Frogs use a viscoelastic tongue and non-Newtonian saliva to catch prey

PubMed Central

Noel, Alexis C.; Guo, Hao-Yuan; Mandica, Mark

2017-01-01

Frogs can capture insects, mice and even birds using only their tongue, with a speed and versatility unmatched in the world of synthetic materials. How can the frog tongue be so sticky? In this combined experimental and theoretical study, we perform a series of high-speed films, material tests on the tongue, and rheological tests of the frog saliva. We show that the tongue's unique stickiness results from a combination of a soft, viscoelastic tongue coupled with non-Newtonian saliva. The tongue acts like a car's shock absorber during insect capture, absorbing energy and so preventing separation from the insect. The shear-thinning saliva spreads over the insect during impact, grips it firmly during tongue retraction, and slides off during swallowing. This combination of properties gives the tongue 50 times greater work of adhesion than known synthetic polymer materials such as the sticky-hand toy. These principles may inspire the design of reversible adhesives for high-speed application. PMID:28148766

An evaluation of two flat-black silicone paints for space application

NASA Technical Reports Server (NTRS)

Clatterbuck, Carroll H.; Scialdone, John J.

1990-01-01

Tests were conducted on two flat-black silicone paints suggested for space applications to determine their optical, electrical, and mechanical properties. Three different types of substrate materials were chosen for these paint tests; the application of the paints onto the primed substrates was carried out by spray coating. The adhesion properties were verified by thermal shock and sudden immersion into liquid nitrogen. A controlled thermal vacuum tests was also carried out by varying the temperature of the paint from -100 to 225 C. The measured optical properties included normal and hemispherical emittance, and solar absorption/reflectance. A simultaneous exposure to low-energy proton/UV irradiation in vacuum, and high-energy proton/electron irradiation was carried out. Additional tests of the paints are described.

Suppression of complement regulatory protein C1 inhibitor in vascular endothelial activation by inhibiting vascular cell adhesion molecule-1 action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Haimou; Qin, Gangjian; Liang, Gang

Increased expression of adhesion molecules by activated endothelium is a critical feature of vascular inflammation associated with the several diseases such as endotoxin shock and sepsis/septic shock. Our data demonstrated complement regulatory protein C1 inhibitor (C1INH) prevents endothelial cell injury. We hypothesized that C1INH has the ability of an anti-endothelial activation associated with suppression of expression of adhesion molecule(s). C1INH blocked leukocyte adhesion to endothelial cell monolayer in both static assay and flow conditions. In inflammatory condition, C1INH reduced vascular cell adhesion molecule (VCAM-1) expression associated with its cytoplasmic mRNA destabilization and nuclear transcription level. Studies exploring the underlying mechanismmore » of C1INH-mediated suppression in VCAM-1 expression were related to reduction of NF-{kappa}B activation and nuclear translocation in an I{kappa}B{alpha}-dependent manner. The inhibitory effects were associated with reduction of inhibitor I{kappa}B kinase activity and stabilization of the NF-{kappa}B inhibitor I{kappa}B. These findings indicate a novel role for C1INH in inhibition of vascular endothelial activation. These observations could provide the basis for new therapeutic application of C1INH to target inflammatory processes in different pathologic situations.« less

Heat shock proteins HSP70 and MRJ cooperatively regulate cell adhesion and migration through urokinase receptor.

PubMed

Lin, Yuli; Peng, Nana; Zhuang, Hongqin; Zhang, Di; Wang, Yao; Hua, Zi-Chun

2014-08-30

The urokinase-type plasminogen activator receptor (uPAR) is an important regulator of ECM proteolysis, cell-ECM interactions and cell signaling. uPAR and heat shock proteins HSP70 and MRJ (DNAJB6) have been implicated in tumor growth and metastasis. We have reported recently that MRJ (DNAJB6, a heat shock protein) can interact with uPAR and enhance cell adhesion. Here, we identified another heat shock protein HSP70 as a novel uPAR-interacting protein. We performed co-immunoprecipitation in human embryonic kidney (HEK) 293 and colon cancer HCT116 cells as well as immunofluorence assays in HEK293 cells stably transfected with uPAR to investigate the association of suPAR with HSP70/MRJ. To understand the biological functions of the triple complex of suPAR/HSP70/MRJ, we determined whether HSP70 and/or MRJ regulated uPAR-mediated cell invasion, migration, adhesion to vitronectin and MAPK pathway in two pair of human tumor cells (uPAR negative HEK293 cells vs HEK293 cells stably transfected with uPAR and HCT116 cells stably transfected with antisense-uPAR vs HCT116 mock cells transfected with vector only) using transwell assay, wound healing assay, quantitative RT-PCR analyzing mmp2 and mmp9 transcription levels, cell adhesion assay and Western blotting assay. HSP70 and MRJ formed a triple complex with uPAR and over-expression of MRJ enhanced the interaction between HSP70 and uPAR, while knockdown of MRJ decreased soluble uPAR in HCT116 cells (P < 0.05) and reduced the formation of the triple complex, suggesting that MRJ may act as an uPAR-specific adaptor protein to link uPAR to HSP70. Further experiments showed that knockdown of HSP70 and/or MRJ by siRNA inhibited uPAR-mediated cell adhesion to vitronectin as well as suppressed cell invasion and migration. Knockdown of HSP70 and/or MRJ inhibited expression of invasion related genes mmp2 and mmp9. Finally, HSP70 and/or MRJ up-regulated phosphorylation levels of ERK1/2 and FAK suggesting MAPK pathway was involved. All the biological function experiments in cell level showed an additive effect when HSP70 and MRJ were regulated simultaneously indicating their collaborated regulation effects on uPAR. These findings may offer a novel insight into the interactions between uPAR and HSP70/MRJ and their functions in cell adhesion and migration may provide more understanding of the roles in regulating cancer metastasis.

Effects of n-acetylcysteine in a rat model of ischemia and reperfusion injury.

PubMed

Cuzzocrea, S; Mazzon, E; Costantino, G; Serraino, I; De Sarro, A; Caputi, A P

2000-08-18

Splanchnic artery occlusion shock (SAO) causes an enhanced formation of reactive oxygen species (ROS), which contribute to the pathophysiology of shock. Here we have investigated the effects of n-acetylcysteine (NAC), a free radical scavenger, in rats subjected to SAO shock. Treatment of rats with NAC (applied at 20 mg/kg, 5 min prior to reperfusion, followed by an infusion of 20 mg/kg/h) attenuated the mean arterial blood and the migration of polymorphonuclear cells (PMNs) caused by SAO-shock. NAC also attenuated the ileum injury (histology) as well as the increase in the tissue levels of myeloperoxidase (MPO) and malondialdehyde (MDA) caused by SAO shock in the ileum. There was a marked increase in the oxidation of dihydrorhodamine 123 to rhodamine in the plasma of the SAO-shocked rats after reperfusion. Immunohistochemical analysis for nitrotyrosine and for poly(ADP-ribose) synthetase (PARS) revealed a positive staining in ileum from SAO-shocked rats. The degree of staining for nitrotyrosine and PARS were markedly reduced in tissue sections obtained from SAO-shocked rats which had received NAC. Reperfused ileum tissue sections from SAO-shocked rats showed positive staining for P-selectin, which was mainly localised in the vascular endothelial cells. Ileum tissue section obtained from SAO-shocked rats with anti-intercellular adhesion molecule (ICAM-1) antibody showed a diffuse staining. NAC treatment markedly reduced the intensity and degree of P-selectin and ICAM-1 in tissue section from SAO-shocked rats. In addition, in ex vivo studies in aortic rings from shocked rats, we found reduced contractions to noradrenaline and reduced responsiveness to a relaxant effect to acetylcholine (vascular hyporeactivity and endothelial dysfunction, respectively). NAC treatment improved contractile responsiveness to noradrenaline, enhanced the endothelium-dependent relaxations and significantly improved survival. Taken together, our results clearly demonstrate that NAC treatment exert a protective effect and part of this effect may be due to inhibition of the expression of adhesion molecule and peroxynitrite-related pathways and subsequent reduction of neutrophil-mediated cellular injury.

Time-dependent effect of clonidine on microvascular permeability during endotoxemia.

PubMed

Schmidt, Karsten; Hernekamp, Jochen Frederick; Philipsenburg, Christoph; Zivkovic, Aleksandar R; Brenner, Thorsten; Hofer, Stefan

2015-09-01

Endothelial leakage with accompanying tissue edema and increased leukocyte adhesion are characteristics of the vascular inflammatory response. Tissue edema formation is a key mechanism in sepsis pathophysiology contributing to impaired tissue oxygenation and the development of shock. Sepsis mortality is directly associated with the severity of these microcirculatory alterations. Dysfunction of the sympathetic nervous system can have deleterious effects in generalized inflammation. This study evaluated the effect of the adrenergic alpha 2 agonist clonidine on microvascular permeability and leukocyte adhesion during endotoxemia. Macromolecular leakage, leukocyte adhesion, and venular wall shear rate were examined in mesenteric postcapillary venules of rats by using intravital microscopy (IVM). Lipopolysaccharide (LPS) (4mg/kg/h) or equivalent volumes of saline were continuously infused following baseline IVM at 0min. IVM was repeated after 60 and 120min in endotoxemic and nonendotoxemic animals. Clonidine (10μg/kg) was applied as an i.v. bolus. Animals received either (i) saline alone, (ii) clonidine alone, (iii) clonidine 45min prior to LPS, (iv) clonidine 10min prior to LPS, (v) clonidine 30min after LPS, or (vi) LPS alone. Due to nonparametric data distribution, Wilcoxon test and Dunn's multiple comparisons test were used for data analysis. Data were considered statistically significant at p<0.05. LPS significantly increased microvascular permeability and leukocyte adhesion and decreased venular wall shear rate. Clonidine significantly reduced microvascular permeability when applied 45min before or 30min after LPS administration. Leukocyte adhesion and venular wall shear rate were not affected by clonidine during endotoxemia. Clonidine reduces microvascular permeability in endotoxemic animals in a time-dependent manner. Adrenergic alpha 2 agonists might prove beneficial in stabilizing capillary leakage during inflammation. Copyright © 2015 Elsevier Inc. All rights reserved.

Abrupt reflow enhances cytokine-induced proinflammatory activation of endothelial cells during simulated shock and resuscitation.

PubMed

Li, Ranran; Zijlstra, Jan G; Kamps, Jan A A M; van Meurs, Matijs; Molema, Grietje

2014-10-01

Circulatory shock and resuscitation are associated with systemic hemodynamic changes, which may contribute to the development of MODS (multiple organ dysfunction syndrome). In this study, we used an in vitro flow system to simulate the consecutive changes in blood flow as occurring during hemorrhagic shock and resuscitation in vivo. We examined the kinetic responses of different endothelial genes in human umbilical vein endothelial cells preconditioned to 20 dyne/cm unidirectional laminar shear stress for 48 h to flow cessation and abrupt reflow, respectively, as well as the effect of flow cessation and reflow on tumor necrosis factor-α (TNF-α)-induced endothelial proinflammatory activation. Endothelial CD31 and VE-cadherin were not affected by the changes in flow in the absence or presence of TNF-α. The messenger RNA levels of proinflammatory molecules E-selectin, VCAM-1 (vascular cell adhesion molecule 1), and IL-8 (interleukin 8) were significantly induced by flow cessation respectively acute reflow, whereas ICAM-1 (intercellular adhesion molecule 1) was downregulated on flow cessation and induced by subsequent acute reflow. Flow cessation also affected the Ang/Tie2 (Angiopoietin/Tie2 receptor tyrosine kinase) system by downregulating Tie2 and inducing its endothelial ligand Ang2, an effect that was further extended on acute reflow. Furthermore, the induction of proinflammatory adhesion molecules by TNF-α under flow cessation was significantly enhanced on subsequent acute reflow. This study demonstrated that flow alterations per se during shock and resuscitation contribute to endothelial activation and that these alterations interact with proinflammatory factors coexisting in vivo such as TNF-α. The abrupt reflow-related enhancement of cytokine-induced endothelial proinflammatory activation supports the concept that sudden regain of flow during resuscitation has an aggravating effect on endothelial activation, which may play a significant role in vascular dysfunction and consequent organ injury. This study implies that the improvement of resuscitation strategies and the pharmacological interference with proinflammatory signaling cascades at the right time of resuscitation of shock patients may be beneficial to regain and/or maintain organ function in patients after circulatory shock.

Heat shock protein antagonists in early stage clinical trials for NSCLC.

PubMed

Hendriks, Lizza E L; Dingemans, Anne-Marie C

2017-05-01

Cancer cells have a higher need of chaperones than normal cells to prevent the toxic effects of intracellular protein misfolding and aggregation. Heat shock proteins (Hsps) belong to these chaperones; they are classified into families according to molecular size. Hsps are upregulated in many cancers and inhibition can inhibit tumor growth by destabilizing proteins necessary for tumor survival. In non-small cell lung cancer (NSCLC), there are three different Hsp antagonist classes that are in (early) clinical trials: Hsp90, Hsp70 and Hsp27 inhibitors. Areas covered: The rationale to use Hsp inhibitors in NSCLC will be summarized and phase I-III trials will be reviewed. Expert opinion: Several Hsp90 inhibitors have been tested in phase I-III trials, until now none was positive in unselected NSCLC; therefore development of AUY922, ganetespib and retaspimycin was halted. Results seem more promising in molecularly selected patients, especially in ALK-rearranged NSCLC. Hsp27 is overexpressed in squamous NSCLC and is a mechanism of chemotherapy resistance. The Hsp27 inhibitor apatorsen is now tested in squamous NSCLC. No phase II/III data are known for Hsp70 inhibitors. Combination of Hsp inhibitors with heat shock transcription factor 1 inhibitors or focal adhesion kinase inhibitors might be of interest for future trials.

Investigation of Coatings Which Prevent Molten Aluminum/Water Explosions

NASA Astrophysics Data System (ADS)

León, D. D.; Richter, R. T.; Levendusky, T. L.

The Aluminum Association contracted Alcoa in 1995 to identify and test new protective coatings for casting pits as a replacement for Porter International's 7001 (Tarset Standard). Three new coatings have been identified through a series of selection criteria including: 1) A standardized splash test used to evaluate personal protective clothing, 2) An industry-standard molten metal explosion test, 3) A multiple-exposure test to measure durability, and 4) An external shock impact test. The results of this program will be reviewed. This study only tested protective coatings at the "in-service cure time", as defined by the manufacturer. These curing times can be excessive for a production casting facility. The Aluminum Association has contracted Alcoa in a second program to investigate the effect of reduced cure times on adhesion and their effectiveness in preventing molten metal/water explosions. A status update of this new two year program is provided.

Improved extraction of ePTFE and medical adhesive modified defibrillation leads from the coronary sinus and great cardiac vein.

PubMed

Wilkoff, Bruce L; Belott, Peter H; Love, Charles J; Scheiner, Avram; Westlund, Randy; Rippy, Marian; Krishnan, Mohan; Norlander, Barry E; Steinhaus, Bruce; Emmanuel, Janson; Zeller, Peter J

2005-03-01

Permanent leads with shocking coils for defibrillation therapy are sometimes implanted in the coronary sinus (CS) and great cardiac vein (GCV). These shocking coils, as documented by pathologic examination of animal investigations, often become tightly encapsulated by fibrosis and can be very difficult to remove. One of three configurations of the Guidant model 7109 Perimeter coronary sinus shocking lead was implanted into the distal portion of the GCV of 24 sheep for up to 14 months. Group 1 had unmodified coils (control), group 2 had coils backfilled with medical adhesive (MA), and Group 3 had coils coated with expanded polytetrafluoroethylene (ePTFE). Eighteen leads, three from each group at 6 and 14 months were transvenously extracted from the left jugular vein. The remaining six animals were not subject to extraction. All animals were euthanized for pathological and microscopic examination. All six of the control, three of the MA, and one of the ePTFE leads required the use of an electrosurgical dissection sheath (EDS) for extraction. Five control, two MA, and none of the ePTFE leads had significant fibrotic attachments to the shocking coils. Significant trauma was observed at necropsy for those leads requiring the use of the EDS for extraction. Tissue ingrowth is a major impediment to the removal of defibrillation leads implanted in the CS and GCV of sheep. Reduction of tissue ingrowth by coating the shocking coils with ePTFE or by backfilling with MA facilitates transvenous lead removal with reduced tissue trauma.

Mechanisms of Thrombocytopenia During Septic Shock: A Multiplex Cluster Analysis of Endogenous Sepsis Mediators.

PubMed

Bedet, Alexandre; Razazi, Keyvan; Boissier, Florence; Surenaud, Mathieu; Hue, Sophie; Giraudier, Stéphane; Brun-Buisson, Christian; Mekontso Dessap, Armand

2018-06-01

Thrombocytopenia is a common feature of sepsis and may involve various mechanisms often related to the inflammatory response. This study aimed at evaluating factors associated with thrombocytopenia during human septic shock. In particular, we used a multiplex analysis to assess the role of endogenous sepsis mediators. Prospective, observational study. Thrombocytopenia was defined as an absolute platelet count <100 G/L or a 50% relative decrease in platelet count during the first week of septic shock. Plasma concentrations of 27 endogenous mediators involved in sepsis and platelet pathophysiology were assessed at day-1 using a multi-analyte Milliplex human cytokine kit. Patients with underlying diseases at risk of thrombocytopenia (hematological malignancies, chemotherapy, cirrhosis, and chronic heart failure) were excluded. Thrombocytopenia occurred in 33 (55%) of 60 patients assessed. Patients with thrombocytopenia were more prone to present with extrapulmonary infections and bacteremia. Disseminated intravascular coagulation was frequent (81%) in these patients. Unbiased hierarchical clustering identified five different clusters of sepsis mediators, including one with markers of platelet activation (e.g., thrombospondin-1) positively associated with platelet count, one with markers of inflammation (e.g., tumor necrosis factor alpha and heat shock protein 70), and endothelial dysfunction (e.g., intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) negatively associated with platelet count, and another involving growth factors of thrombopoiesis (e.g., thrombopoietin), also negatively associated with platelet count. Surrogates of hemodilution (e.g., hypoprotidemia and higher fluid balance) were also associated with thrombocytopenia. Multiple mechanisms seemed involved in thrombocytopenia during septic shock, including endothelial dysfunction/coagulopathy, hemodilution, and altered thrombopoiesis.

Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

PubMed Central

Lu, Zhe; Myoung, Sang-Won; Jung, Yeon-Gil; Balakrishnan, Govindasamy; Lee, Jeongseung; Paik, Ungyu

2013-01-01

The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs) was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF) for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray (APS) method showed a good condition at the interface between the top and bond coats after cyclic furnace thermal fatigue (CFTF) for 1429 cycles, whereas the TBCs with the bond coats prepared by the high-velocity oxygen fuel (HVOF) and low-pressure plasma spray (LPPS) methods showed a partial cracking (and/or delamination) and a delamination after 780 cycles, respectively. The TBCs with the bond coats prepared by the APS, HVOF and LPPS methods were fully delaminated (>50%) after 159, 36, and 46 cycles, respectively, during the thermal-shock tests. The TGO thickness in the TBCs was strongly dependent on the both exposure time and temperature difference tested. The hardness values were found to be increased only after the CFTF, and the TBC with the bond coat prepared by the APS showed the highest adhesive strength before and after the FTF. PMID:28811441

Laser shock peening studies on SS316LN plate with various sacrificial layers

NASA Astrophysics Data System (ADS)

Yella, Pardhu; Venkateswarlu, P.; Buddu, Ramesh K.; Vidyasagar, D. V.; Sankara Rao, K. Bhanu; Kiran, P. Prem; Rajulapati, Koteswararao V.

2018-03-01

Laser shock peening (LSP) has been utilized to modify the surface characteristics of SS316LN plates of 6 mm thickness. Laser pulse widths employed are 30 ps and 7 ns and the laser energy was varied in the range 5-90 mJ. Peening was performed in direct ablation mode as well as with various sacrificial layers such as black paint, transparent adhesive tape and absorbing adhesive tape. The surface characteristics were greatly influenced by the type of sacrificial layer employed. The average surface roughness values are about 0.4 μm when the black paint and transparent adhesive tape were used as sacrificial layers. In contrast to this, using absorbent adhesive tape as a sacrificial layer has resulted in an average surface roughness of about 0.04 μm. Irrespective of pulse durations (30 ps or 7 ns), absorbent adhesive tape has always resulted in compressive residual stresses whereas other layers appear to be not that effective. In case of 30 ps pulse, as the laser energy was increased from 5 mJ to 25 mJ, there was a texture observed in (111) reflection of X-ray diffractograms and the center of the peak has also gradually shifted to left. X-ray line profile analysis suggests that with the increase in laser energy, lattice microstrain also has increased. This lattice microstrain appears to be resulting from the increased dislocation density in the peened sample as evidenced during transmission electron microscopic investigations. Cross-sectional scanning electron microscopy performed on peened samples suggests that absorbing adhesive tape brings no surface damage to the samples whereas other sacrificial layers have resulted in some surface damage. Based on all these structural and microstructural details, it is recommended that absorbent tape could be used as a sacrificial layer during LSP process which induces surface residual stresses with no damage to the sample surface.

On the Material Characterisation of Wind Turbine Blade Coatings: The Effect of Interphase Coating–Laminate Adhesion on Rain Erosion Performance

PubMed Central

Cortés, Enrique; Sánchez, Fernando; Madramany, Borja

2017-01-01

Rain erosion damage, caused by repeated droplet impact on wind turbine blades, is a major cause for concern, even more so at offshore locations with larger blades and higher tip speeds. Due to the negative economic influence of blade erosion, all wind turbine Original Equipment Manufacturers (OEMs) are actively seeking solutions. In most cases, since the surface coating plays a decisive role in the blade manufacture and overall performance, it has been identified as an area where a solution may be obtained. In this research, two main coating technologies have been considered: In-mould coatings (Gel coating) applied during moulding on the entire blade surface and the post-mould coatings specifically developed for Leading Edge Protection (LEP). The coating adhesion and erosion is affected by the shock waves created by the collapsing water droplets on impact. The stress waves are reflected and transmitted to the laminate substrate, so microstructural discontinuities in coating layers and interfaces play a key role on its degradation and may accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations based on their potential stress reduction on the interface. Nevertheless, in order to use them, it is necessary to measure the contact adhesion resistance of the multi-layered system interfaces. The rain erosion performance is assessed using an accelerated testing technique, whereby the test material is repeatedly impacted at high speed with water droplets in a Whirling Arm Rain Erosion Rig (WARER). The materials, specifically the coating–laminate interphase region and acoustic properties, are further characterised by several laboratory tests, including Differential Scanning Calorimetry (DSC), pull-off testing, peeling–adhesion testing and nanoindentation testing. This body of work includes a number of case studies. The first case study compares two of the main coating technologies used in industry (i.e., gel coating and LEP); the second case investigates the effects of the in-mould gel coating curing; and the third considers the inclusion of a primer layer on a LEP configuration system. Following these case studies, the LEP is found to be a far superior coating due to its appropriate mechanical and acoustic properties and the interface between the coating and the substrate is highlighted as a key aspect, as poor adhesion can lead to delamination and, ultimately, premature failure of the coating. PMID:28956841

On the Material Characterisation of Wind Turbine Blade Coatings: The Effect of Interphase Coating-Laminate Adhesion on Rain Erosion Performance.

PubMed

Cortés, Enrique; Sánchez, Fernando; O'Carroll, Anthony; Madramany, Borja; Hardiman, Mark; Young, Trevor M

2017-09-28

Rain erosion damage, caused by repeated droplet impact on wind turbine blades, is a major cause for concern, even more so at offshore locations with larger blades and higher tip speeds. Due to the negative economic influence of blade erosion, all wind turbine Original Equipment Manufacturers (OEMs) are actively seeking solutions. In most cases, since the surface coating plays a decisive role in the blade manufacture and overall performance, it has been identified as an area where a solution may be obtained. In this research, two main coating technologies have been considered: In-mould coatings (Gel coating) applied during moulding on the entire blade surface and the post-mould coatings specifically developed for Leading Edge Protection (LEP). The coating adhesion and erosion is affected by the shock waves created by the collapsing water droplets on impact. The stress waves are reflected and transmitted to the laminate substrate, so microstructural discontinuities in coating layers and interfaces play a key role on its degradation and may accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations based on their potential stress reduction on the interface. Nevertheless, in order to use them, it is necessary to measure the contact adhesion resistance of the multi-layered system interfaces. The rain erosion performance is assessed using an accelerated testing technique, whereby the test material is repeatedly impacted at high speed with water droplets in a Whirling Arm Rain Erosion Rig (WARER). The materials, specifically the coating-laminate interphase region and acoustic properties, are further characterised by several laboratory tests, including Differential Scanning Calorimetry (DSC), pull-off testing, peeling-adhesion testing and nanoindentation testing. This body of work includes a number of case studies. The first case study compares two of the main coating technologies used in industry (i.e., gel coating and LEP); the second case investigates the effects of the in-mould gel coating curing; and the third considers the inclusion of a primer layer on a LEP configuration system. Following these case studies, the LEP is found to be a far superior coating due to its appropriate mechanical and acoustic properties and the interface between the coating and the substrate is highlighted as a key aspect, as poor adhesion can lead to delamination and, ultimately, premature failure of the coating.

Two simple techniques for the safe Sarcoptes collection and individual mite DNA extraction.

PubMed

Soglia, Dominga; Rambozzi, Luisa; Maione, Sandra; Spalenza, Veronica; Sartore, Stefano; Alasaad, Samer; Sacchi, Paola; Rossi, Luca

2009-10-01

Availability of mites is a recognized limiting factor of biological and genetic investigations of the genus Sarcoptes. Current methods of deoxyribonucleic acid (DNA) extraction from individual mites also need substantial improvement in efficiency and operator friendliness. We have first developed a technique for efficient and safe extraction of living mites from scabietic skin samples (crusts or deep skin scrapings). Its core device is a large plastic syringe connected with a 1.5-ml Eppendorf tube. The source material is introduced in the syringe and the device in a shoe box with the tip half of the tube emerging. Mites migrate towards a heat source during a minimum of 36 h. Then, the tube is detached and the mites utilized without risks for the operators. A second technique allows operator-friendly manipulation of individual mites for DNA extraction. Fixed mites are isolated by adhesion to a small strip of polyvinyl chloride (PVC) adhesive tape operated with tweezers. Then, mite and strip are plunged in the lyses buffer and the sample twice submitted to thermal shock for disruption of the chitinous exoskeleton. Data show that the tape does not interfere with successive DNA extraction with a commercial kit. The corresponding protocol, that we briefly name "PVC adhesive tape + thermal shock + kit DNA extraction," compares favorably with the available ones.

Influence of Silicate Concentration in Electrolyte on the Growth and Performance of Plasma Electrolytic Oxidation Coatings Prepared on Low Carbon Steel

NASA Astrophysics Data System (ADS)

Yang, Wenbin; Peng, Zhenjun; Liu, Baixing; Liu, Weimin; Liang, Jun

2018-04-01

Plasma electrolytic oxidation (PEO) coatings were prepared on low carbon steel from electrolytes with different silicate concentrations. The microstructure, elemental and phase compositions of the PEO coatings were analyzed by scanning electron microscope, energy-dispersive spectrometer, and x-ray diffraction, respectively. The adhesion of PEO coatings with low carbon steel substrate was qualitatively examined by thermal shock tests. The tribological properties were evaluated by a reciprocating tribometer sliding against a Si3N4 ceramic ball. The corrosion behaviors of PEO coatings were investigated in 3.5 wt.% NaCl solution by electrochemical impedance spectra and potentiodynamic polarization. Results indicated that all the PEO coatings were comprised of amorphous SiO2 and Fe-containing oxides; however, the silicate concentration in electrolyte showed significant influence on the growth and the performance of PEO coatings. The PEO coating prepared from the electrolyte with silicate concentration of 30 g/L had the highest Fe content because the substrate was more readily oxidized and showed a dense structure, resulting in the best comprehensive performance of adhesion, wear resistance, and corrosion resistance.

Influence of Silicate Concentration in Electrolyte on the Growth and Performance of Plasma Electrolytic Oxidation Coatings Prepared on Low Carbon Steel

NASA Astrophysics Data System (ADS)

Yang, Wenbin; Peng, Zhenjun; Liu, Baixing; Liu, Weimin; Liang, Jun

2018-05-01

Plasma electrolytic oxidation (PEO) coatings were prepared on low carbon steel from electrolytes with different silicate concentrations. The microstructure, elemental and phase compositions of the PEO coatings were analyzed by scanning electron microscope, energy-dispersive spectrometer, and x-ray diffraction, respectively. The adhesion of PEO coatings with low carbon steel substrate was qualitatively examined by thermal shock tests. The tribological properties were evaluated by a reciprocating tribometer sliding against a Si3N4 ceramic ball. The corrosion behaviors of PEO coatings were investigated in 3.5 wt.% NaCl solution by electrochemical impedance spectra and potentiodynamic polarization. Results indicated that all the PEO coatings were comprised of amorphous SiO2 and Fe-containing oxides; however, the silicate concentration in electrolyte showed significant influence on the growth and the performance of PEO coatings. The PEO coating prepared from the electrolyte with silicate concentration of 30 g/L had the highest Fe content because the substrate was more readily oxidized and showed a dense structure, resulting in the best comprehensive performance of adhesion, wear resistance, and corrosion resistance.

The use of silicone based adhesives to encapsulate manganin gauges for high stress experiments

NASA Astrophysics Data System (ADS)

Be'Ery, Ilan; Rosenberg, Zvi

2007-06-01

The use of commercial manganin stress gauges has been limited to stresses in the range of 0-20 GPa due to the short-circuiting of their encapsulating materials (epoxy, Kapton) at higher pressures. Researchers at Lawrence Livermore overcome this difficulty by embedding their gauges in Teflon sheets and measured shock pressures as high as 40 GPa. The fact that Teflon can keep its resistivity at high pressures is attributed to the lack of benzene rings in its structure. On the other hand, Teflon is difficult to work with as an encapsulating material because of its poor adhesive properties. In order to overcome this difficulty we encapsulated our foils in between two tapes of Teflon which have a silicone adhesive glued to it. These are 50 μm thick commercial tapes (manufactured by 3M, type #60) which have a 50 μm thick silicone adhesive (PSA -- pressure sensitive adhesive) on them. This adhesive is easy to work with, has no benzene rings in its structure and has a lower carbon content, compared to other adhesives. Several experiments were conducted in order to directly measure the resistivity of these tapes at high pressures, as well as using them to encapsulate our manganin foils for high pressure studies.

Thermal Characterization of Epoxy Adhesive by Hotfire Testing

NASA Technical Reports Server (NTRS)

Spomer, Ken A.; Haddock, M. Reed; McCool, Alex (Technical Monitor)

2001-01-01

This paper describes subscale solid-rocket motor hot-fire testing of epoxy adhesives in flame surface bondlines to evaluate heat-affected depth, char depth and ablation rate. Hot-fire testing is part of an adhesive down-selection program on the Space Shuttle Solid Rocket Motor Nozzle to provide additional confidence in the down-selected adhesives. The current nozzle structural adhesive bond system is being replaced due to obsolescence. Prior to hot-fire testing, adhesives were tested for chemical, physical and mechanical properties, which resulted in the selection of two potential replacement adhesives, Resin Technology Group's TIGA 321 and 3M's EC2615XLW. Hot-fire testing consisted of four forty-pound charge (FPC) motors fabricated in configurations that would allow side-by-side comparison testing of the candidate replacement adhesives with the current RSRM adhesives. Results of the FPC motor testing show that: 1) the phenolic char depths on radial bondlines is approximately the same and vary depending on the position in the blast tube regardless of which adhesive was used, 2) the replacement candidate adhesive char depths are equivalent to the char depths of the current adhesives, 3) the heat-affected depths of the candidate and current adhesives are equivalent, and 4) the ablation rates for both replacement adhesives were equivalent to the current adhesives.

Frequency of enterotoxins, toxic shock syndrome toxin-1, and biofilm formation genes in Staphylococcus aureus isolates from cows with mastitis in the Northeast of Brazil.

PubMed

Costa, F N; Belo, N O; Costa, E A; Andrade, G I; Pereira, L S; Carvalho, I A; Santos, R L

2018-06-01

Staphylococcus aureus is among the microorganisms more frequently associated with subclinical bovine mastitis. S. aureus may produce several virulence factors. This study aimed at determining the frequency of virulence factors such as enterotoxins, toxic shock syndrome toxin 1, and ica adhesion genes. In addition, we assessed antimicrobial drug resistance in S. aureus isolated from clinical and subclinical cases of mastitis. A total of 88 cows with clinical or subclinical mastitis were sampled, resulting in 38 S. aureus isolates, from which 25 (65.78%) carried toxin genes, including seb, sec, sed, tst, and icaD adhesion gene. These S. aureus isolates belong to 21 ribotypes and three S. aureus strains belonged to the same ribotype producing ica adhesion gene. Approximately 90% of S. aureus strains obtained in our study demonstrated multiple resistance to different antimicrobial agents. The most efficacious antimicrobial agents against the isolates were gentamicin, amoxicillin, and norfloxacin. Gentamicin was the most efficacious agent inhibiting 78.95% of the S. aureus isolates. The least efficacious were penicillin, streptomycin, and ampicillin. Our results can help in understanding the relationship between virulence factors and subclinical mastitis caused by S. aureus. Further research about diversity of S. aureus isolates and genes responsible for the pathogenicity of subclinical mastitis is essential.

Effect of the combination of fibrin glue and growth hormone on intestinal anastomoses in a pig model of traumatic shock associated with peritonitis.

PubMed

Wang, Pengfei; Wang, Jian; Zhang, Wenbo; Li, Yousheng; Li, Jieshou

2009-03-01

Intra-abdominal sepsis and hemorrhagic shock have been found to impair the healing of intestinal anastomoses. The present study examined whether fibrin glue (FG) and recombinant human growth hormone (GH) can improve intestinal primary anastomotic healing in a pig model of traumatic shock associated with peritonitis. Further, the study was designed to investigate the probable mechanism of these agents. Female anesthetized pigs were divided into five groups. Group sham (n = 7), pigs without traumatic shock had small bowel resection anastomoses; group control (n = 14), pigs had bowel resection anastomoses 24 h after abdominal gunshot plus exsanguination/resuscitation; group FG (n = 14); group GH (n = 14); group FG/GH (n = 14), pigs received FG, recombinant GH, or both, respectively. Recombinant GH was given daily for 7 days. Blood samples were collected daily for measurement of interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha levels. Investigations also included adhesion formation, anastomotic bursting pressure, tensile strength, hydroxyproline (HP) content, myeloperoxidase (MPO), tumor necrosis factor (NF)-kappaB activity, and histology analysis 10 days later. A second experiment (n = 20 subjects assigned to each of the five groups) was designed to study survival during the first 20 postoperative days. Traumatic shock associated with peritonitis led to significant decreases in intestinal anastomotic bursting pressures, tensile strengths, and tissue hydroxyproline content, along with severe adhesion formation, increases in MPO activity and NF-kappaB activity, and plasma levels of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6). Both FG and recombinant GH treatment led to early significant increases in plasma levels of TNF-alpha and IL-6. At the same time, FG alone, unlike recombinant GH alone, led to significant increases in anastomotic bursting pressures, tensile strength, and tissue HP content, along with decreases in anastomotic MPO and NF-kappaB activity and later plasma levels of TNF-a and IL-6. The FG group also developed more marked neoangiogenesis and collagen deposition on histology analysis. However, FG and recombinant GH synergistically effected improved anastomotic healing, abolishing the infaust effects promoted by recombinant GH. Adhesion formation after intestinal anastomosis could not be lowered by FG alone or by the combination of FG and recombinant GH. Both FG alone and FG/GH, in contrast to GH alone and control treatment, significantly prolonged the survival time of experimental animals. We found that FG, but not recombinant GH, could lower the risk of anastomotic leakage, improve intestinal anastomotic healing, and prolong survival in a pig model of traumatic shock associated with peritonitis. Both FG and recombinant GH synergistically effected improved intestinal anastomotic healing. It was suggested that GH could be used locally to promote intestinal anastomotic healing in intra-abdominal peritonitis.

Effects of physical and nutritional stress conditions during mycelial growth on conidial germination speed, adhesion to host cuticle, and virulence of Metarhizium anisopliae, an entomopathogenic fungus.

PubMed

Rangel, Drauzio E N; Alston, Diane G; Roberts, Donald W

2008-11-01

Growth under stress may influence pathogen virulence and other phenotypic traits. Conidia of the entomopathogenic fungus Metarhizium anisopliae var. anisopliae (isolate ARSEF 2575) were produced under different stress conditions and then examined for influences on in vitro conidial germination speed, adhesion to the insect cuticle, and virulence to an insect host, Tenebrio molitor. Conidia were produced under non-stress conditions [on potato-dextrose agar plus 1gl(-1) yeast extract (PDAY; control)], or under the following stress conditions: osmotic (PDAY+sodium chloride or potassium chloride, 0.6 or 0.8m); oxidative [(PDAY+hydrogen peroxide, 5mm) or UV-A (irradiation of mycelium on PDAY)]; heat shock (heat treatment of mycelium on PDAY at 45 degrees C, 40min); and nutritive [minimal medium (MM) with no carbon source, or on MM plus 3gl(-1) lactose (MML)]. Conidia were most virulent (based on mortality at 3d) and had the fastest germination rates when produced on MML, followed by MM. In addition, conidial adhesion to host cuticle was greatest when the conidia were produced on MML. Media with high osmolarity (0.8m) produced conidia with slightly elevated virulence and faster germination rates than conidia produced on the control medium (PDAY), but this trend did not hold for media with the lower osmolarity, (0.6m). Conidia produced from mycelium irradiated with UV-A while growing on PDAY had somewhat elevated virulence levels similar to that of conidia produced on MM, but their germination rate was not increased. Hydrogen peroxide and heat shock treatments did not alter virulence. These results demonstrate that the germination, adhesion and virulence of M. anisopliae conidia can be strongly influenced by culture conditions (including stresses) during production of the conidia.

Silver-Teflon coating improvement

NASA Technical Reports Server (NTRS)

Reed, M. W.

1976-01-01

Approximately forty adhesives were subjected to laboratory screening. Seven candidate adhesives were selected from the screening tests and evaluated in a thermal vacuum test on radiator panels similar to the anticipated flight hardware configuration. Several classes of adhesives based on epoxide, polyester, silicone, and urethane resin systems were tested. These included contact adhesives, heat cured adhesives, heat and pressure cured adhesives, pressure sensitive adhesives, and two part paint-on or spray-on adhesives. The panels were tested in a space environmental simulation laboratory chamber during the July 9-20, 1973 time span.

Evaluation of a metering, mixing, and dispensing system for mixing polysulfide adhesive

NASA Technical Reports Server (NTRS)

Evans, Kurt B.

1989-01-01

Tests were performed to evaluate whether a metered mixing system can mix PR-1221 polysulfide adhesive as well as or better than batch-mixed adhesive; also, to evaluate the quality of meter-mixed PR-1860 and PS-875 polysulfide adhesives. These adhesives are candidate replacements for PR-1221 which will not be manufactured in the future. The following material properties were evaluated: peel strength, specific gravity and adhesive components of mixed adhesives, Shore A hardness, tensile adhesion strength, and flow rate. Finally, a visual test called the butterfly test was performed to observe for bubbles and unmixed adhesive. The results of these tests are reported and discussed.

A method to determine shear adhesive strength of fibrin sealants.

PubMed

Sierra, D H; Feldman, D S; Saltz, R; Huang, S

1992-01-01

The adhesive strength of fibrin sealants has not been rigorously evaluated to date. The adhesive strength of six different concentrations of cryoprecipitated fibrinogen as well as the commercially available fibrin tissue adhesive Tissucol was tested under controlled conditions utilizing split-thickness skin grafts as the test adherand. This test configuration permitted the modeling of bonding strength for attachment of skin grafts as well as incorporate established engineering test standards for adhesives. An increase in fibrin concentration corresponded with an increase in shear adhesive strength. No significant increases in adhesive strength were attained after 5 min of bonding for all tested concentrations, except for the commercial adhesive, which attained the adhesive strength of an equivalent concentration of cryoprecipitated adhesive after 90 min. The adhesive strength, however, was an order of magnitude less than reported values of the tensile strength of fibrin material for similar concentrations. Therefore, it is important that the surgeon use a sufficiently high fibrinogen concentration for the specific clinical indication. The method of fibrin sealant preparation and/or the compounding adjuncts appear to have an effect on the development of adhesive strength.

Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive

NASA Technical Reports Server (NTRS)

Hernandez, Alan; Hess, Daniel P.

2016-01-01

This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48-hour cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for the all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use.

Thermal Characterization of Adhesive

NASA Technical Reports Server (NTRS)

Spomer, Ken A.

1999-01-01

The current Space Shuttle Reusable Solid Rocket Motor (RSRM) nozzle adhesive bond system is being replaced due to obsolescence. Down-selection and performance testing of the structural adhesives resulted in the selection of two candidate replacement adhesives, Resin Technology Group's Tiga 321 and 3M's EC2615XLW. This paper describes rocket motor testing of these two adhesives. Four forty-pound charge motors were fabricated in configurations that would allow side by side comparison testing of the candidate replacement adhesives and the current RSRM adhesives. The motors provided an environment where the thermal performance of adhesives in flame surface bondlines was compared. Results of the FPC testing show that: 1) The phenolic char depths on radial bond lines is approximately the same and vary depending on the position in the blast tube regardless of which adhesive was used; 2) The adhesive char depth of the candidate replacement adhesives is less than the char depth of the current adhesives; 3) The heat-affected depth of the candidate replacement adhesives is less than the heat-affected depth of the current adhesives; and 4) The ablation rates for both replacement adhesives are slower than that of the current adhesives.

Adhesion testing of aircraft tires

NASA Technical Reports Server (NTRS)

Bobo, S. N.

1983-01-01

Adhesion testing appeared to offer a less burdensome alternative to replace some of the dynamometer tests. Accordingly, test results and data were requested from retreaders who had used adhesion testing.

Test report: Shock test of the electron/proton spectrometer structural test unit

NASA Technical Reports Server (NTRS)

Vincent, D. L.

1972-01-01

A shock test of the electron-proton spectrometer structural test unit was conducted. The purpose of the shock test was to verify the structural integrity of the electron-spectrometer design and to obtain data on the shock response of the electronics and electronic housing. The test equipment is described and typical shock response data are provided.

Shock Isolation Elements Testing for High Input Loadings. Volume III. Mechanical Shock Isolation Elements.

DTIC Science & Technology

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*SPRINGS, (*SHOCK(MECHANICS), REDUCTION), TORSION BARS, ELASTOMERS, DAMPING, EQUATIONS OF MOTION, MODEL TESTS, TEST METHODS, NUCLEAR EXPLOSIONS, HARDENING.

21 CFR 864.6650 - Platelet adhesion test.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Platelet adhesion test. 864.6650 Section 864.6650...) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6650 Platelet adhesion test. (a) Identification. A platelet adhesion test is a device used to determine in vitro platelet...

21 CFR 864.6650 - Platelet adhesion test.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Platelet adhesion test. 864.6650 Section 864.6650...) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6650 Platelet adhesion test. (a) Identification. A platelet adhesion test is a device used to determine in vitro platelet...

Manufacturing issues which affect coating erosion performance in wind turbine blades

NASA Astrophysics Data System (ADS)

Cortés, E.; Sánchez, F.; Domenech, L.; Olivares, A.; Young, T. M.; O'Carroll, A.; Chinesta, F.

2017-10-01

Erosion damage, caused by repeated rain droplet impact on the leading edges of wind turbine blades, is a major cause for cost concern. Resin Infusion (RI) is used in wind energy blades where low weight and high mechanical performance materials are demanded. The surface coating plays a crucial role in the manufacturing and performance response. The Leading Edge coating is usually moulded, painted or sprayed onto the blade surface so adequate adhesion in the layers' characterization through the thickness is required for mechanical performance and durability reasons. In the current work, an investigation has been directed into the resulting rain erosion durability of the coating was undertaken through a combination of mass loss testing measurements with manufacturing processing parameter variations. The adhesion and erosion is affected by the shock wave caused by the collapsing water droplet on impact. The stress waves are transmitted to the substrate, so microestructural discontinuities in coating layers and interfaces play a key role on its degradation. Standard industrial systems are based on a multilayer system, with a high number of interfaces that tend to accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations and their potential stress reduction on the interface. In this research, the input parameters for the appropriate definition of the Cohesive Zone Modelling (CZM) of the coating-substrate interface are outlined by means of Pull off testing and Peeling testing results. It allowed one to optimize manufacturing and coating process for blades into a knowledge-based guidance for leading edge coating material development. It was achieved by investigating the erosion degradation process using both numerical and laboratory techniques (Pull off, Peeling and Rain Erosion Testing in a whirling arm rain erosion test facility).

Rigid patterns of effortful choice behavior after acute stress in rats.

PubMed

Hart, Evan E; Stolyarova, Alexandra; Conoscenti, Michael A; Minor, Thomas R; Izquierdo, Alicia

2017-01-01

Physical effort is a common cost of acquiring rewards, and decreased effort is a feature of many neuropsychiatric disorders. Stress affects performance on several tests of cognition and decision making in both humans and nonhumans. Only a few recent reports show impairing effects of stress in operant tasks involving effort and cognitive flexibility. Brain regions affected by stress, such as the medial prefrontal cortex and amygdala, are also implicated in mediating effortful choices. Here, we assessed effort-based decision making after an acute stress procedure known to induce persistent impairment in shuttle escape and elevated plasma corticosterone. In these animals, we also probed levels of polysialyted neural cell adhesion molecule (PSA-NCAM), a marker of structural plasticity, in medial frontal cortex and amygdala. We found that animals that consistently worked for high magnitude rewards continued to do so, even after acute shock stress. We also found that PSA-NCAM was increased in both regions after effortful choice experience but not after shock stress alone. These findings are discussed with reference to the existing broad literature on cognitive effects of stress and in the context of how acute stress may bias effortful decisions to a rigid pattern of responding.

Single cell manipulation utilizing femtosecond laser-induced shock and stress waves

NASA Astrophysics Data System (ADS)

Hosokawa, Yoichiroh

2017-02-01

When an intense femtosecond laser pulse is focused into a culture medium through an objective lens, an impulsive force is loaded on the cells with generations of the shock and stress waves at the laser focal point. The shock and stress waves were acted to single cells in the vicinity of the laser focal point as an impulsive force. We have applied the impulsive force to manipulate single cells. As the transient intensity of the impulsive force is over 1000 times stronger than the force due to optical tweezers, drastic single manipulation which is difficult by the optical tweezers can be realized. The generation process of the impulsive force and behavior of animal cell after loading the impulsive force were reviewed, and then our original quantification method of the impulsive force utilizing atomic force microscope (AFM) was introduced with its applications for evaluating adhesions between animal cells and between sub-organelles in plant cell.

Lap Shear and Impact Testing of Ochre and Beeswax in Experimental Middle Stone Age Compound Adhesives.

PubMed

Kozowyk, P R B; Langejans, G H J; Poulis, J A

2016-01-01

The production of compound adhesives using disparate ingredients is seen as some of the best evidence of advanced cognition outside of the use of symbolism. Previous field and laboratory testing of adhesives has shown the complexities involved in creating an effective Middle Stone Age glue using Acacia gum. However, it is currently unclear how efficient different adhesive recipes are, how much specific ingredients influence their performance, and how difficult it may have been for those ingredients to be combined to maximum effect. We conducted a series of laboratory-based lap shear and impact tests, following modern adhesion testing standards, to determine the efficacy of compound adhesives, with particular regard to the ingredient ratios. We tested rosin (colophony) and gum adhesives, containing additives of beeswax and ochre in varying ratios. During both lap shear and impact tests compound rosin adhesives performed better than single component rosin adhesives, and pure acacia gum was the strongest. The large difference in performance between each base adhesive and the significant changes in performance that occur due to relatively small changes in ingredient ratios lend further support to the notion that high levels of skill and knowledge were required to consistently produce the most effective adhesives.

Lap Shear and Impact Testing of Ochre and Beeswax in Experimental Middle Stone Age Compound Adhesives

PubMed Central

2016-01-01

The production of compound adhesives using disparate ingredients is seen as some of the best evidence of advanced cognition outside of the use of symbolism. Previous field and laboratory testing of adhesives has shown the complexities involved in creating an effective Middle Stone Age glue using Acacia gum. However, it is currently unclear how efficient different adhesive recipes are, how much specific ingredients influence their performance, and how difficult it may have been for those ingredients to be combined to maximum effect. We conducted a series of laboratory-based lap shear and impact tests, following modern adhesion testing standards, to determine the efficacy of compound adhesives, with particular regard to the ingredient ratios. We tested rosin (colophony) and gum adhesives, containing additives of beeswax and ochre in varying ratios. During both lap shear and impact tests compound rosin adhesives performed better than single component rosin adhesives, and pure acacia gum was the strongest. The large difference in performance between each base adhesive and the significant changes in performance that occur due to relatively small changes in ingredient ratios lend further support to the notion that high levels of skill and knowledge were required to consistently produce the most effective adhesives. PMID:26983080

Dynamic testing of airplane shock-absorbing struts

NASA Technical Reports Server (NTRS)

Langer, P; Thome, W

1932-01-01

Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests.

Novel Blood Purification System for Regulating Excessive Immune Reactions in Severe Sepsis and Septic Shock: An Ex Vivo Pilot Study.

PubMed

Hara, Yoshitaka; Shimomura, Yasuyo; Nakamura, Tomoyuki; Kuriyama, Naohide; Yamashita, Chizuru; Kato, Yu; Miyasho, Taku; Sakai, Toshikazu; Yamada, Shingo; Moriyama, Kazuhiro; Nishida, Osamu

2015-08-01

Promising results have been reported with blood purification as adjuvant treatment; however, the immunological mechanisms remain unclear. We have been developing a new blood purification system for regulating excessive immune reactions in severe sepsis and septic shock using a granulocyte adsorbing column (Adacolumn [Ada]), and a cytokine-adsorbing hemofilter (AN69ST hemofilter [AN69]). Fresh porcine blood was circulated for 6 h in five experimental groups including Ada and AN69 to assess the effects of leukocyte adsorption, phagocytic activity and adhesiveness of granulocytes. In the present study, we found that Ada mainly adsorbed granulocytes and monocytes, but not lymphocytes. The phagocytic activity level of granulocytes decreased, and adhesiveness increased, but the number of CD11b-positive cells markedly decreased in the current system. Elevated cytokine levels (IL-1β, IL-8 and IL-10) at the outlet of Ada were significantly lower than at the outlet of AN69 due to cytokine adsorption. Further studies are needed to better understand cellular interactions. © 2015 International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.

Shock Isolation Elements Testing for High Input Loadings. Volume II. Foam Shock Isolation Elements.

DTIC Science & Technology

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*EXPANDED PLASTICS, (*SHOCK(MECHANICS), REDUCTION), TEST METHODS, SHOCK WAVES, STRAIN(MECHANICS), LOADS(FORCES), MATHEMATICAL MODELS, NUCLEAR EXPLOSIONS, HARDENING.

Development of a qualification standard for adhesives used in hybrid microcircuits

NASA Technical Reports Server (NTRS)

Licari, J. J.; Weigand, B. L.; Soykin, C. A.

1981-01-01

Improved qualification standards and test procedures for adhesives used in microelectronic packaging are developed. The test methods in specification for the Selection and Use of Organic Adhesives in Hybrid Microcircuits are reevaluated versus industry and government requirements. Four electrically insulative and four electrically conductive adhesives used in the assembly of hybrid microcircuits are selected to evaluate the proposed revised test methods. An estimate of the cost to perform qualification testing of an adhesive to the requirements of the revised specification is also prepared.

Summary of Glue Tests 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bell, D.; /Fermilab

1993-01-07

I have reported most of the results of my adhesive testing to members of the VLPC design team at one time or another, usually verbally, but I am wnnng this summary as an easy reference to the results I obtained. The adhesives I tested were for two primary purposes. The first was adhering optical fibers to Torlon 7130; the other was for securing an aluminum nitride substrate to the same material. I have not had access to a scanning electron microscope and someone with the knowledge to determine actual failure mechanisms, so the deductions I have made about why somemore » adhesives have worked well at low temperatures for some purposes and not for other applications while a different material never worked and another always worked are partially speculation. They should be taken merely at face value with no particular results 'carved in stone' so to speak. The first aspect of my testing was adhesion of optical fiber to torlon. Knowing that this is a very important joint, I tested a variety of glues of two primary types: acrylic and W cure. W cure adhesives are known to possess reasonably good properties at low temperatures and are quite convenient to use as long as a W source is available. The W cure adhesives I tested were: Loctite Utak 376 and also 7EN484(?), Master Bond 1 Component W 15-7, and Norland optical adhesive 61. I found them quite easy to use, and they were packaged in a way in which they were not likely to cause a mess. Lab 6 e Perimenters generally used the Loctite 376 optical cure adhesive in their research into connecting scintillating fibers to the standard type. The acrylics I tested were Loctite Speed Bonder 324 and Permabond Quick Bond 610. These worked reasonably well, but they require a considerably longer set time than the W cure adhesives and are more complicated to use. (5 minutes set time or so for the acrylics versus about 30 seconds for the W. The Loctite must have the activator applied about 5 minutes prior to the adhesive application and the Permabond must be mixed adequately.) I also used a cyanoacrylate ester (superglue type) adhesive which appeared to function adequately in this test, but I would not recommend it for extended use, and I am certain neither would anyone else. I would highly recommend using a W curing adhesive for this purpose if the adhesives and the W treatment can be determined to cause no damage to the fibers. There is no apparent physical damage, but transmission could potentially be damaged. The final optical fiber to torlon test that I did involved testing to see if individual fibers could hold the weight of the entire VlPC copper isotherm in the event that a small number of fibers shrink more than the others as the cryostat is cooled down. While this test was primarily for the purpose of testing the fibers themselves, I constructed a new sample to avoid breaking the others that had already been finished. The adhesive I used for this test was 3M 3535 BIA two part urethane adhesive. I had no problems whatsoever with this product, but like the other two part adhesives, it is considerably less convenient and more messy than the W curing adhesives. The short pot life of this adhesive was also a reason to avoid urethane, since mixing would be required frequently. The other portion of the adhesive testing for the VLPC that I performed was the adhesion of the substrate to the torlon used as a carrier. This bond is extremely small in practice, and I could not completely simulate the size and likely construction methods. I used larger pieces than those that will be bonded, but the primary goal of these tests was to test the performance of the adhesives. These tests contained harsher conditions of temperature changes and loadings than the substrates are likely to meet. By lightly loading the substrates before and after the cooling, it is possible to see if the cold temperatures had any effect on the adhesive-torlon interface, the adhesivesubstrate interface, or the adhesive itself. I tested about 10 adhesives intensely. In addition to these tests I also talked to people with about 20 different adhesive manufactures (maybe more) and Jay Hoffman, an adhesive expert here at the Lab. The general consensus from the. people that I spoke with is that the temperature range near liquid helium is very harsh and many adhesives that set quickly are not able to withstand these temperatures. Only one of the companies that I spoke with had any experience with temperatures that low (they made adhesives for space applications). I will go over each adhesive used in my testing. In addition, I will describe and speculate on the cause of any failures.« less

Transient adhesion in a non-fully detached contact.

PubMed

Liu, Zheyu; Lu, Hongyu; Zheng, Yelong; Tao, Dashuai; Meng, Yonggang; Tian, Yu

2018-04-18

Continuous approaching and detaching displacement usually occurs in an adhesion test. Here, we found a transient adhesion force at the end of a non-fully detached contact. This force occurred when the nominal detaching displacement was less than the traditional quasi-static theory predicted zero force point. The transient adhesion force was ascribed to interfacial adhesion hysteresis, which was caused by the cracking process of the contact and the deformation competition between the sphere and supporting spring. Results indicated that the testing of adhesion can be significantly affected by different combinations of stiffnesses of the contact objects and the supporting spring cantilever. This combination should be carefully designed in an adhesion test. All these results enabled increased understanding of the nature of adhesion and can guide the design of adhesive actuators.

The gene expression of cytokines and chemokines induced by tourniquet shock in mice.

PubMed

Tanaka, Jin; Ishida, Yuko; Ohshima, Tohru; Kondo, Toshikazu

2003-09-01

Traumatic shock is one of the major fields in forensic pathology, but its mechanism remains elusive from the pathophysiological aspects. Tourniquet shock has been established as one of the animal models of traumatic shock, and we examined the gene expression of cytokines and chemokines in the lung and liver in tourniquet shock using mice. Tourniquet was conducted by the application of elastic bands with five turns at both the thighs as high as possible for 2 h, followed by reperfusion. In this procedure, more than 90% mice died within 48 h after reperfusion. Serum hepatic transaminase and hematocrit values significantly increased at 2 h after reperfusion, and their elevation was still evident after 10 h. Histopathologically, hemorrhages, congestion and leukocyte recruitment were observed in the lung and liver specimens after 6 h of reperfusion. Immunohistochemical analysis with anti-myeloperoxidase antibody demonstrated a massive neutrophil infiltration in the lung and liver at 2 h or more after reperfusion. RT-PCR analyses demonstrated that the gene expression of interleukin-1beta, tumor necrosis factor-alpha, monocytes chemoattractant protein-1, macrophage inflammatory protein (MIP)-1alpha, MIP-2, KC and vascular endothelial adhesion molecule-1 was most enhanced in the lung and liver at 2 h after reperfusion. Thus, the gene expression of cytokines and chemokines is presumed to be closely related with the onset of tourniquet shock. From the forensic aspects, these cytokines and chemokines are considered to be useful markers for the early diagnosis of tourniquet shock.

Assessment of adhesion properties of novel probiotic strains to human intestinal mucus.

PubMed

Ouwehand, A C; Tuomola, E M; Tölkkö, S; Salminen, S

2001-02-28

Potential new probiotic strains Lactobacillus brevis PELI, L. reuteri ING1, L. rhamnosus VTT E-800 and L. rhamnosus LC-705 were assessed for their adhesion properties using the human intestinal mucus model. The effect on the adhesion of exposure to acid and pepsin and to milk were tested to simulate gastric and food processing conditions, and the effect of different growth media on adhesion was tested. The properties of the four strains were compared to the well-investigated probiotic L. rhamnosus strain GG. Three of the tested strains showed significant adhesion properties in the mucus model, while L. brevis PELI had intermediate adhesion and L. rhamnosus LC-705 adhered poorly. Pretreatment with different milks decreased the adhesion and low pH and pepsin treatment reduced the adhesion of all tested strains except L. rhamnosus LC-705. No competitive exclusion of pathogenic Salmonella typhimurium or Escherichia coli SfaII was observed. The results indicate that major differences exist between tested proposed probiotic strains. The growth media and the food matrix significantly affect the adhesive ability of the tested strains. This has previously not been taken into account when selecting novel probiotic strains.

Sustained load performance of adhesive anchor systems in concrete

NASA Astrophysics Data System (ADS)

Davis, Todd Marshall

Stemming from a tragic failure of an adhesive anchor system, this research project investigated the sustained load performance of adhesive anchors in concrete under different installation and in-service conditions. The literature review investigated the current state of art of adhesive anchors. Extensive discussion was devoted to the behavior of adhesive anchors in concrete as well as the many factors that can affect their short-term and sustained load strength. Existing standards and specifications for the testing, design, construction, and inspection of adhesive anchors were covered. Based on the results of the literature review and the experience of the research group, a triage was conducted on many parameters identified as possibly affecting the sustained load performance of adhesive anchors and the highest priority parameters were investigated in this project. A stress versus time-to-failure approach was used to evaluate sensitivity of three ICC-ES AC 308 approved adhesive anchor systems. Of the various parameters investigated, only elevated in-service temperature and manufacturer's cure time was shown to exhibit adverse effects on sustained loads more than that predicted by short-term tests of fully cured adhesive over a reasonable structure lifetime of 75 years. In a related study, various tests were conducted on the adhesive alone (time-temperature superposition, time-stress superposition, and dogbone tensile tests). The results of that study were used to investigate the existence of a correlation with long-term anchor pullout testing in concrete. No consistent correlations were detected for the adhesives in the study. Tests were also conducted on the effect of early-age concrete on adhesive anchor bond strength. On the basis of confined test bond-strength alone, adhesive A (vinyl ester) did not show any significant increase after 14 days (102% of 28 day strength at 14 days), and adhesive B and C (epoxies) did not show any significant increase after 7 days (104% and 93% of 28 days strength at 7 days respectively). The results of this research were used to draft recommended standards and specifications for AASHTO pertaining to testing, design, construction, and inspection of adhesive anchors in concrete for transportation structures. These draft standards were not included in this dissertation.

Advanced Metalworking Solutions for Naval Systems That Go in Harm’s Way

DTIC Science & Technology

2008-01-01

and stress corrosion cracking failures; unique processes using compacted titanium powders that are subsequently flowformed into piping, thereby...damping characteristics, adhesion strengths in peel and shock, toxicity, flame retardancy and others. Alternate cladding techniques are being...which produces a high-quality clad overlay but at a low deposition rate relative to other cladding processes. NMC and the project team will

Shear bond strength of orthodontic color-change adhesives with different light-curing times

PubMed Central

Bayani, Shahin; Ghassemi, Amirreza; Manafi, Safa; Delavarian, Mohadeseh

2015-01-01

Background: The purpose of this study was to evaluate the effect of light-curing time on the shear bond strength (SBS) of two orthodontic color-change adhesives (CCAs). Materials and Methods: A total of 72 extracted premolars were randomly assigned into 6 groups of 12 teeth each. Subsequent to primer application, a metal bracket was bonded to the buccal surface using an orthodontic adhesive. Two CCAs (Greengloo and Transbond Plus) were tested and one conventional light-cured adhesive (Resilience) served as control. For each adhesive, the specimens were light-cured for two different times of 20 and 40 s. All the specimens underwent mechanical testing using a universal testing machine to measure the SBS. Adhesive remnant index (ARI) was used to assess the remnant adhesive material on the tooth surface. All statistical analyses were performed using SPSS software. The significance level for all statistical tests was set at P ≤ 0.05. Results: The SBSs of the tested groups were in the range of 14.05-31.25 MPa. Greengloo adhesive showed the highest SBS values when light-cured for 40 s, and Transbond Plus adhesive showed the lowest values when light-cured for 20 s. ARI scores of Transbond Plus adhesive were significantly higher than those of controls, while other differences in ARI values were not significant. Conclusion: Within the limitations of his study, decreasing the light-curing time from 40 to 20 s decreased the SBS of the tested adhesives; however, this decline in SBS was statistically significant only in Transbond Plus adhesive PMID:26005468

Pathway to a Phenocopy: Heat Stress Effects in Early Embryogenesis

PubMed Central

Crews, Sarah M.; McCleery, W. Tyler; Hutson, M. Shane

2015-01-01

Background Heat shocks applied at the onset of gastrulation in early Drosophila embryos frequently lead to phenocopies of U-shaped mutants – having characteristic failures in the late morphogenetic processes of germband retraction and dorsal closure. The pathway from non-specific heat stress to phenocopied abnormalities is unknown. Results Drosophila embryos subjected to 30-min, 38-°C heat shocks at gastrulation appear to recover and restart morphogenesis. Post-heat-shock development appears normal, albeit slower, until a large fraction of embryos develop amnioserosa holes (diameters > 100 μm). These holes are positively correlated with terminal U-shaped phenocopies. They initiate between amnioserosa cells and open over tens of minutes by evading normal wound healing responses. They are not caused by tissue-wide increases in mechanical stress or decreases in cell-cell adhesion, but instead appear to initiate from isolated apoptosis of amnioserosa cells. Conclusions The pathway from heat shock to U-shaped phenocopies involves the opening of one or more large holes in the amnioserosa that compromise its structural integrity and lead to failures in morphogenetic processes that rely on amnioserosa-generated tensile forces. The proposed mechanism by which heat shock leads to hole initiation and expansion is heterochonicity – i.e., disruption of morphogenetic coordination between embryonic and extra-embryonic cell types. PMID:26498920

A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics

NASA Technical Reports Server (NTRS)

Dwight, D. W.; Wightman, J. P.

1977-01-01

The effects of composites as adherends was studied. Several other variables were studied by fractography: aluminum powder adhesive filler, fiber glass cloth scrim or adhesive carrier, new adhesives PPQ-413 and LARC-13, and strength-test temperature. When the new results were juxtaposed with previous work, it appeared that complex interactions between adhesive, adherend, bonding, and testing conditions govern the observed strength and fracture-surface features. The design parameters likely to have a significant effect upon strength-test results are listed.

Adhesion of Antireflective Coatings in Multijunction Photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brock, Ryan; Miller, David C.; Dauskardt, Reinhold H.

2016-11-21

The development of a new composite dual cantilever beam (cDCB) thin-film adhesion testing method is reported, which allows the measurement of adhesion on the fragile thin substrates used in multijunction photovoltaics. We address the adhesion of several antireflective coating systems on multijunction cells. By varying interface chemistry and morphology, we demonstrate the ensuing effects on adhesion and help to develop an understanding of how high adhesion can be achieved, as adhesion values ranging from 0.5 J/m2 to 10 J/m2 were measured. Damp Heat (85 degrees C/85% RH) was used to invoke degradation of interfacial adhesion. We show that even withmore » germanium substrates that fracture easily, quantitative measurements of adhesion can still be made at high test yield. The cDCB test is discussed as an important new methodology, which can be broadly applied to any system that makes use of thin, brittle, or otherwise fragile substrates.« less

Adhesion of Antireflective Coatings in Multijunction Photovoltaics: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brock, Ryan; Dauskardt, Reinhold H.; Miller, David C.

2016-06-16

The development of a new composite dual cantilever beam (cDCB) thin-film adhesion testing method is reported, which allows the measurement of adhesion on the fragile thin substrates used in multijunction photovoltaics. We address the adhesion of several antireflective coating systems on multijunction cells. By varying interface chemistry and morphology, we demonstrate the ensuing effects on adhesion and help to develop an understanding of how high adhesion can be achieved, as adhesion values ranging from 0.5 J/m2 to 10 J/m2 were measured. Damp Heat (85 degrees C/85% RH) was used to invoke degradation of interfacial adhesion. We show that even withmore » germanium substrates that fracture easily, quantitative measurements of adhesion can still be made at high test yield. The cDCB test is discussed as an important new methodology, which can be broadly applied to any system that makes use of thin, brittle, or otherwise fragile substrates.« less

Impact of heat-shock protein 90 on cancer metastasis

PubMed Central

Tsutsumi, Shinji; Beebe, Kristin; Neckers, Len

2009-01-01

Cancer metastasis is the result of complex processes, including alteration of cell adhesion/motility in the microenvironment and neoangiogenesis, that are necessary to support cancer growth in tissues distant from the primary tumor. The molecular chaperone heat-shock protein 90 (Hsp90), also termed the ‘cancer chaperone’, plays a crucial role in maintaining the stability and activity of numerous signaling proteins involved in these processes. Small-molecule Hsp90 inhibitors display anticancer activity both in vitro and in vivo, and multiple Phase II and Phase III clinical trials of several structurally distinct Hsp90 inhibitors are currently underway. In this review, we will highlight the importance of Hsp90 in cancer metastasis and the therapeutic potential of Hsp90 inhibitors as antimetastasis drugs. PMID:19519207

Improvement of Adhesion Properties and Corrosion Resistance of Sol-Gel Coating on Zinc.

PubMed

Savignac, Pauline; Menu, Marie-Joëlle; Gressier, Marie; Denat, Bastien; Khadir, Yacine El; Manov, Stephan; Ansart, Florence

2018-05-03

Corrosion is a major problem for durability of many metals and alloys. Among the efficient classical surface treatments, chromate-based treatments must be banished from industrial use due to their toxicity. At the same time, sol-gel routes have demonstrated high potential to develop an efficient barrier effect against aggressive environments. By this process, the anti-corrosion property can be also associated to others in the case of the development of multi-functional hybrid coatings. In this paper, the main goal is precisely to improve both the corrosion resistance and the adhesion properties of phosphated zinc substrates by the deposition of a hybrid (organic-inorganic) sol-gel layer. To reach this double objective, a choice between two formulations 3-glycidoxypropyltrimethoxysilane (GPTMS)/aluminum-tri-sec-butoxide (ASB) and 3-(trimethoxysilyl)propylmethacrylate (MAP)/tetraethylorthosilicate (TEOS) was firstly made based on the results obtained by microstructural characterizations using SEM, optical analysis, and mechanical characterization such as shock and/or scratch tests (coupled to climatic chamber and salt spray exposure). Several investigations were performed in this study, and the best formulation and performances of the system were obtained by adding a new precursor (1-[3-(trimethoxysilyl)propyl]ureido-UPS) under controlled conditions, as detailed in this paper.

Characterization of silver nanoparticle-infused tissue adhesive for ophthalmic use.

PubMed

Yee, William; Selvaduray, Guna; Hawkins, Benjamin

2015-03-01

In this work, we demonstrate the successful enhancement of breaking strength, adhesive strength, and antibacterial efficacy of ophthalmic tissue adhesive (2-octyl cyanoacrylate) by doping with silver nanoparticles, and investigate the effects of nanoparticle size and concentration. Recent work has shown that silver nanoparticles are a viable antibacterial additive to many compounds, but their efficacy in tissue adhesives was heretofore untested. Our results indicate that doping the adhesive with silver nanoparticles reduced bacterial growth by an order of magnitude or more; nanoparticle size and concentration had minimal influence in the range tested. Tensile breaking strength of polymerized adhesive samples and adhesive strength between a T-shaped support and excised porcine sclera were measured using a universal testing machine according to ASTM (formerly American Society for Testing and Materials) standard techniques. Both tests showed significant improvement with the addition of silver nanoparticles. The enhanced mechanical strength and antibacterial efficacy of the doped adhesive supports the use of tissue adhesives as a viable supplement or alternative to sutures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Riata silicone defibrillation lead with normal electrical measures at routine ambulatory check: The role of high-voltage shock testing

PubMed Central

De Maria, Elia; Borghi, Ambra; Bonetti, Lorenzo; Fontana, Pier Luigi; Cappelli, Stefano

2016-01-01

AIM To describe our experience with shock testing for the evaluation of patients with Riata™ leads. METHODS Among 51 patients with normal baseline electrical parameters, 20 died during follow-up. Of the remaining 31 patients, 15 underwent the test: In 10 cases a defibrillation testing with ventricular fibrillation (VF) induction and in 5 cases a R-wave-synchronized shock (> 20 J, without inducing VF). The test was performed under sedation with Midazolam. RESULTS Twelve patients (80%) had a normal behavior during shock testing: In 8 cases induced VF was correctly detected and treated; in 4 cases of R-wave-synchronized shock electrical parameters remained stable and normal. Three patients (20%) failed the test. One patient with externalized conductors showed a sudden drop of high-voltage impedance (< 10 Ohm) after a 25 J R-wave-synchronized shock. Two other patients with externalized conductors, undergoing defibrillation testing, showed a short-circuit during shock delivery and the implantable cardioverter defibrillator was unable to interrupt VF. CONCLUSION In Riata™ leads the delivery of a low current during routine measurement of high-voltage impedance may not reveal a small short circuit, that can only be evident by attempting to deliver a true shock, either for spontaneous arrhythmias or in the context of a shock testing. PMID:27957252

Die-target for dynamic powder consolidation

DOEpatents

Flinn, J.E.; Korth, G.E.

1985-06-27

A die/target is disclosed for consolidation of a powder, especially an atomized rapidly solidified metal powder, to produce monoliths by the dynamic action of a shock wave, especially a shock wave produced by the detonation of an explosive charge. The die/target comprises a rectangular metal block having a square primary surface with four rectangular mold cavities formed therein to receive the powder. The cavities are located away from the geometrical center of the primary surface and are distributed around such center while also being located away from the geometrical diagonals of the primary surface to reduce the action of reflected waves so as to avoid tensile cracking of the monoliths. The primary surface is covered by a powder retention plate which is engaged by a flyer plate to transmit the shock wave to the primary surface and the powder. Spawl plates are adhesively mounted on other surfaces of the block to act as momentum traps so as to reduce reflected waves in the block. 4 figs.

Die-target for dynamic powder consolidation

DOEpatents

Flinn, John E.; Korth, Gary E.

1986-01-01

A die/target is disclosed for consolidation of a powder, especially an atomized rapidly solidified metal powder, to produce monoliths by the dynamic action of a shock wave, especially a shock wave produced by the detonation of an explosive charge. The die/target comprises a rectangular metal block having a square primary surface with four rectangular mold cavities formed therein to receive the powder. The cavities are located away from the geometrical center of the primary surface and are distributed around such center while also being located away from the geometrical diagonals of the primary surface to reduce the action of reflected waves so as to avoid tensile cracking of the monoliths. The primary surface is covered by a powder retention plate which is engaged by a flyer plate to transmit the shock wave to the primary surface and the powder. Spawl plates are adhesively mounted on other surfaces of the block to act as momentum traps so as to reduce reflected waves in the block.

Heat shock proteins and toll-like receptors.

PubMed

Asea, Alexzander

2008-01-01

Researchers have only just begun to elucidate the relationship between heat shock proteins (HSP) and Toll-like receptors (TLR). HSP were originally described as an intracellular molecular chaperone of naïve, aberrantly folded, or mutated proteins and primarily implicated as a cytoprotective protein when cells are exposed to stressful stimuli. However, recent studies have ascribed novel functions to the Hsp70 protein depending on its localization: Surface-bound Hsp70 specifically activate natural killer (NK) cells, while Hsp70 released into the extracellular milieu specifically bind to Toll-like receptors (TLR) 2 and 4 on antigen-presenting cells (APC) and exerts immunoregulatory effects, including upregulation of adhesion molecules, co-stimulatory molecule expression, and cytokine and chemokine release-a process known as the chaperokine activity of Hsp70. This chapter discusses the most recent advances in the understanding of heat shock protein (HSP) and TLR interactions in general and highlights recent findings that demonstrate Hsp70 is a ligand for TLR and its biological significance.

Adhesion Testing of Firebricks from Launch Pad 39A Flame Trench after STS-124

NASA Technical Reports Server (NTRS)

Hintze, Paul E.; Curran, Jerome P.

2009-01-01

Adhesion testing was performed on the firebricks in the flame trench of Launch Complex 39A to determine the strength of the epoxy/firebrick bond to the backing concrete wall. The testing used an Elcometer 110 pneumatic adhesion tensile testing instrument (PATTI).

Why do some wood-adhesive bonds respond poorly to accelerated moisture-resistant tests?

Treesearch

Charles R. Frihart; James M. Wescott

2008-01-01

The most challenging part of developing acceptable adhesives for wood bonding often is to create a bond that will withstand exposure to wet conditions or wet/dry cycles. Products that pass these tests have been developed empirically, but the aspects that make it difficult for adhesives to pass these tests and systematically ways to develop more durable adhesive bonds...

Bolt Shear Force Sensor

DTIC Science & Technology

2015-03-12

submarine and ship systems required to survive the effects of mechanical shock must consider not only the system and foundation to which the system...See FIG. 1). In the figure, a Bragg grating sensor 1 is inserted and held by epoxy 2 in a mechanical fastener 10. Optical fiber 3 connects the...circumferential) strains. The sensing elements 120 are fixedly bonded to the vertical section 103 using conventional adhesives such as epoxies or

Adherence of Candida sp. to host tissues and cells as one of its pathogenicity features.

PubMed

Modrzewska, Barbara; Kurnatowski, Piotr

2015-01-01

The ability of Candida sp. cells to adhere to the mucosal surfaces of various host organs as well as synthetic materials is an important pathogenicity feature of those fungi which contributes to the development of infection. This property varies depending on the species of the fungus and is the greatest for C. albicans. The process of adhesion depends on plenty of factors related to the fungal and host cells as well as environmental conditions. The main adhesins present on the fungal cell wall are: Als, Epa, Hwp1, but also Eap1, Sun41, Csh1 and probably Hyr1; for adhesion significant are also secreted aspartyl proteases Sap. Various researchers specify a range of genes which contribute to adhesion, such as: CZF1, EFG1, TUP1, TPK1, TPK2, HGC1, RAS1, RIM101, VPS11, ECM1, CKA2, BCR1, BUD2, RSR1, IRS4, CHS2, SCS7, UBI4, UME6, TEC1 and GAT2. Influence for adherence have also heat shock proteins Hsp70, Mediator Middle domain subunit Med31 and morphological transition. Among factors affecting adhesion related to host cells it is necessary to mention fibronectins and integrins (receptors for Candida sp. adhesins), type of epithelial cells, their morphology and differentiation phase. To a lesser degree influence on adhesion have non-specific factors and environmental conditions.

Streptococcus pyogenes CAMP factor promotes bacterial adhesion and invasion in pharyngeal epithelial cells without serum via PI3K/Akt signaling pathway.

PubMed

Kurosawa, Mie; Oda, Masataka; Domon, Hisanori; Isono, Toshihito; Nakamura, Yuki; Saitoh, Issei; Hayasaki, Haruaki; Yamaguchi, Masaya; Kawabata, Shigetada; Terao, Yutaka

2018-01-01

Streptococcus pyogenes is a bacterium that causes systemic diseases, such as pharyngitis and toxic shock syndrome, via oral- or nasal-cavity infection. S. pyogenes produces various molecules known to function with serum components that lead to bacterial adhesion and invasion in human tissues. In this study, we identified a novel S. pyogenes adhesin/invasin. Our results revealed that CAMP factor promoted streptococcal adhesion and invasion in pharyngeal epithelial Detroit562 cells without serum. Recombinant CAMP factor initially localized on the membranes of cells and then became internalized in the cytosol following S. pyogenes infection. Additionally, CAMP factor phosphorylated phosphoinositide 3-kinase and serine-threonine kinase in the cells. ELISA results demonstrate that CAMP factor affected the amount of phosphorylated phosphoinositide 3-kinase and serine-threonine kinase in Detroit562 cells. Furthermore, CAMP factor did not reverse the effect of phosphoinositide 3-kinase knockdown by small interfering RNA in reducing the level of adhesion and invasion of S. pyogenes isogenic cfa-deficient mutant. These results suggested that S. pyogenes CAMP factor activated the phosphoinositide 3-kinase/serine-threonine kinase signaling pathway, promoting S. pyogenes invasion of Detroit562 cells without serum. Our findings suggested that CAMP factor played an important role on adhesion and invasion in pharyngeal epithelial cells. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Evaluation of EA-934NA with 2.5 percent Cab-O-Sil

NASA Technical Reports Server (NTRS)

Caldwell, Gordon A.

1990-01-01

Currently, Hysol adhesive EA-934NA is used to bond the Field Joint Protection System on the Shuttle rocket motors at Kennedy Space Center. However, due to processing problems, an adhesive with a higher viscosity is needed to alleviate these difficulties. One possible solution is to add Cab-O-Sil to the current adhesive. The adhesive strength and bond strengths that can be obtained when 2.5 percent Cab-O-Sil is added to adhesive EA-934NA are examined and tested over a range of test temperatures from -20 to 300 F. Tensile adhesion button and lap shear specimens were bonded to D6AC steel and uniaxial tensile specimens (testing for strength, initial tangent modulus, elongation and Poisson's ratio) were prepared using Hysol adhesive EA-934NA with 2.5 percent Cab-O-Sil added. These specimens were tested at -20, 20, 75, 100, 125, 150, 200, 250, and 300 F, respectively. Additional tensile adhesion button specimens bonding Rust-Oleum primed and painted D6AC steel to itself and to cork using adhesive EA-934NA with 2.5 percent Cab-O-Sil added were tested at 20, 75, 125, 200, and 300 F, respectively. Results generally show decreasing strength values with increasing test temperatures. The bond strengths obtained using cork as a substrate were totally dependent on the cohesive strength of the cork.

Effect of defibrillation threshold testing on effectiveness of the subcutaneous implantable cardioverter defibrillator.

PubMed

Peddareddy, Lakshmi; Merchant, Faisal M; Leon, Angel R; Smith, Paige; Patel, Akshar; El-Chami, Mikhael F

2018-06-12

Defibrillation threshold (DFT) testing is recommended with the subcutaneous ICD (SICD). To describe first shock efficacy for appropriate SICD therapies stratified by the presence of implant DFT testing. We reviewed all patients receiving SICDs at our institution and stratified them based on whether implant DFT testing was performed. Appropriate shocks were reviewed to see if ventricular tachycardia/ventricular fibrillation (VT/VF) terminated with a single shock. First shock efficacy was stratified by implant DFT status. 178 patients implanted with SICDs and followed in our center were included in this study. Of these, 135 (76 %) underwent DFT testing (DFT (+) group). In the DFT (+) 80 appropriate shocks were needed to treat 69 episodes of VT/VF. The first shock was effective in 61 out of 69 episodes (88.4 %), whereas multiple shocks were required to terminate VT/VF in the remaining 8 episodes. Among 43 patients without implant DFT testing (DFT (-) group), 20 appropriate shocks to treat 17 episodes of VT/VF occurred in 7 patients. VT/VF was successfully terminated with the first shock in 16 out of 17 episodes (first shock efficacy 94.1 %). There was no significant difference in first shock effectiveness between those with and without implant DFT testing (p = 0.97). A strategy that omits DFT testing at implant did not appear to compromise the effictiveness of the SICD. These data suggest that routine DFT testing at SICD implant might not be necessary. Randomized trials are needed to confirm this finding. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Bond strength of one-step self-etch adhesives and their predecessors to ground versus unground enamel

PubMed Central

Yazici, A. Ruya; Yildirim, Zeren; Ertan, Atila; Ozgunaltay, Gül; Dayangac, Berrin; Antonson, Sibel A; Antonson, Donald E

2012-01-01

Objective The aim of this study was to compare the shear bond strength of several self-etch adhesives to their two-step predecessors to ground and unground enamel. Methods: Seventy-five extracted, non-carious human third molar teeth were selected for this study. The buccal surfaces of each tooth were mechanically ground to obtain flat enamel surfaces (ground enamel), while the lingual surfaces were left intact (unground enamel). The teeth were randomly divided into five groups according to the adhesive systems (n=15): one-step self-etch adhesive - Clearfil S3 Bond, its two-step predecessor - Clearfil SE Bond, one-step self-etch adhesive - AdheSE One, and its two-step predecessor - AdheSE, and a two-step etch-and-rinse adhesive - Adper Single Bond 2(control). After application of the adhesives to the buccal and lingual enamel surfaces of each tooth, a cylindrical capsule filled with a hybrid composite resin (TPH) was seated against the surfaces. The specimens were stored in distilled water at 37°C for 24 hours, followed by thermocy-cling (5°C–55°C/500 cycles). They were subjected to shear bond strength test in a universal testing machine at a crosshead speed of 1.0 mm/minute. The data were compared using a two-way ANOVA, followed by Bonferroni test at P<.05. Results: All adhesives exhibited statistically similar bond strengths to ground and unground enamel except for the etch-and-rinse adhesive that showed significantly higher bond strengths than the self-etch adhesives (P<.05). No significant differences in bond strength values were observed between ground and unground enamel for any of the adhesives tested (P=.17). Conclusion: Similar bond strengths to ground and unground enamel were achieved with one-step self-etch adhesives and their predecessors. Enamel preparation did not influence the bonding performance of the adhesives tested. PMID:22904656

Bond strength of one-step self-etch adhesives and their predecessors to ground versus unground enamel.

PubMed

Yazici, A Ruya; Yildirim, Zeren; Ertan, Atila; Ozgunaltay, Gül; Dayangac, Berrin; Antonson, Sibel A; Antonson, Donald E

2012-07-01

The aim of this study was to compare the shear bond strength of several self-etch adhesives to their two-step predecessors to ground and unground enamel. Seventy-five extracted, non-carious human third molar teeth were selected for this study. The buccal surfaces of each tooth were mechanically ground to obtain flat enamel surfaces (ground enamel), while the lingual surfaces were left intact (unground enamel). The teeth were randomly divided into five groups according to the adhesive systems (n=15): one-step self-etch adhesive - Clearfil S3 Bond, its two-step predecessor - Clearfil SE Bond, one-step self-etch adhesive - AdheSE One, and its two-step predecessor - AdheSE, and a two-step etch-and-rinse adhesive - Adper Single Bond 2(control). After application of the adhesives to the buccal and lingual enamel surfaces of each tooth, a cylindrical capsule filled with a hybrid composite resin (TPH) was seated against the surfaces. The specimens were stored in distilled water at 37°C for 24 hours, followed by thermocy-cling (5°C-55°C/500 cycles). They were subjected to shear bond strength test in a universal testing machine at a crosshead speed of 1.0 mm/minute. The data were compared using a two-way ANOVA, followed by Bonferroni test at P<.05. All adhesives exhibited statistically similar bond strengths to ground and unground enamel except for the etch-and-rinse adhesive that showed significantly higher bond strengths than the self-etch adhesives (P<.05). No significant differences in bond strength values were observed between ground and unground enamel for any of the adhesives tested (P=.17). Similar bond strengths to ground and unground enamel were achieved with one-step self-etch adhesives and their predecessors. Enamel preparation did not influence the bonding performance of the adhesives tested.

Effect of double-layer application on bond quality of adhesive systems.

PubMed

Fujiwara, Satoshi; Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Imai, Arisa; Watanabe, Hidehiko; Erickson, Robert L; Latta, Mark A; Nakatsuka, Toshiyuki; Miyazaki, Masashi

2018-01-01

The aim of this study was to determine the effect of double-layer application of universal adhesives on the bond quality and compare to other adhesive systems. Two universal adhesives used were in this study: Scotchbond Universal (SU), [3M ESPE] and Prime & Bond elect (PE), [Dentsply Caulk]. The conventional single-step self-etch adhesives G-ӕnial Bond (GB), [GC Corporation.] and BeautiBond (BB), [Shofu Inc.], and a two-step self-etch adhesive, Optibond XTR (OX), [Kerr Corporation], were used as comparison adhesives. Shear bond strengths (SBS) and shear fatigue strengths (SFS) to human enamel and dentin were measured in single application mode and double application mode. For each test condition, 15 specimens were prepared for SBS testing and 30 specimens for SFS testing. Enamel and dentin SBS of the universal adhesives in the double application mode were significantly higher than those of the single application mode. In addition, the universal adhesives in the double application mode had significantly higher dentin SFS values than those of the single application mode. The two-step self-etch adhesive OX tended to have lower bond strengths in the double application mode, regardless of the test method or adherent substrate. The double application mode is effective in enhancing SBS and SFS of universal adhesives, but not conventional two-step self-etch adhesives. These results suggest that, although the double application mode may enhance the bonding quality of a universal adhesive, it may be counter-productive for two-step self-etch adhesives in clinical use. Copyright © 2017 Elsevier Ltd. All rights reserved.

Probabilistic thermal-shock strength testing using infrared imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wereszczak, A.A.; Scheidt, R.A.; Ferber, M.K.

1999-12-01

A thermal-shock strength-testing technique has been developed that uses a high-resolution, high-temperature infrared camera to capture a specimen's surface temperature distribution at fracture. Aluminum nitride (AlN) substrates are thermally shocked to fracture to demonstrate the technique. The surface temperature distribution for each test and AlN's thermal expansion are used as input in a finite-element model to determine the thermal-shock strength for each specimen. An uncensored thermal-shock strength Weibull distribution is then determined. The test and analysis algorithm show promise as a means to characterize thermal shock strength of ceramic materials.

A Study of the Effects of Relative Humidity on Small Particle Adhesion to Surfaces

NASA Technical Reports Server (NTRS)

Whitfield, W. J.; David, T.

1971-01-01

Ambient dust ranging in size from less than one micron up to 140 microns was used as test particles. Relative humidities of 33% to 100% were used to condition test surfaces after loading with the test particles. A 20 psi nitrogen blowoff was used as the removal mechanism to test for particle adhesion. Particles were counted before and after blowoff to determine retention characteristics. Particle adhesion increased drastically as relative humidity increased above 50%. The greatest adhesion changes occurred within the first hour of conditioning time. Data are presented for total particle adhesion, for particles 10 microns and larger, and 50 microns and larger.

Resistance heating releases structural adhesive

NASA Technical Reports Server (NTRS)

Glemser, N. N.

1967-01-01

Composite adhesive package bonds components together for testing and enables separation when testing is completed. The composite of adhesives, insulation and a heating element separate easily when an electrical current is applied.

A comprehensive toxicological evaluation of three adhesives using experimental cigarettes.

PubMed

Coggins, Christopher R E; Jerome, Ann M; Lilly, Patrick D; McKinney, Willie J; Oldham, Michael J

2013-01-01

Adhesives are used in several different manufacturing operations in the production of cigarettes. The use of new, "high-speed-manufacture" adhesives (e.g. vinyl acetate based) could affect the smoke chemistry and toxicology of cigarettes, compared with older "low-speed-manufacture" adhesives (e.g. starch based). This study was conducted to determine whether the inclusion of different levels of three adhesives (ethylene vinyl acetate, polyvinyl acetate and starch) in experimental cigarettes results in different smoke chemistry and toxicological responses in in vitro and in vivo assays. A battery of tests (analytical chemistry, in vitro and in vivo assays) was used to compare the chemistry and toxicology of smoke from experimental cigarettes made with different combinations of the three adhesives. Varying levels of the different side-seam adhesives, as well as the transfer of adhesives from packaging materials, were tested. There were differences in some mainstream cigarette smoke constituents as a function of the level of adhesive added to experimental cigarettes and between the tested adhesives. None of these differences translated into statistically significant differences in the in vitro or in vivo assays. The use of newer "high-speed-manufacture" vinyl acetate-based adhesives in cigarettes does not produce toxicological profiles that prevent the adhesives from replacing the older "low-speed-manufacture" adhesives (such as starch).

Quantitative adhesion characterization of antireflective coatings in multijunction photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brock, Ryan; Rewari, Raunaq; Novoa, Fernando D.

We discuss the development of a new composite dual cantilever beam (cDCB) thin-film adhesion testing method, which enables the quantitative measurement of adhesion on the thin and fragile substrates used in multijunction photovoltaics. In particular, we address the adhesion of several 2- and 3-layer antireflective coating systems on multijunction cells. By varying interface chemistry and morphology through processing, we demonstrate the marked effects on adhesion and help to develop an understanding of how high adhesion can be achieved, as adhesion values ranging from 0.5 J/m2 to 10 J/m2 were measured. Damp heat (85 degrees C/85% RH) was used to invokemore » degradation of interfacial adhesion. We demonstrate that even with germanium substrates that fracture relatively easily, quantitative measurements of adhesion can be made at high test yield. The cDCB test is discussed as an important new methodology, which can be broadly applied to any system that makes use of thin, brittle, or otherwise fragile substrates.« less

Modelling and Laboratory Studies on the Adhesion Fatigue Performance for Thin-Film Asphalt and Aggregate System

PubMed Central

Wang, Dongsheng; Feng, Decheng

2014-01-01

Adhesion between asphalt and aggregate plays an important role in the performance of asphalt mixtures. A low-frequency adhesion fatigue test was proposed in this paper to study the effect of environment on the asphalt-aggregate adhesion system. The stress-based fatigue model had been utilized to describe the fatigue behavior of thin-film asphalt and aggregate system. The factors influencing the adhesion fatigue performance were also investigated. Experiment results show that asphalt has more important effect on the adhesion performance comparing with aggregate. Basalt, which is regarded as hydrophobic aggregates with low silica content, has better adhesion performance to asphalt binder when compared with granite. The effects of aging on the adhesion fatigue performance are different for PG64-22 and rubber asphalt. Long-term aging is found to reduce the adhesion fatigue lives for rubber asphalt and aggregate system, while the effect of long-term aging for aggregate and PG64-22 binder system is positive. Generally the increased stress amplitude and test temperature could induce greater damage and lead to less fatigue lives for adhesion test system. PMID:25054187

Modelling and laboratory studies on the adhesion fatigue performance for thin-film asphalt and aggregate system.

PubMed

Wang, Dongsheng; Yi, Junyan; Feng, Decheng

2014-01-01

Adhesion between asphalt and aggregate plays an important role in the performance of asphalt mixtures. A low-frequency adhesion fatigue test was proposed in this paper to study the effect of environment on the asphalt-aggregate adhesion system. The stress-based fatigue model had been utilized to describe the fatigue behavior of thin-film asphalt and aggregate system. The factors influencing the adhesion fatigue performance were also investigated. Experiment results show that asphalt has more important effect on the adhesion performance comparing with aggregate. Basalt, which is regarded as hydrophobic aggregates with low silica content, has better adhesion performance to asphalt binder when compared with granite. The effects of aging on the adhesion fatigue performance are different for PG64-22 and rubber asphalt. Long-term aging is found to reduce the adhesion fatigue lives for rubber asphalt and aggregate system, while the effect of long-term aging for aggregate and PG64-22 binder system is positive. Generally the increased stress amplitude and test temperature could induce greater damage and lead to less fatigue lives for adhesion test system.

Shear bond strength of one-step self-etch adhesives to dentin: Evaluation of NaOCl pretreatment.

PubMed

Colombo, Marco; Beltrami, Riccardo; Chiesa, Marco; Poggio, Claudio; Scribante, Andrea

2018-02-01

The aim of this study was to evaluate the influence of dentin pretreatment with NaOCl on shear bond strength of four one-step self-etch adhesives with different pH values. Bovine permanent incisors were used. Four one-step self-etch adhesives were tested: Adper™ Easy Bond, Futurabond NR, G-aenial Bond, Clearfil S3 Bond. One two-step self-etch adhesive (Clearfil SE Bond) was used as control. Group 1- no pretreatment; group 2- pretratment with 5,25 % NaOCl; group 3- pretreatment with 37 % H3PO4 etching and 5,25 % NaOCl. A hybrid composite resin was inserted into the dentin surface. The specimens were tested in a universal testing machine. The examiners evaluated the fractured surfaces in optical microscope to determine failure modes, quantified with adhesive remnant index (ARI). Dentin pretreatment variably influenced bond strength values of the different adhesive systems. When no dentin pretreatment was applied, no significant differences were found ( P >.05) among four adhesives tested. No significant differences were recorded when comparing NaOCl pretreatment with H3PO4 + NaOCl pretreatment for all adhesive tested ( P >.05) except Clearfil S3 Bond that showed higher shear bond strength values when H3PO4 was applied. Frequencies of ARI scores were calculated. The influence of dentin pretreatment with NaOCl depends on the composition of each adhesive system used. There was no difference in bond strength values among self-etch adhesives with different pH values. Key words: Dentin, pretreatment, self-etch adhesives.

A method to screen and evaluate tissue adhesives for joint repair applications

PubMed Central

2012-01-01

Background Tissue adhesives are useful means for various medical procedures. Since varying requirements cause that a single adhesive cannot meet all needs, bond strength testing remains one of the key applications used to screen for new products and study the influence of experimental variables. This study was conducted to develop an easy to use method to screen and evaluate tissue adhesives for tissue engineering applications. Method Tissue grips were designed to facilitate the reproducible production of substrate tissue and adhesive strength measurements in universal testing machines. Porcine femoral condyles were used to generate osteochondral test tissue cylinders (substrates) of different shapes. Viability of substrates was tested using PI/FDA staining. Self-bonding properties were determined to examine reusability of substrates (n = 3). Serial measurements (n = 5) in different operation modes (OM) were performed to analyze the bonding strength of tissue adhesives in bone (OM-1) and cartilage tissue either in isolation (OM-2) or under specific requirements in joint repair such as filling cartilage defects with clinical applied fibrin/PLGA-cell-transplants (OM-3) or tissues (OM-4). The efficiency of the method was determined on the basis of adhesive properties of fibrin glue for different assembly times (30 s, 60 s). Seven randomly generated collagen formulations were analyzed to examine the potential of method to identify new tissue adhesives. Results Viability analysis of test tissue cylinders revealed vital cells (>80%) in cartilage components even 48 h post preparation. Reuse (n = 10) of test substrate did not significantly change adhesive characteristics. Adhesive strength of fibrin varied in different test settings (OM-1: 7.1 kPa, OM-2: 2.6 kPa, OM-3: 32.7 kPa, OM-4: 30.1 kPa) and was increasing with assembly time on average (2.4-fold). The screening of the different collagen formulations revealed a substance with significant higher adhesive strength on cartilage (14.8 kPa) and bone tissue (11.8 kPa) compared to fibrin and also considerable adhesive properties when filling defects with cartilage tissue (23.2 kPa). Conclusion The method confirmed adhesive properties of fibrin and demonstrated the dependence of adhesive properties and applied settings. Furthermore the method was suitable to screen for potential adhesives and to identify a promising candidate for cartilage and bone applications. The method can offer simple, replicable and efficient evaluation of adhesive properties in ex vivo specimens and may be a useful supplement to existing methods in clinical relevant settings. PMID:22984926

Laboratory test for ice adhesion strength using commercial instrumentation.

PubMed

Wang, Chenyu; Zhang, Wei; Siva, Adarsh; Tiea, Daniel; Wynne, Kenneth J

2014-01-21

A laboratory test method for evaluating ice adhesion has been developed employing a commercially available instrument normally used for dynamic mechanical analysis (TA RSA-III). This is the first laboratory ice adhesion test that does not require a custom-built apparatus. The upper grip range of ∼10 mm is an enabling feature that is essential for the test. The method involves removal of an ice cylinder from a polymer coating with a probe and the determination of peak removal force (Ps). To validate the test method, the strength of ice adhesion was determined for a prototypical glassy polymer, poly(methyl methacrylate). The distance of the probe from the PMMA surface has been identified as a critical variable for Ps. The new test provides a readily available platform for investigating fundamental surface characteristics affecting ice adhesion. In addition to the ice release test, PMMA coatings were characterized using DSC, DCA, and TM-AFM.

16 CFR 1204.4 - Electric shock protection tests.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Electric shock protection tests. 1204.4... Electric shock protection tests. (a) Safety precautions. For tests involving high voltage, the following... Effectiveness Test or the Antenna-Mast System Test if no electrical breakdown occurs and if no current reading...

16 CFR 1204.4 - Electric shock protection tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Electric shock protection tests. 1204.4... Electric shock protection tests. (a) Safety precautions. For tests involving high voltage, the following... Effectiveness Test or the Antenna-Mast System Test if no electrical breakdown occurs and if no current reading...

16 CFR 1204.4 - Electric shock protection tests.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Electric shock protection tests. 1204.4... Electric shock protection tests. (a) Safety precautions. For tests involving high voltage, the following... Effectiveness Test or the Antenna-Mast System Test if no electrical breakdown occurs and if no current reading...

Preparation and Testing of Plant Seed Meal-based Wood Adhesives

PubMed Central

He, Zhongqi; Chapital, Dorselyn C.

2015-01-01

Recently, the interest in plant seed meal-based products as wood adhesives has steadily increased, as these plant raw materials are considered renewable and environment-friendly. These natural products may serve as alternatives to petroleum-based adhesives to ease environmental and sustainability concerns. This work demonstrates the preparation and testing of the plant seed-based wood adhesives using cottonseed and soy meal as raw materials. In addition to untreated meals, water washed meals and protein isolates are prepared and tested. Adhesive slurries are prepared by mixing a freeze-dried meal product with deionized water (3:25 w/w) for 2 hr. Each adhesive preparation is applied to one end of 2 wood veneer strips using a brush. The tacky adhesive coated areas of the wood veneer strips are lapped and glued by hot-pressing. Adhesive strength is reported as the shear strength of the bonded wood specimen at break. Water resistance of the adhesives is measured by the change in shear strength of the bonded wood specimens at break after water soaking. This protocol allows one to assess plant seed-based agricultural products as suitable candidates for substitution of synthetic-based wood adhesives. Adjustments to the adhesive formulation with or without additives and bonding conditions could optimize their adhesive properties for various practical applications. PMID:25867092

Preparation and testing of plant seed meal-based wood adhesives.

PubMed

He, Zhongqi; Chapital, Dorselyn C

2015-03-05

Recently, the interest in plant seed meal-based products as wood adhesives has steadily increased, as these plant raw materials are considered renewable and environment-friendly. These natural products may serve as alternatives to petroleum-based adhesives to ease environmental and sustainability concerns. This work demonstrates the preparation and testing of the plant seed-based wood adhesives using cottonseed and soy meal as raw materials. In addition to untreated meals, water washed meals and protein isolates are prepared and tested. Adhesive slurries are prepared by mixing a freeze-dried meal product with deionized water (3:25 w/w) for 2 hr. Each adhesive preparation is applied to one end of 2 wood veneer strips using a brush. The tacky adhesive coated areas of the wood veneer strips are lapped and glued by hot-pressing. Adhesive strength is reported as the shear strength of the bonded wood specimen at break. Water resistance of the adhesives is measured by the change in shear strength of the bonded wood specimens at break after water soaking. This protocol allows one to assess plant seed-based agricultural products as suitable candidates for substitution of synthetic-based wood adhesives. Adjustments to the adhesive formulation with or without additives and bonding conditions could optimize their adhesive properties for various practical applications.

Deformation-free rim for the primary mirror of telescope having sub-second resolution

NASA Astrophysics Data System (ADS)

Malyshev, I. V.; Chkhalo, N. I.; Toropov, M. N.; Salashchenko, N. N.; Pestov, A. E.; Kuzin, S. V.; Polkovnikov, V. N.

2017-05-01

The work is devoted to the method of mounting and surface shape measurement of the primary mirror of ARCA telescope, intended for the Sun observation in EUV wavelength range. Calculation of mirror's deformation due to weight is carried out and a method of its experimental determination in interferometer is proposed. The method of deformation-free installation of mirror into the telescope is proposed. Impact shocks and vibrations, arising during missile launch, is analyzed, and an optimal size of bridges in the rim is determined. Calculations of the mirror deformation due to temperature difference in the telescope on the Earth's orbit and its influence on the resolution of the telescope are conducted. The stresses arising in epoxy adhesive due to temperature changes and due to starting shocks are simulated.

Factors that lead to failure with wood adhesive bonds

Treesearch

Charles R. Frihart; James F. Beecher

2016-01-01

Understanding what makes a good wood adhesive is difficult since the type of adhesive, wood species, bonding process, and resultant products vary considerably. Wood bonds are subjected to a variety of tests that reflect the different product performance criteria in diverse countries. The most common tests involve some type of moisture resistance; both wood and adhesive...

Influence of frequency on shear fatigue strength of resin composite to enamel bonds using self-etch adhesives.

PubMed

Takamizawa, Toshiki; Scheidel, Donal D; Barkmeier, Wayne W; Erickson, Robert L; Tsujimoto, Akimasa; Latta, Mark A; Miyazaki, Masashi

2016-09-01

The purpose of this study was to determine the influence of different frequency rates on of bond durability of self-etch adhesives to enamel using shear fatigue strength (SFS) testing. A two-step self-etch adhesive (OX, OptiBond XTR), and two single step self-etch adhesives (GB, G-ӕnial Bond and SU, Scotchbond Universal) were used in this study. The shear fatigue strength (SFS) to enamel was obtained. A staircase method was used to determine the SFS values with 50,000 cycles or until failure occurred. Fatigue testing was performed at frequencies of 5Hz, 10Hz, and 20Hz. For each test condition, 30 specimens were prepared for the SFS testing. Regardless of the bond strength test method, OX showed significantly higher SFS values than the two single-step self-etch adhesives. For each of the three individual self-etch adhesives, there was no significant difference in SFS depending on the frequency rate, although 20Hz results tended to be higher. Regardless of the self-etch adhesive system, frequencies of 5Hz, 10Hz, and 20Hz produced similar results in fatigue strength of resin composite bonded to enamel using 50,000 cycles or until bond failure. Accelerated fatigue testing provides valuable information regarding the long term durability of resin composite to enamel bonding using self-etch adhesive system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Shear bond strength of self-etch adhesives to enamel with additional phosphoric acid etching.

PubMed

Lührs, Anne-Katrin; Guhr, Silke; Schilke, Reinhard; Borchers, Lothar; Geurtsen, Werner; Günay, Hüsamettin

2008-01-01

This study evaluated the shear bond strength of self-etch adhesives to enamel and the effect of additional phosphoric acid etching. Seventy sound human molars were randomly divided into three test groups and one control group. The enamel surfaces of the control group (n=10) were treated with Syntac Classic (SC). Each test group was subdivided into two groups (each n=10). In half of each test group, ground enamel surfaces were coated with the self-etch adhesives AdheSe (ADH), Xeno III (XE) or Futurabond NR (FNR). In the remaining half of each test group, an additional phosphoric acid etching of the enamel surface was performed prior to applying the adhesives. The shear bond strength was measured with a universal testing machine at a crosshead speed of 1 mm/minute after storing the samples in distilled water at 37 degrees C for 24 hours. Fracture modes were determined by SEM examination. For statistical analysis, one-way ANOVA and the two-sided Dunnett Test were used (p>0.05). Additional phosphoric etching significantly increased the shear bond strength of all the examined self-etch adhesives (p<0.001). The highest shear bond strength was found for FNR after phosphoric acid etching. Without phosphoric acid etching, only FNR showed no significant differences compared to the control (SC). SEM evaluations showed mostly adhesive fractures. For all the self-etch adhesives, a slight increase in mixed fractures occurred after conditioning with phosphoric acid. An additional phosphoric acid etching of enamel should be considered when using self-etch adhesives. More clinical studies are needed to evaluate the long-term success of the examined adhesives.

In vitro bonding effectiveness of three different one-step self-etch adhesives with additional enamel etching.

PubMed

Batra, Charu; Nagpal, Rajni; Tyagi, Shashi Prabha; Singh, Udai Pratap; Manuja, Naveen

2014-08-01

To evaluate the effect of additional enamel etching on the shear bond strength of three self-etch adhesives. Class II box type cavities were made on extracted human molars. Teeth were randomly divided into one control group of etch and rinse adhesive and three test groups of self-etch adhesives (Clearfil S3 Bond, Futurabond NR, Xeno V). The teeth in the control group (n = 10) were treated with Adper™ Single Bond 2. The three test groups were further divided into two subgroups (n = 10): (i) self-etch adhesive was applied as per the manufacturer's instructions; (ii) additional etching of enamel surfaces was done prior to the application of self-etch adhesives. All cavities were restored with Filtek Z250. After thermocycling, shear bond strength was evaluated using a Universal testing machine. Data were analyzed using anova independent sample's 't' test and Dunnett's test. The failure modes were evaluated with a stereomicroscope at a magnification of 10×. Additional phosphoric acid etching of the enamel surface prior to the application of the adhesive system significantly increased the shear bond strength of all the examined self-etch adhesives. Additional phosphoric acid etching of enamel surface significantly improved the shear bond strength. © 2013 Wiley Publishing Asia Pty Ltd.

Dentin pretreatment and adhesive temperature as affecting factors on bond strength of a universal adhesive system.

PubMed

Sutil, Bruna Gabrielle da Silva; Susin, Alexandre Henrique

2017-01-01

To evaluate the effects of dentin pretreatment and temperature on the bond strength of a universal adhesive system to dentin. Ninety-six extracted non-carious human third molars were randomly divided into 12 groups (n=8) according to Scotchbond Universal Adhesive (SbU) applied in self-etch (SE) and etch-and-rinse (ER) mode, adhesive temperature (20°C or 37°C) and sodium bicarbonate or aluminum oxide air abrasion. After composite build up, bonded sticks with cross-sectional area of 1 mm2 were obtained to evaluate the microtensile bond strength (μTBS). The specimens were tested at a crosshead speed of 0.5 mm/min on a testing machine until failure. Fractured specimens were analyzed under stereomicroscope to determine the failure patterns in adhesive, cohesive (dentin or resin) and mixed fractures. The microtensile bond strength data was analyzed using two-way ANOVA and Tukey's test (α=5%). Interaction between treatment and temperature was statistically significant for SbU applied in self-etch technique. Both dentin treatments showed higher bond strength for ER mode, regardless of adhesive temperature. When compared to control group, sodium bicarbonate increased bond strength of SbU in SE technique. Adhesive temperature did not significantly affect the μTBS of tested groups. Predominantly, adhesive failure was observed for all groups. Dentin surface treatment with sodium bicarbonate air abrasion improves bond strength of SbU, irrespective of adhesive application mode, which makes this approach an alternative to increase adhesive performance of Scotchbond Universal Adhesive to dentin.

Dentin pretreatment and adhesive temperature as affecting factors on bond strength of a universal adhesive system

PubMed Central

Sutil, Bruna Gabrielle da Silva; Susin, Alexandre Henrique

2017-01-01

Abstract Objectives: To evaluate the effects of dentin pretreatment and temperature on the bond strength of a universal adhesive system to dentin. Material and Methods: Ninety-six extracted non-carious human third molars were randomly divided into 12 groups (n=8) according to Scotchbond Universal Adhesive (SbU) applied in self-etch (SE) and etch-and-rinse (ER) mode, adhesive temperature (20°C or 37°C) and sodium bicarbonate or aluminum oxide air abrasion. After composite build up, bonded sticks with cross-sectional area of 1 mm2 were obtained to evaluate the microtensile bond strength (μTBS). The specimens were tested at a crosshead speed of 0.5 mm/min on a testing machine until failure. Fractured specimens were analyzed under stereomicroscope to determine the failure patterns in adhesive, cohesive (dentin or resin) and mixed fractures. The microtensile bond strength data was analyzed using two-way ANOVA and Tukey's test (α=5%). Results: Interaction between treatment and temperature was statistically significant for SbU applied in self-etch technique. Both dentin treatments showed higher bond strength for ER mode, regardless of adhesive temperature. When compared to control group, sodium bicarbonate increased bond strength of SbU in SE technique. Adhesive temperature did not significantly affect the μTBS of tested groups. Predominantly, adhesive failure was observed for all groups. Conclusions: Dentin surface treatment with sodium bicarbonate air abrasion improves bond strength of SbU, irrespective of adhesive application mode, which makes this approach an alternative to increase adhesive performance of Scotchbond Universal Adhesive to dentin. PMID:29069151

A clinical study to evaluate denture adhesive use in well-fitting dentures.

PubMed

Munoz, Carlos A; Gendreau, Linda; Shanga, Gilbert; Magnuszewski, Tabetha; Fernandez, Patricia; Durocher, John

2012-02-01

The objective of this study was the assessment of retention and stability and functional benefits of denture adhesive applied to well-fitting and well-made dentures. This was a randomized, crossover study to compare two marketed denture adhesives (test cream, Super Poligrip® Free, and test strip, Super Poligrip® Comfort Seal Strips) and an unmarketed cream adhesive (GlaxoSmith Kline Consumer Healthcare) with no adhesive as the negative control. Thirty-six subjects completed the study. One hour after the application of denture adhesive, retention and stability were measured using the Kapur Index and maxillary incisal bite force. Two hours after application, functional tests were used to assess denture movement and peanut particle migration under the denture. Subjects also rated confidence, comfort, satisfaction with dentures, and denture wobble in conjunction with the functional tests. Denture adhesives significantly (p < 0.05) improved retention and stability of well-fitting dentures. Subjects experienced significantly (p < 0.05) fewer dislodgements while eating an apple after adhesive was applied to dentures. Significant (p < 0.05) increases in subjective ratings of confidence and comfort as well as decreases in denture wobble were associated with the use of adhesive. There was significant (p < 0.05) improvement in satisfaction ratings for cream adhesives. A single application of each denture adhesive was well tolerated. The results of this study provide evidence that use of Super Poligrip® denture adhesives can enhance aspects of performance of complete well-fitting dentures as well as provide increased comfort, confidence, and satisfaction with dentures. © 2011 by the American College of Prosthodontists.

33 CFR 183.584 - Shock test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.584 Shock test. A fuel tank is tested by performing the following procedures in the following order: (a) Perform the static pressure test under § 183... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Shock test. 183.584 Section 183...

33 CFR 183.584 - Shock test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.584 Shock test. A fuel tank is tested by performing the following procedures in the following order: (a) Perform the static pressure test under § 183... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Shock test. 183.584 Section 183...

33 CFR 183.584 - Shock test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.584 Shock test. A fuel tank is tested by performing the following procedures in the following order: (a) Perform the static pressure test under § 183... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Shock test. 183.584 Section 183...

33 CFR 183.584 - Shock test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.584 Shock test. A fuel tank is tested by performing the following procedures in the following order: (a) Perform the static pressure test under § 183... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Shock test. 183.584 Section 183...

33 CFR 183.584 - Shock test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Shock test. 183.584 Section 183... SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.584 Shock test. A fuel tank is tested by performing the following procedures in the following order: (a) Perform the static pressure test under § 183...

16 CFR § 1204.4 - Electric shock protection tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Electric shock protection tests. § 1204.4... Electric shock protection tests. (a) Safety precautions. For tests involving high voltage, the following... Effectiveness Test or the Antenna-Mast System Test if no electrical breakdown occurs and if no current reading...

Conservatism implications of shock test tailoring for multiple design environments

NASA Technical Reports Server (NTRS)

Baca, Thomas J.; Bell, R. Glenn; Robbins, Susan A.

1987-01-01

A method for analyzing shock conservation in test specifications that have been tailored to qualify a structure for multiple design environments is discussed. Shock test conservation is qualified for shock response spectra, shock intensity spectra and ranked peak acceleration data in terms of an Index of Conservation (IOC) and an Overtest Factor (OTF). The multi-environment conservation analysis addresses the issue of both absolute and average conservation. The method is demonstrated in a case where four laboratory tests have been specified to qualify a component which must survive seven different field environments. Final judgment of the tailored test specification is shown to require an understanding of the predominant failure modes of the test item.

The Shock and Vibration Bulletin. Part 3. Acoustic and Vibration Testing, Impact and Blast

DTIC Science & Technology

1976-08-01

Research Institute, San Antonio, Texas DESIGN OF A BLAST LOAD GENERATOR FOR OVERPRESSURE TESTING .................................. 261I P. Lieberman...Mathews and B. W. Duggin, Sandia Laboratories, Albuquerque, New Mexico ESTIMATION OF SHIP SHOCK PARAMETERS FOR CONSISTENT DESIGN AND TEST SPECIFICATION G. C...Seattle, Washington COMPONENT TESTING OF LIQUID SHOCK ISOLATORS AND ELASTOMERS IN SUPPORT OF RECENT SHOCK ISOLATION SYSTEM DESIGNS AJ.IP. Ashley, Boeing

New method for rapid testing of bond strength for wood adhesives

Treesearch

James M. Wescott; Michael J. Birkeland; Amy E. Traska; Charles R. Frihart; Brice N. Dally

2007-01-01

In developing new adhesives for wood bonding, the testing of bond performance can often be a limiting factor in the development process. Evaluating the bond performance of an adhesive that can be prepared in less than a day often takes several days using standard performance tests. This testing slows the development process and may cause a company to abandon a...

A study on the compatibility between one-bottle dentin adhesives and composite resins using micro-shear bond strength.

PubMed

Song, Minju; Shin, Yooseok; Park, Jeong-Won; Roh, Byoung-Duck

2015-02-01

This study was performed to determine whether the combined use of one-bottle self-etch adhesives and composite resins from same manufacturers have better bond strengths than combinations of adhesive and resins from different manufacturers. 25 experimental micro-shear bond test groups were made from combinations of five dentin adhesives and five composite resins with extracted human molars stored in saline for 24 hr. Testing was performed using the wire-loop method and a universal testing machine. Bond strength data was statistically analyzed using two way analysis of variance (ANOVA) and Tukey's post hoc test. Two way ANOVA revealed significant differences for the factors of dentin adhesives and composite resins, and significant interaction effect (p < 0.001). All combinations with Xeno V (Dentsply De Trey) and Clearfil S(3) Bond (Kuraray Dental) adhesives showed no significant differences in micro-shear bond strength, but other adhesives showed significant differences depending on the composite resin (p < 0.05). Contrary to the other adhesives, Xeno V and BondForce (Tokuyama Dental) had higher bond strengths with the same manufacturer's composite resin than other manufacturer's composite resin. Not all combinations of adhesive and composite resin by same manufacturers failed to show significantly higher bond strengths than mixed manufacturer combinations.

Application of electroless Ni-P coating on magnesium alloy via CrO3/HF free titanate pretreatment

NASA Astrophysics Data System (ADS)

Rajabalizadeh, Z.; Seifzadeh, D.

2017-11-01

The titanate conversion coating was applied as CrO3/HF free pretreatment for the electroless Ni-P plating on AM60B magnesium alloy. The microscopic images revealed that the alloy surface was completely covered by a cracked conversion film after titanate pretreatment which was mainly composed of Mg(OH)2/MgO, MgF2, TiO2, SiO2, and Al2O3/Al(OH)3. The microscopic images also revealed that numerous Ni nucleation centers were formed over the titanate film after short electroless plating times. The nucleation centers were created not only on the cracked area but also over the whole pretreated surface due to the catalytic action of the titanate film. Also, uniform, dense, and defect-free Ni-P coating with fine structure was achieved after 3 h plating. The Ni-P coating showed mixed crystalline-amorphous structure due to its moderate phosphorus content. The results of two traditional corrosion monitoring methods indicated that the Ni-P coating significantly increases the corrosion resistance of the magnesium alloy. Moreover, Electrochemical Noise (EN) method was used as a non-polarized technique to study the corrosion behavior of the electroless coating at different immersion times. The results of the EN tests were clearly showed the localized nature of the corrosion process. Micro-hardness value of the magnesium alloy was remarkably enhanced after the electroless plating. Finally, suitable adhesion between the Ni-P coating and the magnesium alloy substrate was confirmed by thermal shock and pull-off-adhesion tests.

Bond strength of different adhesives to normal and caries-affected dentins.

PubMed

Xuan, Wei; Hou, Ben-xiang; Lü, Ya-lin

2010-02-05

Currently, several systems of dentin substrate-reacting adhesives are available for use in the restorative treatment against caries. However, the bond effectiveness and property of different adhesive systems to caries-affected dentin are not fully understood. The objective of this study was to evaluate the bond strength of different adhesives to both normal dentin (ND) and caries-affected dentin (CAD) and to analyze the dentin/adhesive interfacial characteristics. Twenty eight extracted human molars with coronal medium carious lesions were randomly assigned to four groups according to adhesives used. ND and CAD were bonded with etch-and-rinse adhesive Adper Single Bond 2 (SB2) or self-etching adhesives Clearfil SE Bond (CSE), Clearfil S(3) Bond (CS3), iBond GI (IB). Rectangular sticks of resin-dentin bonded interfaces 0.9 mm(2) were obtained. The specimens were subjected to microtensile bond strength (microTBS) testing at a crosshead speed of 1 mm/min. Mean microTBS was statistically analyzed with analysis of variance (ANOVA) and Student-Newman-Keuls tests. Interfacial morphologies were analyzed by Scanning Electron Microscopy (SEM). Etch-and-rinse adhesive Adper(TM) Single Bond 2 yielded high bond strength when applied to both normal and caries-affected dentin. The two-step self-etching adhesive Clearfil SE Bond generated the highest bond strength to ND among all adhesives tested but a significantly reduced strength when applied to CAD. For the one-step self-etching adhesives, Clearfil S(3) Bond and iBond GI, the bond strength was relatively low regardless of the dentin type. SEM interfacial analysis revealed that hybrid layers were thicker with poorer resin tag formation and less resin-filled lateral branches in the CAD than in the ND for all the adhesives tested. The etch-and-rinse adhesive performed more effectively to caries-affected dentin than the self-etching adhesives.

Study on cord/rubber interface at elevated temperatures by H-pull test method

NASA Astrophysics Data System (ADS)

Jamshidi, M.; Afshar, F.; Mohammadi, N.; Pourmahdian, S.

2005-08-01

Cords are used as reinforcing materials in rubber compounds. To increase cord/rubber interfacial adhesion, they are coated by an adhesive (usually based on resorcinol-formaldehyde-latex). These composites are used in many sectors such as tire and belt industries. Cord/rubber adhesion strength is an important aspect to determine the durability of system. Due to temperature increase during running tires, the adhesion energy becomes different from initial one. To study cord/rubber interface at elevated temperatures, H-adhesion test method was used. H-pull test is a simple method for adhesion evaluation at ambient temperature, so it is usually used for material quality control. In this research, cord/rubber systems were vulcanized at different temperatures and H-adhesion of samples were evaluated at elevated temperatures. Also cord/rubber interface was studied by ATR analyze to determine interfacial interactions kind.

Effect of prior silane application on the bond strength of a universal adhesive to a lithium disilicate ceramic.

PubMed

Moro, André Fábio Vasconcelos; Ramos, Amanda Barreto; Rocha, Gustavo Miranda; Perez, Cesar Dos Reis

2017-11-01

Universal adhesives combine silane and various monomers in a single bottle to make them more versatile. Their adhesive performance is unclear. The purpose of this in vitro study was to assess the effects of an additional silane application before using a universal adhesive on the adhesion between a disilicate glass ceramic and a composite resin by using a microshear bond strength test (μSBS) and fracture analysis immediately and after thermocycling. One hundred lithium disilicate glass ceramic disks were divided into 10 groups for bond strength testing according to the following 3 surface treatments: silane application (built-in universal adhesive or with additional application), adhesive (Adper Single Bond Plus [SB, 3M ESPE], Scotchbond Universal Adhesive [U, 3M ESPE], and mixed U with Dual Cure Activator [DCA, 3M ESPE]); or thermocycling (half of the specimens were thermocycled 10000 times). After surface treatment, 5 resin cylinders were bonded to each disk and submitted to a μSBS test. The failure mode was analyzed under a stereomicroscope and evaluated by scanning electron microscope and energy-dispersive x-ray spectroscopy. Data from the μSBS test were analyzed by 3-way ANOVA followed by the Tukey HSD post hoc test (α=.05). An additional silane application resulted in a higher μSBS result for all adhesive groups (P<.05). Ceramic surface treatment influenced the performance of adhesives, which may be improved with an additional silane application. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Endorepellin causes endothelial cell disassembly of actin cytoskeleton and focal adhesions through α2β1 integrin

PubMed Central

Bix, Gregory; Fu, Jian; Gonzalez, Eva M.; Macro, Laura; Barker, Amy; Campbell, Shelly; Zutter, Mary M.; Santoro, Samuel A.; Kim, Jiyeun K.; Höök, Magnus; Reed, Charles C.; Iozzo, Renato V.

2004-01-01

Endorepellin, the COOH-terminal domain of the heparan sulfate proteoglycan perlecan, inhibits several aspects of angiogenesis. We provide evidence for a novel biological axis that links a soluble fragment of perlecan protein core to the major cell surface receptor for collagen I, α2β1 integrin, and provide an initial investigation of the intracellular signaling events that lead to endorepellin antiangiogenic activity. The interaction between endorepellin and α2β1 integrin triggers a unique signaling pathway that causes an increase in the second messenger cAMP; activation of two proximal kinases, protein kinase A and focal adhesion kinase; transient activation of p38 mitogen-activated protein kinase and heat shock protein 27, followed by a rapid down-regulation of the latter two proteins; and ultimately disassembly of actin stress fibers and focal adhesions. The end result is a profound block of endothelial cell migration and angiogenesis. Because perlecan is present in both endothelial and smooth muscle cell basement membranes, proteolytic activity during the initial stages of angiogenesis could liberate antiangiogenic fragments from blood vessels' walls, including endorepellin. PMID:15240572

Calculated shock pressures in the aquarium test

NASA Astrophysics Data System (ADS)

Johnson, J. N.

1982-04-01

A new method of analysis has been developed for determintion of shock pressures in aquarium tests on commercial explosives. This test consists of photographing the expanding cylindrical tube wall (which contains the detonation products) and the shock wave in water surrounding the explosive charge. By making a least-squares fit to the shock-front data, it is possible to determine the peak shock-front pressure as a function of distance from the cylinder wall. This has been done for 10-cm and 20-cm-diam ANFO (ammonium nitrate/fuel oil) and aluminized ANFO (7.5 wt% Al) aquarium test data.

Characterization of Adhesives for Attaching Reusable Surface Insulation on Space Shuttle Vehicles

NASA Technical Reports Server (NTRS)

Owen, H. P.; Carroll, M. T.

1973-01-01

An extensive development and testing program on adhesive systems shows that: (1) A closed cell silicone rubber sponge bonded to substrates with thin bond lines of glass filled adhesive exhibits density and modulus values approximately one third that of solid silicone adhesives; (2) utilization of glass or phenolic microballoons as fillers in silicone adhesives reduces density but increases moduli of the vulcanized materials; (3) the silicone elastomer based adhesives appear to be complex systems rather than homogeneous, isotropic materials. Tensile, shear, and compression properties plotted versus temperature verify this conjecture; and (4) constant strain-stress relaxation tests on glass-filled adhesive show that stress relaxation is most pronounced near the glass transition temperature.

Blister Test for Measurements of Adhesion and Adhesion Degradation of Organic Polymers on AA2024-T3

NASA Astrophysics Data System (ADS)

Rincon Troconis, Brendy Carolina

A key parameter for the performance of corrosion protective coatings applied to metals is adhesion. Surface preparation prior to coating application is known to be critical, but there is a lack of understanding of what controls adhesion. Numerous techniques have been developed in the last decades to measure the adhesion strength of coatings to metals. Nonetheless, they are generally non-quantitative, non-reproducible, performed in dry conditions, or overestimate adhesion. In this study, a quantitative and reproducible technique, the Blister Test (BT), is used. The BT offers the ability to study the effects of a range of parameters, including the presence or absence of a wetting liquid, and simulates the stress situation in the coating/substrate interface. The effects of roughness and surface topography were studied by the BT and Optical Profilometry, using AA2024-T3 substrates coated with polyvinyl butyral (PVB). Random abrasion generated a surface with lower average roughness than aligned abrasion due to the continual cross abrasion of the grooves. The BT could discern the effects of different mechanical treatments. An adhesion strength indicator was defined and found to be a useful parameter. The effectiveness of standard adhesion techniques such as ASTM D4541 (Pull-off Test) and ASTM D3359 (Tape Test) was compared to the BT. Also, different attempts to measure adhesion and adhesion degradation of organic polymers to AA2024-T3 were tested. The pull-off test does not produce adhesive failure across the entire interface, while the tape test is a very qualitative technique and does not discern between the effects of different coating systems on the adhesion performance. The BT produces adhesive failure of the primer studied, is very reproducible, and is able to rank different coating systems. Therefore, it was found to be superior to the others. The approaches tested for adhesion degradation were not aggressive enough to have a measurable effect. The effects of cleaning/desmutting and conversion coating (CC) on the adhesion strength of acetoacetate to AA2024-T3 and the effects of improper water rinse temperature after cleaner were assessed using the BT. The results showed that pretreatments improve the adhesion strength of acetoacetate primer on AA2024-T3, but the comparative behavior depends on the specific treatment. Process control is of paramount importance for the performance of acetoacetate coated systems applied on AA2024-T3. The lack of thermal activity in the water rinse after cleaning step produces deleterious effects on the adhesion and blistering resistance of CC. Finally, a test sample incorporating a coated and scribed Al alloy panel and uncoated through-hole fasteners (Ti, SS316, AA2024-T3) was designed to provide accelerated response during atmospheric corrosion testing in the field (long-term beach exposure) or in laboratory chambers (ASTM B117). The results after only three weeks of exposure to ASTM B117 correlated well with long-term beach exposure, allowing rapid ranking of different coating systems. Of the fastener materials studied, visual observation and volume lost determination indicated that the worst attack occurred near SS316 fasteners its effect was explained by Scanning Kelvin Probe measurements and the available cathodic current measured in chloride solution.

Influence of Etching Mode on Enamel Bond Durability of Universal Adhesive Systems.

PubMed

Suzuki, T; Takamizawa, T; Barkmeier, W W; Tsujimoto, A; Endo, H; Erickson, R L; Latta, M A; Miyazaki, M

2016-01-01

The purpose of this study was to determine the enamel bond durability of three universal adhesives in different etching modes through fatigue testing. The three universal adhesives used were Scotchbond Universal, Prime&Bond Elect universal dental adhesive, and All-Bond Universal light-cured dental adhesive. A single-step self-etch adhesive, Clearfil S 3 Bond Plus was used as a control. The shear bond strength (SBS) and shear fatigue strength (SFS) to human enamel were evaluated in total-etch mode and self-etch mode. A stainless steel metal ring with an internal diameter of 2.4 mm was used to bond the resin composite to the flat-ground (4000-grit) tooth surfaces for determination of both SBS and SFS. For each enamel surface treatment, 15 specimens were prepared for SBS and 30 specimens for SFS. The staircase method for fatigue testing was then used to determine the SFS of the resin composite bonded to the enamel using 10-Hz frequencies for 50,000 cycles or until failure occurred. Scanning electron microscopy was used to observe representative debonded specimen surfaces and the resin-enamel interfaces. A two-way analysis of variance and the Tukey post hoc test were used for analysis of the SBS data, whereas a modified t-test with Bonferroni correction was used for the SFS data. All adhesives in total-etch mode showed significantly higher SBS and SFS values than those in self-etch mode. Although All-Bond Universal in self-etch mode showed a significantly lower SBS value than the other adhesives, there was no significant difference in SFS values among the adhesives in this mode. All adhesives showed higher SFS:SBS ratios in total-etch mode than in self-etch mode. With regard to the adhesive systems used in this study, universal adhesives showed higher enamel bond strengths in total-etch mode. Although the influence of different etching modes on the enamel-bonding performance of universal adhesives was found to be dependent on the adhesive material, total-etch mode effectively increased the enamel bond strength and durability, as measured by fatigue testing.

33 CFR 159.105 - Shock test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Shock test. 159.105 Section 159.105 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.105 Shock test. The device, with liquid...

Comparing the diagnostic properties of skin scraping, adhesive tape, and dermoscopy in diagnosing scabies.

PubMed

Abdel-Latif, Azmy A; Elshahed, Ahmad R; Salama, Omar A; Elsaie, Mohamed L

2018-06-01

Scabies is a contagious skin infestation that mainly presents with itching at night and skin burrows that are visible to the naked eye. Diagnosing scabies with dermoscopy is still a matter of controversy. The aim of our study was to compare the diagnostic properties of adhesive tape, skin scraping, and dermoscopy in diagnosing scabies. One hundred patients with clinical presumptive diagnoses of scabies underwent skin scraping, adhesive tape testing, and dermoscopic examination. Each diagnostic procedure was performed on three different areas. Comparing the diagnostic properties of the three methods, the adhesive tape test was the most sensitive method for diagnosing scabies. Sixteen cases (16.0%) were definitely diagnosed as scabies using the adhesive tape test detecting the presence of mites or their eggs. Only 10 cases (10.0%) were definitely diagnosed as scabies using the skin scraping test detecting mites or their eggs. Dermoscopic examination suggested a diagnosis of scabies in 22 cases (22.0%), of which only 10 were definitely diagnosed as scabies by detecting mites using the adhesive tape test, skin scraping, or both. The diagnosis of scabies can only be confirmed by seeing mites. The adhesive tape test and skin scraping procedure have high specificity in diagnosing scabies, but their low sensitivity cannot exclude the possibility of scabies. Dermoscopy-guided tape testing can be a helpful tool for better diagnosis of scabies.

Investigation of Materials for Boundary Layer Control in a Supersonic Wind Tunnel

NASA Technical Reports Server (NTRS)

Braafladt, Alexander; Lucero, John M.; Hirt, Stefanie M.

2013-01-01

During operation of the NASA Glenn Research Center 15- by 15-Centimeter Supersonic Wind Tunnel (SWT), a significant, undesirable corner flow separation is created by the three-dimensional interaction of the wall and floor boundary layers in the tunnel corners following an oblique-shock/ boundary-layer interaction. A method to minimize this effect was conceived by connecting the wall and floor boundary layers with a radius of curvature in the corners. The results and observations of a trade study to determine the effectiveness of candidate materials for creating the radius of curvature in the SWT are presented. The experiments in the study focus on the formation of corner fillets of four different radii of curvature, 6.35 mm (0.25 in.), 9.525 mm (0.375 in.), 12.7 mm (0.5 in.), and 15.875 mm (0.625 in.), based on the observed boundary layer thickness of 11.43 mm (0.45 in.). Tests were performed on ten candidate materials to determine shrinkage, surface roughness, cure time, ease of application and removal, adhesion, eccentricity, formability, and repeatability. Of the ten materials, the four materials which exhibited characteristics most promising for effective use were the heavy body and regular type dental impression materials, the basic sculpting epoxy, and the polyurethane sealant. Of these, the particular material which was most effective, the heavy body dental impression material, was tested in the SWT in Mach 2 flow, and was observed to satisfy all requirements for use in creating the corner fillets in the upcoming experiments on shock-wave/boundary-layer interaction.

Lap Shear Testing of Candidate Radiator Panel Adhesives

NASA Technical Reports Server (NTRS)

Ellis, David; Briggs, Maxwell; McGowan, Randy

2013-01-01

During testing of a subscale radiator section used to develop manufacturing techniques for a full-scale radiator panel, the adhesive bonds between the titanium heat pipes and the aluminum face sheets failed during installation and operation. Analysis revealed that the thermal expansion mismatch between the two metals resulted in relatively large shear stresses being developed even when operating the radiator at moderate temperatures. Lap shear testing of the adhesive used in the original joints demonstrated that the two-part epoxy adhesive fell far short of the strength required. A literature review resulted in several candidate adhesives being selected for lap shear joint testing at room temperature and 398 K, the nominal radiator operating temperature. The results showed that two-part epoxies cured at room and elevated temperatures generally did not perform well. Epoxy film adhesives cured at elevated temperatures, on the other hand, did very well with most being sufficiently strong to cause yielding in the titanium sheet used for the joints. The use of an epoxy primer generally improved the strength of the joint. Based upon these results, a new adhesive was selected for the second subscale radiator section.

Thermal shock testing for assuring reliability of glass-sealed microelectronic packages

NASA Technical Reports Server (NTRS)

Thomas, Walter B., III; Lewis, Michael D.

1991-01-01

Tests were performed to determine if thermal shocking is destructive to glass-to-metal seal microelectronic packages and if thermal shock step stressing can compare package reliabilities. Thermal shocking was shown to be not destructive to highly reliable glass seals. Pin-pull tests used to compare the interfacial pin glass strengths showed no differences between thermal shocked and not-thermal shocked headers. A 'critical stress resistance temperature' was not exhibited by the 14 pin Dual In-line Package (DIP) headers evaluated. Headers manufactured in cryogenic nitrogen based and exothermically generated atmospheres showed differences in as-received leak rates, residual oxide depths and pin glass interfacial strengths; these were caused by the different manufacturing methods, in particular, by the chemically etched pins used by one manufacturer. Both header types passed thermal shock tests to temperature differentials of 646 C. The sensitivity of helium leak rate measurements was improved up to 70 percent by baking headers for two hours at 200 C after thermal shocking.

Effect of isopropyl myristate on the viscoelasticity and drug release of a drug-in-adhesive transdermal patch containing blonanserinEffect of isopropyl myristate on the viscoelasticity and drug release of a drug-in-adhesive transdermal patch containing blonanserinretain-->.

PubMed

Zhao, Chunyi; Quan, Peng; Liu, Chao; Li, Qiaoyun; Fang, Liang

2016-11-01

The purpose of this study was to investigate the effect of isopropyl myristate (IPM), a penetration enhancer, on the viscoelasticity and drug release of a drug-in-adhesive transdermal patch containing blonanserin. The patches were prepared with DURO-TAK ® 87-2287 as a pressure-sensitive adhesive (PSA) containing 5% ( w / w ) of blonanserin and different concentrations of IPM. An in vitro release experiment was performed and the adhesive performance of the drug-in-adhesive patches with different concentrations of IPM was evaluated by a rolling ball tack test and a shear-adhesion test. The glass transition temperature ( T g ) and rheological parameters of the drug-in-adhesive layers were determined to study the effect of IPM on the mechanical properties of the PSA. The results of the in vitro release experiment showed that the release rate of blonanserin increased with an increasing concentration of IPM. The rolling ball tack test and shear-adhesion test showed decreasing values with increasing IPM concentration. The results were interpreted on the basis of the IPM-induced plasticization of the PSA, as evidenced by a depression of the glass transition temperature and a decrease in the elastic modulus. In conclusion, IPM acted as a plasticizer on DURO-TAK ® 87-2287, and it increased the release of blonanserin and affected the adhesive properties of the PSA.

Cytotoxic effects of denture adhesives on primary human oral keratinocytes, fibroblasts and permanent L929 cell lines.

PubMed

Chen, Fengying; Wu, Tianfu; Cheng, Xiangrong

2014-03-01

To date, there have been very little data on the cytotoxic responses of different cell lines to denture adhesives. To determine the cytotoxicity of three denture adhesives on primary human oral keratinocytes (HOKs), fibroblasts (HOFs) and permanent mouse fibroblasts cell lines (L929). Three commercial denture adhesives (two creams and one powder) were prepared for indirect contact using the agar diffusion test, as well as extracts in MTT assay. The results of the MTT assay were statistically analysed by one-way anova and Tukey's test (p < 0.05). All of the tested denture adhesives showed mild to moderate cytotoxicity to primary HOKs (p < 0.001), whereas none of three was toxic to L929 cells (p > 0.05) in both assays. For primary HOFs cultures, slight cytotoxicity was observed for one of the products from the agar diffusion test and undiluted eluates of all tested adhesives with MTT assay (p < 0.01). Denture adhesives are toxic to the primary HOKs and HOFs cultures, whereas non-toxic to L929 cells. The results suggest that primary human oral mucosal cells may provide more valuable information in toxicity screening of denture adhesives. © 2012 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd.

Standardized Laboratory Test Requirements for Hardening Equipment to Withstand Wave Impact Shock in Small High Speed Craft

DTIC Science & Technology

2017-02-06

and methodology for transitioning craft acceleration data to laboratory shock test requirements are summarized and example requirements for...engineering rationale, assumptions, and methodology for transitioning craft acceleration data to laboratory shock test requirements are summarized and... Methodologies for Small High-Speed Craft Structure, Equipment, Shock Isolation Seats, and Human Performance At-Sea, 10 th Symposium on High

Effect of Saliva on the Tensile Bond Strength of Different Generation Adhesive Systems: An In-Vitro Study.

PubMed

Gupta, Nimisha; Tripathi, Abhay Mani; Saha, Sonali; Dhinsa, Kavita; Garg, Aarti

2015-07-01

Newer development of bonding agents have gained a better understanding of factors affecting adhesion of interface between composite and dentin surface to improve longevity of restorations. The present study evaluated the influence of salivary contamination on the tensile bond strength of different generation adhesive systems (two-step etch-and-rinse, two-step self-etch and one-step self-etch) during different bonding stages to dentin where isolation is not maintained. Superficial dentin surfaces of 90 extracted human molars were randomly divided into three study Groups (Group A: Two-step etch-and-rinse adhesive system; Group B: Two-step self-etch adhesive system and Group C: One-step self-etch adhesive system) according to the different generation of adhesives used. According to treatment conditions in different bonding steps, each Group was further divided into three Subgroups containing ten teeth in each. After adhesive application, resin composite blocks were built on dentin and light cured subsequently. The teeth were then stored in water for 24 hours before sending for testing of tensile bond strength by Universal Testing Machine. The collected data were then statistically analysed using one-way ANOVA and Tukey HSD test. One-step self-etch adhesive system revealed maximum mean tensile bond strength followed in descending order by Two-step self-etch adhesive system and Two-step etch-and-rinse adhesive system both in uncontaminated and saliva contaminated conditions respectively. Unlike One-step self-etch adhesive system, saliva contamination could reduce tensile bond strength of the two-step self-etch and two-step etch-and-rinse adhesive system. Furthermore, the step of bonding procedures and the type of adhesive seems to be effective on the bond strength of adhesives contaminated with saliva.

Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives.

PubMed

Baracco, Bruno; Fuentes, M Victoria; Garrido, Miguel A; González-López, Santiago; Ceballos, Laura

2013-07-01

The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24 h and 5,000 thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers' instructions. Composite buildups were constructed and the bonded teeth were then stored in water (24 h, 37 °C) or thermocycled (5,000 cycles) before being sectioned and submitted to MTBS test. Two-way ANOVA and subsequent comparison tests were applied at α = 0.05. Characteristic de-bonded specimens were analyzed using scanning electron microscopy (SEM). After 24 h water storage, MTBS values were highest with XP Bond, Adper Scotchbond 1 XT, Filtek Silorane Adhesive System and Adper Scotchbond SE and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. After thermocycling, MTBS values were highest with XP Bond, followed by Filtek Silorane Adhesive System, Adper Scotchbond SE and Adper Scotchbond 1 XT and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. Thermal aging induced a significant decrease in MTBS values with all adhesives tested. The resistance of resin-dentin bonds to thermal-aging degradation was material dependent. One-step self-etch adhesives obtained the lowest MTBS results after both aging treatments, and their adhesive capacity was significantly reduced after thermocycling.

Microtensile bond strength of three simplified adhesive systems to caries-affected dentin.

PubMed

Scholtanus, J D; Purwanta, Kenny; Dogan, Nilgun; Kleverlaan, Cees J; Feilzer, Albert J

2010-08-01

The purpose of the study was to determine the microtensile bond strength of three different simplified adhesive systems to caries-affected dentin. Fifteen extracted human molars with primary carious lesions were ground flat until dentin was exposed. Soft caries-infected dentin was excavated with the help of caries detector dye. On the remaining hard dentin, a standardized smear layer was created by polishing with 600-grit SiC paper. Teeth were divided into three groups and treated with one of the three tested adhesives: Adper Scotchbond 1 XT (3M ESPE), a 2-step etch-andrinse adhesive, Clearfil S3 Bond (Kuraray), a 1-step self-etching or all-in-one adhesive, and Clearfil SE Bond (Kuraray), a 2-step self-etching adhesive. Five-mm-thick composite buildups (Z-250, 3M ESPE) were built and light cured. After water storage for 24 h at 37ºC, the bonded specimens were sectioned into bars (1.0 x 1.0 mm; n = 20 to 30). Microtensile bond strength of normal dentin specimens and caries-affected dentin specimens was measured in a universal testing machine (crosshead speed = 1 mm/min). Data were analyzed using two-way ANOVA and Tukey's post-hoc test (p < 0.05). No significant differences in bond strength values to normal dentin between the three adhesives were found. Adper Scotchbond 1 XT and Clearfil S3 Bond showed significantly lower bond strength values to caries-affected dentin. For Clearfil SE Bond, bond strength values to normal and caries-affected dentin were not significantly different. All the tested simplified adhesives showed similar bond strength values to normal dentin. For the tested 2-step etch-and-rinse adhesive and the all-in-one adhesive, the bond strength values to caries-affected dentin were lower than to normal dentin.

Heat flux instrumentation for Hyflite thermal protection system

NASA Technical Reports Server (NTRS)

Diller, T. E.

1994-01-01

Using Thermal Protection Tile core samples supplied by NASA, the surface characteristics of the FRCI, TUFI, and RCG coatings were evaluated. Based on these results, appropriate methods of surface preparation were determined and tested for the required sputtering processes. Sample sensors were fabricated on the RCG coating and adhesion was acceptable. Based on these encouraging results, complete Heat Flux Microsensors were fabricated on the RCG coating. The issue of lead attachment was addressed with the annnealing and welding methods developed at NASA Lewis. Parallel gap welding appears to be the best method of lead attachment with prior heat treatment of the sputtered pads. Sample Heat Flux Microsensors were submitted for testing in the NASA Ames arc jet facility. Details of the project are contained in two attached reports. One additional item of interest is contained in the attached AIAA paper, which gives details of the transient response of a Heat Flux Microsensors in a shock tube facility at Virginia Tech. The response of the heat flux sensor was measured to be faster than 10 micro-s.

Development of thin wraparound junction silicon solar cells

NASA Technical Reports Server (NTRS)

Ho, F.; Iles, P. A.

1981-01-01

The state of the art technologies was applied to fabricate 50 micro thick 2x4 cm, coplanar back contact (CBC) solar cells with AMO efficiency above 12%. A requirement was that the cells have low solar absorptance. A wraparound junction (WAJ) with wraparound metallization was chosen. This WAJ approach avoided the need for very complex fixturing, especially during rotation of the cells for providing adequate contacts over dielectric edge layers. The contact adhesion to silicon was considered better than to an insulator. It is indicated that shunt resistance caused by poor WAJ diode quality, and series resistance from the WAJ contact, give good cell performance. The cells developed reached 14 percent AMO efficiency (at 25 C), with solar absorptance values of 0.73. Space/cell environmental tests were performed on these cells and the thin CSC cells performed well. The optimized design configuration and process sequence were used to make 50 deliverable CBC cells. These cells were all above 12 percent efficiency and had an average efficiency of -13 percent. Results of environmental tests (humidity-temperature, thermal shock, and contact adherence) are also given.

Effects of etch-and-rinse and self-etch adhesives on dentin MMP-2 and MMP-9.

PubMed

Mazzoni, A; Scaffa, P; Carrilho, M; Tjäderhane, L; Di Lenarda, R; Polimeni, A; Tezvergil-Mutluay, A; Tay, F R; Pashley, D H; Breschi, L

2013-01-01

Auto-degradation of collagen matrices occurs within hybrid layers created by contemporary dentin bonding systems, by the slow action of host-derived matrix metalloproteinases (MMPs). This study tested the null hypothesis that there are no differences in the activities of MMP-2 and -9 after treatment with different etch-and-rinse or self-etch adhesives. Tested adhesives were: Adper Scotchbond 1XT (3M ESPE), PQ1 (Ultradent), Peak LC (Ultradent), Optibond Solo Plus (Kerr), Prime&Bond NT (Dentsply) (all 2-step etch-and-rinse adhesives), and Adper Easy Bond (3M ESPE), Tri-S (Kuraray), and Xeno-V (Dentsply) (1-step self-etch adhesives). MMP-2 and -9 activities were quantified in adhesive-treated dentin powder by means of an activity assay and gelatin zymography. MMP-2 and MMP-9 activities were found after treatment with all of the simplified etch-and-rinse and self-etch adhesives; however, the activation was adhesive-dependent. It is concluded that all two-step etch-and-rinse and the one-step self-etch adhesives tested can activate endogenous MMP-2 and MMP-9 in human dentin. These results support the role of endogenous MMPs in the degradation of hybrid layers created by these adhesives.

Effects of Etch-and-Rinse and Self-etch Adhesives on Dentin MMP-2 and MMP-9

PubMed Central

Mazzoni, A.; Scaffa, P.; Carrilho, M.; Tjäderhane, L.; Di Lenarda, R.; Polimeni, A.; Tezvergil-Mutluay, A.; Tay, F.R.; Pashley, D.H.; Breschi, L.

2013-01-01

Auto-degradation of collagen matrices occurs within hybrid layers created by contemporary dentin bonding systems, by the slow action of host-derived matrix metalloproteinases (MMPs). This study tested the null hypothesis that there are no differences in the activities of MMP-2 and -9 after treatment with different etch-and-rinse or self-etch adhesives. Tested adhesives were: Adper Scotchbond 1XT (3M ESPE), PQ1 (Ultradent), Peak LC (Ultradent), Optibond Solo Plus (Kerr), Prime&Bond NT (Dentsply) (all 2-step etch-and-rinse adhesives), and Adper Easy Bond (3M ESPE), Tri-S (Kuraray), and Xeno-V (Dentsply) (1-step self-etch adhesives). MMP-2 and -9 activities were quantified in adhesive-treated dentin powder by means of an activity assay and gelatin zymography. MMP-2 and MMP-9 activities were found after treatment with all of the simplified etch-and-rinse and self-etch adhesives; however, the activation was adhesive-dependent. It is concluded that all two-step etch-and-rinse and the one-step self-etch adhesives tested can activate endogenous MMP-2 and MMP-9 in human dentin. These results support the role of endogenous MMPs in the degradation of hybrid layers created by these adhesives. PMID:23128110

On the Interplay Between Adhesion Strength and Tensile Properties of Thermal Spray Coated Laminates—Part I: High Velocity Thermal Spray Coatings

NASA Astrophysics Data System (ADS)

Luo, Xiaotao; Smith, Gregory M.; Sampath, Sanjay

2018-02-01

Adhesion of thermal spray (TS) coatings is an important system level property in coating design and application. Adhesive-based pull testing (ASTM C633) has long been used to evaluate coating/substrate bonding. However, this approach is not always suitable for high velocity spray coatings, for example, where adhesion strengths are routinely greater than the strength of the adhesive bonding agent used in the testing. In this work, a new approach has been proposed to evaluate the adhesion of TS coatings. A systematic investigation of the effects of substrate roughness on both the uniaxial tensile yield strength and traditional bond pull adhesive strength of HVOF Ni and Ni-5wt.%Al, as well as cold-sprayed Ni-coated laminates revealed a strong correlation between these two test methodologies for the respective materials and processes. This approach allows measurement of the adhesion response even where the adhesive method is not applicable, overcoming many of the issues in the traditional ASTM C633. Analysis of cracking patterns of the coatings after 10.5% strain was used to assess the adhesion and cohesion properties. The mechanisms which determine the load transfer between the substrate and the coating are also briefly discussed.

Analysis of the interphase of a polyamide bonded to chromic acid anodized Ti-6AL-4V

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guinta, R.K.; Kander, R.G.

2000-01-06

Structural adhesive joints, when tested as made, typically fail cohesively through the centerline of the adhesive. However, in any study of adhesive joint durability, failure near the adhesive/substrate interface becomes an important consideration. In the current study, an interfacially debonding adhesive test, the notched coating adhesion (NCA) test, was applied to LaRC(trademark) PETI-5 adhesive bonded to chronic acid anodized (CAA) Ti-6Al-4V. Post-failure analysis of the interphase region included X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). Mechanical interlocking between an adhesive and a substrate occurs when the liquid adhesivemore » flows into interstices of the substrate, solidifies, and becomes locked in place. Mechanical interlocking is believed to significantly contribute to the adhesion of substrates that exhibit microroughness, such as metal surfaces treated with chromic acid anodization or sodium hydroxide anodization. Filbey and Wightman found that an epoxy penetrated the pores of CAA Ti-6Al-4V, one of the limited number of pore penetration studies that have been reported. In the current study, the penetration of PETI-5 into the pores of CAA Ti-6Al-4V is investigated through analysis of adhesive/substrate failure surfaces.« less

Drying time of tray adhesive for adequate tensile bond strength between polyvinylsiloxane impression and tray resin material.

PubMed

Yi, Myong-Hee; Shim, Joon-Sung; Lee, Keun-Woo; Chung, Moon-Kyu

2009-07-01

Use of custom tray and tray adhesive is clinically recommended for elastomeric impression material. However there is not clear mention of drying time of tray adhesive in achieving appropriate bonding strength of tray material and impression material. This study is to investigate an appropriate drying time of tray adhesives by evaluating tensile bonding strength between two types of polyvinylsiloxane impression materials and resin tray, according to various drying time intervals of tray adhesives, and with different manufacturing company combination of impression material and tray adhesive. Adhesives used in this study were Silfix (Dentsply Caulk, Milford, Del, USA) and VPS Tray Adhesive (3M ESPE, Seefeld, Germany) and impression materials were Aquasil Ultra (monophase regular set, Dentsply Caulk, Milford, Del, USA) and Imprint II Garant (regular body, 3M ESPE, Seefeld, Germany). They were used combinations from the same manufacture and exchanged combinations of the two. The drying time was designed to air dry, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. Total 240 of test specimens were prepared by auto-polymerizing tray material (Instant Tray Mix, Lang, Wheeling, Il, USA) with 10 specimens in each group. The specimens were placed in the Universal Testing machine (Instron, model 3366, Instron Corp, University avenue, Nowood, MA, USA) to perform the tensile test (cross head speed 5 mm/min). The statistically efficient drying time was evaluated through ANOVA and Scheffe test. All the tests were performed at 95% confidence level. The results revealed that at least 10 minutes is needed for Silfix-Aquasil, and 15 minutes for VPS Tray Adhesive-Imprint II, to attain an appropriate tensile bonding strength. VPS Tray Adhesive-Imprint II had a superior tensile bonding strength when compared to Silfix-Aquasil over 15 minutes. Silfix-Aquasil had a superior bonding strength to VPS Tray Adhesive-Aquasil, and VPS Tray Adhesive-Imprint II had a superior tensile bonding strength to Silfix-Imprint II at all drying periods. Significant increase in tensile bonding strength with Silfix-Aquasil and VPS Tray adhesive-Imprint II combination until 10 and 15 minutes respectively. Tray adhesive-impression material combination from the same company presented higher tensile bonding strength at all drying time intervals than when using tray adhesive-impression material of different manufactures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kubouchi, Masatoshi; Hojo, Hidemitsu

The thermal shock resistance of epoxy resin specimens toughened with carboxy-terminated poly(butadiene-acrylonitrile) (CTBN) and poly-glycol were tested using a new notched disk-type specimen. The new thermal shock testing method consists of quenching a notched disk-type specimen and applying a theoretical analysis to the test results to determine crack propagation conditions. For both toughened epoxy resins, this test method evaluated improvements in thermal shock resistance. The thermal shock resistance of epoxy resin toughened with CTBN exhibited a maximum at a 35 parts per hundred resin content of CTBN. The epoxy resin toughened with polyglycol exhibited improved thermal shock resistance with increasingmore » glycol content. 7 refs., 14 figs., 1 tab.« less

Drop Hammer Tests with Three Oleo Strut Models and Three Different Shock Strut Oils at Low Temperatures

NASA Technical Reports Server (NTRS)

Kranz, M

1954-01-01

Drop hammer tests with different shock strut models and shock strut oils were performed at temperatures ranging to -40 C. The various shock strut models do not differ essentially regarding their springing and damping properties at low temperatures; however, the influence of the different shock strut oils on the springing properties at low temperatures varies greatly.

Adhesion mechanisms of bituminous crack sealant to aggregate and laboratory test development

NASA Astrophysics Data System (ADS)

Hajialiakbari Fini, Elham

Crack sealing is a common pavement maintenance treatment because it extends pavement service life. However, crack sealant often fails prematurely due to a loss of adhesion. Since current test methods are mostly empirical and only provide a qualitative measure of bond strength, they cannot predict sealant adhesive failure accurately. Hence, there is an urgent need for test methods based on bituminous sealant rheology that can better predict sealant field performance. This study introduces three laboratory tests aimed to assess the bond property of hot-poured crack sealant to pavement crack walls. The three tests are designed to serve the respective needs of producers, engineers, and researchers. The first test implements the principle of surface energy to measure the thermodynamic work of adhesion, which is the energy spent in separating the two materials at the interface. The work of adhesion is reported as a measure of material compatibility at an interface. The second test is a direct adhesion test, a mechanical test which is designed to closely resemble both the installation process and the crack expansion due to thermal loading. This test uses the Direct Tension Test (DTT) device. The principle of the test is to apply a tensile force to detach the sealant from its aggregate counterpart. The maximum load, Pmax, and the energy to separation, E, are calculated and reported to indicate interface bonding. The third test implements the principles of fracture mechanics in a pressurized circular blister test. The apparatus is specifically designed to conduct the test for bituminous crack sealant, asphalt binder, or other bitumen-based materials. In this test, a fluid is injected at a constant rate at the interface between the substrate (aggregate or a standard material) and the adhesive (crack sealant) to create a blister. The fluid pressure and blister height are measured as functions of time; the data is used to calculate Interfacial Fracture Energy (IFE), which is a fundamental property that can be used to predict adhesion. The stable interface debonding process makes this test attractive. This test also may be used to estimate the optimum annealing time, and to quantify other interface characteristics, such as the moisture susceptibility of a bond. In addition, the elastic modulus of the sealant and its residual stresses can be determined analytically. While the direct adhesion test is proposed as part of newly-developed performance-based guidelines for the selection of hot-poured crack sealant, the blister test may be used to estimate the optimum annealing time, in addition to IFE determination.

Capabilities of electrodynamic shakers when used for mechanical shock testing

NASA Technical Reports Server (NTRS)

Keegan, W. B.

1973-01-01

The results of a research task to investigate the capabilities of electrodynamic vibrators (shakers) to perform mechanical shock tests are presented. The simulation method employed was that of developing a transient whose shock response spectrum matched the desired shock response spectrum. Areas investigated included the maximum amplitude capabilities of the shaker systems, the ability to control the shape of the resultant shock response spectrum, the response levels induced at frequencies outside the controlled bandwidth, and the nonlinearities in structural response induced by a change in test level.

Adhesive capability of total-etch, self-etch, and self-adhesive systems for fiber post cementation

NASA Astrophysics Data System (ADS)

Theodor, Y.; Koesmaningati, H.; Gita, F.

2017-08-01

The aim of this study was to analyze whether self-etch and self-adhesive systems are comparable to the total-etch system for fiber post cementation. This experimental laboratory study, which was approved by an ethics committee, was performed using 27 mandibular premolar teeth randomly divided into three groups. Fiber post cementation was done using three different adhesive systems. Specimens were prepared with a thickness of 5 mm, which was measured from the cervical to medial areas of the root, and stored for 24 h in saline solution at room temperature. A push-out test was performed using a universal testing machine (Shimidzu AG-5000E) with a crosshead speed of 0.5 mm/min. The results of one way ANOVA bivariate testing showed that the total-etch and self-etch systems have comparable adhesion capability (p<0.05) and that the self-adhesive system has the lowest adhesion capability (p>0.05). With easier application, the self-etch system has a comparable adhesion capability to the total-etch system.

Viscoelastic and fatigue properties of model methacrylate-based dentin adhesives

PubMed Central

Singh, Viraj; Misra, Anil; Marangos, Orestes; Park, Jonggu; Ye, Qiang; Kieweg, Sarah L.; Spencer, Paulette

2013-01-01

The objective of the current study is to characterize the viscoelastic and fatigue properties of model methacrylate-based dentin adhesives under dry and wet conditions. Static, creep, and fatigue tests were performed on cylindrical samples in a 3-point bending clamp. Static results showed that the apparent elastic modulus of the model adhesive varied from 2.56 to 3.53 GPa in the dry condition, and from 1.04 to 1.62 GPa in the wet condition, depending upon the rate of loading. Significant differences were also found for the creep behavior of the model adhesive under dry and wet conditions. A linear viscoelastic model was developed by fitting the adhesive creep behavior. The developed model with 5 Kelvin Voigt elements predicted the apparent elastic moduli measured in the static tests. The model was then utilized to interpret the fatigue test results. It was found that the failure under cyclic loading can be due to creep or fatigue, which has implications for the failure criterion that are applied for these types of tests. Finally, it was found that the adhesive samples tested under dry conditions were more durable than those tested under wet conditions. PMID:20848661

Development and Realization of a Shock Wave Test on Expert Flap Qualification Model

NASA Astrophysics Data System (ADS)

De Fruytier, C.; Dell'Orco, F.; Ullio, R.; Gomiero, F.

2012-07-01

This paper presents the methodology and the results of the shock test campaign conducted by TAS-I and TAS ETCA to qualify the EXPERT Flap in regards of shock wave and acoustic load generated by pyrocord detonation at stages 2/3 separation phase of the EXPERT vehicle. The design concept of the open flap (manufactured by MT AEROSPACE) is a fully integral manufactured, four sided control surface, with an additional stiffening rib and flanges to meet the first eigenfrequency and the allowable deformation requirement with a minimum necessary mass. The objectives were to reproduce equivalent loading at test article level in terms of pulse duration, front pressure, front velocity and acoustic emission. The Thales Alenia Space ETCA pyrotechnic shock test device is usually used to produce high level shocks by performing a shock on a test fixture supporting the unit under test. In this case, the facility has been used to produce a shock wave, with different requested physical characteristics, directed to the unit under test. Different configurations have been tried on a dummy of the unit to test, following an empirical process. This unusual work has lead to the definition of a nominal set- up meeting the requested physical parameters. Two blast sensors have been placed to acquire the pressure around the flap. The distance between the two sensors has allowed estimating the front pressure velocity. Then, several locations have been selected to acquire the acceleration responses on the unit when it was submitted to this environment. Additionally, a “standard” shock test has been performed on this model. The qualification of the flap, in regards of shock environment, has been successfully conducted.

Learned helplessness: effects of response requirement and interval between treatment and testing.

PubMed

Hunziker, M H L; Dos Santos, C V

2007-11-01

Three experiments investigated learned helplessness in rats manipulating response requirements, shock duration, and intervals between treatment and testing. In Experiment 1, rats previously exposed to uncontrollable or no shocks were tested under one of four different contingencies of negative reinforcement: FR 1 or FR 2 escape contingency for running, and FR1 escape contingency for jumping (differing for the maximum shock duration of 10s or 30s). The results showed that the uncontrollable shocks produced a clear operant learning deficit (learned helplessness effect) only when the animals were tested under the jumping FR 1 escape contingency with 10-s max shock duration. Experiment 2 isolated of the effects of uncontrollability from shock exposure per se and showed that the escape deficit observed using the FR 1 escape jumping response (10-s shock duration) was produced by the uncontrollability of shock. Experiment 3 showed that using the FR 1 jumping escape contingency in the test, the learned helplessness effect was observed one, 14 or 28 days after treatment. These results suggest that running may not be an appropriate test for learned helplessness, and that many diverging results found in the literature might be accounted for by the confounding effects of respondent and operant contingencies present when running is required of rats.

[ABILITY OF STAPHYLOCOCCUS OF VARIOUS STRAINS TO CREATE BIOFILMS AND THEIR EFFECT ON HUMAN BODY CELLS].

PubMed

Kornienko, M A; Kopyltsov, V N; Shevlyagina, N V; Didenko, L V; Lyubasovskaya, L A; Priputnevich, T V; Ilina, E N

2016-01-01

The urgency of the staphylococcus research is due to its ability to cause severe infections: softtissue infections, endocarditis, sepsis, toxic shock syndrome, and food poisoning. Coagulase-positive Staphylococcus aureus is the main infection agent of intrahospital infections. This agent has many factors of pathogenicity, which are well known. Among the coagulase-negative staphylococcus (CNS) strains, S. haemolyticus and S. epidermidis are clinically important, because they cause infections in patients with weak immune system. The mechanisms of the CNS pathogenicity are insufficiently understood. The goal of this work was to evaluate the potential pathogenicity of clinical strains of CNS from their capacity to create biofilms and the character of their interaction with human body cells by the example of the HT-29 cell culture. The research was carried out in laboratory strain S. aureus ATCC 29213 and clinical strains S. haemolyticus SH39, S. epidermidis SE36-1 isolated from the neonatal autopsy materials. The visual tests of biofilm formation by each strain and testing of the impact of the strains on the cell culture HT-29 was carried out in this work. The two species of CNS form biofilms at a higher rate than S. aureus. Upon incubation for 2 h of HT-29 cells with staphylococcus strains tested in this work, adhesion of bacteria on cell surface was observed. The adhesion was most pronounced in case of S. aureus ATCC 29213 and S. haemolyticus SH39. Upon 3 h of incubation with S. aureus ATCC 29213 and S. haemolyticus SH39, destruction of cell HT-29 monolayer was observed. The incubation for 24 h with the 3 strains tested in this work caused complete destruction of cell HT-29 monolayer. The maximal toxic effect on HT-29 cells was inherent in the strain S. haemolyticus SH39. The aggregate of the results obtained in this work indicates the presence of the pathogenicity factors in the strains S. haemolyticus SH39, which require additional research.

Long-term In Vitro Adhesion of Polyalkenoate-based Adhesives to Dentin.

PubMed

Sezinando, Ana; Perdigão, Jorge; Ceballos, Laura

2017-01-01

To study the influence of a polyalkenoate copolymer (VCP) on the immediate (24 h) and 6-month dentin bonding stability of VCP-based adhesives, using microtensile bond strength (μTBS), nanoleakage (NL), and ultramorphological analyses (FE-SEM). Eighty-four caries-free molars were randomly assigned to seven adhesives: Clearfil SE Bond (CSE, Kuraray Noritake); Adper Single Bond Plus (SB, 3M ESPE); SB without VCP (SBnoVCP, 3M ESPE); Scotchbond Universal Adhesive applied as a etch-and-rinse adhesive (SBU_ER); SBU without VCP applied as an etch-and-rinse adhesive (SBUnoVCP_ER); SBU applied as a self-etch adhesive (SBU_SE, 3M ESPE); SBU without VCP applied as a self-etch adhesive (SBUnoVCP_SE, 3M ESPE). Half of the beams were tested after 24 h, and the other half was aged in water for 6 months prior to testing. For each tooth/evaluation time, two beams were randomly selected for NL analysis. Statistical analyses of µTBS results were performed using two-way ANOVA, Tukey's post-hoc tests, and Student's t-test for paired data (α = 0.05). Nanoleakage was statistically analyzed using the Kruskal-Wallis and Mann-Whitney tests, with Wilcoxon's test for paired data. For FE-SEM, four caries-free molars were assigned to each of the seven groups. Dentin disks were restored and cross sectioned into halves. One half was observed at 24 h, and the other at 6 months. The highest 6-month mean μTBS was obtained with SBU_SE/SBUnoVCP_SE and SBUnoVCP_ER. SBUnoVCP_SE resulted in greater silver deposition at 6 months. FE-SEM observations showed that CSE and SBU_SE specimens resulted in a submicron hybrid layer without signs of degradation at 6 months. VCP may contribute to the long-term bonding stability of VCP-based adhesives.

Influence of dentin pretreatment on bond strength of universal adhesives.

PubMed

Poggio, Claudio; Beltrami, Riccardo; Colombo, Marco; Chiesa, Marco; Scribante, Andrea

2017-01-01

Objective: The purpose of the present study was to compare bond strength of different universal adhesives under three different testing conditions: when no pretreatment was applied, after 37% phosphoric acid etching and after glycine application. Materials and methods: One hundred and fifty bovine permanent mandibular incisors were used as a substitute for human teeth. Five different universal adhesives were tested: Futurabond M+, Scotchbond Universal, Clearfil Universal Bond, G-Premio BOND, Peak Universal Bond. The adhesive systems were applied following each manufacturer's instructions. The teeth were randomly assigned to three different dentin surface pretreatments: no pretreatment agent (control), 37% phosphoric acid etching, glycine pretreatment. The specimens were placed in a universal testing machine in order to measure and compare bond strength values. Results: The Kruskal-Wallis analysis of variance and the Mann-Whitney test were applied to assess significant differences among the groups. Dentin pretreatments provided different bond strength values for the adhesives tested, while similar values were registered in groups without dentin pretreatment. Conclusions: In the present report, dentin surface pretreatment did not provide significant differences in shear bond strength values of almost all groups. Acid pretreatment lowered bond strength values of Futurabond and Peak Universal Adhesives, whereas glycine pretreatment increased bond strength values of G Praemio Bond adhesive system.

Influence of dentin pretreatment on bond strength of universal adhesives

PubMed Central

Poggio, Claudio; Beltrami, Riccardo; Colombo, Marco; Chiesa, Marco; Scribante, Andrea

2017-01-01

Abstract Objective: The purpose of the present study was to compare bond strength of different universal adhesives under three different testing conditions: when no pretreatment was applied, after 37% phosphoric acid etching and after glycine application. Materials and methods: One hundred and fifty bovine permanent mandibular incisors were used as a substitute for human teeth. Five different universal adhesives were tested: Futurabond M+, Scotchbond Universal, Clearfil Universal Bond, G-Premio BOND, Peak Universal Bond. The adhesive systems were applied following each manufacturer’s instructions. The teeth were randomly assigned to three different dentin surface pretreatments: no pretreatment agent (control), 37% phosphoric acid etching, glycine pretreatment. The specimens were placed in a universal testing machine in order to measure and compare bond strength values. Results: The Kruskal–Wallis analysis of variance and the Mann–Whitney test were applied to assess significant differences among the groups. Dentin pretreatments provided different bond strength values for the adhesives tested, while similar values were registered in groups without dentin pretreatment. Conclusions: In the present report, dentin surface pretreatment did not provide significant differences in shear bond strength values of almost all groups. Acid pretreatment lowered bond strength values of Futurabond and Peak Universal Adhesives, whereas glycine pretreatment increased bond strength values of G Praemio Bond adhesive system. PMID:28642929

Doxycycline-encapsulated nanotube-modified dentin adhesives.

PubMed

Feitosa, S A; Palasuk, J; Kamocki, K; Geraldeli, S; Gregory, R L; Platt, J A; Windsor, L J; Bottino, M C

2014-12-01

This article presents details of fabrication, biological activity (i.e., anti-matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)-encapsulated halloysite nanotube (HNT)-modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives-but, more important, to support the hypothesis that the HNT+DOX adhesive would release DOX at subantimicrobial levels-we tested the antimicrobial activity of synthesized adhesives and the DOX-containing eluates against Streptococcus mutans through agar diffusion assays. Anti-MMP properties were assessed via β-casein cleavage assays. Increasing curing times (10, 20, 40 sec) led to increased DC values. There were no statistically significant differences (p > .05) in DC within each increasing curing time between the modified adhesives compared to SBMP. No statistically significant differences in microtensile bond strength were noted. None of the adhesives eluates were cytotoxic to the human dental pulp stem cells. A significant growth inhibition of S. mutans by direct contact illustrates successful encapsulation of DOX into the experimental adhesive. More important, DOX-containing eluates promoted inhibition of MMP-1 activity when compared to the control. Collectively, our findings provide a solid background for further testing of encapsulated MMP inhibitors into the synthesis of therapeutic adhesives that may enhance the longevity of hybrid layers and the overall clinical performance of adhesively bonded resin composite restorations. © International & American Associations for Dental Research.

21 CFR 864.6650 - Platelet adhesion test.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Platelet adhesion test. 864.6650 Section 864.6650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6650 Platelet adhesion...

21 CFR 864.6650 - Platelet adhesion test.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Platelet adhesion test. 864.6650 Section 864.6650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6650 Platelet adhesion...

21 CFR 864.6650 - Platelet adhesion test.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Platelet adhesion test. 864.6650 Section 864.6650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6650 Platelet adhesion...

Adhesion of multimode adhesives to enamel and dentin after one year of water storage.

PubMed

Vermelho, Paulo Moreira; Reis, André Figueiredo; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

2017-06-01

This study aimed to evaluate the ultramorphological characteristics of tooth-resin interfaces and the bond strength (BS) of multimode adhesive systems to enamel and dentin. Multimode adhesives (Scotchbond Universal (SBU) and All-Bond Universal) were tested in both self-etch and etch-and-rinse modes and compared to control groups (Optibond FL and Clearfil SE Bond (CSB)). Adhesives were applied to human molars and composite blocks were incrementally built up. Teeth were sectioned to obtain specimens for microtensile BS and TEM analysis. Specimens were tested after storage for either 24 h or 1 year. SEM analyses were performed to classify the failure pattern of beam specimens after BS testing. Etching increased the enamel BS of multimode adhesives; however, BS decreased after storage for 1 year. No significant differences in dentin BS were noted between multimode and control in either evaluation period. Storage for 1 year only reduced the dentin BS for SBU in self-etch mode. TEM analysis identified hybridization and interaction zones in dentin and enamel for all adhesives. Silver impregnation was detected on dentin-resin interfaces after storage of specimens for 1 year only with the SBU and CSB. Storage for 1 year reduced enamel BS when adhesives are applied on etched surface; however, BS of multimode adhesives did not differ from those of the control group. In dentin, no significant difference was noted between the multimode and control group adhesives, regardless of etching mode. In general, multimode adhesives showed similar behavior when compared to traditional adhesive techniques. Multimode adhesives are one-step self-etching adhesives that can also be used after enamel/dentin phosphoric acid etching, but each product may work better in specific conditions.

Inductionless or limited shock testing is possible in most patients with implantable cardioverter- defibrillators/cardiac resynchronization therapy defibrillators: results of the multicenter ASSURE Study (Arrhythmia Single Shock Defibrillation Threshold Testing Versus Upper Limit of Vulnerability: Risk Reduction Evaluation With Implantable Cardioverter-Defibrillator Implantations).

PubMed

Day, John D; Doshi, Rahul N; Belott, Peter; Birgersdotter-Green, Ulrika; Behboodikhah, Mahnaz; Ott, Peter; Glatter, Kathryn A; Tobias, Serge; Frumin, Howard; Lee, Byron K; Merillat, John; Wiener, Isaac; Wang, Samuel; Grogin, Harlan; Chun, Sung; Patrawalla, Rob; Crandall, Brian; Osborn, Jeffrey S; Weiss, J Peter; Lappe, Donald L; Neuman, Stacey

2007-05-08

Implantable cardioverter-defibrillators and cardiac resynchronization therapy defibrillators have relied on multiple ventricular fibrillation (VF) induction/defibrillation tests at implantation to ensure that the device can reliably sense, detect, and convert VF. The ASSURE Study (Arrhythmia Single Shock Defibrillation Threshold Testing Versus Upper Limit of Vulnerability: Risk Reduction Evaluation With Implantable Cardioverter-Defibrillator Implantations) is the first large, multicenter, prospective trial comparing vulnerability safety margin testing versus defibrillation safety margin testing with a single VF induction/defibrillation. A total of 426 patients receiving an implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator underwent vulnerability safety margin or defibrillation safety margin screening at 14 J in a randomized order. After this, patients underwent confirmatory testing, which required 2 VF conversions without failure at < or = 21 J. Patients who passed their first 14-J and confirmatory tests, irrespective of the results of their second 14-J test, had their devices programmed to a 21-J shock for ventricular tachycardia (VT) or VF > or = 200 bpm and were followed up for 1 year. Of 420 patients who underwent 14-J vulnerability safety margin screening, 322 (76.7%) passed. Of these, 317 (98.4%) also passed 21-J confirmatory tests. Of 416 patients who underwent 14-J defibrillation safety margin screening, 343 (82.5%) passed, and 338 (98.5%) also passed 21-J confirmatory tests. Most clinical VT/VF episodes (32 of 37, or 86%) were terminated by the first shock, with no difference in first shock success. In all observed cases in which the first shock was unsuccessful, subsequent shocks terminated VT/VF without complication. Although spontaneous episodes of fast VT/VF were limited, there was no difference in the odds of first shock efficacy between groups. Screening with vulnerability safety margin or defibrillation safety margin may allow for inductionless or limited shock testing in most patients.

Effect of multi-adhesive layering on retention of extraoral maxillofacial silicone prostheses in vivo.

PubMed

Kiat-Amnuay, Sudarat; Gettleman, Lawrence; Goldsmith, L Jane

2004-09-01

Loss of retention of maxillofacial prostheses often makes the margin visible or the prosthesis dislodge. Using several medical adhesives in combination may improve retention. The purpose of this study was to investigate the effect of single- and multi-adhesive layering of 2 adhesives on the retention of maxillofacial silicone elastomer strips adhered to the skin of human forearms using a peel test. Power analysis from a previous study and a pilot trial specified at least 20 subjects. Eight Silastic Adhesive A/MDX4-4210 silicone rubber strips (N=240) were applied in a predetermined random order to the left and right ventral forearms of 30 IRB-approved human subjects. Skin-Prep Protective Dressing was applied. Secure 2 Medical Adhesive (SMA) and Epithane-3 (E3) adhesive were used alone or as SMA/E3 or E3/SMA sandwiches (from skin to prosthesis) to adhere strips. Strips were peeled 6 hours later in a universal testing machine at 10 cm/min and data reported in N/m. Paired t tests were used to evaluate left and right arm differences. A Friedman test for nonparametric correlated data with within-subject design was performed, determining differences between both adhesives singly and in combination (alpha=.05). Tests of left-right differences were insignificant ( P =0.43), so the data from both arms were combined. Many strips with E3 did not adhere before testing and were counted as 0 adhesion. Median peel strengths (and 25th and 75th percentiles) in N/m were: SMA = 76.1 (47.1-107), E3 = 6.75 (0.0-25.9), SMA/E3 = 107 (78.0-132), and E3/SMA= 19.6 (6.99-42.4). All 4 variables were significantly different ( P <.0005). The multi-adhesive combination of SMA/E3 had the highest adhesion, followed, in order, by SMA alone, E3/ SMA, and E3 alone. Both E3 groups left a difficult-to-remove residue on the skin. SMA/E3 left a halo-like residue on the skin at the periphery of the strips from the E3 leaking around the SMA. SMA remained adherent to the prosthetic material.

Effects of variables upon pyrotechnically induced shock response spectra, part 2

NASA Technical Reports Server (NTRS)

Smith, James Lee

1988-01-01

Throughout the aerospace industry, large variations of 50 percent (6 dB) or more in shock response spectra (SRS) derived from pyrotechnic separation events continue to be reported from actual spaceflight data and from laboratory tests. As a result of these variations, NASA funded a research program for 1984 through 1986. The purpose of the 1984 through 1986 project was to analyze variations in pyrotechnically induced SRS and to determine if and to what degree manufacturing and assembly variables and tolerances, distance from the shock source, data acquisition instrumentation, and shock energy propagation affect the SRS. Sixty-four free-free boundary plate tests were performed. NASA funded an additional study for 1987 through 1988. This paper is a summary of the additional study. The purpose was to evaluate shock dissipation through various spacecraft structural joint types, to evaluate shock variation for various manufacturing and assembly variables on clamped boundary test plates, and to verify data correction techniques. Five clamped boundary plate tests investigated manufacturing and assembly variables and mass loading effects. Six free-free boundary plate tests investigated shock dissipation across spacecraft joint structures.

Study on the Strength of GFRP/Stainless Steel Adhesive Joints Reinforced with Glass Mat

NASA Astrophysics Data System (ADS)

Iwasa, Masaaki

The adhesive strengths of glass fiber reinforced plastics/metal adhesive joints reinforced with glass mat under tensile shear loads and tensile loads were investigated analytically and experimentally. First, the stress singularity parameters of the bonding edges were analyzed by FEM for various types of adhesive joints reinforced with glass mat. The shear stress and normal stress distributions near the bonding edge can be expressed by two stress singularity parameters. Second, tensile shear tests were performed on taper lap joint and taper lap joint reinforced with glass mat and tensile tests were performed on T-type adhesive joint and T-type adhesive joint reinforced with glass mat. The relationships between the loads and the crosshead displacements were measured. We concluded that reinforcing adhesive joints has a greater effect on strength under tensile load than under tensile shear load. The adhesive joints strength reinforced with glass mat can be evaluated by using stress singularity parameters.

Prevention of Trauma/Hemorrhagic Shock-Induced Mortality, Apoptosis, Inflammation and Mitochondrial Dysfunction Using IL-6 as a Resuscitation Adjuvant

DTIC Science & Technology

2011-12-01

infiltrating PMNs is not merely limited to organs that have been directly injured from trauma. Ischemia - reperfusion injury (which occurs after... injury by facilitating inflammatory cell adhesion in an animal model of myocardial ischemia - reperfusion [61,62]. Fabp2 and Fabp5 have been implicated in...Bauer A, Tweardy DJ (1998) Activation of STAT proteins following ischemia reperfusion injury demonstrates a distinct IL- 6 and G-CSF mediated profile

Method of making a quartz resonator

DOEpatents

Vig, John R.; Filler, Raymond L.; Peters, R. Donald; Frank, James M.

1981-01-01

A quartz resonator is made from a chemically polished quartz plate. The plate is placed in an enclosure fitted with at least three mounting clips to receive the plate. The plate is secured to the clips with an electrically conductive adhesive capable of withstanding operation at 350 degrees C. The assembly is cleaned and a metallic electrode deposited onto the plate until the desired frequency is reached. The enclosure is then hermetically sealed. The resulting resonator can consistently withstand extremely high shocks.

Satisfaction in complete denture wearers with and without adhesives: A randomized, crossover, double-blind clinical trial

PubMed Central

Torres-Sánchez, Carlos; Montoya-Salazar, Vanessa; Gutierrez-Pérez, Jose-Luis; Jimenez-Castellanos, Emilio

2018-01-01

Background The purpose of this study was to compare the satisfaction of patients regarding retention, stability and accumulation of particles with a randomized, double-blind crossed method in users with complete dentures with and without adhesive. Material and Methods Seventeen edentulous individuals were randomized and received new upper and lower complete dentures. After a period of adaptation, they participated in some masticatory tests and clinical revisions, after use the protheses with and without the use of two denture adhesives: Adhesive A (Fittydent, Fittydent International GmbH) and adhesive B (Corega, GlaxoSmithKline) at 0, 7 and 14 days. Satisfaction was measured immediately after each test through a survey using a VAS scale (0-10) and data were analyzed with McNemar’s test with Bonferroni correction. Results The results showed significant differences (p<.01) between the study groups with adhesive A - B and the group without adhesive, but no significant differences were found between the two stickers for any of the variables studied. Conclusions Complete denture adhesives significantly improved the satisfaction of patients because a better retention, stability and less accumulation of particles of the food substitute between the denture and the mucosa is obtained compared with non-use of complete denture adhesives. Key words:Complete dentures, patient satisfaction, denture adhesives, clinical trials. PMID:29946414

Test Operations Procedure (TOP) 10-2-400 Open End Compressed Gas Driven Shock Tube

DTIC Science & Technology

gas-driven shock tube. Procedures are provided for instrumentation, test item positioning, estimation of key test parameters, operation of the shock...tube, data collection, and reporting. The procedures in this document are based on the use of helium gas and Mylar film diaphragms.

Evaluation of microtensile bond strength of self-etching adhesives on normal and caries-affected dentin.

PubMed

Shibata, Shizuma; Vieira, Luiz Clovis Cardoso; Baratieri, Luiz Narciso; Fu, Jiale; Hoshika, Shuhei; Matsuda, Yasuhiro; Sano, Hidehiko

2016-01-01

The purpose of this study was to evaluate the µTBS (microtensile bond strength) of currently available self-etching adhesives with an experimental self-etch adhesive in normal and caries-affected dentin, using a portable hardness measuring device, in order to standardize dentin Knoop hardness. Normal (ND) and caries-affected dentin (CAD) were obtained from twenty human molars with class II natural caries. The following adhesive systems were tested: Mega Bond (MB), a 2-step self-etching adhesive; MTB-200 (MTB), an experimental 1-step self-etching adhesive (1-SEA), and two commercially available one-step self-etching systems, G-Bond Plus (GB) and Adper Easy Bond (EB). MB-ND achieved the highest µTBS (p<0.05). The mean µTBS was statistically lower in CAD than in ND for all adhesives tested (p<0.05), and the 2-step self-etch adhesive achieved better overall performance than the 1-step self-etch adhesives.

A second-generation constrained reaction volume shock tube

NASA Astrophysics Data System (ADS)

Campbell, M. F.; Tulgestke, A. M.; Davidson, D. F.; Hanson, R. K.

2014-05-01

We have developed a shock tube that features a sliding gate valve in order to mechanically constrain the reactive test gas mixture to an area close to the shock tube endwall, separating it from a specially formulated non-reactive buffer gas mixture. This second-generation Constrained Reaction Volume (CRV) strategy enables near-constant-pressure shock tube test conditions for reactive experiments behind reflected shocks, thereby enabling improved modeling of the reactive flow field. Here we provide details of the design and operation of the new shock tube. In addition, we detail special buffer gas tailoring procedures, analyze the buffer/test gas interactions that occur on gate valve opening, and outline the size range of fuels that can be studied using the CRV technique in this facility. Finally, we present example low-temperature ignition delay time data to illustrate the CRV shock tube's performance.

Evaluation of glued-diaphragm fibre optic pressure sensors in a shock tube

NASA Astrophysics Data System (ADS)

Sharifian, S. Ahmad; Buttsworth, David R.

2007-02-01

Glued-diaphragm fibre optic pressure sensors that utilize standard telecommunications components which are based on Fabry-Perot interferometry are appealing in a number of respects. Principally, they have high spatial and temporal resolution and are low in cost. These features potentially make them well suited to operation in extreme environments produced in short-duration high-enthalpy wind tunnel facilities where spatial and temporal resolution are essential, but attrition rates for sensors are typically very high. The sensors we consider utilize a zirconia ferrule substrate and a thin copper foil which are bonded together using an adhesive. The sensors show a fast response and can measure fluctuations with a frequency up to 250 kHz. The sensors also have a high spatial resolution on the order of 0.1 mm. However, with the interrogation and calibration processes adopted in this work, apparent errors of up to 30% of the maximum pressure have been observed. Such errors are primarily caused by mechanical hysteresis and adhesive viscoelasticity. If a dynamic calibration is adopted, the maximum measurement error can be limited to about 10% of the maximum pressure. However, a better approach is to eliminate the adhesive from the construction process or design the diaphragm and substrate in a way that does not require the adhesive to carry a significant fraction of the mechanical loading.

Effect of changes to the manufacturer application techniques 
on the shear bond strength of simplified dental adhesives.

PubMed

Chasqueira, Ana Filipa; Arantes-Oliveira, Sofia; Portugal, Jaime

2013-09-13

The aim of this work was to assess the shear bond strength (SBS) between a composite resin and dentin, promoted by two dental adhesive systems (one-step self-etching adhesive Easy Bond [3M ESPE], and two-step etch-and-rinse adhesive Scotchbond 1XT [3M ESPE]) with different application protocols (per manufacturer's instruction (control group); with one to four additional adhesive layers; or with an extra hydrophobic adhesive layer). Proximal enamel was removed from ninety caries-free human molars to obtain two dentin discs per tooth, which were randomly assigned to twelve experimental groups (n=15). After adhesion protocol, the composite resin (Filtek Z250 [3M ESPE]) was applied. Specimens were mounted in the Watanabe test device and shear bond test was performed in a universal testing machine with a crosshead speed of 5 mm/min. Data were analyzed with ANOVA followed by Student-Newman-Keuls tests (P<0.05). The highest SBS mean value was attained with the Easy Bond three layers group (41.23±2.71 MPa) and the lowest with Scotchbond 1XT per manufacturer's instructions (27.15±2.99 MPa). Easy Bond yielded higher SBS values than Scotchbond 1XT. There were no statistically significant differences (P>0.05) between the application protocols tested, except for the three and four layers groups, that presented higher SBS results compared to manufacturer's instruction groups (P<0.05). No statistically significant differences were detected between the three and four layers groups (P≥0.05). It is recommendable to apply three adhesive layers when using Easy Bond and Scotchbond 1XT adhesives, since it improves SBS values without consuming much time.

LIGS measurements in the nozzle reservoir of a free-piston shock tunnel

NASA Astrophysics Data System (ADS)

Altenhöfer, P.; Sander, T.; Koroll, F.; Mundt, Ch.

2018-02-01

Free-piston shock tunnels are ground-based test facilities allowing the simulation of reentry flow conditions in a simple and cost-efficient way. For a better understanding of the processes occurring in a shock tunnel as well as for an optimal comparability of experimental data gained in shock tunnels to numerical simulations, it is highly desirable to have the best possible characterization of the generated test gas flows. This paper describes the final step of the development of a laser-induced grating spectroscopy (LIGS) system capable of measuring the temperature in the nozzle reservoir of a free-piston shock tunnel during tests: the successful adaptation of the measurement system to the shock tunnel. Preliminary measurements were taken with a high-speed camera and a LED lamp in order to investigate the optical transmissibility of the measurement volume during tests. The results helped to successfully measure LIGS signals in shock tube mode and shock tunnel mode in dry air seeded with NO. For the shock tube mode, six successful measurements for a shock Mach number of about 2.35 were taken in total, two of them behind the incoming shock (p ≈ 1 MPa, T ≈ 600 K) and four after the passing of the reflected shock (p ≈ 4 MPa, T ≈ 1000 K). For five of the six measurements, the derived temperatures were within a deviation range of 6% to a reference value calculated from measured shock speed. The uncertainty estimated was less than or equal to 3.5% for all six measurements. Two LIGS signals from measurements behind the reflected shock in shock tunnel mode were analyzed in detail. One of the signals allowed an unambiguous derivation of the temperature under the conditions of a shock with Mach 2.7 (p ≈ 5 MPa, T ≈ 1200 K, deviation 0.5% , uncertainty 4.9% ).

Doxycycline-Encapsulated Nanotube-Modified Dentin Adhesives

PubMed Central

Feitosa, S.A.; Palasuk, J.; Kamocki, K.; Geraldeli, S.; Gregory, R.L.; Platt, J.A.; Windsor, L.J.; Bottino, M.C.

2014-01-01

This article presents details of fabrication, biological activity (i.e., anti–matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)–encapsulated halloysite nanotube (HNT)–modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives—but, more important, to support the hypothesis that the HNT+DOX adhesive would release DOX at subantimicrobial levels—we tested the antimicrobial activity of synthesized adhesives and the DOX-containing eluates against Streptococcus mutans through agar diffusion assays. Anti-MMP properties were assessed via β-casein cleavage assays. Increasing curing times (10, 20, 40 sec) led to increased DC values. There were no statistically significant differences (p > .05) in DC within each increasing curing time between the modified adhesives compared to SBMP. No statistically significant differences in microtensile bond strength were noted. None of the adhesives eluates were cytotoxic to the human dental pulp stem cells. A significant growth inhibition of S. mutans by direct contact illustrates successful encapsulation of DOX into the experimental adhesive. More important, DOX-containing eluates promoted inhibition of MMP-1 activity when compared to the control. Collectively, our findings provide a solid background for further testing of encapsulated MMP inhibitors into the synthesis of therapeutic adhesives that may enhance the longevity of hybrid layers and the overall clinical performance of adhesively bonded resin composite restorations. PMID:25201918

Temperature Effects on Adhesive Bond Strengths and Modulus for Commonly Used Spacecraft Structural Adhesives

NASA Technical Reports Server (NTRS)

Ojeda, Cassandra E.; Oakes, Eric J.; Hill, Jennifer R.; Aldi, Dominic; Forsberg, Gustaf A.

2011-01-01

A study was performed to observe how changes in temperature and substrate material affected the strength and modulus of an adhesive bondline. Seven different adhesives commonly used in aerospace bonded structures were tested. Aluminum, titanium and Invar adherends were cleaned and primed, then bonded using the manufacturer's recommendations. Following surface preparation, the coupons were bonded with the adhesives. The single lap shear coupons were then pull tested per ASTM D 1002 Standard Test Method for Apparent Shear Strength of Single- Lap-Joint over a temperature range from -150 deg C up to +150 deg C. The ultimate strength was calculated and the resulting data were converted into B-basis design allowables. Average and Bbasis results were compared. Results obtained using aluminum adherends are reported. The effects of using different adherend materials and temperature were also studied and will be reported in a subsequent paper. Dynamic Mechanical Analysis (DMA) was used to study variations in adhesive modulus with temperature. This work resulted in a highly useful database for comparing adhesive performance over a wide range of temperatures, and has facilitated selection of the appropriate adhesive for spacecraft structure applications.

Hepatoprotective Effects of Corilagin Following Hemorrhagic Shock are Through Akt-Dependent Pathway

PubMed Central

Liu, Fu-Chao; Chaudry, Irshad H.; Yu, Huang-Ping

2017-01-01

ABSTRACT Corilagin, a component of Phyllanthus urinaria extract, possesses antioxidant, thrombolytic, antiatherogenic, and hepatoprotective properties, but the mechanism underlying these effects remains unclear. Previous studies showed that the Akt (protein kinase B) signaling pathway exerts anti-inflammatory and organ protective effects. The aim of this study was to investigate the mechanism of action of corilagin and determine whether these effects are mediated through the Akt-dependent pathway in a trauma-hemorrhagic shock-induced liver injury rodent model. Hemorrhagic shock was induced in male Sprague–Dawley rats; mean blood pressure was maintained at 35 mm Hg to 40 mm Hg for 90 min, followed by fluid resuscitation. During resuscitation, three doses of corilagin alone (1 mg/kg, 5 mg/kg, or 10 mg/kg, intravenously) were administered. Furthermore, a single dose of corilagin (5 mg/kg) with and without Wortmannin (1 mg/kg, PI3K inhibitor), Wortmannin alone, or vehicle was administered. Twenty-four hours after resuscitation, plasma alanine aminotransferase and aspartate aminotransferase concentration and hepatic parameters were measured. One-way ANOVA was used for statistical analysis. Hepatic myeloperoxidase activity and the concentrations of plasma alanine aminotransferase and aspartate aminotransferase, interleukin-6, tumor necrosis factor-α, intercellular adhesion molecule-1, and cytokine-induced neutrophil chemoattractant-1 (CINC-1) and CINC-3 increased following hemorrhagic shock. These parameters were significantly attenuated in corilagin-treated rats following hemorrhagic shock. Hepatic phospho-Akt expression was also higher in corilagin-treated rats than in vehicle-treated rats. The elevation of phospho-Akt was abolished by combined treatment with Wortmannin and corilagin. Our results suggest that corilagin exerts its protective effects on hemorrhagic shock-induced liver injury, at least, via the Akt-dependent pathway. PMID:27559697

Support and Development of Workflow Protocols for High Throughput Single-Lap-Joint Testing-Experimental

DTIC Science & Technology

2013-04-01

preparation, and presence of an overflow fillet for a high strength epoxy and ductile methacylate adhesive. A unique feature of this study was the...of expanding adhesive joint test configurations as part of the GEMS program. 15. SUBJECT TERMS single lap joint, adhesion, aluminum, epoxy ... epoxy and ductile methacylate adhesive. A unique feature of this study was the use of untrained GEMS (Gains in the Education of Mathematics and Sci

Nondestructive Evaluation of Adhesive Bond Quality: State of the Art Review

DTIC Science & Technology

1989-06-01

conducted using a and Harnik (6) developed a quantitative medium-focused, 1/4-inch diameter, 10-MHz method of testing adhesive bonded joints transducer...Couchman." Spectral Analysis Tech- E. Harnik . "The Testing of Adhesive- nique of Ultrasonic NDT of Advanced Bonded Joints by a Very High Resolu

Inconsistent shock advisories for monomorphic VT and Torsade de Pointes--A prospective experimental study on AEDs and defibrillators.

PubMed

Fitzgerald, Abi; Johnson, Meshell; Hirsch, Jan; Rich, Mary-Ann; Fidler, Richard

2015-07-01

Cardiovascular disease and sudden cardiac arrest are the leading causes of death in the United States. Early defibrillation is key to successful resuscitation for patients who experience shockable rhythms during a cardiac arrest. It is therefore vital that the shock advisory of AEDs (automated external defibrillators) or defibrillators in AED mode be reliable and appropriate. The goal of this study was to better understand the performance of multiple lay-rescuer and hospital professional defibrillators in AED mode in their analysis of ventricular arrhythmias. The measurable objectives of this study sought to quantify: 1. No shock advisory for sinus rhythms at any rate. 2. Recognition and shock advisory for ventricular fibrillation (VF). 3. Recognition and shock advisory for monomorphic ventricular tachycardia (VT). 4. Recognition and shock advisory for Torsades de Pointes (TdP). This is a prospective evaluation of two AEDs and four semi-automatic, hospital professional defibrillators. This study represents post-marketing evaluation of FDA approved devices. Each defibrillator was connected to multiple rhythm simulators and presented with simulated ECG waveforms 20 consecutive times at various rates when possible. All four defibrillators and both AEDs tested consistently recognized normal sinus rhythm (NSR) from all rhythm sources, and did not recommend a shock for NSR at any rate (from 80 to 220 bpm). All four defibrillators and both AEDs recognized VF from all rhythm sources tested and recommended a shock 100% of the time. Variations were found in the shock advisory rates among defibrillators when testing simulated VT heart rates at or below 150 bpm. One AED tested did not consistently advise a shock for monomorphic VT or TdP at any tested rate. Lay-rescuer AEDs and professional hospital defibrillators tested in AED mode did not reliably recommend a shock for sustained monomorphic VT or TdP at certain rates, despite the fact that it is a critical component of the currently recommended treatment. These findings require further examination of the risk benefit analysis of shocking or not shocking rhythms such as TdP or pulseless VT. Published by Elsevier Ireland Ltd.

Retention strength of impression materials to a tray material using different adhesive methods: an in vitro study.

PubMed

Marafie, Yousef; Looney, Stephen; Nelson, Steven; Chan, Daniel; Browning, William; Rueggeberg, Frederick

2008-12-01

A new self-stick adhesive system has been purported to eliminate the need to use chemical adhesives with plastic impression trays; however, no testing has confirmed the claim. The purpose of this study was to compare the in vitro retentive strength of impression materials to plastic substrates having conventional adhesive (CA) or the self-stick adhesive system, with and without mechanical retention. Three types of impression materials (irreversible hydrocolloid (IH), vinyl polysiloxane (VPS), and polyether (PE)) were applied to polystyrene disc-shaped surfaces (33.68 cm(2)) that were held on the arms of a universal testing machine. The appropriate CA or the self-stick adhesive system (Self-Stick Dots) (SSD) was applied to the plates, which had either no mechanical retention, or equally spaced mechanical perforations (n=4). An in vivo pilot test determined the appropriate rate of plate separation. Plates with impression material were lowered to provide 4 mm of space, the material set, and plates were separated using the appropriate speed. Force at first separation was divided by plate area (peak stress). Five replications per test condition were made, and results were analyzed using ANOVA and Bonferroni-adjusted t tests (alpha=.05). Within each impression material/test combination, stress using SSD was significantly lower than CA (P<.05). Mechanical retention did not always provide significantly greater strength. The combination of mechanical retention and CA yielded the highest strength within each material type, except for PE, for which nonmechanical and CA strength did not differ from that of mechanical and CA. Use of the self-stick adhesive system provided significantly lower retentive strength to plastic tray material than chemical adhesives for irreversible hydrocolloid, vinyl polysiloxane, and polyether.

Watertight cataract incision closure using fibrin tissue adhesive.

PubMed

Hovanesian, John A; Karageozian, Vicken H

2007-08-01

To determine whether a simple method for applying fibrin tissue adhesive to a clear corneal cataract incision can create a watertight seal. Laboratory investigation. Clear corneal cataract incisions were simulated in 8 eye-bank eyes. In 4 eyes, fibrin adhesive was applied to the incision in a simple manner; the other 4 eyes were controls with no adhesive. Each eye was tested under low pressure conditions to detect fluid ingress of India Ink on the eye's surface. The eyes were tested again with external compression to distort the incision to detect fluid egress. In the eyes with fibrin adhesive, there was no egress of fluid with incision distortion and no ingress of India Ink. In the 4 eyes without adhesive, there was ingress and egress of fluid. A simple method of applying fibrin adhesive to cataract incisions created a watertight seal.

Bond durability of adhesives containing modified-monomer with/without-fluoride after aging in artificial saliva and under intrapulpal pressure simulation.

PubMed

El-Deeb, H A; Al Sherbiney, H H; Mobarak, E H

2013-01-01

To evaluate the dentin bond strength durability of adhesives containing modified-monomer with/without-fluoride after storage in artificial saliva and under intrapulpal pressure simulation (IPPS). The occlusal enamel of 48 freshly extracted teeth was trimmed to expose midcoronal dentin. Roots were sectioned to expose the pulp chamber and to connect the specimens to the pulpal-pressure assembly. Specimens were assigned into four groups (n=12) according to adhesive system utilized: a two-step etch-and-rinse adhesive system (SB, Adper Single Bond 2, 3M ESPE), a two-step self-etch adhesive system (CSE, Clearfil SE Bond, Kuraray Medical Inc), and two single-step self-etch adhesives with the same modified monomer (bis-acrylamide)-one with fluoride (AOF, AdheSE One F, Ivoclar-Vivadent) and the other without (AO, AdheSE One, Ivoclar-Vivadent). Bonding was carried out while the specimens were subjected to 15-mm Hg IPPS. Resin composite (Valux Plus, 3M ESPE) buildups were made. After curing, specimens were aged in artificial saliva and under 20-mm Hg IPPS at 37°C in a specially constructed incubator either for 24 hours or six months prior to testing. Bonded specimens (n=6/group) were sectioned into sticks (n=24/group) with a cross section of 0.9 ± 0.01 mm(2) and subjected to microtensile bond strength (μTBS) testing using a universal testing machine. Data were statistically analyzed using two-way analysis of variance (ANOVA) with repeated measures, one-way ANOVA tests, and a t-test (p<0.05). Failure modes were determined using a scanning electron microscope. The μTBS values of SB and CSE fell significantly after six-month storage in artificial saliva and under IPPS, yet these values remained significantly higher than those for the other two adhesives with modified monomers. There was no significant difference in the bond strength values between fluoride-containing and fluoride-free self-etch adhesive systems (AOF and AO) after 24 hours or six months. Modes of failure were mainly adhesive and mixed. Based on the results of this study, 1) Fluoride addition did not affect dentin bond durability; and 2) despite the fact that the single-step adhesive system with modified monomer showed stability, bond strengths associated with these systems remained lower than those of multistep adhesive systems.

Influence of pH cycling on the microtensile bond strength of self-etching adhesives containing MDPB and fluoride to dentin and microhardness of enamel and dentin adjacent to restorations.

PubMed

Pedrosa, Vivianne Oliveira; Flório, Flávia Martão; Turssi, Cecília Pedroso; Amaral, Flávia Lucisano; Basting, Roberta Tarkany; França, Fabiana Mantovani

2012-12-01

To evaluate the influence of pH cycling on microtensile bond strength (µTBS) and fracture pattern of MDPB- and fluoride-containing self-etching adhesive systems to dentin, and on the cross-sectional Knoop microhardness (CSMH) of enamel and dentin adjacent to restorations. The two-step self-etching adhesive Clearfil SE Bond (SE; Kuraray), the two-step MDPBand fluoride-containing adhesive Clearfil Protect Bond (PB; Kuraray), and the one-step fluoride-containing adhesive One-Up Bond F Plus (OU; Tokuyama) were used to bond resin composite to midcoronal dentin surfaces (for µTBS testing) or to Class V cavities (for CSMH testing). µTBS and CSMH tests were performed after a 15-day period of pH cycling or storage in artificial saliva. µTBS to dentin was not affected by pH cycling or storage in artificial saliva; however, µTBS values found for PB were higher than those observed for OU. No difference existed among the µTBS values shown by PB, OU, and SE. The fracture pattern was affected by both pH cycling and adhesive system. In enamel, there was no difference in CSMH values provided by the different adhesive systems and storage media, regardless of the distance and depth from restoration. In dentin, PB and SE showed the highest CSMH values, which differed from those obtained for OU. Significantly higher CSMH values were found 100 µm from the restoration margin for all adhesive systems tested. The bond strength and microhardness in the vicinity of restorations were adhesive dependent, with MDPB and fluoride exerting no effect on the performance of the adhesive systems.

Mini-interfacial fracture toughness as a new validated enamel-bonding effectiveness test.

PubMed

Pongprueksa, Pong; De Munck, Jan; Barreto, Bruno C; Karunratanakul, Kavin; Van Meerbeek, Bart

2016-09-01

Today׳s most commonly applied bonding effectiveness tests are criticized for their high variability and low reliability, the latter in particular with regard to measuring the actual strength of the adhesive interface. in continuation of previous research conducted at dentin, we hereby aimed to validate the novel mini-interfacial fracture toughness (mini-iFT) test on its applicability to assess bonding effectiveness of contemporary adhesives when bonded to enamel. The 3-step etch&rinse (E&R) adhesive OptiBond FL (Kerr), the 2-step self-etch (SE) adhesive Clearfil SE Bond (Kuraray Noritake) and the two multi-mode adhesives Clearfil S(3) Bond Plus (Kuraray Noritake) and Scotchbond Universal (3M ESPE), both used following a 2-step E&R and 1-step SE mode, were applied to clinically relevant, flattened enamel surfaces. A composite (Filtek Z100; 3M ESPE) build-up was made in layers. After 1-week water storage at 37°C, all specimens were sectioned perpendicular to the interface to obtain rectangular sticks. A mini-iFT notch was prepared at the adhesive-enamel interface using a thin diamond blade under water cooling. Finally, the specimens were loaded in a 4-point bending test until failure. the mini-iFT onto human enamel was significantly higher for the adhesives applied in E&R mode versus those applied in SE mode. The lowest mini-iFT was found for the adhesives applied following a 1-step SE approach. SEM fracture analysis revealed that all fractures originated at the adhesive-enamel interface and that the induced crack propagated preferentially along this interface. mini-iFT appeared a valid alternative method to assess the mechanical properties of adhesive-enamel interfaces. Copyright © 2016 Elsevier Ltd. All rights reserved.

Physical and biological properties of a novel anti-adhesion material made of thermally cross-linked gelatin film: Investigation of the usefulness as anti-adhesion material.

PubMed

Horii, Tsunehito; Tsujimoto, Hiroyuki; Miyamoto, Hiroe; Yamanaka, Koki; Tanaka, Shota; Torii, Hiroko; Ozamoto, Yuki; Takamori, Hideki; Nakamachi, Eiji; Ikada, Yoshito; Hagiwara, Akeo

2018-02-01

To create more useful, effective and safer anti-adhesion materials, we developed a thermally cross-linked gelatin film. In this study, we examined the physical properties of the film such as the physical strength and the adhesiveness to reveal the handling properties and biological properties, such as the anti-adhesion effect, the influence on cell proliferation, and the cytotoxicity to reveal the anti-adhesion mechanism, especially in comparison with the conventional hyaluronic acid and carboxymethylcellulose film (the conventional film). A tensile test under dry and wet conditions and shearing stress test showed that the gelatin film has significant higher maximum tensile stress and fracture strain than the conventional film. In the study using a rat model of cecum adhesion, the anti-adhesion effect of the gelatin film was significantly superior to that of the conventional film. In the cell proliferation test, the number of fibroblast cells on the gelatin film increased at each time point, while no cell proliferation was observed on the conventional film. Furthermore, in the cytotoxicity test using a colony assay and Live/Dead assay, the extract of the gelatin film had no cytotoxicity, while the extract of the conventional film had cytotoxicity considerably. These results suggest that the gelatin film provides better handling than the conventional film, due to better physical strength and ductility of the film. In addition, the gelatin film has a significantly greater anti-adhesion effect than the conventional film without any cytotoxicity. Therefore, the gelatin film is quite favorable as an anti-adhesion material. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 689-696, 2018. © 2017 Wiley Periodicals, Inc.

In vitro evaluation of casein phosphopeptide-amorphous calcium phosphate effect on the shear bond strength of dental adhesives to enamel.

PubMed

Shadman, Niloofar; Ebrahimi, Shahram Farzin; Shoul, Maryam Azizi; Sattari, Hasti

2015-01-01

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is applied for remineralization of early caries lesions or tooth sensitivity conditions and may affect subsequent resin bonding. This in vitro study investigated the effect of CPP-ACP on the shear bond strength of dental adhesives to enamel. Sixty extracted human molar teeth were selected and randomly divided into three groups and six subgroups. Buccal or lingual surfaces of teeth were prepared to create a flat enamel surface. Adhesives used were Tetric N-Bond, AdheSE and AdheSE One F. In three subgroups, before applying adhesives, enamel surfaces were treated with Tooth Mousse CPP-ACP for one hour, rinsed and stored in 37°C temperature with 100% humidity. This procedure was repeated for 5 days and then adhesives were applied and Tetric N-Ceram composite was adhered to the enamel. This procedure was also fulfilled for the other three subgroups without CPP-ACP treatment. After 24 hour water storage, samples were tested for shear bond strength test in a universal testing machine. Failure modes were determined by stereomicroscope. Data were analyzed by t-test and one-way analysis of variance with P < 0.05 as the level of significance. In comparison between applied and non-applied CPP-ACP subgroups, there was no significant decrease in the shear bond strength to enamel only in Tetric N-Bond (P > 0.05). In non-applied CPP-ACP subgroups, there were statistically significant differences among all subgroups. Tetric N-Bond had the highest and AdheSE One F had the lowest shear bond strength. CPP-ACP application reduces the shear bond strength of AdheSE and AdheSE One F to enamel but not Tetric N-Bond.

In vitro evaluation of casein phosphopeptide-amorphous calcium phosphate effect on the shear bond strength of dental adhesives to enamel

PubMed Central

Shadman, Niloofar; Ebrahimi, Shahram Farzin; Shoul, Maryam Azizi; Sattari, Hasti

2015-01-01

Background: Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is applied for remineralization of early caries lesions or tooth sensitivity conditions and may affect subsequent resin bonding. This in vitro study investigated the effect of CPP-ACP on the shear bond strength of dental adhesives to enamel. Materials and Methods: Sixty extracted human molar teeth were selected and randomly divided into three groups and six subgroups. Buccal or lingual surfaces of teeth were prepared to create a flat enamel surface. Adhesives used were Tetric N-Bond, AdheSE and AdheSE One F. In three subgroups, before applying adhesives, enamel surfaces were treated with Tooth Mousse CPP-ACP for one hour, rinsed and stored in 37°C temperature with 100% humidity. This procedure was repeated for 5 days and then adhesives were applied and Tetric N-Ceram composite was adhered to the enamel. This procedure was also fulfilled for the other three subgroups without CPP-ACP treatment. After 24 hour water storage, samples were tested for shear bond strength test in a universal testing machine. Failure modes were determined by stereomicroscope. Data were analyzed by t-test and one-way analysis of variance with P < 0.05 as the level of significance. Results: In comparison between applied and non-applied CPP-ACP subgroups, there was no significant decrease in the shear bond strength to enamel only in Tetric N-Bond (P > 0.05). In non-applied CPP-ACP subgroups, there were statistically significant differences among all subgroups. Tetric N-Bond had the highest and AdheSE One F had the lowest shear bond strength. Conclusion: CPP-ACP application reduces the shear bond strength of AdheSE and AdheSE One F to enamel but not Tetric N-Bond. PMID:25878683

Design, Simulation and Fabrication of Triaxial MEMS High Shock Accelerometer.

PubMed

Zhang, Zhenhai; Shi, Zhiguo; Yang, Zhan; Xie, Zhihong; Zhang, Donghong; Cai, De; Li, Kejie; Shen, Yajing

2015-04-01

On the basis of analyzing the disadvantage of other structural accelerometer, three-axis high g MEMS piezoresistive accelerometer was put forward in order to apply to the high-shock test field. The accelerometer's structure and working principle were discussed in details. The simulation results show that three-axis high shock MEMS accelerometer can bear high shock. After bearing high shock impact in high-shock shooting test, three-axis high shock MEMS accelerometer can obtain the intact metrical information of the penetration process and still guarantee the accurate precision of measurement in high shock load range, so we can not only analyze the law of stress wave spreading and the penetration rule of the penetration process of the body of the missile, but also furnish the testing technology of the burst point controlling. The accelerometer has far-ranging application in recording the typical data that projectile penetrating hard target and furnish both technology guarantees for penetration rule and defend engineering.

Effects of solvent evaporation time on immediate adhesive properties of universal adhesives to dentin.

PubMed

Luque-Martinez, Issis V; Perdigão, Jorge; Muñoz, Miguel A; Sezinando, Ana; Reis, Alessandra; Loguercio, Alessandro D

2014-10-01

To evaluate the microtensile bond strengths (μTBS) and nanoleakage (NL) of three universal or multi-mode adhesives, applied with increasing solvent evaporation times. One-hundred and forty caries-free extracted third molars were divided into 20 groups for bond strength testing, according to three factors: (1) Adhesive - All-Bond Universal (ABU, Bisco, Inc.), Prime&Bond Elect (PBE, Dentsply), and Scotchbond Universal Adhesive (SBU, 3M ESPE); (2) Bonding strategy - self-etch (SE) or etch-and-rinse (ER); and (3) Adhesive solvent evaporation time - 5s, 15s, and 25s. Two extra groups were prepared with ABU because the respective manufacturer recommends a solvent evaporation time of 10s. After restorations were constructed, specimens were stored in water (37°C/24h). Resin-dentin beams (0.8mm(2)) were tested at 0.5mm/min (μTBS). For NL, forty extracted molars were randomly assigned to each of the 20 groups. Dentin disks were restored, immersed in ammoniacal silver nitrate, sectioned and processed for evaluation under a FESEM in backscattered mode. Data from μTBS were analyzed using two-way ANOVA (adhesive vs. drying time) for each strategy, and Tukey's test (α=0.05). NL data were computed with non-parametric tests (Kruskal-Wallis and Mann-Whitney tests, α=0.05). Increasing solvent evaporation time from 5s to 25s resulted in statistically higher mean μTBS for all adhesives when used in ER mode. Regarding NL, ER resulted in greater NL than SE for each of the evaporation times regardless of the adhesive used. A solvent evaporation time of 25s resulted in the lowest NL for SBU-ER. Residual water and/or solvent may compromise the performance of universal adhesives, which may be improved with extended evaporation times. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Soft material adhesion characterization for in vivo locomotion of robotic capsule endoscopes: Experimental and modeling results.

PubMed

Kern, Madalyn D; Ortega Alcaide, Joan; Rentschler, Mark E

2014-11-01

The objective of this work is to validate an experimental method and nondimensional model for characterizing the normal adhesive response between a polyvinyl chloride based synthetic biological tissue substrate and a flat, cylindrical probe with a smooth polydimethylsiloxane (PDMS) surface. The adhesion response is a critical mobility design parameter of a Robotic Capsule Endoscope (RCE) using PDMS treads to provide mobility to travel through the gastrointestinal tract for diagnostic purposes. Three RCE design characteristics were chosen as input parameters for the normal adhesion testing: pre-load, dwell time and separation rate. These parameters relate to the RCE׳s cross sectional dimension, tread length, and tread speed, respectively. An inscribed central composite design (CCD) prescribed 34 different parameter configurations to be tested. The experimental adhesion response curves were nondimensionalized by the maximum stress and total displacement values for each test configuration and a mean nondimensional curve was defined with a maximum relative error of 5.6%. A mathematical model describing the adhesion behavior as a function of the maximum stress and total displacement was developed and verified. A nonlinear regression analysis was done on the maximum stress and total displacement parameters and equations were defined as a function of the RCE design parameters. The nondimensional adhesion model is able to predict the adhesion curve response of any test configuration with a mean R(2) value of 0.995. Eight additional CCD studies were performed to obtain a qualitative understanding of the impact of tread contact area and synthetic material substrate stiffness on the adhesion response. These results suggest that the nondimensionalization technique for analyzing the adhesion data is sufficient for all values of probe radius and substrate stiffness within the bounds tested. This method can now be used for RCE tread design optimization given a set of environmental conditions for device operation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improved Tensile Adhesion Specimens for High Strength Epoxy Systems in Aerospace Applications

NASA Technical Reports Server (NTRS)

Haddock, M. Reed; McLennan, Michael L.

2000-01-01

An improved tensile adhesion button has been designed and tested that results in higher measured tensile adhesion strength while providing increased capability for testing high strength epoxy adhesive systems. The best attributes of two well-established tensile button designs were combined and refined into an optimized tensile button. The most significant design change to the tensile button was to improve alignment of the bonded tensile button specimens during tensile testing by changing the interface between the tensile button and the tensile test machine. The established or old button design uses a test fixture that pulls from a grooved annulus or anvil head while the new button design pulls from a threaded hole in the centerline of the button. Finite element (FE) analysis showed that asymmetric loading of the established anvil head tensile button significantly increases the stress concentration in the adhesive, causing failure at lower tensile test loads. The new tensile button was designed to eliminate asymmetric loading and eliminate misalignment sensitivity. Enhanced alignment resulted in improved tensile adhesion strength measurement up to 13.8 MPa (2000psi) over the established button design. Another design change increased the capability of the button by increasing the threaded hole diameter allowing it to test high strength epoxy systems up to 85 MPa(less than 12,000 psi). The improved tensile button can be used in button- to-button or button-to-panel configurations.

An Alternative Method Of Specifying Shock Test Criteria

NASA Technical Reports Server (NTRS)

Ferebee, R. C.; Clayton, J.; Alldredge, D.; Irvine, T.

2008-01-01

Shock testing of aerospace vehicle hardware has presented many challenges over the years due to the high magnitude and short duration of the specifications. Recently, component structural failures have occurred during testing that have not manifested themselves on over 200 Space Shuttle solid rocket booster (SRB) flights (two boosters per flight). It is suspected that the method of specifying shock test criteria may be leaving important information out of the test process. The traditional test criteria specification, the shock response spectrum, can be duplicated by any number of waveforms that may not resemble the actual flight test recorded time history. One method of overcoming this limitation is described herein, which may prove useful for qualifying hardware for the upcoming Constellation Program.

Cell-adhesion molecules in memory formation.

PubMed

Schmidt, R

1995-01-23

After learning events the CNS of higher organisms selects, which acquired informations are permanently stored as a memory trace. This period of memory consolidation is susceptible to interference by biochemical inhibitors of transcription and translation. Ependymin is a specific CNS glycoprotein functionally involved in memory consolidation in goldfish: after active shock-avoidance conditioning ependymin mRNA is rapidly induced in meningeal fibroblasts followed by enhanced synthesis and secretion of several closely related forms of the protein. Intracranial injections of anti-ependymin antisera or antisense oligodeoxynucleotides interfere specifically with memory consolidation, indicating that only de novo synthesized ependymin molecules are involved. Ependymin is capable of directing the growth of central axons in vitro and participates in neuronal regeneration in situ, presumably by its HNK-1 cell-adhesion epitope. Experiments reviewed in this article suggest a model that involves two regulation mechanisms for the function of ependymin in behavioural plasticity: while hormones appear to determine, how much of this cell adhesion molecule is synthesized after learning, local changes of metal cation concentrations in the micro-environment of activated neurons may polymerize ependymin at those synapses, that have to be consolidated to improve their efficacy for future use.

Effect of wall heat transfer on shock-tube test temperature at long times

NASA Astrophysics Data System (ADS)

Frazier, C.; Lamnaouer, M.; Divo, E.; Kassab, A.; Petersen, E.

2011-02-01

When performing chemical kinetics experiments behind reflected shock waves at conditions of lower temperature (<1,000 K), longer test times on the order of 10-20 ms may be required. The integrity of the test temperature during such experiments may be in question, because heat loss to the tube walls may play a larger role than is generally seen in shock-tube kinetics experiments that are over within a millisecond or two. A series of detailed calculations was performed to estimate the effect of longer test times on the temperature uniformity of the post-shock test gas. Assuming the main mode of heat transfer is conduction between the high-temperature gas and the colder shock-tube walls, a comprehensive set of calculations covering a range of conditions including test temperatures between 800 and 1,800 K, pressures between 1 and 50 atm, driven-tube inner diameters between 3 and 16.2 cm, and test gases of N2 and Ar was performed. Based on the results, heat loss to the tube walls does not significantly reduce the area-averaged temperature behind the reflected shock wave for test conditions that are likely to be used in shock-tube studies for test times up to 20 ms (and higher), provided the shock-tube inner diameter is sufficiently large (>8cm). Smaller diameters on the order of 3 cm or less can experience significant temperature loss near the reflected-shock region. Although the area-averaged gas temperature decreases due to the heat loss, the main core region remains spatially uniform so that the zone of temperature change is limited to only the thermal layer adjacent to the walls. Although the heat conduction model assumes the gas and wall to behave as solid bodies, resulting in a core gas temperature that remains constant at the initial temperature, a two-zone gas model that accounts for density loss from the core to the colder thermal layer indicates that the core temperature and gas pressure both decrease slightly with time. A full CFD solution of the shock-tube flow field and heat transfer at long test times was also performed for one typical condition (800 K, 1 atm, Ar), the results of which indicate that the simpler analytical conduction model is realistic but somewhat conservative in that it over predicts the mean temperature loss by a few Kelvins. This paper presents the first comprehensive study on the effects of long test times on the average test gas temperature behind the reflected shock wave for conditions representative of chemical kinetics experiments.

Enamel Wetness Effects on Microshear Bond Strength of Different Bonding Agents (Adhesive Systems): An in vitro Comparative Evaluation Study.

PubMed

Kulkarni, Girish; Mishra, Vinay K

2016-05-01

The purpose of this study was to compare the effect of enamel wetness on microshear bond strength using different adhesive systems. To evaluate microshear bond strength of three bonding agents on dry enamel; to evaluate microshear bond strength of three bonding agents on wet enamel; and to compare microshear bond strength of three different bonding agents on dry and wet enamel. Sixty extracted noncarious human premolars were selected for this study. Flat enamel surfaces of approximately 3 mm were obtained by grinding the buccal surfaces of premolars with water-cooled diamond disks. This study evaluated one etch-and-rinse adhesive system (Single Bond 2) and two self-etching adhesive systems (Clearfil SE Bond and Xeno-V). The specimens were divided into two groups (n = 30). Group I (dry) was air-dried for 30 seconds and in group II (wet) surfaces were blotted with absorbent paper to remove excess water. These groups were further divided into six subgroups (n = 10) according to the adhesives used. The resin composite, Filtek Z 250, was bonded to flat enamel surfaces that had been treated with one of the adhesives, following the manufacturer's instructions. After being stored in water at 37°C for 24 hours, bonded specimens were stressed in universal testing machine (Fig. 3) at a crosshead speed of 1 mm/min. The data were evaluated with one-way and two-way analysis of variance (ANOVA), t-test, and Tukey's Multiple Post hoc tests (a = 0.05). The two-way ANOVA and Tukey's Multiple Post hoc tests showed significant differences among adhesive systems, but wetness did not influence microshear bond strength (p = 0.1762). The one-way ANOVA and t-test showed that the all-in-one adhesive (Xeno-V) was the only material influenced by the presence of water on the enamel surface. Xeno-V showed significantly higher microshear bond strength when the enamel was kept wet. Single Bond 2 adhesive showed significantly higher microshear bond strength as compared with Xeno-V adhesive but no significant difference when compared with Clearfil SE Bond adhesive in dry enamel. Single Bond 2 adhesive showed no significant difference in microshear bond strength as compared with self-etching adhesive systems (Clearfil SE Bond and Xeno-V), when the enamel was kept wet. From the findings of the results, it was concluded that self-etching adhesives were not negatively affected by the presence of water on the enamel surface. The all-in-one adhesive showed different behavior depending on whether the enamel surface was dry or wet. So the enamel surface should not be desiccated, when self-etching adhesives are used.

A program for calculating expansion-tube flow quantities for real-gas mixtures and comparison with experimental results

NASA Technical Reports Server (NTRS)

Miller, C. G., III

1972-01-01

A computer program written in FORTRAN 4 language is presented which determines expansion-tube flow quantities for real test gases CO2 N2, O2, Ar, He, and H2, or mixtures of these gases, in thermochemical equilibrium. The effects of dissociation and first and second ionization are included. Flow quantities behind the incident shock into the quiescent test gas are determined from the pressure and temperature of the quiescent test gas in conjunction with: (1) incident-shock velocity, (2) static pressure immediately behind the incident shock, or (3) pressure and temperature of the driver gas (imperfect hydrogen or helium). The effect of the possible existence of a shock reflection at the secondary diaphragm of the expansion tube is included. Expansion-tube test-section flow conditions are obtained by performing an isentropic unsteady expansion from the conditions behind the incident shock or reflected shock to either the test-region velocity or the static pressure. Both a thermochemical-equilibrium expansion and a frozen expansion are included. Flow conditions immediately behind the bow shock of a model positioned at the test section are also determined. Results from the program are compared with preliminary experimental data obtained in the Langley 6-inch expansion tube.

Shock Layer Radiation Measurements and Analysis for Mars Entry

NASA Technical Reports Server (NTRS)

Bose, Deepak; Grinstead, Jay Henderson; Bogdanoff, David W.; Wright, Michael J.

2009-01-01

NASA's In-Space Propulsion program is supporting the development of shock radiation transport models for aerocapture missions to Mars. A comprehensive test series in the NASA Antes Electric Arc Shock Tube facility at a representative flight condition was recently completed. The facility optical instrumentation enabled spectral measurements of shocked gas radiation from the vacuum ultraviolet to the near infrared. The instrumentation captured the nonequilibrium post-shock excitation and relaxation dynamics of dispersed spectral features. A description of the shock tube facility, optical instrumentation, and examples of the test data are presented. Comparisons of measured spectra with model predictions are also made.

The Shock and Vibration Bulletin. Part 1. Welcome, Invited Papers, Shipboard Shock, Blast and Ground Shock, Shock Testing and Analysis

DTIC Science & Technology

1986-08-01

Shock Testing Mr. John D. Favour, Mr. William J.24 October, P.M. and Anslysis Boeing Aerospace Kacene, Company, Martin Marietta Seattle, WA Denver...THE FEASIOILITY STUDY PRESENTED HERE SHOWS REPORT NO. SC-RR- 71 -02811, 7 THAT, THE CONCEPT Or ACTIVE PROTECTION OFFERS MANY ADVANTAGES OVEi, PASSIVE...paper. Mr. Fotieo ( Martin Marietta Orlando): Would this technique be helpful in predicting the pressures icting on the back end of a projectile as it

Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin.

PubMed

Türkmen, Cafer; Durkan, Meral; Cimilli, Hale; Öksüz, Mustafa

2011-08-01

The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM. Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student's t-test. The failure modes of all groups were also evaluated. The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure. The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces.

Synthesis and characterization of novel halloysite-incorporated adhesive resins.

PubMed

Feitosa, Sabrina A; Münchow, Eliseu A; Al-Zain, Afnan O; Kamocki, Krzysztof; Platt, Jeffrey A; Bottino, Marco C

2015-11-01

To investigate the effects of Halloysite® aluminosilicate clay nanotubes (HNTs) addition on selected physical, mechanical, and biological properties of experimental adhesive resins. Experimental dentin adhesive resins were prepared by mixing Bis-GMA, TEGDMA, HEMA (50/25/25wt.%), and photo-initiators. As-received HNTs were then incorporated into the resin mixture at distinct concentrations: 0 (HNT-free, control), 1, 2.5, 5, 7.5, 10, and 20wt.%. The degree of conversion (DC), radiopacity (RP), Knoop hardness (KHN), flexural strength (FS), and cytotoxicity analyses were carried out for each adhesive formulation. The adhesive resin of Adper Scotchbond Multi-Purpose (SBMP) was used as the commercially available reference for both the RP and cytotoxicity tests. Data were statistically analyzed using One-Way ANOVA and Tukey's test (p≤0.05). All adhesives exhibited similar DC (p=0.1931). The RP of adhesives was improved with the addition of up to 5wt.% of HNTs (p<0.001). Adhesives containing 5-10wt.% of HNTs led to greater KHN when compared to the control (p<0.001). The FS was reduced only when 20wt.% of HNTs was added (p≤0.001). None of the prepared adhesives was cytotoxic. The incorporation of up to 10wt.% of HNTs into the adhesive resins did not jeopardize the tested physical and biological properties. When using HNTs as carriers of drugs/bioactive compounds, the amount of the former added into adhesive resin materials should not exceed 10wt.%; otherwise, a significant reduction in physicomechanical properties may be expected. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of ceramic thickness and type on micromechanical properties of light-cured adhesive bonding agents.

PubMed

Öztürk, Elif; Bolay, Sükran; Hickel, Reinhard; Ilie, Nicoleta

2014-10-01

The aim of this study was to evaluate the micromechanical properties of different adhesive bonding agents when polymerized through ceramics. Sixty sound extracted human third molars were selected and the crowns were sectioned perpendicular to the long axis in order to obtain dentin slices to be bonded with one of the following adhesives: Syntac/Heliobond (Ivoclar-Vivadent) or Adper-Scotchbond-1XT (3M-ESPE). The adhesives were cured by using a LED-unit (Bluephase®, Ivoclar Vivadent) with three different curing times (10 s, 20 s and 30 s) under two ceramics (IPS-e.max-Press, Ivoclar-Vivadent; IPS-Empress®CAD, Ivoclar-Vivadent) of different thicknesses (0 mm, 0.75 mm, 2 mm). Thirty groups were included, each containing 60 measurements. Micromechanical properties (Hardness, HV; indentation modulus, E; and creep, Cr) of the adhesives were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). Data were statistically analyzed by using one-way ANOVA and Tukey's post-hoc test, as well as a multivariate analysis to test the influence of the study parameters (SPSS 18.0). Significant differences were observed between the micromechanical properties of the adhesives (p < 0.05). The ceramic type showed the highest effect on HV (Partial-eta squared (η(2)) = 0.109) of the tested adhesives, while E (η(2) = 0.275) and Cr (η(2) = 0.194) were stronger influenced by the adhesive type. Ceramic thickness showed no effect on the E and Cr of the adhesives. The adhesive bonding agents used in this study performed well by curing through different thicknesses of ceramics. The micromechanical properties of the adhesives were determined by the adhesive type and were less influenced by ceramic type and curing time.

Bonding of universal adhesives to dentine--Old wine in new bottles?

PubMed

Chen, C; Niu, L-N; Xie, H; Zhang, Z-Y; Zhou, L-Q; Jiao, K; Chen, J-H; Pashley, D H; Tay, F R

2015-05-01

Multi-mode universal adhesives offer clinicians the choice of using the etch-and-rinse technique, selective enamel etch technique or self-etch technique to bond to tooth substrates. The present study examined the short-term in vitro performance of five universal adhesives bonded to human coronal dentine. Two hundred non-carious human third molars were assigned to five groups based on the type of the universal adhesives (Prime&Bond Elect, Scotchbond Universal, All-Bond Universal, Clearfil Universal Bond and Futurabond U). Two bonding modes (etch-and-rinse and self-etch) were employed for each adhesive group. Bonded specimens were stored in deionized water for 24h or underwent a 10,000-cycle thermocycling ageing process prior to testing (N=10). Microtensile bond testing (μTBS), transmission electron microscopy (TEM) of resin-dentine interfaces in non-thermocycled specimens and scanning electron microscopy (SEM) of tracer-infused water-rich zones within hybrid layers of thermocycled specimens were performed. Both adhesive type and testing condition (with/without thermocycling) have significant influences on μTBS. The use of each adhesive in either the etch-and-rinse or self-etch application mode did not result in significantly different μTBS to dentine. Hybrid layers created by these adhesives in the etch-and-rinse bonding mode and self-etch bonding mode were ∼5μm and ≤0.5μm thick respectively. Tracer-infused regions could be identified within the resin-dentine interface from all the specimens prepared. The increase in versatility of universal adhesives is not accompanied by technological advances for overcoming the challenges associated with previous generations of adhesives. Therapeutic adhesives with bio-protective and bio-promoting effects are still lacking in commercialized adhesives. Universal adhesives represent manufacturers' attempt to introduce versatility in product design via adaptation of a single-bottle self-etch adhesive for other application modes without compromising its bonding effectiveness. Published by Elsevier Ltd.

pH and effects on Streptococcus mutans growth of denture adhesives: an in vitro study.

PubMed

Chen, Fengying; Mao, Tiantian; Cheng, Xiangrong

2014-06-01

To evaluate the pH and effects on Streptococcus mutans growth of denture adhesives. There is little information regarding the pH of contemporary adhesives and their influences on S. mutans growth. The adhesives tested were Polident® cream, Protefix® cream and Protefix® powder. Samples of each adhesive were added to deionized water to produce solutions of 10.0, 5.0, 2.5 and 1.0% w/v (cream formulations) or 5.0, 2.5,1.0 and 0.5% (powder formulation). The pH values were measured immediately after preparation and at 1-, 2-, 3-, 6-, 12-, and 24-h intervals using a digital pH meter. Streptococcus mutans UA159 was inoculated in the Brain Heart Infusion medium with or without the adhesive extracts (control). Bacterial growth was observed by measuring absorption at 600 nm every 1 h for 12 h using a spectrophotometer. The tested adhesives generally remained relatively pH-stable over 24 h, ranging from 5.5 to 7.0. There were no statistically significant differences in S. mutans growth rates between the extract-treated and control cultures (p>0.5). Some adhesives produce a pH below the critical pH of hydroxyapatite and may not be suitable for patients with natural teeth. None of the tested adhesives significantly affect S. mutans growth. © 2012 The Gerodontology Society and John Wiley & Sons A/S.

Investigations on the viscoelastic performance of pressure sensitive adhesives in drug-in-adhesive type transdermal films.

PubMed

Wolff, Hans-Michael; Irsan; Dodou, Kalliopi

2014-08-01

We aimed to investigate the effect of solubility parameter and drug concentration on the rheological behaviour of drug-in-adhesive films intended for transdermal application. Films were prepared over a range of drug concentrations (5%, 10% and 20% w/w) using ibuprofen, benzoic acid, nicotinic acid and lidocaine as model drugs in acrylic (Duro-Tak 87-4287 and Duro-Tak 87900A) or silicone (Bio-PSA 7-4301 and Bio-PSA 7-4302) pressure sensitive adhesives (PSAs). Saturation status of films was determined using light microscopy. Viscoelastic parameters were measured in rheology tests at 32°C. Subsaturated films had lower viscoelastic moduli whereas saturated films had higher moduli than the placebo films and/or a concentration-dependent increase in their modulus. Saturation concentration of each drug in the films was reflected by decreasing/increasing viscoelastic patterns. The viscoelastic windows (VWs) of the adhesive and drug-in-adhesive films clearly depicted the effect of solubility parameter differences, molar concentration of drug in the adhesive film and differences in PSA chemistry. Drug solubility parameters and molar drug concentrations have an impact on rheological patterns and thus on the adhesive performance of tested pressure sensitive adhesives intended for use in transdermal drug delivery systems. Use of the Flory equation in its limiting form was appropriate to predict drug solubility in the tested formulations.

Effects of heat shock, stannous chloride, and gallium nitrate on the rat inflammatory response.

PubMed

House, S D; Guidon, P T; Perdrizet, G A; Rewinski, M; Kyriakos, R; Bockman, R S; Mistry, T; Gallagher, R A; Hightower, L E

2001-04-01

Heat and a variety of other stressors cause mammalian cells and tissues to acquire cytoprotection. This transient state of altered cellular physiology is nonproliferative and antiapoptotic. In this study, male Wistar rats were stress conditioned with either stannous chloride or gallium nitrate, which have immunosuppressive effects in vivo and in vitro, or heat shock, the most intensively studied inducer of cytoprotection. The early stages of inflammation in response to topical suffusion of mesentery tissue with formyl-methionyl-leucyl-phenylalanine (FMLP) were monitored using intravital microscopy. Microvascular hemodynamics (venular diameter, red blood cell velocity [Vrbc], white blood cell [WBC] flux, and leukocyte-endothelial adhesion [LEA]) were used as indicators of inflammation, and tissue levels of inducible Hsp70, determined using immunoblot assays, provided a marker of cytoprotection. None of the experimental treatments blocked decreases in WBC flux during FMLP suffusion, an indicator of increased low-affinity interactions between leukocytes and vascular endothelium known as rolling adhesion. During FMLP suffusion LEA, an indicator of firm attachment between leukocytes and vascular endothelial cells increased in placebo and gallium nitrate-treated animals but not in heat- and stannous chloride-treated animals, an anti-inflammatory effect. Hsp70 was not detected in aortic tissue from placebo and gallium nitrate-treated animals, indicating that Hsp70-dependent cytoprotection was not present. In contrast, Hsp70 was detected in aortic tissues from heat- and stannous chloride-treated animals, indicating that these tissues were in a cytoprotected state that was also an anti-inflammatory state.

Effects of heat shock, stannous chloride, and gallium nitrate on the rat inflammatory response

PubMed Central

House, S.D.; Guidon, P.T.; Perdrizet, G.A.; Rewinski, M.; Kyriakos, R.; Bockman, R.S.; Mistry, T.; Gallagher, P.A.; Hightower, L.E.

2001-01-01

Heat and a variety of other stressors cause mammalian cells and tissues to acquire cytoprotection. This transient state of altered cellular physiology is nonproliferative and antiapoptotic. In this study, male Wistar rats were stress conditioned with either stannous chloride or gallium nitrate, which have immunosuppressive effects in vivo and in vitro, or heat shock, the most intensively studied inducer of cytoprotection. The early stages of inflammation in response to topical suffusion of mesentery tissue with formyl-methionyl-leucyl-phenylalanine (FMLP) were monitored using intravital microscopy. Microvascular hemodynamics (venular diameter, red blood cell velocity [Vrbc], white blood cell [WBC] flux, and leukocyte-endothelial adhesion [LEA]) were used as indicators of inflammation, and tissue levels of inducible Hsp70, determined using immunoblot assays, provided a marker of cytoprotection. None of the experimental treatments blocked decreases in WBC flux during FMLP suffusion, an indicator of increased low-affinity interactions between leukocytes and vascular endothelium known as rolling adhesion. During FMLP suffusion LEA, an indicator of firm attachment between leukocytes and vascular endothelial cells increased in placebo and gallium nitrate-treated animals but not in heat- and stannous chloride–treated animals, an anti-inflammatory effect. Hsp70 was not detected in aortic tissue from placebo and gallium nitrate–treated animals, indicating that Hsp70-dependent cytoprotection was not present. In contrast, Hsp70 was detected in aortic tissues from heat- and stannous chloride–treated animals, indicating that these tissues were in a cytoprotected state that was also an anti-inflammatory state. PMID:11599578

HSP27 Inhibits Homocysteine-Induced Endothelial Apoptosis by Modulation of ROS Production and Mitochondrial Caspase-Dependent Apoptotic Pathway.

PubMed

Tian, Xin; Zhao, Lei; Song, Xianjing; Yan, Youyou; Liu, Ning; Li, Tianyi; Yan, Bingdi; Liu, Bin

2016-01-01

Objectives. Elevated plasma homocysteine (Hcy) could lead to endothelial dysfunction and is viewed as an independent risk factor for atherosclerosis. Heat shock protein 27 (HSP27), a small heat shock protein, is reported to exert protective effect against atherosclerosis. This study aims to investigate the protective effect of HSP27 against Hcy-induced endothelial cell apoptosis in human umbilical vein endothelial cells (HUVECs) and to determine the underlying mechanisms. Methods. Apoptosis, reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) of normal or HSP27-overexpressing HUVECs in the presence of Hcy were analyzed by flow cytometry. The mRNA and protein expression levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Results. We found that Hcy could induce cell apoptosis with corresponding decrease of nitric oxide (NO) level, increase of endothelin-1 (ET-1), intracellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1), and monocyte chemoattractant protein-1 (MCP-1) levels, elevation of ROS, and dissipation of MMP. In addition, HSP27 could protect the cell against Hcy-induced apoptosis and inhibit the effect of Hcy on HUVECs. Furthermore, HSP27 could increase the ratio of Bcl-2/Bax and inhibit caspase-3 activity. Conclusions. Therefore, we concluded that HSP27 played a protective role against Hcy-induced endothelial apoptosis through modulation of ROS production and the mitochondrial caspase-dependent apoptotic pathway.

Increased leukocyte adhesion to vascular endothelium in preeclampsia is inhibited by antioxidants.

PubMed

Ryu, Seongho; Huppmann, Alison R; Sambangi, Nirmala; Takacs, Peter; Kauma, Scott W

2007-04-01

To test the hypothesis that plasma from women with preeclampsia increases leukocyte adhesion to vascular endothelial cells and that antioxidants inhibit this effect. Plasma from 12 women with severe preeclampsia and 12 with normal pregnancy was tested in an in vitro leukocyte-endothelium adhesion assay in the presence or absence of vitamin E, vitamin C, or N-acetylcysteine. Preeclamptic plasma significantly increased monocyte (U937 cells) and T-cell (Jurkat) adhesion to human umbilical vein (HUVEC) and microvascular endothelial cells, compared with normal pregnant plasma. The antioxidants vitamin E, vitamin C, and N-acetylcysteine significantly inhibited monocyte adhesion to HUVEC in the presence of preeclamptic but not normal pregnant plasma. Increased adhesion in response to preeclamptic plasma was not mediated through a protein kinase C (PKC) mechanism, because the PKC inhibitor bisindolylmaleimide I had no effect on adhesion in the presence of preeclamptic plasma. Severe preeclampsia is associated with increased leukocyte-endothelium adhesion and clinically useful antioxidants can inhibit this effect.

Casein phosphopeptide-amorphous calcium phosphate and shear bond strength of adhesives to primary teeth enamel.

PubMed

Farokh Gisovar, Elham; Hedayati, Nassim; Shadman, Niloofar; Shafiee, Leila

2015-02-01

CPP-ACP (Phosphopeptide-Amorphous Calcium Phosphate) has an important role in caries prevention in pediatric patients. This study was done, because of the great use of CPP-ACP and the need for restoration for teeth treated with CPP-ACP as well as the importance of shear bond strength of adhesives in the success of restorations. This study aimed to evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on shear bond strength of dental adhesives to enamel of primary teeth molars. This in vitro study was conducted on 180 extracted primary molars. They were randomly divided into 6 groups and each group was divided into 2 subgroups (treated with CPP-ACP and untreated). In subgroups with CPP-ACP, enamel was treated with CPP-ACP paste 1 h/d for 5 days. Types of adhesives that were evaluated in this study were Tetric N-Bond, AdheSE, AdheSE One F, single Bond 2, SE Bond, and Adper Prompt L-Pop. Shear bond strength was tested with a universal testing machine and mode of failure was evaluated under stereomicroscope. Data were analyzed by T test, 2-way analysis of variance (ANOVA), Tukey and Fisher exact test using SPSS18. P < 0.05 was considered as significance level. Shear bond strengths of different adhesive systems to enamel of primary teeth treated and untreated with CPP-ACP showed no significant difference (P > 0.05). Mode of failure in all groups regardless of CPP-ACP administration was mainly adhesive type. Our results indicated that CPP-ACP did not affect shear bond strength of studied adhesives to primary teeth enamel. To have a successful and durable composite restoration, having a high strength bonding is essential. Considering the wide use of CPP-ACP in preventing tooth decay and the role of adhesive shear bond strength (SBS) in success of composite restoration, we conducted the present study to evaluate the effect of CPP-ACP on the SBS of adhesives to primary teeth enamel.

Characterization of mode 1 and mixed-mode failure of adhesive bonds between composite adherends

NASA Technical Reports Server (NTRS)

Mall, S.; Johnson, W. S.

1985-01-01

A combined experimental and analytical investigation of an adhesively bonded composite joint was conducted to characterize both the static and fatigue beyond growth mechanism under mode 1 and mixed-mode 1 and 2 loadings. Two bonded systems were studied: graphite/epoxy adherends bonded with EC 3445 and FM-300 adhesives. For each bonded system, two specimen types were tested: a double-cantilever-beam specimen for mode 1 loading and a cracked-lapshear specimen for mixed-mode 1 and 2 loading. In all specimens tested, failure occurred in the form of debond growth. Debonding always occurred in a cohesive manner with EC 3445 adhesive. The FM-300 adhesive debonded in a cohesive manner under mixed-mode 1 and 2 loading, but in a cohesive, adhesive, or combined cohesive and adhesive manner under mode 1 loading. Total strain-energy release rate appeared to be the driving parameter for debond growth under static and fatigue loadings.

Tests to Determine the Adhesive Power of Passenger-Car Tires

NASA Technical Reports Server (NTRS)

Foerster, B.

1956-01-01

The concept of the adhesive power of a tire with respect to the road involves several properties which result from the purpose of the tire; namely, connecting link between vehicle and road: (1) The tire must transfer the tractive and braking forces acting in the direction of travel (tractive and braking adhesion); (2) The tire is to prevent lateral deviations of the vehicle from the desired direction of travel (track adhesion). Moreover, the rubber tire provides part of the springing of the vehicle. Above all, it has to level out the minor road irregularities; thus it smoothes, as it were, the road and simultaneously reduces the noise of driving. The springing properties of the tire affect the adhesive power. The tests described below comprise a determination of the braking and track adhesion of individual tires. The adhesion of driven wheels has not been investigated so far.

Shear bond strength of metallic and ceramic brackets using color change adhesives.

PubMed

Stumpf, Aisha de Souza Gomes; Bergmann, Carlos; Prietsch, José Renato; Vicenzi, Juliane

2013-01-01

To determine the shear bond strength of orthodontic brackets using color change adhesives that are supposed to aid in removing excess of bonding material and compare them to a traditional adhesive. Ninety metallic and ninety ceramic brackets were bonded to bovine incisors using two color change adhesives and a regular one. A tensile stress was applied by a universal testing machine. The teeth were observed in a microscope after debonding in order to determine the Adhesive Remnant Index (ARI). The statistical analysis (ANOVA, Tukey, and Kruskall-Wallis tests) demonstrated that the mean bond strength presented no difference when metallic and ceramic brackets were compared, but the bond resistance values were significantly different for the three adhesives used. The most common ARI outcome was the entire adhesive remaining on the enamel. The bond strength was similar for metallic and ceramic brackets when the same adhesive system was used. ARI scores demonstrated that bonding with these adhesives is safe even when ceramic brackets were used. On the other hand, bond strength was too low for orthodontic purposes when Ortho Lite Cure was used.

Biomechanical comparison of the strength of adhesion of polymethylmethacrylate cement to zirconia ceramic and cobalt-chromium alloy components in a total knee arthroplasty.

PubMed

Kumahashi, Nobuyuki; Uchio, Yuji; Kitamura, Nobuto; Satake, Shigeru; Iwamoto, Mikio; Yasuda, Kazunori

2014-11-01

The purpose of this study was to clarify the biomechanical characteristics of cement-material interfaces for the zirconia ceramic and cobalt-chromium (Co-Cr) alloy femoral components used for total knee arthroplasty. In the first sub-study, we compared the strength of adhesion of the cement to flat plates, by tensile testing under dry and moistened conditions. In the second sub-study, we compared the maximum load of the cement-component complex by tensile testing. In the third sub-study, we compared the fatigue characteristics of the cement-component complex by use of a dynamic tensile testing machine. Under dry conditions, the maximum strength of adhesion to the zirconia ceramic plate was the same as that to the Co-Cr alloy plate. Under moistened conditions, however, the strength of adhesion to the zirconia ceramic plate was significantly lower (p = 0.0017) whereas the strength of adhesion to the Co-Cr alloy plate was not reduced. Maximum load for the cement-component complexes for zirconia ceramic and Co-Cr alloy was no different under both dry and moistened conditions. Fatigue testing showed that cement-zirconia adhesion was stronger than cement-Co-Cr alloy adhesion (p = 0.0161). The strength of adhesion of cement to zirconia ceramic is substantially weaker under wet conditions than under dry conditions. The mechanical properties of cement-zirconia ceramic component complexes and cement-Co-Cr alloy component complexes are equivalent.

Characterization of flexible ECoG electrode arrays for chronic recording in awake rats

PubMed Central

Yeager, John D.; Phillips, Derrick J.; Rector, David M.; Bahr, David F.

2008-01-01

We developed a 64 channel flexible polyimide ECoG electrode array and characterized its performance for long term implantation, chronic cortical recording and high resolution mapping of surface evoked potentials in awake rats. To achieve the longest possible recording periods, the flexibility of the electrode array, adhesion between the metals and carrier substrate, and biocompatibility was critical for maintaining the signal integrity. Experimental testing of thin film adhesion was applied to a gold – polyimide system in order to characterize relative interfacial fracture energies for several different adhesion layers, yielding an increase in overall device reliability. We tested several different adhesion techniques including: gold alone without an adhesion layer, titanium-tungsten, tantalum and chromium. We found the titanium-tungsten to be a suitable adhesion layer considering the biocompatibility requirements as well as stability and delamination resistance. While chromium and tantalum produced stronger gold adhesion, concerns over biocompatibility of these materials require further testing. We implanted the polyimide ECoG electrode arrays through a slit made in the skull of rats and recorded cortical surface evoked responses. The arrays performed reliably over a period of at least 100 days and signals compared well with traditional screw electrodes, with better high frequency response characteristics. Since the ultimate goal of chronically implanted electrode arrays is for neural prosthetic devices that need to last many decades, other adhesion layers that would prove safe for implantation may be tested in the same way in order to improve the device reliability. PMID:18640155

Comparison of the antibacterial activity of different self-etching primers and adhesives.

PubMed

Korkmaz, Yonca; Ozalp, Meral; Attar, Nuray

2008-11-01

The aim of this study was to evaluate the antibacterial effects of different one-step and two-step self-etching primer/adhesives on Streptococcus mutans (S. mutans), Lactobacillus casei (L. casei), and Lactobacillus acidophilus (L. acidophilus). The antibacterial effects of Clearfil Protect Bond Primer and Bonding agent; AdheSE Primer and Bonding agent; Adper Prompt L-Pop; Futurabond NR; Clearfil Tri S Bond; and Cervitec (positive control, 1% chlorhexidine varnish) were tested against standard strains of S. mutans, L. Casei, and L. acidophilus using the disk diffusion method. Standard filter paper disks (n=5) impregnated with 20 microL of each material were prepared. After incubation at 37 masculineC for 48 hours in a 5-10% CO2 atmosphere, the diameter of inhibition zones were measured in millimeters. Data were analyzed using one way analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA). Duncan's Multiple Range Test was used for pairwise comparison. The size of inhibition zones produced by primer/adhesives varied among the brands. AdheSE Primer: S. mutans (20.6+/-1.51); L. casei (14.8+/-1.78); L. acidophilus (11.4+/-0.54). Adper Prompt L-Pop: S. mutans (19.6+/-1.51); L. casei (13.8+/-1.64); L. acidophilus (13.8+/-1.09). Cervitec: S. mutans (23+/-0.00); L. casei (27+/-0.70); L. acidophilus (22.4+/-0.54). Clearfil Protect Bond Primer: S. mutans (17+/-0.00); L. casei (17.6+/-0.54); L. acidophilus (22.4+/-0.54). Futurabond NR was found effective only against S. mutans (14.6+/-1.67). Of all the materials tested, AdheSE Bonding agent, Clearfil Protect Bond Bonding agent, and Clearfil Tri S Bond exhibited no inhibition zone (-) for all bacteria tested. Among the adhesives tested Clearafil Protect Bond Primer based upon monomer methacryloyloxydodecylpyridiniium bromide (MDPB) was found to be the most potent material against L. acidophilus and L. casei. AdheSE Primer and Adper Prompt L-Pop are highly effective against S. mutans. Compared with other adhesive systems, Clearfil Protect Bond Primer (containing MDPB) showed a high antibacterial effect against all microorganizms tested. Two-step, self-etching primer/adhesive system Clearfil Protect Bond might be a suitable choice under minimally invasive restorations. The recently developed one-step, self-etching system Clearfil Tri S Bond showed no antibacterial effect against microorgazims tested.

Plume and Shock Interaction Effects on Sonic Boom in the 1-foot by 1-foot Supersonic Wind Tunnel

NASA Technical Reports Server (NTRS)

Castner, Raymond; Elmiligui, Alaa; Cliff, Susan; Winski, Courtney

2015-01-01

The desire to reduce or eliminate the operational restrictions of supersonic aircraft over populated areas has led to extensive research at NASA. Restrictions are due to the disturbance of the sonic boom, caused by the coalescence of shock waves formed by the aircraft. A study has been performed focused on reducing the magnitude of the sonic boom N-wave generated by airplane components with a focus on shock waves caused by the exhaust nozzle plume. Testing was completed in the 1-foot by 1-foot supersonic wind tunnel to study the effects of an exhaust nozzle plume and shock wave interaction. The plume and shock interaction study was developed to collect data for computational fluid dynamics (CFD) validation of a nozzle plume passing through the shock generated from the wing or tail of a supersonic vehicle. The wing or tail was simulated with a wedgeshaped shock generator. This test entry was the first of two phases to collect schlieren images and off-body static pressure profiles. Three wedge configurations were tested consisting of strut-mounted wedges of 2.5- degrees and 5-degrees. Three propulsion configurations were tested simulating the propulsion pod and aft deck from a low boom vehicle concept, which also provided a trailing edge shock and plume interaction. Findings include how the interaction of the jet plume caused a thickening of the shock generated by the wedge (or aft deck) and demonstrate how the shock location moved with increasing nozzle pressure ratio.

A new class of high-G and long-duration shock testing machines

NASA Astrophysics Data System (ADS)

Rastegar, Jahangir

2018-03-01

Currently available methods and systems for testing components for survival and performance under shock loading suffer from several shortcomings for use to simulate high-G acceleration events with relatively long duration. Such events include most munitions firing and target impact, vehicular accidents, drops from relatively high heights, air drops, impact between machine components, and other similar events. In this paper, a new class of shock testing machines are presented that can be used to subject components to be tested to high-G acceleration pulses of prescribed amplitudes and relatively long durations. The machines provide for highly repeatable testing of components. The components are mounted on an open platform for ease of instrumentation and video recording of their dynamic behavior during shock loading tests.

Fracture toughness in Mode I (GIC) for ductile adhesives

NASA Astrophysics Data System (ADS)

Gálvez, P.; Carbas, RJC; Campilho, RDSG; Abenojar, J.; Martínez, MA; Silva LFM, da

2017-05-01

Works carried out in this publication belong to a project that seeks the replacement of welded joints by adhesive joints at stress concentration nodes in bus structures. Fracture toughness in Mode I (GIC) has been measured for two different ductile adhesives, SikaTack Drive and SikaForce 7720. SikaTack Drive is a single-component polyurethane adhesive with high viscoelasticity (more than 100%), whose main use is the car-glass joining and SikaForce 7720 is double-component structural polyurethane adhesive. Experimental works have been carried out from the test called Double Cantilever Beam (DCB), using two steel beams as adherents and an adhesive thickness according to the problem posed in the Project, of 2 and 3 mm for SikaForce 7720 and SikaTack Drive, respectively. Three different methods have been used for measuring the fracture toughness in mode I (GIC) from the values obtained in the experimental DCB procedure for each adhesive: Corrected Beam Theory (CBT), Compliance Calibration Method (CCM) and Compliance Based Beam Method (CBBM). Four DCB specimens have been tested for each adhesive. Dispersion of each GIC calculation method for each adhesive has been studied. Likewise variations between the three different methods have been also studied for each adhesive.

Investigation of shock focusing in a cavity with incident shock diffracted by an obstacle

NASA Astrophysics Data System (ADS)

Zhang, Q.; Chen, X.; He, L.-M.; Rong, K.; Deiterding, R.

2017-03-01

Experiments and numerical simulations were carried out in order to investigate the focusing of a shock wave in a test section after the incident shock has been diffracted by an obstacle. A conventional shock tube was used to generate the planar shock. Incident shock Mach numbers of 1.4 and 2.1 were tested. A high-speed camera was employed to obtain schlieren photos of the flow field in the experiments. In the numerical simulations, a weighted essentially non-oscillatory (WENO) scheme of third-order accuracy supplemented with structured dynamic mesh adaptation was adopted to simulate the shock wave interaction. Good agreement between experiments and numerical results is observed. The configurations exhibit shock reflection phenomena, shock-vortex interaction and—in particular—shock focusing. The pressure history in the cavity apex was recorded and compared with the numerical results. A quantitative analysis of the numerically observed shock reflection configurations is also performed by employing a pseudo-steady shock transition boundary calculation technique. Regular reflection, single Mach reflection and transitional Mach reflection phenomena are observed and are found to correlate well with analytic predictions from shock reflection theory.

Investigation of organic adhesives for hybrid microcircuits

NASA Technical Reports Server (NTRS)

Perkins, K. L.; Licari, J. J.

1975-01-01

The properties of organic adhesives were investigated to acquire information for a guideline document regarding the selection of adhesives for use in high reliability hybrid microcircuits. Specifically, investigations were made of (1) alternate methods for determining the outgassing of cured adhesives, (2) effects of long term aging at 150 C on the electrical properties of conductive adhesives, (3) effects of shelf life age on adhesive characteristics, (4) bond strengths of electrically conductive adhesives on thick film gold metallization, (5) a copper filled adhesive, (6) effects of products outgassed from cured adhesives on device electrical parameters, (7) metal migration from electrically conductive adhesives, and (8) ionic content of electrically insulative adhesives. The tests performed during these investigations are described, and the results obtained are discussed.

Receptors, mediators, and mechanisms involved in bacterial sepsis and septic shock.

PubMed

Van Amersfoort, Edwin S; Van Berkel, Theo J C; Kuiper, Johan

2003-07-01

Bacterial sepsis and septic shock result from the overproduction of inflammatory mediators as a consequence of the interaction of the immune system with bacteria and bacterial wall constituents in the body. Bacterial cell wall constituents such as lipopolysaccharide, peptidoglycans, and lipoteichoic acid are particularly responsible for the deleterious effects of bacteria. These constituents interact in the body with a large number of proteins and receptors, and this interaction determines the eventual inflammatory effect of the compounds. Within the circulation bacterial constituents interact with proteins such as plasma lipoproteins and lipopolysaccharide binding protein. The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents. The role of individual receptors such as the toll-like receptors and CD14 in the induction of proinflammatory cytokines and adhesion molecules is discussed in detail. In addition, the roles of a number of other receptors that bind bacterial compounds such as scavenger receptors and their modulating role in inflammation are described. Finally, the therapies for the treatment of bacterial sepsis and septic shock are discussed in relation to the action of the aforementioned receptors and proteins.

Development of a new test for the easy characterization of the adhesion at the interface of bilayer tablets: proof-of-concept study by experimental design.

PubMed

Busignies, Virginie; Mazel, Vincent; Diarra, Harona; Tchoreloff, Pierre

2014-12-30

Although, adhesion at the interface of bilayer tablets is critical for their design it is difficult to characterize this adhesion between layers. In view of this, a new test with an easy implementation was proposed for the characterization of the interface of bilayer tablets. This work is presented as a proof-of-concept study to investigate the reliability of this new test with regard to the effects of some critical process parameters (e.g., compaction pressure applied on each layer) and material attributes (e.g., elasticity of the layered materials) on the interfacial adhesion of bilayer tablets. This was investigated using a design of experiment approach and the results obtained were in good accordance with those obtained with other tests and thus, confirms the potential of such a method for the measurement of the interfacial adhesion of bilayer tablets. Copyright © 2014 Elsevier B.V. All rights reserved.

Shear Bond Strengths of Different Adhesive Systems to Biodentine

PubMed Central

Odabaş, Mesut Enes; Bani, Mehmet; Tirali, Resmiye Ebru

2013-01-01

The aim of this study was to measure the shear bond strength of different adhesive systems to Biodentine with different time intervals. Eighty specimens of Biodentine were prepared and divided into 8 groups. After 12 minutes, 40 samples were randomly selected and divided into 4 groups of 10 each: group 1: (etch-and-rinse adhesive system) Prime & Bond NT; group 2: (2-step self-etch adhesive system) Clearfil SE Bond; group 3: (1-step self-etch adhesive systems) Clearfil S3 Bond; group 4: control (no adhesive). After the application of adhesive systems, composite resin was applied over Biodentine. This procedure was repeated 24 hours after mixing additional 40 samples, respectively. Shear bond strengths were measured using a universal testing machine, and the data were subjected to 1-way analysis of variance and Scheffé post hoc test. No significant differences were found between all of the adhesive groups at the same time intervals (12 minutes and 24 hours) (P > .05). Among the two time intervals, the lowest value was obtained for group 1 (etch-and-rinse adhesive) at a 12-minute period, and the highest was obtained for group 2 (two-step self-etch adhesive) at a 24-hour period. The placement of composite resin used with self-etch adhesive systems over Biodentine showed better shear bond strength. PMID:24222742

Shear bond strengths of different adhesive systems to biodentine.

PubMed

Odabaş, Mesut Enes; Bani, Mehmet; Tirali, Resmiye Ebru

2013-01-01

The aim of this study was to measure the shear bond strength of different adhesive systems to Biodentine with different time intervals. Eighty specimens of Biodentine were prepared and divided into 8 groups. After 12 minutes, 40 samples were randomly selected and divided into 4 groups of 10 each: group 1: (etch-and-rinse adhesive system) Prime & Bond NT; group 2: (2-step self-etch adhesive system) Clearfil SE Bond; group 3: (1-step self-etch adhesive systems) Clearfil S(3) Bond; group 4: control (no adhesive). After the application of adhesive systems, composite resin was applied over Biodentine. This procedure was repeated 24 hours after mixing additional 40 samples, respectively. Shear bond strengths were measured using a universal testing machine, and the data were subjected to 1-way analysis of variance and Scheffé post hoc test. No significant differences were found between all of the adhesive groups at the same time intervals (12 minutes and 24 hours) (P > .05). Among the two time intervals, the lowest value was obtained for group 1 (etch-and-rinse adhesive) at a 12-minute period, and the highest was obtained for group 2 (two-step self-etch adhesive) at a 24-hour period. The placement of composite resin used with self-etch adhesive systems over Biodentine showed better shear bond strength.

Adhesion enhancement of biomimetic dry adhesives by nanoparticle in situ synthesis

NASA Astrophysics Data System (ADS)

Díaz Téllez, J. P.; Harirchian-Saei, S.; Li, Y.; Menon, C.

2013-10-01

A novel method to increase the adhesion strength of a gecko-inspired dry adhesive is presented. Gold nanoparticles are synthesized on the tips of the microfibrils of a polymeric dry adhesive to increase its Hamaker constant. Formation of the gold nanoparticles is qualitatively studied through a colour change in the originally transparent substance and quantitatively analysed using ultraviolet-visible spectrophotometry. A pull-off force test is employed to quantify the adhesion enhancement. Specifically, adhesion forces of samples with and without embedded gold nanoparticles are measured and compared. The experimental results indicate that an adhesion improvement of 135% can be achieved.

Experimental and computational study of the effect of shocks on film cooling effectiveness in scramjet combustors

NASA Technical Reports Server (NTRS)

Kamath, Pradeep S.; Holden, Michael S.; Mcclinton, Charles R.

1990-01-01

This paper presents results from a study conducted to investigate the effect of incident oblique shocks on the effectiveness of a coolant film at Mach numbers, typical of those expected in a scramjet combustor at Mach 15 to 20 flight. Computations with a parabolic code are in good agreement with the measured pressures and heat fluxes, after accounting for the influence of the shock upstream of its point of impingement on the plate, and the expansion from the trailing edge of the shock generator. The test data shows that, for the blowing rates tested, the film is rendered largely ineffective by the shock. Computations show that coolant blowing rates five to ten times those tested are required to protect against shock-induced heating. The implications of the results to scramjet combustor design are discussed.

Time-resolved spectroscopic measurements behind incident and reflected shock waves in air and xenon

NASA Technical Reports Server (NTRS)

Yoshinaga, T.

1973-01-01

Time-resolved spectra have been obtained behind incident and reflected shock waves in air and xenon at initial pressures of 0.1 and 1.0 torr using a rotating drum spectrograph and the OSU (The Ohio State University) arc-driven shock tube. These spectra were used to determine the qualitative nature of the flow as well as for making estimates of the available test time. The (n+1,n) and (n,n) band spectra of N2(+) (1st negative) were observed in the test gas behind incident shock waves in air at p1=1.0 torr and Us=9-10 km/sec. Behind reflected shock waves in air, the continuum of spectra appeared to cover almost the entire wavelength of 2,500-7,000 A for the shock-heated test gas. For xenon, the spectra for the incident shock wave cases for p1=0.1 torr show an interesting structure in which two intensely bright regions are witnessed in the time direction. The spectra obtained behind reflected shock waves in xenon were also dominated by continuum radiation but included strong absorption spectra due to FeI and FeII from the moment the reflected shock passed and on.

Shock shapes on blunt bodies in hypersonic-hypervelocity helium, air, and CO2 flows, and calibration results in Langley 6-inch expansion tube

NASA Technical Reports Server (NTRS)

Miller, C. G., III

1975-01-01

Shock shape results for flat-faced cylinders, spheres, and spherically blunted cones in various test gases, along with preliminary results from a calibration study performed in the Langley 6-inch expansion tube are presented. Free-stream velocities from 5 to 7 km/sec are generated at hypersonic conditions with helium, air, and CO2, resulting in normal shock density ratios from 4 to 19. Ideal-gas shock shape predictions, in which an effective ratio of specific heats is used as input, are compared with the measured results. The effect of model diameter is examined to provide insight to the thermochemical state of the flow in the shock layer. The regime for which equilibrium exists in the shock layer for the present air and CO2 test conditions is defined. Test core flow quality, test repeatability, and comparison of measured and predicted expansion-tube flow quantities are discussed.

Biofilm formation and virulence factor analysis of Staphylococcus aureus isolates collected from ovine mastitis.

PubMed

Azara, E; Longheu, C; Sanna, G; Tola, S

2017-08-01

To perform a phenotypic and genotypic characterization of 258 Staphylococcus aureus isolates from clinical ovine mastitis and used for the preparation of inactivated autogenous vaccines. The potential for biofilm production was determined by phenotypic test of Congo Red Agar (CRA) and by PCR for the detection of icaA/D genes. Isolates were also screened by PCR for the presence of enterotoxins (sea, seb, sec, sed and see), toxic shock syndrome toxin (tsst), leukotoxins (lukD-E, lukM and lukPV83), haemolysins (hly-β and hly-γ), autolysin (atlA) genes and encoding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs: clfA, clfB, fnbA, fnbB, bbp, cna, eno, fib, epbs, sdrC, sdrD and SdrE). None of the 258 isolates showed biofilm-forming ability on CRA and harboured icaA/D genes. The most frequent pyrogenic toxin superantigen genes amplified were sec plus tsst-1, which were found strictly in combination with 71·3% of the Staph. aureus isolates tested. None of the isolates harboured the genes encoding sea and see. Of the 258 isolates tested, 159 (61·6%) possessed all lukD-E/lukM/lukPV83 genes, 123 (47·7%) harboured both hly-β/hly-γ genes, whereas almost all (97·3%) were PCR positive for atlA gene. With respect to adhesion determinants, 179 (69·4%) isolates presented simultaneously four genes (fnbA, fib, clfA and clfB) for fibronectin- and fibrinogen-binding proteins. In this search, several putative virulence determinants have been identified in ovine Staph. aureus isolates collected in Sardinia. Some of the putative virulence determinants could be considered as components of a vaccine because of their role in ovine mastitis pathogenesis. © 2017 The Society for Applied Microbiology.

Effect of ozone gas on the shear bond strength to enamel

PubMed Central

PIRES, Patrícia Teixeira; FERREIRA, João Cardoso; OLIVEIRA, Sofia Arantes; SILVA, Mário Jorge; MELO, Paulo Ribeiro

2013-01-01

Ozone is an important disinfecting agent, however its influence on enamel adhesion has not yet been clarified. Objective: Evaluate the influence of ozone pretreatment on the shear strength of an etch-and-rinse and a self-etch system to enamel and analyze the respective failure modes. Material and Methods: Sixty sound bovine incisors were used. Specimens were randomly assigned to four experimental groups (n=15): Group G1 (Excite® with ozone) and group G3 (AdheSE® with ozone) were prepared with ozone gas from the HealOzone unit (Kavo®) for 20 s prior to adhesion, and groups G2 (Excite®) and G4 (AdheSE®) were used as control. Teeth were bisected and polished to simulate a smear layer just before the application of the adhesive systems. The adhesives were applied according to the manufacturer's instructions to a standardized 3 mm diameter surface, and a composite (Synergy D6, Coltene Whaledent) cylinder with 2 mm increments was build. Specimens were stored in 100% humidity for 24 h at 37º C and then subjected to a thermal cycling regimen of 500 cycles. Shear bond tests were performed with a Watanabe device in a universal testing machine at 5 mm/min. The failure mode was analyzed under scanning electron microscope. Means and standard deviation of shear bond strength (SBS) were calculated and difference between the groups was analyzed using ANOVA, Kolmogorov-Smirnov, Levene and Bonferroni. Chi-squared statistical tests were used to evaluate the failure modes. Results: Mean bond strength values and failure modes were as follows: G1- 26.85±6.18 MPa (33.3% of adhesive cohesive failure); G2 - 27.95±5.58 MPa (53.8% of adhesive failures between enamel and adhesive); G3 - 15.0±3.84 MPa (77.8% of adhesive failures between enamel and adhesive) and G4 - 13.1±3.68 MPa (36.4% of adhesive failures between enamel and adhesive). Conclusions: Shear bond strength values of both adhesives tested on enamel were not influenced by the previous application of ozone gas. PMID:23739859

Effect of ozone gas on the shear bond strength to enamel.

PubMed

Pires, Patrícia Teixeira; Ferreira, João Cardoso; Oliveira, Sofia Arantes; Silva, Mário Jorge; Melo, Paulo Ribeiro

2013-01-01

Ozone is an important disinfecting agent, however its influence on enamel adhesion has not yet been clarified. Evaluate the influence of ozone pretreatment on the shear strength of an etch-and-rinse and a self-etch system to enamel and analyze the respective failure modes. Sixty sound bovine incisors were used. Specimens were randomly assigned to four experimental groups (n=15): Group G1 (Excite® with ozone) and group G3 (AdheSE® with ozone) were prepared with ozone gas from the HealOzone unit (Kavo®) for 20 s prior to adhesion, and groups G2 (Excite®) and G4 (AdheSE®) were used as control. Teeth were bisected and polished to simulate a smear layer just before the application of the adhesive systems. The adhesives were applied according to the manufacturer's instructions to a standardized 3 mm diameter surface, and a composite (Synergy D6, Coltene Whaledent) cylinder with 2 mm increments was build. Specimens were stored in 100% humidity for 24 h at 37°C and then subjected to a thermal cycling regimen of 500 cycles. Shear bond tests were performed with a Watanabe device in a universal testing machine at 5 mm/min. The failure mode was analyzed under scanning electron microscope. Means and standard deviation of shear bond strength (SBS) were calculated and difference between the groups was analyzed using ANOVA, Kolmogorov-Smirnov, Levene and Bonferroni. Chi-squared statistical tests were used to evaluate the failure modes. Mean bond strength values and failure modes were as follows: G1--26.85±6.18 MPa (33.3% of adhesive cohesive failure); G2--27.95±5.58 MPa (53.8% of adhesive failures between enamel and adhesive); G3--15.0±3.84 MPa (77.8% of adhesive failures between enamel and adhesive) and G4--13.1±3.68 MPa (36.4% of adhesive failures between enamel and adhesive). Shear bond strength values of both adhesives tested on enamel were not influenced by the previous application of ozone gas.

Effect of surface treatments on the flexural properties and adhesion of glass fiber-reinforced composite post to self-adhesive luting agent and radicular dentin.

PubMed

Elnaghy, Amr M; Elsaka, Shaymaa E

2016-01-01

This study evaluated the effect of different surface treatments on the flexural properties and adhesion of glass fiber post to self-adhesive luting agent and radicular dentin. Seventy-five single-rooted human teeth were prepared to receive a glass fiber post (Reblida). The posts were divided into five groups according to the surface treatment: Gr C (control; no treatment), Gr S (silanization for 60 s), Gr AP (airborne-particle abrasion), Gr HF (etching with 9 % hydrofluoric acid for 1 min), and Gr M10 (etching with CH2Cl2 for 10 min). Dual-cure self-adhesive luting agent (Rely X Unicem) was applied to each group for testing the adhesion using micropush-out test. Failure types were examined with stereomicroscope and surface morphology of the posts was characterized using a scanning electron microscopy (SEM). Flexural properties of posts were assessed using a three-point bending test. Data were analyzed using ANOVA and Tukey's HSD test. Statistical significance was set at the 0.05 probability level. Groups treated with M10 showed significantly higher bond strength than those obtained with other surface treatments (P < 0.05). In general, improvements in bond strength (MPa) were found in the following order: M10 > C > S > AP > HF. Most failure modes were adhesive type of failures between dentin and luting agent (48.2%). SEM analysis revealed that the fiber post surfaces were modified after surface treatments. The surface treatments did not compromise the flexural properties of fiber posts. Application of M10 to the fiber post surfaces enhanced the adhesion to self-adhesive luting agent and radicular dentin.

Structural and tribometric characterization of biomimetically inspired synthetic "insect adhesives"

PubMed Central

Speidel, Matthias W; Kleemeier, Malte; Hartwig, Andreas; Rischka, Klaus; Ellermann, Angelika; Daniels, Rolf

2017-01-01

Background: Based on previous chemical analyses of insect tarsal adhesives, we prepared 12 heterogeneous synthetic emulsions mimicking the polar/non-polar principle, analysed their microscopical structure and tested their adhesive, frictional, and rheological properties. Results: The prepared emulsions varied in their consistency from solid rubber-like, over soft elastic, to fluid (watery or oily). With droplet sizes >100 nm, all the emulsions belonged to the common type of macroemulsions. The emulsions of the first generation generally showed broader droplet-size ranges compared with the second generation, especially when less defined components such as petrolatum or waxes were present in the lipophilic fraction of the first generation of emulsions. Some of the prepared emulsions showed a yield point and were Bingham fluids. Tribometric adhesion was tested via probe tack tests. Compared with the "second generation" (containing less viscous components), the "first generation" emulsions were much more adhesive (31–93 mN), a finding attributable to their highly viscous components, i.e., wax, petrolatum, gelatin and poly(vinyl alcohol). In the second generation emulsions, we attained much lower adhesivenesses, ranging between 1–18 mN. The adhesive performance was drastically reduced in the emulsions that contained albumin as the protein component or that lacked protein. Tribometric shear tests were performed at moderate normal loads. Our measured friction forces (4–93 mN in the first and 0.1–5.8 mN in the second generation emulsions) were comparatively low. Differences in shear performance were related to the chemical composition and emulsion structure. Conclusion: By varying their chemical composition, synthetic heterogeneous adhesive emulsions can be adjusted to have diverse consistencies and are able to mimic certain rheological and tribological properties of natural tarsal insect adhesives. PMID:28144564

Effects of drying agents on bond strength of etch-and-rinse adhesive systems to enamel immediately after bleaching.

PubMed

Niat, Alireza Boruzi; Yazdi, Fatmeh Maleknejad; Koohestanian, Niloufar

2012-12-01

To determine the effect of drying agents and adhesive solvents on the bond strength of resin composite to enamel immediately after bleaching. Sixty healthy human premolars were bleached using 15% carbamide peroxide gel and randomly divided into three groups according to the immersing solutions applied immediately after bleaching: 70% alcohol, acetone, and distilled water. Each group was randomly divided into two subgroups according to the adhesives that were applied: an alcohol-based adhesive (Single Bond) and an acetone-based adhesive (One Step). By using rubber washers, composite Z100 was placed onto the enamel and shear bond strength was evaluated in a universal testing machine at a crosshead speed of 1 mm/min. The type of failure was also assessed using a stereomicroscope. The data were statistically analyzed by two-way ANOVA and Tukey's post-hoc test (α = 0.05). Fisher's Exact test was used to evaluate differences in the failure modes. Statistical analysis showed that the bond strength of the distilled water groups was significantly lower than that of the other groups, but the bond strengths of the two groups where a drying agent was applied were similar to that of the unbleached group. The acetone-based adhesive (One Step) provided higher bond strength than did the alcohol-based adhesive (Single Bond) (p < 0.05). There was no interaction between the two variables (p > 0.05). Fisher's Exact test showed there was no significant difference in the failure mode of all the experimental groups (p > 0.05). The application of drying agents improves the bond strength of resin composite to bleached enamel. Furthermore, the acetone-based adhesive used in the study had a higher bond strength to bleached enamel than did the alcohol-based adhesive used.

Does the use of a novel self-adhesive flowable composite reduce nanoleakage?

PubMed

Naga, Abeer Abo El; Yousef, Mohammed; Ramadan, Rasha; Fayez Bahgat, Sherif; Alshawwa, Lana

2015-01-01

The aim of the study reported here was to evaluate the performance of a self-adhesive flowable composite and two self-etching adhesive systems, when subjected to cyclic loading, in preventing the nanoleakage of Class V restorations. Wedge-shape Class V cavities were prepared (4×2×2 mm [length × width × depth]) on the buccal surfaces of 90 sound human premolars. Cavities were divided randomly into three groups (n=30) according to the used adhesive (Xeno(®) V [self-etching adhesive system]) and BOND-1(®) SF (solvent-free self-etching adhesive system) in conjunction with Artiste(®) Nano Composite resin, and Fusio™ Liquid Dentin (self-adhesive flowable composite), consecutively. Each group was further divided into three subgroups (n=10): (A) control, (B) subjected to occlusal cyclic loading (90N for 5,000 cycles), and (C) subjected to occlusal cyclic loading (90N for 10,000 cycles). Teeth then were coated with nail polish up to 1 mm from the interface, immersed in 50% silver nitrate solution for 24 hours and tested for nanoleakage using the environmental scanning electron microscopy and energy dispersive analysis X-ray analysis. Data were statistically analyzed using two-way analysis of variance and Tukey's post hoc tests (P≤0.05). The Fusio Liquid Dentin group showed statistically significant lower percentages of silver penetration (0.55 μ) compared with the BOND-1 SF (3.45 μ) and Xeno V (3.82 μ) groups, which were not statistically different from each other, as they both showed higher silver penetration. Under the test conditions, the self-adhesive flowable composite provided better sealing ability. Aging of the two tested adhesive systems, as a function of cyclic loading, increased nanoleakage.

Does the use of a novel self-adhesive flowable composite reduce nanoleakage?

PubMed Central

Naga, Abeer Abo El; Yousef, Mohammed; Ramadan, Rasha; Fayez Bahgat, Sherif; Alshawwa, Lana

2015-01-01

Objective The aim of the study reported here was to evaluate the performance of a self-adhesive flowable composite and two self-etching adhesive systems, when subjected to cyclic loading, in preventing the nanoleakage of Class V restorations. Methods Wedge-shape Class V cavities were prepared (4×2×2 mm [length × width × depth]) on the buccal surfaces of 90 sound human premolars. Cavities were divided randomly into three groups (n=30) according to the used adhesive (Xeno® V [self-etching adhesive system]) and BOND-1® SF (solvent-free self-etching adhesive system) in conjunction with Artiste® Nano Composite resin, and Fusio™ Liquid Dentin (self-adhesive flowable composite), consecutively. Each group was further divided into three subgroups (n=10): (A) control, (B) subjected to occlusal cyclic loading (90N for 5,000 cycles), and (C) subjected to occlusal cyclic loading (90N for 10,000 cycles). Teeth then were coated with nail polish up to 1 mm from the interface, immersed in 50% silver nitrate solution for 24 hours and tested for nanoleakage using the environmental scanning electron microscopy and energy dispersive analysis X-ray analysis. Data were statistically analyzed using two-way analysis of variance and Tukey’s post hoc tests (P≤0.05). Results The Fusio Liquid Dentin group showed statistically significant lower percentages of silver penetration (0.55 μ) compared with the BOND-1 SF (3.45 μ) and Xeno V (3.82 μ) groups, which were not statistically different from each other, as they both showed higher silver penetration. Conclusion Under the test conditions, the self-adhesive flowable composite provided better sealing ability. Aging of the two tested adhesive systems, as a function of cyclic loading, increased nanoleakage. PMID:25848318

The effects of two soft drinks on bond strength, bracket microleakage, and adhesive remnant on intact and sealed enamel.

PubMed

Navarro, Raúl; Vicente, Ascensión; Ortiz, Antonio J; Bravo, Luis A

2011-02-01

The purpose of this study was to evaluate the effects of Coca-Cola and Schweppes Limón on bond strength, adhesive remnant, and microleakage beneath brackets. One hundred and twenty upper central incisor brackets were bonded to bovine incisors and divided into three groups: (1) Control, (2) Coca-Cola, and (3) Schweppes Limón. The teeth were submerged in the drinks three times a day for 15 minutes over a 15 day period. Shear bond strength (SBS) was measured with a universal testing machine, and adhesive remnant evaluated using image analysis equipment. Microleakage at the enamel-adhesive and adhesive-bracket interfaces was determined using methylene blue. One hundred and eight teeth were used for scanning electron microscopy to determine the effect of the drinks on intact and sealed enamel. SBS and adhesive remnant data were analysed using the Kruskal-Wallis test (P < 0.05) and microleakage using the Kruskal-Wallis and Mann-Whitney tests applying Bonferroni correction (P < 0.017). No significant differences were found in SBS and adhesive remnant between the groups (P > 0.05). Microleakage at the enamel-adhesive interface for groups 2 and 3 was significantly greater than for group 1 (P < 0.017). At the adhesive-bracket interface, microleakage was significantly greater in group 2 than in group 1 (P < 0.017) while microleakage in group 3 did not differ significantly from either group 1 or 2 (P < 0.017). The drinks produced enamel erosion, loss of adhesive and microleakage. Coca-Cola and Schweppes Limón did not affect the SBS of brackets or the adhesive remnant.

Bond durability of universal adhesive to bovine enamel using self-etch mode.

PubMed

Suzuki, Soshi; Takamizawa, Toshiki; Imai, Arisa; Tsujimoto, Akimasa; Sai, Keiichi; Takimoto, Masayuki; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

2018-04-01

The purpose of this study was to examine the enamel bond durability of universal adhesives in the self-etch mode under 2-year water storage and thermal cycling conditions. Three commercially available universal adhesives and a gold standard two-step self-etch adhesive were used. Ten specimens of bovine enamel were prepared per test group, and shear bond strength (SBS) was measured to determine the bonding durability after thermal cycling (TC) or long-term water storage (WS). The bonded specimens were divided into three groups: (1) specimens subjected to TC, where the bonded specimens were stored in 37 °C distilled water for 24 h before being subjected to 3000, 10,000, 20,000 or 30,000 TC; (2) specimens stored in 37 °C distilled water for 3 months, 6 months, 1 year or 2 year; and (3) specimens stored in 37 °C distilled water for 24 h, serving as a baseline. The two-step self-etch adhesive showed significantly higher SBS than the universal adhesives tested, regardless of the type of degradation method. All universal adhesives showed no significant enamel SBS reductions in TC and WS, when compared to baseline and the other degradation conditions. Compared to the bond strengths obtained with the two-step self-etch adhesive, significantly lower bond strengths were obtained with universal adhesives. However, the enamel bond durability of universal adhesives was relatively stable under both degradation conditions tested. The present data indicate that the enamel bond durability of universal adhesives in the self-etch mode might be sufficient for clinical use.

Estimation of adhesive bond strength in laminated safety glass using guided mechanical waves

NASA Astrophysics Data System (ADS)

Huo, Shihong

Laminated safety glass is used in the automobile industry and in architectural applications. Laminated safety glass consists of a plastic interlayer, such as a layer of poly vinyl butyral (PVB) or Butacite, surrounded by two adjacent glass plates. The glass can be float glass, plate glass, tempered glass, or sheet glass, and the plastic interlayer is made of a viscoelastic material with relatively high damping. The level of adhesive bond strength between the plastic interlayer and the two adjacent glass plates has a significant role in the penetration resistance against flying objects and is a critical parameter towards ensuring the proper performance of safety glass. Therefore, estimation and control of adhesive bond levels in laminated safety glass is a critical issue. There are several destructive testing procedures used to quantify the adhesion level in laminated safety glass. These tests include the tension test, the peel test, the impact test, and the pummel test. All these tests have drawbacks including the pummel test method, which has been the most widely used in industry for over 80 years. The primary drawbacks of the pummel test method are that it is destructive and subjective (i.e., involves individual human judgment), which precludes this method for use as an on-line test method for quality control. Consequently, a quantitative nondestructive testing method to evaluate adhesion levels would be an asset to the laminated safety glass industry. In this study, adhesion levels in laminated safety glass samples, i.e., windshields, have been assessed using the guided mechanical wave method. To study the adhesive bond strength analytically, the imperfect interfaces between the plastic interlayer and the two adjacent glass plates in laminated safety glass are modeled using a bed of longitudinal and shear springs, and their stiffness characteristics are estimated using fracture mechanics and atomic force microscopy (AFM) surface measurements. The atomic force microscopy measurements are used to estimate the contact area at the imperfect interfaces between the plastic interlayer and the two adjacent glass plates for each of the laminates. The spring layers are then embedded in the global matrix method, which is used to predict the guided wave dispersion behavior of the laminated system. Based upon the guided wave energy velocity predictions for each of the laminates with different levels of adhesion, the S0 mode was selected as the most promising for use in nondestructively estimating adhesion levels in laminated safety glass. The predicted energy velocities (obtained using this multilayered model) were validated using guided wave energy velocity experimental measurements. The experimentally obtained velocity measurements are in good agreement with the predicted values. Guided wave attenuation in laminated safety glass is primarily due to the viscoelastic material properties of the PVB plastic interlayer. The attenuation properties of S1 mode were also explored to estimate the adhesive bond strength between the plastic interlayer and the two adjacent glass plates. Results show that the combination of both the energy velocity and attenuation methods has promise towards replacing the pummel test method to estimate the adhesion level in laminated safety glass.

Impact of Isothermal Aging and Testing Temperature on Large Flip-Chip BGA Interconnect Mechanical Shock Performance

NASA Astrophysics Data System (ADS)

Lee, Tae-Kyu; Chen, Zhiqiang; Guirguis, Cherif; Akinade, Kola

2017-10-01

The stability of solder interconnects in a mechanical shock environment is crucial for large body size flip-chip ball grid array (FCBGA) electronic packages. Additionally, the junction temperature increases with higher electric power condition, which brings the component into an elevated temperature environment, thus introducing another consideration factor for mechanical stability of interconnection joints. Since most of the shock performance data available were produced at room temperature, the effect of elevated temperature is of interest to ensure the reliability of the device in a mechanical shock environment. To achieve a stable␣interconnect in a dynamic shock environment, the interconnections must tolerate mechanical strain, which is induced by the shock wave input and reaches the particular component interconnect joint. In this study, large body size (52.5 × 52.5 mm2) FCBGA components assembled on 2.4-mm-thick boards were tested with various isothermal pre-conditions and testing conditions. With a heating element embedded in the test board, a test temperature range from room temperature to 100°C was established. The effects of elevated temperature on mechanical shock performance were investigated. Failure and degradation mechanisms are identified and discussed based on the microstructure evolution and grain structure transformations.

Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin

PubMed Central

Poggio, Claudio; Pigozzo, Marco; Ceci, Matteo; Scribante, Andrea; Beltrami, Riccardo; Chiesa, Marco

2016-01-01

Background: The purpose of this study was to evaluate the influence of three different luting protocols on shear bond strength of computer aided design/computer aided manufacturing (CAD/CAM) resin nanoceramic (RNC) material to dentin. Materials and Methods: In this in vitro study, 30 disks were milled from RNC blocks (Lava Ultimate/3M ESPE) with CAD/CAM technology. The disks were subsequently cemented to the exposed dentin of 30 recently extracted bovine permanent mandibular incisors. The specimens were randomly assigned into 3 groups of 10 teeth each. In Group 1, disks were cemented using a total-etch protocol (Scotchbond™ Universal Etchant phosphoric acid + Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 2, disks were cemented using a self-etch protocol (Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 3, disks were cemented using a self-adhesive protocol (RelyX™ Unicem 2 Automix self-adhesive resin cement). All cemented specimens were placed in a universal testing machine (Instron Universal Testing Machine 3343) and submitted to a shear bond strength test to check the strength of adhesion between the two substrates, dentin, and RNC disks. Specimens were stressed at a crosshead speed of 1 mm/min. Data were analyzed with analysis of variance and post-hoc Tukey's test at a level of significance of 0.05. Results: Post-hoc Tukey testing showed that the highest shear strength values (P < 0.001) were reported in Group 2. The lowest data (P < 0.001) were recorded in Group 3. Conclusion: Within the limitations of this in vitro study, conventional resin cements (coupled with etch and rinse or self-etch adhesives) showed better shear strength values compared to self-adhesive resin cements. Furthermore, conventional resin cements used together with a self-etch adhesive reported the highest values of adhesion. PMID:27076822

Adhesive performance of a multi-mode adhesive system: 1-year in vitro study.

PubMed

Marchesi, Giulio; Frassetto, Andrea; Mazzoni, Annalisa; Apolonio, Fabianni; Diolosà, Marina; Cadenaro, Milena; Di Lenarda, Roberto; Pashley, David H; Tay, Franklin; Breschi, Lorenzo

2014-05-01

The aim of this study was to investigate the adhesive stability over time of a multi-mode one-step adhesive applied using different bonding techniques on human coronal dentine. The hypotheses tested were that microtensile bond strength (μTBS), interfacial nanoleakage expression and matrix metalloproteinases (MMPs) activation are not affected by the adhesive application mode (following the use of self-etch technique or with the etch-and-rinse technique on dry or wet dentine) or by ageing for 24h, 6 months and 1year in artificial saliva. Human molars were cut to expose middle/deep dentine and assigned to one of the following bonding systems (N=15): (1) Scotchbond Universal (3M ESPE) self-etch mode, (2) Scotchbond Universal etch-and-rinse technique on wet dentine, (3) Scotchbond Universal etch-and-rinse technique on dry dentine, and (4) Prime&Bond NT (Dentsply De Trey) etch-and-rinse technique on wet dentine (control). Specimens were processed for μTBS test in accordance with the non-trimming technique and stressed to failure after 24h, 6 months or 1 year. Additional specimens were processed and examined to assay interfacial nanoleakage and MMP expression. At baseline, no differences between groups were found. After 1 year of storage, Scotchbond Universal applied in the self-etch mode and Prime&Bond NT showed higher μTBS compared to the other groups. The lowest nanoleakage expression was found for Scotchbond Universal applied in the self-etch mode, both at baseline and after storage. MMPs activation was found after application of each tested adhesive. The results of this study support the use of the self-etch approach for bonding the tested multi-mode adhesive system to dentine due to improved stability over time. Improved bonding effectiveness of the tested universal adhesive system on dentine may be obtained if the adhesive is applied with the self-etch approach. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin.

PubMed

Poggio, Claudio; Pigozzo, Marco; Ceci, Matteo; Scribante, Andrea; Beltrami, Riccardo; Chiesa, Marco

2016-01-01

The purpose of this study was to evaluate the influence of three different luting protocols on shear bond strength of computer aided design/computer aided manufacturing (CAD/CAM) resin nanoceramic (RNC) material to dentin. In this in vitro study, 30 disks were milled from RNC blocks (Lava Ultimate/3M ESPE) with CAD/CAM technology. The disks were subsequently cemented to the exposed dentin of 30 recently extracted bovine permanent mandibular incisors. The specimens were randomly assigned into 3 groups of 10 teeth each. In Group 1, disks were cemented using a total-etch protocol (Scotchbond™ Universal Etchant phosphoric acid + Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 2, disks were cemented using a self-etch protocol (Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 3, disks were cemented using a self-adhesive protocol (RelyX™ Unicem 2 Automix self-adhesive resin cement). All cemented specimens were placed in a universal testing machine (Instron Universal Testing Machine 3343) and submitted to a shear bond strength test to check the strength of adhesion between the two substrates, dentin, and RNC disks. Specimens were stressed at a crosshead speed of 1 mm/min. Data were analyzed with analysis of variance and post-hoc Tukey's test at a level of significance of 0.05. Post-hoc Tukey testing showed that the highest shear strength values (P < 0.001) were reported in Group 2. The lowest data (P < 0.001) were recorded in Group 3. Within the limitations of this in vitro study, conventional resin cements (coupled with etch and rinse or self-etch adhesives) showed better shear strength values compared to self-adhesive resin cements. Furthermore, conventional resin cements used together with a self-etch adhesive reported the highest values of adhesion.

Shock wave attenuation by grids and orifice plates

NASA Astrophysics Data System (ADS)

Britan, A.; Igra, O.; Ben-Dor, G.; Shapiro, H.

2006-11-01

The interaction of weak shock waves with porous barriers of different geometries and porosities is examined. Installing a barrier inside the shock tube test section will cause the development of the following wave pattern upon a head-on collision between the incident shock wave and the barrier: a reflected shock from the barrier and a transmitted shock propagating towards the shock tube end wall. Once the transmitted shock wave reaches the end wall it is reflected back towards the barrier. This is the beginning of multiple reflections between the barrier and the end wall. This full cycle of shock reflections/interactions resulting from the incident shock wave collision with the barrier can be studied in a single shock tube test. A one-dimensional (1D), inviscid flow model was proposed for simulating the flow resulting from the initial collision of the incident shock wave with the barrier. Fairly good agreement is found between experimental findings and simulations based on a 1D flow model. Based on obtained numerical and experimental findings an optimal design procedure for shock wave attenuator is suggested. The suggested attenuator may ensure the safety of the shelter’s ventilation systems.

Calculating shock arrival in expansion tubes and shock tunnels using Bayesian changepoint analysis

NASA Astrophysics Data System (ADS)

James, Christopher M.; Bourke, Emily J.; Gildfind, David E.

2018-06-01

To understand the flow conditions generated in expansion tubes and shock tunnels, shock speeds are generally calculated based on shock arrival times at high-frequency wall-mounted pressure transducers. These calculations require that the shock arrival times are obtained accurately. This can be non-trivial for expansion tubes especially because pressure rises may be small and shock speeds high. Inaccurate shock arrival times can be a significant source of uncertainty. To help address this problem, this paper investigates two separate but complimentary techniques. Principally, it proposes using a Bayesian changepoint detection method to automatically calculate shock arrival, potentially reducing error and simplifying the shock arrival finding process. To compliment this, a technique for filtering the raw data without losing the shock arrival time is also presented and investigated. To test the validity of the proposed techniques, tests are performed using both a theoretical step change with different levels of noise and real experimental data. It was found that with conditions added to ensure that a real shock arrival time was found, the Bayesian changepoint analysis method was able to automatically find the shock arrival time, even for noisy signals.

A critical review of the measurement of ice adhesion to solid substrates

NASA Astrophysics Data System (ADS)

Work, Andrew; Lian, Yongsheng

2018-04-01

Ice adhesion is an issue spanning a wide range of technical fields. In the aerospace industry, ice accretion has led to a large number of casualties and costs the industry billions of dollars every year. To design effective anti-/de-icing systems, the adhesion of ice to surfaces must be understood. In this review paper, the authors surveyed for papers providing methods for the measurement of ice adhesion. 113 papers were identified for comparison, with data being extracted from 58 papers with common test surfaces (aluminum, steel, Teflon® (Chemours), and polyurethane). The methods used were categorized and data were compared based on their precision and the trends they demonstrated. Conceptual problems were identified with the tests used in the literature and discussed, and open questions relevant to testing the adhesion of ice were identified. Several key parameters affecting ice adhesion identified from the literature were temperature, surface roughness, strain rate, and impact velocity. Their effects on adhesion strength were discussed. While researching this topic, it was discovered that many papers did not report the strain rate in their tests, and the vast majority of papers did not correct their data for stress concentrations on the surface, either of which has been shown to cause variation in the data by one order of magnitude. Data compared from the literature typically spanned one to three orders of magnitude. The causes of these variations were discussed.

Examination of a Junction-Box Adhesion Test for Use in Photovoltaic Module Qualification: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, D. C.; Wohlgemuth, J. H.

2012-08-01

Engineering robust adhesion of the junction-box (j-box) is a hurdle typically encountered by photovoltaic (PV) module manufacturers during product development. There are historical incidences of adverse effects (e.g., fires) caused when the j-box/adhesive/module system has failed in the field. The addition of a weight to the j-box during the 'damp heat' IEC qualification test is proposed to verify the basic robustness of its adhesion system. The details of the proposed test will be described, in addition to the preliminary results obtained using representative materials and components. The described discovery experiments examine moisture-cured silicone, foam tape, and hot-melt adhesives used inmore » conjunction with PET or glass module 'substrates.' To be able to interpret the results, a set of material-level characterizations was performed, including thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. PV j-boxes were adhered to a substrate, loaded with a prescribed weight, and then placed inside an environmental chamber (at 85C, 85% relative humidity). Some systems did not remain attached through the discovery experiments. Observed failure modes include delamination (at the j-box/adhesive or adhesive/substrate interface) and phase change/creep. The results are discussed in the context of the application requirements, in addition to the plan for the formal experiment supporting the proposed modification to the qualification test.« less

Influence of previous acid etching on bond strength of universal adhesives to enamel and dentin.

PubMed

Torres, Carlos Rocha Gomes; Zanatta, Rayssa Ferreira; Silva, Tatiane Josefa; Huhtala, Maria Filomena Rocha Lima; Borges, Alessandra Bühler

2017-01-01

The objective of this study was to evaluate the effect of acid pretreatment on the bond strength of composite resin bonded to enamel and dentin with 2 different universal self-etching adhesives. The null hypothesis was that the acid treatment performed prior to adhesive application would not significantly change the bond strength to enamel or dentin for either universal adhesive tested. A sample of 112 bovine incisors were selected and embedded in acrylic resin. Half were ground until a flat enamel surface was obtained, and the other half were polished until a 6 × 6-mm area of dentin was exposed, resulting into 2 groups (n = 56). The enamel and dentin groups were divided into 2 subgroups according to the adhesive system applied: Futurabond U or Scotchbond Universal. Each of these subgroups was divided into 2 additional subgroups (n = 14); 1 subgroup received phosphoric acid pretreatment, and 1 subgroup did not. The bond strength was assessed with a microtensile test. Data from enamel and dentin specimens were analyzed separately using 1-way analysis of variance. The acid pretreatment did not significantly change the bond strength of the adhesives tested, either to enamel (P = 0.4161) or to dentin (P = 0.4857). The acid etching pretreatment did not affect the bond strength to dentin and enamel when the tested universal multipurpose adhesive systems were used.

False context fear memory in rats.

PubMed

Bae, Sarah E; Holmes, Nathan M; Westbrook, R Frederick

2015-10-01

Four experiments used rats to study false context fear memories. In Experiment 1, rats were pre-exposed to a distinctive chamber (context A) or to a control environment (context C), shocked after a delay in a second chamber (context B) and tested either in B or A. Rats pre-exposed to A froze just as much as control rats in B but more than control rats in A. In Experiment 2, rats were pre-exposed to A or C, subjected to an immediate shock in B and tested in B or A. Rats pre-exposed to A froze when tested in A but did not freeze when tested in B and control rats did not freeze in either A or B. The false fear memory to the pre-exposed A was contingent on its similarity with the shocked B. In Experiment 3, rats pre-exposed to A and subjected to immediate shock in B froze when tested in A but did not freeze when tested in C and rats pre-exposed to C did not freeze when tested either in A or C. In Experiment 4, rats pre-exposed to A and subjected to immediate shock in B froze more when tested in A than rats whose pre-exposure to A began with an immediate shock. The results were discussed in terms of a dual systems explanation of context fear conditioning: a hippocampal-dependent process that forms a unitary representation of context and an amygdala-based process which associates this representation with shock. © 2015 Bae et al.; Published by Cold Spring Harbor Laboratory Press.

Transonic Unsteady Aerodynamics of the F/A-18E at Conditions Promoting Abrupt Wing Stall

NASA Technical Reports Server (NTRS)

Schuster, David M.; Byrd, James E.

2003-01-01

A transonic wind tunnel test of an 8% F/A-18E model was conducted in the NASA Langley Research Center (LaRC) 16-Foot Transonic Tunnel (16-Ft TT) to investigate the Abrupt Wing Stall (AWS) characteristics of this aircraft. During this test, both steady and unsteady measurements of balance loads, wing surface pressures, wing root bending moments, and outer wing accelerations were performed. The test was conducted with a wide range of model configurations and test conditions in an attempt to reproduce behavior indicative of the AWS phenomenon experienced on full-scale aircraft during flight tests. This paper focuses on the analysis of the unsteady data acquired during this test. Though the test apparatus was designed to be effectively rigid. model motions due to sting and balance flexibility were observed during the testing, particularly when the model was operating in the AWS flight regime. Correlation between observed aerodynamic frequencies and model structural frequencies are analyzed and presented. Significant shock motion and separated flow is observed as the aircraft pitches through the AWS region. A shock tracking strategy has been formulated to observe this phenomenon. Using this technique, the range of shock motion is readily determined as the aircraft encounters AWS conditions. Spectral analysis of the shock motion shows the frequencies at which the shock oscillates in the AWS region, and probability density function analysis of the shock location shows the propensity of the shock to take on a bi-stable and even tri-stable character in the AWS flight regime.

Aging impairs smooth muscle-mediated regulation of aortic stiffness: a defect in shock absorption function?

PubMed Central

Gao, Yuan Z.; Saphirstein, Robert J.; Yamin, Rina; Suki, Bela

2014-01-01

Increased aortic stiffness is an early and independent biomarker of cardiovascular disease. Here we tested the hypothesis that vascular smooth muscle cells (VSMCs) contribute significantly to aortic stiffness and investigated the mechanisms involved. The relative contributions of VSMCs, focal adhesions (FAs), and matrix to stiffness in mouse aorta preparations at optimal length and with confirmed VSMC viability were separated by the use of small-molecule inhibitors and activators. Using biomechanical methods designed for minimal perturbation of cellular function, we directly quantified changes with aging in aortic material stiffness. An alpha adrenoceptor agonist, in the presence of NG-nitro-l-arginine methyl ester (l-NAME) to remove interference of endothelial nitric oxide, increases stiffness by 90–200% from baseline in both young and old mice. Interestingly, increases are robustly suppressed by the Src kinase inhibitor PP2 in young but not old mice. Phosphotyrosine screening revealed, with aging, a biochemical signature of markedly impaired agonist-induced FA remodeling previously associated with Src signaling. Protein expression measurement confirmed a decrease in Src expression with aging. Thus we report here an additive model for the in vitro biomechanical components of the mouse aortic wall in which 1) VSMCs are a surprisingly large component of aortic stiffness at physiological lengths and 2) regulation of the VSMC component through FA signaling and hence plasticity is impaired with aging, diminishing the aorta's normal shock absorption function in response to stressors. PMID:25128168

Development of a Fish Stress Protein Antibody/Antigen-Based Approach for Biomonitoring of Water Quality.

DTIC Science & Technology

1993-01-25

10 DISCUSSION ............................................... 14 FIELD TESTS OF ANTIBODY DETECTION OF HEAT SHOCK PROTEIN ACCUMULATION IN... TESTS OF ANTIBODY DETECTION OF HEAT SHOCK PROTEIN ACCUMULATION IN ASIAN CLAMS (CORBICULA FLUMINEA) INTRODUCTION The Trinity River flows through...the utility of induction of heat shock proteins as an indicator of stress in another test organism, the Asian clam (Corbicula fluminea). This organism

Comparison of traditional methods for testing paint service life with new methods for service life prediction

Treesearch

R. Sam Williams; Steve Lacher; Jerrold E. Winandy; Corey Halpin; William C. Feist; Christopher White

2004-01-01

Western redcedar siding was "preweathered" by placing it outdoors for 1, 2, 4, 8, or 16 weeks prior to being painted. Panels were painted following the preweathering and tested for paint adhesion. The amount of time these panels were exposed (preweathered) directly affected paint adhesion. As much as 50% paint adhesion loss was shown for specimens...

Effects of water storage on bond strength and dentin sealing ability promoted by adhesive systems.

PubMed

Cantanhede de Sá, Renata Bacelar; Oliveira Carvalho, Adriana; Puppin-Rontani, Regina Maria; Ambrosano, Glaúcia Maria; Nikaido, Toru; Tagami, Junji; Giannini, Marcelo

2012-12-01

To evaluate the dentin bond strength (BS) and sealing ability (SA) promoted by adhesive systems after 24 h or 6 months of water storage. The tested adhesive systems were: one three-step etch-and-rinse adhesive (Adper Scotchbond Multi-Purpose, SBMP) and three single-step self-etching systems (Adper Easy Bond, Bond Force, and G-Bond Plus). Bovine incisors were used for both evaluations, BS (n = 11) and SA (n = 5). To examine BS, the buccal surface was ground with SiC paper to expose a flat dentin surface. After adhesive application, a block of resin composite was incrementally built up over the bonded surface and sectioned into sticks. These bonded specimens were subjected to microtensile bond strength testing after 24 h and 6 months of water storage using a universal testing machine. For SA analysis, enamel was removed from the buccal surfaces. The teeth were connected to a device to measure the initial SA (10 psi), and the second measurement was taken after treating dentin with EDTA. Afterwards, the adhesive systems were applied to dentin and the SA was re-measured for each adhesive after 24 h and 6 months of water storage. The SA was expressed in terms of percentage of dentinal sealing. BS and SA data were submitted to two-way ANOVA and Tukey's test (α = 0.05). All adhesives showed a reduction of SA after 6 months of water storage. The SA promoted by self-etching adhesives was higher than that of SBMP. No adhesive system showed a reduction of the BS after 6 months. Sealing ability was affected by water storage, while no changes in microtensile bond strength were observed after 6 months of water storage. The single-step self-etching systems showed greater sealing ability than did SBMP, even after 6 months of storage in water.

Microshear bond strength of self-etching systems associated with a hydrophobic resin layer.

PubMed

De Vito Moraes, André Guaraci; Francci, Carlos; Carvalho, Ceci Nunes; Soares, Silvio Peixoto; Braga, Roberto Ruggiero

2011-08-01

To evaluate in vitro the microshear bond strength of adhesive systems applied to dentin according to manufacturers' instructions, associated or not with a hydrophobic layer of unfilled resin. Six self-etching adhesives (Clearfil SE Bond, Kuraray Medical; AdheSE, Ivoclar Vivadent; Xeno III, Dentsply; I Bond, Heraeus-Kulzer; Bond Force, Tokuyama; Futurabond DC, Voco) were tested. The labial dentin of sixty bovine incisors was exposed, and the teeth were divided into two groups according to the application or not of an extra hydrophobic resin layer (Scotchbond Multi Purpose Plus, bottle 3). Six composite cylinders (Filtek Z250, 3M ESPE) were built up on each treated surface. Specimens were stored in distilled water at 37ºC for 24 h and then subjected to the microshear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. Microshear bond strength values were analyzed by 2-way ANOVA and Tukey's post-hoc test. Failure mode was determined using a stereomicroscope under 20X magnification. The application of the hydrophobic resin layer did not affect bond strength, except for AdheSE. However, the bond strengths with the hydrophobic layer were similar among the six tested systems (Clearfil: 17.1 ± 7.9; AdheSE: 14.5 ± 7.1; Xeno lll: 12.8 ± 7.7; I Bond: 9.5 ± 5.8; Bond Force: 17.5 ± 4.1; Futurabond: 7.7 ± 2.3). When used as recommended by the manufacturers, Bond Force presented statistically higher bond strength than AdheSE and I Bond (p < 0.05) (Clearfil 10.4 ± 4.9; AdheSE 1.6 ± 1.6; Xeno lll: 9.0 ± 3.8; I Bond: 3.0 ± 1.5; Bond Force: 14 ± 3.9; Futurabond: 8.8 ± 3.8). Failure mode was predominantly adhesive. The bond strength of the self-etching systems tested was not significantly affected by the application of a hydrophobic layer, but a significant improvement was observed in AdheSE.

Performance Evaluation and Durability Studies of Adhesive Bonds

NASA Astrophysics Data System (ADS)

Ranade, Shantanu Rajendra

In this thesis, four test approaches were developed to characterize the adhesion performance and durability of adhesive bonds for specific applications in areas spanning from structural adhesive joints to popular confectionaries such as chewing gum. In the first chapter, a double cantilever beam (DCB) specimen geometry is proposed for combinatorial fracture studies of structural adhesive bonds. This specimen geometry enabled the characterization of fracture energy vs. bondline thickness trends through fewer tests than those required during a conventional "one at a time" characterization approach, potentially offering a significant reduction in characterization times. The second chapter investigates the adhesive fracture resistance and crack path selection in adhesive joints containing patterns of discreet localized weak interfaces created using physical vapor deposition of copper. In a DCB specimen tested under mode-I conditions, fracture energy within the patterned regions scaled according to a simple rule of mixture, while reverse R-curve and R-curve type trends were observed in the regions surrounding weak interface patterns. Under mixed mode conditions such that bonding surface with patterns is subjected to axial tension, fracture energy did not show R-curve type trends while it was observed that a crack could be made to avoid exceptionally weak interfaces when loaded such that bonding surface with defects is subjected to axial compression. In the third chapter, an adaptation of the probe tack test is proposed to characterize the adhesion behavior of gum cuds. This test method allowed the introduction of substrates with well-defined surface energies and topologies to study their effects on gum cud adhesion. This approach and reported insights could potentially be useful in developing chewing gum formulations that facilitate easy removal of improperly discarded gum cuds from adhering surfaces. In the fourth chapter we highlight a procedure to obtain insights into the long-term performance of silicone sealants designed for load-bearing applications such as solar panel support sealants. Using small strain constitutive tests and time-temperature-superposition principle, thermal shift factors were obtained and successfully used to characterize the creep rupture master curves for specific joint configurations, leading to insights into delayed failures corresponding to three years through experiments carried out in one month.

Effect of fibril shape on adhesive properties

NASA Astrophysics Data System (ADS)

Soto, Daniel; Hill, Ginel; Parness, Aaron; Esparza, Noé; Cutkosky, Mark; Kenny, Tom

2010-08-01

Research into the gecko's adhesive system revealed a unique architecture for adhesives using tiny hairs. By using a stiff material (β-keratin) to create a highly structured adhesive, the gecko's system demonstrates properties not seen in traditional pressure-sensitive adhesives which use a soft, unstructured planar layer. In contrast to pressure sensitive adhesives, the gecko adhesive displays frictional adhesion, in which increased shear force allows it to withstand higher normal loads. Synthetic fibrillar adhesives have been fabricated but not all demonstrate this frictional adhesion property. Here we report the dual-axis force testing of single silicone rubber pillars from synthetic adhesive arrays. We find that the shape of the adhesive pillar dictates whether frictional adhesion or pressure-sensitive behavior is observed. This work suggests that both types of behavior can be achieved with structures much larger than gecko terminal structures. It also indicates that subtle differences in the shape of these pillars can significantly influence their properties.

The development of pyro shock test requirements for Viking Lander Capsule components

NASA Technical Reports Server (NTRS)

Barrett, S.

1975-01-01

The procedure used to derive component-level pyro shock specifications for the Viking Lander Capsule (VLC) is described. Effects of shock path distance and mechanical joints between the device and the point at which the environment is to be estimated are accounted for in the method. The validity of the prediction technique was verified by a series of shock tests on a full-scale structural model of the lander body.

Shock-tube studies of silicon-compound vapors

NASA Technical Reports Server (NTRS)

Park, C.; Fujiwara, T.

1977-01-01

Test gas mixtures containing SiO, SiO2, Si2, and SiH were produced in a shock tube by processing shock waves through a mixture of SiCl4 + N2O + Ar, SiH4 + Ar, or SiH4 + O2 + Ar. Absorption spectra of the test gases were studied photographically in the reflected shock region using a xenon flash lamp as the light source in the range of wavelengths between 250 and 600 nm. SiO was found to be a dominant species in the vapors produced by the SiCl4 + N2O and SiH4 + O2 mixtures. Spontaneous combustion was observed in the SiH4 + O2 + Ar mixture prior to the shock arrival, and the resulting solid SiO2 particles evaporated behind the shock wave. Spectral absorption characteristics of SiO, SiO2, Si2, and SiH were determined by studying the test gases.

Evaluation of cytotoxic effects of six self-etching adhesives with direct and indirect contact tests.

PubMed

Kusdemir, Mahmut; Gunal, Solen; Ozer, Fusun; Imazato, Satoshi; Izutani, Naomi; Ebisu, Shigeyuki; Blatz, Markus B

2011-01-01

This study evaluated the cytotoxicity of self-etching primers/adhesives by direct contact and dentin barrier tests. The three two-step self-etching systems Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Prime&Bond NT/NRC (PB) and one-step self-etching systems Reactmer Bond (RB), Clearfil Tri-S Bond (CTS), and Adper Prompt L-Pop (AP) were examined. In direct contact tests, L929 cells were cultured in the presence of diluted solutions (50, 20, 10, and 1%) of primer/conditioner of adhesive systems. For dentin barrier tests, each system was applied onto 0.5 or 1.5 mm thick human dentin assembled in a simple pulp chamber device and incubated for 24 h at 37°C to make the diffusive components contact the L929 cells placed at the bottom of the chamber. The cytotoxic effects were assessed by MTT assay. Cell culture without application of any primers/adhesives served as the control for both tests. One-way ANOVA and Tukey HSD tests were used for statistical analyses. The direct contact tests demonstrated that CSE and CPB were less toxic than the other materials at all dilutions. In the dentin barrier tests, toxic effects of materials were reduced with an increase in thickness of intervening dentin. CSE and CPB showed less cytotoxicity than the other adhesives (p<0.05) when applied to 0.5 mm-thick dentin, and CSE was the least toxic in the 1.5 mm-dentin group (p<0.05). Dentin thickness positively affected biocompatibility of the tested bonding systems. Two-step self-etching systems with HEMA-based primers were more biocompatible than other self-etching adhesives.

Development of design allowables data for adhesives for attaching reusables surface insulation, addendum 1A

NASA Technical Reports Server (NTRS)

Owen, H. P.; Carroll, M. T.

1973-01-01

The task consisted of conducting mechanical and thermal tests to establish design allowables data on a new room temperature vulcanizing (RTV) silicone adhesive, X3-6004. Low modulus, coupled with relatively low density and good low-temperature properties of this adhesive, places it in contention as a candidate for attaching reusable surface insulation on the space shuttle. Data obtained show that the modulus values of X3-6004 are significantly lower than those of RTV-560 and the other three adhesives characterized at test temperatures from 550 to -175 F. At -175, -200 and -270 F, the modulus of X3-6004 is approximately the same as GE RTV-560 and the other three silicone adhesives. The X3-6004 adhesive exhibits good processing properties. It has a 12 percent lower density than RTV-560. Although lower in overall strength properties as compared to the other adhesives in the program, X3-6004 has adequate adhesion to 2024T81 aluminum to compete as an adhesive for attaching reusable surface insulation. It does exhibit some tendency to revert and soften at temperatures above 350 F when in a confined area.

Hot melt adhesive pad surface attachment assembly concept for on-orbit operations

NASA Technical Reports Server (NTRS)

Progar, D. J.; Stein, B. A.

1984-01-01

The use of a hot melt adhesive concept to develop a Surface Attachment Assembly (SAA) for on-orbit attachment and detachment operations for the Manned Maneuvering Unit (MMU) was investigated. The concept involved impregnation of the hot melt adhesive into a fiberglass covered pad which contained electrical heating and thermoelectric cooling devices. The polyamide hot melt adhesive selected can be repeatedly heated to its melting point in a vacuum and provide good adhesion to various surfaces, i.e., reusable surface insulation tiles, metals, and composites, when cooled. After a series of adhesive screening tests, Jet-Melt 3746 was selected from a group of commercially available thermoplastic adhesive candidates which met or exceeded many of the criteria established for the SAA system. The SAA system was designed and fabricted with the goal of proving the concept with a working model rather than attempting to optimize all facets of the system. This system evolved by investigating alternate attachment concepts, designing and fabricating electronic systems to heat and cool the adhesive, and then fabricating electronic systems to heat and cool the adhesive, and then fabricating and testing two prototype full-size units.

Application of tung oil to improve adhesion strength and water resistance of cottonseed meal and protein adhesives on maple veneer

USDA-ARS?s Scientific Manuscript database

Cottonseed meal-based products show promise in serving as environment-friendly wood adhesives. However, their practical utilization is currently limited due to low durability and water resistant properties. In this research, we tested the improvement of adhesion strength and water resistance of cott...

Adhesive performance of washed cottonseed meal at high solid contents and low temperatures

USDA-ARS?s Scientific Manuscript database

Water-washed cottonseed meal (WCSM) has been shown as a promising biobased wood adhesive. Recently, we prepared WSCM in a pilot scale for promoting its industrial application. In this work, we tested the adhesive strength and viscosity of the adhesive preparation with high solid contents (up to 30%...

Influence of the number of cycles on shear fatigue strength of resin composite bonded to enamel and dentin using dental adhesives in self-etching mode.

PubMed

Tsujimoto, Akimasa; Barkmeier, Wayne W; Erickson, Robert L; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

2018-01-30

The influence of the number of cycles on shear fatigue strength to enamel and dentin using dental adhesives in self-etch mode was investigated. A two-step self-etch adhesive and two universal adhesives were used to bond to enamel and dentin in self-etch mode. Initial shear bond strength and shear fatigue strength to enamel and dentin using the adhesive in self-etch mode were determined. Fatigue testing was used with 20 Hz frequency and cycling periods of 50,000, 100,000 and 1,000,000 cycles, or until failure occurred. For each of the cycling periods, there was no significant difference in shear fatigue strength across the cycling periods for the individual adhesives. Differences in shear fatigue strength were found between the adhesives within the cycling periods. Regardless of the adhesive used in self-etch mode for bonding to enamel or dentin, shear fatigue strength was not influenced by the number of cycles used for shear fatigue strength testing.

Mixing-model Sensitivity to Initial Conditions in Hydrodynamic Predictions

NASA Astrophysics Data System (ADS)

Bigelow, Josiah; Silva, Humberto; Truman, C. Randall; Vorobieff, Peter

2017-11-01

Amagat and Dalton mixing-models were studied to compare their thermodynamic prediction of shock states. Numerical simulations with the Sandia National Laboratories shock hydrodynamic code CTH modeled University of New Mexico (UNM) shock tube laboratory experiments shocking a 1:1 molar mixture of helium (He) and sulfur hexafluoride (SF6) . Five input parameters were varied for sensitivity analysis: driver section pressure, driver section density, test section pressure, test section density, and mixture ratio (mole fraction). We show via incremental Latin hypercube sampling (LHS) analysis that significant differences exist between Amagat and Dalton mixing-model predictions. The differences observed in predicted shock speeds, temperatures, and pressures grow more pronounced with higher shock speeds. Supported by NNSA Grant DE-0002913.

Role of cellular adhesions in tissue dynamics spectroscopy

NASA Astrophysics Data System (ADS)

Merrill, Daniel A.; An, Ran; Turek, John; Nolte, David

2014-02-01

Cellular adhesions play a critical role in cell behavior, and modified expression of cellular adhesion compounds has been linked to various cancers. We tested the role of cellular adhesions in drug response by studying three cellular culture models: three-dimensional tumor spheroids with well-developed cellular adhesions and extracellular matrix (ECM), dense three-dimensional cell pellets with moderate numbers of adhesions, and dilute three-dimensional cell suspensions in agarose having few adhesions. Our technique for measuring the drug response for the spheroids and cell pellets was biodynamic imaging (BDI), and for the suspensions was quasi-elastic light scattering (QELS). We tested several cytoskeletal chemotherapeutic drugs (nocodazole, cytochalasin-D, paclitaxel, and colchicine) on three cancer cell lines chosen from human colorectal adenocarcinoma (HT-29), human pancreatic carcinoma (MIA PaCa-2), and rat osteosarcoma (UMR-106) to exhibit differences in adhesion strength. Comparing tumor spheroid behavior to that of cell suspensions showed shifts in the spectral motion of the cancer tissues that match predictions based on different degrees of cell-cell contacts. The HT-29 cell line, which has the strongest adhesions in the spheroid model, exhibits anomalous behavior in some cases. These results highlight the importance of using three-dimensional tissue models in drug screening with cellular adhesions being a contributory factor in phenotypic differences between the drug responses of tissue and cells.

A low-cost, high-yield fabrication method for producing optimized biomimetic dry adhesives

NASA Astrophysics Data System (ADS)

Sameoto, D.; Menon, C.

2009-11-01

We present a low-cost, large-scale method of fabricating biomimetic dry adhesives. This process is useful because it uses all photosensitive polymers with minimum fabrication costs or complexity to produce molds for silicone-based dry adhesives. A thick-film lift-off process is used to define molds using AZ 9260 photoresist, with a slow acting, deep UV sensitive material, PMGI, used as both an adhesion promoter for the AZ 9260 photoresist and as an undercutting material to produce mushroom-shaped fibers. The benefits to this process are ease of fabrication, wide range of potential layer thicknesses, no special surface treatment requirements to demold silicone adhesives and easy stripping of the full mold if process failure does occur. Sylgard® 184 silicone is used to cast full sheets of biomimetic dry adhesives off 4" diameter wafers, and different fiber geometries are tested for normal adhesion properties. Additionally, failure modes of the adhesive during fabrication are noted and strategies for avoiding these failures are discussed. We use this fabrication method to produce different fiber geometries with varying cap diameters and test them for normal adhesion strengths. The results indicate that the cap diameters relative to post diameters for mushroom-shaped fibers dominate the adhesion properties.

Biocompatibility Evaluation of Four Dentin Adhesives Used as Indirect Pulp Capping Materials

PubMed Central

Cortés, Olga; Bernabé, Antonia

2017-01-01

Background In many cases, the indirect pulp treatment (IPT) is an acceptable treatment for deciduous teeth with reversible pulp inflammation. Various medicaments have been used for IPT, ranging from calcium hydroxide and glass ionomers to dentin adhesives. Objective This in vitro trial aimed to measure cytotoxicity in a cell culture, comparing the following four adhesives: Xeno® V (XE), Excite® F DSC (EX), Adhese® OneF (AD) and Prime & Bond NT (PB). Materials and methods The adhesives were prepared according to the manufacturer’s instructions. After 24 hours of exposure, the cell viability was evaluated using a photometrical test (MTT test). Data were subjected to analysis of variance (ANOVA). Results Adhesives, the main component of which was 2-hydroxyethyl methacrylate (HEMA), were found to be less cytotoxic, while those that included the monomer urethane dimethacrylate (UDMA were the most cytotoxic) in their composition. The effects on cell viability assay varied between the adhesives assayed with statistically significant differences. Conclusions The results may support the argument that Adhese® OneF is the least cytotoxic of the adhesives assayed, and may be considered as an adhesive agent for indirect pulp treatment. However, Prime and Bond NT showed a reduced biocompatibility under the same conditions. PMID:28827848

Mesoporous Silica Nanoparticles-Encapsulated Agarose and Heparin as Anticoagulant and Resisting Bacterial Adhesion Coating for Biomedical Silicone.

PubMed

Wu, Fan; Xu, Tingting; Zhao, Guangyao; Meng, Shuangshuang; Wan, Mimi; Chi, Bo; Mao, Chun; Shen, Jian

2017-05-30

Silicone catheter has been widely used in peritoneal dialysis. The research missions of improving blood compatibility and the ability of resisting bacterial adhesion of silicone catheter have been implemented for the biomedical requirements. However, most of modification methods of surface modification were only able to develop the blood-contacting biomaterials with good hemocompatibility. It is difficult for the biomaterials to resist bacterial adhesion. Here, agarose was selected to resist bacterial adhesion, and heparin was chosen to improve hemocompatibility of materials. Both of them were loaded into mesoporous silica nanoparticles (MSNs), which were successfully modified on the silicone film surface via electrostatic interaction. Structures of the mesoporous coatings were characterized in detail by dynamic light scattering, transmission electron microscopy, Brunauer-Emmett-Teller surface area, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscope, and water contact angle. Platelet adhesion and aggregation, whole blood contact test, hemolysis and related morphology test of red blood cells, in vitro clotting time tests, and bacterial adhesion assay were performed to evaluate the anticoagulant effect and the ability of resisting bacterial adhesion of the modified silicone films. Results indicated that silicone films modified by MSNs had a good anticoagulant effect and could resist bacterial adhesion. The modified silicone films have potential as blood-contacting biomaterials that were attributed to their biomedical properties.

Validation of laboratory-scale recycling test method of paper PSA label products

Treesearch

Carl Houtman; Karen Scallon; Richard Oldack

2008-01-01

Starting with test methods and a specification developed by the U.S. Postal Service (USPS) Environmentally Benign Pressure Sensitive Adhesive Postage Stamp Program, a laboratory-scale test method and a specification were developed and validated for pressure-sensitive adhesive labels, By comparing results from this new test method and pilot-scale tests, which have been...

High Order Numerical Methods for LES of Turbulent Flows with Shocks

NASA Technical Reports Server (NTRS)

Kotov, D. V.; Yee, H. C.; Hadjadj, A.; Wray, A.; Sjögreen, B.

2014-01-01

Simulation of turbulent flows with shocks employing explicit subgrid-scale (SGS) filtering may encounter a loss of accuracy in the vicinity of a shock. In this work we perform a comparative study of different approaches to reduce this loss of accuracy within the framework of the dynamic Germano SGS model. One of the possible approaches is to apply Harten's subcell resolution procedure to locate and sharpen the shock, and to use a one-sided test filter at the grid points adjacent to the exact shock location. The other considered approach is local disabling of the SGS terms in the vicinity of the shock location. In this study we use a canonical shock-turbulence interaction problem for comparison of the considered modifications of the SGS filtering procedure. For the considered test case both approaches show a similar improvement in the accuracy near the shock.

Combined effect of smear layer characteristics and hydrostatic pulpal pressure on dentine bond strength of HEMA-free and HEMA-containing adhesives.

PubMed

Mahdan, Mohd Haidil Akmal; Nakajima, Masatoshi; Foxton, Richard M; Tagami, Junji

2013-10-01

This study evaluated the combined effect of smear layer characteristics with hydrostatic pulpal pressure (PP) on bond strength and nanoleakage expression of HEMA-free and -containing self-etch adhesives. Flat dentine surfaces were obtained from extracted human molars. Smear layers were created by grinding with #180- or #600-SiC paper. Three HEMA-free adhesives (Xeno V, G Bond Plus, Beautibond Multi) and two HEMA-containing adhesives (Bond Force, Tri-S Bond) were applied to the dentine surfaces under hydrostatic PP or none. Dentine bond strengths were determined using the microtensile bond test (μTBS). Data were statistically analyzed using three- and two-way ANOVA with Tukey post hoc comparison test. Nanoleakage evaluation was carried out under a scanning electron microscope (SEM). Coarse smear layer preparation and hydrostatic PP negatively affected the μTBS of HEMA-free and -containing adhesives, but there were no significant differences. The combined experimental condition significantly reduced μTBS of the HEMA-free adhesives, while the HEMA-containing adhesives exhibited no significant differences. Two-way ANOVA indicated that for HEMA-free adhesives, there were significant interactions in μTBS between smear layer characteristics and pulpal pressure, while for HEMA-containing adhesives, there were no significant interactions between them. Nanoleakage formation within the adhesive layers of both adhesive systems distinctly increased in the combined experimental group. The combined effect of coarse smear layer preparation with hydrostatic PP significantly reduced the μTBS of HEMA-free adhesives, while in HEMA-containing adhesives, these effects were not obvious. Smear layer characteristics and hydrostatic PP would additively compromise dentine bonding of self-etch adhesives, especially HEMA-free adhesives. Copyright © 2013 Elsevier Ltd. All rights reserved.

A marine bacterial adhesion microplate test using the DAPI fluorescent dye: a new method to screen antifouling agents.

PubMed

Leroy, C; Delbarre-Ladrat, C; Ghillebaert, F; Rochet, M J; Compère, C; Combes, D

2007-04-01

To develop a method to screen antifouling agents against marine bacterial adhesion as a sensitive, rapid and quantitative microplate fluorescent test. Our experimental method is based on a natural biofilm formed by mono-incubation of the marine bacterium Pseudoalteromonas sp. D41 in sterile natural sea water in a 96-well polystyrene microplate. The 4'6-diamidino-2-phenylindole dye was used to quantify adhered bacteria in each well. The total measured fluorescence in the wells was correlated with the amount of bacteria showing a detection limit of one bacterium per 5 microm(2) and quantifying 2 x 10(7) to 2 x 10(8) bacteria adhered per cm(2). The antifouling properties of three commercial surface-active agents and chlorine were tested by this method in the prevention of adhesion and also in the detachment of already adhered bacteria. The marine bacterial adhesion inhibition rate depending on the agent concentration showed a sigmoid shaped dose-response curve. This test is well adapted for a rapid and quantitative first screening of antifouling agents directly in seawater in the early steps of marine biofilm formation. In contrast to the usual screenings of antifouling products which detect a bactericidal activity, this test is more appropriate to screen antifouling agents for bacterial adhesion removal or bacterial adhesion inhibition activities. This screening test focuses on the antifouling properties of the products, especially the initial steps of marine biofilm formation.

Transient Three-Dimensional Startup Side Load Analysis of a Regeneratively Cooled Nozzle

NASA Technical Reports Server (NTRS)

Wang, Ten-See

2008-01-01

The objective of this effort is to develop a computational methodology to capture the startup side load physics and to anchor the computed aerodynamic side loads with the available data from a regeneratively cooled, high-aspect-ratio nozzle, hot-fired at sea level. The computational methodology is based on an unstructured-grid, pressure-based, reacting flow computational fluid dynamics and heat transfer formulation, a transient 5 s inlet history based on an engine system simulation, and a wall temperature distribution to reflect the effect of regenerative cooling. To understand the effect of regenerative wall cooling, two transient computations were performed using the boundary conditions of adiabatic and cooled walls, respectively. The results show that three types of shock evolution are responsible for side loads: generation of combustion wave; transitions among free-shock separation, restricted-shock separation, and simultaneous free-shock and restricted shock separations; along with the pulsation of shocks across the lip, although the combustion wave is commonly eliminated with the sparklers during actual test. The test measured two side load events: a secondary and lower side load, followed by a primary and peak side load. Results from both wall boundary conditions captured the free-shock separation to restricted-shock separation transition with computed side loads matching the measured secondary side load. For the primary side load, the cooled wall transient produced restricted-shock pulsation across the nozzle lip with peak side load matching that of the test, while the adiabatic wall transient captured shock transitions and free-shock pulsation across the lip with computed peak side load 50% lower than that of the measurement. The computed dominant pulsation frequency of the cooled wall nozzle agrees with that of a separate test, while that of the adiabatic wall nozzle is more than 50% lower than that of the measurement. The computed teepee-like formation and the tangential motion of the shocks during lip pulsation also qualitatively agree with those of test observations. Moreover, a third transient computation was performed with a proportionately shortened 1 s sequence, and lower side loads were obtained with the higher ramp rate.

Effect of blood contamination with 1-step self-etching adhesives on microtensile bond strength to dentin.

PubMed

Yoo, H M; Pereira, P N R

2006-01-01

This study evaluated the effect of blood contamination and decontamination methods on the microtensile bond strength of 1-step self-etching adhesive systems to dentin contaminated after adhesive application and light curing. Three commercially available "all-in-one" adhesives (One Up Bond F, Xeno III and Adper Prompt L-Pop) and 1 resin composite (Clearfil AP-X) were used. Third molars that had been stored in distilled water with 0.5% thymol at 4 degrees C were ground with #600 SiC paper under running water to produce a standardized smear layer. The specimens were randomly divided into groups according to the 3 adhesive systems. The adhesive systems were used under 3 conditions: no contamination, which was the control (C); contamination of the light-cured adhesive surface with blood and reapplication of adhesive (Contamination 1) and contamination of the light-cured adhesive surface with blood, then washing, drying and reapplication of the adhesive (Contamination 2). Following light curing of the adhesive, the resin composite was placed in 3 increments up to a 5-mm-thick layer on the bonded surface. All specimens were stored in distilled water at 37 degrees C for 24 hours. The microtensile bond strength was measured using a universal testing machine (EZ test), and data were analyzed by 1-way ANOVA followed by the Duncan test to make comparisons among the groups (p=0.05). After debonding, 5 specimens were selected from each group and examined in a scanning electron microscope to evaluate the modes of fracture. For all adhesives, contamination groups showed lower bond strength than the control (p<0.05). There was no statistically significant difference among the control groups (p>0.05). For Xeno III and Adper Prompt L-Pop, contamination group #2 showed the lowest bond strength among the groups (p<0.05). For One Up Bond F, contamination group #2 showed higher bond strength than contamination group #1 but showed no statistical significance between them (p>0.05).

Shear bond strength of two 2-step etch-and-rinse adhesives when bonding ceramic brackets to bovine enamel.

PubMed

Godard, Marion; Deuve, Benjamin; Lopez, Isabelle; Hippolyte, Marie-Pascale; Barthélemi, Stéphane

2017-09-01

The present study assessed a fracture analysis and compared the shear bond strength (SBS) of two 2-step etch-and-rinse (E&R) adhesives when bonding ceramic orthodontic brackets to bovine enamel. Thirty healthy bovine mandibular incisors were selected and were equally and randomly assigned to 2 experimental groups. Ceramic brackets (FLI Signature Clear ® , RMO) were bonded onto bovine enamel using an adhesive system. In group 1 (n=15), the conventional E&R adhesive (OrthoSolo ® +Enlight ® , Ormco) was used, and in group 2 (n=15), the new E&R adhesive limited to ceramic bracket bonding (FLI ceramic adhesive ® : FLI sealant resin ® +FLI adhesive paste ® , RMO) was used. In order to obtain appropriate enamel surfaces, the vestibular surfaces of mandibular bovine incisors were flat ground. After bonding, all the samples were stored in distilled water at room temperature for 21 days and subsequently tested for SBS, using the Instron ® universal testing machine. The Adhesive Remnant Index (ARI) scores were evaluated. Failure modes were assessed using optical microscopy at magnification ×40. A statistic data analysis was performed using the Mann-Whitney U-test (P<0.05). The test showed a significant difference (P=0.00155) between the two groups for the SBS values. Group 1 had significantly higher SBS values (9.79 to 20.83MPa) than group 2 (8.45 to 13.94MPa). Analysis of the ARI scores revealed that most of the failures occurred at the enamel/adhesive interface. A statistically significant difference was found for the ARI scores between the two groups (P=0.00996). Only two fractured brackets, which remained bonded onto the bovine enamel, were reported. Both occurred in group 1. When bonded to ceramic brackets, FLI ceramic adhesive ® (RMO) was demonstrated to be very predictable and safe for clinical application in enamel bonding, whereas the results obtained with the conventional adhesive system (OrthoSolo ® +Enlight ® , Ormco) were less reproducible and revealed slightly excessive shear bond strength values. Copyright © 2017 CEO. Published by Elsevier Masson SAS. All rights reserved.

Casein Phosphopeptide-Amorphous Calcium Phosphate and Shear Bond Strength of Adhesives to Primary Teeth Enamel

PubMed Central

Farokh Gisovar, Elham; Hedayati, Nassim; Shadman, Niloofar; Shafiee, Leila

2015-01-01

Background: CPP-ACP (Phosphopeptide-Amorphous Calcium Phosphate) has an important role in caries prevention in pediatric patients. This study was done, because of the great use of CPP-ACP and the need for restoration for teeth treated with CPP-ACP as well as the importance of shear bond strength of adhesives in the success of restorations. Objectives: This study aimed to evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on shear bond strength of dental adhesives to enamel of primary teeth molars. Materials and Methods: This in vitro study was conducted on 180 extracted primary molars. They were randomly divided into 6 groups and each group was divided into 2 subgroups (treated with CPP-ACP and untreated). In subgroups with CPP-ACP, enamel was treated with CPP-ACP paste 1 h/d for 5 days. Types of adhesives that were evaluated in this study were Tetric N-Bond, AdheSE, AdheSE One F, single Bond 2, SE Bond, and Adper Prompt L-Pop. Shear bond strength was tested with a universal testing machine and mode of failure was evaluated under stereomicroscope. Data were analyzed by T test, 2-way analysis of variance (ANOVA), Tukey and Fisher exact test using SPSS18. P < 0.05 was considered as significance level. Results: Shear bond strengths of different adhesive systems to enamel of primary teeth treated and untreated with CPP-ACP showed no significant difference (P > 0.05). Mode of failure in all groups regardless of CPP-ACP administration was mainly adhesive type. Our results indicated that CPP-ACP did not affect shear bond strength of studied adhesives to primary teeth enamel. Conclusions: To have a successful and durable composite restoration, having a high strength bonding is essential. Considering the wide use of CPP-ACP in preventing tooth decay and the role of adhesive shear bond strength (SBS) in success of composite restoration, we conducted the present study to evaluate the effect of CPP-ACP on the SBS of adhesives to primary teeth enamel. PMID:25793113

Pyrotechnic shock at the orbiter/external tank forward attachment

NASA Technical Reports Server (NTRS)

Rogers, W. F.; Grissom, D. S.; Rhodes, L. R.

1980-01-01

During the initial certification test of the forward structural attachment of the space shuttle orbiter to the external tank, pyrotechnic shock from actuation of the separation device resulted in structural failure of the thermal protection tiles surrounding the attachment. Because of the high shock associated with the separation bolt, the development of alternative low shock separation designs was initiated. Two concepts that incorporate a 5.08 centimeter frangible nut as the release device were developed and tested.

33 CFR 159.105 - Shock test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... MARINE SANITATION DEVICES Design, Construction, and Testing § 159.105 Shock test. The device, with liquid retention components, if any, filled with water to half of their volume, must be subjected to 1,000 vertical...

High-speed OH* chemiluminescence imaging of ignition through a shock tube end-wall

NASA Astrophysics Data System (ADS)

Troutman, V. A.; Strand, C. L.; Campbell, M. F.; Tulgestke, A. M.; Miller, V. A.; Davidson, D. F.; Hanson, R. K.

2016-03-01

A high-speed OH* chemiluminescence imaging diagnostic was developed to image the structure and homogeneity of combustion events behind reflected shock waves in the Stanford Constrained Reaction Volume Shock Tube. An intensified high-repetition-rate imaging system was used to acquire images of OH* chemiluminescence (near 308 nm) through a fused quartz shock tube end-wall window at 10-33 kHz during the combustion of n-heptane (21 % O2/Ar, φ = 0.5). In general, the imaging technique enabled observation of the main ignition event in the core of the shock tube that corresponded to typical markers of ignition (e.g., pressure rise), as well as localized ignition near the wall that preceded the main core ignition event for some conditions. Case studies were performed to illustrate the utility of this novel imaging diagnostic. First, by comparing localized wall ignition events to the core ignition event, the temperature homogeneity of the post-reflected shock gas near the end-wall was estimated to be within 0.5 % for the test condition presented (T=1159 hbox {K}, P=0.25 hbox {MPa}). Second, the effect of a recession in the shock tube wall, created by an observation window, on the combustion event was visualized. Localized ignition was observed near the window, but this disturbance did not propagate to the core of the shock tube before the main ignition event. Third, the effect of shock tube cleanliness was investigated by conducting tests in which the shock tube was not cleaned for multiple consecutive runs. For tests after no cleaning was performed, ignition events were concentrated in the lower half of the shock tube. In contrast, when the shock tube was cleaned, the ignition event was distributed around the entire circumference of the shock tube; validating the cleaning procedure.

Improving controllable adhesion on both rough and smooth surfaces with a hybrid electrostatic/gecko-like adhesive

PubMed Central

Ruffatto, Donald; Parness, Aaron; Spenko, Matthew

2014-01-01

This paper describes a novel, controllable adhesive that combines the benefits of electrostatic adhesives with gecko-like directional dry adhesives. When working in combination, the two technologies create a positive feedback cycle whose adhesion, depending on the surface type, is often greater than the sum of its parts. The directional dry adhesive brings the electrostatic adhesive closer to the surface, increasing its effect. Similarly, the electrostatic adhesion helps engage more of the directional dry adhesive fibrillar structures, particularly on rough surfaces. This paper presents the new hybrid adhesive's manufacturing process and compares its performance to three other adhesive technologies manufactured using a similar process: reinforced PDMS, electrostatic and directional dry adhesion. Tests were performed on a set of ceramic tiles with varying roughness to quantify its effect on shear adhesive force. The relative effectiveness of the hybrid adhesive increases as the surface roughness is increased. Experimental data are also presented for different substrate materials to demonstrate the enhanced performance achieved with the hybrid adhesive. Results show that the hybrid adhesive provides up to 5.1× greater adhesion than the electrostatic adhesive or directional dry adhesive technologies alone. PMID:24451392

Clinical acceptability of two self-etch adhesive resins for the bonding of orthodontic brackets to enamel.

PubMed

Schnebel, Bradley; Mateer, Scott; Maganzini, Anthony Louis; Freeman, Katherine

2012-12-01

To determine whether two self-adhesive resin cements, Clearfil SA and RelyX, can be used to successfully bond orthodontic brackets to enamel. Seventy extracted premolars were custom mounted, cleaned and randomly divided into three groups. In group 1 (control), orthodontic brackets were bonded to 25 premolars using the Transbond Plus and Transbond XT two step adhesive systerm adhesive. In group 2, brackets were bonded to 25 premolars using Clearfil SA. In group 3, brackets were bonded to 20 premolars using RelyX. The brackets were debonded using a universal testing machine and shear bond strengths recorded. After debonding, each tooth was examined under 20× magnification to evaluate the residual adhesive remaining. An ANOVA with Duncan's Multiple Range Test was used to determine whether there were significant differences in shear bond strength between the groups. A Kruskal-Wallis Test and a Bonferroni multiple comparison procedure were used to compare the bond failure modes (adhesive remnant index scores) between the groups. The mean shear bond strengths for the brackets bonded using Clearfil SA and RelyX were 5·930±1·840 and 3·334±1·953 MPa, respectively. Both were significantly lower than that for the brackets bonded using Transbond (7·875±3·611 MPa). Both self-etch adhesive resin cement groups showed a greater incidence of bracket failure at the enamel/adhesive interface while the Transbond group showed a higher incidence at the bracket/adhesive interface. The shear bond strengths of the self-etch adhesive resin cements may be inadequate to successfully bond orthodontic brackets to enamel.

Bio-Inspired Controllable Adhesive

DTIC Science & Technology

2008-12-01

pad of the tarsus – which act as a sort of hydraulic suspension. The lamellae contain rows of thin slender fibers , called setae, approximately 130 µm...in length and 20 µm in diameter (Hildebrand, 1988), Fig.1. The terminus of each seta branches into thousands of smaller fibers , or spatular stalks...ADHESION TESTING The structures were characterized (Northen et al., 2008) using a home-built adhesion test apparatus ( Basalt - II) with C. Greiner

Adhesion of new bioactive glass coating.

PubMed

Schrooten, J; Van Oosterwyck, H; Vander Sloten, J; Helsen, J A

1999-03-05

A valuable alternative to the existing biomedical implant coatings is a bioactive glass (BAG) coating that is produced by reactive plasma spraying. A mechanical performance requirement that is of the utmost importance is the adhesion strength of the coating. Considering the application as dental implant, a new adhesion test (shear test), which was close to the service conditions, was designed. A Ti6Al4V rod (3 mm) with a sprayed BAG coating of 50 microm was glued with an epoxy glue to a hollow cylindrical counterpart and was used as such in the tensile machine. This test was evaluated by finite element analysis (FEA). Preliminary experiments showed that a conversion from shear to tensile adhesion strength is possible by using the Von Mises criterion (sigma = 3(1/2)tau), indicating that thin coatings of brittle materials can behave as a ductile material. The new coating technique was proved to produce a high quality coating with an adhesion strength of 40.1 +/- 4.8 MPa in shear and 69.4 +/- 8.4 MPa in tension. The FEA revealed that no one homogeneously distributed shear stress is present but several nonhomogeneously distributed stress components (shear and tensile) are present in the coating. This analysis indicated that real service conditions are much more complicated than standard adhesion tests. Copyright 1999 John Wiley & Sons, Inc.

Evaluation of high temperature structural adhesives for extended service

NASA Technical Reports Server (NTRS)

Hill, S. G.; Peters, P. D.; Hendricks, C. L.

1982-01-01

The evaluation, selection, and demonstration of structural adhesive systems for supersonic cruise research applications, and establishment of environmental durability of selected systems for up to 20,000 hours is described. Ten candidate adhesives were initially evaluated. During screening and evaluation, these candidates were narrowed to three of the most promising for environmental durability testing. The three adhesives were LARC-13, PPQ, and NR056X. The LARC-13 was eliminated because of a lack of stability at 505 K. The NRO56X was removed from the market. The LARC-TPI was added after preliminary evaluation and an abbreviated screening test. Only PPQ and LARC-TPI remained as the reasonable candidates late into the durability testing. Large area bond panels were fabricated to demonstrate the processibility of the selected systems. Specifications were prepared to assure control over critical material and process parameters. Surface characterization concentrated primarily upon titanium surface treatments of 10 volt chronic acid anodize, 5 volt chromic acid anodize and PASA-JELL. Failure analysis was conducted on lap shear adhesive bond failures which occurred in PPQ and LARC-13 test specimens after 10,000 hours at 505 K.

Spared Anterograde Memory for Shock-Probe Fear Conditioning After Inactivation of the Amygdala

PubMed Central

Lehmann, Hugo; Treit, Dallas; Parent, Marise B.

2003-01-01

Previous studies have shown that amygdala lesions impair avoidance of an electrified probe. This finding has been interpreted as indicating that amygdala lesions reduce fear. It is unclear, however, whether amygdala-lesioned rats learn that the probe is associated with shock. If the lesions prevent the formation of this association, then pretraining reversible inactivation of the amygdala should impair both acquisition and retention performance. To test this hypothesis, the amygdala was inactivated (tetrodotoxin; TTX; 1 ng/side) before a shock-probe acquisition session, and retention was tested 4 d later. The data indicated that, compared with rats infused with vehicle, rats infused with TTX received more shocks during the acquisition session, but more importantly, were not impaired on the retention test. In Experiment 2, we assessed whether the spared memory on the retention test was caused by overtraining during acquisition. We used the same procedure as in Experiment 1, with the exception that the number of shocks the rats received during the acquisition session was limited to four. Again the data indicated that amygdala inactivation did not impair performance on the retention test. These results indicate that amygdala inactivation does not prevent the formation of an association between the shock and the probe and that shock-probe deficits during acquisition likely reflect the amygdala's involvement in other processes. PMID:12888544

Effects of Extremely High ’G’ Acceleration Forces on NASA’s Control and Space Exposed Tomato Seeds

DTIC Science & Technology

1991-12-01

mechanical shock test; tomatoes staked 28 and interplanted with dwarf marigolds for nematode protection of tomatoes 28 NASA control seed mechanical shock...plants transplanted to garden Figure 27. NASA control seed mechanical shock test; tomatoes staked and interplanted with dwarf marigolds for nematode

Development of a Post-Installed Deepwater Monitoring System

NASA Technical Reports Server (NTRS)

Seaman, C.; Brower, D. V.; Tang, H.; Le, S.

2015-01-01

A monitoring system that can be deployed on already existing deep water risers and flowlines has been developed. This paper describes the design concepts and testing that was performed in developing the monitoring system. A major challenge of a post-installed instrumentation system is to ensure adequate coupling is achieved between the instruments and the riser or flowline. This work investigates the sensor coupling for pipelines that are suspended in both the water column (from topside platform to the seabed) and for those that are located directly on the seabed. These different environments have resulted in two sensor attachment methods: (1) subsea adhesive sensor clamp design and (2) a friction surface sensor attachment method. This paper presents the adhesive attachment method. The monitoring elements consist of fiber optic sensors that are encased in a polyurethane clamp. With a subsea adhesive, the clamp can be installed by divers in shallow depths or by use of an ROV for deeper applications. The NASA Johnson Space Center was initially involved in the selection and testing of subsea adhesives. It was determined that up to 75 percent of the bonding strength could be achieved with the adhesive from optimal dry bonding versus bonding in submerged sea water environments. The next phase of the study involved the design, fabrication, and testing of several prototype clamps that contained the fiber optic sensors. A mold was produced by NASA using 3-D printing methods that allowed the fabrication of subscale test articles that would accommodate 4-inch and 8-inch diameter pipes. The clamps were installed with adhesive in a "wet" environment on the pipe test articles and tested in the NASA Structures Test Laboratory. The tension/compression and bending tests showed that the prototype sensor clamps achieved good coupling, and could provide high quality strain measurement for active monitoring.

Effect of Dentin Wetness on the Bond Strength of Universal Adhesives.

PubMed

Choi, An-Na; Lee, Ji-Hye; Son, Sung-Ae; Jung, Kyoung-Hwa; Kwon, Yong Hoon; Park, Jeong-Kil

2017-10-25

The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS) testing and confocal laser scanning microscopy (CLSM). Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying), 5, and 10 s. The dentin surfaces were then treated with three universal adhesives: G-Premio Bond, Single Bond Universal, and All-Bond Universal in self-etch or etch-and-rinse mode. After composite build up, a μTBS test was performed. One additional tooth was prepared for each group by staining the adhesives with 0.01 wt % of Rhodamine B fluorescent dye for CLSM analysis. The data were analyzed statistically using ANOVA and Tukey's post hoc tests (α = 0.05). Two-way ANOVA showed significant differences among the adhesive systems and dentin moisture conditions. An interaction effect was also observed ( p < 0.05). One-way ANOVA showed that All-Bond Universal was the only material influenced by the wetness of the dentin surfaces. Wetness of the dentin surface is a factor influencing the micro-tensile bond strength of universal adhesives.

Effect of Dentin Wetness on the Bond Strength of Universal Adhesives

PubMed Central

Lee, Ji-Hye; Son, Sung-Ae; Jung, Kyoung-Hwa; Kwon, Yong Hoon

2017-01-01

The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS) testing and confocal laser scanning microscopy (CLSM). Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying), 5, and 10 s. The dentin surfaces were then treated with three universal adhesives: G-Premio Bond, Single Bond Universal, and All-Bond Universal in self-etch or etch-and-rinse mode. After composite build up, a μTBS test was performed. One additional tooth was prepared for each group by staining the adhesives with 0.01 wt % of Rhodamine B fluorescent dye for CLSM analysis. The data were analyzed statistically using ANOVA and Tukey’s post hoc tests (α = 0.05). Two-way ANOVA showed significant differences among the adhesive systems and dentin moisture conditions. An interaction effect was also observed (p < 0.05). One-way ANOVA showed that All-Bond Universal was the only material influenced by the wetness of the dentin surfaces. Wetness of the dentin surface is a factor influencing the micro-tensile bond strength of universal adhesives. PMID:29068404

Surface Pre-treatment for Thermally Sprayed ZnAl15 Coatings

NASA Astrophysics Data System (ADS)

Bobzin, K.; Öte, M.; Knoch, M. A.

2017-02-01

Pre-treatment of substrates is an important step in thermal spraying. It is widely accepted that mechanical interlocking is the dominant adhesion mechanism for most substrate-coating combinations. To prevent premature failure, minimum coating adhesion strength, surface preparation grades, and roughness parameters are often specified. For corrosion-protection coatings for offshore wind turbines, an adhesion strength ≥ 5 MPa is commonly assumed to ensure adhesion over service lifetime. In order to fulfill this requirement, Rz > 80 µm and a preparation grade of Sa3 are common specifications. In this study, the necessity of these requirements is investigated using the widely used combination of twin-wire arc-sprayed ZnAl15 on S355J2 + N as a test case. By using different blasting media and parameters, the correlation between coating adhesion and roughness parameters is analyzed. The adhesion strength of these systems is measured using a test method allowing measurements on real parts. The results are compared to DIN EN 582:1993, the European equivalent of ASTM-C633. In another series of experiments, the influence of surface pre-treatment grades Sa2.5 and Sa3 is considered. By combining the results of these three sets of experiments, a guideline for surface pre-treatment and adhesion testing on real parts is proposed for the considered system.

Improved metal-adhesive polymers from copper(I)-catalyzed azide-alkyne cycloaddition.

PubMed

Accurso, Adrian A; Delaney, Mac; O'Brien, Jeff; Kim, Hyonny; Iovine, Peter M; Díaz Díaz, David; Finn, M G

2014-08-18

Electrically conductive adhesive polymers offer many potential advantages relative to Sn-Pb solders, including reduced toxicity, low cost, low processing temperatures, and the ability to make application-specific formulations. Polymers generated from the copper(I)-catalyzed cycloaddition (CuAAC) reaction between multivalent azides and alkynes have previously been identified as strong metal-binding adhesives. Herein we demonstrate that the performance of these materials can be remarkably improved by the incorporation of a flexibility-inducing difunctionalized component and a tertiary amine additive in optimized concentrations. The best formulations were identified by means of rapid adhesion testing of a library of potential candidates by using a custom-built instrument and validated in an American Society for Testing and Materials (ASTM)-standard lap-shear test. Characteristic phase transitions were identified by differential scanning calorimetry (DSC) for adhesives with and without the additives as a function of curing temperature. The incorporation of flexible components was found to more than double the strength of the adhesive. Moreover, the adhesive was made electrically conductive by the inclusion of 20 wt% silver-coated copper flakes and further improved in this regard by the incorporation of multiwalled carbon nanotubes in the formulation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Potential for Biobased Adhesives in Wood Bonding

Treesearch

Charles R. Frihart

2016-01-01

There has been a resurgence of interest and research on using bio-based materials as wood adhesives; however, they have achieved only limited market acceptance. To better understand this low level of replacement, it is important to understand why adhesives work or fail in moisture durability tests. A holistic model for wood adhesives has been developed that clarifies...

Protein Modifiers Generally Provide Limited Improvement in Wood Bond Strength of Soy Flour Adhesives

Treesearch

Charles R. Frihart; Linda Lorenz

2013-01-01

Soy flour adhesives using a polyamidoamine-epichlorohydrin (PAE) polymeric coreactant are used increasingly as wood adhesives for interior products. Although these adhesives give good performance, higher bond strength under wet conditions is desirable. Wet strength is important for accelerated tests involving the internal forces generated by the swelling of wood and...

Adrenocorticotropin reverses vascular dysfunction and protects against splanchnic artery occlusion shock

PubMed Central

Squadrito, Francesco; Guarini, Salvatore; Altavilla, Domenica; Squadrito, Giovanni; Campo, Giuseppe M; Arlotta, Mariarita; Quartarone, Cristina; Saitta, Antonino; Cucinotta, Domenico; Bazzani, Carla; Cainazzo, Maria M; Mioni, Chiara; Bertolini, Alfio; Caputi, Achille P

1999-01-01

Tumour necrosis factor (TNF-α) is involved in the pathogenesis of splanchnic artery occlusion (SAO) shock. On the other hand, inhibition of TNF-α is an important component of the mechanism of action of melanocortins in reversing haemorrhagic shock. We therefore investigated the effects of the melanocortin peptide ACTH-(1–24) (adrenocorticotropin fragment 1–24) on the vascular failure induced by SAO shock.SAO-shocked rats had a decreased survival rate (0% at 4 h of reperfusion, while sham-shocked rats survived for more than 4 h), enhanced serum TNF-α concentrations (755±81 U ml−1), decreased mean arterial blood pressure, leukopenia, and increased ileal leukocyte accumulation, as revealed by means of myeloperoxidase activity (MPO=9.4±1 U g−1 tissue). Moreover, aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (PE, 1 nM–10 μM) (Emax and ED50 in shocked rats=7.16 mN mg−1 tissue and 120 nM, respectively; Emax and ED50 in sham-shocked rats=16.31 mN mg−1 tissue and 100 nM, respectively), reduced responsiveness to acetylcholine (ACh, 10 nM-10 μM) (Emax and ED50 in shocked rats=30% relaxation and 520 nM, respectively; Emax and ED50 in sham-shocked rats=82% relaxation and 510 nM, respectively) and increased staining for intercellular adhesion molecule-1 (ICAM-1).ACTH-(1–24) [160 μg kg−1 intravenously (i.v.), 5 min after SAO] increased survival rate [SAO+ACTH-(1–24)=80% at 4 h of reperfusion], reversed hypotension, reduced serum TNF-α (55±13 U ml−1), ameliorated leukopenia, reduced ileal MPO (1.2±0.2 U g−1 tissue), restored the reactivity to PE, improved the responsiveness to ACh and blunted the enhanced immunostaining for ICAM-1 in the aorta.Adrenalectomy only in part–but not significantly–reduced the ACTH-induced shock reversal, the survival rate of SAO+ACTH-(1–24) adrenalectomized rats being 60% at 4 h of reperfusion; and methylprednisolone (80 mg−1 i.v., 5 min after SAO) had a non-significant effect (10% survival) at 4 h of reperfusion.The present data show that melanocortins are effective also in SAO shock, their effect being, at least in part, mediated by reduced production of TNF-α. Furthermore, they demonstrate, for the first time, that this inhibition is responsible for the adrenocorticotropin-induced reversal of vascular failure and leukocyte accumulation. PMID:10516667

Inhibition of blood platelet adhesion by phenolics' rich fraction of Hippophae rhamnoides L. fruits.

PubMed

Olas, B; Kontek, B; Szczesna, M; Grabarczyk, L; Stochmal, A; Zuchowski, J

2017-04-01

Beneficial influence of fruits on human health may be their ability to prevent the hyperactivation of blood platelets and cardiovascular disorders. Effects of the phenolic fraction from Hippophae rhamnoides fruit on different stages of blood platelet activation (platelet adhesion and aggregation) were studied in vitro. We also examined effects of the H. rhamnoides fraction on metabolism of thiol groups, which plays an important role in platelet functions. The effects of the H. rhamnoides fraction on adhesion of blood platelets to collagen and fibrinogen were determined with Tuszynski's and Murphy's method. The platelet aggregation was determined with turbidimetry. The action of the H. rhamnoides fraction on the level of thiol groups in platelet proteins and a level of glutathione (GSH) in platelets was estimated with 5,5'-dithio-bis(2-nitro-benzoic acid). The tested fraction of H. rhamnoides (0.5 - 50 μg/ml; 30 min of the incubation time 30 min) inhibited blood platelets adhesion to collagen and fibrinogen. The effect of the tested fraction on blood platelet adhesion depended on concentration of fraction. In presence of the highest tested concentration which was 50 μg/ml, inhibition of platelet adhesion for thrombin-activated platelets was about 55%. On the other hand, tested plant fraction had no anti-aggregatory properties. Our results showed anti-adhesive properties of phenolic fraction from H. rhamnoides fruit and we suggest that it may be beneficial for prevention of cardiovascular diseases.

Simulation and characterization of a laterally-driven inertial micro-switch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Wenguo; Wang, Yang; Wang, Huiying

2015-04-15

A laterally-driven inertial micro-switch was designed and fabricated using surface micromachining technology. The dynamic response process was simulated by ANSYS software, which revealed the vibration process of movable electrode when the proof mass is shocked by acceleration in sensitive direction. The test results of fabricated inertial micro-switches with and without anti-shock beams indicated that the contact process of micro-switch with anti-shock beams is more reliable than the one without anti-shock beams. The test results indicated that three contact signals had been observed in the contact process of the inertial switch without anti-shock beams, and only one contact signal in themore » inertial switch with anti-shock beams, which demonstrated that the anti-shock beams can effectively constrain the vibration in non-sensitive direction.« less

Effect of Board Thickness on Sn-Ag-Cu Joint Interconnect Mechanical Shock Performance

NASA Astrophysics Data System (ADS)

Lee, Tae-Kyu; Xie, Weidong

2014-12-01

The mechanical stability of solder joints with Sn-Ag-Cu alloy joints on various board thicknesses was investigated with a high G level shock environment. A test vehicle with three different board thicknesses was used for board drop shock performance tests. These vehicles have three different strain and shock level condition couples per board, and are used to identify the joint stability and failure modes based on the board responses. The results revealed that joint stability is sensitive to board thickness. The board drop shock test showed that the first failure location shifts from the corner location near the standoff to the center with increased board thickness due to the shock wave response. From analysis of the thickness variation and failure cycle number, the strain rate during the pulse strain cycle is the dominant factor, which defines the life cycle number per board thickness, and not the maximum strain value. The failure location shift and the shock performance differentiation are discussed from the perspective of maximum principal strain, cycle frequency and strain rate per cycle.

Flight Demonstration of a Shock Location Sensor Using Constant Voltage Hot-Film Anemometry

NASA Technical Reports Server (NTRS)

Moes, Timothy R.; Sarma, Garimella R.; Mangalam, Siva M.

1997-01-01

Flight tests have demonstrated the effectiveness of an array of hot-film sensors using constant voltage anemometry to determine shock position on a wing or aircraft surface at transonic speeds. Flights were conducted at the NASA Dryden Flight Research Center using the F-15B aircraft and Flight Test Fixture (FTF). A modified NACA 0021 airfoil was attached to the side of the FTF, and its upper surface was instrumented to correlate shock position with pressure and hot-film sensors. In the vicinity of the shock-induced pressure rise, test results consistently showed the presence of a minimum voltage in the hot-film anemometer outputs. Comparing these results with previous investigations indicate that hot-film anemometry can identify the location of the shock-induced boundary layer separation. The flow separation occurred slightly forward of the shock- induced pressure rise for a laminar boundary layer and slightly aft of the start of the pressure rise when the boundary layer was tripped near the airfoil leading edge. Both minimum mean output and phase reversal analyses were used to identify the shock location.

Llama heavy-chain antibody fragments efficiently remove toxic shock syndrome toxin 1 from plasma in vitro but not in experimental porcine septic shock.

PubMed

Brummelhuis, Walter J; Joles, Jaap A; Stam, Jord C; Adams, Hendrik; Goldschmeding, Roel; Detmers, Frank J; El Khattabi, Mohamed; Maassen, Bram T; Verrips, C Theo; Braam, Branko

2010-08-01

Staphylococcus aureus produces the superantigen toxic shock syndrome toxin 1 (TSST-1). When the bacterium invades the human circulation, this toxin can induce life-threatening gram-positive sepsis. Current sepsis treatment does not remove bacterial toxins. Variable domains of llama heavy-chain antibodies (VHH) against toxic shock syndrome toxin 1 ([alpha]-TSST-1 VHH) were previously found to be effective in vitro. We hypothesized that removing TSST-1 with [alpha]-TSST-1 VHH hemofiltration filters would ameliorate experimental sepsis in pigs. After assessing in vitro whether timely removing TSST-1 interrupted TSST-1-induced mononuclear cell TNF-[alpha] production, VHH-coated filters were applied in a porcine sepsis model. Clinical course, survival, plasma interferon [gamma], and TSST-1 levels were similar with and without VHH-coated filters as were TSST-1 concentrations before and after the VHH filter. Plasma TSST-1 levels were much lower than anticipated from the distribution of the amount of infused TSST-1, suggesting compartmentalization to space or adhesion to surface not accessible to hemofiltration or pheresis techniques. Removing TSST-1 from plasma was feasible in vitro. However, the [alpha]-TSST-1 VHH adsorption filter-based technique was ineffective in vivo, indicating that improvement of VHH-based hemofiltration is required. Sequestration likely prevented the adequate removal of TSST-1. The latter warrants further investigation of TSST-1 distribution and clearance in vivo.

The adhesive strength and initial viscosity of denture adhesives.

PubMed

Han, Jian-Min; Hong, Guang; Dilinuer, Maimaitishawuti; Lin, Hong; Zheng, Gang; Wang, Xin-Zhi; Sasaki, Keiichi

2014-11-01

To examine the initial viscosity and adhesive strength of modern denture adhesives in vitro. Three cream-type denture adhesives (Poligrip S, Corect Cream, Liodent Cream; PGS, CRC, LDC) and three powder-type denture adhesives (Poligrip Powder, New Faston, Zanfton; PGP, FSN, ZFN) were used in this study. The initial viscosity was measured using a controlled-stress rheometer. The adhesive strength was measured according to ISO-10873 recommended procedures. All data were analyzed independently by one-way analysis of variance combined with a Student-Newman-Keuls multiple comparison test at a 5% level of significance. The initial viscosity of all the cream-type denture adhesives was lower than the powder-type adhesives. Before immersion in water, all the powder-type adhesives exhibited higher adhesive strength than the cream-type adhesives. However, the adhesive strength of cream-type denture adhesives increased significantly and exceeded the powder-type denture adhesives after immersion in water. For powder-type adhesives, the adhesive strength significantly decreased after immersion in water for 60 min, while the adhesive strength of the cream-type adhesives significantly decreased after immersion in water for 180 min. Cream-type denture adhesives have lower initial viscosity and higher adhesive strength than powder type adhesives, which may offer better manipulation properties and greater efficacy during application.

Shear Bond Strength of Self-etching Adhesives to Cavities Prepared by Diamond Bur or Er,Cr:YSGG Laser and Effect of Prior Acid Etching.

PubMed

Jhingan, Pulkit; Sachdev, Vinod; Sandhu, Meera; Sharma, Karan

2015-12-01

To compare and evaluate shear bond strength of self-etching adhesives bonded to cavities prepared by diamond bur or Er,Cr:YSGG laser and the effect of prior acid etching on shear bond strength. Ninety-six caries-free human premolars were selected and divided into 2 groups depending on mode of cavity preparation (48 teeth each). Cavities were prepared with Er,Cr:YSGG laser in group 1 and diamond burs in an air-turbine handpiece in group 2. Groups 1 and 2 were further subdivided into three subgroups of 8 teeth each, which were bonded with sixth- or seventh-generation adhesives with or without prior acid etching, followed by restoration of all samples with APX Flow. These samples were subjected to shear bond strength testing. In addition, the surface morphology of 24 samples each from groups 1 and 2 was evaluated using SEM. Data were analyzed using the Shapiro-Wilk test, one- and two-way ANOVA, the t-test, and the least significant difference test, which showed that the data were normally distributed (p > 0.05). The shear bond strength of adhesives in cavities prepared by Er,Cr:YSGG laser was significantly higher than in diamond bur-prepared cavities (p < 0.05). SEM analysis showed a smear-layer-free anfractuous surface on laser-ablated teeth, in contrast to conventional bur-prepared teeth. The Er,Cr:YSGG laser-ablated surface proved to be more receptive for adhesion than those prepared by diamond bur irrespective of the bonding agent used. Seventh-generation adhesives yielded higher shear bond strength than did sixth-generation adhesives. Prior acid etching decreased the shear bond strength of self-etching adhesives.

Effect of curing and silanizing on composite repair bond strength using an improved micro-tensile test method

PubMed Central

Eliasson, Sigfus Thor; Dahl, Jon E.

2017-01-01

Abstract Objectives: To evaluate the micro-tensile repair bond strength between aged and new composite, using silane and adhesives that were cured or left uncured when new composite was placed. Methods: Eighty Filtek Supreme XLT composite blocks and four control blocks were stored in water for two weeks and thermo-cycled. Sandpaper ground, etched and rinsed specimens were divided into two experimental groups: A, no further treatment and B, the surface was coated with bis-silane. Each group was divided into subgroups: (1) Adper Scotchbond Multi-Purpose, (2) Adper Scotchbond Multi-Purpose adhesive, (3) Adper Scotchbond Universal, (4) Clearfil SE Bond and (5) One Step Plus. For each adhesive group, the adhesive was (a) cured according to manufacturer’s instructions or (b) not cured before repair. The substrate blocks were repaired with Filtek Supreme XLT. After aging, they were serially sectioned, producing 1.1 × 1.1 mm square test rods. The rods were prepared for tensile testing and tensile strength calculated at fracture. Type of fracture was examined under microscope. Results: Leaving the adhesive uncured prior to composite repair placement increased the mean tensile values statistically significant for all adhesives tested, with or without silane pretreatment. Silane surface treatment improved significantly (p < 0.001) tensile strength values for all adhesives, both for the cured and uncured groups. The mean strength of the control composite was higher than the strongest repair strength (p < 0.001). Conclusions: Application of freshly made silane and a thin bonding layer, rendered higher tensile bond strength. Not curing the adhesive before composite placement increased the tensile bond strength. PMID:28642928

Adhesion testing procedure for hot-poured crack sealants.

DOT National Transportation Integrated Search

2008-11-01

Crack sealing is a common pavement maintenance treatment because it extends pavement service life significantly. : However, crack sealant often fails prematurely due to a loss of adhesion. Because current test methods are mostly : empirical and only ...

The Shock and Vibration Bulletin. Part 1. Invited Papers, Submarine Shock Testing, Shock Analysis, Shock Testing

DTIC Science & Technology

1973-06-01

approximately 4. Use of a cold gas for determining was determined and presented in Figure 3. This analysis was unsteady flow characteristics and...driven by a hydraulic motor. shown experimentally that drawbar force re- Roller motion develops a high rotating force , ductions greater than one part in...of doors, a water table flow bient pressure. The interest in determining this decay time is analogy was used. With this analogy, a two-dimensional

Analysis of the flow in a 1-MJ electric-arc shock tunnel

NASA Technical Reports Server (NTRS)

Reller, J. O., Jr.; Reddy, N. M.

1972-01-01

In the electric-arc-heated shock tunnel, the facility performance over a range of shock Mach numbers from 7 to 19 was evaluated. The efficiency of the arc-heated driver is deduced using an improved form of the shock tube equation. A theoretical and experimental analysis is made of the tailored-interface condition. The free stream properties in the test section, with nitrogen as the test gas, are evaluated using a method based on stagnation point, heat transfer measurements.

Computer modeling of test particle acceleration at oblique shocks

NASA Technical Reports Server (NTRS)

Decker, Robert B.

1988-01-01

The present evaluation of the basic techniques and illustrative results of charged particle-modeling numerical codes suitable for particle acceleration at oblique, fast-mode collisionless shocks emphasizes the treatment of ions as test particles, calculating particle dynamics through numerical integration along exact phase-space orbits. Attention is given to the acceleration of particles at planar, infinitessimally thin shocks, as well as to plasma simulations in which low-energy ions are injected and accelerated at quasi-perpendicular shocks with internal structure.

Development Status of Low-Shock Payload Separation Mechanism for H-IIA Launch Vehicle

NASA Astrophysics Data System (ADS)

Terashima, Keita; Kamita, Toru; Horie, Youichi; Kobayashi, Masakazu; Onikura, Hiroki

2013-09-01

This paper presents the design, analysis and test results of the low-shock payload separation mechanism for the H-IIA launch vehicle. The mechanism is based on a simple and reliable four-bar linkage, which makes the release speed of the marman clamp band tension lower than the current system.The adequacy of the principle for low-shock mechanism was evaluated by some simulations and results of fundamental tests. Then, we established the reliability design model of this mechanism, and the adequacy of this model was evaluated by elemental tests.Finally, we conducted the system separation tests using the payload adapter to which the mechanism was assembled, to confirm that the actual separation shock level satisfied our target.

The effectiveness of adhesives on the retention of mandibular free end saddle partial dentures: An in vitro study.

PubMed

Quiney, Daniel; Nishio Ayre, Wayne; Milward, Paul

2017-07-01

Existing in vitro methods for testing denture adhesives do not fully replicate the complex oral geometries and environment; and in vivo methods are qualitative, prone to bias and not easily reproducible. The purpose of this study was to develop a novel, quantitative and more accurate model to test the effect of adhesives on the retentive force of mandibular free end saddle partial dentures. An in vitro model was developed based on an anatomically accurate cast of a clinical case. Experimentally, the amount of adhesive was varied (0.2g-1g) and the tensile force required for displacement was measured. Different commercially available adhesives were then tested at the optimum volume using the in vitro model. A 3D finite element model of the denture was used to assess how the forces to induce denture displacement varied according to the position of the force along the saddle length. The mass of adhesive was found to significantly alter retention forces, with 0.4-0.7g being the optimum range for this particular scenario. Use of adhesives significantly improved mandibular free end saddle partial denture retention with the worst performing adhesive increasing retention nine-fold whilst the best performing adhesive increased retention twenty three-fold. The finite element model revealed that 77% more force was required to displace the denture by positioning forces towards the mesial end of the saddle compared to the distal end. An in vitro denture adhesive model was developed, which demonstrated that mass of adhesive plays a significant role in enhancing denture retention and supported the design principle of placing as few teeth as clinically necessary on the distal end of the free end saddles. Limiting the position of teeth on free end saddles to the mesial and mid portion of the saddle will reduce displacements caused by mastication. The movement of mandibular free end saddle partial dentures can be restricted with the use of denture adhesives. Altering the mass of adhesive used can further improve the retention of mandibular free end saddle partial dentures for patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of Different Etching Modes on Bond Strength to Enamel using Universal Adhesive Systems.

PubMed

Diniz, Ana Cs; Bandeca, Matheus C; Pinheiro, Larissa M; Dos Santosh Almeida, Lauber J; Torres, Carlos Rg; Borges, Alvaro H; Pinto, Shelon Cs; Tonetto, Mateus R; De Jesus Tavarez, Rudys R; Firoozmand, Leily M

2016-10-01

The adhesive systems and the techniques currently used are designed to provide a more effective adhesion with reduction of the protocol application. The objective of this study was to evaluate the bond strength of universal adhesive systems on enamel in different etching modes (self-etch and total etch). The mesial and distal halves of 52 bovine incisors, healthy, freshly extracted, were used and divided into seven experimental groups (n = 13). The enamel was treated in accordance with the following experimental conditions: FUE-Universal System - Futurabond U (VOCO) with etching; FUWE - Futurabond U (VOCO) without etching; SB-Total Etch System - Single Bond 2 (3M); SBUE-Universal System - Single Bond Universal (3M ESPE) with etching; SBUWE - Single Bond Universal (3M ESPE) without etching; CLE-Self-etch System - Clearfil SE Bond (Kuraray) was applied with etching; CLWE - Clearfil SE Bond (Kuraray) without etching. The specimens were made using the composite spectrum TPH (Dentsply) and stored in distilled water (37 ± 1°C) for 1 month. The microshear test was performed using the universal testing machine EMIC DL 2000 with the crosshead speed of 0.5 mm/minute. The bond strength values were analyzed using statistical tests (Kruskal-Wallis test and Mann-Whitney test) with Bonferroni correction. There was no statistically significant difference between groups (p < 0.05), where FUE (36.83 ± 4.9 MPa) showed the highest bond strength values and SBUWE (18.40 ± 2.2 MPa) showed the lowest bond strength values. The analysis of adhesive interface revealed that most failures occurred between the interface composite resin and adhesive. The universal adhesive system used in dental enamel varies according to the trademark, and the previous enamel etching for universal systems and the self-etch both induced greater bond strength values. Selective enamel etching prior to the application of a universal adhesive system is a relevant strategy for better performance bonding.

Influence of a hydrophobic resin coating on the immediate and 6-month dentin bonding of three universal adhesives.

PubMed

Sezinando, Ana; Luque-Martinez, Issis; Muñoz, Miguel Angel; Reis, Alessandra; Loguercio, Alessandro D; Perdigão, Jorge

2015-10-01

To test the influence of a hydrophobic resin coating (HC) on the immediate (24h) and 6-month (6m) microtensile dentin bond strengths (μTBS) and nanoleakage (NL) of three universal adhesives applied in self-etch (SE) or in etch-and-rinse (ER) mode. Sixty caries-free extracted third molars were assigned to 12 experimental groups resulting from the combination of the factors "adhesive system" (Scotchbond Universal Adhesive [SBU], 3M ESPE; All-Bond Universal [ABU], Bisco Inc.; and G-Bond Plus [GBP], GC Corporation); "adhesive strategy" (SE or ER); "hydrophobic resin coating" [HC] (with or without Heliobond, Ivoclar Vivadent); and "storage time" (24h or 6m). Specimens were prepared for μTBS testing - (24h) half of the beams were immediately tested under tension; and (6m) the other half was stored in distilled water (37°C) for 6m prior to testing. For each tooth, two beams were randomly selected for NL evaluation for both evaluation times. Data were analyzed for each adhesive system using three-way ANOVA and Tukey's post-hoc test (α=0.05). μTBS: (24h): In SE mode, HC resulted in statistically greater mean μTBS for all adhesives. (6m): When HC was not used the mean μTBS for SBU/ER, ABU/ER, GBP/ER and SBU/SE decreased significantly. NL: (24h): SBU/ER, ABU/ER and GBP/SE resulted in a significant reduction in NL when HC was applied. (6m): No significant reduction was observed for SBU/ER or for SBU/SE regardless of the use of HC. The application of a hydrophobic resin coating improved the 24h and the 6m performances of all three adhesives systems in SE mode. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

High-Temperature Adhesive Strain Gage Developed

NASA Technical Reports Server (NTRS)

Pereira, J. Michael; Roberts, Gary D.

1997-01-01

Researchers at the NASA Lewis Research Center have developed a unique strain gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. For example, typical commercial strain gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial strain gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' strain gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal strain gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the strain gage measurement on a polyimide specimen at 315 C with an extensometer measurement.

A microfabricated gecko-inspired controllable and reusable dry adhesive

NASA Astrophysics Data System (ADS)

Chary, Sathya; Tamelier, John; Turner, Kimberly

2013-02-01

Geckos utilize a robust reversible adhesive to repeatedly attach and detach from a variety of vertical and inverted surfaces, using structurally anisotropic micro- and nano-scale fibrillar structures. These fibers, when suitably articulated, are able to control the real area of contact and thereby generate high-to-low van der Waals forces. Key characteristics of the natural system include highly anisotropic adhesion and shear forces for controllable attachment, a high adhesion to initial preload force ratio (μ‧) of 8-16, lack of inter-fiber self-adhesion, and operation over more than 30 000 cycles without loss of adhesion performance. A highly reusable synthetic adhesive has been developed using tilted polydimethylsiloxane (PDMS) half-cylinder micron-scale fibers, retaining up to 77% of the initial value over 10 000 repeated test cycles against a flat glass puck. In comparison with other gecko-inspired adhesives tested over 10 000 cycles or more thus far, this paper reports the highest value of μ‧, along with a large shear force of ˜78 kPa, approaching the 88-226 kPa range of gecko toes. The anisotropic adhesion forces are close to theoretical estimates from the Kendall peel model, quantitatively showing how lateral shearing articulation in a manner similar to the gecko may be used to obtain adhesion anisotropy with synthetic fibers using a combination of tilt angle and anisotropic fiber geometry.

A new facility for studying shock-wave passage over dust layers

NASA Astrophysics Data System (ADS)

Chowdhury, A. Y.; Marks, B. D.; Johnston, H. Greg; Mannan, M. Sam; Petersen, E. L.

2016-03-01

Dust explosion hazards in areas where coal and other flammable materials are found have caused unnecessary loss of life and halted business operations in some instances. The elimination of secondary dust explosion hazards, i.e., reducing dust dispersion, can be characterized in shock tubes to understand shock-dust interactions. For this reason, a new shock-tube test section was developed and integrated into an existing shock-tube facility. The test section has large windows to allow for the use of the shadowgraph technique to track dust-layer growth behind a passing normal shock wave, and it is designed to handle an initial pressure of 1 atm with an incident shock wave Mach number as high as 2 to mimic real-world conditions. The test section features an easily removable dust pan with inserts to allow for adjustment of the dust-layer thickness. The design also allows for changing the experimental variables such as initial pressure, shock Mach number (Ms), dust-layer thickness, and the characteristics of the dust itself. The characterization experiments presented herein demonstrate the advantages of the authors' test techniques toward providing new physical insights over a wider range of data than what have been available heretofore in the literature. Limestone dust with a layer thickness of 3.2 mm was subjected to Ms = 1.23, 1.32, and 1.6 shock waves, and dust-layer rise height was mapped with respect to time after shock passage. Dust particles subjected to a Ms = 1.6 shock wave rose more rapidly and to a greater height with respect to shock wave propagation than particles subjected to Ms = 1.23 and 1.32 shock waves. Although these results are in general agreement with the literature, the new data also highlight physical trends for dust-layer growth that have not been recorded previously, to the best of the authors' knowledge. For example, the dust-layer height rises linearly until a certain time where the growth rate is dramatically reduced, and in this second regime there is clear evidence of surface vertical structures at the dust-air interface.

Influence of Thin-Film Adhesives in Pullout Tests Between Nickel-Titanium Shape Memory Alloy and Carbon Fiber-Reinforced Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Quade, Derek J.; Jana, Sadhan; McCorkle, Linda S.

2018-01-01

Strips of nickel-titanium (NiTi) shape memory alloy (SMA) and carbon fiber-reinforced polymer matrix composite (PMC) were bonded together using multiple thin film adhesives and their mechanical strengths were evaluated under pullout test configuration. Tensile and lap shear tests were conducted to confirm the deformation of SMAs at room temperature and to evaluate the adhesive strength between the NiTi strips and the PMC. Optical and scanning electron microscopy techniques were used to examine the interfacial bonding after failure. Simple equations on composite tensile elongation were used to fit the experimental data on tensile properties. ABAQUS models were generated to show the effects of enhanced bond strength and the distribution of stress in SMA and PMC. The results revealed that the addition of thin film adhesives increased the average adhesive strength between SMA and PMC while halting the room temperature shape memory effect within the pullout specimen.

Adhesive properties and adhesive joints strength of graphite/epoxy composites

NASA Astrophysics Data System (ADS)

Rudawska, Anna; Stančeková, Dana; Cubonova, Nadezda; Vitenko, Tetiana; Müller, Miroslav; Valášek, Petr

2017-05-01

The article presents the results of experimental research of the adhesive joints strength of graphite/epoxy composites and the results of the surface free energy of the composite surfaces. Two types of graphite/epoxy composites with different thickness were tested which are used to aircraft structure. The single-lap adhesive joints of epoxy composites were considered. Adhesive properties were described by surface free energy. Owens-Wendt method was used to determine surface free energy. The epoxy two-component adhesive was used to preparing the adhesive joints. Zwick/Roell 100 strength device were used to determination the shear strength of adhesive joints of epoxy composites. The strength test results showed that the highest value was obtained for adhesive joints of graphite-epoxy composite of smaller material thickness (0.48 mm). Statistical analysis of the results obtained, the study showed statistically significant differences between the values of the strength of the confidence level of 0.95. The statistical analysis of the results also showed that there are no statistical significant differences in average values of surface free energy (0.95 confidence level). It was noted that in each of the results the dispersion component of surface free energy was much greater than polar component of surface free energy.

Elastic modulus of tree frog adhesive toe pads.

PubMed

Barnes, W Jon P; Goodwyn, Pablo J Perez; Nokhbatolfoghahai, Mohsen; Gorb, Stanislav N

2011-10-01

Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5-15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4-25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs.

Research on Reasons for Repeated Falling of Tiles in Internal Walls of Construction

NASA Astrophysics Data System (ADS)

Xu, LiBin; Chen, Shangwei; He, Xinzhou; Zhu, Guoliang

2018-03-01

In view of the quality problem of repeated falling of facing tiles in some construction, the essay had a comparative trial in laboratory on cement mortar which is often used to paste tiles, special tile mortar and dry-hang glue, and measured durability of tile adhesive mortar through freezing and thawing tests. The test results indicated that ordinary cement mortar cannot meet standards due to reasons like big shrinkage and low adhesive. In addition, the ten times of freezing and thawing tests indicated that ordinary cement mortar would directly shell and do not have an adhesive force, and moreover, adhesive force of special tile mortar would reduce. Thus, for tiles of large size which are used for walls, dry-hang techniques are recommended to be used.

Incorporation of Tin on copper clad laminate to increase the interface adhesion for signal loss reduction of high-frequency PCB lamination

NASA Astrophysics Data System (ADS)

Wang, Chong; Wen, Na; Zhou, Guoyun; Wang, Shouxu; He, Wei; Su, Xinhong; Hu, Yongsuan

2017-11-01

A novel method of improving the adhesion between copper and prepreg in high frequency PCB was proposed and studied in this work. This process which aimed to decrease the IEP (isoelectric point) of the copper to obtain higher adhesion, was achieved by depositing a thin tin layer with lower IEP on copper. It was characterized by scanning electron microscopy (SEM), 3D microscope, peel strength test, X-Ray thickness test, grazing incidence X-ray diffraction (GXRD), X-ray photoelectron spectroscopy (XPS), Agilent vector network analyzer (VNA), which confirmed its excellent adhesion performance and outstanding electrical properties in high-frequency signal transmission compared with traditional brown oxide method. Moreover, the mechanism of achieving high adhesion for this method was also investigated.

Adhesive performance of precoated brackets after expiration.

PubMed

Cloud, Cayce C; Trojan, Terry M; Suliman, Sam N; Tantbirojn, Daranee; Versluis, Antheunis

2016-03-01

To evaluate adhesive performance in terms of debonding forces of precoated metal and ceramic brackets 4 years after expiration. Buccal and lingual surfaces of embedded extracted maxillary premolars were etched with 34% Tooth Conditioner Gel (Dentsply Caulk, Milford, Del), rinsed, and dried. Transbond MIP (3M Unitek, Monrovia, Calif) was applied prior to placing adhesive precoated brackets (APC II Victory stainless steel and APC Plus Clarity ceramic brackets, 3M Unitek). The preexpiration brackets had 29-35 months before, and the postexpiration brackets were 45-52 months past, their expiration dates. Sample size was 17-21 per group. Debonding forces were determined by subjecting the bonded brackets to a shear force in a universal testing machine. Debonding forces were compared using two-way ANOVA. Debonded surfaces were examined under a stereomicroscope to determine failure modes, which were compared using the chi-square test. No statistically significant difference was found in debonding forces (P  =  .8581) or failure modes (P  =  .4538) between expired and unexpired brackets. Metal brackets required statistically significantly higher debonding forces than did ceramic brackets (P  =  .0001). For both expired and unexpired brackets, failure modes were mostly cohesive in the adhesive layer for ceramic brackets, and mixed between adhesive and cohesive failure in the adhesive layer for metal brackets. Adhesive precoated brackets did not have any reduction in enamel-adhesion properties up to 4 years after their expiration date. Extended shelf life testing for precoated dental brackets may be worth considering.

EFFECT OF AN ADDITIONAL HYDROPHILIC VERSUS HYDROPHOBIC COAT ON THE QUALITY OF DENTINAL SEALING PROVIDED BY TWO-STEP ETCH-AND-RINSE ADHESIVES

PubMed Central

Silva, Safira Marques de Andrade; Carrilho, Marcela Rocha de Oliveira; Marquezini, Luiz; Garcia, Fernanda Cristina Pimentel; Manso, Adriana Pigozzo; Alves, Marcelo Corrêa; de Carvalho, Ricardo Marins

2009-01-01

Objective: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. Material and Methods: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. Results: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. Conclusions: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent. PMID:19466248

Mussel-mimetic, bioadhesive polymers from plant-derived materials.

PubMed

Hiraishi, Noriko; Kaneko, Daisaku; Taira, Shu; Wang, Siqian; Otsuki, Masayuki; Tagami, Junji

2015-02-01

Mussel-mimetic, bioadhesive polymers are synthesized from plant-derived sources. The strong adhesive action is caused by interactions between the catechol groups at the end of the polymer terminal chains and the substrate surface. Here, we present a preliminary study of the adhesion properties and a discussion of the adhesion mechanism. Two bioadhesive polymers were synthesized from natural plant-derived monomers by the transesterification of: (a) caffeic acid (3,4-dihydroxycinnamic acid; DHCA) and p-coumaric acid (4-hydroxycinnamic acid; 4HCA) to produce poly(DHCA-co-4HCA); and (b) 4-dihydroxyhydrocinnamic acid (DHHCA) and 3-(3-hydroxyphenyl) propionic acid (3HPPA) to produce poly(DHHCA-co-3HPPA). Thermoplastic poly(DHCA-co-4HCA) or poly(DHHCA-co-3HPPA) was placed between glass, carbon, steel, or bovine dentin substrates, and a lap shear adhesion test was conducted to compare them using conventional cyanoacrylate glue and epoxy resin. The greatest adhesion for all tested substrates was exhibited by poly(DHHCA-co-3HPPA), followed by epoxy resin adhesive, poly(DHCA-co-4HCA), and cyanoacrylate adhesive. The adhesive strength of poly(DHHCA-co-3HPPA) was greater than 25.6 MPa for glass, 29.6 MPa for carbon, 15.7 MPa for steel, and 16.3 MPA for bovine dentin. The adhesion of poly(DHHCA-co-3HPPA) might be the strongest reported for a mussel-mimic adhesive system, and could be a feasible alternative to petroleum adhesives. © 2013 Wiley Publishing Asia Pty Ltd.

Influence of an oxygen-inhibited layer on enamel bonding of dental adhesive systems: surface free-energy perspectives.

PubMed

Ueta, Hirofumi; Tsujimoto, Akimasa; Barkmeier, Wayne W; Oouchi, Hajime; Sai, Keiichi; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

2016-02-01

The influence of an oxygen-inhibited layer (OIL) on the shear bond strength (SBS) to enamel and surface free-energy (SFE) of adhesive systems was investigated. The adhesive systems tested were Scotchbond Multipurpose (SM), Clearfil SE Bond (CS), and Scotchbond Universal (SU). Resin composite was bonded to bovine enamel surfaces to determine the SBS, with and without an OIL, of adhesives. The SFE of cured adhesives with and without an OIL were determined by measuring the contact angles of three test liquids. There were no significant differences in the mean SBS of SM and CS specimens with or without an OIL; however, the mean SBS of SU specimens with an OIL was significantly higher than that of SU specimens without an OIL. For all three systems, the mean total SFE (γS), polarity force (γSp), and hydrogen bonding force (γSh) values of cured adhesives with an OIL were significantly higher than those of cured adhesives without an OIL. The results of this study indicate that the presence of an OIL promotes higher SBS of a single-step self-etch adhesive system, but not of a three-step or a two-step self-etch primer system. The SFE values of cured adhesives with an OIL were significantly higher than those without an OIL. The SFE characteristics of the OIL of adhesives differed depending on the type of adhesive. © 2015 Eur J Oral Sci.

Tests of the Performance of Coatings for Low Ice Adhesion

NASA Technical Reports Server (NTRS)

Anderson, David N.; Reich, Allen D.

1997-01-01

This paper reports studies of the performance of low-ice-adhesion coatings by NASA Lewis and BFGoodrich. Studies used impact ice accreted both in the NASA Lewis Icing Research Tunnel (IRT) and in the BFGoodrich Icing Wind Tunnel (IWT) and static ice in a BFGoodrich bench-top parallel-plate shear rig. Early tests at NASA Lewis involved simple qualitative evaluations of the ease of removing impact ice from a surface. Coated surfaces were compared with uncoated ones. Some of the coatings were tested again with static ice at BFGoodrich to obtain quantitative measurements. Later, methods to establish the adhesion force on surfaces subjected to impact ice were explored at Lewis. This paper describes the various test programs and the results of testing some of the coatings looked at over the past 5 years. None of the coatings were found to be truly ice-phobic; however, the most effective coatings were found to reduce the adhesion of ice to about 1/2 that of an uncoated aluminum sample.

Shear bond strength of one-step self-etch adhesives to enamel: effect of acid pretreatment.

PubMed

Poggio, Claudio; Scribante, Andrea; Della Zoppa, Federica; Colombo, Marco; Beltrami, Riccardo; Chiesa, Marco

2014-02-01

The purposes of this study were to evaluate the effect of surface pretreatment with phosphoric acid on the enamel bond strength of four-one-step self-etch adhesives with different pH values. One hundred bovine permanent mandibular incisors were used. The materials used in this study included four-one-step self-etch adhesives with different pH values: Adper(™) Easy Bond Self-Etch Adhesive (ph = 0,8-1), Futurabond NR (ph = 1,4), G-aenial Bond (ph = 1,5), Clearfil(3) S Bond (ph = 2,7). One two-step self-etch adhesive (Clearfil SE Bond/ph = 0,8-1) was used as control. The teeth were assigned into two subgroups according to bonding procedure. In the first subgroup (n = 50), no pretreatment agent was applied. In the second subgroup (n = 50), etching was performed using 37% phosphoric acid for 30 s. After adhesive systems application, a nanohybrid composite resin was inserted into the enamel surface. The specimens were placed in a universal testing machine (Model 3343, Instron Corp., Canton, Mass., USA). After the testing procedure, the fractured surfaces were examined with an optical microscope at a magnification of 10× to determine failure modes. The adhesive remnant index (ARI) was used to assess the amount of adhesive left on the enamel surface. Descriptive statistics of the shear bond strength and frequency distribution of ARI scores were calculated. Enamel pretreatment with phosphoric acid significantly increased bond strength values of all the adhesives tested. No significant differences in bond strength were detected among the four different one-step self-etch adhesives with different pH. Two-step self-etch adhesive showed the highest bond strength. © 2013 John Wiley & Sons A/S.

Influence of CVD diamond tips and Er:YAG laser irradiation on bonding of different adhesive systems to dentin.

PubMed

da Silva, Melissa Aline; Di Nicolo, Rebeca; Barcellos, Daphne Camara; Batista, Graziela Ribeiro; Pucci, Cesar Rogerio; Rocha Gomes Torres, Carlos; Borges, Alessandra Bühler

2013-01-01

The aim of this study was to compare the microtensile bond strength of three adhesive systems, using different methods of dentin preparation. A hundred and eight bovine teeth were used. The dentin from buccal face was exposed and prepared with three different methods, divided in 3 groups: Group 1 (DT)- diamond tip on a high-speed handpiece; Group 2 (CVD)-CVD tip on a ultrasonic handpiece; Group 3 (LA)-Er: YAG laser. The teeth were divided into 3 subgroups, according adhesive systems used: Subgroup 1-Adper Single Bond Plus/3M ESPE (SB) total-etch adhesive; Subgroup 2-Adper Scotchbond SE/3M ESPE (AS) selfetching adhesive; Subgroup 3-Clearfil SE Bond/Kuraray (CS) selfetching adhesive. Blocks of composite (Filtek Z250-3M ESPE) 4 mm high were built up and specimens were stored in deionized water for 24 hours at 37°C. Serial mesiodistal and buccolingual cuts were made and stick-like specimens were obtained, with transversal section of 1.0 mm(2). The samples were submitted to microtensile test at 1 mm/min and load of 10 kg in a universal testing machine. Data (MPa) were subjected to ANOVA and Tukey's tests (p < 0.05). Surface treatment with Diamond or CVD tips associated with Clearfil SE Bond adhesive produced significantly lower bond strength values compared to other groups. Surface treatment with Er: YAG laser associated with Single Bond Plus or Clearfil SE Bond adhesives and surface treatment with CVD tip associated with Adper Scotchbond SE adhesive produced significantly lower bond strength values compared to surface treatment with diamond or CVD tips associated with Single Bond Plus or Adper Scotchbond SE adhesives. Interactions between laser and the CVD tip technologies and the different adhesive systems can produce a satisfactory bonding strength result, so that these associations may be beneficial and enhance the clinical outcomes.

Comparative bonding ability to dentin of a universal adhesive system and monomer conversion as functions of extended light curing times and storage.

PubMed

Sampaio, Paula Costa Pinheiro; Kruly, Paula de Castro; Ribeiro, Clara Cabral; Hilgert, Leandro Augusto; Pereira, Patrícia Nóbrega Rodrigues; Scaffa, Polliana Mendes Candia; Di Hipólito, Vinicius; D'Alpino, Paulo Henrique Perlatti; Garcia, Fernanda Cristina Pimentel

2017-11-01

The purpose of this in vitro study was to evaluate the bonding ability and monomer conversion of a universal adhesive system applied to dentin as functions of different curing times and storage. The results were compared among a variety of commercial adhesives. Flat superficial dentin surfaces were exposed on human molars and assigned into one of the following adhesives (n = 15): total-etch Adper Single Bond 2 (SB) and Optibond Solo Plus (OS), self-etch Optibond All in One (OA) and Clearfil SE Bond (CSE), and Scotchbond Universal Adhesive in self-etch mode (SU). The adhesives were applied following the manufacturers' instructions and cured for 10, 20, or 40s. Specimens were processed for the microtensile bond strength (µTBS) test in accordance with the non-trimming technique and tested after 24h and 2 years. The fractured specimens were classified under scanning electron microscopy (SEM). Infrared (IR) spectra were obtained and monomer conversion (%) was calculated by comparing the aliphatic-to-aromatic IR absorption peak ratio before and after polymerization (n=5). Data were analyzed by 2-way ANOVA/Tukey's tests (α = 0.05). At 24-h evaluation, OA and CSE presented similar bond strength means irrespective of the curing time, whereas SB and SU exhibited significantly higher means when cured for 40s as did OS when cured for 20 or 40s (p < 0.05). At 2-year evaluation, only OA exhibited significantly higher bond strength when cured for 20 and 40s (p < 0.05). When the evaluation times were compared, OA also exhibited the same bonding ability when cured for longer periods of time (20 and 40s). All of the adhesives tested exhibited significantly lower monomer conversion when photoactivated according to the manufacturers' instructions (10s). Higher monomer conversions obtained with longer light exposure allow only higher immediate bond strength for most of the adhesives tested. After 2-year storage, only the self-etching adhesive Optibond All-In-One exhibited the same bonding ability when cured for longer periods of time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanical and microbiological properties and drug release modeling of an etch-and-rinse adhesive containing copper nanoparticles.

PubMed

Gutiérrez, M F; Malaquias, P; Matos, T P; Szesz, A; Souza, S; Bermudez, J; Reis, A; Loguercio, A D; Farago, P V

2017-03-01

To evaluate the effect of addition of copper nanoparticles (CN) at different concentrations into a two-step etch-and-rinse (2-ER) adhesive on antimicrobial activity (AMA), copper release (CR), ultimate tensile strength (UTS), degree of conversion (DC), water sorption (WS), solubility (SO), as well as the immediate (IM) and 1-year resin-dentin bond strength (μTBS) and nanoleakage (NL). Seven adhesives were formulated according to the addition of CN (0, 0.0075, 0.015, 0.06, 0.1, 0.5 and 1wt%) in adhesive. The AMA was evaluated against Streptococcus mutans using agar diffusion assay. For CR, WS and SO, specimens were constructed and tested for 28 days. For UTS, specimens were tested after 24h and 28 days. For DC, specimens were constructed and tested after 24h by FTIR. After enamel removal, the ER was applied to dentin. After composite resin build-ups, specimens were sectioned to obtain resin-dentin sticks. For μTBS and NL, specimens were tested after 24h and 1-year periods. All data were submitted to statistical analysis (α=0.05). The addition of CN provided AMA to the adhesives at all concentrations. Higher CR was observed in adhesives with higher concentration of CN. UTS, DC, WS and SO were not influenced. For μTBS an increase was observed in 0.1 and 0.5% copper group. For NL, a significant decrease was observed in all groups in comparison with control group. After 1-year, no significant reductions of μTBS and no significant increases of NL were observed for copper containing adhesives compared to the control group. The addition of CN in concentrations up to 1wt% in the 2-ER adhesive may be an alternative to provide AMA and preserve the bonding to dentin, without reducing adhesives' mechanical properties evaluated. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The Effect of Deposition Conditions on Adhesion Strength of Ti and Ti6Al4V Cold Spray Splats

NASA Astrophysics Data System (ADS)

Goldbaum, Dina; Shockley, J. Michael; Chromik, Richard R.; Rezaeian, Ahmad; Yue, Stephen; Legoux, Jean-Gabriel; Irissou, Eric

2012-03-01

Cold spray is a complex process where many parameters have to be considered in order to achieve optimized material deposition and properties. In the cold spray process, deposition velocity influences the degree of material deformation and material adhesion. While most materials can be easily deposited at relatively low deposition velocity (<700 m/s), this is not the case for high yield strength materials like Ti and its alloys. In the present study, we evaluate the effects of deposition velocity, powder size, particle position in the gas jet, gas temperature, and substrate temperature on the adhesion strength of cold spayed Ti and Ti6Al4V splats. A micromechanical test technique was used to shear individual splats of Ti or Ti6Al4V and measure their adhesion strength. The splats were deposited onto Ti or Ti6Al4V substrates over a range of deposition conditions with either nitrogen or helium as the propelling gas. The splat adhesion testing coupled with microstructural characterization was used to define the strength, the type and the continuity of the bonded interface between splat and substrate material. The results demonstrated that optimization of spray conditions makes it possible to obtain splats with continuous bonding along the splat/substrate interface and measured adhesion strengths approaching the shear strength of bulk material. The parameters shown to improve the splat adhesion included the increase of the splat deposition velocity well above the critical deposition velocity of the tested material, increase in the temperature of both powder and the substrate material, decrease in the powder size, and optimization of the flow dynamics for the cold spray gun nozzle. Through comparisons to the literature, the adhesion strength of Ti splats measured with the splat adhesion technique correlated well with the cohesion strength of Ti coatings deposited under similar conditions and measured with tubular coating tensile (TCT) test.

VRPI Thermoresponsive Reversibly Attachable Patch for Temporary Intervention in Ocular Trauma

DTIC Science & Technology

2014-09-01

Polymerization (ATRP) on biocompatible substrates (e.g. parylene, polyimide , etc.). Adhesion data performed on preliminary samples under uniaxial testing...adhesion performance is completed in vitro, adhesion in vivo and biocompatibility will be assessed using a rabbit animal model. 15. SUBJECT TERMS...vitro, validate adhesive performance in vivo and perform preliminary biocompatibility assessments. 2. Keywords. sutureless wound repair

Kinetics of Pseudomonas aeruginosa adhesion to 304 and 316-L stainless steel: role of cell surface hydrophobicity.

PubMed Central

Vanhaecke, E; Remon, J P; Moors, M; Raes, F; De Rudder, D; Van Peteghem, A

1990-01-01

Fifteen different isolates of Pseudomonas aeruginosa were used to study the kinetics of adhesion to 304 and 316-L stainless steel. Stainless steel plates were incubated with approximately 1.5 X 10(7) CFU/ml in 0.01 M phosphate-buffered saline (pH 7.4). After the plates were rinsed with the buffer, the number of adhering bacteria was determined by a bioluminescence assay. Measurable adhesion, even to the electropolished surfaces, occurred within 30 s. Bacterial cell surface hydrophobicity, as determined by the bacterial adherence to hydrocarbons test and the contact angle measurement test, was the major parameter influencing the adhesion rate constant for the first 30 min of adhesion. A parabolic relationship between the CAM values and the logarithm of the adhesion rate constants (In k) was established. No correlation between either the salt aggregation or the improved salt aggregation values and the bacterial adhesion rate constants could be found. Since there was no significant correlation between the bacterial electrophoretic mobilities and the In k values, the bacterial cell surface charge seemed of minor importance in the process of adhesion of P. aeruginosa to 304 and 316-L stainless steel. PMID:2107796

Develop, demonstrate, and verify large area composite structural bonding with polyimide adhesives. [adhesively bonding graphite-polyimide structures

NASA Technical Reports Server (NTRS)

Bhombal, B. D.; Wykes, D. H.; Hong, K. C.; Stenersen, A. A.

1982-01-01

The technology required to produce graphite-polyimide structural components with operational capability at 598 K (600 F) is considered. A series of polyimide adhesives was screened for mechanical and physical properties and processibility in fabricating large midplane bonded panels and honeycomb sandwich panels in an effort to fabricate a structural test component of the space shuttle aft body flap. From 41 formulations, LaRC-13, FM34B-18, and a modified LaRC-13 adhesive were selected for further evaluation. The LaRC-13 adhesive was rated as the best of the three adhesives in terms of availability, cost, processibility, properties, and ability to produce void fee large area (12" x 12") midplane bonds. Surface treatments and primers for the adhesives were evaluated and processes were developed for the fabrication of honeycomb sandwich panels of very good quality which was evidenced by rupture in the honeycomb core rather than in the facesheet bands on flatwise tensile strength testing. The fabrication of the adhesively bonded honeycomb sandwich cover panels, ribs, and leading edge covers of Celion graphite/LARC-160 polyimide laminates is described.

Combinatorial materials research applied to the development of new surface coatings VII: An automated system for adhesion testing

NASA Astrophysics Data System (ADS)

Chisholm, Bret J.; Webster, Dean C.; Bennett, James C.; Berry, Missy; Christianson, David; Kim, Jongsoo; Mayo, Bret; Gubbins, Nathan

2007-07-01

An automated, high-throughput adhesion workflow that enables pseudobarnacle adhesion and coating/substrate adhesion to be measured on coating patches arranged in an array format on 4×8in.2 panels was developed. The adhesion workflow consists of the following process steps: (1) application of an adhesive to the coating array; (2) insertion of panels into a clamping device; (3) insertion of aluminum studs into the clamping device and onto coating surfaces, aligned with the adhesive; (4) curing of the adhesive; and (5) automated removal of the aluminum studs. Validation experiments comparing data generated using the automated, high-throughput workflow to data obtained using conventional, manual methods showed that the automated system allows for accurate ranking of relative coating adhesion performance.

Mass spectrometric measurements of driver gas arrival in the T4 free-piston shock-tunnel

NASA Astrophysics Data System (ADS)

Boyce, R. R.; Takahashi, M.; Stalker, R. J.

2005-12-01

Available test time is an important issue for ground-based flow research, particularly for impulse facilities such as shock tunnels, where test times of the order of several ms are typical. The early contamination of the test flow by the driver gas in such tunnels restricts the test time. This paper reports measurements of the driver gas arrival time in the test section of the T4 free-piston shock-tunnel over the total enthalpy range 3 17 MJ/kg, using a time-of-flight mass spectrometer. The results confirm measurements made by previous investigators using a choked duct driver gas detector at these conditions, and extend the range of previous mass spectrometer measurements to that of 3 20 MJ/kg. Comparisons of the contamination behaviour of various piston-driven reflected shock tunnels are also made.

Stochastic shock response spectrum decomposition method based on probabilistic definitions of temporal peak acceleration, spectral energy, and phase lag distributions of mechanical impact pyrotechnic shock test data

NASA Astrophysics Data System (ADS)

Hwang, James Ho-Jin; Duran, Adam

2016-08-01

Most of the times pyrotechnic shock design and test requirements for space systems are provided in Shock Response Spectrum (SRS) without the input time history. Since the SRS does not describe the input or the environment, a decomposition method is used to obtain the source time history. The main objective of this paper is to develop a decomposition method producing input time histories that can satisfy the SRS requirement based on the pyrotechnic shock test data measured from a mechanical impact test apparatus. At the heart of this decomposition method is the statistical representation of the pyrotechnic shock test data measured from the MIT Lincoln Laboratory (LL) designed Universal Pyrotechnic Shock Simulator (UPSS). Each pyrotechnic shock test data measured at the interface of a test unit has been analyzed to produce the temporal peak acceleration, Root Mean Square (RMS) acceleration, and the phase lag at each band center frequency. Maximum SRS of each filtered time history has been calculated to produce a relationship between the input and the response. Two new definitions are proposed as a result. The Peak Ratio (PR) is defined as the ratio between the maximum SRS and the temporal peak acceleration at each band center frequency. The ratio between the maximum SRS and the RMS acceleration is defined as the Energy Ratio (ER) at each band center frequency. Phase lag is estimated based on the time delay between the temporal peak acceleration at each band center frequency and the peak acceleration at the lowest band center frequency. This stochastic process has been applied to more than one hundred pyrotechnic shock test data to produce probabilistic definitions of the PR, ER, and the phase lag. The SRS is decomposed at each band center frequency using damped sinusoids with the PR and the decays obtained by matching the ER of the damped sinusoids to the ER of the test data. The final step in this stochastic SRS decomposition process is the Monte Carlo (MC) simulation. The MC simulation identifies combinations of the PR and decays that can meet the SRS requirement at each band center frequency. Decomposed input time histories are produced by summing the converged damped sinusoids with the MC simulation of the phase lag distribution.

Adhesives: Test Method, Group Assignment, and Categorization Guide for High-Loading-Rate Applications Preparation and Testing of Single Lap Joints (Ver. 2.2, Unlimited)

DTIC Science & Technology

2016-04-01

Gerard Chaney, and Charles Pergantis Weapons and Materials Research Directorate, ARL Coatings, Corrosion, and Engineered Polymers Branch (CCEPB...SUBJECT TERMS single lap joint, adhesive, sample preparation, testing, database, metadata, material pedigree, ISO 16. SECURITY CLASSIFICATION OF: 17...temperature/water immersion conditioning test for lap-joint test specimens using the test tubes and convection oven method

The differential effects of heat-shocking on the viability of spores from Bacillus anthracis, Bacillus subtilis, and Clostridium sporogenes after treatment with peracetic acid- and glutaraldehyde-based disinfectants

PubMed Central

March, Jordon K; Pratt, Michael D; Lowe, Chinn-Woan; Cohen, Marissa N; Satterfield, Benjamin A; Schaalje, Bruce; O'Neill, Kim L; Robison, Richard A

2015-01-01

This study investigated (1) the susceptibility of Bacillus anthracis (Ames strain), Bacillus subtilis (ATCC 19659), and Clostridium sporogenes (ATCC 3584) spores to commercially available peracetic acid (PAA)- and glutaraldehyde (GA)-based disinfectants, (2) the effects that heat-shocking spores after treatment with these disinfectants has on spore recovery, and (3) the timing of heat-shocking after disinfectant treatment that promotes the optimal recovery of spores deposited on carriers. Suspension tests were used to obtain inactivation kinetics for the disinfectants against three spore types. The effects of heat-shocking spores after disinfectant treatment were also determined. Generalized linear mixed models were used to estimate 6-log reduction times for each spore type, disinfectant, and heat treatment combination. Reduction times were compared statistically using the delta method. Carrier tests were performed according to AOAC Official Method 966.04 and a modified version that employed immediate heat-shocking after disinfectant treatment. Carrier test results were analyzed using Fisher's exact test. PAA-based disinfectants had significantly shorter 6-log reduction times than the GA-based disinfectant. Heat-shocking B. anthracis spores after PAA treatment resulted in significantly shorter 6-log reduction times. Conversely, heat-shocking B. subtilis spores after PAA treatment resulted in significantly longer 6-log reduction times. Significant interactions were also observed between spore type, disinfectant, and heat treatment combinations. Immediately heat-shocking spore carriers after disinfectant treatment produced greater spore recovery. Sporicidal activities of disinfectants were not consistent across spore species. The effects of heat-shocking spores after disinfectant treatment were dependent on both disinfectant and spore species. Caution must be used when extrapolating sporicidal data of disinfectants from one spore species to another. Heat-shocking provides a more accurate picture of spore survival for only some disinfectant/spore combinations. Collaborative studies should be conducted to further examine a revision of AOAC Official Method 966.04 relative to heat-shocking. PMID:26185111

System integration and demonstration of adhesive bonded high temperature aluminum alloys for aerospace structure, phase 2

NASA Technical Reports Server (NTRS)

Falcone, Anthony; Laakso, John H.

1993-01-01

Adhesive bonding materials and processes were evaluated for assembly of future high-temperature aluminum alloy structural components such as may be used in high-speed civil transport aircraft and space launch vehicles. A number of candidate high-temperature adhesives were selected and screening tests were conducted using single lap shear specimens. The selected adhesives were then used to bond sandwich (titanium core) test specimens, adhesive toughness test specimens, and isothermally aged lap shear specimens. Moderate-to-high lap shear strengths were obtained from bonded high-temperature aluminum and silicon carbide particulate-reinforced (SiC(sub p)) aluminum specimens. Shear strengths typically exceeded 3500 to 4000 lb/in(sup 2) and flatwise tensile strengths exceeded 750 lb/in(sup 2) even at elevated temperatures (300 F) using a bismaleimide adhesive. All faceskin-to-core bonds displayed excellent tear strength. The existing production phosphoric acid anodize surface preparation process developed at Boeing was used, and gave good performance with all of the aluminum and silicon carbide particulate-reinforced aluminum alloys investigated. The results of this program support using bonded assemblies of high-temperature aluminum components in applications where bonding is often used (e.g., secondary structures and tear stoppers).

Zn-doped etch-and-rinse model dentin adhesives: Dentin bond integrity, biocompatibility, and properties.

PubMed

Barcellos, Daphne Câmara; Fonseca, Beatriz Maria; Pucci, César Rogério; Cavalcanti, Bruno das Neves; Persici, Erasmo De Souza; Gonçalves, Sérgio Eduardo de Paiva

2016-07-01

This study assessed a 6 month resin/dentin bond's durability and cytotoxic effect of Zn-doped model dentin adhesives. The mechanical and physicochemical properties were also tested. A model etch-and-rinse single-bottle adhesive was formulated (55wt.% Bis-GMA, 45wt.% HEMA, 0.5wt.% CQ, 0.5wt.% DMAEMA) and Zinc methacrylate (Zn-Mt) or ZnO nanoparticles (ZnOn) were added to the model's adhesive, resulting in three groups: Group Control (control model adhesive); Group Zn-Mt (1wt.% Zn-Mt incorporated to adhesive) and Group ZnOn (1wt.% ZnOn incorporated to adhesive). The microtensile bond strength (mTBS) was assessed after 24h or 6 months in water storage. Mechanical properties (diametral tensile strength/DTS, flexural strength/FS, flexural modulus/FM, resilience modulus/RM, and compressive strength/CS) and physicochemical properties (polymerization shrinkage/PS, contact angle/CA, water sorption/WS, and water solubility/WS) were also tested. Cytotoxicity was evaluated with SRB biochemical assay. No significant difference in the DTS, FS, FM, CS, CA, WS, and WS were found when 1% of ZnOn or Zn-Mt was added to the model dentin adhesive. Group Zn-Mt decreased the RM of adhesive. Groups Zn-Mt and ZnOn decreased the PS of adhesives. Group ZnOn reduced the cytotoxicity of adhesive. Group ZnOn preserved mTBS after 6 months storage without degradation areas as seen by SEM analysis. The 1wt.% ZnOn may preserve the integrity of the hybrid layer and may reduce cytotoxicity and polymerization shrinkage of model dentin adhesive. The addition of Zn-Mt to the adhesive had no beneficial effects. Copyright © 2016 The Academy of Dental Materials. All rights reserved.

On the role of covarying functions in stimulus class formation and transfer of function.

PubMed Central

Markham, Rebecca G; Markham, Michael R

2002-01-01

This experiment investigated whether directly trained covarying functions are necessary for stimulus class formation and transfer of function in humans. Initial class training was designed to establish two respondent-based stimulus classes by pairing two visual stimuli with shock and two other visual stimuli with no shock. Next, two operant discrimination functions were trained to one stimulus of each putative class. The no-shock group received the same training and testing in all phases, except no stimuli were ever paired with shock. The data indicated that skin conductance response conditioning did not occur for the shock groups or for the no-shock group. Tests showed transfer of the established discriminative functions, however, only for the shock groups, indicating the formation of two stimulus classes only for those participants who received respondent class training. The results suggest that transfer of function does not depend on first covarying the stimulus class functions. PMID:12507017

Cognitive Function and Heat Shock Protein 70 in Children With Temporal Lobe Epilepsy.

PubMed

Oraby, Azza M; Raouf, Ehab R Abdol; El-Saied, Mostafa M; Abou-Khadra, Maha K; Helal, Suzette I; Hashish, Adel F

2017-01-01

We conducted the present study to examine cognitive function and serum heat shock protein 70 levels among children with temporal lobe epilepsy. The Stanford-Binet Intelligence Test was carried out to examine cognitive function in 30 children with temporal lobe epilepsy and 30 controls. Serum heat shock protein 70 levels were determined with an enzyme-linked immunosorbent assay. The epilepsy group had significantly lower cognitive function testing scores and significantly higher serum heat shock protein 70 levels than the control group; there were significant negative correlations between serum heat shock protein 70 levels and short-term memory and composite scores. Children with uncontrolled seizures had significantly lower verbal reasoning scores and significantly higher serum heat shock protein 70 levels than children with controlled seizures. Children with temporal lobe epilepsy have cognitive dysfunction and elevated levels of serum heat shock protein 70, which may be considered a stress biomarker.

Shock absorbency of factors in the shoe/heel interaction--with special focus on role of the heel pad.

PubMed

Jørgensen, U; Bojsen-Møller, F

1989-06-01

The heel pad acts as a shock absorber in walking and in heel-strike running. In some patients, a reduction of its shock-absorbing capacity has been connected to the development of overuse injuries. In this article, the shock absorption of the heel pad as well as external shock absorbers are studied. Individual variation and the effect of trauma and confinement on the heel pad were specifically investigated. Drop tests, imitating heel impacts, were performed on a force plate. The test specimens were cadaver heel pads (n = 10); the shoe sole component consisted of ethyl vinyl acetate (EVA) foam and Sorbothane inserts. The shock absorption was significantly greater in the heel pad than in the external shock absorbers. The mean heel pad shock absorption was 1.1 times for EVA foam and 2.1 times for Sorbothane. The shock absorption varied by as much as 100% between heel pads. Trauma caused a decrease in the heel pad shock absorbency (24%), whereas heel pad confinement increased the shock absorbency (49% in traumatized heel pads and 29.5% in nontraumatized heel pads). These findings provide a biomechanical rationale for the clinical observations of a correlation between heel pad shock absorbency loss and heel strike-dependent overuse injuries. To increase shock absorbency, confinement of the heel pad should be attempted in vivo.

Intraoperative Defibrillation Testing of Subcutaneous Implantable Cardioverter-Defibrillator Systems-A Simple Issue?

PubMed

Frommeyer, Gerrit; Zumhagen, Sven; Dechering, Dirk G; Larbig, Robert; Bettin, Markus; Löher, Andreas; Köbe, Julia; Reinke, Florian; Eckardt, Lars

2016-03-15

The results of the recently published randomized SIMPLE trial question the role of routine intraoperative defibrillation testing. However, testing is still recommended during implantation of the entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) system. To address the question of whether defibrillation testing in S-ICD systems is still necessary, we analyzed the data of a large, standard-of-care prospective single-center S-ICD registry. In the present study, 102 consecutive patients received an S-ICD for primary (n=50) or secondary prevention (n=52). Defibrillation testing was performed in all except 4 patients. In 74 (75%; 95% CI 0.66-0.83) of 98 patients, ventricular fibrillation was effectively terminated by the first programmed internal shock. In 24 (25%; 95% CI 0.22-0.44) of 98 patients, the first internal shock was ineffective and further internal or external shock deliveries were required. In these patients, programming to reversed shock polarity (n=14) or repositioning of the sensing lead (n=1) or the pulse generator (n=5) led to successful defibrillation. In 4 patients, a safety margin of <10 J was not attained. Nevertheless, in these 4 patients, ventricular arrhythmias were effectively terminated with an internal 80-J shock. Although it has been shown that defibrillation testing is not necessary in transvenous ICD systems, it seems particular important for S-ICD systems, because in nearly 25% of the cases the primary intraoperative test was not successful. In most cases, a successful defibrillation could be achieved by changing shock polarity or by optimizing the shock vector caused by the pulse generator or lead repositioning. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Potential probiotic characteristics of Lactobacillus and Enterococcus strains isolated from traditional dadih fermented milk against pathogen intestinal colonization.

PubMed

Collado, M Carmen; Surono, Ingrid S; Meriluoto, Jussi; Salminen, Seppo

2007-03-01

Traditional fermented buffalo milk in Indonesia (dadih) has been believed to have a beneficial impact on human health, which could be related to the properties of the lactic acid bacteria (LAB) involved in its fermentation process. In previous studies, it was discovered that strains of dadih lactic isolates possessed some beneficial properties in vitro. In the present study, the adhesion capacity of specific LAB isolates from dadih to intestinal mucus was analyzed. Further, the ability to inhibit model human pathogens and displace them from mucus was assessed. The adhesion of tested LAB strains was strain-dependent and varied from 1.4 to 9.8%. The most adhesive Lactobacillus plantarum strain was IS-10506, with 9.8% adhesion. The competition assay between dadih LAB isolates and pathogens showed that a 2-h preincubation with L. plantarum at 37 degrees C significantly reduced pathogen adhesion to mucus. All tested LAB strains displaced and inhibited pathogen adhesion, but the results were strain-specific and dependent on time and pathogen strains. In general, L. plantarum IS-10506 showed the best ability against pathogen adhesion.

Influence of Test Section Geometry on the Blast Environment in an Explosively Driven Conical Shock Tube

DTIC Science & Technology

2018-03-30

ARL-TR-8335•MAR 2018 US Army Research Laboratory Influence of Test Section Geometry on theBlast Environment in an Explosively DrivenConical Shock...ARL-TR-8335•MAR 2018 US Army Research Laboratory Influence of Test Section Geometry on theBlast Environment in an Explosively DrivenConical Shock...Tube by Joel B Stewart Weapons and Materials Research Directorate, ARL Approved for public release; distribution is unlimited. REPORT DOCUMENTATION

Comparison of shear bond strength of self-etch and self-adhesive cements bonded to lithium disilicate, enamel and dentin.

PubMed

Naranjo, Jennifer; Ali, Mohsin; Belles, Donald

2015-11-01

Comparison of shear bond strength of self-etch and self-adhesive cements bonded to lithium disilicate, enamel and dentin. With several self-adhesive resin cements currently available, there is confusion about which product and technique is optimal for bonding ceramic restorations to teeth. The objective of this study was to compare the shear bond strength of lithium disilicate cemented to enamel and dentin using 5 adhesive cements. 100 lithium disilicate rods were pretreated with 5% hydrofluoric acid, silane, and cemented to 50 enamel and 50 dentin surfaces using five test cements: Variolink II (etch-and-rinse) control group, Clearfil Esthetic (two step self-etch), RelyX Unicem, SpeedCEM, and BifixSE (self-adhesive). All specimens were stored (37 degrees C, 100% humidity) for 24 hours before testing their shear bond strength using a universal testing machine (Instron). Debonded surfaces were observed under a low-power microscope to assess the location and type of failure. The highest bond strength for both enamel and dentin were recorded for Variolink II, 15.1MPa and 20.4MPa respectively, and the lowest were recorded for BifixSE, 0.6MPa and 0.9MPa respectively. Generally, higher bond strengths were found for dentin (7.4MPa) than enamel (5.3MPa). Tukey's post hoc test showed no significant difference between Clearfil Esthetic and SpeedCem (p = 0.059), Unicem and SpeedCem (p = 0.88), and Unicem and BifixSE (p = 0.092). All cements bonded better to lithium disilicate than to enamel or dentin, as all bond failures occurred at the tooth/adhesive interface except for Variolink II. Bond strengths recorded for self-adhesive cements were very low compared to the control "etch and rinse" and self-etch systems. Further improvements are apparently needed in self-adhesive cements for them to replace multistep adhesive systems. The use of conventional etch and rinse cements such as Veriolink II should be preferred for cementing all ceramic restorations over self-adhesive cements until the bond strengths are improved.

Bio-based wood adhesives--preparation, characterization, and testing

USDA-ARS?s Scientific Manuscript database

Adhesive bonding plays an increasing role in the forest product industry and is a key factor for efficiently utilizing timber and other lignocellulosic resources. As synthetic wood adhesives are mostly derived from depleting petrochemical resources and have resulted in increasing environmental conce...

Design guidelines for use of adhesives and organic coatings in hybrid microcircuits

NASA Technical Reports Server (NTRS)

Caruso, S. V.; Licari, J. J.; Perkins, K. L.; Schramm, W. A.

1974-01-01

A study was conducted to investigate the reliability of organic adhesives in hybrid microcircuits. The objectives were twofold: (1) to identify and investigate problem areas that could result from the use of organic adhesives and (2) to develop evaluation tests to quantify the extent to which these problems occur for commercially available adhesives. Efforts were focused on electrically conductive adhesives. Also, a study was made to evaluate selected organic coatings for contamination protection for hybrid microcircuits.

Experimental Investigation of Shock-Cell Noise Reduction for Single Stream Nozzles in Simulated Flight

NASA Technical Reports Server (NTRS)

Yamamoto, K.; Brausch, J. F.; Balsa, T. F.; Janardan, B. A.; Knott, P. R.

1984-01-01

Seven single stream model nozzles were tested in the Anechoic Free-Jet Acoustic Test Facility to evaluate the effectiveness of convergent divergent (C-D) flowpaths in the reduction of shock-cell noise under both static and mulated flight conditions. The test nozzles included a baseline convergent circular nozzle, a C-D circular nozzle, a convergent annular plug nozzle, a C-D annular plug nozzle, a convergent multi-element suppressor plug nozzle, and a C-D multi-element suppressor plug nozzle. Diagnostic flow visualization with a shadowgraph and aerodynamic plume measurements with a laser velocimeter were performed with the test nozzles. A theory of shock-cell noise for annular plug nozzles with shock-cells in the vicinity of the plug was developed. The benefit of these C-D nozzles was observed over a broad range of pressure ratiosin the vicinity of their design conditions. At the C-D design condition, the C-D annual nozzle was found to be free of shock-cells on the plug.

Hemorrhagic shock caused by sigmoid colon volvulus: An autopsy case

PubMed Central

Sato, Hiroaki; Tanaka, Toshiko; Tanaka, Noriyuki

2011-01-01

Summary Background Many reports have described sigmoid volvulus, but fatal hemorrhagic shock resulting from the rupture of the involved artery has not been reported as a complication of a sigmoid volvulus. Case Report A 71-year-old man with slight abdominal pain and obstipation in hypotension died at a nursing home without seeing a doctor. At autopsy, a mesenteric hematoma and hemoperitoneum was observed with approximately 1,000 ml of blood in the abdominal cavity. The sigmoid colon and the mesentery were twisted at an adhesion site of a sigmoid colon to an ileum, and the condition was determined to be a sigmoid volvulus. The volvulus was observed to be loosened. The inferior mesenteric artery was incorporated into the twisted part of the mesentery, but remained patent, and its peripheral branch near the hematoma ruptured without histological abnormality. Conclusions Since ischemic-reperfusion injury occurs with a temporarily occluded artery, the acute re-loading of blood flow may injure the distal vessels after spontaneous reduction of compression by loosening of the volvulus. PMID:22129905

Application of Surface Protective Coating to Enhance Environment-Withstanding Property of the MEMS 2D Wind Direction and Wind Speed Sensor.

PubMed

Shin, Kyu-Sik; Lee, Dae-Sung; Song, Sang-Woo; Jung, Jae Pil

2017-09-19

In this study, a microelectromechanical system (MEMS) two-dimensional (2D) wind direction and wind speed sensor consisting of a square heating source and four thermopiles was manufactured using the heat detection method. The heating source and thermopiles of the manufactured sensor must be exposed to air to detect wind speed and wind direction. Therefore, there are concerns that the sensor could be contaminated by deposition or adhesion of dust, sandy dust, snow, rain, and so forth, in the air, and that the membrane may be damaged by physical shock. Hence, there was a need to protect the heating source, thermopiles, and the membrane from environmental and physical shock. The upper protective coating to protect both the heating source and thermopiles and the lower protective coating to protect the membrane were formed by using high-molecular substances such as SU-8, Teflon and polyimide (PI). The sensor characteristics with the applied protective coatings were evaluated.

The link between the peel force of adhesive dressings and subjective discomfort in volunteer subjects.

PubMed

Dykes, P J; Heggie, R

2003-07-01

The study compared the level of discomfort experienced by healthy volunteers on the removal of a range of adhesive wounds. This was an open, within subject comparative study of six adhesive dressings in 24 volunteers. The test site was the lower back. Allocation of test materials to the test sites was randomised. The peel force of removal was recorded after 24 hours of application using a device that removed the dressing at a constant speed and angle to the skin surface. The discomfort experienced at each removal was assessed by the subjects themselves using an electronic visual analogue scale. Overall, Mepilex Border was given a significantly lower discomfort score (p < or = 0.01) by the subjects than the other dressings. There were no clear differences between the five other products tested. Tielle and Allevyn Adhesive had significantly higher (p < or = 0.05) peel force than the other products. Mepilex Border caused less discomfort on removal than Duoderm Extra Thin, Biatain and Versiva, even though the peel force was similar. Tielle and Allevyn had higher peel force, but the levels of discomfort were not significantly higher for these products. It may be that the level of discomfort experienced by subjects on removal of an adhesive dressing is not entirely dependent on the peel force and that other aspects of the interaction of the skin surface and adhesive play a role.

In vitro microtensile bond strength of four adhesives tested at the gingival and pulpal walls of class II restorations

PubMed Central

Purk, John H.; Healy, Matthew; Dusevich, Vladimir; Glaros, Alan; Eick, J. David

2007-01-01

Background The authors compared the microtensile bond strength of teeth restored with four adhesives at the gingival and pulpal cavity walls of Class II resin-based composite restorations. Methods Five pairs of extracted third molars received two Class II preparations/restorations in each tooth. The authors randomly assigned each preparation to one of four adhesive groups: Adper Scotchbond Multipurpose Dental Adhesive (SBMP) (3M ESPE, St. Paul, Minn.), Clearfil SE Bond (CFSE) (Kuraray America, New York City), Prime & Bond NT (PBNT) (Dentsply Caulk, Milford, Del.) and PQ1 (Ultradent, South Jordan, Utah). They restored the teeth and obtained microtensile specimens from each cavity wall. Specimens were tested on a testing machine until they failed. Results The mean (± standard deviation) bond strengths (in megapascals) were as follows: SBMP (pulpal), 36.4 (17.2); SBMP (gingival), 29.7 (15.3); CFSE (pulpal), 50.8 (13.6); CFSE (gingival), 50.2 (14.0); PBNT (pulpal), 38.3 (19.2); PBNT (gingival), 38.9 (17.7); PQ1 (pulpal), 58.7 (8.7); and PQ1 (gingival), 54.5 (18.5). A two-way analysis of variance found an adhesive effect (P < .001) but no location effect (P > .05). Conclusions PQ1 and CFSE performed the best. The results showed no significant difference in microtensile bond strength at the gingival wall versus the pulpal wall. Clinical Implications Under in vitro conditions, a total-etch ethanol-based adhesive (PQ1) failed cohesively more often than did the other adhesives tested. PMID:17012721

Development of combinatorial chemistry methods for coatings: high-throughput adhesion evaluation and scale-up of combinatorial leads.

PubMed

Potyrailo, Radislav A; Chisholm, Bret J; Morris, William G; Cawse, James N; Flanagan, William P; Hassib, Lamyaa; Molaison, Chris A; Ezbiansky, Karin; Medford, George; Reitz, Hariklia

2003-01-01

Coupling of combinatorial chemistry methods with high-throughput (HT) performance testing and measurements of resulting properties has provided a powerful set of tools for the 10-fold accelerated discovery of new high-performance coating materials for automotive applications. Our approach replaces labor-intensive steps with automated systems for evaluation of adhesion of 8 x 6 arrays of coating elements that are discretely deposited on a single 9 x 12 cm plastic substrate. Performance of coatings is evaluated with respect to their resistance to adhesion loss, because this parameter is one of the primary considerations in end-use automotive applications. Our HT adhesion evaluation provides previously unavailable capabilities of high speed and reproducibility of testing by using a robotic automation, an expanded range of types of tested coatings by using the coating tagging strategy, and an improved quantitation by using high signal-to-noise automatic imaging. Upon testing, the coatings undergo changes that are impossible to quantitatively predict using existing knowledge. Using our HT methodology, we have developed several coatings leads. These HT screening results for the best coating compositions have been validated on the traditional scales of coating formulation and adhesion loss testing. These validation results have confirmed the superb performance of combinatorially developed coatings over conventional coatings on the traditional scale.

Effects of hydrogen sulfide on hemodynamics, inflammatory response and oxidative stress during resuscitated hemorrhagic shock in rats

PubMed Central

2010-01-01

Introduction Hydrogen sulfide (H2S) has been shown to improve survival in rodent models of lethal hemorrhage. Conversely, other authors have reported that inhibition of endogenous H2S production improves hemodynamics and reduces organ injury after hemorrhagic shock. Since all of these data originate from unresuscitated models and/or the use of a pre-treatment design, we therefore tested the hypothesis that the H2S donor, sodium hydrosulfide (NaHS), may improve hemodynamics in resuscitated hemorrhagic shock and attenuate oxidative and nitrosative stresses. Methods Thirty-two rats were mechanically ventilated and instrumented to measure mean arterial pressure (MAP) and carotid blood flow (CBF). Animals were bled during 60 minutes in order to maintain MAP at 40 ± 2 mm Hg. Ten minutes prior to retransfusion of shed blood, rats randomly received either an intravenous bolus of NaHS (0.2 mg/kg) or vehicle (0.9% NaCl). At the end of the experiment (T = 300 minutes), blood, aorta and heart were harvested for Western blot (inductible Nitric Oxyde Synthase (iNOS), Nuclear factor-κB (NF-κB), phosphorylated Inhibitor κB (P-IκB), Inter-Cellular Adhesion Molecule (I-CAM), Heme oxygenase 1(HO-1), Heme oxygenase 2(HO-2), as well as nuclear respiratory factor 2 (Nrf2)). Nitric oxide (NO) and superoxide anion (O2-) were also measured by electron paramagnetic resonance. Results At the end of the experiment, control rats exhibited a decrease in MAP which was attenuated by NaHS (65 ± 32 versus 101 ± 17 mmHg, P < 0.05). CBF was better maintained in NaHS-treated rats (1.9 ± 1.6 versus 4.4 ± 1.9 ml/minute P < 0.05). NaHS significantly limited shock-induced metabolic acidosis. NaHS also prevented iNOS expression and NO production in the heart and aorta while significantly reducing NF-kB, P-IκB and I-CAM in the aorta. Compared to the control group, NaHS significantly increased Nrf2, HO-1 and HO-2 and limited O2- release in both aorta and heart (P < 0.05). Conclusions NaHS is protective against the effects of ischemia reperfusion induced by controlled hemorrhage in rats. NaHS also improves hemodynamics in the early resuscitation phase after hemorrhagic shock, most likely as a result of attenuated oxidative stress. The use of NaHS hence appears promising in limiting the consequences of ischemia reperfusion (IR). PMID:20836847

Impact of bracket displacement or rotation during bonding and time of removal of excess adhesive on the bracket-enamel bond strength.

PubMed

Oliveira, Adauê S; Barwaldt, Caroline K; Bublitz, Luana S; Moraes, Rafael R

2014-06-01

This study investigated the the influence of bracket displacement or rotation during fixation and the time of excess adhesive removal from around the bracket on bond strength to enamel. Stainless steel brackets were bonded to the buccal faces of bovine incisors using Transbond XT® adhesive resin. The teeth were divided into five groups (n = 20). In the control group, no displacement or rotation of the bracket was carried out. In the Displac-A group, excess adhesive was removed after the bracket was displaced 2 mm incisally. In the B-Displac group, excess adhesive was removed before the bracket was displaced incisally. In the Rotat-A group, excess adhesive was removed after the bracket was rotated 45°. In the B-Rotat group, excess adhesive was removed before the bracket was rotated. Photoactivation was carried out on the lateral sides of the bracket. A shear test was conducted 10 min after fixation using a knife-edged chisel. Bond strength data were analysed using ANOVA and Fisher's test (5%). The adhesive remnant index (ARI) was scored under magnification. ARI data were analysed using the Kruskal-Wallis test (5%). No significant differences were detected among the Control, Displac-A, Rotat-A and B-Rotat groups. The B-Displac group showed lower bond strength than all of the other groups, except Displac-A. No significant differences were observed in ARI scores across groups. Displacements of the brackets during fixation did not seem to affect the enamel bond strength when excess adhesive is removed after the final positioning of the bracket. © 2014 British Orthodontic Society.

Comparison of shear bond strength of universal adhesives on etched and nonetched enamel.

PubMed

Beltrami, Riccardo; Chiesa, Marco; Scribante, Andrea; Allegretti, Jessica; Poggio, Claudio

2016-04-06

The purpose of this study was to evaluate the effect of surface pretreatment with 37% phosphoric acid on the enamel bond strength of different universal adhesives. One hundred and sixty bovine permanent mandibular incisors freshly extracted were used as a substitute for human teeth. The materials tested in this study included 6 universal adhesives, and 2 self-etch adhesives as control. The teeth were assigned into 2 groups: In the first group, etching was performed using 37% phosphoric acid for 30 seconds. In the second group, no pretreatment agent was applied. After adhesive application, a nanohybrid composite resin was inserted into the enamel surface by packing the material into cylindrical-shaped plastic matrices. After storing, the specimens were placed in a universal testing machine. The normality of the data was calculated using the Kolmogorov-Smirnov test. Analysis of variance (ANOVA) was applied to determine whether significant differences in debond strength values existed among the various groups. Groups with phosphoric acid pretreatment showed significantly higher shear bond strength values than groups with no enamel pretreatment (p<0.001). No significant variation in shear strength values was detected when comparing the different adhesive systems applied onto enamel after orthophosphoric acid application (p>0.05). All adhesives provide similar bond strength values when enamel pretreatment is applied even if compositions are different. Bond strength values are lower than promised by manufacturers.

Effect of oxiplex* films (PEO/CMC) on adhesion formation and reformation in rabbit models and on peritoneal infection in a rat model.

PubMed

Rodgers, K E; Schwartz, H E; Roda, N; Thornton, M; Kobak, W; diZerega, G S

2000-04-01

To assess the efficacy of Oxiplex (FzioMed, Inc., San Luis Obispo, CA) barriers. Film of polyethylene oxide and carboxymethylcellulose (Oxiplex) were tested for strength and tissue adherence. Films were selected for evaluation in models for biocompatability and adherence. Three films were selected for evaluation in efficacy studies, and one was evaluated for effects on bacterial peritonitis. Handling characteristics of Oxiplex film were evaluated via laparoscopy. University laboratory. Rabbits, rats, pigs. Placement of Oxiplex prototypes at the site of injury. Mechanical properties, biocompatibility, tissue adherence, adhesion development, infection potentiation, and device handling. Mechanical tests indicated that tensile strength and elongation were inversely correlated. All films tested had excellent tissue adherence properties. Selected films, based on residence time and biocompatibility, prevented adhesion formation in all animals and were highly efficacious in preventing adhesion reformation. The optimal Oxiplex prototype prevented adhesion reformation in 91% of the animals. This Oxiplex film, dyed to allow visualization, prevented adhesion reformation and did not affect bacterial peritonitis. In a laparoscopic model, the Oxiplex film, delivered in FilmSert forceps, via a 5.0-mm trocar, rapidly unfurled and could be easily applied to tissue with strong adherence. These data show development of an adhesion prevention material that is tissue adherent, can be placed via laparoscopy, and does not affect host resistance.

Tensile strength of glass fiber posts submitted to different surface treatments.

PubMed

Faria, Maria Isabel A; Gomes, Érica Alves; Messias, Danielle Cristine; Silva Filho, João Manoel; Souza Filho, Celso Bernardo; Paulino, Silvana Maria

2013-01-01

The aim of this in vitro study was to evaluate the tensile strength of glass fiber posts submitted to different surface treatments. Forty-eight maxillary canines had their crowns sectioned and root canals endodontically treated. The roots were embedded in acrylic resin and distributed into 3 groups according to the surface treatment: Group I: the posts were treated with silane agent for 30 s and adhesive; Group II: the posts were cleaned with alcohol before treatment with silane agent and adhesive; Group III: the posts were submitted to conditioning with 37% phosphoric acid for 30 s before treatment with silane agent and adhesive. Each group was divided into 2 subgroups for adhesive polymerization or not before insertion into the canal: A - adhesive was not light cured and B - adhesive was light cured. All posts were cemented with Panavia F and the samples were subjected to tensile strength test in a universal testing machine at crosshead speed of 1 mm/min. Data were submitted to one-way ANOVA and Tukey's test at 5% significance level. There was statistically significant difference (p<0.01) only between group GIII-B and groups GI-A and GI-B. No significant difference was found among the other groups (p>0.05). It was concluded that the products used for cleaning the posts influenced the retention regardless of adhesive light curing.

Properties and shock response of PMMA

NASA Astrophysics Data System (ADS)

Jordan, Jennifer L.; Casem, Daniel; Moy, Paul; Walter, Timothy

2017-01-01

Polymethylmethacrylate (PMMA) is used widely in shock experiments as a window material and in explosive characterization tests, e.g. gap tests, as a shock mitigation material. In order to simulate the complex loading present in a gap test, the constitutive response of the PMMA must be well understood. However, it is not clear what characterization must be done when the PMMA material is changed, e.g. changing supplier, and the Rohm and Haas Type II UVA PMMA, which was used for many of the calibration experiments, is no longer available. In this paper, we will present characterization results on legacy Rohm and Haas Type II UVA in comparison with a new PMMA grade proposed for use in gap tests. Planar shock experiments are performed to determine the compression and release response.

Appetitive context conditioning proactively, but transiently, interferes with expression of counterconditioned context fear

PubMed Central

Holmes, Nathan M.

2014-01-01

Four experiments used rats to study appetitive–aversive transfer. Rats trained to eat a palatable food in a distinctive context and shocked in that context ate and did not freeze when tested 1 d later but froze and did not eat when tested 14 d later. These results were associatively mediated (Experiments 1 and 2), observed when rats were or were not food deprived (Experiments 1 and 2), and were not due to latent inhibition (Experiment 3). In contrast, rats trained to eat in the context and shocked there 13 d later froze and did not eat when tested 1 d after the shocked exposure. However, rats that received an additional eating session in the context 1 d before the shocked exposure ate and did not freeze when tested 1 d after the shocked exposure (Experiment 4). The results show that appetitive conditioning transiently interferes with aversive conditioning. They are discussed in terms of a weak context–shock association becoming stronger with the lapse of time (so-called fear incubation) or of the interference by the context–food association becoming weaker with the lapse of time. PMID:25320352

Effect of a low-viscosity adhesive resin on the adhesion of metal brackets to enamel etched with hydrochloric or phosphoric acid combined with conventional adhesives.

PubMed

Yetkiner, Enver; Ozcan, Mutlu; Wegehaupt, Florian Just; Wiegand, Annette; Eden, Ece; Attin, Thomas

2013-12-01

This study investigated the effect of a low-viscosity adhesive resin (Icon) applied after either hydrochloric (HCl) or phosphoric acid (H3PO4) on the adhesion of metal brackets to enamel. Failure types were analyzed. The crowns of bovine incisors (N = 20) were sectioned mesio-distally and inciso-gingivally, then randomly assigned to 4 groups according to the following protocols to receive mandibular incisor brackets: 1) H3PO4 (37%)+TransbondXT (3M UNITEK); 2) H3PO4 (37%)+Icon+TransbondXT; 3) HCl (15%)+Icon (DMG)+TransbondXT 4) HCl (15%)+Icon+Heliobond (Ivoclar Vivadent)+TransbondXT. Specimens were stored in distilled water at 37°C for 24 h and thermocycled (5000x, 5°C to 55°C). The shear bond strength (SBS) test was performed using a universal testing machine (1 mm/min). Failure types were classified according to the Adhesive Remnant Index (ARI). Contact angles of adhesive resins were measured (n = 5 per adhesive) on ceramic surfaces. No significant difference in SBS was observed, implying no difference between combinations of adhesive resins and etching agents (p = 0.712; ANOVA). The Weibull distribution presented significantly lower Weibull modulus (m) of group 3 (m = 2.97) compared to other groups (m = 5.2 to 6.6) (p < 0.05). The mean SBS results (MPa) in descending order were as follows: group 4 (46.7 ± 10.3) > group 1 (45.4 ± 7.9) > group 2 (44.2 ± 10.6) > group 3 (42.6 ± 15.5). While in groups 1, 3, and 4 exclusively an ARI score of 0 (no adhesive left on tooth) was observed, in group 2, only one specimen demonstrated score 1 (less than half of adhesive left on tooth). Contact angle measurements were as follows: Icon (25.86 ± 3.81 degrees), Heliobond (31.98 ± 3.17 degrees), TransbondXT (35 ± 2.21 degrees). Icon can be safely used with the conventional adhesives tested on surfaces etched with either HCl or H3PO4.

Shear bond strength of a new one-bottle dentin adhesive.

PubMed

Swift, E J; Bayne, S C

1997-08-01

To test the shear bond strength of a new adhesive, 3M Single Bond, to dentin surfaces containing different degrees of moisture. Two commercially available one-bottle adhesives (Prime & Bond, One-Step) and a conventional three-step system (Scotchbond Multi-Purpose Plus) were included for comparison. 120 bovine teeth were embedded in acrylic and the labial surfaces were polished to 600 grit to create standardized dentin surfaces for testing. Resin composite was bonded to dentin using a gelatin capsule technique. Four adhesive systems were evaluated with three different degrees of surface moisture (moist, wet, and overwet). Shear bond strengths of adhesives to dentin were determined using a universal testing machine and analyzed by ANOVA and Tukey's post hoc tests. Single Bond had mean shear bond strengths of 19.2, 23.2 and 20.3 MPa to moist, wet, and overwet dentin, respectively. Bond strengths of the three-component system Scotchbond Multi-Purpose Plus ranged from 23.1 to 25.3 MPa, but were not significantly higher than the values for Single Bond. Prime & Bond had bond strengths similar to those of Single Bond, but One-Step had significantly lower bond strengths (P < 0.05) in the wet and overwet conditions.

Computations of Axisymmetric Flows in Hypersonic Shock Tubes

NASA Technical Reports Server (NTRS)

Sharma, Surendra P.; Wilson, Gregory J.

1995-01-01

A time-accurate two-dimensional fluid code is used to compute test times in shock tubes operated at supersonic speeds. Unlike previous studies, this investigation resolves the finer temporal details of the shock-tube flow by making use of modern supercomputers and state-of-the-art computational fluid dynamic solution techniques. The code, besides solving the time-dependent fluid equations, also accounts for the finite rate chemistry in the hypersonic environment. The flowfield solutions are used to estimate relevant shock-tube parameters for laminar flow, such as test times, and to predict density and velocity profiles. Boundary-layer parameters such as bar-delta(sub u), bar-delta(sup *), and bar-tau(sub w), and test time parameters such as bar-tau and particle time of flight t(sub f), are computed and compared with those evaluated by using Mirels' correlations. This article then discusses in detail the effects of flow nonuniformities on particle time-of-flight behind the normal shock and, consequently, on the interpretation of shock-tube data. This article concludes that for accurate interpretation of shock-tube data, a detailed analysis of flowfield parameters, using a computer code such as used in this study, must be performed.

A measurement system analysis with design of experiments: Investigation of the adhesion performance of a pressure sensitive adhesive with the probe tack test.

PubMed

Michaelis, Marc; Leopold, Claudia S

2015-12-30

The tack of a pressure sensitive adhesive (PSA) is not an inherent material property and strongly depends on the measurement conditions. Following the concept of a measurement system analysis (MSA), influencing factors of the probe tack test were investigated by a design of experiments (DoE) approach. A response surface design with 38 runs was built to evaluate the influence of detachment speed, dwell time, contact force, adhesive film thickness and API content on tack, determined as the maximum of the stress strain curve (σmax). It could be shown that all investigated factors have a significant effect on the response and that the DoE approach allowed to detect two-factorial interactions between the dwell time, the contact force, the adhesive film thickness and the API content. Surprisingly, it was found that tack increases with decreasing and not with increasing adhesive film thickness. Copyright © 2015. Published by Elsevier B.V.

Surface characterization and adhesion of oxygen plasma-modified LARC-TPI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, J.W.; Wightman, J.P.

1992-01-01

LARC-TPI, an aromatic thermoplastic polyimide, was exposed to an oxygen plasma as a surface pretreatment of adhesive bonding. Chemical and physical changes which occurred in the polyimide surface as a result of the plasma treatment were investigated using X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy (IR-RAS), contact angle analysis, ellipsometry and high resolution scanning electron microscopy (HR-SEM). A 180{degree} peel test with an acrylate-based pressure sensitive adhesive as a flexible adherend was utilized to study the interactions of the plasma-treated polyimide surface with other polymeric materials. The surface characterization and adhesion testing results showed that the oxygen plasma treatment, whilemore » creating a more hydrophilic, polar surface, also caused chain scission resulting in the formation of a weak boundary layer which inhibited adhesion.« less

Joint Test Protocol: Environmentally Friendly Zirconium Oxide Pretreatment Demonstration

DTIC Science & Technology

2013-12-01

coatings . Loss of paint adhesion is the primary failure mode on aluminum and steel. 3.7.3 Test Methodology The test methodology for pencil hardness...conversion pretreatment coatings . Loss of paint adhesion is the primary failure mode on aluminum and steel. 3.8.3 Test Methodology The test...SUPPLEMENTARY NOTES 14. ABSTRACT There is a need to implement innovative and cost- effective replacement technologies to address the multiple health, safety

Evaluation of high temperature structural adhesives for extended service, phase 4

NASA Technical Reports Server (NTRS)

Hendricks, C. L.; Hill, S. G.; Hale, J. N.

1985-01-01

The evaluation of three phenylquinoxaline polymers as high temperature structural adhesives is presented. These included an experimental crisskubjabke oiktner (X-PQ) and two experimental materials (PPQ-2501) and (PPQ-HC). Lap shear, crack extension, and climing drum peel specimens were fabricated from all three polymers, and tested after thermal, combined thermal/humidity, and stressed Skydrol exposure. All three polymers generally performed well as adhesives at initial test temperatures from 219K (-67 F) to 505K (450 F) and after humidity exposure. The 644K (700 F) cured test specimens exhibited superior Skydrol resistance and thermal stability at 505K (450 F) when compared to the 602K (625 F) cured test specimens.

A spatial paradigm, the allothetic place avoidance alternation task, for testing visuospatial working memory and skill learning in rats.

PubMed

Dockery, Colleen A; Wesierska, Malgorzata J

2010-08-30

We present a paradigm for assessing visuospatial working memory and skill learning in a rodent model, based on the place avoidance test. In our allothetic place avoidance alternation task (APAAT) the paradigm is comprised of minimal training sessions, tests various aspects of learning and memory and provides a rich set of parameters. A single working memory session consists of four conditions: habituation (no shock), two place avoidance training intervals (shock activated) and a retrieval test (shock inactivated). The location of the shock sector is alternated for each training day which initially requires extinction of previous representations and further working memory to achieve effective place avoidance across sessions. Visuospatial skill memory was evaluated by the shock/entrance ratio by tracking locomotor activity which is essential to execute a place avoidance strategy. For each day rats learned to avoid a new place with shock, as shown by a decreased number of entrances, and an increased time to the first entrance and maximum avoidance time. Skill learning improved according to the decreased number of shocks per entrance across conditions. These results indicate that complex cognitive functions are captured by this behavioral method. This APAAT paradigm expands and complements existing tools for studying hippocampal-prefrontal dependent functions to support development of treatment interventions. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Gap Test Calibrations and Their Scaling

NASA Astrophysics Data System (ADS)

Sandusky, Harold

2011-06-01

Common tests for measuring the threshold for shock initiation are the NOL large scale gap test (LSGT) with a 50.8-mm diameter donor/gap and the expanded large scale gap test (ELSGT) with a 95.3-mm diameter donor/gap. Despite the same specifications for the explosive donor and polymethyl methacrylate (PMMA) gap in both tests, calibration of shock pressure in the gap versus distance from the donor scales by a factor of 1.75, not the 1.875 difference in their sizes. Recently reported model calculations suggest that the scaling discrepancy results from the viscoelastic properties of PMMA in combination with different methods for obtaining shock pressure. This is supported by the consistent scaling of these donors when calibrated in water-filled aquariums. Calibrations with water gaps will be provided and compared with PMMA gaps. Scaling for other donor systems will also be provided. Shock initiation data with water gaps will be reviewed.

Uterine rupture disguised by urinary retention following a second trimester induced abortion: a case report.

PubMed

Jiang, Qiaoying; Yang, Liwei; Ashley, Charles; Medlin, Erin E; Kushner, David M; Zheng, Yanmei

2015-01-22

Uterine rupture classically presents with severe abdominal pain, loss of fetal station, vaginal bleeding, and shock. We present a case of uterine rupture presenting as significant urinary retention that occurred following a second trimester abortion induced with mifepristone and misoprostol. Uterine rupture was discovered unexpectedly on diagnostic laparoscopy. The uterine rupture was contained by dense adhesions between the omentum and bladder with the previous uterine cesarean hysterotomy scar. This case highlights the difficulties in diagnosis of abnormal placentation and an unusual presentation of uterine rupture. This case was managed successfully laparoscopically.

Influence of caries infiltrant contamination on shear bond strength of different adhesives to dentin.

PubMed

Jia, Liuhe; Stawarczyk, Bogna; Schmidlin, Patrick R; Attin, Thomas; Wiegand, Annette

2013-03-01

To analyze whether the contamination with a caries infiltrant system impairs the adhesive performance of etch-and-rinse and self-etching adhesives on dentin. Dentin contamination with the caries infiltrant system (Icon, DMG) was simulated by applying either hydrochloric acid (15 % HCl, Icon Etch, 15 s), the resin infiltrant (Icon infiltrant, 4 min), or both prior to the application of the respective adhesives (each group n = 10). In the control groups, the etch-and-rinse adhesive (Optibond FL, Kerr) and the self-etching adhesive (iBOND Self Etch, Hereaus) were applied without former contamination with the infiltrant system. Additionally, the adhesive performance of the resin infiltrant alone was tested. Shear bond strength of a nano-hybrid composite was analyzed after thermocycling (5,000×, 5-55°C) of the specimens and analyzed by ANOVA/Scheffé post hoc tests (p < 0.05) and Weibull statistics. Failure mode was inspected under a stereomicroscope at × 25 magnification. Contamination with the resin infiltrant alone did not impair shear bond strength, while contamination with hydrochloric acid or with hydrochloric acid and the resin infiltrant reduced shear bond strength (MPa) of the adhesives (Optibond FL: 20.5 ± 3.6, iBOND Self Etch: 17.9 ± 2.6) significantly. Hydrochloric acid contamination increased the number of adhesive failures. The adhesive performance of the caries infiltrant system alone was insufficient. The contamination with the caries infiltrant system impaired the shear bond strength of conventional dental adhesives. Contamination of the caries infiltrant system on dentin should be avoided due to the detrimental effect of hydrochloric acid etching.

Comparison between universal adhesives and two-step self-etch adhesives in terms of dentin bond fatigue durability in self-etch mode.

PubMed

Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

2017-06-01

This aim of this study was to compare universal adhesives and two-step self-etch adhesives in terms of dentin bond fatigue durability in self-etch mode. Three universal adhesives - Clearfil Universal, G-Premio Bond, and Scotchbond Universal Adhesive - and three-two-step self-etch adhesives - Clearfil SE Bond, Clearfil SE Bond 2, and OptiBond XTR - were used. The initial shear bond strength and shear fatigue strength of resin composite bonded to adhesive on dentin in self-etch mode were determined. Scanning electron microscopy observations of fracture surfaces after bond strength tests were also made. The initial shear bond strength of universal adhesives was material dependent, unlike that of two-step self-etch adhesives. The shear fatigue strength of Scotchbond Universal Adhesive was not significantly different from that of two-step self-etch adhesives, unlike the other universal adhesives. The shear fatigue strength of universal adhesives differed depending on the type of adhesive, unlike those of two-step self-etch adhesives. The results of this study encourage the continued use of two-step self-etch adhesive over some universal adhesives but suggest that changes to the composition of universal adhesives may lead to a dentin bond fatigue durability similar to that of two-step self-etch adhesives. © 2017 Eur J Oral Sci.

Transonic shock-induced dynamics of a flexible wing with a thick circular-arc airfoil

NASA Technical Reports Server (NTRS)

Bennett, Robert M.; Dansberry, Bryan E.; Farmer, Moses G.; Eckstrom, Clinton V.; Seidel, David A.; Rivera, Jose A., Jr.

1991-01-01

Transonic shock boundary layer oscillations occur on rigid models over a small range of Mach numbers on thick circular-arc airfoils. Extensive tests and analyses of this phenomena have been made in the past but essentially all of them were for rigid models. A simple flexible wing model with an 18 pct. circular arc airfoil was constructed and tested in the Langley Transonic Dynamics Tunnel to study the dynamic characteristics that a wing might have under these circumstances. In the region of shock boundary layer oscillations, buffeting of the first bending mode was obtained. This mode was well separated in frequency from the shock boundary layer oscillations. A limit cycle oscillation was also measured in a third bending like mode, involving wind vertical bending and splitter plate motion, which was in the frequency range of the shock boundary layer oscillations. Several model configurations were tested, and a few potential fixes were investigated.

Microbial ingrowth around single- and multi-component adhesives studied in vitro.

PubMed

Preussker, S; Klimm, W; Pöschmann, M; Koch, R

2003-01-01

The aim of this study was to compare the in vitro microbial leakage in 4 micro-hybrid composites in combination with 4 single-component dental adhesives (Scotchbond 1/Z100 MP = group 1; Syntac Single-Component/Tetric Flow = group 3; OptiBond Solo/XRV Herculite = group 5; Solobond M/Arabesk Top = group 7) and 4 multi-component dental adhesives (Scotchbond Multi-Purpose/Z100 MP = group 2; Syntac/Tetric Flow = group 4; OptiBond FL/XRV Herculite = group 6; Solobond Plus/Arabesk Top = group 8). Ninety-four mixed standardized Class V cavities of human caries-free extracted premolars were filled with eight different composite adhesive systems using a one-layer (groups 1-4) or a two-layer technique (groups 5-8). After thermocycling and incubation in a broth culture of Streptococcus mutans and Lactobacillus acidophilus, followed by decalcification and staining, the extent and the type of microbial leakage were measured histologically. The extent of microbial leakage in the composite restorations was very low in all groups and there were no significant differences between adhesives. Z100 MP in combination with single- and multi-component adhesives showed a significantly higher microbial leakage than Tetric Flow systems (U test: p=0.037). XRV Herculite adhesive systems showed significantly less extensive microbial leakage than Arabesk Top adhesive systems (U test: p<0.001). The single-component dental adhesives achieved a marginal adaptation of composites comparable to that of multi-component adhesives in vitro. Copyright 2003 S. Karger AG, Basel

Effects of Different Radiation Doses on the Bond Strengths of Two Different Adhesive Systems to Enamel and Dentin.

PubMed

da Cunha, Sandra Ribeiro de Barros; Ramos, Pedro Augusto Minorin Mendes; Haddad, Cecília Maria Kalil; da Silva, João Luis Fernandes; Fregnani, Eduardo Rodrigues; Aranha, Ana Cecília Corrêa

2016-01-01

To evaluate the effects of three different radiation doses on the bond strengths of two different adhesive systems to enamel and dentin. Eighty human third molars were randomly divided into four groups (n = 20) according to the radiation dose (control/no radiation, 20 Gy, 40 Gy, and 70 Gy). The teeth were sagittally sectioned into three slices: one mesial and one distal section containing enamel and one middle section containing dentin. The sections were then placed in the enamel and dentin groups, which were further divided into two subgroups (n = 10) according to the adhesive used. Three restorations were performed in each tooth (one per section) using Adper Single Bond 2 (3M ESPE) or Universal Single Bond (3M ESPE) adhesive system and Filtek Z350 XT (3M ESPE) resin composite and subjected to the microshear bond test. Data were analyzed using a two-way ANOVA followed by Tukey's test. Failure modes were examined under a stereoscopic loupe. Radiotherapy did not affect the bond strengths of the adhesives to either enamel or dentin. In dentin, the Universal Single Bond adhesive system showed higher bond strength values when compared with the Adper Single Bond adhesive system. More adhesive failures were observed in the enamel for all radiation doses and adhesives. Radiotherapy did not influence the bond strength to enamel or dentin, irrespective of the adhesive or radiation dose used.

Energetic ion acceleration at collisionless shocks

NASA Technical Reports Server (NTRS)

Decker, R. B.; Vlahos, L.

1985-01-01

An example is presented from a test particle simulation designed to study ion acceleration at oblique turbulent shocks. For conditions appropriate at interplanetary shocks near 1 AU, it is found that a shock with theta sub B n = 60 deg is capable of producing an energy spectrum extending from 10 keV to approx. 1 MeV in approx 1 hour. In this case total energy gains result primarily from several separate episodes of shock drift acceleration, each of which occurs when particles are scattered back to the shock by magnetic fluctuations in the shock vicinity.

Epigallocatechin-3-gallate and Epigallocatechin-3-O-(3-O-methyl)-gallate Enhance the Bonding Stability of an Etch-and-Rinse Adhesive to Dentin

PubMed Central

Yu, Hao-Han; Zhang, Ling; Yu, Fan; Li, Fang; Liu, Zheng-Ya; Chen, Ji-Hua

2017-01-01

This study evaluated epigallocatechin-3-gallate (EGCG) and epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG-3Me) modified etch-and-rinse adhesives (Single Bond 2, SB 2) for their antibacterial effect and bonding stability to dentin. EGCG-3Me was isolated and purified with column chromatography and preparative high performance liquid chromatography. EGCG and EGCG-3Me were incorporated separately into the adhesive SB 2 at concentrations of 200, 400, and 600 µg/mL. The effect of cured adhesives on the growth of Streptococcus mutans (S. mutans) was determined with scanning electron microscopy and confocal laser scanning microscopy; the biofilm of bacteria was further quantified via optical density 600 values. The inhibition of EGCG and EGCG-3Me on dentin-originated collagen proteases activities was evaluated with a proteases fluorometric assay kit. The degree of conversion (DC) of the adhesives was tested with micro-Raman spectrum. The immediate and post-thermocycling (5000 cycles) bond strength was assessed through Microtensile Bond Strength (MTBS) test. Cured EGCG/EGCG-3Me modified adhesives inhibit the growth of S. mutans in a concentration-dependent manner. The immediate MTBS of SB 2 was not compromised by EGCG/EGCG-3Me modification. EGCG/EGCG-3Me modified adhesive had higher MTBS than SB 2 after thermocycling, showing no correlation with concentration. The DC of the adhesive system was affected depending on the concentration of EGCG/EGCG-3Me and the depth of the hybrid layer. EGCG/EGCG-3Me modified adhesives could inhibit S. mutans adhesion to dentin–resin interface, and maintain the bonding stability. The adhesive modified with 400 µg/mL EGCG-3Me showed antibacterial effect and enhanced bonding stability without affect the DC of adhesive. PMID:28772546

Epigallocatechin-3-gallate and Epigallocatechin-3-O-(3-O-methyl)-gallate Enhance the Bonding Stability of an Etch-and-Rinse Adhesive to Dentin.

PubMed

Yu, Hao-Han; Zhang, Ling; Yu, Fan; Li, Fang; Liu, Zheng-Ya; Chen, Ji-Hua

2017-02-15

This study evaluated epigallocatechin-3-gallate (EGCG) and epigallocatechin-3- O -(3- O -methyl)-gallate (EGCG-3Me) modified etch-and-rinse adhesives (Single Bond 2, SB 2) for their antibacterial effect and bonding stability to dentin. EGCG-3Me was isolated and purified with column chromatography and preparative high performance liquid chromatography. EGCG and EGCG-3Me were incorporated separately into the adhesive SB 2 at concentrations of 200, 400, and 600 µg/mL. The effect of cured adhesives on the growth of Streptococcus mutans ( S. mutans ) was determined with scanning electron microscopy and confocal laser scanning microscopy; the biofilm of bacteria was further quantified via optical density 600 values. The inhibition of EGCG and EGCG-3Me on dentin-originated collagen proteases activities was evaluated with a proteases fluorometric assay kit. The degree of conversion (DC) of the adhesives was tested with micro-Raman spectrum. The immediate and post-thermocycling (5000 cycles) bond strength was assessed through Microtensile Bond Strength (MTBS) test. Cured EGCG/EGCG-3Me modified adhesives inhibit the growth of S. mutans in a concentration-dependent manner. The immediate MTBS of SB 2 was not compromised by EGCG/EGCG-3Me modification. EGCG/EGCG-3Me modified adhesive had higher MTBS than SB 2 after thermocycling, showing no correlation with concentration. The DC of the adhesive system was affected depending on the concentration of EGCG/EGCG-3Me and the depth of the hybrid layer. EGCG/EGCG-3Me modified adhesives could inhibit S. mutans adhesion to dentin-resin interface, and maintain the bonding stability. The adhesive modified with 400 µg/mL EGCG-3Me showed antibacterial effect and enhanced bonding stability without affect the DC of adhesive.

Bonding efficacy of new self-etching, self-adhesive dual-curing resin cements to dental enamel.

PubMed

Benetti, Paula; Fernandes, Virgílio Vilas; Torres, Carlos Rocha; Pagani, Clovis

2011-06-01

This study evaluated the efficacy of the union between two new self-etching self-adhesive resin cements and enamel using the microtensile bond strength test. Buccal enamel of 80 bovine teeth was submitted to finishing and polishing with metallographic paper to a refinement of #600, in order to obtain a 5-mm2 flat area. Blocks (2 x 4 x 4 mm) of laboratory composite resin were cemented to enamel according to different protocols: (1) untreated enamel + RelyX Unicem cement (RX group); (2) untreated enamel + Bifix SE cement (BF group); (3) enamel acid etching and application of resin adhesive Single Bond + RelyX Unicem (RXA group); (4) enamel acid etching and application of resin adhesive Solobond M + Bifix SE (BFA group). After 7 days of storage in distillated water at 37°C, the blocks were sectioned for obtaining microbar specimens with an adhesive area of 1 mm2 (n = 120). Specimens were submitted to the microtensile bond strength test at a crosshead speed of 0.5 mm/min. The results (in MPa) were analyzed statistically by ANOVA and Tukey's test. Enamel pre-treatment with phosphoric acid and resin adhesive (27.9 and 30.3 for RXA and BFA groups) significantly improved (p ≤ 0.05) the adhesion of both cements to enamel compared to the union achieved with as-polished enamel (9.9 and 6.0 for RX and BF). Enamel pre-treatment with acid etching and the application of resin adhesive significantly improved the bond efficacy of both luting agents compared to the union achieved with as-polished enamel.

High-Temperature Structures, Adhesives, and Advanced Thermal Protection Materials for Next-Generation Aeroshell Design

NASA Technical Reports Server (NTRS)

Collins, Timothy J.; Congdon, William M.; Smeltzer, Stanley S.; Whitley, Karen S.

2005-01-01

The next generation of planetary exploration vehicles will rely heavily on robust aero-assist technologies, especially those that include aerocapture. This paper provides an overview of an ongoing development program, led by NASA Langley Research Center (LaRC) and aimed at introducing high-temperature structures, adhesives, and advanced thermal protection system (TPS) materials into the aeroshell design process. The purpose of this work is to demonstrate TPS materials that can withstand the higher heating rates of NASA's next generation planetary missions, and to validate high-temperature structures and adhesives that can reduce required TPS thickness and total aeroshell mass, thus allowing for larger science payloads. The effort described consists of parallel work in several advanced aeroshell technology areas. The areas of work include high-temperature adhesives, high-temperature composite materials, advanced ablator (TPS) materials, sub-scale demonstration test articles, and aeroshell modeling and analysis. The status of screening test results for a broad selection of available higher-temperature adhesives is presented. It appears that at least one (and perhaps a few) adhesives have working temperatures ranging from 315-400 C (600-750 F), and are suitable for TPS-to-structure bondline temperatures that are significantly above the traditional allowable of 250 C (482 F). The status of mechanical testing of advanced high-temperature composite materials is also summarized. To date, these tests indicate the potential for good material performance at temperatures of at least 600 F. Application of these materials and adhesives to aeroshell systems that incorporate advanced TPS materials may reduce aeroshell TPS mass by 15% - 30%. A brief outline is given of work scheduled for completion in 2006 that will include fabrication and testing of large panels and subscale aeroshell test articles at the Solar-Tower Test Facility located at Kirtland AFB and operated by Sandia National Laboratories. These tests are designed to validate aeroshell manufacturability using advanced material systems, and to demonstrate the maintenance of bondline integrity at realistically high temperatures and heating rates. Finally, a status is given of ongoing aeroshell modeling and analysis efforts which will be used to correlate with experimental testing, and to provide a reliable means of extrapolating to performance under actual flight conditions. The modeling and analysis effort includes a parallel series of experimental tests to determine TSP thermal expansion and other mechanical properties which are required for input to the analysis models.

The role of complement C3 and fibrinogen in monocyte adhesion to PEO like plasma deposited tetraglyme

PubMed Central

Szott, Luisa M.; Horbett, Thomas A.

2010-01-01

The role of complement C3 in mediating adhesion of monocytes to plasma deposited tetraglyme surfaces was studied. Although fibrinogen (Fg) is usually considered the main factor in mediating phagocyte attachment, plasma deposited PEO-like tetraethylene glycol dimethyl ether (tetraglyme) coatings that have ultra-low Fg adsorption (< 10 ng/cm2) from low concentration solutions and low monocyte adhesion in vitro still show high phagocyte adhesion after short implantations and later become encapsulated when tested in vivo. To test whether higher Fg adsorption under in vivo conditions could explain the higher in vivo reactivity, we again measured the resistance of tetraglyme films to Fg adsorption. We found a surprising and previously unreported increased amount of adsorbed Fg on tetraglyme surfaces from higher concentration protein solutions. However, monocyte adhesion to tetraglyme did not markedly increase despite the increased Fg adsorption. We thus suspected proteins other than Fg must be responsible for the increased in vivo reactivity. We found that on tetraglyme pre-adsorbed with C3-depleted serum, monocyte adhesion was greatly reduced as compared to samples adsorbed with normal serum. Addition of exogenous pure C3 to the serum used to pre-adsorb the surfaces restored monocyte adhesion to tetraglyme coatings. While Fg clearly plays an important role in mediating monocyte adhesion to tetraglyme surfaces, the results show an additional role for adsorbed C3 in monocyte adhesion. PMID:20939050

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilpi, Lauri, E-mail: Lauri.Kilpi@vtt.fi; Ylivaara, Oili M. E.; Vaajoki, Antti

The scratch test method is widely used for adhesion evaluation of thin films and coatings. Usual critical load criteria designed for scratch testing of coatings were not applicable to thin atomic layer deposition (ALD) films on silicon wafers. Thus, the bases for critical load evaluation were established and the critical loads suitable for ALD coating adhesion evaluation on silicon wafers were determined in this paper as L{sub CSi1}, L{sub CSi2}, L{sub CALD1}, and L{sub CALD2}, representing the failure points of the silicon substrate and the coating delamination points of the ALD coating. The adhesion performance of the ALD Al{sub 2}O{submore » 3}, TiO{sub 2}, TiN, and TaCN+Ru coatings with a thickness range between 20 and 600 nm and deposition temperature between 30 and 410 °C on silicon wafers was investigated. In addition, the impact of the annealing process after deposition on adhesion was evaluated for selected cases. The tests carried out using scratch and Scotch tape test showed that the coating deposition and annealing temperature, thickness of the coating, and surface pretreatments of the Si wafer had an impact on the adhesion performance of the ALD coatings on the silicon wafer. There was also an improved load carrying capacity due to Al{sub 2}O{sub 3}, the magnitude of which depended on the coating thickness and the deposition temperature. The tape tests were carried out for selected coatings as a comparison. The results show that the scratch test is a useful and applicable tool for adhesion evaluation of ALD coatings, even when carried out for thin (20 nm thick) coatings.« less

In vitro and biomechanical screening of polyethylene glycol and poly(trimethylene carbonate) block copolymers for annulus fibrosus repair.

PubMed

Long, Rose G; Rotman, Stijn G; Hom, Warren W; Assael, Dylan J; Illien-Jünger, Svenja; Grijpma, Dirk W; Iatridis, James C

2018-02-01

Herniated intervertebral discs (IVDs) are a common cause of back and neck pain. There is an unmet clinical need to seal annulus fibrosus (AF) defects, as discectomy surgeries address acute pain but are complicated by reherniation and recurrent pain. Copolymers of polyethylene glycol with trimethylene carbonate (TMC) and hexamethylene diisocyanate (HDI) end-groups were formulated as AF sealants as the HDI form covalent bonds with native AF tissue. TMC adhesives were evaluated and optimized using the design criteria: stable size, strong adherence to AF tissue, high cytocompatibility, restoration of IVD biomechanics to intact levels following in situ repair, and low extrusion risk. TMC adhesives had high adhesion strength as assessed with a pushout test (150 kPa), and low degradation rates over 3 weeks in vitro. Both TMC adhesives had shear moduli (220 and 490 kPa) similar to, but somewhat higher than, AF tissue. The adhesive with three TMC moieties per branch (TMC3) was selected for additional in situ testing because it best matched AF shear properties. TMC3 restored torsional stiffness, torsional hysteresis area and axial range of motion to intact states. However, in a failure test of compressive deformation under fixed 5 ° flexion, some herniation risk was observed with failure strength of 5.9 MPa compared with 13.5 MPa for intact samples; TMC3 herniated under cyclic organ culture testing. These TMC adhesives performed well during in vitro and in situ testing, but additional optimization to enhance failure strength is required to further this material to advanced screening tests, such as long-term degradation. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Adhesion in a Vacuum Environment and its Implications for Dust Mitigation Techniques on Airless Bodies

NASA Technical Reports Server (NTRS)

Berkebile, Stephen; Gaier, James R.

2012-01-01

During the Apollo missions, the adhesion of dust to critical spacecraft systems was a greater problem than anticipated and resulted in functional degradation of thermal control surfaces, spacesuit seals, and other spacecraft components. Notably, Earth-based simulation efforts did not predict the magnitude and effects of dust adhesion in the lunar environment. Forty years later, we understand that the ultrahigh vacuum (UHV) environment, coupled with micrometeorite impacts and constant ion and photon bombardment from the sun result in atomically clean and high surface energy dust particles and spacecraft surfaces. However, both the dominant mechanism of adhesion in airless environments and the conditions for high fidelity simulation tests have still to be determined. The experiments presented in here aim to aid in the development of dust mitigation techniques for airless bodies (e.g., lunar surface, asteroids, moons of outer planets). The approach taken consists of (a) quantifying the adhesion between common polymer and metallic spacecraft materials and a synthetic noritic volcanic glass, as a function of surface cleanliness and of triboelectric charge transfer in a UHV environment, and (b) determining parameters for high fidelity tests through investigation of adhesion dependence on vacuum environment and sample treatment. Adhesion force has been measured between pins of spacecraft materials and a plate of synthetic volcanic glass by determining the pull-off force with a torsion balance. Although no significant adhesion is generally observed directly as a result of high surface energies, the adhesion due to induced electrostatic charge is observed to increase with spacecraft material cleanliness, in some cases by over a factor of 10. Furthermore, electrostatically-induced adhesion is found to decrease rapidly above pressures of 10-6 torr. It is concluded that high-fidelity tests should be conducted in high to ultrahigh vacuum and include an ionized surface cleaning process.

Conservative, special-relativistic smoothed particle hydrodynamics

NASA Astrophysics Data System (ADS)

Rosswog, Stephan

2010-11-01

We present and test a new, special-relativistic formulation of smoothed particle hydrodynamics (SPH). Our approach benefits from several improvements with respect to earlier relativistic SPH formulations. It is self-consistently derived from the Lagrangian of an ideal fluid and accounts for the terms that stem from non-constant smoothing lengths, usually called “grad-h terms”. In our approach, we evolve the canonical momentum and the canonical energy per baryon and thus circumvent some of the problems that have plagued earlier formulations of relativistic SPH. We further use a much improved artificial viscosity prescription which uses the extreme local eigenvalues of the Euler equations and triggers selectively on (a) shocks and (b) velocity noise. The shock trigger accurately monitors the relative density slope and uses it to fine-tune the amount of artificial viscosity that is applied. This procedure substantially sharpens shock fronts while still avoiding post-shock noise. If not triggered, the viscosity parameter of each particle decays to zero. None of these viscosity triggers is specific to special relativity, both could also be applied in Newtonian SPH.The performance of the new scheme is explored in a large variety of benchmark tests where it delivers excellent results. Generally, the grad-h terms deliver minor, though worthwhile, improvements. As expected for a Lagrangian method, it performs close to perfect in supersonic advection tests, but also in strong relativistic shocks, usually considered a particular challenge for SPH, the method yields convincing results. For example, due to its perfect conservation properties, it is able to handle Lorentz factors as large as γ = 50,000 in the so-called wall shock test. Moreover, we find convincing results in a rarely shown, but challenging test that involves so-called relativistic simple waves and also in multi-dimensional shock tube tests.

Effects of three silane primers and five adhesive agents on the bond strength of composite material for a computer-aided design and manufacturing system.

PubMed

Shinohara, Ayano; Taira, Yohsuke; Sakihara, Michino; Sawase, Takashi

2018-01-01

Objective The objective of this study was to evaluate the effects of combinations of silane primers and adhesive agents on the bond strength of a composite block for a computer-aided design and manufacturing system. Material and Methods Three silane primers [Clearfil Ceramic Primer (CP), Super-Bond PZ Primer (PZ), and GC Ceramic Primer II (GP)] were used in conjunction with five adhesive agents [G-Premio Bond (P-Bond), Repair Adhe Adhesive (R-Adhesive), Super-Bond D-Liner Dual (SB-Dual), Super-Bond C&B (SB-Self), and SB-Dual without tributylborane derivative (SB-Light)]. The surface of a composite block (Gradia Block) was ground with silicon carbide paper. After treatment with a silane primer, a adhesive agent was applied to each testing specimen. The specimens were then bonded with a light-curing resin composite. After 24 h, the shear bond strength values were determined and compared using a post hoc test (α=0.05, n=8/group). We also prepared control specimens without primer (No primer) and/or without adhesive agent (No adhesive). Results PZ/SB-Dual and GP/SB-Dual presented the highest bond strength, followed by GP/P-Bond, CP/SB-Dual, CP/R-Adhesive, No primer/SB-Dual, GP/R-Adhesive, CP/P-Bond, No primer/R-Adhesive, PZ/R-Adhesive, CP/SB-Self, PZ/P-Bond, PZ/SB-Self, and GP/SB-Self in descending order of bond strength. No primer/P-Bond, No primer/SB-Self, and all specimens in the SB-Light and No adhesive groups presented the lowest bond strengths. Conclusion A dual-curing adhesive agent (SB-Dual) containing a tributylborane derivative in combination with a silane primer (GP or PZ) presents a greater bond strength between the composite block and the repairing resin composite than the comparators used in the study.

Effects of three silane primers and five adhesive agents on the bond strength of composite material for a computer-aided design and manufacturing system

PubMed Central

2018-01-01

Abstract Objective The objective of this study was to evaluate the effects of combinations of silane primers and adhesive agents on the bond strength of a composite block for a computer-aided design and manufacturing system. Material and Methods Three silane primers [Clearfil Ceramic Primer (CP), Super-Bond PZ Primer (PZ), and GC Ceramic Primer II (GP)] were used in conjunction with five adhesive agents [G-Premio Bond (P-Bond), Repair Adhe Adhesive (R-Adhesive), Super-Bond D-Liner Dual (SB-Dual), Super-Bond C&B (SB-Self), and SB-Dual without tributylborane derivative (SB-Light)]. The surface of a composite block (Gradia Block) was ground with silicon carbide paper. After treatment with a silane primer, a adhesive agent was applied to each testing specimen. The specimens were then bonded with a light-curing resin composite. After 24 h, the shear bond strength values were determined and compared using a post hoc test (α=0.05, n=8/group). We also prepared control specimens without primer (No primer) and/or without adhesive agent (No adhesive). Results PZ/SB-Dual and GP/SB-Dual presented the highest bond strength, followed by GP/P-Bond, CP/SB-Dual, CP/R-Adhesive, No primer/SB-Dual, GP/R-Adhesive, CP/P-Bond, No primer/R-Adhesive, PZ/R-Adhesive, CP/SB-Self, PZ/P-Bond, PZ/SB-Self, and GP/SB-Self in descending order of bond strength. No primer/P-Bond, No primer/SB-Self, and all specimens in the SB-Light and No adhesive groups presented the lowest bond strengths. Conclusion A dual-curing adhesive agent (SB-Dual) containing a tributylborane derivative in combination with a silane primer (GP or PZ) presents a greater bond strength between the composite block and the repairing resin composite than the comparators used in the study. PMID:29742254

Accelerated aging of adhesive-mediated fiber post-resin composite bonds: A modeling approach.

PubMed

Radovic, Ivana; Monticelli, Francesca; Papacchini, Federica; Magni, Elisa; Cury, Alvaro Hafiz; Vulicevic, Zoran R; Ferrari, Marco

2007-08-01

Although fiber posts luted in root canals are not directly exposed to oral fluids, water storage is considered as in vitro accelerated aging test for bonded interfaces. The aim of the study was to evaluate the influence of accelerated water aging on fiber post-resin composite adhesion. Forty fiber posts (DT Light Post, RTD) were randomly divided into two main groups, according to the surface treatment performed. Group I: XPBond adhesive (Dentsply Caulk); Group II: sandblasting (Rocatec-Pre, 3M ESPE) and XPBond. Dual-cured resin cement (Calibra, Dentsply Caulk) and flowable composite (X-Flow, Dentsply Caulk) were applied on the posts to produce cylindrical specimens. The bond strength at the interface between post and cement/composite was measured with the microtensile test according to the non-trimming technique. Half of the sticks were tested immediately for bond strength, while in the other half testing was performed after 1 month of water storage at 37 degrees C. Post-cement/composite interfaces were evaluated under SEM prior and after water aging. Statistical analysis was performed using the Kruskal-Wallis ANOVA followed by Dunn's multiple range test (p<0.05). Immediate bond strength was higher on sandblasted posts. After water aging the two post surface treatments resulted comparable in bond strength. Resin cement achieved higher bond strength to fiber posts than flowable composite. Water aging significantly reduced bond strength. Sandblasting followed by adhesive coating may improve immediate post-resin bond strength in comparison to adhesive alone. However, fiber post-resin bond strength mediated by hydrophilic adhesive tends to decrease after water aging.

Design guidelines for use of adhesives in hybrid microcircuits. [for electronic equipment in space applications

NASA Technical Reports Server (NTRS)

Caruso, S. V.; Perkins, K. L.; Licari, J. J.

1973-01-01

Although it is generally accepted that the use of adhesives in the assembly of hybrid microcircuits offers advantages over other bonding methods, there currently does not exist a set of guidelines for the selection of adhesives which will insure that hybrid microcircuits assembled with them will meet the long use-life, high-reliability requirements of electronic equipment for space applications. This study was directed to the identification of the properties of electrically insulative adhesives that potentially could cause problems in such an application, and to the development of evaluation tests to quantify these properties and thus form the basis for establishing suitable guidelines and, ultimately, specifications. Bond strength, outgassing after cure, and corrosivity were selected for detailed attention since they are considered to be especially critical. Introductory discussion includes enumeration and brief comments on the properties of adhesives considered to be important for the proposed application, a general review of polymeric types of adhesives, and identification of the major types of adhesives commercially available and specifically designed for microelectronic use. The specific tests developed to evaluate bond strength, outgassing after cure, and corrosivity are discussed in detail, and comparative results obtained for selected adhesives representative of the major types are given.

Adhesion between polymers and evaporated gold and nickel films

NASA Technical Reports Server (NTRS)

Yamada, Y.; Wheeler, D. R.; Buckley, D. H.

1984-01-01

To obtain information on the adhesion between metal films and polymeric solids, the adhesion force was measured by means of a tensile pull test. It was found that the adhesion strengths between polymeric solids and gold films evaporated on polymer substrates were (1.11 + or - 0.53) multiplied by 10(6) N/M(2) on PTFE, about 5.49 multiplied by 10(6) N/m(2) on UHMWPE, and 6.54x10(6) on 6/6 nylon. The adhesion strengths for nickel films evaporated on PTFE, UHMWPE, and 6/6 nylon were found to be a factor of 1.7 higher than those for the gold coated PTFE, UHMWPE, and 6/6 nylon. To confirm quantitatively the effect of electron irradiation on the adhesion strength between a PTFE solid and metal films, a tensile pull test was performed on the irradiated PTFE specimens, which were prepared by evaporating nickel or gold on PTFE surfaces irradiated by 2-keV electrons for various times. After irradiation, the adhesion strength increased to (4.92 + or - 0.92)x10(6) N/m(2) for nickel coated PTFE and (1.82 + or - 0.48)x10(6) N/m(2) for gold coated PTFE. The improvement in adhesion for nickel is higher than that for gold.

Shock and vibration tests of uranium mononitride fuel pellets for a space power nuclear reactor

NASA Technical Reports Server (NTRS)

Adams, D. W.

1972-01-01

Shock and vibration tests were conducted on cylindrically shaped, depleted, uranium mononitride (UN) fuel pellets. The structural capabilities of the pellets were determined under exposure to shock and vibration loading which a nuclear reactor may encounter during launching into space. Various combinations of diametral and axial clearances between the pellets and their enclosing structures were tested. The results of these tests indicate that for present fabrication of UN pellets, a diametral clearance of 0.254 millimeter and an axial clearance of 0.025 millimeter are tolerable when subjected to launch-induced loads.

HOS cell adhesion on Ti6Al4V ELI texturized by CO2 laser

NASA Astrophysics Data System (ADS)

Sandoval-Amador, A.; Bayona–Alvarez, Y. M.; Carreño Garcia, H.; Escobar-Rivero, P.; Y Peña-Ballesteros, D.

2017-12-01

In this work, the response of HOS cells on Ti6Al4V ELI textured surfaces by a CO2 laser was evaluated. The test surfaces were; smooth Ti6Al4V, used as the control, and four textured surfaces with linear geometry. These four surfaces had different separation distances between textured lines, D1 (1000 microns), D2 (750 microns), D3 (500 microns) and D4 (250 microns). Toxicity of textured surfaces was assessed by MTT and the cellular adhesion test was performed using HOS ATCC CRL 1543 line cells. This test was done after 5 days of culture in a RPMI 1640 medium supplemented with 10% fetal bovine serum and 1% antibiotics. The results showed that the linear textures present 23% toxicity after 30 days of incubation, nevertheless, the adhesion tests results are inconclusive in such conditions and therefore the effect of the line separation on the cell adhesion cannot be determined.

Detection and Identification of Small Seismic Events Following the 3 September 2017 UNT Around North Korean Nuclear Test Site

NASA Astrophysics Data System (ADS)

Kim, W. Y.; Richards, P. G.

2017-12-01

At least four small seismic events were detected around the North Korean nuclear test site following the 3 September 2017 underground nuclear test. The magnitude of these shocks range from 2.6 to 3.5. Based on their proximity to the September 3 UNT, these shocks may be considered as aftershocks of the UNT. We assess the best method to classify these small events based on spectral amplitude ratios of regional P and S wave from the shocks. None of these shocks are classified as explosion-like based on P/S spectral amplitude ratios. We examine additional possible small seismic events around the North Korean test site by using seismic data from stations in southern Korea and northeastern China including IMS seismic arrays, GSN stations, and regional network stations in the region.

Adhesives and the ATS satellite. [construction of honeycomb panels

NASA Technical Reports Server (NTRS)

Hancock, F. E.

1972-01-01

Adhesives in the ATS satellite allow the designers to save weight, simplify design and fabrication and provide thermal and electrical conductivity or resistivity as required. The selections of adhesives are restricted to those few which can pass rigorous outgassing tests in order to avoid contaminating lenses and thermal control surfaces in space. An epoxy adhesive is used to construct the honeycomb panels which constitute most of the satellite's structure. General purpose epoxy adhesives hold doublers and standoffs in place and bond the truss to its fittings. Specialized adhesives include a high temperature resistant polyamide, a flexible polyurethane and filled epoxies which conduct heat or electricity.

Bone bonding through bioadhesives: present status.

PubMed

Meyer, G; Muster, D; Schmitt, D; Jung, P; Jaeger, J H

1979-01-01

Until recently use of adhesives was confined to cases in which glued areas could be pre-treated or at least cleaned. Thus, grease or oil contaminated surfaces could not be joined together by glueing. More recently, some adhesives have been developed which allow previous treatment of greasy surfaces to be avoided. Among these we find epoxy resins, acrylics and polyurethances. These adhesives have been used until now in various industries. We have begun a research program with these products and in aiming to design an adhesive which would enable immediate and strong bone bonding and avoid problems of metallic fixation, this study is a continuation of our previous research. Thus we tested - currently available surgical and dental adhesives - original mixtures developed in our laboratory. Mechanical assays were performed on bone samples from human femurs in different conditions : dried, cleaned, fresh, or after immersion in physiological solution. They consist essentially of tensile tests on Lhomargy and Zwick's machine wherein the stress is directed perpendicular to the interface. Variations of tensile strength (in h bar) are related to hardening time and to mixture composition. The specimens are joined together either in monolayers or in multilayers. The use of adequate catalysts ensures setting at room temperature. Torsion tests and fatigue tests are carried out concomitantly. Standardized bevel fermoral osteotomies were performed on mice with a dental saw after I.P. Nembutal anesthesia in order to test biological tolerance : - for the control group we study the evolution of bone repair after circumferential wiring - for the animals under test, bones are glued together with one of the proposed adhesives. Radiological and histological studies (using classical Azantrichrome staining after demineralization) are carried out at regular time intervals. In the control animals particular attention is paid to the time course of the formation, constitution and evolution of callus. In the test animals, we can observe callus formation, bone growth into the adhesive material and glue resorption, and look for specific antigenic phenomena. Despite expected improvements, bone glueing remains a challenge and only restricted clinical applications can be proposed.

Acoustic emission analysis: A test method for metal joints bonded by adhesives

NASA Technical Reports Server (NTRS)

Brockmann, W.; Fischer, T.

1978-01-01

Acoustic emission analysis is applied to study adhesive joints which had been subjected to mechanical and climatic stresses, taking into account conditions which make results applicable to adhesive joints used in aerospace technology. Specimens consisting of the alloy AlMgSi0.5 were used together with a phenolic resin adhesive, an epoxy resin modified with a polyamide, and an epoxy resin modified with a nitrile. Results show that the acoustic emission analysis provides valuable information concerning the behavior of adhesive joints under load and climatic stresses.

Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies.

PubMed

Bastos, Laura Alves; Sousa, Ana Beatriz Silva; Drubi-Filho, Brahim; Panzeri Pires-de-Souza, Fernanda de Carvalho; Garcia, Lucas da Fonseca Roberti

2015-02-01

The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/Silorane and Silorane groups). Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE) were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray), with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups), or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE) (Three-step/Methacrylate group) (n = 6). The restored teeth were sectioned into stick-shaped test specimens (1.0 × 1.0 mm), and coupled to a universal test machine (0.5 mm/min) to perform microtensile testing. Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p < 0.05). However, it was not significantly different from Preetching/Silorane and Methacrylate groups. Pre-etching increased bond strength of silorane-based composite specific adhesive system to dentin.

Pharmacokinetic Evaluation of Two Nicotine Patches in Smokers.

PubMed

Rasmussen, Scott; Horkan, Kathleen Halabuk; Kotler, Mitchell

2018-02-02

Smoking continues to be a major preventable cause of early mortality worldwide, and nicotine replacement therapy has been demonstrated to increase rates of abstinence among smokers attempting to quit. Nicotine transdermal systems (also known as nicotine patches) attach to the skin via an adhesive layer composed of a mixture of different-molecular-weight polyisobutylenes (PIBs) in a specific ratio. This randomized, single-dose, 2-treatment, crossover pharmacokinetic (PK) trial assessed the bioequivalence of nicotine patches including a replacement PIB adhesive (test) compared with the PIB adhesive historically used on marketed patches (reference). The test and reference patches were bioequivalent, as determined by the PK parameters of C max and AUC 0-t . In addition, the parameters T max and t 1/2 did not significantly differ between the 2 patches, supporting the bioequivalence finding from the primary analysis. The tolerability profiles of the patches containing the replacement and previously used PIB adhesives were similar; application-site adverse events did not significantly differ between test and reference patches. Overall, these data establish the bioequivalence of the nicotine patch with the replacement PIB adhesive formulation and the previously utilized PIB adhesive formulation. © 2018 The Authors. Clinical Pharmacology in Drug Development published by Wiley Periodicals, Inc. on behalf of The American College of Clinical Pharmacology.

Shock Radiation Tests for Saturn and Uranus Entry Probes

NASA Technical Reports Server (NTRS)

Cruden, Brett A.; Bogdanoff, David W.

2017-01-01

This paper describes a test series in the Electric Arc Shock Tube at NASA Ames Research Center with the objective of quantifying shock-layer radiative heating magnitudes for future probe entries into Saturn and Uranus atmospheres. Normal shock waves are measured in Hydrogen-Helium mixtures (89:11 by volume) at freestream pressures between 13-66 Pa (0.1-0.5 Torr) and velocities from 20-30 kms. No shock layer radiation is detected within measurement limits below 25 kms, a finding consistent with predictions for Uranus entries. Between 25-30 kms, radiance is quantified from the Vacuum Ultraviolet through Near Infrared, with focus on the Lyman-a and Balmer series lines of Hydrogen. Shock profiles are analyzed for electron number density and electronic state distribution. The shocks do not equilibrate over several cm, and in many cases the state distributions are non-Boltzmann. Radiation data are compared to simulations of Decadal Survey entries for Saturn and shown to be as much as 8x lower than predicted with the Boltzmann radiation model. Radiance is observed in front of the shock layer, the characteristics of which match the expected diffusion length.

Exploratory study on the effects of novel diamine curing agents and isocyanate precursors on the properties on new epoxy and urethane adhesives

NASA Technical Reports Server (NTRS)

Glasgow, D. G.; Garthwait, C.

1977-01-01

Aromatic diamines based on diphenyl sulfone and benzophenone were studied as epoxy adhesive curing agents. Previously found differences in adhesive strengths for meta vs para orientation were not found in these series. The use of aluminum and alumina as fillers in a m,m prime-methylene dianiline-cured epoxy adhesive was not found to be beneficial to adhesive strength. Alumina filled adhesives had much lower strength than unfilled adhesives. The unfilled m,m prime-methylene dianiline-based epoxy adhesive had excellent resistance to moisture relative to a p,p prime-methylene dianiline-based adhesive and maintained good strengths up to 250 F. A glass fiber composite based on a m,m prime-methylene dianiline-cured epoxy appeared to be equivalent to the p,p prime-methylene dianiline-cured epoxy as judged by short beam shear tests.

24 CFR 200.954 - Supplementary specific requirements under the HUD building product standard and certification...

Code of Federal Regulations, 2013 CFR

2013-04-01

... under the HUD building product standard and certification program for construction adhesives for wood... program for construction adhesives for wood floor systems. (a) Applicable standards. (1) All construction adhesives for field glued wood floor systems shall be designed, manufactured, and tested in compliance with...

24 CFR 200.954 - Supplementary specific requirements under the HUD building product standard and certification...

Code of Federal Regulations, 2014 CFR

2014-04-01

... under the HUD building product standard and certification program for construction adhesives for wood... program for construction adhesives for wood floor systems. (a) Applicable standards. (1) All construction adhesives for field glued wood floor systems shall be designed, manufactured, and tested in compliance with...

Use of additives to enhance the properties of cottonseed protein as wood adhesives

USDA-ARS?s Scientific Manuscript database

Soy protein is currently being used commercially as a “green” wood adhesive. Previous work in this laboratory has shown that cottonseed protein isolate, tested on maple wood veneer, produced higher adhesive strength and hot water resistance relative to soy protein. In the present study, cottonseed...

24 CFR 200.954 - Supplementary specific requirements under the HUD building product standard and certification...

Code of Federal Regulations, 2010 CFR

2010-04-01

... under the HUD building product standard and certification program for construction adhesives for wood... program for construction adhesives for wood floor systems. (a) Applicable standards. (1) All construction adhesives for field glued wood floor systems shall be designed, manufactured, and tested in compliance with...

Anxiolytic effect of BPC-157, a gastric pentadecapeptide: shock probe/burying test and light/dark test.

PubMed

Sikiric, P; Jelovac, N; Jelovac-Gjeldum, A; Dodig, G; Staresinic, M; Anic, T; Zoricic, I; Ferovic, D; Aralica, G; Buljat, G; Prkacin, I; Lovric-Bencic, M; Separovic, J; Seiwerth, S; Rucman, R; Petek, M; Turkovic, B; Ziger, T

2001-03-01

To study anxiolytic effect of a gastric pentadecapeptide, BPC-157. In shock probe/burying test, pentadecapeptide BPC-157 (10 microg/kg, 10 ng/kg, ip), diazepam (0.075, 0.0375 mg/kg, ip), and an equivolume of saline (5 mL/kg, ip) were given at 30 min prior test. In light/dark test, the same dosage of diazepam, BPC-157, and saline were given at 45 min prior procedure. Shock probe/burying test: rats treated with either diazepam or pentadecapeptide BPC-157 were much less afraid after the shock: almost not burying and the total time spent in burying was clearly less than in controls. However, while in the diazepam treated rats the number of shocks received increased over control values, in pentadecapeptide BPC-157 treated groups the number of shocks remained not modified compared with the control values. Light/dark test: after exposure to the intense light, diazepam treated mice had longer latencies of crossing to the dark compartment, a greater number of crossing and a greater number of exploratory rearing, and spent longer time in the light compartment, as compared to the control mice, while BPC-157 mice had a similar behavior to that of the control mice. In contrast with the effect in light area, in dark zone diazepam produced no change with respect to controls, while BPC-157 (10 microg/kg) mice had a greater number of crossing and a greater number of exploratory rearing. Both diazepam and BPC-157 displayed a bidirectional effect, but the activity of pentadecapeptide BPC-157 was particular, and different from diazepam.

Bio-inspired Armor Protective Material Systems for Ballistic Shock Mitigation

DTIC Science & Technology

2011-01-01

Coupon testing a b s t r a c t Severe transient ballistic shocks from projectile impacts, mine blasts , or overhead artillery attacks can incapacitate an...past two decades [1]. A ballistic shock results from a significant amount of concentrated energy deposited from caliber projectile impacts, mine blasts ...LS- Dyna , has been predominately utilized to calculate the target shock responses including acceleration histo- ries, shock response spectra

Evaluation of dental adhesive systems incorporating an antibacterial monomer eugenyl methacrylate (EgMA) for endodontic restorations.

PubMed

Almaroof, A; Niazi, S A; Rojo, L; Mannocci, F; Deb, S

2017-05-01

The purpose of this study was to incorporate EgMA, an antibacterial monomer into two commercial dental adhesive systems for their application in endodontic restoration with the aim to disinfect the root canal space before curing and to inhibit bacterial growth on their surfaces after being cured. EgMA monomer was added at 20%wt. into the formulation of the single-component self-etch, Clearfil Universal Bond™ (CUB) and into the catalyst and the adhesive components of the total-etch Adper Scotchbond-multipurpose™ (SBMP) adhesive systems. The degree of conversion (DC) was calculated from FTIR spectra, glass transition temperature (Tg) determined by DSC, water sorption and solubility were measured gravimetrically, and surface free energy (SFE) via contact angle measurements. The bonding performance to coronal and middle root canal dentin was assessed through push-out bond strength after filling the canals with a composite core material and the surface integrity was observed using SEM and confocal laser scanning microscopy (CLSM). The standard agar diffusion test (ADT) was used to identify the sensitivity of three endodontically pathogenic bacteria, Enterococcus faecalis, Streptococcus mutans and Propionibacterium acnes to uncured EgMA modified adhesives. Multispecies biofilm model from these strains was grown on the disc surface of cured adhesives and investigated using quantitative microbial culture and CLSM with live/dead staining. MTT assay was also used to determine the cytotoxicity of these adhesives. The incorporation of EgMA lowered polymerization exotherm and enhanced the hydrophobic character of these adhesives, without changing the DC and Tg in comparison to the controls (without EgMA). The total push-out bond strengths of the EgMA-containing adhesives were not significantly different from those of the controls (p>0.05). The modification of self-etch adhesive system enhanced the bond strength in the middle region of the roots canal. SEM of debonded specimens and CLSM examination showed the integrity of the resin-dentin interfaces. For all three bacteria tested, the sizes of the inhibition zones produced by uncured EgMA modified adhesives were significantly greater (p<0.05) than those of the controls. The results of biofilm inhibition tests showed less CFU for total bacteria on bonding agents with EgMA compared to the control materials (p<0.05). The modification at 20% monomer concentration had no adverse effects on cytocompatibility of both adhesives tested. The inclusion of EgMA endows dental adhesives with effective antibacterial effects without influencing their curing properties, bonding ability to root canal dentin, and cytotoxicity against human gingival fibroblasts, indicating the usefulness of their application in endodontic restorations. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Pyro shock simulation: Experience with the MIPS simulator

NASA Technical Reports Server (NTRS)

Dwyer, Thomas J.; Moul, David S.

1988-01-01

The Mechanical Impulse Pyro Shock (MIPS) Simulator at GE Astro Space Division is one version of a design that is in limited use throughout the aerospace industry, and is typically used for component shock testing at levels up to 10,000 response g's. Modifications to the force imput, table and component boundary conditions have allowed a range of test conditions to be achieved. Twelve different designs of components with weights up to 23 Kg are in the process or have completed qualification testing in the Dynamic Simulation Lab at GE in Valley Forge, Pa. A summary of the experience gained through the use of this simulator is presented as well as examples of shock experiments that can be readily simulated at the GE Astro MIPS facility.

The effect of the air-blowing step on the technique sensitivity of four different adhesive systems.

PubMed

Spreafico, Diego; Semeraro, Stefano; Mezzanzanica, Dario; Re, Dino; Gagliani, Massimo; Tanaka, Toru; Sano, Hidehiko; Sidhu, Sharanbir K

2006-03-01

To evaluate the technique sensitivity of four different adhesive systems using different air-blowing pressure. Four adhesive systems were employed: Clearfil SE Bond [SE] (Kuraray, Japan), G-Bond [GB] (GC Corporation, Japan), Adper Prompt L-Pop [LP] (3M ESPE, USA) and an experimental adhesive, SSB-200 [SSB] (Kuraray, Japan). Twenty-four extracted molars were used. After grinding the coronal enamel surface, the teeth were divided into two equal groups. The first group's teeth were randomly assigned for bonding with the different adhesives using gentle air-blowing (g). For the teeth of the second group, the four adhesive systems were applied using strong air-blowing (s). After storage overnight in 37 degrees C water, the bonded specimens were sectioned into sticks (1 mm x 1 mm wide), which were subjected to microtensile bond strength testing (microTBS) at a crosshead speed of 1 mm/min. The load at failure of each specimen was recorded and the data were analyzed by one-way ANOVA and Tukey HSD tests. The surfaces of the fractured specimens were observed using SEM to determine the failure mode. The results of the microTBS test showed that the highest bond strengths tended to be with SE for both gentle and strong air-blowing, and the significantly lowest for SSB with strong air streaming. Comparing the two techniques, significant differences were noted only for SSB-200 (P < 0.05). For each material, the SEM evaluation did not show distinct differences in the nature of the fractures between the two techniques, except for SSB-200. The adhesives tested are not technique sensitive, except SSB-200, with regards to the air-blowing step.

Fracture toughness versus micro-tensile bond strength testing of adhesive-dentin interfaces.

PubMed

De Munck, Jan; Luehrs, Anne-Katrin; Poitevin, André; Van Ende, Annelies; Van Meerbeek, Bart

2013-06-01

To assess interfacial fracture toughness of different adhesive approaches and compare to a standard micro-tensile bond-strength (μTBS) test. Chevron-notched beam fracture toughness (CNB) was measured following a modified ISO 24370 standard. Composite bars with dimensions of 3.0×4.0×25 mm were prepared, with the adhesive-dentin interface in the middle. At the adhesive-dentin interface, a chevron notch was prepared using a 0.15 mm thin diamond blade mounted in a water-cooled diamond saw. Each specimen was loaded until failure in a 4-point bend test setup and the fracture toughness was calculated according to the ISO specifications. Similarly, adhesive-dentin micro-specimens (1.0×1.0×8-10 mm) were stressed in tensile until failure to determine the μTBS. A positive correlation (r(2)=0.64) was observed between CNB and μTBS, which however was only nearly statistically significant, mainly due to the dissimilar outcome of Scotchbond Universal (3M ESPE). While few μTBS specimens failed at the adhesive-dentin interface, almost all CNB specimens failed interfacially at the notch tip. Weibull moduli for interfacial fracture toughness were much higher than for μTBS (3.8-11.5 versus 2.7-4.8, respectively), especially relevant with regard to early failures. Although the ranking of the adhesives on their bonding effectiveness tested using CNB and μTBS corresponded well, the outcome of CNB appeared more reliable and less variable. Fracture toughness measurement is however more laborious and requires specific equipment. The μTBS nevertheless appeared to remain a valid method to assess bonding effectiveness in a versatile way. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Method of measuring metal coating adhesion

DOEpatents

Roper, J.R.

A method for measuring metal coating adhesion to a substrate material comprising the steps of preparing a test coupon of substrate material having the metal coating applied to one surface thereof, applying a second metal coating of gold or silver to opposite surfaces of the test coupon by hot hollow cathode process, applying a coating to one end of each of two pulling rod members, joining the coated ends of the pulling rod members to said opposite coated surfaces of the test coupon by a solid state bonding technique and finally applying instrumented static tensile loading to the pulling rod members until fracture of the metal coating adhesion to the substrate material occurs.

Method of measuring metal coating adhesion

DOEpatents

Roper, John R.

1985-01-01

A method for measuring metal coating adhesion to a substrate material comprising the steps of preparing a test coupon of substrate material having the metal coating applied to one surface thereof, applying a second metal coating of gold or silver to opposite surfaces of the test coupon by hot hollow cathode process, applying a coating to one end of each of two pulling rod members, joining the coated ends of the pulling rod members to said opposite coated surfaces of the test coupon by a solid state bonding technique and finally applying instrumented static tensile loading to the pulling rod members until fracture of the metal coating adhesion to the substrate material occurs.

Method and Apparatus for the Quantification of Particulate Adhesion Forces on Various Substrates

NASA Technical Reports Server (NTRS)

Wohl, Christopher J.; Atkins, Brad M.; Connell, John W.

2011-01-01

Mitigation strategies for lunar dust adhesion have typically been limited to qualitative analysis. This technical memorandum describes the generation and operation of an adhesion testing device capable of quantitative assessment of adhesion forces between particulates and substrates. An aerosolization technique is described to coat a surface with a monolayer of particulates. Agitation of this surface, via sonication, causes particles to dislodge and be gravitationally fed into an optical particle counter. Experimentally determined adhesion force values are compared to forces calculated from van der Waals interactions and are used to calculate the work of adhesion using Johnson-Kendall-Roberts (JKR) theory. Preliminary results indicate that a reduction in surface energy and available surface area, through topographical modification, improve mitigation of particulate adhesion.

Improved Adhesion and Compliancy of Hierarchical Fibrillar Adhesives.

PubMed

Li, Yasong; Gates, Byron D; Menon, Carlo

2015-08-05

The gecko relies on van der Waals forces to cling onto surfaces with a variety of topography and composition. The hierarchical fibrillar structures on their climbing feet, ranging from mesoscale to nanoscale, are hypothesized to be key elements for the animal to conquer both smooth and rough surfaces. An epoxy-based artificial hierarchical fibrillar adhesive was prepared to study the influence of the hierarchical structures on the properties of a dry adhesive. The presented experiments highlight the advantages of a hierarchical structure despite a reduction of overall density and aspect ratio of nanofibrils. In contrast to an adhesive containing only nanometer-size fibrils, the hierarchical fibrillar adhesives exhibited a higher adhesion force and better compliancy when tested on an identical substrate.

Shock Radiation Tests for Saturn and Uranus Entry Probes

NASA Technical Reports Server (NTRS)

Cruden, Brett A.; Bogdanoff, David W.

2014-01-01

This paper describes a test series in the Electric Arc Shock Tube at NASA Ames Research Center with the objective of quantifying shock-layer radiative heating magnitudes for future probe entries into Saturn and Uranus atmospheres. Normal shock waves are measured in Hydrogen/Helium mixtures (89:11 by mole) at freestream pressures between 13-66 Pa (0.1-0.5 Torr) and velocities from 20-30 km/s. No shock layer radiation is detected below 25 km/s, a finding consistent with predictions for Uranus entries. Between 25-30 km/s, radiance is quantified from the Vacuum Ultraviolet through Near Infrared, with focus on the Lyman-alpha and Balmer series lines of Hydrogen. Shock profiles are analyzed for electron number density and electronic state distribution. The shocks do not equilibrate over several cm, and distributions are demonstrated to be non-Boltzmann. Radiation data are compared to simulations of Decadal survey entries for Saturn and shown to be significantly lower than predicted with the Boltzmann radiation model.

Delamination failure of multilaminated adhesively bonded joints at low temperatures

NASA Astrophysics Data System (ADS)

Lee, Chi-Seung; Chun, Min-Sung; Kim, Myung-Hyun; Lee, Jae-Myung

2011-08-01

A series of experimental investigations of multilaminated joints adhesively bonded by epoxy/polyurethane (PU) glue were conducted in order to examine the delamination failure characteristics under in-plane shear loading at low temperatures. In order to observe these phenomena, a series of lap-shear tests were carried out at various low temperatures (20 °C, -110 °C and -163 °C) and various adhesion areas (15 mm × 50 mm, 30 mm × 50 mm, 50 mm × 50 mm, 75 mm × 50 mm and 100 mm × 50 mm). The test results were used to investigate the delamination and material characteristics, as well as the material properties, e.g., ultimate shear stress and shear elongation. Furthermore, the dependencies of the characteristics of multilaminated adhesively bonded joints (MABJs) on temperature and adhesion area was analyzed using the stress-strain relationship, and closed form formulas that are functions of the dependent parameters are proposed.

Development of a novel nanoscratch technique for quantitative measurement of ice adhesion strength

NASA Astrophysics Data System (ADS)

Loho, T.; Dickinson, M.

2018-04-01

The mechanism for the way that ice adheres to surfaces is still not well understood. Currently there is no standard method to quantitatively measure how ice adheres to surfaces which makes ice surface studies difficult to compare. A novel quantitative lateral force adhesion measurement at the micro-nano scale for ice was created which shears micro-nano sized ice droplets (less than 3 μm in diameter and 100nm in height) using a nanoindenter. By using small ice droplets, the variables associated with bulk ice measurements were minimised which increased data repeatability compared to bulk testing. The technique provided post- testing surface scans to confirm that the ice had been removed and that measurements were of ice adhesion strength. Results show that the ice adhesion strength of a material is greatly affected by the nano-scale surface roughness of the material with rougher surfaces having higher ice adhesion strength.

Evaluation of non-specular reflecting silvered Teflon and filled adhesives

NASA Technical Reports Server (NTRS)

Bourland, G.; Cox, R. L.

1981-01-01

A non-specular silver-Teflon tape thermal control coating was tested to provide the data necessary to qualify it for use on the Space Shuttle Orbiter radiators. Effects of cure cycle temperature and pressure on optical and mechanical properties on the silver-Teflon tape were evaluated. The baseline Permacel P-223 adhesive, used with the specular silver-Teflon tape initially qualified for the Orbiter radiators, and four alternate metal-filled and unfilled adhesives were evaluated. Tests showed the cure process has no effect on the silver-Teflon optical properties, and that the baseline adhesive cure cycle gives best results. In addition the P-223 adhesive bond is more reproducible than the alternates, and the non-specular tape meets both the mechanical and the optical requirements of the Orbiter radiator coating specification. Existing Orbiter coating techniques were demonstrated to be effective in aplying the non-specular tape to a curved panel simulating the radiators. Author

Clinical impact of defibrillation testing at the time of implantable cardioverter-defibrillator insertion.

PubMed

Hadid, Claudio; Atienza, Felipe; Strasberg, Boris; Arenal, Ángel; Codner, Pablo; González-Torrecilla, Esteban; Datino, Tomás; Percal, Tamara; Almendral, Jesús; Ortiz, Mercedes; Martins, Raphael; Martinez-Alzamora, Nieves; Fernandez Aviles, Francisco

2015-01-01

Ventricular fibrillation is routinely induced during implantable cardioverter-defibrillator insertion to assess defibrillator performance, but this strategy is experiencing a progressive decline. We aimed to assess the efficacy of defibrillator therapies and long-term outcome in a cohort of patients that underwent defibrillator implantation with and without defibrillation testing. Retrospective observational series of consecutive patients undergoing initial defibrillator insertion or generator replacement. We registered spontaneous ventricular arrhythmias incidence and therapy efficacy, and mortality. A total of 545 patients underwent defibrillator implantation (111 with and 434 without defibrillation testing). After 19 (range 9-31) months of follow-up, the death rate per observation year (4% vs. 4%; p = 0.91) and the rate of patients with defibrillator-treated ventricular arrhythmic events per observation year (with test: 10% vs. without test: 12%; p = 0.46) were similar. The generalized estimating equations-adjusted first shock probability of success in patients with test (95%; CI 88-100%) vs. without test (98%; CI 96-100%; p = 0.42) and the proportion of successful antitachycardia therapies (with test: 87% vs. without test: 80%; p = 0.35) were similar between groups. There was no difference in the annualized rate of failed first shock per patient and per shocked patient between groups (5% vs. 4%; p = 0.94). In this observational study, that included an unselected population of patients with a defibrillator, no difference was found in overall mortality, first shock efficacy and rate of failed shocks regardless of whether defibrillation testing was performed or not.

[Effect of haw leaf extract and its preparation on polymorphonuclear leucocyte adhesion during HUVEC anoxia/reoxygenation injury].

PubMed

Li, Peng; Fu, Jian-hua; Li, Xin-zhi

2008-08-01

To study the effect and molecular mechanism of two haw leaf extracts, Vitexin-rhamnoside (VR) and Vitexin-glucoside (VG), and their preparation, Aoshaen injection (AI), on the polymorphonuclear leucocyte (PMN) adhesion during human umbilical vein endothelial cell (HUVEC) anoxia/reoxygenation (A/R) injury. The cell model of A/R injury duplicated by breaking off the oxygen supplying of HUVEC for 60 min followed with reoxygenating for 30 min (phase 1) or 240 min (phase 2) was taken as the experimental objective. The effects of testing drugs (VR, VG and AI) on PMN adhesion in the model cells were measured by enzyme immunoassay, and their effects on PMN superficial adhesion molecule CD11/CD18 expression were measured by flow cytometer respectively. After 60 min of anoxia, HUVEC was shrunk and deformed. The adhesion between PMN and HUVEC significantly revealed at phase 1 in the model group, but it was fewer in the normal cell group, and also lesser in the groups treated with various drugs. The condition of cell adhesion revealed at phase 2 was the similar to that at phase 1. All testing drugs, VR, VG and AI, showed inhibitory effect on the cell adhesion at either phase 1 or phase 2, showing a certain dose-effect relationship. The expression of CD11/ CD18 was also inhibited by the testing drugs, and a good dose-effect relation was shown by VG and AI. At the resting condition, there are almost no expression of CD11/CD18 molecule, but it could be enhanced by incubating PMN with supernate of A/R injured HUVEC culture, and more marked at phase 1. Adding the test drugs into the supernate could inhibit the enhancing of CD11/CD18 molecule expression and reduce the PMN-HUVEC adhesion, which may be one of the molecular mechanisms of haw leaf extracts and their preparation in protecting heart against A/R injury.

Shear bond strength of different adhesives tested in accordance with DIN 13990-1/-2 and using various methods of enamel conditioning.

PubMed

Richter, C; Jost-Brinkmann, P-G

2015-03-01

The purpose of this work was to analyze the shear bond strength (SBS) of different adhesives for orthodontic brackets in accordance with DIN 13990-1/-2, also taking into consideration potential effects arising from different scenarios of enamel conditioning and specimen storage. A total of 390 experiments were performed, with groups of 10 specimens subjected to identical treatments. Three adhesives were tested: Transbond™ XT (3M Unitek, Monrovia, USA), Beauty Ortho Bond (Shofu, Kyoto, Japan), and Fuji Ortho LC (GC Europe, Leuven, Belgium). SBS was evaluated separately at the bracket-adhesive and adhesive-enamel interfaces, as well as the total (enamel-adhesive-bracket) interface. The brackets were metal brackets for upper right central incisors (Discovery® from Dentaurum, Ispringen, Germany). A universal testing machine (Zwick Z010, Ulm, Germany) was used for testing the SBS after 15 min, or after storage in distilled water at 37 °C for 24 h, or after 24 h followed by 500 thermocycles alternating between 5 and 55 °C. Transbond™ XT produced the highest levels of SBS. The least favorable performance was observed with Fuji Ortho LC after enamel conditioning with 10 % polyacrylic acid. Thermocycling did not have a significant influence. Transbond™ XT and Beauty Ortho Bond (but not Fuji Ortho LC) yielded levels of SBS adequate for clinical application (≥ 7 MPa).

Cytotoxic effects of resin-modified orthodontic band adhesives. Are they safe?

PubMed

Malkoc, Siddik; Corekci, Bayram; Botsali, Hayriye Esra; Yalçin, Muhammet; Sengun, Abdülkadir

2010-09-01

To evaluate the cytotoxic effects of three different resin-modified orthodontic band adhesives. Three resin-modified orthodontic band adhesives (Bisco Ortho Band Paste LC, Multi-Cure Glass Ionomer Band Cement, and Transbond Plus Light Cure Band Adhesive) were prepared and the samples were extracted in 3 mL of Basal Medium Eagle with 10% newborn calf serum for 24 hours. The L929 cells were plated (25,000 cells/mL) in wells of 96-well dishes and maintained in a humidified incubator for 24 hours at 37 degrees C, 5% CO(2), and 95% air. After 24-hour incubation of the cells, the incubation medium was replaced by the immersed medium in which the samples were stored. Then L929 cells were incubated in contact with eluates for 24 hours. The cell mitochondrial activity was evaluated by the methyltetrazolium test. Twelve wells were used for each specimen, and methyltetrazolium tests were applied two times. The data were statistically analyzed using one-way analysis of variance and Tukey Honestly Significantly Different tests. Results with L929 fibroblasts demonstrated that all freshly prepared resin-modified orthodontic band adhesive materials reduced vital cell numbers (P > .05), in comparison to the control group. Our data demonstrate that all materials showed significant cytotoxicity compared to the control group. The results indicate that all materials showed significant cytotoxicity compared to the control group, and further studies using different test methods are needed for all resin-modified orthodontic band adhesives.

Lyophilized plasma attenuates vascular permeability, inflammation and lung injury in hemorrhagic shock.

PubMed

Pati, Shibani; Peng, Zhanglong; Wataha, Katherine; Miyazawa, Byron; Potter, Daniel R; Kozar, Rosemary A

2018-01-01

In severe trauma and hemorrhage the early and empiric use of fresh frozen plasma (FFP) is associated with decreased morbidity and mortality. However, utilization of FFP comes with the significant burden of shipping and storage of frozen blood products. Dried or lyophilized plasma (LP) can be stored at room temperature, transported easily, reconstituted rapidly with ready availability in remote and austere environments. We have previously demonstrated that FFP mitigates the endothelial injury that ensues after hemorrhagic shock (HS). In the current study, we sought to determine whether LP has similar properties to FFP in its ability to modulate endothelial dysfunction in vitro and in vivo. Single donor LP was compared to single donor FFP using the following measures of endothelial cell (EC) function in vitro: permeability and transendothelial monolayer resistance; adherens junction preservation; and leukocyte-EC adhesion. In vivo, using a model of murine HS, LP and FFP were compared in measures of HS- induced pulmonary vascular inflammation and edema. Both in vitro and in vivo in all measures of EC function, LP demonstrated similar effects to FFP. Both FFP and LP similarly reduced EC permeability, increased transendothelial resistance, decreased leukocyte-EC binding and persevered adherens junctions. In vivo, LP and FFP both comparably reduced pulmonary injury, inflammation and vascular leak. Both FFP and LP have similar potent protective effects on the vascular endothelium in vitro and in lung function in vivo following hemorrhagic shock. These data support the further development of LP as an effective plasma product for human use after trauma and hemorrhagic shock.

Investigation of adhesion of modern wound dressings: a comparative analysis of 56 different wound dressings.

PubMed

Klode, J; Schöttler, L; Stoffels, I; Körber, A; Schadendorf, D; Dissemond, J

2011-08-01

In the process of chronic wound care, adhesive wound dressings may cause pain and injury in the wound environment during dressing changes. At present, no standardized test procedures are available for the investigation of adhesion of wound dressings. Therefore, our study aimed to test the adhesion of different wound dressings on steel as well as on healthy skin. Within an open, comparative study, the adhesive areas of 56 wound dressings were investigated. The adhesives were categorized into acrylate (n = 23), silicone (n = 9), hydrocolloid (n = 17) and polyurethane groups (n = 7). Using an especially modified testing machine, the adhesion of the wound dressings was measured on steel as well as on the skin of healthy study participants, in compliance with the European EN 1939:2003 standard. The energy required to remove the wound dressings from human skin, was measured in Newton (N) and the following median values were obtained: hydrocolloid (2.25 N) > acrylate (1.14 N) > polyurethane (0.9 N) > silicone (0.7 N). The subjective pain intensity during the removal of the wound dressings was recorded using the visual analogue scale (VAS) with values ranging from 0 to 10. For hydrocolloid, it was 6.8, for acrylate 4.9, for polyurethane 3.1 and for silicone 2.5 points VAS. In comparison with human skin, the adhesion of wound dressings was significantly higher on steel (P < 0.0001), but was different for the different groups of wound dressings. Moreover, there was a statistically significant correlation between the adhesion and pain intensity (correlation coefficient 0.806; P = 0.01). The knowledge about the widely differing adhesion properties of different wound dressings on the skin of patients should nowadays be considered during the individual selection of the applied products. Based on these data, different types of wound dressings could be developed, guaranteeing a good adhesion and a low traumatic risk when removed. © 2010 The Authors. Journal of the European Academy of Dermatology and Venereology © 2010 European Academy of Dermatology and Venereology.

Mechanical properties and modeling of drug release from chlorhexidine-containing etch-and-rinse adhesives.

PubMed

Stanislawczuk, Rodrigo; Reis, Alessandra; Malaquias, Pamela; Pereira, Fabiane; Farago, Paulo Vitor; Meier, Marcia Margarete; Loguercio, Alessandro D

2014-04-01

To evaluate the effects of chlorhexidine (CHX) addition in different concentrations into simplified etch-and-rinse adhesives on the ultimate tensile strength (UTS), water sorption (WS), solubility (SO) and the rate of CHX release over time. We added CHX diacetate to Ambar [AM] (FGM) and XP Bond [XP] (Dentsply) in concentrations of 0, 0.01, 0.05, 0.1 and 0.2 wt%. For UTS (n=10 for each group), adhesive specimens were constructed in an hourglass shape metallic matrix with cross-sectional area of 0.8 mm(2). Half of specimens were tested after 24 h and the other half after 28 days of water storage in tension of 0.5 mm/min. For WS and SO (n=10 for each group), adhesive discs (5.8 mm×1.0 mm) were prepared into a mold. After desiccation, we weighed and stored the cured adhesive specimens in distilled water for evaluation of the WS, SO and the cumulative release of CHX over a 28-day period. For CHX release (n=10 for each group), spectrophotometric measurements of storage solution were performed to examine the release kinetics of CHX. We subjected data from each test to ANOVA and Tukey' test (α=0.05). XP Bond adhesive showed significantly more WS and SO and lower UTS than Ambar. In general, the addition of CHX did not alter WS, SO and UTS of the adhesives. XP showed a higher CHX release than AM (p<0.05) in all concentrations and the final amount of CHX release was directly proportional to the initial CHX concentration added to the adhesives. After 28 days of water storage, approximately 20% of CHX was released from XP and 8.0-12.0% from AM. Addition of CHX to commercial adhesive is a feasible method to provide a controlled release of CHX over time without jeopardizing WS, SO and UTS of the adhesives. Manufacturers should consider adding CHX to commercial adhesives to provide a controlled release of CHX over time. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A New Spin on an Old Technology: Piezoelectric Ejecta Diagnostics for Shock Environments

NASA Astrophysics Data System (ADS)

Vogan, W. S.; Anderson, W. W.; Grover, M.; King, N. S. P.; Lamoreaux, S. K.; Morley, K. B.; Rigg, P. A.; Stevens, G. D.; Turley, W. D.; Buttler, W. T.

2006-07-01

In our investigation of ejecta, or metal particulate emitted from a surface subjected to shock-loaded conditions, we have developed a shock experiment suitable for testing new ideas in piezoelectric mass and impact detectors. High-explosive (HE) shock loading of tin targets subjected to various machined and compressed finishes results in significant trends in ejecta characteristics of interest such as areal density and velocity. Our enhanced piezoelectric diagnostic, "piezo-pins" modified for shock mitigation, have proven levels of robustness and reliability suitable for effective operation in these ejecta milieux. These field tests address questions about ejecta production from surfaces of interest; experimental results are discussed and compared with those from complementary diagnostics such as x-ray and optical attenuation visualization techniques.

An LDA (Laser-Doppler Anemometry) investigation of three-dimensional normal shock wave boundary-layer interactions

NASA Technical Reports Server (NTRS)

Chriss, R. M.; Hingst, W. R.; Strazisar, A. J.; Keith, T. G., Jr.

1989-01-01

Nonintrusive measurements were made of a normal shock wave/boundary layer interaction. Two dimensional measurements were made throughout the interaction region while 3-D measurements were made in the vicinity of the shock wave. The measurements were made in the corner of the test section of a continuous supersonic wind tunnel in which a normal shock wave had been stabilized. Laser Doppler Anemometry, surface pressure measurement and flow visualization techniques were employed for two freestream Mach number test cases: 1.6 and 1.3. The former contained separated flow regions and a system of shock waves. The latter was found to be far less complicated. The results define the flow field structure in detail for each case.

An analysis of combustion studies in shock expansion tunnels and reflected shock tunnels

NASA Technical Reports Server (NTRS)

Jachimowski, Casimir J.

1992-01-01

The effect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in high-speed flows for a simulated Mach 17 flight condition was investigated by analyzing the results of comparative combustion experiments performed in a reflected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-stream combustor code that includes finite rate combustion chemistry. The results of this study indicate that the combustion process is kinetically controlled in the experiments in both tunnels and the presence of the nonequilibrium partially dissociated oxygen in the reflected shock tunnel enhances the combustion. Methods of compensating for the effect of dissociated oxygen are discussed.

Effect of Phosphoric Acid Pre-etching on Fatigue Limits of Self-etching Adhesives.

PubMed

Takamizawa, T; Barkmeier, W W; Tsujimoto, A; Scheidel, D D; Erickson, R L; Latta, M A; Miyazaki, M

2015-01-01

The purpose of this study was to use shear bond strength (SBS) and shear fatigue limit (SFL) testing to determine the effect of phosphoric acid pre-etching of enamel and dentin prior to application of self-etch adhesives for bonding resin composite to these substrates. Three self-etch adhesives--1) G- ænial Bond (GC Corporation, Tokyo, Japan); 2) OptiBond XTR (Kerr Corp, Orange, CA, USA); and 3) Scotchbond Universal (3M ESPE Dental Products, St Paul, MN, USA)--were used to bond Z100 Restorative resin composite to enamel and dentin surfaces. A stainless-steel metal ring with an inner diameter of 2.4 mm was used to bond the resin composite to flat-ground (4000 grit) tooth surfaces for determination of both SBS and SFL. Fifteen specimens each were used to determine initial SBS to human enamel/dentin, with and without pre-etching with a 35% phosphoric acid (Ultra-Etch, Ultradent Products Inc, South Jordan, UT, USA) for 15 seconds prior to the application of the adhesives. A staircase method of fatigue testing (25 specimens for each test) was then used to determine the SFL of resin composite bonded to enamel/dentin using a frequency of 10 Hz for 50,000 cycles or until failure occurred. A two-way analysis of variance and Tukey post hoc test were used for analysis of SBS data, and a modified t-test with Bonferroni correction was used for the SFL data. Scanning electron microscopy was used to examine the area of the bonded restorative/tooth interface. For all three adhesive systems, phosphoric acid pre-etching of enamel demonstrated significantly higher (p<0.05) SBS and SFL with pre-etching than it did without pre-etching. The SBS and SFL of dentin bonds decreased with phosphoric acid pre-etching. The SBS and SFL of bonds using phosphoric acid prior to application of self-etching adhesives clearly demonstrated different tendencies between enamel and dentin. The effect of using phosphoric acid, prior to the application of the self-etching adhesives, on SBS and SFL was dependent on the adhesive material and tooth substrate and should be carefully considered in clinical situations.

Influence of gas and treatment time on the surface modification of EPDM rubber treated at afterglow microwave plasmas

NASA Astrophysics Data System (ADS)

da Maia, J. V.; Pereira, F. P.; Dutra, J. C. N.; Mello, S. A. C.; Becerra, E. A. O.; Massi, M.; Sobrinho, A. S. da Silva

2013-11-01

The ethylene propylene diene monomer (EPDM) rubber possesses excellent physical/chemical bulk properties, is cost-effective, and has been used in the mechanical and aerospace industry. However, it has an inert surface and needs a surface treatment in order to improve its adhesion properties. Plasma modification is the most accepted technique for surface modification of polymers without affecting the properties of the bulk. In this study, an afterglow microwave plasma reactor was used to generate the plasma species responsible for the EPDM surface modification. The plasma modified surfaces were analyzed by means of contact angle measurement, adhesion tests, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. Two experimental variables were analyzed: type of the plasma gases and exposure time were considered. The predominant failure mode was adhesive, for long treatment times a mixture of adhesive and cohesive failure can be observed and the best conditions tested there was an increase of the rupture strength of about 27%, that can be associated mainly with the creation of oxygen containing functional groups on the rubber surface (CO, COC and CO) identified by spectroscopic methods. The predominant failure mode was adhesive, for long treatment times a mixture of adhesive and cohesive failure can be observed. In various conditions tested the contact angles easily decreased more than 500%. What can be concluded that high wettability is a necessary condition to obtain good adhesion, but this is not a sufficient condition.

Experimental Study on the Viscosity and Adhesive Performance of Exogenous Liquid Fibrin Glue

PubMed Central

HAYASHI, Takuro; HASEGAWA, Mitsuhiro; INAMASU, Joji; ADACHI, Kazuhide; NAGAHISA, Shinya; HIROSE, Yuichi

2014-01-01

Exogenous fibrin glue (FG) is highly suitable for neurosurgical procedures, because of its viscosity and adhesive properties. Several FGs are commercially available, but only few reports detail their differences. In the present study, we investigated the viscosity and adhesive performance of two types of FG: one is derived from blood donated in Europe and the United States (CSL Behring's Beriplast®, BP) and the other is derived from blood donated in Japan (the Chemo-Sero-Therapeutic Research Institute's Bolheal®, BH). The viscosity test that measured fibrinogen viscosity revealed that BP had significantly higher viscosity than BH. Similarly, the dripping test showed that BP traveled a significantly shorter drip distance in the vertical direction than BH, although the transverse diameter of the coagulated FG did not differ statistically significantly. In the tensile strength test, BP showed superior adhesion performance over BH. The histological study of the hematoxylin-eosin-stained specimens in both groups showed favorable adhesion. Although further studies are required on its manufacturing and usage methods, FG shows differences in viscosity and adhesive performance according to the blood from which it is derived. We conclude that it is desirable to select the type and usage method of FG according to the characteristics of the surgical operation in question. Our findings suggest that FG produced from the blood donated in Europe and the United States might be more suitable for use in surgical procedures that demand an especially high degree of viscosity and rapid adhesive performance. PMID:25367586

Experimental study on the viscosity and adhesive performance of exogenous liquid fibrin glue.

PubMed

Hayashi, Takuro; Hasegawa, Mitsuhiro; Inamasu, Joji; Adachi, Kazuhide; Nagahisa, Shinya; Hirose, Yuichi

2014-01-01

Exogenous fibrin glue (FG) is highly suitable for neurosurgical procedures, because of its viscosity and adhesive properties. Several FGs are commercially available, but only few reports detail their differences. In the present study, we investigated the viscosity and adhesive performance of two types of FG: one is derived from blood donated in Europe and the United States (CSL Behring's Beriplast(®), BP) and the other is derived from blood donated in Japan (the Chemo-Sero-Therapeutic Research Institute's Bolheal(®), BH). The viscosity test that measured fibrinogen viscosity revealed that BP had significantly higher viscosity than BH. Similarly, the dripping test showed that BP traveled a significantly shorter drip distance in the vertical direction than BH, although the transverse diameter of the coagulated FG did not differ statistically significantly. In the tensile strength test, BP showed superior adhesion performance over BH. The histological study of the hematoxylin-eosin-stained specimens in both groups showed favorable adhesion. Although further studies are required on its manufacturing and usage methods, FG shows differences in viscosity and adhesive performance according to the blood from which it is derived. We conclude that it is desirable to select the type and usage method of FG according to the characteristics of the surgical operation in question. Our findings suggest that FG produced from the blood donated in Europe and the United States might be more suitable for use in surgical procedures that demand an especially high degree of viscosity and rapid adhesive performance.

Characterization of laser-driven shock waves in solids using a fiber optic pressure probe.

PubMed

Cranch, Geoffrey A; Lunsford, Robert; Grün, Jacob; Weaver, James; Compton, Steve; May, Mark; Kostinski, Natalie

2013-11-10

Measurement of laser-driven shock wave pressure in solid blocks of polymethyl methacrylate is demonstrated using fiber optic pressure probes. Three probes based on a fiber Fabry-Perot, fiber Bragg grating, and interferometric fiber tip sensor are tested and compared. Shock waves are generated using a high-power laser focused onto a thin foil target placed in close proximity to the test blocks. The fiber Fabry-Perot sensor appears capable of resolving the shock front with a rise time of 91 ns. The peak pressure is estimated, using a separate shadowgraphy measurement, to be 3.4 GPa.

Ability of finger-jointed lumber to maintain load at elevated temperatures

Treesearch

Douglas R. Rammer; Samuel L. Zelinka; Laura E Hasburgh; Steven T. Craft

2018-01-01

This article presents a test method that was developed to screen adhesive formulations for finger-jointed lumber. The goal was to develop a small-scale test that could be used to predict whether an adhesive would pass a full-scale ASTM E119 wall assembly test. The method involved loading a 38-mm square finger-jointed sample in a four-point bending test inside of an...

The differential effects of heat-shocking on the viability of spores from Bacillus anthracis, Bacillus subtilis, and Clostridium sporogenes after treatment with peracetic acid- and glutaraldehyde-based disinfectants.

PubMed

March, Jordon K; Pratt, Michael D; Lowe, Chinn-Woan; Cohen, Marissa N; Satterfield, Benjamin A; Schaalje, Bruce; O'Neill, Kim L; Robison, Richard A

2015-10-01

This study investigated (1) the susceptibility of Bacillus anthracis (Ames strain), Bacillus subtilis (ATCC 19659), and Clostridium sporogenes (ATCC 3584) spores to commercially available peracetic acid (PAA)- and glutaraldehyde (GA)-based disinfectants, (2) the effects that heat-shocking spores after treatment with these disinfectants has on spore recovery, and (3) the timing of heat-shocking after disinfectant treatment that promotes the optimal recovery of spores deposited on carriers. Suspension tests were used to obtain inactivation kinetics for the disinfectants against three spore types. The effects of heat-shocking spores after disinfectant treatment were also determined. Generalized linear mixed models were used to estimate 6-log reduction times for each spore type, disinfectant, and heat treatment combination. Reduction times were compared statistically using the delta method. Carrier tests were performed according to AOAC Official Method 966.04 and a modified version that employed immediate heat-shocking after disinfectant treatment. Carrier test results were analyzed using Fisher's exact test. PAA-based disinfectants had significantly shorter 6-log reduction times than the GA-based disinfectant. Heat-shocking B. anthracis spores after PAA treatment resulted in significantly shorter 6-log reduction times. Conversely, heat-shocking B. subtilis spores after PAA treatment resulted in significantly longer 6-log reduction times. Significant interactions were also observed between spore type, disinfectant, and heat treatment combinations. Immediately heat-shocking spore carriers after disinfectant treatment produced greater spore recovery. Sporicidal activities of disinfectants were not consistent across spore species. The effects of heat-shocking spores after disinfectant treatment were dependent on both disinfectant and spore species. Caution must be used when extrapolating sporicidal data of disinfectants from one spore species to another. Heat-shocking provides a more accurate picture of spore survival for only some disinfectant/spore combinations. Collaborative studies should be conducted to further examine a revision of AOAC Official Method 966.04 relative to heat-shocking. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

The Shock and Vibration Bulletin. Part 3. Shock Testing, Shock Analysis

DTIC Science & Technology

1974-08-01

APPROXIMATE TRANSFORMATION C.S. O’Hearne and J.W. Shipley, Martin Marietta Aerospace, Orlando, Florida LINEAR LUMPED-MASS MODELING TECHNIQUES FOR BLAST LOADED...Leppert, B.K. Wada, Jet Propulsion Laboratory, Pasadena, California, and R. Miyakawa, Martin - Marietta Aerospace, Denver, Colorado (assigned to the Jet...Wilmington, Delaware Vibration Testing and Analysis DEVELOPMENT OF SAM-D MISSILE RANDOM VIBRATION RESPONSE LOADS P.G. Hahn, Martin Marietta Aerospace

Joining of polypropylene/polypropylene and glass fiber reinforced polypropylene composites

NASA Astrophysics Data System (ADS)

Zhang, Jianguang

Joining behavior of polypropylene (PP) to PP and long glass fiber reinforced polypropylene (LFT) to LFT were investigated. Adhesive bonding was used to join PP/PP. Both adhesive bonding and ultrasonic welding were used to join LFT/LFT. Single-lap shear testing and low velocity impact (LVI) testing were used to evaluate the performance of bonded structures. The two-part acrylic adhesive DP8005 was determined to be the best among the three adhesive candidates, which was attributed to its low surface energy. The impact resistance of LFT/LFT joints, normalized with respect to thickness, was higher than that of PP/PP joints because of higher stiffness of LFT/LFT joints. The stress states in the adhesive layer of adhesively bonded structures were analyzed using ANSYS and LS-DYNA to simulate the single-lap shear testing and LVI testing, respectively. The shear and peel stresses peaked at the edges of the adhesive layer. Compared to LFT/LFT joints, higher peel stress occurred in the adhesive layer in the PP/PP joints in tension. Impact response of adhesively bonded structures as evaluated by LS-DYNA showed good agreement with the experimental results. The effect of weld time and weld pressure on the shear strength of ultrasonically welded LFT/LFT was evaluated. With higher weld pressure, less time was required to obtain a complete weld. At longer weld times, lower weld pressure was required. From the 15 weld conditions studied, a weld map was obtained that provides conditions to achieve a complete weld. Nanoindentation was used to evaluate the effect of ultrasonic weld on the modulus and hardness of the PP matrix. Modulus and hardness of the PP matrix were slightly decreased by ultrasonic welding possibly due to the decrease in the molecular weight. The temperature profile in LFT/LFT in the transverse direction during ultrasonic welding was analyzed by two ANSYS-based thermal models: (a) one in which heat generated by interfacial friction was treated as a heat flux and (b) one in which heat was generated in a thin slab at the interface. The weld map obtained from the thin slab model was closer to the one obtained experimentally.

Repair Types, Procedures - Part 1

DTIC Science & Technology

2010-05-01

Affordable Combat Aircraft, AGARD - CP -600, 1997. [17] Helbling J, Grover R and Ratwani M. M “Analysis and Structural Test of Composite Reinforcement to...considered suitable for the composite patch repair of aluminum structure. Ductile adhesives such as FM- 73 are preferred over brittle adhesives Repair Types...zone. A proper cure cycle is followed as prescribed by the adhesive manufacturer. For FM- 73 adhesive cure at 2500F (1210C) for 120 minutes is

In vitro effects of Salvia officinalis L. essential oil on Candida albicans

PubMed Central

Sookto, Tularat; Srithavaj, Theerathavaj; Thaweboon, Sroisiri; Thaweboon, Boonyanit; Shrestha, Binit

2013-01-01

Objective To determine the anticandidal activities of Salvia officinalis L. (S. officinalis) essential oil against Candida albicans (C. albicans) and the inhibitory effects on the adhesion of C. albicans to polymethyl methacrylate (PMMA) resin surface. Methods Disc diffusion method was first used to test the anticandidal activities of the S. officinalis L. essential oil against the reference strain (ATCC 90028) and 2 clinical strains of C. albicans. Then the minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) were determined by modified membrane method. The adhesion of C. albicans to PMMA resin surface was assessed after immersion with S. officinalis L. essential oil at various concentrations of 1×MIC, 0.5×MIC and 0.25×MIC at room temperature for 30 min. One-way ANOVA was used to compare the Candida cell adhesion with the pretreatment agents and Tukey's test was used for multiple comparisons. Results S. officinalis L. essential oil exhibited anticandidal activity against all strains of C. albicans with inhibition zone ranging from 40.5 mm to 19.5 mm. The MIC and MLC of the oil were determined as 2.780 g/L against all test strains. According to the effects on C. albicans adhesion to PMMA resin surface, it was found that immersion in the essential oil at concentrations of 1×MIC (2.780 g/L), 0.5×MIC (1.390 g/L) and 0.25×MIC (0.695 g/L) for 30 min significantly reduced the adhesion of all 3 test strains to PMMA resin surface in a dose dependent manner (P<0.05). Conclusions S. officinalis L. essential oil exhibited anticandidal activities against C. albicans and had inhibitory effects on the adhesion of the cells to PMMA resin surface. With further testing and development, S. officinalis essential oil may be used as an antifungal denture cleanser to prevent candidal adhesion and thus reduce the risk of candida-associated denture stomatitis. PMID:23646301

Bonding characteristics of self-etching adhesives to intact versus prepared enamel.

PubMed

Perdigão, Jorge; Geraldeli, Saulo

2003-01-01

This study tested the null hypothesis that the preparation of the enamel surface would not affect the enamel microtensile bond strengths of self-etching adhesive materials. Ten bovine incisors were trimmed with a diamond saw to obtain a squared enamel surface with an area of 8 x 8 mm. The specimens were randomly assigned to five adhesives: (1) ABF (Kuraray), an experimental two-bottle self-etching adhesive; (2) Clearfil SE Bond (Kuraray), a two-bottle self-etching adhesive; (3) One-Up Bond F (Tokuyama), an all-in-one adhesive; (4) Prompt L-Pop (3M ESPE), an all-in-one adhesive; and (5) Single Bond (3M ESPE), a two-bottle total-etch adhesive used as positive control. For each specimen, one half was roughened with a diamond bur for 5 seconds under water spray, whereas the other half was left unprepared. The adhesives were applied as per manufacturers' directions. A universal hybrid composite resin (Filtek Z250, 3M ESPE) was inserted in three layers of 1.5 mm each and light-cured. Specimens were sectioned in X and Y directions to obtain bonded sticks with a cross-sectional area of 0.8 +/- 0.2 mm2. Sticks were tested in tension in an Instron at a cross-speed of 1 mm per minute. Statistical analysis was carried out with two-way analysis of variance and Duncan's test at p < .05. Ten extra specimens were processed for observation under a field-emission scanning electron microscope. Single Bond, the total-etch adhesive, resulted in statistically higher microtensile bond strength than any of the other adhesives regardless of the enamel preparation (unprepared = 31.5 MPa; prepared = 34.9 MPa, not statistically different at p < .05). All the self-etching adhesives resulted in higher microtensile bond strength when enamel was roughened than when enamel was left unprepared. However, for ABF and for Clearfil SE Bond this difference was not statistically significant at p > .05. When applied to ground enamel, mean bond strengths of Prompt L-Pop were not statistically different from those of Clearfil SE Bond and ABF. One-Up Bond F did not bond to unprepared enamel. Commercial self-etching adhesives performed better on prepared enamel than on unprepared enamel. The field-emission scanning electron microscope revealed a deep interprismatic etching pattern for the total-etch adhesive, whereas the self-etching systems resulted in an etching pattern ranging from absent to moderate.

Effect of Self-Adhesive and Separate Etch Adhesive Dual Cure Resin Cements on the Bond Strength of Fiber Post to Dentin at Different Parts of the Root.

PubMed

Amiri, Ehsan Mohamadian; Balouch, Fariba; Atri, Faezeh

2017-05-01

Bonding of fiber posts to intracanal dentin is challenging in the clinical setting. This study aimed to compare the effect of self-adhesive and separate etch adhesive dual cure resin cements on the bond strength of fiber post to dentin at different parts of the root. This in-vitro experimental study was conducted on 20 single-rooted premolars. The teeth were decoronated at 1mm coronal to the cementoenamel junction (CEJ), and the roots underwent root canal treatment. Post space was prepared in the roots. Afterwards, the samples were randomly divided into two groups. In group 1, the fiber posts were cemented using Rely X Unicem cement, while in group 2, the fiber posts were cemented using Duo-Link cement, according to the manufacturer's instructions. The intracanal post in each root was sectioned into three segments of coronal, middle, and apical, and each cross-section was subjected to push-out bond strength test at a crosshead speed of 1mm/minute until failure. Push-out bond strength data were analyzed using independent t-test and repeated measures ANOVA. The bond strength at the middle and coronal segments in separate etch adhesive cement group was higher than that in self-adhesive cement group. However, the bond strength at the apical segment was higher in self-adhesive cement group compared to that in the other group. Overall, the bond strength in separate etch adhesive cement group was significantly higher than that in self-adhesive cement group (P<0.001). Bond strength of fiber post to intracanal dentin is higher after the use of separate etch adhesive cement compared to self-adhesive cement.

[The durability of three self-etch adhesives bonded to dentin].

PubMed

Tian, Fu-Cong; Wang, Xiao-Yan; Gao, Xue-Jun

2013-04-01

To investigate the durability of self-etch adhesives bonded to dentin in vitro. Forty-two extracted human molars were selected and occlusal dentin surfaces were exposed. The teeth were randomly distributed into three groups based on adhesives applied. The one-step self-etch adhesive B(Adper Prompt) and C(G-Bond) and two-step self-etch adhesive A (Clearfil SE bond) were used. After application of the adhesives to the dentin surfaces, composite crowns were built up, after 24 h water storage, the teeth were sectioned longitudinally into sticks (1.0 mm×1.0 mm bonding area) for microtensile testing or slabs (1 mm thick) for scanning electron microscopec (SEM) observation. Bonding strength (mTBS) and nano-leakage were evaluated immediately after cutting or after 6 months in water. The mTBS was analyzed using one-way ANOVA (SPSS 13.0). The nanoleakage was observed by SEM with a backscattered electron detector. Both adhesives and water storage time affected the mTBS. All adhesives showed decreased bond strength after six-month water aging [A dropped from (40.60 ± 5.76) MPa to (36.04 ± 3.15) MPa; B dropped from (19.06 ± 1.50) MPa to (11.19 ± 1.97) MPa; C dropped from (17.75 ± 1.10) MPa to (9.14 ± 1.15) MPa] (P < 0.05). B and C showed lower mTBS than A after aging (P < 0.05). Compared to A, nanoleakage was more obvious after aging for B and C. All self-etch adhesives tested were probably influenced by water aging, however, the two-step adhesive showed better durability than the one-step adhesives.

Effective testing of personal protective equipment in blast loading conditions in shock tube: Comparison of three different testing locations

PubMed Central

Alay, Eren; Zheng, James Q.; Chandra, Namas

2018-01-01

We exposed a headform instrumented with 10 pressure sensors mounted flush with the surface to a shock wave with three nominal intensities: 70, 140 and 210 kPa. The headform was mounted on a Hybrid III neck, in a rigid configuration to eliminate motion and associated pressure variations. We evaluated the effect of the test location by placing the headform inside, at the end and outside of the shock tube. The shock wave intensity gradually decreases the further it travels in the shock tube and the end effect degrades shock wave characteristics, which makes comparison of the results obtained at three locations a difficult task. To resolve these issues, we developed a simple strategy of data reduction: the respective pressure parameters recorded by headform sensors were divided by their equivalents associated with the incident shock wave. As a result, we obtained a comprehensive set of non-dimensional parameters. These non-dimensional parameters (or amplification factors) allow for direct comparison of pressure waveform characteristic parameters generated by a range of incident shock waves differing in intensity and for the headform located in different locations. Using this approach, we found a correlation function which allows prediction of the peak pressure on the headform that depends only on the peak pressure of the incident shock wave (for specific sensor location on the headform), and itis independent on the headform location. We also found a similar relationship for the rise time. However, for the duration and impulse, comparable correlation functions do not exist. These findings using a headform with simplified geometry are baseline values and address a need for the development of standardized parameters for the evaluation of personal protective equipment (PPE) under shock wave loading. PMID:29894521

Novel CPR system that predicts return of spontaneous circulation from amplitude spectral area before electric shock in ventricular fibrillation.

PubMed

Nakagawa, Yoshihide; Amino, Mari; Inokuchi, Sadaki; Hayashi, Satoshi; Wakabayashi, Tsutomu; Noda, Tatsuya

2017-04-01

Amplitude spectral area (AMSA), an index for analysing ventricular fibrillation (VF) waveforms, is thought to predict the return of spontaneous circulation (ROSC) after electric shocks, but its validity is unconfirmed. We developed an equation to predict ROSC, where the change in AMSA (ΔAMSA) is added to AMSA measured immediately before the first shock (AMSA1). We examine the validity of this equation by comparing it with the conventional AMSA1-only equation. We retrospectively investigated 285 VF patients given prehospital electric shocks by emergency medical services. ΔAMSA was calculated by subtracting AMSA1 from last AMSA immediately before the last prehospital electric shock. Multivariate logistic regression analysis was performed using post-shock ROSC as a dependent variable. Analysis data were subjected to receiver operating characteristic curve analysis, goodness-of-fit testing using a likelihood ratio test, and the bootstrap method. AMSA1 (odds ratio (OR) 1.151, 95% confidence interval (CI) 1.086-1.220) and ΔAMSA (OR 1.289, 95% CI 1.156-1.438) were independent factors influencing ROSC induction by electric shock. Area under the curve (AUC) for predicting ROSC was 0.851 for AMSA1-only and 0.891 for AMSA1+ΔAMSA. Compared with the AMSA1-only equation, the AMSA1+ΔAMSA equation had significantly better goodness-of-fit (likelihood ratio test P<0.001) and showed good fit in the bootstrap method. Post-shock ROSC was accurately predicted by adding ΔAMSA to AMSA1. AMSA-based ROSC prediction enables application of electric shock to only those patients with high probability of ROSC, instead of interrupting chest compressions and delivering unnecessary shocks to patients with low probability of ROSC. Copyright © 2017 Elsevier B.V. All rights reserved.

Nanoporous Monolithic Microsphere Arrays Have Anti-Adhesive Properties Independent of Humidity

PubMed Central

Eichler-Volf, Anna; Xue, Longjian; Kovalev, Alexander; Gorb, Elena V.; Gorb, Stanislav N.; Steinhart, Martin

2016-01-01

Bioinspired artificial surfaces with tailored adhesive properties have attracted significant interest. While fibrillar adhesive pads mimicking gecko feet are optimized for strong reversible adhesion, monolithic microsphere arrays mimicking the slippery zone of the pitchers of carnivorous plants of the genus Nepenthes show anti-adhesive properties even against tacky counterpart surfaces. In contrast to the influence of topography, the influence of relative humidity (RH) on adhesion has been widely neglected. Some previous works deal with the influence of RH on the adhesive performance of fibrillar adhesive pads. Commonly, humidity-induced softening of the fibrils enhances adhesion. However, little is known on the influence of RH on solid anti-adhesive surfaces. We prepared polymeric nanoporous monolithic microsphere arrays (NMMAs) with microsphere diameters of a few 10 µm to test their anti-adhesive properties at RHs of 2% and 90%. Despite the presence of continuous nanopore systems through which the inner nanopore walls were accessible to humid air, the topography-induced anti-adhesive properties of NMMAs on tacky counterpart surfaces were retained even at RH = 90%. This RH-independent robustness of the anti-adhesive properties of NMMAs significantly contrasts the adhesion enhancement by humidity-induced softening on nanoporous fibrillar adhesive pads made of the same material. PMID:28773497

Human dental pulp stem cell adhesion and detachment in polycaprolactone electrospun scaffolds under direct perfusion

PubMed Central

Paim, A.; Braghirolli, D.I.; Cardozo, N.S.M.; Pranke, P.; Tessaro, I.C.

2018-01-01

Cell adhesion in three-dimensional scaffolds plays a key role in tissue development. However, stem cell behavior in electrospun scaffolds under perfusion is not fully understood. Thus, an investigation was made on the effect of flow rate and shear stress, adhesion time, and seeding density under direct perfusion in polycaprolactone electrospun scaffolds on human dental pulp stem cell detachment. Polycaprolactone scaffolds were electrospun using a solvent mixture of chloroform and methanol. The viable cell number was determined at each tested condition. Cell morphology was analyzed by confocal microscopy after various incubation times for static cell adhesion with a high seeding density. Scanning electron microscopy images were obtained before and after perfusion for the highest flow rate tested. The wall pore shear stress was calculated for all tested flow rates (0.005–3 mL/min). An inversely proportional relationship between adhesion time with cell detachment under perfusion was observed. Lower flow rates and lower seeding densities reduced the drag of cells by shear stress. However, there was an operational limit for the lowest flow rate that can be used without compromising cell viability, indicating that a flow rate of 0.05 mL/min might be more suitable for the tested cell culture in electrospun scaffolds under direct perfusion. PMID:29590258

Shear Bond Strengths and Morphological Evaluation of Filled and Unfilled Adhesive Interfaces to Enamel and Dentine

PubMed Central

Mortazavi, Vajihesadat; Fathi, Mohammadhosein; Ataei, Ebrahim; Khodaeian, Niloufar; Askari, Navid

2012-01-01

In this laboratory study shear bond strengths of three filled and one unfilled adhesive systems to enamel and dentine were compared. Forty-eight extracted intact noncarious human mandibular molars were randomly assigned to two groups of 24 one for bonding to enamel and the other for bonding to dentine. Buccal and lingual surfaces of each tooth were randomly assigned for application of each one of filled (Prime & Bond NT (PBNT), Optibond Solo Plus (OBSP), and Clearfil SE Bond (CSEB)) and unfilled (Single Bond (SB)) adhesive systems (n = 12). A universal resin composite was placed into the translucent plastic cylinders (3 mm in diameter and 2 mm in length) and seated against the enamel and dentine surfaces and polymerized for 40 seconds. Shear bond strength was determined using a universal testing machine, and the results were statistically analyzed using two-way ANOVA, one-way ANOVA, t-test, and Tukey HSD post hoc test with a 5% level of significance.There were no statistically significant differences in bond strength between the adhesive systems in enamel, but CSEB and SB exhibited significantly higher and lower bond strength to dentine, respectively, than the other tested adhesive systems while there were no statistically significant differences between PBNT and OBSP. PMID:23209471

Simulations of the Richtmyer-Meshkov Instability in a two-shock vertical shock tube

NASA Astrophysics Data System (ADS)

Ferguson, Kevin; Olson, Britton; Jacobs, Jeffrey

2017-11-01

Simulations of the Richtmyer-Meshkov Instability (RMI) in a new two-shock vertical shock tube configuration are presented. The simulations are performed using the ARES code at Lawrence-Livermore National Laboratory (LLNL). Two M=1.2 shock waves travel in opposing directions and impact an initially stationary interface formed by sulfur hexaflouride (SF6) and air. The delay between the two shocks is controlled to achieve a prescribed temporal separation in shock wave arrival time. Initial interface perturbations and diffusion profiles are generated in keeping with previously gathered experimental data. The effect of varying the inter-shock delay and initial perturbation structure on instability growth and mixing parameters is examined. Information on the design, construction, and testing of a new two-shock vertical shock tube are also presented.

Surface heat shock protein 90 serves as a potential receptor for calcium oxalate crystal on apical membrane of renal tubular epithelial cells.

PubMed

Fong-Ngern, Kedsarin; Sueksakit, Kanyarat; Thongboonkerd, Visith

2016-07-01

Adhesion of calcium oxalate monohydrate (COM) crystals on renal tubular epithelial cells is a crucial step in kidney stone formation. Finding potential crystal receptors on the apical membrane of the cells may lead to a novel approach to prevent kidney stone disease. Our previous study identified a large number of crystal-binding proteins on the apical membrane of MDCK cells. However, their functional role as potential crystal receptors had not been validated. The present study aimed to address the potential role of heat shock protein 90 (HSP90) as a COM crystal receptor. The apical membrane was isolated from polarized MDCK cells by the peeling method and recovered proteins were incubated with COM crystals. Western blot analysis confirmed the presence of HSP90 in the apical membrane and the crystal-bound fraction. Immunofluorescence staining without permeabilization and laser-scanning confocal microscopy confirmed the surface HSP90 expression on the apical membrane of the intact cells. Crystal adhesion assay showed that blocking surface HSP90 by specific anti-HSP90 antibody and knockdown of HSP90 by small interfering RNA (siRNA) dramatically reduced crystal binding on the apical surface of MDCK cells (by approximately 1/2 and 2/3, respectively). Additionally, crystal internalization assay revealed the presence of HSP90 on the membrane of endocytic vesicle containing the internalized COM crystal. Moreover, pretreatment of MDCK cells with anti-HSP90 antibody significantly reduced crystal internalization (by approximately 1/3). Taken together, our data indicate that HSP90 serves as a potential receptor for COM crystals on the apical membrane of renal tubular epithelial cells and is involved in endocytosis/internalization of the crystals into the cells.

Influence of different etching modes on bond strength and fatigue strength to dentin using universal adhesive systems.

PubMed

Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Berry, Thomas P; Watanabe, Hedehiko; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

2016-02-01

The purpose of this study was to determine the dentin bonding ability of three new universal adhesive systems under different etching modes using fatigue testing. Prime & Bond elect [PE] (DENTSPLY Caulk), Scotchbond Universal [SU] (3M ESPE), and All Bond Universal [AU] (Bisco) were used in this study. A conventional single-step self-etch adhesive, Clearfil Bond SE ONE [CS] (Kuraray Noritake Dental) was also included as a control. Shear bond strengths (SBS) and shear fatigue strength (SFS) to human dentin were obtained in the total-etch mode and self-etch modes. For each test condition, 15 specimens were prepared for the SBS and 30 specimens for SFS. SEM was used to examine representative de-bonded specimens, treated dentin surfaces and the resin/dentin interface for each test condition. Among the universal adhesives, PE in total-etch mode showed significantly higher SBS and SFS values than in self-etch mode. SU and AU did not show any significant difference in SBS and SFS between the total-etch mode and self-etch mode. However, the single-step self-etch adhesive CS showed significantly lower SBS and SFS values in the etch-and-rinse mode when compared to the self-etch mode. Examining the ratio of SFS/SBS, for PE and AU, the etch-and-rinse mode groups showed higher ratios than the self-etch mode groups. The influence of different etching modes on dentin bond quality of universal adhesives was dependent on the adhesive material. However, for the universal adhesives, using the total-etch mode did not have a negative impact on dentin bond quality. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Repair bond strength in aged methacrylate- and silorane-based composites.

PubMed

Bacchi, Atais; Consani, Rafael Leonardo; Sinhoreti, Mario Alexandre; Feitosa, Victor Pinheiro; Cavalcante, Larissa Maria; Pfeifer, Carmem Silva; Schneider, Luis Felipe

2013-10-01

To evaluate the tensile bond strength at repaired interfaces of aged dental composites, either dimethacrylate- or silorane-based, when subjected to different surface treatments. The composites used were Filtek P60 (methacrylate-based, 3M ESPE) and Filtek P90 (silorane-based, 3M ESPE), of which 50 slabs were stored for 6 months at 37°C. The surface of adhesion was abraded with a 600-grit silicone paper and the slabs repaired with the respective composite, according to the following surface treatment protocols: G1: no treatment; G2: adhesive application; G3: silane + adhesive; G4: sandblasting (Al2O3) + adhesive; G5: sandblasting (Al2O3) + silane + adhesive. After 24-h storage in distilled water at 37°C, tensile bond strength (TBS) was determined in a universal testing machine (Instron 4411) at a crosshead speed of 0.5 mm/min. The original data were submitted to two-way ANOVA and Tukey's test (α = 5%). The methacrylate-based composite presented a statistically significantly higher repair potential than did the silorane-based resin (p = 0.0002). Of the surface treatments for the silorane-based composite, aluminum-oxide air abrasion and adhesive (18.5 ± 3.3MPa) provided higher bond strength than only adhesive application or the control group without surface treatment. For Filtek P60, the control without treatment presented lower repair strength than all other groups with surface treatments, which were statistically similar to each other. The interaction between the factors resin composite and surface treatment was significant (p = 0.002). For aged silorane-based materials, repairs were considered successful after sandblasting (Al2O3) and adhesive application. For methacrylate resin, repair was successful with all surface treatments tested.

Scramjet Tests in a Shock Tunnel at Flight Mach 7, 10, and 15 Conditions

NASA Technical Reports Server (NTRS)

Rogers, R. C.; Shih, A. T.; Tsai, C.-Y.; Foelsche, R. O.

2001-01-01

Tests of the Hyper-X scramjet engine flowpath have been conducted in the HYPULSE shock tunnel at conditions duplicating the stagnation enthalpy at flight Mach 7, 10, and 15. For the tests at Mach 7 and 10 HYPULSE was operated as a reflected-shock tunnel; at the Mach 15 condition, HYPULSE was operated as a shock-expansion tunnel. The test conditions matched the stagnation enthalpy of a scramjet engine on an aerospace vehicle accelerating through the atmosphere along a 1000 psf dynamic pressure trajectory. Test parameter variation included fuel equivalence ratios from lean (0.8) to rich (1.5+); fuel composition from pure hydrogen to mixtures of 2% and 5% silane in hydrogen by volume; and inflow pressure and Mach number made by changing the scramjet model mounting angle in the HYPULSE test chamber. Data sources were wall pressures and heat flux distributions and schlieren and fuel plume imaging in the combustor/nozzle sections. Data are presented for calibration of the facility nozzles and the scramjet engine model. Comparisons of pressure distributions and flowpath streamtube performance estimates are made for the three Mach numbers tested.

Water impact shock test system

NASA Technical Reports Server (NTRS)

1977-01-01

The basic objective was to design, manufacture, and install a shock test system which, in part, would have the ability to subject test articles weighing up to 1,000 pounds to both half sine and/or full sine pulses having peak levels of up to 50 G's with half sine pulse durations of 100 milliseconds or full sine period duration of 200 milliseconds. The tolerances associated with the aforementioned pulses were +20% and -10% for the peak levels and plus or minus 10% for the pulse durations. The subject shock test system was to be capable of accepting test article sizes of up to 4 feet by 4 feet mounting surface by 4 feet in length.

The NO Regular Defibrillation testing In Cardioverter Defibrillator Implantation (NORDIC ICD) trial: concept and design of a randomized, controlled trial of intra-operative defibrillation testing during de novo defibrillator implantation.

PubMed

Bänsch, Dietmar; Bonnemeier, Hendrik; Brandt, Johan; Bode, Frank; Svendsen, Jesper Hastrup; Felk, Angelika; Hauser, Tino; Wegscheider, Karl

2015-01-01

Although defibrillation (DF) testing is still considered a standard procedure during implantable cardioverter-defibrillator (ICD) insertion and has been an essential element of all trials that demonstrated the survival benefit of ICD therapy, there are no large randomized clinical trials demonstrating that DF testing improves clinical outcome and if the outcome would remain the same by omitting DF testing. Between February 2011 and July 2013, we randomly assigned 1077 patients to ICD implantation with (n = 540) or without (n = 537) DF testing. The intra-operative DF testing was standardized across all participating centres. After inducing a fast ventricular tachycardia (VT) with a heart rate ≥240 b.p.m. or ventricular fibrillation (VF) with a low-energy T-wave shock, DF was attempted with an initial 15 J shock. If the shock reversed the VT or VF, DF testing was considered successful and terminated. If unsuccessful, two effective 24 J shocks were administered. If DF was unsuccessful, the system was reconfigured and another DF testing was performed. An ICD shock energy of 40 J had to be programmed in all patients for treatment of spontaneous VT/VF episodes. The primary endpoint was the average efficacy of the first ICD shock for all true VT/VF episodes in each patient during follow-up. The secondary endpoints included the frequency of system revisions, total fluoroscopy, implantation time, procedural serious adverse events, and all-cause, cardiac, and arrhythmic mortality during follow-up. Home Monitoring was used in all patients to continuously monitor the system integrity, device programming and performance. The NO Regular Defibrillation testing In Cardioverter Defibrillator Implantation (NORDIC ICD) trial is one of two large prospective randomized trials assessing the effect of DF testing omission during ICD implantation. NCT01282918. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Structure-induced switching of interpolymer adhesion at a solid-polymer melt interface.

PubMed

Jiang, Naisheng; Sen, Mani; Zeng, Wenduo; Chen, Zhizhao; Cheung, Justin M; Morimitsu, Yuma; Endoh, Maya K; Koga, Tadanori; Fukuto, Masafumi; Yuan, Guangcui; Satija, Sushil K; Carrillo, Jan-Michael Y; Sumpter, Bobby G

2018-02-14

Here we report a link between the interfacial structure and adhesive property of homopolymer chains physically adsorbed (i.e., via physisorption) onto solids. Polyethylene oxide (PEO) was used as a model and two different chain conformations of the adsorbed polymer were created on silicon substrates via the well-established Guiselin's approach: "flattened chains" which lie flat on the solid and are densely packed, and "loosely adsorbed polymer chains" which form bridges jointing up nearby empty sites on the solid surface and cover the flattened chains. We investigated the adhesion properties of the two different adsorbed chains using a custom-built adhesion testing device. Bilayers of a thick PEO overlayer on top of the flattened chains or loosely adsorbed chains were subjected to the adhesion test. The results revealed that the flattened chains do not show any adhesion even with the chemically identical free polymer on top, while the loosely adsorbed chains exhibit adhesion. Neutron reflectivity experiments corroborated that the difference in the interfacial adhesion is not attributed to the interfacial brodening at the free polymer-adsorbed polymer interface. Instead, coarse-grained molecular dynamics simulation results suggest that the tail parts of the loosely adsorbed chains act as "connector molecules", bridging the free chains and substrate surface and improving the interfacial adhesion. These findings not only shed light on the structure-property relationship at the interface, but also provide a novel approach for developing sticking/anti-sticking technologies through precise control of the interfacial polymer nanostructures.

Modeling cell adhesion and proliferation: a cellular-automata based approach.

PubMed

Vivas, J; Garzón-Alvarado, D; Cerrolaza, M

Cell adhesion is a process that involves the interaction between the cell membrane and another surface, either a cell or a substrate. Unlike experimental tests, computer models can simulate processes and study the result of experiments in a shorter time and lower costs. One of the tools used to simulate biological processes is the cellular automata, which is a dynamic system that is discrete both in space and time. This work describes a computer model based on cellular automata for the adhesion process and cell proliferation to predict the behavior of a cell population in suspension and adhered to a substrate. The values of the simulated system were obtained through experimental tests on fibroblast monolayer cultures. The results allow us to estimate the cells settling time in culture as well as the adhesion and proliferation time. The change in the cells morphology as the adhesion over the contact surface progress was also observed. The formation of the initial link between cell and the substrate of the adhesion was observed after 100 min where the cell on the substrate retains its spherical morphology during the simulation. The cellular automata model developed is, however, a simplified representation of the steps in the adhesion process and the subsequent proliferation. A combined framework of experimental and computational simulation based on cellular automata was proposed to represent the fibroblast adhesion on substrates and changes in a macro-scale observed in the cell during the adhesion process. The approach showed to be simple and efficient.

A-1 Test Stand modifications

NASA Image and Video Library

2011-09-14

Team members check the progress of a liquid nitrogen cold shock test on the A-1 Test Stand at Stennis Space Center on Sept. 15. The cold shock test is used to confirm the test stand's support system can withstand test conditions, when super-cold rocket engine propellant is piped. The A-1 Test Stand is preparing to conduct tests on the powerpack component of the J-2X rocket engine, beginning in early 2012.

Voyager: Vibration Acoustics and Pyro Shock Testing

NASA Image and Video Library

2017-07-05

An engineer works on vibration acoustics and pyro shock testing for one of NASA's Voyager spacecraft on November 18, 1976. Several of the spacecraft's science instruments are visible at left. https://photojournal.jpl.nasa.gov/catalog/PIA21733

Development of design allowables data for adhesives for attaching reusable surface insulation

NASA Technical Reports Server (NTRS)

Owen, H. P.; Carroll, M. T.

1972-01-01

Results are presented from tests to establish design allowables data for the following room temperature vulcanizing (RTV) silicone rubber based adhesives: (1) General Electric's RTV-560; (2) Dow Corning's 93-046; and (3) Martin Marietta's SLA-561. These adhesives are being evaluated for attaching reusable surface insulation to space shuttle structure.

Durability of adhesives in plywood

Treesearch

Robert H. Gillespie; Bryan H. River

1976-01-01

Seven different adhesives were evaluated for durability as plywood adhesives by exposing panels and shear-test specimens to weathering at the Madison exposure site for nearly 8 years. Wet-strength loss and wood-failure changes were measured as a function of exposure time. The method of exposure accelerated the degradation that would have resulted from exposure in most...

Tensile and shear strength of adhesives

NASA Technical Reports Server (NTRS)

Stibolt, Kenneth A.

1990-01-01

This experiment is conducted in a freshman-level course: Introduction to Engineering Materials. There are no prerequisites for the course although students should have some knowledge of basic algebra. The objectives are to tension and shear test adhesives and to determine the tensile and shear properties of adhesives. Details of equipment of procedure are given.

Evaluation of the adhesion on the nano-scaled polymeric film systems.

PubMed

Park, Tae Sung; Park, Ik Keun; Yoshida, Sanichiro

2017-04-01

We applied scanning acoustic microscopy known as the V(z) curve technique to photoresist thin-film systems for the evaluation of the adhesive strength at the film-substrate interface. Through the measurement of the SAW (Surface Acoustic Wave) velocity, the V(z) curve analysis allows us to quantify the stiffness of the film-substrate interface. In addition, we conducted a nano-scratch test to quantify the ultimate strength of the adhesion through the evaluation of the critical load. To vary the adhesive conditions, we prepared thin-film specimens with three different types of pre-coating surface treatments, i.e., oxygen-plasma bombardment, HMDS (Hexametyldisilazane) treatment and untreated. The magnitudes of the quantified stiffness and ultimate strength are found consistent with each other for all the specimens tested, indicating that the pre-coating surface treatment can strengthen both the stiffness and ultimate strength of the adhesion. The results of this study demonstrate the usefulness of the V(Z) analysis as a nondestructive method to evaluate the adhesion strength of nano-structured thin-film systems. Copyright © 2017 Elsevier B.V. All rights reserved.

A test of the adhesion approximation for gravitational clustering

NASA Technical Reports Server (NTRS)

Melott, Adrian L.; Shandarin, Sergei; Weinberg, David H.

1993-01-01

We quantitatively compare a particle implementation of the adhesion approximation to fully non-linear, numerical 'N-body' simulations. Our primary tool, cross-correlation of N-body simulations with the adhesion approximation, indicates good agreement, better than that found by the same test performed with the Zel-dovich approximation (hereafter ZA). However, the cross-correlation is not as good as that of the truncated Zel-dovich approximation (TZA), obtained by applying the Zel'dovich approximation after smoothing the initial density field with a Gaussian filter. We confirm that the adhesion approximation produces an excessively filamentary distribution. Relative to the N-body results, we also find that: (a) the power spectrum obtained from the adhesion approximation is more accurate than that from ZA or TZA, (b) the error in the phase angle of Fourier components is worse than that from TZA, and (c) the mass distribution function is more accurate than that from ZA or TZA. It appears that adhesion performs well statistically, but that TZA is more accurate dynamically, in the sense of moving mass to the right place.

A test of the adhesion approximation for gravitational clustering

NASA Technical Reports Server (NTRS)

Melott, Adrian L.; Shandarin, Sergei F.; Weinberg, David H.

1994-01-01

We quantitatively compare a particle implementation of the adhesion approximation to fully nonlinear, numerical 'N-body' simulations. Our primary tool, cross-correlation of N-body simulations with the adhesion approximation, indicates good agreement, better than that found by the same test performed with the Zel'dovich approximation (hereafter ZA). However, the cross-correlation is not as good as that of the truncated Zel'dovich approximation (TZA), obtained by applying the Zel'dovich approximation after smoothing the initial density field with a Gaussian filter. We confirm that the adhesion approximation produces an excessively filamentary distribution. Relative to the N-body results, we also find that: (a) the power spectrum obtained from the adhesion approximation is more accurate that that from ZA to TZA, (b) the error in the phase angle of Fourier components is worse that that from TZA, and (c) the mass distribution function is more accurate than that from ZA or TZA. It appears that adhesion performs well statistically, but that TZA is more accurate dynamically, in the sense of moving mass to the right place.

Influence of Nd:YAG laser on the bond strength of self-etching and conventional adhesive systems to dental hard tissues.

PubMed

Marimoto, A K; Cunha, L A; Yui, K C K; Huhtala, M F R L; Barcellos, D C; Prakki, A; Gonçalves, S E P

2013-01-01

The aim of this study was to investigate the influence of Nd:YAG laser on the shear bond strength to enamel and dentin of total and self-etch adhesives when the laser was applied over the adhesives, before they were photopolymerized, in an attempt to create a new bonding layer by dentin-adhesive melting. One-hundred twenty bovine incisors were ground to obtain flat surfaces. Specimens were divided into two substrate groups (n=60): substrate E (enamel) and substrate D (dentin). Each substrate group was subdivided into four groups (n=15), according to the surface treatment accomplished: X (Xeno III self-etching adhesive, control), XL (Xeno III + laser Nd:YAG irradiation at 140 mJ/10 Hz for 60 seconds + photopolymerization, experimental), S (acid etching + Single Bond conventional adhesive, Control), and SL (acid etching + Single Bond + laser Nd:YAG at 140 mJ/10 Hz for 60 seconds + photopolymerization, experimental). The bonding area was delimited with 3-mm-diameter adhesive tape for the bonding procedures. Cylinders of composite were fabricated on the bonding area using a Teflon matrix. The teeth were stored in water at 37°C/48 h and submitted to shear testing at a crosshead speed of 0.5 mm/min in a universal testing machine. Results were analyzed with three-way analysis of variance (ANOVA; substrate, adhesive, and treatment) and Tukey tests (α=0.05). ANOVA revealed significant differences for the substrate, adhesive system, and type of treatment: lased or unlased (p<0.05). The mean shear bond strength values (MPa) for the enamel groups were X=20.2 ± 5.61, XL=23.6 ± 4.92, S=20.8 ± 4.55, SL=22.1 ± 5.14 and for the dentin groups were X=14.1 ± 7.51, XL=22.2 ± 6.45, S=11.2 ± 5.77, SL=15.9 ± 3.61. For dentin, Xeno III self-etch adhesive showed significantly higher shear bond strength compared with Single Bond total-etch adhesive; Nd:YAG laser irradiation showed significantly higher shear bond strength compared with control (unlased). Nd:YAG laser application prior to photopolymerization of adhesive systems significantly increased the bond strength to dentin.

Evaluation of different types of enamel conditioning before application of a fissure sealant.

PubMed

Ciucchi, Philip; Neuhaus, Klaus W; Emerich, Marta; Peutzfeldt, Anne; Lussi, Adrian

2015-01-01

The aim of the study was to compare fissure sealant quality after mechanical conditioning of erbium-doped yttrium aluminium garnet (Er:YAG) laser or air abrasion prior to chemical conditioning of phosphoric acid etching or of a self-etch adhesive. Twenty-five permanent molars were initially divided into three groups: control group (n = 5), phosphoric acid etching; test group 1 (n = 10), air abrasion; and test group 2, (n = 10) Er:YAG laser. After mechanical conditioning, the test group teeth were sectioned buccolingually and the occlusal surface of one half tooth (equal to one sample) was acid etched, while a self-etch adhesive was applied on the other half. The fissure system of each sample was sealed, thermo-cycled and immersed in 5% methylene dye for 24 h. Each sample was sectioned buccolingually, and one slice was analysed microscopically. Using specialized software microleakage, unfilled margin, sealant failure and unfilled area proportions were calculated. A nonparametric ANOVA model was applied to compare the Er:YAG treatment with that of air abrasion and the self-etch adhesive with phosphoric acid (α = 0.05). Test groups were compared to the control group using Wilcoxon rank sum tests (α = 0.05). The control group displayed significantly lower microleakage but higher unfilled area proportions than the Er:YAG laser + self-etch adhesive group and displayed significantly higher unfilled margin and unfilled area proportions than the air-abrasion + self-etch adhesive group. There was no statistically significant difference in the quality of sealants applied in fissures treated with either Er:YAG laser or air abrasion prior to phosphoric acid etching, nor in the quality of sealants applied in fissures treated with either self-etch adhesive or phosphoric acid following Er:YAG or air-abrasion treatment.

[Bond strengths of absorbable polylactic acid root canal post with three different adhesives].

PubMed

Pan, Hui; Cheng, Can; Hu, Jia; Liu, He; Sun, Zhi-hui

2015-12-18

To find absorbable adhesives with suitable bonding properties for the absorbable polylactic acid root canal post. To test and compare the bond strengths of absorbable polylactic acid root canal post with three different adhesives. The absorbable polylactic acid root canal posts were used to restore the extracted teeth, using 3 different adhesives: cyanoacrylates, fibrin sealant and glass ionomer cement. The teeth were prepared into slices for micro-push-out test. The bond strength was statistically analyzed using ANOVA. The specimens were examined using microscope and the failure mode was divided into four categories: cohesive failure between absorbable polylactic acid root canal posts and adhesives, cohesive failure between dentin and adhesives, failure within the adhesives and failure within the absorbable polylactic acid root canal posts. The bond strength of cyanoacrylates [(16.83 ± 6.97) MPa] and glass ionomer cement [(12.10 ± 5.09) MPa] were significantly higher than fibrin sealant [(1.17 ± 0.50) MPa], P<0.001. There was no significant difference between cyanoacrylates and glass ionomer cement (P=0.156). In the group of cyanoacrylates, the cohesive failure between the absorbable polylactic acid root canal posts and the adhesives was 25.0%, the cohesive failure between the dentin and the adhesives was 16.7%, the failure within the adhesives was 33.3%, and the failure within the absorbable polylactic acid root canal posts was 25.0%. In the group of fibrin sealant, the cohesive failure between the absorbable polylactic acid root canal posts and the adhesives was 66.7%, the cohesive failure between the dentin and the adhesives was 22.2%, the failure within the adhesives was 11.1%. In the group of glass ionomer cement, the cohesive failure between the absorbable polylactic acid root canal posts and the adhesives was 87.5%, the failure within the adhesives was 12.5%. The major failure mode in fibrin sealant and glass ionomer cement was the cohesive failure between the absorbable polylactic acid root canal posts and the adhesives. No major failure modes were found in the group of cyanoacrylates. The bond strength of fibrin sealant is low, which cannot meet the requirement of clinical use. The bond strengths of cyanoacrylates and glass ionomer cement are suitable for clinical use. The cyanoacrylates are a kind of absorbable adhesive which has suitable bonding properties for the absorbable polylactic acid root canal post.

Plasma and energetic particle structure of a collisionless quasi-parallel shock

NASA Technical Reports Server (NTRS)

Kennel, C. F.; Scarf, F. L.; Coroniti, F. V.; Russell, C. T.; Smith, E. J.; Wenzel, K. P.; Reinhard, R.; Sanderson, T. R.; Feldman, W. C.; Parks, G. K.

1983-01-01

The quasi-parallel interplanetary shock of November 11-12, 1978 from both the collisionless shock and energetic particle points of view were studied using measurements of the interplanetary magnetic and electric fields, solar wind electrons, plasma and MHD waves, and intermediate and high energy ions obtained on ISEE-1, -2, and -3. The interplanetary environment through which the shock was propagating when it encountered the three spacecraft was characterized; the observations of this shock are documented and current theories of quasi-parallel shock structure and particle acceleration are tested. These observations tend to confirm present self consistent theories of first order Fermi acceleration by shocks and of collisionless shock dissipation involving firehouse instability.

The Shock and Vibration Bulletin. Part 1. Welcome, Keynote Address, Invited Papers, Pyrotechnic Shock, and Shock Testing and Analysis

DTIC Science & Technology

1983-05-01

DESIGN PROCEDURE M. S. IIAndal, University of Vermont, Burlington, VT Machinery Dynamics ANALYTICAL AND EXPERIMENTAL INVESTIGATION OF ROTATING BLADE... methodology to accurately predict rotor vibratory loads and has recently been initiated for detail design and bench test- coupled rotor/airframe vibrations... design methodology , a trating on the basic disciplines of aerodynamics and struc. coupled rotor/airframe vibration analysis has been developed. tural

Functionally Graded Adhesives for Composite Joints

NASA Technical Reports Server (NTRS)

Stapleton, Scott E.; Waas, Anthony M.; Arnold, Steven M.

2012-01-01

Adhesives with functionally graded material properties are being considered for use in adhesively bonded joints to reduce the peel stress concentrations located near adherend discontinuities. Several practical concerns impede the actual use of such adhesives. These include increased manufacturing complications, alterations to the grading due to adhesive flow during manufacturing, and whether changing the loading conditions significantly impact the effectiveness of the grading. An analytical study is conducted to address these three concerns. An enhanced joint finite element, which uses an analytical formulation to obtain exact shape functions, is used to model the joint. Furthermore, proof of concept testing is conducted to show the potential advantages of functionally graded adhesives. In this study, grading is achieved by strategically placing glass beads within the adhesive layer at different densities along the joint.

In Vitro Comparison of a Novel Single Probe Dual-Energy Lithotripter to Current Devices.

PubMed

Carlos, Evan C; Wollin, Daniel A; Winship, Brenton B; Jiang, Ruiyang; Radvak, Daniela; Chew, Ben H; Gustafson, Michael R; Simmons, W Neal; Zhong, Pei; Preminger, Glenn M; Lipkin, Michael E

2018-06-01

The LithoClast Trilogy is a novel single probe, dual-energy lithotripter with ultrasonic (US) vibration and electromagnetic impact forces. ShockPulse and LithoClast Select are existing lithotripters that also use a combination of US and mechanical impact energies. We compared the efficacy and tip motion of these devices in an in vitro setting. Begostones, in the ratio 15:3, were used in all trials. Test groups were Trilogy, ShockPulse, Select ultrasound (US) only, and Select ultrasound with pneumatic (USP). For clearance testing, a single investigator facile with each lithotripter fragmented 10 stones per device. For drill testing, a hands-free apparatus with a submerged balance was used to apply 1 or 2 lbs of pressure on a stone in contact with the device tip. High-speed photography was used to assess Trilogy and ShockPulse's probe tip motion. Select-USP was slowest and Trilogy fastest on clearance testing (p < 0.01). On 1 lbs drill testing, Select-US was slowest (p = 0.001). At 2 lbs, ShockPulse was faster than Select US (p = 0.027), but did not significantly outpace Trilogy nor Select-USP. At either weight, there was no significant difference between Trilogy and ShockPulse. During its US function, Trilogy's maximum downward tip displacement was 0.041 mm relative to 0.0025 mm with ShockPulse. Trilogy had 0.25 mm of maximum downward displacement during its impactor function while ShockPulse had 0.01 mm. Single probe dual-energy devices, such as Trilogy and ShockPulse, represent the next generation of lithotripters. Trilogy more efficiently cleared stone than currently available devices, which could be explained by its larger probe diameter and greater downward tip displacement during both US and impactor functions.

3D micro-crack propagation simulation at enamel/adhesive interface using FE submodeling and element death techniques.

PubMed

Liu, Heng-Liang; Lin, Chun-Li; Sun, Ming-Tsung; Chang, Yen-Hsiang

2010-06-01

This study investigates micro-crack propagation at the enamel/adhesive interface using finite element (FE) submodeling and element death techniques. A three-dimensional (3D) FE macro-model of the enamel/adhesive/ceramic subjected to shear bond testing was generated and analyzed. A 3D micro-model with interfacial bonding structure was constructed at the upper enamel/adhesive interface where the stress concentration was found from the macro-model results. The morphology of this interfacial bonding structure (i.e., resin tag) was assigned based on resin tag geometry and enamel rod arrangement from a scanning electron microscopy micrograph. The boundary conditions for the micro-model were determined from the macro-model results. A custom iterative code combined with the element death technique was used to calculate the micro-crack propagation. Parallel experiments were performed to validate this FE simulation. The stress concentration within the adhesive occurred mainly at the upper corner near the enamel/adhesive interface and the resin tag base. A simulated fracture path was found at the resin tag base along the enamel/adhesive interface. A morphological observation of the fracture patterns obtained from in vitro testing corresponded with the simulation results. This study shows that the FE submodeling and element death techniques could be used to simulate the 3D micro-stress pattern and the crack propagation noted at the enamel/adhesive interface.

Bacterial adhesion on conventional and self-ligating metallic brackets after surface treatment with plasma-polymerized hexamethyldisiloxane.

PubMed

Tupinambá, Rogerio Amaral; Claro, Cristiane Aparecida de Assis; Pereira, Cristiane Aparecida; Nobrega, Celestino José Prudente; Claro, Ana Paula Rosifini Alves

2017-01-01

Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. Hexamethyldisiloxane (HMDSO) polymer films were deposited on conventional (n = 10) and self-ligating (n = 10) stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD) radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM) analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region) and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI) and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. Significant statistical differences (p< 0.05) for surface roughness and bacterial adhesion reduction were observed on conventional brackets after surface treatment and between conventional and self-ligating brackets; no significant statistical differences were observed between self-ligating groups (p> 0.05). Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film.

Attenuation of postoperative adhesions using a modeled manual therapy.

PubMed

Bove, Geoffrey M; Chapelle, Susan L; Hanlon, Katherine E; Diamond, Michael P; Mokler, David J

2017-01-01

Postoperative adhesions are pathological attachments that develop between abdominopelvic structures following surgery. Considered unavoidable and ubiquitous, postoperative adhesions lead to bowel obstructions, infertility, pain, and reoperations. As such, they represent a substantial health care challenge. Despite over a century of research, no preventive treatment exists. We hypothesized that postoperative adhesions develop from a lack of movement of the abdominopelvic organs in the immediate postoperative period while rendered immobile by surgery and opiates, and tested whether manual therapy would prevent their development. In a modified rat cecal abrasion model, rats were allocated to receive treatment with manual therapy or not, and their resulting adhesions were quantified. We also characterized macrophage phenotype. In separate experiments we tested the safety of the treatment on a strictureplasty model, and also the efficacy of the treatment following adhesiolysis. We show that the treatment led to reduced frequency and size of cohesive adhesions, but not other types of adhesions, such as those involving intraperitoneal fatty structures. This effect was associated with a delay in the appearance of trophic macrophages. The treatment did not inhibit healing or induce undesirable complications following strictureplasty. Our results support that that maintained movements of damaged structures in the immediate postoperative period has potential to act as an effective preventive for attenuating cohesive postoperative adhesion development. Our findings lay the groundwork for further research, including mechanical and pharmacologic approaches to maintain movements during healing.

Bacterial endotoxin adhesion to different types of orthodontic adhesives

PubMed Central

ROMUALDO, Priscilla Coutinho; GUERRA, Thaís Rodrigues; ROMANO, Fábio Lourenço; da SILVA, Raquel Assed Bezerra; BRANDÃO, Izaíra Tincani; SILVA, Célio Lopes; da SILVA, Lea Assed Bezerra; NELSON-FILHO, Paulo

2017-01-01

Abstract Bacterial endotoxin (LPS) adhesion to orthodontic brackets is a known contributing factor to inflammation of the adjacent gingival tissues. Objective The aim of this study was to assess whether LPS adheres to orthodontic adhesive systems, comparing two commercial brands. Material and Methods Forty specimens were fabricated from Transbond XT and Light Bond composite and bonding agent components (n=10/component), then contaminated by immersion in a bacterial endotoxin solution. Contaminated and non-contaminated acrylic resin samples were used as positive and negative control groups, respectively. LPS quantification was performed by the Limulus Amebocyte Lysate QCL-1000™ test. Data obtained were scored and subjected to the Chi-square test using a significance level of 5%. Results There was endotoxin adhesion to all materials (p<0.05). No statistically significant difference was found between composites/bonding agents and acrylic resin (p>0.05). There was no significant difference (p>0.05) among commercial brands. Affinity of endotoxin was significantly greater for the bonding agents (p=0.0025). Conclusions LPS adhered to both orthodontic adhesive systems. Regardless of the brand, the endotoxin had higher affinity for the bonding agents than for the composites. There is no previous study assessing the affinity of LPS for orthodontic adhesive systems. This study revealed that LPS adheres to orthodontic adhesive systems. Therefore, additional care is recommended to orthodontic applications of these materials. PMID:28877283

Statistical Analysis of a Large Sample Size Pyroshock Test Data Set Including Post Flight Data Assessment. Revision 1

NASA Technical Reports Server (NTRS)

Hughes, William O.; McNelis, Anne M.

2010-01-01

The Earth Observing System (EOS) Terra spacecraft was launched on an Atlas IIAS launch vehicle on its mission to observe planet Earth in late 1999. Prior to launch, the new design of the spacecraft's pyroshock separation system was characterized by a series of 13 separation ground tests. The analysis methods used to evaluate this unusually large amount of shock data will be discussed in this paper, with particular emphasis on population distributions and finding statistically significant families of data, leading to an overall shock separation interface level. The wealth of ground test data also allowed a derivation of a Mission Assurance level for the flight. All of the flight shock measurements were below the EOS Terra Mission Assurance level thus contributing to the overall success of the EOS Terra mission. The effectiveness of the statistical methodology for characterizing the shock interface level and for developing a flight Mission Assurance level from a large sample size of shock data is demonstrated in this paper.

Computational Modeling and Experimental Validation of Shock Induced Damage in Woven E-Glass/Vinylester Laminates

NASA Astrophysics Data System (ADS)

Hufner, D. R.; Augustine, M. R.

2018-05-01

A novel experimental method was developed to simulate underwater explosion pressure pulses within a laboratory environment. An impact-based experimental apparatus was constructed; capable of generating pressure pulses with basic character similar to underwater explosions, while also allowing the pulse to be tuned to different intensities. Having the capability to vary the shock impulse was considered essential to producing various levels of shock-induced damage without the need to modify the fixture. The experimental apparatus and test method are considered ideal for investigating the shock response of composite material systems and/or experimental validation of new material models. One such test program is presented herein, in which a series of E-glass/Vinylester laminates were subjected to a range of shock pulses that induced varying degrees of damage. Analysis-test correlations were performed using a rate-dependent constitutive model capable of representing anisotropic damage and ultimate yarn failure. Agreement between analytical predictions and experimental results was considered acceptable.

Associative learning for danger avoidance nullifies innate positive chemotaxis to host olfactory stimuli in a parasitic wasp

NASA Astrophysics Data System (ADS)

Benelli, Giovanni; Stefanini, Cesare; Giunti, Giulia; Geri, Serena; Messing, Russell H.; Canale, Angelo

2014-09-01

Animals rely on associative learning for a wide range of purposes, including danger avoidance. This has been demonstrated for several insects, including cockroaches, mosquitoes, drosophilid flies, paper wasps, stingless bees, bumblebees and honeybees, but less is known for parasitic wasps. We tested the ability of Psyttalia concolor (Hymenoptera: Braconidae) females to associate different dosages of two innately attractive host-induced plant volatiles (HIPVs), ethyl octanoate and decanal, with danger (electric shocks). We conducted an associative treatment involving odours and shocks and two non-associative controls involving shocks but not odours and odours but not shocks. In shock-only and odour-only trained wasps, females preferred on HIPV-treated than on blank discs. In associative-trained wasps, however, P. concolor's innate positive chemotaxis for HIPVs was nullified (lowest HIPV dosage tested) or reversed (highest HIPV dosage tested). This is the first report of associative learning of olfactory cues for danger avoidance in parasitic wasps, showing that the effects of learning can override innate positive chemotaxes.

Dentine bond strength and antimicrobial activity evaluation of adhesive systems.

PubMed

André, Carolina Bosso; Gomes, Brenda Paula Figueiredo Almeida; Duque, Thais Mageste; Stipp, Rafael Nobrega; Chan, Daniel Chi Ngai; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

2015-04-01

This study evaluated the dentine bond strength (BS) and the antibacterial activity (AA) of six adhesives against strict anaerobic and facultative bacteria. Three adhesives containing antibacterial components (Gluma 2Bond (glutaraldehyde)/G2B, Clearfil SE Protect (MDPB)/CSP and Peak Universal Bond (PUB)/chlorhexidine) and the same adhesive versions without antibacterial agents (Gluma Comfort Bond/GCB, Clearfil SE Bond/CSB and Peak LC Bond/PLB) were tested. The AA of adhesives and control groups was evaluated by direct contact method against four strict anaerobic and four facultative bacteria. After incubation, according to the appropriate periods of time for each microorganism, the time to kill microorganisms was measured. For BS, the adhesives were applied according to manufacturers' recommendations and teeth restored with composite. Teeth (n=10) were sectioned to obtain bonded beams specimens, which were tested after artificial saliva storage for one week and one year. BS data were analyzed using two-way ANOVA and Tukey test. Saliva storage for one year reduces the BS only for GCB. In general G2B and GCB required at least 24h for killing microorganisms. PUB and PLB killed only strict anaerobic microorganisms after 24h. For CSP the average time to eliminate the Streptococcus mutans and strict anaerobic oral pathogens was 30 min. CSB showed no AA against facultative bacteria, but had AA against some strict anaerobic microorganisms. Storage time had no effect on the BS for most of the adhesives. The time required to kill bacteria depended on the type of adhesive and never was less than 10 min. Most of the adhesives showed stable bond strength after one year and the Clearfil SE Protect may be a good alternative in restorative procedures performed on dentine, considering its adequate bond strength and better antibacterial activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of Underwater Adhesives and Friction Coatings for In Situ Attachment of Fiber Optic Sensor System for Subsea Applications

NASA Technical Reports Server (NTRS)

Tang, Henry H.; Le, Suy Q.; Orndoff, Evelyne S.; Smith, Frederick D.; Tapia, Alma S.; Brower, David V.

2012-01-01

Integrity and performance monitoring of subsea pipelines and structures provides critical information for managing offshore oil and gas production operation and preventing environmentally damaging and costly catastrophic failure. Currently pipeline monitoring devices require ground assembly and installation prior to the underwater deployment of the pipeline. A monitoring device that could be installed in situ on the operating underwater structures could enhance the productivity and improve the safety of current offshore operation. Through a Space Act Agreement (SAA) between the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) and Astro Technology, Inc. (ATI), JSC provides technical expertise and testing facilities to support the development of fiber optic sensor technologies by ATI. This paper details the first collaboration effort between NASA JSC and ATI in evaluating underwater applicable adhesives and friction coatings for attaching fiber optic sensor system to subsea pipeline. A market survey was conducted to examine different commercial ]off ]the ]shelf (COTS) underwater adhesive systems and to select adhesive candidates for testing and evaluation. Four COTS epoxy based underwater adhesives were selected and evaluated. The adhesives were applied and cured in simulated seawater conditions and then evaluated for application characteristics and adhesive strength. The adhesive that demonstrated the best underwater application characteristics and highest adhesive strength were identified for further evaluation in developing an attachment system that could be deployed in the harsh subsea environment. Various friction coatings were also tested in this study to measure their shear strengths for a mechanical clamping design concept for attaching fiber optic sensor system. A COTS carbide alloy coating was found to increase the shear strength of metal to metal clamping interface by up to 46 percent. This study provides valuable data for assessing the feasibility of developing the next generation fiber optic senor system that could be retrofitted onto existing subsea pipeline structures.

Microtensile bond strength of contemporary adhesives to primary enamel and dentin.

PubMed

Marquezan, Marcela; da Silveira, Bruno Lopes; Burnett, Luiz Henrique; Rodrigues, Célia Regina Martins Delgado; Kramer, Paulo Floriani

2008-01-01

The purpose of this study was to assess bond strength of three self-etching and two total-etch adhesive systems bonded to primary tooth enamel and dentin. Forty extracted primary human molars were selected and abraded in order to create flat buccal enamel and occlusal dentin surfaces. Teeth were assigned to one of the adhesive systems: Adper Scotch Bond Multi Purpose, Adper Single Bond 2, Adper Prompt L-Pop, Clearfil SE Bond and AdheSE. Immediately to adhesive application, a composite resin (Filtek Z250) block was built up. After 3 months of water storage, each sample was sequentially sectioned in order to obtain sticks with a square cross-sectional area of about 0.72 mm2. The specimens were fixed lengthways to a microtensile device and tested using a universal testing machine with a 50-N load cell at a crosshead speed of 0.5 mm/min. Microtensile bond strength values were recorded in MPa and compared by Analysis of Variance and the post hoc Tukey test (a = 0.05). In enamel, Clearfil SE Bond presented the highest values, followed by Adper Single Bond 2, AdheSE and Adper Scotch Bond Multi Purpose, without significant difference. The highest values in dentin were obtained with Adper Scotch Bond Multi Purpose and all other adhesives did not present significant different values from that, except Adper Prompt L-Pop that achieved the lowest bond strength in both substrates. Adper Scotch Bond Multi Purpose and Adper Single Bond 2 presented significantly lower values in enamel than in dentin although all other adhesives presented similar results in both substrates. contemporary adhesive systems present similar behaviors when bonded to primary teeth, with the exception of the one-step self-etching system; and self-etching systems can achieve bond strength values as good in enamel as in dentin of primary teeth.

BOND STRENGTH AND MORPHOLOGY OF ENAMEL USING SELF-ETCHING ADHESIVE SYSTEMS WITH DIFFERENT ACIDITIES

PubMed Central

Moura, Sandra Kiss; Reis, Alessandra; Pelizzaro, Arlete; Dal-Bianco, Karen; Loguercio, Alessandro Dourado; Arana-Chavez, Victor Elias; Grande, Rosa Helena Miranda

2009-01-01

Objectives: To assess the bond strength and the morphology of enamel after application of self-etching adhesive systems with different acidities. The tested hypothesis was that the performance of the self-etching adhesive systems does not vary for the studied parameters. Material and methods: Composite resin (Filtek Z250) buildups were bonded to untreated (prophylaxis) and treated (burcut or SiC-paper) enamel surfaces of third molars after application of four self-etching and two etch-and-rinse adhesive systems (n=6/condition): Clearfil SE Bond (CSE); OptiBond Solo Plus Self-Etch (OP); AdheSe (AD); Tyrian Self Priming Etching (TY), Adper Scotchbond Multi-Purpose Plus (SBMP) and Adper Single Bond (SB). After storage in water (24 h/37°C), the bonded specimens were sectioned into sticks with 0.8 mm2 cross-sectional area and the microtensile bond strength was tested at a crosshead speed of 0.5 mm/min. The mean bond strength values (MPa) were subjected to two-way ANOVA and Tukey's test (α=0.05). The etching patterns of the adhesive systems were also observed with a scanning electron microscope. Results: The main factor adhesive system was statistically significant (p<0.05). The mean bond strength values (MPa) and standard deviations were: CSE (20.5±3.5), OP (11.3±2.3), AD (11.2±2.8), TY (11.1±3.0), SBMP (21.9±4.0) and SB (24.9±3.0). Different etching patterns were observed for the self-etching primers depending on the enamel treatment and the pH of the adhesive system. Conclusion: Although there is a tendency towards using adhesive systems with simplified application procedures, this may compromise the bonding performance of some systems to enamel, even when the prismless enamel is removed. PMID:19668991

Torque resistance of impression copings after direct implant impression: An in vitro evaluation of impression materials with and without adhesive.

PubMed

Auroy, Pascal; Nicolas, Emanuel; Bedouin, Yvan

2017-01-01

No data are available on the ability of an impression coping to resist the manual placement of an abutment replica (implant analog) during prosthodontic laboratory procedures after a direct (pick-up) impression. The purpose of this in vitro study was to evaluate the torque resistance of impression copings after a direct impression, that is, the amount of rotational torque sufficient to induce irreversible displacement of impression copings in the impression material bulk once the impression has been made. A reference model with 5 abutment replicas was constructed. Five impression copings were screwed onto the abutment replicas, and standardized impressions were made. A controlled twisting force was applied to each impression coping. A torque tester recorded the torque variation. Three elastomeric impression materials were tested. ANOVA and the Tukey test (α=.05) were performed using an average of 30 measurements per impression material, with and without adhesive. ANOVA and the Tukey test results showed that the adhesive, cohesive, and mechanical bonds between the impression coping and the impression material depended greatly on the type of material and that the average rupture threshold of these bonds was statistically significantly different in pairwise comparisons (P<.05). The curve analysis showed that when the impression materials are used with adhesives, the deformation of the interface is irreversible beyond 5 Ncm of torque. The polyether impression material is the direct impression material that showed the highest breakdown threshold for adhesive bonding when used without an adhesive. The use of an adhesive on impression copings leads to irreversible deformation of the interface at torque stresses well below the adhesive bond threshold of the same materials used without an adhesive. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

A test of Lee's quasi-linear theory of ion acceleration by interplanetary traveling shocks

NASA Technical Reports Server (NTRS)

Kennel, C. F.; Coroniti, F. V.; Scarf, F. L.; Livesey, W. A.; Russell, C. T.; Smith, E. J.

1986-01-01

Lee's (1983) quasi-linear theory of ion acceleration is tested using ISEE-3 measurements of the November 12, 1978 quasi-parallel interplanetary shock. His theory accounts with varying degrees of precision for the energetic proton spatial profiles; the dependence of the spectral index of the power law proton velocity distribution upon the shock compression ratio; the power law dependence of the upstream proton scalelength upon energy; the absolute magnitude of the upstream proton scale length; the behavior of the energetic proton anisotropy upstream and downstream of the shock; the behavior of the alpha-particle proton ratio upstream; the equality of the spatial scale lengths at the shock of the upstream waves and of the protons that resonate with them; and the dependence of the integrated wave energy density upon the proton energy density at the shock. However, the trace magnetic field frequency spectra disagree with his theory in two ways. The part of the spectrum that can resonate with the observed protons via first-order cyclotron resonance is flat, whereas Lee's theory predicts an f exp - 7/4 frequency dependence for the November 12 shock. Higher frequency waves, which could not resonate with the observed upstream protons, increased in amplitude as the shock approached, suggesting that they too were generated by the shock.

Low Energy Multi-Stage Atrial Defibrillation Therapy Terminates Atrial Fibrillation with Less Energy than a Single Shock

PubMed Central

Li, Wenwen; Janardhan, Ajit H.; Fedorov, Vadim V.; Sha, Qun; Schuessler, Richard B.; Efimov, Igor R.

2011-01-01

Background Implantable device therapy of atrial fibrillation (AF) is limited by pain from high-energy shocks. We developed a low-energy multi-stage defibrillation therapy and tested it in a canine model of AF. Methods and Results AF was induced by burst pacing during vagus nerve stimulation. Our novel defibrillation therapy consisted of three stages: ST1 (1-4 low energy biphasic shocks), ST2 (6-10 ultra-low energy monophasic shocks), and ST3 (anti-tachycardia pacing). Firstly, ST1 testing compared single or multiple monophasic (MP) and biphasic (BP) shocks. Secondly, several multi-stage therapies were tested: ST1 versus ST1+ST3 versus ST1+ST2+ST3. Thirdly, three shock vectors were compared: superior vena cava to distal coronary sinus (SVC>CSd), proximal coronary sinus to left atrial appendage (CSp>LAA) and right atrial appendage to left atrial appendage (RAA>LAA). The atrial defibrillation threshold (DFT) of 1BP shock was less than 1MP shock (0.55 ± 0.1 versus 1.38 ± 0.31 J; p =0.003). 2-3 BP shocks terminated AF with lower peak voltage than 1BP or 1MP shock and with lower atrial DFT than 4 BP shocks. Compared to ST1 therapy alone, ST1+ST3 lowered the atrial DFT moderately (0.51 ± 0.46 versus 0.95 ± 0.32 J; p = 0.036) while a three-stage therapy, ST1+ST2+ST3, dramatically lowered the atrial DFT (0.19 ± 0.12 J versus 0.95 ± 0.32 J for ST1 alone, p=0.0012). Finally, the three-stage therapy ST1+ST2+ST3 was equally effective for all studied vectors. Conclusions Three-stage electrotherapy significantly reduces the AF defibrillation threshold and opens the door to low energy atrial defibrillation at or below the pain threshold. PMID:21980076

Cold Shock as a Screen for Genes Involved in Cold Acclimatization in Neurospora crassa

PubMed Central

Watters, Michael K.; Manzanilla, Victor; Howell, Holly; Mehreteab, Alexander; Rose, Erik; Walters, Nicole; Seitz, Nicholas; Nava, Jacob; Kekelik, Sienna; Knuth, Laura; Scivinsky, Brianna

2018-01-01

When subjected to rapid drops of temperature (cold shock), Neurospora responds with a temporary shift in its morphology. This report is the first to examine this response genetically. We report here the results of a screen of selected mutants from the Neurospora knockout library for alterations in their morphological response to cold shock. Three groups of knockouts were selected to be subject to this screen: genes previously suspected to be involved in hyphal development as well as knockouts resulting in morphological changes; transcription factors; and genes homologous to E. coli genes known to alter their expression in response to cold shock. A total of 344 knockout strains were subjected to cold shock. Of those, 118 strains were identified with altered responses. We report here the cold shock morphologies and GO categorizations of strains subjected to this screen. Of strains with knockouts in genes associated with hyphal growth or morphology, 33 of 131 tested (25%) showed an altered response to cold shock. Of strains with knockouts in transcription factor genes, 30 of 145 (20%) showed an altered response to cold shock. Of strains with knockouts in genes homologous to E. coli genes which display altered levels of transcription in response to cold shock, a total of 55 of 68 tested (81%) showed an altered cold shock response. This suggests that the response to cold shock in these two organisms is largely shared in common. PMID:29563189

Shock tubes and waves; Proceedings of the Fourteenth International Symposium on Shock Tubes and Shock Waves, University of Sydney, Sydney, Australia, August 19-22, 1983

NASA Astrophysics Data System (ADS)

Archer, R. D.; Milton, B. E.

Techniques and facilities are examined, taking into account compressor cascades research using a helium-driven shock tube, the suppression of shocks on transonic airfoils, methods of isentropically achieving superpressures, optimized performance of arc heated shock tubes, pressure losses in free piston driven shock tubes, large shock tubes designed for nuclear survivability testing, and power-series solutions of the gasdynamic equations for Mach reflection of a planar shock by a wedge. Other subjects considered are related to aerodynamics in shock tubes, shocks in dusty gases, chemical kinetics, and lasers, plasmas, and optical methods. Attention is given to vapor explosions and the blast at Mt. St. Helens, combustion reaction mechanisms from ignition delay times, the development and use of free piston wind tunnels, models for nonequilibrium flows in real shock tubes, air blast measuring techniques, finite difference computations of flow about supersonic lifting bodies, and the investigation of ionization relaxation in shock tubes.

Materials corrosion and protection from first principles

NASA Astrophysics Data System (ADS)

Johnson, Donald F.

Materials erode under environmental stresses such as high temperature, high pressure, and mechanical shock/stress, but erosion is often exacerbated by chemical corrosion. In this dissertation, periodic density functional theory (DFT) is employed to simulate interfacial adhesion, absorption kinetics, bulk diffusion, and other material phenomena (e.g., hydrogen-enhanced decohesion and shock-induced phase changes) with the intention of understanding corrosion and subsequent failure processes and guiding the design of new protective coatings. This work examines corrosion and/or protection of materials ( i.e., Fe, Ni, W) with important applications: structural steel, gun tubes, high-pressure oil recovery vessels, jet engine turbine blades, and fusion reactor walls. We use DFT to model the pressure-induced, bcc-to-hcp phase transformation in Fe, in which a new low energy pathway is predicted exhibiting nonadiabatic behavior coupling magnetic and structural changes. Protection of steel is addressed in two aspects: interfacial adhesion of protective coatings and assessment of corrosion resistance provided by a surface alloy. First, the current chrome-coated steel system is examined where extremely strong adhesion is predicted at the Cr/Fe interface originating in strong spin correlations. A ceramic coating, SiC, is considered as a possible replacement for Cr. Strong adhesion is predicted, especially for C-Fe interfacial bonds. To assess corrosion resistance, we model ingress of two common corrosive elements, H and C, into two Fe alloys, FeAl and Fe3Si. Adsorption and absorption thermodynamics and kinetics, as well as bulk dissolution and diffusion are calculated in order to determine whether these two alloys can inhibit uptake of H and C. Relative to pure Fe, dissolved H and C are less stable in the alloys, as the dissolution enthalpy is predicted to be more endothermic. Overall, the energy barriers and rate constants for adsorbed H/C diffusing into Fe3Si subsurface layers suggests that alloying Fe with Si can be an effective means to limit uptake of these elements into steel. Spallation of protective layers on jet engine turbine blades is a problem that arises during thermal cycling. An alternative thermal barrier coating system involving MoSi2 is considered and calculations predict strong adhesion at the MoSi2/Ni interface. The interfacial bonding structure reveals a mixture of metallic and covalent cross-interface bonds. The adhesion energy is similar across all three MoSi2 facets studied. Upon exposure to oxygen, this MoSi2 alloy will form a strongly adhered oxide scale, which in turn may strongly adhere the heat shield material (yttria-stabilized zirconia), thereby potentially extending the lifetime of the barrier coating. Lastly, the interaction of hydrogen isotopes (fusion fuel) with tungsten (a proposed fusion reactor wall material) is examined. Exothermic dissociative adsorption is predicted, along with endothermic absorption and dissolution. Surface-to-subsurface diffusion energy barriers for H incorporation into bulk W are large and the corresponding outward diffusion barriers are very small. In bulk W, deep energetic traps (trapping multiple H atoms) are predicted at vacancy defects. Thus, under high neutron fluxes that will produce vacancies in W, H are predicted to collect at these vacancies. In turn, locally high concentrations of H at such vacancies will enhance decohesion of bulk W, consistent with observed blistering under deuterium implantation. Limiting vacancy formation may be key to the survival of W as a fusion reactor wall material.

Experimental study on a heavy-gas cylinder accelerated by cylindrical converging shock waves

NASA Astrophysics Data System (ADS)

Si, T.; Zhai, Z.; Luo, X.; Yang, J.

2014-01-01

The Richtmyer-Meshkov instability behavior of a heavy-gas cylinder accelerated by a cylindrical converging shock wave is studied experimentally. A curved wall profile is well-designed based on the shock dynamics theory [Phys. Fluids, 22: 041701 (2010)] with an incident planar shock Mach number of 1.2 and a converging angle of in a mm square cross-section shock tube. The cylinder mixed with the glycol droplets flows vertically through the test section and is illuminated horizontally by a laser sheet. The images obtained only one per run by an ICCD (intensified charge coupled device) combined with a pulsed Nd:YAG laser are first presented and the complete evolution process of the cylinder is then captured in a single test shot by a high-speed video camera combined with a high-power continuous laser. In this way, both the developments of the first counter-rotating vortex pair and the second counter-rotating vortex pair with an opposite rotating direction from the first one are observed. The experimental results indicate that the phenomena induced by the converging shock wave and the reflected shock formed from the center of convergence are distinct from those found in the planar shock case.

Computational considerations for the simulation of shock-induced sound

NASA Technical Reports Server (NTRS)

Casper, Jay; Carpenter, Mark H.

1996-01-01

The numerical study of aeroacoustic problems places stringent demands on the choice of a computational algorithm, because it requires the ability to propagate disturbances of small amplitude and short wavelength. The demands are particularly high when shock waves are involved, because the chosen algorithm must also resolve discontinuities in the solution. The extent to which a high-order-accurate shock-capturing method can be relied upon for aeroacoustics applications that involve the interaction of shocks with other waves has not been previously quantified. Such a study is initiated in this work. A fourth-order-accurate essentially nonoscillatory (ENO) method is used to investigate the solutions of inviscid, compressible flows with shocks in a quasi-one-dimensional nozzle flow. The design order of accuracy is achieved in the smooth regions of a steady-state test case. However, in an unsteady test case, only first-order results are obtained downstream of a sound-shock interaction. The difficulty in obtaining a globally high-order-accurate solution in such a case with a shock-capturing method is demonstrated through the study of a simplified, linear model problem. Some of the difficult issues and ramifications for aeroacoustics simulations of flows with shocks that are raised by these results are discussed.

Characterization of laser-driven shock waves in solids using a fiber optic pressure probe

DOE PAGES

Cranch, Geoffrey A.; Lunsford, Robert; Grun, Jacob; ...

2013-11-08

Measurement of laser-driven shock wave pressure in solid blocks of polymethyl methacrylate is demonstrated using fiber optic pressure probes. Three probes based on a fiber Fabry–Perot, fiber Bragg grating, and interferometric fiber tip sensor are tested and compared. Shock waves are generated using a high-power laser focused onto a thin foil target placed in close proximity to the test blocks. The fiber Fabry–Perot sensor appears capable of resolving the shock front with a rise time of 91 ns. As a result, the peak pressure is estimated, using a separate shadowgraphy measurement, to be 3.4 GPa.