Drying shrinkage problems in high PI subgrade soils.

DOT National Transportation Integrated Search

2014-01-01

The main objective of this study was to investigate the longitudinal cracking in pavements due to drying : shrinkage of high PI subgrade soils. The study involved laboartory soil testing and modeling. The : shrinkage cracks usually occur within the v...

PLASTIC SHRINKAGE CONTROLLING EFFECT BY POLYPROPYLENE SHORT FIBER WITH HYDROPHILY

NASA Astrophysics Data System (ADS)

Hosoda, Akira; Sadatsuki, Yoshitomo; Oshima, Akihiro; Ishii, Akina; Tsubaki, Tatsuya

The aim of this research is to clarify the mechanism of controlling plastic shrinkage crack by adding small amout of synthetic short fiber, and to propose optimum polypropylene short fiber to control plastic shrinkage crack. In this research, the effect of the hydrophily of polypropylene fiber was investigated in the amount of plastic shrinkage of mortar, total area of plastic shrinkage crack, and bond properties between fiber and mortar. The plastic shrinkage test of morar was conducted under high temperature, low relative humidity, and constant wind velocity. When polypropylene fiber had hydrophily, the amount of plastic shrinkage of mortar was restrained, which was because cement paste in morar was captured by hydrophilic fiber and then bleeding of mortar was restrained. With hydrophily, plastic shrinkage of mortar was restrained and bridging effect was improved due to better bond, which led to remarkable reduction of plastic shrinkage crack. Based on experimental results, the way of developing optimum polypropylene short fiber for actual construction was proposed. The fiber should have large hydrophily and small diameter, and should be used in as small amount as possible in order not to disturb workability of concrete.

Restrained shrinkage cracking of cementitious composites containing soft PCM inclusions: A paste (matrix) controlled response

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

Wei, Zhenhua; Falzone, Gabriel; Das, Sumanta

The addition of phase change materials (PCMs) has been proposed as a way to mitigate thermal cracking in cementitious materials. However, the addition of PCMs, i.e., soft inclusions, degrades the compressive strength of cementitious composites. From a strength-of-materials viewpoint, such reductions in strength are suspected to increase the tendency of cementitious materials containing PCMs to crack under load (e.g., volume instability-induced stresses resulting from thermal and/or hygral deformations). Based on detailed assessments of free and restrained shrinkage, elastic modulus, and tensile strength, this study shows that the addition of PCMs does not alter the cracking sensitivity of the material. Inmore » fact, the addition of PCMs (or other soft inclusions) enhances the cracking resistance as compared to a plain cement paste or composites containing equivalent dosages of (stiff) quartz inclusions. This is because composites containing soft inclusions demonstrate benefits resulting from crack blunting and deflection, and improved stress relaxation. As a result, although the tensile stress at failure remains similar, the time to failure (i.e., macroscopic cracking) of PCM-containing composites is considerably extended. More generally, the outcomes indicate that dosages of soft(er) inclusions, and the resulting decrease in compressive strength does not amplify the cracking risk of cementitious composites.« less

The influence of shrinkage-cracking on the drying behaviour of White Portland cement using Single-Point Imaging (SPI).

PubMed

Beyea, S D; Balcom, B J; Bremner, T W; Prado, P J; Cross, A R; Armstrong, R L; Grattan-Bellew, P E

1998-11-01

The removal of water from pores in hardened cement paste smaller than 50 nm results in cracking of the cement matrix due to the tensile stresses induced by drying shrinkage. Cracks in the matrix fundamentally alter the permeability of the material, and therefore directly affect the drying behaviour. Using Single-Point Imaging (SPI), we obtain one-dimensional moisture profiles of hydrated White Portland cement cylinders as a function of drying time. The drying behaviour of White Portland cement, is distinctly different from the drying behaviour of related concrete materials containing aggregates.

Autogenous healing of sea-water exposed mortar: Quantification through a simple and rapid permeability test

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

Palin, D., E-mail: d.palin@tudelft.nl; Jonkers, H. M.; Wiktor, V.

Concrete has an autogenous ability to heal cracks potentially contributing to its functional water tightness and durability. Here, we quantify the crack-healing capacity of sea-water submerged mortar specimens through a simple and rapid permeability test. Defined crack width geometries were created in blast furnace slag cement specimens allowing healed specimens to be quantified against unhealed specimens. Specimens with 0.2 mm wide cracks were not permeable after 28 days submersion. Specimens with 0.4 mm cracks had decreases in permeability of 66% after 28 days submersion, and 50–53% after 56 days submersion. Precipitation of aragonite and brucite in the cracks was themore » main cause of crack healing. Healing potential was dependent on the initial crack width, thermodynamic considerations and the amount of ions available in the crack. To our knowledge, this is the first study to quantify the functional autogenous healing capacity of cracked sea-water exposed cementitious specimens.« less

New methods to quantify the cracking performance of cementitious systems made with internal curing

NASA Astrophysics Data System (ADS)

Schlitter, John L.

which is located outside of the sample to provide restraint against expansion. Second, the standard ring test is a passive test that only relies on the autogenous and drying shrinkage of the mixture to induce cracking. The dual ring test can be an active test because it has the ability to vary the temperature of the specimen in order to induce thermal stress and produce cracking. This ability enables the study of the restrained cracking capacity as the mixture ages in order to quantify crack sensitive periods of time. Measurements made with the dual ring quantify the benefits from using larger amounts of internal curing. Mixtures that resupplied internal curing water to match that of chemical shrinkage could sustain three times the magnitude of thermal change before cracking. The second device discussed in this thesis is a large scale slab testing device. This device tests the cracking potential of 15' long by 4" thick by 24" wide slab specimens in an environmentally controlled chamber. The current standard testing devices can be considered small scale and encounter problems when linking their results to the field due to size effects. Therefore, the large scale slab testing device was developed in order to calibrate the results of smaller scale tests to real world field conditions such as a pavement or bridge deck. Measurements made with the large scale testing device showed that the cracking propensity of the internally cured mixtures was reduced and that a significant benefit could be realized.

Comparison of shrinkage related properties of various patch repair materials

NASA Astrophysics Data System (ADS)

Kristiawan, S. A.; Fitrianto, R. S.

2017-02-01

A patch repair material has been developed in the form of unsaturated polyester resin (UPR)-mortar. The performance and durability of this material are governed by its compatibility with the concrete being repaired. One of the compatibility issue that should be tackled is the dimensional compatibility as a result of differential shrinkage between the repair material and the concrete substrate. This research aims to evaluate such shrinkage related properties of UPR-mortar and to compare with those of other patch repair materials. The investigation includes the following aspects: free shrinkage, resistance to delamination and cracking. The results indicate that UPR-mortar poses a lower free shrinkage, lower risk of both delamination and cracking tendency in comparison to other repair materials.

Autogenous Crack Control during Construction Phases of MOSE Venice Dams

NASA Astrophysics Data System (ADS)

Bertagnoli, Gabriele; Anerdi, Constanza; Malavisi, Marzia; Zoratto, Nadia

2017-10-01

The design of concrete structures exposed to severe environmental attack, like in marine environment, requires serious attention for concrete durability. Early age cracking due to autogenous deformations can be detrimental to the performance of tidal structures. The study of the structural effects of hydration heat and rheological behaviour of a set of huge concrete structures of the Mobile Venice Dams known with the MOSE acronym (Experimental Electromechanical Module) is presented in this paper. Together with other measures such as coastal reinforcement, the raising of quaysides, and the paving and improvement of the lagoon, MOSE is designed to protect Venice and the lagoon from tides of up to 3 meters. Construction began simultaneously in 2003 at all three lagoon inlets, and the project has been completed in 2014. Floods have caused damage since ancient times and have become more frequent and intense as a result of the combined effect of eustatism (a rise in sea level) and subsidence (a drop in land level) caused by natural and man-induced phenomena. Nowadays, towns and villages in the lagoon are about 23 cm lower with respect to the water level than at the beginning of the 1900s. Each year, floods can cause serious problems for the inhabitants as well as deterioration of architecture, urban structures and the ecosystem. Over the entire lagoon area, there is also a constant risk of a catastrophic event such as that of 4 November 1966, when a tide of 194 cm submerged Venice, Chioggia and the other built-up areas.

Review and specification for shrinkage cracks of bridge decks : final report.

DOT National Transportation Integrated Search

2016-12-01

An existing standard method ASTM C157 is used to determine the length change or free shrinkage of an unrestrained concrete specimen. However, in bridge decks, the concrete is actually under restrained conditions, and thus free shrinkage test methods ...

Shrinkage and durability study of bridge deck concrete.

DOT National Transportation Integrated Search

2010-12-01

The Mississippi Department of Transportation is incorporating changes to material : specifications and construction procedures for bridge decks in an effort to reduce shrinkage : cracking. These changes are currently being implemented into a limited ...

Use of a porcine collagen matrix as an alternative to autogenous tissue for grafting oral soft tissue defects.

PubMed

Herford, Alan S; Akin, Lee; Cicciu, Marco; Maiorana, Carlo; Boyne, Philip J

2010-07-01

Soft tissue grafting is often required to correct intraoral mucosal deficiencies. Autogenous grafts have disadvantages including an additional harvest site with its associated pain and morbidity and, sometimes, poor quality and limited amount of the graft. Porcine collagen matrices have the potential to be helpful for grafting of soft tissue defects. Thirty consecutive patients underwent intraoral grafting to re-create missing soft tissue. Defects ranged in size from 50 to 900 mm(2). Porcine collagen matrices were used to reconstruct missing tissue. Indications included preprosthetic (22), followed by tumor removal (5), trauma (2), and release of cheek ankylosis (1). The primary efficacy parameters evaluated were the degree of lateral and/or alveolar extension and the evaluation of re-epithelialization and shrinkage of the grafted area. Overall, the percentage of shrinkage of the graft was 14% (range, 5%-20%). The amount of soft tissue extension averaged 3.4 mm (range, 2-10 mm). The secondary efficacy parameters included hemostatic effect, pain evaluation, pain and discomfort, and clinical evaluation of the grafted site. All patients reported minimal pain and swelling associated with the grafted area. No infections were noted. This porcine collagen matrix provides a biocompatible surgical material as an alternative to an autogenous transplant, thus obviating the need to harvest soft tissue autogenous grafts from other areas of the oral cavity. Copyright 2010 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Effects of powder characteristics on injection molding and burnout cracking

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

Bandyopadhyay, G.; French, K.W.

Silicon nitride particle size and size distributions were varied widely to determine their effects on burnout cracking of injection-molded test parts containing thick and thin sections. Elimination of internal cracking required significant burnout shrinkage, which did not occur by changes of particle size and size distribution. However, isopressing of test parts after burnout provided the dimensional shrinkage necessary for producing crack-free components.

Development of early age shrinkage stresses in reinforced concrete bridge decks

NASA Astrophysics Data System (ADS)

William, Gergis W.; Shoukry, Samir N.; Riad, Mourad Y.

2008-12-01

This paper describes the instrumentation and data analysis of a reinforced concrete bridge deck constructed on 3-span continuous steel girders in Evansville, West Virginia. An instrumentation system consisting of 232 sensors is developed and implemented specifically to measure strains and temperature in concrete deck, strains in longitudinal and transverse rebars, the overall contraction and expansion of concrete deck, and crack openings. Data from all sensors are automatically collected every 30 minutes starting at the time of placing the concrete deck. Measured strain and temperature time-histories were used to calculate the stresses, which were processed to attenuate the thermal effects due to daily temperature changes and isolate the drying shrinkage component. The results indicated that most of concrete shrinkage occurs during the first three days. Under the constraining effects from stay-in-place forms and reinforcement, early age shrinkage leads to elevated longitudinal stress, which is the main factor responsible for crack initiation.

Geosynthetics for reflective crack control

DOT National Transportation Integrated Search

1999-03-01

Reflective cracking due to shrinkage and brittleness in asphalt pavements can seriously degrade an asphalt overlay before it is near its design life. Geosynthetics have been used to impede the reflection of existing transverse cracking to the new ove...

Shrinkage modeling of concrete reinforced by palm fibres in hot dry environments

NASA Astrophysics Data System (ADS)

Akchiche, Hamida; Kriker, Abdelouahed

2017-02-01

The cement materials, such as concrete and conventional mortar present very little resistance to traction and cracking, these hydraulic materials which induces large withdrawals on materials and cracks in structures. The hot dry environments such as: the Saharan regions of Algeria, Indeed, concrete structures in these regions are very fragile, and present high shrinkage. Strengthening of these materials by fibers can provide technical solutions for improving the mechanical performance. The aim of this study is firstly, to reduce the shrinkage of conventional concrete with its reinforcement with date palm fibers. In fact, Algeria has an extraordinary resources in natural fibers (from Palm, Abaca, Hemp) but without valorization in practical areas, especially in building materials. Secondly, to model the shrinkage behavior of concrete was reinforced by date palm fibers. In the literature, several models for still fiber concrete were founded but few are offers for natural fiber concretes. To do so, a still fiber concretes model of YOUNG - CHERN was used. According to the results, a reduction of shrinkage with reinforcement by date palm fibers was showed. A good ability of molding of shrinkage of date palm reinforced concrete with YOUNG - CHERN Modified model was obtained. In fact, a good correlation between experimental data and the model data was recorded.

Shrinkage stress in concrete under dry-wet cycles: an example with concrete column

NASA Astrophysics Data System (ADS)

Gao, Yuan; Zhang, Jun; Luosun, Yiming

2014-02-01

This paper focuses on the simulation of shrinkage stress in concrete structures under dry-wet environments. In the modeling, an integrative model for autogenous and drying shrinkage predictions of concrete under dry-wet cycles is introduced first. Second, a model taking both cement hydration and moisture diffusion into account synchronously is used to calculate the distribution of interior humidity in concrete. Using the above two models, the distributions of shrinkage strain and stress in concrete columns made by normal and high strength concrete respectively under dry-wet cycles are calculated. The model results show that shrinkage gradient along the radial direction of the column from the center to outer surface increases with age as the outer circumference suffers to dry. The maximum and minimum shrinkage occur at the outer surface and the center of the column, respectively, under drying condition. As wetting starts, the shrinkage strain decreases with increase of interior humidity. The closer to the wetting face, the higher the humidity and the lower the shrinkage strain, as well as the lower the shrinkage stress. As results of the dry-wet cycles acting on the outer circumference of the column, cyclic stress status is developed within the area close to the outer surface of the column. The depth of the influencing zone of dry-wet cyclic action is influenced by concrete strength and dry-wet regime. For low strength concrete, relatively deeper influencing zone is expected compared with that of high strength concrete. The models are verified by concrete-steel composite ring tests and a good agreement between model and test results is found.

Research notes : geosynthetic materials in reflective crack prevention.

DOT National Transportation Integrated Search

2007-06-01

Extension of transverse cracks across roadway travel lanes is common in Oregon. Cracks form as a result of shrinkage and brittleness during very cold temperatures. These cracks deteriorate over time, spalling and creating bumpy riding surfaces. Prema...

Geosynthetic materials in reflective crack prevention.

DOT National Transportation Integrated Search

2007-07-01

Reflective cracking due to shrinkage and brittleness in asphalt pavements can seriously degrade an asphalt overlay : before it is near the end of its design life. Geosynthetics have been used to impede the reflection of existing : transverse cracking...

GTA weld cracking-alloy 625 to 304L

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

Patterson, R.A.; Milewski, J.O.

1985-08-01

Autogenous gas tungsten arc welds joining alloy 625 and 304L stainless steel were found to be susceptible to weld solidification cracking. Utilization of pulsed current GTA welding produced a higher sensitivity to solidification cracks than continuous current welding. Spot Varestraint tests show that the sensitivity of this dissimilar metal combination to cracking exists over the entire range of dilutions while the greatest sensitivity is in 304L stainless steel rich compositions. Auger electron spectroscopy indicates that segregation of sulfur and phosphorous to the interdendritic phase promotes the hot cracking.

Bridge decks : mitigation of cracking and increased durability.

DOT National Transportation Integrated Search

2013-07-01

This report discusses the application of expansive cements (Type K and Type G) and shrinkage-reducing admixtures (SRAs) in : reducing the cracking due to drying shrinkage. The Type K expansive cement contained portland cement and calcium : sulfoalumi...

Drying shrinkage problems in high-plastic clay soils in Oklahoma.

DOT National Transportation Integrated Search

2013-08-01

Longitudinal cracking in pavements due to drying shrinkage of high-plastic subgrade soils has been a major : problem in Oklahoma. Annual maintenance to seal and repair these distress problems costs significant amount of : money to the state. The long...

AutoGen Version 5.0

NASA Technical Reports Server (NTRS)

Gladden, Roy E.; Khanampornpan, Teerapat; Fisher, Forest W.

2010-01-01

Version 5.0 of the AutoGen software has been released. Previous versions, variously denoted Autogen and autogen, were reported in two articles: Automated Sequence Generation Process and Software (NPO-30746), Software Tech Briefs (Special Supplement to NASA Tech Briefs), September 2007, page 30, and Autogen Version 2.0 (NPO- 41501), NASA Tech Briefs, Vol. 31, No. 10 (October 2007), page 58. To recapitulate: AutoGen (now signifying automatic sequence generation ) automates the generation of sequences of commands in a standard format for uplink to spacecraft. AutoGen requires fewer workers than are needed for older manual sequence-generation processes, and greatly reduces sequence-generation times. The sequences are embodied in spacecraft activity sequence files (SASFs). AutoGen automates generation of SASFs by use of another previously reported program called APGEN. AutoGen encodes knowledge of different mission phases and of how the resultant commands must differ among the phases. AutoGen also provides means for customizing sequences through use of configuration files. The approach followed in developing AutoGen has involved encoding the behaviors of a system into a model and encoding algorithms for context-sensitive customizations of the modeled behaviors. This version of AutoGen addressed the MRO (Mars Reconnaissance Orbiter) primary science phase (PSP) mission phase. On previous Mars missions this phase has more commonly been referred to as mapping phase. This version addressed the unique aspects of sequencing orbital operations and specifically the mission specific adaptation of orbital operations for MRO. This version also includes capabilities for MRO s role in Mars relay support for UHF relay communications with the MER rovers and the Phoenix lander.

Geosynthetics for reflective crack control : construction report.

DOT National Transportation Integrated Search

1999-03-01

Reflective cracking due to shrinkage and brittleness in asphalt pavements can seriously degrade an asphalt overlay before it is near its design life. Geosynthetics have been used to impede the reflection of existing transverse cracking to the new ove...

Autogen Version 2.0

NASA Technical Reports Server (NTRS)

Gladden, Roy

2007-01-01

Version 2.0 of the autogen software has been released. "Autogen" (automated sequence generation) signifies both a process and software used to implement the process of automated generation of sequences of commands in a standard format for uplink to spacecraft. Autogen requires fewer workers than are needed for older manual sequence-generation processes and reduces sequence-generation times from weeks to minutes.

Polymerization shrinkage stress of composite resins and resin cements - What do we need to know?

PubMed

Soares, Carlos José; Faria-E-Silva, André Luis; Rodrigues, Monise de Paula; Vilela, Andomar Bruno Fernandes; Pfeifer, Carmem Silvia; Tantbirojn, Daranee; Versluis, Antheunis

2017-08-28

Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with post-operative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed.

Preparation of Shrinkage Compensating Concrete with HCSA Expansive Agent

NASA Astrophysics Data System (ADS)

Li, Changcheng; Jia, Fujia

2017-10-01

Shrinkage compensating concrete (SCC) has become one of the best effective methods of preventing and reducing concrete cracking. SCC is prepared by HCSA high performance expansive agent for concrete which restrained expansion rate is optimized by 0.057%. Slump, compressive strength, restrained expansion rate and cracking resistance test were carried out on SCC. The results show that the initial slump of fresh SCC was about 220mm-230mm, while slump after 2 hours was 180mm-200mm. The restrained expansion rate of SCC increased with the mixing amount of expansive agent. After cured in water for 14 days, the restrained expansion rate of C35 and C40 SCC were 0.020%-0.032%. With the dosage of expansive agent increasing, restrained expansion rate of SCC increased, maximum compressive stress and cracking stress improved, cracking temperature fell, thus cracking resistance got effectively improvement.

Plastic shrinkage of mortars with shrinkage reducing admixture and lightweight aggregates studied by neutron tomography

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

Wyrzykowski, Mateusz, E-mail: mateusz.wyrzykowski@empa.ch; Lodz University of Technology, Department of Building Physics and Building Materials, Lodz; Trtik, Pavel

2015-07-15

Water transport in fresh, highly permeable concrete and rapid water evaporation from the concrete surface during the first few hours after placement are the key parameters influencing plastic shrinkage cracking. In this work, neutron tomography was used to determine both the water loss from the concrete surface due to evaporation and the redistribution of fluid that occurs in fresh mortars exposed to external drying. In addition to the reference mortar with a water to cement ratio (w/c) of 0.30, a mortar with the addition of pre-wetted lightweight aggregates (LWA) and a mortar with a shrinkage reducing admixture (SRA) were tested.more » The addition of SRA reduced the evaporation rate from the mortar at the initial stages of drying and reduced the total water loss. The pre-wetted LWA released a large part of the absorbed water as a consequence of capillary pressure developing in the fresh mortar due to evaporation.« less

Autogenic Deposits as A Potential Recorder of High-Frequency Signals: The Role of Autogenic Processes Revisited

NASA Astrophysics Data System (ADS)

Li, H.; Plink-Bjorklund, P.

2017-12-01

Studies (e.g., Jerolmack and Paola, 2010) have suggested that autogenic processes act as a filter for high-frequency environmental signals, and the underlying assumption is that autogenic processes can cause fluctuations in sediment and water discharge that modify or shred the signal. This assumption, however, fails to recognize that autogenic processes and their final products are dynamic and that they can respond to allogenic forcings. We compile a database containing published field studies, physical experiments, and numerical modeling works, and analyze the data under different boundary conditions. Our analyses suggest different conclusions. Autogenic processes are intrinsic to the sedimentary system, and they possess distinct patterns under steady boundary conditions. Upon changing boundary conditions, the autogenic patterns are also likely to change (depending on the magnitude of the change in the boundary conditions). Therefore, the pattern change provides us with the opportunity to restore the high-frequency signals that may not pass through the transfer zone. Here we present the theoretical basis for using autogenic deposits to infer high-frequency signals as well as modern and ancient field examples, physical experiments, and modeling works to illustrate the autogenic response to allogenic forcings. The field studies show the potential of using autogenic deposits to restore short-term climatic variability. The experiments demonstrate that autogenic processes in rivers are closely linked to sediment and water discharge. The modeling examples reveal the counteracting effects of some autogenic processes to form a self-organized pattern under a set of specific boundary conditions. We also highlight the limitations and challenges that need more research efforts to restore high-frequency signals. Some critical issues include the magnitude of the signals, the effect of the interference between different signals, and the incompleteness of the autogenic deposits.

Using a centrifuge for quality control of pre-wetted lightweight aggregate in internally cured concrete

NASA Astrophysics Data System (ADS)

Miller, Albert E.

Early age shrinkage of cementitious systems can result in an increased potential for cracking which can lead to a reduction in service life. Early age shrinkage cracking can be particularly problematic for high strength concretes, which are often specified due to their high strength and low permeability. However, these high strength concretes frequently exhibit a reduction in the internal relative humidity (RH) due to the hydration reaction (chemical shrinkage) and self-desiccation which results in a bulk shrinkage, termed autogenous shrinkage, which is substantial at early ages. Due to the low permeability of these concretes, standard external curing is not always efficient in addressing this reduction in internal RH since the penetration of water can be limited. Internal curing has been developed to reduce autogenous shrinkage. Internally cured mixtures use internal reservoirs filled with fluid (generally water) that release this fluid at appropriate times to counteract the effects of self-desiccation thereby maintaining a high internal RH. Internally cured concrete is frequently produced in North America using pre-wetted lightweight aggregate. One important aspect associated with preparing quality internally cured concrete is being able to determine the absorbed moisture and surface moisture associated with the lightweight aggregate which enables aggregate moisture corrections to be made for the concrete mixture. This thesis represents work performed to develop a test method using a centrifuge to determine the moisture state of pre-wetted fine lightweight aggregate. The results of the test method are then used in a series of worksheets that were developed to assist field technicians when performing the tests and applying the results to a mixture design. Additionally, research was performed on superabsorbent polymers to assess their ability to be used as an internal curing reservoir.

Effect of the Key Mixture Parameters on Shrinkage of Reactive Powder Concrete

PubMed Central

Zubair, Ahmed

2014-01-01

Reactive powder concrete (RPC) mixtures are reported to have excellent mechanical and durability characteristics. However, such concrete mixtures having high amount of cementitious materials may have high early shrinkage causing cracking of concrete. In the present work, an attempt has been made to study the simultaneous effects of three key mixture parameters on shrinkage of the RPC mixtures. Considering three different levels of the three key mixture factors, a total of 27 mixtures of RPC were prepared according to 33 factorial experiment design. The specimens belonging to all 27 mixtures were monitored for shrinkage at different ages over a total period of 90 days. The test results were plotted to observe the variation of shrinkage with time and to see the effects of the key mixture factors. The experimental data pertaining to 90-day shrinkage were used to conduct analysis of variance to identify significance of each factor and to obtain an empirical equation correlating the shrinkage of RPC with the three key mixture factors. The rate of development of shrinkage at early ages was higher. The water to binder ratio was found to be the most prominent factor followed by cement content with the least effect of silica fume content. PMID:25050395

Effect of the key mixture parameters on shrinkage of reactive powder concrete.

PubMed

Ahmad, Shamsad; Zubair, Ahmed; Maslehuddin, Mohammed

2014-01-01

Reactive powder concrete (RPC) mixtures are reported to have excellent mechanical and durability characteristics. However, such concrete mixtures having high amount of cementitious materials may have high early shrinkage causing cracking of concrete. In the present work, an attempt has been made to study the simultaneous effects of three key mixture parameters on shrinkage of the RPC mixtures. Considering three different levels of the three key mixture factors, a total of 27 mixtures of RPC were prepared according to 3(3) factorial experiment design. The specimens belonging to all 27 mixtures were monitored for shrinkage at different ages over a total period of 90 days. The test results were plotted to observe the variation of shrinkage with time and to see the effects of the key mixture factors. The experimental data pertaining to 90-day shrinkage were used to conduct analysis of variance to identify significance of each factor and to obtain an empirical equation correlating the shrinkage of RPC with the three key mixture factors. The rate of development of shrinkage at early ages was higher. The water to binder ratio was found to be the most prominent factor followed by cement content with the least effect of silica fume content.

Construction monitoring of paving fabrics systems to reduce reflective cracking.

DOT National Transportation Integrated Search

2008-08-01

Reflective cracking has been a major issue in pavement rehabilitation for many decades, due in part to shrinkage, constant expansion and contraction of pavement. These cracks result in uncomfortable rides and further deteriorate highways and local st...

Field Method for Measuring the Shrinkage/Swelling Dynamics of Cracks Using a Low-Cost ``Crack-o-meter''

NASA Astrophysics Data System (ADS)

Stewart, R. D.; Abou Najm, M. R.; Rupp, D. E.; Selker, J. S.

2010-12-01

Shrinking/swelling soils are characterized by transient crack networks which function as dominant controls on the partitioning of surface and subsurface flow, the rate and depth of percolation, and evaporation rates. For such soils, understanding the dynamics of cracks is critical to accurately quantify their influence on groundwater recharge, stream-flow generation, and solute transport, among other component of a site’s hydrology. We propose a low-cost method for measuring transient crack-volume using a sealed plastic bag connected by a hose to a PVC standpipe. The empty bag is placed into the crack, and then water is added via the standpipe, until the bag has expanded to the boundaries of the crack and some water remains in the standpipe. As the crack shrinks or swells, its volume changes, causing water displacement within the bag, which is measured as a corresponding change in water level in the standpipe. An automated level logger within the standpipe is used to record changes in water level, which are converted to volumetric changes from the known internal cross-sectional area of the standpipe. The volume of water filling the bag is accurately measured at the start and completion of the experiment (to check for leakage). Adding the startup volume to the cumulative temporal volumetric change in the standpipe provides a simple and accurate method for monitoring transient crack volume. Currently, the design is undergoing preliminary testing in a field site in Ninhue, Chile, and field and laboratory testing in Corvallis, Oregon. Initial results from the Chilean field site suggest that the crack-o-meters are responding to the closing of cracks, but further effort is needed to calibrate and validate the results. We hope that these low-cost “crack-o-meters” will become useful and simple tools for researchers to quantify temporal changes in crack volume with the objective of incorporating these results into hydrological modeling efforts.

Investigation into shrinkage of high-performance concrete used for Iowa bridge decks and overlays.

DOT National Transportation Integrated Search

2013-09-01

High-performance concrete (HPC) overlays have been used increasingly as an effective and economical method for bridge decks in Iowa and other states. However, due to its high cementitious material content, HPC often displays high shrinkage cracking p...

Assessment of the Effectiveness of Clay Soil Covers as Engineered Barriers in Waste Disposal Facilities with Emphasis on Modeling Cracking Behavior

DTIC Science & Technology

2008-06-01

escaping the clay and keeping its compacted conditions constant. Other stabilizing additives such as surfactants or cement and applications such as foamed ...not a local phenomenon. Once a crack is formed, increasing the width of the crack at the surface by additional shrinkage will also extend the depth...at the surface, increasing the width of the crack by additional shrinkage will drive the crack deeper into the soil mass, expos- ing new surfaces to

Comment on autogenic training and hypertension.

PubMed

Sakai, M; Sato, T; Takeichi, M; Fakunishi, I

1997-06-01

We comment on a report by Watanabe, et al. regarding the effects of autogenic training on hypertension. Using previous reports in the United States, we mention methodological problems on how to evaluate the effects of autogenic training and express our hope that they would provide further research to clarify the effects of autogenic training on hypertension.

Influence of fly ash, slag cement and specimen curing on shrinkage of bridge deck concrete.

DOT National Transportation Integrated Search

2014-12-01

Cracks occur in bridge decks due to restrained shrinkage of concrete materials. Concrete materials shrink as : cementitious materials hydrate and as water that is not chemically bonded to cementitious materials : migrates from the high humid environm...

Location, location & size: defects close to surfaces dominate fatigue crack initiation

NASA Astrophysics Data System (ADS)

Serrano-Munoz, Itziar; Buffiere, Jean-Yves; Mokso, Rajmund; Verdu, Catherine; Nadot, Yves

2017-03-01

Metallic cast components inevitably contain defects such as shrinkage cavities which are inherent to the solidification process. Those defects are known to significantly alter the fatigue life of components. Yet very little is known, quantitatively, on the dangerosity of internal casting defects compared to surface ones. In this study, fatigue specimens containing controlled internal defects (shrinkage pores) are used to foster internal cracking. In situ fatigue tests monitored by X ray synchrotron tomography revealed that the internal nucleation and propagation of cracks was systematically overran by surface cracking initiated at castings defects up to ten times smaller than the internal ones. These findings indicate that the presence of internal defects in cast components can be tolerated to a larger extent than is allowed by nowadays standards

Location, location &size: defects close to surfaces dominate fatigue crack initiation.

PubMed

Serrano-Munoz, Itziar; Buffiere, Jean-Yves; Mokso, Rajmund; Verdu, Catherine; Nadot, Yves

2017-03-27

Metallic cast components inevitably contain defects such as shrinkage cavities which are inherent to the solidification process. Those defects are known to significantly alter the fatigue life of components. Yet very little is known, quantitatively, on the dangerosity of internal casting defects compared to surface ones. In this study, fatigue specimens containing controlled internal defects (shrinkage pores) are used to foster internal cracking. In situ fatigue tests monitored by X ray synchrotron tomography revealed that the internal nucleation and propagation of cracks was systematically overran by surface cracking initiated at castings defects up to ten times smaller than the internal ones. These findings indicate that the presence of internal defects in cast components can be tolerated to a larger extent than is allowed by nowadays standards.

Towards a better understanding of the cracking behavior in soils

USDA-ARS?s Scientific Manuscript database

Understanding and modeling shrinkage-induced cracks helps bridge the gap between flow problem in the laboratory and at the field. Modeling flow at the field scale with Darcian fluxes developed at the laboratory scales is challenged with preferential flows attributed to the cracking behavior of soils...

Polymerization shrinkage kinetics and shrinkage-stress in dental resin-composites.

PubMed

Al Sunbul, Hanan; Silikas, Nick; Watts, David C

2016-08-01

To investigate a set of resin-composites and the effect of their composition on polymerization shrinkage strain and strain kinetics, shrinkage stress and the apparent elastic modulus. Eighteen commercially available resin-composites were investigated. Three specimens (n=3) were made per material and light-cured with an LED unit (1200mW/cm(2)) for 20s. The bonded-disk method was used to measure the shrinkage strain and Bioman shrinkage stress instrument was used to measure shrinkage stress. The shrinkage strain kinetics at 23°C was monitored for 60min. Maximum strain and stress was evaluated at 60min. The shrinkage strain rate was calculated using numerical differentiation. The shrinkage strain values ranged from 1.83 (0.09) % for Tetric Evoceram (TEC) to 4.68 (0.04) % for Beautifil flow plus (BFP). The shrinkage strain rate ranged from 0.11 (0.01%s(-1)) for Gaenial posterior (GA-P) to 0.59 (0.07) %s(-1) for BFP. Shrinkage stress values ranged from 3.94 (0.40)MPa for TET to 10.45 (0.41)MPa for BFP. The apparent elastic modulus ranged from 153.56 (18.7)MPa for Ever X posterior (EVX) to 277.34 (25.5) MPa for Grandio SO heavy flow (GSO). The nature of the monomer system determines the amount of the bulk contraction that occurs during polymerization and the resultant stress. Higher values of shrinkage strain and stress were demonstrated by the investigated flowable materials. The bulk-fill materials showed comparable result when compared to the traditional resin-composites. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Location, location & size: defects close to surfaces dominate fatigue crack initiation

PubMed Central

Serrano-Munoz, Itziar; Buffiere, Jean-Yves; Mokso, Rajmund; Verdu, Catherine; Nadot, Yves

2017-01-01

Metallic cast components inevitably contain defects such as shrinkage cavities which are inherent to the solidification process. Those defects are known to significantly alter the fatigue life of components. Yet very little is known, quantitatively, on the dangerosity of internal casting defects compared to surface ones. In this study, fatigue specimens containing controlled internal defects (shrinkage pores) are used to foster internal cracking. In situ fatigue tests monitored by X ray synchrotron tomography revealed that the internal nucleation and propagation of cracks was systematically overran by surface cracking initiated at castings defects up to ten times smaller than the internal ones. These findings indicate that the presence of internal defects in cast components can be tolerated to a larger extent than is allowed by nowadays standards PMID:28345599

Autogenous Bone Reconstruction of Large Secondary Skull Defects.

PubMed

Fearon, Jeffrey A; Griner, Devan; Ditthakasem, Kanlaya; Herbert, Morley

2017-02-01

The authors sought to ascertain the upper limits of secondary skull defect size amenable to autogenous reconstructions and to examine outcomes of a surgical series. Published data for autogenous and alloplastic skull reconstructions were also examined to explore associations that might guide treatment. A retrospective review of autogenously reconstructed secondary skull defects was undertaken. A structured literature review was also performed to assess potential differences in reported outcomes between autogenous bone and synthetic alloplastic skull reconstructions. Weighted risks were calculated for statistical testing. Ninety-six patients underwent autogenous skull reconstruction for an average defect size of 93 cm (range, 4 to 506 cm) at a mean age of 12.9 years. The mean operative time was 3.4 hours, 2 percent required allogeneic blood transfusions, and the average length of stay was less than 3 days. The mean length of follow-up was 28 months. There were no postoperative infections requiring surgery, but one patient underwent secondary grafting for partial bone resorption. An analysis of 34 studies revealed that complications, infections, and reoperations were more commonly reported with alloplastic than with autogenous reconstructions (relative risk, 1.57, 4.8, and 1.48, respectively). Autogenous reconstructions are feasible, with minimal associated morbidity, for patients with skull defect sizes as large as 500 cm. A structured literature review suggests that autogenous bone reconstructions are associated with lower reported infection, complication, and reoperation rates compared with synthetic alloplasts. Based on these findings, surgeons might consider using autogenous reconstructions even for larger skull defects. Therapeutic, IV.

AUTOGENIC THERAPY IN TENSION HEADACHE

PubMed Central

Amruthraj, Brunda; Mishra, H.; Kumaraiah, V.

1987-01-01

SUMMARY Ten subjects diagnosed as Psychalgia were taken for study. A multiple baseline design was adapted and clients were subjected to 30 sessions of autogenic training. They were assessed using physiological (EMG and thermal change) and behavioural measures (Visual analogue scale and behavioural symptom checklist). Findings revealed autogenic therapy to be effective in reducing tension headache. PMID:21927245

Documenting AUTOGEN and APGEN Model Files

NASA Technical Reports Server (NTRS)

Gladden, Roy E.; Khanampompan, Teerapat; Fisher, Forest W.; DelGuericio, Chris c.

2008-01-01

A computer program called "autogen hypertext map generator" satisfies a need for documenting and assisting in visualization of, and navigation through, model files used in the AUTOGEN and APGEN software mentioned in the two immediately preceding articles. This program parses autogen script files, autogen model files, PERL scripts, and apgen activity-definition files and produces a hypertext map of the files to aid in the navigation of the model. This program also provides a facility for adding notes and descriptions, beyond what is in the source model represented by the hypertext map. Further, this program provides access to a summary of the model through variable, function, sub routine, activity and resource declarations as well as providing full access to the source model and source code. The use of the tool enables easy access to the declarations and the ability to traverse routines and calls while analyzing the model.

Bridge decks : mitigation of cracking and increased durability.

DOT National Transportation Integrated Search

2016-06-01

The application of pre-soaked lightweight aggregates (LWA) as an internal curing agent in concrete to reduce the cracking due to drying shrinkage is thoroughly studied in this report. It is determined that although LWA can significantly reduce autoge...

Bridge Decks: Mitigation of Cracking and Increased Durability.

DOT National Transportation Integrated Search

2016-06-01

The application of pre-soaked lightweight aggregates (LWA) as an internal curing agent in concrete to reduce the cracking due to drying shrinkage is thoroughly studied in this report. It is determined that although LWA can significantly reduce autoge...

Kinetics of corneal thermal shrinkage

NASA Astrophysics Data System (ADS)

Borja, David; Manns, Fabrice; Lee, William E.; Parel, Jean-Marie

2004-07-01

Purpose: The purpose of this study was to determine the effects of temperature and heating duration on the kinetics of thermal shrinkage in corneal strips using a custom-made shrinkage device. Methods: Thermal shrinkage was induced and measured in corneal strips under a constant load placed while bathed in 25% Dextran irrigation solution. A study was performed on 57 Florida Lions Eye Bank donated human cadaver eyes to determine the effect of temperature on the amount and rate of thermal shrinkage. Further experiments were performed on 20 human cadaver eyes to determine the effects of heating duration on permanent shrinkage. Data analysis was performed to determine the effects of temperature, heating duration, and age on the amount and kinetics of shrinkage. Results: Shrinkage consisted of two phases: a shrinkage phase during heating and a regression phase after heating. Permanent shrinkage increased with temperature and duration. The shrinkage and regression time constants followed Arrhenius type temperature dependence. The shrinkage time constants where calculated to be 67, 84, 121, 560 and 1112 (s) at 80, 75, 70, 65, and 60°C respectively. At 65°C the permanent shrinkage time constant was calculated to be 945s. Conclusion: These results show that shrinkage treatments need to raise the temperature of the tissue above 75°C for several seconds in order to prevent regression of the shrinkage effect immediately after treatment and to induce the maximum amount of permanent irreversible shrinkage.

[Autogenic training as a therapy for adjustment disorder in adults].

PubMed

Jojić, Boris R; Leposavić, Ljubica M

2005-01-01

Autogenic training is a widely recognised psychotherapy technique. The British School of Autogenic Training cites a large list of disorders, states, and changes, where autogenic training may prove to be of help. We wanted to explore the application of autogenic training as a therapy for adjustment disorder in adults. Our sample consisted of a homogeneous group of 35 individuals, with an average age of 39.3 +/- 1.6 years, who were diagnosed with adjustment disorder, F 43.2, in accordance with ICD 10 search criteria. The aim of our study was to research the effectiveness of autogenic training as a therapy for adjustment disorder in adults, by checking the influence of autogenic training on the biophysical and biochemical indicators of adjustment disorder. We measured the indicators of adjustment disorder and their changes in three phases: before the beginning, immediately after the beginning, and six months after the completion, of a practical course in autogenic training. We measured systolic and diastolic arterial blood pressure, brachial pulse rate as well as the levels of cortisol in plasma, of cholesterol in blood, and of glucose. During that period, autogenic training functioned as the sole therapy. The study confirmed our preliminary assumptions. The measurements we performed demonstrated that arterial blood pressure, pulse rate, concentration of cholesterol and cortisol, after the application of autogenic training among the subjects suffering from adjustment disorder, were lower in comparison to the initial values. These values remained lower even six months after the completion of the practical course in autogenic training. Autogenic training significantly decreases the values of physiological indicators of adjustment disorder, diminishes the effects of stress in an individual, and helps adults to cope with stress, facilitating their recuperation.

[Autogenic training as a therapy for adjustment disorder in adolescents].

PubMed

Jojić, Boris R; Leposavić, Ljubica M

2005-01-01

Autogenic training is a widespread technique used in psychotherapy. The British school of autogenic training cites a large list of diseases, health states, and life changes, in which autogenic training can be of help. We wanted to explore the application of autogenic training as a therapy for adjustment disorder in adolescents. The sample consisted of a homogeneous group of 31 individuals, with an average age of 17.3 +/- 0.2 years, who were diagnosed with adjustment disorder, F 43.2, in accordance with ICD 10 search criteria. The aim of our work was to figure out the influence of autogenic training on adjustment disorder, through biophysical and biochemical indicators, and to research the efficiacy of autogenic training as a therapy for adjustment disorder in adolescents. We observed adjustment disorder indicators and their changes in three phases, using initial, final, and control values, which we measured immediately before the beginning, immediately after the completion, and six months after the completion, of the practical course in autogenic training. We measured systolic and diastolic arterial blood pressure, brachial pulse rates, cortisol levels in plasma, cholesterol levels in blood, as well as glucose concentrations. During that period, autogenic training was employed as the sole therapy. The study confirmed our preliminary assumptions. The measurements we performed showed that arterial blood pressure, pulse rates, cholesterol and cortisol concentrations, after the application of autogenic training among adolescents suffering from adjustment disorder, were lower than the initial values. They remained lower even six months after the completion of the practical course in autogenic training. We concluded that autogenic training significantly decreases the values of physiological indicators of adjustment disorder, diminishes the effects of stress in an individual, and eases the adaptation of adolescents to stress, helping with recovery.

Molar cusp deformation evaluated by micro-CT and enamel crack formation to compare incremental and bulk-filling techniques.

PubMed

Oliveira, Laís Rani Sales; Braga, Stella Sueli Lourenço; Bicalho, Aline Arêdes; Ribeiro, Maria Tereza Hordones; Price, Richard Bengt; Soares, Carlos José

2018-07-01

To describe a method of measuring the molar cusp deformation using micro-computed tomography (micro-CT), the propagation of enamel cracks using transillumination, and the effects of hygroscopic expansion after incremental and bulk-filling resin composite restorations. Twenty human molars received standardized Class II mesio-occlusal-distal cavity preparations. They were restored with either a bulk-fill resin composite, X-tra fil (XTRA), or a conventional resin composite, Filtek Z100 (Z100). The resin composites were tested for post-gel shrinkage using a strain gauge method. Cusp deformation (CD) was evaluated using the images obtained using a micro-CT protocol and using a strain-gauge method. Enamel cracks were detected using transillumination. The post-gel shrinkage of Z100 was higher than XTRA (P < 0.001). The amount of cusp deformation produced using Z100 was higher compared to XTRA, irrespective of the measurement method used (P < 0.001). The thinner lingual cusp always had a higher CD than the buccal cusp, irrespective of the measurement method (P < 0.001). A positive correlation (r = 0.78) was found between cusp deformation measured by micro-CT or by the strain-gauge method. After hygroscopic expansion of the resin composite, the cusp displacement recovered around 85% (P < 0.001). After restoration, Z100 produced more cracks than XTRA (P = 0.012). Micro-CT was an effective method for evaluating the cusp deformation. Transillumination was effective for detecting enamel cracks. There were fewer negative effects of polymerization shrinkage in bulk-fill resin restorations using XTRA than for the conventional incremental filling technique using conventional composite resin Z100. Shrinkage and cusp deformation are directly related to the formation of enamel cracks. Cusp deformation and crack propagation may increase the risk of tooth fracture. Copyright © 2018 Elsevier Ltd. All rights reserved.

Autogenic dynamics of debris-flow fans

NASA Astrophysics Data System (ADS)

van den Berg, Wilco; de Haas, Tjalling; Braat, Lisanne; Kleinhans, Maarten

2015-04-01

Alluvial fans develop their semi-conical shape by cyclic avulsion of their geomorphologically active sector from a fixed fan apex. These cyclic avulsions have been attributed to both allogenic and autogenic forcings and processes. Autogenic dynamics have been extensively studied on fluvial fans through physical scale experiments, and are governed by cyclic alternations of aggradation by unconfined sheet flow, fanhead incision leading to channelized flow, channel backfilling and avulsion. On debris-flow fans, however, autogenic dynamics have not yet been directly observed. We experimentally created debris-flow fans under constant extrinsic forcings, and show that autogenic dynamics are a fundamental intrinsic process on debris-flow fans. We found that autogenic cycles on debris-flow fans are driven by sequences of backfilling, avulsion and channelization, similar to the cycles on fluvial fans. However, the processes that govern these sequences are unique for debris-flow fans, and differ fundamentally from the processes that govern autogenic dynamics on fluvial fans. We experimentally observed that backfilling commenced after the debris flows reached their maximum possible extent. The next debris flows then progressively became shorter, driven by feedbacks on fan morphology and flow-dynamics. The progressively decreasing debris-flow length caused in-channel sedimentation, which led to increasing channel overflow and wider debris flows. This reduced the impulse of the liquefied flow body to the flow front, which then further reduced flow velocity and runout length, and induced further in-channel sedimentation. This commenced a positive feedback wherein debris flows became increasingly short and wide, until the channel was completely filled and the apex cross-profile was plano-convex. At this point, there was no preferential transport direction by channelization, and the debris flows progressively avulsed towards the steepest, preferential, flow path. Simultaneously

Comparative Study of Shrinkage and Non-Shrinkage Model of Food Drying

NASA Astrophysics Data System (ADS)

Shahari, N.; Jamil, N.; Rasmani, KA.

2016-08-01

A single phase heat and mass model has always been used to represent the moisture and temperature distribution during the drying of food. Several effects of the drying process, such as physical and structural changes, have been considered in order to increase understanding of the movement of water and temperature. However, the comparison between the heat and mass equation with and without structural change (in terms of shrinkage), which can affect the accuracy of the prediction model, has been little investigated. In this paper, two mathematical models to describe the heat and mass transfer in food, with and without the assumption of structural change, were analysed. The equations were solved using the finite difference method. The converted coordinate system was introduced within the numerical computations for the shrinkage model. The result shows that the temperature with shrinkage predicts a higher temperature at a specific time compared to that of the non-shrinkage model. Furthermore, the predicted moisture content decreased faster at a specific time when the shrinkage effect was included in the model.

Shrinkage of Dental Composite in Simulated Cavity Measured with Digital Image Correlation

PubMed Central

Li, Jianying; Thakur, Preetanjali; Fok, Alex S. L.

2014-01-01

Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to understand where and how shrinkage strain and stress develop in such restored teeth, Digital Image Correlation (DIC) was used to provide a comprehensive view of the displacement and strain distributions within model restorations that had undergone polymerization shrinkage. Specimens with model cavities were made of cylindrical glass rods with both diameter and length being 10 mm. The dimensions of the mesial-occlusal-distal (MOD) cavity prepared in each specimen measured 3 mm and 2 mm in width and depth, respectively. After filling the cavity with resin composite, the surface under observation was sprayed with first a thin layer of white paint and then fine black charcoal powder to create high-contrast speckles. Pictures of that surface were then taken before curing and 5 min after. Finally, the two pictures were correlated using DIC software to calculate the displacement and strain distributions. The resin composite shrunk vertically towards the bottom of the cavity, with the top center portion of the restoration having the largest downward displacement. At the same time, it shrunk horizontally towards its vertical midline. Shrinkage of the composite stretched the material in the vicinity of the “tooth-restoration” interface, resulting in cuspal deflections and high tensile strains around the restoration. Material close to the cavity walls or floor had direct strains mostly in the directions perpendicular to the interfaces. Summation of the two direct strain components showed a relatively uniform distribution around the restoration and its magnitude equaled approximately to the volumetric shrinkage strain of the material. PMID:25079865

Fatigue resistance and crack propensity of novel "super-closed" sandwich composite resin restorations in large MOD defects.

PubMed

Magne, Pascal; Silva, Silvana; Andrada, Mauro de; Maia, Hamilton

2016-01-01

To assess the influence of conventional glass ionomer cement (GIC) vs resin-modified GIC (RMGIC) as a base material for novel, super-closed sandwich restorations (SCSR) and its effect on shrinkage-induced crack propensity and in vitro accelerated fatigue resistance. A standardized MOD slottype tooth preparation was applied to 30 extracted maxillary molars (5 mm depth/5 mm buccolingual width). A modified sandwich restoration was used, in which the enamel/dentin bonding agent was applied first (Optibond FL, Kerr), followed by a Ketac Molar (3M ESPE)(group KM, n = 15) or Fuji II LC (GC) (group FJ, n = 15) base, leaving 2 mm for composite resin material (Miris 2, Coltène-Whaledent). Shrinkageinduced enamel cracks were tracked with photography and transillumination. Samples were loaded until fracture or to a maximum of 185,000 cycles under isometric chewing (5 H z), starting with a load of 200 N (5,000 X), followed by stages of 400, 600, 800, 1,000, 1,200, and 1,400 N at a maximum of 30,000 X each. Groups were compared using the life table survival analysis (α = .008, Bonferroni method). Group FJ showed the highest survival rate (40% intact specimens) but did not differ from group KM (20%) or traditional direct restorations (13%, previous data). SCSR generated less shrinkage-induced cracks. Most failures were re-restorable (above the cementoenamel junction [CEJ]). Inclusion of GIC/RMGIC bases under large direct SCSRs does not affect their fatigue strength but tends to decrease the shrinkage-induced crack propensity. The use of GIC/ RMGIC bases and the SCSR is an easy way to minimize polymerization shrinkage stress in large MOD defects without weakening the restoration.

Autogenous teeth used for bone grafting: a comparison with traditional grafting materials.

PubMed

Kim, Young-Kyun; Kim, Su-Gwan; Yun, Pil-Young; Yeo, In-Sung; Jin, Seung-Chan; Oh, Ji-Su; Kim, Heung-Joong; Yu, Sun-Kyoung; Lee, Sook-Young; Kim, Jae-Sung; Um, In-Woong; Jeong, Mi-Ae; Kim, Gyung-Wook

2014-01-01

This study evaluated the surface structures and physicochemical characteristics of a novel autogenous tooth bone graft material currently in clinical use. The material's surface structure was compared with a variety of other bone graft materials via scanning electron microscope (SEM). The crystalline structure of the autogenous tooth bone graft material from the crown (AutoBT crown) and root (AutoBT root), xenograft (BioOss), alloplastic material (MBCP), allograft (ICB), and autogenous mandibular cortical bone were compared using x-ray diffraction (XRD) analysis. The solubility of each material was measured with the Ca/P dissolution test. The results of the SEM analysis showed that the pattern associated with AutoBT was similar to that from autogenous cortical bones. In the XRD analysis, AutoBT root and allograft showed a low crystalline structure similar to that of autogenous cortical bones. In the CaP dissolution test, the amount of calcium and phosphorus dissolution in AutoBT was significant from the beginning, while displaying a pattern similar to that of autogenous cortical bones. In conclusion, autogenous tooth bone graft materials can be considered to have physicochemical characteristics similar to those of autogenous bones. Copyright © 2014 Elsevier Inc. All rights reserved.

AUTOGEN

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

2003-05-29

AUTOGEN computes collision-free sequences of robot motion instructions to permit traversal of three-dimensional space curves. Order and direction of curve traversal and orientation of end effector are constraided by a set of manufacturing rules. Input can be provided as a collection of solid models or in terms of wireframe objects and structural cross-section definitions. Entity juxtaposition can be inferred, with appropriate structural features automatically provided. Process control is asserted as a function of position and orientation along each space curve, and is currently implemented for welding processes.

Management of pain through autogenic training.

PubMed

Kanji, N

2000-08-01

Physical and emotional pain are an inevitable part of human existence and are without natural antidotes. In view of this, and in the light of increasing professional reluctance to depend on analgesics, this paper proposes the widespread application of autogenic training, a relaxation technique which has been seen to confront pain very effectively, and also to reduce substantially drugs dependency. It analyses autogenic training in respect of some of the more common pain-allied disorders such as childbirth, headaches and migraines, back pain, cancer and palliative care, and cardiology.

Cure shrinkage in casting resins

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

Spencer, J. Brock

2015-02-01

A method is described whereby the shrinkage of a casting resin can be determined. Values for the shrinkage of several resin systems in frequent use by Sandia have been measured. A discussion of possible methods for determining the stresses generated by cure shrinkage and thermal contraction is also included.

Influence of nano-material on the expansive and shrinkage soil behavior

NASA Astrophysics Data System (ADS)

Taha, Mohd Raihan; Taha, Omer Muhie Eldeen

2012-10-01

This paper presents an experimental study performed on four types of soils mixed with three types of nano-material of different percentages. The expansion and shrinkage tests were conducted to investigate the effect of three type of nano-materials (nano-clay, nano-alumina, and nano-copper) additive on repressing strains in compacted residual soil mixed with different ratios of bentonite (S1 = 0 % bentonite, S2 = 5 % bentonite, S3 = 10 % bentonite, and S4 = 20 % bentonite). The soil specimens were compacted under the condition of maximum dry unit weight and optimum water content ( w opt) using standard compaction test. The physical and mechanical results of the treated samples were determined. The untreated soil values were used as control points for comparison purposes. It was found that with the addition of optimum percentage of nano-material, both the swell strain and shrinkage strain reduced. The results show that nano-material decreases the development of desiccation cracks on the surface of compacted samples without decrease in the hydraulic conductivity.

Autogenic drainage for airway clearance in cystic fibrosis.

PubMed

McCormack, Pamela; Burnham, Paul; Southern, Kevin W

2017-10-06

Autogenic drainage is an airway clearance technique that was developed by Jean Chevaillier in 1967. The technique is characterised by breathing control using expiratory airflow to mobilise secretions from smaller to larger airways. Secretions are cleared independently by adjusting the depth and speed of respiration in a sequence of controlled breathing techniques during exhalation. The technique requires training, concentration and effort from the individual. It is important to systematically review the evidence demonstrating that autogenic drainage is an effective intervention for people with cystic fibrosis. To compare the clinical effectiveness of autogenic drainage in people with cystic fibrosis with other physiotherapy airway clearance techniques. We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews, as well as two trials registers (31 August 2017).Dtae of most recent search of the Cochrane Cystic Fibrosis Trials Register: 25 September 2017. We identified randomised and quasi-randomised controlled studies comparing autogenic drainage to another airway clearance technique or no therapy in people with cystic fibrosis for at least two treatment sessions. Data extraction and assessments of risk of bias were independently performed by two authors. The authors assessed the quality of the evidence using the GRADE system. The authors contacted two investigators for further information pertinent to their published studies. Searches retrieved 35 references to 21 individual studies, of which seven (n = 208) were eligible for inclusion. One study was of parallel design with the remaining six being cross-over in design; participant numbers ranged from 17 to 75. The total study duration varied between four days and two years. The age of participants ranged between seven and 63 years with a wide

[Clinical experience in communication in autogenous psychotherapy and hypnosis].

PubMed

Eletti, P L; Peresson, L

1983-12-30

Questions relating to communication and metacommunication during two forms of directive psychotherapy (Schultz's autogenous training and hypnosis) are examined. The concept of rigidity and cognitive flexibility with regard to the physician-patient relationship is discussed: abstract-concrete dynamics, abstract generalisation of diagnosis, linguistic egocentricity, stereotypical adaptation to conventional language. Some attention is devoted to Heider's balance theory as the first approach to psychological understanding of the therapeutic relationship. The communicative and metacommunicative process described by the Palo Alto (California) school is discussed. Autogenous psychotherapy and hypnosis extend through the concepts of symmetrical relation and inferior complementarity. The criteria for reaching these objectives are stated, along with the pragmatic methods devised for decoding messages and gaining access to metacommunication. Three clinical cases treated through autogenous training and one with hypnosis are analysed with respect to communication and from the relational standpoint. The patient's messages are decoded, the ambiguity of the communication is detected, and the physician's possible answers are examined at both the technical and the emotive level. It is felt that the correct use of the communicational perspective greatly extends the possibilities of autogenous training and hypnosis. It is not a question of combining relational and autogenous management, but of using the Palo Alto discoveries in the more complete understanding of cases in which psychotherapy is employed.

Autogenic training to reduce anxiety in nursing students: randomized controlled trial.

PubMed

Kanji, Nasim; White, Adrian; Ernst, Edzard

2006-03-01

This paper reports a study to determine the effectiveness of autogenic training in reducing anxiety in nursing students. Nursing is stressful, and nursing students also have the additional pressures and uncertainties shared with all academic students. Autogenic training is a relaxation technique consisting of six mental exercises and is aimed at relieving tension, anger and stress. Meta-analysis has found large effect sizes for autogenic trainings intervention comparisons, medium effect sizes against control groups, and no effects when compared with other psychological therapies. A controlled trial with 50 nursing students found that the number of certified days off sick was reduced by autogenic training compared with no treatment, and a second trial with only 18 students reported greater improvement in Trait Anxiety, but not State Anxiety, compared with untreated controls. A randomized controlled trial with three parallel arms was completed in 1998 with 93 nursing students aged 19-49 years. The setting was a university college in the United Kingdom. The treatment group received eight weekly sessions of autogenic training, the attention control group received eight weekly sessions of laughter therapy, and the time control group received no intervention. The outcome measures were the State-Trait Anxiety Inventory, the Maslach Burnout Inventory, blood pressure and pulse rate completed at baseline, 2 months (end of treatment), and 5, 8, and 11 months from randomization. There was a statistically significantly greater reduction of State (P<0.001) and Trait (P<0.001) Anxiety in the autogenic training group than in both other groups immediately after treatment. There were no differences between the groups for the Maslach Burnout Inventory. The autogenic training group also showed statistically significantly greater reduction immediately after treatment in systolic (P<0.01) and diastolic (P<0.05) blood pressure, and pulse rate (P<0.002), than the other two groups

Autogenic training and dream recall.

PubMed

Schredl, M; Doll, E

1997-06-01

The present study has investigated the relationship between Autogenic Training and dream recall for 112 participants in 16 beginning courses of 10 wk. Analyses confirmed the hypothesis that learning and practicing this relaxation technique enhanced dream recall.

Autogenic training for tension type headaches: a systematic review of controlled trials.

PubMed

Kanji, N; White, A R; Ernst, E

2006-06-01

To determine from the published evidence whether autogenic training as sole therapy is effective for prevention of tension-type headaches in adults. Systematic review of controlled trials. Literature searches were performed in January 2005 in six major databases, specifically Medline, EMBASE, AMED, CENTRAL, PsychInfo and CINAHL and information was extracted and evaluated in a pre-defined manner. Seven controlled clinical trials were included in the review. The methodological quality of these studies was low. Patient samples were generally representative of the more severely affected cases. None of the studies show autogenic training to be convincingly superior to other interventions care. Some trials suggested that the effect of autogenic training is no different from hypnosis and inferior to biofeedback. There is no consistent evidence to suggest that autogenic training is superior to other interventions for prevention of tension headaches, or different from other forms of relaxation. Further studies should investigate the use of standard autogenic training in patients with moderate headache.

Phobic postural vertigo treated with autogenic training: a case report.

PubMed

Goto, Fumiyuki; Nakai, Kimiko; Kunihiro, Takanobu; Ogawa, Kaoru

2008-09-30

Patients suffering from dizziness due to vertigo are commonly encountered in the department of otolaryngology. If various clinical examinations do not reveal any objective findings, then the patients are referred to the department of internal medicine or psychiatry. In many cases, the diagnosis is psychological dizziness. Phobic postural vertigo, which was first reported by Brandt T et al in 1994, is supposed to be a type of psychological dizziness. The diagnosis is based on 6 characteristics proposed by Brandt et al. Patients are usually treated with conventional medical therapy, but some cases may be refractory to such a therapy. Psychotherapy is recommended in some cases; however, psychotherapy including autogenic training, which can be used for general relaxation, is not widely accepted. This paper describes the successful administration of autogenic training in a patient suffering from phobic postural vertigo. We present a case of a patient who suffered from phobic postural vertigo. A 37-year-old female complained of dizziness. She had started experiencing dizziness almost 3 years She was intractable to many sort of conventional therapy. In the end, her symptom disappeared after introduction of autogenic training. Autogenic training can be a viable and acceptable treatment option for phobic postural vertigo patients who fail to respond to other therapies. This case emphasizes the importance of autogenic training as a method to control symptom of phobic postural vertigo.

Chronobiometric assessment of autogenic training effects upon blood pressure and heart rate.

PubMed

Watanabe, Y; Halberg, F; Cornélissen, G; Saito, Y; Fukuda, K; Otsuka, K; Kikuchi, T

1996-12-01

Autogenic training, a method of self-hypnosis, lowers the extent of within-day variation of systolic blood pressure assessed by the circadian double amplitude. The blood pressure and heart rate of ten patients, conventionally diagnosed as having hypertension or white-coat hypertension, were automatically monitored at 30-min intervals for 7 days before autogenic training and again for 7 days, at 1 or 2 months after the start of autogenic training (practiced three times daily). The circadian double amplitude of systolic blood pressure of the patients investigated was 3 to 17 mm Hg lower on autogenic training. In 5 patients, reductions by 7 to 17 mm Hg were statistically significant. These results are regarded as provisional statistics, the utility of which depends on replication. By contrast, the over-all group reduction of the circadian double amplitude of systolic blood pressure by 8 mm Hg on the average can be taken at face value. Autogenic training also lowered the circadian double amplitude of diastolic blood pressure, but the effect was small as was the effect of autogenic training upon the MESOR (a rhythm adjusted mean) and acrophase (a measure of the timing of over-all high values recurring each day). The effect of autogenic training upon the circadian double amplitude of systolic blood pressure suggests its trial as first-line treatment of patients with an excessive circadian blood pressure amplitude, a condition which, even in the absence of an elevated 24-hr, average of blood pressure, is associated with a large increase in the risk of developing ischemic stroke or nephropathy.

Hospital Universiti Sains Malaysia experience in orbital floor reconstruction: autogenous graft versus Medpor.

PubMed

Wajih, Wahid Abdullah Salem; Shaharuddin, Bakiah; Razak, Noor Hayati Abdul

2011-06-01

A normally restored orbital structure after reconstructive surgery would accelerate the return of orbital function. The aim of the present study was to compare the outcomes of 2 orbital implants: autogenous grafts and porous polyethylene (Medpor). A longitudinal study was conducted of all patients who had undergone orbital floor reconstruction using an autogenous graft or Medpor. The study participants were divided into 2 groups, and the postoperative outcomes were assessed clinically. Of the 26 patients, 14 (53.0%) had undergone surgery with an autogenous graft and 12 (46.2%) with Medpor. Postoperatively, no diplopia in the primary gaze was noted in any patient. However, down gaze and peripheral diplopia was found in 11.5% and 26.9% in the autogenous group and in 3.8% and 26.9% in the Medpor group, respectively (P = 1.24). Enophthalmos was present in 11.4% of the autogenous graft group and 15.3% of the Medpor group (P = .465). The Hess chart findings were abnormal in 11.4% of both groups (P = .062). Restriction of movement was observed in 1 patient (3.8%) from the autogenous group and 7.7% of the Medpor group (P = .574). Orbital floor reconstruction using an autogenous graft or Medpor showed comparable results. Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

The treatment of recalcitrant post-traumatic nightmares with autogenic training and autogenic abreaction: a case study.

PubMed

Sadigh, M R

1999-09-01

Recurrent and frightening dreams are commonly experienced by patients who suffer from post-traumatic stress disorder after a motor vehicle accident. Such nocturnal episodes, if left untreated, can result in the experience of severe distress with physical, emotional, and psychophysiological concomitant. The present single-case study investigated the effects of the standard autogenic exercises and autogenic abreaction in reducing the frequency and severity of post-traumatic nightmares in a survivor of a car crash. The patient was also instructed in two additional organ-specific formulas in order to improve her sleep. The results of the study showed that the interventions were successful in effectively treating the patient's distressing nightmares. Follow-up data suggested that the treatment effects persisted after the termination of therapy. Suggestions for future investigations are discussed.

Do low-shrink composites reduce polymerization shrinkage effects?

PubMed

Tantbirojn, D; Pfeifer, C S; Braga, R R; Versluis, A

2011-05-01

Progress in polymer science has led to continuous reduction of polymerization shrinkage, exemplified by a new generation of "low-shrink composites". The common inference that shrinkage stress effects will be reduced in teeth restored with such restoratives with lower shrinkage was tested in extracted human premolars. Mesio-occluso-distal slot-shaped cavities were cut and restored with a conventional (SupremePlus) or low-shrink (RefleXions, Premise, Kalore, and LS) composite (N = 5). We digitized the coronal surfaces before and 10 min after restoration to determine cuspal deflection from the buccal and lingual volume change/area. We also determined the main properties involved (total shrinkage, post-gel shrinkage, degree of conversion, and elastic modulus), as well as microleakage, to verify adequate bonding. It was shown that, due to shrinkage stresses, buccal and lingual surfaces pulled inward after restoration (9-14 microns). Only Kalore and LS resulted in significantly lower tooth deformation (ANOVA/Student-Newman-Keuls post hoc, p = 0.05). The other two low-shrink composites, despite having the lowest and highest total shrinkage values, did not cause significant differences in cuspal deflection. Deflection seemed most related to the combination of post-gel shrinkage and elastic modulus. Therefore, even for significantly lower total shrinkage values, shrinkage stress is not necessarily reduced.

Self-repair of cracks in brittle material systems

NASA Astrophysics Data System (ADS)

Dry, Carolyn M.

2016-04-01

One of the most effective uses for self repair is in material systems that crack because the cracks can allow the repair chemical to flow into the crack damage sites in all three dimensions. In order for the repair chemical to stay in the damage site and flow along to all the crack and repair there must be enough chemical to fill the entire crack. The repair chemical must be designed appropriately for the particular crack size and total volume of cracks. In each of the three examples of self repair in crackable brittle systems, the viscosity and chemical makeup and volume of the repair chemicals used is different for each system. Further the chemical delivery system has to be designed for each application also. Test results from self repair of three brittle systems are discussed. In "Self Repair of Concrete Bridges and Infrastructure" two chemicals were used due to different placements in bridges to repair different types of cracks- surface shrinkage and shear cracks, In "Airplane Wings and Fuselage, in Graphite" the composite has very different properties than the concrete bridges. In the graphite for airplane components the chemical also had to survive the high processing temperatures. In this composite the cracks were so definite and deep and thin that the repair chemical could flow easily and repair in all layers of the composite. In "Ceramic/Composite Demonstrating Self Repair" the self repair system not only repaired the broken ceramic but also rebounded the composite to the ceramic layer

Phobic postural vertigo treated with autogenic training: a case report

PubMed Central

Goto, Fumiyuki; Nakai, Kimiko; Kunihiro, Takanobu; Ogawa, Kaoru

2008-01-01

Background Patients suffering from dizziness due to vertigo are commonly encountered in the department of otolaryngology. If various clinical examinations do not reveal any objective findings, then the patients are referred to the department of internal medicine or psychiatry. In many cases, the diagnosis is psychological dizziness. Phobic postural vertigo, which was first reported by Brandt T et al in 1994, is supposed to be a type of psychological dizziness. The diagnosis is based on 6 characteristics proposed by Brandt et al. Patients are usually treated with conventional medical therapy, but some cases may be refractory to such a therapy. Psychotherapy is recommended in some cases; however, psychotherapy including autogenic training, which can be used for general relaxation, is not widely accepted. This paper describes the successful administration of autogenic training in a patient suffering from phobic postural vertigo. Case presentation We present a case of a patient who suffered from phobic postural vertigo. A 37-year-old female complained of dizziness. She had started experiencing dizziness almost 3 years She was intractable to many sort of conventional therapy. In the end, her symptom disappeared after introduction of autogenic training. Conclusion Autogenic training can be a viable and acceptable treatment option for phobic postural vertigo patients who fail to respond to other therapies. This case emphasizes the importance of autogenic training as a method to control symptom of phobic postural vertigo. PMID:18826607

Quantification of water penetration into concrete through cracks by neutron radiography

NASA Astrophysics Data System (ADS)

Kanematsu, M.; Maruyama, I.; Noguchi, T.; Iikura, H.; Tsuchiya, N.

2009-06-01

Improving the durability of concrete structures is one of the ways to contribute to the sustainable development of society, and it has also become a crucial issue from an environmental viewpoint. It is well known that moisture behavior in reinforced concrete is linked to phenomena such as cement hydration, volume change and cracking caused by drying shrinkage, rebar corrosion and water leakage that affect the durability of concrete. In this research, neutron radiography was applied for visualization and quantification of water penetration into concrete through cracks. It is clearly confirmed that TNR can make visible the water behavior in/near horizontal/vertical cracks and can quantify the rate of diffusion and concentration distribution of moisture with high spatial and time resolution. On detailed analysis, it is observed that water penetrates through the crack immediately after pouring and its migration speed and distribution depend on the moisture condition in the concrete.

EFFECT OF LIGHT-CURING UNITS AND ACTIVATION MODE ON POLYMERIZATION SHRINKAGE AND SHRINKAGE STRESS OF COMPOSITE RESINS

PubMed Central

Lopes, Lawrence Gonzaga; Franco, Eduardo Batista; Pereira, José Carlos; Mondelli, Rafael Francisco Lia

2008-01-01

The aim of this study was to evaluate the polymerization shrinkage and shrinkage stress of composites polymerized with a LED and a quartz tungsten halogen (QTH) light sources. The LED was used in a conventional mode (CM) and the QTH was used in both conventional and pulse-delay modes (PD). The composite resins used were Z100, A110, SureFil and Bisfil 2B (chemical-cured). Composite deformation upon polymerization was measured by the strain gauge method. The shrinkage stress was measured by photoelastic analysis. The polymerization shrinkage data were analyzed statistically using two-way ANOVA and Tukey test (p≤0.05), and the stress data were analyzed by one-way ANOVA and Tukey's test (p≤0.05). Shrinkage and stress means of Bisfil 2B were statistically significant lower than those of Z100, A110 and SureFil. In general, the PD mode reduced the contraction and the stress values when compared to CM. LED generated the same stress as QTH in conventional mode. Regardless of the activation mode, SureFil produced lower contraction and stress values than the other light-cured resins. Conversely, Z100 and A110 produced the greatest contraction and stress values. As expected, the chemically cured resin generated lower shrinkage and stress than the light-cured resins. In conclusion, The PD mode effectively decreased contraction stress for Z100 and A110. Development of stress in light-cured resins depended on the shrinkage value. PMID:19089287

The Application of Autogenic Feedback Training in a Smoking Termination Program.

ERIC Educational Resources Information Center

Boullion, Jean K.; Chen, W. William

1980-01-01

Autogenic feedback training was an effective adjunct to a smoking termination program. An 81 percent reduction in smoking activity was found for the subjects who received the training. Achieving relaxation and reducing anxiety through autogenic feedback training helped subjects restore their self-confidence and deal with stress. (Author)

Fundamental investigations related to the mitigation of volume changes in cement-based materials at early ages

NASA Astrophysics Data System (ADS)

Sant, Gaurav Niteen

The increased use of high-performance, low water-to-cement (w/c) ratio concretes has led to increased occurrences of early-age shrinkage cracking in civil engineering structures. To reduce the magnitude of early-age shrinkage and the potential for cracking, mitigation strategies using shrinkage reducing admixtures (SRAs), saturated lightweight aggregates, expansive cements and extended moist curing durations in construction have been recommended. However, to appropriately utilize these strategies, it is important to have a complete understanding of the driving forces of early-age volume change and how these methods work from a materials perspective to reduce shrinkage. This dissertation uses a first-principles approach to understand the mechanism of shrinkage reducing admixtures (SRAs) to generate an expansion and mitigate shrinkage at early-ages, quantify the influence of a CaO-based expansive additive in reducing unrestrained shrinkage, residual stress development and the cracking potential at early-ages and quantify the influence of shrinkage reducing admixtures (SRAs) and cement hydration (pore structure refinement) on the reduction induced in the fluid transport properties of the material. The effects of shrinkage reducing admixtures (SRAs) are described in terms of inducing autogenous expansions in cement pastes at early ages. An evaluation comprising measurements of autogenous deformation, x-ray diffraction (Rietveld analysis), pore solution and thermogravimetric analysis and electron microscopy is performed to understand the chemical nature and physical effects of the expansion. Thermodynamic calculations performed on the measured liquid-phase compositions indicate the SRA produces elevated Portlandite super-saturations in the pore solution which results in crystallization stress driven expansions. The thermodynamic calculations are supported by deformation measurements performed on cement pastes mixed in solutions saturated with Portlandite or containing

Autogenous transplantation of maxillary and mandibular molars.

PubMed

Reich, Peter P

2008-11-01

Autogenous tooth transplantation has been used as a predictable surgical approach to correct malocclusion and replace edentulous areas. This article focuses on the surgical approach and technique for molar transplantation. Thirty-two patients aged between 11 and 25 years underwent 44 autogenous molar transplantations. The procedure involved transplantation of impacted or newly erupted third molars into the extraction sockets of nonrestorable molars and surgical removal and replacement of horizontally impacted molars into their proper vertical alignment. Five basic procedural concepts were applied: 1) atraumatic extraction, avoiding disruption of the root sheath and root buds; 2) apical contouring of bone at the transplantation site and maxillary sinus lift via the Summers osteotome technique, when indicated, for maxillary molars; 3) preparation of a 4-wall bony socket; 4) avoidance of premature occlusal interferences; and 5) stabilization of the tooth with placement of a basket suture. All 32 patients successfully underwent the planned procedure. To date, 2 patients have had localized infection that resulted in loss of the transplant. The remaining 42 transplants remain asymptomatic and functioning, with a mean follow-up period of 19 months. No infection, ankylosis, loss of the transplant, or root resorption has been noted. In addition, endodontic therapy has not been necessary on any transplanted teeth. Autogenous tooth transplantation has been discussed and described in the literature previously, with a primary focus on cuspid and bicuspid transplantation. The molar transplant is infrequently discussed in today's literature, possibly because of the preponderance of titanium dental implants. Autogenous molar transplantation is a viable procedure with low morbidity and excellent functional and esthetic outcomes. This report shows the successful transplantation of 42 of 44 molars in 32 patients with a mean follow-up period of 19 months.

A 3D Lattice Modelling Study of Drying Shrinkage Damage in Concrete Repair Systems

PubMed Central

Luković, Mladena; Šavija, Branko; Schlangen, Erik; Ye, Guang; van Breugel, Klaas

2016-01-01

Differential shrinkage between repair material and concrete substrate is considered to be the main cause of premature failure of repair systems. The magnitude of induced stresses depends on many factors, for example the degree of restraint, moisture gradients caused by curing and drying conditions, type of repair material, etc. Numerical simulations combined with experimental observations can be of great use when determining the influence of these parameters on the performance of repair systems. In this work, a lattice type model was used to simulate first the moisture transport inside a repair system and then the resulting damage as a function of time. 3D simulations were performed, and damage patterns were qualitatively verified with experimental results and cracking tendencies in different brittle and ductile materials. The influence of substrate surface preparation, bond strength between the two materials, and thickness of the repair material were investigated. Benefits of using a specially tailored fibre reinforced material, namely strain hardening cementitious composite (SHCC), for controlling the damage development due to drying shrinkage in concrete repairs was also examined. PMID:28773696

A 3D Lattice Modelling Study of Drying Shrinkage Damage in Concrete Repair Systems.

PubMed

Luković, Mladena; Šavija, Branko; Schlangen, Erik; Ye, Guang; van Breugel, Klaas

2016-07-14

Differential shrinkage between repair material and concrete substrate is considered to be the main cause of premature failure of repair systems. The magnitude of induced stresses depends on many factors, for example the degree of restraint, moisture gradients caused by curing and drying conditions, type of repair material, etc. Numerical simulations combined with experimental observations can be of great use when determining the influence of these parameters on the performance of repair systems. In this work, a lattice type model was used to simulate first the moisture transport inside a repair system and then the resulting damage as a function of time. 3D simulations were performed, and damage patterns were qualitatively verified with experimental results and cracking tendencies in different brittle and ductile materials. The influence of substrate surface preparation, bond strength between the two materials, and thickness of the repair material were investigated. Benefits of using a specially tailored fibre reinforced material, namely strain hardening cementitious composite (SHCC), for controlling the damage development due to drying shrinkage in concrete repairs was also examined.

Crack Driving Forces in a Multilayered Coating System for Ceramic Matrix Composite Substrates

NASA Technical Reports Server (NTRS)

Ghosn, Louis J.; Zhu, Dongming; Miller, Robert A.

2005-01-01

The effects of the top coating thickness, modulus and shrinkage strains on the crack driving forces for a baseline multilayer Yttria-Stabilized-Zirconia/Mullite/Si thermal and environment barrier coating (TEBC) system for SiC/SiC ceramic matrix composite substrates are determined for gas turbine applications. The crack driving forces increase with increasing modulus, and a low modulus thermal barrier coating material (below 10 GPa) will have no cracking issues under the thermal gradient condition analyzed. Since top coating sintering increases the crack driving forces with time, highly sintering resistant coatings are desirable to maintain a low tensile modulus and maintain a low crack driving force with time. Finite element results demonstrated that an advanced TEBC system, such as ZrO2/HfO2, which possesses improved sintering resistance and high temperature stability, exhibited excellent durability. A multi-vertical cracked structure with fine columnar spacing is an ideal strain tolerant coating capable of reducing the crack driving forces to an acceptable level even with a high modulus of 50 GPa.

Autogenous Metallic Pipe Leak Repair in Potable Water Systems.

PubMed

Tang, Min; Triantafyllidou, Simoni; Edwards, Marc A

2015-07-21

Copper and iron pipes have a remarkable capability for autogenous repair (self-repair) of leaks in potable water systems. Field studies revealed exemplars that metallic pipe leaks caused by nails, rocks, and erosion corrosion autogenously repaired, as confirmed in the laboratory experiments. This work demonstrated that 100% (N = 26) of 150 μm leaks contacting representative bulk potable water in copper pipes sealed autogenously via formation of corrosion precipitates at 20-40 psi, pH 3.0-11.0, and with upward and downward leak orientations. Similar leaks in carbon steel pipes at 20 psi self-repaired at pH 5.5 and 8.5, but two leaks did not self-repair permanently at pH 11.0 suggesting that water chemistry may control the durability of materials that seal the leaks and therefore the permanence of repair. Larger 400 μm holes in copper pipes had much lower (0-33%) success of self-repair at pH 3.0-11.0, whereas all 400 μm holes in carbon steel pipes at 20 psi self-repaired at pH 4.0-11.0. Pressure tests indicated that some of the repairs created at 20-40 psi ambient pressure could withstand more than 100 psi without failure. Autogenous repair has implications for understanding patterns of pipe failures, extending the lifetime of decaying infrastructure, and developing new plumbing materials.

Reconstruction of mandibular defects with autogenous bone grafts: a review of 30 cases.

PubMed

Sajid, Malik Ali Hassan; Warraich, Riaz Ahmed; Abid, Hina; Ehsan-ul-Haq, Muhammad; Shah, Khurram Latif; Khan, Zafar

2011-01-01

Multitudes of options are available for reconstruction of functional and cosmetic defects of the mandible, caused by various ailments. At the present time, autogenous bone grafting is the gold standard by which all other techniques of reconstruction of the mandible can be judged. The purpose of this study was to evaluate the outcome of different osseous reconstruction options using autogenous bone grafts for mandibular reconstruction. This Interventional study was conducted at Department of Oral and Maxillofacial Surgery, King Edward Medical University/Mayo Hospital Lahore, from January 2008 to July 2009 including one year follow-up. The study was carried out on thirty patients having bony mandibular defects. They were reconstructed with the autogenous bone grafts from different graft donor sites. On post-operative visits they were evaluated for outcome variables. Success rate of autogenous bone grafts in this study was 90%. Only 10% of the cases showed poor results regarding infection, resorption and graft failure. Autogenous bone grafts, non-vascularised or vascularised, are a reliable treatment modality for the reconstruction of the bony mandibular defects with predictable functional and aesthetic outcome.

Devitrification and shrinkage behavior of silica fibers

NASA Technical Reports Server (NTRS)

Zaplatynsky, I.

1972-01-01

Devitrification and shrinkage of three batches of silica fibers were investigated in the temperature range of 1200 to 1350 C. Fibers with high water and impurity content devitrified rapidly to cristobalite and quartz and exhibited rapid, but the least amount of, shrinkage. A batch with low water and impurity content devitrified more slowly to cristobalite only and underwent severe shrinkage by the mechanism of viscous flow. A third batch of intermediate purity level and low water content devitrified at a moderate rate mainly to cristobalite but shrunk very rapidly. Completely devitrified silica fibers did not exhibit any further shrinkage.

[Short and long-term changes in cortical circulation caused by autogenic training].

PubMed

Meyer, H K; Diehl, B J; Ulrich, P; Meinig, G

1987-01-01

The well-known hyperfrontal pattern of hemispheric blood flow measured with 133-Xenon is not found in 12 healthy resting men who have been practicing Autogenic Training for at least six months. This might indicate a long-term decrease in the level of activation. Successfully practiced exercises of Autogenic Training lead to an increased blood flow in the Rolandic area representing the body sceme and to a decreased blood flow in regions related to acoustical attention and to autonomic functions. Left hemispheric cerebral blood flow ist lower in rest. The relative activation of the left hemisphere during Autogenic Training is discussed.

A clinical study of autogenic training-based behavioral treatment for panic disorder.

PubMed

Sakai, M

1996-03-01

The present study investigated the effect of autogenic training-based behavioral treatment for panic disorder and identified the predictors of treatment outcome. Thirty-four patients meeting DSM-III-R criteria for panic disorder received autogenic training-based behavioral treatment from October 1981 to December 1994. They were treated individually by the author. The medical records of the patients were investigated for the purpose of this study. The results showed that this autogenic training-based behavioral treatment had successful results. Fifteen patients were cured, nine much improved, five improved, and five unchanged at the end of the treatment. Improvement trends were found as for the severity of panic attack and the severity of agoraphobic avoidance. No consistent findings about predictors emerged when such pretreatment variables as demographics and severity of symptoms were used to predict the outcome. Also, three treatment variables showed useful predictive power. First, practicing the second standard autogenic training exercise satisfactorily predicted better outcomes. Second, application of in vivo exposure was found to be positively associated with the treatment outcome in patients with agoraphobic avoidance. Third, longer treatment periods were associated with better outcomes. These findings suggested that the autogenic training-based behavioral treatment could provide relief to the majority of panic disorder patients.

[Application of joint reconstruction with autogenous coronoid process graft to treat temporomandibular joint ankylosis].

PubMed

Xie, Qing-tiao; Huang, Xuan-ping; Jiang, Xian-fang; Yang, Yuan-yuan; Li, Hua; Lin, Xi

2013-08-01

To evaluate the clinical effect of joint reconstruction by using autogenous coronoid process graft to treat temporomandibular joint(TMJ) ankylosis. Nine cases of TMJ ankylosis from September 2008 to September 2010 were surgically treated by joint reconstruction with autogenous coronoid process graft, using autogenous articular disc or prosthodontic membrane as interpositional material. Mouth opening, occlusion and cone beam CT(CBCT) were used for evaluation before and after surgery. Satisfactory mouth opening was achieved in all patients and no one got occlusal changes or reankylosis during follow-up. CBCT showed that coronoid process graft reached bone union with the ramus and turned to be round. It is effective to cure TMJ ankylosis through joint reconstruction with autogenous coronoid process graft.

Shrinkage-stress kinetics of photopolymerised resin-composites

NASA Astrophysics Data System (ADS)

Satterthwaite, Julian D.

The use of directly-placed substances as restorative materials in teeth remains the technique of choice for preserving function and form in teeth that have cavities. The current aesthetic restorative materials of choice are resin-composite materials, although these undergo molecular densification during polymerisation, which has deleterious effects. Although shrinkage-strain is the cause, it is the shrinkage-stress effects that may be seen as being responsible for the problems with adhesive resin-based restorations that are encountered clinically, the bond may fail with separation of the material from the cavity wall, leading to marginal discolouration, pulpal irritation and subsequent necrosis, post operative sensitivity, recurrent caries and eventual failure of restorations. Other outcomes include cohesive fracture of enamel or cusps, cuspal movement (strain) and persistent pain. The aims of this research were to characterise the effects of variations in resin-composite formulation on shrinkage-strain and shrinkage-stress kinetics. In particular, the influence of the size and morphology of the dispersed phase was investigated through the study of experimental formulations. Polymerisation shrinkage-strain kinetics were assessed with the bonded-disk method. It was found that resin-composites with spherical filler particles had significantly lower shrinkage-strain compared to those with irregular filler particles. Additionally, shrinkage-strain was found to be dependent on the size of filler particle, and this trend was related, in part, to differences in the degree of conversion. The data were also used to calculate the activation energy for each material, and a relationship between this and filler particle size for the irregular fillers was demonstrated. A fixed-compliance cantilever beam instrument (Bioman) was used for characterisation of shrinkage-stress kinetics. Significant differences were identified between materials in relation to filler particle size and

9 CFR 113.113 - Autogenous biologics.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Autogenous biologics. 113.113 Section 113.113 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS STANDARD REQUIREMENTS...

Fatigue crack initiation of magnesium alloys under elastic stress amplitudes: A review

NASA Astrophysics Data System (ADS)

Wang, B. J.; Xu, D. K.; Wang, S. D.; Han, E. H.

2017-12-01

The most advantageous property of magnesium (Mg) alloys is their density, which is lower compared with traditional metallic materials. Mg alloys, considered the lightest metallic structural material among others, have great potential for applications as secondary load components in the transportation and aerospace industries. The fatigue evaluation of Mg alloys under elastic stress amplitudes is very important in ensuring their service safety and reliability. Given their hexagonal close packed structure, the fatigue crack initiation of Mg and its alloys is closely related to the deformation mechanisms of twinning and basal slips. However, for Mg alloys with shrinkage porosities and inclusions, fatigue cracks will preferentially initiate at these defects, remarkably reducing the fatigue lifetime. In this paper, some fundamental aspects about the fatigue crack initiation mechanisms of Mg alloys are reviewed, including the 3 followings: 1) Fatigue crack initiation of as-cast Mg alloys, 2) influence of microstructure on fatigue crack initiation of wrought Mg alloys, and 3) the effect of heat treatment on fatigue initiation mechanisms. Moreover, some unresolved issues and future target on the fatigue crack initiation mechanism of Mg alloys are also described.

Hot cracking of Structural Steel during Laser Welding

NASA Astrophysics Data System (ADS)

Pineda Huitron, Rosa M.; Vuorinen, Esa

2017-10-01

Laser welding is an important technique in many industries due to its high precision in operation, its local and fast processing, narrow welds and its good weld surface quality. However, the process can involve some complications due to the rapid heating and cooling of the material processed, resulting in physical and metallurgical effects as thermal contraction during solidification, giving as a result the presence of residual stresses in the narrow weld. Formation of defects during the process is an important topic to be evaluated in order to achieve better performance of the steels in use. In the present work, defects formed during laser welding of a structural steel have been investigated. The defects formed have been identified and the causes of the defects are discussed. Possible strategies for improvement of the welding procedure and final weld result are proposed. The defects were analysed by optical and scanning electron microscopy and hardness measurement. Cracks were located in the middle of the fusion zone and followed both inter-granular and trans-granular paths. Impurities as manganese sulphides were found along the welding direction, and could act as sites for crack formation. The cracks formed during solidification of the weld are identified as solidification cracks. This kind of cracks is usually caused by solidification shrinkage and thermal contractions during the process, which appear in the fusion zone and sometimes in the heat affected zone.

Spiral crack patterns observed for melt-grown spherulites of poly(L-lactic acid) upon quenching.

PubMed

Matsuda, Futoshi; Sobajima, Takamasa; Irie, Satoshi; Sasaki, Takashi

2016-04-01

In this paper, we demonstrate the characteristic spiral cracking that appears on the surface of melt-grown poly(L-lactic acid) (PLLA) spherulites with relatively large sizes (greater than 0.4mm in diameter). The crack occurs via thermal shrinkage upon quenching after crystallization. Although concentric cracks on polymer spherulites have been found to occur in quite a few studies, spiral crack patterns have never been reported so far. The present spiral crack was observed for thick spherulites (> 10 μm), whereas the concentric crack pattern was frequently observed for thin spherulites (typically 5 μm). The present PLLA spherulites exhibited a non-banded structure with no apparent structural periodicity at least on the scale of the spiral pitch, and thus no direct correlation between the crack pattern and the spherulitic structure was suggested. The spiral was revealed to be largely Archimedean of which the spiral pitch increases with an increase in the thickness of the spherulite. This may be interpreted in terms of a classical mechanical model for a thin layer with no delamination from the substrate.

Autogenous and reactive obsessions: further evidence for a two-factor model of obsessions.

PubMed

Moulding, Richard; Kyrios, Michael; Doron, Guy; Nedeljkovic, Maja

2007-01-01

Obsessive-compulsive disorder is a highly disabling anxiety disorder, characterized by occurrence of intrusive and unwanted thoughts (obsessions), which lead to performance of repetitive compulsions and/or rituals in order to reduce distress. Recently, it has been proposed that obsessions may be divided into two categories, termed autogenous and reactive obsessions [Lee, H.-J., & Kwon, S.-M. (2003). Two different types of obsessions: autogenous obsessions and reactive obsessions. Behavior Research and Therapy, 41, 11-29]. In this study, we aimed to further validate this subtyping of obsessions, and to investigate the cognitive and emotional correlates of the subtypes. Evidence was found for the division, using a confirmatory factor analysis in an analogue sample (N=372). It was found that frequency of reactive obsessions related more strongly to distress caused by overt OC symptoms (e.g., washing, checking), whereas frequency of autogenous obsessions related to distress from impulses of harm. Compared to autogenous obsessions, frequency of reactive obsessions correlated more strongly with all OC-related beliefs. Few differences were found between autogenous and reactive obsessions with respect to depression, anxiety, and view about self (self-ambivalence, self-esteem). It is suggested that existing OC-belief measures are more relevant to reactive obsessions. Implications for theory and treatment are discussed.

[Autogenic training within the therapeutic scope of schizophrenic patients].

PubMed

Starke, H

1976-06-01

The author calls the reader's attention to the rather strange fact that autogenic training, in spite of worldwide recognition and extensive uses of the method in various disciplines of medicine and spheres of live, has not so far been finding wide application in the medical specialty dealing with mental disorders. After discussing some possible causes of this situation and commenting on first signs of a necessary change in attitude toward autogenic training, he reports his own experience in the treatment of schizophrenic patients with this psychotherapeutic method, emphasizing the need for including psychotherapy in a complex concept of the treatment of psychoses.

Thermal shrinkage for shoulder instability.

PubMed

Toth, Alison P; Warren, Russell F; Petrigliano, Frank A; Doward, David A; Cordasco, Frank A; Altchek, David W; O'Brien, Stephen J

2011-07-01

Thermal capsular shrinkage was popular for the treatment of shoulder instability, despite a paucity of outcomes data in the literature defining the indications for this procedure or supporting its long-term efficacy. The purpose of this study was to perform a clinical evaluation of radiofrequency thermal capsular shrinkage for the treatment of shoulder instability, with a minimum 2-year follow-up. From 1999 to 2001, 101 consecutive patients with mild to moderate shoulder instability underwent shoulder stabilization surgery with thermal capsular shrinkage using a monopolar radiofrequency device. Follow-up included a subjective outcome questionnaire, discussion of pain, instability, and activity level. Mean follow-up was 3.3 years (range 2.0-4.7 years). The thermal capsular shrinkage procedure failed due to instability and/or pain in 31% of shoulders at a mean time of 39 months. In patients with unidirectional anterior instability and those with concomitant labral repair, the procedure proved effective. Patients with multidirectional instability had moderate success. In contrast, four of five patients with isolated posterior instability failed. Thermal capsular shrinkage has been advocated for the treatment of shoulder instability, particularly mild to moderate capsular laxity. The ease of the procedure makes it attractive. However, our retrospective review revealed an overall failure rate of 31% in 80 patients with 2-year minimum follow-up. This mid- to long-term cohort study adds to the literature lacking support for thermal capsulorrhaphy in general, particularly posterior instability. The online version of this article (doi:10.1007/s11420-010-9187-7) contains supplementary material, which is available to authorized users.

Subcritical crack propagation due to chemical rock weakening: macroscale chemo-plasticity and chemo-elasticity modeling

NASA Astrophysics Data System (ADS)

Hueckel, T.; Hu, M.

2015-12-01

Crack propagation in a subcritically stressed rock subject to chemically aggressive environment is analyzed and numerically simulated. Chemically induced weakening is often encountered in hydraulic fracturing of low-permeability oil/gas reservoirs and heat reservoirs, during storage of CO2 and nuclear waste corroding canisters, and other circumstances when rock matrix acidizing is involved. Upon acidizing, mineral mass dissolution is substantially enhanced weakening the rock and causing crack propagation and eventually permeability changes in the medium. The crack process zone is modeled mathematically via a chemo-plastic coupling and chemo-elastic coupling model. In plasticity a two-way coupling is postulated between mineral dissolution and a yield limit of rock matrix. The rate of dissolution is described by a rate law, but the mineral mass removal per unit volume is also a function of a variable internal specific surface area, which is in turn affected by the micro-cracking (treated as a plastic strain). The behavior of the rock matrix is modeled as rigid-plastic adding a chemical softening capacity to Cam-Clay model. Adopting the Extended Johnson's approximation of processes around the crack tip, the evolution of the stress field and deformation as a function of the chemically enhanced rock damage is modeled in a simplified way. In addition, chemical reactive transport is made dependent on plastic strain representing micro-cracking. Depending on mechanical and chemical boundary conditions, the area of enhanced chemical softening is near or somewhat away from the crack tip.In elasticity, chemo-mechanical effect is postulated via a chemical volumetric shrinkage strain proportional to mass removal variable, conceived analogously to thermal expansion. Two versions are considered: of constant coefficient of shrinkage and a variable one, coupled to deviatoric strain. Airy Potential approach used for linear elasticity is extended considering an extra term, which is

Thermo-mechanical simulations of early-age concrete cracking with durability predictions

NASA Astrophysics Data System (ADS)

Havlásek, Petr; Šmilauer, Vít; Hájková, Karolina; Baquerizo, Luis

2017-09-01

Concrete performance is strongly affected by mix design, thermal boundary conditions, its evolving mechanical properties, and internal/external restraints with consequences to possible cracking with impaired durability. Thermo-mechanical simulations are able to capture those relevant phenomena and boundary conditions for predicting temperature, strains, stresses or cracking in reinforced concrete structures. In this paper, we propose a weakly coupled thermo-mechanical model for early age concrete with an affinity-based hydration model for thermal part, taking into account concrete mix design, cement type and thermal boundary conditions. The mechanical part uses B3/B4 model for concrete creep and shrinkage with isotropic damage model for cracking, able to predict a crack width. All models have been implemented in an open-source OOFEM software package. Validations of thermo-mechanical simulations will be presented on several massive concrete structures, showing excellent temperature predictions. Likewise, strain validation demonstrates good predictions on a restrained reinforced concrete wall and concrete beam. Durability predictions stem from induction time of reinforcement corrosion, caused by carbonation and/or chloride ingress influenced by crack width. Reinforcement corrosion in concrete struts of a bridge will serve for validation.

Development of Laboratory Testing Criteria for Evaluating Cementitious, Rapid-Setting Pavement Repair Materials

DTIC Science & Technology

2011-04-01

thus they should only be used when experienced operators have been trained on using the material with the mixer. ABC Cement was suited for various... autogenous shrinkage, all of which occur during hydration. Shrinkage potential is important because repair materials that shrink excessively are more

Synthesis, characterization, shrinkage and curing kinetics of a new low-shrinkage urethane dimethacrylate monomer for dental applications.

PubMed

Atai, Mohammad; Ahmadi, Mehdi; Babanzadeh, Samal; Watts, David C

2007-08-01

The aim of the study was to synthesize and characterize an isophorone-based urethane dimethacrylate (IP-UDMA) resin-monomer and to investigate its shrinkage and curing kinetics. The IP-UDMA monomer was synthesized through the reaction of polyethylene glycol 400 and isophorone diisocyanate followed by reacting with HEMA to terminate it with methacrylate end groups. The reaction was followed using a standard back titration method and FTIR spectroscopy. The final product was purified and characterized using FTIR, (1)H NMR, elemental analysis and refractive index measurement. The shrinkage-strain of the specimens photopolymerized at circa 700mW/cm(2) was measured using the bonded-disk technique at 23, 35, and 45 degrees C. Initial shrinkage-strain-rates were obtained by numerical differentiation of shrinkage-strain data with respect to time. Degree-of-conversion of the specimens was measured using FTIR spectroscopy. The thermal curing kinetics of the monomer were also studied by differential scanning calorimetry (DSC). The characterization methods confirmed the suggested reaction route and the synthesized monomer. A low shrinkage-strain of about 4% was obtained for the new monomer. The results showed that the shrinkage-strain-rate of the monomer followed the autocatalytic model of Kamal and Sourour [Kamal MR, Sourour S. Kinetic and thermal characterization of thermoset cure. Polym Eng Sci 1973;13(1):59-64], which is used to describe the reaction kinetics of thermoset resins. The model parameters were calculated by linearization of the equation. The model prediction was in a good agreement with the experimental data. The properties of the new monomer compare favorably with properties of the commercially available resins.

Evidence-based alternatives for autogenous grafts around teeth: outcomes, attachment, and stability.

PubMed

McGuire, Michael K

2014-06-01

Although the use of autogenous harvested tissues has proven to be the gold standard for soft tissue augmentation procedures involving root coverage or generation of keratinized tissue, harvest site morbidity and limited supply have prompted clinicians to seek graft alternatives. Using a hierarchy of evidence, the author reviews both clinical and patient-reported results for harvest graft substitutes and, considering his own research experience, reviews autogenous graft substitute outcomes, attachment, and stability over time. Overall, when the goal is keratinized-tissue generation, living cellular constructs and xenogeneic collagen matrices have provided acceptable clinical results, but with better esthetics and patient preference than autogenous free gingival grafts. For root coverage therapy, enamel matrix derivatives, platelet-derived growth factors, and xenogeneic collagen matrices have provided acceptable results with equivalent esthetics to autogenous connective tissue grafts, while also being preferred by patients. Longterm results for enamel matrix derivatives, platelet-derived growth factors, and xenogeneic collagen matrices indicate root coverage can be maintained over time. In the author's hands, xenogeneic collagen matrices have been the only harvest graft alternatives that can be used either covered or uncovered by soft tissue.

Shrinkage Degree in $L_{2}$ -Rescale Boosting for Regression.

PubMed

Xu, Lin; Lin, Shaobo; Wang, Yao; Xu, Zongben

2017-08-01

L 2 -rescale boosting ( L 2 -RBoosting) is a variant of L 2 -Boosting, which can essentially improve the generalization performance of L 2 -Boosting. The key feature of L 2 -RBoosting lies in introducing a shrinkage degree to rescale the ensemble estimate in each iteration. Thus, the shrinkage degree determines the performance of L 2 -RBoosting. The aim of this paper is to develop a concrete analysis concerning how to determine the shrinkage degree in L 2 -RBoosting. We propose two feasible ways to select the shrinkage degree. The first one is to parameterize the shrinkage degree and the other one is to develop a data-driven approach. After rigorously analyzing the importance of the shrinkage degree in L 2 -RBoosting, we compare the pros and cons of the proposed methods. We find that although these approaches can reach the same learning rates, the structure of the final estimator of the parameterized approach is better, which sometimes yields a better generalization capability when the number of sample is finite. With this, we recommend to parameterize the shrinkage degree of L 2 -RBoosting. We also present an adaptive parameter-selection strategy for shrinkage degree and verify its feasibility through both theoretical analysis and numerical verification. The obtained results enhance the understanding of L 2 -RBoosting and give guidance on how to use it for regression tasks.

Synthesis of MgB2 at Low Temperature and Autogenous Pressure

PubMed Central

Mackinnon, Ian D. R.; Winnett, Abigail; Alarco, Jose A.; Talbot, Peter C.

2014-01-01

High quality, micron-sized interpenetrating grains of MgB2, with high density, are produced at low temperatures (~420 °C < T < ~500 °C) under autogenous pressure by pre-mixing Mg powder and NaBH4 and heating in an Inconel 601 alloy reactor for 5–15 h. Optimum production of MgB2, with yields greater than 75%, occurs for autogenous pressure in the range 1.0 MPa to 2.0 MPa, with the reactor at ~500 °C. Autogenous pressure is induced by the decomposition of NaBH4 in the presence of Mg and/or other Mg-based compounds. The morphology, transition temperature and magnetic properties of MgB2 are dependent on the heating regime. Significant improvement in physical properties accrues when the reactor temperature is held at 250 °C for >20 min prior to a hold at 500 °C. PMID:28788656

[Observation of bridging operation by an autogenous incus in the ossiculoplasty].

PubMed

Li, Hao-zhun; Gong, Shu-sheng

2008-10-01

To study the clinical effects of bridging operation by an autogenous incus in the ossiculoplasty. All the postoperative follow-up data of the 68 patients were analyzed retrospectively, who underwent bridging operation by an autogenous incus in the ossiculoplasty and were followed up for 6-28 months with an average of 19.75 months. The autogenous incus which had been reshaped was implanted between the intact malleus and the intact mobile stapes. The preoperative and postoperative pure tone average (PTA) air-conduction, bone-conduction and air-bone gap on four frequencies (0.5, 1, 2 and 4 kHz) were calculated and analyzed. No postoperative autogenous includes were extruded with only two cases displaced. The pure tone air conduction improved from a preoperative average of (46.69 +/- 18.32) dB to a postoperative average of (30.21 +/- 9.46) dB, while bone conduction improved from a preoperative average of (24.72 +/- 10.63) dB to a postoperative average of (18.15 +/- 8.91) dB, as well as air-bone gap closed from a preoperative average of 21.97 +/- 10.32 dB to a postoperative average of (12.06 +/- 9.46) dB. The success rate (postoperative PTA-ABG < or = 20 dB) occurred in 75% of all the cases. The improvement of the bone conduction occurred in 66% of all the cases, at least with 10 dB occurred in at least two frequencies. Because of low expenses, high convenience in an operation, high stability in effects, very low complications and excellent hearing results for the patients, the bridging operation as stated in the above was worthy of choice. The autogenous incus could be utilized if the defects between the intact, mobile stapes and the intact malleus could be well repaired.

Autogenous Regulation of Splicing of the Transcript of a Yeast Ribosomal Protein Gene

NASA Astrophysics Data System (ADS)

Dabeva, Mariana D.; Post-Beittenmiller, Martha A.; Warner, Jonathan R.

1986-08-01

The gene for a yeast ribosomal protein, RPL32, contains a single intron. The product of this gene appears to participate in feedback control of the splicing of the intron from the transcript. This autogenous regulation of splicing provides a striking analogy to the autogenous regulation of translation of ribosomal proteins in Escherichia coli.

Crack-free conditions in welding of glass by ultrashort laser pulse.

PubMed

Miyamoto, Isamu; Cvecek, Kristian; Schmidt, Michael

2013-06-17

The spatial distribution of the laser energy absorbed by nonlinear absorption process in bulk glass w(z) is determined and thermal cycles due to the successive ultrashort laser pulse (USLP) is simulated using w(z) based on the transient thermal conduction model. The thermal stress produced in internal melting of bulk glass by USLP is qualitatively analyzed based on a simple thermal stress model, and crack-free conditions are studied in glass having large coefficient of thermal expansion. In heating process, cracks are prevented when the laser pulse impinges into glass with temperatures higher than the softening temperature of glass. In cooling process, shrinkage stress is suppressed to prevent cracks, because the embedded molten pool produced by nonlinear absorption process behaves like an elastic body under the compressive stress field unlike the case of CW-laser welding where the molten pool having a free surface produced by linear absorption process is plastically deformed under the compressive stress field.

Application of autogenic training for anxiety disorders: a clinical study in a psychiatric setting.

PubMed

Sakai, M

1997-03-01

The effects of autogenic training for anxiety disorders were investigated in a psychiatric setting of a medical school hospital and the predictors of this treatment outcome were identified. Fifty-five patients who meet the DSM-III-R criteria for anxiety disorders were treated individually with autogenic training by the author from October 1981 to October 1995. The medical records of the patients were investigated retrospectively. The results showed that the autogenic training was successful. Twenty-eight patients (51%) were cured, fourteen (25%) much improved, eight (15%) improved and five (9%) unchanged at the end of the treatment. Forty-two patients (76%) were assessed as having had successful treatment. Pretreatment variables, such as patient's clinical characteristics, did not provide a useful guide to the outcome. Four treatment variables did have a bearing on outcome. First, practicing the second standard autogenic training exercise was a satisfactory predictor of a better outcome. Second, practicing generalization training also was a useful predictor. Third, the application of other behavioral treatment techniques was found to be positively associated with outcome. Fourth, longer treatment periods were associated with a better outcome. These findings suggested that autogenic training could be of significant benefit for the treatment of anxiety disorders.

Analysis of structural diseases in widened structure due to the shrinkage and creep difference of new bridge

NASA Astrophysics Data System (ADS)

Wu, Wenqing; Zhang, Hui

2018-03-01

In order to investigate the possible structural diseases brought to the top flange of existing prestressed concrete box girder bridge due to the shrinkage and creep difference between new and old bridge, the stress state of the existing box girder before and after widening and the mechanisms of potential structural diseases were analyzed using finite element method in this paper. Results showed that the inner flange of the old box girder were generally in the state of large tensile stress, the main reason for which was the shrinkage and creep effect difference of the new and old bridge. And the tensile stress was larger than tensile strength of C50 concrete, which would most likely cause crack in the deck plate of box girder. Hence, reinforcement measures are needed to be designed carefully. Meanwhile, the transverse deformation of widened structure had exceeded the distance between the anti-seismic block and the web of box girder at the end cross section, which would squeeze anti-seismic block severely. Therefore, it is necessary to limit the length of continuous bridge in need of widening.

Modeling crack growth during Li insertion in storage particles using a fracture phase field approach

NASA Astrophysics Data System (ADS)

Klinsmann, Markus; Rosato, Daniele; Kamlah, Marc; McMeeking, Robert M.

2016-07-01

Fracture of storage particles is considered to be one of the major reasons for capacity fade and increasing power loss in many commercial lithium ion batteries. The appearance of fracture and cracks in the particles is commonly ascribed to mechanical stress, which evolves from inhomogeneous swelling and shrinkage of the material when lithium is inserted or extracted. Here, a coupled model of lithium diffusion, mechanical stress and crack growth using a phase field method is applied to investigate how the formation of cracks depends on the size of the particle and the presence or absence of an initial crack, as well as the applied flux at the boundary. The model shows great versatility in that it is free of constraints with respect to particle geometry, dimension or crack path and allows simultaneous observation of the evolution of lithium diffusion and crack growth. In this work, we focus on the insertion process. In particular, we demonstrate the presence of intricate fracture phenomena, such as, crack branching or complete breakage of storage particles within just a single half cycle of lithium insertion, a phenomenon that was only speculated about before.

Sealing of cracks in cement using microencapsulated sodium silicate

NASA Astrophysics Data System (ADS)

Giannaros, P.; Kanellopoulos, A.; Al-Tabbaa, A.

2016-08-01

Cement-based materials possess an inherent autogenous self-healing capability allowing them to seal, and potentially heal, microcracks. This can be improved through the addition of microencapsulated healing agents for autonomic self-healing. The fundamental principle of this self-healing mechanism is that when cracks propagate in the cementitious matrix, they rupture the dispersed capsules and their content (cargo material) is released into the crack volume. Various healing agents have been explored in the literature for their efficacy to recover mechanical and durability properties in cementitious materials. In these materials, the healing agents are most commonly encapsulated in macrocontainers (e.g. glass tubes or capsules) and placed into the material. In this work, microencapsulated sodium silicate in both liquid and solid form was added to cement specimens. Sodium silicate reacts with the calcium hydroxide in hydrated cement paste to form calcium-silicate-hydrate gel that fills cracks. The effect of microcapsule addition on rheological and mechanical properties of cement is reported. It is observed that the microcapsule addition inhibits compressive strength development in cement and this is observed through a plateau in strength between 28 and 56 days. The improvement in crack-sealing for microcapsule-containing specimens is quantified through sorptivity measurements over a 28 day healing period. After just seven days, the addition of 4% microcapsules resulted in a reduction in sorptivity of up to 45% when compared to specimens without any microcapsule addition. A qualitative description of the reaction between the cargo material and the cementitious matrix is also provided using x-ray diffraction analysis.

Untangling climate signals from autogenic changes in long-term peatland development

NASA Astrophysics Data System (ADS)

Morris, Paul J.; Baird, Andy J.; Young, Dylan M.; Swindles, Graeme T.

2015-12-01

Peatlands represent important archives of Holocene paleoclimatic information. However, autogenic processes may disconnect peatland hydrological behavior from climate and overwrite climatic signals in peat records. We use a simulation model of peatland development driven by a range of Holocene climate reconstructions to investigate climate signal preservation in peat records. Simulated water-table depths and peat decomposition profiles exhibit homeostatic recovery from prescribed changes in rainfall, whereas changes in temperature cause lasting alterations to peatland structure and function. Autogenic ecohydrological feedbacks provide both high- and low-pass filters for climatic information, particularly rainfall. Large-magnitude climatic changes of an intermediate temporal scale (i.e., multidecadal to centennial) are most readily preserved in our simulated peat records. Simulated decomposition signals are offset from the climatic changes that generate them due to a phenomenon known as secondary decomposition. Our study provides the mechanistic foundations for a framework to separate climatic and autogenic signals in peat records.

Autogenic-feedback training - A treatment for motion and space sickness

NASA Technical Reports Server (NTRS)

Cowings, Patricia S.

1990-01-01

A training method for preventing the occurrence of motion sickness in humans, called autogenic-feedback training (AFT), is described. AFT is based on a combination of biofeedback and autogenic therapy which involves training physiological self-regulation as an alternative to pharmacological management. AFT was used to reliably increase tolerance to motion-sickness-inducing tests in both men and women ranging in age from 18 to 54 years. The effectiveness of AFT is found to be significantly higher than that of protective adaptation training. Data obtained show that there is no apparent effect from AFT on measures of vestibular perception and no side effects.

Alternative methods for determining shrinkage in restorative resin composites.

PubMed

de Melo Monteiro, Gabriela Queiroz; Montes, Marcos Antonio Japiassú Resende; Rolim, Tiago Vieira; de Oliveira Mota, Cláudia Cristina Brainer; de Barros Correia Kyotoku, Bernardo; Gomes, Anderson Stevens Leônidas; de Freitas, Anderson Zanardi

2011-08-01

The purpose of this study was to evaluate polymerization shrinkage of resin composites using a coordinate measuring machine, optical coherence tomography and a more widely known method, such as Archimedes Principle. Two null hypothesis were tested: (1) there are no differences between the materials tested; (2) there are no differences between the methods used for polymerization shrinkage measurements. Polymerization shrinkage of seven resin-based dental composites (Filtek Z250™, Filtek Z350™, Filtek P90™/3M ESPE, Esthet-X™, TPH Spectrum™/Dentsply 4 Seasons™, Tetric Ceram™/Ivoclar-Vivadent) was measured. For coordinate measuring machine measurements, composites were applied to a cylindrical Teflon mold (7 mm × 2 mm), polymerized and removed from the mold. The difference between the volume of the mold and the volume of the specimen was calculated as a percentage. Optical coherence tomography was also used for linear shrinkage evaluations. The thickness of the specimens was measured before and after photoactivation. Polymerization shrinkage was also measured using Archimedes Principle of buoyancy (n=5). Statistical analysis of the data was performed with ANOVA and the Games-Howell test. The results show that polymerization shrinkage values vary with the method used. Despite numerical differences the ranking of the resins was very similar with Filtek P90 presenting the lowest shrinkage values. Because of the variations in the results, reported values could only be used to compare materials within the same method. However, it is possible rank composites for polymerization shrinkage and to relate these data from different test methods. Independently of the method used, reduced polymerization shrinkage was found for silorane resin-based composite. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of cementitious permanent formwork on moisture field of internal-cured concrete under drying

NASA Astrophysics Data System (ADS)

Wang, Jiahe; Zhang, Jun; Ding, Xiaoping; Zhang, Jiajia

2018-02-01

Drying shrinkage of concrete may still be the main source of cracking in concrete structures, even though the autogenous shrinkage of concrete can be effectively reduced by using internal curing. In the present paper, the effect of internal curing with pre-soaked lightweight aggregate and engineered cementitious composite permanent formwork (ECC-PF) on a moisture distribution in three kinds of concrete in a drying environment are investigated from both aspects of experiments and theoretical modeling. The test results show that the combination use of ECC-PF and internal curing can well maintain the humidity at a relatively high level not only at a place far from drying surface, but also at a place close to the drying surfaces. The developed model can well catch the characteristics of the moisture distribution in concrete under drying and the impacts of internal curing and ECC-PF can well be reflected as well. The model can be used for the design of concrete structures with combination use of internal curing and permanent formwork.

Application of autogenic training in patients with Ménière disease.

PubMed

Goto, Fumiyuki; Nakai, Kimiko; Ogawa, Kaoru

2011-10-01

Data are limited on the role of psychotherapy in the treatment of Ménière disease. We sought to document the effect of a psychotherapeutic technique known as autogenic training on clinical outcome in Ménière disease. Six patients with Ménière disease were studied. Retrospective chart review was conducted. All patients were refractory to conventional therapy and completed a course of autogenic training, which was offered as a complementary treatment. Autogenic training with initial psychological counseling was conducted by a clinical psychologist during 45-min sessions. Outcome measures assessed were the frequency of vertigo and functional levels 2 years after initiation of autogenic training. Functional levels were evaluated according to the 1995 guidelines of the American Academy of Otolaryngology-Head Neck Surgery (AAO-HNS). As a personality measure, we used the Maudsley Personality Inventory (MPI), devised by Eysenck, which measures neuroticism (N), extraversion (E), and propensity to lie (L). Five of six patients showed improved functional level after three to eight sessions of psychotherapy; hearing level did not change. The score of the N scale of the MPI was closely related to the number of psychotherapy sessions. Prognosis was evaluated based on the AAO-HNS reporting guidelines, as follows: A = 3, B = 1, C = 1, F = 1. The value of N in MPI was closely related to the number of psychological counseling sessions (R = 0.97, P < 0.05). In conclusion, autogenic training may enhance the mental well-being of patients with Ménière disease and improve clinical outcome.

Simulation model of fatigue crack opening/closing phenomena for predicting RPG load under arbitrary stress distribution field

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

Toyosada, M.; Niwa, T.

1995-12-31

In this paper, Newman`s calculation model is modified to solve his neglected effect of the change of stress distribution ahead of a crack, and to leave elastic plastic materials along the crack surface because of the compatibility of Dugdale model. In addition to above treatment, the authors introduce plastic shrinkage at an immediate generation of new crack surfaces due to emancipation of internal force with the magnitude of yield stress level during unloading process in the model. Moreover, the model is expanded to arbitrary stress distribution field. By using the model, RPG load is simulated for a center notched specimenmore » under constant amplitude loading with various stress ratios and decreased maximum load while keeping minimum load.« less

Autogenic training alters cerebral activation patterns in fMRI.

PubMed

Schlamann, Marc; Naglatzki, Ryan; de Greiff, Armin; Forsting, Michael; Gizewski, Elke R

2010-10-01

Cerebral activation patterns during the first three auto-suggestive phases of autogenic training (AT) were investigated in relation to perceived experiences. Nineteen volunteers trained in AT and 19 controls were studied with fMRI during the first steps of autogenic training. FMRI revealed activation of the left postcentral areas during AT in those with experience in AT, which also correlated with the level of AT experience. Activation of prefrontal and insular cortex was significantly higher in the group with experience in AT while insular activation was correlated with number years of simple relaxation exercises. Specific activation in subjects experienced in AT may represent a training effect. Furthermore, the correlation of insular activation suggests that these subjects are different from untrained subjects in emotional processing or self-awareness.

Strategies to overcome polymerization shrinkage--materials and techniques. A review.

PubMed

Malhotra, Neeraj; Kundabala, M; Shashirashmi, Acharya

2010-03-01

Stress generation at tissue/resin composite interfaces is one of the important reasons for failure of resin-based composite (RBC) restorations owing to the inherent property of polymerization shrinkage. Unrelieved stresses can weaken the bond between the tooth structure and the restoration, eventually producing a gap at the restoration margins. This can lead to postoperative sensitivity, secondary caries, fracture of the restorations, marginal deterioration and discoloration. As polymerization shrinkage cannot be eliminated completely, various techniques and protocols have been suggested in the manipulation of, and restorative procedures for, RBCs to minimize the shrinkage and associated stresses. Introduction of various newer monomer systems (siloranes) may also overcome this problem of shrinkage stress. This review emphasizes the various material science advances and techniques advocated that are currently available or under trial/testing phase to deal with polymerization shrinkage in a clinical environment. Minimizing the shrinkage stresses in RBC restorations may lead to improvement in the success rate and survival of restorations. Thus, it is important for dental practitioners to be aware of various techniques and materials available to reduce these shrinkage stresses and be updated with the current knowledge available to deal with this issue.

Cloning and expression of autogenes encoding RNA polymerases of T7-like bacteriophages

DOEpatents

Studier, F. William; Dubendorff, John W.

1998-01-01

This invention relates to the cloning and expression of autogenes encoding RNA polymerases of T7 and T7-like bacteriophages, in which the RNA polymerase gene is transcribed from a promoter which is recognized by the encoded RNA polymerase. Cloning of T7 autogenes was achieved by reducing the activity of the RNA polymerase sufficiently to permit host cell growth. T7 RNA polymerase activity was controlled by combining two independent methods: lac-repression of the recombinant lac operator-T7 promoter in the autogene and inhibition of the polymerase by T7 lysozyme. Expression systems for producing the RNA polymerases of T7 and other T7-like bacteriophages, and expression systems for producing selected gene products are described, as well as other related materials and methods.

Cloning and expression of autogenes encoding RNA polymerases of T7-like bacteriophages

DOEpatents

Studier, F.W.; Dubendorff, J.W.

1998-10-20

This invention relates to the cloning and expression of autogenes encoding RNA polymerases of T7 and T7-like bacteriophages, in which the RNA polymerase gene is transcribed from a promoter which is recognized by the encoded RNA polymerase. Cloning of T7 autogenes was achieved by reducing the activity of the RNA polymerase sufficiently to permit host cell growth. T7 RNA polymerase activity was controlled by combining two independent methods: lac-repression of the recombinant lac operator-T7 promoter in the autogene and inhibition of the polymerase by T7 lysozyme. Expression systems for producing the RNA polymerases of T7 and other T7-like bacteriophages, and expression systems for producing selected gene products are described, as well as other related materials and methods. 12 figs.

Cloning and expression of autogenes encoding RNA polymerases of T7-like bacteriophages

DOEpatents

Studier, F.W.; Dubendorff, J.W.

1998-11-03

This invention relates to the cloning and expression of autogenes encoding RNA polymerases of T7 and T7-like bacteriophages, in which the RNA polymerase gene is transcribed from a promoter which is recognized by the encoded RNA polymerase. Cloning of T7 autogenes was achieved by reducing the activity of the RNA polymerase sufficiently to permit host cell growth. T7 RNA polymerase activity was controlled by combining two independent methods: lac-repression of the recombinant lac operator-T7 promoter in the autogene and inhibition of the polymerase by T7 lysozyme. Expression systems for producing the RNA polymerases of T7 and other T7-like bacteriophages, and expression systems for producing selected gene products are described, as well as other related materials and methods. 12 figs.

Evaluation of the efficacy of an autogenous Escherichia coli vaccine in broiler breeders.

PubMed

Li, Lili; Thøfner, Ida; Christensen, Jens Peter; Ronco, Troels; Pedersen, Karl; Olsen, Rikke H

2017-06-01

In poultry production Escherichia coli autogenous vaccines are often used. However, the efficacy of autogenous E. coli vaccinations has not been evaluated experimentally in chickens after start of lay. The aim of the present study was to evaluate the protective effect of an autogenous E. coli vaccine in broiler breeders. Three groups of 28-week-old broiler breeders (unvaccinated, vaccinated once and twice, respectively) were challenged with a homologous E. coli strain (same strain as included in the vaccine) or a heterologous challenge strain in an experimental ascending model. The clinical outcome was most pronounced in the unvaccinated group; however, the vast majority of chickens in the vaccinated groups had severe pathological manifestations similar to findings in the unvaccinated group after challenge with a homologous as well as a heterologous E. coli strain. Although significant titre rises in IgY antibodies were observed in the twice vaccinated group, antibodies did not confer significant protection in terms of pathological impact. Neither could transfer of maternal-derived antibodies to offspring be demonstrated. In conclusion, with the use of the present model for ascending infection, significant protection of an autogenous E. coli vaccine against neither a homologous nor a heterologous E. coli challenge could not be documented.

A study of polymerization shrinkage kinetics using digital image correlation.

PubMed

Lau, Andrew; Li, Jianying; Heo, Young Cheul; Fok, Alex

2015-04-01

To investigate the polymerization shrinkage kinetics of dental resin composites by measuring in real time the full-field shrinkage strain using a novel technique based on digital image correlation (DIC). Polymerization shrinkage in resin composite specimens (Filtek LS and Z100) was measured as a function of time and position. The main experimental setup included a CCD camera and an external shutter inversely synchronized to that of the camera. The specimens (2 mm × 4 mm × 5 mm) were irradiated for 40s at 1200 mW/cm(2), while alternating image acquisition and obstruction of the curing light occurred at 15 fps. The acquired images were processed using proprietary software to obtain the full-field strain maps as a function of time. Z100 showed a higher final shrinkage value and rate of development than LS. The final volumetric shrinkage for Z100 and LS were 1.99% and 1.19%, respectively. The shrinkage behavior followed an established shrinkage strain kinetics model. The corresponding characteristic time and reaction order exponent for LS and Z100 were calculated to be approximately 23s and 0.84, and 14s and 0.7, respectively, at a distance of 1.0mm from the irradiated surface, the position where maximum shrinkage strain occurred. Thermal expansion from the exothermic reaction could have affected the accuracy of these parameters. The new DIC method using an inversely synchronized shutter provided realtime, full-field results that could aid in assessing the shrinkage strain kinetics of dental resin composites as a function of specimen depth. It could also help determine the optimal curing modes for dental resin composites. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Variation of Shrinkage Strain within the Depth of Concrete Beams.

PubMed

Jeong, Jong-Hyun; Park, Yeong-Seong; Lee, Yong-Hak

2015-11-16

The variation of shrinkage strain within beam depth was examined through four series of time-dependent laboratory experiments on unreinforced concrete beam specimens. Two types of beam specimens, horizontally cast and vertically cast, were tested; shrinkage variation was observed in the horizontally cast specimens. This indicated that the shrinkage variation within the beam depth was due to water bleeding and tamping during the placement of the fresh concrete. Shrinkage strains were measured within the beam depth by two types of strain gages, surface-attached and embedded. The shrinkage strain distribution within the beam depth showed a consistent tendency for the two types of gages. The test beams were cut into four sections after completion of the test, and the cutting planes were divided into four equal sub-areas to measure the aggregate concentration for each sub-area of the cutting plane. The aggregate concentration increased towards the bottom of the beam. The shrinkage strain distribution was estimated by Hobbs' equation, which accounts for the change of aggregate volume concentration.

Variation of Shrinkage Strain within the Depth of Concrete Beams

PubMed Central

Jeong, Jong-Hyun; Park, Yeong-Seong; Lee, Yong-Hak

2015-01-01

The variation of shrinkage strain within beam depth was examined through four series of time-dependent laboratory experiments on unreinforced concrete beam specimens. Two types of beam specimens, horizontally cast and vertically cast, were tested; shrinkage variation was observed in the horizontally cast specimens. This indicated that the shrinkage variation within the beam depth was due to water bleeding and tamping during the placement of the fresh concrete. Shrinkage strains were measured within the beam depth by two types of strain gages, surface-attached and embedded. The shrinkage strain distribution within the beam depth showed a consistent tendency for the two types of gages. The test beams were cut into four sections after completion of the test, and the cutting planes were divided into four equal sub-areas to measure the aggregate concentration for each sub-area of the cutting plane. The aggregate concentration increased towards the bottom of the beam. The shrinkage strain distribution was estimated by Hobbs’ equation, which accounts for the change of aggregate volume concentration. PMID:28793677

Post-resection mucosal margin shrinkage in oral cancer: quantification and significance.

PubMed

Mistry, Rajesh C; Qureshi, Sajid S; Kumaran, C

2005-08-01

The importance of tumor free margins in outcome of cancer surgery is well known. Often the pathological margins are reported to be significantly smaller than the in situ margins. This discrepancy is due to margin shrinkage the quantum of which has not been studied in patients with oral cancers. To quantify the shrinkage of mucosal margin following excision for carcinoma of the oral tongue and buccal mucosa. Mucosal margins were measured prior to resection and half an hour after excision in 27 patients with carcinoma of the tongue and buccal mucosa. The mean margin shrinkage was assessed and the variables affecting the quantum of shrinkage analyzed. The mean shrinkage from the in situ to the post resection margin status was 22.7% (P < 0.0001). The mean shrinkage of the tongue margins was 23.5%, compared to 21.2% for buccal mucosa margins. The mean shrinkage in T1/T2 tumors (25.6%) was significantly more than in T3/T4 (9.2%, P < 0.011). There is significant shrinkage of mucosal margins after surgery. Hence this should be considered and appropriate margins should be taken at initial resection to prevent the agony of post-operative positive surgical margins. Copyright 2005 Wiley-Liss, Inc.

[Comparative study on graft of autogeneic iliac bone and tissue engineered bone].

PubMed

Shen, Bing; Xie, Fu-lin; Xie, Qing-fang

2002-11-01

To compare the clinical results of repairing bone defect of limbs with tissue engineering technique and with autogeneic iliac bone graft. From July 1999 to September 2001, 52 cases of bone fracture were randomly divided into two groups (group A and B). Open reduction and internal fixation were performed in all cases as routine operation technique. Autogeneic iliac bone was implanted in group A, while tissue engineered bone was implanted in group B. Routine postoperative treatment in orthopedic surgery was taken. The operation time, bleeding volume, wound healing and drainage volume were compared. The bone union was observed by the X-ray 1, 2, 3, and 5 months after operation. The sex, age and disease type had no obvious difference between groups A and B. all the wounds healed with first intention. The swelling degree of wound and drainage volume had no obvious difference. The operation time in group A was longer than that in group B (25 minutes on average) and bleeding volume in group A was larger than that in group B (150 ml on average). Bone union completed within 3 to 7 months in both groups. But there were 2 cases of delayed union in group A and 1 case in group B. Repair of bone defect with tissue engineered bone has as good clinical results as that with autogeneic iliac bone graft. In aspect of operation time and bleeding volume, tissue engineered bone graft is superior to autogeneic iliac bone.

Thermoelectrically controlled device for studies of temperature-induced corneal shrinkage

NASA Astrophysics Data System (ADS)

Borja, David; Manns, Fabrice; Fernandez, Viviana; Lamar, Peggy; Soederberg, Per G.; Parel, Jean-Marie A.

2002-06-01

The purpose of this study was to design and calibrate a device to measure the dynamics of thermal shrinkage in corneal and scleral strips. The apparatus consists of a thermoelectric cell controlled by a temperature controller designed to generate temperatures up to 90 degree(s)C in rectangular corneal strips; a copper cuvette filled with Dextran solution that holds the corneal strip and a displacement sensor that measures the change in length of the tissue during heat-induced shrinkage. The device was tested on corneal tissue from Florida Eye-Bank eyes that were cut into 2x4mm rectangular strips. Preliminary results indicate that our system can reproducibly create and accurately measure thermally induced corneal shrinkage. Shrinkage experiments will be used to optimize laser parameters for corneal shrinkage during laser thermokeratoplasty and laser scleral buckling.

[Development of Autogenic Training Clinical Effectiveness Scale (ATCES)].

PubMed

Ikezuki, Makoto; Miyauchi, Yuko; Yamaguchi, Hajime; Koshikawa, Fusako

2002-02-01

The purpose of the present study was to develop a scale measuring clinical effectiveness of autogenic training. In Study 1, 167 undergraduates completed a survey of items concerning physical and mental states, which were thought to vary in the course of autogenic training. With item and factor analyses, 20 items were selected, and the resulting scale (ATCES) had high discrimination and clear factor structure. In Study 2, reliability and concurrent and clinical validity of the scale were examined with three groups of respondents: 85 mentally healthy, 31 control, 13 clinical persons. The scale showed a high test-retest correlation (r = .83) and alpha coefficient (alpha = .86). ATCES had a Pearson correlation coefficient of r = .56 with General Health Questionnaire (GHQ-12), and r = .73 with trait anxiety (STAI-T). And ATCES successfully discriminated the mentally healthy and clinical groups in terms of clinical effectiveness. These results demonstrated high reliability and sufficient concurrent and clinical validity of the new scale.

Influence of length-to-diameter ratio on shrinkage of basalt fiber concrete

NASA Astrophysics Data System (ADS)

Ruijie, MA; Yang, Jiansen; Liu, Yuan; Zheng, Xiaojun

2017-09-01

In order to study the shrinkage performance of basalt concrete, using the shrinkage rate as index, the work not only studied the influence of different length-to-diameter ratio (LDR) on plastic shrinkage and drying shrinkage of basalt fiber concrete, but also analyzed the action mechanism. The results show that when the fiber content is 0.1%, the LDR of 800 and 1200 take better effects on reducing plastic shrinkage, however the fiber content is 0.3%, that of LDR 600 is better. To improve drying shrinkage, the fiber of LDR 800 takes best effect. In the concrete structure, the adding basalt fibers form a uniform and chaotic supporting system, optimize the pore and the void structure of concrete, make the material further compacted, reduce the water loss, so as to decrease the shrinkage of concrete effectively.

Creep and shrinkage effects on integral abutment bridges

NASA Astrophysics Data System (ADS)

Munuswamy, Sivakumar

Integral abutment bridges provide bridge engineers an economical design alternative to traditional bridges with expansion joints owing to the benefits, arising from elimination of expensive joints installation and reduced maintenance cost. The superstructure for integral abutment bridges is cast integrally with abutments. Time-dependent effects of creep, shrinkage of concrete, relaxation of prestressing steel, temperature gradient, restraints provided by abutment foundation and backfill and statical indeterminacy of the structure introduce time-dependent variations in the redundant forces. An analytical model and numerical procedure to predict instantaneous linear behavior and non-linear time dependent long-term behavior of continuous composite superstructure are developed in which the redundant forces in the integral abutment bridges are derived considering the time-dependent effects. The redistributions of moments due to time-dependent effects have been considered in the analysis. The analysis includes nonlinearity due to cracking of the concrete, as well as the time-dependent deformations. American Concrete Institute (ACI) and American Association of State Highway and Transportation Officials (AASHTO) models for creep and shrinkage are considered in modeling the time dependent material behavior. The variations in the material property of the cross-section corresponding to the constituent materials are incorporated and age-adjusted effective modulus method with relaxation procedure is followed to include the creep behavior of concrete. The partial restraint provided by the abutment-pile-soil system is modeled using discrete spring stiffness as translational and rotational degrees of freedom. Numerical simulation of the behavior is carried out on continuous composite integral abutment bridges and the deformations and stresses due to time-dependent effects due to typical sustained loads are computed. The results from the analytical model are compared with the

Cloning and expression of autogenes encoding RNA poly,erases of T7-like bacteriophages

DOEpatents

Studier, F. William; Dubendorff, John W.

1998-01-01

This invention relates to the cloning and expression of autogenes encoding RNA polymerases of T7 and T7-like bacteriophages, in which the RNA polymerase gene is transcribed from a promoter which is recognized by the encoded RNA polymerase. Cloning of T7 autogenes was achieved by reducing the activity of the RNA polymerase sufficiently to permit host cell growth. T7 RNA polymerase activity was controlled by combining two independent methods: lac-repression of the recombinant lac operator-T7 promoter in the autogene and inhibition of the polymerase by T7 lysozyme. Expression systems for producing the RNA polymerases of T7 and other T7-like bacteriophages, and expression systems for producing selected gene products are described, as well as other related materials and methods.

Autogenous teeth used for bone grafting: A systematic review.

PubMed

Gual-Vaqués, P; Polis-Yanes, C; Estrugo-Devesa, A; Ayuso-Montero, R; Mari-Roig, A; López-López, J

2018-01-01

Recently, bone graft materials using permanent teeth have come to light, and clinical and histological outcomes of this material have been confirmed by some studies. The aim of this systematic review was to evaluate the reliability of the autogenous tooth bone graft material applied to alveolar ridge augmentation procedures. A systematic review of literature was conducted analyzing articles published between 2007 and 2017. The following four outcome variables were defined: a) implant stability b) post-operative complication c) evaluation of implant survival and failure rates, and d) histological analysis. A total of 108 articles were identified; 6 were selected for review. Based on the PICO (problem, intervention, comparison, outcome) model, the chief question of this study was: Can patients with alveolar ridge deficiency be successfully treated with the autogenous teeth used as bone graft? The mean primary stability of the placed implants was 67.3 ISQ and the mean secondary stability was 75.5 ISQ. The dehiscence of the wound was the most frequent complication with a rate of 29.1%. Of the 182 analyzed implants, the survival rate was 97.7% and the failure rate was 2.3%. In the histological analysis, most of studies reported bone formation. There is insufficient evidence regarding the effects of autogenous teeth used for bone grafting to support any definitive conclusions, although it has been shown clinically safe and good bone forming capacity, and good results are shown about implant stability.

Autogenous transplantation of teeth with complete root formation: two case reports.

PubMed

Teixeira, C S; Pasternak, B; Vansan, L P; Sousa-Neto, M D

2006-12-01

Autotransplantation is an alternative treatment for replacing lost teeth when suitable donor teeth are available. This paper presents two cases of successful autogenous tooth transplantation. Two third molars with complete root development were autogenously transplanted from their original sockets into new recipient sites on the same side of the mouth, one in the maxilla and one in the mandible. In both cases, the third molars were transplanted immediately after the first molar extractions. To provide better adaptation of the donor teeth, the recipient alveolar sites were remodelled using surgical burs. Semi-rigid splints were maintained for 45 and 15 days, respectively. Root canal treatment commenced one a week after transplantation and the canals were medicated with a calcium hydroxide paste before they were filled. Clinical and radiographic findings after 5 and 3 years of follow-up, respectively, are discussed in relation to the literature. Autogenous transplantation of teeth with complete root formation may be considered as a viable treatment option to conventional prosthetic and implant rehabilitation for both therapeutic and economic reasons. Careful surgical and endodontic procedure, together with careful case selection may lead to satisfactory aesthetic and functional outcomes.

Fatigue resistance and crack propensity of large MOD composite resin restorations: direct versus CAD/CAM inlays.

PubMed

Batalha-Silva, Silvana; de Andrada, Mauro Amaral Caldeira; Maia, Hamilton Pires; Magne, Pascal

2013-03-01

To assess the influence of material/technique selection (direct vs. CAD/CAM inlays) for large MOD composite adhesive restorations and its effect on the crack propensity and in vitro accelerated fatigue resistance. A standardized MOD slot-type tooth preparation was applied to 32 extracted maxillary molars (5mm depth and 5mm bucco-palatal width) including immediately sealed dentin for the inlay group. Fifteen teeth were restored with direct composite resin restoration (Miris2) and 17 teeth received milled inlays using Paradigm MZ100 block in the CEREC machine. All inlays were adhesively luted with a light curing composite resin (Filtek Z100). Enamel shrinkage-induced cracks were tracked with photography and transillumination. Cyclic isometric chewing (5 Hz) was simulated, starting with a load of 200 N (5000 cycles), followed by stages of 400, 600, 800, 1000, 1200 and 1400 N at a maximum of 30,000 cycles each. Samples were loaded until fracture or to a maximum of 185,000 cycles. Teeth restored with the direct technique fractured at an average load of 1213 N and two of them withstood all loading cycles (survival=13%); with inlays, the survival rate was 100%. Most failures with Miris2 occurred above the CEJ and were re-restorable (67%), but generated more shrinkage-induced cracks (47% of the specimen vs. 7% for inlays). CAD/CAM MZ100 inlays increased the accelerated fatigue resistance and decreased the crack propensity of large MOD restorations when compared to direct restorations. While both restorative techniques yielded excellent fatigue results at physiological masticatory loads, CAD/CAM inlays seem more indicated for high-load patients. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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

Asamoto, Shingo, E-mail: asamoto@mail.saitama-u.ac.j; Ohtsuka, Ayumu; Kuwahara, Yuta

In this paper, the effects of actual environmental actions on shrinkage, creep and shrinkage cracking of concrete are studied comprehensively. Prismatic specimens of plain concrete were exposed to three sets of artificial outdoor conditions with or without solar radiation and rain to examine the shrinkage. For the purpose of studying shrinkage cracking behavior, prismatic concrete specimens with reinforcing steel were also subjected to the above conditions at the same time. The shrinkage behavior is described focusing on the effects of solar radiation and rain based on the moisture loss. The significant environment actions to induce shrinkage cracks are investigated frommore » viewpoints of the amount of the shrinkage and the tensile strength. Finally, specific compressive creep behavior according to solar radiation and rainfall is discussed. It is found that rain can greatly inhibit the progresses of concrete shrinkage and creep while solar radiation is likely to promote shrinkage cracking and creep.« less

Short-Term Effect of Autogenic Drainage on Ventilation Inhomogeneity in Adult Subjects With Stable Non-Cystic Fibrosis Bronchiectasis.

PubMed

Poncin, William; Reychler, Grégory; Leeuwerck, Noémie; Bauwens, Nathalie; Aubriot, Anne-Sophie; Nader, Candice; Liistro, Giuseppe; Gohy, Sophie

2017-05-01

Lung clearance index (LCI), a measure of ventilation inhomogeneity derived from a multiple-breath washout test, is a promising tool for assessing airway function in patients with non-cystic fibrosis bronchiectasis. However, it is unknown whether ventilation inhomogeneity could improve after successful elimination of excessive secretions within bronchiectasis. The objective of this work was to assess the short-term effects of lung secretion clearance using the autogenic drainage technique on standard lung function tests and LCI in subjects with non-cystic fibrosis bronchiectasis. Nitrogen-based multiple-breath washout, spirometry, and body plethysmography tests were performed 30 min before autogenic drainage in adults with stable non-cystic fibrosis bronchiectasis. The autogenic drainage session was followed by a 5-min break, after which the tests were repeated in the same order. Sputum expectorated during autogenic drainage was quantified as dry weight and correlated with change between post- and pre-measurements (Δ). Paired t test or Wilcoxon signed-rank tests were used to compare pre- and post-autogenic drainage measurement outcomes. A P value of ≤.05 was considered as statistically significant. Twenty-four subjects were studied (18 females, median age [range]: 65 [21-81] y). Mean ± SD LCI significantly improved after autogenic drainage (10.88 ± 2.62 vs 10.53 ± 2.35, P = .042). However, only 20% of subjects with mucus hyperproduction during autogenic drainage had a ΔLCI that exceeded measurement variability. The percent of predicted slow vital capacity (SVC%) also slightly improved (88.7 ± 19.3% vs 90 ± 19.1%, P = .02). ΔLCI was inversely related to dry sputum weight (r = -.48, P = .02) and ΔSVC% (r = -.64, P = .001). ΔSVC% also correlated with dry sputum weight (r = 0.46, P = .02). In adults with non-cystic fibrosis bronchiectasis and mucus hypersecretion, autogenic drainage improved ventilation inhomogeneity. LCI change may be the result of the

Method for Assessment of Changes in the Width of Cracks in Cement Composites with Use of Computer Image Processing and Analysis

NASA Astrophysics Data System (ADS)

Tomczak, Kamil; Jakubowski, Jacek; Fiołek, Przemysław

2017-06-01

Crack width measurement is an important element of research on the progress of self-healing cement composites. Due to the nature of this research, the method of measuring the width of cracks and their changes over time must meet specific requirements. The article presents a novel method of measuring crack width based on images from a scanner with an optical resolution of 6400 dpi, subject to initial image processing in the ImageJ development environment and further processing and analysis of results. After registering a series of images of the cracks at different times using SIFT conversion (Scale-Invariant Feature Transform), a dense network of line segments is created in all images, intersecting the cracks perpendicular to the local axes. Along these line segments, brightness profiles are extracted, which are the basis for determination of crack width. The distribution and rotation of the line of intersection in a regular layout, automation of transformations, management of images and profiles of brightness, and data analysis to determine the width of cracks and their changes over time are made automatically by own code in the ImageJ and VBA environment. The article describes the method, tests on its properties, sources of measurement uncertainty. It also presents an example of application of the method in research on autogenous self-healing of concrete, specifically the ability to reduce a sample crack width and its full closure within 28 days of the self-healing process.

A new method to measure the polymerization shrinkage kinetics of light cured composites.

PubMed

Lee, I B; Cho, B H; Son, H H; Um, C M

2005-04-01

This study was undertaken to develop a new measurement method to determine the initial dynamic volumetric shrinkage of composite resins during polymerization, and to investigate the effect of curing light intensity on the polymerization shrinkage kinetics. The instrument was basically an electromagnetic balance that was constructed with a force transducer using a position sensitive photo detector (PSPD) and a negative feedback servo amplifier. The volumetric change of composites during polymerization was detected continuously as a buoyancy change in distilled water by means of the Archimedes' principle. Using this new instrument, the dynamic patterns of the polymerization shrinkage of seven commercial composite resins were measured. The polymerization shrinkage of the composites was 1.92 approximately 4.05 volume %. The shrinkage of a packable composite was the lowest, and that of a flowable composite was the highest. The maximum rate of polymerization shrinkage increased with increasing light intensity but the peak shrinkage rate time decreased with increasing light intensity. A strong positive relationship was observed between the square root of the light intensity and the maximum shrinkage rate. The shrinkage rate per unit time, dVol%/dt, showed that the instrument can be a valuable research method for investigating the polymerization reaction kinetics. This new shrinkage-measuring instrument has some advantages that it was insensitive to temperature changes and could measure the dynamic volumetric shrinkage in real time without complicated processes. Therefore, it can be used to characterize the shrinkage kinetics in a wide range of commercial and experimental visible-light-cure materials in relation to their composition and chemistry.

Monitoring of pre-release cracks in prestressed concrete using fiber optic sensors

NASA Astrophysics Data System (ADS)

Abdel-Jaber, Hiba; Glisic, Branko

2015-04-01

Prestressed concrete experiences low to no tensile stresses, which results in limiting the occurrence of cracks in prestressed concrete structures. However, the nature of construction of these structures requires the concrete not to be subjected to the compressive force from the prestressing tendons until after it has gained sufficient compressive strength. Although the structure is not subjected to any dead or live load during this period, it is influenced by shrinkage and thermal variations. Thus, the concrete can experience tensile stresses before the required compressive strength has been attained, which can result in the occurrence of "pre-release" cracks. Such cracks are visually closed after the transfer of the prestressing force. However, structural capacity and behavior can be impacted if cracks are not sufficiently closed. This paper researches a method for the verification of the status of pre-release cracks after transfer of the prestressing force, and it is oriented towards achievement of Level IV Structural Health Monitoring (SHM). The method relies on measurements from parallel long-gauge fiber optic sensors embedded in the concrete prior to pouring. The same sensor network is used for the detection and characterization of cracks, as well as the monitoring of the prestressing force transfer and the determination of the extent of closure of pre-release cracks. This paper outlines the researched method and presents its application to a real-life structure, the southeast leg of Streicker Bridge on the Princeton University campus. The application structure is a curved continuous girder that was constructed in 2009. Its deck experienced four pre-release cracks that were closed beyond the critical limits based on the results of this study.

Roof System EPDM Shrinkage.

ERIC Educational Resources Information Center

Betker, Edward

1998-01-01

Looks at Ethylene Propylene Diene Terpolymer rubber roof membranes and the potential problems associated with this material's shrinkage. Discusses how long such a roof should perform and issues affecting repair or replacement. Recommends that a building's function be considered in any roofing decision. (RJM)

Health, Height, Height Shrinkage, and SES at Older Ages: Evidence from China†

PubMed Central

Huang, Wei; Lei, Xiaoyan; Ridder, Geert; Strauss, John

2015-01-01

In this paper, we build on the literature that examines associations between height and health outcomes of the elderly. We investigate the associations of height shrinkage at older ages with socioeconomic status, finding that height shrinkage for both men and women is negatively associated with better schooling, current urban residence, and household per capita expenditures. We then investigate the relationships between pre-shrinkage height, height shrinkage, and a rich set of health outcomes of older respondents, finding that height shrinkage is positively associated with poor health outcomes across a variety of outcomes, being especially strong for cognition outcomes. PMID:26594311

30 CFR 35.20 - Autogenous-ignition temperature test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... timer shall be stopped. The test flask shall then be flushed well with clean dry air and, after a lapse... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Autogenous-ignition temperature test. 35.20..., EVALUATION, AND APPROVAL OF MINING PRODUCTS FIRE-RESISTANT HYDRAULIC FLUIDS Test Requirements § 35.20...

[Effect of autogenic training on glucose regulation and lipid status in non-insulin dependent diabetics].

PubMed

Kostić, N; Secen, S

2000-01-01

The objective of this study was to examine the benefits of autogenic training in patients with type 2 diabetes and 40 diabetics treated with oral antidiabetic agents were assigned to receive autogenic training. Treatment effects on GHb levels, glycemia, lipids and lipid peroxidases were evaluated after 12 weeks. Subjects demonstrated significant improvements of GHb level (8.94 +/- 2.21% vs. 7.9 +/- 2.395) (p < 0.005). Fasting glucose was significantly lower after treatment (11.6 +/- 6.1 mmol/l vs. 8.32 +/- 4.53 mmol/l) (p < 0.005). The serum level of HDL cholesterol was significantly higher after autogenic training (1.21 +/- 0.11 vs. 1.36 +/- 1.42) (p < 0.005). Cholesterol level was significantly lower after training (6.63 +/- 1.66 mmol/l vs. 6.10 +/- 1.12 mmol/l) (p < 0.05). Lipid peroxidase was significantly lower after treatment (4.05 +/- 0.58 vs. 3.69 +/- 1.26) (p < 0.005). Autogenic training in selected patients, especially those who are most responsive to stress would provide benefits for glucosE control and lipid metabolism that are not always achieved by conventional treatment.

The effect of autogenic training and biofeedback on motion sickness tolerance.

PubMed

Jozsvai, E E; Pigeau, R A

1996-10-01

Motion sickness is characterized by symptoms of vomiting, drowsiness, fatigue and idiosyncratic changes in autonomic nervous system (ANS) responses such as heart rate (HR) and skin temperature (ST). Previous studies found that symptoms of motion sickness are controllable through self-regulation of ANS responses and the best method to teach such control is autogenic-feedback (biofeedback) training. Recent experiments indicated that biofeedback training is ineffective in reducing symptoms of motion sickness or in increasing tolerance to motion. If biofeedback facilitates learning of ANS self-regulation then autogenic training with true feedback (TFB) should lead to better control over ANS responses and better motion tolerance than autogenic training with false feedback (FFB). If there is a relationship between ANS self-regulation and coping with motion stress, a significant correlation should be found between amounts of control over ANS responses and measures of motion tolerance and/or symptoms of motion sickness. There were 3 groups of 6 subjects exposed for 6 weeks to weekly sessions of Coriolis stimulation to induce motion sickness. Between the first and second Coriolis sessions, subjects in the experimental groups received five episodes of autogenic training with either true (group TFB) or false (group FFB) feedback on their HR and ST. The control group (CTL) received no treatment. Subjects learned to control their HR and ST independent of whether they received true or false feedback. Learned control of ST and HR was not related to severity of motion sickness or subject's ability to withstand Coriolis stimulation following treatment. A lack of significant correlation between these variables suggested that subjects were not able to apply their skills of ANS self-regulation in the motion environment, and/ or such skills had little value in reducing symptoms of motion sickness or enhancing their ability to withstand rotations.

Determination of Coefficient of Thermal Expansion (CTE) of 20MPa Mass Concrete Using Granite Aggregate

NASA Astrophysics Data System (ADS)

Chee Siang, GO

2017-07-01

Experimental test was carried out to determine the coefficient of thermal expansion (CTE) value of 20MPa mass concrete using granite aggregate. The CTE value was established using procedure proposed by Kada et al. 2002 in determining the magnitude of early-ages CTE through laboratory test which is a rather accurate way by eliminating any possible superimposed effect of others early-age thermal deformation shrinkages such as autogenous, carbonation, plastic and drying shrinkage. This was done by submitting granite concrete block samples instrumented with ST4 vibrating wire extensometers to thermal shocks. The response of the concrete samples to this shock results in a nearly instantaneous deformation, which are measured by the sensor. These deformations, as well as the temperature signal, are used to calculate the CTE. By repeating heat cycles, the variation in the early-ages of concrete CTE over time was monitored and assessed for a period of upto 7 days. The developed CTE value facilitating the verification and validation of actual maximum permissible critical temperature differential limit (rather than arbitrarily follow published value) of cracking potential. For thick sections, internal restraint is dominant and this is governed by differentials mainly. Of the required physical properties for thermal modelling, CTE is of paramount importance that with given appropriate internal restraint factor the condition of cracking due to internal restraint is governs by equation, ΔTmax= 3.663ɛctu / αc. Thus, it can be appreciated that an increase in CTE will lower the maximum allowable differential for cracking avoidance in mass concrete while an increase of tensile strain capacity will increase the maximum allowable temperature differential.

Spectral analysis of the central nervous system effects of the relaxation response elicited by autogenic training.

PubMed

Jacobs, G D; Lubar, J F

1989-01-01

This study examined the effects of the relaxation response, elicited by autogenic training, on central nervous system (CNS) activity. We used computerized spectral analysis of EEG activity as a dependent measure. After baseline EEG data were obtained for all subjects, the experimental group practiced standard autogenic exercises for 15 experimental sessions with home practice. The control subjects received the same number of sessions under identical conditions, except that they listened to a pleasant radio show without home practice. Subjects were then posttested to assess the acute and chronic effects of autogenic training and the relaxation response on CNS activity. The results indicated significant acute effects differences between groups; the experimental group showed greater increases in theta and greater decreases in alpha percent total power. The results suggest that the relaxation response elicited by autogenic training produces significant acute changes in EEG activity and a characteristic spectral pattern; the results also suggest that focusing attention on a repetitive, internal stimulus is a key element in Benson's relaxation response model.

Comparison of autogeneic and allogeneic natural killer cells immunotherapy on the clinical outcome of recurrent breast cancer

PubMed Central

Liang, Shuzhen; Xu, Kecheng; Niu, Lizhi; Wang, Xiaohua; Liang, Yingqing; Zhang, Mingjie; Chen, Jibing; Lin, Mao

2017-01-01

In the present study, we aimed to compare the clinical outcome of autogeneic and allogeneic natural killer (NK) cells immunotherapy for the treatment of recurrent breast cancer. Between July 2016 and February 2017, 36 patients who met the enrollment criteria were randomly assigned to two groups: autogeneic NK cells immunotherapy group (group I, n=18) and allogeneic NK cells immunotherapy group (group II, n=18). The clinical efficacy, quality of life, immune function, circulating tumor cell (CTC) level, and other related indicators were evaluated. We found that allogeneic NK cells immunotherapy has better clinical efficacy than autogeneic therapy. Moreover, allogeneic NK cells therapy improves the quality of life, reduces the number of CTCs, reduces carcinoembryonic antigen and cancer antigen 15-3 (CA15-3) expression, and significantly enhances immune function. To our knowledge, this is the first clinical trial to compare the clinical outcome of autogeneic and allogeneic NK cells immunotherapy for recurrent breast cancer. PMID:28894383

Treatment of Childhood Migraine Using Autogenic Feedback Training.

ERIC Educational Resources Information Center

Labbe, Elise L.

1984-01-01

Compared autogenic feedback training with a waiting-list control group as a treatment for children (N=28) with migraine headaches. Children in the treatment condition were significantly improved at the end of treatment and at one-month and six-month follow-up. No improvement was found for the children in the control condition. (BH)

Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

PubMed

Sarabadani, Hamid; Rayhani, Mohammad T

2014-06-01

Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. © The Author(s) 2014.

[Efficiency of autogenous training in medical rehabilitation of patients with irritable colon syndrome with constipation dominance].

PubMed

Pakhomova, I V; Aĭvazian, T A; Zaĭtsev, V P; Gusakova, E V; Molina, L P

2008-01-01

It was established that use of autogenous training makes possible to increase efficiency of the therapy, leading to considerable more evident improvement of somatic and psychotic state, decrease of pain syndrome. Predictors of efficiency of autogenous training were marked out. Indications for use the method in medical rehabilitation of patients with irritable colon syndrome with constipation dominance were elaborated.

Shrinkage deformation of cement foam concrete

NASA Astrophysics Data System (ADS)

Kudyakov, A. I.; Steshenko, A. B.

2015-01-01

The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

Critical stresses for extension of filament-bridged matrix cracks in ceramic-matrix composites: An assessment with a model composite with tailored interfaces

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

Danchaivijit, S.; Shetty, D.K.; Eldridge, J.

Matrix cracking was studied in a model unidirectional composite of SiC filaments in an epoxy-bonded alumina matrix. The residual clamping stress on the filaments due to the shrinkage of the epoxy was moderated with the addition of the alumina filler, and the filament surface was coated with a releasing agent to produce unbonded frictional interfaces. Uniaxial tension specimens with controlled through-cracks with bridging filaments were fabricated by a two-step casting technique. Critical stresses for extension of the filament-bridged cracks of various lengths were measured in uniaxial tension using a high-sensitivity extensometer. The measured crack-length dependence of the critical stress wasmore » in good agreement with the prediction of a stress-intensity analysis that employed a new force-displacement law for the bridging filaments. The analysis required independent experimental evaluation of the matrix fracture toughness, the interfacial sliding friction stress, and the residual tension in the matrix. The matrix-cracking stress for the test specimens without the deliberately introduced cracks was significantly higher than the steady-state cracking stress measured for the long, filament-bridged cracks.« less

A Monte Carlo Evaluation of Estimated Parameters of Five Shrinkage Estimate Formuli.

ERIC Educational Resources Information Center

Newman, Isadore; And Others

1979-01-01

A Monte Carlo simulation was employed to determine the accuracy with which the shrinkage in R squared can be estimated by five different shrinkage formulas. The study dealt with the use of shrinkage formulas for various sample sizes, different R squared values, and different degrees of multicollinearity. (Author/JKS)

Ductility dip cracking susceptibility of Inconel Filler Metal 52 and Inconel Alloy 690

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

Kikel, J.M.; Parker, D.M.

1998-06-01

Alloy 690 and Filler Metal 52 have become the materials of choice for commercial nuclear steam generator applications in recent years. Filler Metal 52 exhibits improved resistance to weld solidification and weld-metal liquation cracking as compared to other nickel-based filler metals. However, recently published work indicates that Filler Metal 52 is susceptible to ductility dip cracking (DDC) in highly restrained applications. Susceptibility to fusion zone DDC was evaluated using the transverse varestraint test method, while heat affected zone (HAZ) DDC susceptibility was evaluated using a newly developed spot-on-spot varestraint test method. Alloy 690 and Filler Metal 52 cracking susceptibility wasmore » compared to the DDC susceptibility of Alloy 600, Filler Metal 52, and Filler Metal 625. In addition, the effect of grain size and orientation on cracking susceptibility was also included in this study. Alloy 690, Filler Metal 82, Filler Metal 52, and Filler Metal 625 were found more susceptible to fusion zone DDC than Alloy 600. Filler Metal 52 and Alloy 690 were found more susceptible to HAZ DDC when compared to wrought Alloy 600, Filler Metal 82 and Filler Metal 625. Filler Metal 52 exhibited the greatest susceptibility to HAZ DDC of all the weld metals evaluated. The base materials were found much more resistant to HAZ DDC in the wrought condition than when autogenously welded. A smaller grain size was found to offer greater resistance to DDC. For weld metal where grain size is difficult to control, a change in grain orientation was found to improve resistance to DDC.« less

[Free from stress by autogenic therapy. Relaxation technique yielding peace of mind and self-insight].

PubMed

Broms, C

1999-02-10

The utilisation of self-regulatory capacity is one of the purposes of autogenic therapy, a method consisting of exercises focused on the limbs, lungs, heart, diaphragm and head. The physiological response is muscle relaxation, increased peripheral blood flow, lower heart rate and blood pressure, slower and deeper breathing, and reduced oxygen consumption. Autogenic training is applicable in most pathological conditions associated with stress, and can be used preventively or as a complement to conventional treatment.

Shrinkage strain-rates of dental resin-monomer and composite systems.

PubMed

Atai, Mohammad; Watts, David C; Atai, Zahra

2005-08-01

The purpose of this study was to investigate the shrinkage strain rate of different monomers, which are commonly used in dental composites and the effect of monomer functionality and molecular mass on the rate. Bis-GMA, TEGDMA, UDMA, MMA, HEMA, HPMA and different ratios of Bis-GMA/TEGDMA were mixed with Camphorquinone and Dimethyl aminoethyle methacrylate as initiator system. The shrinkage strain of the samples photopolymerised at Ca. 550 mW/cm2 and 23 degrees C was measured using the bonded-disk technique of Watts and Cash (Meas. Sci. Technol. 2 (1991) 788-794), and initial shrinkage-strain rates were obtained by numerical differentiation. Shrinkage-strain rates rose rapidly to a maximum, and then fell rapidly upon vitrification. Strain and initial strain rate were dependent upon monomer functionality, molecular mass and viscosity. Strain rates were correlated with Bis-GMA in Bis-GMA/TEGDMA mixtures up to 75-80 w/w%, due to the higher molecular mass of Bis-GMA affecting termination reactions, and then decreased due to its higher viscosity affecting propagation reactions. Monofunctional monomers exhibited lower rates. UDMA, a difunctional monomer of medium viscosity, showed the highest shrinkage strain rate (P < 0.05). Shrinkage strain rate, related to polymerization rate, is an important factor affecting the biomechanics and marginal integrity of composites cured in dental cavities. This study shows how this is related to monomer molecular structure and viscosity. The results are significant for the production, optimization and clinical application of dental composite restoratives.

Modeling dental composite shrinkage by digital image correlation and finite element methods

NASA Astrophysics Data System (ADS)

Chen, Terry Yuan-Fang; Huang, Pin-Sheng; Chuang, Shu-Fen

2014-10-01

Dental composites are light-curable resin-based materials with an inherent defect of polymerization shrinkage which may cause tooth deflection and debonding of restorations. This study aimed to combine digital image correlation (DIC) and finite element analysis (FEA) to model the shrinkage behaviors under different light curing regimens. Extracted human molars were prepared with proximal cavities for composite restorations, and then divided into three groups to receive different light curing protocols: regular intensity, low intensity, and step-curing consisting of low and high intensities. For each tooth, the composite fillings were consecutively placed under both unbonded and bonded conditions. At first, the shrinkage of the unbonded restorations was analyzed by DIC and adopted as the setting of FEA. The simulated shrinkage behaviors obtained from FEA were further validated by the measurements in the bonded cases. The results showed that different light curing regimens affected the shrinkage in unbonded restorations, with regular intensity showing the greatest shrinkage strain on the top surface. The shrinkage centers in the bonded cases were located closer to the cavity floor than those in the unbonded cases, and were less affected by curing regimens. The FEA results showed that the stress was modulated by the accumulated light energy density, while step-curing may alleviate the tensile stress along the cavity walls. In this study, DIC provides a complete description of the polymerization shrinkage behaviors of dental composites, which may facilitate the stress analysis in the numerical investigation.

Effect of biofeedback-assisted autogenic training on headache activity and mood states in Korean female migraine patients.

PubMed

Kang, Eun-Ho; Park, Joo-Eon; Chung, Chin-Sang; Yu, Bum-Hee

2009-10-01

Biofeedback with or without combined autogenic training is known to be effective for the treatment of migraine. This study aimed to examine the effect of biofeedback treatment on headache activity, anxiety, and depression in Korean female patients with migraine headache. Patients were randomized into the treatment group (n=17) and monitoring group (n=15). Mood states including anxiety and depression, and psychophysiological variables such as mean skin temperature of the patients were compared with those of the normal controls (n=21). We found greater treatment response rate (defined as > or =50% reduction in headache index) in patients with biofeedback-assisted autogenic training than in monitoring group. The scores on the anxiety and depression scales in the patients receiving biofeedback-assisted autogenic training decreased after the biofeedback treatment. Moreover, the decrease in their anxiety levels was significantly related to the treatment outcome. This result suggests that the biofeedback-assisted autogenic training is effective for the treatment of migraine and its therapeutic effect is closely related to the improvement of the anxiety level.

Effect of Biofeedback-assisted Autogenic Training on Headache Activity and Mood States in Korean Female Migraine Patients

PubMed Central

Kang, Eun-Ho; Park, Joo-Eon; Chung, Chin-Sang

2009-01-01

Biofeedback with or without combined autogenic training is known to be effective for the treatment of migraine. This study aimed to examine the effect of biofeedback treatment on headache activity, anxiety, and depression in Korean female patients with migraine headache. Patients were randomized into the treatment group (n=17) and monitoring group (n=15). Mood states including anxiety and depression, and psychophysiological variables such as mean skin temperature of the patients were compared with those of the normal controls (n=21). We found greater treatment response rate (defined as ≥50% reduction in headache index) in patients with biofeedback-assisted autogenic training than in monitoring group. The scores on the anxiety and depression scales in the patients receiving biofeedback-assisted autogenic training decreased after the biofeedback treatment. Moreover, the decrease in their anxiety levels was significantly related to the treatment outcome. This result suggests that the biofeedback-assisted autogenic training is effective for the treatment of migraine and its therapeutic effect is closely related to the improvement of the anxiety level. PMID:19794995

[Comparative study of polymerization shrinkage and related properties of flowable composites and an unfilled resin].

PubMed

Bukovinszky, Katalin; Molnár, Lilla; Bakó, József; Szalóki, Melinda; Hegedus, Csaba

2014-03-01

The polymerization shrinkage and shrinkage stress of dental composites are in the center of the interest of researchers and manufacturers. It is a great challenge to minimize this important property as low as possible. Many factors are related and are in complicated correlation with each other affecting the polymerization shrinkage. Polymerization shrinkage stress degree of conversion and elasticity has high importance from this aspect. Our aim was to study the polymerization shrinkage and related properties (modulus of elasticity, degree of conversion, shrinkage stress) of three flowable composite (Charisma Opal Flow, SDR, Filtek Ultimate) and an unfilled composite resin. Modulus of elasticity was measured using three point flexure tests on universal testing machine. The polymerization shrinkage stress was determined using bonded-disc technique. The degree of conversion measurements were performed by FT-IR spectroscopy. And the volumetric shrinkage was investigated using Archimedes principle and was measured on analytical balance with special additional equipment. The unfilled resin generally showed higher shrinkage (8,26%), shrinkage stress (0,8 MPa) and degree of conversion (38%), and presented the lowest modulus of elasticity (3047,02MPa). Highest values of unfilled resin correspond to the literature. The lack of fillers enlarges the shrinkage, and the shrinkage stress, but gives the higher flexibility and higher degree of conversion. Further investigations needs to be done to understand and reveal the differences between the composites.

One Session of Autogenic Training Increases Acute Subjective Sexual Arousal in Premenopausal Women Reporting Sexual Arousal Problems.

PubMed

Stanton, Amelia M; Hixon, J Gregory; Nichols, Lindsey M; Meston, Cindy M

2018-01-01

Below average heart rate variability (HRV) has been associated with sexual arousal dysfunction and overall sexual dysfunction in women. Autogenic training, a psychophysiologic relaxation technique, has been shown to increase HRV. In a recent study, sexually healthy women experienced acute increases in physiologic (ie, genital) and subjective sexual arousal after 1 brief session of autogenic training. To build on these findings by testing the effects of a single session of autogenic training on sexual arousal in a sample of women who reported decreased or absent sexual arousal for at least 6 months. Genital sexual arousal, subjective sexual arousal, and perceived genital sensations were assessed in 25 women 20 to 44 years old before and after listening to a 22-minute autogenic training recording. HRV was assessed with electrocardiography. Change in genital sexual arousal, subjective sexual arousal, and perceived genital sensations from the pre-manipulation erotic film to the post-manipulation erotic film. Marginally significant increases in discrete subjective sexual arousal (P = .051) and significant increases in perceived genital sensations (P = .018) were observed. In addition, degree of change in HRV significantly moderated increases in subjective arousal measured continuously over time (P < .0001). There were no significant increases in genital arousal after the manipulation. The results of this study suggest that autogenic training, and other interventions that aim to increase HRV, could be a useful addition to treatment protocols for women who are reporting a lack of subjective arousal or decreased genital sensations. There are few treatment options for women with arousal problems. We report on a new psychosocial intervention that could improve arousal. Limitations include a relatively small sample and the lack of a control group. Our findings indicate that autogenic training significantly improves acute subjective arousal and increases perceived genital

Shrinkage Stresses Generated during Resin-Composite Applications: A Review

PubMed Central

Schneider, Luis Felipe J.; Cavalcante, Larissa Maria; Silikas, Nick

2010-01-01

Many developments have been made in the field of resin composites for dental applications. However, the manifestation of shrinkage due to the polymerization process continues to be a major problem. The material's shrinkage, associated with dynamic development of elastic modulus, creates stresses within the material and its interface with the tooth structure. As a consequence, marginal failure and subsequent secondary caries, marginal staining, restoration displacement, tooth fracture, and/or post-operative sensitivity are clinical drawbacks of resin-composite applications. The aim of the current paper is to present an overview about the shrinkage stresses created during resin-composite applications, consequences, and advances. The paper is based on results of many researches that are available in the literature. PMID:20948573

Effect of low-shrinkage monomers on the physicochemical properties of experimental composite resin

PubMed Central

He, Jingwei; Garoushi, Sufyan; Vallittu, Pekka K.; Lassila, Lippo

2018-01-01

Abstract This study was conducted to determine whether novel experimental low-shrinkage dimethacrylate co-monomers could provide low polymerization shrinkage composites without sacrifice to degree of conversion, and mechanical properties of the composites. Experimental composites were prepared by mixing 28.6 wt% of bisphenol-A-glycidyl dimethacrylate based resin matrix (bis-GMA) with various weight-fractions of co-monomers; tricyclo decanedimethanol dacrylate (SR833s) and isobornyl acrylate (IBOA) to 71.4 wt% of particulate-fillers. A composite based on bis-GMA/TEGDMA (triethylene glycol dimethacrylate) was used as a control. Fracture toughness and flexural strength were determined for each experimental material following international standards. Degree of monomer-conversion (DC%) was determined by FTIR spectrometry. The volumetric shrinkage in percent was calculated as a buoyancy change in distilled water by means of the Archimedes’ principle. Polymerization shrinkage-strain and -stress of the specimens were measured using the strain-gage technique and tensilometer, respectively with respect to time. Statistical analysis revealed that control group had the highest double-bond conversion (p < .05) among the experimental resins tested. All of the experimental composite resins had comparable flexural strength, modulus, and fracture toughness (p > .05). Volumetric shrinkage and shrinkage stress decreased with increasing IBOA concentration. Replacing TEGDMA with SR833s and IBOA can decrease the volumetric shrinkage, shrinkage strain, and shrinkage stress of composite resins without affecting the mechanical properties. However, the degree of conversion was also decreased. PMID:29536025

Effect of low-shrinkage monomers on the physicochemical properties of experimental composite resin.

PubMed

He, Jingwei; Garoushi, Sufyan; Vallittu, Pekka K; Lassila, Lippo

2018-01-01

This study was conducted to determine whether novel experimental low-shrinkage dimethacrylate co-monomers could provide low polymerization shrinkage composites without sacrifice to degree of conversion, and mechanical properties of the composites. Experimental composites were prepared by mixing 28.6 wt% of bisphenol-A-glycidyl dimethacrylate based resin matrix ( bis -GMA) with various weight-fractions of co-monomers; tricyclo decanedimethanol dacrylate (SR833s) and isobornyl acrylate (IBOA) to 71.4 wt% of particulate-fillers. A composite based on bis -GMA/TEGDMA (triethylene glycol dimethacrylate) was used as a control. Fracture toughness and flexural strength were determined for each experimental material following international standards. Degree of monomer-conversion (DC%) was determined by FTIR spectrometry. The volumetric shrinkage in percent was calculated as a buoyancy change in distilled water by means of the Archimedes' principle. Polymerization shrinkage-strain and -stress of the specimens were measured using the strain-gage technique and tensilometer, respectively with respect to time. Statistical analysis revealed that control group had the highest double-bond conversion ( p  < .05) among the experimental resins tested. All of the experimental composite resins had comparable flexural strength, modulus, and fracture toughness ( p  > .05). Volumetric shrinkage and shrinkage stress decreased with increasing IBOA concentration. Replacing TEGDMA with SR833s and IBOA can decrease the volumetric shrinkage, shrinkage strain, and shrinkage stress of composite resins without affecting the mechanical properties. However, the degree of conversion was also decreased.

A Monte Carlo Evaluation of Estimated Parameters of Five Shrinkage Estimate Formuli.

ERIC Educational Resources Information Center

Newman, Isadore; And Others

A Monte Carlo study was conducted to estimate the efficiency of and the relationship between five equations and the use of cross validation as methods for estimating shrinkage in multiple correlations. Two of the methods were intended to estimate shrinkage to population values and the other methods were intended to estimate shrinkage from sample…

Healing of rabbit calvarial critical-sized defects using autogenous bone grafts and fibrin glue.

PubMed

Lappalainen, Olli-Pekka; Korpi, Riikka; Haapea, Marianne; Korpi, Jarkko; Ylikontiola, Leena P; Kallio-Pulkkinen, Soili; Serlo, Willy S; Lehenkari, Petri; Sándor, George K

2015-04-01

This study aimed to evaluate ossification of cranial bone defects comparing the healing of a single piece of autogenous calvarial bone representing a bone flap as in cranioplasty compared to particulated bone slurry with and without fibrin glue to represent bone collected during cranioplasty. These defect-filling materials were then compared to empty control cranial defects. Ten White New Zealand adult male rabbits had bilateral critical-sized calvarial defects which were left either unfilled as control defects or filled with a single full-thickness piece of autogenous bone, particulated bone, or particulated bone combined with fibrin glue. The defects were left to heal for 6 weeks postoperatively before termination. CT scans of the calvarial specimens were performed. Histomorphometric assessment of hematoxylin-eosin- and Masson trichrome-stained specimens was used to analyze the proportion of new bone and fibrous tissue in the calvarial defects. There was a statistically significant difference in both bone and soft tissue present in all the autogenous bone-grafted defect sites compared to the empty negative control defects. These findings were supported by CT scan findings. While fibrin glue combined with the particulated bone seemed to delay ossification, the healing was more complete compared to empty control non-grafted defects. Autogenous bone grafts in various forms such as solid bone flaps or particulated bone treated with fibrin glue were associated with bone healing which was superior to the empty control defects.

Self-reinnervated muscles lose autogenic length feedback, but intermuscular feedback can recover functional connectivity

PubMed Central

Prilutsky, Boris I.; Gregor, Robert J.; Abelew, Thomas A.; Nichols, T. Richard

2016-01-01

In this study, we sought to identify sensory circuitry responsible for motor deficits or compensatory adaptations after peripheral nerve cut and repair. Self-reinnervation of the ankle extensor muscles abolishes the stretch reflex and increases ankle yielding during downslope walking, but it remains unknown whether this finding generalizes to other muscle groups and whether muscles become completely deafferented. In decerebrate cats at least 19 wk after nerve cut and repair, we examined the influence of quadriceps (Q) muscles' self-reinnervation on autogenic length feedback, as well as intermuscular length and force feedback, among the primary extensor muscles in the cat hindlimb. Effects of gastrocnemius and soleus self-reinnervation on intermuscular circuitry were also evaluated. We found that autogenic length feedback was lost after Q self-reinnervation, indicating that loss of the stretch reflex appears to be a generalizable consequence of muscle self-reinnervation. However, intermuscular force and length feedback, evoked from self-reinnervated muscles, was preserved in most of the interactions evaluated with similar relative inhibitory or excitatory magnitudes. These data indicate that intermuscular spinal reflex circuitry has the ability to regain functional connectivity, but the restoration is not absolute. Explanations for the recovery of intermuscular feedback are discussed, based on identified mechanisms responsible for lost autogenic length feedback. Functional implications, due to permanent loss of autogenic length feedback and potential for compensatory adaptations from preserved intermuscular feedback, are discussed. PMID:27306676

Leaf shrinkage with dehydration: coordination with hydraulic vulnerability and drought tolerance.

PubMed

Scoffoni, Christine; Vuong, Christine; Diep, Steven; Cochard, Hervé; Sack, Lawren

2014-04-01

Leaf shrinkage with dehydration has attracted attention for over 100 years, especially as it becomes visibly extreme during drought. However, little has been known of its correlation with physiology. Computer simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll pathways outside the xylem would cause a strong decline of leaf hydraulic conductance (K(leaf)). For 14 diverse species, we tested the hypothesis that shrinkage during dehydration (i.e. in whole leaf, cell and airspace thickness, and leaf area) is associated with reduction in K(leaf) at declining leaf water potential (Ψ(leaf)). We tested hypotheses for the linkage of leaf shrinkage with structural and physiological water relations parameters, including modulus of elasticity, osmotic pressure at full turgor, turgor loss point (TLP), and cuticular conductance. Species originating from moist habitats showed substantial shrinkage during dehydration before reaching TLP, in contrast with species originating from dry habitats. Across species, the decline of K(leaf) with mild dehydration (i.e. the initial slope of the K(leaf) versus Ψ(leaf) curve) correlated with the decline of leaf thickness (the slope of the leaf thickness versus Ψ(leaf) curve), as expected based on predictions from computer simulations. Leaf thickness shrinkage before TLP correlated across species with lower modulus of elasticity and with less negative osmotic pressure at full turgor, as did leaf area shrinkage between full turgor and oven desiccation. These findings point to a role for leaf shrinkage in hydraulic decline during mild dehydration, with potential impacts on drought adaptation for cells and leaves, influencing plant ecological distributions.

Forced expiratory technique, directed cough, and autogenic drainage.

PubMed

Fink, James B

2007-09-01

In health, secretions produced in the respiratory tract are cleared by mucociliary transport, cephalad airflow bias, and cough. In disease, increased secretion viscosity and volume, dyskinesia of the cilia, and ineffective cough combine to reduce secretion clearance, leading to increased risk of infection. In obstructive lung disease these conditions are further complicated by early collapse of airways, due to airway compression, which traps both gas and secretions. Techniques have been developed to optimize expiratory flow and promote airway clearance. Directed cough, forced expiratory technique, active cycle of breathing, and autogenic drainage are all more effective than placebo and comparable in therapeutic effects to postural drainage; they require no special equipment or care-provider assistance for routine use. Researchers have suggested that standard chest physical therapy with active cycle of breathing and forced expiratory technique is more effective than chest physical therapy alone. Evidence-based reviews have suggested that, though successful adoption of techniques such as autogenic drainage may require greater control and training, patients with long-term secretion management problems should be taught as many of these techniques as they can master for adoption in their therapeutic routines.

Shrinkage and footage loss from drying 4/4-inch hard maple lumber.

Treesearch

Daniel E. Dunmire

1968-01-01

Equations are presented for estimating shrinkage and resulting footage losses due to drying hard maple lumber. The equations, based on board shrinkage data taken from a representative lumber sample, are chiefly intended for use with lots of hard maple lumber, such as carloads, truckloads, or kiln loads, but also can be used for estimating the average shrinkage of...

Liquid nitrogen-treated autogenous dentin as bone substitute: an experimental study in a rabbit model.

PubMed

Atiya, Basim K; Shanmuhasuntharam, Palasuntharam; Huat, Siar; Abdulrazzak, Shurooq; Oon, Ha

2014-01-01

Different forms of dentin, including untreated, undemineralized, demineralized, boiled, or mixed with other materials, have been evaluated for efficacy as bone substitutes. However, the effects of application of liquid nitrogen-treated dentin for bone grafting remain unknown. The objective of this study was to chronologically evaluate bone healing following grafting with liquid nitrogen-treated dentin in a rabbit model. Autogenous dentin treated with liquid nitrogen at -196°C for 20 minutes was used. In 16 New Zealand White rabbits, a bone defect (5 mm in diameter) was created in each femur and randomly grafted with either autogenous dentin (experimental group) or autogenous bone grafts (positive control). In another four rabbits (negative control), a similar defect in each femur was left empty. The rabbits were sacrificed at 2, 4, 8, and 12 weeks. Explants of grafted sites were harvested for histologic and histomorphometric analysis. At 2 and 4 weeks in both the experimental and positive control groups, accelerated formation of new bone was observed, which was undergoing remodeling at 8 and 12 weeks. The mean new bone score was higher in the experimental than in the negative control groups, but this was not statistically significant. The present results demonstrated that liquid nitrogen-treated autogenous dentin has both osteoconductive and osteoinductive properties and therefore has potential as a bone substitute.

Analysis of the status of pre-release cracks in prestressed concrete structures using long-gauge sensors

NASA Astrophysics Data System (ADS)

Abdel-Jaber, H.; Glisic, B.

2015-02-01

Prestressed structures experience limited tensile stresses in concrete, which limits or completely eliminates the occurrence of cracks. However, in some cases, large tensile stresses can develop during the early age of the concrete due to thermal gradients and shrinkage effects. Such stresses can cause early-age cracks, termed ‘pre-release cracks’, which occur prior to the transfer of the prestressing force. When the prestressing force is applied to the cross-section, it is assumed that partial or full closure of the cracks occurs by virtue of the force transfer through the cracked cross-section. Verification of the closure of the cracks after the application of the prestressing force is important as it can either confirm continued structural integrity or indicate and approximate reduced structural capacity. Structural health monitoring (SHM) can be used for this purpose. This paper researches an SHM method that can be applied to prestressed beam structures to assess the condition of pre-release cracks. The sensor network used in this method consists of parallel long-gauge fiber optic strain sensors embedded in the concrete cross-sections at various locations. The same network is used for damage detection, i.e. detection and characterization of the pre-release cracks, and for monitoring the prestress force transfer. The method is validated on a real structure, a curved continuous girder. Results from the analysis confirm the safety and integrity of the structure. The method and its application are presented in this paper.

[Predictors of efficiency of autogenous melodeclamation training in patients with chronic somatic pathology].

PubMed

Trdatian, N A

2009-01-01

This controlled study involving 99 patients with chronic somatic diseases (CSD) had the objective to identify psychological predictors of the efficiency of a new method of psychotherapy, namely autogenous melodeclamation training (AMDT). Dynamics of the psychological status of the patients in the course of therapy was assessed using SMOL test, Spilberger STAI test, overall health-physical activity-mood test, and Beck depression inventory. It was shown that moderately compromised psychological adaptation and minor depressive disorders were the most reliable predictors of marked improvement of the patients' psychological status under effect of autogenous melodeclamation training included in the combined rehabilitative therapy of chronic somatic diseases.

Evaluation of Autogenous Engineered Septal Cartilage Grafts in Rabbits- A Minimally Invasive Preclinical Model.

PubMed

Kushnaryov, Anton; Yamaguchi, Tomonoro; Briggs, Kristen K; Wong, Van W; Reuther, Marsha; Neuman, Monica; Lin, Victor; Sah, Robert L; Masuda, Koichi; Watson, Deborah

2014-07-23

Evaluate safety of autogenous engineered septal neocartilage grafts.Compare properties of implanted grafts versus in vitro controls. Prospective, basic science. Research laboratory. Constructs were fabricated from septal cartilage and serum harvested from adult rabbits and then cultured in vitro or implanted on the nasal dorsum as autogenous grafts for 30 or 60 days. Rabbits were monitored for local and systemic complications. Histological, biochemical and biomechanical properties of implanted and in vitro constructs were evaluated and compared. No systemic or serious local complications were observed. After 30 and 60 days, implanted constructs contained more DNA (p<0.01) and less sGAG per DNA (p<0.05) when compared with in vitro controls. Confined compressive aggregate moduli were also higher in implanted constructs when compared with in vitro controls (p<0.05) and increased with longer in vivo incubation time (p<0.01). Implanted constructs displayed resorption rates of 20-45 percent. Calcium deposition in implanted constructs was observed using alizarin red histochemistry and microtomographic analyses. Autogenous engineered septal cartilage grafts were well tolerated. As seen in experiments with athymic mice, implanted constructs accumulated more DNA and less sGAG when compared with in vitro controls. Confined compressive aggregate moduli were also higher in implanted constructs. Implanted constructs displayed resorption rates similar to previously published studies using autogenous implants of native cartilage. The basis for observed calcification in implanted constructs and its effect on long-term graft efficacy is unknown at this time and will be a focus of future studies.

Durability of conventional concretes containing black rice husk ash.

PubMed

Chatveera, B; Lertwattanaruk, P

2011-01-01

In this study, black rice husk ash (BRHA) from a rice mill in Thailand was ground and used as a partial cement replacement. The durability of conventional concretes with high water-binder ratios was investigated including drying shrinkage, autogenous shrinkage, depth of carbonation, and weight loss of concretes exposed to hydrochloric (HCl) and sulfuric (H(2)SO(4)) acid attacks. Two different replacement percentages of cement by BRHA, 20% and 40%, and three different water-binder ratios (0.6, 0.7 and 0.8) were used. The ratios of paste volume to void content of the compacted aggregate (γ) were 1.2, 1.4, and 1.6. As a result, when increasing the percentage replacement of BRHA, the drying shrinkage and depth of carbonation reaction of concretes increased. However, the BRHA provides a positive effect on the autogenous shrinkage and weight loss of concretes exposed to hydrochloric and sulfuric acid attacks. In addition, the resistance to acid attack was directly varied with the (SiO(2) + Al(2)O(3) + Fe(2)O(3))/CaO ratio. Results show that ground BRHA can be applied as a pozzolanic material and also improve the durability of concrete. Copyright © 2010 Elsevier Ltd. All rights reserved.

Non-Ionotropic NMDA Receptor Signaling Drives Activity-Induced Dendritic Spine Shrinkage.

PubMed

Stein, Ivar S; Gray, John A; Zito, Karen

2015-09-02

The elimination of dendritic spine synapses is a critical step in the refinement of neuronal circuits during development of the cerebral cortex. Several studies have shown that activity-induced shrinkage and retraction of dendritic spines depend on activation of the NMDA-type glutamate receptor (NMDAR), which leads to influx of extracellular calcium ions and activation of calcium-dependent phosphatases that modify regulators of the spine cytoskeleton, suggesting that influx of extracellular calcium ions drives spine shrinkage. Intriguingly, a recent report revealed a novel non-ionotropic function of the NMDAR in the regulation of synaptic strength, which relies on glutamate binding but is independent of ion flux through the receptor (Nabavi et al., 2013). Here, we tested whether non-ionotropic NMDAR signaling could also play a role in driving structural plasticity of dendritic spines. Using two-photon glutamate uncaging and time-lapse imaging of rat hippocampal CA1 neurons, we show that low-frequency glutamatergic stimulation results in shrinkage of dendritic spines even in the presence of the NMDAR d-serine/glycine binding site antagonist 7-chlorokynurenic acid (7CK), which fully blocks NMDAR-mediated currents and Ca(2+) transients. Notably, application of 7CK or MK-801 also converts spine enlargement resulting from a high-frequency uncaging stimulus into spine shrinkage, demonstrating that strong Ca(2+) influx through the NMDAR normally overcomes a non-ionotropic shrinkage signal to drive spine growth. Our results support a model in which NMDAR signaling, independent of ion flux, drives structural shrinkage at spiny synapses. Dendritic spine elimination is vital for the refinement of neural circuits during development and has been linked to improvements in behavioral performance in the adult. Spine shrinkage and elimination have been widely accepted to depend on Ca(2+) influx through NMDA-type glutamate receptors (NMDARs) in conjunction with long-term depression

Time dependence of composite shrinkage using halogen and LED light curing.

PubMed

Uhl, Alexander; Mills, Robin W; Rzanny, Angelika E; Jandt, Klaus D

2005-03-01

The polymerization shrinkage of light cured dental composites presents the major drawback for these aesthetically adaptable restorative materials. LED based light curing technology has recently become commercially available. Therefore, the aim of the present study was to investigate if there was a statistically significant difference in linear and volumetric composite shrinkage strain if a LED LCU is used for the light curing process rather than a conventional halogen LCU. The volumetric shrinkage strain was determined using the Archimedes buoyancy principle after 5, 10, 20, 40 s of light curing and after 120 s following the 40 s light curing time period. The linear shrinkage strain was determined with a dynamic mechanical analyzer for the composites Z100, Spectrum, Solitaire2 and Definite polymerized with the LCUs Trilight (halogen), Freelight I (LED) and LED63 (LED LCU prototype). The changes in irradiance and spectra of the LCUs were measured after 0, 312 and 360 min of duty time. In general there was no considerable difference in shrinkage of the composites Z100, Spectrum or Solitaire2 when the LED63 was used instead of the Trilight. There was, however, a statistically significant difference in shrinkage strain when the composite Definite was polymerized with the LED63 instead of the Trilight. The spectrum of the Trilight changed during the experiment considerably whereas the LED63 showed an almost constant light output. The Freelight I dropped considerably in irradiance and had to be withdrawn from the study because of technical problems. The composites containing only the photoinitiator camphorquinone showed similar shrinkage strain behaviour when a LED or halogen LCU is used for the polymerization. The irradiance of some LED LCUs can also decrease over time and should therefore be checked on a regular basis.

Drying Shrinkage of Mortar Incorporating High Volume Oil Palm Biomass Waste

NASA Astrophysics Data System (ADS)

Shukor Lim, Nor Hasanah Abdul; Samadi, Mostafa; Rahman Mohd. Sam, Abdul; Khalid, Nur Hafizah Abd; Nabilah Sarbini, Noor; Farhayu Ariffin, Nur; Warid Hussin, Mohd; Ismail, Mohammed A.

2018-03-01

This paper studies the drying shrinkage of mortar incorporating oil palm biomass waste including Palm Oil Fuel Ash, Oil Palm Kernel Shell and Oil Palm Fibre. Nano size of palm oil fuel ash was used up to 80 % as cement replacement by weight. The ash has been treated to improve the physical and chemical properties of mortar. The mass ratio of sand to blended ashes was 3:1. The test was carried out using 25 × 25 × 160 mm prism for drying shrinkage tests and 70 × 70 ×70 mm for compressive strength test. The results show that the shrinkage value of biomass mortar is reduced by 31% compared with OPC mortar thus, showing better performance in restraining deformation of the mortar while the compressive strength increased by 24% compared with OPC mortar at later age. The study gives a better understanding of how the biomass waste affect on mortar compressive strength and drying shrinkage behaviour. Overall, the oil palm biomass waste can be used to produce a better performance mortar at later age in terms of compressive strength and drying shrinkage.

[Effect of hypnosis and autogenic training on acral circulation and coping with the illness in patients with progressive scleroderma].

PubMed

Seikowski, K; Weber, B; Haustein, U F

1995-02-01

In 12 patients with systemic sclerosis the influence of hypnosis and autogenic training on the acral blood circulation and the coping with the disease was investigated in a pilot study. In the first step significant increases in the skin temperature of the finger (mean +/- SD: 3.9 +/- 1.2 degrees C) could be found after relaxation hypnosis. In the second step six patients (study group) gained experience with autogenic training. The other six patients served as control group. In the study group, the skin temperature of the fingers (short-term effect) was significantly higher than in the control group (1.9 +/- 1.0 degrees C). Long-term effects of the autogenic training (mean acral rewarning time, duration and course of the Raynaud attacks, acral lesions of the hands, psychosomatic status of complaints, type of relation to the disease as precondition for coping with the disease) were not found within the relatively short follow-up period of 4 months. Two patients, however, reported that they could shorten the duration of Raynaud attacks by autogenic training. In our patients heterogenicity and an increased score of multiple psychosomatic complaints were registered at the outset. As far as the type of relation to the disease is concerned, the patients could be assessed as almost adapted. Hypnosis and autogenic training can be recommended as complementary therapy in systemic sclerosis.

Synthesis and photopolymerization of low shrinkage methacrylate monomers containing bulky substituent groups.

PubMed

Ge, Junhao; Trujillo, Marianela; Stansbury, Jeffrey

2005-12-01

This study was conducted to determine whether novel photopolymerizable formulations based on dimethacrylate monomers with bulky substituent groups could provide low polymerization shrinkage without sacrifice to degree of conversion, and mechanical properties of the polymers. Relatively high molecular weight dimethacrylate monomers were prepared from rigid bisphenol A core groups. Photopolymerization kinetics and shrinkage as well as flexural strength and glass transition temperatures were evaluated for various comonomer compositions. Copolymerization of the bulky monomers with TEGDMA show higher conversion but similar shrinkage compared with Bis-GMA/TEGDMA controls. The resulting polymers have suitable mechanical strength properties for potential dental restorative materials applications. When copolymerized with PEGDMA, the bulky monomers show lower shrinkage, comparable conversion, and more homogeneous polymeric network structures compared with Bis-EMA/PEGDMA systems. The novel dimethacrylate monomers with reduced reactive group densities can decrease the polymerization shrinkage as anticipated, but there is no significant evidence that the bulky substituent groups have any additional effect on reducing shrinkage based on the physical interactions as polymer side chains. The bulky groups improve the double bond conversion and help maintain the mechanical properties of the resulting polymer, which would otherwise decrease rapidly due to the reduced crosslinking density. Further, it was found that bulky monomers help produce more homogeneous copolymer networks.

Thermo-Oxidative Induced Damage in Polymer Composites: Microstructure Image-Based Multi-Scale Modeling and Experimental Validation

NASA Astrophysics Data System (ADS)

Hussein, Rafid M.; Chandrashekhara, K.

2017-11-01

A multi-scale modeling approach is presented to simulate and validate thermo-oxidation shrinkage and cracking damage of a high temperature polymer composite. The multi-scale approach investigates coupled transient diffusion-reaction and static structural at macro- to micro-scale. The micro-scale shrinkage deformation and cracking damage are simulated and validated using 2D and 3D simulations. Localized shrinkage displacement boundary conditions for the micro-scale simulations are determined from the respective meso- and macro-scale simulations, conducted for a cross-ply laminate. The meso-scale geometrical domain and the micro-scale geometry and mesh are developed using the object oriented finite element (OOF). The macro-scale shrinkage and weight loss are measured using unidirectional coupons and used to build the macro-shrinkage model. The cross-ply coupons are used to validate the macro-shrinkage model by the shrinkage profiles acquired using scanning electron images at the cracked surface. The macro-shrinkage model deformation shows a discrepancy when the micro-scale image-based cracking is computed. The local maximum shrinkage strain is assumed to be 13 times the maximum macro-shrinkage strain of 2.5 × 10-5, upon which the discrepancy is minimized. The microcrack damage of the composite is modeled using a static elastic analysis with extended finite element and cohesive surfaces by considering the modulus spatial evolution. The 3D shrinkage displacements are fed to the model using node-wise boundary/domain conditions of the respective oxidized region. Microcrack simulation results: length, meander, and opening are closely matched to the crack in the area of interest for the scanning electron images.

A Single Session of Autogenic Training Increases Acute Subjective and Physiological Sexual Arousal in Sexually Functional Women.

PubMed

Stanton, Amelia; Meston, Cindy

2017-10-03

Heart rate variability (HRV) has recently been associated with female sexual function (Stanton, Lorenz, Pulverman, & Meston, 2015). Below-average HRV was identified as a possible risk factor for sexual arousal dysfunction and overall sexual dysfunction in women. Based on this newly established relationship between HRV and female sexual function, the present study examined the effect of autogenic training to increase HRV on acute physiological and subjective sexual arousal in women. Specifically, vaginal pulse amplitude (VPA), an index of genital sexual arousal, and subjective sexual arousal were assessed in 33 sexually functional women, aged 18 to 27, before and after a short session of autogenic training. Autogenic training, a relaxation technique that restores the balance between the activity of the sympathetic and the parasympathetic branches of the autonomic nervous system, has been shown to significantly increase HRV (Miu, Heilman, & Miclea, 2009). After autogenic training, significant increases in both VPA (p <.05) and subjective sexual arousal (p <.005) were observed. Moreover, change in HRV from pre- to postmanipulation significantly moderated changes in subjective sexual arousal (p <.05) when it was measured continuously during the presentation of the erotic stimulus. This cost-effective, easy-to-administer behavioral intervention may have important implications for increasing sexual arousal in women.

Hardness, density, and shrinkage characteristics of silk-oak from Hawaii

Treesearch

R. L. Youngs

1964-01-01

Shrinkage, specific gravity, and hardness of two shipments of silk-oak (Grevillea robusta) from Hawaii were evaluated to provide basic information pertinent to the use of the wood for cabinet and furniture purposes. The wood resembles Hawaii-grown shamel ash (Fraxinus uhdei ) in the properties evaluated. Shrinkage compares well with that of black cherry, silver maple,...

Effect of autogenic relaxation on depression among menopausal women in rural areas of Thiruvallur District (Tamil Nadu).

PubMed

Sujithra, S

2014-01-01

An experimental study was conducted among 60 menopausal women, 30 each in experimental and control group who met inclusion criteria. The menopausal women were identified in both the groups and level of depression was assessed using Cornell Dysthmia rating scale. Simple random sampling technique by lottery method was used for selecting the sample. Autogenic relaxation was practiced by the menopausal women for four weeks. The findings revealed that in experimental group, after intervention of autogenic relaxation on depression among menopausal women, 23 (76.7%) had mild depression. There was a statistically significant effectiveness in experimental group at the level of p < 0.05. There was a statistically significant association between the effectiveness of autogenic relaxation on depression among menopausal women in the post-experimental group with the type of family at the level of p < 0.05.

Sustainable exploitation and management of autogenic ecosystem engineers: application to oysters in Chesapeake Bay.

PubMed

Wilberg, Michael J; Wiedenmann, John R; Robinson, Jason M

2013-06-01

Autogenic ecosystem engineers are critically important parts of many marine and estuarine systems because of their substantial effect on ecosystem services. Oysters are of particular importance because of their capacity to modify coastal and estuarine habitats and the highly degraded status of their habitats worldwide. However, models to predict dynamics of ecosystem engineers have not previously included the effects of exploitation. We developed a linked population and habitat model for autogenic ecosystem engineers undergoing exploitation. We parameterized the model to represent eastern oyster (Crassostrea virginica) in upper Chesapeake Bay by selecting sets of parameter values that matched observed rates of change in abundance and habitat. We used the model to evaluate the effects of a range of management and restoration options including sustainability of historical fishing pressure, effectiveness of a newly enacted sanctuary program, and relative performance of two restoration approaches. In general, autogenic ecosystem engineers are expected to be substantially less resilient to fishing than an equivalent species that does not rely on itself for habitat. Historical fishing mortality rates in upper Chesapeake Bay for oysters were above the levels that would lead to extirpation. Reductions in fishing or closure of the fishery were projected to lead to long-term increases in abundance and habitat. For fisheries to become sustainable outside of sanctuaries, a substantial larval subsidy would be required from oysters within sanctuaries. Restoration efforts using high-relief reefs were predicted to allow recovery within a shorter period of time than low-relief reefs. Models such as ours, that allow for feedbacks between population and habitat dynamics, can be effective tools for guiding management and restoration of autogenic ecosystem engineers.

Post-veraison irreversible stem shrinkage in grapevine (Vitis vinifera) is caused by periderm formation.

PubMed

Van de Wal, Bart A E; Leroux, Olivier; Steppe, Kathy

2018-05-01

Grapevines are characterized by a period of irreversible stem shrinkage around the onset of ripening of the grape berries. Since this shrinkage is unrelated to meteorological conditions or drought, it is often suggested that it is caused by the increased sink strength of the grape berries during this period. However, no studies so far have experimentally investigated the mechanisms underlying this irreversible stem shrinkage. We therefore combined continuous measurements of stem diameter variations and histology of potted 2-year-old grapevines (Vitis vinifera L. 'Boskoop Glory'). Sink strength was altered by pruning all grape clusters (treatment P), while non-pruned grapevines served as control (treatment C). Unexpectedly, our results showed irreversible post-veraison stem shrinkage in both treatments, suggesting that the shrinkage is not linked to grape berry sink strength. Anatomical analysis indicated that the shrinkage is the result of the formation of successive concentric periderm layers, and the subsequent dehydration and compression of the older bark tissues, an anatomical feature that is characteristic of Vitis stems. Stem shrinkage is hence unrelated to grape berry development, in contrast to what has been previously suggested.

An Experimental Study on Shrinkage Strains of Normal-and High-Strength Concrete-Filled Frp Tubes

NASA Astrophysics Data System (ADS)

Vincent, Thomas; Ozbakkaloglu, Togay

2017-09-01

It is now well established that concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs) are an attractive construction technique for new columns, however studies examining concrete shrinkage in CFFTs remain limited. Concrete shrinkage may pose a concern for CFFTs, as in these members the curing of concrete takes place inside the FRP tube. This paper reports the findings from an experimental study on concrete shrinkage strain measurements for CFFTs manufactured with normal- and high-strength concrete (NSC and HSC). A total of 6 aramid FRP (AFRP)-confined concrete specimens with circular cross-sections were manufactured, with 3 specimens each manufactured using NSC and HSC. The specimens were instrumented with surface and embedded strain gauges to monitor shrinkage development of exposed concrete and concrete sealed inside the CFFTs, respectively. All specimens were cylinders with a 152 mm diameter and 305 mm height, and their unconfined concrete strengths were 44.8 or 83.2 MPa. Analysis of the shrinkage measurements from concrete sealed inside the CFFTs revealed that embedment depth and concrete compressive strength only had minor influences on recorded shrinkage strains. However, an analysis of shrinkage measurements from the exposed concrete surface revealed that higher amounts of shrinkage can occur in HSC. Finally, it was observed that shrinkage strains are significantly higher for concrete exposed at the surface compared to concrete sealed inside the CFFTs.

Effect of autogenic training on drug consumption in patients with primary headache: an 8-month follow-up study.

PubMed

Zsombok, Terezia; Juhasz, Gabriella; Budavari, Agota; Vitrai, Jozsef; Bagdy, Gyorgy

2003-03-01

To examine the effects of Schultz-type autogenic training on headache-related drug consumption and headache frequency in patients with migraine, tension-type, or mixed (migraine plus tension-type) headache over an 8-month period. Behavioral treatments often are used alone or adjunctively for different types of headache. There are, however, only a few studies that have compared the efficacy and durability of the same treatment in different types of primary headache, and the effects of treatment on headache-related drug consumption rarely have been assessed even in these studies. Twenty-five women with primary headache (11 with mixed headache, 8 with migraine, and 6 with tension-type headache) were evaluated via an open-label, self-controlled, 8-month, follow-up study design. After an initial 4 months of observation, patients began learning Schultz-type autogenic training as modified for patients with headache. They practiced autogenic training on a regular basis for 4 months. Based on data from headache diaries and daily medication records, headache frequencies and the amounts of analgesics, "migraine-specific" drugs (ergots and triptans), and anxiolytics taken by the patients were compared in the three subgroups over the 8-month period. Results.-From the first month of implementation of autogenic training, headache frequencies were significantly reduced in patients with tension-type and mixed headache. Significant reduction in frequency was achieved in patients with migraine only from the third month of autogenic training. Decreases in headache frequencies were accompanied by decreases in consumption of migraine drugs and analgesics resulting in significant correlations among these parameters. Reduction in consumption of anxiolytic drugs was more rapid and robust in patients with tension-type headache compared to patients with migraine, and this outcome failed to show any correlation with change in headache frequency. Schultz-type autogenic training is an effective

Limitation of Shrinkage Porosity in Aluminum Rotor Die Casting

NASA Astrophysics Data System (ADS)

Kim, Young-Chan; Choi, Se-Weon; Kim, Cheol-Woo; Cho, Jae-Ik; Lee, Sung-Ho; Kang, Chang-Seog

Aluminum rotor prone to have many casting defects especially large amount of air and shrinkage porosity, which caused eccentricity, loss and noise during motor operation. Many attempts have been made to develop methods of shrinkage porosity control, but still there are some problems to solve. In this research, the process of vacuum squeeze die casting is proposed for limitation of defects. The 6 pin point gated dies which were in capable of local squeeze at the end ring were used. Influences of filling patterns on HPDC were evaluated and the important process control parameters were high injection speed, squeeze length, venting and process conditions. By using local squeeze and vacuum during filling and solidification, air and shrinkage porosity were significantly reduced and the feeding efficiency at the upper end ring was improved 10%. As a result of controlling the defects, the dynamometer test showed improved motor efficiency by more than 4%.

Aerosol particle shrinkage event phenomenology in a South European suburban area during 2009-2015

NASA Astrophysics Data System (ADS)

Alonso-Blanco, E.; Gómez-Moreno, F. J.; Núñez, L.; Pujadas, M.; Cusack, M.; Artíñano, B.

2017-07-01

A high number of aerosol particle shrinkage cases (70) have been identified and analyzed from an extensive and representative database of aerosol size distributions obtained between 2009 and 2015 at an urban background site in Madrid (Spain). A descriptive classification based on the process from which the shrinkage began is proposed according which shrinkage events were divided into three groups: (1) NPF + shrinkage (NPF + S) events, (2) aerosol particle growth process + shrinkage (G + S) events, and (3) pure shrinkage (S) events. The largest number of shrinkages corresponded to the S-type followed by NPF + S, while the G + S events were the least frequent group recorded. Duration of shrinkages varied widely from 0.75 to 8.5 h and SR from -1.0 to -11.1 nm h-1. These processes typically occurred in the afternoon, around 18:00 UTC, caused by two situations: i) a wind speed increase usually associated with a change in the wind direction (over 60% of the observations) and ii) the reduction of photochemical activity at the end of the day. All shrinkages were detected during the warm period, mainly between May and August, when local meteorological conditions (high solar irradiance and temperature and low relative humidity), atmospheric processes (high photochemical activity) and availability of aerosol-forming precursors were favorable for their development. As a consequence of these processes, the particles concentration corresponding to the Aitken mode decreased into the nucleation mode. The accumulation mode did not undergo significant changes during these processes. In some cases, a dilution of the particulate content in the ambient air was observed. This work, goes further than others works dealing with aerosol particles shrinkages, as it incorporates as a main novelty a classification methodology for studying these processes. Moreover, compared to other studies, it is supported by a high and representative number of observations. Thus, this study contributes to

Shrinkage and growth compensation in common sunflowers: refining estimates of damage

USGS Publications Warehouse

Sedgwick, James A.; Oldemeye, John L.; Swenson, Elizabeth L.

1986-01-01

Shrinkage and growth compensation of artificially damaged common sunflowers (Helianthus annuus) were studied in central North Dakota during 1981-1982 in an effort to increase accuracy of estimates of blackbird damage to sunflowers. In both years, as plants matured damaged areas on seedheads shrank at a greater rate than the sunflower heads themselves. This differential shrinkage resulted in an underestimation of the area damaged. Sunflower head and damaged-area shrinkage varied widely by time and degree of damage and by size of the seedhead damaged. Because variation in shrinkage by time of damage was so large, predicting when blackbird damage occurs may be the most important factor in estimating seed loss. Yield'occupied seed area was greater (P < 0.05) for damaged than undamaged heads and tended to increase as degree of damage inflicted increased, indicating growth compensation was occurring in response to lost seeds. Yields of undamaged seeds in seedheads damaged during early seed development were higher than those of heads damaged later. This suggested that there was a period of maximal response to damage when plants were best able to redirect growth to seeds remaining in the head. Sunflowers appear to be able to compensate for damage of ≤ 15% of the total hear area. Estimates of damage can be improved by applying empirical results of differential shrinkage and growth compensations.

Technical innovations in ear reconstruction using a skin expander with autogenous cartilage grafts.

PubMed

Dashan, Yu; Haiyue, Jiang; Qinghua, Yang; Bo, Pan; Lin, Lin; Tailing, Wang; Yanmei, Wang; Xiao, Qin; Hongxing, Zhuang

2008-01-01

Pioneers such as Tanzer and Brent have established the foundations of microtia reconstruction using an autogenous costal cartilage framework. The framework and its skin coverage are the two limiting factors in ear reconstruction. At the present time autogenous rib cartilage and mastoid skin are still first choice materials for most surgeons. They have the combined advantages of well-matched texture and colour. To reconstruct a symmetrical, accurate, prominent auricle and minimise as much as possible the chest wall deformity caused by rib cartilage harvesting, we set out to improve our techniques for cartilaginous framework definition and to use the remnant ear to enhance the projection of the reconstructed ear. Since 2000, 342 cases (366 ears) were treated using our current techniques. Data pertaining to complications were recorded. Final results were assessed a minimum of 1 year postoperatively. The follow-up period ranged from 1 to 6 years. Most of the patients with microtia were satisfied with the results of their ear reconstruction. In conclusion, our techniques help to reduce the quantity of rib cartilage needed to fabricate ear framework and minimise chest wall deformity. The frameworks are accurate, prominent and stable. Reconstructed ears are similar in colour and appearance to the normal side. Our innovations are practical and reliable for microtia reconstruction using skin expanders in combination with a sculpted autogenous rib cartilage framework.

Minimum risk wavelet shrinkage operator for Poisson image denoising.

PubMed

Cheng, Wu; Hirakawa, Keigo

2015-05-01

The pixel values of images taken by an image sensor are said to be corrupted by Poisson noise. To date, multiscale Poisson image denoising techniques have processed Haar frame and wavelet coefficients--the modeling of coefficients is enabled by the Skellam distribution analysis. We extend these results by solving for shrinkage operators for Skellam that minimizes the risk functional in the multiscale Poisson image denoising setting. The minimum risk shrinkage operator of this kind effectively produces denoised wavelet coefficients with minimum attainable L2 error.

Use of autogenous bone and beta-tricalcium phosphate in maxillary sinus lifting: histomorphometric study and immunohistochemical assessment of RUNX2 and VEGF.

PubMed

Pereira, R S; Gorla, L F; Boos, F B J D; Okamoto, R; Garcia Júnior, I R; Hochuli-Vieira, E

2017-04-01

The aim of this study was to compare the use of beta-tricalcium phosphate (β-TCP) (chronOS) with autogenous bone grafts alone in maxillary sinus elevation surgery. The test samples were β-TCP alone, β-TCP mixed with autogenous bone grafts (1:1), and autogenous bone grafts alone. Twelve maxillary sinuses were grafted with β-TCP (group 1), nine with β-TCP+autogenous bone graft (group 2), and 12 with autogenous bone graft (group 3). After 6 months, biopsies were obtained concurrent to the placement of dental implants; these were subjected to histomorphometric analysis and immunohistochemical analysis for runt-related transcription factor 2 (RUNX2) and vascular endothelial growth factor (VEGF). The average bone formation in group 1 was 46.3±11.6% in the pristine bone region, 47.6±9.9% in the intermediate region, and 44.8±22.1% in the apical region; in group 2, values were 35.0±15.8%, 32.5±13.7%, and 32.8±16.0%, respectively; in group 3, values were 43.1±16.0%, 31.0±13.0%, and 46.1±16.3%, respectively. Immunostaining of samples in group 2 showed high cellular activity and immature bone; this differed from groups 1 and 3, in which mature bone was demonstrated. Thus, this study showed that β-TCP presents the same behaviour as autogenous bone graft, which makes it a good bone substitute. Copyright © 2017 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

[Assessment of therapeutic results for simple bone cyst with percutaneous injection of autogenous bone marrow].

PubMed

Wang, Enbo; Zhao, Qun; Zhang, Lijun

2006-09-01

To evaluate the therapeutic results of percutaneous injection of autogenous bone marrow for simple bone cyst and to analyze the prognostic factors of the treatment. From March 2000 to June 2005, 31 patients with simple bone cysts were treated by percutaneous injection of autogenous bone marrow. Of 31 patients, there were 18 males and 13 females, aged 5 years and 7 months to 15 years. The locations were proximal humerus in 18 cases, proximal femur in 7 cases and other sites in 6 cases. Two cases were treated with repeated injections. The operative process included percutaneous aspiration of fluid in the bone cysts and injection of autogenous bone marrow aspirated from posterior superior iliac spine. The mean volume of marrow injected was 40 ml (30-70 ml). No complications were noted during treatment. Thirty patients were followed for an average of 2.2 years (1-5 years) with 2 cases out of follow-up. After one injection of bone marrow, 9 cysts (29.0%) were healed up completely, 7 cysts (22.6%) basically healed up, 13 cysts (41.9%) healed up partially and 2 (6.5%) had no response. The satisfactory and effective rates were 67.7% and 93.5% respectively. There was significant difference between active stage group and resting stage group(P<0.05). There were no statistically significant difference in therapeutic results between groups of different ages, lesion sites or bone marrow hyperplasia(P>0.05). Percutaneous injection of autogenous bone marrow is a safe and effective method to treat simple bone cyst, but repeated injections is necessary for some patients. The therapeutic results are better in cysts at resting stage than those at active stage.

A model for shrinkage strain in photo polymerization of dental composites.

PubMed

Petrovic, Ljubomir M; Atanackovic, Teodor M

2008-04-01

We formulate a new model for the shrinkage strain developed during photo polymerization in dental composites. The model is based on the diffusion type fractional order equation, since it has been proved that polymerization reaction is diffusion controlled (Atai M, Watts DC. A new kinetic model for the photo polymerization shrinkage-strain of dental composites and resin-monomers. Dent Mater 2006;22:785-91). Our model strongly confirms the observation by Atai and Watts (see reference details above) and their experimental results. The shrinkage strain is modeled by a nonlinear differential equation in (see reference details above) and that equation must be solved numerically. In our approach, we use the linear fractional order differential equation to describe the strain rate due to photo polymerization. This equation is solved exactly. As shrinkage is a consequence of the polymerization reaction and polymerization reaction is diffusion controlled, we postulate that shrinkage strain rate is described by a diffusion type equation. We find explicit form of solution to this equation and determine the strain in the resin monomers. Also by using equations of linear viscoelasticity, we determine stresses in the polymer due to the shrinkage. The time evolution of stresses implies that the maximal stresses are developed at the very beginning of the polymerization process. The stress in a dental composite that is light treated has the largest value short time after the treatment starts. The strain settles at the constant value in the time of about 100s (for the cases treated in Atai and Watts). From the model developed here, the shrinkage strain of dental composites and resin monomers is analytically determined. The maximal value of stresses is important, since this value must be smaller than the adhesive bond strength at cavo-restoration interface. The maximum stress determined here depends on the diffusivity coefficient. Since diffusivity coefficient increases as

Centrifugation-assisted Assembly of Colloidal Silica into Crack-Free and Transferrable Films with Tunable Crystalline Structures

PubMed Central

Fan, Wen; Chen, Min; Yang, Shu; Wu, Limin

2015-01-01

Self-assembly of colloidal particles into colloidal films has many actual and potential applications. While various strategies have been developed to direct the assembly of colloidal particles, fabrication of crack-free and transferrable colloidal film with controllable crystal structures still remains a major challenge. Here we show a centrifugation-assisted assembly of colloidal silica spheres into free-standing colloidal film by using the liquid/liquid interfaces of three immiscible phases. Through independent control of centrifugal force and interparticle electrostatic repulsion, polycrystalline, single-crystalline and quasi-amorphous structures can be readily obtained. More importantly, by dehydration of silica particles during centrifugation, the spontaneous formation of capillary water bridges between particles enables the binding and pre-shrinkage of the assembled array at the fluid interface. Thus the assembled colloidal films are not only crack-free, but also robust and flexible enough to be easily transferred on various planar and curved substrates. PMID:26159121

The application of autogenic training in counseling center for mother and child in order to promote breastfeeding.

PubMed

Vidas, Mercedes; Folnegović-Smalc, Vera; Catipović, Marija; Kisić, Marko

2011-09-01

The aim of this study was to investigate whether mothers with newborn children, the usage of autogenic training with advice on breastfeeding effect on: the decision and the duration of breastfeeding, increase maternal confidence and support. It was assumed that the above result in a higher percentage of mothers who exclusively breastfed baby during the first six months of child's life. The survey was conducted in the Association "For a healthy and happy childhood"-Counseling center for mother and child, in Bjelovar in 2010. The Counseling center was attended by 100 nursing mothers with children aged up to two months. They randomly went to the study or control group. Mothers of both groups were advised to successful breastfeeding. Study group has practiced autogenic training until the child's age of six months. In parallel, by using psychotherapeutic interview and specific questionnaires we collected data on the somatic, psychological and social situation of the mother, discovered mother's mental changes (anxiety, depression) that were treated. The results at the end of the study confirm the initial expected benefits from the application of autogenic training. Mothers of the study group were significantly more emotionally balanced with a higher self-esteem. Autogenous training with the advices for successful breastfeeding conducted in this counseling center contributed in significantly higher rate of breastfeeding children up to six months of life, improved mental and physical health of mother and child and their peculiar relationship.

[Effect of autogenic training with cognitive and symbol therapy on the treatment of patients with primary headache].

PubMed

Zsombók, Terézia; Juhász, Gabriella; Gonda, Xénia; Vitrai, József; Bagdy, György

2005-01-01

Only a minor part of headaches are associated with an organic abnormality in the nervous system. In case of migraine and tension headache, the main provoking factor is psychological stress. Furthermore, these syndromes often occur together with depression and anxiety disorders, and when these comorbid conditions are present headache attacks tend to be more frequent, longer and stronger, causing an increase in the consumption of antimigraine agents, and at the same time increase the consumption of antidepressant and anxiolytic agents. Further to drugs, modified versions of Schultz-type autogenic training is also frequently used for anxiolysis. The aim of our research was to study the effect of the cognitive and symbol therapy enhanced autogenic training on headache and related drug consumption in three different types of primary headaches. Twenty five female patients with migraine, tension-type headache or mixed headache participated in an eight-month follow-up study. Headache frequency, analgesic, antimigraine and anxiolytic consumption were measured by means of a headache diary. During the first four months (observation phase) patients became familiar with using the diary, and in the second four months they participated in autogenic training. The data of the second, third and fourth months were considered as baseline data. Our method decreased headache frequency and drug consumption in all three headache groups. This means that the cognitive and symbol therapy enhanced autogenic training is an effective alternative for medications in the treatment of primary headaches.

Study of SEM preparation artefacts with correlative microscopy: Cell shrinkage of adherent cells by HMDS-drying.

PubMed

Katsen-Globa, Alisa; Puetz, Norbert; Gepp, Michael M; Neubauer, Julia C; Zimmermann, Heiko

2016-11-01

One of the often reported artefacts during cell preparation to scanning electron microscopy (SEM) is the shrinkage of cellular objects, that mostly occurs at a certain time-dependent stage of cell drying. Various methods of drying for SEM, such as critical point drying, freeze-drying, as well as hexamethyldisilazane (HMDS)-drying, were usually used. The latter becomes popular since it is a low cost and fast method. However, the correlation of drying duration and real shrinkage of objects was not investigated yet. In this paper, cell shrinkage at each stage of preparation for SEM was studied. We introduce a shrinkage coefficient using correlative light microscopy (LM) and SEM of the same human mesenchymal stem cells (hMSCs). The influence of HMDS-drying duration on the cell shrinkage is shown: the longer drying duration, the more shrinkage is observed. Furthermore, it was demonstrated that cell shrinkage is inversely proportional to cultivation time: the longer cultivation time, the more cell spreading area and the less cell shrinkage. Our results can be applicable for an exact SEM quantification of cell size and determination of cell spreading area in engineering of artificial cellular environments using biomaterials. SCANNING 38:625-633, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

In-place cement stabilized base reconstruction techniques interim report, "construction and two year evaluation" : technical summary.

DOT National Transportation Integrated Search

2002-08-01

The purpose of this research is to evaluate the effectiveness of soil cement shrinkage crack mitigation techniques. Ten test sections, 1000 feet long, were constructed on LA 89 in Vermilion Parish. The shrinkage crack mitigation methods being evaluat...

Autogenic-Feedback Training Exercise (AFTE) Method and System

NASA Technical Reports Server (NTRS)

Cowings, Patricia S. (Inventor)

1997-01-01

The Autogenic-Feedback Training Exercise (AFTE) method of the present invention is a combined application of physiologic and perceptual training techniques. such as autogenic therapy and biofeedback. This combined therapy approach produces a methodology that is appreciably more effective than either of the individual techniques used separately. The AFTE method enables sufficient magnitude of control necessary to significantly reduce the behavioral and physiologic reactions to severe environmental stressors. It produces learned effects that are persistent over time and are resistant to extinction and it can be administered in a short period of time. The AFTE method may be used efficiently in several applications, among which are the following: to improve pilot and crew performance during emergency flying conditions; to train people to prevent the occurrence of nausea and vomiting associated with motion and sea sickness, or morning sickness in early pregnancy; as a training method for preventing or counteracting air-sickness symptoms in high-performance military aircraft; for use as a method for cardiovascular training, as well as for multiple other autonomic responses, which may contribute to the alleviation of Space Motion Sickness (SMS) in astronauts and cosmonauts; training people suffering from migraine or tension headaches to control peripheral blood flow and reduce forehead and/or trapezius muscle tension; training elderly people suffering from fecal incontinence to control their sphincter muscles; training cancer patients to reduce the nauseagenic effects of chemotherapy; and training patients with Chronic Intestinal Pseudo-obstruction (CIP).

The effect of mucosal cuff shrinkage around dental implants during healing abutment replacement.

PubMed

Nissan, J; Zenziper, E; Rosner, O; Kolerman, R; Chaushu, L; Chaushu, G

2015-10-01

Soft tissue shrinkage during the course of restoring dental implants may result in biological and prosthodontic difficulties. This study was conducted to measure the continuous shrinkage of the mucosal cuff around dental implants following the removal of the healing abutment up to 60 s. Individuals treated with implant-supported fixed partial dentures were included. Implant data--location, type, length, diameter and healing abutments' dimensions--were recorded. Mucosal cuff shrinkage, following removal of the healing abutments, was measured in bucco-lingual direction at four time points--immediately after 20, 40 and 60 s. anova was used to for statistical analysis. Eighty-seven patients (49 women and 38 men) with a total of 311 implants were evaluated (120 maxilla; 191 mandible; 291 posterior segments; 20 anterior segments). Two-hundred and five (66%) implants displayed thick and 106 (34%) thin gingival biotype. Time was the sole statistically significant parameter affecting mucosal cuff shrinkage around dental implants (P < 0.001). From time 0 to 20, 40 and 60 s, the mean diameter changed from 4.1 to 4.07, 3.4 and 2.81 mm, respectively. The shrinkage was 1%, 17% and 31%, respectively. The gingival biotype had no statistically significant influence on mucosal cuff shrinkage (P = 0.672). Time required replacing a healing abutment with a prosthetic element should be minimised (up to 20/40 s), to avoid pain, discomfort and misfit. © 2015 John Wiley & Sons Ltd.

3D full field strain analysis of polymerization shrinkage in a dental composite.

PubMed

Martinsen, Michael; El-Hajjar, Rani F; Berzins, David W

2013-08-01

The objective of this research was to study the polymerization shrinkage in a dental composite using 3D digital image correlation (DIC). Using 2 coupled cameras, digital images were taken of bar-shaped composite (Premise Universal Composite; Kerr) specimens before light curing and after for 10 min. Three-dimensional DIC was used to assess in-plane and out-of-plane deformations associated with polymerization shrinkage. The results show the polymerization shrinkage to be highly variable with the peak values occurring 0.6-0.8mm away from the surface. Volumetric shrinkage began to significantly decrease at 3.2mm from the specimen surface and reached a minimum at 4mm within the composite. Approximately 25-30% of the strain registered at 5 min occurred after light-activation. Application of 3D DIC dental applications can be performed without the need for assumptions on the deformation field. Understanding the local deformations and strain fields from the initial polymerization shrinkage can lead to a better understanding of the composite material and interaction with surrounding tooth structure, aiding in their further development and clinical prognosis. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Shrinkage Prediction for the Investment Casting of Stainless Steels

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

Sabau, Adrian S

2007-01-01

In this study, the alloy shrinkage factors were obtained for the investment casting of 17-4PH stainless steel parts. For the investment casting process, unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively. Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine in order to obtain the actual tooling allowances. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. The numerical simulation results for the shrinkage factors were compared with experimental results.

Some Issues of Shrinkage-Reducing Admixtures Application in Alkali-Activated Slag Systems

PubMed Central

Bílek, Vlastimil; Kalina, Lukáš; Novotný, Radoslav; Tkacz, Jakub; Pařízek, Ladislav

2016-01-01

Significant drying shrinkage is one of the main limitations for the wider utilization of alkali-activated slag (AAS). Few previous works revealed that it is possible to reduce AAS drying shrinkage by the use of shrinkage-reducing admixtures (SRAs). However, these studies were mainly focused on SRA based on polypropylene glycol, while as it is shown in this paper, the behavior of SRA based on 2-methyl-2,4-pentanediol can be significantly different. While 0.25% and 0.50% had only a minor effect on the AAS properties, 1.0% of this SRA reduced the drying shrinkage of waterglass-activated slag mortar by more than 80%, but it greatly reduced early strengths simultaneously. This feature was further studied by isothermal calorimetry, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). Calorimetric experiments showed that 1% of SRA modified the second peak of the pre-induction period and delayed the maximum of the main hydration peak by several days, which corresponds well with observed strength development as well as with the MIP and SEM results. These observations proved the certain incompatibility of SRA with the studied AAS system, because the drying shrinkage reduction was induced by the strong retardation of hydration, resulting in a coarsening of the pore structure rather than the proper function of the SRA. PMID:28773584

Quantity Effect of Radial Cracks on the Cracking Propagation Behavior and the Crack Morphology

PubMed Central

Chen, Jingjing; Xu, Jun; Liu, Bohan; Yao, Xuefeng; Li, Yibing

2014-01-01

In this letter, the quantity effect of radial cracks on the cracking propagation behavior as well as the circular crack generation on the impacted glass plate within the sandwiched glass sheets are experimentally investigated via high-speed photography system. Results show that the radial crack velocity on the backing glass layer decreases with the crack number under the same impact conditions during large quantities of repeated experiments. Thus, the “energy conversion factor” is suggested to elucidate the physical relation between the cracking number and the crack propagation speed. Besides, the number of radial crack also takes the determinative effect in the crack morphology of the impacted glass plate. This study may shed lights on understanding the cracking and propagation mechanism in laminated glass structures and provide useful tool to explore the impact information on the cracking debris. PMID:25048684

Self-desiccation mechanism of high-performance concrete.

PubMed

Yang, Quan-Bing; Zhang, Shu-Qing

2004-12-01

Investigations on the effects of W/C ratio and silica fume on the autogenous shrinkage and internal relative humidity of high performance concrete (HPC), and analysis of the self-desiccation mechanisms of HPC showed that the autogenous shrinkage and internal relative humidity of HPC increases and decreases with the reduction of W/C respectively; and that these phenomena were amplified by the addition of silica fume. Theoretical analyses indicated that the reduction of RH in HPC was not due to shortage of water, but due to the fact that the evaporable water in HPC was not evaporated freely. The reduction of internal relative humidity or the so-called self-desiccation of HPC was chiefly caused by the increase in mole concentration of soluble ions in HPC and the reduction of pore size or the increase in the fraction of micro-pore water in the total evaporable water (T(r)/T(te) ratio).

Improving the Incoherence of a Learned Dictionary via Rank Shrinkage.

PubMed

Ubaru, Shashanka; Seghouane, Abd-Krim; Saad, Yousef

2017-01-01

This letter considers the problem of dictionary learning for sparse signal representation whose atoms have low mutual coherence. To learn such dictionaries, at each step, we first update the dictionary using the method of optimal directions (MOD) and then apply a dictionary rank shrinkage step to decrease its mutual coherence. In the rank shrinkage step, we first compute a rank 1 decomposition of the column-normalized least squares estimate of the dictionary obtained from the MOD step. We then shrink the rank of this learned dictionary by transforming the problem of reducing the rank to a nonnegative garrotte estimation problem and solving it using a path-wise coordinate descent approach. We establish theoretical results that show that the rank shrinkage step included will reduce the coherence of the dictionary, which is further validated by experimental results. Numerical experiments illustrating the performance of the proposed algorithm in comparison to various other well-known dictionary learning algorithms are also presented.

A combined approach of enamel matrix derivative gel and autogenous bone grafts in treatment of intrabony periodontal defects. A case report.

PubMed

Leung, George; Jin, Lijian

2003-04-01

Enamel matrix derivative (EMD) has recently been introduced as a new modality in regenerative periodontal therapy. This case report demonstrates a combined approach in topical application of EMD gel (Emdogain) and autogenous bone grafts for treatment of intrabony defects and furcation involvement defects in a patient with chronic periodontitis. The seven-month post-surgery clinical and radiographic results were presented. The combined application of EMD gel with autogenous bone grafts in intrabony osseous defects resulted in clinically significant gain of attachment on diseased root surfaces and bone fill on radiographs. Further controlled clinical studies are required to confirm the long-term effectiveness of the combination of EMD gel and autogenous bone grafts in treatment of various osseous defects in subjects with chronic periodontitis.

Stress fracture as a complication of autogenous bone graft harvest from the distal tibia.

PubMed

Chou, Loretta B; Mann, Roger A; Coughlin, Michael J; McPeake, William T; Mizel, Mark S

2007-02-01

Autogenous bone graft from the distal tibia provides cancellous bone graft for foot and ankle operations, and it has osteogenic and osteoconductive properties. The site is in close proximity to the foot and ankle, and published retrospective studies show low morbidity from the procedure. One-hundred autografts were obtained from the distal tibia between 2000 and 2003. In four cases the distal tibial bone graft harvest resulted in a stress fracture. There were three women and one man. The average time of diagnosis of the stress fracture from the operation was 1.8 months. All stress fractures healed with a short course (average 2.4 months) of cast immobilization. This study demonstrated that a stress fracture from the donor site of autogenous bone graft of the distal tibia occurs and can be successfully treated nonoperatively.

First evaluation of endotoxins in veterinary autogenous vaccines produced in Italy by LAL assay.

PubMed

Antonella, Di Paolo; Katia, Forti; Lucia, Anzalone; Sara, Corneli; Martina, Pellegrini; Giulio, Severi; Monica, Cagiola

2018-06-21

Endotoxin contamination is a serious concern for manufacturers of biological products and vaccines in terms of not only quality but also safety parameters. We evaluated the endotoxin presence in different veterinary autogenous vaccines produced by the Pharmaceutical Unit at the Experimental Zooprophylactic Institute of Umbria and Marche "Togo Rosati" (IZSUM). According to the 3Rs principles (Replace, Reduce, Refine), which aim to progressively reduce animal use in the quality control process, we tested the vaccines obtained from gram-negative bacteria and adjuvants by the limulus amebocyte lysate (LAL) assay. The results revealed low endotoxin concentrations compared to available data in the literature and represent the first report of the application of the 3Rs principles to veterinary autogenous vaccines production in Italy. Copyright © 2018. Published by Elsevier Ltd.

Micromechanical Analysis of Crack Closure Mechanism for Intelligent Material Containing TiNi Fibers

NASA Astrophysics Data System (ADS)

Araki, Shigetoshi; Ono, Hiroyuki; Saito, Kenji

In our previous study, the micromechanical modeling of an intelligent material containing TiNi fibers was performed and the stress intensity factor KI at the tip of the crack in the material was expressed in terms of the magnitude of the shape memory shrinkage of the fibers and the thermal expansion strain in the material. In this study, the value of KI at the tip of the crack in the TiNi/epoxy material is calculated numerically by using analytical expressions obtained in our first report. As a result, we find that the KI value decreases with increasing shrink strain of the fibers, and this tendency agrees with that of the experimental result obtained by Shimamoto etal.(Trans. Jpn. Soc. Mech. Eng., Vol. 65, No. 634 (1999), pp. 1282-1286). Moreover, there exists an optimal value of the shrink strain of the fibers to make the KI value zero. The change in KI with temperature during the heating process from the reference temperature to the inverse austenitic finishing temperature of TiNi fiber is also consistent with the experimental result. These results can be explained by the changes in the shrink strain, the thermal expansion strain, and the elastic moduli of TiNi fiber with temperature. These results may be useful in designing intelligent materials containing TiNi fibers from the viewpoint of crack closure.

Lateral ridge augmentation with Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone graft: a systematic review.

PubMed

Aludden, H C; Mordenfeld, A; Hallman, M; Dahlin, C; Jensen, T

2017-08-01

The objective of this systematic review was to test the hypothesis of no difference in implant treatment outcomes when using Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone grafts for lateral ridge augmentation. A search of the MEDLINE, Cochrane Library, and Embase databases in combination with a hand-search of relevant journals was conducted. Human studies published in English from 1 January 1990 to 1 May 2016 were included. The search provided 337 titles and six studies fulfilled the inclusion criteria. Considerable variation prevented a meta-analysis from being performed. The two treatment modalities have never been compared within the same study. Non-comparative studies demonstrated a 3-year implant survival of 96% with 50% Bio-Oss mixed with 50% autogenous bone graft. Moreover, Bio-Oss alone or Bio-Oss mixed with autogenous bone graft seems to increase the amount of newly formed bone as well as the width of the alveolar process. Within the limitations of this systematic review, lateral ridge augmentation with Bio-Oss alone or in combination with autogenous bone graft seems to induce newly formed bone and increase the width of the alveolar process, with high short-term implant survival. However, long-term studies comparing the two treatment modalities are needed before final conclusions can be drawn. Copyright © 2017 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Low-shrink composite resins: a review of their history, strategies for managing shrinkage, and clinical significance.

PubMed

Pitel, Mark L

2013-09-01

Despite numerous advances in composite resin technology over the course of many decades, shrinkage behavior and the resultant stresses inherent to direct placed composite restorations continue to challenge clinicians. This overview of composite resins includes a review of their history and development along with a discussion of strategies for reducing polymerization shrinkage. An assessment of the clinical significance of these materials is also provided, including a discussion of the differences between polymerization shrinkage and stress, incremental layering versus bulk placement, and the emergence of lower shrinkage stress monomer chemistry.

A Crack Growth Evaluation Method for Interacting Multiple Cracks

NASA Astrophysics Data System (ADS)

Kamaya, Masayuki

When stress corrosion cracking or corrosion fatigue occurs, multiple cracks are frequently initiated in the same area. According to section XI of the ASME Boiler and Pressure Vessel Code, multiple cracks are considered as a single combined crack in crack growth analysis, if the specified conditions are satisfied. In crack growth processes, however, no prescription for the interference between multiple cracks is given in this code. The JSME Post-Construction Code, issued in May 2000, prescribes the conditions of crack coalescence in the crack growth process. This study aimed to extend this prescription to more general cases. A simulation model was applied, to simulate the crack growth process, taking into account the interference between two cracks. This model made it possible to analyze multiple crack growth behaviors for many cases (e. g. different relative position and length) that could not be studied by experiment only. Based on these analyses, a new crack growth analysis method was suggested for taking into account the interference between multiple cracks.

Effect of autogenic training on cardiac autonomic nervous activity in high-risk fire service workers for posttraumatic stress disorder.

PubMed

Mitani, Satoko; Fujita, Masatoshi; Sakamoto, Satoko; Shirakawa, Taro

2006-05-01

We investigated the effect of autogenic training (AT) on cardiac autonomic nervous activity in fire services workers with the use of the questionnaire of the Japanese-language version of Impact of Event Scale-Revised (IES-R-J) and indexes of heart rate variability. We studied 22 male fire services workers who were divided into posttraumatic stress disorder (PTSD)-related stress group (n=10) and control group (n=12). They underwent AT twice or three times a week for 2 months. Posttraumatic stress disorder-related stress group showed a significantly higher cardiac sympathetic nervous activity and a significantly lower cardiac parasympathetic nervous activity than control group at baseline. Autogenic training significantly decreased cardiac sympathetic nervous activity and significantly increased cardiac parasympathetic nervous activity in both groups. These changes were accompanied by a significant decrease in the total points of IES-R-J. Autogenic training is effective for ameliorating the disturbance of cardiac autonomic nervous activity and psychological issues secondary to PTSD.

Autogenous electrolyte, non-pyrolytically produced solid capacitor structure

DOEpatents

Sharp, Donald J.; Armstrong, Pamela S.; Panitz, Janda Kirk G.

1998-01-01

A solid electrolytic capacitor having a solid electrolyte comprising manganese dioxide dispersed in an aromatic polyamide capable of further cure to form polyimide linkages, the solid electrolyte being disposed between a first electrode made of valve metal covered by an anodic oxide film and a second electrode opposite the first electrode. The electrolyte autogenously produces water, oxygen, and hydroxyl groups which act as healing substances and is not itself produced pyrolytically. Reduction of the manganese dioxide and the water molecules released by formation of imide linkages result in substantially improved self-healing of anodic dielectric layer defects.

Autogenous electrolyte, non-pyrolytically produced solid capacitor structure

DOEpatents

Sharp, D.J.; Armstrong, P.S.; Panitz, J.K.G.

1998-03-17

A solid electrolytic capacitor is described having a solid electrolyte comprising manganese dioxide dispersed in an aromatic polyamide capable of further cure to form polyimide linkages, the solid electrolyte being disposed between a first electrode made of valve metal covered by an anodic oxide film and a second electrode opposite the first electrode. The electrolyte autogenously produces water, oxygen, and hydroxyl groups which act as healing substances and is not itself produced pyrolytically. Reduction of the manganese dioxide and the water molecules released by formation of imide linkages result in substantially improved self-healing of anodic dielectric layer defects. 2 figs.

Autogenic-feedback training: A countermeasure for orthostatic intolerance

NASA Technical Reports Server (NTRS)

Cowings, Patricia S.; Toscano, William B.; Kamiya, Joe; Miller, Neal E.; Pickering, Thomas G.

1991-01-01

NASA has identified cardiovascular deconditioning as a serious biomedical problem associated with long-duration exposure to microgravity in space. High priority has been given to the development of countermeasures for this disorder and the resulting orthostatic intolerance experienced by crewmembers upon their return to the 1g norm of Earth. The present study was designed to examine the feasibility of training human subjects to control their own cardiovascular responses to gravitational stimulation (i.e., a tilt table). Using an operant conditioning procedure, Autogenic-Feedback Training (AFT), we would determine if subjects could learn to increase their own blood pressure voluntarily.

Autogenous Partial Bone Chip Grafting on the Exposed Inferior Alveolar Nerve After Cystic Enucleation.

PubMed

Seo, Mi Hyun; Eo, Mi Young; Cho, Yun Ju; Kim, Soung Min; Lee, Suk Keun

2018-03-01

This prospective study evaluated the clinical effectiveness of the new approach of partial autogenous bone chip grafts for the treatment of mandibular cystic lesions related to the inferior alveolar nerve (IAN). A total of 38 patients treated for mandibular cysts or benign tumors were included in this prospective study and subsequently divided into 3 groups depending on the bone grafting method used: cystic enucleation without a bone graft (group 1), partial bone chip graft covering the exposed IAN (group 2), and autogenous bone graft covering the entire defect (group 3). We evaluated the symptoms, clinical signs, and radiographic changes using dental panorama preoperatively, immediate postoperatively, and at 1, 3, 6, and 12 months postoperatively. Radiographic densities were compared using Adobe Photoshop CS5 (Adobe Systems Inc., San Jose, CA). Repeated measures analysis of variance was used for statistical evaluation with SPSS 22.0 (SPSS Inc, Chicago, IL), and P < 0.05 was considered statistically significant.Radiopacities were the most increased at 1 year postoperative in group 3; groups 2 and 3 did not show statistically significant differences, whereas groups 1 and 3 were statistically significant. In terms of radiographic bone healing with clinical regeneration of the exposed IAN, healing occurred in all patients, although the best healing was achieved in group 2.This autogenous partial bone chip grafting procedure to cover the exposed IAN is suggested as a new surgical protocol for the treatment of cystic lesions associated with the IAN.

Autogenous accelerated curing of concrete cylinders. Part II, Development of a moisture measuring method.

DOT National Transportation Integrated Search

1970-01-01

Through a literature study, approximately fifty methods of measuring moisture were investigated to ascertain a suitable method for use in measuring moisture changes in 6 inch by 12 inch concrete cylinders cured by the autogenous accelerated curing me...

Characteristics of low polymerization shrinkage flowable resin composites in newly-developed cavity base materials for bulk filling technique.

PubMed

Nitta, Keiko; Nomoto, Rie; Tsubota, Yuji; Tsuchikawa, Masuji; Hayakawa, Tohru

2017-11-29

The purpose of this study was to evaluate polymerization shrinkage and other physical properties of newly-developed cavity base materials for bulk filling technique, with the brand name BULK BASE (BBS). Polymerization shrinkage was measured according to ISO/FDIS 17304. BBS showed the significantly lowest polymerization shrinkage and significantly higher depth of cure than conventional flowable resin composites (p<0.05). The Knoop hardness, flexural strength and elastic modulus of that were significantly lower than conventional flowable resin composites (p<0.05). BBS had the significantly greatest filler content (p<0.05). SEM images of the surface showed failure of fillers. The lowest polymerization shrinkage was due to the incorporation of a new type of low shrinkage monomer, which has urethane moieties. There were no clear correlations between inorganic filler contents and polymerization shrinkage, flexural strength and elastic modulus. In conclusion, the low polymerization shrinkage of BBS will be useful for cavity treatment in dental clinics.

Reduced heart rate variability and vagal tone in anxiety: trait versus state, and the effects of autogenic training.

PubMed

Miu, Andrei C; Heilman, Renata M; Miclea, Mircea

2009-01-28

This study investigated heart rate variability (HRV) in healthy volunteers that were selected for extreme scores of trait anxiety (TA), during two opposite psychophysiological conditions of mental stress, and relaxation induced by autogenic training. R-R intervals, HF and LF powers, and LF/HF ratios were derived from short-term electrocardiographic recordings made during mental stress and relaxation by autogenic training, with respiratory rate and skin conductance being controlled for in all the analyses. The main finding was that high TA was associated with reduced R-R intervals and HF power across conditions. In comparison to mental stress, autogenic training increased HRV and facilitated the vagal control of the heart. There were no significant effects of TA or the psychophysiological conditions on LF power, or LF/HF ratio. These results support the view that TA, which is an important risk factor for anxiety disorders and predictor of cardiovascular morbidity and mortality, is associated with autonomic dysfunction that seems likely to play a pathogenetic role in the long term.

Microstructure Characterization and Stress Corrosion Evaluation of Autogenous and Hybrid Friction Stir Welded Al-Cu-Li 2195 Alloy

NASA Technical Reports Server (NTRS)

Li, Zhixian; Arbegast, William J.; Meletis, Efstathios I.

1997-01-01

Friction stir welding process is being evaluated for application on the Al-Cu-Li 2195 Super-Light Weight External Tank of the Space Transportation System. In the present investigation Al-Cu-Li 2195 plates were joined by autogenous friction stir welding (FSW) and hybrid FSW (friction stir welding over existing variable polarity plasma arc weld). Optical microscopy and transmission electron microscopy (TEM) were utilized to characterize microstructures of the weldments processed by both welding methods. TEM observations of autogenous FSW coupons in the center section of the dynamically-recrystallized zone showed an equiaxed recrystallized microstructure with an average grain size of approx. 3.8 microns. No T(sub 1), precipitates were present in the above-mentioned zone. Instead, T(sub B) and alpha precipitates were found in this zone with a lower population. Alternate immersion, anodic polarization, constant load, and slow strain tests were carried out to evaluate the general corrosion and stress-corrosion properties of autogenous and hybrid FSW prepared coupons. The experimental results will be discussed.

Prediction of Shrinkage Porosity Defect in Sand Casting Process of LM25

NASA Astrophysics Data System (ADS)

Rathod, Hardik; Dhulia, Jay K.; Maniar, Nirav P.

2017-08-01

In the present worldwide and aggressive environment, foundry commercial enterprises need to perform productively with least number of rejections and create casting parts in shortest lead time. It has become extremely difficult for foundry industries to meet demands of defects free casting and meet strict delivery schedules. The process of casting solidification is complex in nature. Prediction of shrinkage defect in metal casting is one of the critical concern in foundries and is one of the potential research areas in casting. Due to increasing pressure to improve quality and to reduce cost, it is very essential to upgrade the level of current methodology used in foundries. In the present research work, prediction methodology of shrinkage porosity defect in sand casting process of LM25 using experimentation and ANSYS is proposed. The objectives successfully achieved are prediction of shrinkage porosity distribution in Al-Si casting and determining effectiveness of investigated function for predicting shrinkage porosity by correlating results of simulating studies to those obtained experimentally. The real-time application of the research reflects from the fact that experimentation is performed on 9 different Y junctions at foundry industry and practical data obtained from experimentation are used for simulation.

Fabrication and characterization of self-folding thermoplastic sheets using unbalanced thermal shrinkage.

PubMed

Danielson, Christian; Mehrnezhad, Ali; YekrangSafakar, Ashkan; Park, Kidong

2017-06-14

Self-folding or micro-origami technologies are actively investigated as a novel manufacturing process to fabricate three-dimensional macro/micro-structures. In this paper, we present a simple process to produce a self-folding structure with a biaxially oriented polystyrene sheet (BOPS) or Shrinky Dinks. A BOPS sheet is known to shrink to one-third of its original size in plane, when it is heated above 160 °C. A grid pattern is engraved on one side of the BOPS film with a laser engraver to decrease the thermal shrinkage of the engraved side. The thermal shrinkage of the non-engraved side remains the same and this unbalanced thermal shrinkage causes folding of the structure as the structure shrinks at high temperature. We investigated the self-folding mechanism and characterized how the grid geometry, the grid size, and the power of the laser engraver affect the bending curvature. The developed fabrication process to locally modulate thermomechanical properties of the material by engraving the grid pattern and the demonstrated design methodology to harness the unbalanced thermal shrinkage can be applied to develop complicated self-folding macro/micro structures.

Predicting shrinkage and warpage in injection molding: Towards automatized mold design

NASA Astrophysics Data System (ADS)

Zwicke, Florian; Behr, Marek; Elgeti, Stefanie

2017-10-01

It is an inevitable part of any plastics molding process that the material undergoes some shrinkage during solidification. Mainly due to unavoidable inhomogeneities in the cooling process, the overall shrinkage cannot be assumed as homogeneous in all volumetric directions. The direct consequence is warpage. The accurate prediction of such shrinkage and warpage effects has been the subject of a considerable amount of research, but it is important to note that this behavior depends greatly on the type of material that is used as well as the process details. Without limiting ourselves to any specific properties of certain materials or process designs, we aim to develop a method for the automatized design of a mold cavity that will produce correctly shaped moldings after solidification. Essentially, this can be stated as a shape optimization problem, where the cavity shape is optimized to fulfill some objective function that measures defects in the molding shape. In order to be able to develop and evaluate such a method, we first require simulation methods for the diffierent steps involved in the injection molding process that can represent the phenomena responsible for shrinkage and warpage ina sufficiently accurate manner. As a starting point, we consider the solidification of purely amorphous materials. In this case, the material slowly transitions from fluid-like to solid-like behavior as it cools down. This behavior is modeled using adjusted viscoelastic material models. Once the material has passed a certain temperature threshold during cooling, any viscous effects are neglected and the behavior is assumed to be fully elastic. Non-linear elastic laws are used to predict shrinkage and warpage that occur after this point. We will present the current state of these simulation methods and show some first approaches towards optimizing the mold cavity shape based on these methods.

COMPARATIVE ANALYSIS OF THE SHRINKAGE STRESS OF COMPOSITE RESINS

PubMed Central

Pereira, Rosana Aparecida; de Araujo, Paulo Amarante; Castañeda-Espinosa, Juan Carlos; Mondelli, Rafael Francisco Lia

2008-01-01

The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500). In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different composites. Gaps between the composites and molds formed after polymerization were evaluated microscopically. In the third method, the wall-to-wall shrinkage stress of the resins that were placed in bovine dentin cavities was evaluated. The gaps were measured microscopically. Data were analyzed by one-way ANOVA and Tukey's test (α=0.05). The obtained contraction forces were: Grandio = 12.18 ± 0.428N; Filtek Z 250 = 11.80 ± 0.760N; Filtek Supreme = 11.80 ± 0.707 N; and Admira = 11.89 ± 0.647 N. The gaps obtained between composites and Teflon molds were: Filtek Z 250 = 0.51 ± 0.0357%; Filtek Supreme = 0.36 ± 0.0438%; Admira = 0.25 ± 0.0346% and Grandio = 0.16 ± 0.008%. The gaps obtained in wall-to-wall contraction were: Filtek Z 250 = 11.33 ± 2.160 μm; Filtek Supreme = 10.66 ± 1.211μm; Admira = 11.16 ± 2.041 μm and Grandio = 10.50 ± 1.224 μm. There were no significant differences among the composite resins obtained with the first (shrinkage stress generated during polymerization) and third method (wall-to-wall shrinkage). The composite resins obtained with the second method (Teflon method) differed significantly regarding gap formation. PMID:19089286

Leaf Shrinkage with Dehydration: Coordination with Hydraulic Vulnerability and Drought Tolerance1[C][W][OPEN

PubMed Central

Scoffoni, Christine; Vuong, Christine; Diep, Steven; Cochard, Hervé; Sack, Lawren

2014-01-01

Leaf shrinkage with dehydration has attracted attention for over 100 years, especially as it becomes visibly extreme during drought. However, little has been known of its correlation with physiology. Computer simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll pathways outside the xylem would cause a strong decline of leaf hydraulic conductance (Kleaf). For 14 diverse species, we tested the hypothesis that shrinkage during dehydration (i.e. in whole leaf, cell and airspace thickness, and leaf area) is associated with reduction in Kleaf at declining leaf water potential (Ψleaf). We tested hypotheses for the linkage of leaf shrinkage with structural and physiological water relations parameters, including modulus of elasticity, osmotic pressure at full turgor, turgor loss point (TLP), and cuticular conductance. Species originating from moist habitats showed substantial shrinkage during dehydration before reaching TLP, in contrast with species originating from dry habitats. Across species, the decline of Kleaf with mild dehydration (i.e. the initial slope of the Kleaf versus Ψleaf curve) correlated with the decline of leaf thickness (the slope of the leaf thickness versus Ψleaf curve), as expected based on predictions from computer simulations. Leaf thickness shrinkage before TLP correlated across species with lower modulus of elasticity and with less negative osmotic pressure at full turgor, as did leaf area shrinkage between full turgor and oven desiccation. These findings point to a role for leaf shrinkage in hydraulic decline during mild dehydration, with potential impacts on drought adaptation for cells and leaves, influencing plant ecological distributions. PMID:24306532

Water transfer properties and shrinkage in lime-based rendering mortars

NASA Astrophysics Data System (ADS)

Arizzi, A.; Cultrone, G.

2012-04-01

aspect to be considered in the evaluation of the decay caused by water is the high shrinkage suffered by renders when they are applied on an extended surface (i.e. a wall), especially when they are aerial lime-based mortars. The shrinkage causes the formation of fissures that become an easy way for water to entry and diffuse through the mortar pore system. This factor is rarely taken into consideration during the hydric assays performed in the laboratory, since mortar samples of 4x4x16 or 4x4x4 cm in size do not undergo to such degree of shrinkage. For this reason, we have also studied the shrinkage of these mortars and considered it in the final assessment of mortars hydric properties. The shrinkage was evaluated according to a non-standardized method, by means of a shrinkage-measuring device that measures the mortar dimensional variations over time. This measurement has shown that the highest the lime content the biggest the mortar shrinkage and, consequently, the strongest the decay due to water.

Periodontal healing in one-wall intra-bony defects in dogs following implantation of autogenous bone or a coral-derived biomaterial.

PubMed

Kim, Chang-Sung; Choi, Seong-Ho; Cho, Kyoo-Sung; Chai, Jung-Kiu; Wikesjö, Ulf M E; Kim, Chong-Kwan

2005-06-01

Autogenous bone grafts and bone biomaterials are being used as part of protocols aiming at reconstruction of periodontal defects. There is a limited biologic information on the effect of such materials on periodontal healing, in particular aberrant healing events that may prevent their general use. The objective of this study was, using histological techniques, to evaluate periodontal healing with focus on root resorption and ankylosis following implantation of autogenous bone and a coral-derived biomaterial into intra-bony defects in dogs. One-wall intra-bony periodontal defects were surgically created at the distal aspect of the second and the mesial aspect of the fourth mandibular premolars in either right or left jaw quadrants in four Beagle dogs. Each animal received particulated autogenous bone and the resorbable calcium carbonate biomaterial into discrete one-wall intra-bony defects. The mucoperiosteal flaps were positioned and sutured to their pre-surgery position. The animals were euthanized 8 weeks post-surgery when block sections of the defect sites were collected and prepared for qualitative histological analysis. There were no significant differences in periodontal healing between sites receiving autograft bone and the coral-derived biomaterial. A well-organized periodontal ligament bridging new bone and cementum regeneration was observed extending coronal to a notch prepared to delineate the apical extent of the defect. Osteoid and bone with enclosed osteocytes were formed onto the surface of both autograft and coral particles. Although small resorption pits were evident in most teeth, importantly none of the biomaterials provoked marked root resorption. Ankylosis was not observed. Particulated autogenous bone and the coral-derived biomaterial may be implanted into periodontal defects without significant healing aberrations such as root resorption and ankylosis. The histopathological evaluation suggests that the autogenous bone graft has a limited

Recrystallization-Induced Surface Cracks of Carbon Ions Irradiated 6H-SiC after Annealing

PubMed Central

Ye, Chao; Ran, Guang; Zhou, Wei; Shen, Qiang; Feng, Qijie; Lin, Jianxin

2017-01-01

Single crystal 6H-SiC wafers with 4° off-axis [0001] orientation were irradiated with carbon ions and then annealed at 900 °C for different time periods. The microstructure and surface morphology of these samples were investigated by grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Ion irradiation induced SiC amorphization, but the surface was smooth and did not have special structures. During the annealing process, the amorphous SiC was recrystallized to form columnar crystals that had a large amount of twin structures. The longer the annealing time was, the greater the amount of recrystallized SiC would be. The recrystallization volume fraction was accorded with the law of the Johnson–Mehl–Avrami equation. The surface morphology consisted of tiny pieces with an average width of approximately 30 nm in the annealed SiC. The volume shrinkage of irradiated SiC layer and the anisotropy of newly born crystals during annealing process produced internal stress and then induced not only a large number of dislocation walls in the non-irradiated layer but also the initiation and propagation of the cracks. The direction of dislocation walls was perpendicular to the growth direction of the columnar crystal. The longer the annealing time was, the larger the length and width of the formed crack would be. A quantitative model of the crack growth was provided to calculate the length and width of the cracks at a given annealing time. PMID:29068408

Recrystallization-Induced Surface Cracks of Carbon Ions Irradiated 6H-SiC after Annealing.

PubMed

Ye, Chao; Ran, Guang; Zhou, Wei; Shen, Qiang; Feng, Qijie; Lin, Jianxin

2017-10-25

Single crystal 6H-SiC wafers with 4° off-axis [0001] orientation were irradiated with carbon ions and then annealed at 900 °C for different time periods. The microstructure and surface morphology of these samples were investigated by grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Ion irradiation induced SiC amorphization, but the surface was smooth and did not have special structures. During the annealing process, the amorphous SiC was recrystallized to form columnar crystals that had a large amount of twin structures. The longer the annealing time was, the greater the amount of recrystallized SiC would be. The recrystallization volume fraction was accorded with the law of the Johnson-Mehl-Avrami equation. The surface morphology consisted of tiny pieces with an average width of approximately 30 nm in the annealed SiC. The volume shrinkage of irradiated SiC layer and the anisotropy of newly born crystals during annealing process produced internal stress and then induced not only a large number of dislocation walls in the non-irradiated layer but also the initiation and propagation of the cracks. The direction of dislocation walls was perpendicular to the growth direction of the columnar crystal. The longer the annealing time was, the larger the length and width of the formed crack would be. A quantitative model of the crack growth was provided to calculate the length and width of the cracks at a given annealing time.

Theoretical Model of the Effect of Crack Tip Blunting on the Ultimate Tensile Strength of Welds in 2219-T87 Aluminum

NASA Technical Reports Server (NTRS)

Beil, R. J.

1982-01-01

A theoretical model representing blunting of a crack tip radius through diffusion of vacancies is presented. The model serves as the basis for a computer program which calculates changes, due to successive weld heat passes, in the ultimate tensile strength of 2219-T81 aluminum. In order for the model to yield changes of the same order in the ultimate tensile strength as that observed experimentally, a crack tip radius of the order of .001 microns is required. Such sharp cracks could arise in the fusion zone of a weld from shrinkage cavities or decohered phase boundaries between dendrites and the eutectic phase, or, possibly, from plastic deformation due to thermal stresses encountered during the welding process. Microstructural observations up to X2000 (resolution of about .1 micron) did not, in the fusion zone, show structural details which changed significantly under the influence of a heat pass, with the exception of possible small changes in the configuration of the interdendritic eutectic and in porosity build-up in the remelt zone.

Fatigue crack tip deformation and fatigue crack propagation

NASA Technical Reports Server (NTRS)

Kang, T. S.; Liu, H. W.

1972-01-01

The effects of stress ratio, prestress cycling and plate thickness on the fatigue crack propagation rate are studied on 2024-T351 aluminum alloy. Fatigue crack propagation rate increases with the plate thickness and the stress ratio. Prestress cycling below the static yield strength has no noticeable effect on the fatigue crack propagation rate. However, prestress cycling above the static yield strength causes the material to strain harden and increases the fatigue crack propagation rate. Crack tip deformation is used to study the fatigue crack propagation. The crack tip strains and the crack opening displacements were measured from moire fringe patterns. The moire fringe patterns were obtained by a double exposure technique, using a very high density master grille (13,400 lines per inch).

The influence of collagen membrane and autogenous bone chips on bone augmentation in the anterior maxilla: a preclinical study.

PubMed

Janner, Simone F M; Bosshardt, Dieter D; Cochran, David L; Chappuis, Vivianne; Huynh-Ba, Guy; Jones, Archie A; Buser, Daniel

2017-11-01

To evaluate the effect of a resorbable collagen membrane and autogenous bone chips combined with deproteinized bovine bone mineral (DBBM) on the healing of buccal dehiscence-type defects. The second incisors and the first premolars were extracted in the maxilla of eight mongrels. Reduced diameter, bone-level implants were placed 5 weeks later. Standardized buccal dehiscence-type defects were created and grafted at implant surgery. According to an allocation algorithm, the graft composition of each of the four maxillary sites was DBBM + membrane (group D + M), autogenous bone chips + DBBM + membrane (group A + D + M), DBBM alone (group D) or autogenous bone chips + DBBM (group A + D). Four animals were sacrificed after 3 weeks of healing and four animals after 12 weeks. Histological and histomorphometric analyses were performed on oro-facial sections. The pattern of bone formation and resorption within the grafted area showed high variability among the same group and healing time. The histomorphometric analysis of the 3-week specimens showed a positive effect of autogenous bone chips on both implant osseointegration and bone formation into the grafted region (P < 0.05). The presence of the collagen membrane correlated with greater bone formation around the DBBM particles and greater bone formation in the grafted region after 12 weeks of healing (P < 0.05). The oro-facial width of the augmented region at the level of the implant shoulder was significantly reduced in cases where damage of the protection splints occurred in the first week of healing (P < 0.05). The addition of autogenous bone chips and the presence of the collagen membrane increased bone formation around DBBM particles. Wound protection from mechanical noxa during early healing may be critical for bone formation within the grafted area. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Advanced shrink material for NTD process with lower Y/X shrinkage bias of elongated patterns

NASA Astrophysics Data System (ADS)

Miyamoto, Yoshihiro; Sekito, Takashi; Sagan, John; Horiba, Yuko; Kinuta, Takafumi; Nagahara, Tatsuro; Tarutani, Shinji

2015-03-01

Negative tone shrink materials (NSM) suitable for resolution enhancement of negative tone development (NTD) 193nm immersion resists have been developed. While this technology is being expanded to integrated circuits (IC) manufacturing, there still have two major problems to apply various processes. One of them is shrink ID bias which means shrink differences between isolated (I) and dense (D) CDs, and the other one is Y/X shrinkage bias which means shrinkage differences between major axis (Y) and minor axis (X) of the elongated or oval shape pattern. While we have presented the improvement of shrink ID bias at SPIE2014 [1], the reduction of Y/X shrinkage bias was the examination theme for quite some time. In this paper, we present Y/X shrinkage bias of current NTD shrink material, new concept material for Y/X bias reduction and the result of new shrink material. Current NTD shrink model has Y/X bias of 1.6 (Y shrink=16nm) at a mixing bake (MB) of 150°C on AZ AX2110P NTD elongated pattern of X=70nm and Y=210nm ADI. This means shrinkage of Y has larger shrinkage than X and that makes difficult to apply shrink material. We expected that the characteristic shape of elongated pattern was one of the root-cause for Y/X bias, and then simulated how to achieve equivalent shrinkage at Y and X. We concluded that available resist volume per each Y and X unit was not equivalent and need new shrink concept to solve Y/X bias. Based on our new concept, we prepared new shrink material which has lower Y/X bias and larger shrink amount compared with current NTD shrink material. Finally we have achieved lower Y/X bias from 1.6 to 1.1 at MB150°C and moreover got higher shrinkage than current NTD shrink material from 10.1nm to 16.7nm.

Comparison of autogenous cancellous bone grafting and extracorporeal shock wave therapy on osteotomy healing in the tibial tuberosity advancement procedure in dogs. Radiographic densitometric evaluation.

PubMed

Barnes, K; Lanz, O; Werre, S; Clapp, K; Gilley, R

2015-01-01

To compare optical values in the osteotomy gap created after a tibial tuberosity advancement (TTA) treated with autogenous cancellous bone graft, extracorporeal shock wave therapy, a combination of autogenous cancellous bone graft and extracorporeal shock wave therapy, and absence of both autogenous cancellous bone graft and extracorporeal shock wave therapy using densitometry. Dogs that were presented for surgical repair of a cranial cruciate ligament rupture were randomly assigned to one of four groups: TTA with autogenous cancellous bone graft (TTA-G), TTA with autogenous cancellous bone graft and extracorporeal shock wave therapy (TTA-GS), TTA with extracorporeal shock wave therapy (TTA-S), and TTA with no additional therapy (TTA-O). Mediolateral radiographs at zero, four and eight weeks after surgery were evaluated to compare healing of the osteotomy gap via densitometry. An analysis of variance was used to compare the densitometric values between groups. At four weeks after surgery, a significant difference in osteotomy gap density was noted between TTA-GS (8.4 millimetres of aluminium equivalent [mmAleq]) and TTA-S (6.1 mmAleq), and between TTA-GS (8.4 mmAleq) and TTA-O (6.4 mmAleq). There were no significant differences noted between any groups at the eight week re-evaluation. There were no significant differences in the osteotomy gap density at eight weeks after surgery regardless of the treatment modality used. The combination of autogenous cancellous bone graft and extracorporeal shock wave therapy may lead to increased radiographic density of the osteotomy gap in the first four weeks after surgery. Densitometry using an aluminium step wedge is a feasible method for comparison of bone density after TTA in dogs.

Modified creep and shrinkage prediction model B3 for serviceability limit state analysis of composite slabs

NASA Astrophysics Data System (ADS)

Gholamhoseini, Alireza

2016-03-01

Relatively little research has been reported on the time-dependent in-service behavior of composite concrete slabs with profiled steel decking as permanent formwork and little guidance is available for calculating long-term deflections. The drying shrinkage profile through the thickness of a composite slab is greatly affected by the impermeable steel deck at the slab soffit, and this has only recently been quantified. This paper presents the results of long-term laboratory tests on composite slabs subjected to both drying shrinkage and sustained loads. Based on laboratory measurements, a design model for the shrinkage strain profile through the thickness of a slab is proposed. The design model is based on some modifications to an existing creep and shrinkage prediction model B3. In addition, an analytical model is developed to calculate the time-dependent deflection of composite slabs taking into account the time-dependent effects of creep and shrinkage. The calculated deflections are shown to be in good agreement with the experimental measurements.

Tracheal reconstruction with autogenous jejunal microsurgical transfer.

PubMed

Jones, R E; Morgan, R F; Marcella, K L; Mills, S E; Kron, I L

1986-06-01

Tracheal defects due to stricture formation, tracheomalacia, and neoplasms can present difficult reconstructive problems. Tracheal defects were surgically created in 6 dogs and primarily reconstructed with microsurgical free tissue transfer of autogenous jejunal segments. Primary healing was accomplished in all dogs without severe air leakage or infection. Bronchoscopy demonstrated no substantial secretions or tracheal narrowing. Gross pathological examination of the trachea revealed no evidence of tracheal disruption or infection. Direct measurements revealed no major tracheal narrowing. Microscopic examination demonstrated normal jejunal mucosa with a minimal amount of inflammatory change at the margins of the reconstruction at 6 weeks. Microvascular free tissue transfer of jejunal segments to correct cervical tracheal defects can readily be accomplished with excellent healing and maintenance of the tracheal lumen in dogs.

[Miniplate internal fixation and autogenous iliac bone graft in surgical treatment of old metatarsal fractures].

PubMed

Pan, Hao; Yu, Guangrong; Xiong, Wen; Zhao, Zhiming; Ding, Fan; Zheng, Qiong; Kan, Wushen

2011-07-01

To summarize the experience of treating old metatarsal fractures with surgery methods of miniplate internal fixation and autogenous iliac bone. Between May 2009 and July 2010, 7 patients with old metatarsal fractures were treated surgically, including 5 multi-metatarsal fractures and 2 single metatarsal fractures. There were 5 males and 2 females aged from 25 to 43 years (mean, 33 years). The time from fracture to operation was 4-12 weeks. The X-ray films showed that a small amount of callus formed at both broken ends with shortening, angulation, or rotation displacement. The surgical treatments included open reduction, internal fixation by miniplate, and autogenous iliac bone graft (1.5-2.5 cm(3)). The external plaster fixation was used in all patients for 4 to 6 weeks postoperatively (mean, 5 weeks). All incisions healed by first intention. The 7 patients were followed up 8-18 months (mean, 13.5 months). The clinical fracture healing time was 6 to 12 weeks postoperatively (mean, 8.4 weeks). No pain of planta pedis occurred while standing and walking. The American Orthopaedic Foot and Ankle Society (AOFAS) mesopedes and propodium score was 75-96 (mean, 86.4). It has the advantages of reliable internal fixation, high fracture healing rate, less complications to treat old metatarsal fractures with surgery methods of miniplate internal fixation and autogenous iliac bone graft, so it is an effective treatment method.

[Preliminary result of allogenic bone and autogeneic-iliac bone in comminuted fracture reparation in rabbits].

PubMed

Wang, Zhi-qiang; Li, Qi-jia; Wang, Qi

2002-11-01

To observe the difference of the fracture reparation using autogeneic-iliac bone and allogenic bone. Comminuted fracture of humerus in two sides were made in rabbits. Autogeneic-iliac bone was implanted in one side, while allogenic bone of equal capacity was implanted in the other side. General observation, X-ray, and HE histologic section were done when the rabbits were put to death in different stages. One week after implantation, the graft had been enclosed by connective tissue without infiltration of the inflammatory cells. At the 2nd week, the graft had been enclosed in osteoplastic granulation tissue, and the cartilage callus had formed. At the 3rd week, there had been broken sequestrum among the callus; the cartilage had actively formed the bone; and the medulla had been making. At the 4th week, the sequestrum had disappeared, and the mature callus had appeared; the osteoblasts had arranged in a line around the edge of the mature callus. At the 5th week, the callus was strong, compact and approached mature bones. At the 6th week, there had been the compact lamellar structures and the complete haversian's systems. There was no significant difference between callus of two sides by using image quantitative analysis in the 3rd, 4th week (P > 0.05). The allogenic bone has good histocompatibility and bone conduction effect, and can be used for bone transplantation substitute with autogenous-iliac bone.

[Fusion of reconstructed titanic plate, vertebral pedical screws and autogenous granulated cancellous bone graft in posterior occipitocervical region].

PubMed

Zhong, Dejun; Song, Yueming

2006-08-01

To explore the technique of fusing the reconstructed titanic plate, the C2 pedical screws, and the autogenous granulated cancellous bone graft in the occipitocervical region. From April 2002 to January 2005, 19 patients aged 31-67 years with occipitocervical instability underwent the occipitocervical fusion using the reconstructed plate, C2 pedical screws, and autogenous granulated cancellous bone graft. Of the patients, 8 had complex occipitocervical deformity, 8 had old atlantoaxial fracture and dislocation, 2 had rheumatoid arthritis and anterior dislocation of the atlantoaxial joint, and 1 had cancer of the deltoid process of the axis. No complication occurred during and after operation. The follow-up for an average of 16 months in 19 patients showed that all the patients achieved solid bony fusion in the occipitocervical region. There was no broken plate, broken screw, looseness of the internal fixation or neurovascular injury. The fixation of the C2 pedical screws with the reconstructed titanic plate is reliable, the insertion is easy, and the autogenous granulated cancellous bone graft has a high fusion rate, thus resulting in a satisfactory effect in the occipitocervical fusion.

Four-Phase Dendritic Model for the Prediction of Macrosegregation, Shrinkage Cavity, and Porosity in a 55-Ton Ingot

NASA Astrophysics Data System (ADS)

Ge, Honghao; Ren, Fengli; Li, Jun; Han, Xiujun; Xia, Mingxu; Li, Jianguo

2017-03-01

A four-phase dendritic model was developed to predict the macrosegregation, shrinkage cavity, and porosity during solidification. In this four-phase dendritic model, some important factors, including dendritic structure for equiaxed crystals, melt convection, crystals sedimentation, nucleation, growth, and shrinkage of solidified phases, were taken into consideration. Furthermore, in this four-phase dendritic model, a modified shrinkage criterion was established to predict shrinkage porosity (microporosity) of a 55-ton industrial Fe-3.3 wt pct C ingot. The predicted macrosegregation pattern and shrinkage cavity shape are in a good agreement with experimental results. The shrinkage cavity has a significant effect on the formation of positive segregation in hot top region, which generally forms during the last stage of ingot casting. The dendritic equiaxed grains also play an important role on the formation of A-segregation. A three-dimensional laminar structure of A-segregation in industrial ingot was, for the first time, predicted by using a 3D case simulation.

Early prophylactic autogenous bone grafting in type III open tibial fractures.

PubMed

Kesemenli, Cumhur C; Kapukaya, Ahmet; Subaşi, Mehmet; Arslan, Huseyin; Necmioğlu, Serdar; Kayikçi, Cuma

2004-08-01

The authors report the results achieved in patients with type III open tibial fractures who underwent primary autogenous bone grafting at the time of debridement and skeletal stabilisation. Twenty patients with a mean age of 35.8 years (range, 24-55) were treated between 1996 and 1999. Eight fractures were type IIIA, 11 were type IIIB, and 1 was type IIIC. At the index procedure, wound debridement, external fixation and autogenous bone grafting with bone coverage were achieved. The mean follow-up period was 46 months (range, 34-55). The mean time to fixator removal was 21 weeks (range, 14-35), and the mean time to union was 28 weeks (range, 19-45). Skin coverage was achieved by a myocutaneous flap in 2 patients, late primary closure in 4, and split skin grafting in 14. One (5%) of the patients experienced delayed union, and 1 (5%) developed infection. In tibial type III open fractures, skin coverage may be delayed, using the surrounding soft tissue to cover any exposed bone after thorough débridement and wound cleansing. Primary prophylactic bone grafting performed at the same time reduces the rate of delayed union, shortens the time to union, and does not increase the infection rate.

Autogenous bone particle/titanium fiber composites for bone regeneration in a rabbit radius critical-size defect model.

PubMed

Xie, Huanxin; Ji, Ye; Tian, Qi; Wang, Xintao; Zhang, Nan; Zhang, Yicai; Xu, Jun; Wang, Nanxiang; Yan, Jinglong

2017-11-01

To explore the effects of autogenous bone particle/titanium fiber composites on repairing segmental bone defects in rabbits. A model of bilateral radial bone defect was established in 36 New Zealand white rabbits which were randomly divided into 3 groups according to filling materials used for bilaterally defect treatment: in group C, 9 animal bone defect areas were prepared into simple bilateral radius bone defect (empty sham) as the control group; 27 rabbits were used in groups ABP and ABP-Ti. In group ABP, left defects were simply implanted with autogenous bone particles; meanwhile, group ABP-Ti animals had right defects implanted with autogenous bone particle/titanium fiber composites. Animals were sacrificed at 4, 8, and 12 weeks, respectively, after operation. Micro-CT showed that group C could not complete bone regeneration. Bone volume to tissue volume values in group ABP-Ti were better than group ABP. From histology and histomorphometry Groups ABP and ABP-Ti achieved bone repair, the bone formation of group ABP-Ti was better. The mechanical strength of group ABP-Ti was superior to that of other groups. These results confirmed the effectiveness of autologous bone particle/titanium fiber composites for promoting bone regeneration and mechanical strength.

Effects of Prepolymerized Particle Size and Polymerization Kinetics on Volumetric Shrinkage of Dental Modeling Resins

PubMed Central

Ha, Jung-Yun; Chun, Ju-Na; Son, Jun Sik; Kim, Kyo-Han

2014-01-01

Dental modeling resins have been developed for use in areas where highly precise resin structures are needed. The manufacturers claim that these polymethyl methacrylate/methyl methacrylate (PMMA/MMA) resins show little or no shrinkage after polymerization. This study examined the polymerization shrinkage of five dental modeling resins as well as one temporary PMMA/MMA resin (control). The morphology and the particle size of the prepolymerized PMMA powders were investigated by scanning electron microscopy and laser diffraction particle size analysis, respectively. Linear polymerization shrinkage strains of the resins were monitored for 20 minutes using a custom-made linometer, and the final values (at 20 minutes) were converted into volumetric shrinkages. The final volumetric shrinkage values for the modeling resins were statistically similar (P > 0.05) or significantly larger (P < 0.05) than that of the control resin and were related to the polymerization kinetics (P < 0.05) rather than the PMMA bead size (P = 0.335). Therefore, the optimal control of the polymerization kinetics seems to be more important for producing high-precision resin structures rather than the use of dental modeling resins. PMID:24779020

Monitoring of self-healing phenomena towards enhanced sustainability of historic mortars

NASA Astrophysics Data System (ADS)

Amenta, M.; Karatasios, I.; Maravelaki, P.; Kilikoglou, V.

2016-05-01

Mortars are known for their ability to heal their defects in an autogenic way. This phenomenon is expressed by the filling of microcracks by secondary products, restoring or enhancing the material's performance. Parameterization of self-healing phenomenon could be a key factor for the enhanced sustainability of these materials in terms of reduced repair cost and consumption of natural raw materials and thus reduced environmental fingerprint. The fact that this phenomenon takes place autogenously suggests that the material can self-repair its defects, without external intervention, thus leading to a prolonged life cycle. In the present study, the autogenic self-healing phenomenon was studied in natural hydraulic lime mortars, considering aspects of curing time before initial cracking, duration and conditions of the healing period. Furthermore, strength recovery due to autogenic self-healing was measured under high humidity conditions, and thermo-gravimetric analysis (DTA/TG) was performed in all specimens in order to quantitatively assess the available unreacted components in the binder at all ages. Regarding the microstructure of the healing phases, the main products formed during healing consist of calcite and various C-S-H/C-A-H phases. Depending on the parameters mentioned above, there is a wide diversity in the intensity, typology and topography of the secondary phases inside the cracks. The main differences discussed were observed between specimens cracked at very early age and those damaged after 30 days of curing. Similarly, the mechanical properties of the crack-healed specimens were associated with the above findings and especially with the available each-time amount of lime, determined by thermo-gravimetric analysis.

[Use of supportive autogenic training in multiple morbidity in geriatric psychiatry patients].

PubMed

Kircher, T; Stetter, F; Wormstall, H

1997-01-01

23 multimorbid, geronto-psychiatric patients, aged 60 years or older, participated in a "supportive" course of autogenic training according to Schultz. Participating in the course an average of 7 +/- 3 weeks, 17 (76%) of the subjects were able to learn the training. In general, subjects reported a better general condition after the training sessions, measured with visual analogue scales (p < 0.001). The psychopathological status improved significantly during the time of the course (BPRS: p < 0.001; GDS: p < 0.001). No significant change was found in the cognitive state (MMSE) and the statements on the "list of complaints" ("Beschwerdenliste"). The global training success was better in the psychopathological less affected than in the more severely ill (BPRS prior r = 0.64, p = 0.001, GDS prior r = 0.46, p < 0.05). No correlation was found between training success and age, number of somatic diseases, number of medication, MMSE and the "Beschwerdenliste". Autogenic training is a useful component in psychotherapeutic and psychiatric therapy for elderly multimorbid in- and outpatients. A half-open group, two therapy sessions per week, reciting the training formulae aloud, a structured, simple setting and co-therapists proved to be worthwhile.

Combined Use of Shrinkage Reducing Admixture and CaO in Cement Based Materials

NASA Astrophysics Data System (ADS)

Tittarelli, Francesca; Giosuè, Chiara; Monosi, Saveria

2017-10-01

The combined addition of a Shrinkage-Reducing Admixture (SRA) with a CaO-based expansive agent (CaO) has been found to have a synergistic effect to improve the dimensional stability of cement based materials. In this work, aimed to further investigate the effect, mortar and self-compacting concrete specimens were prepared either without admixtures, as reference, or with SRA alone and/or CaO. Their performance was compared in terms of compressive strength and free shrinkage measurements. Results showed that the synergistic effect in reducing shrinkage is confirmed in the specimens manufactured with SRA and CaO. In order to clarify this phenomenon, the effect of SRA on the hydration of CaO as well as cement was evaluated through different techniques. The obtained results show that SRA induces a finer microstructure of the CaO hydration products and a retarding effect on the microstructure development of cement based materials. A more deformable mortar or concrete, due to the delay in microstructure development by SRA, coupled with a finer microstructure of CaO hydration products could allow higher early expansion, which might contribute in contrasting better the successive drying shrinkage.

Influence of the shape of the layers in photo-cured dental restorations on the shrinkage stress peaks-FEM study.

PubMed

Kowalczyk, Piotr

2009-12-01

The aim of the paper is to analyse an influence of the shape of the layers in photo-cured dental restorations of Class I on distribution of shrinkage stresses along the tooth-restoration interface. The study is a continuation of the previous considerations (Kowalczyk and Gambin (2008) [1]), where techniques, which reduce stress concentration at the top of the tooth-restoration interface, were considered. The analysis leads to proposition of new layer forming techniques, which diminish the stress peaks at the interface and prevent the crack propagation process. To find the stress distributions in the dental restoration layers and the tooth tissues the finite element method implemented in the ABAQUS (Simulia, Providence, USA) software is used. For Class I restoration of the premolar tooth, the axisymmetrical model is assumed. The restoration is made of four layers of a photo-cured composite. Between the tooth tissues and the restoration, a layer of bonding agent 0.01mm thick is placed and modeled by FEM with help of the cohesive elements. The assumed model takes into account an influence of changes of elastic properties and viscous effects. For each case of the restoration layers system, the Huber-Mises stresses are analysed. The investigations show that the stresses near the restoration-tooth tissue interface are reduced due to viscous flow of the cured material and due to existence of a thin layer of the bonding agent. However, the stress distribution both, in the restoration and in the tooth tissues, is strongly dependent on a shape of the filling layers. Numerical simulations disclose that stress peaks are located at the top corners of each layer. The top corners of the last layer are the places where microleakage may occur. Stress concentrations at the corners of the preceding layers may lead to a growth of uprising crack. It will be shown that the flat layers in the restoration create relatively high values of the stress peaks. The rounded layers, with shapes

Experimental evaluation and simulation of volumetric shrinkage and warpage on polymeric composite reinforced with short natural fibers

NASA Astrophysics Data System (ADS)

Santos, Jonnathan D.; Fajardo, Jorge I.; Cuji, Alvaro R.; García, Jaime A.; Garzón, Luis E.; López, Luis M.

2015-09-01

A polymeric natural fiber-reinforced composite is developed by extrusion and injection molding process. The shrinkage and warpage of high-density polyethylene reinforced with short natural fibers of Guadua angustifolia Kunth are analyzed by experimental measurements and computer simulations. Autodesk Moldflow® and Solid Works® are employed to simulate both volumetric shrinkage and warpage of injected parts at different configurations: 0 wt.%, 20 wt.%, 30 wt.% and 40 wt.% reinforcing on shrinkage and warpage behavior of polymer composite. Become evident the restrictive effect of reinforcing on the volumetric shrinkage and warpage of injected parts. The results indicate that volumetric shrinkage of natural composite is reduced up to 58% with fiber increasing, whereas the warpage shows a reduction form 79% to 86% with major fiber content. These results suggest that it is a highly beneficial use of natural fibers to improve the assembly properties of polymeric natural fiber-reinforced composites.

Combined use of autogenic therapy and biofeedback in training effective control of heart rate by humans

NASA Technical Reports Server (NTRS)

Cowings, P. S.

1977-01-01

Experiments were performed on 24 men and women (aged 20-27 yr) in three equal groups who were taught to control their own heart rates by autogenic training and biofeedback under dark and sound-isolated conditions. Group I was parasympathetic dominant, group II was sympathetic dominant, and group III consisted of parasympathetic-dominant subjects and controls who received only biofeedback of their own heart rates. The results corroborate three hypotheses: (1) subjects with para-sympathetic-dominant autonomic profiles perform in a way that is both qualitatively and quantitatively different from subjects with sympathetic-dominant autonomic profiles; (2) tests of interindividual variability yield data relevant to individual performance in visceral learning tasks; and (3) the combined use of autogenic training, biofeedback, and verbal feedback is suitable for conditioning large stable autonomic responses in humans.

Control of polymerization shrinkage and stress in nanogel-modified monomer and composite materials

PubMed Central

Moraes, Rafael R.; Garcia, Jeffrey W.; Barros, Matthew D.; Lewis, Steven H.; Pfeifer, Carmem S.; Liu, JianCheng; Stansbury, Jeffrey W.

2011-01-01

Objectives This study demonstrates the effects of nano-scale prepolymer particles as additives to model dental monomer and composite formulations. Methods Discrete nanogel particles were prepared by solution photopolymerization of isobornyl methacrylate and urethane dimethacrylate in the presence of a chain transfer agent, which also provided a means to attach reactive groups to the prepolymer. Nanogel was added to triethylene glycol dimethacrylate (TEGDMA) in increments between 5 and 40 wt% with resin viscosity, reaction kinetics, shrinkage, mechanical properties, stress and optical properties evaluated. Maximum loading of barium glass filler was determined as a function of nanogel content and composites with varied nanogel content but uniform filler loading were compared in terms of consistency, conversion, shrinkage and mechanical properties. Results High conversion, high molecular weight internally crosslinked and cyclized nanogel prepolymer was efficiently prepared and redispersed into TEGDMA with an exponential rise in viscosity accompanying nanogel content. Nanogel addition at any level produced no deleterious effects on reaction kinetics, conversion or mechanical properties, as long as reactive nanogels were used. A reduction in polymerization shrinkage and stress was achieved in proportion to nanogel content. Even at high nanogel concentrations, the maximum loading of glass filler was only marginally reduced relative to the control and high strength composite materials with low shrinkage were obtained. Significance The use of reactive nanogels offers a versatile platform from which resin and composite handling properties can be adjusted while the polymerization shrinkage and stress development that challenge the adhesive bonding of dental restoratives are controllably reduced. PMID:21388669

Control of polymerization shrinkage and stress in nanogel-modified monomer and composite materials.

PubMed

Moraes, Rafael R; Garcia, Jeffrey W; Barros, Matthew D; Lewis, Steven H; Pfeifer, Carmem S; Liu, JianCheng; Stansbury, Jeffrey W

2011-06-01

This study demonstrates the effects of nano-scale prepolymer particles as additives to model dental monomer and composite formulations. Discrete nanogel particles were prepared by solution photopolymerization of isobornyl methacrylate and urethane dimethacrylate in the presence of a chain transfer agent, which also provided a means to attach reactive groups to the prepolymer. Nanogel was added to triethylene glycol dimethacrylate (TEGDMA) in increments between 5 and 40 wt% with resin viscosity, reaction kinetics, shrinkage, mechanical properties, stress and optical properties evaluated. Maximum loading of barium glass filler was determined as a function of nanogel content and composites with varied nanogel content but uniform filler loading were compared in terms of consistency, conversion, shrinkage and mechanical properties. High conversion, high molecular weight internally crosslinked and cyclized nanogel prepolymer was efficiently prepared and redispersed into TEGDMA with an exponential rise in viscosity accompanying nanogel content. Nanogel addition at any level produced no deleterious effects on reaction kinetics, conversion or mechanical properties, as long as reactive nanogels were used. A reduction in polymerization shrinkage and stress was achieved in proportion to nanogel content. Even at high nanogel concentrations, the maximum loading of glass filler was only marginally reduced relative to the control and high strength composite materials with low shrinkage were obtained. The use of reactive nanogels offers a versatile platform from which resin and composite handling properties can be adjusted while the polymerization shrinkage and stress development that challenge the adhesive bonding of dental restoratives are controllably reduced. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Cryogenic Autogenous Pressurization Testing for Robotic Refueling Mission 3

NASA Technical Reports Server (NTRS)

Boyle, R.; DiPirro, M.; Tuttle, J.; Francis, J.; Mustafi, S.; Li, X.; Barfknecht, P.; DeLee, C. H.; McGuire, J.

2015-01-01

A wick-heater system has been selected for use to pressurize the Source Dewar of the Robotic Refueling Mission Phase 3 on-orbit cryogen transfer experiment payload for the International Space Station. Experimental results of autogenous pressurization of liquid argon and liquid nitrogen using a prototype wick-heater system are presented. The wick-heater generates gas to increase the pressure in the tank while maintaining a low bulk fluid temperature. Pressurization experiments were performed in 2013 to characterize the performance of the wick heater. This paper describes the experimental setup, pressurization results, and analytical model correlations.

New System of Shrinkage Measurement through Cement Mortars Drying

PubMed Central

Morón, Carlos; Saiz, Pablo; Ferrández, Daniel; García-Fuentevilla, Luisa

2017-01-01

Cement mortar is used as a conglomerate in the majority of construction work. There are multiple variants of cement according to the type of aggregate used in its fabrication. One of the major problems that occurs while working with this type of material is the excessive loss of moisture during cement hydration (setting and hardening), known as shrinkage, which provokes a great number of construction pathologies that are difficult to repair. In this way, the design of a new sensor able to measure the moisture loss of mortars at different age levels is useful to establish long-term predictions concerning mortar mass volume loss. The purpose of this research is the design and fabrication of a new capacitive sensor able to measure the moisture of mortars and to relate it with the shrinkage. PMID:28272297

Mechanism for Angular Deformation of L-shaped Specimens —Influence of Filling Material and Shrinkage Factor—

NASA Astrophysics Data System (ADS)

Furuhashi, Hiroshi; Aoki, Takerou; Okabe, Sayaka; Arai, Tsuyoshi; Seto, Masahiro; Yamabe, Masashi

L-shape is the important and fundamental shape for injection molded parts. Therefore to reveal the corner angular deformation mechanism of this shape is also valuable for understanding the warpage mechanism of injection molded parts. In this study, we investigated the influence of the filling materials (fiber, talc and not filled) and two kinds of anisotropic shrinkage factors, solidification shrinkage and shrinkage caused by thermal expansion coefficient during cooling, to the angular deformation of L-shaped specimens and the following conclusions were obtained 1) The anisotropic solidification shrinkage of MD/TD and the anisotropic thermal expansion coefficient of MD/TD are considered to cause the angular deformation of L-shaped specimens. But the contribution ratios of these two anisotropies depend on the filling material for plastics. 2) The angular deformation of PP and PBT filled with glass fiber is mainly caused by the anisotropic thermal expansion coefficient and on the other hand, that of PP and PBT without filling material is caused by anisotropic solidification shrinkage. However both anisotropies cause the angular deformation of PP filled with talc. 3) The plate thickness dependence of the angular deformation of PP filled with talc is the singular peculiar phenomenon. The plate thickness dependence of anisotropic solidification shrinkage of this material (it is also singular) is considered to have an important influence on this phenomenon.

Glacier shrinkage driving global changes in downstream systems.

PubMed

Milner, Alexander M; Khamis, Kieran; Battin, Tom J; Brittain, John E; Barrand, Nicholas E; Füreder, Leopold; Cauvy-Fraunié, Sophie; Gíslason, Gísli Már; Jacobsen, Dean; Hannah, David M; Hodson, Andrew J; Hood, Eran; Lencioni, Valeria; Ólafsson, Jón S; Robinson, Christopher T; Tranter, Martyn; Brown, Lee E

2017-09-12

Glaciers cover ∼10% of the Earth's land surface, but they are shrinking rapidly across most parts of the world, leading to cascading impacts on downstream systems. Glaciers impart unique footprints on river flow at times when other water sources are low. Changes in river hydrology and morphology caused by climate-induced glacier loss are projected to be the greatest of any hydrological system, with major implications for riverine and near-shore marine environments. Here, we synthesize current evidence of how glacier shrinkage will alter hydrological regimes, sediment transport, and biogeochemical and contaminant fluxes from rivers to oceans. This will profoundly influence the natural environment, including many facets of biodiversity, and the ecosystem services that glacier-fed rivers provide to humans, particularly provision of water for agriculture, hydropower, and consumption. We conclude that human society must plan adaptation and mitigation measures for the full breadth of impacts in all affected regions caused by glacier shrinkage.

Glacier shrinkage driving global changes in downstream systems

PubMed Central

Khamis, Kieran; Battin, Tom J.; Brittain, John E.; Barrand, Nicholas E.; Füreder, Leopold; Cauvy-Fraunié, Sophie; Gíslason, Gísli Már; Jacobsen, Dean; Hannah, David M.; Hodson, Andrew J.; Hood, Eran; Lencioni, Valeria; Ólafsson, Jón S.; Robinson, Christopher T.; Tranter, Martyn; Brown, Lee E.

2017-01-01

Glaciers cover ∼10% of the Earth’s land surface, but they are shrinking rapidly across most parts of the world, leading to cascading impacts on downstream systems. Glaciers impart unique footprints on river flow at times when other water sources are low. Changes in river hydrology and morphology caused by climate-induced glacier loss are projected to be the greatest of any hydrological system, with major implications for riverine and near-shore marine environments. Here, we synthesize current evidence of how glacier shrinkage will alter hydrological regimes, sediment transport, and biogeochemical and contaminant fluxes from rivers to oceans. This will profoundly influence the natural environment, including many facets of biodiversity, and the ecosystem services that glacier-fed rivers provide to humans, particularly provision of water for agriculture, hydropower, and consumption. We conclude that human society must plan adaptation and mitigation measures for the full breadth of impacts in all affected regions caused by glacier shrinkage. PMID:28874558

Shrinkage vectors of a flowable composite in artificial cavity models with different boundary conditions: Ceramic and Teflon.

PubMed

Kaisarly, Dalia; El Gezawi, Moataz; Xu, Xiaohui; Rösch, Peter; Kunzelmann, Karl-Heinz

2018-01-01

Polymerization shrinkage of dental resin composites leads to stress build-up at the tooth-restoration interface that predisposes the restoration to debonding. In contrast to the heterogeneity of enamel and dentin, this study investigated the effect of boundary conditions in artificial cavity models such as ceramic and Teflon. Ceramic serves as a homogenous substrate that provides optimal bonding conditions, which we presented in the form of etched and silanized ceramic in addition to an etched, silanized and bonded ceramic cavity. In contrast, the Teflon cavity presented a non-adhesive boundary condition that provided an exaggerated condition of poor bonding as in the case of contamination during the application procedure or a poor bonding substrate such as sclerotic or deep dentin. The greatest 3D shrinkage vectors and movement in the axial direction were observed in the ceramic cavity with the bonding agent followed by the silanized ceramic cavity, and smallest shrinkage vectors and axial movements were observed in the Teflon cavity. The shrinkage vectors in the ceramic cavities exhibited downward movement toward the cavity bottom with great downward shrinkage of the free surface. The shrinkage vectors in the Teflon cavity pointed towards the center of the restoration with lateral movement greater at one side denoting the site of first detachment from the cavity walls. These results proved that the boundary conditions, in terms of bonding substrates, significantly influenced the shrinkage direction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Measurement of early age shrinkage of Virginia concrete mixtures.

DOT National Transportation Integrated Search

2008-01-01

Concrete volume changes throughout its service life. The total in-service volume change is the resultant of applied loads and shrinkage. When loaded, concrete undergoes an instantaneous elastic deformation and a slow inelastic deformation called cree...

Autogenic Training and Hand Temperature Biofeedback in the Treatment of Migraine: A Preliminary Analysis.

ERIC Educational Resources Information Center

Jessup, B.; And Others

The possibility of alleviating migraine headaches by autogenic relaxation training, with or without hand temperature biofeedback, was assessed. The study examined five independent groups in a bi-directional control group design. Volunteer migraine sufferers served as subjects, each participating for 12 weeks. The first four weeks of the study were…

Autogenic Feedback Training (Body FORTRAN) for Musically Gifted Students at Bonita Vista High School.

ERIC Educational Resources Information Center

Lane, John M.

1982-01-01

The Gifted Self-Understanding Assessment Battery (GSAB) was given to 34 (27 females, 7 males) music students (aged 15-17) at Bonita Vista High School in Chula Vista (California). Biofeedback training and assessment were followed by individual counseling for Autogenic Feedback Training (AFT) to achieve improvement of the individual's own well…

Development and construction of low-cracking high-performance concrete (LC-HPC) bridge decks : free shrinkage, moisture optimization and concrete production : final report.

DOT National Transportation Integrated Search

2009-08-01

The development and evaluation of low-cracking high-performance concrete (LC-HPC) for use in bridge decks : is described based on laboratory test results and experience gained during the construction of 14 bridges. This report : emphasizes the materi...

Development and construction of low-cracking high-performance concrete (LC-HPC) bridge decks : free shrinkage, moisture optimization and concrete production : summary report.

DOT National Transportation Integrated Search

2009-08-01

The development and evaluation of low-cracking high-performance concrete (LC-HPC) for use in bridge decks : is described based on laboratory test results and experience gained during the construction of 14 bridges. This report : emphasizes the materi...

Effect of a weightlifting belt on spinal shrinkage.

PubMed

Bourne, N D; Reilly, T

1991-12-01

Spinal loading during weightlifting results in a loss of stature which has been attributed to a decrease in height of the intervertebral discs--so-called 'spinal shrinkage'. Belts are often used during the lifting of heavy weights, purportedly to support, stabilize and thereby attenuate the load on the spine. The purpose of this study was to examine the effects of a standard weightlifting belt in attenuating spinal shrinkage. Eight male subjects with a mean age of 24.8 years performed two sequences of circuit weight-training, one without a belt and on a separate occasion with a belt. The circuit training regimen consisted of six common weight-training exercises. These were performed in three sets of ten with a change of exercise after each set of ten repetitions. A stadiometer sensitive to within 0.01 mm was used to record alterations in stature. Measurements of stature were taken before and after completion of the circuit. The absolute visual analogue scale (AVAS) was used to measure the discomfort and pain intensity resulting from each of the two conditions. The circuit weight-training caused stature losses of 3.59mm without the belt and 2.87 mm with the belt (P greater than 0.05). The subjects complained of significantly less discomfort when the belt was worn (P less than 0.05). The degree of shrinkage was significantly correlated (r = 0.752, P less than 0.05) with perceived discomfort but only when the belt was not worn. These results suggest the potential benefits of wearing a weightlifting belt and support the hypothesis that the belt can help in stabilizing the trunk.

Effect of a weightlifting belt on spinal shrinkage.

PubMed Central

Bourne, N D; Reilly, T

1991-01-01

Spinal loading during weightlifting results in a loss of stature which has been attributed to a decrease in height of the intervertebral discs--so-called 'spinal shrinkage'. Belts are often used during the lifting of heavy weights, purportedly to support, stabilize and thereby attenuate the load on the spine. The purpose of this study was to examine the effects of a standard weightlifting belt in attenuating spinal shrinkage. Eight male subjects with a mean age of 24.8 years performed two sequences of circuit weight-training, one without a belt and on a separate occasion with a belt. The circuit training regimen consisted of six common weight-training exercises. These were performed in three sets of ten with a change of exercise after each set of ten repetitions. A stadiometer sensitive to within 0.01 mm was used to record alterations in stature. Measurements of stature were taken before and after completion of the circuit. The absolute visual analogue scale (AVAS) was used to measure the discomfort and pain intensity resulting from each of the two conditions. The circuit weight-training caused stature losses of 3.59mm without the belt and 2.87 mm with the belt (P greater than 0.05). The subjects complained of significantly less discomfort when the belt was worn (P less than 0.05). The degree of shrinkage was significantly correlated (r = 0.752, P less than 0.05) with perceived discomfort but only when the belt was not worn. These results suggest the potential benefits of wearing a weightlifting belt and support the hypothesis that the belt can help in stabilizing the trunk. Images Figure 1 PMID:1810615

Low shrinkage light curable nanocomposite for dental restorative material.

PubMed

Chen, Min-Huey; Chen, Ci-Rong; Hsu, Seng-Haw; Sun, Shih-Po; Su, Wei-Fang

2006-02-01

The aim of this study was to develop a low shrinkage visible light curable nanocomposite dental restorative material without sacrificing the other properties of conventional materials. This nanocomposite was developed by using an epoxy resin 3,4-epoxycyclohexylmethyl-(3,4-epoxy)cyclohexane carboxylate (ERL4221) matrix with 55% wt of 70-100 nm nanosilica fillers through ring-opening polymerization. GPS (gamma-glycidoxypropyl trimethoxysilane) was used to modify the surfaces of silica nanoparticles. The nanocomposite was shown to exhibit low polymerization shrinkage strain, which is only a quarter of currently used methacrylate-based composites. It also exhibited a low thermal expansion coefficient of 49.8 microm/m degrees C which is comparable to that of the methacrylate based composites (51.2 microm/m degrees C). The strong interfacial interactions between the resin and fillers at nanoscales were demonstrated by an observed high strength and high thermal stability of the nanocomposite. A microhardness of 62 KHN and a tensile strength of 47 MPa were reached. A high degree of conversion ( approximately 70%) can be obtained after less than 60 s of irradiation upon the nanocomposite. A transmission electron microscope (TEM) study of the nanocomposite showed no aggregation of fillers. Comparable results to the methacrylate based composites were obtained from the one day MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) cytotoxicity test. The developed epoxy resin based nanocomposite demonstrated low shrinkage and high strength and is suitable for dental restorative material applications.

Shrinkage regression-based methods for microarray missing value imputation.

PubMed

Wang, Hsiuying; Chiu, Chia-Chun; Wu, Yi-Ching; Wu, Wei-Sheng

2013-01-01

Missing values commonly occur in the microarray data, which usually contain more than 5% missing values with up to 90% of genes affected. Inaccurate missing value estimation results in reducing the power of downstream microarray data analyses. Many types of methods have been developed to estimate missing values. Among them, the regression-based methods are very popular and have been shown to perform better than the other types of methods in many testing microarray datasets. To further improve the performances of the regression-based methods, we propose shrinkage regression-based methods. Our methods take the advantage of the correlation structure in the microarray data and select similar genes for the target gene by Pearson correlation coefficients. Besides, our methods incorporate the least squares principle, utilize a shrinkage estimation approach to adjust the coefficients of the regression model, and then use the new coefficients to estimate missing values. Simulation results show that the proposed methods provide more accurate missing value estimation in six testing microarray datasets than the existing regression-based methods do. Imputation of missing values is a very important aspect of microarray data analyses because most of the downstream analyses require a complete dataset. Therefore, exploring accurate and efficient methods for estimating missing values has become an essential issue. Since our proposed shrinkage regression-based methods can provide accurate missing value estimation, they are competitive alternatives to the existing regression-based methods.

Intractable depression successfully treated with a combination of autogenic training and high-dose antidepressant in department of otorhinolaryngology: a case report.

PubMed

Goto, Fumiyuki; Nakai, Kimiko; Murakami, Masato; Ogawa, Kaoru

2009-08-14

Patients suffering from ear discomfort are commonly encountered in the department of otolaryngology. If various clinical examinations do not reveal any objective findings, then the patients are referred to the department of internal medicine or psychiatry. Psychotherapy is recommended in some cases. This paper describes the successful administration of autogenic training in a patient suffering from ear discomfort due to major depression. We present a case of intractable depression that was successfully treated with a combination of psychotherapy, administered by a clinical psychologist, and high-dose antidepressant. The patient was a 36-year-old female with hearing discomfort in her left ear. In 2003, she experienced insomnia and an appetite loss, and her condition was diagnosed as major depression along with an avoidant personality disorder. Her depression has not been improved with antidepressant treatment for 3 years in department of psychosomatic medicine. She was referred to our department because of ear discomfort in her left ear. There was no abnormality in her physical examinations. She wanted to be treated in department of otorhinolaryngology. We increased the dose of fluvoxamine maleate up to 200 mg/day, and introduced cognitive therapy and autogenic training by a clinical psychologist. Eventually, her depressive state as well as the hearing complaint was markedly alleviated. Autogenic training can be a viable and acceptable treatment option for patients who fail to respond to other therapies. This case emphasizes the importance of autogenic training as a method to control physical symptom of depression.

Photo-crosslinkable cyanoacrylate bioadhesive: shrinkage kinetics, dynamic mechanical properties, and biocompatibility of adhesives containing TMPTMA and POSS nanostructures as crosslinking agents.

PubMed

Ghasaban, S; Atai, M; Imani, M; Zandi, M; Shokrgozar, M-A

2011-11-01

The study investigates the photo-polymerization shrinkage behavior, dynamic mechanical properties, and biocompatibility of cyanoacrylate bioadhesives containing POSS nanostructures and TMPTMA as crosslinking agents. Adhesives containing 2-octyl cyanoacrylate (2-OCA) and different percentages of POSS nanostructures and TMPTMA as crosslinking agents were prepared. The 1-phenyl-1, 2-propanedione (PPD) was incorporated as photo-initiator into the adhesive in 1.5, 3, and 4 wt %. The shrinkage strain of the specimens was measured using bonded-disk technique. Shrinkage strain, shrinkage strain rate, maximum and time at maximum shrinkage strain rate were measured and compared. Mechanical properties of the adhesives were also studied using dynamic mechanical thermal analysis (DMTA). Biocompatibility of the adhesives was examined by MTT method. The results showed that shrinkage strain increased with increasing the initiator concentration up to 3 wt % in POSS-containing and 1.5 wt % in TMPTMA-containing specimens and plateaued out at higher concentrations. By increasing the crosslinking agent, shrinkage strain, and shrinkage strain rate increased and the time at maximum shrinkage strain rate decreased. The study indicates that the incorporation of crosslinking agents into the cyanoacrylate adhesives resulted in improved mechanical properties. Preliminary MTT studies also revealed better biocompatibility profile for the adhesives containing crosslinking agents comparing to the neat specimens. Copyright © 2011 Wiley Periodicals, Inc.

Damage of Wood-Concrete Composite subjected to variable hygrometric conditions

NASA Astrophysics Data System (ADS)

Loulou, L.; Caré, S.; Le Roy, R.; Bornert, M.

2010-06-01

This paper discusses the factors influencing the durability of glued assemblies of wood and cementitious material under variable hygrometric conditions. The composite specimens are composed of cement paste connected to plywood using epoxy glue. The cement paste is subjected to autogeneous shrinkage and the wood is subjected to imbibition test. Plywood is used so that the swelling deformations due to the imbibition process are parallel to the connection plane. Swelling strains in wood are related to the water content measured by gammadensimetry technique. Global strains above and below the glue interface have been measured and have been compared to the free strains. We showed that there are restrained deformations at the glue interface and that the cement paste is damaged. Local strains have been characterized by means of the digital image correlation technique. We showed in particular that the deformations in wood are related to the microstructure of the layers of plywood and that the restrained deformations at the glue interface lead to a bending of the cement paste. In the case of strong adhesion properties, this bending induces cracking in cement paste.

Swelling of Superabsorbent Poly(Sodium-Acrylate Acrylamide) Hydrogels and Influence of Chemical Structure on Internally Cured Mortar

NASA Astrophysics Data System (ADS)

Krafcik, Matthew J.; Erk, Kendra A.

Superabsorbent hydrogel particles show promise as internal curing agents for high performance concrete (HPC). These gels can absorb and release large volumes of water and offer a solution to the problem of self-dessication in HPC. However, the gels are sensitive to ions naturally present in concrete. This research connects swelling behavior with gel-ion interactions to optimize hydrogel performance for internal curing, reducing the chance of early-age cracking and increasing the durability of HPC. Four different hydrogels of poly(sodium-acrylate acrylamide) are synthesized and characterized with swelling tests in different salt solutions. Depending on solution pH, ionic character, and gel composition, diffrerent swelling behaviors are observed. As weight percent of acrylic acid increases, gels demonstrate higher swelling ratios in reverse osmosis water, but showed substantially decreased swelling when aqueous cations are present. Additionally, in multivalent cation solutions, overshoot peaks are present, whereby the gels have a peak swelling ratio but then deswell. Multivalent cations interact with deprotonated carboxylic acid groups, constricting the gel and expelling water. Mortar containing hydrogels showed reduced autogenous shrinkage and increased relative humidity.

Regional Brain Shrinkage over Two Years: Individual Differences and Effects of Pro-Inflammatory Genetic Polymorphisms

PubMed Central

Persson, N.; Ghisletta, P.; Dahle, C.L.; Bender, A.R.; Yang, Y.; Yuan, P.; Daugherty, A.M.; Raz, N.

2014-01-01

We examined regional changes in brain volume in healthy adults (N = 167, age 19-79 years at baseline; N = 90 at follow-up) over approximately two years. With latent change score models, we evaluated mean change and individual differences in rates of change in 10 anatomically-defined and manually-traced regions of interest (ROIs): lateral prefrontal cortex (LPFC), orbital frontal cortex (OF), prefrontal white matter (PFw), hippocampus (HC), parahippocampal gyrus (PhG), caudate nucleus (Cd), putamen (Pt), insula (In), cerebellar hemispheres (CbH), and primary visual cortex (VC). Significant mean shrinkage was observed in the HC, CbH, In, OF, and the PhG, and individual differences in change were noted in all regions, except the OF. Pro-inflammatory genetic variants mediated shrinkage in PhG and CbH. Carriers of two T alleles of interleukin-1β (IL-1βC-511T, rs16944) and a T allele of methylenetetrahydrofolate reductase (MTHFRC677T, rs1801133) polymorphisms showed increased PhG shrinkage. No effects of a pro-inflammatory polymorphism for C-reactive protein (CRP-286C>A>T, rs3091244) or apolipoprotein (APOE) ε4 allele were noted. These results replicate the pattern of brain shrinkage observed in previous studies, with a notable exception of the LPFC thus casting doubt on the unique importance of prefrontal cortex in aging. Larger baseline volumes of CbH and In were associated with increased shrinkage, in conflict with the brain reserve hypothesis. Contrary to previous reports, we observed no significant linear effects of age and hypertension on regional brain shrinkage. Our findings warrant further investigation of the effects of neuroinflammation on structural brain change throughout the lifespan. PMID:25264227

SEM-induced shrinkage and site-selective modification of single-crystal silicon nanopores

NASA Astrophysics Data System (ADS)

Chen, Qi; Wang, Yifan; Deng, Tao; Liu, Zewen

2017-07-01

Solid-state nanopores with feature sizes around 5 nm play a critical role in bio-sensing fields, especially in single molecule detection and sequencing of DNA, RNA and proteins. In this paper we present a systematic study on shrinkage and site-selective modification of single-crystal silicon nanopores with a conventional scanning electron microscope (SEM). Square nanopores with measurable sizes as small as 8 nm × 8 nm and rectangle nanopores with feature sizes (the smaller one between length and width) down to 5 nm have been obtained, using the SEM-induced shrinkage technique. The analysis of energy dispersive x-ray spectroscopy and the recovery of the pore size and morphology reveal that the grown material along with the edge of the nanopore is the result of deposition of hydrocarbon compounds, without structural damage during the shrinking process. A simplified model for pore shrinkage has been developed based on observation of the cross-sectional morphology of the shrunk nanopore. The main factors impacting on the task of controllably shrinking the nanopores, such as the accelerating voltage, spot size, scanned area of e-beam, and the initial pore size have been discussed. It is found that single-crystal silicon nanopores shrink linearly with time under localized irradiation by SEM e-beam in all cases, and the pore shrinkage rate is inversely proportional to the initial equivalent diameter of the pore under the same e-beam conditions.

DH and ESPI laser interferometry applied to the restoration shrinkage assessment

NASA Astrophysics Data System (ADS)

Campos, L. M. P.; Parra, D. F.; Vasconcelos, M. R.; Vaz, M.; Monteiro, J.

2014-01-01

In dental restoration postoperative marginal leakage is commonly associated to polymerization shrinkage effects. In consequence the longevity and quality of restorative treatment depends on the shrinkage mechanisms of the composite filling during the polymerization. In this work the development of new techniques for evaluation of those effects under light-induced polymerization of dental nano composite fillings is reported. The composite resins activated by visible light, initiate the polymerization process by absorbing light in wavelengths at about 470 nm. The techniques employed in the contraction assessment were digital holography (DH) and Electronic Speckle Pattern Interferometry (ESPI) based on laser interferometry. A satisfactory resolution was achieved in the non-contact displacement field measurements on small objects concerning the experimental dental samples. According to a specific clinical protocol, natural teeth were used (human mandibular premolars). A class I cavity was drilled and restored with nano composite material, according to Black principles. The polymerization was monitored by DH and ESPI in real time during the cure reaction of the restoration. The total displacement reported for the material in relation of the tooth wall was 3.7 μm (natural tooth). The technique showed the entire tooth surface (wall) deforming during polymerization shrinkage.

Effects of molecular structure of the resins on the volumetric shrinkage and the mechanical strength of dental restorative composites.

PubMed

Kim, L U; Kim, J W; Kim, C K

2006-09-01

To prepare a dental composite that has a low amount of curing shrinkage and excellent mechanical strength, various 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane (Bis-GMA) derivatives were synthesized via molecular structure design, and afterward, properties of their mixtures were explored. Bis-GMA derivatives, which were obtained by substituting methyl groups for hydrogen on the phenyl ring in the Bis-GMA, exhibited lower curing shrinkage than Bis-GMA, whereas their viscosities were higher than that of Bis-GMA. Other Bis-GMA derivatives, which contained a glycidyl methacrylate as a molecular end group exhibited reduced curing shrinkage and viscosity. Methoxy substitution for hydroxyl groups on the Bis-GMA derivatives was performed for the further reduction of the viscosity and curing shrinkage. Various resin mixtures, which had the same viscosity as the commercial one, were prepared, and their curing shrinkage was examined. A resin mixture containing 2,2-bis[3,5-dimethyl, 4-(2-methoxy-3-methacryloyloxy propoxy) phenyl] propane] (TMBis-M-GMA) as a base resin and 4-tert-butylphenoxy-2-methyoxypropyl methacrylate (t-BP-M-GMA) as a diluent exhibited the lowest curing shrinkage among them. The composite prepared from this resin mixture also exhibited the lowest curing shrinkage along with enhanced mechanical properties.

Conjugation of diisocyanate side chains to dimethacrylate reduces polymerization shrinkage and increases the hardness of composite resins.

PubMed

Jan, Yih-Dean; Lee, Bor-Shiunn; Lin, Chun-Pin; Tseng, Wan-Yu

2014-04-01

Polymerization shrinkage is one of the main causes of dental restoration failure. This study tried to conjugate two diisocyanate side chains to dimethacrylate resins in order to reduce polymerization shrinkage and increase the hardness of composite resins. Diisocyanate, 2-hydroxyethyl methacrylate, and bisphenol A dimethacrylate were reacted in different ratios to form urethane-modified new resin matrices, and then mixed with 50 wt.% silica fillers. The viscosities of matrices, polymerization shrinkage, surface hardness, and degrees of conversion of experimental composite resins were then evaluated and compared with a non-modified control group. The viscosities of resin matrices increased with increasing diisocyanate side chain density. Polymerization shrinkage and degree of conversion, however, decreased with increasing diisocyanate side chain density. The surface hardness of all diisocyanate-modified groups was equal to or significantly higher than that of the control group. Conjugation of diisocyanate side chains to dimethacrylate represents an effective means of reducing polymerization shrinkage and increasing the surface hardness of dental composite resins. Copyright © 2012. Published by Elsevier B.V.

Evaluation of the polymerization shrinkage of experimental flowable composite resins through optical coherence tomography

NASA Astrophysics Data System (ADS)

Carneiro, Vanda S. M.; Mota, Cláudia C. B. O.; Souza, Alex F.; Cajazeira, Marlus R. R.; Gerbi, Marleny E. M. M.; Gomes, Anderson S. L.

2018-02-01

This study evaluated the polymerization shrinkage of two experimental flowable composite resins (CR) with different proportions of Urethane dimethacrylate (UDMA)/triethylene glycol dimethacrylate (TEGDMA) monomers in the organic matrix (50:50 and 60:40, respectively). A commercially available flowable CR, Tetric N-Flow (Ivoclair Vivadent, Liechtenstein, Germany), was employed as the control group. The resins were inserted in a cylindrical teflon mold (7 mm diameter, 0.6 mm height) and scanned with OCT before photoactivation, immediately after and 15 minutes after light-curing (Radii-Cal, SDI, Australia, 1,200 mW/cm2 ) exposure. A Callisto SD-OCT system (Thorlabs Inc, USA), operating at 930 nm central wavelength was employed for imaging acquisition. Cross-sectional OCT images were captured with 8 mm transverse scanning (2000x512 matrix), and processed by the ImageJ software, for comparison between the scanning times and between groups. Pearson correlation showed significant shrinkage for all groups in each time analyzed. Kruskal-Wallis test showed greater polymerization shrinkage for the 50:50 UDMA/TEGDMA group (p=0.001), followed by the control group (p=0.018). TEGDMA concentration was proportionally related to the polymerization shrinkage of the flowable composite resins.

A study of 23 unicameral bone cysts of the calcaneus: open chip allogeneic bone graft versus percutaneous injection of bone powder with autogenous bone marrow.

PubMed

Park, Il-Hyung; Micic, Ivan Dragoljub; Jeon, In-Ho

2008-02-01

The treatment of unicameral bone cyst varies from percutaneous needle biopsy, aspiration and local injection of steroid, autologous bone marrow, or demineralized bone matrix to curettage and open bone-grafting. The purpose of this study was to compare the results of open chip allogeneic bone graft versus percutaneous injection of demineralized bone powder with autogenous bone marrow in management of calcaneal cysts. Twenty-three calcaneal unicameral cysts in 20 patients were treated. Lyophilized irradiated chip allogeneic bone (CAB) and autogenous bone marrow were used for treatment of 13 cysts in 11 patients, and 10 cysts in 9 patients were treated with percutaneous injection of irradiated allogeneic demineralized bone powder (DBP) and autogenous bone marrow. There were 11 males and 9 female patients with mean age of 17 years. The patients were followed for an average of 49.4 months. Complete healing was achieved in 9 cysts treated with chip allogeneic bone and in 5 cysts treated with powdered bone. Four cysts treated with CAB and 3 cysts treated with DBP healed with a defect. Two cysts treated with powdered bone and autogenous bone marrow were classified as persistent. No infections or pathological fractures were observed during the followup period. Percutaneous injection of a mixture of allogeneic bone powder with autogenous bone marrow is a minimal invasive method and could be an effective alternative in the treatment of unicameral calcaneal bone cysts. The postoperative morbidity was low, the hospital stay was brief, and patient's comfort for unrestricted activity was enhanced.

Investigation on Failures of Composite Beam and Substrate Concrete due to Drying Shrinkage Property of Repair Materials

NASA Astrophysics Data System (ADS)

Pattnaik, Rashmi Ranjan

2017-06-01

A Finite Element Analysis (FEA) and an experimental study was conducted on composite beam of repair material and substrate concrete to investigate the failures of the composite beam due to drying shrinkage property of the repair materials. In FEA, the stress distribution in the composite beam due to two concentrate load and shrinkage of repair materials were investigated in addition to the deflected shape of the composite beam. The stress distributions and load deflection shapes of the finite element model were investigated to aid in analysis of the experimental findings. In the experimental findings, the mechanical properties such as compressive strength, split tensile strength, flexural strength, and load-deflection curves were studied in addition to slant shear bond strength, drying shrinkage and failure patterns of the composite beam specimens. Flexure test was conducted to simulate tensile stress at the interface between the repair material and substrate concrete. The results of FEA were used to analyze the experimental results. It was observed that the repair materials with low drying shrinkage are showing compatible failure in the flexure test of the composite beam and deform adequately in the load deflection curves. Also, the flexural strength of the composite beam with low drying shrinkage repair materials showed higher flexural strength as compared to the composite beams with higher drying shrinkage value of the repair materials even though the strength of those materials were more.

Analysis of the shrinkage at the thick plate part using response surface methodology

NASA Astrophysics Data System (ADS)

Hatta, N. M.; Azlan, M. Z.; Shayfull, Z.; Roselina, S.; Nasir, S. M.

2017-09-01

Injection moulding is well known for its manufacturing process especially in producing plastic products. To measure the final product quality, there are lots of precautions to be taken into such as parameters setting at the initial stage of the process. Sometimes, if these parameters were set up wrongly, defects may be occurred and one of the well-known defects in the injection moulding process is a shrinkage. To overcome this problem, a maximisation at the precaution stage by making an optimal adjustment on the parameter setting need to be done and this paper focuses on analysing the shrinkage by optimising the parameter at thick plate part with the help of Response Surface Methodology (RSM) and ANOVA analysis. From the previous study, the outstanding parameter gained from the optimisation method in minimising the shrinkage at the moulded part was packing pressure. Therefore, with the reference from the previous literature, packing pressure was selected as the parameter setting for this study with other three parameters which are melt temperature, cooling time and mould temperature. The analysis of the process was obtained from the simulation by Autodesk Moldflow Insight (AMI) software and the material used for moulded part was Acrylonitrile Butadiene Styrene (ABS). The analysis and result were obtained and it found that the shrinkage can be minimised and the significant parameters were found as packing pressure, mould temperature and melt temperature.

Intractable depression successfully treated with a combination of autogenic training and high-dose antidepressant in department of otorhinolaryngology: a case report

PubMed Central

2009-01-01

Introduction Patients suffering from ear discomfort are commonly encountered in the department of otolaryngology. If various clinical examinations do not reveal any objective findings, then the patients are referred to the department of internal medicine or psychiatry. Psychotherapy is recommended in some cases. This paper describes the successful administration of autogenic training in a patient suffering from ear discomfort due to major depression. Case presentation We present a case of intractable depression that was successfully treated with a combination of psychotherapy, administered by a clinical psychologist, and high-dose antidepressant. The patient was a 36-year-old female with hearing discomfort in her left ear. In 2003, she experienced insomnia and an appetite loss, and her condition was diagnosed as major depression along with an avoidant personality disorder. Her depression has not been improved with antidepressant treatment for 3 years in department of psychosomatic medicine. She was referred to our department because of ear discomfort in her left ear. There was no abnormality in her physical examinations. She wanted to be treated in department of otorhinolaryngology. We increased the dose of fluvoxamine maleate up to 200 mg/day, and introduced cognitive therapy and autogenic training by a clinical psychologist. Eventually, her depressive state as well as the hearing complaint was markedly alleviated. Conclusion Autogenic training can be a viable and acceptable treatment option for patients who fail to respond to other therapies. This case emphasizes the importance of autogenic training as a method to control physical symptom of depression. PMID:20184684

Differences between autogenous and reactive obsessions in terms of metacognitions and automatic thoughts.

PubMed

Keleş Altun, İlkay; Uysal, Emel; Özkorumak Karagüzel, Evrim

2017-01-01

Obsessive compulsive disorder (OCD) is characterized by obsessions and compulsions. Obsessions have been classified as autogenous obsessions and reactive obsessions on the basis of the cognitive theory of Lee and Kwon. The aim of this study was to investigate the differences between autogenous groups (AG) and reactive groups (RG) in terms of metacognition and automatic thoughts, for the purpose of investigating the differences of cognitive appraisals. One hundred and thirty-three patients diagnosed with OCD were included in the study as the patient group. A control group was formed of 133 age, gender and education-matched healthy individuals. The OCD group patients were separated into subgroups according to the primary obsessions. The sociodemographic data, and the Yale-Brown Obsessive Compulsive Scale, Metacognition Questionnaire-30 (MCQ-30), Automatic Thoughts Questionnaire (ATQ), Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI) scores of the AG, RG, and control groups were compared. The MCQ-30 (total) and the subscales of MCQ-30 and ATQ scale points were seen to be significantly higher in the AG than in the RG and significantly higher in the RG than in the control group. In the reactive obsession group, the predictive variables of the ATQ points were determined to be MCQ-30 (total), BDI and BAI. In the autogenous obsession group, the predictive variables of the ATQ points were determined to be BDI and BAI. In the current study, differences were determined between the AG and the RG in respect of metacognitions and automatic thoughts. In light of these results, the recommended grouping can be considered useful in the identification of OCD sub-types. There is a need for further studies to identify more homogenous sub-types of OCD. Future multi-centered studies of sub-typing with larger samples using more specific instruments to sub-type and dimensional evaluation will be useful for detailed evaluation and better understanding of the subject.

Stiffness and shrinkage of green and dry joists

Treesearch

Lyman W. Wood; Lawrence A. Soltis

1964-01-01

This report gives information on the edgewise modulus of elasticity, stiffness, and shrinkage of 360 joists in three species, three grades, and two sizes, each species obtained from two sources. Each joist was evaluated nondestructively at four moisture content values ranging from the green condition to about 11 percent. Information is also given on specific gravity,...

[Substance P and vasoactive intestinal peptide in patients with progressive scleroderma. Determination of plasma level before and after autogenic training].

PubMed

Haustein, U F; Weber, B; Seikowski, K

1995-02-01

In 12 patients suffering from systemic sclerosis (SSc) the influence of autogenic training on the plasma level of the neuropeptides substance P and vasoactive intestinal peptide (VIP) was studied. Compared with healthy controls the SSc patients exhibited significantly elevated levels of substance P (mean +/- SD: 7.1 +/- 3.2 pmol/l vs 1.6 +/- 1.6 pmol/l). Apart from variations the VIP plasma concentration did not significantly differ from that in healthy controls (mean +/- SD 10.7 +/- 7.1 pmol/l versus 12.0 +/- 5.3 pmol/l). Autogenic training did not bring about any significant changes in the plasma levels of neuropeptides.

The Long-Term Clinical Outcomes Following Autogenous Bone Grafting for Large-Volume Defects of the Knee

PubMed Central

Delano, Mark; Spector, Myron; Pittsley, Andrew; Gottschalk, Alexander

2014-01-01

Objective: We report the long-term clinical outcomes of patients who underwent autogenous bone grafting of large-volume osteochondral defects of the knee due to osteochondritis dessicans (OCD) and osteonecrosis (ON). This is the companion report to one previous published on the biological response. We hypothesized that these grafts would integrate with host bone and the articular surface would form fibrocartilage providing an enduring clinical benefit. Design: Three groups (patients/knees) were studied: OCD without a fragment (n = 12/13), OCD with a partial fragment (n = 14/16), and ON (n = 25/26). Twenty-five of 52 patients were available for clinical follow-up between 12 and 21 years. Electronic medical records provided comparison clinical information. In addition, there were plain film radiographs, MRIs, plus repeat arthroscopy and biopsy on 14 patients. Results: Autogenous bone grafts integrated with the host bone. MRI showed soft tissue covering all the grafts at long-term follow-up. Biopsy showed initial surface fibrocartilage that subsequently converted to fibrocartilage and hyaline cartilage at 20 years. OCD patients had better clinical outcomes than ON patients. No OCD patients were asymptomatic at anytime following surgery. Half of the ON patients came to total knee replacement within 10 years. Conclusions: Autogenous bone grafting provides an alternative biological matrix to fill large-volume defects in the knee as a singular solution integrating with host bone and providing an enduring articular cartilage surface. The procedure is best suited for those with OCD. The treatment for large-volume articular defects by this method remains salvage in nature and palliative in outcome. PMID:26069688

Modified Weaver-Dunn Procedure Versus The Use of Semitendinosus Autogenous Tendon Graft for Acromioclavicular Joint Reconstruction.

PubMed

Hegazy, Galal; Safwat, Hesham; Seddik, Mahmoud; Al-Shal, Ehab A; Al-Sebai, Ibrahim; Negm, Mohame

2016-01-01

The optimal operative method for acromioclavicular joint reconstruction remains controversial. The modified Weaver-Dunn method is one of the most popular methods. Anatomic reconstruction of coracoclavicular ligaments with autogenous tendon grafts, widely used in treating chronic acromioclavicular joint instability, reportedly diminishes pain, eliminates sequelae, and improves function as well as strength. To compare clinical and radiologic outcomes between a modified Weaver-Dunn procedure and an anatomic coracoclavicular ligaments reconstruction technique using autogenous semitendinosus tendon graft. Twenty patients (mean age, 39 years) with painful, chronic Rockwood type III acromioclavicular joint dislocations were subjected to surgical reconstruction. In ten patients, a modified Weaver-Dunn procedure was performed, in the other ten patients; autogenous semitendinosus tendon graft was used. The mean time between injury and the index procedure was 18 month (range from 9 - 28). Clinical evaluation was performed using the Oxford Shoulder Score and Nottingham Clavicle Score after a mean follow-up time of 27.8 months. Preoperative and postoperative radiographs were compared. In the Weaver-Dunn group the Oxford Shoulder Score improved from 25±4 to 40±2 points. While the Nottingham Clavicle Score increased from 48±7 to 84±11. In semitendinosus tendon graft group, the Oxford Shoulder Score improved from 25±3 points to 50±2 points and the Nottingham Clavicle Score from 48±8 points to 95±8, respectively. Acromioclavicular joint reconstruction using the semitendinosus tendon graft achieved better Oxford Shoulder Score and Nottingham Clavicle Score compared to the modified Weaver-Dunn procedure.

Modified Weaver-Dunn Procedure Versus The Use of Semitendinosus Autogenous Tendon Graft for Acromioclavicular Joint Reconstruction

PubMed Central

Hegazy, Galal; Safwat, Hesham; Seddik, Mahmoud; Al-shal, Ehab A.; Al-Sebai, Ibrahim; Negm, Mohame

2016-01-01

Background: The optimal operative method for acromioclavicular joint reconstruction remains controversial. The modified Weaver-Dunn method is one of the most popular methods. Anatomic reconstruction of coracoclavicular ligaments with autogenous tendon grafts, widely used in treating chronic acromioclavicular joint instability, reportedly diminishes pain, eliminates sequelae, and improves function as well as strength. Objective: To compare clinical and radiologic outcomes between a modified Weaver-Dunn procedure and an anatomic coracoclavicular ligaments reconstruction technique using autogenous semitendinosus tendon graft. Methods: Twenty patients (mean age, 39 years) with painful, chronic Rockwood type III acromioclavicular joint dislocations were subjected to surgical reconstruction. In ten patients, a modified Weaver-Dunn procedure was performed, in the other ten patients; autogenous semitendinosus tendon graft was used. The mean time between injury and the index procedure was 18 month (range from 9 – 28). Clinical evaluation was performed using the Oxford Shoulder Score and Nottingham Clavicle Score after a mean follow-up time of 27.8 months. Preoperative and postoperative radiographs were compared. Results: In the Weaver-Dunn group the Oxford Shoulder Score improved from 25±4 to 40±2 points. While the Nottingham Clavicle Score increased from 48±7 to 84±11. In semitendinosus tendon graft group, the Oxford Shoulder Score improved from 25±3 points to 50±2 points and the Nottingham Clavicle Score from 48±8 points to 95±8, respectively. Conclusion: Acromioclavicular joint reconstruction using the semitendinosus tendon graft achieved better Oxford Shoulder Score and Nottingham Clavicle Score compared to the modified Weaver-Dunn procedure. PMID:27347245

Trait- and density-mediated indirect interactions initiated by an exotic invasive plant autogenic ecosystem engineer

Treesearch

Dean E. Pearson

2010-01-01

Indirect interactions are important for structuring ecological systems. However, research on indirect effects has been heavily biased toward top-down trophic interactions, and less is known about other indirect-interaction pathways. As autogenic ecosystem engineers, plants can serve as initiators of nontrophic indirect interactions that, like top-down pathways, can...

Autogenic Feedback Training (Body Fortran) with Biofeedback and the Computer for Self-Improvement and Change.

ERIC Educational Resources Information Center

Cassel, Russell N.; Sumintardja, Elmira Nasrudin

1983-01-01

Describes autogenic feedback training, which provides the basis whereby an individual is able to improve on well being through use of a technique described as "body fortran," implying that you program self as one programs a computer. Necessary requisites are described including relaxation training and the management of stress. (JAC)

Comparison of Bovine Bone-Autogenic Bone Mixture Versus Platelet-Rich Fibrin for Maxillary Sinus Grafting: Histologic and Histomorphologic Study.

PubMed

Ocak, Hakan; Kutuk, Nukhet; Demetoglu, Umut; Balcıoglu, Esra; Ozdamar, Saim; Alkan, Alper

2017-06-01

Numerous grafting materials have been used to augment the maxillary sinus floor for long-term stability and success for implant-supported prosthesis. To enhance bone formation, adjunctive blood-born growth factor sources have gained popularity during the recent years. The present study compared the use of platelet-rich fibrin (PRF) and bovine-autogenous bone mixture for maxillary sinus floor elevation. A split-face model was used to apply 2 different filling materials for maxillary sinus floor elevation in 22 healthy adult sheep. In group 1, bovine and autogenous bone mixture; and in group 2, PRF was used. The animals were killed at 3, 6, and 9 months. Histologic and histomorphologic examinations revealed new bone formation in group 1 at the third and sixth months. In group 2, new bone formation was observed only at the sixth month, and residual PRF remnants were identified. At the ninth month, host bone and new bone could not be distinguished from each other in group 1, and bone formation was found to be proceeding in group 2. PRF remnants still existed at the ninth month. In conclusion, bovine bone and autogenous bone mixture is superior to PRF as a grafting material in sinus-lifting procedures.

Autogenic Versus Allogenic Controls on the Evolution of a Coupled Fluvial Megafan-Mountainous Catchment System: Insight from Numerical Modelling

NASA Astrophysics Data System (ADS)

Mouchene, M.; van der Beek, P.; Carretier, S.; Mouthereau, F.

2017-12-01

Alluvial megafans are sensitive recorders of landscape evolution, controlled by both autogenic processes and allogenic forcing, and they are influenced by the coupled dynamics of the fan with its mountainous catchment. The Mio-Pliocene Lannemezan megafan in the northern Pyrenean foreland (SW France) was abandoned by its mountainous feeder stream during the Quaternary and subsequently incised. The flight of alluvial terraces abandoned along the stream network may suggest a climatic control on the incision. We use a landscape evolution numerical model (CIDRE) to explore the relative roles of autogenic processes and external forcing in the building, abandonment and incision of a foreland megafan, and we compare the results with the inferred evolution of the Lannemezan megafan. Autogenic processes are sufficient to explain the building of a megafan and the long-term entrenchment of its feeding river on time and space scales that match the Lannemezan setting. Climate, through temporal variations in precipitation rate, may have played a role in the episodic pattern of incision on a shorter timescale. In contrast, base-level changes, tectonic activity in the mountain range or tilting of the foreland through flexural isostatic rebound do not appear to have played a role in the abandonment of the megafan.

Endodontic Treatment of an Autogenous Transplanted Tooth Using an Er,Cr:YSGG Laser and Radial Firing Tips: Case Report.

PubMed

Martins, Miguel Rodrigues; Lima, Rita C; Pina-Vaz, Irene; Carvalho, Manuel Fontes; Gutknecht, Norbert

2016-10-01

Although several surgical techniques have been reported, no study has yet reported alternative strategies for endodontic treatment of autogenous transplanted teeth. Therefore, the aim of this clinical report is to present the long-term endodontic outcome of a nonvital autogenously transplanted third molar treated with an Er,Cr:YSGG laser and radial firing tips (RFTs). Autogenous tooth transplantation can be considered an alternative to restore edentulous areas and, in donor's teeth with complete root formation, root canal treatment should be performed up to 14 days following transplantation. In the present case report, the patient returned only after 6 months, with clinical and radiological signs of apical periodontitis (AP) associated with the transplanted tooth. Instead of traditional endodontic chemical irrigants or medications, the protocol for smear-layer removal and root canal disinfection was based on intracanal irradiation with an Er,Cr:YSGG laser and RFTs. After 3-years' follow-up, the complete reestablishment of the periodontal ligament and the arrest of the resorptive process could be noticed. This protocol has shown to be effective for the endodontic treatment of a transplanted multi-rooted tooth with AP. Further randomized clinical trials should be conducted to clearly demonstrate the effectiveness of this laser-assisted endodontic protocol.

[Repair of swine full-thickness cutaneous deficiency by autogenic BMSCs compounded with collagen membrane].

PubMed

He, Lijuan; Liu, Daqing; Bai, Cixian; Yan, Yingfun; Guan, Lidong; Pei, Xuetao

2009-03-01

To supply references to tissue-engineered skin clinical applications with autogenic BMSCs composited collagen membrane to repair swine full-thickness cutaneous deficiency. Twenty mL bone marrow were obtained respectively from 4 swine, autogenic BMSCs were cultured and passed to the 3rd passage. The fresh bovine tendon treated by means of chemically cross-linked was made 5 cm diameter collagen I (Col I) membrane. The 2 x 10(7)/mL P3 swine autogenic BMSCs labeled DAPI were planted to sterile Col I membrane for 24 hours incubation, then the tissue-engineered skin was constructed. The five full-thickness skin defect of 5 cm diameter was excised to the muscle from forward to backward on the back midline two sides of swine. The tissue-engineered skin were implanted in the experimental group, while Col I membrane was implanted in control group. After 3 and 8 weeks of implantation, the two swine wound surface healing circumstance was observed and further evaluated with histology analysis and TEM. After 3 weeks of implantation, the experimental group were observed with fluorescence microscopy and staining for glycogen. After 3 weeks of implantation, the wound surface of control group were observed nigrescene, scab and putrescence, and after 8 weeks of implantation, also evident putrescence and scar. The wound surface of experiment group was alive after 3 weeks implantation, appearance was leveled off and flexible without evident scar. The wound surface recovered well after 8 weeks of implantation, wound surface healing rate was significantly difference between the two groups (P < 0.01). After 3 weeks of implantation, control group were observed acestoma hyperplasia and no epidermal coverage by histology analysis. The experimental group was showed integrity epidermis and dermis structure. The basal layer was crimson and continuously positive with glycogen staining. After 8 weeks of implantation, the experimental group and control group were emerged normal skin structure

3D mapping of polymerization shrinkage using X-ray micro-computed tomography to predict microleakage.

PubMed

Sun, Jirun; Eidelman, Naomi; Lin-Gibson, Sheng

2009-03-01

The objectives of this study were to (1) demonstrate X-ray micro-computed tomography (microCT) as a viable method for determining the polymerization shrinkage and microleakage on the same sample accurately and non-destructively, and (2) investigate the effect of sample geometry (e.g., C-factor and volume) on polymerization shrinkage and microleakage. Composites placed in a series of model cavities of controlled C-factors and volumes were imaged using microCT to determine their precise location and volume before and after photopolymerization. Shrinkage was calculated by comparing the volume of composites before and after polymerization and leakage was predicted based on gap formation between composites and cavity walls as a function of position. Dye penetration experiments were used to validate microCT results. The degree of conversion (DC) of composites measured using FTIR microspectroscopy in reflectance mode was nearly identical for composites filled in all model cavity geometries. The shrinkage of composites calculated based on microCT results was statistically identical regardless of sample geometry. Microleakage, on the other hand, was highly dependent on the C-factor as well as the composite volume, with higher C-factors and larger volumes leading to a greater probability of microleakage. Spatial distribution of microleakage determined by microCT agreed well with results determined by dye penetration. microCT has proven to be a powerful technique in quantifying polymerization shrinkage and corresponding microleakage for clinically relevant cavity geometries.

Suspended, Shrinkage-Free, Electrospun PLGA Nanofibrous Scaffold for Skin Tissue Engineering.

PubMed

Ru, Changhai; Wang, Feilong; Pang, Ming; Sun, Lining; Chen, Ruihua; Sun, Yu

2015-05-27

Electrospinning is a technique for creating continuous nanofibrous networks that can architecturally be similar to the structure of extracellular matrix (ECM). However, the shrinkage of electrospun mats is unfavorable for the triggering of cell adhesion and further growth. In this work, electrospun PLGA nanofiber assemblies are utilized to create a scaffold. Aided by a polypropylene auxiliary supporter, the scaffold is able to maintain long-term integrity without dimensional shrinkage. This scaffold is also able to suspend in cell culture medium; hence, keratinocyte cells seeded on the scaffold are exposed to air as required in skin tissue engineering. Experiments also show that human skin keratinocytes can proliferate on the scaffold and infiltrate into the scaffold.

Evaluation of bridge deck with shrinkage-compensating concrete.

DOT National Transportation Integrated Search

2016-04-01

Concrete bridge decks are susceptible to premature cracking and to corrosion of reinforcing steel. Low-permeability : concrete does not always ensure durability if the concrete has excessive cracks that facilitate the intrusion of aggressive solution...

Untangling climatic and autogenic signals in peat records

NASA Astrophysics Data System (ADS)

Morris, Paul J.; Baird, Andrew J.; Young, Dylan M.; Swindles, Graeme T.

2016-04-01

Raised bogs contain potentially valuable information about Holocene climate change. However, autogenic processes may disconnect peatland hydrological behaviour from climate, and overwrite and degrade climatic signals in peat records. How can genuine climate signals be separated from autogenic changes? What level of detail of climatic information should we expect to be able to recover from peat-based reconstructions? We used an updated version of the DigiBog model to simulate peatland development and response to reconstructed Holocene rainfall and temperature reconstructions. The model represents key processes that are influential in peatland development and climate signal preservation, and includes a network of feedbacks between peat accumulation, decomposition, hydraulic structure and hydrological processes. It also incorporates the effects of temperature upon evapotranspiration, plant (litter) productivity and peat decomposition. Negative feedbacks in the model cause simulated water-table depths and peat humification records to exhibit homeostatic recovery from prescribed changes in rainfall, chiefly through changes in drainage. However, the simulated bogs show less resilience to changes in temperature, which cause lasting alterations to peatland structure and function and may therefore be more readily detectable in peat records. The network of feedbacks represented in DigiBog also provide both high- and low-pass filters for climatic information, meaning that the fidelity with which climate signals are preserved in simulated peatlands is determined by both the magnitude and the rate of climate change. Large-magnitude climatic events of an intermediate frequency (i.e., multi-decadal to centennial) are best preserved in the simulated bogs. We found that simulated humification records are further degraded by a phenomenon known as secondary decomposition. Decomposition signals are consistently offset from the climatic events that generate them, and decomposition

Management of unicameral bone cyst by using freeze dried radiation sterilized bone allograft impregnate with autogenous bone marrow.

PubMed

Datta, N K; Das, K P; Alam, M S; Kaiser, M S

2014-07-01

Unicameral bone cyst is a common benign bone tumor and most frequent cause of the pathological fracture in children. We have started a prospective study for that treatment of unicameral bone cyst by using freeze dried radiation sterilized bone allograft impregnated with autogenous bone marrow in the department of Orthopaedics, Bangabandhu Sheikh Mujib Medical University (BSMMU) during May 1999 to April 2012. Aim of this study was to see Freeze dried radiation sterilized bone allograft impregnate with autogenous bone marrow a satisfactory graft material in the treatment of unicameral bone cyst as well as factors such as patients age, sex, cyst size and site of lesion influence on cyst healing. A total 35 patients of unicameral bone cyst were operated. In this study out of 35 patients, male were 22(62.86%) and female were 13(37.14). Male Female ratio 22:13(1.70:1) Age of the patients ranging from 2 years 6 month to 20 years, mean age 12.18 years more common 11 years to 20 years 29(82.86%) patients. Common bones sites involvements are proximal end of Humerus 20(57.14%), proximal end of Femur 7(20 %), proximal end of Tibia 3(8.57%), Calcanium 2(5.71%), proximal end of Ulna 1(2.86%), shaft of Radius 1(2.86%) and Phalanx 1(2.86%). Final clinical outcome of unicameral bone cyst treated by thorough curettage of cavity and tightly filled with freeze dried radiation sterilized bone allograft impregnate with autogenous bone marrow in which healed (success rate) 88.57% (31) and recurrence rate is 11.43% (4). P value is <0.001. Follow up period was 6 month to 11 years. From our study it was realized that freeze dried radiation sterilized bone allograft impregnated with autogenous bone marrow is useful graft material for healing of the lesional area as well as restoring structural integrity for the treatment of unicameral bone cyst.

Measurement of the full-field polymerization shrinkage and depth of cure of dental composites using digital image correlation.

PubMed

Li, Jianying; Fok, Alex S L; Satterthwaite, Julian; Watts, David C

2009-05-01

The aim of this study was to measure the full-field polymerization shrinkage of dental composites using optical image correlation method. Bar specimens of cross-section 4mm x 2mm and length 10mm approximately were light cured with two irradiances, 450 mW/cm(2) and 180 mW/cm(2), respectively. The curing light was generated with Optilux 501 (Kerr) and the two different irradiances were achieved by adjusting the distance between the light tip and the specimen. A single-camera 2D measuring system was used to record the deformation of the composite specimen for 30 min at a frequency of 0.1 Hz. The specimen surface under observation was sprayed with paint to produce sufficient contrast to allow tracking of individual points on the surface. The curing light was applied to one end of the specimen for 40s during which the painted surface was fully covered. After curing, the cover was removed immediately so that deformation of the painted surface could be recorded by the camera. The images were then analyzed with specialist software and the volumetric shrinkage determined along the beam length. A typical shrinkage strain field obtained on a specimen surface was highly non-uniform, even at positions of constant distance from the irradiation surface, indicating possible heterogeneity in material composition and shrinkage behavior in the composite. The maximum volumetric shrinkage strain of approximately 1.5% occurred at a subsurface distance of about 1mm, instead of at the irradiation surface. After reaching its peak value, the shrinkage strain then gradually decreased with increasing distance along the beam length, before leveling off to a value of approximately 0.2% at a distance of 4-5mm. The maximum volumetric shrinkage obtained agreed well with the value of 1.6% reported by the manufacturer for the composite examined in this work. Using irradiance of 180 mW/cm(2) resulted in only slightly less polymerization shrinkage than using irradiance of 450 mW/cm(2). Compared to the

Crack deflection: Implications for the growth of long and short fatigue cracks

NASA Astrophysics Data System (ADS)

Suresh, S.

1983-11-01

The influences of crack deflection on the growth rates of nominally Mode I fatigue cracks are examined. Previous theoretical analyses of stress intensity solutions for kinked elastic cracks are reviewed. Simple elastic deflection models are developed to estimate the growth rates of nonlinear fatigue cracks subjected to various degrees of deflection, by incorporating changes in the effective driving force and in the apparent propagation rates. Experimental data are presented for intermediate-quenched and step-quenched conditions of Fe/2Si/0.1C ferrite-martensite dual phase steel, where variations in crack morphology alone influence considerably the fatigue crack propagation rates and threshold stress intensity range values. Such results are found to be in good quantitative agreement with the deflection model predictions of propagation rates for nonlinear cracks. Experimental information on crack deflection, induced by variable amplitude loading, is also provided for 2020-T651 aluminum alloy. It is demonstrated with the aid of elastic analyses and experiments that crack deflection models offer a physically-appealing rationale for the apparently slower growth rates of long fatigue cracks subjected to constant and variable amplitude loading and for the apparent deceleration and/or arrest of short cracks. The changes in the propagation rates of deflected fatigue cracks are discussed in terms of the local mode of crack advance, microstructure, effective driving force, growth mechanisms, mean stress, slip characteristics, and crack closure.

Success Rates and Immunologic Responses of Autogenic, Allogenic, and Xenogenic Treatments to Repair Articular Cartilage Defects

PubMed Central

Revell, Christopher M.

2009-01-01

This review examines current approaches available for articular cartilage repair, not only in terms of their regeneration potential, but also as a function of immunologic response. Autogenic repair techniques, including osteochondral plug transplantation, chondrocyte implantation, and microfracture, are the most widely accepted clinical treatment options due to the lack of immunogenic reactions, but only moderate graft success rates have been reported. Although suspended allogenic chondrocytes are shown to evoke an immune response upon implantation, allogenic osteochondral plugs and tissue-engineered grafts using allogenic chondrocytes exhibit a tolerable immunogenic response. Additionally, these repair techniques produce neotissue with success rates approaching those of currently available autogenic repair techniques, while simultaneously obviating their major hindrance of donor tissue scarcity. To date, limited research has been performed with xenogenic tissue, although several studies demonstrate the potential for its long-term success. This article focuses on the various treatment options for cartilage repair and their associated success rates and immunologic responses. PMID:19063664

The Shrinkage Model And Expert System Of Plastic Lens Formation

NASA Astrophysics Data System (ADS)

Chang, Rong-Seng

1988-06-01

Shrinkage causes both the appearance & dimension defects of the injected plastic lens. We have built up a model of state equations with the help of finite element analysis program to estimate the volume change (shrinkage and swelling) under the combinations of injection variables such as pressure and temperature etc., then the personal computer expert system has been build up to make that knowledge conveniently available to the user in the model design, process planning, process operation and some other work. The domain knowledge is represented by a R-graph (Relationship-graph) model which states the relationships of variables & equations. This model could be compare with other models in the expert system. If the user has better model to solve the shrinkage problem, the program will evaluate it automatically and a learning file will be trigger by the expert system to teach the user to update their knowledge base and modify the old model by this better model. The Rubin's model and Gilmore's model have been input to the expert system. The conflict has been solved both from the user and the deeper knowledge base. A cube prism and the convex lens examples have been shown in this paper. This program is written by MULISP language in IBM PC-AT. The natural language provides English Explaination of know why and know how and the automatic English translation for the equation rules and the production rules.

Influence of gelatinous fibers on the shrinkage of silver maple

Treesearch

Donals G. Arganbright; Dwight W. Bensend; Floyd G. Manwiller

1970-01-01

The degree of lean was found to have a significant influence on the logitudinal and transverse shrinkage of three soft maple trees. This may be accounted for by differences in the cell wall layer thickness and fibril angle.

Urban shrinkage in Germany and the USA: a comparison of transformation patterns and local strategies.

PubMed

Wiechmann, Thorsten; Pallagst, Karina M

2012-01-01

Many American and European cities have to deal with demographic and economic trajectories leading to urban shrinkage. According to official data, 13% of urban regions in the US and 54% of those in the EU have lost population in recent years. However, the extent and spatial distribution of declining populations differ significantly between Europe and the US. In Germany, the situation is driven by falling birth rates and the effects of German reunification. In the US, shrinkage is basically related to long-term industrial transformation. But the challenges of shrinking cities seldom appeared on the agendas of politicians and urban planners until recently. This article provides a critical overview of the development paths and local strategies of four shrinking cities: Schwedt and Dresden in eastern Germany; Youngstown and Pittsburgh in the US. A typology of urban growth and shrinkage, from economic and demographic perspectives, enables four types of city to be differentiated and the differences between the US and eastern Germany to be discussed. The article suggests that a new transatlantic debate on policy and planning strategies for restructuring shrinking cities is needed to overcome the dominant growth orientation that in most cases intensifies the negative consequences of shrinkage.

Gear crack propagation investigations

NASA Technical Reports Server (NTRS)

Lewicki, David G.; Ballarini, Roberto

1996-01-01

Analytical and experimental studies were performed to investigate the effect of gear rim thickness on crack propagation life. The FRANC (FRacture ANalysis Code) computer program was used to simulate crack propagation. The FRANC program used principles of linear elastic fracture mechanics, finite element modeling, and a unique re-meshing scheme to determine crack tip stress distributions, estimate stress intensity factors, and model crack propagation. Various fatigue crack growth models were used to estimate crack propagation life based on the calculated stress intensity factors. Experimental tests were performed in a gear fatigue rig to validate predicted crack propagation results. Test gears were installed with special crack propagation gages in the tooth fillet region to measure bending fatigue crack growth. Good correlation between predicted and measured crack growth was achieved when the fatigue crack closure concept was introduced into the analysis. As the gear rim thickness decreased, the compressive cyclic stress in the gear tooth fillet region increased. This retarded crack growth and increased the number of crack propagation cycles to failure.

Components of inhibition in autogenous- and reactive-type obsessive-compulsive disorder: Dissociation of interference control.

PubMed

Fan, Jie; Liu, Wanting; Lei, Hui; Cai, Lin; Zhong, Mingtian; Dong, Jiaojiao; Zhou, Cheng; Zhu, Xiongzhao

2016-05-01

Obsessive-compulsive disorder (OCD) is characterized by unwanted, intrusive thoughts (obsessions) and/or repetitive, ritualistic behaviors (compulsions). Findings related to the two components of inhibition, namely interference control and behavioral inhibition, among OCD patients have been inconsistent. It might be that this inconsistency is due to the heterogeneity among OCD cases representing multiple subtypes of OCD, such as autogenous obsessions and reactive obsessions types (AOs vs. ROs). AOs and ROs are distinguished by the category of their most disturbing obsessions. The purpose of this study was to systematically examine whether inhibition functions differ between AO and RO patients. We assessed interference control and behavioral inhibition with the emotional Stroop task (EST) and stop-signal task (SST), respectively, in 42 AOs, 55 ROs and 62 healthy controls (HCs) and event-related potentials (ERPs) were recorded in a random subset of these subjects (25 AOs, 25 ROs, and 31HCs). Results showed that in the EST, AOs exhibited longer reaction times (RTs) for color-naming positive-, negative-, and neutral-valence word stimulus than both ROs and HCs, and demonstrated larger P2 and less negative N450 amplitudes than HCs and larger P3 amplitudes than ROs and HCs. In the SST, both AOs and ROs showed lengthened stop signal reaction time (SSRT) and reduced Stop-P3 amplitudes in successful inhibition (SI) trials compared to the HC group. These present findings suggest that behavioral inhibition impairment may reflect a common pathology in both the autogenous- and reactive-type OCD patients, whereas interference inhibition impairment appears to be specific to patients with autogenous obsessions. These findings strengthened the insight into the clinical heterogeneity and pathophysiology of OCD. Copyright © 2016 Elsevier B.V. All rights reserved.

Hybrid processing and anisotropic sintering shrinkage in textured ZnO ceramics

PubMed Central

Keskinbora, Kahraman; Suzuki, Tohru S; Ozgur Ozer, I; Sakka, Yoshio; Suvaci, Ender

2010-01-01

We have studied the combined effects of the templated grain growth and magnetic alignment processes on sintering, anisotropic sintering shrinkage, microstructure development and texture in ZnO ceramics. Suspensions of 0–10 vol % ZnO template particles were slip cast in a 12 T rotating magnetic field. Sintering and texture characteristics were investigated via thermomechanical analysis and electron backscatter diffraction, respectively. Sintering as well as texture characteristics depend on template concentration. For the studied ZnO system, there is a critical template concentration (2 vol % in this study) above which densification is limited by the templates owing to constrained sintering. Below this limit, the densification is enhanced and the anisotropic shrinkage is reduced, which is attributed to densifying characteristics of the templates. PMID:27877373

[Essential hypertension and stress. When do yoga, psychotherapy and autogenic training help?].

PubMed

Herrmann, J M

2002-05-09

Psychosocial factors play an important role in the development and course of essential hypertension, although "stress" can account for only 10% of blood pressure variance. A variety of psychotherapeutic interventions, such as relaxation techniques (autogenic training or progressive muscular relaxation), behavioral therapy or biofeedback techniques, can lower elevated blood pressure by an average of 10 mmHg (systolic) and 5 mmHg (diastolic). As a "secondary effect", such measures may also prompt the hypertensive to adopt a more health-conscious lifestyle.

Polymerization Behavior and Mechanical Properties of High-Viscosity Bulk Fill and Low Shrinkage Resin Composites.

PubMed

Shibasaki, S; Takamizawa, T; Nojiri, K; Imai, A; Tsujimoto, A; Endo, H; Suzuki, S; Suda, S; Barkmeier, W W; Latta, M A; Miyazaki, M

The present study determined the mechanical properties and volumetric polymerization shrinkage of different categories of resin composite. Three high viscosity bulk fill resin composites were tested: Tetric EvoCeram Bulk Fill (TB, Ivoclar Vivadent), Filtek Bulk Fill posterior restorative (FB, 3M ESPE), and Sonic Fill (SF, Kerr Corp). Two low-shrinkage resin composites, Kalore (KL, GC Corp) and Filtek LS Posterior (LS, 3M ESPE), were used. Three conventional resin composites, Herculite Ultra (HU, Kerr Corp), Estelite ∑ Quick (EQ, Tokuyama Dental), and Filtek Supreme Ultra (SU, 3M ESPE), were used as comparison materials. Following ISO Specification 4049, six specimens for each resin composite were used to determine flexural strength, elastic modulus, and resilience. Volumetric polymerization shrinkage was determined using a water-filled dilatometer. Data were evaluated using analysis of variance followed by Tukey's honestly significant difference test (α=0.05). The flexural strength of the resin composites ranged from 115.4 to 148.1 MPa, the elastic modulus ranged from 5.6 to 13.4 GPa, and the resilience ranged from 0.70 to 1.0 MJ/m 3 . There were significant differences in flexural properties between the materials but no clear outliers. Volumetric changes as a function of time over a duration of 180 seconds depended on the type of resin composite. However, for all the resin composites, apart from LS, volumetric shrinkage began soon after the start of light irradiation, and a rapid decrease in volume during light irradiation followed by a slower decrease was observed. The low shrinkage resin composites KL and LS showed significantly lower volumetric shrinkage than the other tested materials at the measuring point of 180 seconds. In contrast, the three bulk fill resin composites showed higher volumetric change than the other resin composites. The findings from this study provide clinicians with valuable information regarding the mechanical properties and

Concrete pavement mixture design and analysis (MDA) : factors influencing drying shrinkage.

DOT National Transportation Integrated Search

2014-10-01

This literature review focuses on factors influencing drying shrinkage of concrete. Although the factors are normally interrelated, they : can be categorized into three groups: paste quantity, paste quality, and other factors.

Influence of friction stir processing on the room temperature fatigue cracking mechanisms of A356 aluminum alloy

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

Nelaturu, Phalgun; Jana, Saumyadeep; Mishra, Rajiv S.

Here, failure by fatigue is a common problem associated with cast aluminum alloys due to defects like shrinkage porosities, non-metallic inclusions, etc. Friction stir processing (FSP) has recently emerged as an effective technique for local modification of microstructure. This study investigates the fatigue crack initiation and growth mechanisms in cast and FSPed A356 aluminum alloy. Two sets of parameters were used to friction stir the cast alloy resulting in the complete modification the cast microstructure to a wrought microstructure. Both the FSPed microstructures exhibited severe abnormal grain growth (AGG) after heat treatment leading to a multimodal grain size distribution –more » the grain sizes ranging from a few microns to a few millimeters. One of the FSP conditions displayed an excellent improvement in fatigue life by an order of magnitude, while the other condition displayed an unexpectedly large scatter in fatigue lives. Detailed study of the fractured fatigue specimens by electron back scattered diffraction (EBSD) revealed that both, fatigue crack initiation and propagation, were intimately tied to the grain size as well as the grain misorientations in the microstructure.« less

Influence of friction stir processing on the room temperature fatigue cracking mechanisms of A356 aluminum alloy

DOE PAGES

Nelaturu, Phalgun; Jana, Saumyadeep; Mishra, Rajiv S.; ...

2018-01-11

Here, failure by fatigue is a common problem associated with cast aluminum alloys due to defects like shrinkage porosities, non-metallic inclusions, etc. Friction stir processing (FSP) has recently emerged as an effective technique for local modification of microstructure. This study investigates the fatigue crack initiation and growth mechanisms in cast and FSPed A356 aluminum alloy. Two sets of parameters were used to friction stir the cast alloy resulting in the complete modification the cast microstructure to a wrought microstructure. Both the FSPed microstructures exhibited severe abnormal grain growth (AGG) after heat treatment leading to a multimodal grain size distribution –more » the grain sizes ranging from a few microns to a few millimeters. One of the FSP conditions displayed an excellent improvement in fatigue life by an order of magnitude, while the other condition displayed an unexpectedly large scatter in fatigue lives. Detailed study of the fractured fatigue specimens by electron back scattered diffraction (EBSD) revealed that both, fatigue crack initiation and propagation, were intimately tied to the grain size as well as the grain misorientations in the microstructure.« less

Autogenous Transplantation for Replacing a Hopeless Tooth.

PubMed

Zakershahrak, Mehrsa; Moshari, Amirabbas; Vatanpour, Mehdi; Khalilak, Zohreh; Jalali Ara, Afsoon

2017-01-01

Autogenous tooth transplantation (ATT) is a simple and reasonable choice for replacing the missing teeth when a proper donor tooth is available. This report presents a case of successful ATT of a maxillary right third molar for replacement of mandibular right second molar with a concomitant endodontic-periodontal disease. The mandibular second molar was believed to be hopeless due to a severe damage to coronal tooth structure, inappropriate root canal treatment and apical radiolucency. After extraction of mandibular second molar and maxillary third molar (the donor), the tooth was re-implanted into the extracted socket of second molar site. Root canal therapy was then performed. After 3 years, clinical and radiographic examinations revealed satisfying results, with no signs and symptoms. The patient is asymptomatic and the transplanted tooth is still functional with no signs of marginal periodontal pathosis. Radiographies showed bone regeneration in the site of previous extensive periapical lesion, normal periodontal ligament with no signs of root resorption.

[A case of fibromyalgia treated with medical and autogenic training].

PubMed

Goto, Fumiyuki; Asama, Youji; Nakai, Kimiko

2005-12-01

Fibromyalgia, which is relatively rare, may include symptoms of dizziness, vertigo and tinnitus. Subject was 38 years old woman reporting vertigo and whole body pain. Cochleovestibular function was normal. Pain was gradually intensified during her outpatient clinic and she was admitted. Treatments including intramusclular injection of botulinus toxin and intravenous injection of steroid were applied. Psychological counseling and autogenic training were effective in relieving her pain and vertigo. During her admission, several spells of vertigo occurred but no nystagmus was found. The abnormality in proprioception and neural disintegration may be related to vertigo. Treatment should start as early as possible together with psychological therapy.

Direct voxel-based comparisons between grey matter shrinkage and glucose hypometabolism in chronic alcoholism

PubMed Central

Ritz, Ludivine; Segobin, Shailendra; Lannuzel, Coralie; Boudehent, Céline; Vabret, François; Eustache, Francis; Beaunieux, Hélène

2015-01-01

Alcoholism is associated with widespread brain structural abnormalities affecting mainly the frontocerebellar and the Papez’s circuits. Brain glucose metabolism has received limited attention, and few studies used regions of interest approach and showed reduced global brain metabolism predominantly in the frontal and parietal lobes. Even though these studies have examined the relationship between grey matter shrinkage and hypometabolism, none has performed a direct voxel-by-voxel comparison between the degrees of structural and metabolic abnormalities. Seventeen alcoholic patients and 16 control subjects underwent both structural magnetic resonance imaging and 18F-2-fluoro-deoxy-glucose-positron emission tomography examinations. Structural abnormalities and hypometabolism were examined in alcoholic patients compared with control subjects using two-sample t-tests. Then, these two patterns of brain damage were directly compared with a paired t-test. Compared to controls, alcoholic patients had grey matter shrinkage and hypometabolism in the fronto-cerebellar circuit and several nodes of Papez’s circuit. The direct comparison revealed greater shrinkage than hypometabolism in the cerebellum, cingulate cortex, thalamus and hippocampus and parahippocampal gyrus. Conversely, hypometabolism was more severe than shrinkage in the dorsolateral, premotor and parietal cortices. The distinct profiles of abnormalities found within the Papez’s circuit, the fronto-cerebellar circuit and the parietal gyrus in chronic alcoholism suggest the involvement of different pathological mechanisms. PMID:26661206

Direct voxel-based comparisons between grey matter shrinkage and glucose hypometabolism in chronic alcoholism.

PubMed

Ritz, Ludivine; Segobin, Shailendra; Lannuzel, Coralie; Boudehent, Céline; Vabret, François; Eustache, Francis; Beaunieux, Hélène; Pitel, Anne L

2016-09-01

Alcoholism is associated with widespread brain structural abnormalities affecting mainly the frontocerebellar and the Papez's circuits. Brain glucose metabolism has received limited attention, and few studies used regions of interest approach and showed reduced global brain metabolism predominantly in the frontal and parietal lobes. Even though these studies have examined the relationship between grey matter shrinkage and hypometabolism, none has performed a direct voxel-by-voxel comparison between the degrees of structural and metabolic abnormalities. Seventeen alcoholic patients and 16 control subjects underwent both structural magnetic resonance imaging and (18)F-2-fluoro-deoxy-glucose-positron emission tomography examinations. Structural abnormalities and hypometabolism were examined in alcoholic patients compared with control subjects using two-sample t-tests. Then, these two patterns of brain damage were directly compared with a paired t-test. Compared to controls, alcoholic patients had grey matter shrinkage and hypometabolism in the fronto-cerebellar circuit and several nodes of Papez's circuit. The direct comparison revealed greater shrinkage than hypometabolism in the cerebellum, cingulate cortex, thalamus and hippocampus and parahippocampal gyrus. Conversely, hypometabolism was more severe than shrinkage in the dorsolateral, premotor and parietal cortices. The distinct profiles of abnormalities found within the Papez's circuit, the fronto-cerebellar circuit and the parietal gyrus in chronic alcoholism suggest the involvement of different pathological mechanisms. © The Author(s) 2015.

On the Crack Bifurcation and Fanning of Crack Growth Data

NASA Technical Reports Server (NTRS)

Forman, Royce G.; Zanganeh, Mohammad

2015-01-01

Crack growth data obtained from ASTM load shedding method for different R values show some fanning especially for aluminum alloys. It is believed by the authors and it has been shown before that the observed fanning is due to the crack bifurcation occurs in the near threshold region which is a function of intrinsic properties of the alloy. Therefore, validity of the ASTM load shedding test procedure and results is confirmed. However, this position has been argued by some experimentalists who believe the fanning is an artifact of the test procedure and thus the obtained results are invalid. It has been shown that using a special test procedure such as using compressively pre-cracked specimens will eliminate the fanning effect. Since not using the fanned data fit can result in a significantly lower calculated cyclic life, design of a component, particularly for rotorcraft and propeller systems will considerably be impacted and therefore this study is of paramount importance. In this effort both test procedures i.e. ASTM load shedding and the proposed compressive pre-cracking have been used to study the fatigue crack growth behavior of compact tension specimens made of aluminum alloy 2524-T3. Fatigue crack growth paths have been closely observed using SEM machines to investigate the effects of compression pre-cracking on the crack bifurcation behavior. The results of this study will shed a light on resolving the existing argument by better understanding of near threshold fatigue crack growth behavior.

Polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials--a comparative study.

PubMed

Rüttermann, Stefan; Krüger, Sören; Raab, Wolfgang H-M; Janda, Ralf

2007-10-01

To investigate the polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials. The densities of SureFil (SU), CeramXMono (CM), Clearfil AP-X (CF), Solitaire 2 (SO), TetricEvoCeram (TE), and Filtek P60 (FT) were measured using the Archimedes' principle prior to and 15min after curing for 20, 40 and 60s and after 1h, 24h, 7 d, and 30 d storage at 37 degrees C in water. Volumetric changes (DeltaV) in percent after polymerization and after each storage period in water were calculated from the changes of densities. Water sorption and solubility were determined after 30 d for all specimens and their curing times. Two-way ANOVA was calculated for shrinkage and repeated measures ANOVA was calculated for hygroscopic expansion (p<0.05). DeltaV depended on filler load but not on curing time (SU approximately -2.0%, CM approximately -2.6%, CF approximately -2.1%, SO approximately -3.3%, TE approximately -1.7%, FT approximately -1.8%). Hygroscopic expansion depended on water sorption and solubility. Except for SU, all materials showed DeltaV approximately +1% after water storage. Polymerization shrinkage depended on the type of resin-based filling material but not on curing time. Shrinkage was not compensated by hygroscopic expansion.

Investigation of Helicopter Longeron Cracks

NASA Technical Reports Server (NTRS)

Newman, John A.; Baughman, James; Wallace, Terryl A.

2009-01-01

Four cracked longerons, containing a total of eight cracks, were provided for study. Cracked regions were cut from the longerons. Load was applied to open the cracks, enabling crack surface examination. Examination revealed that crack propagation was driven by fatigue loading in all eight cases. Fatigue crack initiation appears to have occurred on the top edge of the longerons near geometric changes that affect component bending stiffness. Additionally, metallurgical analysis has revealed a local depletion in alloying elements in the crack initiation regions that may be a contributing factor. Fatigue crack propagation appeared to be initially driven by opening-mode loading, but at a crack length of approximately 0.5 inches (12.7 mm), there is evidence of mixed-mode crack loading. For the longest cracks studied, shear-mode displacements destroyed crack-surface features of interest over significant portions of the crack surfaces.

Autogenic Feedback Training Exercise: Controlling Physiological Responses to Mitigate Motion Sickness

NASA Technical Reports Server (NTRS)

Walton, Nia; Spencer, Telissa; Cowings, Patricia; Toscano, William B.

2018-01-01

During space travel approximately 50 of the crew experience symptoms of motion sickness that can range from mild forms of nausea or dizziness to severe malaise and vomiting1. Developing an effective treatment for these symptoms has become a priority of the National Aeronautics and Space Administration (NASA). Autogenic-Feedback Training Exercise (AFTE) is a nonpharmacological countermeasure for mitigating motion sickness. It involves training subjects to control physiological responses in high stress environments2. The primary goal of this experiment is to evaluate the effectiveness of AFTE for increasing tolerance to motion sickness in high stress environments.

Eight-year follow-up of autogenous tooth transplantation involving multidisciplinary treatment.

PubMed

Candeiro, George T M; Alencar-Júnior, Emmanuel A; Scarparo, Henrique C; Furtado-Júnior, João H C; Gavini, Giulio; Caldeira, Celso L

2015-09-01

Although autogenous tooth transplantation is a widely reported procedure, its success is dependent on a number of factors. Here we describe the surgical technique, endodontic treatment and rehabilitation employed for a patient in whom a lower right third molar was transplanted to substitute an adjacent second molar with extensive caries. During an 8-year follow-up period, normal periodontal healing was observed and no infection, ankylosis or progressive resorption occurred. It may be concluded that transplantation of a third molar is a practicable approach for replacement of a lost permanent tooth, with restoration of esthetics and function.

Effect of current and speed on porosity in autogenous Tungsten Inert Gas (TIG) welding of aluminum alloys A1100 butt joint

NASA Astrophysics Data System (ADS)

Milyardi, Indra; Sunar Baskoro, Ario

2018-04-01

Autogenous Tungsten Inert Gas (TIG) welding has been conducted on aluminum alloy A1100. The purpose of this research is to determine the proper current and speed of autogenous TIG welding with butt joint pattern. Variations on welding current are 150 A, 155 A, and 160 A with the variations on welding speed are 1 mm/seconds, 1.1 mm/seconds, 1.2 mm/seconds. The welded results were tested using non-destructive test (NDT) method using X-Ray radiography. After the test, it is found that the appropriate current for the best result without porosity can be achieved using the welding parameter of welding current of 160 A and the welding speed of 1.1 mm seconds.

Thoracoscopic CO laser coagulation shrinkage of blebs in treatment of spontaneous pneumothorax

NASA Astrophysics Data System (ADS)

Sensaki, Koji; Arai, Tsunenori; Kikuchi, Keiichi; Takagi, Keigo; Tanaka, Susumu; Kikuchi, Makoto

1992-06-01

Spontaneous pneumothorax is a common disease in young people. Operative intervention has been done in most of the recurrent cases. Recently thoracoscopic treatment has been tested as a less invasive treatment modarity. We adopted carbon monoxide (CO) laser for thoracoscopic treatment of recurrent spontaneous pneumothorax. CO laser (wavelength; 5.4 micrometers ) could be delivered by chalcogenide glass (As - S) covered with a teflon sheath and ZnSe fiber tip. The sterilized flexible bronchoscope was inserted through the thoracoscopic outer sheath under local anesthesia. Shrinkage of blebs was obtained by non-contact method of CO laser irradiation. Laser power at the tip was 2.5 - 5 W and irradiation duration was 0.5 s each. Excellent shrinkage of bleb and bulla could be obtained by CO laser without perforation complication. Advantages of CO laser as a thoracoscopic treatment were: (1) capability of fiber delivery (flexible thoracoscopy was easy to operate and clear to visualize the blebs which were frequently found at the apical portion of the lung, and (2) shallow extinction length (good shrinkage of blebs, low risk of perforation, and thin layer of carbonization). In conclusion, our new technique of thoracoscopic CO laser irradiation was found to be a safe and effective treatment of spontaneous pneumothorax.

Statistical Mechanics Provides Novel Insights into Microtubule Stability and Mechanism of Shrinkage

PubMed Central

Jain, Ishutesh; Inamdar, Mandar M.; Padinhateeri, Ranjith

2015-01-01

Microtubules are nano-machines that grow and shrink stochastically, making use of the coupling between chemical kinetics and mechanics of its constituent protofilaments (PFs). We investigate the stability and shrinkage of microtubules taking into account inter-protofilament interactions and bending interactions of intrinsically curved PFs. Computing the free energy as a function of PF tip position, we show that the competition between curvature energy, inter-PF interaction energy and entropy leads to a rich landscape with a series of minima that repeat over a length-scale determined by the intrinsic curvature. Computing Langevin dynamics of the tip through the landscape and accounting for depolymerization, we calculate the average unzippering and shrinkage velocities of GDP protofilaments and compare them with the experimentally known results. Our analysis predicts that the strength of the inter-PF interaction (Ems) has to be comparable to the strength of the curvature energy (Emb) such that Ems−Emb≈1kBT, and questions the prevalent notion that unzippering results from the domination of bending energy of curved GDP PFs. Our work demonstrates how the shape of the free energy landscape is crucial in explaining the mechanism of MT shrinkage where the unzippered PFs will fluctuate in a set of partially peeled off states and subunit dissociation will reduce the length. PMID:25692909

Impaired decision-making and brain shrinkage in alcoholism.

PubMed

Le Berre, A-P; Rauchs, G; La Joie, R; Mézenge, F; Boudehent, C; Vabret, F; Segobin, S; Viader, F; Allain, P; Eustache, F; Pitel, A-L; Beaunieux, H

2014-03-01

Alcohol-dependent individuals usually favor instant gratification of alcohol use and ignore its long-term negative consequences, reflecting impaired decision-making. According to the somatic marker hypothesis, decision-making abilities are subtended by an extended brain network. As chronic alcohol consumption is known to be associated with brain shrinkage in this network, the present study investigated relationships between brain shrinkage and decision-making impairments in alcohol-dependent individuals early in abstinence using voxel-based morphometry. Thirty patients performed the Iowa Gambling Task and underwent a magnetic resonance imaging investigation (1.5T). Decision-making performances and brain data were compared with those of age-matched healthy controls. In the alcoholic group, a multiple regression analysis was conducted with two predictors (gray matter [GM] volume and decision-making measure) and two covariates (number of withdrawals and duration of alcoholism). Compared with controls, alcoholics had impaired decision-making and widespread reduced gray matter volume, especially in regions involved in decision-making. The regression analysis revealed links between high GM volume in the ventromedial prefrontal cortex, dorsal anterior cingulate cortex and right hippocampal formation, and high decision-making scores (P<0.001, uncorrected). Decision-making deficits in alcoholism may result from impairment of both emotional and cognitive networks. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Statistical Study to Evaluate the Effect of Processing Variables on Shrinkage Incidence During Solidification of Nodular Cast Irons

NASA Astrophysics Data System (ADS)

Gutiérrez, J. M.; Natxiondo, A.; Nieves, J.; Zabala, A.; Sertucha, J.

2017-04-01

The study of shrinkage incidence variations in nodular cast irons is an important aspect of manufacturing processes. These variations change the feeding requirements on castings and the optimization of risers' size is consequently affected when avoiding the formation of shrinkage defects. The effect of a number of processing variables on the shrinkage size has been studied using a layout specifically designed for this purpose. The β parameter has been defined as the relative volume reduction from the pouring temperature up to the room temperature. It is observed that shrinkage size and β decrease as effective carbon content increases and when inoculant is added in the pouring stream. A similar effect is found when the parameters selected from cooling curves show high graphite nucleation during solidification of cast irons for a given inoculation level. Pearson statistical analysis has been used to analyze the correlations among all involved variables and a group of Bayesian networks have been subsequently built so as to get the best accurate model for predicting β as a function of the input processing variables. The developed models can be used in foundry plants to study the shrinkage incidence variations in the manufacturing process and to optimize the related costs.

Treatment of active unicameral bone cysts with percutaneous injection of demineralized bone matrix and autogenous bone marrow.

PubMed

Rougraff, Bruce T; Kling, Thomas J

2002-06-01

The treatment of unicameral bone cysts varies from open bone-grafting procedures to percutaneous injection of corticosteroids or bone marrow. The purpose of this study was to evaluate the feasibility and effectiveness of percutaneous injection of a mixture of demineralized bone matrix and autogenous bone marrow for the treatment of simple bone cysts. Twenty-three patients with an active unicameral bone cyst were treated with trephination and injection of allogeneic demineralized bone matrix and autogenous bone marrow. The patients were followed for an average of fifty months (range, thirty to eighty-one months), at which time pain, function, and radiographic signs of resolution of the cyst were assessed. The average time until the patients had pain relief was five weeks, and the average time until the patients returned to full, unrestricted activities was six weeks. Bone-healing at the site of the injection was first seen radiographically at three to six months. No patient had a pathologic fracture during this early bone-healing stage. Cortical remodeling was seen radiographically by six to nine months, and after one year the response was usually complete, changing very little from then on. Five patients required a second injection because of recurrence of the cyst, and all five had a clinically and radiographically quiescent cyst after an average of thirty-six additional months of follow-up. Seven of the twenty-three patients had incomplete healing manifested by small, persistent radiolucent areas within the original cyst. None of these cysts increased in size or resulted in pain or fracture. Percutaneous injection of allogeneic demineralized bone matrix and autogenous bone marrow is an effective treatment for unicameral bone cysts.

[Autogenous platelet-rich plasma gel with acellular xenogeneic dermal matrix for treatment of deep II degree burns].

PubMed

Hao, Tianzhi; Zhu, Jingmin; Hu, Wenbo; Zhang, Hua; Gao, Zhenhui; Wen, Xuehui; Zhou, Zhi; Lu, Gang; Liu, Jingjie; Li, Wen

2010-06-01

To investigate the effectiveness of autogenous platelet-rich plasma (PRP) gel with acellular xenogeneic dermal matrix in the treatment of deep II degree burns. From January 2007 to December 2009, 30 cases of deep II degree burns were treated. There were 19 males and 11 females with an average age of 42.5 years (range, 32-57 years). The burn area was 10% to 48% of total body surface area. The time from burn to hospitalization was 30 minutes to 8 hours. All patients were treated with tangential excision surgery, one side of the wounds were covered with autogenous PRP gel and acellular xenogeneic dermal matrix (PRP group), the other side of the wounds were covered with acellular xenogeneic dermal matrix only (control group). The healing rate, healing time, infection condition, and scar formation were observed. At 7 days after operation, the infection rate in PRP group (6.7%, 2/30) was significantly lower than that in control group (16.7%, 5/30, P < 0.05). The healing times were (18 +/- 4) days and (22 +/- 4) days respectively in PRP group and control group, showing significant difference (P < 0.05). The healing rates at 14 days and 21 days were 75% +/- 7% and 88% +/- 5% in PRP group, were 62% +/- 15% and 73% +/- 7% in control group, showing significant difference (P < 0.05). RPR group was superior to control group in elasticity, color, appearance, softness, scar formation, and healing quality. Autogenous PRP gel with acellular xenogeneic dermal matrix can accelerate the wound healing of deep II degree burns as well as alleviate the scar proliferation.

[Autogenic training (AT)--respiratory feedback (RFB); similarities and limits in general practice oriented differential indications].

PubMed

Barolin, G S

1988-04-15

Autogenic Training (AT) is not merely a "relaxation exercise". We quote five dimensions of AT that should by clearly differentiated: 1) concentration, 2) relaxation, 3) vegetative switch toward the hypnoid state, 4) dynamising reprise exercise. 5) holistic inclusion in a complex psychotherapeutical concept. We consider the self induced hypnoid state plus dynamising reprise exercise as the main components for the beneficial effect of AT. The hynoid state has its neurophysiological definition as a third human state of consciousness. The reprise exercise is more than making it abolish, but has its own therapeutical values: dynamisation. Respiratory feedback (RBF - a special kind of biofeedback) has the factors relaxation and vegetative switch towards hypnoid in common with autogenic training. Where these components are specially requested, RFB proves valuable in therapy. In other indications however AT is of much better use. Namely: where the educational value of mutation, self-concentration and the therapeutic context is of predominant importance. AT as well as RFB may be considered "misused" in having them replace the therapeutical and understanding conversation between doctor and patients, in a mechanistic way. As a slogan it may be said: AT goes deeper, RFB goes quicker.

Comparison of the effect of three autogenous bone harvesting methods on cell viability in rabbits

PubMed Central

Moradi Haghgoo, Janet; Arabi, Seyed Reza; Hosseinipanah, Seyyed Mohammad; Solgi, Ghasem; Rastegarfard, Neda; Farhadian, Maryam

2017-01-01

Background. This study was designed to compare the viability of autogenous bone grafts, harvested using different methods, in order to determine the best harvesting technique with respect to more viable cells. Methods. In this animal experimental study, three harvesting methods, including manual instrument (chisel), rotary device and piezosurgery, were used for harvesting bone grafts from the lateral body of the mandible on the left and right sides of 10 rabbits. In each group, 20 bone samples were collected and their viability was assessed using MTS kit. Statistical analyses, including ANOVA and post hoc Tukey tests, were used for evaluating significant differences between the groups. Results. One-way ANOVA showed significant differences between all the groups (P=0.000). Data analysis using post hoc Tukey tests indicated that manual instrument and piezosurgery had no significant differences with regard to cell viability (P=0.749) and the cell viability in both groups was higher than that with the use of a rotary instrument (P=0.000). Conclusion. Autogenous bone grafts harvested with a manual instrument and piezosurgery had more viable cells in comparison to the bone chips harvested with a rotary device. PMID:28748046

Recent evaluations of crack-opening-area in circumferentially cracked pipes

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

Rahman, S.; Brust, F.; Ghadiali, N.

1997-04-01

Leak-before-break (LBB) analyses for circumferentially cracked pipes are currently being conducted in the nuclear industry to justify elimination of pipe whip restraints and jet shields which are present because of the expected dynamic effects from pipe rupture. The application of the LBB methodology frequently requires calculation of leak rates. The leak rates depend on the crack-opening area of the through-wall crack in the pipe. In addition to LBB analyses which assume a hypothetical flaw size, there is also interest in the integrity of actual leaking cracks corresponding to current leakage detection requirements in NRC Regulatory Guide 1.45, or for assessingmore » temporary repair of Class 2 and 3 pipes that have leaks as are being evaluated in ASME Section XI. The objectives of this study were to review, evaluate, and refine current predictive models for performing crack-opening-area analyses of circumferentially cracked pipes. The results from twenty-five full-scale pipe fracture experiments, conducted in the Degraded Piping Program, the International Piping Integrity Research Group Program, and the Short Cracks in Piping and Piping Welds Program, were used to verify the analytical models. Standard statistical analyses were performed to assess used to verify the analytical models. Standard statistical analyses were performed to assess quantitatively the accuracy of the predictive models. The evaluation also involved finite element analyses for determining the crack-opening profile often needed to perform leak-rate calculations.« less

Allogenic and Autogenic Signals in the Stratigraphic Record of the Deep-Sea Bengal Fan.

PubMed

Blum, Mike; Rogers, Kimberly; Gleason, James; Najman, Yani; Cruz, Jarrett; Fox, Lyndsey

2018-05-22

The Himalayan-sourced Ganges-Brahmaputra river system and the deep-sea Bengal Fan represent Earth's largest sediment-dispersal system. Here we present detrital zircon U-Pb provenance data from Miocene to middle Pleistocene Bengal Fan turbidites, and evaluate the influence of allogenic forcing vs. autogenic processes on signal propagation from the Himalaya to the deep sea. Our data record the strong tectonic and climatic forcing characteristic of the Himalayan system: after up to 2500 km of river transport, and >1400 km of transport by turbidity currents, the U-Pb record faithfully represents Himalayan sources. Moreover, specific U-Pb populations record Miocene integration of the Brahmaputra drainage with the Asian plate, as well as the rapid Plio-Pleistocene incision through, and exhumation of, the eastern Himalayan syntaxis. The record is, however, biased towards glacial periods when rivers were extended across the shelf in response to climate-forced sea-level fall, and discharged directly to slope canyons. Finally, only part of the record represents a Ganges or Brahmaputra provenance end-member, and most samples represent mixing from the two systems. Mixing or the lack thereof likely represents the fingerprint of autogenic delta-plain avulsions, which result in the two rivers delivering sediment separately to a shelf-margin canyon or merging together as they do today.

Discrete crack growth analysis methodology for through cracks in pressurized fuselage structures

NASA Technical Reports Server (NTRS)

Potyondy, David O.; Wawrzynek, Paul A.; Ingraffea, Anthony R.

1994-01-01

A methodology for simulating the growth of long through cracks in the skin of pressurized aircraft fuselage structures is described. Crack trajectories are allowed to be arbitrary and are computed as part of the simulation. The interaction between the mechanical loads acting on the superstructure and the local structural response near the crack tips is accounted for by employing a hierarchical modeling strategy. The structural response for each cracked configuration is obtained using a geometrically nonlinear shell finite element analysis procedure. Four stress intensity factors, two for membrane behavior and two for bending using Kirchhoff plate theory, are computed using an extension of the modified crack closure integral method. Crack trajectories are determined by applying the maximum tangential stress criterion. Crack growth results in localized mesh deletion, and the deletion regions are remeshed automatically using a newly developed all-quadrilateral meshing algorithm. The effectiveness of the methodology and its applicability to performing practical analyses of realistic structures is demonstrated by simulating curvilinear crack growth in a fuselage panel that is representative of a typical narrow-body aircraft. The predicted crack trajectory and fatigue life compare well with measurements of these same quantities from a full-scale pressurized panel test.

Autogenic Feedback Training Applications for Man in Space

NASA Technical Reports Server (NTRS)

Cowings, Patricia S.; Wade, Charles E. (Technical Monitor)

1994-01-01

Finding an effective treatment for the motion sickness-like symptoms that occur in space has become a high priority for NASA. This paper reviews the back-round research and procedures of an experiment designed to prevent space motion sickness in shuttle crewmembers. The preventive method used, Autogenic - Feedback Training (AFT) involves training subjects to control voluntarily several of their own physiological responses to environmental stressors. AFT has been used reliably to increase tolerance to motion sickness during around based tests in over 300 men and women under a variety of conditions that induce motion sickness, and preliminary evidence from space suggests that AFT may be an effective treatment for space motion sickness as well. Other applications of AFT described include; (1) a potential treatment for post flight orthostatic intolerance, a serious biomedical problem resulting from long duration exposure to micro-g and (2) improving pilot performance during emergency flying conditions.

Replica-based Crack Inspection

NASA Technical Reports Server (NTRS)

Newman, John A.; Smith, Stephen W.; Piascik, R. S.; Willard, Scott A.; Dawicke, David S.

2007-01-01

A surface replica-based crack inspection method has recently been developed for use in Space Shuttle main engine (SSME) hydrogen feedline flowliners. These flowliners exist to ensure favorable flow of liquid hydrogen over gimble joint bellows, and consist of two rings each containing 38 elongated slots. In the summer of 2002, multiple cracks ranging from 0.1 inches to 0.6 inches long were discovered; each orbiter contained at least one cracked flowliner. These long cracks were repaired and eddy current inspections ensured that no cracks longer than 0.075 inches were present. However, subsequent fracture-mechanics review of flight rationale required detection of smaller cracks, and was the driving force for development of higher-resolution inspection method. Acetate tape surface replicas have been used for decades to detect and monitor small cracks. However, acetate tape replicas have primarily been limited to laboratory specimens because complexities involved in making these replicas - requiring acetate tape to be dissolved with acetone - are not well suited for a crack inspection tool. More recently developed silicon-based replicas are better suited for use as a crack detection tool. A commercially available silicon-based replica product has been determined to be acceptable for use in SSME hydrogen feedlines. A method has been developed using this product and a scanning electron microscope for analysis, which can find cracks as small as 0.005 inches and other features (e.g., pits, scratches, tool marks, etc.) as small as 0.001 inches. The resolution of this method has been validated with dozens of cracks generated in a laboratory setting and this method has been used to locate 55 cracks (ranging in size from 0.040 inches to 0.004 inches) on space flight hardware. These cracks were removed by polishing away the cracked material and a second round of replicas confirmed the repair.

Mining pharmacovigilance data using Bayesian logistic regression with James-Stein type shrinkage estimation.

PubMed

An, Lihua; Fung, Karen Y; Krewski, Daniel

2010-09-01

Spontaneous adverse event reporting systems are widely used to identify adverse reactions to drugs following their introduction into the marketplace. In this article, a James-Stein type shrinkage estimation strategy was developed in a Bayesian logistic regression model to analyze pharmacovigilance data. This method is effective in detecting signals as it combines information and borrows strength across medically related adverse events. Computer simulation demonstrated that the shrinkage estimator is uniformly better than the maximum likelihood estimator in terms of mean squared error. This method was used to investigate the possible association of a series of diabetic drugs and the risk of cardiovascular events using data from the Canada Vigilance Online Database.

Identification of cracks in thick beams with a cracked beam element model

NASA Astrophysics Data System (ADS)

Hou, Chuanchuan; Lu, Yong

2016-12-01

The effect of a crack on the vibration of a beam is a classical problem, and various models have been proposed, ranging from the basic stiffness reduction method to the more sophisticated model involving formulation based on the additional flexibility due to a crack. However, in the damage identification or finite element model updating applications, it is still common practice to employ a simple stiffness reduction factor to represent a crack in the identification process, whereas the use of a more realistic crack model is rather limited. In this paper, the issues with the simple stiffness reduction method, particularly concerning thick beams, are highlighted along with a review of several other crack models. A robust finite element model updating procedure is then presented for the detection of cracks in beams. The description of the crack parameters is based on the cracked beam flexibility formulated by means of the fracture mechanics, and it takes into consideration of shear deformation and coupling between translational and longitudinal vibrations, and thus is particularly suitable for thick beams. The identification procedure employs a global searching technique using Genetic Algorithms, and there is no restriction on the location, severity and the number of cracks to be identified. The procedure is verified to yield satisfactory identification for practically any configurations of cracks in a beam.

Fast generation of computer-generated holograms using wavelet shrinkage.

PubMed

Shimobaba, Tomoyoshi; Ito, Tomoyoshi

2017-01-09

Computer-generated holograms (CGHs) are generated by superimposing complex amplitudes emitted from a number of object points. However, this superposition process remains very time-consuming even when using the latest computers. We propose a fast calculation algorithm for CGHs that uses a wavelet shrinkage method, eliminating small wavelet coefficient values to express approximated complex amplitudes using only a few representative wavelet coefficients.

Stability of implants placed in augmented posterior mandible after alveolar osteotomy using resorbable nonceramic hydroxyapatite or intraoral autogenous bone: 12-month follow-up.

PubMed

Dottore, Alexandre M; Kawakami, Paulo Y; Bechara, Karen; Rodrigues, Jose Augusto; Cassoni, Alessandra; Figueiredo, Luciene C; Piattelli, Adriano; Shibli, Jamil Awad

2014-06-01

This prospective, controlled split-mouth study evaluated the stability of dental implants placed in the augmented mandibular areas with alveolar segmental "sandwich" osteotomies using nonceramic hydroxyapatite (ncHA) or autogenous bone. This study included 11 bilaterally partially edentulous mandibular patients in a split-mouth design. Alveolar augmentation osteotomies were performed bilaterally with interpositional ncHA graft (test group) or interpositional intraoral autogenous bone graft (control group). After 6 months of healing, four implants (two implants in each side) were placed in each patient. Forty-four implants were inserted and loaded after 6-month healing period. At 1-year follow-up, radiographic, prosthetic, and resonance frequency analysis parameters were assessed. Success criteria included absence of pain, sensitivity, suppuration, and implant mobility; absence of continuous peri-implant radiolucency; and distance between the implant shoulder and the first visible bone contact (DIB) < 2 mm. After a 1-year loading period, the overall implant survival rate was 95.45%, with two implant losses (one of each group). Among the surviving implants (42 out of 44), two did not fulfill the success criteria; therefore, the implant success was 90.90%. DIB was 0.71 ± 0.70 and 0.84 ± 0.72 mm for ncHA and autogenous bone grafts, respectively (p > .05). Implant stability measurements were similar between the groups during the 12-month follow-up (p > .05). Within the limits of this study, the implants placed either in sites augmented with ncHA or autogenous bone seem to represent a safe and successful procedure, at least, after 12-month follow-up. © 2012 Wiley Periodicals, Inc.

Muscle activity patterns and spinal shrinkage in office workers using a sit-stand workstation versus a sit workstation.

PubMed

Gao, Ying; Cronin, Neil J; Pesola, Arto J; Finni, Taija

2016-10-01

Reducing sitting time by means of sit-stand workstations is an emerging trend, but further evidence is needed regarding their health benefits. This cross-sectional study compared work time muscle activity patterns and spinal shrinkage between office workers (aged 24-62, 58.3% female) who used either a sit-stand workstation (Sit-Stand group, n = 10) or a traditional sit workstation (Sit group, n = 14) for at least the past three months. During one typical workday, muscle inactivity and activity from quadriceps and hamstrings were monitored using electromyography shorts, and spinal shrinkage was measured using stadiometry before and after the workday. Compared with the Sit group, the Sit-Stand group had less muscle inactivity time (66.2 ± 17.1% vs. 80.9 ± 6.4%, p = 0.014) and more light muscle activity time (26.1 ± 12.3% vs. 14.9 ± 6.3%, p = 0.019) with no significant difference in spinal shrinkage (5.62 ± 2.75 mm vs. 6.11 ± 2.44 mm). This study provides evidence that working with sit-stand workstations can promote more light muscle activity time and less inactivity without negative effects on spinal shrinkage. Practitioner Summary: This cross-sectional study compared the effects of using a sit-stand workstation to a sit workstation on muscle activity patterns and spinal shrinkage in office workers. It provides evidence that working with a sit-stand workstation can promote more light muscle activity time and less inactivity without negative effects on spinal shrinkage.

Multiple-Shrinkage Multinomial Probit Models with Applications to Simulating Geographies in Public Use Data.

PubMed

Burgette, Lane F; Reiter, Jerome P

2013-06-01

Multinomial outcomes with many levels can be challenging to model. Information typically accrues slowly with increasing sample size, yet the parameter space expands rapidly with additional covariates. Shrinking all regression parameters towards zero, as often done in models of continuous or binary response variables, is unsatisfactory, since setting parameters equal to zero in multinomial models does not necessarily imply "no effect." We propose an approach to modeling multinomial outcomes with many levels based on a Bayesian multinomial probit (MNP) model and a multiple shrinkage prior distribution for the regression parameters. The prior distribution encourages the MNP regression parameters to shrink toward a number of learned locations, thereby substantially reducing the dimension of the parameter space. Using simulated data, we compare the predictive performance of this model against two other recently-proposed methods for big multinomial models. The results suggest that the fully Bayesian, multiple shrinkage approach can outperform these other methods. We apply the multiple shrinkage MNP to simulating replacement values for areal identifiers, e.g., census tract indicators, in order to protect data confidentiality in public use datasets.

Measurement and analysis of critical crack tip processes during fatigue crack growth

NASA Technical Reports Server (NTRS)

Davidson, D. L.; Hudak, S. J.; Dexter, R. J.

1985-01-01

The mechanics of fatigue crack growth under constant-amplitudes and variable-amplitude loading were examined. Critical loading histories involving relatively simple overload and overload/underload cycles were studied to provide a basic understanding of the underlying physical processes controlling crack growth. The material used for this study was 7091-T7E69, a powder metallurgy aluminum alloy. Local crack-tip parameters were measured at various times before, during, and after the overloads, these include crack-tip opening loads and displacements, and crack-tip strain fields. The latter were useed, in combination with the materials cyclic and monotonic stress-strain properties, to compute crack-tip residual stresses. The experimental results are also compared with analytical predictions obtained using the FAST-2 computer code. The sensitivity of the analytical model to constant-amplitude fatigue crack growth rate properties and to through-thickness constrain are studied.

Evaluating shrinkage of wood propellers in a high-temperature environment

Treesearch

Richard Bergman; Robert J. Ross

2008-01-01

Minimizing wood shrinkage is a priority for many wood products in use, particularly engineered products manufactured to close tolerances, such as wood propellers for unmanned surveillance aircraft used in military operations. Those currently in service in the Middle East are experiencing performance problems as a consequence of wood shrinking during long-term storage...

Evaluation of shrinkage polymerization and temperature of different acrylic resins used to splinting transfer copings in indirect impression technique

NASA Astrophysics Data System (ADS)

Franco, Ana Paula G. O.; Karam, Leandro Z.; Galvão, José R.; Kalinowski, Hypolito J.

2015-09-01

The aim of the present study was evaluate the shrinkage polymerization and temperature of different acrylic resins used to splinting transfer copings in indirect impression technique. Two implants were placed in an artificial bone, with the two transfer copings joined with dental floss and acrylic resins; two dental resins are used. Measurements of deformation and temperature were performed with Fiber Braggs grating sensor for 17 minutes. The results revealed that one type of resin shows greater values of polymerization shrinkage than the other. Pattern resins did not present lower values of shrinkage, as usually reported by the manufacturer.

Modeling and Analysis of Process Parameters for Evaluating Shrinkage Problems During Plastic Injection Molding of a DVD-ROM Cover

NASA Astrophysics Data System (ADS)

Öktem, H.

2012-01-01

Plastic injection molding plays a key role in the production of high-quality plastic parts. Shrinkage is one of the most significant problems of a plastic part in terms of quality in the plastic injection molding. This article focuses on the study of the modeling and analysis of the effects of process parameters on the shrinkage by evaluating the quality of the plastic part of a DVD-ROM cover made with Acrylonitrile Butadiene Styrene (ABS) polymer material. An effective regression model was developed to determine the mathematical relationship between the process parameters (mold temperature, melt temperature, injection pressure, injection time, and cooling time) and the volumetric shrinkage by utilizing the analysis data. Finite element (FE) analyses designed by Taguchi (L27) orthogonal arrays were run in the Moldflow simulation program. Analysis of variance (ANOVA) was then performed to check the adequacy of the regression model and to determine the effect of the process parameters on the shrinkage. Experiments were conducted to control the accuracy of the regression model with the FE analyses obtained from Moldflow. The results show that the regression model agrees very well with the FE analyses and the experiments. From this, it can be concluded that this study succeeded in modeling the shrinkage problem in our application.

Patella fractures associated with accelerated ACL rehabilitation in patients with autogenous patella tendon reconstructions.

PubMed

Brownstein, B; Bronner, S

1997-09-01

Patella fracture is a recognized complication of ACL reconstruction with an autogenous patella tendon graft. Typically, fracture occurs as a result of a fall. The incidence of fracture is approximately 0.5%. Accelerated rehabilitation protocols can place stress on the patella, especially in the initial stages of recovery. Therapists are reminded to observe constraints placed on patients by biological tissues, recovering neuromuscular status, and previous level of conditioning. Rehabilitation protocols should be revised according to these factors.

Dimensional stability of concrete slabs on grade.

DOT National Transportation Integrated Search

2012-10-01

Drying shrinkage is one of the major causes of cracking in concrete slabs on grade. The moisture : difference between the top and bottom surface of the slabs causes a dimensional or shrinkage gradient : to develop through the depth of the slabs...

Acoustic properties of interfacial debonding and their relationship with shrinkage stress in Class-I restorations.

PubMed

Yang, Bo; Guo, Jiawen; Huang, Qin; Heo, Young; Fok, Alex; Wang, Yan

2016-06-01

(1) To investigate the properties, and their correlations, of the acoustic emission (AE) from interfacial debonding of Class-I composite restorations during curing. (2) To establish the relationship between the theoretical shrinkage stress and the level of interfacial debonding in such restorations as determined by AE measurement. An AE sensor was attached onto the surface of human molars with a Class-I composite restoration of 4mm (length)×3mm (width)×2mm (depth) to monitor their debonding from the tooth tissues during curing. Background signals were analyzed before curing to determine the threshold amplitude for noise filtering. Three groups (n=3) of composites with different levels of shrinkage were tested: (1) Z100™, (2) Filtek™ Z250, and (3) Filtek™ LS. All restorations were cured with an LED blue light operated at 1200mW/cm(2) for 40s. AE signals were recorded continuously from the start of curing for 10min, and their frequency, amplitude and duration were analyzed. Finally, the cumulative number of AE events was compared with the theoretical maximum shrinkage stress that could be generated by the composites. The amplitude of the background signals was below 30dB, which was chosen as the threshold for noise filtering. The amplitude of all debonding events ranged from 30 to 50dB, and their duration was below 100μs. The peak frequency had two main bands: 100-200kHz and 700-800kHz. The duration time increased with increasing amplitude, but no correlation was found between the peak frequency and the other two parameters. The cumulative number of AE events was 30.67±2.31, 14.00±7.81 and 5.67±3.06 for Z100, Z250 and LS, respectively, which corresponded well with the theoretical maximum shrinkage stress they could produce, i.e. 42.5, 97.5 and 182.5MPa. R(2)=0.9955 for the linear regression. The theoretical shrinkage stress below which no AE events were detected was about 14.3MPa. For the materials considered, the amount of interfacial debonding produced

Use of Empirical Estimates of Shrinkage in Multiple Regression: A Caution.

ERIC Educational Resources Information Center

Kromrey, Jeffrey D.; Hines, Constance V.

1995-01-01

The accuracy of four empirical techniques to estimate shrinkage in multiple regression was studied through Monte Carlo simulation. None of the techniques provided unbiased estimates of the population squared multiple correlation coefficient, but the normalized jackknife and bootstrap techniques demonstrated marginally acceptable performance with…

Crack layer theory

NASA Technical Reports Server (NTRS)

Chudnovsky, A.

1984-01-01

A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

Crack layer theory

NASA Technical Reports Server (NTRS)

Chudnovsky, A.

1987-01-01

A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

Shrinkage covariance matrix approach based on robust trimmed mean in gene sets detection

NASA Astrophysics Data System (ADS)

Karjanto, Suryaefiza; Ramli, Norazan Mohamed; Ghani, Nor Azura Md; Aripin, Rasimah; Yusop, Noorezatty Mohd

2015-02-01

Microarray involves of placing an orderly arrangement of thousands of gene sequences in a grid on a suitable surface. The technology has made a novelty discovery since its development and obtained an increasing attention among researchers. The widespread of microarray technology is largely due to its ability to perform simultaneous analysis of thousands of genes in a massively parallel manner in one experiment. Hence, it provides valuable knowledge on gene interaction and function. The microarray data set typically consists of tens of thousands of genes (variables) from just dozens of samples due to various constraints. Therefore, the sample covariance matrix in Hotelling's T2 statistic is not positive definite and become singular, thus it cannot be inverted. In this research, the Hotelling's T2 statistic is combined with a shrinkage approach as an alternative estimation to estimate the covariance matrix to detect significant gene sets. The use of shrinkage covariance matrix overcomes the singularity problem by converting an unbiased to an improved biased estimator of covariance matrix. Robust trimmed mean is integrated into the shrinkage matrix to reduce the influence of outliers and consequently increases its efficiency. The performance of the proposed method is measured using several simulation designs. The results are expected to outperform existing techniques in many tested conditions.

Modelling and measurement of crack closure and crack growth following overloads and underloads

NASA Technical Reports Server (NTRS)

Dexter, R. J.; Hudak, S. J.; Davidson, D. L.

1989-01-01

Ignoring crack growth retardation following overloads can result in overly conservative life predictions in structures subjected to variable amplitude fatigue loading. Crack closure is believed to contribute to the crack growth retardation, although the specific closure mechanism is dabatable. The delay period and corresponding crack growth rate transients following overload and overload/underload cycles were systematically measured as a function of load ratio and overload magnitude. These responses are correlated in terms of the local 'driving force' for crack growth, i.e. the effective stress intensity factor range. Experimental results are compared with the predictions of a Dugdale-type (1960) crack closure model, and improvements in the model are suggested.

Depth of cure, flexural properties and volumetric shrinkage of low and high viscosity bulk-fill giomers and resin composites.

PubMed

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

2017-03-31

The purpose of this study was to investigate the depth of cure, flexural properties and volumetric shrinkage of low and high viscosity bulk-fill giomers and resin composites. Depth of cure and flexural properties were determined according to ISO 4049, and volumetric shrinkage was measured using a dilatometer. The depths of cure of giomers were significantly lower than those of resin composites, regardless of photo polymerization times. No difference in flexural strength and modulus was found among either high or low viscosity bulk fill materials. Volumetric shrinkage of low and high viscosity bulk-fill resin composites was significantly less than low and high viscosity giomers. Depth of cure of both low and high viscosity bulk-fill materials is time dependent. Flexural strength and modulus of high viscosity or low viscosity bulk-fill giomer or resin composite materials are not different for their respective category. Resin composites exhibited less polymerization shrinkage than giomers.

Performance of portland limestone cements: Cements designed to be more sustainable that include up to 15% limestone addition

NASA Astrophysics Data System (ADS)

Barrett, Timothy J.

increasing the number of very fine limestone particles. This results in the cements tested having similar autogenous shrinkage development in the PLC systems compared to the OPC, with slightly less shrinkage in the PLC-slag system. The stress that develops when this shrinkage is restrained is very similar in comparing the OPC, PLC and PLC-slag systems and the PLC mixture tends to crack at a similar or slightly earlier times.

Alveolar ridge preservation of an extraction socket using autogenous tooth bone graft material for implant site development: prospective case series

PubMed Central

Yun, Pil-Young; Um, In-Woong; Lee, Hyo-Jung; Yi, Yang-Jin; Bae, Ji-Hyun; Lee, Junho

2014-01-01

This case series evaluated the clinical efficacy of autogenous tooth bone graft material (AutoBT) in alveolar ridge preservation of an extraction socket. Thirteen patients who received extraction socket graft using AutoBT followed by delayed implant placements from Nov. 2008 to Aug. 2010 were evaluated. A total of fifteen implants were placed. The primary and secondary stability of the placed implants were an average of 58 ISQ and 77.9 ISQ, respectively. The average amount of crestal bone loss around the implant was 0.05 mm during an average of 22.5 months (from 12 to 34 months) of functional loading. Newly formed tissues were evident from the 3-month specimen. Within the limitations of this case, autogenous tooth bone graft material can be a favorable bone substitute for extraction socket graft due to its good bone remodeling and osteoconductivity. PMID:25551013

Fretting Fatigue with Cylindrical-On-Flat Contact: Crack Nucleation, Crack Path and Fatigue Life

PubMed Central

Noraphaiphipaksa, Nitikorn; Manonukul, Anchalee; Kanchanomai, Chaosuan

2017-01-01

Fretting fatigue experiments and finite element analysis were carried out to investigate the influence of cylindrical-on-flat contact on crack nucleation, crack path and fatigue life of medium-carbon steel. The location of crack nucleation was predicted using the maximum shear stress range criterion and the maximum relative slip amplitude criterion. The prediction using the maximum relative slip amplitude criterion gave the better agreement with the experimental result, and should be used for the prediction of the location of crack nucleation. Crack openings under compressive bulk stresses were found in the fretting fatigues with flat-on-flat contact and cylindrical-on-flat contacts, i.e., fretting-contact-induced crack openings. The crack opening stress of specimen with flat-on-flat contact was lower than those of specimens with cylindrical-on-flat contacts, while that of specimen with 60-mm radius contact pad was lower than that of specimen with 15-mm radius contact pad. The fretting fatigue lives were estimated by integrating the fatigue crack growth curve from an initial propagating crack length to a critical crack length. The predictions of fretting fatigue life with consideration of crack opening were in good agreement with the experimental results. PMID:28772522

The Short-Term Effect of Breathing Tasks Via an Incentive Spirometer on Lung Function Compared With Autogenic Drainage in Subjects With Cystic Fibrosis.

PubMed

Sokol, Gil; Vilozni, Daphna; Hakimi, Ran; Lavie, Moran; Sarouk, Ifat; Bat-El Bar; Dagan, Adi; Ofek, Miryam; Efrati, Ori

2015-12-01

Forced expiration may assist secretion movement by manipulating airway dynamics in patients with cystic fibrosis (CF). Expiratory resistive breathing via a handheld incentive spirometer has the potential to control the expiratory flow via chosen resistances (1-8 mm) and thereby mobilize secretions and improve lung function. Our objective was to explore the short-term effect of using a resistive-breathing incentive spirometer on lung function in subjects with CF compared with the autogenic drainage technique. This was a retrospective study. Subjects with CF performed 30-45 min of either the resistive-breathing incentive spirometer (n = 40) or autogenic drainage (n = 32) technique on separate days. The spirometer encourages the patient to exhale as long as possible while maintaining a low lung volume. The autogenic drainage technique includes repetitive inspiratory and expiratory maneuvers at various tidal breathing magnitudes while exhalation is performed in a sighing manner. Spirometry was performed before and 20-30 min after the therapy. Use of a resistive-breathing incentive spirometer improved FVC and FEV1 by 5-42% in 26 subjects. The forced expiratory flow during the middle half of the FVC maneuver (FEF25-75%) improved by >20% in 9 (22%) subjects. FVC improved the most in subjects with an FEV1 of 40-60% of predicted. Improvements negatively correlated with baseline percent-of-predicted FVC values provided improvements were above 10% (r(2) = 0.28). Values improved in a single subjects using the autogenic drainage technique. These 2 techniques may allow lower thoracic pressures and assist in the prevention of central airway collapse. The resistive-breathing incentive spirometer is a self-administered simple method that may aid airway clearance and has the potential to improve lung function as measured by FVC, FEV1, and FEF25-75% in patients with CF. Copyright © 2015 by Daedalus Enterprises.

Fatigue crack sizing in rail steel using crack closure-induced acoustic emission waves

NASA Astrophysics Data System (ADS)

Li, Dan; Kuang, Kevin Sze Chiang; Ghee Koh, Chan

2017-06-01

The acoustic emission (AE) technique is a promising approach for detecting and locating fatigue cracks in metallic structures such as rail tracks. However, it is still a challenge to quantify the crack size accurately using this technique. AE waves can be generated by either crack propagation (CP) or crack closure (CC) processes and classification of these two types of AE waves is necessary to obtain more reliable crack sizing results. As the pre-processing step, an index based on wavelet power (WP) of AE signal is initially established in this paper in order to distinguish between the CC-induced AE waves and their CP-induced counterparts. Here, information embedded within the AE signal was used to perform the AE wave classification, which is preferred to the use of real-time load information, typically adopted in other studies. With the proposed approach, it renders the AE technique more amenable to practical implementation. Following the AE wave classification, a novel method to quantify the fatigue crack length was developed by taking advantage of the CC-induced AE waves, the count rate of which was observed to be positively correlated with the crack length. The crack length was subsequently determined using an empirical model derived from the AE data acquired during the fatigue tests of the rail steel specimens. The performance of the proposed method was validated by experimental data and compared with that of the traditional crack sizing method, which is based on CP-induced AE waves. As a significant advantage over other AE crack sizing methods, the proposed novel method is able to estimate the crack length without prior knowledge of the initial crack length, integration of AE data or real-time load amplitude. It is thus applicable to the health monitoring of both new and existing structures.

Autogenous cultured growth plate chondrocyte transplantation in the treatment of physeal injury in rabbits.

PubMed

Tomaszewski, R; Bohosiewicz, J; Gap, A; Bursig, H; Wysocka, A

2014-11-01

The aim of this experimental study on New Zealand's white rabbits was to investigate the transplantation of autogenous growth plate cells in order to treat the injured growth plate. They were assessed in terms of measurements of radiological tibial varus and histological characteristics. An experimental model of plate growth medial partial resection of the tibia in 14 New Zealand white rabbits was created. During this surgical procedure the plate growth cells were collected and cultured. While the second surgery was being performed, the autologous cultured growth plate cells were grafted at the right tibia, whereas the left tibia was used as a control group. Histological examinations showed that the grafted right tibia presented the regular shape of the plate growth with hypertrophic maturation, chondrocyte columniation and endochondral calcification. Radiological study shows that the mean tibial deformity at the left angle was 20.29° (6.25 to 33) and 7.21° (5 to 10) in the right angle. This study has demonstrated that grafting of autogenous cultured growth plate cells into a defect of the medial aspect of the proximal tibial physis can prevent bone bridge formation, growth arrest and the development of varus deformity. Cite this article: Bone Joint Res 2014;3:310-16. ©2014 The British Editorial Society of Bone & Joint Surgery.

Biofeedback, autogenic training, and progressive relaxation in the treatment of Raynaud's disease: a comparative study.

PubMed Central

Keefe, F J; Surwit, R S; Pilon, R N

1980-01-01

Twenty-one female patients suffering from diagnosed idiopathic Raynaud's Disease were trained to raise digital skin temperature using either autogenic training, progressive muscle relaxation, or a combination of autogenic training and skin temperature feedback. Patients were instructed in the treatment procedures in three one-hour group sessions spaced one week apart. All patients were instructed to practice what they had learned twice a day at home. Patients kept records of the frequency of vasospastic attacks occurring over a four-week baseline period, and during the first four weeks and the ninth week of training. In addition, patients underwent four laboratory cold stress tests during which they were instructed to maintain digital temperature as the ambient temperature was slowly dropped from 26 degrees to 17 degrees C. Cold stress tests were given during week 1 of baseline and during weeks 1, 3, and 5 of training. No significant differences between the three behavioral treatment procedures were obtained. In addition, the ability of patients to maintain digital temperature during the cold stress challenge showed significant improvement from the first to the last tests. Symptomatic improvement was maintained by all patients nine weeks after the start of training. The implications of these findings for the behavioral treatment of Raynaud's Disease are discussed. PMID:6988380

Wetlands shrinkage, fragmentation and their links to agriculture in the Muleng-Xingkai Plain, China.

PubMed

Song, Kaishan; Wang, Zongming; Li, Lin; Tedesco, Lenore; Li, Fang; Jin, Cui; Du, Jia

2012-11-30

In the past five decades, the wetlands in the Muleng-Xingkai Plain, Northeast China, have experienced rapid shrinkage and fragmentation. In this study, wetlands cover change and agricultural cultivation were investigated through a time series of thematic maps from 1954, and Landsat satellite images representing the last five decades (1976, 1986, 1995, 2000, and 2005). Wetlands shrinkage and fragmentation were studied based on landscape metrics and the land use changes transition matrix. Furthermore, the driving forces were explored according to socioeconomic development and major natural environmental factors. The results indicate a significant decrease in the wetlands area in the past five decades, with an average annual decrease rate of 9004 ha/yr. Of the 625,268 ha of native wetlands in 1954, approximately 64% has been converted to other land use types by 2005, of which conversion to cropland accounts for the largest share (83%). The number of patches decreased from 1272 (1954) to 197 (1986) and subsequently increased to 326 (2005). The mean patch size changed from 480 ha (1954) to 1521 ha (1976), and then steadily decreased to 574 ha (2005). The largest patch index (total core area index) indicates wetlands shrinkage with decreased values from 31.73 (177,935 ha) to 3.45 (39,421 ha) respectively. Climatic changes occurred over the study period, providing a potentially favorable environment for agricultural development. At the same time population, groundwater harvesting, and fertilizer application increased significantly, resulting in wetlands degradation. According to the results, the shrinkage and fragmentation of wetlands could be explained by socioeconomic development and secondarily aided by changing climatic conditions. Copyright © 2012 Elsevier Ltd. All rights reserved.

Autogenic erosional surfaces on backwater-mediated deltas from floods and avulsions

NASA Astrophysics Data System (ADS)

Ganti, V.; Chadwick, A. J.; Lamb, M. P.; Fischer, W. W.; Trower, L.

2016-12-01

Erosional surfaces provide key bounds on the architecture of fluvio-deltaic stratigraphy and are attributed to relative sea level fall and sediment supply changes modulated by secular changes in climate; however, major knowledge gap exists in detangling the record of internal sedimentary dynamics from that of allogenic forcings. Recent work suggests that river flood variability through persistent backwater hydrodynamics exerts a primary control on lobe-scale avulsions on deltas, and floods and avulsions play an important role in driving transient channel incision even in deltas experiencing net aggradation. Here, we identify and quantify two autogenically generated mechanisms that result in erosional boundaries within fluvio-deltaic stratigraphy, namely, flood-induced and avulsion-induced scours. We developed a theoretical model based on mass conversation that suggests that flood-induced scours resulting from river drawdown propagate approximately one backwater length (Lb) from the shoreline, and the scour depth is maximum near the shoreline and scales with flood variability and the bankfull depth (hbf). Avulsion-induced scours result from river steepening due to shortening of the new river path. This mechanism results in an erosional pulse whose maximum depth scales with the critical in-channel sedimentation that induces an avulsion (scales with hbf) and initiates at the avulsion site and propagates upstream by Lb. Together, autogenically generated erosional scours can extend 1-2Lb from the shoreline and their depths are a function of hbf and flood variability. We validate these theoretical predictions using a recent experiment of river delta evolution governed by persistent backwater hydrodynamics under constant sea level conditions. Finally, we reinterpret outcrop scale observations within the Castlegate sandstone, Utah—type example for sequence stratigraphy—and show that field observations are consistent with scours resulting from floods and avulsions alone.

Crack tip field and fatigue crack growth in general yielding and low cycle fatigue

NASA Technical Reports Server (NTRS)

Minzhong, Z.; Liu, H. W.

1984-01-01

Fatigue life consists of crack nucleation and crack propagation periods. Fatigue crack nucleation period is shorter relative to the propagation period at higher stresses. Crack nucleation period of low cycle fatigue might even be shortened by material and fabrication defects and by environmental attack. In these cases, fatigue life is largely crack propagation period. The characteristic crack tip field was studied by the finite element method, and the crack tip field is related to the far field parameters: the deformation work density, and the product of applied stress and applied strain. The cyclic carck growth rates in specimens in general yielding as measured by Solomon are analyzed in terms of J-integral. A generalized crack behavior in terms of delta is developed. The relations between J and the far field parameters and the relation for the general cyclic crack growth behavior are used to analyze fatigue lives of specimens under general-yielding cyclic-load. Fatigue life is related to the applied stress and strain ranges, the deformation work density, crack nucleus size, fracture toughness, fatigue crack growth threshold, Young's modulus, and the cyclic yield stress and strain. The fatigue lives of two aluminum alloys correlate well with the deformation work density as depicted by the derived theory. The general relation is reduced to Coffin-Manson low cycle fatigue law in the high strain region.

Identification of signalling cascades involved in red blood cell shrinkage and vesiculation.

PubMed

Kostova, Elena B; Beuger, Boukje M; Klei, Thomas R L; Halonen, Pasi; Lieftink, Cor; Beijersbergen, Roderick; van den Berg, Timo K; van Bruggen, Robin

2015-04-16

Even though red blood cell (RBC) vesiculation is a well-documented phenomenon, notably in the context of RBC aging and blood transfusion, the exact signalling pathways and kinases involved in this process remain largely unknown. We have established a screening method for RBC vesicle shedding using the Ca(2+) ionophore ionomycin which is a rapid and efficient method to promote vesiculation. In order to identify novel pathways stimulating vesiculation in RBC, we screened two libraries: the Library of Pharmacologically Active Compounds (LOPAC) and the Selleckchem Kinase Inhibitor Library for their effects on RBC from healthy donors. We investigated compounds triggering vesiculation and compounds inhibiting vesiculation induced by ionomycin. We identified 12 LOPAC compounds, nine kinase inhibitors and one kinase activator which induced RBC shrinkage and vesiculation. Thus, we discovered several novel pathways involved in vesiculation including G protein-coupled receptor (GPCR) signalling, the phosphoinositide 3-kinase (PI3K)-Akt (protein kinase B) pathway, the Jak-STAT (Janus kinase-signal transducer and activator of transcription) pathway and the Raf-MEK (mitogen-activated protein kinase kinase)-ERK (extracellular signal-regulated kinase) pathway. Moreover, we demonstrated a link between casein kinase 2 (CK2) and RBC shrinkage via regulation of the Gardos channel activity. In addition, our data showed that inhibition of several kinases with unknown functions in mature RBC, including Alk (anaplastic lymphoma kinase) kinase and vascular endothelial growth factor receptor 2 (VEGFR-2), induced RBC shrinkage and vesiculation.

Identification of signalling cascades involved in red blood cell shrinkage and vesiculation

PubMed Central

Kostova, Elena B.; Beuger, Boukje M.; Klei, Thomas R.L.; Halonen, Pasi; Lieftink, Cor; Beijersbergen, Roderick; van den Berg, Timo K.; van Bruggen, Robin

2015-01-01

Even though red blood cell (RBC) vesiculation is a well-documented phenomenon, notably in the context of RBC aging and blood transfusion, the exact signalling pathways and kinases involved in this process remain largely unknown. We have established a screening method for RBC vesicle shedding using the Ca2+ ionophore ionomycin which is a rapid and efficient method to promote vesiculation. In order to identify novel pathways stimulating vesiculation in RBC, we screened two libraries: the Library of Pharmacologically Active Compounds (LOPAC) and the Selleckchem Kinase Inhibitor Library for their effects on RBC from healthy donors. We investigated compounds triggering vesiculation and compounds inhibiting vesiculation induced by ionomycin. We identified 12 LOPAC compounds, nine kinase inhibitors and one kinase activator which induced RBC shrinkage and vesiculation. Thus, we discovered several novel pathways involved in vesiculation including G protein-coupled receptor (GPCR) signalling, the phosphoinositide 3-kinase (PI3K)–Akt (protein kinase B) pathway, the Jak–STAT (Janus kinase–signal transducer and activator of transcription) pathway and the Raf–MEK (mitogen-activated protein kinase kinase)–ERK (extracellular signal-regulated kinase) pathway. Moreover, we demonstrated a link between casein kinase 2 (CK2) and RBC shrinkage via regulation of the Gardos channel activity. In addition, our data showed that inhibition of several kinases with unknown functions in mature RBC, including Alk (anaplastic lymphoma kinase) kinase and vascular endothelial growth factor receptor 2 (VEGFR-2), induced RBC shrinkage and vesiculation. PMID:25757360

Surface crack problems in plates

NASA Technical Reports Server (NTRS)

Joseph, P. F.; Erdogan, F.

1989-01-01

The mode I crack problem in plates under membrane loading and bending is reconsidered. The purpose is to examine certain analytical features of the problem further and to provide some new results. The formulation and the results given by the classical and the Reissner plate theories for through and part-through cracks are compared. For surface cracks the three-dimensional finite element solution is used as the basis of comparison. The solution is obtained and results are given for the crack/contact problem in a plate with a through crack under pure bending and for the crack interaction problem. Also, a procedure is developed to treat the problem of subcritical crack growth and to trace the evolution of the propagating crack.

Development of shrinkage limits and testing protocols for ODOT high performance concrete.

DOT National Transportation Integrated Search

2013-12-01

ODOT has observed varying degrees of cracking in their concrete structures. Cracking of high performance reinforced : concrete structures, in particular bridge decks, is of paramount concern to ODOT. Cracking at early ages (especially within : the fi...

A crack-closure model for predicting fatigue-crack growth under aircraft spectrum loading

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.

1981-01-01

The development and application of an analytical model of cycle crack growth is presented that includes the effects of crack closure. The model was used to correlate crack growth rates under constant amplitude loading and to predict crack growth under aircraft spectrum loading on 2219-T851 aluminum alloy sheet material. The predicted crack growth lives agreed well with experimental data. The ratio of predicted to experimental lives ranged from 0.66 to 1.48. These predictions were made using data from an ASTM E24.06.01 Round Robin.

Method of refining cracked oil by using metallic soaps. [desulfurization of cracked oils

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

Masakichi, M.; Marunouchi, K.K.; Yoshimura, T.

1937-04-13

The method of refining cracked oil consists in dissolving oil-soluble heavy metallic soap of oleic acid in a volatile organic solvent which will disperse homogeneously in cracked oil; pouring the solution thus obtained slowly into cracked oil to effect dispersion naturally and homogeneously at room temperature in the cracked oil. This process serves to react the mercaptans in the cracked oil with the heavy metallic soap by a double decomposition reaction and to precipitate the mercaptans as insoluble metallic salts. The remaining liquid is distilled to separate it from the remaining solvent.

A moment projection method for population balance dynamics with a shrinkage term

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

Wu, Shaohua; Yapp, Edward K.Y.; Akroyd, Jethro

A new method of moments for solving the population balance equation is developed and presented. The moment projection method (MPM) is numerically simple and easy to implement and attempts to address the challenge of particle shrinkage due to processes such as oxidation, evaporation or dissolution. It directly solves the moment transport equation for the moments and tracks the number of the smallest particles using the algorithm by Blumstein and Wheeler (1973) . The performance of the new method is measured against the method of moments (MOM) and the hybrid method of moments (HMOM). The results suggest that MPM performs muchmore » better than MOM and HMOM where shrinkage is dominant. The new method predicts mean quantities which are almost as accurate as a high-precision stochastic method calculated using the established direct simulation algorithm (DSA).« less

Ply cracking in composite laminates

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

Han, Youngmyong.

1989-01-01

Ply cracking behavior and accompanying stiffness changes in thermoset as well as thermoplastic matrix composites under various loading conditions are investigated. Specific topics addressed are: analytical model development for property degradations due to ply cracking under general in-plane loading; crack initiation and multiplication under static loading; and crack multiplication under cyclic loading. A model was developed to calculate the energy released due to ply cracking in a composite laminate subjected to general in-plane loading. The method is based on the use of a second order polynomial to represent the crack opening displacement and the concept of a through-the-thickness inherent flaw.more » The model is then used in conjunction with linear elastic fracture mechanics to predict the progressive ply cracking as well as first ply cracking. A resistance curve for crack multiplication is proposed as a means of characterizing the resistance to ply cracking in composite laminates. A methodology of utilizing the resistance curve to assess the crack density or overloading is also discussed. The method was applied to the graphite/thermoplastic polyimide composite to predict progressive ply cracking. However, unlike the thermoset matrix composites, a strength model is found to fit the experimental results better than the fracture mechanics based model. A set of closed form equations is also developed to calculate the accompanying stiffness changes due to the ply cracking. The effect of thermal residual stress is included in the analysis. A new method is proposed to characterize transverse ply cracking of symmetric balanced laminates under cyclic loading. The method is based on the concept of a through-the-thickness inherent flaw, the Paris law, and the resistance curve. Only two constants are needed to predict the crack density as a function of fatigue cycles.« less

Crack networks in damaged glass

NASA Astrophysics Data System (ADS)

Mallet, Celine; Fortin, Jerome; Gueguen, Yves

2013-04-01

We investigate how cracks develop and propagate in synthetic glass samples. Cracks are introduced in glass by a thermal shock of 300oC. Crack network is documented from optical and electronic microscopy on these samples that have been submitted to a thermal shock only. Samples are cylinder of 80 mm length and 40 mm diameter. Sections were cut along the cylinder axis and perpendicular to it. Using SEM, crack lengths and apertures can be measured. Optical microscopy allows to get the crack distribution over the entire sample. The sample average crack length is 3 mm. The average aperture is 6 ± 3μm. There is however a clear difference between the sample core, where the crack network has approximatively a transverse isotrope symmetry and the outer ring, where cracks are smaller and more numerous. By measuring before and after the thermal treatment the radial P and S wave velocities in room conditions, we can determine the total crack density which is 0.24. Thermally cracked samples, as described above, were submitted to creep tests. Constant axial stress and lateral stress were applied. Several experiments were performed at different stress values. Samples are saturated for 48 hours (to get an homogeneous pore fluid distribution), the axial stress is increased up to 80% of the sample strength. Stress step tests were performed in order to get creep data. The evolution of strain (axial and radial strain) is measured using strain gages, gap sensors (for the global axial strain) and pore volume change (for the volumetric strain). Creep data are interpreted as evidence of sub-critical crack growth in the cracked glass samples. The above microstructural observations are used, together with a crack propagation model, to account for the creep behavior. Assuming that (i) the observed volumetric strain rate is due to crack propagation and (ii) crack aspect ratio is constant we calculate the creep rate. We obtain some value on the crack propagation during a 24 hours of constant

Shrinkage and porosity evolution during air-drying of non-cellular food systems: Experimental data versus mathematical modelling.

PubMed

Nguyen, Thanh Khuong; Khalloufi, Seddik; Mondor, Martin; Ratti, Cristina

2018-01-01

In the present work, the impact of glass transition on shrinkage of non-cellular food systems (NCFS) during air-drying will be assessed from experimental data and the interpretation of a 'shrinkage' function involved in a mathematical model. Two NCFS made from a mixture of water/maltodextrin/agar (w/w/w: 1/0.15/0.015) were created out of maltodextrins with dextrose equivalent 19 (MD19) or 36 (MD36). The NCFS made with MD19 had 30°C higher Tg than those with MD36. This information indicated that, during drying, the NCFS with MD19 would pass from rubbery to glassy state sooner than NCFS MD36, for which glass transition only happens close to the end of drying. For the two NCFS, porosity and volume reduction as a function of moisture content were captured with high accuracy when represented by the mathematical models previously developed. No significant differences in porosity and in maximum shrinkage between both samples during drying were observed. As well, no change in the slope of the shrinkage curve as a function of moisture content was perceived. These results indicate that glass transition alone is not a determinant factor in changes of porosity or volume during air-drying. Copyright © 2017 Elsevier Ltd. All rights reserved.

Elevated temperature crack growth

NASA Technical Reports Server (NTRS)

Kim, K. S.; Vanstone, R. H.

1992-01-01

The purpose of this program was to extend the work performed in the base program (CR 182247) into the regime of time-dependent crack growth under isothermal and thermal mechanical fatigue (TMF) loading, where creep deformation also influences the crack growth behavior. The investigation was performed in a two-year, six-task, combined experimental and analytical program. The path-independent integrals for application to time-dependent crack growth were critically reviewed. The crack growth was simulated using a finite element method. The path-independent integrals were computed from the results of finite-element analyses. The ability of these integrals to correlate experimental crack growth data were evaluated under various loading and temperature conditions. The results indicate that some of these integrals are viable parameters for crack growth prediction at elevated temperatures.

Characterization of Cracking and Crack Growth Properties of the C5A Aircraft Tie-Box Forging

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Smith, Stephen W.; Newman, John A.; Willard, Scott A.

2003-01-01

Detailed destructive examinations were conducted to characterize the integrity and material properties of two aluminum alloy (7075-T6) horizontal stabilizer tie box forgings removed.from US. Air Force C5A and C5B transport aircraft. The C5B tie box forging was,found to contain no evidence of cracking. Thirteen cracks were found in the CSA,forging. All but one of the cracks observed in the C5A component were located along the top cap region (one crack was located in the bottom cap region). The cracks in the C5A component initiated at fastener holes and propagated along a highly tunneled intergranular crack path. The tunneled crack growth configuration is a likelv result of surface compressive stress produced during peening of the .forging suijace. The tie box forging ,fatigue crack growth, fracture and stress corrosion cracking (SCC) properties were characterized. Reported herein are the results of laboratory air ,fatigue crack growth tests and 95% relative humidity SCC tests conducted using specimens machined from the C5A ,forging. SCC test results revealed that the C5A ,forging material was susceptible to intergranular environmental assisted cracking: the C5A forging material exhibited a SCC crack-tip stress-intensity factor threshold of less than 6 MPadn. Fracture toughness tests revealed that the C5A forging material exhibited a fracture toughness that was 25% less than the C5B forging. The C5A forging exhibited rapid laboratory air fatigue crack growth rates having a threshold crack-tip stress-intensity factor range of less than 0.8 MPa sup m. Detailed fractographic examinations revealed that the ,fatigue crack intergranular growth crack path was similar to the cracking observed in the C5A tie box forging. Because both fatigue crack propagation and SCC exhibit similar intergranular crack path behavior, the damage mechanism resulting in multi-site cracking of tie box forgings cannot be determined unless local cyclic stresses can be quantified.

Autogenic and Allogenic: Emergent Coastline Patterns Interact With Forcing Variations

NASA Astrophysics Data System (ADS)

Murray, A. B.; Alvarez Antolinez, J. A.; Mendez, F. J.; Moore, L. J.; Wood, J.; Farley, G.

2017-12-01

between forcing and coastline shape. Comparisons between model predictions and observed shoreline-change patterns support the suggestion that the relationship between emergent coastline behaviours (autogenic processes) and external influences (autogenic forcing) involves such memory effects (Antolinez et al., in revision).

The internal strength of rivers: autogenic processes in control of the sediment load (Tana River, Kenya)

NASA Astrophysics Data System (ADS)

Geeraert, Naomi; Ochieng Omengo, Fred; Tamooh, Fredrick; Paron, Paolo; Bouillon, Steven; Govers, Gerard

2014-05-01

The construction of sediment rating curves for monitoring stations is a widely used technique to budget sediment fluxes. Changes in the relationship between discharge and sediment concentrations over time are often attributed to human-induced changes in catchment characteristics, such as land use change, dam construction or soil conservation measures and many models have been developed to quantitatively link catchment characteristics and river sediment load. Conversely, changes in river sediment fluxes are often interpreted as indications of major changes in the catchment. By doing so, autogenic processes, taking place within the river channel, are overlooked despite the increasing awareness of their importance. We assessed the role of autogenic processes on the sediment load of Tana River (Kenya). The Tana river was impacted by major dam construction between 1968 and 1988, effectively blocking at least 80% of the sediment transfer from the highlands to the lower river reaches. However, a comparison of pre-dam sediment fluxes at Garissa (located 250 km downstream of the dams) with recent measurements shows that sediment fluxes have not changed significantly. This suggests that most of the sediment in the post-dam period has to originate from inside the alluvial plain of the river, as tributaries downstream of the dams are scarce and intermittent. Several observations are consistent with this hypothesis. We observed that, during the wet season, sediment concentrations rapidly increased below the dams and are not controlled by inputs from tributaries. Also, sediment concentrations were high at the beginning of the wet season, which can be attributed to channel adjustment to the higher discharges. The river sediment does not contain significant amounts of 137Cs or 210Pbxs, suggesting that sediments are not derived from topsoil erosion. Furthermore, we observed a counter clockwise hysteresis during individual events which can be explained by the fact that sediment

Compatibilite deformationnelle des betons autoplacants pour des utilisations dans les reparations des infrastructures routieres

NASA Astrophysics Data System (ADS)

Ghezal, Aicha Fadela

Concrete structures repairs in Civil Engineering by using a thin bonded overlay is common practice. However the repaired structures are often victim of premature deterioration of the new repair material due to the appearance of restrained shrinkage cracks. In this context, the main objective of this thesis is to identify, through the experimental program called Phase I the principal parameters that significantly influence the creep potential of the evaluated mixtures. Once these parameters identified, the experimental entitled Phase II is conducted under conditions simulating repairs, and emphasis was placed on restrained shrinkage using instrumented ring test. Article 1 summarized the laboratory investigation undertaken to evaluate the potential of flexural creep behavior of several SCC. The results show clearly that the flexural creep potential of SCC varies widely depending on the nature of HRWR in use. In general, the use of naphthalene sulfonate leads to higher creep by comparison to polycarboxylate. It has been shown also that even when belonging to the same A.S.T.M. classification (polycarboxylic family) the magnitude of flexural creep varies also widely depending on the properties of polycarboxylic chemicals admixture. Based on the identified parameters in phase I, namely PNS superplasticizers type and PC2, with two ternary blended cements with fly ash (BTCFA) and slag (BTCS), the second experimental program was undertaken and summarized in articles 2 and 3. As presented in article 2, the results indicate that optimized SCCs produced with blended ternary cement with fly ash (BTCFA) developed at earlier age lower compressive and splitting-tensile strengths than the corresponding SCCs with blended cement with slag (BTCS). Test results also indicated that the drying shrinkage of SCCs based on BTCFA is higher than the corresponding SCCs proportioned with BTCS and attributed in part to higher total pores volume measured at 120 days on SCC BTCFA. The restrained

Vibration based algorithm for crack detection in cantilever beam containing two different types of cracks

NASA Astrophysics Data System (ADS)

Behzad, Mehdi; Ghadami, Amin; Maghsoodi, Ameneh; Michael Hale, Jack

2013-11-01

In this paper, a simple method for detection of multiple edge cracks in Euler-Bernoulli beams having two different types of cracks is presented based on energy equations. Each crack is modeled as a massless rotational spring using Linear Elastic Fracture Mechanics (LEFM) theory, and a relationship among natural frequencies, crack locations and stiffness of equivalent springs is demonstrated. In the procedure, for detection of m cracks in a beam, 3m equations and natural frequencies of healthy and cracked beam in two different directions are needed as input to the algorithm. The main accomplishment of the presented algorithm is the capability to detect the location, severity and type of each crack in a multi-cracked beam. Concise and simple calculations along with accuracy are other advantages of this method. A number of numerical examples for cantilever beams including one and two cracks are presented to validate the method.

The application of Newman crack-closure model to predicting fatigue crack growth

NASA Astrophysics Data System (ADS)

Si, Erjian

1994-09-01

Newman crack-closure model and the relevant crack growth program were applied to the analysis of crack growth under constant amplitude and aircraft spectrum loading on a number of aluminum alloy materials. The analysis was performed for available test data of 2219-T851, 2024-T3, 2024-T351, 7075-T651, 2324-T39, and 7150-T651 aluminum materials. The results showed that the constraint factor is a significant factor in the method. The determination of the constraint factor is discussed. For constant amplitude loading, satisfactory crack growth lives could be predicted. For the above aluminum specimens, the ratio of predicted to experimental lives, Np/Nt, ranged from 0.74 to 1.36. The mean value of Np/Nt was 0.97. For a specified complex spectrum loading, predicted crack growth lives are not in very good agreement with the test data. Further effort is needed to correctly simulate the transition between plane strain and plane stress conditions, existing near the crack tip.

Laparoscopic transverse rectus abdominus flap delay for autogenous breast reconstruction.

PubMed

Kaddoura, I L; Khoury, G S

1998-01-01

Laparoscopic ligation of the deep and superficial inferior epigastric vessels was done for ten mastectomized patients who elected to have autogenous reconstruction of their breast. All these patients had at least one indication for the delay which included obesity, smoking, or requirement of a large volume of tissue for their reconstruction. The procedure did not add any morbidity or mortality to our patients and was found to be comparable to the "open" delay in preventing partial tissue loss in all but two patients. We describe the use of a minimally invasive procedure to augment the deep superior epigastric pedicled blood supply for the future transverse rectus abdominus flap. We have found in laparoscopic delay a safe, short procedure that is useful in high risk patients who choose the option of autologous breast reconstruction.

Autogenic reaction synthesis of photocatalysts for solar fuel generation

DOEpatents

Ingram, Brian J.; Pol, Vilas G.; Cronauer, Donald C.; Ramanathan, Muruganathan

2016-04-19

In one preferred embodiment, a photocatalyst for conversion of carbon dioxide and water to a hydrocarbon and oxygen comprises at least one nanoparticulate metal or metal oxide material that is substantially free of a carbon coating, prepared by heating a metal-containing precursor compound in a sealed reactor under a pressure autogenically generated by dissociation of the precursor material in the sealed reactor at a temperature of at least about 600.degree. C. to form a nanoparticulate carbon-coated metal or metal oxide material, and subsequently substantially removing the carbon coating. The precursor material comprises a solid, solvent-free salt comprising a metal ion and at least one thermally decomposable carbon- and oxygen-containing counter-ion, and the metal of the salt is selected from the group consisting of Mn, Ti, Sn, V, Fe, Zn, Zr, Mo, Nb, W, Eu, La, Ce, In, and Si.

Design and evaluation of high-volume fly ash (HVFA) concrete mixes, report D : creep, shrinkage, and abrasion resistance of HVFA concrete.

DOT National Transportation Integrated Search

2012-10-01

The main objective of this study was to determine the effect on shrinkage, creep, : and abrasion resistance of high-volume fly ash (HVFA) concrete. The HVFA concrete : test program consisted of comparing the shrinkage, creep, and abrasion performance...

Reducing Shrinkage in Convenience Stores by the Use of the PSI.

ERIC Educational Resources Information Center

Terris, William; Jones, John W.

This bibliography contains over 1,200 behavioral and property is a rapidly growing problem. Successful strategies are needed to reduce employee theft; new loss prevention techniques need to be developed and evaluated. Two loss prevention programs aimed at reducing employees' theft were compared by the measures of shrinkage rates. Initially, a…

Self-organization in irregular landscapes: Detecting autogenic interactions from field data using descriptive statistics and dynamical systems theory

NASA Astrophysics Data System (ADS)

Larsen, L.; Watts, D.; Khurana, A.; Anderson, J. L.; Xu, C.; Merritts, D. J.

2015-12-01

The classic signal of self-organization in nature is pattern formation. However, the interactions and feedbacks that organize depositional landscapes do not always result in regular or fractal patterns. How might we detect their existence and effects in these "irregular" landscapes? Emergent landscapes such as newly forming deltaic marshes or some restoration sites provide opportunities to study the autogenic processes that organize landscapes and their physical signatures. Here we describe a quest to understand autogenic vs. allogenic controls on landscape evolution in Big Spring Run, PA, a landscape undergoing restoration from bare-soil conditions to a target wet meadow landscape. The contemporary motivation for asking questions about autogenic vs. allogenic controls is to evaluate how important initial conditions or environmental controls may be for the attainment of management objectives. However, these questions can also inform interpretation of the sedimentary record by enabling researchers to separate signals that may have arisen through self-organization processes from those resulting from environmental perturbations. Over three years at Big Spring Run, we mapped the dynamic evolution of floodplain vegetation communities and distributions of abiotic variables and topography. We used principal component analysis and transition probability analysis to detect associative interactions between vegetation and geomorphic variables and convergent cross-mapping on lidar data to detect causal interactions between biomass and topography. Exploratory statistics revealed that plant communities with distinct morphologies exerted control on landscape evolution through stress divergence (i.e., channel initiation) and promoting the accumulation of fine sediment in channels. Together, these communities participated in a negative feedback that maintains low energy and multiple channels. Because of the spatially explicit nature of this feedback, causal interactions could not

Osmotic shrinkage of giant egg-lecithin vesicles.

PubMed Central

Boroske, E; Elwenspoek, M; Helfrich, W

1981-01-01

Osmotic shrinkage of giant egg-lecithin vesicles was observed by phase-contrast microscopy. The vesicles remained or became spherical when shrinking. Small and thick-walled vesicles formed visible fingers attached to the sphere. The water permeability of the single bilayer was found to be 41 micrometers/s. A variety of observations indicate that osmosis induces a parallel lipid flow between the monolayers of the bilayer, leading to a strong positive spontaneous curvature. They also suggest the formation of mostly submicroscopic daughter vesicles. The estimated coupling constant, 2 . 10(-6) mol/mol, is large enough to be biologically significant. Images FIGURE 1 FIGURE 3 FIGURE 4 PMID:7213933

Liquid metal embrittlement. [crack propagation in metals with liquid metal in crack space

NASA Technical Reports Server (NTRS)

Tiller, W. A.

1973-01-01

Crack propagation is discussed for metals with liquid metal in the crack space. The change in electrochemical potential of an electron in a metal due to changes in stress level along the crack surface was investigated along with the change in local chemistry, and interfacial energy due to atomic redistribution in the liquid. Coupled elastic-elastrostatic equations, stress effects on electron energy states, and crack propagation via surface roughening are discussed.

Polypropylene fiber reinforced microsilica concrete bridge deck overlay at Link River Bridge

DOT National Transportation Integrated Search

2000-02-01

In 1997 ODOT overlaid the Link River Bridge with microsilica concrete, reinforced with polypropylene fibers (FMC). The manufacturer claimed the fibers would reduce plastic shrinkage cracks and settlement cracking during the early life of the concrete...

Inspecting cracks in foam insulation

NASA Technical Reports Server (NTRS)

Cambell, L. W.; Jung, G. K.

1979-01-01

Dye solution indicates extent of cracking by penetrating crack and showing original crack depth clearly. Solution comprised of methylene blue in denatured ethyl alcohol penetrates cracks completely and evaporates quickly and is suitable technique for usage in environmental or structural tests.

Evaluation of crack-sealing milled pavement in the effort to reduce transverse cracking.

DOT National Transportation Integrated Search

2015-01-01

To determine if crack sealing milled pavement prior to overlay will deter the : migration of transverse cracking, or have an effect on pavement performance, : when compared to an adjacent milled pavement that receives no crack sealing : treatment.

Crack-closure and crack-growth measurements in surface-flawed titanium alloy Ti6Al-4V

NASA Technical Reports Server (NTRS)

Elber, W.

1975-01-01

The crack-closure and crack-growth characteristics of the titanium alloy Ti-6Al-4V were determined experimentally on surface-flawed plate specimens. Under cyclic loading from zero to tension, cracks deeper than 1 mm opened at approximately 50 percent of the maximum load. Cracks shallower than 1 mm opened at higher loads. The correlation between crack-growth rate and the total stress-intensity range showed a lower threshold behavior. This behavior was attributed to the high crack-opening loads at short cracks because the lower threshold was much less evident in correlations between the crack-growth rates and the effective stress-intensity range.

C-O-H-S magmatic fluid system in shrinkage bubbles of melt inclusions

NASA Astrophysics Data System (ADS)

Robidoux, P.; Frezzotti, M. L.; Hauri, E. H.; Aiuppa, A.

2016-12-01

Magmatic volatiles include multiple phases in the C-O-H-S system of shrinkage bubbles for which a conceptual model is still unclear during melt inclusion formation [1,2,3,4]. The present study aims to qualitatively explore the evolution of the volatile migration, during and after the formation of the shrinkage bubble in melt inclusions trapped by olivines from Holocene to present at San Cristóbal volcano (Nicaragua), Central American Volcanic Arc (CAVA). Combined scanning electron microscope (SEM) and Raman spectroscopy observations allow to define the mineral-fluid phases inside typical shrinkage bubbles at ambient temperature. The existence of residual liquid water is demonstrated in the shrinkage bubbles of naturally quenched melt inclusion and this water could represents the principal agent for chemical reactions with other dissolved ionic species (SO42-, CO32-, etc.) and major elements (Mg, Fe, Cu, etc.) [4,5]. With the objective of following the cooling story of the bubble-inclusion system, the new methodological approach here estimate the interval of equilibrium temperatures for each SEM-Raman identified mineral phase (carbonates, hydrous carbonates, sulfurs, sulfates, etc.). Finally, two distinct mechanisms are proposed to describe the evolution of this heterogeneous fluid system in bubble samples at San Cristóbal which imply a close re-examination for similar volcanoes in subduction zone settings: (1) bubbles are already contracted and filled by volatiles by diffusion processes from the glass and leading to a C-O-H-S fluid-glass reaction enriched in Mg-Fe-Cu elements (2) bubbles are formed by oversaturation of the volatiles from the magma which is producing an immiscible metal-rich fluid. [1]Moore et al. (2015). Am. Mineral. 100, 806-823 [2]Wallace et al. (2015). Am. Mineral. 100, 787-794 [3]Lowenstern (2015). Am. Mineral. 100, 672-673 [4]Esposito, et al. (2016). Am. Mineral. 101, 1691-1708 [5]Kamenetsky et al. (2001). Earth Planet. Sci. Lett. 184, 685-702

Shrinkage Estimation of Varying Covariate Effects Based On Quantile Regression

PubMed Central

Peng, Limin; Xu, Jinfeng; Kutner, Nancy

2013-01-01

Varying covariate effects often manifest meaningful heterogeneity in covariate-response associations. In this paper, we adopt a quantile regression model that assumes linearity at a continuous range of quantile levels as a tool to explore such data dynamics. The consideration of potential non-constancy of covariate effects necessitates a new perspective for variable selection, which, under the assumed quantile regression model, is to retain variables that have effects on all quantiles of interest as well as those that influence only part of quantiles considered. Current work on l1-penalized quantile regression either does not concern varying covariate effects or may not produce consistent variable selection in the presence of covariates with partial effects, a practical scenario of interest. In this work, we propose a shrinkage approach by adopting a novel uniform adaptive LASSO penalty. The new approach enjoys easy implementation without requiring smoothing. Moreover, it can consistently identify the true model (uniformly across quantiles) and achieve the oracle estimation efficiency. We further extend the proposed shrinkage method to the case where responses are subject to random right censoring. Numerical studies confirm the theoretical results and support the utility of our proposals. PMID:25332515

Recycling of rubble from building demolition for low-shrinkage concretes.

PubMed

Corinaldesi, Valeria; Moriconi, Giacomo

2010-04-01

In this project concrete mixtures were prepared that were characterized by low ductility due to desiccation by using debris from building demolition, which after a suitable treatment was used as aggregate for partial replacement of natural aggregates. The recycled aggregate used came from a recycling plant, in which rubble from building demolition was selected, crushed, cleaned, sieved, and graded. Such aggregates are known to be more porous as indicated by the Saturated Surface Dry (SSD) moisture content. The recycled concrete used as aggregates were added to the concrete mixture in order to study their influence on the fresh and hardened concrete properties. They were added either after water pre-soaking or in dry condition, in order to evaluate the influence of moisture in aggregates on the performance of concrete containing recycled aggregate. In particular, the effect of internal curing, due to the use of such aggregates, was studied. Concrete behavior due to desiccation under dehydration was studied by means of both drying shrinkage test and German angle test, through which shrinkage under the restrained condition of early age concrete can be evaluated. Copyright 2009 Elsevier Ltd. All rights reserved.

Reflectivity of crack sealant.

DOT National Transportation Integrated Search

2002-01-01

Crack sealing is used in road maintenance but presents a problem when crack seal material visually pops out on the roadway, making it difficult to see lane stripes. This problem will increase as New Mexico increases its use of crack sealants. This su...

Endovascular Treatment of Autogenous Radiocephalic Fistulas with the 'Eighth Note' Deformity for Hemodialysis

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

Weng Meijui; Chen, Matt Chiung-Yu, E-mail: jjychen@gmail.co; Chi Wenche

2010-02-15

The purpose of this paper is to describe a unique 'eighth note' deformity of the autogenous radiocephalic fistula for hemodialysis and to retrospectively evaluate the efficacy and safety of its endovascular treatment. Over 3 years, a total of 808 patients and 558 autogenous radiocephalic fistulas were treated for vascular access dysfunction or thrombosis. These included 14 fistulas in 14 patients (9 men, 5 women; mean age, 58.2 {+-} 2.8 years; range 27-79 years) whose fistulograms before treatment resembled a musical note, the eighth note. Endovascular treatment sought to remodel the deformed vascular access to a classic radiocephalic fistula and increasemore » the number of cannulation sites available for hemodialysis. The technical and clinical success rates were each 92.8% (13/14). Fistula remodeling was successful in 13 patients. The postintervention primary patency was 100% at 90 days, 91.7 {+-} 0.8% at 120 days, 78.6 {+-} 13.9% at 180 days, 62.9 {+-} 17.9% at 360 days, 31.4 {+-} 24.0% at 540 days, and 0% at 720 days. The postintervention secondary patency was 100% at 90 days, 100% at 120 days, 100% at 180 days, 85.7 {+-} 13.2% at 360 days, and 85.7 {+-} 13.2% at 720 days. No major complications were noted. Minor complications were found in 71.4% of patients, all of which resolved spontaneously. In conclusion, endovascular treatment of fistulas with the eighth note deformity can effectively increase the number of available cannulation sites, facilitate fistula maturation, and facilitate thromboaspiration after fistula thrombosis.« less

Opening-mode cracking in asphalt pavements : crack initiation and saturation.

DOT National Transportation Integrated Search

2009-12-01

This paper investigates the crack initiation and saturation for opening-mode cracking. Using elastic governing equations : and a weak form stress boundary condition, we derive an explicit solution of elastic fields in the surface course and : obtain ...

Intermittent crack growth in fatigue

NASA Astrophysics Data System (ADS)

Kokkoniemi, R.; Miksic, A.; Ovaska, M.; Laurson, L.; Alava, M. J.

2017-07-01

Fatigue occurs under cyclic loading at stresses below a material’s static strength limit. We consider fatigue crack growth as a stochastic process and perform crack growth experiments in a metal (copper). We follow optically cracks propagating from initial edge notches. The main interest is in the dynamics of the crack growth—the Paris’ law and the initiation phase prior to that—and especially the intermittency this is discovered to display. How the sampling of the crack advancement, performed at regular intervals, influences such measurement results is analysed by the analogy of planar crack dynamics in slow, driven growth.

Soil stabilization field trial : interim report II.

DOT National Transportation Integrated Search

2002-02-01

Shrinkage cracks in cement-stabilized bases/subbase can be alleviated by specifying the right cement dosage, or by other additives/procedures that suppress crack susceptibility. A field trial of six 1000 ft sections to investigate several alternative...

On Generating Fatigue Crack Growth Thresholds

NASA Technical Reports Server (NTRS)

Forth, Scott C.; Newman, James, Jr.; Forman, Royce G.

2003-01-01

The fatigue crack growth threshold, defining crack growth as either very slow or nonexistent, has been traditionally determined with standardized load reduction methodologies. These experimental procedures can induce load history effects that result in crack closure. This history can affect the crack driving force, i.e. during the unloading process the crack will close first at some point along the wake or blunt at the crack tip, reducing the effective load at the crack tip. One way to reduce the effects of load history is to propagate a crack under constant amplitude loading. As a crack propagates under constant amplitude loading, the stress intensity factor range, Delta K, will increase, as will the crack growth rate. da/dN. A fatigue crack growth threshold test procedure is experimentally validated that does not produce load history effects and can be conducted at a specified stress ratio, R. The authors have chosen to study a ductile aluminum alloy where the plastic deformations generated during testing may be of the magnitude to impact the crack opening.

Effectiveness of autogenic relaxation training on children and adolescents with behavioral and emotional problems.

PubMed

Goldbeck, Lutz; Schmid, Katharina

2003-09-01

To investigate the effectiveness of autogenic relaxation training in a mildly disturbed outpatient population of children and adolescents with mostly internalizing symptoms, and/or some aggressive, impulsive, or attention deficit symptoms. Fifty children and adolescents from southern Germany (mean age 10.2 years; range 6-15 years; mostly intact middle class family background) participated in a group intervention program. Fifteen patients were randomly assigned to a waiting-list control group. Behavior symptoms (Child Behavior Checklist), psychosomatic complaints (Giessen Complaint List), and level of stress were assessed before and after the intervention or after the waiting phase. Individual goal attainment was evaluated at the end of the intervention and in a 3-month follow-up. The parent report on CBCL reflected reduced symptoms compared with control. The child report indicated reduced stress and psychosomatic complaints both in the intervention and control group, and no significant group x time interaction effects occurred on these scales. Effect sizes of 0.49 in the CBCL and 0.36 in the complaint list indicated clinically relevant effects of the intervention compared with the control group. At the end of the intervention, 56% of the children and 55% of the parents reported partial goal attainment, 38% of the children and 30% of the parents reported complete goal attainment; 71% of the parents confirmed partial goal attainment 3 months postintervention. Autogenic relaxation training is an effective broadband method for children and adolescents.

Improved Silica Aerogel Composite Materials

NASA Technical Reports Server (NTRS)

Paik, Jong-Ah; Sakamoto, Jeffrey; Jones, Steven

2008-01-01

A family of aerogel-matrix composite materials having thermal-stability and mechanical- integrity properties better than those of neat aerogels has been developed. Aerogels are known to be excellent thermal- and acoustic-insulation materials because of their molecular-scale porosity, but heretofore, the use of aerogels has been inhibited by two factors: (1) Their brittleness makes processing and handling difficult. (2) They shrink during production and shrink more when heated to high temperatures during use. The shrinkage and the consequent cracking make it difficult to use them to encapsulate objects in thermal-insulation materials. The underlying concept of aerogel-matrix composites is not new; the novelty of the present family of materials lies in formulations and processes that result in superior properties, which include (1) much less shrinkage during a supercritical-drying process employed in producing a typical aerogel, (2) much less shrinkage during exposure to high temperatures, and (3) as a result of the reduction in shrinkage, much less or even no cracking.

Sudden bending of cracked laminates

NASA Technical Reports Server (NTRS)

Sih, G. C.; Chen, E. P.

1980-01-01

A dynamic approximate laminated plate theory is developed with emphasis placed on obtaining effective solution for the crack configuration where the 1/square root of r stress singularity and the condition of plane strain are preserved. The radial distance r is measured from the crack edge. The results obtained show that the crack moment intensity tends to decrease as the crack length to laminate plate thickness is increased. Hence, a laminated plate has the desirable feature of stabilizing a through crack as it increases its length at constant load. Also, the level of the average load intensity transmitted to a through crack can be reduced by making the inner layers to be stiffer than the outer layers. The present theory, although approximate, is useful for analyzing laminate failure to crack propagation under dynamic load conditions.

Shrinkage stress compensation in composite-restored teeth: relaxation or hygroscopic expansion?

PubMed

Meriwether, Laurel A; Blen, Bernard J; Benson, Jarred H; Hatch, Robert H; Tantbirojn, Daranee; Versluis, Antheunis

2013-05-01

Polymerization of composite restorations causes shrinkage, which deforms and thus stresses restored teeth. This shrinkage deformation, however, has been shown to decrease over time. The objective was to investigate whether this reduction was caused by hygroscopic expansion or stress relaxation of the composite/tooth complex. Extracted molars were mounted in rigid stainless steel rings with four spherical reference areas. Twelve molars were prepared with large mesioocclusodistal slots, etched, bonded, and restored with a composite material (Filtek Supreme, 3M ESPE) in two horizontal layers. Ten intact molars were the controls. The teeth were stored either in deionized water or silicone oil. They were scanned after preparation (baseline), restoration (0-week), and after 1, 2, and 4 weeks storage. Scanned tooth surfaces were aligned with the baseline using the unchanged reference areas. Cuspal flexure was calculated from lingual and buccal surface deformation. To verify that the restorations had remained bonded, dye penetration at the interfaces was assessed using basic fuchsin dye. Statistical assessment was done by ANOVA followed by Student-Newman-Keuls post hoc test (p=0.05). Substantial cuspal contraction was found for restored teeth after the composite was cured (13-14 μm cuspal flexure). After 4 weeks cuspal contraction decreased significantly for restored teeth stored in water (7.3 ± 3.2) but not for those stored in silicone oil (11.4 ± 5.0). Dye penetration of the occlusal interface was minimal in both groups (106 ± 87 and 21 ± 28 μm in water and silicone oil, respectively). The results suggest that hygroscopic expansion was the main mechanism for shrinkage stress compensation. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

TH-E-BRF-01: Exploiting Tumor Shrinkage in Split-Course Radiotherapy

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

Unkelbach, J; Craft, D; Hong, T

2014-06-15

Purpose: In split-course radiotherapy, a patient is treated in several stages separated by weeks or months. This regimen has been motivated by radiobiological considerations. However, using modern image-guidance, it also provides an approach to reduce normal tissue dose by exploiting tumor shrinkage. In this work, we consider the optimal design of split-course treatments, motivated by the clinical management of large liver tumors for which normal liver dose constraints prohibit the administration of an ablative radiation dose in a single treatment. Methods: We introduce a dynamic tumor model that incorporates three factors: radiation induced cell kill, tumor shrinkage, and tumor cellmore » repopulation. The design of splitcourse radiotherapy is formulated as a mathematical optimization problem in which the total dose to the liver is minimized, subject to delivering the prescribed dose to the tumor. Based on the model, we gain insight into the optimal administration of radiation over time, i.e. the optimal treatment gaps and dose levels. Results: We analyze treatments consisting of two stages in detail. The analysis confirms the intuition that the second stage should be delivered just before the tumor size reaches a minimum and repopulation overcompensates shrinking. Furthermore, it was found that, for a large range of model parameters, approximately one third of the dose should be delivered in the first stage. The projected benefit of split-course treatments in terms of liver sparing depends on model assumptions. However, the model predicts large liver dose reductions by more than a factor of two for plausible model parameters. Conclusion: The analysis of the tumor model suggests that substantial reduction in normal tissue dose can be achieved by exploiting tumor shrinkage via an optimal design of multi-stage treatments. This suggests taking a fresh look at split-course radiotherapy for selected disease sites where substantial tumor regression translates into

Soil stabilization field trial : interim report.

DOT National Transportation Integrated Search

2001-04-01

Shrinkage cracks in cement-stabilized bases/subbase can be alleviated by specifying : the right cement dosage, or by other additives/procedures that suppress crack susceptibility. A field : trial of six 1000 ft test sections to investigate several al...

Soil stabilization field trial : interim report I.

DOT National Transportation Integrated Search

2001-04-01

Shrinkage cracks in cement-stabilized bases/subbase can be alleviated by specifying the right cement dosage, or by other additives/procedures that suppress crack susceptibility. A field trial of six 1000 ft test sections to investigate several altern...

Soil stabilization field trial : interim report III.

DOT National Transportation Integrated Search

2003-11-01

Shrinkage cracks in cement-stabilized bases/subbase can be alleviated by specifying the right cement dosage, or by other additives/procedures that suppress crack susceptibility. A field trial of six 1000 ft test sections to investigate several altern...

Interaction of a penny-shaped crack and an external circular crack in a transversely isotropic composite

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

Tsai, Y.M.

1998-12-31

The interaction of a penny-shaped crack and an external circular crack in a transversely isotropic composite is investigated using the techniques of Hankel transform and multiplying factors. The boundary conditions of the problem have three different parts. The stress intensity factors at the inner and the outer crack tips are obtained in exact expressions as the products of a dimensional quantity and nondimensional functions. The presence of a penny-shaped crack is shown to have a strong effect on the magnitude of the stress intensity of the external circular crack. The crack surface displacement is also obtained and evaluated numerically formore » different values of the ratio of the inner crack radius to the external crack radius.« less

Autogenic incision and terrace formation resulting from abrupt late-glacial base-level fall, lower Chippewa River, Wisconsin, USA

NASA Astrophysics Data System (ADS)

Faulkner, Douglas J.; Larson, Phillip H.; Jol, Harry M.; Running, Garry L.; Loope, Henry M.; Goble, Ronald J.

2016-08-01

A paucity of research exists regarding the millennial-scale response of inland alluvial streams to abrupt base-level fall. Studies of modern systems indicate that, over short time scales, the response is a diffusion-like process of upstream-propagating incision. In contrast, evidence from the lower Chippewa River (LCR), located in the upper Midwest of the USA, suggests that autogenic controls operating over time scales of several millennia can overwhelm diffusion, resulting in incision that is prolonged and episodic. During the Last Glacial Maximum, the LCR drained the Chippewa Lobe of the Laurentide Ice Sheet to the glacial upper Mississippi River (UMR). As a meltwater stream, it aggraded and filled its valley with glacial outwash, as did its largest tributaries, which were also meltwater streams. Its nonglacial tributaries aggraded, too, filling their valleys with locally derived sediment. During deglaciation, the UMR incised at least twice, abruptly lowering the LCR's base level - 15 m at 16 ka or earlier and an additional 40 m at ca. 13.4 ka. Each of these base-level falls initiated incision of the LCR, led by upstream migrating knickpoints. The propagation of incision has, however, been a lengthy process. The optically stimulated luminescence (OSL) ages of terrace alluvium indicate that, by 13.5 ka, incision had advanced up the LCR only 15 km, and by 9 ka, only 55 km. The process has also been episodic, resulting in the formation of fill-cut terraces (inferred from GPR surveys and exposures of terrace alluvium) that are younger and more numerous in the upstream direction. Autogenic increases in sediment load and autogenic bed armoring, the result of periodic tributary-stream rejuvenation and preferential winnowing of fines by the incising river, may have periodically caused knickpoint migration and incision to slow and possibly stop, allowing lateral erosion and floodplain formation to dominate. A decline in sediment flux from stabilizing incised tributary

Dilatometric shrinkage study on magnesium titanate-based ceramic systems

NASA Astrophysics Data System (ADS)

Ermawati, F. U.; Suasmoro, S.

2018-03-01

The development of dielectric materials for applications in the microwave frequencies has been increasing with rapid progress in mobile and satellite communication systems. Magnesium titanate (MgTiO3)-based ceramics have been the favourite candidates for such applications due to their excellent dielectric characteristics, i.e. a moderate level of dielectric constant together with a high-quality factor and high-temperature stability. These outstanding performance, however, can only be achieved when the ceramics are highly dense. The work reported in this paper discussed the study on the dilatometric shrinkage behaviour of pure and zinc-doped magnesium titanate (Mg1–xZn x TiO3 for x = 0–0.5) ceramic systems after the systems following the heating passage up to 1300 °C. The results were discussed based on the phase formation data recorded from powder X-ray diffraction (XRD). An additional 2 wt. % V2O5 to the MZT0.2 system has increased the shrinkage of the system, and hence the relative density. The V2O5 addition also prevented the grain growth and did not alter the structure. From 100 Hz to 20 MHz, the dielectric permittivity is constant; which varies from (15.4 – 17.0) ± 0.1 % throughout the samples, these values are therefore frequency independent.

Allogenic and Autogenic Signals in the Detrital Zircon U-Pb Record of the Deep-Sea Bengal Fan

NASA Astrophysics Data System (ADS)

Blum, M. D.; Rogers, K. G.; Gleason, J. D.; Najman, Y.

2017-12-01

The Himalayan-sourced Ganges-Brahmaputra river system and the deep-sea Bengal Fan represent Earth's largest sediment-dispersal system. This presentation summarizes a new detrital zircon U-Pb (DZ) provenance record from the Bengal Fan from cores collected during IODP Expedition 354, with coring sites located 1350 km downdip from the shelf margin. Each of our 15 samples were collected from medium- to fine-grained turbidite sand and, based on shipboard biostratigraphic analyses, our samples are late Miocene to late Pleistocene in age. Each sample was analyzed by LA-ICPMS at the Arizona Laserchron facility, with an average of n=270 concordant U-Pb ages per sample. Our goals are to use these data to evaluate the influence of allogenic controls vs. autogenic processes on signal propagation from source-to-sink. At the first order, large-scale sediment transfer to the Bengal Fan clearly records the strong tectonic and climatic forcing associated with the Himalayas and Ganges-Brahmaputra system: after up to 2500 km of river transport, and 1350 km of transport in turbidity currents, the DZ record faithfully represents Himalayan source terrains. The sand-rich turbidite part of the record is nevertheless biased towards glacial periods when rivers extended across the shelf in response to climate-forced sea-level fall, and discharged directly to slope canyons. However, only part of the Bengal Fan DZ record represents either the Ganges or the Brahmaputra, with most samples representing varying degrees of mixing of sediments from the two systems: this mixing, or the lack thereof, represents the signal of autogenic avulsions on the delta plain that result in the two river systems delivering sediment separately to the shelf margin, or together as they do today. Within the allogenic framework established by tectonic processes, the climatic system, and global climate-forced sea-level change, the DZ U-Pb record of sediment mixing or the lack thereof provides a fingerprint of autogenic

Investigation of Cracks Found in Helicopter Longerons

NASA Technical Reports Server (NTRS)

Newman, John A.; Baughman, James M.; Wallace, Terryl A.

2009-01-01

Four cracked longerons, containing a total of eight cracks, were provided for study. Cracked regions were cut from the longerons. Load was applied to open the cracks, enabling crack surface examination. Examination revealed that crack propagation was driven by fatigue loading in all eight cases. Fatigue crack initiation appears to have occurred on the top edge of the longerons near geometric changes that affect component bending stiffness. Additionally, metallurigical analysis has revealed a local depletion in alloying elements in the crack initiation regions that may be a contributing factor. Fatigue crack propagation appeared to be initially driven by opening-mode loading, but at a crack length of approximately 0.5 inches (12.7 mm), there is evidence of mixed-mode crack loading. For the longest cracks studied, shear-mode displacements destroyed crack-surface features of interest over significant portions of the crack surfaces.

Statistical distribution of time to crack initiation and initial crack size using service data

NASA Technical Reports Server (NTRS)

Heller, R. A.; Yang, J. N.

1977-01-01

Crack growth inspection data gathered during the service life of the C-130 Hercules airplane were used in conjunction with a crack propagation rule to estimate the distribution of crack initiation times and of initial crack sizes. A Bayesian statistical approach was used to calculate the fraction of undetected initiation times as a function of the inspection time and the reliability of the inspection procedure used.

A 12 year EDF study of concrete creep under uniaxial and biaxial loading

DOE PAGES

Charpin, Laurent; Le Pape, Yann; Coustabeau, Eric; ...

2017-11-04

This paper presents a 12-year-long creep and shrinkage experimental campaign on cylindrical and prismatic concrete samples under uniaxial and biaxial stress, respectively. The motivation for the study is the need for predicting the delayed strains and the pre-stress loss of concrete containment buildings of nuclear power plants. Two subjects are central in this regard: the creep strain's long-term evolution and the creep Poisson's ratio. A greater understanding of these areas is necessary to ensure reliable predictions of the long-term behavior of the concrete containment buildings.Long-term basic creep appears to evolve as a logarithm function of time in the range ofmore » 3 to 10 years of testing. Similar trends are observed for drying creep, autogenous shrinkage, and drying shrinkage testing, which suggests that all delayed strains obtained using different loading and drying conditions originate from a common mechanism.The creep Poisson's ratio derived from the biaxial tests is approximately constant over time for both the basic and drying creep tests (creep strains corrected by the shrinkage strain).It is also shown that the biaxial non-drying samples undergo a significant increase in Young's modulus after 10 years.« less

A 12 year EDF study of concrete creep under uniaxial and biaxial loading

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

Charpin, Laurent; Le Pape, Yann; Coustabeau, Eric

This paper presents a 12-year-long creep and shrinkage experimental campaign on cylindrical and prismatic concrete samples under uniaxial and biaxial stress, respectively. The motivation for the study is the need for predicting the delayed strains and the pre-stress loss of concrete containment buildings of nuclear power plants. Two subjects are central in this regard: the creep strain's long-term evolution and the creep Poisson's ratio. A greater understanding of these areas is necessary to ensure reliable predictions of the long-term behavior of the concrete containment buildings.Long-term basic creep appears to evolve as a logarithm function of time in the range ofmore » 3 to 10 years of testing. Similar trends are observed for drying creep, autogenous shrinkage, and drying shrinkage testing, which suggests that all delayed strains obtained using different loading and drying conditions originate from a common mechanism.The creep Poisson's ratio derived from the biaxial tests is approximately constant over time for both the basic and drying creep tests (creep strains corrected by the shrinkage strain).It is also shown that the biaxial non-drying samples undergo a significant increase in Young's modulus after 10 years.« less

Influence of irradiance on Knoop hardness, degree of conversion, and polymerization shrinkage of nanofilled and microhybrid composite resins.

PubMed

Fugolin, Ana Paula Piovezan; Correr-Sobrinho, Lourenço; Correr, Américo Bortolazzo; Sinhoreti, Mário Alexandre Coelho; Guiraldo, Ricardo Danil; Consani, Simonides

2016-01-01

The purpose of this study was to investigate the influence of the irradiance emitted by a light-curing unit on microhardness, degree of conversion (DC), and gaps resulting from shrinkage of 2 dental composite resins. Cylinders of nanofilled and microhybrid composites were fabricated and light cured. After 24 hours, the tops and bottoms of the specimens were evaluated via indentation testing and Fourier transform infrared spectroscopy to determine Knoop hardness number (KHN) and DC, respectively. Gap width (representing polymerization shrinkage) was measured under a scanning electron microscope. The nanofilled composite specimens presented significantly greater KHNs than did the microhybrid specimens (P < 0.05). The microhybrid composite resin exhibited significantly greater DC and gap width than the nanofilled material (P < 0.05). Irradiance had a mostly material-dependent influence on the hardness and DC, but not the polymerization shrinkage, of composite resins.

Eddy current crack detection capability assessment approach using crack specimens with differing electrical conductivity

NASA Astrophysics Data System (ADS)

Koshti, Ajay M.

2018-03-01

Like other NDE methods, eddy current surface crack detectability is determined using probability of detection (POD) demonstration. The POD demonstration involves eddy current testing of surface crack specimens with known crack sizes. Reliably detectable flaw size, denoted by, a90/95 is determined by statistical analysis of POD test data. The surface crack specimens shall be made from a similar material with electrical conductivity close to the part conductivity. A calibration standard with electro-discharged machined (EDM) notches is typically used in eddy current testing for surface crack detection. The calibration standard conductivity shall be within +/- 15% of the part conductivity. This condition is also applicable to the POD demonstration crack set. Here, a case is considered, where conductivity of the crack specimens available for POD testing differs by more than 15% from that of the part to be inspected. Therefore, a direct POD demonstration of reliably detectable flaw size is not applicable. Additional testing is necessary to use the demonstrated POD test data. An approach to estimate the reliably detectable flaw size in eddy current testing for part made from material A using POD crack specimens made from material B with different conductivity is provided. The approach uses additional test data obtained on EDM notch specimens made from materials A and B. EDM notch test data from the two materials is used to create a transfer function between the demonstrated a90/95 size on crack specimens made of material B and the estimated a90/95 size for part made of material A. Two methods are given. For method A, a90/95 crack size for material B is given and POD data is available. Objective of method A is to determine a90/95 crack size for material A using the same relative decision threshold that was used for material B. For method B, target crack size a90/95 for material A is known. Objective is to determine decision threshold for inspecting material A.

Operational Applications of Autogenic Feedback Training Exercise as a Treatment for Airsickness in the Military

NASA Technical Reports Server (NTRS)

Gebreyesus, Fiyore; Cowings, Patricia S.; Toscano, William B.

2012-01-01

Airsickness is experienced by about 50% of military aviators some time in their career. Aviators who suffer from recurrent episodes of airsickness are typically referred to the Naval Aerospace Medical Institute (NAMI) at Pensacola where they undergo extensive evaluation and 8 weeks of training in the Self-Paced Airsickness Desensitization (SPAD) program. Researchers at NASA Ames have developed an alternative mitigation training program, Autogenic Feedback Training Exercise (AFTE) that has demonstrated an 80% success rate for improving motion sickness tolerance.

Immunoexpression of PPAR-γ and osteocalcin proteins for bone repair of critical-size defects treated with fragmented autogenous abdominal adipose tissue graft.

PubMed

Deliberador, Tatiana Miranda; Giovanini, Allan Fernando; Lopes, Tertuliano Ricardo; Zielak, João César; Moro, Alexandre; Baratto Filho, Flares; Santos, Felipe Rychuv; Storrer, Carmen L Mueller

2014-01-01

Immunoexpression of PPAR-γ and osteocalcin proteins was evaluated for bone repair of critical-size defects (CSDs), created in rat calvaria (n=42) and treated with fragmented abdominal autogenous adipose tissue graft. Three groups (n=14) were formed: C (control - blood clot), AB (autogenous bone) and AT (fragmented adipose tissue). The groups were divided into subgroups (n=7) for euthanasia at 30 and 90 days. Histological and immunohistochemical analyses were performed. Data were subjected to descriptive statistics (mode). A complete bone closure was observed in Group AB 90 days after surgery. In Group C, repair was achieved by the formation of collagen fiber bundles oriented parallel to the wound surface at both post-surgery periods. In Group AT the type of healing was characterized by dense connective tissue containing collagen fiber bundles arranged amidst the remaining adipose tissue, with rare heterotopic bone formation associated with fibrosis and different types of tissue necrosis. Immunostaining of PPAR-γ was not observed in any specimen from Groups C and AB. In Group AT, the immunostaining of PPAR-γ was more evident 30 days after surgery. Immunostaining of osteocalcin was present in all groups and at both postoperative periods. The fragmented autogenous abdominal adipose tissue graft did not favor the repair of critical-size bone defects created surgically in rat calvaria as evidenced by the positive immunostaining of PPAR-γ protein and the negative immunostaining of osteocalcin in the osteoblast-like cells and bone matrix.

Crack propagation in teeth: a comparison of perimortem and postmortem behavior of dental materials and cracks.

PubMed

Hughes, Cris E; White, Crystal A

2009-03-01

This study presents a new method for understanding postmortem heat-induced crack propagation patterns in teeth. The results demonstrate that patterns of postmortem heat-induced crack propagation differ from perimortem and antemortem trauma-induced crack propagation patterns. Dental material of the postmortem tooth undergoes dehydration leading to a shrinking and more brittle dentin material and a weaker dentin-enamel junction. Dentin intertubule tensile stresses are amplified by the presence of the pulp cavity, and initiates crack propagation from the internal dentin, through the dentin-enamel junction and lastly the enamel. In contrast, in vivo perimortem and antemortem trauma-induced crack propagation initiates cracking from the external surface of the enamel toward the dentin-enamel junction where the majority of the energy of the crack is dissipated, eliminating the crack's progress into the dentin. These unique patterns of crack propagation can be used to differentiate postmortem taphonomy-induced damage from antemortem and perimortem trauma in teeth.

Cocaine/Crack: The Big Lie.

ERIC Educational Resources Information Center

National Inst. on Drug Abuse (DHHS/PHS), Rockville, MD.

This pamphlet focuses on cocaine and crack use and the addictive nature of cocaine/crack. It contains a set of 21 questions about crack and cocaine, each accompanied by a clear and complete response. Interspersed throughout the booklet are photographs and quotes from former cocaine or crack users/addicts. Questions and answers focus on what…

The crack-inclusion interaction problem

NASA Technical Reports Server (NTRS)

Liu, X.-H.; Erdogan, F.

1986-01-01

The general plane elastostatic problem of interaction between a crack and an inclusion is considered. The Green's functions for a pair of dislocations and a pair of concentrated body forces are used to generate the crack and the inclusion. Integral equations are obtained for a line crack and an elastic line inclusion having an arbitrary relative orientation and size. The nature of stress singularity around the end points of rigid and elastic inclusions is described and three special cases of this intersection problem are studied. The problem is solved for an arbitrary uniform stress state away from the crack-inclusion region. The nonintersecting crack-inclusion problem is considered for various relative size, orientation, and stiffness parameters, and the stress intensity factors at the ends of the inclusion and the crack are calculated. For the crack-inclusion intersection case, special stress intensity factors are defined and are calculated for various values of the parameters defining the relative size and orientation of the crack and the inclusion and the stiffness of the inclusion.

The crack-inclusion interaction problem

NASA Technical Reports Server (NTRS)

Xue-Hui, L.; Erdogan, F.

1984-01-01

The general plane elastostatic problem of interaction between a crack and an inclusion is considered. The Green's functions for a pair of dislocations and a pair of concentrated body forces are used to generate the crack and the inclusion. Integral equations are obtained for a line crack and an elastic line inclusion having an arbitrary relative orientation and size. The nature of stress singularity around the end points of rigid and elastic inclusions is described and three special cases of this intersection problem are studied. The problem is solved for an arbitrary uniform stress state away from the crack-inclusion region. The nonintersecting crack-inclusion problem is considered for various relative size, orientation, and stiffness parameters, and the stress intensity factors at the ends of the inclusion and the crack are calculated. For the crack-inclusion intersection case, special stress intensity factors are defined and are calculated for various values of the parameters defining the relative size and orientation of the crack and the inclusion and the stiffness of the inclusion.

Shrinkage Behavior of Polystyrene-based Foam Molded Parts Depending on Volatile Matter Content and Other Factors

NASA Astrophysics Data System (ADS)

Ghafafian, Carineh

Polymer foam materials play a large role in the modern world. Expanded polystyrene (EPS) bead foam is a lightweight, low density, and good thermal and acoustic insulating material whose properties make it attractive for a number of applications, especially as building insulation. However, EPS also experiences post-molding shrinkage; it shrinks dimensionally from its molded size after processing. This means parts must be stored in warehouses until they are considered stable by the industry standard, DIN EN 1603. This often takes 11--18 weeks and is thus very timely and expensive. This study aims to decrease the post-molding shrinkage time of EPS foam by understanding the mechanisms of shrinkage behavior. Samples were split into two groups based on their amount of initial volatile matter content and storage conditions, then compared to a control group. Based on thermogravimetric analysis and gas chromatography with mass spectrometry, the volatile matter content and composition was found to not be the sole contributor to EPS foam dimensional stability. Residual stress testing was done with the hole drilling method and Raman spectroscopy. As this type of testing has not been done with polymer foams before, the aim was to see if either method could reliably produce residual stress values. Both methods measured residual stress values with unknown accuracy. All samples stored at a higher temperature (60°C) reached dimensional stability by the end of this study. Thus, air diffusion into EPS foam, encouraged by the high temperature storage, was found to play a significant role in post-molding shrinkage.

Universal Shapes formed by Interacting Cracks

NASA Astrophysics Data System (ADS)

Fender, Melissa; Lechenault, Frederic; Daniels, Karen

2011-03-01

Brittle failure through multiple cracks occurs in a wide variety of contexts, from microscopic failures in dental enamel and cleaved silicon to geological faults and planetary ice crusts. In each of these situations, with complicated curvature and stress geometries, pairwise interactions between approaching cracks nonetheless produce characteristically curved fracture paths known in the geologic literature as en passant cracks. While the fragmentation of solids via many interacting cracks has seen wide investigation, less attention has been paid to the details of individual crack-crack interactions. We investigate the origins of this widely observed crack pattern using a rectangular elastic plate which is notched on each long side and then subjected to quasistatic uniaxial strain from the short side. The two cracks propagate along approximately straight paths until the pass each other, after which they curve and release a lenticular fragment. We find that, for materials with diverse mechanical properties, the shape of this fragment has an aspect ratio of 2:1, with the length scale set by the initial cracks offset s and the time scale set by the ratio of s to the pulling velocity. The cracks have a universal square root shape, which we understand by using a simple geometric model and the crack-crack interaction.

Transition of Corner Cracks at Holes into Through-The-Thickness Cracks

DTIC Science & Technology

1983-12-01

upon an imaginary crack depth, which is arrived at by allowing the flaw to continually grow in the same elliptical shape it had when it penetrated the...approximately 0.75, and then they deteriorate rapidly . This value of 0.75 agrees with the value selected as the start of the transition region along the bore of...a corner crack emanating from a hole as it grows until it reaches final fracture. However, in a region near where the corner crack penetrates the back

Comparative results of autogenous ignition temperature measurements by ASTM G 72 and pressurized scanning calorimetry in gaseous oxygen

NASA Technical Reports Server (NTRS)

Bryan, C. J.; Lowrie, R.

1986-01-01

The autogenous ignition temperature of four materials was determined by ASTM (G 72) and pressurized differential scanning calorimetry at 0.68-, 3.4-, and 6.8-MPa oxygen pressure. All four materials were found to ignite at lower temperatures in the ASTM method. The four materials evaluated in this program were Neoprene, Vespel SP-21, Fluorel E-2160, and nylon 6/6.

Fusion welding studies using laser on Ti-SS dissimilar combination

NASA Astrophysics Data System (ADS)

Shanmugarajan, B.; Padmanabham, G.

2012-11-01

Laser welding investigations were carried out on dissimilar Ti-SS combination. The study is aimed to improve the weld strength and ductility by minimizing harmful intermetallics and taking advantage of high cooling rates in laser welding. Results of continuous wave 3.5 kW CO2 laser welding of totally dissimilar combination of Titanium and stainless steel (304) have been discussed. Bead on plate welding experiments were conducted to identify the laser welding parameters using depth of penetration as criteria. The welding of dissimilar combination has been attempted both autogenously and with interlayers such as Vanadium (V) and Tantalum (Ta) in the form of laser cladding as well as strip. Autogenous welds were carried out by varying the laser power, welding speed and position of the laser beam with respect to the joint centre. The resultant welds are characterized by macrostructure analysis, SEM/EDAX and XRD and as welded tensile test in UTM. The autogenous welds have exhibited extensive cracking even when welded at high speeds or by manipulating the beam position with respect to the joint. Similarly Vandaium as interlayer could not achieve crack free joint. A joint with 40 MPa strength could be made with Ta as interlayer. Results and analysis of these variants of laser welded joints are reported and discussed.

Fatigue-Crack-Growth Structural Analysis

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.

1986-01-01

Elastic and plastic deformations calculated under variety of loading conditions. Prediction of fatigue-crack-growth lives made with FatigueCrack-Growth Structural Analysis (FASTRAN) computer program. As cyclic loads are applied to initial crack configuration, FASTRAN predicts crack length and other parameters until complete break occurs. Loads are tensile or compressive and of variable or constant amplitude. FASTRAN incorporates linear-elastic fracture mechanics with modifications of load-interaction effects caused by crack closure. FASTRAN considered research tool, because of lengthy calculation times. FASTRAN written in FORTRAN IV for batch execution.

Autogenous bone grafts in the esthetic zone: optimizing the procedure using piezosurgery.

PubMed

Majewski, Piotr

2012-12-01

Soft and hard tissue defects pose a therapeutic challenge in modern implant dentistry. There are a multitude of surgical techniques available, and it is necessary to match the problem with the solution. This report describes the reconstruction of the alveolar ridge in the esthetic zone with the help of autogenous bone blocks harvested from the chin that were shaped to fit and stabilized at the recipient site. The procedures were performed using Piezosurgery, which made it possible to introduce surgical modifications and had a significant impact on the accuracy of the procedure. An observation period of 2 to 7 years showed positive stable results for treatment in terms of function and esthetics.

Evaluation of bridge deck with shrinkage-compensating concrete : VCTIR report detail.

DOT National Transportation Integrated Search

2016-01-01

Concrete bridge decks are susceptible to premature cracking and to corrosion of reinforcing steel. Low-permeability concrete does not always ensure durability if the concrete has excessive cracks that facilitate the intrusion of aggressive solutions....

21 CFR 137.190 - Cracked wheat.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Cracked wheat. 137.190 Section 137.190 Food and... Related Products § 137.190 Cracked wheat. Cracked wheat is the food prepared by so cracking or cutting... such wheat, other than moisture, remain unaltered. Cracked wheat contains not more than 15 percent of...

Crack-tip-opening angle measurements and crack tunneling under stable tearing in thin sheet 2024-T3 aluminum alloy

NASA Technical Reports Server (NTRS)

Dawicke, D. S.; Sutton, M. A.

1993-01-01

The stable tearing behavior of thin sheets 2024-T3 aluminum alloy was studied for middle crack tension specimens having initial cracks that were: flat cracks (low fatigue stress) and 45 degrees through-thickness slant cracks (high fatigue stress). The critical crack-tip-opening angle (CTOA) values during stable tearing were measured by two independent methods, optical microscopy and digital image correlation. Results from the two methods agreed well. The CTOA measurements and observations of the fracture surfaces showed that the initial stable tearing behavior of low and high fatigue stress tests is significantly different. The cracks in the low fatigue stress tests underwent a transition from flat-to-slant crack growth, during which the CTOA values were high and significant crack tunneling occurred. After crack growth equal to about the thickness, CTOA reached a constant value of 6 deg and after crack growth equal to about twice the thickness, crack tunneling stabilized. The initial high CTOA values, in the low fatigue crack tests, coincided with large three-dimensional crack front shape changes due to a variation in the through-thickness crack tip constraint. The cracks in the high fatigue stress tests reach the same constant CTOA value after crack growth equal to about the thickness, but produced only a slightly higher CTOA value during initial crack growth. For crack growth on the 45 degree slant, the crack front and local field variables are still highly three-dimensional. However, the constant CTOA values and stable crack front shape may allow the process to be approximated with two-dimensional models.

Angiogenesis in healing autogenous flexor-tendon grafts.

PubMed

Gelberman, R H; Chu, C R; Williams, C S; Seiler, J G; Amiel, D

1992-09-01

On the basis of recent evidence that flexor tendon grafts may heal without the ingrowth of vascular adhesions, eighteen autogenous donor tendons of intrasynovial and extrasynovial origin were transferred to the synovial sheaths in the forepaws of nine dogs, and controlled passive mobilization was instituted early in the postoperative period. The angiogenic responses of the tendon grafts were determined with perfusion studies with India ink followed by cleaing of the tissues with the Spalteholz technique at two, four, and six weeks. A consistent pattern of neovascularization was noted in the donor tendons of extrasynovial origin. Vascular adhesions arising from the flexor digitorum superficialis and the tendon sheath enveloped the tendon grafts by two weeks. By six weeks, the vascularity of the tendon grafts of extrasynovial origin appeared completely integrated with that of the surrounding tissues. Examination of cross sections revealed that the segments of tendon had been completely vascularized by obliquely oriented intratendinous vessels. In contrast, the flexor tendon grafts of intrasynovial origin healed without ingrowth of vascular adhesions. Primary intrinsic neovascularization took place from the proximal and, to a lesser extent, distal sites of the sutures. Examination of cross sections revealed vessels extending through the surface layer of the tendon graft, with small vessels penetrating the interior of the tendons at regular intervals.

An investigation of the elevated temperature cracking susceptibility of alloy C-22 weld-metal

NASA Astrophysics Data System (ADS)

Gallagher, Morgan Leo

Alloy C-22 is one of the most corrosion resistant Ni-Cr-Mo alloys available today, and is particularly versatile. As a result, Alloy C-22 is being considered for use in the construction of storage canisters for permanent disposal of radioactive waste in the Yucca Mountain Project. However, in such a critical application, weld related defects (such as these two forms of cracking) are simply unacceptable. Solidification cracking occurs when weld shrinkage strains are applied to liquid films that result from microsegregation during solidification. Many nickel-base alloys are susceptible to solidification cracking since they solidify as austenite and many of their alloying additions partition during solidification and form low melting eutectic constituents. The transvarestraint test was used to quantify the susceptibility of Alloy C-22 to solidification cracking. The solidification cracking temperature range (SCTR) was found to be approximately 50°C (90°F); this SCTR predicts that Alloy-C-22 will have only slightly higher susceptibility than known crack-resistant alloys, such as duplex stainless-steel 2205 and austenitic stainless-steel Type 304 (FN6). Ductility-dip cracking (DDC) is a solid-state cracking phenomenon that occurs below the effective solidus temperature in highly restrained austenitic alloys. Although this type of cracking is relatively uncommon, it can be costly in critical applications where there is a low tolerance for defects. This investigation used two separate tests to quantify the susceptibility of the alloy to DDC: the hot-ductility test and the strain-to-fracture (STF) test. The hot-ductility test revealed that Alloy C-22 weld-metal exhibits an intermediate temperature ductility-dip, with ductility recovery at the upper end of the testing temperature range. The ductility minimum in the hot-ductility tests occurred around 950°C (1742°F) in both the on-heating and on-cooling tests. The strain-to-fracture test also revealed Alloy C-22 to be

A Study of Shrinkage Stress Reduction and Mechanical Properties of Nanogel-Modified Resin Systems

PubMed Central

Liu, JianCheng; Howard, Gregory D.; Lewis, Steven H.; Barros, Matthew D.; Stansbury, Jeffrey W.

2012-01-01

A series of nanogel compositions were prepared from urethane dimethacrylate (UDMA) and isobornyl methacrylate (IBMA) in the presence of a thiol chain transfer agent. The linear oligomer of IBMA was synthesized by a similar solution polymerization technique. The nanogels were prepared with different crosslinker concentrations to achieve varied branching densities and molecular weights. The prepolymers were dispersed in triethylene glycol dimethacrylate at loading levels ranging from 10 wt% to 50 wt%. Photopolymerization reaction kinetics of all prepolymer modified systems were enhanced relative to the nanogel-free control during early stage polymerization while limiting conversion was similar for most samples. Volumetric polymerization shrinkage was reduced proportionally with the prepolymer content while the corresponding decrease in polymerization stress was potentially greater than an additive linear behavior. Flexural strength for inert linear polymer-modified systems decreased significantly with the increase in the prepolymer content; however, with an increase in the crosslinker concentration within the nanogel additives, and an increase in the concentration of residual pendant reactive sites, flexural strength was maintained or improved regardless of the nanogel loading level. This demonstrates that covalent attachment rather than just physical entanglement with the polymer matrix is important for effective polymer mechanical reinforcement by nanogel additives. Reactive nanogel additives can be considered as a practical, generic means to achieve substantial reductions in polymerization shrinkage and shrinkage stress in common polymers. PMID:23109731

Report D : self-consolidating concrete (SCC) for infrastructure elements - creep, shrinkage and abrasion resistance.

DOT National Transportation Integrated Search

2012-08-01

Concrete specimens were fabricated for shrinkage, creep, and abrasion resistance : testing. Variations of self-consolidating concrete (SCC) and conventional concrete were : all tested. The results were compared to previous similar testing programs an...

Salivation quantum--stomatopyrosis--autogenic training.

PubMed

Pokupec, Josipa-Sanja Gruden; Gruden, Vladimir; Biocina-Lukenda, Dolores

2009-09-01

Stomatopyrosis of 'burning mouth' syndrome, in a narrower sense of definition, is a condition characterized by sensation of burning and heating in mouth, despite its normal mucosa. This research has been directed towards treatment of stomatopyrosis, putting emphasis on the implementation of psychopharmacotherapy and psychotherapy. The research was conducted on altogether 120 respondents suffering from stomatopyrosis. The respondents were divided into two equal groups: each one comprising 60 members. All the respondents were treated by means of a standard topical therapy. All the patients were assessed clinically and by means of psychological tests measuring depression and anxiety four times: once before the treatment, after one month, after two months and after four months since the beginning of the treatment. The acquired data were afterwards statistically processed. When grading the symptoms on VAS, i.e. visual analogous scale, the subjective assessment of symptoms was marked as 7-8 cm, which shows a high degree of burning sensation. According to our study, the quantity of saliva, which was at the beginning of the research slightly decreased, normalized after the treatment. Apart from the clinical investigation of stomatopyrosis, we applied Depression and Anxiety questionnaires. On the basis of our research, we have concluded the following: the comorbidity of stomatopyrosis with the phenomena of anxiety and depression proves that, among other factors, there is a psychogenic aetiology of this disease. Autogenic training, which is a psychotherapeutic anxiolytic technique, is a therapy of choice for stomatopyrosis, which contributes not only to the elimination of oral complaints, but to the emotional rehabilitation of the patients as well, and to the reduction of dryness in the mouth.

Fatigue Crack Growth and Crack Bridging in SCS-6/Ti-24-11

NASA Technical Reports Server (NTRS)

Ghosn, Louis J.; Kantzos, Pete; Telesman, Jack

1995-01-01

Interfacial damage induced by relative fiber/matrix sliding was found to occur in the bridged zone of unidirectional SCS-6/Ti-24Al-11Nb intermetallic matrix composite specimens subjected to fatigue crack growth conditions. The degree of interfacial damage was not uniform along the bridged crack wake. Higher damage zones were observed near the machined notch in comparison to the crack tip. The interfacial friction shear strength tau(sub f) measured in the crack wake using pushout testing revealed lower values than the as-received interface. Interfacial wear also reduced the strength of the bridging fibers. The reduction in fiber strength is thought to be a function of the magnitude of relative fiber/matrix displacements ind the degree of interfacial damage. Furthermore, two different fiber bridging models were used to predict the influence of bridging on the fatigue crack driving force. The shear lag model required a variable tau(sub f) in the crack wake (reflecting the degradation of the interface) before its predictions agreed with trends exhibited by the experimental data. The fiber pressure model did an excellent job in predicting both the FCG data and the DeltaCOD in the bridged zone even though it does not require a knowledge of tau(sub f).

Corrosion fatigue crack propagation in metals

NASA Technical Reports Server (NTRS)

Gangloff, Richard P.

1990-01-01

This review assesses fracture mechanics data and mechanistic models for corrosion fatigue crack propagation in structural alloys exposed to ambient temperature gases and electrolytes. Extensive stress intensity-crack growth rate data exist for ferrous, aluminum and nickel based alloys in a variety of environments. Interactive variables (viz., stress intensity range, mean stress, alloy composition and microstructure, loading frequency, temperature, gas pressure and electrode potential) strongly affect crack growth kinetics and complicate fatigue control. Mechanistic models to predict crack growth rates were formulated by coupling crack tip mechanics with occluded crack chemistry, and from both the hydrogen embrittlement and anodic dissolution/film rupture perspectives. Research is required to better define: (1) environmental effects near threshold and on crack closure; (2) damage tolerant life prediction codes and the validity of similitude; (3) the behavior of microcrack; (4) probes and improved models of crack tip damage; and (5) the cracking performance of advanced alloys and composites.

Influence of crack history on the stable tearing behavior of a thin-sheet material with multiple cracks

NASA Technical Reports Server (NTRS)

Dawicke, D. S.; Newman, J. C., Jr.; Sutton, M. A.; Amstutz, B. E.

1994-01-01

Fracture tests were conducted on 2.3mm thick, 305mm wide sheets of 2024-T3 aluminum alloy with from one to five collinear cracks. The cracks were introduced (crack history) into the specimens by three methods: saw cutting, fatigue precracking at a low stress range, and fatigue precracking at a high stress range. For the single crack tests, the initial crack history influenced the stress required for the onset of stable crack growth and the first 10mm of crack growth. The effect on failure stress was about 4 percent or less. For the multiple crack tests, the initial crack history was shown to cause differences of more than 20 percent in the link-up stress and 13 percent in failure stress. An elastic-plastic finite element analysis employing the CTOA fracture criterion was used to predict the fracture behavior of the single and multiple crack tests. The numerical predictions were within 7 percent of the observed link-up and failure stress in all the tests.

Fatigue Crack Growth Rate and Stress-Intensity Factor Corrections for Out-of-Plane Crack Growth

NASA Technical Reports Server (NTRS)

Forth, Scott C.; Herman, Dave J.; James, Mark A.

2003-01-01

Fatigue crack growth rate testing is performed by automated data collection systems that assume straight crack growth in the plane of symmetry and use standard polynomial solutions to compute crack length and stress-intensity factors from compliance or potential drop measurements. Visual measurements used to correct the collected data typically include only the horizontal crack length, which for cracks that propagate out-of-plane, under-estimates the crack growth rates and over-estimates the stress-intensity factors. The authors have devised an approach for correcting both the crack growth rates and stress-intensity factors based on two-dimensional mixed mode-I/II finite element analysis (FEA). The approach is used to correct out-of-plane data for 7050-T7451 and 2025-T6 aluminum alloys. Results indicate the correction process works well for high DeltaK levels but fails to capture the mixed-mode effects at DeltaK levels approaching threshold (da/dN approximately 10(exp -10) meter/cycle).

Crack Closure and Fatigue Crack Growth in 2219-T851 Aluminum Alloy

DTIC Science & Technology

1976-08-01

assumes the length of the crack perimeter to remain es - ’I sentially constant. At the maximum load, the crack is ap- proximately parabolic (or ellipical...for center cracked j specimens) in shape. With unloading, the parabola (or el- lipse) is collapsed. The resulting change in shape produces an apparent...reloading process, the electrical potential remained es - j sentially constant initially and was less than that at the corresponding load during unloading

The effect of crack motion during epoxy crack injection and curing.

DOT National Transportation Integrated Search

2005-06-01

One strategy to regain structural integrity of cracked reinforced concrete bridge deck girders is to inject the cracks with epoxy. Many bridge owners allow all traffic to use the bridge during injection and curing, while other bridge owners restrict ...

Shear fatigue crack growth - A literature survey

NASA Technical Reports Server (NTRS)

Liu, H. W.

1985-01-01

Recent studies of shear crack growth are reviewed, emphasizing test methods and data analyses. The combined mode I and mode II elastic crack tip stress fields are considered. The development and design of the compact shear specimen are described, and the results of fatigue crack growth tests using compact shear specimens are reviewed. The fatigue crack growth tests are discussed and the results of inclined cracks in tensile panels, center cracks in plates under biaxial loading, cracked beam specimens with combined bending and shear loading, center-cracked panels and double edge-cracked plates under cyclic shear loading are examined and analyzed in detail.

Polymerization shrinkage of different types of composite resins and microleakage with and without liner in class II cavities.

PubMed

Karaman, E; Ozgunaltay, G

2014-01-01

To determine the volumetric polymerization shrinkage of four different types of composite resin and to evaluate microleakage of these materials in class II (MOD) cavities with and without a resin-modified glass ionomer cement (RMGIC) liner, in vitro. One hundred twenty-eight extracted human upper premolar teeth were used. After the teeth were divided into eight groups (n=16), standardized MOD cavities were prepared. Then the teeth were restored with different resin composites (Filtek Supreme XT, Filtek P 60, Filtek Silorane, Filtek Z 250) with and without a RMGIC liner (Vitrebond). The restorations were finished and polished after 24 hours. Following thermocycling, the teeth were immersed in 0.5% basic fuchsin for 24 hours, then midsagitally sectioned in a mesiodistal plane and examined for microleakage using a stereomicroscope. The volumetric polymerization shrinkage of materials was measured using a video imaging device (Acuvol, Bisco, Inc). Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U-tests. All teeth showed microleakage, but placement of RMGIC liner reduced microleakage. No statistically significant differences were found in microleakage between the teeth restored without RMGIC liner (p>0.05). Filtek Silorane showed significantly less volumetric polymerization shrinkage than the methacrylate-based composite resins (p<0.05). The use of RMGIC liner with both silorane- and methacrylate-based composite resin restorations resulted in reduced microleakage. The volumetric polymerization shrinkage was least with the silorane-based composite.

Observation of Intralaminar Cracking in the Edge Crack Torsion Specimen

NASA Technical Reports Server (NTRS)

Czabaj, Michael W.; Ratcliffe, James G.; Davidson, Barry D.

2013-01-01

The edge crack torsion (ECT) test is evaluated to determine its suitability for measuring fracture toughness associated with mode III delamination growth onset. A series of ECT specimens with preimplanted inserts with different lengths is tested and examined using nondestructive and destructive techniques. Ultrasonic inspection of all tested specimens reveals that delamination growth occurs at one interface ply beneath the intended midplane interface. Sectioning and optical microscopy suggest that the observed delamination growth results from coalescence of angled intralaminar matrix cracks that form and extend across the midplane plies. The relative orientation of these cracks is approximately 45 deg with respect to the midplane, suggesting their formation is caused by resolved principal tensile stresses arising due to the global mode-III shear loading. Examination of ECT specimens tested to loads below the level corresponding to delamination growth onset reveals that initiation of intralaminar cracking approximately coincides with the onset of nonlinearity in the specimen's force-displacement response. The existence of intralaminar cracking prior to delamination growth onset and the resulting delamination extension at an unintended interface render the ECT test, in its current form, unsuitable for characterization of mode III delamination growth onset. The broader implications of the mechanisms observed in this study are also discussed with respect to the current understanding of shear-driven delamination in tape-laminate composites.

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