WorldWideScience

Sample records for early-age autogenous shrinkage

  1. Measurement with corrugated tubes of early-age autogenous shrinkage of cement-based material

    DEFF Research Database (Denmark)

    Tian, Qian; Jensen, Ole Mejlhede

    2009-01-01

    The use of a special corrugated mould enables transformation of volume strain into horizontal, linear strain measurement in the fluid stage. This allows continuous measurement of the autogenous shrinkage of cement-based materials since casting, and also effectively eliminates unwanted influence...... on the measuring results from gravity, temperature variation and mould restraint. In this paper the principle of the corrugated tube measurement is described. A systematic study was carried out on the influence on the measuring results of the material properties, size effects and encapsulated air in the corrugated...... tube. The experimental results show that there is a minor influence on the measuring results of the stiffness and size of the plastic tube as well as of the encapsulated air. However, the influence decreases with the hardening process and becomes negligible a few hours after final set....

  2. Mitigation strategies for autogenous shrinkage cracking

    DEFF Research Database (Denmark)

    Bentz, Dale P.; Jensen, Ole Mejlhede

    2004-01-01

    , the fundamental parameters contributing to the autogenous shrinkage and resultant early-age cracking of concrete are presented. Basic characteristics of the cement paste that contribute to or control the autogenous shrinkage response include the surface tension of the pore solution, the geometry of the pore...... of early-age cracking due to autogenous shrinkage. Mitigation strategies discussed in this paper include: the addition of shrinkage-reducing admixtures more commonly used to control drying shrinkage, control of the cement particle size distribution, modification of the mineralogical composition......, it should be possible to minimize cracking due to autogenous shrinkage via some combination of the presented approaches....

  3. Identification of microcracks caused by autogenous shrinkage

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede; Guang, Ye

    2005-01-01

    Detection and quantification of microcracks caused by restrained autogenous shrinkage in high-performance concrete is difficult. Available techniques either lack the required resolution or may cause further cracks indistinguishable from the original ones. The new technique presented in this paper...... microscopy, electron probe micro analysis, EPMA, and scanning electron microscopy, SEM. A preliminary analysis of the observed microcracks is presented in this paper....

  4. Autogenous Shrinkage of High Strength Lightweight Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    DING Qingjun; TIAN Yaogang; WANG Fazhou; ZHANG Feng; HU Shuguang

    2005-01-01

    The characteristic of autogenous shrinkage ( AS ) and its effect on high strength lightweight aggregate concrete (HSLAC) were studied. The experimental results show that the main shrinkage of high strength concrete is AS and the amount of cement can affect the AS of HSLAC remarkably. At the early stage the AS of HSLAC is lower than that of high strength normal concrete, but it has a large growth at the later stage. The AS of high strength normal concrete becomes stable at 90d age, but HSLAC still has a high AS growth. It is found that adjusting the volume rate of lightweight aggregate, mixing with a proper dosage of fly ash and raising the water saturation degree of lightweight aggregate can markedly reduce the AS rate of HSLAC.

  5. Influence of Nano-SiO2 on the Consistency, Setting Time, Early-Age Strength, and Shrinkage of Composite Cement Pastes

    Directory of Open Access Journals (Sweden)

    Yu Chen

    2016-01-01

    Full Text Available The study outlined the raw materials and mix proportions to prepare composite cement pastes with the addition of silica-based micro- and nanoparticles. The effects of amorphous nano-SiO2 on the early-age properties, including the consistency, setting time, early-age strength, and chemical and autogenous shrinkages, were investigated. Under the condition of the same dosage of superplasticizer used, the consistency of cement paste with nano-SiO2 is higher than that with silica fume. Significant reductions of the initial and final setting times are observed especially for nano-SiO2 addition groups, and the time difference between the initial and final setting times goes up with the increasing proportions of nano-SiO2. The addition of nano-SiO2 is more helpful to the improvement of early-age strengths of the paste with or without fly ash admixed than silica fume additive for the same mass proportion. Both the chemical and autogenous shrinkages of cement paste develop with the increasing amount of micro- or nanolevel silica particles; however, nano-SiO2 plays a more active role than silica fume in inspiring early-age shrinkage. The physical and chemical mechanisms of nano-SiO2 in cement paste are also discussed.

  6. The influence of superabsorbent polymers on the autogenous shrinkage properties of cement pastes with supplementary cementitious materials

    DEFF Research Database (Denmark)

    Snoeck, D.; Jensen, Ole Mejlhede; De Belie, N.

    2015-01-01

    Fly ash and blast-furnace slag containing binders are frequently used in the construction industry and it is important to know the extent of autogenous shrinkage and its (ideal) mitigation by superabsorbent polymers in these systems as a function of their age. In this paper, the autogenous...... shrinkage was determined by manual and automated shrinkage measurements. Autogenous shrinkage was reduced in cement pastes with the supplementary cementitious materials versus Portland cement pastes. At later ages, the rate of autogenous shrinkage is higher due to the pozzolanic activity. Internal curing...

  7. Influence of Cement Particle-Size Distribution on Early Age Autogenous Strains and Stresses in Cement-Based Materials

    DEFF Research Database (Denmark)

    Bentz, Dale P.; Jensen, Ole Mejlhede; Hansen, Kurt Kielsgaard

    2001-01-01

    The influence of cement particle-size distribution on autogenous strains and stresses in cement pastes of identical water-to-cement ratios is examined for cement powders of four different finenesses. Experimental measurements include chemical shrinkage, to quantify degree of hydration; internal...... relative humidity development; autogenous deformation; and eigenstress development, using a novel embedded spherical stress sensor. Because the latter three measurements are conducted under sealed conditions, whereas chemical-shrinkage measurements are made under "saturated" conditions, the National...... controls the initial pore-size distribution of the cement paste, which, in turn, regulates the magnitude of the induced autogenous shrinkage stresses produced by the water/air menisci in the air-filled pores formed throughout the hydration process. The experimental results indicate that a small autogenous...

  8. Shrinkage-reducing admixtures and early-age desiccation in cement pastes and mortars

    DEFF Research Database (Denmark)

    Bentz, D. P.; Geiker, Mette Rica; Hansen, Kurt Kielsgaard

    2001-01-01

    Fundamental studies of the early-age desiccation of cement-based materials with and without a shrinkage-reducing admixture (SRA) have been performed. Studies have been conducted under both sealed and drying conditions. Physical measurements include mass loss, surface tension, X-ray absorption...

  9. Experimental Research on the Autogenous Shrinkage of MK High Performance Concrete

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Calcine and mill kaolin were used under agreeable technological conditions to generate matakaolin (MK). The autogenous shrinkage performance of high performance concrete added with MK was researched. It is shown that MK has an effective inhibitory action to early autogenous shrinkage of cement concrete, and the inhibitory action increases with the increase of MK. The autogenous shrinkage values from 24 hours after placement to 56 days are all higher than those of the contrasted concrete, among which, the value of the concrete with 5% MK is the highest. But the total shrinkage values in 56 days are all less than those of the contrasted test pieces. The total contraction after 24 h of placement decreases as the increase of MK, moreover,it is greatly less than that of the contrasted ones.

  10. Modeling and analyzing autogenous shrinkage of hardening cement paste

    NARCIS (Netherlands)

    Lu, T.; Koenders, E.A.B.

    2014-01-01

    In this paper, a conceptual model for analyzing the plastic part of autogenous deformation of cement paste based on the Arrhenius rate theory will be presented. The autogenous deformation will be calculated from the elastic deformations with inclusion of creep. Different kinds of cement paste with a

  11. Modeling and analyzing autogenous shrinkage of hardening cement paste

    NARCIS (Netherlands)

    Lu, T.; Koenders, E.A.B.

    2014-01-01

    In this paper, a conceptual model for analyzing the plastic part of autogenous deformation of cement paste based on the Arrhenius rate theory will be presented. The autogenous deformation will be calculated from the elastic deformations with inclusion of creep. Different kinds of cement paste with a

  12. Autogenous shrinkage in high-performance cement paste: An evaluation of basic mechanisms

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede; van Breugel, Klaas

    2003-01-01

    In this paper, various mechanisms Suggested to cause autogenous shrinkage are presented. The mechanisms are evaluated from the point of view of their soundness and applicability to quantitative modeling of autogenous shrinkage. The capillary tension approach is advantageous, because it has a sound...... mechanical and thermodynamical basis. Furthermore, this mechanism is easily applicable in a numerical model when dealing with a continuously changing microstructure. In order to test the numerical model, autogenous deformation and internal relative humidity (RH) of a Portland cement paste were measured...... during the first week of hardening. The isothermal heat evolution was also recorded to monitor the progress of hydration and the elastic modulus in compression was measured. RH change, degree of hydration and elastic modulus were used as input data for the calculation of autogenous deformation based...

  13. Autogenous shrinkage of Ducorit S5R ASTM C 1698-09 test method

    DEFF Research Database (Denmark)

    Damkilde, Lars

    The report deals with experimental measurement of autogenous shrinkage of Ducorit S5R according to the test method ASTM C 1698-09. This test method measures the bulk strain of a sealed cementitious specimen, at constant temperature and not subjected to external forces, from the time of final...

  14. Cracking in cement paste induced by autogenous shrinkage

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede; Weiss, Jason

    2009-01-01

    technique allows identification of microcracks while avoiding artefacts induced by unwanted restraint, drying, or temperature variations during sample preparation. Small cylindrical samples of cement paste are cast with steel rods of different diameters in their centre. The rods restrain the autogenous...

  15. Early age shrinkage pattern of concrete on replacement of fine aggregate with industrial by-product

    Directory of Open Access Journals (Sweden)

    R.K. Mishra

    2016-10-01

    Full Text Available This is an experimental work carried out to investigate early age shrinkage pattern of concrete, prepared, on 50% replacement of industrial by-product (like pond ash and granulated blast furnace slag as fine aggregate using OPC, PPC and PSC as a binder. This is to observe the effect of pond ash and slag as they are having some cementitious properties and effect of cement type is also discussed. All the mixes were prepared keeping in view of pumpable concrete without any super plasticizers. Higher shrinkage value indicates the presence of more bleed water or internal moisture. It is concluded that slag is the best option for fine aggregate replacement for concrete making and durable structure.

  16. Influence of Fly Ash and Slag Powder on Autogenous Shrinkage of Cement Mortars%粉煤灰和矿粉对水泥胶砂自收缩的影响

    Institute of Scientific and Technical Information of China (English)

    肖佳; 陈雷; 邢昊

    2011-01-01

    试验研究了粉煤灰和矿粉对水泥胶砂自收缩的影响.结果表明:当胶砂比(质量比)为1∶0.5,水胶比(质量比)为0.3时,随水化龄期延长,水泥胶砂自收缩增大,早期自收缩发展急剧.粉煤灰降低了水泥胶砂的自收缩,随着粉煤灰掺量(质量分数)增大,水泥胶砂自收缩减小;掺10%和20%粉煤灰水泥胶砂的21d自收缩较纯水泥胶砂分别下降了21.1%和29.5%.水化早期(5d前),矿粉掺量(质量分数)在10%~20%时,随着矿粉掺量增大,水泥胶砂自收缩降低;掺10%和20%矿粉水泥胶砂的21 d自收缩较纯水泥胶砂分别增加了11.1%和6.6%.%The influence of fly ash and slag powder on the autogenous shrinkage of cement mortars was studied. The experiment test results indicate that the autogenous shrinkage of cement mortar made with 1:0. 5 binder to sand ratio(by mass) and 0. 3 water to binder ratio(by mass) increases with development of hydration. At early age, rate of autogenous shrinkage develops sharply. Addition of fly ash reduces the autogenous shrinkage of cement mortar, and the autogenous shrinkage of cement mortar decreases with increase of fly ash content(by mass). Compared to pure cement mortar, after hydrated for 21 d , the 10% and 20% of fly ash addition reduce autogenous shrinkage of cement mortar by 21. 1% and 29. 5% respectively. Originally within 5 d, the 10%- 20% (by mass) of slag powder addition decreases autogenous shrinkage of cement mortar. Compared to pure cement mortar, after hydrated for 21 d, the 10% and 20% of slag powder addition increase autogenous shrinkage of cement mortar by 11. 1% and 6. 6% respectively.

  17. Autogenous shrinkage prediction on high-performance concrete of fly ash based on BP neural network

    Science.gov (United States)

    Wang, Baomin; Zhang, Wenping; Wang, Lijiu

    2006-11-01

    The article adopts test data of neural network for autogenous shrinkage to train and predict on the data which doesn't join training. The article's prediction is on the basis of common medium sand, 5-31.5mm limestone rubble, second class fly-ash, P.O42.5 silicate cement, considering factors include five ones such as ratio of water and cement, sand rate, content of cement, content of fly ash, etc.By adjusting various parameters of neural network structure, it obtains three optimized results of neural network simulation. The error between concrete autogtenous shrinkage value of neural network prediction and trial value is within 3%, which can meet requirement of the concrete engineering.

  18. Early-age volume changes of extrudable reactive powder concrete

    Directory of Open Access Journals (Sweden)

    De Noirfontaine M.N.

    2010-06-01

    Full Text Available This article presents a study on the early-age autogenous deformations of Extrudable Reactive Powder Concretes (ERPCs, especially designed for the making of concrete pipes by extrusion. Different ERPC mixtures, with variable amounts of polycarboxylate superplasticizer (SP, have been investigated. Results on 28-day mechanical properties, early-age hydration rate, autogenous shrinkage and premature cracking risk are analyzed and discussed in relation with the ERPC mix parameters.

  19. Early-age volume changes of extrudable reactive powder concrete

    Science.gov (United States)

    Cherkaoui, K.; Courtial, M.; Dunstetter, F.; Khelidj, A.; Mounanga, P.; de Noirfontaine, M. N.

    2010-06-01

    This article presents a study on the early-age autogenous deformations of Extrudable Reactive Powder Concretes (ERPCs), especially designed for the making of concrete pipes by extrusion. Different ERPC mixtures, with variable amounts of polycarboxylate superplasticizer (SP), have been investigated. Results on 28-day mechanical properties, early-age hydration rate, autogenous shrinkage and premature cracking risk are analyzed and discussed in relation with the ERPC mix parameters.

  20. Early-age volume changes of extrudable reactive powder concrete

    OpenAIRE

    De Noirfontaine M.N.; Mounanga P.; Khelidj A.; Dunstetter F.; Cherkaoui K.; Courtial M.

    2010-01-01

    This article presents a study on the early-age autogenous deformations of Extrudable Reactive Powder Concretes (ERPCs), especially designed for the making of concrete pipes by extrusion. Different ERPC mixtures, with variable amounts of polycarboxylate superplasticizer (SP), have been investigated. Results on 28-day mechanical properties, early-age hydration rate, autogenous shrinkage and premature cracking risk are analyzed and discussed in relation with the ERPC mix parameters.

  1. High-performance binders with reduced autogenous shrinkage on the basis of fine cement

    Energy Technology Data Exchange (ETDEWEB)

    Martschuk, V. [Inst. of the Cement Industry, Dusseldorf (Germany)

    2001-07-01

    A study on the hydration of portland cement was presented. The paper presented special features of the chemical shrinkage of cement paste at high and low water-cement ratios. It also described the effect of silica fume on the deformation behaviour of cement paste, as well as on the behaviour of hardened binder paste at water-binder ratios of 0.40 and 0.25. High performance concrete has a high density and a tendency to chemically shrink because of its low water-cement ratio. The study showed that the autogenous shrinkage increases if silica fume is added. Theoretical calculations were performed and showed that the typical addition of silica fume results in an increase in total porosity, and therefore, to the deterioration of the packing density of the binder mixture. The specific surface area of the dry powder is also increased. It was concluded that replacing cement by optimized fine cements improves the theoretical packing density in binders. The hardened cement paste studies showed that this makes a cement that is denser with less tendency to shrink. 7 refs., 3 tabs., 8 figs.

  2. Effect of Pulverized Fuel Ashes on Autogenous Shrinkage and Compressive Strength of Cement Pastes%粉煤灰对水泥浆体自收缩和抗压强度的影响

    Institute of Scientific and Technical Information of China (English)

    郝成伟; 邓敏; 莫立武; 刘开伟

    2011-01-01

    Autogenous shrinkage of cement pastes with different contents of pulverized fuel ashes(PFA) and different water-to-binder ratio were measured by a shrinkage test device. Compressive strength of sealed cement paste were also measured. The influence of PFA on the pore structures and micrograph of hydration products were investigated through mercury intrusion porosimetry(MIP) and scanning electron microscopy(SEM) , on which the influence mechanism was analyzed. Experimental results demonstrated that autogenous shrinkage of cement pastes decreased with the increased contents of PFA at early age (before 7 d) , this may be ascribed to inhibition of PFA on the shrinkage. After 7 d, however, both autogenous shrinkage, and compressive strength of cement pastes increased. This may be attributed to decrease of pore radius and densification of cement hydration products due to the pozzolanic reaction of fly ash.%设计组装了水泥浆体自收缩测量装置,进行了不同粉煤灰掺量和水胶比的水泥浆体自收缩和抗压强度测试,采用压汞测孔仪(MIP)、扫描电镜(SEM)等测试技术研究了粉煤灰对水泥浆体孔结构、产物形貌等微观结构的影响,并对其影响机理进行了分析.结果表明:粉煤灰能够有效抑制水泥浆体的早期自收缩,在7d前,其自收缩随着粉煤灰掺量的增加而减小;与纯硅酸盐水泥浆体相比,粉煤灰水泥浆体7d后的抗压强度增幅较大,但自收缩增长速率也趋于增大;火山灰反应引起的孔径细化、水化产物结构致密是粉煤灰影响水泥浆体自收缩和抗压强度的根本原因.

  3. Self-Shrinkage Behaviors of Waste Paper Fiber Reinforced Cement Paste considering Its Self-Curing Effect at Early-Ages

    Directory of Open Access Journals (Sweden)

    Zhengwu Jiang

    2016-01-01

    Full Text Available The aim of this paper was to study how the early-age self-shrinkage behavior of cement paste is affected by the addition of the waste paper fibers under sealed conditions. Although the primary focus was to determine whether the waste paper fibers are suitable to mitigate self-shrinkage as an internal curing agent under different adding ways, evaluating their strength, pore structure, and hydration properties provided further insight into the self-cured behavior of cement paste. Under the wet mixing condition, the waste paper fibers could mitigate the self-shrinkage of cement paste and, at additions of 0.2% by mass of cement, the waste paper fibers were found to show significant self-shrinkage cracking control while providing some internal curing. In addition, the self-curing efficiency results were analyzed based on the strength and the self-shrinkage behaviors of cement paste. Results indicated that, under a low water cement ratio, an optimal dosage and adding ways of the waste paper fibers could enhance the self-curing efficiency of cement paste.

  4. Can superabsorent polymers mitigate autogenous shrinkage of internally cured concrete without compromising the strength?

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede; Kovler, Konstantin

    2012-01-01

    The paper “Super absorbing polymers as an internal curing agent for mitigation of early-age cracking of high-performance concrete bridge decks” deals with different aspects of using superabsorbent polymers (SAP) in concrete to mitigate self-desiccation. The paper concludes that “Addition of SAP l...

  5. Measurement of volume change in cementitious materials at early ages - Review of testing protocols and interpretation of results

    DEFF Research Database (Denmark)

    Sant, Gaurav; Lura, Pietro; Weiss, Jason

    2006-01-01

    Early-age cracking in concrete bridge decks, pavements, and superstructure elements has served as the impetus for substantial research on early-age shrinkage in cementitious materials. Much of this research has indicated how mixture proportions, constituent materials, and construction operations...... measurement in a rigid mold, and the ASTM C 157 standard. The results of the autogenous and chemical shrinkage tests are compared with one another to describe fully early-age length change. It is shown that through careful experimentation and interpretation, the results of these tests can be completely...

  6. Measurement of volume change in cementitious materials at early ages - Review of testing protocols and interpretation of results

    DEFF Research Database (Denmark)

    Sant, Gaurav; Lura, Pietro; Weiss, Jason

    2006-01-01

    measurement in a rigid mold, and the ASTM C 157 standard. The results of the autogenous and chemical shrinkage tests are compared with one another to describe fully early-age length change. It is shown that through careful experimentation and interpretation, the results of these tests can be completely...

  7. HETEK - Control of Early Age Cracking in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Christensen, Søren Lolk; Dela, Birgitte Friis;

    1997-01-01

    This report deals with autogenous shrinkage of two concretes and the corresponding mortars. The theory of self-desiccation and autogenous deformation is presented. Autogenous shrinkage of mortar is measuredin a paste dilatometer at constant and varying temperatures. Similarly the autogenous...

  8. Surface Modification of Fly Ashes with Carbide Slag and Its Effect on Compressive Strength and Autogenous Shrinkage of Blended Cement Pastes

    Institute of Scientific and Technical Information of China (English)

    HAO Chengwei; DENG Min; MO Liwu; LIU Kaiwei

    2012-01-01

    Surfaces of grade Ⅲ fly ashes were modified through mixing with carbide slag and calcining at 850 ℃ for 1 h.Mineralogical compositions and surface morphology of fly ashes before and after modification were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM),respectively.Effect of surface-modified fly ashes on compressive strength and autogenous shrinkage of blended cement pastes was investigated.Microstructures of cement pastes were examined by backscattered electron (BSE) imaging and mercury intrusion porosimetry (MIP).The experimental results showed that β-C2S was formed on the surfaces of fly ashes after modification.Hydration of β-C2S on the surface-modified fly ashes densified interface zone and enhanced bond strength between particles of fly ashes and hydrated clinkers.In addition,surface modification of fly ashes tended to decrease total porosity and 10-50 nm pores of cement pastes.Surface modification of fly ashes increased compressive strength and reduced autogenous shrinkage of cement pastes.

  9. Effect of Pre-wetted Light-weight Aggregate on Internal Relative Humidity and Autogenous Shrinkage of Concrete

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This research indicates that the gradient of internal relative humidity (IRH) decreases rapidly within 7-day curing age in HPC.The amount of water imported by pre-wetted light-weight aggregate can regulate IRH of concrete.By importing a proper amount of water, the process of the decline of IRH can be delayed and the antogenous shrinkage can be reduced.The relationship among the amount of water imported by pre- wetted lightweight aggregate, IRH and AS was established.The result provides a new method of reducing early AS and enhancing early cracking resistance of HPC.

  10. The effect of fibers on the loss of water by evaporation and shrinkage of concrete

    Directory of Open Access Journals (Sweden)

    N. M. P. Pillar

    Full Text Available Shrinkage is one of the least desirable attributes in concrete. Large areas of exposed concrete surfaces , such as in shotcrete tunnel linings, where it is practically impossible to make a moist cure, are highly susceptible to plastic shrinkage at early ages. The autogenous and drying shrinkage can lead to states of greater than threshold strength, causing fracture, mechanical damage and lack of durability of concrete structures. The addition of fibers can greatly reduce plastic shrinkage, but has limited effect in mitigating autogenous and drying shrinkage. To evaluate the performance of polypropylene and steel fibers to understand their effect on shrinkage of concrete, a study was carried out to relate the loss of water from the paste and the shrinkage during the first 28 days of age, and compare it with a control mix without fiber. The loss of water was obtained by the weight loss of the specimens at different ages, since the only component that could contribute for the loss of weight was the water lost by the paste of the concrete. And the paste itself is the only source of shrinkage. Uniaxial compressive tests from very early ages enabled the determination of time when plastic shrinkage ended. It was observed that the control concrete mix lost three times more water and developed plastic and drying shrinkage 60 % higher than the fiber reinforced concrete mixes. It was possible to demonstrate that the reduced loss of water caused by the incorporation of fibers is related to the mitigation of plastic shrinkage. It was observed that the fibers are effective to restrain the movement of water through the cement paste in the plastic state, however such effect is limited after concrete starts the hardening state.

  11. Influence and Mechanism of Lightweight Aggregates Pre-Saturated with Shrinkage Reducing Admixtures on Autogenous Shrinkage of Cement Mortar%减缩剂预饱和轻骨料对水泥砂浆自收缩的影响及机理

    Institute of Scientific and Technical Information of China (English)

    党玉栋; 钱觉时; 乔墩; 张琳; 贾兴文; 陆福高

    2011-01-01

    Internal curing (IC) and utilizing the shrinkage reducing admixture (SRA) are two effective methods of autogenous shrinkage mitigation. However, IC and SRA have some marked deficiencies when they are used individually. This paper investigated the influences of light weight aggregates pre-saturated with shrinkage reducing admixtures (SRA-LWA) on the autogenous shrinkage and strength of cement mortar; meanwhile, the effects of SRA-LWA on hydration degree and microstructre of interfacial transition zone (ITZ) were also examined. The results indicate that the SRA could reduce the release rate of solution by decreasing the solution's surface tension and increasing the viscosity. With the same amount of SRA, the ability of autogenous shrinkage reduction of SRA-LWA was similar to that of the SRA mixed with cement mortar (SRA-Mixed). However, the SRA-LWA could diminish the adverse impacts of SRA on cement hydration and strength of cement mortar significantly. Further, comparing to light weight aggregates pre-saturated with water (Water-LWA), the SRA-LWA had a more remarkable contribution to shrinkage reduction, and showed the evidence of lower porosity and denser microstructure of ITZ nearby the LWA.%使用内养护(IC)和减缩剂(SRA)是两种可有效降低水泥基材料自收缩的方法,但两者单独采用时存在明显不足.试验研究了减缩剂预饱和的轻骨料对水泥砂浆自收缩、强度、水化程度以及骨料一水泥石基体界面过渡区域的影响.结果表明:由于减缩剂降低溶液表面张力并增加溶液黏度,减缩剂溶液相比水从轻骨料中释放速率明显降低;与直接内掺减缩剂相比,当减缩剂引入量相等时,减缩剂预饱和轻骨料对砂浆自收缩降低程度相近,但其对砂浆强度不利影响则大大降低;与饱水轻骨料内养护措施相比,减缩剂预饱和轻骨料能够显著降低砂浆的自收缩,明显改善骨料与浆体界面区域的孔隙率和微观结构.

  12. Analysis, prediction, and case studies of early-age cracking in bridge decks

    Science.gov (United States)

    ElSafty, Adel; Graeff, Matthew K.; El-Gharib, Georges; Abdel-Mohti, Ahmed; Mike Jackson, N.

    2016-06-01

    Early-age cracking can adversely affect strength, serviceability, and durability of concrete bridge decks. Early age is defined as the period after final setting, during which concrete properties change rapidly. Many factors can cause early-age bridge deck cracking including temperature change, hydration, plastic shrinkage, autogenous shrinkage, and drying shrinkage. The cracking may also increase the effect of freeze and thaw cycles and may lead to corrosion of reinforcement. This research paper presents an analysis of causes and factors affecting early-age cracking. It also provides a tool developed to predict the likelihood and initiation of early-age cracking of concrete bridge decks. Understanding the concrete properties is essential so that the developed tool can accurately model the mechanisms contributing to the cracking of concrete bridge decks. The user interface of the implemented computer Excel program enables the user to input the properties of the concrete being monitored. The research study and the developed spreadsheet were used to comprehensively investigate the issue of concrete deck cracking. The spreadsheet is designed to be a user-friendly calculation tool for concrete mixture proportioning, temperature prediction, thermal analysis, and tensile cracking prediction. The study also provides review and makes recommendations on the deck cracking based mainly on the Florida Department of Transportation specifications and Structures Design Guidelines, and Bridge Design Manuals of other states. The results were also compared with that of other commercially available software programs that predict early-age cracking in concrete slabs, concrete pavement, and reinforced concrete bridge decks. The outcome of this study can identify a set of recommendations to limit the deck cracking problem and maintain a longer service life of bridges.

  13. Autogenous Deformation and Change of the Relative Humidity in Silica Fume-Modified Cement Paste

    DEFF Research Database (Denmark)

    Jensen, Ole mejlhede; Hansen, Per Freiesleben

    1996-01-01

    Even during sealed curing and at a constant temperature a hardening cement paste will deform and the relative humidity within its pores will lower. This autogenous deformation and autogenous relative humidity change may be so significant that the cement paste cracks if the deformation is restrained....... This article focuses on the influence of silica fume addition on autogenous deformation and autogenous relative humidity change. Continuous measurement of autogenous deformation and autogenous relative humidity change for more than 1 year and 1« years, respectively, was performed. The investigations show...... thatsilica fume addition markedly increases the autogenous shrinkage as well as the autogenous relative humidity change....

  14. Autogenous Deformation of Concrete

    DEFF Research Database (Denmark)

    Autogenous deformation of concrete can be defined as the free deformation of sealed concrete at a constant temperature. A number of observed problems with early age cracking of high-performance concretes can be attributed to this phenomenon. During the last 10 years , this has led to an increased...... focus on autogenous deformation both within concrete practice and concrete research. Since 1996 the interest has been significant enough to hold international, yearly conferences entirely devoted to this subject. The papers in this publication were presented at two consecutive half-day sessions...... at the American Concrete Institute’s Fall Convention in Phoenix, Arizona, October 29, 2002. All papers have been reviewed according to ACI rules. This publication, as well as the sessions, was sponsored by ACI committee 236, Material Science of Concrete. The 12 presentations from 8 different countries indicate...

  15. Autogenous Deformation of Concrete

    DEFF Research Database (Denmark)

    Autogenous deformation of concrete can be defined as the free deformation of sealed concrete at a constant temperature. A number of observed problems with early age cracking of high-performance concretes can be attributed to this phenomenon. During the last 10 years , this has led to an increased...... focus on autogenous deformation both within concrete practice and concrete research. Since 1996 the interest has been significant enough to hold international, yearly conferences entirely devoted to this subject. The papers in this publication were presented at two consecutive half-day sessions...... at the American Concrete Institute’s Fall Convention in Phoenix, Arizona, October 29, 2002. All papers have been reviewed according to ACI rules. This publication, as well as the sessions, was sponsored by ACI committee 236, Material Science of Concrete. The 12 presentations from 8 different countries indicate...

  16. Cracking Tendency of Restrained Concrete at Early Ages

    Institute of Scientific and Technical Information of China (English)

    BA Hengjing; SU Anshuang; GAO Xiaojian; TAO Qi

    2008-01-01

    A modified testing system characterized by full automation, steady operation and high accuracy of strain and stress measurements was developed to determine the cracking tendency of high strength concrete (HSC) in restrained condition at early ages. The shrinkage stress and the tensile creep behavior of HSC at early ages were investigated. The influence of W/C ratio and curing conditions on the early-age shrinkage stress and tensile creep was evaluated. It was found that the lower W/C ratio and drying curing condition resulted in higher shrinkage stress, stress induced tensile creep and greater cracking tendency.

  17. On Early Age Crack Formation in FRC Slabs

    DEFF Research Database (Denmark)

    Olesen, John Forbes; Stang, Henrik

    1997-01-01

    The problem of early age crack formation in FRC slabs due to restrained temperature and shrinkage deformations, is given an analytical treatment. A model taking into account the ageing properties of the tensile softening curve and the continued development in the temperature and shrinkage...... deformations after crack initiation, is presented. Based on this model a design strategy for FRC slabs is outlined....

  18. Experimental Research on Early-age Plastic Shrinkage Cracking of Pre-Mixed Mortar by Slab Test Method%预拌砂浆早期塑性收缩开裂平板法试验研究

    Institute of Scientific and Technical Information of China (English)

    吴其峰; 张航

    2014-01-01

    基于平板开裂试验方法,采用正交设计研究了不同因素对预拌砂浆早期塑性收缩开裂的影响。试验结果表明,砂细度模数2.6,粉煤灰I级和外加剂掺量1.2%能有效抑制塑性裂缝的产生和扩展,显著提高砂浆抵抗塑性开裂的能力。%Based on the experimental method of slab test method, the effects of different factors on the plastic shrinkage cracking of pre-mixed mortar were researched by using orthogonal design.The results indicated that sand fineness modulus 2.6,class I fly ash and admixture dosage 1.2% restrained the generation and propagation of plastic shrinkage cracking effectively and improved the crack resistance ability of pre-mixed mortar obviously.

  19. Can superabsorbent polymers mitigate shrinkage in cementitious materials blended with supplementary cementitious materials?

    DEFF Research Database (Denmark)

    Snoeck, Didier; Jensen, Ole Mejlhede; De Belie, Nele

    2016-01-01

    A promising way to mitigate autogenous shrinkage in cementitious materials with a low water-to-binder ratio is internal curing by the use of superabsorbent polymers. Superabsorbent polymers are able to absorb multiple times their weight in water and can be applied as an internal water reservoir...... shrinkage in materials blended with fly ash or blast-furnace slag remain scarce, especially after one week of age. This paper focuses on the autogenous shrinkage by performing manual and automated shrinkage measurements up to one month of age. Without superabsorbent polymers, autogenous shrinkage...... was reduced in cement pastes with the supplementary cementitious materials versus Portland cement pastes. At later ages, the rate of autogenous shrinkage is higher due to the pozzolanic activity of the supplementary cementitious materials. Internal curing by means of superabsorbent polymers is successful...

  20. Measuring autogenous strain of concrete with corrugated moulds

    DEFF Research Database (Denmark)

    Tian, Qian; Jensen, Ole Mejlhede

    2008-01-01

    A reliable technique to quantify autogenous strain is a prerequisite to numerical modeling in stress calculations for high performance concrete. The introducing of a special kind of corrugated tube mould helps to transforming volume strain measurement into liner strain measurement in horizontal...... direction for fluid concrete, which not only realizes the continuous monitoring of the autogenous shrinkage since casting, but also effectively eliminates the disturbance resulting from gravity, temperature variation and mould restraint on measuring results. Based on this measuring technique, this paper...

  1. Thermodynamics of Autogenous Self-healing in Cementitious Materials

    NARCIS (Netherlands)

    Huang, H.

    2014-01-01

    Concrete is a brittle composite cementitious material that easily fractures under tensile loading. Microcracks can appear throughout the concrete prior to application of any load because of temperature-induced strain and autogenous and drying shrinkage. There is no doubt that these cracks provide pr

  2. Thermodynamics of Autogenous Self-healing in Cementitious Materials

    NARCIS (Netherlands)

    Huang, H.

    2014-01-01

    Concrete is a brittle composite cementitious material that easily fractures under tensile loading. Microcracks can appear throughout the concrete prior to application of any load because of temperature-induced strain and autogenous and drying shrinkage. There is no doubt that these cracks provide

  3. Influence of fly ash fineness on water requirement and shrinkage of blended cement mortars

    Directory of Open Access Journals (Sweden)

    Vanissorn Vimonsatit

    2015-12-01

    Full Text Available In this paper, the influence of fly ash fineness on water requirement and shrinkage of blended cement mortar was studied. The results indicate that the water requirement and shrinkage characteristic of the blended cement mortar are dependent on fly ash fineness and replacement level. The use of coarse fly ash slightly reduces the water requirement but greatly reduced the drying and the autogenous shrinkage of the blended cement mortars and the reduction is more with an increase in the fly ash replacement level. The finer fly ashes further reduce the water requirement, but increase the drying and the autogenous shrinkages as compared with coarser fly ash. The incorporation of superplasticizer drastically reduces the water requirement, but the effect on the drying and autogenous shrinkages of the normal Portland cement mortar is small. However, for the fly ash mortar, the use of superplasticizer results in a decrease in drying shrinkage and in a substantial increase in the autogenous shrinkage particularly for the fine fly ash at a high replacement level.

  4. Time-dependent Early-age Behaviors of Concrete under Restrained Condition

    Institute of Scientific and Technical Information of China (English)

    MA Xinwei; CAO Lixin; R D Hooton; H Lam; NIU Changren

    2007-01-01

    To investigate the early-age behaviors of concrete under a restrained condition, a set of apparatus was developed. In this way, the tensile creep and other early-age properties can be investigated in depth. By measuring the modulus of elasticity of concrete, synchronous shrinkage of concrete and steel rings and free shrinkage of concrete, the deformations of concrete ring can be quantified respectively. The experimental results show the tensile stress in concrete is time-dependent, and the stress at cracking is much lower than the tensile strength at that age; the tensile creep plays an important role in relaxing the tensile stress and postponing the cracking of concrete.

  5. Thermodynamics of Autogenous Self-healing in Cementitious Materials

    OpenAIRE

    Huang, H.

    2014-01-01

    Concrete is a brittle composite cementitious material that easily fractures under tensile loading. Microcracks can appear throughout the concrete prior to application of any load because of temperature-induced strain and autogenous and drying shrinkage. There is no doubt that these cracks provide preferential access for aggressive agents to penetrate into the concrete, probably causing corrosion of reinforcement steel and degradation of concrete. As a result, the service life of reinforced co...

  6. The influence of shrinkage reducing admixtures on plastic shrinkage

    Directory of Open Access Journals (Sweden)

    Mora, J.

    2003-12-01

    Full Text Available Shrinkage reducing admixtures (SRAs are viable alternatives for reducing plastic shrinkage cracking in concrete. The objective of the present paper is to study early age plastic shrinkage in restrained concrete elements, where three different SRAs have been used. The influence of the admixture is analyzed through the following measurements: capillary pressure, evaporation, temperature evolution, crack evolution and settlement. The tests for studying the cracking and deformation were made on two different configurations (i.e., restrained prisms with reduced cross-section and restrained panel, in a wind tunnel, with controlled wind temperature and velocity. The conclusions obtained indicate the viability of the use of this type of admixture and the usefulness of the test methods.

    Los aditivos reductores de retracción (SRAs se plantean, hoy en día, como una alternativa viable para reducir la fisuración por retracción plástica. El objetivo del presente artículo es conocer mejor y predecir el comportamiento a primeras edades de la retracción plástica en elementos estructurales coaccionados, a los que se les ha añadido diversos aditivos reductores de retracción (tres tipos diferentes. Esta influencia se analiza a través de las siguientes propiedades: presión capilar, evaporación, evolución de temperaturas, evolución de fisuración, y deformaciones verticales de asentamiento. Los ensayos para estudiar la fisuración y las deformaciones se han realizado sobre diferentes configuraciones (prisma restringido con estrangulamiento y panel restringido, en un túnel de viento, con temperaturas y velocidades de viento controladas. Las conclusiones obtenidas señalan la viabilidad del empleo de este tipo de aditivos y la bondad de los métodos experimentales utilizados.

  7. Veterinary autogenous vaccines.

    Science.gov (United States)

    Hera, A; Bures, J

    2004-01-01

    Autogenous vaccines remain a regulatory issue. They are demanded by practising veterinarians and by animal owners and they are quite widely used, mainly in Central European Countries, the Czech Republic, Hungary and Slovak Republic having probably the longest tradition with these products in Central Europe. The scope given in Article 3, Para. 2 (and/or Article 4 for some countries) of Directive 2001/82/EC applies to these products in the Acceding Countries. As these products are exempt from the harmonised regulation at the EU level, they are regulated by individual countries, the regulation varying from practically no regulatory measures in certain countries to a quite complex and demanding regulation in the other countries. Both risks and benefits are related to these products and they shall be taken into account when regulatory measures are considered. The major risks related to veterinary autogenous vaccines relate to possibility of transmission of TSE agents or other viral, bacterial and/or fungal contaminants. As appropriate and well balanced regulation of these products is deemed necessary, considering the risks related to these products, and based on the fact that national regulatory measures could be considered as a trade barrier under certain circumstances, harmonisation of the key issues or legal admission of the nationally based regulatory measures, including movement of these products from the other Member States, shall be laid down in the EU legislation. The veterinary autogenous vaccines complying with basic quality and safety requirements are thus a very useful tool in the animal health and welfare management but their use should be restricted to situations where there is no authorised veterinary medicinal product available and veterinary autogenous vaccines must not be allowed to replace good farming or veterinary practices.

  8. AUTOGENIC THERAPY IN TENSION HEADACHE

    OpenAIRE

    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.

  9. Development of spraying agent for reducing drying shrinkage of mortar

    Science.gov (United States)

    Fujiwara, Hiromi; Maruoka, Masanori; Liu, Lingling

    2017-02-01

    Mortar used to repair is sometimes exposed to drying state in early ages after construction and a few days later water is sprayed frequently on the surface of the mortar in order to prevent cracks. This research studied on shrinkage characteristic of mortar subjected to drying conditions like this. The result showed that the water spraying on the mortar after initial drying did not have any effect to prevent shrinkage, but increased. And it also showed when various chemical agents are mixed and used in watersprayingit had the prevention effect on shrinkage. This report was to understand this kind of phenomenon and clarify the mechanism. In addition, based on the results, the new spraying agent was developed to reduce drying shrinkage.

  10. Early age damage quantification of actively restrained concrete using inverse analysis

    Science.gov (United States)

    Albanna, Ali

    Early-age cracking can be a significant problem in concrete pavements, floors, and bridge decks. Cracking occurs when the volumetric changes associated with drying, hydration, and temperature reduction are prevented. Good knowledge about the characteristics of early age concrete is necessary to achieve reliable crack control. Volumetric changes due to shrinkage depend on the type of concrete and its components. It has been found that light weight aggregates can work as internal reservoir to supply the concrete matrix with water that is needed during the early age; this process is called internal curing. Also fibers can give more ductility to the concrete and produce less shrinkage. There is a need to better understand the effects of early age uniaxial restraint on long term concrete mechanical performance. In this study, two types of concrete were studied (high performance fiber reinforced concrete and ordinary concrete) under actively restrained loading conditions to assess the effect on the long term fracture toughness and energy. Single edge notched specimens having dimensions of 250 mm x 150 mm x 75 mm and a notch to depth ratio of 0.33 were caste and used in both direct tension and three point bending. The direct tension tests were carried out on a direct tension loading frame constructed in house that was supplied with two mechanical jacks and load cell.

  11. Influence of ultra-fine fly ash on hydration shrinkage of cement paste

    Institute of Scientific and Technical Information of China (English)

    GAO Ying-li; ZHOU Shi-qiong

    2005-01-01

    Hydration shrinkage generated by cement hydration is the cause of autogenous shrinkage of high strength concrete. It may result in the volume change and even cracking of mortar and concrete. According to the data analysis in a series of experimental studies, the influence of ultra-fine fly ash on the hydration shrinkage of composite cementitious materials was investigated. It is found that ultra-fine fly ash can reduce the hydration shrinkage of cement paste effectively, and the more the ultra-fine fly ash, the less the hydration shrinkage. Compared with cement paste without the ultra-fine fly ash, the shrinkage ratio of cement paste reduces from 23.4% to 39.7% when the ultra-fine fly ash replaces cement from 20% to 50%. Moreover, the microscopic mechanism of the ultra-fine fly ash restraining the hydration shrinkage was also studied by scanning electron microscopy, X-ray diffraction and hydrated equations. The results show that the hydration shrinkage can be restrained to a certain degree because the ultra-fine fly ash does not participate in the hydration at the early stage and the secondary hydration products are different at the later stage.

  12. Prediction of residual stress due to early age behaviour of massive concrete structures: on site experiments and macroscopic modelling

    CERN Document Server

    Zreiki, Jihad; Chaouche, Mohend; Moranville, Micheline

    2008-01-01

    Early age behaviour of concrete is based on complex multi-physical and multiscale phenomena. The predication of both cracking risk and residual stresses in hardened concrete structures is still a challenging task. We propose in this paper a practical method to characterize in the construction site the material parameters and to identify a macroscopic model from simple tests. We propose for instance to use a restrained shrinkage ring test to identify a basic early age creep model based on a simple ageing visco-elastic Kelvin model. The strain data obtained from this test can be treated through an early age finite element incremental procedure such that the fitting parameters of the creep law can be quickly identified. The others properties of concrete have been measured at different ages (elastic properties, hydration kinetics, and coefficient of thermal expansion). From the identified early age model, we computed the temperature rise and the stress development in a non reinforced concrete stress for nuclear w...

  13. Mobile Learning and Early Age Mathematics

    Science.gov (United States)

    Peled, Shir; Schocken, Shimon

    2014-01-01

    The ability to develop engaging simulations and constructive learning experiences using mobile devices is unprecedented, presenting a disruption in educational practices of historical proportions. In this paper we describe some of the unique virtues that mobile learning hold for early age mathematics education. In particular, we describe how…

  14. Transitional Thermal Creep of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Freiesleben Hansen, Per

    1999-01-01

    Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete which includes the transitional thermal effect. The model govern both early age concrete and hardened concrete. The development of the material properties in the model are assumed to depend on the hydration process...... and the thermal activation of the water in the microstructure. The thermal activation is assumed to be governed by the Arrhenius principle and the activation energy of the viscosity of water is found applicable in the analysis of experimental data. Changes in temperature create an imbalance in the microstructure...

  15. Transitional Thermal Creep of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard, A. B.; Damkilde, L.; Hansen, Per Freiesleben

    1999-01-01

    Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete that includes the transitional thermal effect. The model governs both early age concrete and hardened concrete. The development of the material properties in the model is assumed to depend on the hydration process...... and the thermal activation of water in the microstructure. The thermal activation is assumed to be governed by the Arrhenius principle, and the activation energy of the viscosity of water is found applicable in the analysis of the experimental data. Changes in temperature create an imbalance in the microstructure...

  16. A Prediction Method of Tensile Young's Modulus of Concrete at Early Age

    Directory of Open Access Journals (Sweden)

    Isamu Yoshitake

    2012-01-01

    Full Text Available Knowledge of the tensile Young's modulus of concrete at early ages is important for estimating the risk of cracking due to restrained shrinkage and thermal contraction. However, most often, the tensile modulus is considered equal to the compressive modulus and is estimated empirically based on the measurements of compressive strength. To evaluate the validity of this approach, the tensile Young's moduli of 6 concrete and mortar mixtures are measured using a direct tension test. The results show that the tensile moduli are approximately 1.0–1.3-times larger than the compressive moduli within the material's first week of age. To enable a direct estimation of the tensile modulus of concrete, a simple three-phase composite model is developed based on random distributions of coarse aggregate, mortar, and air void phases. The model predictions show good agreement with experimental measurements of tensile modulus at early age.

  17. Equipment for measuring autogenous RH-change and autogenous deformation in cement paste and concrete

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Jensen, Ole Mejlhede

    1997-01-01

    Equipment for measuring autogenous RH-change and autogenous deformation in cement paste and concrete are presented. The equipment consists of a Rotronic Hygroskop DT including a measuring chamber for measuring autogenous RH-change in cement paste and concrete, a paste dilatometer for measuring...

  18. GENERALIZED DOUBLE PARETO SHRINKAGE.

    Science.gov (United States)

    Armagan, Artin; Dunson, David B; Lee, Jaeyong

    2013-01-01

    We propose a generalized double Pareto prior for Bayesian shrinkage estimation and inferences in linear models. The prior can be obtained via a scale mixture of Laplace or normal distributions, forming a bridge between the Laplace and Normal-Jeffreys' priors. While it has a spike at zero like the Laplace density, it also has a Student's t-like tail behavior. Bayesian computation is straightforward via a simple Gibbs sampling algorithm. We investigate the properties of the maximum a posteriori estimator, as sparse estimation plays an important role in many problems, reveal connections with some well-established regularization procedures, and show some asymptotic results. The performance of the prior is tested through simulations and an application.

  19. Micromechanical Modeling of Concrete at Early Age

    Science.gov (United States)

    Tuleubekov, Kairat

    The focus of this research is a micromechanical characterization of Portland cement concrete at early age (less than 28 days). Concrete's viscoelastic properties change significantly at early age due to solidification of its matrix component. Bazant's solidification theory models concrete as a material solidifying in time. This approach is generalized to a three-dimensional characterization of a composite material with a solidifying matrix and elastic inclusions. An integral constitutive relationship was obtained using a generalized correspondence principle and homogenization techniques for elastic composite materials. In light of this approach, effective creep properties of composite spherical assemblage with an aging matrix are obtained. In addition, the elastic Hashin-Monteiro model is generalized to account for the effect of the interfacial transition zone properties on concrete creep. An effective computational platform was developed to evaluate operator expressions in order to obtain relaxation and creep functions numerically. Through numerical examples, it is shown that triaxial generalization of Bazant's solidification model enables robust and computationally efficient prediction of creep deformations in Portland cement concrete.

  20. Effect of various Portland cement paste compositions on early-age strain

    Science.gov (United States)

    Guzzetta, Alana G.

    Early-age strain in paste, mortar, and concrete mixtures was investigated using a new method where the specimen shape was a cone frustum. Strain of the specimen from both the horizontal and vertical directions was captured by height change measurement. The volumetric strain was then calculated as a function of the height change and was plotted versus time. A correlation was found between the slopes of the volumetric strain curve resulting from this test method and the initial setting time of the tested material. An initial evaluation of the repeatability of this innovative test method was conducted. The early-age strain effects of aggregate volume, shrinkage reducing admixture, water-cementitious ratio (w/cm), and partial cement replacement with supplementary cementitious materials were tested and individually compared. From these comparisons, it was observed that ambient temperature, bleed water development, and rheological properties had a significant impact on the volumetric strain results. Data showed increased strain as aggregate volume was reduced and as the w/cm was changed from 0.25 up to 0.50. The addition of shrinkage reducing admixture generally caused an increase in the 36-hour volumetric strain value. In most of the mixtures, cement replacement with 20% fly ash or 10% metakaolin reduced the measured volumetric strain when the w/cm was 0.30. Replacement of cement with 10% silica fume caused an insignificant change in volumetric strain results.

  1. Assessment of early-age cracking of high-performance concrete in restrained ring specimens

    Directory of Open Access Journals (Sweden)

    Quang-phu NGUYEN NGUYEN

    2010-03-01

    Full Text Available High-performance concrete (HPC is stronger and more durable than conventional concrete. However, shrinkage and shrinkage cracking are common phenomena in HPC, especially early-age cracking. This study assessed early-age cracking of HPC for two mixtures using restrained ring tests. The two mixtures were produced with water/binder mass ratio (mW/mB of 0.22 and 0.40, respectively. The results show that, with greater steel thickness, the higher degree of restraint resulted in a higher interface pressure and earlier cracking. With steel thickness of 6 mm, 19 mm, and 30 mm, the age of cracking were, respectively, 12 days, 8 days, and 5.4 days with the mW/mB = 0.22 mixture; and 22.5 days, 12.6 days, and 7.1 days with the mW/mB = 0.40 mixture. Cases of the same steel thickness show that the ring specimens with a thicker concrete wall crack later. With the mW/mB = 0.22 mixture, concrete walls with thicknesses of 37.5 mm, 75 mm, and 112.5 mm cracked at 3.4 days, 8.0 days, and 9.8 days, respectively; with the mW/mB = 0.40 mixture, the ages of cracking were 7.1 days, 12.6 days, and 16.0 days, respectively.

  2. Preparation of High Shrinkage Polypropylene

    Institute of Scientific and Technical Information of China (English)

    吕文军; 王华平; 李建梅; 张玉梅

    2001-01-01

    The common PP chips have been used to prepare high shrinkage PP fibers with shrinkage in boiling water higher than 50%. Meanwhile, the process conditions on fiber structure and properties have been discussed in detail. With the increase of drawing temperature, the shrinkage in boiling water of the fiber increases at first,and then decreases in the temperature range from 70℃ to 100℃. The better drawing temperature is from 75℃ to 85℃ according to the melt index of the PP material. The shrinkage in boiling water of PP fiber increases with the increase of pump delivery. The orientation factor and crystallinity increase with the increase of drawing temperature. With an increase in drawing temperature,unit-cell numbers and monomer unit numbers in every crystal nucleus tend to increase, but unit volume crystal nucleus tend to reduce.

  3. Spontaneous shrinkage of vestibular schwannoma

    Directory of Open Access Journals (Sweden)

    Rossana Romani

    2016-01-01

    Conclusion: Early WWR management can be associated with spontaneous shrinkage of VS over time. Prospective clinical study of larger numbers of such cases using the UK VS database may help to identify predictive factors for the spontaneous regression of VS.

  4. The soil reference shrinkage curve

    CERN Document Server

    Chertkov, V Y

    2014-01-01

    A recently proposed model showed how a clay shrinkage curve is transformed to the soil shrinkage curve at the soil clay content higher than a critical one. The objective of the present work was to generalize this model to the soil clay content lower a critical one. I investigated (i) the reference shrinkage curve, that is, one without cracks; (ii) the superficial layer of aggregates, with changed pore structure compared with the intraaggregate matrix; and (iii) soils with sufficiently low clay content where there are large pores inside the intraaggregate clay (so-called lacunar pores). The methodology is based on detail accounting for different contributions to the soil volume and water content during shrinkage. The key point is the calculation of the lacunar pore volume variance at shrinkage. The reference shrinkage curve is determined by eight physical soil parameters: (1) oven-dried specific volume; (2) maximum swelling water content; (3) mean solid density; (4) soil clay content; (5) oven-dried structural...

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Shamsad Ahmad

    2014-01-01

    Full Text Available 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.

  7. Evaluation of autogenous grafts used in vestibuloplasty.

    Science.gov (United States)

    Metin, M; Dolanmaz, D; Alkan, A

    2003-01-01

    Vestibuloplasty is indicated when prosthesis stability is poor due to mandibular or maxillary atrophy. The use of autogenous grafts to provide sufficient vestibular depth is widely accepted. In this retrospective study, the outcomes of vestibuloplasty performed on 41 patients using various types of autogenous grafts (full-thickness skin, dermal, reversed dermal, meshed skin and palatal mucosal) are presented. The best results were obtained with palatal mucosal grafts, but graft size is limited. Meshed skin grafts were shown to be the best alternative.

  8. Self-healing of drying shrinkage cracks in cement-based materials incorporating reactive MgO

    Science.gov (United States)

    Qureshi, T. S.; Al-Tabbaa, A.

    2016-08-01

    Excessive drying shrinkage is one of the major issues of concern for longevity and reduced strength performance of concrete structures. It can cause the formation of cracks in the concrete. This research aims to improve the autogenous self-healing capacity of traditional Portland cement (PC) systems, adding expansive minerals such as reactive magnesium oxide (MgO) in terms of drying shrinkage crack healing. Two different reactive grades (high ‘N50’and moderately high ‘92-200’) of MgO were added with PC. Cracks were induced in the samples with restraining end prisms through natural drying shrinkage over 28 days after casting. Samples were then cured under water for 28 and 56 days, and self-healing capacity was investigated in terms of mechanical strength recovery, crack sealing efficiency and improvement in durability. Finally, microstructures of the healing materials were investigated using FT-IR, XRD, and SEM-EDX. Overall N50 mixes show higher expansion and drying shrinkage compared to 92-200 mixes. Autogenous self-healing performance of the MgO containing samples were much higher compared to control (only PC) mixes. Cracks up to 500 μm were sealed in most MgO containing samples after 28 days. In the microstructural investigations, highly expansive Mg-rich hydro-carbonate bridges were found along with traditional calcium-based, self-healing compounds (calcite, portlandite, calcium silicate hydrates and ettringite).

  9. On the Feasibility of Early-age English learning

    Institute of Scientific and Technical Information of China (English)

    朱静

    2009-01-01

    Children's English learning in China attracts more and more people's attention and is on the teidency of starting at an early age. Under the trend of "learning English from childhood", the author has explored the Criical Period Hypothesis and discussed the younger learners' dsadvantages and older learners'advantages when learning Englsh. and concludes that early-age English learning is not feasible.

  10. Uniaxial Tension Test of Slender Reinforced Early Age Concrete Members

    Directory of Open Access Journals (Sweden)

    Wenbo Zhang

    2011-08-01

    Full Text Available The present study aims to obtain the tensile properties of early age concrete based on a uniaxial tension test employing RC slender members. First, the paper shows that concrete strain is equal to the strain of rebar at the mid-span of the RC member. The tensile Young’s modulus and the strain capacity of early age concrete are estimated using strain measurements. The experiment indicated that the tensile Young’s modulus at an early age is higher than the compressive modulus. This observation was similar to one found in a previous investigation which used a direct tension test of early age concrete. Moreover, the paper describes how an empirical equation for mature concrete can be applied to the relation between uniaxial tensile strength and splitting tensile strength even in early age concrete. Based on a uniaxial tension test, the paper proposes an empirical equation for the relationship between standard bond stresses and relative slip.

  11. Early Age Fracture Mechanics and Cracking of Concrete

    DEFF Research Database (Denmark)

    Østergaard, Lennart

    2003-01-01

    Modern high performance concretes have low water cement ratios and do often include silica fume. Also early age high strength cements are often applied and when all these factors sum up, it turns out that the cracking sensibility is dramatically increased in com- parison with ordinary concrete...... if applied in early age. The results are only valid after 24 hours for fast and normal hardening cements and after 48 hours for slow hardening cements. This is con¯rmed in a finite element model. The fracture properties of early age concrete have been determined. The framework of the investigations has been...

  12. The shrinkage in lime mortars

    Directory of Open Access Journals (Sweden)

    Sánchez, J. A.

    1997-03-01

    Full Text Available Nowadays, the methodology existing to measure the shrinkage in air, developed for paste and cement mortars, has serious problems to be applied to lime mortars, due to its different mechanism of hardening several modifications in Norms UNE 80-113-86 y 80-112-89 make possible the determination of the shrinkage in these traditional mortars.

    La metodología existente en la actualidad para la medida de la retracción de secado, desarrollada para las pastas y los morteros de cemento, presenta serios problemas a la hora de su aplicación a los morteros de cal debido a su distinto mecanismo de endurecimiento. Algunas modificaciones de las normas UNE 80-113-86 y 80-112-89 hacen posible la determinación de la retracción en estos morteros tradicionales.

  13. Autogenous Phenomena in Cement-Based Materials

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    Denne afhandling er skrevet med henblik på opnåelse af den danske doktorgrad i teknik, dr.techn. Den vedrører autogene fænomener i cementbaserede materialer – primært deformation og ændring af den relative luftfugtighed (RF). I afhandlingen er det belyst, hvordan betydningen af disse fænomener bl...

  14. Autogenous Phenomena in Cement-Based Materials

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    modeldannelse og analyse at beskrive de autogene fænomener. Dette studie viser at især det cementbaserede materiales porestruktur spiller en helt central rolle for udvikling af autogent svind. Dette er en væsentlig årsag til at mikrosilica kan forøge autogent svind betydeligt, idet mikrosilica virker forfinende...

  15. Drying Shrinkage Behaviour of Fibre Reinforced Concrete Incorporating Polyvinyl Alcohol Fibres and Fly Ash

    Directory of Open Access Journals (Sweden)

    Amin Noushini

    2014-01-01

    Full Text Available The current study assesses the drying shrinkage behaviour of polyvinyl alcohol fibre reinforced concrete (PVA-FRC containing short-length (6 mm and long-length (12 mm uncoated monofilament PVA fibres at 0.125%, 0.25%, 0.375%, and 0.5% volumetric fractions. Fly ash is also used as a partial replacement of Portland cement in all mixes. PVA-FRC mixes have been compared to length change of control concrete (devoid of fibres at 3 storage intervals: early-age (0–7 days, short-term (0–28 days, and long-term (28–112 days intervals. The shrinkage results of FRC and control concrete up to 112 days indicated that all PVA-FRC mixes exhibited higher drying shrinkage than control. The shrinkage exhibited by PVA-FRC mixes ranged from 449 to 480 microstrain, where this value was only 427 microstrain in the case of control. In addition, the longer fibres exhibited higher mass loss, thus potentially contributing to higher shrinkage.

  16. Accounting for PDMS shrinkage when replicating structures

    DEFF Research Database (Denmark)

    Madsen, Morten Hannibal; Feidenhans'l, Nikolaj Agentoft; Hansen, Poul-Erik

    2014-01-01

    are seldom applied to counteract the shrinkage of PDMS. Also, to perform metrological measurements using replica techniques one has to take the shrinkage into account. Thus we report a study of the shrinkage of PDMS with several different mixing ratios and curing temperatures. The shrinkage factor, with its...... associated uncertainty, for PDMS in the range 40 to 120 °C is provided. By applying this correction factor, it is possible to replicate structures with a standard uncertainty of less than 0.2% in lateral dimensions using typical curing temperatures and PDMS mixing ratios in the range 1:6 to 1:20 (agent:base)....

  17. Shrinkage behavior of self-compacting concrete

    Institute of Scientific and Technical Information of China (English)

    Farhad ASLANI; Shami NEJADI

    2012-01-01

    In the structures where long-term behavior should be monitored and controlled,creep and shrinkage effects have to be included precisely in the analysis and design procedures.Shrinkage varies with the constituent and mixture proportions,and depends on the curing conditions and the work environment as well.Self-compacting concrete (SCC) contains combinations of various components,such as aggregate,cement,superplasticizer,water-reducing agent and other ingredients which affect the properties of the SCC including shrinkage.Hence,the realistic prediction shrinkage strains of SCC are an important requirement of the design process for this type of concrete structures.This study reviews the accuracy of the conventional concrete (CC) shrinkage prediction models proposed by the international codes of practice,including CEB-FIP (1990),ACI 209R (1997),Eurocode 2 (2001),JSCE (2002),AASHTO (2004; 2007) and AS 3600 (2009).Also,SCC shrinkage prediction models proposed by Poppe and De Schutter (2005),Larson (2007),Cordoba (2007) and Khayat and Long (2010) are reviewed.Further,a new shrinkage prediction model based on the comprehensive analysis on both of the available models,i.e.,the CC and the SCC is proposed.The predicted shrinkage strains are compared with the actual measured shrinkage strains in 165 mixtures of SCC and 21 mixtures of CC.

  18. Lattice Modeling of Early-Age Behavior of Structural Concrete

    Science.gov (United States)

    Pan, Yaming; Prado, Armando; Porras, Rocío; Hafez, Omar M.; Bolander, John E.

    2017-01-01

    The susceptibility of structural concrete to early-age cracking depends on material composition, methods of processing, structural boundary conditions, and a variety of environmental factors. Computational modeling offers a means for identifying primary factors and strategies for reducing cracking potential. Herein, lattice models are shown to be adept at simulating the thermal-hygral-mechanical phenomena that influence early-age cracking. In particular, this paper presents a lattice-based approach that utilizes a model of cementitious materials hydration to control the development of concrete properties, including stiffness, strength, and creep resistance. The approach is validated and used to simulate early-age cracking in concrete bridge decks. Structural configuration plays a key role in determining the magnitude and distribution of stresses caused by volume instabilities of the concrete material. Under restrained conditions, both thermal and hygral effects are found to be primary contributors to cracking potential. PMID:28772590

  19. Influence Of Volcanic Scoria On Mechanical Strength, Chemical Resistance And Drying Shrinkage Of Mortars

    Directory of Open Access Journals (Sweden)

    Al-Swaidani A.

    2014-09-01

    Full Text Available In the study, three types of cement have been prepared; one CEM I type (the control sample and two blended cements: CEM II/A-P and CEM II/B-P (EN 197-1, each of them with three replacement levels of volcanic scoria: (10 %, 15 %, 20 % wt. and (25 %, 30 %, 35 % wt., respectively. Strength development of mortars has been investigated at 2, 7, 28 and 90 days curing. Evaluation of chemical resistance of mortars containing scoria-based cements has been investigated through exposure to 5 % sulphate and 5 % sulphuric acid solutions in accordance with ASTM C1012 & ASTM 267, respectively. Drying shrinkage has been evaluated in accordance with ASTM C596. Test results showed that at early ages, the mortars containing CEM II/B-P binders had strengths much lower than that of the control mortar. However, at 90 days curing, the strengths were comparable to the control mortar. In addition, the increase of scoria significantly improved the sulphate resistance of mortars. Further, an increase in scoria addition improved the sulphuric acid resistance of mortar, especially at the early days of exposure. The results of drying shrinkage revealed that the CEM II/B-P mortar bars exhibited a greater contraction when compared to the control mortar, especially at early ages. However, drying shrinkage of mortars was not influenced much at longer times.

  20. The Use of Frozen Autogenous Bone Flap for Cranioplasty

    Directory of Open Access Journals (Sweden)

    Houshang Moin

    2005-11-01

    Full Text Available Background: The artificial methods of cranioplasty such as using metals or alloplastic materials have some disadvantages, comparning with autogenic bone flaps. We tried to show that the autogenic flaps have less complications when used in cranioplasty. Methods: With good sealing of bone flap after extraction and preserving in -70 to -800 C, in Immounology Department, the autogenic bone was fixed in the previous site. Results: From 10 patients, one of them developed infection and osteomyelitic bone was extracted. No bone resorption was detected. Background: Comparing with other studies of autogenous bone flap cranioplasty, we have similar rate of complication. In other studies, the rate of infection was almost equal to our results. So using autogenous bone in our center is advisable. Key words: cranioplasty, autogenous bone, frozen bone, infection

  1. Autogenic Drainage in Children With Cystic Fibrosis.

    Science.gov (United States)

    Corten, Lieselotte; Morrow, Brenda M

    2017-04-01

    Airway clearance is an essential part of the management of cystic fibrosis (CF) as it facilitates clearance of viscous pulmonary secretions. This review aimed to determine the effect of autogenic drainage (AD) and assisted autogenic drainage (AAD) compared with no, sham, or other types of airway clearance in children with CF. Two pediatric randomized cross-over trials were identified on the use of AD in children with CF; no studies were available on the use of AAD. In one study AD had a positive influence on the Huang score, and is preferred over postural drainage in this population. We could not determine the efficacy of AD and AAD in children with CF. We recommend the implementation of pediatric-specific randomized controlled trials with adequate sample sizes, appropriate clinical outcome measures, and analysis of adverse effects.

  2. Autogenic drainage: efficacy of a simplified method.

    Science.gov (United States)

    Lindemann, H; Boldt, A; Kieselmann, R

    1990-01-01

    A simplified and modified technique of the original autogenic drainage (AD) is described which is supplemented by breathing against an external flow resistance. The new method allows a better teaching and learning. It's efficacy is proven by means of a comparative trial of AD and PEP physiotherapy (i.e. expiration against a defined stenosis). The autogenic drainage (AD) was introduced by a Belgian working group (2). The basic idea was to support the elimination of mucus by deep breathing and by repressing the cough as long as possible. However, a rather sophisticated method impeded teaching and learning of AD (1). Thus, till now, there are only preliminary results which suggest the efficacy of AD (e.g. 3). Therefore, a simplified technique was developed and examined with regard to its sputum eliminating effect.

  3. Autogenic training as a therapy for adjustment disorder in adults

    OpenAIRE

    Jojić Boris R.; Leposavić Ljubica M.

    2005-01-01

    Introduction. 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 accord...

  4. Autogenic training as a therapy for adjustment disorder in adolescents

    OpenAIRE

    Jojić Boris R.; Leposavić Ljubica M.

    2005-01-01

    INTRODUCTION 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,...

  5. Ultrasonic Techniques for Air Void Size Distribution and Property Evaluation in Both Early-Age and Hardened Concrete Samples

    Directory of Open Access Journals (Sweden)

    Shuaicheng Guo

    2017-03-01

    Full Text Available Entrained air voids can improve the freeze-thaw durability of concrete, and also affect its mechanical and transport properties. Therefore, it is important to measure the air void structure and understand its influence on concrete performance for quality control. This paper aims to measure air void structure evolution at both early-age and hardened stages with the ultrasonic technique, and evaluates its influence on concrete properties. Three samples with different air entrainment agent content were specially prepared. The air void structure was determined with optimized inverse analysis by achieving the minimum error between experimental and theoretical attenuation. The early-age sample measurement showed that the air void content with the whole size range slightly decreases with curing time. The air void size distribution of hardened samples (at Day 28 was compared with American Society for Testing and Materials (ASTM C457 test results. The air void size distribution with different amount of air entrainment agent was also favorably compared. In addition, the transport property, compressive strength, and dynamic modulus of concrete samples were also evaluated. The concrete transport decreased with the curing age, which is in accordance with the air void shrinkage. The correlation between the early-age strength development and hardened dynamic modulus with the ultrasonic parameters was also evaluated. The existence of clustered air voids in the Interfacial Transition Zone (ITZ area was found to cause severe compressive strength loss. The results indicated that this developed ultrasonic technique has potential in air void size distribution measurement, and demonstrated the influence of air void structure evolution on concrete properties during both early-age and hardened stages.

  6. Mathematical Modelling and Experimental Analysis of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe

    1997-01-01

    The report deals with mathematical models for concrete at early age. In the hardening process chemical reactions take place and the concrete skeleton is created. The processes changes the moisture content and produces heat. The associated temperature rise gives expansion of the material which may...

  7. Early age performance of latex-modified concrete bridge deck overlays

    Science.gov (United States)

    Sujjavanich, Suvimol

    Environmental factors and physical properties of latex modified concrete (LMC) are hypothesized to contribute to early age cracking in bridge deck overlays. Cracking permits the ingress of moisture and aggressive solutions into the substrate and may contribute to other subsequent distresses. Understanding the material properties and mechanisms involved is necessary to minimize these distresses. This research consisted of a two part study: first, the development of LMC strength and fracture properties at ages ranging from 5 hours to 28 days was studied, and secondly, the effects of the environment on LMC distresses were modelled. Environmental conditions: temperature, solar energy, and wind speed were determined from weather records. A fracture mechanics based model, the Fictitious Crack Model (FCM), incorporating finite element analyses and superposition techniques was employed with material properties from the first part of study on LMC performance. Different bilinear strain softening diagrams were used to predict fracture performance at different ages. The predictions agreed well with the test data. The impacts of temperature differentials on crack development were studied. The shrinkage effect was also indirectly incorporated through the temperature analysis. The material properties study indicated significant changes in strength, deformability and fracture properties, particularly during the early age. The developments differ slightly from conventional concrete. Test results indicated a significant improvement in reducing and bridging microcracks, especially in the prepeak-load region. Fracture toughness and deformability increased significantly with time. Fracture energy varied from 2.3 to 133.1 N/m, depending on age, and to some degree, on notch depth ratio. In the second stage, the FCM provided a reasonable prediction for crack initiation and propagation when only temperature effects are of concern. Age, surface conditions and structural restraint strongly

  8. Compressed sensing recovery via nonconvex shrinkage penalties

    Science.gov (United States)

    Woodworth, Joseph; Chartrand, Rick

    2016-07-01

    The {{\\ell }}0 minimization of compressed sensing is often relaxed to {{\\ell }}1, which yields easy computation using the shrinkage mapping known as soft thresholding, and can be shown to recover the original solution under certain hypotheses. Recent work has derived a general class of shrinkages and associated nonconvex penalties that better approximate the original {{\\ell }}0 penalty and empirically can recover the original solution from fewer measurements. We specifically examine p-shrinkage and firm thresholding. In this work, we prove that given data and a measurement matrix from a broad class of matrices, one can choose parameters for these classes of shrinkages to guarantee exact recovery of the sparsest solution. We further prove convergence of the algorithm iterative p-shrinkage (IPS) for solving one such relaxed problem.

  9. Autogenic training as a therapy for adjustment disorder in adults

    Directory of Open Access Journals (Sweden)

    Jojić Boris R.

    2005-01-01

    Full Text Available Introduction. 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. Aim. 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. Method. 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. Results. 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. Conclusion. 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.

  10. Autogenic training as a therapy for adjustment disorder in adolescents

    Directory of Open Access Journals (Sweden)

    Jojić Boris R.

    2005-01-01

    Full Text Available INTRODUCTION 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. OBJECTIVE 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 efficacy of autogenic training as a therapy for adjustment disorder in adolescents. METHOD 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. RESULTS 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. CONCLUSION 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

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

    Science.gov (United States)

    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.

  12. Modelling autogenous expansion for magnesia concrete in arch dams

    Institute of Scientific and Technical Information of China (English)

    Feng JIN; Guoxin ZHANG; Xiaoqing LUO; Chuhan ZHANG

    2008-01-01

    Magnesia Concrete is a kind of expansive con-crete used in Chinese hydraulic engineering more and more widely. To evaluate the effects of autogenous expan-sion on the stresses of arch dams, a simple model of auto-genous expansion for Magnesia Concrete in dam engineering is presented. This model is based on three assumptions: 1) the total amount of autogenous expan-sion of Magnesia Concrete is related only to the properties of materials and mixing of concrete; 2) the autogenous expansion of Magnesia Concrete is irreversible due to the irreversibility of hydration reaction of Magnesia in the concrete; 3) the autogenous expansion strain rates of Magnesia Concrete bear a relation between temperature and residual Magnesia per unit volume of concrete. The model is verified by some experimental data of autogen-ous expansion of Magnesia Concrete and field-measured data of an arch dam in China. Embedded into finite ele-ment arch dam simulation software, this model is employed to simulate the effects of autogenous expansion of Magnesia Concrete in hydraulic engineering.

  13. Shrinkage assessment of low shrinkage composites using micro-computed tomography.

    Science.gov (United States)

    Hirata, Ronaldo; Clozza, Emanuele; Giannini, Marcelo; Farrokhmanesh, Ehsan; Janal, Malvin; Tovar, Nick; Bonfante, Estevam A; Coelho, Paulo G

    2015-05-01

    The aim of this study was to quantify the polymerization volumetric shrinkage of one regular and two low shrinkage bulk fill composites in class I cavities with or without an adhesive layer, using three-dimensional (3D) micro-computed tomography (μCT). Class I cavity preparations (2.5 mm depth × 4 mm length × 4 mm wide) were standardized in 36 extracted human third molars, which were randomly divided in six groups (n = 6 each) as follows: Group VIT (regular composite without bonding agent); Group SDR (low shrinkage flowable composite without bonding agent); Group TET (low shrinkage composite without bonding agent); Group VIT/P (regular composite with bonding agent); Group SDR/X (low shrinkage flowable composite with bonding agent); TET/T (low shrinkage composite with bonding agent). Each tooth was scanned via µCT at cavity preparation, immediately after cavity filling, and after light-curing. Acquired μCT data were imported into Amira software for analysis and volume values evaluated between steps from cavity preparation until light-curing. Both low shrinkage composites showed a significantly less volumetric shrinkage than VIT. The use of dental adhesive significantly decreased the average volumetric contraction similarly for the three composites, by about 20%. Both low shrinkage composites showed less volumetric polymerization contraction than the regular composite. The use of dental adhesive decreased the total volumetric shrinkage for all evaluated composites. © 2014 Wiley Periodicals, Inc.

  14. Pregnancy, Maternal Tobacco Smoking, and Early Age Leukemia in Brazil

    OpenAIRE

    2012-01-01

    Background: Cigarette smoking has been associated with acute myeloid leukemia but hypothesis on the association between maternal smoking during pregnancy and childhood leukemia is unclear. Objectives: To investigate the association between maternal exposure to tobacco smoking during pregnancy and early age (< 2 yr.) leukemia (EAL). Methods: A hospital-based multicenter case-control study aiming to explore EAL risk factors was carried out in Brazil during 1999-2007. Data were collected by ...

  15. Control of Early Age Concrete. Phase 3: Creep in Concrete

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Hansen, Per Freiesleben

    1997-01-01

    The mechanical properties of the "Road Directorate Concrete" at early ages are studied. Creep in tension at 24 and 72 maturity hours are measured on dogbone shaped specimens. The development of tensile modulus of elasticity and strength are measured with a method developed here. The results...... are compared to compression values and splitting strengths. It is found that the properties of creep in tension are similar to the properties in compression. Further the influence form temperature on creep is found to be significant....

  16. Monitoring early age cementitious materials using ultrasonic guided waves

    Science.gov (United States)

    Borgerson, Jacob L.

    The evaluation of early age concrete is critical for reducing construction times and ensuring quality. In this study, the use of ultrasonic guided waves for monitoring the development of early age cementitious materials is investigated. A torsional wave is transmitted and received through a waveguide that is embedded in early age mortar or concrete. As the cementitious material sets and hardens, the received wave(s) change, indicating the transition from a semifluid to a solid state. This thesis proposes two systems. The first system is a through-transmission system; a wave is transmitted on one end of an embedded waveguide using a sensor arrangement and then it is received on the opposite end of the rod with another sensor. This approach monitors the attenuation of the fundamental torsional wave mode, resulting from the leakage of energy from the cylindrical steel rod to the surrounding cementitious material. The evolution of the material's properties is related to the energy leakage or attenuation of the guided wave. The second system is a pulse-echo system; a wave is transmitted on one end of a partially embedded waveguide via a sensor arrangement that also receives the reflected signals. This approach monitors both the reflection from the end of the rod and the reflection from the point where the waveguide enters the material. The development of the cementitious material's mechanical properties is related to both the energy leaked into the surrounding material and the energy reflected at the point of entry. The ability of this method to only require access to one side of the specimen makes it attractive for monitoring early age cementitious materials in the field. Experiments were performed on mixtures with varying water-cement ratios (w/c = 0.40, 0.50, and 0.60), chemical admixtures (accelerant and retardant), mineral admixtures (silica fume and fly ash), and coarse aggregate (pea gravel). The time of setting and compressive strength of the various mixtures

  17. Breast specimen shrinkage following formalin fixation

    Directory of Open Access Journals (Sweden)

    Horn CL

    2014-02-01

    Full Text Available Christopher L Horn, Christopher Naugler Department of Pathology and Laboratory Medicine, University of Calgary, and Calgary Laboratory Services, Calgary, AB, Canada Abstract: Accurate measurement of primary breast tumors and subsequent surgical margin assessment is critical for pathology reporting and resulting patient therapy. Anecdotal observations from pathology laboratory staff indicate possible shrinkage of breast cancer specimens due to the formalin fixation process. As a result, we conducted a prospective study to investigate the possible shrinkage effects of formalin fixation on breast cancer specimens. The results revealed no significant changes in tumor size, but there were significant changes in the distance to all surgical resection margins from the unfixed to fixed state. This shrinkage effect could interfere with the accuracy of determining distance to margin assessment and tumor-free margin assessment. Thus, changes in these measurements due to the formalin fixation process have the potential to alter treatment options for the patient. Keywords: breast margins, formalin, shrinkage, cancer

  18. A Shrinkage Estimator for Combination of Bioassays

    Institute of Scientific and Technical Information of China (English)

    Jian Xiong; D.G. Chen; Zhen-hai Yang

    2007-01-01

    A shrinkage estimator and a maximum likelihood estimator are proposed in this paper for combination of bioassays. The shrinkage estimator is obtained in closed form which incorporates prior information just on the common log relative potency after the homogeneity test for combination of bioassays is accepted. It is a practical improvement over other estimators which require iterative procedure to obtain the estimator for the relative potency. A real data is also used to show the superiorities for the newly-proposed procedures.

  19. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  20. Influence of Shrinkage-Reducing Admixtures on the Development of Plastic Shrinkage Cracks

    DEFF Research Database (Denmark)

    Lura, Pietro; Pease, Bradley Justin; Mazzotta, Guy;

    2007-01-01

    settlement of the concrete and tensile stress development in the surface of the concrete, which increase the potential for development of plastic shrinkage cracks. Specifically, this paper studies the development of plastic shrinkage cracks in mortars containing a commercially available shrinkage......-reducing admixture (SRA). Mortars containing SRA show fewer and narrower plastic shrinkage cracks than plain mortars when exposed to the same environmental conditions. It is proposed that the lower surface tension of the pore fluid in the mortars containing SRA results in less evaporation, reduced settlement......, reduced capillary tension, and lower crack-inducing stresses at the topmost layer of the mortar....

  1. Development of novel low shrinkage dental nanocomposite

    Science.gov (United States)

    Sun, Yi; Wu, Xiaorong; Liu, Yanju; Xie, Weili; Sun, Shouhua

    2009-07-01

    It has been the focus to develop low shrinkage dental composite resins in recent ten years. A major difficulty in developing low shrinkage dental materials is their deficiency in mechanical properties to clinical use. This paper reviews the present investigations of low shrinkage dental composite resins and attempts to develop a novel system with multifunctional POSS incorporated. In this paper, it is especially interesting to evaluate the influences of shrinkage with different weight percentage of POSS (0~15wt%) incorporated in dental composite resins. Their double bond conversions are evaluated and their microstructures are characterized with Fourier-transform infra-red spectroscopy and X-ray diffraction. Their mechanical properties are also presented in this paper. The results show that the shrinkage of nanocomposites with POSS can be reduced effectively from 3.53% to 2.18%. The mechanical properties of this novel system, such as strength, hardness and toughness, are also enhanced greatly. Especially with 2wt%POSS incorporated, the best integrative improved effects are revealed. The mechanism of shrinkage is discussed.

  2. [Autogenic training in psychophysiological preparation for parachute jumps].

    Science.gov (United States)

    Reshetnikov, M M

    1978-01-01

    The efficiency of specific psychophysiological preparation--autogenic training--to parachute jumps was measured in two groups of cadets (test subjects and controls). Hetero- and autogenic training was carried out according to a scheme specially developed for this type of activity. The study of questionnaires and physiological data demonstrated that the specific psychophysiological preparation by means of autogenic training for a certain type of activity helped to develop active self-control over one's own state and emotions, alleviated tension, arrested adverse neurotic manifestations (sleep disturbances, depression, anxiety), contributed to the feeling of confidence in the successful completion of the jump and promoted positive tuning towards subsequent jumps.

  3. Moulding Faces at an Early Age-A Case Series

    Science.gov (United States)

    Sunny, Sunil; Mathew, Neethu; Parambath, Anvar Kizhakke; Madhusudanan, Amla

    2016-01-01

    Certain malocclusions have to be treated at an early age to avoid surgeries for the correction in the future. Introduction of functional appliances has reduced the elimination and correction of skeletal as well as dental discrepancies. Proper case selection taking into consideration skeletal and dental age with the use of various diagnostic aids helps us to identify and treat the malocclusions before it is too late. In this case series, we report three patients with skeletal jaw malrelationship treated with functional and orthopaedic appliances. PMID:27656599

  4. Autogenous Transplantation for Replacing a Hopeless Tooth

    Science.gov (United States)

    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. PMID:28179939

  5. Airway physiology, autogenic drainage, and active cycle of breathing.

    Science.gov (United States)

    Lapin, Craig D

    2002-07-01

    Airway clearance techniques are used to aid in mucus clearance in a variety of disease states. Autogenic drainage and active-cycle-of-breathing technique are 2 such modalities that rely heavily on basic airway physiology to enhance clearance. In this review I discuss the equal pressure point, huffing, and asynchronous and collateral ventilation, and review the literature and theory regarding autogenic drainage and active cycle of breathing. Selection of airway clearance techniques is discussed in the light of evidence-based medicine.

  6. Shrinkage Properties of Cement Stabilized Gravel

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard

    2014-01-01

    Cement stabilized gravel is an attractive material in road construction because its strength prop-erties are accommodating the increasingly higher requirements to the bearing capacity of a base course. However, reflection cracking of cement stabilized gravel is a major concern. In this pa......-per the shrinkage properties of cement stabilized gravel have been documented under various temperature and relative humidity conditions. Two cement contents corresponding to a 28-days compressive strength of 6.2 MPa and 12.3 MPa have been tested and compared. It is found that the coefficient of linear expansion...... for the two cement contents is 9.9 × 10-6 ⁰C-1 and 11.3 × 10-6 ⁰C-1, respectively. Furthermore, it is found that reflecting cracking can mainly be explained by temperature dependent shrinkage rather than moisture dependent shrinkage....

  7. How pregnancy at early age protects against breast cancer.

    Science.gov (United States)

    Meier-Abt, Fabienne; Bentires-Alj, Mohamed

    2014-03-01

    Pregnancy at an early age has a strong protective effect against breast cancer in humans and rodents. Postulated mechanisms underlying this phenomenon include alterations in the relative dynamics of hormone and growth factor-initiated cell fate-determining signaling pathways within the hierarchically organized mammary gland epithelium. Recent studies in epithelial cell subpopulations isolated from mouse and human mammary glands have shown that early pregnancy decreases the proportion of hormone receptor-positive cells and causes pronounced changes in gene expression as well as decreased proliferation in stem/progenitor cells. The changes include downregulation of Wnt and transforming growth factor β (TGFβ) signaling. These new findings highlight the importance of cell-cell interactions within the mammary gland epithelium in modulating cancer risk and provide potential targets for breast cancer prevention strategies.

  8. A Bayesian Shrinkage Approach for AMMI Models.

    Science.gov (United States)

    da Silva, Carlos Pereira; de Oliveira, Luciano Antonio; Nuvunga, Joel Jorge; Pamplona, Andrezza Kéllen Alves; Balestre, Marcio

    2015-01-01

    Linear-bilinear models, especially the additive main effects and multiplicative interaction (AMMI) model, are widely applicable to genotype-by-environment interaction (GEI) studies in plant breeding programs. These models allow a parsimonious modeling of GE interactions, retaining a small number of principal components in the analysis. However, one aspect of the AMMI model that is still debated is the selection criteria for determining the number of multiplicative terms required to describe the GE interaction pattern. Shrinkage estimators have been proposed as selection criteria for the GE interaction components. In this study, a Bayesian approach was combined with the AMMI model with shrinkage estimators for the principal components. A total of 55 maize genotypes were evaluated in nine different environments using a complete blocks design with three replicates. The results show that the traditional Bayesian AMMI model produces low shrinkage of singular values but avoids the usual pitfalls in determining the credible intervals in the biplot. On the other hand, Bayesian shrinkage AMMI models have difficulty with the credible interval for model parameters, but produce stronger shrinkage of the principal components, converging to GE matrices that have more shrinkage than those obtained using mixed models. This characteristic allowed more parsimonious models to be chosen, and resulted in models being selected that were similar to those obtained by the Cornelius F-test (α = 0.05) in traditional AMMI models and cross validation based on leave-one-out. This characteristic allowed more parsimonious models to be chosen and more GEI pattern retained on the first two components. The resulting model chosen by posterior distribution of singular value was also similar to those produced by the cross-validation approach in traditional AMMI models. Our method enables the estimation of credible interval for AMMI biplot plus the choice of AMMI model based on direct posterior

  9. A Bayesian Shrinkage Approach for AMMI Models.

    Directory of Open Access Journals (Sweden)

    Carlos Pereira da Silva

    Full Text Available Linear-bilinear models, especially the additive main effects and multiplicative interaction (AMMI model, are widely applicable to genotype-by-environment interaction (GEI studies in plant breeding programs. These models allow a parsimonious modeling of GE interactions, retaining a small number of principal components in the analysis. However, one aspect of the AMMI model that is still debated is the selection criteria for determining the number of multiplicative terms required to describe the GE interaction pattern. Shrinkage estimators have been proposed as selection criteria for the GE interaction components. In this study, a Bayesian approach was combined with the AMMI model with shrinkage estimators for the principal components. A total of 55 maize genotypes were evaluated in nine different environments using a complete blocks design with three replicates. The results show that the traditional Bayesian AMMI model produces low shrinkage of singular values but avoids the usual pitfalls in determining the credible intervals in the biplot. On the other hand, Bayesian shrinkage AMMI models have difficulty with the credible interval for model parameters, but produce stronger shrinkage of the principal components, converging to GE matrices that have more shrinkage than those obtained using mixed models. This characteristic allowed more parsimonious models to be chosen, and resulted in models being selected that were similar to those obtained by the Cornelius F-test (α = 0.05 in traditional AMMI models and cross validation based on leave-one-out. This characteristic allowed more parsimonious models to be chosen and more GEI pattern retained on the first two components. The resulting model chosen by posterior distribution of singular value was also similar to those produced by the cross-validation approach in traditional AMMI models. Our method enables the estimation of credible interval for AMMI biplot plus the choice of AMMI model based on direct

  10. Polymerization shrinkage, flexural and compression properties of low-shrinkage dental resin composites.

    Science.gov (United States)

    Park, Jeong-Kil; Lee, Geun-Ho; Kim, Jong-Hwa; Park, Mi-Gyoung; Ko, Ching-Chang; Kim, Hyung-Il; Kwon, Yong Hoon

    2014-01-01

    This study evaluated the polymerization shrinkage, flexural and compressive properties of low-shrinkage resin composites. For the study, four methacrylate-based and one silorane-based resin composites were light cured using three different light-curing units (LCUs) and their polymerization shrinkage, flexural (strength (FS) and modulus (FM)) and compressive (strength (CS) and modulus (CM)) properties were evaluated. Data were statistically analyzed using ANOVA and a post-hoc Tukey test. The polymerization shrinkage ranged approximately 7.6-14.2 μm for 2-mm thick specimens depending on the resin product and LCU. Filtek LS showed the least shrinkage while the rest shrank approximately 13.2-14.2 μm. However, Filtek LS showed the greatest shrinkage difference for the used LCUs. FS and CS of the tested specimens ranged 96.2-152.1 MPa and 239.2-288.4 MPa, respectively, depending on the resin product and LCU. The highest and lowest FS and FM were recorded for the methacrylate-based resin composites. Among the specimens, Filtek LS showed the lowest CS and CM.

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

    DEFF Research Database (Denmark)

    Li, Lili; Thøfner, Ida; Christensen, Jens Peter

    2017-01-01

    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...... infection, significant protection of an autogenous E. coli vaccine against neither a homologous nor a heterologous E. coli challenge could not be documented....

  12. Experimental study on the shrinkage properties and cracking potential of high strength concrete containing industrial by-products for nuclear power plant concrete

    Energy Technology Data Exchange (ETDEWEB)

    KIm, Baek Joong; Yi, Chong Ku [School of Civil, Environmental and Architectural Engineering, Korea University, Seoul (Korea, Republic of)

    2017-02-15

    In Korea, attempts have been made to develop high strength concrete for the safety and design life improvement of nuclear power plants. In this study, the cracking potentials of nuclear power plant-high strength concretes (NPP-HSCs) containing industrial by-products with W/B 0.34 and W/B 0.28, which are being reviewed for their application in the construction of containment structures, were evaluated through autogenous shrinkage, unrestrained drying shrinkage, and restrained drying shrinkage experiments. The cracking potentials of the NPP-HSCs with W/B 0.34 and W/B 0.28 were in the order of 0.34FA25 > 0.34FA25BFS25 > 0.34BFS50 > 0.34BFS65SF5 and 0.28FA25SF5 >> 0.28BFS65SF5 > 0.28BFS45SF5 > 0.28 FA20BFS25SF5, respectively. The cracking potentials of the seven mix proportions excluding 0.28FA25SF5 were lower than that of the existing nuclear power plant concrete; thus, the durability of a nuclear power plant against shrinkage cracking could be improved by applying the seven mix proportions with low cracking potentials.

  13. Discrete multiscale wavelet shrinkage and integrodifferential equations

    Science.gov (United States)

    Didas, S.; Steidl, G.; Weickert, J.

    2008-04-01

    We investigate the relation between discrete wavelet shrinkage and integrodifferential equations in the context of simplification and denoising of one-dimensional signals. In the continuous setting, strong connections between these two approaches were discovered in 6 (see references). The key observation is that the wavelet transform can be understood as derivative operator after the convolution with a smoothing kernel. In this paper, we extend these ideas to the practically relevant discrete setting with both orthogonal and biorthogonal wavelets. In the discrete case, the behaviour of the smoothing kernels for different scales requires additional investigation. The results of discrete multiscale wavelet shrinkage and related discrete versions of integrodifferential equations are compared with respect to their denoising quality by numerical experiments.

  14. Basin Depth Control on the Autogenic Timescale of Fluviodeltaic Systems

    Science.gov (United States)

    Carlson, B.; Kim, W.; Piliouras, A.

    2013-12-01

    ABSTRACT Autogenic processes are inherent processes in sediment transport that influence landscape building and leave distinct signatures in the sedimentary record. It is of great interest to understand autogenic processes in order to decouple internal processes from external controls, such as tectonics or climate change. Here we present results from a series of delta-building experiments to determine the variability of the fluviodeltaic autogenic timescale in response to varying basin water depth. This internal timescale was measured as the time that is required for the delta topset to be reworked through a full cycle of storage and release of sediment. The topset aggrades by fluvial sedimentation until it reaches a maximum slope, at which point a large amount of sediment starts to release, typically resulting in strong channelization. This is followed by a period of avulsions, lateral migration, and backfilling of channels on the topset. These storage and release events are repeated. We used time-lapse images to track shoreline positions and observe changes in progradation rate. The changes in topset topography were also used to determine storage and release duration. The experimental results indicate that the autogenic timescales generally increase with increasing basin water depth. These observations may be explained by the amount of time required to build a lobe with an area large enough to trigger a switch from a lobe-building release event to a backfilling storage event. Individual lobes show a similar surface area regardless of basin depth in the experiments. Deeper basin depth simply requires a larger volume to be filled within this area, thus more time to complete one autogenic process. However, when channel depth is significantly smaller than basin depth, e.g., in very deep basins, stochastic variability in sediment transport and channel lateral mobility outweighs the autogenic cyclicity. This study suggests that internal dynamics and its stratigraphic

  15. Pregnancy, maternal tobacco smoking and early age leukemia in Brazil

    Directory of Open Access Journals (Sweden)

    Sergio eKoifman

    2012-11-01

    Full Text Available Background: Cigarette smoking has been associated with acute myeloid leukemia but hypothesis on the association between maternal smoking during pregnancy and childhood leukemia is unclear. Objectives: To investigate the association between maternal exposure to tobacco smoking during pregnancy and early age (< 2 yr. leukemia (EAL. Methods: A hospital-based multicenter case-control study aiming to explore EAL risk factors was carried out in Brazil during 1999-2007. Data were collected by direct interview with the biological mothers using a standardized questionnaire. The present study included 675 children, being 193 acute lymphoblastic leukemia (ALL, 59 acute myeloid leukemia (AML, and 423 controls, being the latter age frequency matched and paired by area of residence with the cases. Unconditional logistic regression was performed, and odds ratios (OR on the association between tobacco smoking (3 months before pregnancy, during pregnancy, and 3 months after delivery and EAL were ascertained after adjustment for selected variables (maternal age at birth and education, birth weight, infant skin color, and oral contraceptives use during pregnancy.Results: Smoking was reported by 17.5% of case mothers and 20.6% of controls´. Among women who reported to have smoked 20 or more cigarettes during the index pregnancy, an adjusted OR = 5.28 (95% C.I. 1.40-19.95 for ALL was observed. Heavy smoking during breastfeeding yielded an adjusted risk estimate for ALL, OR = 7.78 (95% C.I. 1.33-45.5. No dose-response effect was observed according to smoking exposure during pregnancy and EAL. An association between secondhand smoking during pregnancy or breastfeeding was not observed. Conclusion: An association between maternal smoking and AAL in the offspring was restricted to women who have reported an intense exposure to tobacco smoke during pregnancy and breastfeeding.

  16. Regularized brain reading with shrinkage and smoothing

    OpenAIRE

    Wehbe, Leila; Ramdas, Aaditya; Steorts, Rebecca C.; Shalizi, Cosma Rohilla

    2014-01-01

    Functional neuroimaging measures how the brain responds to complex stimuli. However, sample sizes are modest, noise is substantial, and stimuli are high dimensional. Hence, direct estimates are inherently imprecise and call for regularization. We compare a suite of approaches which regularize via shrinkage: ridge regression, the elastic net (a generalization of ridge regression and the lasso), and a hierarchical Bayesian model based on small area estimation (SAE). We contrast regularization w...

  17. Shrinkage measurement for holographic recording materials

    Science.gov (United States)

    Fernández, R.; Gallego, S.; Márquez, A.; Francés, J.; Navarro Fuster, V.; Neipp, C.; Ortuño, M.; Beléndez, A.; Pascual, I.

    2017-05-01

    There is an increasing demand for new holographic recording materials. One of them are photopolymers, which are becoming a classic media in this field. Their versatility is well known and new possibilities are being created by including new components, such as nanoparticles or dispersed liquid crystal molecules in classical formulations, making them interesting for additional applications in which the thin film preparation and the structural modification have a fundamental importance. Prior to obtaining a wide commercialization of displays based on photopolymers, one of the key aspects is to achieve a complete characterization of them. In this sense, one of the main parameters to estimate and control is the shrinkage of these materials. The volume variations change the angular response of the hologram in two aspects, the angular selectivity and the maximum diffraction efficiency. One criteria for the recording material to be used in a holographic data storage application is the shrinkage, maximum of 0.5%. Along this work, we compare two different methods to measure the holographic recording material shrinkage. The first one is measuring the angle of propagation for both diffracted orders +/-1 when slanted gratings are recorded, so that an accurate value of the grating vector can be calculated. The second one is based on interference measurements at zero spatial frequency limit. We calculate the shrinkage for three different photopolymers: a polyvinyl alcohol acrylamide (PVA/AA) based photopolymer, one of the greenest photopolymers whose patent belongs to the Alicante University called Biophotopol and on the last place a holographic-dispersed liquid crystal photopolymer (H-PDLC).

  18. Measuring techniques for autogenous strain of cement paste

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede

    2006-01-01

    Volumetric measurement of autogenous strain is frequently performed by placing the fresh cement paste in a rubber membrane submerged in water. The volume change of the cement paste is measured by the amount of water displaced by the submerged sample. Volumetric and linear measurements of autogenous...... of the volumetric method. Water absorption is driven by a lowering of the water activity in the cement paste due to dissolved salts in the pore fluid and to self-desiccation. From the moment of casting, significant water uptake was registered in all experiments. This water uptake influenced the volumetric...... on the same cement pastes....

  19. Measuring techniques for autogenous strain of cement paste

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede

    2007-01-01

    Volumetric measurement of autogenous strain is frequently performed by placing the fresh cement paste in a rubber membrane submerged in water. The volume change of the cement paste is measured by the amount of water displaced by the submerged sample. Volumetric and linear measurements of autogenous...... of the volumetric method. Water absorption is driven by a lowering of the water activity in the cement paste due to dissolved salts in the pore fluid and to self-desiccation. From the moment of casting, significant water uptake was registered in all experiments. This water uptake influenced the volumetric...... on the same cement pastes....

  20. Nearest shrunken centroids via alternative genewise shrinkages

    Science.gov (United States)

    Choi, Byeong Yeob; Bair, Eric; Lee, Jae Won

    2017-01-01

    Nearest shrunken centroids (NSC) is a popular classification method for microarray data. NSC calculates centroids for each class and “shrinks” the centroids toward 0 using soft thresholding. Future observations are then assigned to the class with the minimum distance between the observation and the (shrunken) centroid. Under certain conditions the soft shrinkage used by NSC is equivalent to a LASSO penalty. However, this penalty can produce biased estimates when the true coefficients are large. In addition, NSC ignores the fact that multiple measures of the same gene are likely to be related to one another. We consider several alternative genewise shrinkage methods to address the aforementioned shortcomings of NSC. Three alternative penalties were considered: the smoothly clipped absolute deviation (SCAD), the adaptive LASSO (ADA), and the minimax concave penalty (MCP). We also showed that NSC can be performed in a genewise manner. Classification methods were derived for each alternative shrinkage method or alternative genewise penalty, and the performance of each new classification method was compared with that of conventional NSC on several simulated and real microarray data sets. Moreover, we applied the geometric mean approach for the alternative penalty functions. In general the alternative (genewise) penalties required fewer genes than NSC. The geometric mean of the class-specific prediction accuracies was improved, as well as the overall predictive accuracy in some cases. These results indicate that these alternative penalties should be considered when using NSC. PMID:28199352

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

    Science.gov (United States)

    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.

  2. Polymerization shrinkage assessment of dental resin composites: a literature review.

    Science.gov (United States)

    Kaisarly, Dalia; Gezawi, Moataz El

    2016-09-01

    Composite restorations are widely used worldwide, but the polymerization shrinkage is their main disadvantage that may lead to clinical failures and adverse consequences. This review reports, currently available in vitro techniques and methods used for assessing the polymerization shrinkage. The focus lies on recent methods employing three-dimensional micro-CT data for the evaluation of polymerization shrinkage: volumetric measurement and the shrinkage vector evaluation through tracing particles before and after polymerization. Original research articles reporting in vitro shrinkage measurements and shrinkage stresses were included in electronic and hand-search. Earlier methods are easier, faster and less expensive. The procedures of scanning the samples in the micro-CT and performing the shrinkage vector evaluation are time consuming and complicated. Moreover, the respective software is not commercially available and the various methods for shrinkage vector evaluation are based on different mathematical principles. Nevertheless, these methods provide clinically relevant information and give insight into the internal shrinkage behavior of composite applied in cavities and how boundary conditions affect the shrinkage vectors. The traditional methods give comparative information on polymerization shrinkage of resin composites, whereas using three-dimensional micro-CT data for volumetric shrinkage measurement and the shrinkage vector evaluation is a highly accurate method. The methods employing micro-CT data give the researchers knowledge related to the application method and the boundary conditions of restorations for visualizing the shrinkage effects that could not be seen otherwise. Consequently, this knowledge can be transferred to the clinical situation to optimize the material manipulation and application techniques for improved outcomes.

  3. Autogenic training: a narrative and quantitative review of clinical outcome.

    Science.gov (United States)

    Linden, W

    1994-09-01

    This review of controlled outcome research on Autogenic Training complements the literature by pooling narrative and quantitative approaches, by including only studies with experimental controls, by integrating the English and German literature, and by adding research findings published since the last review. Whereas previous reviews have already reported positive effects of Autogenic Training for migraine, insomnia, and test anxiety, additional supportive findings for angina pectoris, asthma, childbirth, eczema, hypertension, infertility, Raynaud's disease, and recovery from myocardial infarction are discussed here. The impact of protocol variations on outcome is described, and the specificity of Autogenic Training relative to other stress management techniques is highlighted. Quantitative findings suggested that Autogenic Training was associated with medium-sized pre- to posttreatment effects ranging from d = .43 for biological indices of change to d = .58 for psychological and behavioral indices thus matching effect sizes for other biobehavioral treatment techniques like biofeedback and muscular relaxation. Length of treatment did not affect clinical outcome. The discussion emphasizes how narrative and quantitative strategies complement one another.

  4. Treatment of Childhood Migraine Using Autogenic Feedback Training.

    Science.gov (United States)

    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)

  5. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Science.gov (United States)

    2010-07-01

    ...-constantan or chromelalumel—and a potentiometer shall be used for all temperature measurements. (3) Syringe...) Temperature control. Each autotransformer shall be so adjusted that the temperature at the neck, mid-section... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Autogenous-ignition temperature test....

  6. Autogenous tooth transplantation: an alternative to replace extracted tooth

    Directory of Open Access Journals (Sweden)

    David B. Kamadjaja

    2015-09-01

    Full Text Available Background: The gold standard treatment to replace missing tooth is dental implants, however, in certain cases, such as in young patients its placement is contraindicated. Autogenous tooth transplantation, which has been widely done in Scandinavian countries for many years, may become a good alternative to overcome this problem. Purpose: This article attempted to provide information about the indication, treatment planning, surgical technique and the successful result of autogenous tooth transplantation. Case: A fifteen year old male patient presented with large caries and periapical disease of his lower left first molar, which was partially erupted and the roots was not fully formed in radiograph. Case management: Autogenous tooth transplantation procedure was performed consisting of extraction of #36, odontectomy of #38 followed by its implantation to socket #36 and fixation of the transplanted tooth to the adjacent teeth. Post operative evaluation was done on regular basis within 18 months period. There was no complaint, the tooth was clinically stable and no evidence of periodontal problem. Serial radiographs showed healing of alveolar bone and periodontal tissue, and the complete root formation was evident by 18 months post operatively. Conclusion: Autogenous tooth transplantation is a potential alternative to replace extracted tooth. Provided that the case be properly planned and operation carefully performed, successful result of this treatment can be achieved.

  7. Autogeneous healing and chloride ingress in cracked concrete

    NARCIS (Netherlands)

    Savija, B.; Schlangen, E.

    2016-01-01

    An experimental study of the influence of autogeneous healing on chloride ingress in cracked concrete is presented. In the study, two concrete mixtures (a Portland cement mix and a blast furnace slag mix), two healing regimes (submerged and fog room regime), two cracking ages (14 and 28 days), and m

  8. Autogeneous healing and chloride ingress in cracked concrete

    NARCIS (Netherlands)

    Savija, B.; Schlangen, E.

    2016-01-01

    An experimental study of the influence of autogeneous healing on chloride ingress in cracked concrete is presented. In the study, two concrete mixtures (a Portland cement mix and a blast furnace slag mix), two healing regimes (submerged and fog room regime), two cracking ages (14 and 28 days), and m

  9. Do low-shrink composites reduce polymerization shrinkage effects?

    Science.gov (United States)

    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.

  10. Recycling of rubble from building demolition for low-shrinkage concretes.

    Science.gov (United States)

    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.

  11. Reducing Shrinkage in Canned and Frozen Mushrooms

    OpenAIRE

    Gormley, T. R. (Thomas Ronan); Walshe, P.E.

    1982-01-01

    The process involving a preliminary soaking of the mushrooms in water for 20 min followed by a chill storage period followed by a further water soak for 2 hr, and known as the 3S process, gave a considerable reduction in total shrinkage in both brown and white strain canned mushrooms compared with the control samples. Water uptake by the mushrooms in the 3S process was greatest when the soaking water temperature was between 20 and 30°C and had a pH of 8. Citric acid in the blanch water enhanc...

  12. Mechanical Self-shrinkage of Artillery Barrels

    Directory of Open Access Journals (Sweden)

    Ioan Ciorba

    2012-09-01

    Full Text Available Objective of this paper is to define what self-shrink artillery barrel is. She is considered to be a compound barrel like as a thick-walled tube (k>2, in his wall being introduced a state of stress and strain using specific technological proceeds. This type of treatment is aimed to increase the artillery barrel load capacity and wear resistance in operation. The experimental part was realized using an industrial plant at Mechanical Factory of Resita. This part presents a comparative study between mechanical self-shrinkage on artillery head barrel, first using a mandrel and seconds a ball.

  13. Huadong sintering model about expansion and shrinkage

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The whole sintering course from the beginning of heating to the end of heat preservation stage was studied by taking into account the influence of pressing. It was found that there exist expanding mechanism and shrinking mechanism in the sintering process, and the expanding mechanism is always acting before the shrinking mechanism. Whether the sintering body shrinks or expands depends on the interaction between the two mechanisms. And according to this, the Huadong sintering model in account of expansion and shrinkage mechanism was given.

  14. Internal water curing with Liapor aggregates

    DEFF Research Database (Denmark)

    Lura, Pietro

    2005-01-01

    Internal water curing is a very efficient way to counteract self-desiccation and autogenous shrinkage in high performance concrete, thereby reducing the likelihood of early-age cracking. This paper deals with early-age volume changes and moisture transport in lightweight aggregate concrete realiz...

  15. Silorane- and high filled-based"low-shrinkage" resin composites: shrinkage, flexural strength and modulus

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Galvão Arrais

    2013-04-01

    Full Text Available This study compared the volumetric shrinkage (VS, flexural strength (FS and flexural modulus (FM properties of the low-shrinkage resin composite Aelite LS (Bisco to those of Filtek LS (3M ESPE and two regular dimethacrylate-based resin composites, the microfilled Heliomolar (Ivoclar Vivadent and the microhybrid Aelite Universal (Bisco. The composites (n = 5 were placed on the Teflon pedestal of a video-imaging device, and VS was recorded every minute for 5 min after 40 s of light exposure. For the FS and FM tests, resin discs (0.6 mm in thickness and 6.0 mm in diameter were obtained (n = 12 and submitted to a piston-ring biaxial test in a universal testing machine. VS, FS, and FM data were submitted to two-way repeated measures and one-way ANOVA, respectively, followed by Tukey's post-hoc test (a = 5%. Filtek LS showed lower VS than did Aelite LS, which in turn showed lower shrinkage than did the other composites. Aelite Universal and Filtek LS exhibited higher FS than did Heliomolar and Aelite LS, both of which exhibited the highest FM. No significant difference in FM was noted between Filtek LS and Aelite Universal, while Heliomolar exhibited the lowest values. Aelite LS was not as effective as Filtek LS regarding shrinkage, although both low-shrinkage composites showed lower VS than did the other composites. Only Filtek LS exhibited FS and FM comparable to those of the regular microhybrid dimethacrylate-based resin composite.

  16. Towards a first classification of aerosol shrinkage events

    Directory of Open Access Journals (Sweden)

    E. Alonso-Blanco

    2015-09-01

    Full Text Available This work presents for the first time a classification of shrinkage events based on the aerosol processes that precede them. To this end, 3.5 years of continuous measurements (from 2009 to 2012 of aerosol size distributions, obtained with a Scanning Mobility Particle Sizer (SMPS at an urban background site in Southern Europe, have been interpreted. 48 shrinkage events were identified and analysed, all occurring during spring and summer when the atmospheric conditions are more favourable for their development. In this study the shrinkage events took place mostly towards the end of the day, and their occurrence could be associated to atmospheric dilution conditions and a reduction in photochemical activity. The shrinkage rate (SR varied between −1.0 and −11.1 nm h−1 (average value of −4.7 ± 2.6 nm h−1. Changes in particle concentrations corresponding to the nucleation and Aitken modes were detected, whereby an increase in the number of particles in the nucleation mode often coincided with a reduction in the Aitken mode. The accumulation mode did not undergo significant changes during these processes. In addition, in some cases, a dilution of the total particle number concentration in the ambient air was observed. Following the proposed methodology, three groups of events have been identified: Group I (NPF + shrinkage, Group II (aerosol growth process + shrinkage and Group III (pure shrinkage events. The largest number of shrinkage events has been observed in the absence of prior processes, i.e. pure shrinkage events, followed by Group I events and finally Group II events. Although this analysis has confirmed that the triggering of shrinkage events is clearly linked to the atmospheric situation and the characteristics of the measurement area, this classification may contribute to a better understanding of the processes involved and the features that characterize shrinkage events.

  17. RILEM technical committee 195-DTD recommendation for test methods for AD and TD of early age concrete Round Robin documentation report : program, test results and statistical evaluation

    CERN Document Server

    Bjøntegaard, Øyvind; Krauss, Matias; Budelmann, Harald

    2015-01-01

    This report presents the Round-Robin (RR) program and test results including a statistical evaluation of the RILEM TC195-DTD committee named “Recommendation for test methods for autogenous deformation (AD) and thermal dilation (TD) of early age concrete”. The task of the committee was to investigate the linear test set-up for AD and TD measurements (Dilation Rigs) in the period from setting to the end of the hardening phase some weeks after. These are the stress-inducing deformations in a hardening concrete structure subjected to restraint conditions. The main task was to carry out an RR program on testing of AD of one concrete at 20 °C isothermal conditions in Dilation Rigs. The concrete part materials were distributed to 10 laboratories (Canada, Denmark, France, Germany, Japan, The Netherlands, Norway, Sweden and USA), and in total 30 tests on AD were carried out. Some supporting tests were also performed, as well as a smaller RR on cement paste. The committee has worked out a test procedure recommenda...

  18. Autogenous bone grafts in periodontal practice: A literature review

    Directory of Open Access Journals (Sweden)

    Nymphea Pandit

    2016-01-01

    Full Text Available To improve the long-term prognosis of teeth, the treatment of periodontal diseases has evolved from resection to regeneration. Regeneration of the supporting structures of the teeth involves the use of a variety of materials of natural and synthetic origins. The ultimate aim of a true connective tissue attachment to the cementum, however, is difficult to achieve and a few of the materials have shown promising results. Autogenous bone graft obtained from the same individual has always been considered the gold standard because of its high osteogenic potential and virtually nil side effects. The present paper describes the use of autogenous grafts in the periodontal practice. The compilation of the data was done by PubMed search since the first use of the graft in periodontics.

  19. Autogenous bone grafts in periodontal practice: A literature review

    OpenAIRE

    Nymphea Pandit; Inder Kumar Pandit

    2016-01-01

    To improve the long-term prognosis of teeth, the treatment of periodontal diseases has evolved from resection to regeneration. Regeneration of the supporting structures of the teeth involves the use of a variety of materials of natural and synthetic origins. The ultimate aim of a true connective tissue attachment to the cementum, however, is difficult to achieve and a few of the materials have shown promising results. Autogenous bone graft obtained from the same individual has always been con...

  20. Guided bone regeneration with autogenous graft of Chin

    OpenAIRE

    Ramos Perfecto, Donald; Estudiantes de la Segunda Especialidad en Periodoncia. Facultad Odontología UNMSM. Lima - Perú.; García Olivera, John; Estudiantes de la Segunda Especialidad en Periodoncia. Facultad Odontología UNMSM. Lima - Perú.; Sueldo Gálvez, Luis; Estudiantes de la Segunda Especialidad en Periodoncia. Facultad Odontología UNMSM. Lima - Perú.

    2014-01-01

    The deficiencies of bone quality in the patient, either of wide or height, make the clinician take decisions to improve these conditions, with the purpose of placing implants or improving faulty edges that can support a prosthetics frame. For this, the procedures of guided bone regeneration with ones own chin bone (autogenous implant), are the ones with the best forecast for resolving the problem. In this clinical case we show the diagnosis, the surgical technique, the advantages and pharmaco...

  1. Autogenous tooth transplantation for replacing a lost tooth: case reports

    OpenAIRE

    Kang, Ji-Youn; Chang, Hoon-Sang; Hwang,Yun-Chan; Hwang, In-Nam; Oh, Won-Mann; LEE, Bin-Na

    2013-01-01

    The autogenous tooth transplantation is an alternative treatment replacing a missing tooth when a suitable donor tooth is available. It is also a successful treatment option to save significant amount of time and cost comparing implants or conventional prosthetics. These cases, which required single tooth extraction due to deep caries and severe periodontal disease, could have good results by transplanting non-functional but sound donor tooth to the extraction site.

  2. Hydration of Portoguese cements, measurement and modelling of chemical shrinkage

    DEFF Research Database (Denmark)

    Maia, Lino; Geiker, Mette Rica; Figueiras, Joaquim A.

    2008-01-01

    Development of cement hydration was studied by measuring the chemical shrinkage of pastes. Five types of Portuguese Portland cement were used in cement pastes with . Chemical shrinkage was measured by gravimetry and dilatometry. In gravimeters results were recorded automatically during at least...

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

    Energy Technology Data Exchange (ETDEWEB)

    Wyrzykowski, Mateusz, E-mail: mateusz.wyrzykowski@empa.ch [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Lodz University of Technology, Department of Building Physics and Building Materials, Lodz (Poland); Trtik, Pavel [Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, Villigen (Switzerland); Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Münch, Beat [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Weiss, Jason [Purdue University, School of Civil Engineering, West Lafayette (United States); Vontobel, Peter [Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, Villigen (Switzerland); Lura, Pietro [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); ETH Zurich, Institute for Building Materials (IfB), Zurich (Switzerland)

    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. 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.

  4. Simulation of shrinkage cavity formation during solidification of binary alloy

    Directory of Open Access Journals (Sweden)

    T. Skrzypczak

    2010-01-01

    Full Text Available Presented paper is focused on numerical modeling of binary alloy solidification process with connection to shrinkage cavity formation phenomenon. Appropriate matching of cooling parameters during solidification process of the cast with raiser is essential to obtain suitable properties of the manufactured part. Localization, structure and depth of the shrinkage cavity is connected to these parameters. The raiser is removed after process, so defect localization in the top part of the manufactured element is of great importance. Mathematical model of solidification process is presented in the paper. The main focus is put on the algorithm of shrinkage cavity creation process. On the basis of mathematical model the numerical approach using finite element method is proposed. On the base of mathematical and numerical model computer program is made. It is able to perform simulation of the shrinkage cavity formation in 2D region. Shape and localization of shrinkage cavity obtained from simulation is compared to defect which was created during experiment.

  5. Distributed fiber optic sensor-enhanced detection and prediction of shrinkage-induced delamination of ultra-high-performance concrete overlay

    Science.gov (United States)

    Bao, Yi; Valipour, Mahdi; Meng, Weina; Khayat, Kamal H.; Chen, Genda

    2017-08-01

    This study develops a delamination detection system for smart ultra-high-performance concrete (UHPC) overlays using a fully distributed fiber optic sensor. Three 450 mm (length) × 200 mm (width) × 25 mm (thickness) UHPC overlays were cast over an existing 200 mm thick concrete substrate. The initiation and propagation of delamination due to early-age shrinkage of the UHPC overlay were detected as sudden increases and their extension in spatial distribution of shrinkage-induced strains measured from the sensor based on pulse pre-pump Brillouin optical time domain analysis. The distributed sensor is demonstrated effective in detecting delamination openings from microns to hundreds of microns. A three-dimensional finite element model with experimental material properties is proposed to understand the complete delamination process measured from the distributed sensor. The model is validated using the distributed sensor data. The finite element model with cohesive elements for the overlay-substrate interface can predict the complete delamination process.

  6. Fiber Bragg grating sensors as a tool to evaluate the influence of filler on shrinkage of geopolymer matrices

    Science.gov (United States)

    Campopiano, Stefania; Iadicicco, Agostino; Messina, Francesco; Ferone, Claudio; Cioffi, Raffaele

    2015-05-01

    Geopolymer matrices represent one of the main sustainable alternatives to ordinary Portland cement (OPC) and other clinker-based blended cements. Real scale applications are limited and a relevant amount of data is still needed to assess the early age and long-term behavior of these systems. Particularly, the early-age monitoring of geopolymers represent a key parameter for mix design optimization. Most of the available methods for the measurement of temperature evolution due to polycondensation kinetics and early age deformations are related to laboratory activities. The upscaling to in situ techniques represents a crucial step toward technological assessment. To this aim, authors propose to use Fiber Bragg Gratings (FBGs) embedded in the geopolymer matrices. Starting from a case study by authors related to the design of externally bonded fiber reinforced geopolymers for strengthening of existing structures, the matrix was optimized in terms of quartz filler content. The measurements carried out by means of FBG sensors allowed to reduce filler content respect to the abovementioned work. Particularly, quartz content can be reduced by 50%. The temperature associated to polycondensation was slightly below 65°C for the three studied systems, limiting the use of designed metakaolin geopolymer to non-massive structures, since thermal cracking could occur, unless further research will be able to assess the viability of retardants. The experimental results confirm that FBG represent an accurate method for simultaneous shrinkage and temperature measurements for geopolymers and the application in real scale structures for remote sensing could help to create database on inner temperatures and early age deformations.

  7. Effective Expansion: Balance between Shrinkage and Hygroscopic Expansion.

    Science.gov (United States)

    Suiter, E A; Watson, L E; Tantbirojn, D; Lou, J S B; Versluis, A

    2016-05-01

    The purpose of this study was to investigate the relationship between hygroscopic expansion and polymerization shrinkage for compensation of polymerization shrinkage stresses in a restored tooth. One resin-modified glass-ionomer (RMGI) (Ketac Nano, 3M ESPE), 2 compomers (Dyract, Dentsply; Compoglass, Ivoclar), and a universal resin-based composite (Esthet•X HD, Dentsply) were tested. Volumetric change after polymerization ("total shrinkage") and during 4 wk of water storage at 37°C was measured using an optical method (n= 10). Post-gel shrinkage was measured during polymerization using a strain gauge method (n= 10). Extracted human molars with large mesio-occluso-distal slot preparations were restored with the tested restorative materials. Tooth surfaces at baseline (preparation), after restoration, and during 4 wk of 37°C water storage were scanned with an optical scanner to determine cuspal flexure (n= 8). Occlusal interface integrity was measured using dye penetration. Data were analyzed using analysis of variance and post hoc tests (significance level 0.05). All tested materials shrunk after polymerization. RMGI had the highest total shrinkage (4.65%) but lowest post-gel shrinkage (0.35%). Shrinkage values dropped significantly during storage in water but had not completely compensated polymerization shrinkage after 4 wk. All restored teeth initially exhibited inward (negative) cuspal flexure due to polymerization shrinkage. Cuspal flexure with the RMGI restoration was significantly less (-6.4 µm) than with the other materials (-12.1 to -14.1 µm). After 1 d, cuspal flexure reversed to +5.0 µm cuspal expansion with the RMGI and increased to +9.3 µm at 4 wk. After 4 wk, hygroscopic expansion compensated cuspal flexure in a compomer (Compoglass) and reduced flexure with Dyract and resin-based composite. Marginal integrity (93.7% intact restoration wall) was best for the Compoglass restorations and lowest (73.1%) for the RMGI restorations. Hygroscopic

  8. Anisotropic shrinkage characteristics of tape cast alumina

    Science.gov (United States)

    Patwardhan, Jaideep Suresh

    Dimensional control during sintering is a major issue in ceramics processing to avoid high post-sintering costs associated with machining of the fired ceramic part to desired tolerances and dimensions. Ceramic forming processes such as tape casting, injection molding, and extrusion involve shear of anisotropic particles resulting in preferential alignment of the particles in the green body. This preferential alignment causes directionality in mechanical, electrical, optical, and magnetic properties and most importantly warpage or distortion during sintering. A large effort has been devoted to synthesizing ceramic green bodies with minimal density gradients and uniform packing and modeling the sintering behavior evolution but little effort has been devoted to characterizing orientation of particles and the effect of preferential alignment on sintering shrinkage anisotropy. A systematic study was initiated to study the effect of processing variables such as shear rate, solids loading, temperature, and binder content on aqueous tape cast alumina. Three different alumina systems: A16-SG, Baikowski RC-UFX DBM and RC-LS DBM were investigated. Aqueous tapes of high solids loading alumina (56 vol. %) were tape cast at various speeds and thicknesses and assuming plane Couette flow a shear rate regime of 21--270 s-1 was investigated. Higher shear rates and high solids loading resulted in higher in-plane anisotropy whereas the anisotropy in the thickness direction was higher for low solids loading systems. The anisotropy was found to be fairly constant above a certain critical shear rate (˜100 s-1) irrespective of the temperature and the solids loading and this correlated with the viscosity-shear rate relationship of the cast slips. The higher shrinkage anisotropy in the thickness direction for the low solids loading systems (35 and 45 vol. %) was attributed to the higher amount of organics in the slip required to sustain the suitable viscosity for tape casting and

  9. Cure shrinkage in epoxy grouts for grouted repairs

    Science.gov (United States)

    Shamsuddoha, Md.; Islam, Md. Mainul; Aravinthan, Thiru; Manalo, Allan; Lau, Kin-tak

    2013-08-01

    Structures can go through harsh environmental adversity and can experience material loss and cracks during their service lives. Infill material is used to ensure a supporting bed for a grouted repair. Epoxy grouts are used for repairing and rehabilitating structures, such as foundations, bridges, piers, transportation pipelines, etc., because they are resistant to typical chemicals and possess superior mechanical properties than other grouts. The resin based infill used inside the void or cracked space of the repair is vulnerable to shrinkage. When these filled grouts have high resin content, cracks can develop from residual stresses, which can affect the load transfer performance. It follows that interlayer separation and cracking of infill layer can occur in a grouted repair. In this study, volumetric shrinkage of two epoxy grouts was measured over 28 days using a Pycnometer. The highest volumetric shrinkage measured after 7 days was found to be 2.72%. The results suggest that the volumetric shrinkage can be reduced to 1.1% after 7 days, through the introduction of a coarse aggregate filler; a 2.5 times reduction in shrinkage. About 98% and 92% of the total shrinkage over the 28 day period, of the unfilled and filled grouts respectively, was found to occur within 7 days of mixing. The gel-time shrinkages were also calculated, to determine the "postgel" part of the curing contraction which subsequently produces residual stresses in the hardened grout systems.

  10. Alternative methods for determining shrinkage in restorative resin composites.

    Science.gov (United States)

    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.

  11. Parametric Assessment of Stress Development and Cracking in Internally Cured Restrained Mortars Experiencing Autogenous Deformations and Thermal Loading

    Directory of Open Access Journals (Sweden)

    Kambiz Raoufi

    2011-01-01

    Full Text Available A finite element model is used to examine how the properties of cementitious mortar are related to the stress development in the dual ring test. The results of this investigation are used to explain the thermal cracking behavior of mixtures containing prewetted lightweight aggregates (LWA by quantifying the contribution of several material properties individually. In addition to the beneficial effects of using the LWA as an internal curing agent to reduce the autogenous shrinkage of concrete, the LWA also helps to reduce the potential for thermal cracking due to a lower elastic modulus and increased stress relaxation. The rate of stress development, age of cracking, and magnitude of the temperature drop necessary to induce cracking in a dual ring specimen are dependent on a variety of factors, including the coefficient of thermal expansion of both the cementitious mortar and the restraining rings, elastic modulus of the mortar, creep effect of the mortar, and rate of thermal loading. Depending on the rate of cooling, cracking may or may not occur. The slowest rate of cooling (2.5∘C/h minimizes the effects of creep while cooling rates faster than 8∘C/h can produce a thermal gradient through the mortar cross-section that needs to be considered.

  12. Comparative Analysis of Measured and Predicted Shrinkage Strain in Concrete

    Directory of Open Access Journals (Sweden)

    Kossakowski P. G.

    2014-06-01

    Full Text Available The article discusses the issues related to concrete shrinkage. The basic information on the phenomenon is presented as well as the factors that determine the contraction are pointed out and the stages of the process are described. The guidance for estimating the shrinkage strain is given according to Eurocode standard PN-EN 1992-1-1:2008. The results of studies of the samples shrinkage strain of concrete C25/30 are presented with a comparative analysis of the results estimated by the guidelines of the standard according to PN-EN 1992-1- 1:2008

  13. Shrinkage covariance matrix approach for microarray data

    Science.gov (United States)

    Karjanto, Suryaefiza; Aripin, Rasimah

    2013-04-01

    Microarray technology was developed for the purpose of monitoring the expression levels of thousands of genes. A microarray data set typically consists of tens of thousands of genes (variables) from just dozens of samples due to various constraints including the high cost of producing microarray chips. As a result, the widely used standard covariance estimator is not appropriate for this purpose. One such technique is the Hotelling's T2 statistic which is a multivariate test statistic for comparing means between two groups. It requires that the number of observations (n) exceeds the number of genes (p) in the set but in microarray studies it is common that n Hotelling's T2 statistic with the shrinkage approach is proposed to estimate the covariance matrix for testing differential gene expression. The performance of this approach is then compared with other commonly used multivariate tests using a widely analysed diabetes data set as illustrations. The results across the methods are consistent, implying that this approach provides an alternative to existing techniques.

  14. Influence of temperature on autogenous deformation and relative humidity change in hardening cement paste

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

    1999-01-01

    This paper deals with autogenous deformation and autogenous relative humidity change (RH change) in hardening cement paste. Theoretical considerations and experimental data are presented, which elucidate the influence of temperature on these properties. This is an important subject in the control...

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

    Science.gov (United States)

    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.

  16. Autogenic therapy: Techniques, foundations, health and clinical applications, and empirical support

    Directory of Open Access Journals (Sweden)

    Manuel R. Abuín

    2016-12-01

    Full Text Available Autogenic therapy emerges from the "autogenic training" method created by Schultz, and its development incorporates different therapeutic methods based on a psychophysiological approach. All these methods promote homeostatic self-regulatory brain processes. The aims of this paper are to describe and analyse the autogenic methods, the psychophysiological and neurophysiological processes involved, and their effective applications in both health and clinical fields. For these purposes, beside reviewing the earlier work by Schultz and Luthe, an electronic search of literature was conducted in order to find relevant contributions on these topics. Results show a big development of autogenic methods until the 80s, with an enormous amount of applications and studies on the psychophysiological and neurophysiological changes related to the practice of autogenic training. However, their expansion during the last 25 years has been much lower in comparison with other methods such as mindfulness and hypnosis. Possible causes are discussed and new challenges are suggested

  17. Clinical study of graft materials using autogenous teeth in maxillary sinus augmentation.

    Science.gov (United States)

    Jeong, Kyung-In; Kim, Su-Gwan; Kim, Young-Kyun; Oh, Ji-Su; Jeong, Mi-Ae; Park, Jin-Ju

    2011-12-01

    The purpose of this study was to evaluate the effectiveness of autogenous tooth bone graft materials. Hundred implants in 51 patients were selected, and the patients received maxillary sinus augmentation and implant placement using autogenous tooth graft materials at the Chosun University Dental Hospital and Seoul National University Bundang Hospital between July 2009 and November 2010. In cases using autogenous tooth bone graft alone, or together with other graft material, the implant survival rate was 96.15%. On histomorphologic examination, autogenous tooth bone graft materials showed gradual resorption and new bone formation through osteoconduction and osteoinduction. The results indicated that autogenous tooth bone graft materials are appropriate for use in maxillary sinus augmentation.

  18. Autogenic-feedback training: A countermeasure for orthostatic intolerance

    Science.gov (United States)

    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.

  19. Gorham's disease in humerus treated with autogenous vascularized fibular graft

    Science.gov (United States)

    Kim, Jeung Woo; Kang, Hong Je; Kim, Dong Chul; Shin, Chang Hyun

    2017-01-01

    Gorham's disease is a rare disorder of the bone characterized by progressive massive osteolysis. The pathophysiology is unknown, and diagnosis is often difficult. Most cases are often recognized retrospectively. There is no standardized treatment and management for Gorham's disease. We report a case of an 18-year-old male presenting with a pathologic fracture in the humerus shaft diagnosed with Gorham's disease. Patient was treated with autogenous vascularized fibular graft with wide excision and a 10 years followup after first surgery. PMID:28400670

  20. Decalcificated human dentin matrix in autogenous repair of skull defects

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@In the management of traumatic skull defect, the classical treatment has usually been adopted, i.e.,primary debridement and secondary repair of bone defect, especially in cases of open lacerated skull fracture. 1 In general, the use of prosthetic material in repair is often not so satisfactory either in China or abroad. Decalcificated human dentin matrix (DHDM)has been used in autogenous repair of traumatic skull defect in primary operation and a good curative effect has been gained since the time from September 1996 to March 1998. Clinical results and CT scanning observation are reported in the following.

  1. Gorham's disease in humerus treated with autogenous vascularized fibular graft

    Directory of Open Access Journals (Sweden)

    Jeung Woo Kim

    2017-01-01

    Full Text Available Gorham's disease is a rare disorder of the bone characterized by progressive massive osteolysis. The pathophysiology is unknown, and diagnosis is often difficult. Most cases are often recognized retrospectively. There is no standardized treatment and management for Gorham's disease. We report a case of an 18-year-old male presenting with a pathologic fracture in the humerus shaft diagnosed with Gorham's disease. Patient was treated with autogenous vascularized fibular graft with wide excision and a 10 years followup after first surgery.

  2. Autogenous electrolyte, non-pyrolytically produced solid capacitor structure

    Science.gov (United States)

    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.

  3. Creep and Shrinkage of High Strength Concretes: an Experimental Analysis

    Directory of Open Access Journals (Sweden)

    Berenice Martins Toralles carbonari

    2002-01-01

    Full Text Available The creep and shrinkage behaviour of high strength silica fume concretes is significantly different from that of conventional concretes. In order to represent the proper time-dependent response of the material in structural analysis and design, these aspects should be adequately quantified. This paper discusses an experimental setup that is able to determine the creep and shrinkage of concrete from the time of placing. It also compares different gages that can be used for measuring the strains. The method is applied to five different concretes in the laboratory under controlled environmental conditions. The phenomena that are quantified can be classified as basic shrinkage, drying shrinkage, basic creep and drying creep. The relative importance of these mechanisms in high strength concrete will also be presented.

  4. Nanocavity Shrinkage and Preferential Amorphization during Irradiation in Silicon

    Institute of Scientific and Technical Information of China (English)

    ZHU Xian-Fang; WANG Zhan-Guo

    2005-01-01

    @@ We model the recent experimental results and demonstrate that the internal shrinkage of nanocavities in silicon is intrinsically associated with preferential amorphization as induced by self-ion irradiation.

  5. Comparison of shrinkage related properties of various patch repair materials

    Science.gov (United States)

    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.

  6. Influence of gelatinous fibers on the shrinkage of silver maple

    Science.gov (United States)

    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.

  7. Applying strain into graphene by SU-8 resist shrinkage

    Science.gov (United States)

    Takamura, Makoto; Hibino, Hiroki; Yamamoto, Hideki

    2016-07-01

    We investigated the use of the shrinkage of SU-8 resist caused by thermal annealing to apply strain into graphene grown by the chemical-vapor-deposition (CVD) method. We demonstrate that the shrinkage of resist deposited on top of graphene on a substrate induces a local tensile strain within a distance of 1-2 μm from the edge of the resist. The thermal shrinkage of SU-8 will allow us to design the local strain in graphene on substrates. We also show that the shrinkage induces a large tensile strain in graphene suspended between two bars of SU-8. We expect that a much larger strain can be induced by suppressing defects in CVD-grown graphene.

  8. 减缩剂与内养护复合对水泥砂浆性能的影响%Influence of Combination of Shrinkage Reducing Admixture with Internal Curing on Properties of Cement Mortar

    Institute of Scientific and Technical Information of China (English)

    党玉栋; 钱觉时; 郭清春; 王智; 贾兴文

    2013-01-01

    Influence of shrinkage reducing admixture(SRA),internal curing(IC) by using saturated lightweight aggregate,and SRA combined with IC on shrinkage,cement hydration and compressive strength of cement mortar cured under sealed and drying conditions were investigated.For sealed curing,compared with SRA or IC mixtures,when the IC and SRA were used together,the autogenous shrinkage of cement mortar was significantly reduced,which was resulted from the reduction of internal relative humidity drop,a microdilatancy in length was observed in 7 d age,moreover,the ultimate autogenous shrinkage of the mortar was below 100× 10-6 at 28 d age.On the other hand,for drying condition,compared with only using IC,the SRA can significantly enhance the drying shrinkage reduction of internally cured mortar.However,since the moisture loss of internally cured mortar was larger than that of using SRA only,the drying shrinkage of mortar with adding IC and SRA together was greater than that of adding SRA only.Nevertheless,the combination was contributed to the cement hydration and strength development of mortar compared with that of using SRA only.%研究了密封和干燥条件下,使用减缩剂、饱和轻骨料内养护以及两者复合使用对砂浆收缩、水化以及抗压强度的影响.结果表明:密封条件下,较减缩剂和内养护单独使用,两者复合使用能进一步抑制砂浆内部相对湿度的下降,进而使体系自收缩发展速率和水平显著降低,砂浆7d内保持微膨胀状态,28d自收缩率低于100×10-6;干燥条件下,相比仅使用内养护,复合减缩剂后砂浆干燥收缩明显降低,但由于内养护使砂浆失水量增大,复合减缩剂后减缩效果不及仅使用减缩剂的砂浆;两者复合使用后能够显著降低减缩剂单独使用时对水泥水化和砂浆强度的不利影响.

  9. Accurate characterisation of post moulding shrinkage of polymer parts

    DEFF Research Database (Denmark)

    Neves, L. C.; De Chiffre, L.; González-Madruga, D.;

    2015-01-01

    The work deals with experimental determination of the shrinkage of polymer parts after injection moulding. A fixture for length measurements on 8 parts at the same time was designed and manufactured in Invar, mounted with 8 electronic gauges, and provided with 3 temperature sensors. The fixture...... of post moulding shrinkage of polymer parts was developed. Expanded uncertainties (k=2) of 3 μm were obtained....

  10. Method to determine factors contributing to thermoplastic sheet shrinkage

    Science.gov (United States)

    Rensch, Greg J.; Frye, Brad A.

    A test method is presented for the determination of shrinkage behavior in vacuum-formed thermoplastic resin sheeting, as presently simulated for various resin lots, sheet-gage thicknesses, sheet orientations, and mold profiles. The thermoforming machine and vacuum-forming mold characteristics are discussed. It is established that the four variable factors exert statistically significant effects on the shrinkage response of three Declar resin lots, but that these are of no real practical significance for either engineering or manufacturing operations.

  11. Fast shrinkage of tropical glaciers in Colombia

    Science.gov (United States)

    Ceballos, Jorge Luis; Euscátegui, Christian; Ramírez, Jair; Cañon, Marcela; Huggel, Christian; Haeberli, Wilfried; Machguth, Horst

    As a consequence of ongoing atmospheric temperature rise, tropical glaciers belong to the unique and threatened ecosystems on Earth, as defined by the Intergovernmental Panel on Climate Change (Houghton and others, 2001). Worldwide glacier monitoring, especially as part of the Global Climate Observing System (GCOS), includes the systematic collection of data on such perennial surface ice masses. Several peaks in the sierras of Colombia have lost their glacier cover during recent decades. Today, high-altitude glaciers still exist in Sierra Nevada de Santa Marta, in Sierra Nevada del Cocuy and on the volcanoes of Nevados del Ruiz, de Santa Isabel, del Tolima and del Huila. Comparison of reconstructions of maximum glacier area extent during the Little Ice Age with more recent information from aerial photographs and satellite images clearly documents a fast-shrinking tendency and potential disappearance of the remaining glaciers within the next few decades. In the past 50 years, Colombian glaciers have lost 50% or more of their area. Glacier shrinkage has continued to be strong in the last 15 years, with a loss of 10-50% of the glacier area. The relationship between fast glacier retreat and local, regional and global climate change is now being investigated. Preliminary analyses indicate that the temperature rise of roughly 1° C in the last 30 years recorded at high-altitude meteorological stations exerts a primary control on glacier retreat. The investigations on the Colombian glaciers thus corroborate earlier findings concerning the high sensitivity of glaciers in the wet inner tropics to temperature rise. To improve understanding of fast glacier retreat in Colombia, a modern monitoring network has been established according to the multilevel strategy of the Global Terrestrial Network for Glaciers (GTN-G) within GCOS. The observations are also contributions to continued assessments of hazards from the glacier-covered volcanoes and to integrated global change

  12. Acoustic Emission Behavior of Early Age Concrete Monitored by Embedded Sensors

    Directory of Open Access Journals (Sweden)

    Lei Qin

    2014-10-01

    Full Text Available Acoustic emission (AE is capable of monitoring the cracking activities inside materials. In this study, embedded sensors were employed to monitor the AE behavior of early age concrete. Type 1–3 cement-based piezoelectric composites, which had lower mechanical quality factor and acoustic impedance, were fabricated and used to make sensors. Sensors made of the composites illustrated broadband frequency response. In a laboratory, the cracking of early age concrete was monitored to recognize different hydration stages. The sensors were also embedded in a mass concrete foundation to localize the temperature gradient cracks.

  13. Forced expiratory technique, directed cough, and autogenic drainage.

    Science.gov (United States)

    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.

  14. TESTING AND ANALYSIS OF CAP CONCRETE STRESS AND STRAIN DUE TO SHRINKAGE, CREEP, AND EXPANSION FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, H.; Restivo, M.

    2011-08-01

    In-situ decommissioning of Reactors P- and R- at the Savannah River Site will require filling the reactor vessels with a special concrete based on materials such as magnesium phosphate, calcium aluminate or silica fume. Then the reactor vessels will be overlain with an 8 ft. thick layer of Ordinary Portland Cement (OPC) steel reinforced concrete, called the 'Cap Concrete'. The integrity of this protective layer must be assured to last for a sufficiently long period of time to avoid ingress of water into the reactor vessel and possible movement of radioactive contamination into the environment. During drying of this Cap Concrete however, shrinkage strains are set up in the concrete as a result of diffusion and evaporation of water from the top surface. This shrinkage varies with depth in the poured slab due to a non-uniform moisture distribution. This differential shrinkage results in restraint of the upper layers with larger shrinkage by lower layers with lesser displacements. Tensile stresses can develop at the surface from the strain gradients in the bulk slab, which can lead to surface cracking. Further, a mechanism called creep occurs during the curing period or early age produces strains under the action of restraining forces. To investigate the potential for surface cracking, an experimental and analytical program was started under TTQAP SRNL-RP-2009-01184. Slab sections made of Cap Concrete mixture were instrumented with embedded strain gages and relative humidity sensors and tested under controlled environmental conditions of 23 C and relative humidities (RH) of 40% and 80% over a period of 50 days. Calculation methods were also developed for predictions of stress development in the full-scale concrete placement over the reactor vessels. These methods were evaluated by simulating conditions for the test specimens and the calculation results compared to the experimental data. A closely similar test with strain gages was performed by Kim and Lee for

  15. Effect of light-curing units and activation mode on polymerization shrinkage and shrinkage stress of composite resins.

    Science.gov (United States)

    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 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.

  16. Crack Risk Evaluation of Early Age Concrete Based on the Distributed Optical Fiber Temperature Sensing

    Directory of Open Access Journals (Sweden)

    Nannan Shi

    2016-01-01

    Full Text Available Cracks often appear in concrete arch dams, due to the thermal stress and low tensile strength of early age concrete. There are three commonly used temperature controlling measures: controlling the casting temperature, burying cooling pipe, and protecting the surface. However, because of the difficulty to obtain accurate temperature and thermal stress field of the concrete, the rationality and economy of these measures are not assessed validly before and after construction. In this paper, a crack risk evaluation system for early age concrete is established, including distributed optical fiber temperature sensing (DTS, prediction of temperature and stress fields, and crack risk evaluation. Based on the DTS temperature data, the back-analysis method is applied to retrieve the thermal parameters of concrete. Then, the temperature and thermal stress of early age concrete are predicted using the reversed thermal parameters, as well as the laboratory test parameters. Finally, under the proposed cracking risk evaluation principle, the cracking risk level of each concrete block is given; the preliminary and later temperature controlling measures were recommended, respectively. The application of the proposed system in Xiluodu super high arch dam shows that this system works effectively for preventing cracks of early age concrete.

  17. Early age stress-crack opening relationships for high performance concrete

    DEFF Research Database (Denmark)

    Østergaard, Lennart; Lange, David A.; Stang, Henrik

    2004-01-01

    Stress–crack opening relationships for concrete in early age have been determined for two high performance concrete mixes with water to cementitious materials ratios of 0.307 and 0.48. The wedge splitting test setup was used experimentally and the cracked nonlinear hinge model based on the fictit...

  18. ESEM drying tests: microcracking initiation in thin cement paste due to early age drying

    NARCIS (Netherlands)

    Jankovic, D.

    2009-01-01

    Scattered and discontinues microcracking as a subsequent side-effect of deformations due to early age drying, occurs in thin (approximately 1 mm thick) cement paste samples, when stepwise dried in ESEM. Microcracking of cement paste and restrains appear to be practically unavoidable. They are relate

  19. Effect of Superplasticizers on the Early Age Hydration of Sulfoaluminate Cement

    Institute of Scientific and Technical Information of China (English)

    YUAN Xiaohui; CHEN Wei; YANG Mo

    2014-01-01

    The effects of two types of superplasticizers on the properties of CSA cement pastes during early hydration were studied. The influences of two types of superplasticizers on the properties of cement pastes, including the normal consistency, setting time, fluidity, and compressive strength, were investigated by using various methods. The hydration products of the cement pastes cured for 1 day and 3 days were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the PCE type superplasticizer retards the early age hydration while the FDN type superplasticizer accelerates the early age hydration of the CSA cement. Both types of superplasticizers have no influence on the further hydration of CSA cement, confirmed by the calorimeter tests as well. The ultrasonic pulse velocity measurements were used to probe the influence of two types of superplasticizers on the hydration of CSA cement pastes at a high water-cement ratio (0.45). The results show that the PCE type superplasticizer retards the early age hydration of the CSA cement while the FDN type superplasticizer has little influence on the early age hydration of the CSA cement.

  20. Plastic and free shrinkages cracking of blended white cement concrete

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, A.M.; White, T.; Ariaratnam, S.; Knutson, K. [Housing and Building National Research Center, Cairo (Egypt)

    2007-07-01

    This paper presented the results of a study that investigated the plastic and free shrinkages of white portland cement concrete, concrete incorporating silica fume (SF) and concrete incorporating metakaolin (MK) compared to regular plain gray portland cement concrete. An experimental program was designed to investigate the plastic and free shrinkage of concrete containing gray and white blended cement. The paper discussed the experimental details including materials and cement types such as SF, MK, aggregate, and superplasticizer as well as concrete mixtures and specimen preparation including mixture proportions, preparation and curing of concrete specimens, and test specimens. It also presented the determination of concrete properties such as slump of fresh concrete, plastic shrinkage, and dry shrinkage. Test results and discussion of results were also provided. It was concluded that plain white portland cement concrete showed less number of plastic cracks but slightly higher average crack width compared to other concrete mixtures with MK or SF. In addition, free shrinkage behavior of plain white cement and plain gray cement matrix was comparable. 23 refs.

  1. Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

    Science.gov (United States)

    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.

  2. Effect of light-curing units and activation mode on polymerization shrinkage and shrinkage stress of composite resins

    Directory of Open Access Journals (Sweden)

    Lawrence Gonzaga Lopes

    2008-02-01

    Full Text Available 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.

  3. Autogenic reaction synthesis of photocatalysts for solar fuel generation

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Autogenic reaction synthesis of photocatalysts for solar fuel generation

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Linear Shrinkage Behaviour of Compacted Loam Masonry Blocks

    Directory of Open Access Journals (Sweden)

    NAWAB ALI LAKHO

    2017-04-01

    Full Text Available Walls of wet loam, used in earthen houses, generally experience more shrinkage which results in cracks and less compressive strength. This paper presents a technique of producing loam masonry blocks that are compacted in drained state during casting process in order to minimize shrinkage. For this purpose, loam masonry blocks were cast and compacted at a pressure of 6 MPa and then dried in shade by covering them in plastic sheet. The results show that linear shrinkage of 2% occurred which is smaller when compared to un-compacted wet loam walls. This implies that the loam masonry blocks compacted in drained state is expected to perform better than un-compacted wet loam walls.

  6. Brain shrinkage and subdural effusion associated with ACTH administration.

    Science.gov (United States)

    Satoh, J; Takeshige, H; Hara, H; Fukuyama, Y

    1982-01-01

    Sequential computed tomographic (CT) studies of 11 patients (aged five months to seven years) with intractable epilepsy treated with synthetic ACTH-Z showed brain shrinkage in all cases. Brain shrinkage started to appear on daily ACTH injections for seven days, reached the maximum within four weeks of administration (14 injections every day and then 7 injections every other day), and almost returned to the original status in seven out of nine cases which were followed up for one to three months after the therapy. The subjects aged less than two years showed more remarkable brain shrinkage than did those aged more than five years. Furthermore, two other cases were complicated by subdural effusion after ACTH therapy. It is the authors' assumption that both of these phenomena are caused by the high concentration of corticosteroid through a change of the water and electrolyte contents in the brain.

  7. Compressive dynamic range imaging via Bayesian shrinkage dictionary learning

    Science.gov (United States)

    Yuan, Xin

    2016-12-01

    We apply the Bayesian shrinkage dictionary learning into compressive dynamic-range imaging. By attenuating the luminous intensity impinging upon the detector at the pixel level, we demonstrate a conceptual design of an 8-bit camera to sample high-dynamic-range scenes with a single snapshot. Coding strategies for both monochrome and color cameras are proposed. A Bayesian reconstruction algorithm is developed to learn a dictionary in situ on the sampled image, for joint reconstruction and demosaicking. We use global-local shrinkage priors to learn the dictionary and dictionary coefficients representing the data. Simulation results demonstrate the feasibility of the proposed camera and the superior performance of the Bayesian shrinkage dictionary learning algorithm.

  8. Improving the Incoherence of a Learned Dictionary via Rank Shrinkage.

    Science.gov (United States)

    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.

  9. Prediction of ALLOY SHRINKAGE FACTORS FOR THE INVESTMENT CASTING PROCESS

    Energy Technology Data Exchange (ETDEWEB)

    Sabau, Adrian S [ORNL

    2006-01-01

    This study deals with the experimental measurements and numerical predictions of alloy shrinkage factors (SFs) related to the investment casting process. The dimensions of the A356 aluminum alloy casting were determined from the numerical simulation results of solidification, heat transfer, fluid dynamics, and deformation phenomena. The investment casting process was carried out using wax patterns of unfilled wax and shell molds that were made of fused silica with a zircon prime coat. The dimensions of the die tooling, wax pattern, and casting were measured, in order to determine the actual tooling allowances. Several numerical simulations were carried out, to assess the level of accuracy for the casting shrinkage. The solid fraction threshold, at which the transition from the fluid dynamics to the solid dynamics occurs, was found to be important in predicting shrinkage factors (SFs). It was found that accurate predictions were obtained for all measued dimensions when the shell mold was considered a deformable material.

  10. Shrinkage anisotropy characteristics from soil structure and initial sample/layer size

    CERN Document Server

    Chertkov, V Y

    2014-01-01

    The objective of this work is a physical prediction of such soil shrinkage anisotropy characteristics as variation with drying of (i) different sample/layer sizes and (ii) the shrinkage geometry factor. With that, a new presentation of the shrinkage anisotropy concept is suggested through the sample/layer size ratios. The work objective is reached in two steps. First, the relations are derived between the indicated soil shrinkage anisotropy characteristics and three different shrinkage curves of a soil relating to: small samples (without cracking at shrinkage), sufficiently large samples (with internal cracking), and layers of similar thickness. Then, the results of a recent work with respect to the physical prediction of the three shrinkage curves are used. These results connect the shrinkage curves with the initial sample size/layer thickness as well as characteristics of soil texture and structure (both inter- and intra-aggregate) as physical parameters. The parameters determining the reference shrinkage c...

  11. Peculiarities of application the method of autogenic training in the correction of eating behavior

    OpenAIRE

    Shebanova, Vitaliya

    2014-01-01

    The article presented peculiarities of applying the method of autogenic training in the correction of eating disorders. Described stages of correction work with desadaptive eating behavior. Author makes accent on the rules self-assembly formula intentions.

  12. Optimal linear shrinkage corrections of sample LMMSE and MVDR estimators

    OpenAIRE

    2012-01-01

    La proposició d'estimadors shrinkage òptims que corregeixen la degradació dels mètodes sample LMMSE i sample MUDR en el règim on el número de mostres és petit en comparació a la dimensió de les observacions. [ANGLÈS] This master thesis proposes optimal shrinkage estimators that counteract the performance degradation of the sample LMMSE and sample MVDR methods in the regime where the sample size is small compared to the observation dimension. [CASTELLÀ] Esta máster tesis propone estimado...

  13. Hydration of Portoguese cements, measurement and modelling of chemical shrinkage

    DEFF Research Database (Denmark)

    Maia, Lino; Geiker, Mette Rica; Figueiras, Joaquim A.

    2008-01-01

    form of the dispersion model. The development of hydration varied between the investigated cements; based on the measured data the degree of hydration after 24 h hydration at 20 C varied between 40 and 50%. This should be taken into account when comparing properties of concrete made from the different......Development of cement hydration was studied by measuring the chemical shrinkage of pastes. Five types of Portuguese Portland cement were used in cement pastes with . Chemical shrinkage was measured by gravimetry and dilatometry. In gravimeters results were recorded automatically during at least...

  14. Self-cementing Mechanism of CFBC Coal Ashes at Early Ages

    Institute of Scientific and Technical Information of China (English)

    SONG Yuanming; QIAN Jueshi; WANG Zhi; WANG Zhijuan

    2008-01-01

    The self-cementing mechanism at early ages of circulating fluidized bed combustion (CFBC) coal ashes was studied by X-ray diffraction (XRD), infrared (IR) spectroscopy and chemical method. The results indicate that the amorphous phase is predominant in CFBC coal ashes. The polymerization degree of [SiO4] and [AlO6] of CFBC desulphurization coal ashes is lower than that of those without desulphurization. The contents of the components with fast hydration rate of CFBC desulphurization coal ashes are significantly greater than those of the ashes without desulphurization. This work confirms that the amorphous minerals with high chemical activity are the main causes of the self-cementing property of CFBC desulphurization coal ashes at early ages.

  15. DEVELOPING OF HIGH QUALITY COURSE MATERIALS TO IMPROVE EARLY AGE PRACTITIONERS’ EDUCATION

    Directory of Open Access Journals (Sweden)

    MONA VINTILA

    2012-11-01

    Full Text Available The pre-primary age is an especially sensitive period in children’s development but high quality education and care from a very early age creates a good foundation for lifelong learning. This is why performant teacher education is needed.This paper addresses the issue of early age practitioners’ education presenting an European project that aims to develop course materials that focus on the major areas in early learning and contribute to the development of research based, pedagogical approaches within three areas that are crucial in respect to get all toddlers on a successful life learning road: learning of language(s and focus on the teacher-child communication, improved knowledge of how to foster toddlers'wellbeing, identifying crucial aspects for improved parental involvement.

  16. Drying shrinkage of mortars with limestone filler and blast-furnace slag

    Directory of Open Access Journals (Sweden)

    Carrasco, M. F.

    2003-12-01

    Full Text Available During the 1990's the use of cements made with port land clinker and two mineral admixtures, called ternary or blended cements, has grown considerably. Nowadays, cements containing several combinations of fly ash and silica fume, blast-furnace slag and silica fume or blast-furnace slag and limestone filler are commonly used. There are numerous works on the influence of blended cements on the fresh state and mechanical properties of mortar and concrete, but the their deformations due to drying shrinkage are not so well described. Analysis of drying shrinkage is relevant because this property influences the possibility of cracking occurrence and, hence, the deterioration of mechanical and durable properties of concrete structures. This paper evaluates the influence on the drying shrinkage of mortars of variable contents of limestone filler and/or blast-furnace slag in Portland cement. Additionally, flexion strength and non evaporable water content were evaluated. Test results show that the inclusion of these mineral admixtures, Joint or separately, increments drying shrinkage of mortars at early ages. Despite this fact, mortars made with limestone filler cement are less susceptible to cracking than mortars made with cements incorporating blast-furnace slag or both admixtures.

    Durante los años 90 el uso de cementos fabricados con clínker Portland y dos adiciones suplementarias (cementos ternarios o compuestos se ha incrementado en forma considerable. En la práctica, es cada vez más común el empleo de estos cementos conteniendo combinaciones de ceniza volante y humo de sílice, escoria y humo de sílice o escoria y filler calcáreo. En la actualidad existen numerosos estudios sobre la influencia de los cementos compuestos en las características en estado fresco y las propiedades mecánicas de morteros y hormigones, pero las deformaciones que estos materiales sufren debido a la retracción por secado no son tan conocidas. El análisis de

  17. Early-age concrete strength estimation based on piezoelectric sensor using artificial neural network

    Science.gov (United States)

    Kim, Junkyeong; Kim, Ju-Won; Park, Seunghee

    2014-04-01

    Recently, novel methods to estimate the strength of concrete have been reported based on numerous NDT methods. Especially, electro-mechanical impedance technique using piezoelectric sensors are studied to estimate the strength of concrete. However, the previous research works could not provide the general information about the early-age strength important to manage the quality of concrete and/or the construction process. In order to estimate the early-age strength of concrete, the electro-mechanical impedance method and the artificial neural network(ANN) is utilized in this study. The electro-mechanical impedance varies with the mechanical properties of host structures. Because the strength development is most influential factor among the change of mechanical properties at early-age of curing, it is possible to estimate the strength of concrete by analyzing the change of E/M impedance. The strength of concrete is a complex function of several factors like mix proportion, temperature, elasticity, etc. Because of this, it is hard to mathematically derive equations about strength of concrete. The ANN can provide the solution about early-age strength of concrete without mathematical equations. To verify the proposed approach, a series of experimental studies are conducted. The impedance signals are measured using embedded piezoelectric sensors during curing process and the resonant frequency of impedance is extracted as a strength feature. The strength of concrete is calculated by regression of strength development curve obtained by destructive test. Then ANN model is established by trained using experimental results. Finally the ANN model is verified using impedance data of other sensors.

  18. Relationship between macular pigment and visual function in subjects with early age-related macular degeneration

    OpenAIRE

    Akuffo, Kwadwo Owusu; Nolan, John M.; Peto, Tunde; Stack, Jim; Leung, Irene; Corcoran, Laura; Beatty, Stephen

    2016-01-01

    Purpose To investigate the relationship between macular pigment (MP) and visual function in subjects with early age-related macular degeneration (AMD). Methods 121 subjects with early AMD enrolled as part of the Central Retinal Enrichment Supplementation Trial (CREST; ISRCTN13894787) were assessed using a range of psychophysical measures of visual function, including best corrected visual acuity (BCVA), letter contrast sensitivity (CS), mesopic and photopic CS, mesopic and photopic glare disa...

  19. Characterization of Moisture Diffusion in Cured Concrete Slabs at Early Ages

    OpenAIRE

    Xiao Zhang; Hongduo Zhao

    2015-01-01

    The objective of this paper is to investigate the characterization of moisture diffusion inside early-age concrete slabs subjected to curing. Time-dependent relative humidity (RH) distributions of three mixture proportions subjected to three different curing methods (i.e., air curing, water curing, and membrane-forming compounds curing) and sealed condition were measured for 28 days. A one-dimensional nonlinear moisture diffusion partial differential equation (PDE) based on Fick’s second law,...

  20. A Numerical Model for the Thermomechanical Conditions During Hydration of Early-age Concrete

    DEFF Research Database (Denmark)

    Hattel, Jesper; Thorborg, Jesper

    2003-01-01

    In the present study, a macroscopic numerical model for the thermomechanical conditions during hydration of early-age concrete is presented. The formulation is based on a semi-coupled, incremental thermomechanical model where the heat production from the hydration process is expressed in terms of...... analytical solutions are carried out as well as examples of analysis of real concrete structures. (C) 2002 Elsevier Science Inc. All rights reserved....

  1. Artificial Neural Network-Based Early-Age Concrete Strength Monitoring Using Dynamic Response Signals.

    Science.gov (United States)

    Kim, Junkyeong; Lee, Chaggil; Park, Seunghee

    2017-06-07

    Concrete is one of the most common materials used to construct a variety of civil infrastructures. However, since concrete might be susceptible to brittle fracture, it is essential to confirm the strength of concrete at the early-age stage of the curing process to prevent unexpected collapse. To address this issue, this study proposes a novel method to estimate the early-age strength of concrete, by integrating an artificial neural network algorithm with a dynamic response measurement of the concrete material. The dynamic response signals of the concrete, including both electromechanical impedances and guided ultrasonic waves, are obtained from an embedded piezoelectric sensor module. The cross-correlation coefficient of the electromechanical impedance signals and the amplitude of the guided ultrasonic wave signals are selected to quantify the variation in dynamic responses according to the strength of the concrete. Furthermore, an artificial neural network algorithm is used to verify a relationship between the variation in dynamic response signals and concrete strength. The results of an experimental study confirm that the proposed approach can be effectively applied to estimate the strength of concrete material from the early-age stage of the curing process.

  2. Characterization of Moisture Diffusion in Cured Concrete Slabs at Early Ages

    Directory of Open Access Journals (Sweden)

    Xiao Zhang

    2015-01-01

    Full Text Available The objective of this paper is to investigate the characterization of moisture diffusion inside early-age concrete slabs subjected to curing. Time-dependent relative humidity (RH distributions of three mixture proportions subjected to three different curing methods (i.e., air curing, water curing, and membrane-forming compounds curing and sealed condition were measured for 28 days. A one-dimensional nonlinear moisture diffusion partial differential equation (PDE based on Fick’s second law, which incorporates the effect of curing in the Dirichlet boundary condition using a concept of curing factor, is developed to simulate the diffusion process. Model parameters are calibrated by a genetic algorithm (GA. Experimental results show that the RH reducing rate inside concrete under air curing is greater than the rates under membrane-forming compound curing and water curing. It is shown that the effect of water-to-cement (w/c ratio on self-desiccation is significant. Lower w/c ratio tends to result in larger RH reduction. RH reduction considering both effect of diffusion and self-desiccation in early-age concrete is not sensitive to w/c ratio, but to curing method. Comparison between model simulation and experimental results indicates that the improved model is able to reflect the effect of curing on moisture diffusion in early-age concrete slabs.

  3. Early-age Electrical Resistivity and Reactive Capacity of Mineral Admixtures in Mortars

    Institute of Scientific and Technical Information of China (English)

    LIANG Wenquan; HE Zhen; ZHANG Yongchuan; CHEN Meizhu; YANG Huaquan

    2006-01-01

    A non-contacting electrical resistivity measurement device was used to investigate the effect of different types and contents of mineral admixtures on the hydration performance of mortars during early age. The experimental results show that the changes of measured resistivity with time of hydration can be used to describe the hydration characteristics of cement- based materials, as well as the physical and chemical behavior of fly ash; blast furnace slag and silica fume at the very early ages. With an increasing replacement ratio of mineral admixtures, for the specimens blended with fly ash or slag, the resistivity increases firstly, then the following flatting period extends and after setting the resistivity increasing becomes slow and consequently a lower resistivity value at 24 hours occurs. This is due to the dilution effect and lower pozzolanic/ hydraulic activity of fly ash and slag. However, for the samples incorporated with silica fume, the resistivity value through 24 hours is lower with shorter flatting period and larger slope in the resistivity curves, which is because of its particle size effect and higher pozzolanic activity of silica fume. Moreover, non-contacting resistivity measurement might provide a helpful information to predict the long term performance including the durability of cement-based materials at early ages.

  4. Changes of Ca2+ activated potassium channels and cellular proliferation in autogenous vein grafts

    Institute of Scientific and Technical Information of China (English)

    钱济先; 宋胜云; 马保安; 范清宇

    2003-01-01

    Objective: To investigate changes of Ca2+ activated potassium channels (KCa) in autogenous vein grafts. Methods: Contraction of venous ring was measured by means of perfusion in vitro. The intimal rabbits proliferation of vascular and proliferation of cultured smooth muscle cells(vascular smooth muscle cells, VSMCs)were observed by the means of computerised image analysis and MTT method respectively. Furthermore, whole cell mode of patch clamp was used to record KCa of VSMCs isolated from autogenous vein grafts. Results: One week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation (P<0.05, n=8 vs control), and they was more enhanced 4 weeks after vein transplantation (P<0.01, n=8 vs control).TEA(blocker of Ca2+ activated potassium channels)increased MTT A490 nm value of VSMCs from femoral vein in a dose dependent manner(P<0.05, n=8). KCa current density was significantly attenuated in VSMCs from autogenous vein grafts (1-4) week after transplantation(P<0.05, n=5).Conclusion: KCa is inhibited in autogenous vein graft, which account for vasospasm and intimal proliferation.

  5. 偏高岭土对硅酸盐水泥浆体干燥收缩行为的影响及机理%Effect of Metakaolin on Drying Shrinkage Behaviour of Portland Cement Pastes and its Mechanism

    Institute of Scientific and Technical Information of China (English)

    罗旌旺; 卢都友; 许涛; 许仲梓

    2011-01-01

    In order to explore the mechanism of the effect of the metakaolin (MK) effect on the drying shrinkage of cementitious ma- terials, the drying shrinkage and mass loss of blended Portland cement pastes with various MK contents (0, 5%, 10%, 15%) and different maturities (precured in water for 3 d and 28 d, respectively), were investigated by drying at 20 ℃ and 55% relative humidity. The composition and microstructure of cement pastes were determined by thermal analysis and mercury intrusion porosimetry. The results show that the effect of MK on the drying shrinkage of cement pastes is closely related to the MK content and maturity of the pastes. The late-age drying shrinkage of cement pastes with different maturities decreased with the increase of MK contents. However, the effect on the early age drying shrinkage depended on the maturity of paste. The MK increased slightly the early age drying shrinkage of the paste pre-cured for 3 d, and decreased the early age shrinkage of the paste pre-cured for 28 d. The drying shrinkage of cement paste was proportional to its mass loss and the mechanism of water loss and its relation with the drying shrinkage varied. The decrease of drying shrinkage of blended cement paste with the MK was due to the result of less and slower evaporation of water in the MK blended cement paste with low porosity and refined pores structure by the micro-filler effect, nuclear effect and/or pozzolanic reaction of the MK.%为探究偏高岭土(metakaolin,MK)影响水泥基材料干燥收缩(干缩)机理,研究了不同MK掺量(0、5%、10%、15%)、不同成熟度(水中分别预养护3d和28d)硅酸盐水泥浆体在20℃、55%相对湿度下的干缩和质量损失行为,并采用综合热分析和压汞法研究了不同成熟度水泥浆体的组成和微观结构。结果表明:MK对浆体干燥收缩行为的影响与掺量和浆体成熟度密切相关;MK使不同成熟度水泥浆体长期(28

  6. Stiffness and shrinkage of green and dry joists

    Science.gov (United States)

    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,...

  7. Effect of processing conditions on shrinkage in injection molding

    NARCIS (Netherlands)

    Jansen, K.M.B.; Dijk, van D.J.; Husselman, M.H.

    1998-01-01

    A systematic study on the effect of processing conditions on mold shrinkage was undertaken for seven common thermoplastic polymers. It turned out that the holding pressure was always the key parameter. The effect of the melt temperature is slightly less important. Injection velocity and mold tempera

  8. Postoperative sensitivity associated with low shrinkage versus conventional composites

    OpenAIRE

    Ivanović Vladimir; Savić-Stanković Tatjana; Karadžić Branislav; Ilić Jugoslav; Santini Ario; Beljić-Ivanović Katarina

    2013-01-01

    Introduction. Postoperative sensitivity in restorative dentistry can be related to preparation trauma, dentin adhesives’ ability to seal open dentinal tubules, deformation of restorations under occlusal stresses and microleakage. Objective. The study assessed possible reduction in postoperative sensitivity with low shrinkage compared to conventional composites using different bonding agents and the influence of the operator skill on the incidence of postoperative sensitivity. Methods. N...

  9. The Shrinkage Cracking Behavior in Reinforced Reactive Powder Concrete Walls

    Directory of Open Access Journals (Sweden)

    Samir A. Al-Mashhadi

    2017-07-01

    Full Text Available In this study, the reduced scale wall models were used (they are believed to resemble as much as possible the field conditions to study the shrinkage behavior of reactive powder concrete (RPC base restrained walls. Six base restrained RPC walls were casted in different length/height ratios of two ratios of steel fiber by volume in Summer. These walls were restrained by reinforced concrete bases to provide the continuous base restraint to the walls. The mechanical properties of reactive powder concrete investigated were; compressive strength between (75.3 – 140.1 MPa, splitting tensile strength between (5.7 – 13.9 MPa, flexural tensile strength (7.7 – 24.5 MPa, and static modulus of elasticity (32.7 – 47.1GPa. Based on the observations of this work, it was found that the cracks did not develop in the reduced scale of the reactive powder concrete (RPC walls restrained from movement at their bases for different L/H ratios (2, 5, and 10 and for two ratio of steel fiber (1% & 2% during 90 days period of drying conditions. Moreover, the shrinkage values increase toward the edges. Based on the results of this work, the increase in the maximum shrinkage values of walls with 1% steel fiber were (29%, 28%, 28% of the maximum shrinkage values of walls with 2% steel fiber of length/height ratios of (2, 5, and 10 respectively. The experimental observation in beam specimens showed that the free shrinkage, tensile strain capacity and elastic tensile strain capacity (at date of cracking of beams with 1% steel fiber were higher than the beams with 2% steel fiber by about (24%, (45% and (42% respectively

  10. Cure shrinkage effects in epoxy and polycyanate matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Spellman, G.P.

    1995-12-22

    A relatively new advanced composite matrix, polycyanate ester, was evaluated for cure shrinkage. The chemical cure shrinkage of composites is difficult to model but a number of clever experimental techniques are available to the investigator. In this work the method of curing a prepreg layup on top of a previously cured laminate of identical ply composition is utilized. The polymeric matrices used in advanced composites have been primarily epoxies and therefore a common system of this type, Fiberite 3501-6, was used as a base case material. Three polycyanate matrix systems were selected for the study. These are: Fiberite 954-2A, YLA RS-3, and Bryte Technology BTCy-1. The first three of these systems were unidirectional prepreg with carbon fiber reinforcement. The Bryte Technology material was reinforced with E-glass fabric. The technique used to evaluate cure shrinkage results in distortion of the flatness of an otherwise symmetric laminate. The first laminate is cured in a conventional fashion. An identical layup is cured on this first laminate. During the second cure all constituents are exposed to the same thermal cycles. However, only the new portion of the laminate will experience volumetric changes associate with matrix cure. The additional strain of cure shrinkage results in an unsymmetric distribution of residual stresses and an associated warpage of the laminate. The baseline material, Fiberite 3501-6, exhibited cure shrinkage that was in accordance with expectations. Cure strains were {minus}4.5E-04. The YLA RS-3 material had cure strains somewhat lower at {minus}3.2E-04. The Fiberite 954-2A cure strain was {minus}1.5E-04 that is 70% lower than the baseline material. The glass fabric material with the Bryte BTCy-1 matrix did not result in meaningful results because the processing methods were not fully compatible with the material.

  11. Untangling climatic and autogenic signals in peat records

    Science.gov (United States)

    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

  12. UFA水泥基材料早期自收缩与干燥收缩研究%Early autogenous shrinkage and dry shrinkage of cement based materials containing ultra-fine fly ash

    Institute of Scientific and Technical Information of China (English)

    高英力; 周士琼; 马保国

    2008-01-01

    低水胶比条件下水泥基材料的自收缩率已超过干燥收缩率成为导致混凝土过早开裂的隐患.以超细粉煤灰(ultra-fine fly ash,UFA)等量取代水泥20%~40%,配制了UFA水泥基复合胶凝材料,分别对固定水胶比和变水胶比两种情况下的UFA水泥砂浆早期(7 d前)自收缩变形和干燥收缩变形进行试验研究.结果表明,在固定水胶比条件下,砂浆的自收缩率随UFA掺量增加递减,而干缩率却随之增大;在变水胶比条件下,砂浆的自收缩率随水胶比的增加递减,干缩率随之增大.且回归分析表明两种情况下砂浆的自收缩及干燥收缩变形均表现出较好的线性相关;UFA对水泥基材料改性作用明显,在保持相同流动度条件下,UFA的掺入可有效降低用水量,早期及后期强度能赶上甚至超过基准水泥胶砂,弥补了UFA早期不水化所引发的早期强度低缺陷;微观测试表明,UFA在水泥基材料中起到了较好的密实填充、减水分散及增强作用.

  13. Reconstruction of the mandible with a poly(D,L-lactide) scaffold, autogenous corticocancellous bone graft, and autogenous platelet-rich plasma: an animal experiment.

    NARCIS (Netherlands)

    Fennis, J.P.M.; Stoelinga, P.J.W.; Merkx, M.A.T.; Jansen, J.A.

    2005-01-01

    An animal study is presented, evaluating a method of mandibular reconstruction using a poly(D,Llactide) (PDLLA) scaffold. Six goats underwent a continuity resection of the mandibular angle. The defect was bridged with a preshaped PDLLA scaffold, filled with an autogenous particulate bone graft from

  14. Study of ‘real’ shrinkage by ESEM observations and digital image analysis

    NARCIS (Netherlands)

    Jankovic, D.

    2007-01-01

    Defining the 'real' shrinkage values of concrete is still a subject of much debate. In shrinkage experiments size effects are inherently present. Through an attempt to determine the real shrinkage of cement-based materials, these size effects have to be eliminated or at least reduced as much a possi

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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)

  17. Frontalis muscle flap suspension for the correction of congenital blepharoptosis in early age children.

    Directory of Open Access Journals (Sweden)

    Dianju Hou

    Full Text Available BACKGROUND: We aimed to report our successful use of frontalis muscle flap suspension for the correction of congenital blepharoptosis in early age children. METHODS: This retrospective study included 61 early age children (41 boys, 20 girls with an average age of 6 years (range, 3-10 years with congenital blepharoptosis who received surgery during the period from March 2007 to January 2011. There were 39 cases of unilateral blepharoptosis and 22 cases of bilateral blepharoptosis, thus a total of 83 eyes were affected. If patient had bilateral blepharoptosis, both eyes were operated on in the same surgery. Patients were followed for 3 months to 5 years. The procedure was performed without complications in all cases. RESULTS: The postoperative healing grade was good in 81 eyes (97.6%; the correction of blepharoptosis was satisfactory, the double eyelid folds were natural and aesthetic, the eyelid position and the curvature were ideal, and the eyes were bilaterally symmetrical. The postoperative healing grade was fair in 2 eyes (2.4%; blepharoptosis was improved compared with that before surgery. At discharge, lagophthalmos was noted in 10 eyes of which 4 cases resolved by the last follow-up. The remaining 6 cases were mild. Eleven eyes received reoperation for residual ptosis after the first surgery. The curvature of the palpebral margin was not natural in 4 eyes. These unnatural curvature possibly was caused by an excessively low lateral fixation point or postoperative avulsion. CONCLUSION: Frontalis muscle flap suspension under general anesthesia for the correction of congenital blepharoptosis in early age children can achieve good surgical results.

  18. Autogenic training: a meta-analysis of clinical outcome studies.

    Science.gov (United States)

    Stetter, Friedhelm; Kupper, Sirko

    2002-03-01

    Autogenic training (AT) is a self-relaxation procedure by which a psychophysiological determined relaxation response is elicited. A meta-analysis was performed to evaluate the clinical effectiveness of AT. Seventy-three controlled outcome studies were found (published 1952-99). Sixty studies (35 randomized controlled trials [RCT]) qualified for inclusion in the meta-analysis. Medium-to-large effect sizes (ES) occurred for pre-post comparisons of disease-specific AT-effects, with the RCTs showing larger ES. When AT was compared to real control conditions, medium ES were found. Comparisons of AT versus other psychological treatment mostly resulted in no effects or small negative ES. This pattern of results was stable at follow-up. Unspecific AT-effects (i.e., effects on mood, cognitive performance, quality of life, and physiological variables) tended to be even larger than main effects. Separate meta-analyses for different disorders revealed a significant reduction of the heterogeneity of ES. Positive effects (medium range) of AT and of AT versus control in the meta-analysis of at least 3 studies were found for tension headache/migraine, mild-to-moderate essential hypertension, coronary heart disease, asthma bronchiale, somatoform pain disorder (unspecified type), Raynaud's disease, anxiety disorders, mild-to-moderate depression/dysthymia, and functional sleep disorders.

  19. Dynamic correlations between heart and brain rhythm during Autogenic meditation

    Directory of Open Access Journals (Sweden)

    Daekeun eKim

    2013-07-01

    Full Text Available This study is aimed to determine significant physiological parameters of brain and heart under meditative state, both in each activities and their dynamic correlations. Electrophysiological changes in response to meditation were explored in 12 healthy volunteers who completed 8 weeks of a basic training course in autogenic meditation. Heart coherence, representing the degree of ordering in oscillation of heart rhythm intervals, increased significantly during meditation. Relative EEG alpha power and alpha lagged coherence also increased. A significant slowing of parietal peak alpha frequency was observed. Parietal peak alpha power increased with increasing heart coherence during meditation, but no such relationship was observed during baseline. Average alpha lagged coherence also increased with increasing heart coherence during meditation, but, again, no significant relationship was observed at baseline. Relative alpha power increased with increasing heart coherence during both meditation and baseline periods. Heart coherence can be a cardiac marker for the meditative state and also may be a general marker for the meditative state since heart coherence is strongly correlated with EEG alpha activities. It is expected that increasing heart coherence and the accompanying EEG alpha activations, heart brain synchronicity, would help recover physiological synchrony following a period of homeostatic depletion.

  20. Sinusfloor elevation and grafting with autogenous iliac crest bone.

    Science.gov (United States)

    van den Bergh, J P; ten Bruggenkate, C M; Krekeler, G; Tuinzing, D B

    1998-12-01

    Insufficient bone height in the posterior area of the maxilla, due to expansion of the maxillary sinus and atrophic reduction of the alveolar process of the maxilla, represents a contra-indication for insertion of dental implants. This anatomic problem can, in many cases, be solved by augmentation of the floor of the maxillary sinus. This surgical technique was introduced by Tatum. The so-called top hinge door method creates a new floor of the maxillary sinus at a more cranial level. Underneath this new floor the existing space is filled with a bone graft. Implantation in the alveolar process with increased bone height allows insertion of dental implants. This sinus grafting technique was used in the present study. In total, 62 sinusfloor elevations were performed with cancellous iliac bone grafts in 42 patients. In those 62 augmented sinuses, 161 ITI screw type implants were inserted. The follow-up was 1-6 years after implantation. In 2 cases infections occurred. One implant needed an extended integration time. No implants were lost. The ITI solid screw implant appears to be a suitable implant following sinusfloor elevation operations, due to its rough surface, its shape and the size of the thread. The sinusfloor elevation procedure with autogenous cancellous bone graft appears to be a valuable and reliable pre-implantological procedure, provided a proper pre-operative investigation and careful surgery are performed. This procedure allows dental implant placement with a high success rate.

  1. Reorganization of the Brain and Heart Rhythm During Autogenic Meditation

    Directory of Open Access Journals (Sweden)

    Dae-Keun eKim

    2014-01-01

    Full Text Available The underlying changes in heart coherence that are associated with reported EEG changes in response to meditation have been explored. We measured EEG and heart rate variability (HRV before and during autogenic meditation. Fourteen subjects participated in the study. Heart coherence scores were significantly increased during meditation compared to the baseline. We found near significant decrease in high beta absolute power, increase in alpha relative power and significant increases in lower(alpha and higher(above beta band coherence during 3 minute epochs of heart coherent meditation compared to 3 minute epochs of heart noncoherence at baseline. The coherence and relative power increase in alpha band and absolute power decrease in high beta band could reflect relaxation state during the heart coherent meditation. The coherence increase in the higher(above beta band could reflect cortico-cortical local integration and thereby affect cognitive reorganization, simultaneously with relaxation. Further research is still needed for a confirmation of heart coherence as a simple window for the meditative state.

  2. Reduced frequency of nickel allergy upon oral nickel contact at an early age

    DEFF Research Database (Denmark)

    Van Hoogstraten, I M; Andersen, Klaus Ejner; Von Blomberg, B M

    1991-01-01

    the feasibility of oral prevention of undesired T cell-mediated immunity in man. Potentially tolerizing (oral nickel contacts via orthodontic braces) as well as sensitizing (ear piercing) events were studied retrospectively in 2176 patients attending nine European patch test clinics. Patients were interviewed...... by means of a confidential questionnaire. The results show that ear piercing strongly favoured development of nickel ACH. More importantly, patients having had oral contacts with nickel-releasing appliances (dental braces) at an early age, but only if prior to ear piercing, showed a reduced frequency...

  3. Early Age Thermal Conditioning Improves Broiler Chick's Response to Acute Heat Stress at Marketing Age

    Directory of Open Access Journals (Sweden)

    Ahmed M. Hassan

    2012-01-01

    Full Text Available Problem statement: Acute heat stress at marketing age especially in broiler chickens raised in open houses with reduced means of heat exchange leads to economic losses. The objective of this study was to determine beneficial effects of early age thermal conditioning in reducing adverse effects of acute heat stress and decrease losses. Approach: Ninety one day-old broiler chicks were randomly assigned to one of three treatments (n = 30: (1 control (normally raised, (2 early age thermal conditioning (exposed to temperature of 40±1°C for 24 h at 5th day of age, then raised as control chicks and (3 chronic stress (exposed to 33±2°C from day one till 6 weeks of age. At 42nd day of age, all chicks were subjected to acute heat stress of 39±2°C for 2 h. Blood samples were collected from all groups before and after exposure to acute heat stress. Results: Blood pH increased in both controls and thermally-conditioned chicks after exposure to acute heat stress coinciding with significant decrease in blood carbon dioxide pressure (pCo2 in controls only. Blood potassium level decreased in controls, while in thermally-conditioned or chronically-stressed no significant changes were observed. Blood sodium level showed a trend toward decreased levels in controls while a trend toward increased levels was observed in both thermally-conditioned and chronically-stressed birds. Importantly, significant reductions were observed in total erythrocyte count and hemoglobin level in chronically-stressed birds as compared to other groups before and after acute stress exposure. Hetrophil/lymphocyte ratio increased in both controls and thermally-conditioned chicks after acute heat exposure, but not in chronically-stressed birds. Conclusion: When exposed to acute heat stress at marketing age, chicks subjected to early age thermal conditioning responded very similar to birds adapted to chronic heat stress indicating a protective role of early age thermal conditioning.

  4. Control of Early Age Cracking in Concrete. Phase 4 and 5: Material Modelling, Continuum Approach

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Hansen, Per Freiesleben

    1997-01-01

    This report deals with numerical modelling of early age concrete. The hydration process giving the strength and stiffness development after casting is discussed. Several factors influence the progress of hydration such as the temperature level and the moisture activity. The factors are coupled...... and a material model is proposed which includes some of the couplings. It is shown how more factors may be incorporated. The model is illustrated through analysis of measured creep response both at a varying load history and at a varying temperature history....

  5. Internal curing with lightweight aggregate produced from biomass-derived waste

    Energy Technology Data Exchange (ETDEWEB)

    Lura, Pietro, E-mail: pietro.lura@empa.ch [Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf (Switzerland); Institute for Building Materials (IfB), ETH Zürich (Switzerland); Wyrzykowski, Mateusz [Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf (Switzerland); Department of Building Physics and Building Materials, Lodz University of Technology (Poland); Tang, Clarence [Siam Research and Innovation, SCG Cement–Building Materials, Saraburi (Thailand); Lehmann, Eberhard [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

    2014-05-01

    Shrinkage of concrete may lead to cracking and ultimately to a reduction of the service life of concrete structures. Among known methods for shrinkage mitigation, internal curing with porous aggregates was successfully utilized in the last couple of decades for decreasing autogenous and drying shrinkage. In this paper, the internal curing performance of pre-saturated lightweight aggregates produced from biomass-derived waste (bio-LWA) was studied. In the first part of this paper, the microstructure of the bio-LWA is investigated, with special focus on their pore structure and on their water absorption and desorption behavior. The bio-LWA has large porosity and coarse pore structure, which allows them to release the entrained water at early age and counteract self-desiccation and autogenous shrinkage. In the second part, the efficiency of internal curing in mortars incorporating the bio-LWA is examined by neutron tomography, internal relative humidity and autogenous deformation measurements.

  6. New particle growth and shrinkage observed in subtropical environments

    Directory of Open Access Journals (Sweden)

    L.-H. Young

    2012-07-01

    Full Text Available We present the first systematic analysis for new particle formation (NPF, growth and shrinkage of new particles observed at four different sites in subtropical Central Taiwan. A total of 14 NPF events were identified during 137 days of ambient measurements during a cold and warm season. The derived nucleation rates of 1 nm particles (J1 and growth rates were in the range of 39.6–252.9 cm−3 s−1 and 6.5–14.5 nm h−1, respectively. The NPF events occurred on days either with low condensation sink (CS, increased morning traffic emissions and the breakup of nocturnal inversion layer (type A, or with high CS, minimum levels of primary traffic emissions and enhanced atmospheric dilution (type B. On non-event days, the particle number concentrations were mostly driven by traffic emissions. We have also observed shrinkage of new particles (type A-S and B-S, reversal of growth, during five out of the 14 NPF events. In intense shrinkage cases, the grown particles shrank back to the smallest measurable size of ~10 nm, thereby creating a unique "arch-like" shape in the size distribution contour plot. The particle shrinkage rates ranged from 5.1 to 7.6 nm h−1. The ratios of shrinkage-to-growth rates were mostly in the range of 0.40–0.65, suggesting that a large fraction of the condensable species that contributed to growth were likely semi-volatile. The particle shrinkage was related to air masses with low CS due to atmospheric dilution, high ambient temperature and low relative humidity and such atmospheric conditions may have facilitated the evaporation of semi-volatile species from the particles to the gas phase. Our observations show that the new particle growth may be a~reversible process and the evaporating semi-volatile species are important for the growth of new particles to cloud condensation nuclei sizes.

  7. Influence of particle size of autogenous bone grafts on the early stages of bone regeneration: A histologic and stereologic study in rabbit calvarium

    DEFF Research Database (Denmark)

    Pallesen, L.; Schou, S.; Aaboe, Merete

    2002-01-01

    autogenous bone grafts, bone regeneration, calvarial defects, histology, particle size, particulated bone grafts, rabbits, revascularization, stereology......autogenous bone grafts, bone regeneration, calvarial defects, histology, particle size, particulated bone grafts, rabbits, revascularization, stereology...

  8. Bone-to-implant contact after maxillary sinus floor augmentation with Bio-Oss and autogenous bone in different ratios in mini pigs

    DEFF Research Database (Denmark)

    Jensen, Thomas; Schou, Søren; Gundersen, Hans Jørgen Gottlieb

    2013-01-01

    OBJECTIVES: The objective was to test the hypotheses: (i) no differences in bone-to-implant contact formation, and (ii) no differences between the use of autogenous mandibular or iliac bone grafts, when autogenous bone, Bio-Oss mixed with autogenous bone, or Bio-Oss is used as graft...... for the maxillary sinus floor augmentation. MATERIAL AND METHODS: Bilateral sinus floor augmentation was performed in 40 mini pigs with: (A) 100% autogenous bone, (B) 75% autogenous bone and 25% Bio-Oss, (C) 50% autogenous bone and 50% Bio-Oss, (D) 25% autogenous bone and 75% Bio-Oss, or (E) 100% Bio......-Oss. Autogenous bone was harvested from the iliac crest or the mandible and the graft composition was selected at random and placed concomitant with the implant placement. The animals were euthanized 12 weeks after surgery. Bone-to-implant contact was estimated by stereological methods and summarized as median...

  9. Numerical model predictions of autogenic fluvial terraces and comparison to climate change expectations

    Science.gov (United States)

    Limaye, Ajay B. S.; Lamb, Michael P.

    2016-03-01

    Terraces eroded into sediment (alluvial) and bedrock (strath) preserve an important history of river activity. River terraces are thought to form when a river switches from a period of slow vertical incision and valley widening to fast vertical incision and terrace abandonment. Consequently, terraces are often interpreted to reflect changing external drivers including tectonics, sea level, and climate. In contrast, the intrinsic unsteadiness of lateral migration in rivers may generate terraces even under constant rates of vertical incision without external forcing. To explore this mechanism, we simulate landscape evolution by a vertically incising, meandering river and isolate the age and geometry of autogenic river terraces. Modeled autogenic terraces form for a wide range of lateral and vertical incision rates and are often paired and longitudinally extensive for intermediate ratios of vertical-to-lateral erosion rate. Autogenic terraces have a characteristic reoccurrence time that scales with the time for relief generation. There is a preservation bias against older terraces due to reworking of previously visited parts of the valley. Evolving, spatial differences in bank strength between bedrock and sediment reduce terrace formation frequency and length, favor pairing, and can explain sublinear terrace margins at valley boundaries. Age differences and geometries for modeled autogenic terraces are consistent, in cases, with natural terraces and overlap with metrics commonly attributed to terrace formation due to climate change. We suggest a new phase space of terrace properties that may allow differentiation of autogenic terraces from terraces formed by external drivers.

  10. Brain structural alterations in obsessive-compulsive disorder patients with autogenous and reactive obsessions.

    Directory of Open Access Journals (Sweden)

    Marta Subirà

    Full Text Available Obsessive-compulsive disorder (OCD is a clinically heterogeneous condition. Although structural brain alterations have been consistently reported in OCD, their interaction with particular clinical subtypes deserves further examination. Among other approaches, a two-group classification in patients with autogenous and reactive obsessions has been proposed. The purpose of the present study was to assess, by means of a voxel-based morphometry analysis, the putative brain structural correlates of this classification scheme in OCD patients. Ninety-five OCD patients and 95 healthy controls were recruited. Patients were divided into autogenous (n = 30 and reactive (n = 65 sub-groups. A structural magnetic resonance image was acquired for each participant and pre-processed with SPM8 software to obtain a volume-modulated gray matter map. Whole-brain and voxel-wise comparisons between the study groups were then performed. In comparison to the autogenous group, reactive patients showed larger gray matter volumes in the right Rolandic operculum. When compared to healthy controls, reactive patients showed larger volumes in the putamen (bilaterally, while autogenous patients showed a smaller left anterior temporal lobe. Also in comparison to healthy controls, the right middle temporal gyrus was smaller in both patient subgroups. Our results suggest that autogenous and reactive obsessions depend on partially dissimilar neural substrates. Our findings provide some neurobiological support for this classification scheme and contribute to unraveling the neurobiological basis of clinical heterogeneity in OCD.

  11. Exploiting tumor shrinkage through temporal optimization of radiotherapy

    CERN Document Server

    Unkelbach, Jan; Hong, Theodore; Papp, David; Ramakrishnan, Jagdish; Salari, Ehsan; Wolfgang, John; Bortfeld, Thomas

    2013-01-01

    In multi-stage radiotherapy, a patient is treated in several stages separated by weeks or months. This regimen has been motivated mostly by radiobiological considerations, but also provides an approach to reduce normal tissue dose by exploiting tumor shrinkage. The paper considers the optimal design of multi-stage 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. We introduce a dynamic tumor model that incorporates three factors: radiation induced cell kill, tumor shrinkage, and tumor cell repopulation. The design of multi-stage 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. We analyze treatments consisting ...

  12. Modelling of elastoplastic damage in concrete due to desiccation shrinkage

    Science.gov (United States)

    Bourgeois, F.; Burlion, N.; Shao, J. F.

    2002-07-01

    We present a numerical modelling of elastoplastic damage due to drying shrinkage of concrete in the framework of mechanics of partially saturated porous media. An elastoplastic model coupled with isotropic damage is first formulated. Two plastic flow mechanisms are involved, controlled by applied stress and suction, respectively. A general concept of net effective stress is used in take into account effects of capillary pressure and material damage on stress-controlled plastic deformation. Damage evolution depends both on elastic and plastic strains. The model's parameters are determined or chosen from relevant experimental data. Comparisons between numerical simulations and experimental data are presented to show the capacity of model to reproduce mains features of concrete behaviour under mechanical loading and during drying shrinkage of concrete. An example of application concerning drying of a concrete wall is finally presented. The results obtained allow to show potential capacity of proposed model for numerical modelling of complex coupling processes in concrete structures.

  13. New System of Shrinkage Measurement through Cement Mortars Drying

    Science.gov (United States)

    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

  14. Shrinkage and trajectory of the flat jet with inclination angle

    Institute of Scientific and Technical Information of China (English)

    Shufeng Ye; Yusheng Xie; Hongzhi Guo; Ye Huang; Shantong Jin

    2003-01-01

    The performance of the flat jet with an inclination angle was investigated by a water model. A mathematical model for theshrinkage and the trajectory of the flat jet with an inclination angle was derived theoretically and verified by experimental data of thewater model. The experimental results indicate that the inclination angle (α) has no influence on the shrinkage of the flat jet, theshrinkage of the flat jet along the width direction decreases with the increasing of the initial velocity at the exit (u0) and the initialthickness of the flat jet (t0). Enough bigger initial exit velocity (u0) and initial thickness can suppress the shrinkage of the flat jetalong the width direction and keep the flat jet stabilized. In addition, the trajectory of the flat jet with an inclination angle is parabolicand must be taking into consideration when to determine the striking distance.

  15. Analysis of Shrinkage on Thick Plate Part using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Najihah S.N.

    2016-01-01

    Full Text Available Injection moulding is the most widely used processes in manufacturing plastic products. Since the quality of injection improves plastic parts are mostly influenced by process conditions, the method to determine the optimum process conditions becomes the key to improving the part quality. This paper presents a systematic methodology to analyse the shrinkage of the thick plate part during the injection moulding process. Genetic Algorithm (GA method was proposed to optimise the process parameters that would result in optimal solutions of optimisation goals. Using the GA, the shrinkage of the thick plate part was improved by 39.1% in parallel direction and 17.21% in the normal direction of melt flow.

  16. Reversible cerebral shrinkage in kwashiorkor: an MRI study.

    Science.gov (United States)

    Gunston, G D; Burkimsher, D; Malan, H; Sive, A A

    1992-08-01

    Protein energy malnutrition is associated with cerebral atrophy which may be detrimental to intellectual development. The aim of this study was to document the anatomical abnormalities which lead to the appearance of cerebral atrophy using magnetic resonance imaging (MRI) in the acute stage of kwashiorkor and to monitor changes during nutritional rehabilitation. Twelve children aged 6 to 37 months requiring admission to hospital for the treatment of kwashiorkor were studied. The children were evaluated clinically, biochemically, and by MRI of their brains on admission and 30 and 90 days later. Brain shrinkage was present in every child on admission. White and grey matter appeared equally affected and the myelination was normal for age. At 90 days, the cerebral changes had resolved in nine and improved substantially in the remainder, by which time serum proteins and weight for age were within the normal range. The findings of this study suggest that brain shrinkage associated with kwashiorkor reverses rapidly with nutritional rehabilitation.

  17. Combinatorial Selection and Least Absolute Shrinkage via the CLASH Algorithm

    CERN Document Server

    Kyrillidis, Anastasios

    2012-01-01

    The least absolute shrinkage and selection operator (LASSO) for linear regression exploits the geometric interplay of the $\\ell_2$-data error objective and the $\\ell_1$-norm constraint to arbitrarily select sparse models. Guiding this uninformed selection process with sparsity models has been precisely the center of attention over the last decade in order to improve learning performance. To this end, we alter the selection process of LASSO to explicitly leverage combinatorial sparsity models (CSMs) via the combinatorial selection and least absolute shrinkage (CLASH) operator. We provide concrete guidelines how to leverage combinatorial constraints within CLASH, and characterize CLASH's guarantees as a function of the set restricted isometry constants of the sensing matrix. Finally, our experimental results show that CLASH can outperform both LASSO and model-based compressive sensing in sparse estimation.

  18. Evaluation of Early-Age Concrete Compressive Strength with Ultrasonic Sensors.

    Science.gov (United States)

    Yoon, Hyejin; Kim, Young Jin; Kim, Hee Seok; Kang, Jun Won; Koh, Hyun-Moo

    2017-08-07

    Surface wave velocity measurement of concrete using ultrasonic sensors requires testing on only one side of a member. Thus, it is applicable to concrete cast inside a form and is often used to detect flaws and evaluate the compressive strength of hardened concrete. Predicting the in situ concrete strength at a very early stage inside the form helps with determining the appropriate form removal time and reducing construction time and costs. In this paper, the feasibility of using surface wave velocities to predict the strength of in situ concrete inside the form at a very early stage was evaluated. Ultrasonic sensors were used to measure a series of surface waves for concrete inside a form in the first 24 h after placement. A continuous wavelet transform was used to compute the travel time of the propagating surface waves. The cylindrical compressive strength and penetration resistance tests were also performed during the test period. Four mixtures and five curing temperatures were used for the specimens. The surface wave velocity was confirmed to be applicable to estimating the concrete strength at a very early age in wall-like elements. An empirical formula is proposed for evaluating the early-age compressive strength of concrete considering the 95% prediction intervals.

  19. Research and Application of the Mathematic Model for the Washing Shrinkage of Woven Fabric

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Having analyzed the relationships between washing shrinkage and weaving technique, parameters, material properties of woven fabrics and studied the shrinkage mechanism and its mathematical model of the plain fabric,researchers set up a shrinkage model of the twills and satins and proposed a method for calculating the washing shrinkage based on weaving technique and parameters of fabrics. Shrinkage experiments of silk habotai, silk twill and silk satin fabrics were performed. The results were compared with those of the theoretical computations, and it has been proven that the theoretical method is reliable.

  20. Super-resolution optical telescopes with local light diffraction shrinkage

    OpenAIRE

    Changtao Wang; Dongliang Tang; Yanqin Wang; Zeyu Zhao; Jiong Wang; Mingbo Pu; Yudong Zhang; Wei Yan; Ping Gao; Xiangang Luo

    2015-01-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found ...

  1. The Process of Shrinkage as a Challenge to Urban Governance

    Directory of Open Access Journals (Sweden)

    Stryjakiewicz Tadeusz

    2016-06-01

    Full Text Available For many decades most researchers, planners and local authorities have been focusing almost exclusively on urban growth and its socio-economic and spatial consequences. However, in the current debate concerning the future of cities and regions in Europe the process of their shrinkage starts to attract more attention. In the conditions of a declining population, urban governance is an important challenge for local authorities, being usually much more difficult than during the periods of population growth.

  2. Evaluating plastic shrinkage and permeability of polypropylene fiber reinforced concrete

    Directory of Open Access Journals (Sweden)

    G.M. Sadiqul Islam

    2016-12-01

    Full Text Available Plastic concrete is susceptible to develop cracks due to shrinkage in dry and windy conditions. Addition of fibers could reduce propagation of this crack. On the other hand, permeability determines the durability properties of concrete. This study evaluated strength, plastic shrinkage and permeability (gas and water of concrete incorporating ‘polypropylene’ fiber (aspect ratio 300 in various proportions (viz. 0.10%, 0.15%, 0.2%, 0.25% and 0.3% by volume of concrete. Plane concrete samples were also prepared and tested for reference purpose. Inclusion of 0.1% fiber gave minor reduction (2% in compressive strength while the tensile strength increased by 39% with same fiber content compared to the plain concrete. A significant reduction in crack generation, appearance period of first crack and crack area between plane concrete and fiber reinforced concretes was found. The experimental result with inclusion of 0.1–0.3% fiber in concrete indicated that plastic shrinkage cracks were reduced by 50–99% compared to the plain concrete. For reference concrete (without fiber, test within the high temperature and controlled humidity chamber gave higher crack width than the acceptable limit (3 mm specified by the ACI 224. With the inclusion of 0.1% fiber reduced the crack width down to 1 mm and the trend was continued with the addition of more fibers. However, results showed that with the addition of polypropylene fiber both water and gas permeability coefficient was increased. Therefore, it is concluded that the fiber reinforced concrete would work better for plastic shrinkage susceptible structural elements (flat elements such as slab; however, it requires careful judgement while applying to a water retaining structures.

  3. Polymerization shrinkage of flowable resin-based restorative materials

    OpenAIRE

    Stavridakis, Minos M; Dietschi, Didier; Krejci, Ivo

    2005-01-01

    This study measured the linear polymerization displacement and polymerization forces induced by polymerization shrinkage of a series of flowable resin-based restorative materials. The materials tested were 22 flowable resin-based restorative materials (Admira Flow, Aelite Flow, Aeliteflow LV, Aria, Crystal Essence, Definite Flow, Dyract Flow, Filtek Flow, FloRestore, Flow-it, Flow-Line, Freedom, Glacier, OmegaFlo, PermaFlo, Photo SC, Revolution 2, Star Flow, Synergy Flow, Tetric Flow, Ultrase...

  4. Prediction of Prestressing Losses by Concrete Creep and Shrinkage

    Energy Technology Data Exchange (ETDEWEB)

    Woo, S.K. [Korea Electric Power Research Institute, Taejon (Korea)

    1999-07-01

    In this study, the personal-computer program was developed to predict prestressing losses of containment structures induced by concrete creep and shrinkage in nuclear power plants. Thie program is composed of three major parts in which are the pre-processor, calculation module and post-processor. Input data for this program are: material properties of concrete, rebar, liner and duct, test results of concrete creep and shrinkage, relative humidity, dimension of containment structures, and the number of prestressing tendon related in containment structures. To obtain better results, this program was designed to reflect the prestressing losses due to influence that occurred after prestressing of each tendon, thus it can predict prestressing losses and allowable prestressing forces of each tendon. As a case study, this program was applied to containment structures of Youngkwang 3 and 4 NPP's and analytical results were compared with test results in Inservice Inspection of containment structures. From this comparison, it was proved that this program could well predict prestressing losses by concrete creep and shrinkage. (author). 4 refs., 1 fig., 3 tabs.

  5. PREDIKSI SHRINKAGE UNTUK MENGHINDARI CACAT PRODUK PADA PLASTIC INJECTION

    Directory of Open Access Journals (Sweden)

    Agus Dwi Anggono

    2015-05-01

    Full Text Available Plastic injection merupakan proses manufactur untuk membuat produk dengan bahan dasar plastic atau dalam kesempatan ini polypropylene. Pada proses tersebut seringkali terjadi cacat produk seperti pengerutan, retak, dimensi tidak sesuai dan kerusakan saat produk keluar dari mould, sehingga banyak material yang terbuang percuma. Meskipun cacat produk tersebut dipengaruhi banyak factor, tetapi yang paling utama adalah masalah shrinkage, atau penyusutan material setelah terjadi pendinginan. Sangat penting untuk melakukan prediksi lebih awal terjadinya penyusutan setelah pendinginan untuk menghindari cacat produk. Dalam penelitian ini akan dilakukan prediksi shrinkage yang akan digunakan untuk material polypropylene dengan cara perhitungan standar. Pembuatan modeling dalam bentuk 3D (tiga dimensi injection molding baik cavity maupun corenya dengan menggunakan CATIA, kemudian dilakukan analisis dengan software MoldFlow untuk pembuatan mesh dan memberikan batasan panas pada komponen sehingga dapat diketahui mode penyusutannya. Analisis ini akan memberikan gambaran tentang distribusi panas pada mould dan memberikan tentang gambaran aliran fluida. Pada analisis tersebut dapat dilihat gejala terjadinya cacat produk, jika hal itu terjadi maka perlu dilakukan perubahan shrinkage, sampai diperoleh hasil analisis yang baik.

  6. Controlled Shrinkage of Expanded Glass Particles in Metal Syntactic Foams

    Directory of Open Access Journals (Sweden)

    Kadhim Al-Sahlani

    2017-09-01

    Full Text Available Metal matrix syntactic foams have been fabricated via counter-gravity infiltration of a packed bed of recycled expanded glass particles (EG with A356 aluminum alloy. Particle shrinkage was studied and has been utilized to increase the particles’ strength and tailor the mechanical properties of the expanded glass/metal syntactic foam (EG-MSF. The crushing strength of particles could be doubled by shrinking them for 20 min at 700 °C. Owing to the low density of EG (0.20–0.26 g/cm3, the resulting foam exhibits a low density (1.03–1.19 g/cm3 that increases slightly due to particle shrinkage. Chemical and physical analyses of EG particles and the resulting foams were conducted. Furthermore, metal syntactic foam samples were tested in uni-axial compression tests. The stress-strain curves obtained exhibit three distinct regions: elastic deformation followed by a stress plateau and densification commencing at 70–80% macroscopic strain. Particle shrinkage increased the mechanical strength of the foam samples and their average plateau stress increased from 15.5 MPa to 26.7 MPa.

  7. Controlled Shrinkage of Expanded Glass Particles in Metal Syntactic Foams.

    Science.gov (United States)

    Al-Sahlani, Kadhim; Taherishargh, Mehdi; Kisi, Erich; Fiedler, Thomas

    2017-09-13

    Metal matrix syntactic foams have been fabricated via counter-gravity infiltration of a packed bed of recycled expanded glass particles (EG) with A356 aluminum alloy. Particle shrinkage was studied and has been utilized to increase the particles' strength and tailor the mechanical properties of the expanded glass/metal syntactic foam (EG-MSF). The crushing strength of particles could be doubled by shrinking them for 20 min at 700 °C. Owing to the low density of EG (0.20-0.26 g/cm³), the resulting foam exhibits a low density (1.03-1.19 g/cm³) that increases slightly due to particle shrinkage. Chemical and physical analyses of EG particles and the resulting foams were conducted. Furthermore, metal syntactic foam samples were tested in uni-axial compression tests. The stress-strain curves obtained exhibit three distinct regions: elastic deformation followed by a stress plateau and densification commencing at 70-80% macroscopic strain. Particle shrinkage increased the mechanical strength of the foam samples and their average plateau stress increased from 15.5 MPa to 26.7 MPa.

  8. The physical effects of an intra-aggregate structure on soil shrinkage

    CERN Document Server

    Chertkov, V Y

    2014-01-01

    Clay and soil containing it have shrinkage curves that are qualitatively different in shape. The objective of this work is to qualitatively show with maximum simplicity, how a clay shrinkage curve turns into a soil shrinkage curve. Because of the crack volume the measured shrinkage curve is not the single-valued feature of a soil. We use a concept of the reference shrinkage curve that is only stipulated by soil shrinkage without cracking, single-valued, and qualitatively similar to an observed shrinkage curve. We also use new concepts of an intra-aggregate soil structure: (i) a rigid superficial layer of aggregates that loses water during shrinkage; and (ii) lacunar pores (micro-cracks) inside an intra-aggregate clay that change in volume during shrinkage. Then, through a series of consecutive steps, illustrating each step by a separate graphic presentation, we move from a clay shrinkage curve to a soil shrinkage curve with predicted qualitative features that coincide with those experimentally observed in num...

  9. Evaluation of shrinkage and cracking in concrete of ring test by acoustic emission method

    Science.gov (United States)

    Watanabe, Takeshi; Hashimoto, Chikanori

    2015-03-01

    Drying shrinkage of concrete is one of the typical problems related to reduce durability and defilation of concrete structures. Lime stone, expansive additive and low-heat Portland cement are used to reduce drying shrinkage in Japan. Drying shrinkage is commonly evaluated by methods of measurement for length change of mortar and concrete. In these methods, there is detected strain due to drying shrinkage of free body, although visible cracking does not occur. In this study, the ring test was employed to detect strain and age cracking of concrete. The acoustic emission (AE) method was adopted to detect micro cracking due to shrinkage. It was recognized that in concrete using lime stone, expansive additive and low-heat Portland cement are effective to decrease drying shrinkage and visible cracking. Micro cracking due to shrinkage of this concrete was detected and evaluated by the AE method.

  10. Evaluation of Aquacel Ag for Autogenous Skin Donor Sites.

    Science.gov (United States)

    Haith, Linwood R; Stair-Buchmann, Megan E; Ackerman, Bruce H; Herder, Diane; Reigart, Cynthia L; Stoering, Marla; Guilday, Robert E; Patton, Mary Lou; Ross, Kerry M

    2015-01-01

    An ongoing objective of burn research is to evaluate wound dressings and develop new treatments to expedite wound healing. This was a single-center, prospective, randomized, controlled study to evaluate the effectiveness of Aquacel Ag as a dressing for autogenous skin donor sites compared with Xeroform. We hypothesized that donor sites treated with Aquacel Ag would heal faster. Patients were considered for enrollment if they required skin grafting with two donor sites >100 cm at least 2 inches apart. Dressings were observed daily starting on post-op day #2 until discharge and then weekly in the outpatient burn clinic. Assessments evaluated pain, infection, and reapplication. Photographs were taken on post-op day #2, upon "90% re-epithelialization," and at post-op day #30-45. Scar assessments and blinded photographic reviews were completed to assess cosmetic healing. Twenty-nine patients completed the study. Re-epithelialization occurred faster with Xeroform (15.2 days vs. 17.6 days). Daily pain scores were higher with Xeroform (6.72 vs. 5.68) and Aquacel Ag needed to be replaced more often (1.72 times vs. 0.10 times). Three patients developed donor site infections with Aquacel Ag. Scar scores between the donor sites were not statistically significant. The blinded photo review concluded that Xeroform had a better cosmetic outcome (24 vs. 10%). Although patients complained of more pain with Xeroform, it demonstrated shorter healing times and better cosmetic outcomes. Aquacel Ag needed to be replaced more often and represented the only three donor site infections.

  11. Autogenous regulation of Escherichia coli polynucleotide phosphorylase expression revisited.

    Science.gov (United States)

    Carzaniga, Thomas; Briani, Federica; Zangrossi, Sandro; Merlino, Giuseppe; Marchi, Paolo; Dehò, Gianni

    2009-03-01

    The Escherichia coli polynucleotide phosphorylase (PNPase; encoded by pnp), a phosphorolytic exoribonuclease, posttranscriptionally regulates its own expression at the level of mRNA stability and translation. Its primary transcript is very efficiently processed by RNase III, an endonuclease that makes a staggered double-strand cleavage about in the middle of a long stem-loop in the 5'-untranslated region. The processed pnp mRNA is then rapidly degraded in a PNPase-dependent manner. Two non-mutually exclusive models have been proposed to explain PNPase autogenous regulation. The earlier one suggested that PNPase impedes translation of the RNase III-processed pnp mRNA, thus exposing the transcript to degradative pathways. More recently, this has been replaced by the current model, which maintains that PNPase would simply degrade the promoter proximal small RNA generated by the RNase III endonucleolytic cleavage, thus destroying the double-stranded structure at the 5' end that otherwise stabilizes the pnp mRNA. In our opinion, however, the first model was not completely ruled out. Moreover, the RNA decay pathway acting upon the pnp mRNA after disruption of the 5' double-stranded structure remained to be determined. Here we provide additional support to the current model and show that the RNase III-processed pnp mRNA devoid of the double-stranded structure at its 5' end is not translatable and is degraded by RNase E in a PNPase-independent manner. Thus, the role of PNPase in autoregulation is simply to remove, in concert with RNase III, the 5' fragment of the cleaved structure that both allows translation and prevents the RNase E-mediated PNPase-independent degradation of the pnp transcript.

  12. Autogenous Regulation of Escherichia coli Polynucleotide Phosphorylase Expression Revisited▿ †

    Science.gov (United States)

    Carzaniga, Thomas; Briani, Federica; Zangrossi, Sandro; Merlino, Giuseppe; Marchi, Paolo; Dehò, Gianni

    2009-01-01

    The Escherichia coli polynucleotide phosphorylase (PNPase; encoded by pnp), a phosphorolytic exoribonuclease, posttranscriptionally regulates its own expression at the level of mRNA stability and translation. Its primary transcript is very efficiently processed by RNase III, an endonuclease that makes a staggered double-strand cleavage about in the middle of a long stem-loop in the 5′-untranslated region. The processed pnp mRNA is then rapidly degraded in a PNPase-dependent manner. Two non-mutually exclusive models have been proposed to explain PNPase autogenous regulation. The earlier one suggested that PNPase impedes translation of the RNase III-processed pnp mRNA, thus exposing the transcript to degradative pathways. More recently, this has been replaced by the current model, which maintains that PNPase would simply degrade the promoter proximal small RNA generated by the RNase III endonucleolytic cleavage, thus destroying the double-stranded structure at the 5′ end that otherwise stabilizes the pnp mRNA. In our opinion, however, the first model was not completely ruled out. Moreover, the RNA decay pathway acting upon the pnp mRNA after disruption of the 5′ double-stranded structure remained to be determined. Here we provide additional support to the current model and show that the RNase III-processed pnp mRNA devoid of the double-stranded structure at its 5′ end is not translatable and is degraded by RNase E in a PNPase-independent manner. Thus, the role of PNPase in autoregulation is simply to remove, in concert with RNase III, the 5′ fragment of the cleaved structure that both allows translation and prevents the RNase E-mediated PNPase-independent degradation of the pnp transcript. PMID:19136586

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

    Energy Technology Data Exchange (ETDEWEB)

    Studier, F. William (Stony Brook, NY); Dubendorff, John W. (Sound Beach, NY)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Studier, F. William (Stony Brook, NY); Dubendorff, John W. (Sound Beach, NY)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. The fate of preserved homograft pericardium and autogenous pericardium within the heart

    Science.gov (United States)

    Clarke, C. P.; Barratt-Boyes, B. G.; Sims, F. H.

    1968-01-01

    Animal experiments were performed to assess the usefulness of preserved homograft pericardium for intracardiac surgery, with particular reference to the problem of homograft mitral valve papillary muscle fixation. The fate of fresh autogenous pericardium was also studied. Both homograft and autogenous pericardium were destroyed and replaced by fibrous tissue. This reaction was faster when the pericardium was in direct contact with the blood stream and slower when it was buried within the myocardium. As homograft pericardium provided a more intense fibrous reaction than autogenous pericardium, it was considered to be very suitable for papillary muscle fixation and less suitable for other intracardiac procedures. The technique used for attaching the papillary muscle of a homograft mitral valve is briefly described. Images PMID:5654067

  18. Repair process of surgical defects filled with autogenous bone grafts in tibiae of diabetic rats

    Directory of Open Access Journals (Sweden)

    Jônatas Caldeira Esteves

    2008-10-01

    Full Text Available From a biological standpoint, the best material for reconstruction of bone defects is the autogenous bone graft. However, as tissue healing is affected under diabetic conditions, major changes might take place in the revascularization, incorporation, replacement and remodeling phases of the grafted area. The purpose of this study was to assess the bone healing process in surgical wounds prepared in tibiae of diabetic rats and filled with autogenous bone. Forty male rats (Rattus norvegicus albinus, Wistar were randomly assigned to receive an endovenous injection (penile vein of either citrate buffer solution (Group 1 - control; n=20 or streptozotocin dissolved in citrate buffer solution (35 mg/kg to induce diabetes (Group 2 - diabetic; n=20. After determination of glycemia, the animals were anesthetized and the anterolateral regions of the tibiae of both limbs were shaved, antisepsis was performed and longitudinal incisions were made in each limb. The tibiae were exposed and two 2mm-diameter surgical cavities were prepared: one in the right limb, filled with particulate autogenous bone and the other in the left limb, filled with blood clot. The animals were euthanized at 10 and 30 postoperative days. The anatomic pieces were obtained, submitted to laboratory processing and sections were stained by hematoxylin and eosin and Masson's Trichrome for histomorphologic and histometric analyses. In both groups, the wounds filled with autogenous bone graft showed better results than those filled with blood clot. The control group showed higher new bone formation in wounds filled with autogenous bone graft at 30 days than the diabetic group, but without statistical significance. It may be concluded that, in general, the new bone formation occurred with autogenous graft was quantitatively similar between control and diabetic groups and qualitatively better in the control group.

  19. Autogenic synthesis of SnO{sub 2} materials and their structural, electrochemical, and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Pol, V.G., E-mail: pol@anl.gov [Electrochemical Energy Storage Department, Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Calderon-Moreno, J.M. [Institute of Physical Chemistry Ilie Murgulescu, Romanian Academy, 202 Splaiul Independentei St., Bucharest 060021 (Romania); Thackeray, M.M. [Electrochemical Energy Storage Department, Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)

    2012-12-15

    During autogenic reactions, organometallic precursors are decomposed above their critical temperature within an enclosed chamber at high temperatures and pressures. It has recently been established that such reactions can be used to synthesize carbon-coated metal oxide and metal phosphate nanoparticles. These materials are of interest as electrodes for lithium-ion batteries. In this paper, we report the autogenic fabrication of a carbon-coated SnO{sub 2} product and a carbon-free SnO{sub 2} product after removal of the carbon coating by combustion. The major objectives of the study were to monitor any beneficial effects that carbon-coated electrodes containing a lithium alloying element such as Sn might have in improving the electrical connectivity between electrode particles, which expand and contract significantly on lithiation and delithiation, and their utility in lithium cells. Specifically, we report the compositional, structural and morphological properties, and electrochemical behavior of carbon-coated SnO{sub 2} electrodes. Given the importance of the optical properties of SnO{sub 2}, we also describe the effects of the carbon coating on the optical absorbance and photoluminescence of autogenically-prepared SnO{sub 2} materials. - Graphical abstract: One-step, solvent-free autogenic reactions yield nanosized SnO{sub 2} nanoparticles, uniformly coated and interconnected by 2-4 nm carbon layers, with improved electrochemical performance. Highlights: Black-Right-Pointing-Pointer Distinctive autogenic process synthesized SnO{sub 2} nanoparticles coated with 2-4 nm carbon layers. Black-Right-Pointing-Pointer Carbon coating improved capacity retention and cycling stability of SnO{sub 2} nanoparticles. Black-Right-Pointing-Pointer Carbon coating quenched photoluminescence of SnO{sub 2} component in SnO{sub 2}-C composite. Black-Right-Pointing-Pointer Autogenic approach is extremely versatile, holds promise for designing new nanoarchitectures.

  20. AUTOGENIC TRAINING RELAXATION HELPING POSTPARTUM MOTHERS TO ACHIEVE SUCCESSFUL BREASTFEEDING ON EARLY LACTATION PERIOD

    Directory of Open Access Journals (Sweden)

    Farida Juanita

    2017-04-01

    Full Text Available Introduction: The numbers of breastfeeding failures are mostly caused by mothers` disbelief to themselves. One method that can be done to overcome these problems in accordance with the self-care nursing theory is the autogenic training relaxation. This method teaches mothers to be self-sufficient in building a positive intention and motivation to help the process of breastfeeding. This study aimed to examine the influence of autogenic training relaxation to the effectiveness of breastfeeding and the enhancement of breast milk volume on maternal postpartum. Method: By using an experimental posttest only-non equivalent control group design, 26 samples were taken based on the criteria and divided into two groups by matching technuiqe. autogenic training was given through MP3 Player for 3 weeks. Post-test observation conducted on the third week by home visit. Via Christi Breastfeeding Assessment Tool Jan Riordan modifications used to assess the effectiveness of breastfeeding, and to measure the milk ejection volume, used weighing test using electronic baby scales. Data were analyzed using one-tailed independent t test with α ≤ 0.05. Result: The analysis showed that mothers who did autogenic training relaxation could breastfeed more effectively and had greater average volume of milk ejection than the control group (p = 0.000 and p = 0.001. Discussion: It can be concluded that autogenic relaxation training techniques affect the effectiveness of breastfeeding and breast milk volume. These results can be considered that autogenic training as an intervention in program of support for breastfeeding mothers.

  1. Autogenous tooth transplants for the pediatric dental patient: report of three cases.

    Science.gov (United States)

    Kennedy, David

    2013-01-01

    There are select instances where autogenous tooth transplantation should be considered as part of the overall management of the developing occlusion in the child patient. These circumstances occur when there are missing mandibular premolars in Class II malocclusions with good faces, unevenly distributed agenesis, missing or lost incisors, and ectopic teeth. The purposes of this paper were to educate pediatric dentists about the autogenous tooth transplantation technique, its success, its potential advantages and disadvantages and to report on three cases treated with autogenesis tooth transplantation.

  2. Autogenous vein graft thrombosis following exposure to calcium-free solutions (calcium paradox).

    Science.gov (United States)

    Nozick, J H; Farnsworth, P; Montefusco, C M; Parsonnet, V; Ruigrok, T J; Zimmerman, A N

    1981-01-01

    The morphological and functional effects of calcium-free and calcium-containing solutions on canine jugular vein intima were examined under conditions which closely resemble those techniques currently employed in peripheral vascular and aortocoronary bypass surgery. Veins that had been exposed only to calcium-containing solutions remained patent for the duration of the experimental period. Vein perfusion with a calcium-free solution, however, resulted in disruption of the jugular vein intima once calcium ions were reintroduced. Autogenous as a femoral arterial graft became thrombosed within 60 minutes. It is therefore suggested that vein grafts of autogenous origin be irrigated with calcium-containing solutions to prevent intimal damage and thrombosis.

  3. Reduced frequency of nickel allergy upon oral nickel contact at an early age

    DEFF Research Database (Denmark)

    Van Hoogstraten, I M; Andersen, Klaus Ejner; Von Blomberg, B M

    1991-01-01

    From animal studies we know that oral administration of T-dependent antigens before sensitization effectively induces systemic immune unresponsiveness. Such 'oral tolerance' is persistent, dose-dependent, antigen-specific and presumably T suppressor cell-mediated. Oral tolerance induction could...... the feasibility of oral prevention of undesired T cell-mediated immunity in man. Potentially tolerizing (oral nickel contacts via orthodontic braces) as well as sensitizing (ear piercing) events were studied retrospectively in 2176 patients attending nine European patch test clinics. Patients were interviewed...... by means of a confidential questionnaire. The results show that ear piercing strongly favoured development of nickel ACH. More importantly, patients having had oral contacts with nickel-releasing appliances (dental braces) at an early age, but only if prior to ear piercing, showed a reduced frequency...

  4. Non-linearities in tensile creep of concrete at early age

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars

    1997-01-01

    A meterial model for creep is proposed which takes into consideration some of the couplings in early age concrete. The model is in incremental form and reflect the hydration process where new layers of cement gel are formed in a stress free state. In the present context attention is on non......-linear creep at high stress levels. The parameteres in the model develop in time as a result of hydration. The creep model has been used to analyse the tensile experiments at different stress levels carried out in the HETEK project. The tests were made on dogbone shaped specimen and the test procedure...... is described. Furthermore, compressive creep at high stress levels are fitted....

  5. Effect of Reinforcement on Early-Age Concrete Temperature Stress: Preliminary Experimental Investigation and Analytical Simulation

    Directory of Open Access Journals (Sweden)

    Jianda Xin

    2015-01-01

    Full Text Available For concrete under short-term loading, effect of reinforcement on concrete crack resistance capability is usually negligible; however, recent research results show that extension of this viewpoint to concrete under long-term loading (temperature variation may be unsuitable. In order to investigate this phenomenon, this paper presents the experimental and analytical results of early-age reinforced concrete temperature stress development under uniaxial restraint. The experiments were carried out on a temperature stress testing machine (TSTM. Experimental results show that the coupling of reinforcement and concrete creep behavior influenced the concrete temperature stress development, and nearly 16% of concrete stress was reduced in the current research. Moreover, the cracking time of reinforced concrete was also delayed. Finally, based on the principle of superposition, analytical simulations of effect of reinforcement on concrete temperature stress have been performed.

  6. Mix design of concrete with high content of mineral additions: Optimisation to improve early age strength

    Energy Technology Data Exchange (ETDEWEB)

    M.I.A. Khokhar; E. Roziere; P. Turcry; F. Grondin; A. Loukili [Institut de Recherche en Genie Civil et Mecanique (GeM), Nantes (France)

    2010-05-15

    The concrete industry is an important source of CO{sub 2} gas emissions. The cement used in the design of concrete is the result of a chemical process linked to the decarbonation of limestone conducted at high temperature and results in a significant release of carbon dioxide. Under the project EcoBeton (Green concrete) funded by the French National Research Agency (ANR), concrete mixtures have been designed with a low cement quantity, by replacing cement by mineral additions i.e., blast-furnace slag, fly ash or limestone fillers. Replacement of cement by other materials at high percentages generally lowers the early age strength of the resulting concrete. To cope with this problem, an optimisation method for mix design of concrete using Bolomey's law has been used. Following the encouraging results obtained from mortar, a series of tests on concretes with various substitution percentages were carried out to validate the optimisation method.

  7. Apparent Activation Energy of Concrete in Early Age Determined by Adiabatic Test

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The apparent activation energy of concrete in early age was determined by adiabatic temperature rise test with different initial temperatures. The influence of mineral admixtures such as fly ash, slag and silica fume on the apparent activation energy of concrete was investigated. The equivalent age that expresses the maturity of concrete was calculated to evaluate the cracking risk of concrete in structures. The results reveal that a substitution of 20% fly ash for Portland cement obviously decreases the apparent activation energy of concrete, however, a substitution of 10% silica fume for Portland cement increases the apparent activation. Finite element method analysis of a simulating concrete wall shows that the concrete containing 20% fly ash has the lowest cracking risk.

  8. Influence of sodium borate on the early age hydration of calcium sulfoaluminate cement

    Energy Technology Data Exchange (ETDEWEB)

    Champenois, Jean-Baptiste; Dhoury, Mélanie [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze Cedex (France); Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze Cedex (France); Mercier, Cyrille [LMCPA, Université de Valenciennes et du Hainaut Cambrésis, 59600 Maubeuge (France); Revel, Bertrand [Centre Commun de Mesure RMN, Université Lille1 Sciences Technologies, Cité Scientifique, 59655 Villeneuve d' Ascq Cedex (France); Le Bescop, Patrick [CEA, DEN, DPC, SECR, F-91192 Gif-sur-Yvette (France); Damidot, Denis [Ecole des Mines de Douai, LGCgE-GCE, 59508 Douai (France)

    2015-04-15

    Calcium sulfoaluminate (CSA) cements are potential candidates for the conditioning of radioactive wastes with high sodium borate concentrations. This work thus investigates early age hydration of two CSA cements with different gypsum contents (0 to 20%) as a function of the mixing solution composition (borate and NaOH concentrations). Gypsum plays a key role in controlling the reactivity of cement. When the mixing solution is pure water, increasing the gypsum concentration accelerates cement hydration. However, the reverse is observed when the mixing solution contains sodium borate. Until gypsum exhaustion, the pore solution pH remains constant at ~ 10.8, and a poorly crystallized borate compound (ulexite) precipitates. A correlation is established between this transient precipitation and the hydration delay. Decreasing the gypsum content in the binder, or increasing the sodium content in the mixing solution, are two ways of reducing the stability of ulexite, thus decreasing the hydration delay.

  9. The impact of early age at first childbirth on maternal and infant health.

    Science.gov (United States)

    Gibbs, Cassandra M; Wendt, Amanda; Peters, Stacey; Hogue, Carol J

    2012-07-01

    The objective of this review was to assess whether early age at first childbirth is associated with increased risk of poor pregnancy outcomes. Early age at childbirth is variously defined in studies of its effect on maternal and infant health. In this systematic review, we limit analysis to studies of at least moderate quality that examine first births among young mothers, where young maternal age is defined as low gynaecological age (≤ 2 years since menarche) or as a chronological age ≤ 16 years at conception or delivery. We conduct meta-analyses for specific maternal or infant health outcomes when there are at least three moderate quality studies that define the exposure and outcome in a similar manner and provide odds ratios or risk ratios as their effect estimates. We conclude that the overall evidence of effect for very young maternal age (effect or precision but not to change the conclusion. Evidence points to an impact of young maternal age on low birthweight and preterm birth, which may mediate other infant outcomes such as neonatal mortality. The evidence that young maternal age increases risk for maternal anaemia is also fairly strong, although information on other nutritional outcomes and maternal morbidity/mortality is less clear. Many of the differences observed among older teenagers with respect to infant outcomes may be because of socio-economic or behavioural differences, although these may vary by country/setting. Future, high quality observational studies in low income settings are recommended in order to address the question of generalisability of evidence. In particular, studies in low income countries need to consider low gynaecological age, rather than simply chronological age, as an exposure. As well, country-specific studies should measure the minimum age at which childbearing for teens has similar associations with health as childbearing for adults. This 'tipping point' may vary by the underlying physical and nutritional health of girls

  10. Dietary habits of Mongolian people, and their influence on lifestyle-related diseases and early aging.

    Science.gov (United States)

    Komatsu, Fumio; Kagawa, Yasuo; Kawabata, Terue; Kaneko, Yoshinori; Purvee, Baatar; Otgon, Jugder; Chimedregzen, Ulziiburen

    2008-07-01

    Mongolians are known to have relatively short life expectancy. In order to examine the role of dietary habits in the early aging of Mongolians, the food intake inquiry, anthropometric measurements and blood clinical tests were performed for 365 healthy inhabitants in Murun, a northern Mongolia city, and compared to those of Japanese. Murun inhibitants were found to have a characteristic dietary habit of taking large amounts of meat, milk, dairy products and wheat flour products, in contrast little vegetables, fruits and fishes. The daily calorie intake of the adults was estimated to be 2,525 kcal, and the fat/total calorie ratio was calculated 33.7%, about 1.3-fold higher than that of Japanese. The intake ratio of fatty acid from the Mongolian foods, saturated : mono-unsaturated : poly-unsaturated fatty acids (PUFA) ratio, was 10.3 : 7.8 : 3.0. Results of blood clinical tests showed significantly higher levels of serum triglycerides, low-density lipoprotein cholesterol (LDL) and homocysteine, and lower levels of high-density lipoprotein cholesterol (HDL), n-3 PUFA, folic acid and adiponectin, in comparison with those of Japanese. In addition, the Mongolians were also found to have significantly high levels of oxidative stress markers, such as serum malondialdehyde-modified LDL (MDA-LDL), urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and serum reactive oxygen metabolites (ROM). The serum ROM level in the Mongolians seemed to associate with their body fat ratio (pObesity was observed at a high incidence in the subjects over 30-year old, and over 40-year old their handgrip ability was markedly decreased. These findings suggest that in the Mongolians the dietary habits associate with their lifestyle-related diseases and early aging, and the improvement of dietary habits is an effective strategy for health promotion of the inhabitants.

  11. CONCEPT OF LIFE QUALITY OF FAMILIES WITH EARLY AGE CHILD WITH ENDANGERED DEVELOPMENT DUE TO DISABILITY

    Directory of Open Access Journals (Sweden)

    Šándorová Zdenka

    2014-05-01

    Full Text Available In the Czech Republic, there is a trend nowadays in supporting families caring for a child vulnerable due to disability. A network of services offering support to these families is growing. Causes of this fact can be found at three different levels, on the child and family side, but also at the support system. Concept of a life quality, and it´s various dimensions for this target group, have been neglected until recently. Present time, however, introduces significant changes in an approach to this issue and the concept of life quality in general is getting to the fore within the interagency scope and the social policy. In this particular case it presents a complex construct comprising many subunits. We can look at them from a variety of perspectives and operate with them in many different ways. This paper solves a view at this concept unusually at the background of the specific activities of Early Care Centre in Pardubice. For the paper processing qualitative research strategies have been used – description of organization´s material and quantitative survey (evaluation questionnaire for the year 2012. Particular aim of this paper is to describe activities of Early Care Centre in Pardubice which affect the concept of life quality of families with child (early age vulnerable due to disability. Results analysis of the evaluation survey which is aimed to identify some of quality indicators of service provided in 2012 also at the Centre for Early Intervention in Pardubice and comparison with the material of the National Centre of social services transformation support - A system of services for children and young people with disabilities and their families (Bačáková, 2013. Results evaluate the life quality concept for families with children in early age with the endangered development due to disability from the position of the family, support and assistance provider and support and assistance evaluator. The conclusion summarizes the problem

  12. Effect of modulated photo-activation on polymerization shrinkage behavior of dental restorative resin composites.

    Science.gov (United States)

    Tauböck, Tobias T; Feilzer, Albert J; Buchalla, Wolfgang; Kleverlaan, Cornelis J; Krejci, Ivo; Attin, Thomas

    2014-08-01

    This study investigated the influence of modulated photo-activation on axial polymerization shrinkage, shrinkage force, and hardening of light- and dual-curing resin-based composites. Three light-curing resin composites (SDR bulk-fill, Esthet X flow, and Esthet X HD) and one dual-curing material (Rebilda DC) were subjected to different irradiation protocols with identical energy density (27 J cm(-2) ): high-intensity continuous light (HIC), low-intensity continuous light (LIC), soft-start (SS), and pulse-delay curing (PD). Axial shrinkage and shrinkage force of 1.5-mm-thick specimens were recorded in real time for 15 min using custom-made devices. Knoop hardness was determined at the end of the observation period. Statistical analysis revealed no significant differences among the curing protocols for both Knoop hardness and axial shrinkage, irrespective of the composite material. Pulse-delay curing generated the significantly lowest shrinkage forces within the three light-curing materials SDR bulk-fill, Esthet X flow, and Esthet X HD. High-intensity continuous light created the significantly highest shrinkage forces within Esthet X HD and Rebilda DC, and caused significantly higher forces than LIC within Esthet X flow. In conclusion, both the composite material and the applied curing protocol control shrinkage force formation. Pulse-delay curing decreases shrinkage forces compared with high-intensity continuous irradiation without affecting hardening and axial polymerization shrinkage. © 2014 Eur J Oral Sci.

  13. Postoperative sensitivity associated with low shrinkage versus conventional composites

    Directory of Open Access Journals (Sweden)

    Ivanović Vladimir

    2013-01-01

    Full Text Available Introduction. Postoperative sensitivity in restorative dentistry can be related to preparation trauma, dentin adhesives’ ability to seal open dentinal tubules, deformation of restorations under occlusal stresses and microleakage. Objective. The study assessed possible reduction in postoperative sensitivity with low shrinkage compared to conventional composites using different bonding agents and the influence of the operator skill on the incidence of postoperative sensitivity. Methods. Nine hundred and sixty permanent premolars and molars with primary carious lesions from patients 21 to 40 years old were used. Cavities 2 to 3 mm deep and with margins in enamel were prepared by four operators. Two operators had five years (A and B and two had over 20 years (C and D of clinical experience. Teeth were divided into eight groups each contained 120 restorations: (1 Els®+James-2 (original formula, (2 Els®+James-2 (new formula, (3 Els®+Excite, (4 InTenSe®+James-2 (original formula, (5 InTenSe®+James-2 (new formula, (6 InTenSe®+Excite, (7 Tetric Ceram®+Excite, and (8 Point 4®+OptiBond Solo Plus. At 14 days postoperatively, two independent operators, who did not take part in the clinical procedure, assessed postoperative teeth sensitivity using special questionnaires. Data were analyzed using non-parametric chi-square, Mann-Whitney and ANOVA tests. Results. Group 8 showed significantly higher score than the other groups. Less postoperative sensitivity was reported with two low-shrinkage composites (groups 2, 3, and 5 but with no significant difference. There was no statistical difference between groups 1, 2, 3, 4, 5, 6 and 7. Operator A had the highest postoperative sensitivity score compared to the other three. Conclusion. Conventional composite material Point 4® with its bonding agent caused significantly more postoperative sensitivity than low shrinkage composites combined with different adhesives. Operator skill influenced the incidence of

  14. Sonar target enhancement by shrinkage of incoherent wavelet coefficients.

    Science.gov (United States)

    Hunter, Alan J; van Vossen, Robbert

    2014-01-01

    Background reverberation can obscure useful features of the target echo response in broadband low-frequency sonar images, adversely affecting detection and classification performance. This paper describes a resolution and phase-preserving means of separating the target response from the background reverberation noise using a coherence-based wavelet shrinkage method proposed recently for de-noising magnetic resonance images. The algorithm weights the image wavelet coefficients in proportion to their coherence between different looks under the assumption that the target response is more coherent than the background. The algorithm is demonstrated successfully on experimental synthetic aperture sonar data from a broadband low-frequency sonar developed for buried object detection.

  15. Sparse electromagnetic imaging using nonlinear iterative shrinkage thresholding

    KAUST Repository

    Desmal, Abdulla

    2015-04-13

    A sparse nonlinear electromagnetic imaging scheme is proposed for reconstructing dielectric contrast of investigation domains from measured fields. The proposed approach constructs the optimization problem by introducing the sparsity constraint to the data misfit between the scattered fields expressed as a nonlinear function of the contrast and the measured fields and solves it using the nonlinear iterative shrinkage thresholding algorithm. The thresholding is applied to the result of every nonlinear Landweber iteration to enforce the sparsity constraint. Numerical results demonstrate the accuracy and efficiency of the proposed method in reconstructing sparse dielectric profiles.

  16. Photoelastic study of shrinkage fitted components for a gasturbine engine

    Science.gov (United States)

    Govindaraju, T. V.; Maheshappa, H.; Govindaraju, N.; Gargesa, G.

    A 3D photoelastic model of shrink-fitted components of a gas turbine engine such as low-pressure main shaft and compressor adopter shaft (or hub) are used to perform a photo-elastic investigation of shrink-fitted components for different relative thickness ratio and different contact length ratio. The relative rigidity of the hub is found to increase as the relative thickness ratio increases, and the relative rigidity is found to increase as the contact length ratio decreases. An optimization of the geometry of the shrinkage-fitted components is also obtained.

  17. Shrinkage calibration method for μPIM manufactured parts

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Tosello, Guido; Salaga, J.

    2016-01-01

    Five green and five sintered parts of a micro mechanical component, produced by micro powder injection moulding, were measured using an optical coordinate measuring machine. The aim was to establish a method for quality assurance of the final produced parts. Initially, the so called “green” parts...... was evaluated propagating the expanded uncertainty previously stated and considering green and sintered parts correlated. Results showed that the proposed method can be effective instating tolerances if it is assumed that the variability on the dimensions induced by the shrinkage equals the propagated expanded...

  18. Distinguishing allogenic from autogenic causes of bed elevation change in late Quaternary alluvial stratigraphic records

    Science.gov (United States)

    Daniels, J. Michael

    2008-10-01

    Allogenic and autogenic mechanisms both cause changes in the bed elevation of rivers and thereby influence the characteristics of alluvial stratigraphic records (ASRs). Allogenic forcing mechanisms can be grouped into five categories whose relative influence varies with timescale: climate, tectonism, base level, land use/land cover and direct human modification of channels. Late Quaternary ASRs are influenced by the greatest range of allogenic forcing variables with climate among the most important. Autogenic mechanisms of bed elevation change are ubiquitous throughout fluvial systems and are always time-transgressive. Autogenic bed elevation change propagates through drainage networks at predictable rates and results in a time-space envelope within which its effects are capable of operating. ASRs that can be correlated over geographical areas large enough and time intervals small enough to exist outside this envelope most likely result from allogenic forcing. This formulation represents a quantitative and geographic set of threshold criteria for distinguishing between autogenic and allogenic mechanisms. Over late Quaternary timescales (10 2 to 10 5 years) in tectonically stable regions climate change is the dominant allogenic mechanism and, therefore, the first-order control on the morphology, sedimentology, pedologic characteristics and chronology of alluvial stratigraphic records that meet or exceed the threshold criteria for demonstrating allogenic causality.

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

    Directory of Open Access Journals (Sweden)

    Anton Kushnaryov

    2014-01-01

    Full Text Available Objectives. (1 Evaluate safety of autogenous engineered septal neocartilage grafts and (2 compare properties of implanted grafts versus controls. Study Design. Prospective, basic science. Setting. Research laboratory. Methods. Constructs were fabricated from septal cartilage 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 constructs were evaluated. Results. No serious complications were observed. Implanted constructs contained more DNA (P<0.01 and less sGAG perDNA (P<0.05 when compared with in vitro controls. Confined compressive aggregate moduli were also higher in implanted constructs (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 observe. Conclusion. 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 higher in implanted constructs. Implanted constructs displayed resorption rates similar to previously published studies using autogenous implants of native cartilage.

  20. Osteogenesis and ototoxicity of a novel preparation of autogenous bone cement: implications for mastoid obliteration.

    Science.gov (United States)

    Zou, Wenting; Chen, Xihui

    2014-12-01

    To study the osteogenesis and ototoxicity of autogenous bone cement. A randomized, prospective, controlled animal study. University laboratory. We created a critical defect on the bulla wall of guinea pigs. Fifty-three guinea pigs were divided into 3 groups. The defects were filled with autogenous bone cement (ABC) or autogenous bone dust (ABD) on the left side while the contralateral sides were kept intact as the blank control (BC) group or a defect was induced without obliteration as the operation control (OC) group (groups 1 and 2, n = 25 each). The animals were sacrificed at 2, 4, 8, and 12 weeks postoperatively. Group 3 (n = 3) was the ototoxicity positive control (OPC) group. The critical defects were evaluated for bone repair by histologic observation and computed tomography (CT), and the ototoxicity of the material was assessed by measuring shifts in the hearing threshold and changes in cochlear morphology. Antibiotic susceptibility testing of the material was also performed. Histologic observation and CT scans revealed complete bone repair in the ABC group at 12 weeks postoperatively, but progress was slower in the ABD group. The hearing threshold and cochlear morphology did not differ significantly between the preoperative and 12-week postoperative measurement. Autogenous bone dust inhibited some of the bacterial species commonly associated with chronic suppurative otitis media. Animals treated with ABC exhibited osteogenesis, with no ototoxicity and bacteriostasis compared with the use of ABD. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.

  1. Acromioclavicular Reconstruction using Autogenous Semitendinosus Tendon Graft and the Importance of Postoperative Rehabilitation: A Case Report

    Directory of Open Access Journals (Sweden)

    Jade PY Ho

    2013-11-01

    Full Text Available We present a case of chronic acromioclavicular joint dislocation (Rockwood type 5 in which the choice of acromioclavicular reconstruction using autogenous semitendinosus tendon graft was made due to its superiority in anatomical reconstruction of the coracoclavicular ligaments, and the impact of postoperative rehabilitation on the recovery of this patient. We also discuss the rationale behind this.

  2. Clinical evaluation of ridge augmentation using autogenous tooth bone graft material: case series study.

    Science.gov (United States)

    Lee, Ji-Young; Kim, Young-Kyun; Yi, Yang-Jin; Choi, Joon-Ho

    2013-08-01

    Interest in bone graft material has increased with regard to restoration in cases of bone defect around the implant. Autogenous tooth bone graft material was developed and commercialized in 2008. In this study, we evaluated the results of vertical and horizontal ridge augmentation with autogenous tooth bone graft material. This study targeted patients who had vertical or horizontal ridge augmentation using AutoBT from March 2009 to April 2010. We evaluated the age and gender of the subject patients, implant stability, adjunctive surgery, additional bone graft material and barrier membrane, post-operative complication, implant survival rate, and crestal bone loss. We performed vertical and horizontal ridge augmentation using powder- or block-type autogenous tooth bone graft material, and implant placement was performed on nine patients (male: 7, female: 2). The average age of patients was 49.88±12.98 years, and the post-operative follow-up period was 35±5.31 months. Post-operative complications included wound dehiscence (one case), hematoma (one case), and implant osseointegration failure (one case; survival rate: 96%); however, there were no complications related to bone graft material, such as infection. Average marginal bone loss after one-year loading was 0.12±0.19 mm. Therefore, excellent clinical results can be said to have been obtained. Excellent clinical results can be said to have been obtained with vertical and horizontal ridge augmentation using autogenous tooth bone graft material.

  3. Starch hydrolysis in autogenerative high pressure digestion: Gelatinisation and saccharification as rate limiting steps

    NARCIS (Netherlands)

    Lindeboom, R.E.F.; Ding, L.; Weijma, J.; Plugge, C.M.; Lier, van J.B.

    2014-01-01

    Autogenerative high pressure digestion (AHPD) provides an integrated biogas upgrading technology, capable of producing biogas with a CH4 content exceeding 95% at pressures up to 90 bar. Hydrolysis is generally regarded as the rate-limiting step in the anaerobic digestion of complex organic matter, g

  4. Guided bone regeneration using autogenous tooth bone graft in implant therapy: case series.

    Science.gov (United States)

    Kim, Young-Kyun; Kim, Su-Gwan; Bae, Ji-Hyun; Um, In-Woong; Oh, Ji-Su; Jeong, Kyung-In

    2014-04-01

    Recently, techniques have been reported that involve the preparation of extracted teeth from patients used as particulated bone graft materials for bone graft purposes. For implant placement and bone graft, autogenous teeth bone graft materials were used in 15 patients, and clinically excellent results were obtained. In histological examination, favorable bony healing by osteoconduction was observed.

  5. Neural progenitor cells from human induced pluripotent stem cells generated less autogenous immune response.

    Science.gov (United States)

    Huang, Ke; Liu, PengFei; Li, Xiang; Chen, ShuBin; Wang, LiHui; Qin, Li; Su, ZhengHui; Huang, WenHao; Liu, Juli; Jia, Bei; Liu, Jie; Cai, JingLei; Pei, DuanQing; Pan, GuangJin

    2014-02-01

    The breakthrough development of induced pluripotent stem cells (iPSCs) raises the prospect of patient-specific treatment for many diseases through the replacement of affected cells. However, whether iPSC-derived functional cell lineages generate a deleterious immune response upon auto-transplantation remains unclear. In this study, we differentiated five human iPSC lines from skin fibroblasts and urine cells into neural progenitor cells (NPCs) and analyzed their immunogenicity. Through co-culture with autogenous peripheral blood mononuclear cells (PBMCs), we showed that both somatic cells and iPSC-derived NPCs do not stimulate significant autogenous PBMC proliferation. However, a significant immune reaction was detected when these cells were co-cultured with allogenous PBMCs. Furthermore, no significant expression of perforin or granzyme B was detected following stimulation of autogenous immune effector cells (CD3(+)CD8(-) T cells, CD3(+)CD8(+) T cells or CD3(-)CD56(+) NK cells) by NPCs in both PBMC and T cell co-culture systems. These results suggest that human iPSC-derived NPCs may not initiate an immune response in autogenous transplants, and thus set a base for further preclinical evaluation of human iPSCs.

  6. Patient-related factors influencing patency of autogenous brachiocephalic haemodialysis fistulas

    NARCIS (Netherlands)

    Lamprou, Alexander A.; de Bruin, Cor; van Roon, Arie; Loonstra, Jan; van der Laan, Maarten; Tielliu, Ignace; Zeebregts, Clark

    2017-01-01

    Objective: The objective of this study was to analyse the outcome of autogenous brachiocephalic fistula for dialysis purposes and to determine modifiable and non-modifiable patient-related factors of influence on the patency of a newly created fistula. Design of study: A single-centre retrospective

  7. Augmentation of localized defects of the anterior maxillary ridge with autogenous bone before insertion of implants

    NARCIS (Netherlands)

    Raghoebar, GM; Batenburg, RHK; Vissink, A; Reintsema, H

    1996-01-01

    Purpose: This study evaluated the applicability of intraorally harvested autogenous bone grafts for the augmentation of the narrow maxillary alveolar ridge to enable insertion of implants for single tooth replacement. Materials and Methods: Local defects of the anterior maxilla were reconstructed in

  8. Shrinkage and cracking behavior of high performance concretes containing chemical admixtures

    Institute of Scientific and Technical Information of China (English)

    亓萌; 李宗津; 马保国

    2002-01-01

    Modern concretes often incorporate several chemical admixtures to alter the properties of fresh or hardened concrete. In this work, the influences of three types of chemical admixtures, calcium nitrite inhibitor (CNI), retarder (D-17) and superplasticizer (W-19) on free shrinkage and restrained shrinkage cracking of high performance concrete were experimentally investigated. The test results showed that, with the same water to binder ratio (0.4), mixtures containing D-17 of 0.25 percent or higher ratio of W-19 (2.76 percent) all exhibited a reduction in free shrinkage and shrinkage cracking width. However, the incorporations of various ratios of CNI into mixtures led to an increase in free shrinkage and shrinkage cracking width as compared to control mixture. In order to study the influence of CNI, the microstructure of concrete mixture containing CNI were investigated by Mercury Intrusion Porosimetry as well as Scanning Electronic Microscopy(SEM) technique.

  9. Shrinkage and microstructural development during drying of organically modified silica xerogels

    Energy Technology Data Exchange (ETDEWEB)

    Raman, N.K. [New Mexico Univ., Albuquerque, NM (United States); Wallace, S. [Nanopore Corp., Albuquerque, NM (United States); Brinker, C.J. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States)

    1996-07-01

    We have studied the different driving forces behind syneresis in MTES/TEOS gels by aging them in different H{sub 2}O/EtOH pore fluids. We show using shrinkage, density, contact angle, and N{sub 2} sorption measurements, the influence of gel/solvent interactions on the microstructural evolution during drying. Competing effects of syneresis (that occurs during aging) and drying shrinkage resulted in the overall linear shrinkage of the organically modified gels to be constant at {approximately}50%. Increasing the hydrophobicity of the gels caused the driving force for syneresis to change from primarily condensation reactions to a combination of condensation and solid/liquid interfacial energy. In addition the condensation driven shrinkage was observed to be irreversible, whereas the interfacial free energy driven shrinkage was observed to be partially reversible. Nitrogen sorption experiments show that xerogels with the same overall extent of shrinkage can have vastly different microstructures due to the effects of microphase separation.

  10. Effect of metakaolin on drying shrinkage behaviour of cement pastes%偏高岭土对硅酸盐水泥浆体干燥收缩的影响

    Institute of Scientific and Technical Information of China (English)

    罗旌旺; 卢都友; 许涛

    2012-01-01

    为探究偏高岭土(MK)影响水泥基材料干燥收缩机制,研究不同MK掺量、不同成熟度硅酸盐水泥浆体在20℃、55%湿度下的干燥收缩和质量损失,并采用压汞法(MIP)研究不同成熟度水泥浆体的孔结构.结果表明:MK对浆体干燥收缩行为的影响与掺量和浆体成熟度密切相关;虽然MK使不同成熟度水泥浆体长期(28 d以上)干缩均减小,掺量越大,干缩越小,但对早期干缩的影响则存在差异.MK使预养护3d的浆体早期干缩略有增大,而预养护28d则相反.MK对浆体的干燥收缩与质量损失的影响有明显的一致对应关系,浆体质量损失越大,则收缩越明显.MK通过微填充效应、晶核效应和火山灰效应使不同成熟度浆体孔隙率下降、孔径细化,导致浆体在干燥条件下蒸发失水减少、过程减缓,从而减小浆体干燥收缩.%For exploring the mechanism of the effect of metakaolin ( MK) on drying shrinkage of eementi-tous materials, the drying shrinkage and weight loss of blended cement pastes with various replacement levels of MK and different maturities, were studied by being dried at 20 ℃ ,55% RH. The pore structure of cement pastes was measured by mercury intrusion porosimetry ( MIP). Results showed that the effect of MK on drying shrinkage of cement pastes was closely related to the MK content and maturity of cement paste. The long-term drying shrinkage of cement pastes with different maturities decreased with the increasing MK contents. The early age drying shrinkage of the paste pre-cured increased with MK for 3 d, while the early age shrinkage of the paste procured decreased for 28 d. The effect of MK on the mass loss of paste agreed well with its effect on drying shrinkage, the higher the mass loss, the larger the shrinkage. The decrease of drying shrinkage of blended cement paste with MK was due to the less and slower e-vaporation of water in the paste with lower porosity and refined pore structure

  11. Collapse-type shrinkage characteristics in plantation-grown eucalypts: I . Correlations of basic density and some structural indices with shrinkage and collapse properties

    Institute of Scientific and Technical Information of China (English)

    WUYi-qiang; HAYASHIKazuo; LIUYuan; CAIYing-chun; SUGIMORIMasatoshi; LUOJian-ju

    2005-01-01

    Collapse-type shrinkage is one of highly refractory drying defects in low-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD), microfibril angle (MFA), double fibre cell wall thickness (DWT), proportion of ray parenchyma (RP), unit cell wall shrinkage, total shrinkage and residual collapse, which are associated with collapse-type shrinkage characteristics, were investigated by using simple regression method for three species of collapse-susceptible Eucalyptus urophyll, E. grandis and E.urophyllaxE.grandis, planted at Dong-Men Forest Farm in Guangxi autonomous region, China. The results indicated that : unit cell wall shrinkage had a extremely strong positive correlation with BD, moderately strong positive correlation with DWT, and a weakly or moderately negative correlation with RP and MFA; total shrinkage was positively correlated with BD, DWT and RP and negatively related to MFA, but not able to be predicted ideally by any examined factors alone owing to lower R2 value (R2≤0.5712); residual collapse was negatively correlated with BD and DWT, linearly positively correlated with MFA, and had strongly positive linear correlation with RP. It is concluded that BD can be used as single factor (R2≥0.9412) to predicate unit cell wall shrinkage and RP is the relatively sound indicator for predicting residual collapse

  12. Shrinkage strain – Rates study of dental composites based on (BisGMA/TEGDMA monomers

    Directory of Open Access Journals (Sweden)

    A. Amirouche-Korichi

    2017-02-01

    The results revealed that the fraction of opaque filler had no significant effect on the shrinkage strain-rate and on the time at maximum shrinkage strain-rate but these two parameters are closely related to the monomer ratios and viscosity of the organic matrix. The results have confirmed the proportionality of the shrinkage strain and DC and showed that the filler contents and monomer ratios would not affect this proportionality.

  13. Nondestructive Wireless Monitoring of Early-Age Concrete Strength Gain Using an Innovative Electromechanical Impedance Sensing System

    Directory of Open Access Journals (Sweden)

    C. P. Providakis

    2013-01-01

    Full Text Available Monitoring the concrete early-age strength gain at any arbitrary time from a few minutes to a few hours after mixing is crucial for operations such as removal of frameworks, prestress, or cracking control. This paper presents the development and evaluation of a potential active wireless USB sensing tool that consists of a miniaturized electromechanical impedance measuring chip and a reusable piezoelectric transducer appropriately installed in a Teflon-based enclosure to monitor the concrete strength development at early ages and initial hydration states. In this study, the changes of the measured electromechanical impedance signatures as obtained by using the proposed sensing system during the whole early-age concrete hydration process are experimentally investigated. It is found that the proposed electromechanical impedance (EMI sensing system associated with a properly defined statistical index which evaluates the rate of concrete strength development is very sensitive to the strength gain of concrete structures from their earliest stages.

  14. Effect of Cement Type on Autogenous Deformation of Cement-Based Materials

    DEFF Research Database (Denmark)

    Pietro, Lura; Ye, Guang; van Breugel, Klaas

    2004-01-01

    (BFS) cement pastes. Self-desiccation shrinkage of the BFS cement paste was modeled based on the RH measurements, following the capillary-tension approach. The main findings of this study are: 1) self-desiccation shrinkage can be related to self-desiccation both for Portland and for BFS cement pastes......, taking into account the influence of the dissolved salts in the pore solution, 2) the BFS cement paste studied shows pronounced self-desiccation and self-desiccation shrinkage, mainly caused by its very fine pore structure....

  15. Joint functional disability in children of early age with olygoarticular juvenile arthritis

    Directory of Open Access Journals (Sweden)

    T A Shelepina

    2008-01-01

    Full Text Available Objective. To study functional status, character of functional disturbances and possibilities of their correction in children of early age with juvenile arthritis (JA. Material and methods. 42 pts with oligoarticular (at presentation variant of JA with onset before 4 years of age admitted to pediatric department of the Institute of rheumatology of RAMS were included. Mean age of children at the disease onset was 22,4+10 months (from 9 to 46 months, mean disease duration at the first hospitalization — 9,5±5,5 months. Functional status and daily activities limitations (decrease of moving capacity and hand performance were assessed at the beginning of the disease, at admission to the institute and at discharge after drug and rehabilitation treatment. Results. At the disease onset 40 pts (95,2% had knee joint damage (one sided in 28 — 66,6%. 30 from these 40 pts (75% had flexion deformity and daily activities limitations and two pts had anlde joint damage. 12 pts (28,6% received courses of nonsteroidal anti-inflammatory drugs (NSA1D and 5 pts (11,9% — disease modifying anti-rheumatic drugs (DMARD before admission. All pts had active joint syndrome at admission. Daily activities limitations were present in 41 pts (97,6%. DMARD were prescribed to 41 pts (with glucocorticoids (GC in 12 cases. Intra-articular injections of GC were performed in 15 pts. Individual exercise therapy (passive joint movement was applied in all pts, postural treatment — in 41 (97,6%. One pt received exercise therapy in a group. Splints were done for 6 pts. Stepped correction in plaster was performed in 4 from them. In all pts after treatment arthritis subsided and functional status improved. In 18 (42,8% from them function of damaged joint was fully restored and in 19 (45,2% — improved. After several stages of hospital treatment deformation was corrected and function restored in 4 (9,5% pts Conclusion. Клее joints are frequently involved in children of early age

  16. Investigation of Shrinkage Defect in Castings by Quantitative Ishikawa Diagram

    Directory of Open Access Journals (Sweden)

    Chokkalingam B.

    2017-03-01

    Full Text Available Metal casting process involves processes such as pattern making, moulding and melting etc. Casting defects occur due to combination of various processes even though efforts are taken to control them. The first step in the defect analysis is to identify the major casting defect among the many casting defects. Then the analysis is to be made to find the root cause of the particular defect. Moreover, it is especially difficult to identify the root causes of the defect. Therefore, a systematic method is required to identify the root cause of the defect among possible causes, consequently specific remedial measures have to be implemented to control them. This paper presents a systematic procedure to identify the root cause of shrinkage defect in an automobile body casting (SG 500/7 and control it by the application of Pareto chart and Ishikawa diagram. with quantitative Weightage. It was found that the root causes were larger volume section in the cope, insufficient feeding of riser and insufficient poured metal in the riser. The necessary remedial measures were taken and castings were reproduced. The shrinkage defect in the castings was completely eliminated.

  17. Impaired decision-making and brain shrinkage in alcoholism.

    Science.gov (United States)

    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 (Palcoholism may result from impairment of both emotional and cognitive networks.

  18. Response Predicting LTCC Firing Shrinkage: A Response Surface Analysis Study

    Energy Technology Data Exchange (ETDEWEB)

    Girardi, Michael; Barner, Gregg; Lopez, Cristie; Duncan, Brent; Zawicki, Larry

    2009-02-25

    The Low Temperature Cofired Ceramic (LTCC) technology is used in a variety of applications including military/space electronics, wireless communication, MEMS, medical and automotive electronics. The use of LTCC is growing due to the low cost of investment, short development time, good electrical and mechanical properties, high reliability, and flexibility in design integration (3 dimensional (3D) microstructures with cavities are possible)). The dimensional accuracy of the resulting x/y shrinkage of LTCC substrates is responsible for component assembly problems with the tolerance effect that increases in relation to the substrate size. Response Surface Analysis was used to predict product shrinkage based on specific process inputs (metal loading, layer count, lamination pressure, and tape thickness) with the ultimate goal to optimize manufacturing outputs (NC files, stencils, and screens) in achieving the final product design the first time. Three (3) regression models were developed for the DuPont 951 tape system with DuPont 5734 gold metallization based on green tape thickness.

  19. Physical Model of Drying Shrinkage of Recycled Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    GUO Yuanchen; WANG Xue; QIAN Jueshi

    2015-01-01

    We prepared concretes (RC0, RC30, and RC100) with three different mixes. The pore-size distribution parameters of RAC were examined by high-precision mercury intrusion method (MIM) and nuclear magnetic resonance (NMR) imaging. A capillary-bundle physical model with random-distribution pores (improved model, IM) was established according to the parameters, and dry-shrinkage strain values were calculated and verified. Results show that in all pore types, capillary pores, and gel pores have the greatest impacts on concrete shrinkage, especially for pores 2.5-50 and 50-100 nm in size. The median radii are 34.2, 31, and 34 nm for RC0, RC30, and RC100, respectively. Moreover, the internal micropore size distribution of RC0 differs from that of RC30 and RC100, and the pore descriptions of MIM and NMR are consistent both in theory and in practice. Compared with the traditional capillary-bundle model, the calculated results of IM have higher accuracy as demonstrated by experimental veriifcation.

  20. Role of ferrite and phosphorus plus sulphur in the crack sensitivity of autogenously welded type 309 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, Jr., F. J.

    1976-07-01

    A study on autogenous welding of Type 309 thin stainless steel sheet was made after experiencing cracking difficulties on several commercial heats. A relationship exists between the sum of the phosphorus plus sulfur, the ferrite control of the weld metal, and the crack sensitivity of autogenously made welds. A new simple weld test for thin-gage sheet is utilized for studying the susceptibility to cracking. A chemistry modification is suggested to alleviate possible weld cracking when autogenously welding this grade. The principles of crack sensitivity prediction could apply to other austenitic stainless steel types where chemistry limits are such that ferrite is possible.

  1. Design changes of device to investigation of alloys linear contraction and shrinkage stresses

    Directory of Open Access Journals (Sweden)

    J. Mutwil

    2009-07-01

    Full Text Available Some design changes in device elaborated by author to examination of linear contraction and shrinkage stresses progress of metals and alloys during– and after solidification have been described. The introduced changes have been focused on design of closing of shrinkage test rod mould. The introduced changes have been allowed to simplify a mounting procedure of thermocouples measuring a temperature of the shrinkage rod casting (in 6 points. Exemplary investigation results of linear contraction and shrinkage stresses development in Al-Si13.5% alloy have been presented.

  2. Shrinkage reduction of dental composites by addition of expandable zirconia filler

    DEFF Research Database (Denmark)

    Skovgaard, M.; Almdal, Kristoffer; Sørensen, Bent F.

    2011-01-01

    A problem with dental resin composites is the polymerization shrinkage, which makes the filling loosen from the tooth or induces crack formation. We have developed an expandable metastable tetragonal zirconia filler, which upon reaction with water, is able to counter the polymer shrinkage....... The shrinkage of the composite was calculated from density measurements using Archimedes method. The rate of the phase transformation in resin was measured by determining the volume fraction of monoclinic zirconia (vm). The composite had a vm of 0.5 after 8 h of water storage. The overall shrinkage...... of the composites was reduced from 3.2% (initially) to 1.7%....

  3. A physical resist shrinkage model for full-chip lithography simulations

    Science.gov (United States)

    Liu, Peng; Zheng, Leiwu; Ma, Maggie; Zhao, Qian; Fan, Yongfa; Zhang, Qiang; Feng, Mu; Guo, Xin; Wallow, Tom; Gronlund, Keith; Goossens, Ronald; Zhang, Gary; Lu, Yenwen

    2016-03-01

    Strong resist shrinkage effects have been widely observed in resist profiles after negative tone development (NTD) and therefore must be taken into account in computational lithography applications. However, existing lithography simulation tools, especially those designed for full-chip applications, lack resist shrinkage modeling capabilities because they are not needed until only recently when NTD processes begin to replace the conventional positive tone development (PTD) processes where resist shrinkage effects are negligible. In this work we describe the development of a physical resist shrinkage (PRS) model for full-chip lithography simulations and present its accuracy evaluation against experimental data.

  4. Maternal Alcohol Consumption during Pregnancy and Early Age Leukemia Risk in Brazil

    Directory of Open Access Journals (Sweden)

    Jeniffer Dantas Ferreira

    2015-01-01

    Full Text Available Objectives. To investigate the association between the maternal alcohol consumption during pregnancy and early age leukemia (EAL in offspring. Methods. Datasets were analyzed from a case-control study carried out in Brazil during 1999–2007. Data were obtained by maternal interviews using a standardized questionnaire. The present study included 675 children (193 acute lymphoid leukemia (ALL, 59 acute myeloid leukemia (AML, and 423 controls. Unconditional logistic regression was performed, and adjusted odds ratios (adj. OR on the association between alcohol consumption and EAL were ascertained. Results. Alcohol consumption was reported by 43% of ALL and 39% of AML case mothers and 35.5% of controls’. Beer consumption before and during pregnancy was associated with ALL in crude analysis (OR = 1.54, 95% CI, 1.08–2.19, although in adjusted analysis no statistical significance was found. For weekly intake of ≤1 glass (adj. OR = 1.30, 95% CI, 0.71–2.36 and ≥1 glass/week (adj. OR = 1.47, 95% CI, 0.88–2.46 a potential dose-response was observed (P trend < 0.03. Conclusion. This study failed to support the hypothesis of an increased risk of EAL associated with maternal alcohol intake during pregnancy, neither with the interaction with tobacco nor with alcohol consumption.

  5. Study on the hydration product of cement in early age using TEM

    Institute of Scientific and Technical Information of China (English)

    HAN Song; YAN PeiYu; LIU RengGuang

    2012-01-01

    The morphology,crystallization and elemental composition of cement hydration products in early age including Ca(OH)2,CSH gel,AFt and AFm were investigated by transmission electron microscopy (TEM).Compared with the results from SEM and XRD,the TEM method and its advantage in the investigation of early hydration products were discussed.The results showed that TEM method is more accurate and reliable than SEM in the investigation of early hydration products.The CSH gel was confirmed to be amorphous foil-like shape product with a lot of crumples in early hydration age.Its Ca/Si ratio is 1.3±0.2.The morphology difference of AFt and AFm was clarified.AFt and AFm are both poly-crystal with layered structure,composed of disordered nano crystal.The size of nano crystal is less than 20 nm.The difference of Ca/Si ratio results between SEM and TEM was investigated,and its reason was explained.

  6. Maternal Alcohol Consumption during Pregnancy and Early Age Leukemia Risk in Brazil.

    Science.gov (United States)

    Ferreira, Jeniffer Dantas; Couto, Arnaldo Cézar; Emerenciano, Mariana; Pombo-de-Oliveira, Maria S; Koifman, Sergio

    2015-01-01

    Objectives. To investigate the association between the maternal alcohol consumption during pregnancy and early age leukemia (EAL) in offspring. Methods. Datasets were analyzed from a case-control study carried out in Brazil during 1999-2007. Data were obtained by maternal interviews using a standardized questionnaire. The present study included 675 children (193 acute lymphoid leukemia (ALL), 59 acute myeloid leukemia (AML), and 423 controls). Unconditional logistic regression was performed, and adjusted odds ratios (adj. OR) on the association between alcohol consumption and EAL were ascertained. Results. Alcohol consumption was reported by 43% of ALL and 39% of AML case mothers and 35.5% of controls'. Beer consumption before and during pregnancy was associated with ALL in crude analysis (OR = 1.54, 95% CI, 1.08-2.19), although in adjusted analysis no statistical significance was found. For weekly intake of ≤1 glass (adj. OR = 1.30, 95% CI, 0.71-2.36) and ≥1 glass/week (adj. OR = 1.47, 95% CI, 0.88-2.46) a potential dose-response was observed (P trend pregnancy, neither with the interaction with tobacco nor with alcohol consumption.

  7. Analysis of gene set using shrinkage covariance matrix approach

    Science.gov (United States)

    Karjanto, Suryaefiza; Aripin, Rasimah

    2013-09-01

    Microarray methodology has been exploited for different applications such as gene discovery and disease diagnosis. This technology is also used for quantitative and highly parallel measurements of gene expression. Recently, microarrays have been one of main interests of statisticians because they provide a perfect example of the paradigms of modern statistics. In this study, the alternative approach to estimate the covariance matrix has been proposed to solve the high dimensionality problem in microarrays. The extension of traditional Hotelling's T2 statistic is constructed for determining the significant gene sets across experimental conditions using shrinkage approach. Real data sets were used as illustrations to compare the performance of the proposed methods with other methods. The results across the methods are consistent, implying that this approach provides an alternative to existing techniques.

  8. Relationship between Retinal Layer Thickness and the Visual Field in Early Age-Related Macular Degeneration

    Science.gov (United States)

    Acton, Jennifer H.; Smith, R. Theodore; Hood, Donald C.; Greenstein, Vivienne C.

    2012-01-01

    Purpose. To quantify and compare the structural and functional changes in subjects with early age-related macular degeneration (AMD), using spectral-domain optical coherence tomography (SD-OCT) and microperimetry. Methods. Twenty-one eyes of 21 subjects with early AMD were examined. MP-1 10-2 visual fields (VFs) and SD-OCT line and detail volume scans were acquired. The thicknesses of the outer segment (OS; distance between inner segment ellipsoid band and upper retinal pigment epithelium [RPE] border) and RPE layers and elevation of the RPE from Bruch's membrane were measured using a computer-aided manual segmentation technique. Thickness values were compared with those for 15 controls, and values at locations with VF total deviation defects were compared with values at nondefect locations at equivalent eccentricities. Results. Sixteen of 21 eyes with AMD had VF defects. Compared with controls, line scans showed significant thinning of the OS layer (P = 0.006) and thickening and elevation of the RPE (P = 0.037, P = 0.002). The OS layer was significantly thinner in locations with VF defects compared with locations without defects (P = 0.003). There was a negligible difference between the retinal layer thickness values of the 5 eyes without VF defects and the values of normal controls. Conclusions. In early AMD, when VF defects were present, there was significant thinning of the OS layer and thickening and elevation of the RPE. OS layer thinning was significantly associated with decreased visual sensitivity, consistent with known photoreceptor loss in early AMD. For AMD subjects without VF defects, thickness values were normal. The results highlight the clinical utility of both SD-OCT retinal layer quantification and VF testing in early AMD. PMID:23074210

  9. EFFECTIVENESS OF AUTOGENIC DRAINAGE VERSUS POSTURAL DRAINAGE ON OXYGEN SATURATION IN PATIENTS WITH CHRONIC BRONCHITIS WITH 15 MINUTES POST THERAPY

    OpenAIRE

    Kiran, V.; Dr. Bhimasen .S; E. Mastanaiah; A. Thiruppathi

    2014-01-01

    Background: Patients with COPD will have more amount of secretions. To clear the secretions by using of different bronchial hygiene techniques like postural drainage and autogenic drainage technique, manual hyperventilation technique ,active cycle breathing technique .Hence in this study to compare the short-term effects of postural drainage with clapping (PD) and autogenic drainage (AD) on level of oxygen saturation in blood, and amount of sputum recovery. Methodology: The study was done ...

  10. Creep and shrinkage effects on integral abutment bridges

    Science.gov (United States)

    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

  11. The Relationship Among Photoinhibition, Photooxidation and Early Aging at a Late Development Stage in Different Varieties with High Yield

    Institute of Scientific and Technical Information of China (English)

    JIAO De-mao; LI Xia; HUANG Xue-qing; JI Ben-hua

    2002-01-01

    Using six high yield varieties from different ecological districts in China the parameters of Chl fluorescence, the performance of membrane lipid peroxidation and the reduction of Chl content in flag leaf under natural condition at the later developmental stages (from heading stage to mature stage). The results showed that Fv/Fm, decreased gradually, the excessive light energy led to the accumulation of active oxygen O2-, H2O2 and the product of membrane-lipid peroxidation, MDA, which resulted in the reduction of Chl content and early aging due to photooxidation during the course of senescence of flag leaf. This phenomenon varied obviously in rice varieties. When comparina japonica tolerant to photooxidation, Fv/Fm in indica shanyou 63 susceptible to photoxidation decreased significantly. An increase of active oxygen and a sharp drop of Chl content, resulted in "yellowish" early aging and influenced filling and setting of rice grain. The mechanism on early aging in indica was related to light and temperature conditions in filling stages. On a fine day (above 25℃ ), PS Ⅱ reaction center exhibited a dynamic change on revisable inactivation. Under strong midday light, PS Ⅱ function in indica exhibited obvious down-regulation and photoinhibition; Under strong light with low temperature, PS Ⅱ resulted in photodamage, showing early aging, which were related to the degradation of PS Ⅱ - D1 Protein and the inhibition of the endogenous protecting system such as Xanthophyll cycle and the enzymes of scavenging active oxygen. The results suggested that for a view of high-yield breeding, on the basis of a good type-plant, giving consideration to the utilization of heterosis and resistance to early aging, selecting japonica or a sterile line with japonice genotype as maternal was a breeding strategy worthy of being paid more attention.

  12. To develop a quantitative method for predicting shrinkage porosity in squeeze casting

    Institute of Scientific and Technical Information of China (English)

    Shaomin Li; Kenichiro Mine; Shinji Sanakanishi; Koichi Anzai

    2009-01-01

    In order to secure high strength and high elongation of suspension parts, it is critical to predict shrinkage porosity quantitatively. A new simulation method for quantitative predic'don of shrinkage porosity when replenishing molten metal has been proposed for squeeze casting process. To examine the accuracy of the calculation model, the proposed method was applied to a plate model.

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

    Science.gov (United States)

    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.

  14. Effect of modulated photo-activation on polymerization shrinkage behavior of dental restorative resin composites

    NARCIS (Netherlands)

    T.T. Tauböck; A.J. Feilzer; W. Buchalla; C.J. Kleverlaan; I. Krejci; T. Attin

    2014-01-01

    This study investigated the influence of modulated photo-activation on axial polymerization shrinkage, shrinkage force, and hardening of light- and dual-curing resin-based composites. Three light-curing resin composites (SDR bulk-fill, Esthet X flow, and Esthet X HD) and one dual-curing material (Re

  15. Magnitude, modeling and significance of swelling and shrinkage processes in clay soils.

    NARCIS (Netherlands)

    Bronswijk, J.J.B.

    1991-01-01

    The dynamic process of swelling and shrinkage in clay soils has significant practical consequences, such as the rapid transport of water and solutes via shrinkage cracks to the subsoil, and the destruction of buildings and roads on clay soils. In order to develop measuring methods and computer simul

  16. Effect of cure cycle on enthalpy relaxation and post shrinkage in neat epoxy and epoxy composites

    DEFF Research Database (Denmark)

    Jensen, Martin; Jakobsen, Johnny

    2016-01-01

    . Enthalpy recovery is found to exert a minor impact on the sample dimension during reheating since a non-reversing shrinkage is observed during reheating. This shrinkage is ascribed to structural changes on molecular level in the specimen and it is inferred that samples with a high initial disorder only...

  17. Influence of Cure Shrinkage on Process-Induced Stress and Deformation in Thick Thermosetting Composites

    Science.gov (United States)

    1992-07-01

    unidirectional composite micromechanics model The constituent fiber properties (constant), the resin properties and chemical shrinkage (cure dependent...during cure. Changes in the resin properties directly influence the mechanical properties in the composite, and chemical shrinkage represents a...xA (5) The expansion coefficients, otL and or, are based on the micromechanics model utilizing constant fiber properties. cure dependent resin

  18. Prediction of Shrinkage Pore Volume Fraction Using a Dimensionless Niyama Criterion

    Science.gov (United States)

    Carlson, Kent D.; Beckermann, Christoph

    2009-01-01

    A method is presented to use a dimensionless form of the well-known Niyama criterion to directly predict the amount of shrinkage porosity that forms during solidification of metal alloy castings. The main advancement offered by this method is that it avoids the need to know the threshold Niyama value below which shrinkage porosity forms; such threshold values are generally unknown and alloy dependent. The dimensionless criterion accounts for both the local thermal conditions (as in the original Niyama criterion) and the properties and solidification characteristics of the alloy. Once a dimensionless Niyama criterion value is obtained from casting simulation results, the corresponding shrinkage pore volume fraction can be determined knowing only the solid fraction-temperature curve and the total solidification shrinkage of the alloy. Curves providing the shrinkage pore volume percentage as a function of the dimensionless Niyama criterion are given for WCB steel, aluminum alloy A356, and magnesium alloy AZ91D. The present method is used in a general-purpose casting simulation software package to predict shrinkage porosity in three-dimensional (3-D) castings. Comparisons between simulated and experimental shrinkage porosity results for a WCB steel plate casting demonstrate that this method can reasonably predict shrinkage. Additional simulations for magnesium alloy AZ91D illustrate that this method is applicable to a wide variety of alloys and casting conditions.

  19. Ten-year comparative analysis of bovine pericardium and autogenous vein for patch angioplasty in patients undergoing carotid endarterectomy.

    Science.gov (United States)

    Kim, Ji-Hoon; Cho, Yong-Pil; Kwon, Tae-Won; Kim, Hyangkyoung; Kim, Geun-Eun

    2012-04-01

    To evaluate early and late clinical outcomes of carotid endarterectomy (CEA) with bovine pericardium patch in comparison with autogenous vein. During a 10-year period, 456 CEAs were performed using patch closure of the arteriotomy with bovine pericardium (252 cases) and autogenous vein (204 cases). Retrospectively, surgical outcomes were evaluated and compared regarding CEA-related parameters, early and late mortality and morbidity rates, and the incidence of restenosis and aneurysmal dilatation between patients with bovine pericardium patch closure and those with autogenous vein closure. The two groups were comparable regarding basic demographics, clinical data, and anatomic data, except the incidence of coronary or peripheral arterial diseases. In patients with bovine pericardium patch closure, the total operating time and carotid clamping duration were statistically significantly shorter than in those with autogenous vein closure (P pericardium patch closure (5.6% vs. 10.8%; P pericardium patch closure and 67 months for autogenous vein closure, the incidence of restenosis was similar, but aneurysmal dilatation was higher in patients with autogenous vein closure with a statistically significant difference (0% vs. 2.0%; P pericardium patch angioplasty showed excellent early and late clinical outcomes. Our results demonstrated bovine pericardium to be a suitable patch material for routine use in CEA. Copyright © 2012 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.

  20. Monitoring of collagen shrinkage by use of second harmonic generation microscopy

    Science.gov (United States)

    Lin, Sung-Jan; Chen, Jau-Shiuh; Lo, Wen; Sun, Yen; Chen, Wei-Liang; Chan, Jung-Yi; Tan, Hsin-Yuan; Lin, Wei-Chou; Hsu, Chih-Jung; Young, Tai-Horng; Jee, Shiou-Hwa; Dong, Chen-Yuan

    2006-02-01

    Thermal treatment induced collagen shrinkage has a great number of applications in medical practice. Clinically, the there is lack of reliable non-invasive methods to quantify the shrinkage. Overt treatment by heat application can lead to devastating results. We investigate the serial changes of collagen shrinkage by thermal treatment of rat tail tendons. The change in length is correlated with the finding in second harmonic generation microscopy and histology. Rat tail tendon shortens progressively during initial thermal treatment. After a certain point in time, the length then remains almost constant despite further thermal treatment. The intensity of second harmonic generation signals also progressively decreases initially and then remains merely detectable upon further thermal treatment. It prompts us to develop a mathematic model to quantify the dependence of collagen shrinkage on changes of SHG intensity. Our results show that SHG intensity can be used to predict the degree of collagen shrinkage during thermal treatment for biomedical applications.

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

    Science.gov (United States)

    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.

  2. The Formation of Carbon Nanostructures via Catalytic Pyrolysis of Naphthalene under Its Autogenic Pressure

    Directory of Open Access Journals (Sweden)

    Chao-Gang Wang

    2015-01-01

    Full Text Available The formation of carbon nanotubes (CNTs, spherical carbon nanocapsules (CNCs, and carbon spheres (CSs is accomplished by using the method of reactions under autogenic pressure at elevated temperatures (RAPET. A powder mixture of naphthalene and nickel acetate tetrahydrate is dissociated under its autogenic pressure. The resultant CNTs and CNCs exhibit good graphitic quality, and the diameters range from 50~200 nm. Smooth and monodisperse CSs with the diameter ranging from 5~10 μm can be obtained by pyrolysis of pure naphthalene. Our results show that the reaction temperature and catalyst proportion play a key role in the formation of carbon nanostructures with RAPET method.

  3. A theoretical and experimental analysis of polymerization shrinkage of bone cement: A potential major source of porosity.

    Science.gov (United States)

    Gilbert, J L; Hasenwinkel, J M; Wixson, R L; Lautenschlager, E P

    2000-10-01

    A theoretical basis for understanding polymerization shrinkage of bone cement is presented based on density changes in converting monomer to polymer. Also, an experimental method, based on dilatometry and the Archimedes' principle is presented for highly precise and accurate measurement of unconstrained volumetric shrinkage of bone cement. Furthermore, a theoretical and experimental analysis of polymerization shrinkage in a constrained deformational state is presented to demonstrate that porosity can develop due to shrinkage. Six bone-cement conditions (Simplex-Ptrade mark vacuum and hand mixed, Endurancetrade mark vacuum mixed, and three two-solution experimental bone cements with higher initial monomer levels) were tested for volumetric shrinkage. It was found that shrinkage varied statistically (ptheory that they are the result of shrinkage. The results of this study show that shrinkage of bone cement under certain constrained conditions may result in the development of porosity at the implant-bone cement interface and elsewhere in the polymerizing cement mantle.

  4. Application of autogenic training in patients with Ménière disease.

    Science.gov (United States)

    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 training may enhance the mental well-being of patients with Ménière disease and improve clinical outcome.

  5. Operational Applications of Autogenic Feedback Training Exercise as a Treatment for Airsickness in the Military

    Science.gov (United States)

    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.

  6. Synthesis of MgB2 at Low Temperature and Autogenous Pressure

    Directory of Open Access Journals (Sweden)

    Ian D. R. Mackinnon

    2014-05-01

    Full Text Available 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.

  7. Eyelid-associated complications after autogenous fat injection for cosmetic forehead augmentation

    Science.gov (United States)

    2013-01-01

    Background We report two cases of unilateral upper eyelid swelling with multiple small lumps as an unusual complication of autogenous fat injection for cosmetic forehead augmentation. Case presentation Two female patients were referred to our clinic for unusual unilateral eyelid swelling, with multiple small lumps. The duration of symptoms differed in each case, but both patients had a history of autogenous fat injection for cosmetic forehead augmentation at a local plastic surgery clinic. The lumps were small (diameter 5 mm~10 mm), palpable, hard, and nonmobile, and were evaluated by magnetic resonance imaging (MRI). Lumps from the eyelids of two patients were excised under general anesthesia. All of the masses were located deeply and found near the superior orbital rim or lateral orbital rim. The lumps exhibited chronic inflammation with fibrosis. Some of the lumps showed foamy histiocytic aggregation and foreign body lipogranuloma, resulting from iatrogenic fat injection. After excision, all masses and swelling disappeared, and moderate ptotic eyelid or lagophthalmos of affected eyes also improved. Conclusions To our knowledge, eyelid swelling with multiple lumps in the eyelid is a very rare complication of autogenous fat injection for cosmetic forehead augmentation. This report should be helpful for ophthalmic clinicians who encounter these unusual symptoms. PMID:23841959

  8. Bioactive Glass versus Autogenous Iliac Crest Bone Graft in Adolescent Idiopathic Scoliosis Surgery

    Directory of Open Access Journals (Sweden)

    Ameri Ebrahim

    2009-10-01

    Full Text Available Surgery on the skeleton frequently requires harvesting of autogenous bone graft from the pelvis, but this procedure often is complicated by problems. The purpose of this retrospective, comparative descriptive study was to compare the efficacy of metal-derived bioactive glass (Novabone versus autogenous iliac crest bone graft in adolescent idiopathic scoliosis surgery. The study was carried out on forty cases (aged 14-20 years with 55 total curves fused for AIS. Posterior spinal fusion was performed using local bone grafts combined with autogenous iliac crest bone graft in 20 patients (group 1, and combined with Novabone in another twenty ones (group 2. The patients were observed for a minimum of 24 months after surgery, with a mean postoperative observation time of 34.7 months. The results were assessed clinically and radiologically. In group 1, average preoperative curve was 66° with immediate correction to 24.2° (59.7% and final follow-up of 27.4° (54.3%, but in group 2 the calculated numbers included 63.8°, 25.8° (59.6% and 28.4° (55.5 % respectively. There were 5 indeterminate fusions (3 cases in group 1 and 2 in the other group, 1 acute infection, and 1 hook dislodgement in the synthetic group. These results justify and favor the use of bone substitutes for instrumented posterior spinal fusion in AIS. Potentially hazardous harvesting of pelvic bone is no longer necessary for such operations.

  9. Bioactive Glass versus Autogenous Iliac Crest Bone Graft in Adolescent Idiopathic Scoliosis Surgery

    Directory of Open Access Journals (Sweden)

    Ameri E

    2009-04-01

    Full Text Available Surgery on the skeleton frequently requires harvesting of autogenous bone graft from the pelvis, but this procedure is complicated by problems. The purpose of this retrospective, comparative descriptive study was to compare the efficacy of metal-derived bioactive glass (Novabone versus autogenous iliac crest bone graft in adolescent idiopathic scoliosis surgery. The study was carried out on forty cases (aged 14-20 years with 55 total curves fused for AIS. Posterior spinal fusion was performed using local bone grafts combined with autogenous iliac crest bone graft in 20 patients (group 1, and combined with Novabone in another twenty ones (group 2. The patients were observed for a minimum of 24 months after surgery, with a mean postoperative observation time of 34.7 months. The results were assessed clinically and radiologically. In group 1, average preoperative curve was 66° with immediate correction to 24.2° (59.7% and final follow-up of 27.4° (54.3%, but in group 2 the calculated numbers included 63.8°, 25.8° (59.6% and 28.4° (55.5 % respectively. There were 5 indeterminate fusions (3 cases in group 1 and 2 in the other group, 1 acute infection, and 1 hook dislodgement in the synthetic group. These results justify and favor the use of bone substitutes for instrumented posterior spinal fusion in AIS. Potentially hazardous harvesting of pelvic bone is no longer necessary for such operations.

  10. Bone formation by autogenous grafting of cultured bone/porous ceramic constructs in a dog

    Energy Technology Data Exchange (ETDEWEB)

    Iida, J.; Ueda, Y.; Ohgushi, H.; Takakura, Y. [Nara Medical Univ., Kashihara (Japan). Dept. of Orthopedic Surgery; Yoshikawa, T. [Nara Medical Univ., Kashihara (Japan). Dept. of Orthopedic Surgery; Nara Medical Univ., Kashihara (Japan). Dept. of Phathology; Uemura, T.; Tateishi, T. [National Inst. for Advanced Interdisciplinary Research (NAIR), Ibaraki (Japan). Tsukuba Research Center; Enomoto, Y.; Ichijima, K. [Nara Medical Univ., Kashihara (Japan). Dept. of Phathology

    2001-07-01

    Five ml of bone marrow was collected from the humerus of a 6 month old female dog by needle aspiration. The marrow was cultured in T-75 flask and expand the marrow mesenchymal cells. After 1 week in primary culture, cells were released by trypsin treatment, concentrated and loaded onto porous hydroxyapatite (HA) blocks. The marrow/HA constructs were subcultured in the presence of dexamethasone and beta-glycerophosphate (osteogenic medium). After 2 weeks of subculture, the autogenous cultured bone/HA constructs were subcutaneously implanted into the back of the dog. Histological findings of the constructs at 3 weeks after implantation revealed thick layer of lamellar bone together with active osteoblasts lining in many pore areas of the HA. High alkaline phosphatase activity could be detected in the construct. These results indicate that autogenous cultured bone/HA constructs can produce extensive bone formation after implantation in a large animal(dog). Therefore, based upon the fact that human marrow-derived culture bone/HA construct possesses osteogenic potential when it is grafted into nude mice, it can be expected that autogenous human cultured bone/ceramic grafts may be useful to reconstruct bone in the clinical setting. (orig.)

  11. Autogenous standard versus inside-out vein graft to repair facial nerve in rabbits

    Institute of Scientific and Technical Information of China (English)

    TANG Jie; WANG Xue-mei; HU Jing; LUO En; QI Meng-chun

    2008-01-01

    To evaluate autogenous vein grafts and inside-out vein grafts as conduits for the defects repair in the rabbit facial nerves.Methods:The 10 mm segments of buccal division of facial nerve were transected for 48 rabbits in this study.Then the gaps were immediately repaired by autogenous vein grafts or inside-out vein grafts in different groups. All the animals underwent the whisker movement test and electrophysiologic test during the following 16 weeks at different time points postoperatively. Subsequently,the histological examination was performed to observe the facial nerve regeneration morphologically.Results:At 8 weeks after operation,the facial nerve regeneration has significant difference between the experimental group and the control group in electrophysiologic test and histological observation. However,at the end of this study,16 weeks after operation,there was no significant difference between inside-out vein grafts and standard vein grafts in enhancing peripheral nerve regeneration.Conclusion:This study suggest that both kinds of vein grafts play positive roles in facial nerve regeneration after being repaired immediately,but the autogenous inside-out vein grafts might accelerate and facilitate axonal regeneration as compared with control.

  12. Differences in latent inhibition as a function of the autogenous-reactive OCD subtype.

    Science.gov (United States)

    Lee, Han-Joo; Telch, Michael J

    2010-07-01

    We examined differences in a visual search-based latent inhibition (LI) task in 48 non-treatment seeking individuals diagnosed with obsessive-compulsive disorder (OCD) and 26 non-OCD controls, using a visual search-based LI task as a function of participants' primary obsessional presentation based on the autogenous-reactive subtype model of obsessions (Lee & Kwon, 2003; Lee & Telch, 2007). We hypothesized that LI would be significantly attenuated among OCD participants whose primary obsessions were characterized by aversive impulses, images, or thoughts with sexual, aggressive, blasphemous, and repulsive themes (autogenous obsessions) due to their weakened attentional inhibitory mechanisms and elevated schizotypal personality features, as compared with those whose primary obsessions were characterized by somewhat realistic aversive mental intrusions about contamination, mistakes, accidents, or disarray (reactive obsession) and non-OCD controls. Results showed that those primarily displaying autogenous obsessions failed to display LI, whereas those primarily displaying reactive obsessions and non-OCD controls displayed significant LI effects. Our data suggest that the magnitude of LI varies as a function of primary obsessional presentations among individuals with OCD.

  13. Alternative method to treat oroantral communication and fistula with autogenous bone graft and platelet rich firbin

    Science.gov (United States)

    Niedzielska, Iwona; Borgiel-Marek, Halina; Różanowski, Bartosz

    2016-01-01

    Background Removing a tooth from the jaw results in the occurrence of oroantral communication in beneficial anatomic conditions or in the case of a iatrogenic effect. Popularized treatments of the oroantral communication have numerous faults. Large bone defect eliminates the chance to introduce an implant. Purpose of this work was assessment of the usefulness of autogenous bone graft and PRF in normal bone regeneration in the site of oroantral communication. Material and Methods Bone regeneration in the site of oroantral communication was assessed in 20 patients. Bone defects were supplemented autogenous bone graft from mental protuberance in 14 cases and from oblique line in 6 cases. The graft was covered with a PRF membrane. Results In the study group in all cases closure of the oroantral communication was observed. The average width of the alveolar was 13 mm and the average height was 12.5 mm. In 3 patients an average increase of alveolar height of 1.5 mm was observed. Conclusions This method may be the best option to prepare alveolar for new implant and prosthetic solutions. Key words:Oroantral communication, oroantral fistula, autogenous bone graft, bone regeneration, platelet rich fibrin. PMID:27475687

  14. Bone Formation in Maxillary Sinus Lift Using Autogenous Bone Graft at 2 and 6 Months

    Science.gov (United States)

    Netto, Henrique Duque; Miranda Chaves, Maria das Graças Alfonso; Aatrstrup, Beatriz; Guerra, Renata; Olate, Sergio

    2016-01-01

    SUMMARY The aim of this study is to compare the bone formation in maxillary sinus lift with an autogenous bone graft in histological evaluation at 2 or 6 months. A comparative study was designed where 10 patients with missing teeth bilaterally in the posterior zone of the maxilla were selected. Patients received a particulate autogenous bone graft under the same surgical conditions, selecting a site to collect a biopsy and histological study at two months and another at six months postoperatively. Histomorphometry was performed and were used Kolmogorov-Smirnov test, student’s t-test and Spearman’s correlation coefficient, considering a value of p<0.05. Differences were observed in inflammatory infiltrate and vascularization characteristics; however, the group analyzed at two months presented 38.12% ± 6.64 % of mineralized tissue, whereas the group studied at 6 months presented an average of 38.45 ± 9.27 %. There were no statistical differences between the groups. It is concluded that the bone formation may be similar in intrasinus particulate autogenous bone grafts in evaluations at two or six months; under these conditions, early installation of implants is viable. PMID:27867255

  15. A new view on bone graft in dental implantation: Autogenous bone mixed with titanium granules

    Directory of Open Access Journals (Sweden)

    Yeke Wu

    2013-01-01

    Full Text Available Introduction : Dental implants have been widely applied in clinic for many years. However, the success rate is still challenging mainly because of bone deficiency. An ideal bone graft is traditionally thought to guide and induce new bone regeneration as well as been absorbed completely by human body. The Hypothesis: Autogenous bone mixed with titanium granules might be an ideal bone graft for dental implantation. Evaluation of the Hypothesis: First, we analyzed advantages of grafts of autogenous bone mixed with titanium granules, such as serving as a s scaffold for wound healing and tissue regeneration, creating sui microenvironment for implant-bone integration, shortening the new bone′s creeping distance, etc. Then we creatively hypothesized a novel alternative bone graft with premixed autogenous bone and non-absorbent titanium granules. Apart from repairing bone deficiency, our hypothesis could promote the integration between new bone and titanium implant from the perspective of microenvironment. We believe that the method is promising and worth extension in clinical application.

  16. Evaluation of polymerization shrinkage, polymerization shrinkage stress, wear resistance, and compressive strength of a silorane-based composite: A finite element analysis study

    Directory of Open Access Journals (Sweden)

    Suresh Mitthra

    2017-01-01

    Full Text Available Background: Understanding the mechanical properties is important in predicting the clinical behavior of composites. Finite element analysis (FEA evaluates properties of materials replicating clinical scenario. Aim: This study evaluated polymerization shrinkage and stress, wear resistance (WR, and compressive strength (CS of silorane in comparison with two methacrylate resins. Settings and Design: This study design was a numerical study using FEA. Materials and Methods: Three-dimensional (3D models of maxillary premolar with Class I cavities (2 mm depth, 4 mm length, and 2.5 mm width created and restored with silorane, nanohybrid, and microhybrid; Groups I, II, and III, respectively. Loads of 200–600 N were applied. Polymerization shrinkage was first determined by displacement produced in the X, Y, and Z planes. Maximum stress distribution due to shrinkage was calculated using AN SYS software. 3D cube models of composite resins were simulated with varying filler particle size. Similar loads were applied. WR and compressive stress were calculated: K W L/H and load/cross-sectional area, respectively. Statistical analysis done using one-way ANOVA, Kruskal–Wallis, and Tukey's honestly significant difference test (P < 0.05. Results: Polymerization shrinkage (0.99% and shrinkage stress (233.21 Mpa of silorane were less compared to microhybrid (2.14% and 472.43 Mpa and nanohybrid (2.32% and 464.88 Mpa. Silorane (7.92×/1011 μm/mm3 and nanohybrid (7.79×/1011 showed superior WR than microhybrid (1.113×/1017. There was no significant difference in compressive stress among the groups. Conclusion: Silorane exhibited less polymerization shrinkage and shrinkage stress compared to methacrylates. Silorane and nanohybrid showed greater WR compared to microhybrid. CS of all groups was similar.

  17. Vygotsky’s socio-cultural theory of literacy Scaffolding children to read and write at an early age

    Directory of Open Access Journals (Sweden)

    Mahzan Arshad

    2009-10-01

    Full Text Available In the article the concept of semiotic mediation, appropriation, internalization,Zone of Proximal Development (ZPD and scaffolding in particular werereviewed to provide understanding of the process. Under the concept ofsemiotic mediation, the issue of how children learn through imitating adults wasexamined with inputs from second language acquisition theories. Vygotsky’sconcept of appropriation provides the springboard for a discussion on howchildren may appropriate the psychological tool of language through modelingand text meditation in the context of second language learning. It is hopedthat the understanding of these concepts could lead to more insights in orderto understand the various changes observable in children at early age as theynudge to achieve their potential in their literacy development. The informationgathered in the paper may be used by parents or teachers in preschool as thefoundation to help children acquire literacy skills at early age.

  18. Investigations of linear contraction and shrinkage stresses development in hypereutectic al-si binary alloys

    Directory of Open Access Journals (Sweden)

    J. Mutwil

    2009-07-01

    Full Text Available Shrinkage phenomena during solidification and cooling of hypereutectic aluminium-silicon alloys (AlSi18, AlSi21 have been examined. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered has been used as a test sample. Two type of experiments have been conducted: 1 on development of the test sample linear dimension changes (linear expansion/contraction, 2 on development of shrinkage stresses in the test sample. By the linear contraction experiments the linear dimension changes of the test sample and the metal test mould as well a temperature in six points of the test sample have been registered. By shrinkage stresses examination a shrinkage tension force and linear dimension changes of the test sample as well a temperature in three points of the test sample have been registered. Registered time dependences of the test bar and the test mould linear dimension changes have shown, that so-called pre-shrinkage extension has been mainly by mould thermal extension caused. The investigation results have shown that both: the linear contraction as well as the shrinkage stresses development are evident dependent on metal temperature in a warmest region the sample (thermal centre.

  19. Compositional Changes for Reduction of Polymerisation-Induced Shrinkage in Holographic Photopolymers

    Directory of Open Access Journals (Sweden)

    D. Cody

    2016-01-01

    Full Text Available Polymerisation-induced shrinkage is one of the main reasons why many photopolymer materials are not used for certain applications including holographic optical elements and holographic data storage. Here, two compositional changes for the reduction of shrinkage in an acrylamide-based photopolymer are reported. A holographic interferometric technique was used to study changes in the dynamics of the shrinkage processes occurring in the modified photopolymer during holographic recording in real time. Firstly, the effect of the replacement of the acrylamide monomer in the photopolymer composition with a larger monomer molecule, diacetone acrylamide, on polymerisation-induced shrinkage has been studied. A reduction in relative shrinkage of 10–15% is obtained using this compositional change. The second method tested for shrinkage reduction involved the incorporation of BEA-type zeolite nanoparticles in the acrylamide-based photopolymer. A reduction in relative shrinkage of 13% was observed for acrylamide photopolymer layers doped with 2.5% wt. BEA zeolites in comparison to the undoped photopolymer.

  20. Importance of shrinkage in empirical bayes estimates for diagnostics: problems and solutions.

    Science.gov (United States)

    Savic, Radojka M; Karlsson, Mats O

    2009-09-01

    Empirical Bayes ("post hoc") estimates (EBEs) of etas provide modelers with diagnostics: the EBEs themselves, individual prediction (IPRED), and residual errors (individual weighted residual (IWRES)). When data are uninformative at the individual level, the EBE distribution will shrink towards zero (eta-shrinkage, quantified as 1-SD(eta (EBE))/omega), IPREDs towards the corresponding observations, and IWRES towards zero (epsilon-shrinkage, quantified as 1-SD(IWRES)). These diagnostics are widely used in pharmacokinetic (PK) pharmacodynamic (PD) modeling; we investigate here their usefulness in the presence of shrinkage. Datasets were simulated from a range of PK PD models, EBEs estimated in non-linear mixed effects modeling based on the true or a misspecified model, and desired diagnostics evaluated both qualitatively and quantitatively. Identified consequences of eta-shrinkage on EBE-based model diagnostics include non-normal and/or asymmetric distribution of EBEs with their mean values ("ETABAR") significantly different from zero, even for a correctly specified model; EBE-EBE correlations and covariate relationships may be masked, falsely induced, or the shape of the true relationship distorted. Consequences of epsilon-shrinkage included low power of IPRED and IWRES to diagnose structural and residual error model misspecification, respectively. EBE-based diagnostics should be interpreted with caution whenever substantial eta- or epsilon-shrinkage exists (usually greater than 20% to 30%). Reporting the magnitude of eta- and epsilon-shrinkage will facilitate the informed use and interpretation of EBE-based diagnostics.

  1. Polymerisation shrinkage versus layer thickness of a dentine bonding resin: Method development

    Directory of Open Access Journals (Sweden)

    Jafarzadeh T

    2002-07-01

    Full Text Available Dentine bonding systems are usually unfilled, and so their shrinkage may be significant. High"nshrinkage may cause internal stress at the interface between resin-composite restoration and the dentine"nsubstrate. Failure of the adhesive interface may be observed due to the interna! stress. The aims of this"nstudy were:"nA To obtain a suitable method for measuring the kinetics of polymerisation shrinkage in unfilled resm at different thicknesses, particularly for thin films."nB Consideraing the effect of thickness on shrinkage."nScotchbond Multipurpose (3M adhesive bond resin was used. To overcome the particular challenges presented by thin films, a filled-ring measurement procedure was used. Also, a non-contact laser analogue displacement sensor system was developed and applied to measure polymerisation shrinkage. Regression analysis was performed on a complete data set. Non-linear regression analysis established a logarithmic relationship between polymerisation shrinkage and layer thickness. The method applied in this study was found to be sensitive and accurate procedure for determining photo-polymerisation shrinkage of thin films. Polymerisation shrinkage increased with logarithmic of the adhesive thickness.

  2. An integrated approach to soil structure, shrinkage, and cracking in samples and layers

    CERN Document Server

    Chertkov, V Y

    2014-01-01

    A recent model showed how a clay shrinkage curve is step-by-step transformed into the shrinkage curve of an aggregated soil at any clay content if it is measured on samples so small that cracks do not occur at shrinkage. Such a shrinkage curve was called a reference curve. The present work generalizes this model to any soil sample size or layer thickness, i.e., to any crack contribution to the shrinkage curve. The approach is based on: (i) recently suggested features of an intra-aggregate structure; (ii) detailed accounting for the contributions to the soil volume and water content during shrinkage; and (iii) new concepts of lacunar factor, crack factor, and critical sample size. The following input parameters are needed for the prediction: (i) all parameters determining the basic dependence of the reference shrinkage curve; (ii) parameters determining the critical sample size (structural porosity and minimum and maximum aggregate size at maximum swelling); and (iii) initial sample size or layer thickness. A ...

  3. Determination of the Thermal Expansion Coefficient of Concrete at Early Ages by Using Temperature-stress Testing Machine

    Institute of Scientific and Technical Information of China (English)

    HUO Kaicheng; SHUI Zhonghe; LI Yue

    2006-01-01

    By using the uptodate temperatuer-stress testing machine, the thermal expansion coefficient of concrete at early ages was studied and indicative conclusions were achieved: temperature rising due to hydration heat is not directly correlated with cracking, but the temperature and stress evolution process should be taken into consideration in the same time. Proper chemical admixtures and mineral compositions can improve the mechanical properties of concrete such as thermal expansion coefficient, which is very indicative in practice.

  4. CHANNEL SHRINKAGE AND ITS INSTABILITY IN THE LOWER YELLOW RIVER1

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    From the mid 1980s through the late 1990s, the channel of the lower Yellow River experienced serious shrinkage, which has decreased the flood conveyance of the channel and the sediment carrying capacity of the flow, raised the water levels of floods, and, thus, severely threatened the safety of flood control along the river. The completion of Xiaolangdi Dam in 1999 could help mitigate the channel shrinkage problem, but the situation has not changed yet. This paper analyses the characteristics, mechanisms, and conditions resulting in channel shrinkage, points out channel instabilities, and puts forward approaches of channel rehabilitation.

  5. INTER-GROUP IMAGE REGISTRATION BY HIERARCHICAL GRAPH SHRINKAGE.

    Science.gov (United States)

    Ying, Shihui; Wu, Guorong; Liao, Shu; Shen, Dinggang

    2013-12-31

    In this paper, we propose a novel inter-group image registration method to register different groups of images (e.g., young and elderly brains) simultaneously. Specifically, we use a hierarchical two-level graph to model the distribution of entire images on the manifold, with intra-graph representing the image distribution in each group and the inter-graph describing the relationship between two groups. Then the procedure of inter-group registration is formulated as a dynamic evolution of graph shrinkage. The advantage of our method is that the topology of entire image distribution is explored to guide the image registration. In this way, each image coordinates with its neighboring images on the manifold to deform towards the population center, by following the deformation pathway simultaneously optimized within the graph. Our proposed method has been also compared with other state-of-the-art inter-group registration methods, where our method achieves better registration results in terms of registration accuracy and robustness.

  6. An improved adaptive wavelet shrinkage for ultrasound despeckling

    Indian Academy of Sciences (India)

    P Nirmala Devi; R Asokan

    2014-08-01

    Ultrasound imaging is the most widely used medical diagnostic technique for clinical decision making, due to its ability to make real time imaging for moving structures, low cost and safety. However, its usefulness is degraded by the presence of signal dependent speckle noise. Several wavelet-based denoising schemes have been reported in the literature for the removal of speckle noise. This study proposes a new and improved adaptive wavelet shrinkage in the translational invariant domain. It exploits the knowledge of the correlation of the wavelet coefficients within and across the resolution scales. A preliminary coefficient classification representing useful image information and noise is performed with a novel inter-scale dependency measure. The spatial context adaptation of the wavelet coefficients within a subband is achieved by a local spatial adaptivity indicator, determined by using a truncation threshold. A weighted signal variance is estimated based on this measure and used in the determination of a subband adaptive threshold. The proposed thresholding function aims to reduce the fixed bias of the soft thresholding approach. Experiments conducted with the proposed filter are compared with the existing filtering algorithms in terms of Peak-Signal to Noise Ratio (PSNR), Mean Square Error (MSE), Structural Similarity IndexMeasure (SSIM), Equivalent Number of Looks (ENL) and Edge Preservation Index (EPI). A comparison of the results shows that the proposed filter achieves an improvement in terms of quantitative measures and in terms of visual quality of the images.

  7. Super-resolution optical telescopes with local light diffraction shrinkage

    Science.gov (United States)

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-12-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems.

  8. Shrinkage, abrasion, erosion and sorption of clay plasters

    Directory of Open Access Journals (Sweden)

    Minke, G.

    2011-09-01

    Full Text Available At the Buildung Research Institute (FEB, Faculty of Architecture, University of Kassel, Germany, in the last years several hundred tests were made to study the characteristics of different loam mortars in respect of their linear shrinkage, absorption of humidity and their resistance against abrasion and erosion. In order to get data about abrasion and erosion new test methods and special apparatusses were developed. The mortars tested, chosen from the market, showed extremely varying test results.

    En el Laboratorio de Construcciones Experimentales (FEB de la Facultad de Arquitectura, Universidad de Kassel, Alemania, fueron testeados cientos de diferentes pruebas de revoque de barro para estudiar su contracción durante el secado, su absorción de humedad y su resistencia contra abrasión, erosión y absorción. Para recibir datos sobre abrasión y erosión, nuevas aparatos y metodos fueron desarrollados. Los resultados de los revoques comprados en el mercado muestran gran diferencias en los valores.

  9. An Iterative Shrinkage Approach to Total-Variation Image Restoration

    CERN Document Server

    Michailovich, Oleg

    2009-01-01

    The problem of restoration of digital images from their degraded measurements plays a central role in a multitude of practically important applications. A particularly challenging instance of this problem occurs in the case when the degradation phenomenon is modeled by an ill-conditioned operator. In such a case, the presence of noise makes it impossible to recover a valuable approximation of the image of interest without using some a priori information about its properties. Such a priori information is essential for image restoration, rendering it stable and robust to noise. Particularly, if the original image is known to be a piecewise smooth function, one of the standard priors used in this case is defined by the Rudin-Osher-Fatemi model, which results in total variation (TV) based image restoration. The current arsenal of algorithms for TV-based image restoration is vast. In the present paper, a different approach to the solution of the problem is proposed based on the method of iterative shrinkage (aka i...

  10. Polymerization Shrinkage and Flexural Modulus of Flowable Dental Composites

    Directory of Open Access Journals (Sweden)

    Janaína Cavalcanti Xavier

    2010-09-01

    Full Text Available Linear polymerization shrinkage (LPS, flexural strength (FS and modulus of elasticity (ME of low-viscosity resin composites (Admira Flow™, Grandio Flow™/VOCO; Filtek Z350 Flow™/3M ESPE; Tetric Flow™/Ivoclar-Vivadent was evaluated using a well-established conventional micro-hybrid composite as a standard (Filtek Z250™/3M ESPE. For the measurement of LPS, composites were applied to a cylindrical metallic mould and polymerized (n = 8. The gap formed at the resin/mould interface was observed using SEM (1500×. For FS and ME, specimens were prepared according to the ISO 4049 specifications (n = 10. Statistical analysis of the data was performed with one-way ANOVA and the Tukey test. The conventional resin presented significantly lower LPS associated with high FS and ME, but only the ME values of the conventional resin differed significantly from the low-viscosity composites. The relationship between ME and LPS of low-viscosity resin composites when used as restorative material is a critical factor in contraction stress relief and marginal leakage.

  11. Shrinkage/swelling of compacted clayey loose and dense soils

    Science.gov (United States)

    Nowamooz, Hossein; Masrouri, Farimah

    2009-11-01

    This Note presents an experimental study performed on expansive compacted loose and dense samples using osmotic oedometers. Several successive wetting and drying cycles were applied in a suction range between 0 and 8 MPa under different values of constant net vertical stress (15, 30, and 60 kPa). During the suction cycles, the dense samples showed cumulative swelling strains, while the loose samples showed volumetric shrinkage accumulation. At the end of the suction cycles, the volumetric strains converged to an equilibrium stage that indicated elastic behavior of the swelling soil for any further hydraulic variations. At this stage, the compression curves for the studied soil at the different imposed suctions (0, 2, and 8 MPa) converged towards the saturated state curve for the high applied vertical stresses. We defined this pressure as the saturation stress(P). The compression curves provided sufficient data to examine the soil mechanical behavior at the equilibrium stage. To cite this article: H. Nowamooz, F. Masrouri, C. R. Mecanique 337 (2009).

  12. Flood control and shrinkage in the Haihe River Mouth

    Institute of Scientific and Technical Information of China (English)

    胡世雄; 王兆印; 李行伟

    2001-01-01

    Because of overusing water resources in the upper and middle reaches of the Haihe Basin, less and less water flows to the river mouth. The Haihe River flow is cut off in most time of the seasons, sediment deposited in the river mouth channel is rarely scoured away, and many of the river mouth channels have been shrinking quickly. The discharge capacity of the channel is consequently reduced greatly, which results in more and more serious flood hazard. Many tide gates have been built for storing fresh water and preventing the salty and turbid water. The channel downstream of the gate is silting up and people have to dredge the channel every year before the flood season. This paper studies the laws of the siltation and strategies controlling channel shrinkage. The strategies are digger dredging, trailer dredging, scouring with pumping water or storing tidal water, building double guiding dikes and building a new gate. Comparison of various strategies is performed, suggesting the most effective strategy con

  13. Minerals of expansive and non-shrinkage sulfomineral cements

    Directory of Open Access Journals (Sweden)

    Samchenko Svetlana V.

    2017-01-01

    Full Text Available Usually to obtain expansive cements sulfoaluminate clinker or mix aluminate clinker with calcium sulfates (gypsum, hemihydrate, anhydrate are used. For these cements ettringite is an important hydration product and kinetic reaction of this phase plays an important role in determinаting performance. The alternative aluminate phases may be ferrite containing ones. This article deals with the composition and properties of solid solution of calcium sulfoaluminate, sulfoferrite and sulfoaluminoferrite cements. It was studied an influence of calcium sulfate on structure and properties of calcium aluminate and ferrite phases, and their stability under high temperatures. Beside that the properties of cements containing these phases were studied. The investigation of hydration and properties of sulfomineral cements shows that ettringite and its analogies are formed in such way to provide expansion and compression of cement stone. Degree of expansion and self-stressing of cement stone depends not only on composition of sulfated minerals but on ratio and types of clinkers. The higher expansion is reached by the use of high alite containing Portland cement clinker together with sulfoaluminate or sulfoalumoferrite one, the lower expansion is reached by addition of sulfoalumoferrite and sulfoferrite clinkers. These cements are classified as self-stressing, expansive or shrinkage-compensating ones depend on the degree of their expansion after 28 days of curing.

  14. Laser-induced scleral shrinkage for refractive surgery

    Science.gov (United States)

    Ren, Qiushi; Simon, Gabriel; Parel, Jean-Marie A.; Shen, Jin-Hui

    1994-06-01

    We investigate the laser refractive scleroplasty (LRS) as a potential minimal-invasive method for correcting post-operative astigmatism. The scleral shrinkage near limbus was induced on 6 cadaver eyes using a 200 micrometers fiber optic probe coupled to a pulsed Ho:YAG laser. The diameter of the treatment spot was 0.8 mm. The output energy measured at tip was 60.2+/- 0.6 mJ. The treatments consisted of multiple sector patterns placed along the major axis of astigmatism parallel to the limbus, and round patterns placed along the limbus. Three treatment spots were applied on each side of the sector. The separation among sectors and limbus is 1 mm. Keratometry and topography of the cornea were measured after each sector or round pattern treatment. Effect of 5 and 10 pulses at each treatment spot were compared. Histology was performed to evaluate laser tissue damage. The major axis of astigmatism was shifted 90 degrees after the sector pattern treatment and amount of dioptric change increased when adding a new treatment or using more treatment pulses. However, the spherical equivalent of the eyes was essentially unchanged. The keratometry of the corneas remained the same after the round pattern treatment. Laser refractive scleroplasty may be applied for the correction of post-operative astigmatism.

  15. Autogenous bone graft combined with polylactic polyglycolic acid polymer for treatment of dehiscence around immediate dental implants.

    Science.gov (United States)

    Hassan, Khalid S

    2009-11-01

    The use of composite bone grafts in dehiscence defects around immediate dental implants are aimed at improving the outcome of the regenerative process. The present study was designed to evaluate the efficacy of combinations of autogenous bone graft with a synthetic copolymer polylactic and polyglycolic acid (Fisiograft) on bone healing of buccal dehiscence defects around immediate dental implants. Sixteen adult male patients who each received an immediate implant for a single tooth replacement at a maxillary anterior or premolar site were included in this study. Patients were divided into 2 groups. One group received immediate dental implants augmented with autogenous bone graft combined with Fisiograft. The other group received immediate dental implants augmented with autogenous bone graft alone. The results revealed that both treatment modalities led to significant improvements for the primary outcome regarding bone fill as well as a significant reduction of probing pocket depth and gain of attachment level. Moreover, there were slightly statistically significant differences between the groups. In conclusion, the combination of autogenous bone graft and Fisiograft showed a slight superiority to autogenous bone graft alone, suggesting that it could be an optimum bone substitute for treatment of dehiscence around immediate dental implant.

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

    Directory of Open Access Journals (Sweden)

    Liang S

    2017-08-01

    Full Text Available Shuzhen Liang,1,2 Kecheng Xu,1,2 Lizhi Niu,1,2 Xiaohua Wang,1 Yingqing Liang,1 Mingjie Zhang,3 Jibing Chen,1,2 Mao Lin1,2 1Department of Central Laboratory, Fuda Cancer Hospital, Jinan University School of Medicine, Guangzhou, Guangdong, China; 2Fuda Cancer Institute, Guangzhou, Guangdong, China; 3Hank Bioengineering Co., Ltd, Shenzhen, China Abstract: 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. Keywords: clinical outcome, autogeneic, allogeneic, natural killer cells, recurrent breast cancer

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

    Science.gov (United States)

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

    2017-06-23

    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.

  18. Study of swelling-shrinkage regularity of montmorillonite crystal and its relation with matric suction

    Institute of Scientific and Technical Information of China (English)

    谭罗荣; 孔令伟

    2001-01-01

    The swell-shrinking mineral of saturated and unsaturated expansive soil has important effect on engineering mechanical behavior. Based on the swelling-shrinkage change regularity of montmorillonite crystal in this paper, the actions between various interlayers of montmorillonite crystal are generally summarized as two kinds of action potentials-shrinkage potential and swelling potential. Moreover, through the experimental research and analysis, the expression formula for variations of the swelling potential and shrinkage potential with interlayer distance is presented, and the regularity of matric suction variations with interlayer distance is also obtained for unsaturated expansive soil. It may provide a new theoretical basis and research path for further research on the swelling-shrinkage mechanism of expansive soil and matric suction potential of unsaturated soil.

  19. Measurement of composite shrinkage using a fibre optic Bragg grating sensor.

    Science.gov (United States)

    Milczewski, M S; Silva, J C C; Paterno, A S; Kuller, F; Kalinowski, H J

    2007-01-01

    Fibre Bragg grating is used to determine resin-based composite shrinkage. Two composite resins (Freedom from SDI and Z100 from 3M) were tested to determine the polymerization contraction behaviour. Each sample of resin was prepared with an embedded fibre Bragg grating. A LED activation unit with wavelength from 430 nm to 470 nm (Dabi Atlante) was used for resin polymerization. The wavelength position of the peak in the optical reflection spectra of the sensor was measured. The wavelength shift was related to the shrinkage deformation of the samples. Temperature and strain evolution during the curing phase of the material was monitored. The shrinkage in the longitudinal direction was 0.15 +/- 0.02% for resin Z100 (3M) and 0.06+/-0.01% for Freedom (SDI); two-thirds of shrinkage occurred after the first 50 s of illumination.

  20. Shrinkage and Expansive Strain of Concrete with Fly Ash and Expansive Agent

    Institute of Scientific and Technical Information of China (English)

    GAO Peiwei; LU Xiaolin; TANG Mingshu

    2009-01-01

    The effects of fly ash and MgO-type expansive agent on the shrinkage and expan-sive strain of concrete with high magnesia cement were investigated. The results show that high volumes of fly ash may reduce the shrinkage strain of concrete and inhibit the expansive strain of concrete with MgO-type expansive agent, but can not eliminate the shrinkage of concrete. MgO-type expansive agent may produce expansive strain and compensate the shrinkage strain of concrete, re-lieve the cracking risk, but the hydration product of magnesia tends to get together in paste and pro-duce expansive cracking of concrete with high magnesia content according to SEM observation.

  1. Numerical Simulation on Open Wellbore Shrinkage and Casing Equivalent Stress in Bedded Salt Rock Stratum

    Directory of Open Access Journals (Sweden)

    Jianjun Liu

    2013-01-01

    Full Text Available Most salt rock has interbed of mudstone in China. Owing to the enormous difference of mechanical properties between the mudstone interbed and salt rock, the stress-strain and creep behaviors of salt rock are significantly influenced by neighboring mudstone interbed. In order to identify the rules of wellbore shrinkage and casings equivalent stress in bedded salt rock stratum, three-dimensional finite difference models were established. The effects of thickness and elasticity modulus of mudstone interbed on the open wellbore shrinkage and equivalent stress of casing after cementing operation were studied, respectively. The results indicate that the shrinkage of open wellbore and equivalent stress of casings decreases with the increase of mudstone interbed thickness. The increasing of elasticity modulus will reduce the shrinkage of open wellbore and casing equivalent stress. Research results can provide the scientific basis for the design of mud density and casing strength.

  2. Numerical simulation on open wellbore shrinkage and casing equivalent stress in bedded salt rock stratum.

    Science.gov (United States)

    Liu, Jianjun; Zhang, Linzhi; Zhao, Jinzhou

    2013-01-01

    Most salt rock has interbed of mudstone in China. Owing to the enormous difference of mechanical properties between the mudstone interbed and salt rock, the stress-strain and creep behaviors of salt rock are significantly influenced by neighboring mudstone interbed. In order to identify the rules of wellbore shrinkage and casings equivalent stress in bedded salt rock stratum, three-dimensional finite difference models were established. The effects of thickness and elasticity modulus of mudstone interbed on the open wellbore shrinkage and equivalent stress of casing after cementing operation were studied, respectively. The results indicate that the shrinkage of open wellbore and equivalent stress of casings decreases with the increase of mudstone interbed thickness. The increasing of elasticity modulus will reduce the shrinkage of open wellbore and casing equivalent stress. Research results can provide the scientific basis for the design of mud density and casing strength.

  3. Marginal adaptation of a low-shrinkage silorane-based composite: A SEM-analysis

    DEFF Research Database (Denmark)

    Schmidt, Malene; Bindslev, Preben Hørsted; Poulsen, Sven;

    2012-01-01

    shrinkage, has been marketed. Objective. To investigate whether reduced polymerization shrinkage improves the marginal adaptation of composite restorations. Material and methods. A total of 156 scanning electron microscopy (SEM) pictures (78 baseline, 78 follow-up) of the occlusal part of Class II......-casts of the restorations were used for SEM pictures at x 16 magnification. Pictures from baseline and follow-up (398 days, SD 29 days) were randomized and the examiner was blinded to the material and the age of the restoration. Stereologic measurements were used to calculate the length and the width of the marginal......Introduction. Shrinkage during polymerization of resin-based composite materials may lead to gap formation and hamper the marginal adaptaion of the restorations. To reduce the problem of polymerization shrinkage, a new composite material (Filtek™ Silorane, 3M-ESPE, Germany), with a reduced...

  4. Development of high shrinkage polyethylene terephthalate (PET) shape memory polymer tendons for concrete crack closure

    Science.gov (United States)

    Teall, Oliver; Pilegis, Martins; Sweeney, John; Gough, Tim; Thompson, Glen; Jefferson, Anthony; Lark, Robert; Gardner, Diane

    2017-04-01

    The shrinkage force exerted by restrained shape memory polymers (SMPs) can potentially be used to close cracks in structural concrete. This paper describes the physical processing and experimental work undertaken to develop high shrinkage die-drawn polyethylene terephthalate (PET) SMP tendons for use within a crack closure system. The extrusion and die-drawing procedure used to manufacture a series of PET tendon samples is described. The results from a set of restrained shrinkage tests, undertaken at differing activation temperatures, are also presented along with the mechanical properties of the most promising samples. The stress developed within the tendons is found to be related to the activation temperature, the cross-sectional area and to the draw rate used during manufacture. Comparisons with commercially-available PET strip samples used in previous research are made, demonstrating an increase in restrained shrinkage stress by a factor of two for manufactured PET filament samples.

  5. Mechanical properties, volumetric shrinkage and depth of cure of short fiber-reinforced resin composite.

    Science.gov (United States)

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

    2016-01-01

    The mechanical properties, volumetric shrinkage and depth of cure of a short fiber-reinforced resin composite (SFRC) were investigated in this study and compared to both a bulk fill resin composite (BFRC) and conventional glass/ceramic-filled resin composite (CGRC). Fracture toughness, flexural properties, volumetric shrinkage and depth of cure of the SFRC, BFRC and CGRC were measured. SFRC had significantly higher fracture toughness than BFRCs and CGRCs. The flexural properties of SFRC were comparable with BFRCs and CGRCs. SFRC showed significantly lower volumetric shrinkage than the other tested resin composites. The depth of cure of the SFRC was similar to BFRCs and higher than CGRCs. The data from this laboratory investigation suggests that SFRC exhibits improvements in fracture toughness, volumetric shrinkage and depth of cure when compared with CGRC, but depth of cure of SFRC was similar to BFRC.

  6. Influence of Technological Parameters of Furane Mixtures on Shrinkage Creation in Ductile Cast Iron Castings

    Directory of Open Access Journals (Sweden)

    Vasková I.

    2014-10-01

    Full Text Available Ductile cast iron (GS has noticed great development in last decades and its boom has no analogue in history humankind. Ductile iron has broaden the use of castings from cast iron into areas, which where exclusively domains for steel castings. Mainly by castings, which weight is very high, is the propensity to shrinkage creation even higher. Shrinkage creation influences mainly material, construction of casting, gating system and mould. Therefore, the main realized experiment was to ascertain the influence of technological parameters of furane mixture on shrinkage creation in castings from ductile iron. Together was poured 12 testing items in 3 moulds forto determine and compare the impact of various technological parameters forms the propensity for shrinkage in the casting of LGG.

  7. Strength and Drying Shrinkage of Alkali-Activated Slag Paste and Mortar

    Directory of Open Access Journals (Sweden)

    Mao-chieh Chi

    2012-01-01

    Full Text Available The aim of this study is to investigate the strengths and drying shrinkage of alkali-activated slag paste and mortar. Compressive strength, tensile strength, and drying shrinkage of alkali-activated slag paste and mortar were measured with various liquid/slag ratios, sand/slag ratios, curing ages, and curing temperatures. Experimental results show that the higher compressive strength and tensile strength have been observed in the higher curing temperature. At the age of 56 days, AAS mortars show higher compressive strength than Portland cement mortars and AAS mortars with liquid/slag ratio of 0.54 have the highest tensile strength in all AAS mortars. In addition, AAS pastes of the drying shrinkage are higher than AAS mortars. Meanwhile, higher drying shrinkage was observed in AAS mortars than that observed comparable Portland cement mortars.

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

    OpenAIRE

    Shamsad Ahmad; Ahmed Zubair; Mohammed Maslehuddin

    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 w...

  9. Polymerization Shrinkage of Dental Composites Registered by a Video-imaging Device. A pilot study

    OpenAIRE

    Afaag, Ali; Sandelin, Benjamin

    2014-01-01

    The use of composite materials for dental fillings has become more common due to demands for more esthetic filling materials and a national ban against using mercury-containing products, among others dental amalgam. However, one of the drawbacks with composites is their polymerization shrinkage. Filler particles are incorporated into composites among other things to minimize the shrinkage. The sizes of the filler particles have in recent years become smaller and most composites have nano-part...

  10. Study on a New Method of Reducing the Water Shrinkage of Rabbit Hair Knitted Fabrics

    Institute of Scientific and Technical Information of China (English)

    PAN Fu-kui; WANG Shan-yuan; LONG Min; YANG Guang-ming

    2005-01-01

    In order to reduce the water shrinkage of rabbit hair knitted fabrics, a new method is developed, which is blending rabbit hairs with a little bit of blaze. The sericin on the blaze which can swell and melt in hot and wet condition[1] can cohere the rabbit hairs through special processing. So the relative movement among fibers could be restricted. The testing results show that the water shrinkage of rabbit hair knitted fabrics can be greatly reduced after processed.

  11. Astrocytic mechanisms explaining neural-activity-induced shrinkage of extraneuronal space

    DEFF Research Database (Denmark)

    Østby, Ivar; Øyehaug, Leiv; Einevoll, Gaute T;

    2009-01-01

    Neuronal stimulation causes approximately 30% shrinkage of the extracellular space (ECS) between neurons and surrounding astrocytes in grey and white matter under experimental conditions. Despite its possible implications for a proper understanding of basic aspects of potassium clearance and astr......Neuronal stimulation causes approximately 30% shrinkage of the extracellular space (ECS) between neurons and surrounding astrocytes in grey and white matter under experimental conditions. Despite its possible implications for a proper understanding of basic aspects of potassium clearance...

  12. Influence of rare earths on shrinkage porosity in thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2009-01-01

    Ductile cast iron has been cast in test bars with thickness from 2 to 10 mm. The rare earth elements La and Ce have been added to some of the castings to evaluate their influence on microstructure and shrinkage tendency. Both La and Ce increased the graphite nodule count, especially for thickness...... the temperature T-1, which is controlled by the growth of off-eutectic austenite dendrites, increased the shrinkage tendency....

  13. Denoising of Mechanical Vibration Signals Using Quantum-Inspired Adaptive Wavelet Shrinkage

    OpenAIRE

    2014-01-01

    The potential application of a quantum-inspired adaptive wavelet shrinkage (QAWS) technique to mechanical vibration signals with a focus on noise reduction is studied in this paper. This quantum-inspired shrinkage algorithm combines three elements: an adaptive non-Gaussian statistical model of dual-tree complex wavelet transform (DTCWT) coefficients proposed to improve practicability of prior information, the quantum superposition introduced to describe the interscale dependencies of DTCWT co...

  14. Pore Structure and Influence of Recycled Aggregate Concrete on Drying Shrinkage

    OpenAIRE

    Yuanchen Guo; Jueshi Qian; Xue Wang

    2013-01-01

    Pore structure plays an important role in the drying shrinkage of recycled aggregate concrete (RAC). High-precision mercury intrusion and water evaporation were utilized to study the pore structure of RAC, which has a different replacement rate of recycled concrete aggregate (RCA), and to analyze its influence on drying shrinkage. Finally, a fractal-dimension calculation model was established based on the principles of mercury intrusion and fractal-geometry theory. Calculations were performed...

  15. Tumor shrinkage by cyclopamine tartrate through inhibiting hedgehog signaling

    Institute of Scientific and Technical Information of China (English)

    Qipeng Fan; Arash Garrossian; Massoud Garrossian; Dale Gardner; Jingwu Xie; Dongsheng Gu; Miao He; Hailan Liu; Tao Sheng; Guorui Xie; Ching-xin Li; Xiaoli Zhang; Brandon Wainwright

    2011-01-01

    The link of hedgehog (Hh) signaling activation to human cancer and synthesis of a variety of Hh signaling inhibitors raise great expectation that inhibiting Hh signaling may be effective in human cancer treatment. Cyclopamine (Cyc), an alkaloid from the Veratrum plant, is a specific natural product inhibitor of the Hh pathway that acts by targeting smoothened (SMO) protein. However, its poor solubility, acid sensitivity, and weak potency relative to other Hh antagonists prevent the clinical development of Cyc as a therapeutic agent. Here, we report properties of cyclopamine tartrate salt (CycT) and its activities in Hh signaling-mediated cancer in vitro and in vivo. Unlike Cyc, CycT is water soluble (5-10 mg/mL). The median lethal dose (LD) of CycT was 62.5 mg/kg body weight compared to 43.5 mg/kg for Cyc, and the plasma half-life (T) of CycT was not significantly different from that of Cyc. We showed that CycT had a higher inhibitory activity for Hh signaling-dependent motor neuron differentiation than did Cyc (IC = 50nmol/L for CycT vs. 300 nmol/L for Cyc). We also tested the antitumor effectiveness of these Hh inhibitors using two mouse models of basal cell carcinomas (K14cre:Ptch1and K14cre:SmoM2). After topical application of CycT or Cyc daily for 21 days, we found that all CycT-treated mice had tumor shrinkage and decreased expression of Hh target genes. Taken together, we found that CycT is an effective inhibitor of Hh signaling-mediated carcinogenesis.

  16. Maxillary sinus floor elevation surgery with BioOss (R) mixed with a bone marrow concentrate or autogenous bone : test of principle on implant survival and clinical performance

    NARCIS (Netherlands)

    Rickert, D.; Vissink, A.; Slot, Jan; Sauerbier, S.; Meijer, H. J. A.; Raghoebar, G. M.

    2014-01-01

    The purpose of this study was to assess implant survival and 1-year clinical performance of implants placed in the posterior maxilla that had been subjected to maxillary sinus floor elevation surgery with bovine bone mineral (BioOss (R)) mixed with autogenous bone marrow concentrate or autogenous bo

  17. Autogenous bone graft and ePTFE membrane in the treatment of peri-implantitis. II. Stereologic and histologic observations in cynomolgus monkeys

    DEFF Research Database (Denmark)

    Schou, Søren; Holmstrup, Palle; Skovgaard, Lene Theil

    2003-01-01

    autogenous bone graft; guided bone regeneration; histology; membrane; non-human primates; oral implants; osseointegration; pathalogy; peri-implantitis; stereology; treatment......autogenous bone graft; guided bone regeneration; histology; membrane; non-human primates; oral implants; osseointegration; pathalogy; peri-implantitis; stereology; treatment...

  18. Drying Shrinkage of Cement-Based Materials Under Conditions of Constant Temperature and Varying Humidity

    Institute of Scientific and Technical Information of China (English)

    MA Bao-guo; WEN Xiao-dong; WANG Ming-yuan; YAN Jia-jia; Gao Xiao-jian

    2007-01-01

    Currently,deformations along the central axis of specimens were usually measured under fixed environmental conditions. Seldom were the effects of environmental factors on the drying-shrinkage deformation of cement-based material considered. For this paper, the drying-shrinkage deformation at different w/b ratios and different additions to mortars was investigated under different environments at a temperature of 20 ℃ and humidity ranging from 100% to 50%. The specimens were cured in water for 28 days before measurement. The results illustrate that mortar shows much less shrinkage under various drying conditions when a lower w/b ratio is adopted. With a decrease in relative humidity the speed of drying-shrinkage becomes gradually lower. The addition of silica fume reduces the drying-shrinkage of mortar under higher relative humidity, because the pore structure of mortar with silica fume becomes more refined. The addition of fly ash increases the total porosity and the volume of coarse pores in the mortar. The drying-shrinkage of mortar under different conditions increases with the addition of more of fly ash.

  19. Conversion-dependent shrinkage stress and strain in dental resins and composites.

    Science.gov (United States)

    Stansbury, Jeffrey W; Trujillo-Lemon, Marianela; Lu, Hui; Ding, Xingzhe; Lin, Yan; Ge, Junhao

    2005-01-01

    The placement of dental composites is complicated by the contraction that accompanies polymerization of these materials. The resulting shrinkage stress that develops during cure of a bonded restoration can induce defects within the composite, the tooth or at the interface resulting in compromised clinical performance and/or esthetics. In light of the substantial efforts devoted to understanding and attempting to control shrinkage stress and strain in dental composite restoratives, this paper offers a perspective on the conversion dependent development of shrinkage and stress. The relationships between polymer property development and the physical evolution of the network structures associated with dental polymers as well as the interrelated kinetics of the photopolymerization reaction process are examined here. Some of the methods used to assess conversion in dental resins and composites are considered. In particular, newly introduced techniques that allow real time analysis of conversion by near-infrared spectroscopy to be coupled directly to simultaneous dynamic measurements of either shrinkage stress or strain are described. The results are compared with reports from the dental materials literature as well as complementary studies in other related fields of polymer science. The complex, nonlinear correlation between conversion, shrinkage and stress are highlighted. A brief review of some of the materials-based approaches designed to minimize polymerization shrinkage and stress is also provided.

  20. Effect on effective diffusion coefficients and investigation of shrinkage during osmotic dehydration of apricot

    Energy Technology Data Exchange (ETDEWEB)

    Togrul, Inci Turk; Ispir, Ayse [Firat University, Engineering Faculty, Department of Chemical Engineering, 23279 Elazig (Turkey)

    2007-10-15

    This article represents the results of the variation in density and shrinkage of apricots during its osmotic dehydration. Shrinkage was investigated by means of dimensionless volume, diameter and length. Various osmotic agents such as sucrose, glucose, fructose, maltodextrin and sorbitol were used. It was found that the shrinkage of apricots could be well correlated with the moisture content of the sample during osmotic dehydration. The relationship between dimensionless parameters and moisture content was investigated by using eight non-linear models for each osmotic agent. It was find that the following proposed model can be confidently use for explaining the effect of shrinkage during osmotic dehydration of apricots.V/V{sub 0},D/D{sub 0},L/L{sub 0},{rho}/{rho}{sub 0}=a+b. exp (cX)+d. exp (e.X{sup f})In addition, the osmotic dehydration kinetics of apricots with and without shrinkage was studied. The effective diffusivities calculated from the diffusional model with and without shrinkage varied from 10.342 x 10{sup -9} m{sup 2}/s to 5.139 x 10{sup -9} and from 1.755 x 10{sup -10} and 0.767 x 10{sup -10} m{sup 2}/s, respectively. (author)

  1. Microcomputed Tomography Evaluation of Polymerization Shrinkage of Class I Flowable Resin Composite Restorations.

    Science.gov (United States)

    Sampaio, C S; Chiu, K-J; Farrokhmanesh, E; Janal, M; Puppin-Rontani, R M; Giannini, M; Bonfante, E A; Coelho, P G; Hirata, R

    The present study aimed to characterize the pattern and volume of polymerization shrinkage of flowable resin composites, including one conventional, two bulk fill, and one self-adhesive. Standardized class I preparations (2.5 mm depth × 4 mm length × 4 mm wide) were performed in 24 caries-free human third molars that were randomly divided in four groups, according to the resin composite and adhesive system used: group 1 = Permaflo + Peak Universal Bond (PP); group 2 = Filtek Bulk Fill + Scotchbond Universal (FS); group 3 = Surefil SDR + XP Bond (SX); and group 4 = Vertise flow self-adhering (VE) (n=6). Each tooth was scanned three times using a microcomputed tomography (μCT) apparatus. The first scan was done after the cavity preparation, the second after cavity filling with the flowable resin composite before curing, and the third after it was cured. The μCT images were imported into three-dimensional rendering software, and volumetric polymerization shrinkage percentage was calculated for each sample. Data were submitted to one-way analysis of variance and post hoc comparisons. No significant difference was observed among PP, FS, and VE. SX bulk fill resin composite presented the lowest values of volumetric shrinkage. Shrinkage was mostly observed along the occlusal surface and part of the pulpal floor. In conclusion, polymerization shrinkage outcomes in a 2.5-mm deep class I cavity were material dependent, although most materials did not differ. The location of shrinkage was mainly at the occlusal surface.

  2. A new method for chill and shrinkage control in ladle treated ductile iron

    Institute of Scientific and Technical Information of China (English)

    Torbj(o)rn Skaland

    2006-01-01

    The paper is undertaken with the objective of describing a new method for treating ductile cast iron in a ladle process, where the main objective is to minimize formation of eutectic carbides and shrinkage porosity during solidification. The suppression of carbide formation is associated with the nucleating properties of the nodularizer and inoculant alloys. By nucleating properties it is understood the number and potency of nuclei formed by an alloy addition. The nodularizer and inoculant additions also influence ductile iron solidification shrinkage. Some alloys may give good protection against shrinkage while others tend to promote more shrinkage.The use of vanous rare earth elements is found to have a pronounced impact on these conditions. It has been discovered that the use of pure lanthanum as the primary rare earth source in the magnesium ferrosilicon nodularizer surprisingly further improves the performance of the ductile iron ladle treatment method compared to similar methods using cerium or mishmetal bearing nodularizers. The nucleating properties are substantially improved and the risk for carbides (chill) and shrinkage formation in the sandwich or tundish ladle treated ductile iron is then minimized.The paper describes this new ladle treatment concept in detail, and gives examples from successful testing of the new nodularizing technology and how it simultaneously affects and minimizes critical ductile iron chill and shrinkage tendencies.

  3. Transient brain shrinkage in infantile spasms after ACTH treatment. Report of two cases.

    Science.gov (United States)

    Maekawa, K; Ohta, H; Tamai, I

    1980-02-01

    This is the report of two cases of infantile spasms, manifesting transient brain shrinkage in computerized tomography (CT) after ACTH treatment. ACTH was given for 8 weeks to a 8-months-old Japanese girl with infantile spasms. First CT performed at 2 weeks after the final ACTH injection, displayed moderate brain shrinkage. Second CT at 4 months showed marked diminution of the shrinkage. ACTH was also given for 8 weeks to a 14 months old Japanese boy with infantile spasms. First CT, just before ACTH treatment, showed mild cortical atrophy, the second at 7 days after the final ACTH injection revealed marked brain shrinkage and moderate ventricular dilatation, and the third at 2 months, disclosed mild improvement of the shrinkage. ACTH or corticoateroid has widespread effects on the developing nervous system. In animal experiments, ACTH or steroids interfere with brain growth of young rats. CT findings of transient brain shrinkage in a child with infantile spasms might suggest that intensive treatment with ACTH or steroids in infancy interferes with brain growth as seen in the results of animal experiments.

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

    Science.gov (United States)

    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.

  5. A comparison of autogenous theories for the origin of eukaryotic cells.

    Science.gov (United States)

    Baum, David A

    2015-12-01

    Eukaryotic cells have many unique features that all evolved on the stem lineage of living eukaryotes, making it difficult to reconstruct the order in which they accumulated. Nuclear endosymbiotic theories hold that three prokaryotes (nucleus, cytoplasm, and mitochondrion) came together to form a eukaryotic cell, whereas autogenous models hold that the nucleus and cytoplasm formed through evolutionary changes in a single prokaryotic lineage. Given several problems with nuclear endosymbiotic theories, this review focuses on autogenous models. Until recently all autogenous models assumed an outside-in (OI) topology, proposing that the nuclear envelope was formed from membrane-bound vesicles within the original cell body. Buzz Baum and I recently proposed an inside-out (IO) alternative, suggesting that the nucleus corresponds to the original cell body, with the cytoplasmic compartment deriving from extracellular protrusions. In this review, I show that OI and IO models are compatible with both mitochondria early (ME) or mitochondria late (ML) formulations. Whereas ME models allow that the relationship between mitochondria and host was mutualistic from the outset, ML models imply that the association began with predation or parasitism, becoming mutualistic later. In either case, the mutualistic interaction that eventually formed was probably syntrophic. Diverse features of eukaryotic cell biology align well with the IOME model, but it would be premature to rule out the OIME model. ML models require that phagocytosis, a complex and energy expensive process, evolved before mitochondria, which seems unlikely. Nonetheless, further research is needed, especially resolution of the phylogenetic affinities of mitochondria. © 2015 Botanical Society of America.

  6. Autogenous bone block in the treatment of teeth with hopeless prognosis

    Directory of Open Access Journals (Sweden)

    Nymphea Pandit

    2012-01-01

    Full Text Available Background: Autogenous bone graft, although considered as a gold standard, has been relegated to background because of limited quantity and donor site morbidity. Revival of interest in its use has been reflected by its tremendous capacity for regeneration in less than ideal situation. Bone blocks have been used for implant site augmentation, with varied success. Aim: Aim of the study was to evaluate the efficacy of autogenous bone block in the regeneration of bone, for saving teeth with a hopeless prognosis. Settings and Design: A total of six patients and 12 sites with grade II and III mobile teeth were treated with autogenous bone blocks and fiber splinting. Subjects and Methods: Attachment loss, probing depths, and radiographic bone loss were recorded at baseline and at 12 months interval. Statistical Analysis Used: The Student paired t test was used for evaluation of the changes from baseline to 12 months. Results: At 12 months post-operatively, there was a highly significant amount of bone gain as compared to the baseline. The mean amount of bone loss reduced from 9.41 ± 1.16 to 5.41 ± 1.01. The clinical attachment loss reduced from 7.37 ± 1.24 mm to 3.79 ± 0.89 mm and probing depth reduced from 7 ± 1.67 mm to 5.5 ± 0.63 mm. The grafted bone was observed to have been incorporated with the host bone in most of the sites as evidenced by radiographs. Conclusions: For teeth with hopeless prognosis, this method can be considered to be a very viable alternative to extraction and replacement by costly implants.

  7. Evaluation of ABM/P-15 versus autogenous bone in an ovine lumbar interbody fusion model.

    Science.gov (United States)

    Sherman, Blake P; Lindley, Emily M; Turner, A Simon; Seim, Howard B; Benedict, James; Burger, Evalina L; Patel, Vikas V

    2010-12-01

    A prospective, randomized study was performed in an ovine model to compare the efficacy of an anorganic bovine-derived hydroxyapatite matrix combined with a synthetic 15 amino acid residue (ABM/P-15) in facilitating lumbar interbody fusion when compared with autogenous bone harvested from the iliac crest. P-15 is a biomimetic to the cell-binding site of Type-I collagen for bone-forming cells. When combined with ABM, it creates the necessary scaffold to initiate cell invasion, binding, and subsequent osteogenesis. In this study, six adult ewes underwent anterior-lateral interbody fusion at L3/L4 and L4/L5 using PEEK interbody rings filled with autogenous bone at one level and ABM/P-15 at the other level and no additional instrumentation. Clinical CT scans were obtained at 3 and 6 months; micro-CT scans and histomorphometry analyses were performed after euthanization at 6 months. Clinical CT scan analysis showed that all autograft and ABM/P-15 treated levels had radiographically fused outside of the rings at the 3-month study time point. Although the clinical CT scans of the autograft treatment group showed significantly better fusion within the PEEK rings than ABM/P-15 at 3 months, micro-CT scans, clinical CT scans, and histomorphometric analyses showed there were no statistical differences between the two treatment groups at 6 months. Thus, ABM/P-15 was as successful as autogenous bone graft in producing lumbar spinal fusion in an ovine model, and it should be further evaluated in clinical studies.

  8. Augmentation of the rat jaw with autogeneic cortico-cancellous bone grafts and guided tissue regeneration.

    Science.gov (United States)

    Donos, Nikolaos; Kostopoulos, Lambros; Karring, Thorkild

    2002-04-01

    The aim of the present study was to evaluate the effect of augmenting the maxillary alveolar ridge and the lateral aspect of the mandible with onlay autogeneic cortico-cancellous bone grafts that were covered with e-PTFE membranes. The experiment was carried out in 51 rats. In 15 rats, the edentulous maxillary jaw between the incisor and the first molar was augmented by means of an autogeneic ischiac bone graft that was fixed with a gold-coated microimplant. In one side, the graft was covered with an e-PTFE membrane, while the other side, which served as control, was treated without a membrane. In the other 36 rats, the lateral aspect of the mandible was augmented in both sides by means of an autogeneic ischiac bone graft that was fixed with a gold-coated or a titanium microimplant. In one side, the augmented area was covered with an e-PTFE membrane, while the contralateral side was treated without a membrane. Histological analysis at 60, 120 and 180 days after augmentation of the maxilla showed that, in the case of the test sites (where most of the membranes were either exposed or lost), the bone grafts presented extensive resorption and there was a lack of bone continuity between the graft and the recipient site. Similar findings were made at the non-membrane-treated control sides. In the case of augmentation of the mandible with membranes, the bone grafts were not resorbed, but were integrated into newly formed bone at the recipient site. In the control sides, the grafts presented varying degrees of resorption and integration into the recipient bone. It is concluded that, in comparison to bone grafting alone, onlay ischiac bone grafting combined with guided tissue regeneration eliminates the risk of bone graft resorption and ensures integration of the graft into newly formed bone at the recipient site, provided that closure of the operated area can be maintained during healing.

  9. Frontalis Sling Operation using Silicone Rod Compared with Autogenous Fascia Lata for Simple Congenital Ptosis

    Directory of Open Access Journals (Sweden)

    Purnima Rajkarnikar Sthapit

    2014-09-01

    Full Text Available Introduction: To evaluate the cosmetic results and recurrence of unilateral frontalis sling surgery using a silicone rod compared with autogenous fascia lata in cases of simple congenital ptosis. Methods: This is a retrospective comparative study of 59 patients who underwent a frontalis sling operation for congenital ptosis. Patients were divided into two groups according to the sling material used; an autogeneous fascia lata (fl group (n = 24 and a silicone rod group (sl (n = 35. Cosmetic results and recurrence rates were compared between these 2 groups. The cosmetic results of the frontalis sling operation were assessed as good, fair, or poor based on the difference between the Margin Reflex Distance of both eyelids and graded as good if the difference in two eyes was ≤1mm and poor if it was 2mm or more. Recurrence was defined as the conversion of the cosmetic result from good or fair to poor category. Results: At postoperative day seven and 30, MRD of both the groups were good but on three months follow-up MRD of silicon rod group dropped, however it was not statistically significant .Lid contour was good in both the groups, however, lid symmetry was poor in two cases of fascia lata at three months follow-up. Repeat surgery for poor outcome was done in 8.6% of cases in silicon rod and 8.3% of fascia lata group. Conclusions: The frontalis sling operation using either a silicone rod or autogenous fascia lata showed equally good cosmetic results and lower recurrence rate at three months follow up. Keywords: congenital ptosis; fascia lata; frontalis sling surgery; margin reflex distance; silicone rod.

  10. Early age alcohol use and later alcohol problems in adolescents: individual and peer mediators in a bi-national study.

    Science.gov (United States)

    Mason, W Alex; Toumbourou, John W; Herrenkohl, Todd I; Hemphill, Sheryl A; Catalano, Richard F; Patton, George C

    2011-12-01

    This paper examines whether there is cross-national similarity in the longitudinal relationship between early age alcohol use and adolescent alcohol problems. Potential mechanisms underlying this relationship also are examined, testing adolescent alcohol use, low self-regulation, and peer deviance as possible mediators. Students (N = 1,945) participating in the International Youth Development Study, a longitudinal panel survey study, responded to questions on alcohol use and influencing factors, and were followed annually over a 3-year period from 2002 to 2004 (98% retention rate). State-representative, community student samples were recruited in grade 7 in Washington State, United States (US, n = 961, 78% of those eligible; Mage = 13.09, SD = .44) and Victoria, Australia (n = 984, 76% of those eligible; Mage = 12.93, SD = .41). Analyses were conducted using multiple-group structural equation modeling. In both states, early age alcohol use (age 13) had a small but statistically significant association with subsequent alcohol problems (age 15). Overall, there was little evidence for mediation of early alcohol effects. Low self-regulation prospectively predicted peer deviance, alcohol use, and alcohol problems in both states. Peer deviance was more positively related to alcohol use and low self-regulation among students in Victoria compared to students in Washington State. The small but persistent association of early age alcohol use with alcohol problems across both samples is consistent with efforts to delay alcohol initiation to help prevent problematic alcohol use. Self-regulation was an important influence, supporting the need to further investigate the developmental contribution of neurobehavioral disinhibition.

  11. A thermal comparator sensor for measuring autogenous deformation in hardening Portland cement paste

    DEFF Research Database (Denmark)

    Østergaard, Thomas; Jensen, Ole Mejlhede

    2003-01-01

    of the thermal comparator is based on thermal expansion of aluminium. A particular characteristic of the measuring system is the fixation of the thermal comparator sensor to the deforming specimen. The modular system ensures effective thermostatic control of the hydrating cement paste samples. The technique......This paper describes a simple and accurate experimental device specially developed to measure autogenous deformation in hardening cement-based materials. The measuring system consists of a so-called thermal comparator sensor and a modular thermostatically controlled system. The operating principle...

  12. Autogenous control of PspF, a constitutively active enhancer-binding protein of Escherichia coli.

    OpenAIRE

    Jovanovic, G; Dworkin, J; Model, P

    1997-01-01

    Escherichia coli sigma54-dependent phage shock protein operon (pspA to -E) transcription is under the control of PspF, a constitutively active activator. Sigma70-dependent transcription of pspF is under autogenous control by wild-type PspF but not by a DNA-binding mutant, PspF deltaHTH. Negative autoregulation of PspF is continual and not affected by stimuli, like f1 pIV, that induce the pspA to -E operon. PspF production is independent of PspA (the negative regulator of the pspA to -E operon...

  13. Localized ridge augmentation using autogenous block bone graft followed by dental implant placement

    Directory of Open Access Journals (Sweden)

    K V Prabhakara Rao

    2012-01-01

    Full Text Available The placement of endosseous dental implants is often hampered by unfavourable anatomy of the alveolar bone. Most frequently patients lose their teeth due to alveolar bone loss, tooth extraction; trauma and long term use of removable appliances tend to lose the bone making it difficult for the placement of implant in an optimal prosthetic position. The loss of width of the residual alveolar ridge necessitated measures which could refurbish the lost dimensions. Here we report the successful management of such a condition wherein placement of implant was made possible by placement of autogenous bone block graft obtained from the mandibular symphysis region and predictable osseointegration thus achieved.

  14. Stepwise surgical approach to diabetic partial foot amputations with autogenous split thickness skin grafting

    Directory of Open Access Journals (Sweden)

    Crystal L. Ramanujam

    2016-06-01

    Full Text Available In the surgical treatment of severe diabetic foot infections, substantial soft tissue loss often accompanies partial foot amputations. These sizeable soft tissue defects require extensive care with the goal of expedited closure to inhibit further infection and to provide resilient surfaces capable of withstanding long-term ambulation. Definitive wound closure management in the diabetic population is dependent on multiple factors and can have a major impact on the risk of future diabetic foot complications. In this article, the authors provide an overview of autogenous skin grafting, including anatomical considerations, clinical conditions, surgical approach, and adjunctive treatments, for diabetic partial foot amputations.

  15. Treatment of Rockwood type III acromioclavicular joint dislocation using autogenous semitendinosus tendon graft and endobutton technique

    Directory of Open Access Journals (Sweden)

    Ye G

    2016-01-01

    Full Text Available Gang Ye, Chao-An Peng, Hua-Bin Sun, Jing Xiao, Kang Zhu Department of Orthopedics, the People’s Hospital of Huangpi District, Wuhan City, People’s Republic of China Background: The aim of this study was to evaluate the therapeutic effect of autogenous semitendinosus graft and endobutton technique, and compare with hook plate in treatment of Rockwood type III acromioclavicular (AC joint dislocation.Methods: From April 2012 to April 2013, we treated 46 patients with Rockwood type III AC joint dislocation. Patients were randomly divided into two groups: Group A was treated using a hook plate and Group B with autogenous semitendinosus graft and endobutton technique. All participants were followed up for 12 months. Radiographic examinations were performed every 2 months postoperatively, and clinical evaluation was performed using the Constant–Murley score at the last follow-up.Results: Results indicated that patients in Group B showed higher mean scores (90.3±5.4 than Group A (80.4±11.5 in terms of Constant–Murley score (P=0.001. Group B patients scored higher in terms of pain (P=0.002, activities (P=0.02, range of motion (P<0.001, and strength (P=0.004. In Group A, moderate pain was reported by 2 (8.7% and mild pain by 8 (34.8% patients. Mild pain was reported by 1 (4.3% patient in Group B. All patients in Group B maintained complete reduction, while 2 (8.7% patients in Group A experienced partial reduction loss. Two patients (8.7% encountered acromial osteolysis on latest radiographs, with moderate shoulder pain and limited range of motion.Conclusion: Autogenous semitendinosus graft and endobutton technique showed better results compared with the hook plate method and exhibited advantages of fewer complications such as permanent pain and acromial osteolysis. Keywords: Rockwood type III acromioclavicular joint dislocation, autogenous semitendinosus graft, endobutton, hook plate

  16. Histomorphometric evaluation of bone regeneration using autogenous bone and beta-tricalcium phosphate in diabetic rabbits

    Directory of Open Access Journals (Sweden)

    Živadinović Milka

    2016-01-01

    Full Text Available Background/Aim. The mechanism of impaired bone healing in diabetes mellitus includes different tissue and cellular level activities due to micro- and macrovascular changes. As a chronic metabolic disease with vascular complications, diabetes affects a process of bone regeneration as well. The therapeutic approach in bone regeneration is based on the use of osteoinductive autogenous grafts as well as osteoconductive synthetic material, like a β-tricalcium phosphate. The aim of the study was to determine the quality and quantity of new bone formation after the use of autogenous bone and β-tricalcium phosphate in the model of calvarial critical-sized defect in rabbits with induced diabetes mellitus type I. Methods. The study included eight 4-month-old Chincilla rabbits with alloxan-induced diabetes mellitus type I. In all animals, there were surgically created two calvarial bilateral defects (diameter 12 mm, which were grafted with autogenous bone and β-tricalcium phosphate (n = 4 or served as unfilled controls (n = 4. After 4 weeks of healing, animals were sacrificed and calvarial bone blocks were taken for histologic and histomorphometric analysis. Beside descriptive histologic evaluation, the percentage of new bone formation, connective tissue and residual graft were calculated. All parameters were statistically evaluated by Friedman Test and post hock Wilcoxon Singed Ranks Test with a significance of p < 0.05. Results. Histology revealed active new bone formation peripherally with centrally located connective tissue, newly formed woven bone and well incorporated residual grafts in all treated defects. Control samples showed no bone bridging of defects. There was a significantly more new bone in autogeonous graft (53% compared with β-tricalcium phosphate (30%, (p < 0.030 and control (7%, (p < 0.000 groups. A significant difference was also recorded between β-tricalcium phosphate and control groups (p < 0.008. Conclusion. In the present

  17. MICROSURGICAL RECONSTRUCTION OF THE AERODIGESTIVE TRACT WITH COLONIC-ILEAL AUTOGENIC GRAFT IN PATIENTS WITH HYPOPHARYNX CANCER

    Directory of Open Access Journals (Sweden)

    M. V. Ratushny

    2014-01-01

    Full Text Available Study objective: development of the new method of reconstruction of upper section of the aerodigestive tract with the use of a microsurgical colonic-ileal autogenic graft that allows instant recovery of the food passage and voice function.A clinical case of successful treatment of a patient with locally distributed hypopharynx cancer is provided, regarding which microsurgical reconstruction of upper sections of the aerodigestive tract was performed with a free colonic-ileal autogenic graft at the surgical stage of therapy after laryngectomy with sleeve resection of the hypopharynx.The use of a colonic-ileal autogenic graft in the course of reconstruction of upper sections of the aerodigestive tract allowed instant recovery of both food passage and voice function for the patient after laryngectomy with sleeve resection of the hypopharynx.Conclusions:1. Application of this autogenic graft as a plastic material allows recovering both food passage and voice function instantly and completely with circular defects of upper sections of the aerodigestive tract.2. The ileocecal valve included into the structure of the combined autogenic graft prevents saliva and food aspiration into the trachea through the tracheo-oesophageal shunt.3. Mucous secretion of the autogenic graft has no aggressive action on the mucous membrane of the trachea, which allows implementation of the vocal rehabilitation plan.4. After the flap formation, there is no functional or aesthetic damage in the donor area.5. This reconstruction method cuts down the rehabilitation time significantly as well as decreases the patient’s disability level.

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

    Science.gov (United States)

    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

  19. The Analysis of Average Diameter of Erythrocytes in Children of Early Age with Pneumonia and Acute Respiratory Viral Infections

    Directory of Open Access Journals (Sweden)

    S. S. Shevchenko,

    2015-01-01

    Full Text Available Development of inflammatory bronkholegochny process in children is followed by the permanent changes in system of an eritron aggravating finally the phenomena of a hypoxia of bodies and fabrics. Work purpose: studying of average diameter of erythrocytes at children of early age, patients with pneumonia and ARVI. Determination of average diameter of erythrocytes was carried out by a diffraction method on identical structure of chaotic objects at 36 children with pneumonia and at 41 children with a ARVI aged from 4 months till 3 years. The control group was made by 20 almost healthy children of the same age. During the sharp period of a disease the average diameter of erythrocytes was authentically increased both at pneumonia, and at a ARVI. Reliable difference of these indicators when comparing a toxic syndrome at pneumonia and a ARVI is revealed. Thus, at children of early age, patients with pneumonia and ARVI, in dynamics of a disease the natural changes of average diameter of erythrocytes having differential and diagnostic and predictive value are revealed.

  20. Self-healing of Early Age Cracks in Cement-based Materials by Mineralization of Carbonic Anhydrase Microorganism

    Directory of Open Access Journals (Sweden)

    Chunxiang eQian

    2015-11-01

    Full Text Available This research investigated the self-healing potential of early age cracks in cement-based materials incorporating the bacteria which can produce carbonic anhydrase. Cement-based materials specimens were pre-cracked at the age of 7, 14, 28, 60 days to study the repair ability influenced by cracking time, the width of cracks were between 0.1 and 1.0 mm to study the healing rate influenced by width of cracks. The experimental results indicated that the bacteria showed excellent repairing ability to small cracks formed at early age of 7 days, cracks below 0.4 mm was almost completely closed. The repair effect reduced with the increasing of cracking age. Cracks width influenced self-healing effectiveness significantly. The transportation of CO2 and Ca2+ controlled the self-healing process. The computer simulation analyses revealed the self-healing process and mechanism of microbiologically precipitation induced by bacteria and the depth of precipitated CaCO3 could be predicted base on valid Ca2+.

  1. An Early Aged Ophiolite in the Western Kunlun Mts.,NW Tibetan Plateau and Its Tectonic Implications

    Institute of Scientific and Technical Information of China (English)

    XIAO Xuchang; WANG Jun; SU Li; JI Wenhua; SONG Shuguang

    2005-01-01

    The early aged ophiolites have attracted attention of many geologists in recent decades, because the early aged ophiolites can provide the information about the ancient oceanic processes relevant to the evolution of plate tectonics in the early period of the earth, and also concern such problems as whether there existed a "Proto-Tethys" and the break-up and convergence of the Rodinian Supercontinent. This paper reveals a definite complete ophiolite of Neoproterozoic-Early Paleozoic, named Kuda ophiolite in the western Kunlun Mts., NW Tibetan Plateau, and reports the recent reasonable SHRIMP zircon U-Pb ages of 510±4 Ma, and 502±13 Ma for the cumulates of the Kuda ophiolite, using the most powerful dating tool, the SHRIMP-Ⅱ. The geochemical and geochronology data integrating with the geological setting suggest that the Kuda ophiolite might have formed in an archipelago oceanic basin, not in a vast ocean, the so-called "Proto-Tethys",and was tectonically emplaced during the Early Paleozoic.

  2. Full-thickness tissue engineered skin constructed with autogenic bone marrow mesenchymal stem cells

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To explore the feasibility of repairing clinical cutaneous deficiency, autogenic bone marrow mesen-chymal stem cells (BMSCs) were isolated and differentiated into epidermal cells and fibroblasts in vitro supplemented with different inducing factors and biomaterials to construct functional tissue- engineered skin. The results showed that after 72 h induction, BMSCs displayed morphologic changes such as typical epidermal cell arrangement, from spindle shape to round or oval; tonofibrils, melano-somes and keratohyaline granules were observed under a transmission electronic microscope. The differentiated cells expressed epidermal stem cell surface marker CK19 (59.66% ± 4.2%) and epidermal cells differentiation marker CK10. In addition, the induced epidermal cells acquired the anti-radiation capacity featured by lowered apoptosis following exposure to UVB. On the other hand, the collagen microfibrils deposition was noticed under a transmission electronic microscope after differentiating into dermis fibroblasts; RT-PCR identified collagen type I mRNA expression in differentiated cells; radioimmunoassay detected the secretion of interleukin-6 (IL-6) and interleukin-8 (IL-8) (up to 115.06 pg/mL and 0.84 ng/mL, respectively). Further in vivo implanting BMSCs with scaffold material short-ened skin wound repair significantly. In one word, autogenic BMSCs have the potential to differentiate into epidermal cells and fibroblasts in vitro, and show clinical feasibility acting as epidermis-like and dermis-like seed cells in skin engineering.

  3. Viability of Split Thickness Autogenous Skin Transplantation in Canine Distal Limb Reconstruction – An Experimental Evaluation

    Directory of Open Access Journals (Sweden)

    M. S. Ijaz, A. K. Mahmood, N. Ahmad1, M. A. Khan, and U. Farooq

    2012-05-01

    Full Text Available Distal limb reconstruction is complicated by the paucity of local tissues and the frequent association of orthopedic injury with cutaneous loss. Though, second-intention healing or skin stretching techniques are used for wounds involving less than a 30% circumference of the limb, however, skin grafts are recommended for reconstruction of larger superficial wounds. The present study was designed to clinically evaluate the viability of split thickness autogenous skin transplantation (STAST in dogs. Standardized surgical defects of variable size i.e. 3×3, 4×4 and 5×5 sq cm were made on the left middle radial area (forearm of 15 mongrel dogs assigned to Group A, B and C, respectively having 5 dogs each. Split thickness autogenous skin grafts were harvested from mid thorax and placed in these defects through several simple interrupted sutures. Results indicated a success rate of 80% with no clinical difference in the survival rate of three different sizes of grafts used. Hence, STAST can successfully be used for canine distal limb reconstruction.

  4. Alternative surgical treatment of paralytic lagophthalmos using autogenic cartilage grafts and canthopexy.

    Science.gov (United States)

    Friedhofer, Henri; Coltro, Pedro Soler; Vassiliadis, Aneta Hionia; Nigro, Marcelus Vinícius; Saito, Fábio Lopes; Moura, Tatiana; Faria, José Carlos; Ferreira, Marcus Castro

    2013-08-01

    This study aims to analyze the use of autogenic auricular cartilage grafts as weight for the upper eyelid in conjunction with lateral canthopexy for patients with mild paralytic lagophthalmos. This procedure was also accompanied by elevation of the lower eyelid using the cartilage graft for moderate cases. We conducted a retrospective study including case series of 30 patients with paralytic lagophthalmos from 1997 to 2010. For mild cases, cartilage from the auricular scapha was placed in pretarsal space of the upper eyelid and cartilage from the concha was inserted in preaponeurotic space and then sutured to the levator aponeurosis in conjunction with lateral canthopexy. For moderate cases, lower eyelid was also elevated by suturing cartilage graft to tarsum and resting it by the inferior orbital rim. All patients had some degree of keratopathy before the intervention. After treatment, they presented with evident clinical improvement, reduction of eye symptoms, and resolution of keratopathy. During the mean postoperative follow-up of 37.3 months, none of the patients presented with cartilage graft exposition, reabsorption, visibility, infection, or warping. Complete eye closure was achieved in 24 (80%) patients, whereas the remaining 6 (20%) patients had residual asymptomatic lagophthalmos. The intervention using autogenic auricular cartilage grafts explained in this study was only effective for the treatment of mild and moderate cases of paralytic lagophthalmos. This outpatient surgery is associated with low morbidity and achievement of functional and aesthetic improvement.

  5. Pure orbital blowout fractures reconstructed with autogenous bone grafts: functional and aesthetic outcomes.

    Science.gov (United States)

    Kronig, S A J; van der Mooren, R J G; Strabbing, E M; Stam, L H M; Tan, J A S L; de Jongh, E; van der Wal, K G H; Paridaens, D; Koudstaal, M J

    2016-04-01

    The purpose of this study was to investigate the ophthalmic clinical findings following surgical reconstruction with autogenous bone grafts of pure blowout fractures. A retrospective review of 211 patients who underwent surgical repair of an orbital fracture between October 1996 and December 2013 was performed. Following data analysis, 60 patients who were followed up over a period of 1 year were included. A solitary floor fracture was present in 38 patients and a floor and a medial wall fracture in 22 patients. Comparing preoperative findings between these two groups, preoperative diplopia and enophthalmos were almost twice as frequent in the group with additional medial wall fractures: diplopia 8% and 14% and enophthalmos 18% and 55%, respectively. One year following surgery there was no diplopia present in either group. In the solitary floor fracture group, 3% still had enophthalmos. It can be concluded that at 1 year following the repair of pure orbital floor fractures using autogenous bone, good functional and aesthetic results can be obtained. In the group with both floor and medial wall fractures, no enophthalmos was found when both walls were reconstructed. When the medial wall was left unoperated, 29% of patients still suffered from enophthalmos after 1 year.

  6. Physicochemical Characteristics of Bone Substitutes Used in Oral Surgery in Comparison to Autogenous Bone

    Directory of Open Access Journals (Sweden)

    Antoine Berberi

    2014-01-01

    Full Text Available Bone substitutes used in oral surgery include allografts, xenografts, and synthetic materials that are frequently used to compensate bone loss or to reinforce repaired bone, but little is currently known about their physicochemical characteristics. The aim of this study was to evaluate a number of physical and chemical properties in a variety of granulated mineral-based biomaterials used in dentistry and to compare them with those of autogenous bone. Autogenous bone and eight commercial biomaterials of human, bovine, and synthetic origins were studied by high-resolution X-ray diffraction, atomic absorption spectrometry, and laser diffraction to determine their chemical composition, calcium release concentration, crystallinity, and granulation size. The highest calcium release concentration was 24. 94 mg/g for Puros and the lowest one was 2.83 mg/g for Ingenios β-TCP compared to 20.15 mg/g for natural bone. The range of particles sizes, in terms of median size D50, varied between 1.32 μm for BioOss and 902.41 μm for OsteoSponge, compared to 282.1 μm for natural bone. All samples displayed a similar hexagonal shape as bone, except Ingenios β-TCP, Macrobone, and OsteoSponge, which showed rhomboid and triclinic shapes, respectively. Commercial bone substitutes significantly differ in terms of calcium concentration, particle size, and crystallinity, which may affect their in vivo performance.

  7. Full-thickness tissue engineered skin constructed with autogenic bone marrow mesenchymal stem cells

    Institute of Scientific and Technical Information of China (English)

    HE LiJuan; PEI XueTao; NAN Xue; WANG YunFang; GUAN LiDong; BAI CiXian; SHI ShuangShuang; YUAN HongFeng; CHEN Lin; LIU DaQing

    2007-01-01

    To explore the feasibility of repairing clinical cutaneous deficiency, autogenic bone marrow mesenchymal stem cells (BMSCs) were isolated and differentiated into epidermal cells and fibroblasts in vitro supplemented with different inducing factors and biomaterials to construct functional tissueengineered skin. The results showed that after 72 h induction, BMSCs displayed morphologic changes such as typical epidermal cell arrangement, from spindle shape to round or oval; tonofibrils, melanosomes and keratohyaline granules were observed under a transmission electronic microscope. The differentiated cells expressed epidermal stem cell surface marker CK19 (59.66%±4.2%) and epidermal cells differentiation marker CK10. In addition, the induced epidermal cells acquired the anti-radiation capacity featured by lowered apoptosis following exposure to UVB. On the other hand, the collagen microfibrils deposition was noticed under a transmission electronic microscope after differentiating into dermis fibroblasts; RT-PCR identified collagen type Ⅰ mRNA expression in differentiated cells;radioimmunoassay detected the secretion of interleukin-6 (IL-6) and interleukin-8 (IL-8) (up to 115.06pg/mL and 0.84 ng/mL, respectively). Further in vivo implanting BMSCs with scaffold material shortened skin wound repair significantly. In one word, autogenic BMSCs have the potential to differentiate into epidermal cells and fibroblasts in vitro, and show clinical feasibility acting as epidermis-like and dermis-like seed cells in skin engineering.

  8. Autogenous tibial strut grafts used in severe kyphoscoliosis:surgical policies and preliminary results

    Institute of Scientific and Technical Information of China (English)

    CHEN Hui; QIU Yong; WANG Bin; YU Yang; ZHU Ze-zhang ZHU Li-hua

    2005-01-01

    Background Surgery for severe kyphoscoliosis is frequently unsatisfying because of loss of correction, high rate of pseudarthrosis and neurological complications.Several authors reported that the anterior fusion with strut grafts might improve the surgical outcome.This article describes and assesses the surgical strategies and the application of autogenous tibial strut in the treatment of severe kyphoscoliosis.Results The mean preoperative and postoperative kyphosis was 82°and 52°respectively, and the mean scoliosis was 84°and 44°respectively.Complications included pseudarthrosis (2 cases, one with graft fracture and the other with hook displacement), posterior elements fractures (4), pleura penetrations (3, in the plastic surgery of the thoracic cage), dura tear (2), exudative pleuritis (2, in the anterior surgery), and tibia fracture of the harvesting site (1).The mean loss of correction in coronal and sagittal plane was 6° and 7° respectively.Except for 1 case, the patients with incomplete paraplegia showed improvements to varying extents.Conclusion Autogenous tibial strut can provide excellent support to the kyphoscoliotic spine: it reduces pseudarthrodic rate, loss of correction and complications of graft harvest, it also prevents the occurrence of neurological impairment.

  9. Treatment of an Immature Autogenous Arteriovenous Fistula with Percutaneous Transluminal Angioplasty

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyoung Rae [Kangwon National University, Chuncheon (Korea, Republic of)

    2008-11-15

    The purpose of this study was to evaluate the efficacy of percutaneous transluminal angioplasty (PTA) in facilitating maturation of autogenous arteriovenous fistulae. There were 12 immature autogenous arteriovenous fistulae. We performed 15 PTAs transvenously. Post-intervention anatomic and clinical successes were estimated, and the 6-month and 1-year primary and secondary patency rates were calculated using Kaplan-Meier analysis. All immature fistulae had underlying stenosis (n=20): arteriovenous anastomosis (n=1) and venous outflow (n=19): 1) within 5 cm from the anastomosis (n=10); 2) more than 5 cm but less than 10 cm from the anastomosis (n=5); 3) more than 10 cm from the anastomosis, including central veins (n=4). Six fistulae had two or more stenoses. Repeat intervention was necessary in two patients. The anatomical success rate was 94.3%, and the clinical success rate was 86.7%. The 6-month and 1-year primary patency rates were 72.7% and 54.5%, and the secondary patency rates were 100% and 81.8%, respectively. All immature hemodialysis fistulae have underlying stenosis, most of which are located near the arteriovenous anastomosis. Early interventional procedures are helpful in the salvage and maintenance of immature arteriovenous fistulae, with a high degree of success

  10. Perceptual shrinkage of a one-way motion path with high-speed motion.

    Science.gov (United States)

    Nakajima, Yutaka; Sakaguchi, Yutaka

    2016-07-28

    Back-and-forth motion induces perceptual shrinkage of the motion path, but such shrinkage is hardly perceived for one-way motion. If the shrinkage is caused by temporal averaging of stimulus position around the endpoints, it should also be induced for one-way motion at higher motion speeds. In psychophysical experiments with a high-speed projector, we tested this conjecture for a one-way motion stimulus at various speeds (4-100 deg/s) along a straight path. Results showed that perceptual shrinkage of the motion path was robustly observed in higher-speed motion (faster than 66.7 deg/s). In addition, the amount of the forwards shift at the onset position was larger than that of the backwards shift at the offset position. These results demonstrate that high-speed motion can induce shrinkage, even for a one-way motion path. This can be explained by the view that perceptual position is represented by the integration of the temporal average of instantaneous position and the motion representation.

  11. The effects of dimensional mould sizes on volumetric shrinkage strain of lateritic soil

    Directory of Open Access Journals (Sweden)

    John Engbonye SANI

    2016-07-01

    Full Text Available Dimensional influences of specimen size on the volumetric shrinkage strain values of a lateritic soil for waste containment system have not been researched upon. Therefore, this paper presents the result of a laboratory study on the volumetric shrinkage strain (VSS of lateritic soil at three different dimensional sizes of mould (split former mould, proctor mould and California bearing ratio mould at three energy levels; British standard light (BSL, West African standard (WAS and British standard heavy (BSH respectively. Compactions were done at different molding water content of -2% to +6% optimum moisture content (OMC. At -2% to +2% molding water content for the split former mould the volumetric shrinkage strain met the requirement of not more than 4% while at +4% and +6% only the WAS and BSH met the requirement. The proctor mould and the CBR mould on the other hand gave a lower value of volumetric shrinkage strain in all compactive effort and the values are lower than the 4% safe VSS suggested by Tay et al., (2001. Based on the VSS values obtained if the CBR mould can be used to model site condition it is recommended for use to simulate site condition for Volumetric shrinkage strain for all molding water content and compactive effort.

  12. Measurement of linear polymerization shrinkage in light cure Ideal Makoo composite resin

    Directory of Open Access Journals (Sweden)

    Ghavam M.

    2001-09-01

    Full Text Available "nAbstract: Polymerization shrinkage of light cure composite resins causes many complications in conservative and esthetic restorations. The objective of this in-vitro study was to evaluate the polymerization shrinkage, degree of conversion and the amount of filler in IDM and tetric ceram composites. Ten disk shaped, uncured specimens (8mm×1.547mm of each composite were placed on glass slide in the center of the metal attached to it. Then specimens were light cured for 60s from underneath. After 30 minutes, the thickness of specimens, using a micrometer and the percent of the polymerization shrinkage of each sample were measured. Statistical analysis was carried out by t-test (P<0.05. Also the degree of conversion of specimens was evaluated with FTIR and the mineral filler content was measured by burning in electric oven. Polymerization shrinkage in IDM and tetric ceram was not significantly different. Degree of conversion and mineral filler content in tetric ceram was greater than that of IDM. "nIt is assumed that the low degree of conversion in IDM is due to its chemical composition and filler content. Also, the similarity in linear polymerization shrinkage between IDM and tetric ceram may be caused by the low degree of conversion in IDM.

  13. A Pore-Centric Model for Combined Shrinkage and Gas Porosity in Alloy Solidification

    Science.gov (United States)

    Khalajzadeh, Vahid; Carlson, Kent D.; Backman, Daniel G.; Beckermann, Christoph

    2017-04-01

    A unified model has been developed for combined gas- and shrinkage-induced pore formation during solidification of metal alloys. The model is based on a pore-centric approach, in which the temporal evolution of the pore radius is calculated as a function of cooling rate, thermal gradient, gas diffusion, and shrinkage. It accounts for the effect of porosity formation on the liquid velocity within the mushy zone. Simulations for an aluminum alloy show that the porosity transitions smoothly from shrinkage-induced to gas-induced as the Niyama value is increased. A Blake (cavitation) instability is observed to occur when the porosity is both gas- and shrinkage-driven. A revised dimensionless Niyama curve for pure shrinkage is presented. The experimentally observed gas porosity trend that the pore volume decreases with increasing cooling rate is well predicted. The pore-centric formulation allows the present model to be solved locally, at any point in a casting, during a regular casting simulation.

  14. Pore Structure and Influence of Recycled Aggregate Concrete on Drying Shrinkage

    Directory of Open Access Journals (Sweden)

    Yuanchen Guo

    2013-01-01

    Full Text Available Pore structure plays an important role in the drying shrinkage of recycled aggregate concrete (RAC. High-precision mercury intrusion and water evaporation were utilized to study the pore structure of RAC, which has a different replacement rate of recycled concrete aggregate (RCA, and to analyze its influence on drying shrinkage. Finally, a fractal-dimension calculation model was established based on the principles of mercury intrusion and fractal-geometry theory. Calculations were performed to study the pore-structure fractal dimension of RAC. Results show the following. (1 With the increase in RCA content, the drying shrinkage values increase gradually. (2 Pores with the greatest impact on concrete shrinkage are those whose sizes ranging from 2.5 nm to 50 nm and from 50 nm to 100 nm. In the above two ranges, the proportions of RAC are greater than those of RC0 (natural aggregate concrete, NAC, which is the main reason the shrinkage values of RAC are greater than those of NAC. (3 The pore structure of RAC has good fractal feature, and the addition of RCA increases the complexity of the pore surface of concrete.

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

    Science.gov (United States)

    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.

  16. Effects of Manufactured-sand on Dry Shrinkage and Creep of High-strength Concrete

    Institute of Scientific and Technical Information of China (English)

    ZHOU Mingkai; WANG Jiliang; ZHU Lide; HE Tusheng

    2008-01-01

    The influences of natural sand, manufactured-sand (MS) and stone-dust (SD) in the manufactured-sand on workability, compressive strength, elastic modulus, drying shrinkage and creep properties of high-strength concrete (HSC) were tested and compared. The results show that the reasonable content (7%-10.5%) of SD in MS will not deteriorate the workability of MS-HSC. It could even improve the workability. Moreover, the compressive strength increases gradually with the increasing SD content,and the MS-HSC with low SD content (smaller than 7%) has the elastic modulus which approaches that of the natural sand HSC, but the elastic modulus reduces when the SD content is high. The influence of the SD content on drying shrinkage performance of MS-HSC is closely related to the hydration age. The shrinkage rate of MS-HSC in the former 7 d age is higher than that of the natural sand HSC, but the difference of the shrinkage rate in the late age is not marked. Meanwhile the shrinkage rate reduces as the fly ash is added; the specific creep and creep coefficient of MS-HSC with 7% SD are close to those of the natural sand HSC.

  17. Physical Shrinkage Relationship in Soils of Dissimilar Lithologies in Central Southeastern Nigeria

    Science.gov (United States)

    Onweremadu, E. U.; Akamigbo, F. O. R.; Igwe, C. A.

    This study investigated the relationship between volume shrinkage properties of soils derived from different parent materials in Central Southeastern Nigeria as they related to selected soil physical properties. Using a free survey technique and guided by a geological map of the area, field sampling was conducted in the early months of 2005. Routine analyses were done using collected soil samples. Results showed significant (pwaterholding capacity, Atterberg limits and Co-efficient Of Linear Extensibility (COLE) among the 6 studied soil groups. Volume shrinkage results indicated severe shrinkage (20-30%) rating for soils derived from Shale, moderate shrinkage (10-20%) for soils formed over Lower Coal Measures and Falsebedded Sandstones and slight shrinkage (0-10%) ratings for the rest. The COLE, used as an index of VS correlated significantly (pwaterholding capacity (WHC), Liquid Limit (LL), Plastic Limit (PL), Plasticity Index (PI) and clay content. A model was generated which expressed good predictive relationship between COLE and selected physical properties (R = 0.87; R2 = 0.75; 1-R2 = 0.25, RMSE = 0.01 and Bias = +0.00001), indicating high accuracy and little over-estimation by the model. More soil and soil related variables may further improve generated model (s), thus should be included in future studies.

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

    Science.gov (United States)

    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.

  19. Shrinkage Characteristics of Experimental Polymer Containing Composites under Controlled Light Curing Modes

    Directory of Open Access Journals (Sweden)

    Alain Pefferkorn

    2012-01-01

    Full Text Available The adsorption of polymethylmethacrylate polymer of different molecular weight at the aerosil/ethyleneglycol- or 1,3 butanediol-dimethacrylate interfaces was determined to provide microstructured networks. Their structural characteristics were determined to be controlled by the amount of polymer initially supplied to the system. The sediment (the settled phase characteristics, determined as a function of the polymer concentration and the rate of the polymerization shrinkage determined for composite resins, obtained by extrusion of the sediment after centrifugation, were found to be correlated. The specific role of the adsorbed polymer was found to be differently perturbed with the supplementary supply of dimethacrylate based monomer additives. Particularly, the bisphenol A dimethacrylate that generated crystals within the sediment was found to impede the shrinkage along the crystal lateral faces and strongly limit the shrinkage along its basal faces. Addition of ethyleneglycol- or polyethylene-glycoldimethacrylate monomers was determined to modify the sedimentation characteristics of the aerosil suspension and the shrinkage properties of the composites. Finally, the effects of stepwise light curing methods with prolonged lighting-off periods were investigated and found to modify the development and the final values of the composite shrinkage.

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

    Science.gov (United States)

    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.

  1. Properties evaluation of silorane, low-shrinkage, non-flowable and flowable resin-based composites in dentistry

    OpenAIRE

    Maia, Rodrigo R.; Reis, Rodrigo S.; Moro, André F.V.; Perez, Cesar R.; Bárbara M. Pessôa; Dias, Katia R.H.C.

    2015-01-01

    Purpose. This study tested the null hypothesis that different classes of direct restorative dental materials: silorane-based resin, low-shrinkage and conventional (non-flowable and flowable) resin-based composite (RBC) do not differ from each other with regard to polymerization shrinkage, depth of cure or microhardness. Methods. 140 RBC samples were fabricated and tested by one calibrated operator. Polymerization shrinkage was measured using a gas pycnometer both before and immediately after ...

  2. Crack development through plastic shrinkage in fresh concretes and mortars

    Directory of Open Access Journals (Sweden)

    Aguanell García, M.

    1989-09-01

    Full Text Available The rate of water evaporation in the exposed surfaces plays an important part in the development of cracks in fresh concretes and mortars before hardening is completed. This rate of evaporation depends on the drying power of the wind sweeping such surfaces as a function of the relative humidity, temperature and speed of the air. After many studies and research work on the subject of plastic cracking, the following axiom has been established: "Plastic shrinkage and cracking of concrete surfaces take place when water evaporates from the surface quicker than it can be replaced through exudation". Once the value of weather parameters are known, the extent of the risk of crack development can be known and preventive steps taken to overcome such risk. Obviously, such steps are all oriented to reducing or stopping evaporation and go from covering surfaces with wet sackcloth or plastic foil, through sprinkling water mists or lowering the concrete temperature, to using film-forming curing products. Another additional measure can be the addition of polypropelene fibers to the concrete while in the mixer, at the rate of 0.9 kg fiber to 1 m3 of concrete.

    En la formación de grietas en morteros y hormigones frescos, antes de finalizar el fraguado, tiene una primordial importancia la velocidad de evaporación del agua de las superficies expuestas al exterior, velocidad que depende del poder desecante de los vientos que barren estas superficies y que está en función de la humedad relativa del aire, de su temperatura y de su velocidad. Después de los múltiples estudios e investigaciones sobre este tema de la formación de las grietas plásticas, se ha llegado a establecer el siguiente axioma: "La retracción plástica y las grietas se producen, en las superficies del hormigón, cuando el agua se evapora de ellas más rápidamente que la que puede ser reemplazada por exudación." Conociendo el valor de los parámetros meteorol

  3. Morphological variation and habitat modification are strongly correlated for the autogenic ecosystem engineer Spartina anglica (common cordgrass)

    NARCIS (Netherlands)

    van Hulzen, J.B.; Van Soelen, J.; Bouma, T.J.

    2007-01-01

    We explored to what extent morphological variation and habitat modification are correlated for an autogenic ecosystem engineer, which is an organism that modifies its habitat via its own physical structures. The intertidal salt marsh species Spartina anglica is well known for its capacity to enhance

  4. The Assessment of Critical Thinking Skill for Early Age Children Based on Criterion Referenced and Norm Referenced Interpretations

    Directory of Open Access Journals (Sweden)

    Rodhoty Taza Mila

    2016-11-01

    Full Text Available Abstract The objective of this research is to study comprehensively the assessment of critical thinking skill for early age children based on criterion referenced and norm referenced interpretations. It is a non-experimental quantitative research for students in Assalam Kinder-garten. There are some critical thinking skill indicators, such as clarity, accuracy, precision, depth, breath, relevance, and logic. By using assessment based on criterion referenced inter-pretations, critical thinking skill  is so real and absolute, while by using assessment based on norm referenced interpretations, critical thinking skill is so relative depends on their groups. Based on criterion referenced interpretations, there are 24 students can’t think critically because their scores are lower than minimum limit and 10 students can think critically because their scores are higher than minimum limit. Based on norm referenced interpreta-tions, there are 19 students think critically above average and 15 students think critically under average. So, the assessment of critical thinking skill for early age children can be strong foundation to prepare the best stimulation for optimalizing their critical thinking skill until mature in the future. Abstrak Tujuan dari penelitian ini adalah untuk mempelajari secara komprehensif penilaian keterampilan berpikir kritis untuk anak-anak usia dini berdasarkan penilaian acuan kriteria dan penilaian acuan norma. Ini merupakan penelitian kuantitatif non-eksperimental untuk siswa di TK Assalam. Ada beberapa indikator keterampilan berpikir kritis, seperti kejelasan, akurasi, presisi, kedalaman, keluasan, relevansi, dan logika. Dengan menggunakan penilaian acuan kriteria, keterampilan berpikir kritis menjadi nyata dan mutlak, sementara dengan menggunakan penilaian acuan norma, keterampilan berpikir kritis menjadi sangat relatif tergantung pada kelompok mereka. Berdasarkan penilaian acuan kriteria, ada 24 siswa tidak dapat berpikir

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Yih-Dean Jan

    2014-04-01

    Conclusion: Conjugation of diisocyanate side chains to dimethacrylate represents an effective means of reducing polymerization shrinkage and increasing the surface hardness of dental composite resins.

  7. Shrinkage Analysis on Thick Plate Part using Response Surface Methodology (RSM

    Directory of Open Access Journals (Sweden)

    Isafiq M.

    2016-01-01

    Full Text Available The work reported herein is about an analysis on the quality (shrinkage on a thick plate part using Response Surface Methodology (RSM. Previous researches showed that the most influential factor affecting the shrinkage on moulded parts are mould and melt temperature. Autodesk Moldflow Insight software was used for the analysis, while specifications of Nessei NEX 1000 injection moulding machine and P20 mould material were incorporated in this study on top of Acrylonitrile Butadiene Styrene (ABS as a moulded thermoplastic material. Mould temperature, melt temperature, packing pressure and packing time were selected as variable parameters. The results show that the shrinkage have improved 42.48% and 14.41% in parallel and normal directions respectively after the optimisation process.

  8. Thermal assisted ion shrinkage (TAIS) of fluorinated polyimide for optical telecommunication devices

    Science.gov (United States)

    Trigaud, T.; Moliton, J. P.; Quillat, M.; Chiron, D.

    1999-06-01

    In the framework of the development of low cost optical devices for telecommunications, here is studied the shrinkage of 6FDA-ODA polyimide films by ion irradiation as a function of five parameters: the ion fluence, the ion fluence rate, the ion energy, the ion nature and the target temperature. In the 30-350 keV energy range for impinging ions, the shrinkage remains constant whatever the tested fluence rate is. An upper limit appears for fluences above 10 16 ions cm -2. The etching is linearly dependent on the ion beam energy and reaches a maximum around 1 μm by thermal assisted ion shrinkage (TAIS) with Na + irradiations.

  9. A cure shrinkage model for analyzing the stresses and strains in encapsulated assemblies

    Science.gov (United States)

    Chambers, R. S.; Lagasse, R. R.; Guess, T. R.; Plazek, D. J.; Bero, C.

    Electrical component assemblies are encapsulated to provide delicate parts with voltage isolation and protection against damage caused by shock, vibration, and harsh atmospheric environments. During cure, thermosetting resins shrink and harden simultaneously. If the natural deformation of the resin is constrained by adhesion to the mold or to relatively stiff embedded components, cure shrinkage stresses are generated in the encapsulant. Subsequent cooling or thermal cycling produces additional stresses that are caused by the mismatches in thermal strains among the materials in the encapsulated assembly. Although cure shrinkage stresses frequently are neglected because they are considerably smaller than thermal stresses, cure shrinkage stresses can cause delamination or fractures in the encapsulant, since the partially cured resin is not as tough as the fully cured material. Cracks generated during cure can compromise performance (e.g., permit dielectric breakdown), degrade a component's protection, and grow under subsequent thermal cycling producing residual stresses that differ from those found in uncracked assemblies.

  10. A cure shrinkage model for analyzing the stresses and strains in encapsulated assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, R.S.; Lagasse, R.R.; Guess, T.R. [Sandia National Labs., Albuquerque, NM (United States); Plazek, D.J.; Bero, C. [Pittsburgh Univ., PA (United States). Dept. of Materials Science and Engineering

    1992-12-31

    Electrical component assemblies are encapsulated to provide delicate parts with voltage isolation and protection against damage caused by shock, vibration, and harsh atmospheric environments. During cure, thermosetting resins shrink and harden simultaneously. If the natural deformation of the resin is constrained by adhesion to the mold or to relatively stiff embedded components, cure shrinkage stresses are generated in the encapsulant. Subsequent cooling or thermal cycling produces additional stresses that are caused by the mismatches in thermal strains among the materials in the encapsulated assembly. Although cure shrinkage stresses frequently are neglected because they are considerably smaller than thermal stresses, cure shrinkage stresses can cause delamination or fractures in the encapsulant, since the partially cured resin is not as tough as the fully cured material. Cracks generated during cure can compromise performance (e. g., permit dielectric breakdown), degrade a component`s protection, and grow under subsequent thermal cycling producing residual stresses that differ from those found in uncracked assemblies. 3 refs., 11 figs.

  11. Adaptive contourlet-wavelet iterative shrinkage/thresholding for remote sensing image restoration

    Institute of Scientific and Technical Information of China (English)

    Nu WEN; Shi-zhi YANG; Cheng-jie ZHU; Sheng-cheng CUI

    2014-01-01

    In this paper, we present an adaptive two-step contourlet-wavelet iterative shrinkage/thresholding (TcwIST) algorithm for remote sensing image restoration. This algorithm can be used to deal with various linear inverse problems (LIPs), including image deconvolution and reconstruction. This algorithm is a new version of the famous two-step iterative shrinkage/thresholding (TwIST) algorithm. First, we use the split Bregman Rudin-Osher-Fatemi (ROF) model, based on a sparse dictionary, to decom-pose the image into cartoon and texture parts, which are represented by wavelet and contourlet, respectively. Second, we use an adaptive method to estimate the regularization parameter and the shrinkage threshold. Finally, we use a linear search method to find a step length and a fast method to accelerate convergence. Results show that our method can achieve a signal-to-noise ratio improvement (ISNR) for image restoration and high convergence speed.

  12. Dental composite resins: measuring the polymerization shrinkage using optical fiber Bragg grating sensors

    Science.gov (United States)

    Ottevaere, H.; Tabak, M.; Chah, K.; Mégret, P.; Thienpont, H.

    2012-04-01

    Polymerization shrinkage of dental composite materials is recognized as one of the main reasons for the development of marginal leakage between a tooth and filling material. As an alternative to conventional measurement methods, we propose optical fiber Bragg grating (FBG) based sensors to perform real-time strain and shrinkage measurements during the curing process of dental resin cements. We introduce a fully automated set-up to measure the Bragg wavelength shift of the FBG strain sensors and to accurately monitor the linear strain and shrinkage of dental resins during curing. Three different dental resin materials were studied in this work: matrix-filled BisGMA-based resins, glass ionomers and organic modified ceramics.

  13. Cell shrinkage as a signal to apoptosis in NIH 3T3 fibroblasts

    DEFF Research Database (Denmark)

    Friis, Martin B; Friborg, Christel R; Schneider, Linda

    2005-01-01

    Cell shrinkage is a hallmark of the apoptotic mode of programmed cell death, but it is as yet unclear whether a reduction in cell volume is a primary activation signal of apoptosis. Here we studied the effect of an acute elevation of osmolarity (NaCl or sucrose additions, final osmolarity 687...... mosmol l(-1)) on NIH 3T3 fibroblasts to identify components involved in the signal transduction from shrinkage to apoptosis. After 1.5 h the activity of caspase-3 started to increase followed after 3 h by the appearance of many apoptotic-like bodies. The caspase-3 activity increase was greatly enhanced...... in cells expressing a constitutively active G protein, Rac (RacV12A3 cell), indicating that Rac acts upstream to caspase-3 activation. The stress-activated protein kinase, p38, was significantly activated by phosphorylation within 30 min after induction of osmotic shrinkage, the phosphorylation being...

  14. Polymerization shrinkage and contraction force of composite resin restorative inserted with "Megafiller".

    Science.gov (United States)

    Tani, Y; Nambu, T; Ishikawa, A; Katsuyama, S

    1993-12-01

    This study quantified the contraction force and polymerization shrinkage of composite resins with/without beta-Quartz Glass Ceramic Inserts (BQCI) as "Megafiller". The materials used for the determination included a chemically cured composite and five light-cured composites. The system for measuring contraction force consisted of a transparent teflon tube for preparing the specimen, a small load cell, a dynamic strain gauge and a pen-recorder. After the composite was packed into the teflon mold, a BQCI (Type R3) was inserted through the opening and the specimen was cured. Linear polymerization shrinkage of the composites was measured every 10 seconds from the start of mixing or irradiation to 90 minutes by the mercury bath method. Three pieces each of BQCI (Type T3) were inserted in each specimen. The results suggested that BQCI was markedly effective in reducing polymerization shrinkage, but was not always effective in reducing the contraction force during polymerization.

  15. Fast approach to infrared image restoration based on shrinkage functions calibration

    Science.gov (United States)

    Zhang, Chengshuo; Shi, Zelin; Xu, Baoshu; Feng, Bin

    2016-05-01

    High-quality image restoration in real time is a challenge for infrared imaging systems. We present a fast approach to infrared image restoration based on shrinkage functions calibration. Rather than directly modeling the prior of sharp images to obtain the shrinkage functions, we calibrate them for restoration directly by using the acquirable sharp and blurred image pairs from the same infrared imaging system. The calibration method is employed to minimize the sum of squared errors between sharp images and restored images from the blurred images. Our restoration algorithm is noniterative and its shrinkage functions are stored in the look-up tables, so an architecture solution of pipeline structure can work in real time. We demonstrate the effectiveness of our approach by testing its quantitative performance from simulation experiments and its qualitative performance from a developed wavefront coding infrared imaging system.

  16. Physical modeling of the soil swelling curve vs. the shrinkage curve

    CERN Document Server

    Chertkov, V Y

    2014-01-01

    Physical understanding of the links between soil swelling, texture, structure, cracking, and sample size is of great interest for the physical understanding of many processes in the soil-air-water system and for applications in civil, agricultural, and environmental engineering. The background of this work is an available chain of interconnected physical shrinkage curve models for clay, intra-aggregate matrix, aggregated soil without cracks, and soil with cracks. The objective of the work is to generalize these models to the case of swelling, and to construct the physical-swelling-model chain with a step-by-step transition from clay to aggregated soil with cracks. The generalization is based on thorough accounting for the analogies and differences between shrinkage and swelling and the corresponding use, modification, or replacement of the soil shrinkage features. Two specific soil swelling features to be used are: (i) air entrapping in pores of the contributing clay; and (ii) aggregate destruction with the f...

  17. Hormone replacement therapy and age-related brain shrinkage: regional effects.

    Science.gov (United States)

    Raz, Naftali; Rodrigue, Karen M; Kennedy, Kristen M; Acker, James D

    2004-11-15

    Neuroprotective properties of estrogen have been established in animal models, but clinical trials of hormone replacement therapy (HRT) produced contradictory results. We examined the impact of HRT on age-related regional changes in human brain volume. Six brain regions were measured twice, five years apart, in 12 healthy women who took HRT and in matched controls who did not. The controls showed a typical pattern of differential brain shrinkage in the association cortices and the hippocampus with no change in the primary visual cortex. In contrast, women who took HRT showed comparable shrinkage of the hippocampus but no significant shrinkage of the neocortex. Future large scale studies may benefit from applying regional rather than global measures in assessment of brain integrity.

  18. Hormone-dependent shrinkage of a sphenoid wing meningioma after pregnancy: case report.

    Science.gov (United States)

    Kerschbaumer, Johannes; Freyschlag, Christian F; Stockhammer, Günter; Taucher, Susanne; Maier, Hans; Thomé, Claudius; Seiz-Rosenhagen, Marcel

    2016-01-01

    Meningiomas are known to be associated with female sex hormones. Worsening neurological symptoms or newly diagnosed meningiomas have been described in the context of elevated levels of sex hormones, for example, in pregnancy. To the authors' knowledge, tumor shrinkage after the normalization of hormones has not been described, even if it is known that neurological deficits due to meningioma compression may improve after giving birth. A 32-year-old female patient presented with severe headache and vision disturbances at the end of her second pregnancy. Magnetic resonance imaging revealed an extended mass at the lateral left-sided sphenoid wing that was suspected to be a meningioma. After delivery, the patient's symptoms improved, and MRI obtained 2 months postpartum showed significant shrinkage of the lesion. Significant tumor shrinkage can occur after pregnancy. Thus, repeat imaging is indicated in these patients.

  19. [Elevation of proinflammatory cytokines level at early age as the risk factor of neurological and mental pathology development].

    Science.gov (United States)

    Zubarev, O E; Klimenko, V M

    2011-10-01

    Proinflammatory cytokines Interleukin-1, Interleukin-6 (IL-1, IL-6) and tumour necrosis factor alpha (TNFalpha), the key mediators of neuroimmune interactions, are the common pathogenic part of various kinds of the perinatal pathology leading to severe neurological and mental diseases. In the review, features of expression of the proinflammatory cytokines and their receptors in the brain at early age under normal and pathological conditions, their influence on processes of maturing of the CNS cells are described, the data of experimental and clinical researches of disturbances of the mental functions arising in adults owing to elevation of the IL-1, IL-6 levels and TNFalpha in early ontogenesis are cited. The role of the cytokines in pathogenesis of schizophrenia, a syndrome of attention deficiency, autism and a Parkinsonism is discussed.

  20. Diversity Shrinkage: Cross-Validating Pareto-Optimal Weights to Enhance Diversity via Hiring Practices.

    Science.gov (United States)

    Song, Q Chelsea; Wee, Serena; Newman, Daniel A

    2017-07-27

    To reduce adverse impact potential and improve diversity outcomes from personnel selection, one promising technique is De Corte, Lievens, and Sackett's (2007) Pareto-optimal weighting strategy. De Corte et al.'s strategy has been demonstrated on (a) a composite of cognitive and noncognitive (e.g., personality) tests (De Corte, Lievens, & Sackett, 2008) and (b) a composite of specific cognitive ability subtests (Wee, Newman, & Joseph, 2014). Both studies illustrated how Pareto-weighting (in contrast to unit weighting) could lead to substantial improvement in diversity outcomes (i.e., diversity improvement), sometimes more than doubling the number of job offers for minority applicants. The current work addresses a key limitation of the technique-the possibility of shrinkage, especially diversity shrinkage, in the Pareto-optimal solutions. Using Monte Carlo simulations, sample size and predictor combinations were varied and cross-validated Pareto-optimal solutions were obtained. Although diversity shrinkage was sizable for a composite of cognitive and noncognitive predictors when sample size was at or below 500, diversity shrinkage was typically negligible for a composite of specific cognitive subtest predictors when sample size was at least 100. Diversity shrinkage was larger when the Pareto-optimal solution suggested substantial diversity improvement. When sample size was at least 100, cross-validated Pareto-optimal weights typically outperformed unit weights-suggesting that diversity improvement is often possible, despite diversity shrinkage. Implications for Pareto-optimal weighting, adverse impact, sample size of validation studies, and optimizing the diversity-job performance tradeoff are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  1. Regional brain shrinkage over two years: individual differences and effects of pro-inflammatory genetic polymorphisms.

    Science.gov (United States)

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

    2014-12-01

    We examined regional changes in brain volume in healthy adults (N=167, age 19-79years 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 PhG, and individual differences in change were noted in all regions, except the OF. Pro-inflammatory genetic variants modified shrinkage in PhG and CbH. Carriers of two T alleles of interleukin-1β (IL-1β C-511T, rs16944) and a T allele of methylenetetrahydrofolate reductase (MTHFR C677T, 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.

  2. Capability poverty by deficits in net dietary intake at early age – neglected by the Rangarajan poverty line

    Directory of Open Access Journals (Sweden)

    Per A Eklund

    2014-11-01

    Full Text Available Introduction: The Rangarajan Expert Group set up to improve the methodology for measuring poverty fails to: (i shift from uncertain assessments of calorie - consumption poverty to use of ‘direct’ determinants of deficits in net dietary intake, indicating risk of capability poverty; [1,2] (ii include vegetables and fruit as an additional food category; and (iii consider inequity in child nutritional outcomes.  The 2014 poverty line includes raised expenditure on calories, meat, protein and fats and four non-food categories. The report avoids the issue of disparities in social protection that drive capability poverty. It concludes that its normative food basket does offer “a basis for optimism on associated nutrition-status outcomes”. Rationale: Inferior nutrition status, compounded in the lowest wealth groups, argues for use of ‘direct’ indicators of net deficits in nutritional intake in poverty assessments, such as the growth curve of children and measurements of anaemia. [3,4] Objective: Where, and how, do diseases and poor nutrients, contribute to rising deficits in net dietary intake? In 20 of 106 districts, in six states, from the 2002-04 LDHS-2 to the 2011 Hungama survey, child underweight (<-2SD, 5y increased by more than 5 percentage points. [5] Why? Methods and results: Literature confirms socio-economic rationale of addressing capability poverty indicated by child chronic undernutrition. [6,7,8] Iron-poor vegetarian diets, limited coverage of iron supplementation to young children and of food fortification in low-income settings, argue for raised intake of fruit and vegetables. [9] Conclusion: Capability poverty, driven by nutritional deficits at early age, perpetuates socio-economic disparities. Will location-specific determinants be addressed of rising deficits in net dietary intake at early age? Will iron - rich vegetables and fruits become an additional food group in a revised poverty line? 

  3. Polymorphisms in the SULF1 gene are associated with early age of onset and survival of ovarian cancer

    Directory of Open Access Journals (Sweden)

    Mills Gordon B

    2011-01-01

    Full Text Available Abstract Background SULF1 (sulfatase 1 selectively removes the 6-O-sulphate group from heparan sulfate, changing the binding sites for extracellular growth factors. SULF1 expression has been reported to be decreased in various cancers, including ovarian cancer. We hypothesized that single nucleotide polymorphisms (SNPs of SULF1 would impact clinicopathologic characteristics. Methods We genotyped five common (minor allele frequency>0.05 regulatory SNPs with predicted functionalities (rs2623047 G>A, rs13264163 A>G, rs6990375 G>A, rs3802278 G>A, and rs3087714 C>T in 168 patients with primary epithelial ovarian cancer, using the polymerase chain reaction-restriction fragment length polymorphism method. Results We found that rs2623047 G>A was significantly associated with an early age of onset of ovarian cancer in the G allele dose-response manner (P = 0.027; Ptrend = 0.007 and that rs2623047 GG/GA genotypes were associated with longer progression-free survival; rs6990375 G>A was also associated with the early age of onset in the A allele dose-response manner (P = 0.013; Ptrend= 0.009. The significant differences in age of disease onset persisted among carriers of haplotypes of rs2623047 and rs6990375 (P = 0.014; Ptrend = 0.004. In luciferase reporter gene assays, rs2623047 G allele showed a slightly higher promoter activity than the A allele in the SKOV3 tumorigenic cell line. Conclusions These findings suggest that genetic variations in SULF1 may play a role in ovarian cancer onset and prognosis. Further studies with large sample sizes and of the mechanistic relevance of SULF1 SNPs are warranted.

  4. Captures, Cutoffs, and Autogenic Drainage Basin Reorganization from Bedrock River Meandering in the Oregon Coast Range

    Science.gov (United States)

    Johnson, K. N.; Finnegan, N. J.

    2015-12-01

    Meandering bedrock channels in the Oregon Coast Range (OCR), USA, have lateral migration rates far in excess of vertical incision rates. Consequently, the sweeping of trunk streams through this landscape can locally exert a much stronger influence on tributary channel long profiles than far-field tectonic forcing of base-level. Here, we use LiDAR-data to explore the influence of lateral channel mobility on the evolution of tributaries to the Smith River, in the OCR. We focus on two processes that dramatically and instantaneously change tributary long profiles: 1) Capture of tributaries by growing meander bends, and 2) Meander bend neck cutoffs on the main-stem that leave tributaries disconnected from base-level lowering. We focus on these two types of events because they provide clear examples of autogenic drivers of landscape disequilibrium at the sub-watershed scale in a landscape that is commonly argued to reflect steady tectonic forcing of base-level. We show that tributary streams are significantly more likely to flow into the leading edge of meander bends, testifying to the repeated capture of tributaries by growing bends. Examples of eminent captures by migrating bends, and examples with large knick points along recently captured tributaries suggest that the autogenic capture of tributaries by growing bends is a fundamental cause of transience in tributary channels in this landscape. To demonstrate the influence of the process of meander bend neck cutoff on tributary long profile evolution, we compare the long profiles of 34 tributaries that were hung above the main-stem of the Smith River following neck cutoff events. These stagnated tributary channels typically exhibit large convexities that record ongoing lowering of the trunk stream. Measured heights of these hanging tributaries implies that the timescale of adjustment for tributaries following cutoff events is ~ 105-106 years. The timescale of adjustment of tributary channels following meander cutoff

  5. Allogeneic and autogenous transplantations of MSCs in treatment of the physeal bone bridge in rabbits

    Directory of Open Access Journals (Sweden)

    Urbanova Lucie

    2008-09-01

    Full Text Available Abstract Background The aim of this experimental study on New Zealand's white rabbits was to find differences in the results of treating the distal physeal femoral defect by the transplantation of autologous or allogeneic mesenchymal stem cells (MSCs. After the excision of a created bone bridge in the distal physis of the right femur, modified composite scaffold with MSCs was transplanted into the defect. In animal Group A (n = 11 autogenous MSCs were implanted; in animal Group B (n = 15 allogeneic MSCs were implanted. An iatrogenic physeal defect of the left femur of each animal not treated by MSCs transplantation served as control. The rabbits were euthanized four months after the transplantation. The treatment results were evaluated morphometrically (femoral length and valgus deformity measurement and histologically (character and quality of the new cartilage. Results Four months after the transplantation, the right femurs of the animals in Group A were on average longer by 0.50 ± 0.04 cm (p = 0.018 than their left femurs, the right femurs of rabbits in Group B were on average longer by 0.43 ± 0.01 cm (p = 0.028 than their left femurs. 4 months after the therapeutic transplantation of MSCs valgus deformity of the distal part of the right femur of animals in Group A was significantly lower (by 4.45 ± 1.86° than that of their left femur (p = 0.028, in Group B as well (by 3.66 ± 0.95° than that of their left femur p = 0.001. However, no significant difference was found between rabbits with transplanted autogenous MSCs (Group A and rabbits with transplanted allogeneic MSCs (Group B either in the femur length (p = 0.495, or in its valgus deformity (p = 0.1597. After the MSCs transplantation the presence of a newly formed hyaline cartilage was demonstrated histologically in all the animals (both groups. The ability of transplanted MSCs to survive in the damaged physis was demonstrated in vivo by magnetic resonance, in vitro by Perls reaction

  6. Sparse contrast-source inversion using linear-shrinkage-enhanced inexact Newton method

    KAUST Repository

    Desmal, Abdulla

    2014-07-01

    A contrast-source inversion scheme is proposed for microwave imaging of domains with sparse content. The scheme uses inexact Newton and linear shrinkage methods to account for the nonlinearity and ill-posedness of the electromagnetic inverse scattering problem, respectively. Thresholded shrinkage iterations are accelerated using a preconditioning technique. Additionally, during Newton iterations, the weight of the penalty term is reduced consistently with the quadratic convergence of the Newton method to increase accuracy and efficiency. Numerical results demonstrate the applicability of the proposed method.

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

    Science.gov (United States)

    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.

  8. The effect of mold surface topography on plastic parat in-process shrinkage in injection molding

    DEFF Research Database (Denmark)

    Arlø, Uffe Rolf; Hansen, Hans Nørgaard; Kjær, Erik Michael

    2003-01-01

    An experimental study of the effect of mold surface roughness on in-process in-flow linear part shrinkage in injection molding has been carried out. The investigation is based on an experimental two-cavity tool, where the cavities have different surface topographies, but are otherwise identical....... The study has been carried out for typical commercial polystyrene and polypropylene grades. The relationship between mold surface topography and linear shrinkage has been investigated with an experimental two-cavity mold producing simple rectangular parts with the nominal dimensions 1 x 25 x 50 mm (see...

  9. Method and application of wavelet shrinkage denoising based on genetic algorithm

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Genetic algorithm (GA) based on wavelet transform threshold shrinkage (WTS) and translation-invafiant threshold shrinkage (TIS) is introduced into the method of noise reduction, where parameters used in WTS and TIS, such as wavelet function,decomposition levels, hard or soft threshold and threshold can be selected automatically. This paper ends by comparing two noise reduction methods on the basis of their denoising performances, computation time, etc. The effectiveness of these methods introduced in this paper is validated by the results of analysis of the simulated and real signals.

  10. Alcohol consumption and frontal lobe shrinkage: study of 1432 non-alcoholic subjects

    OpenAIRE

    Kubota, M.; Nakazaki, S.; Hirai, S.; Saeki, N; YAMAURA, A.; Kusaka, T

    2001-01-01

    OBJECTIVES—To evaluate the influences of chronic alcohol consumption on brain volume among social drinkers, as it is well known that alcohol misusers have a high risk of brain shrinkage.
METHODS—Frontal lobe volumes on MRI were compared with the current alcohol habits of consecutive 1432 non-alcoholic subjects.
RESULTS—After adjusting for other variables, age was found to be the most powerful promoting factor for the shrinkage with a odds ratio of 2.8 (95% confidence i...

  11. Hinge-free topology optimization with embedded translation-invariant differentiable wavelet shrinkage

    DEFF Research Database (Denmark)

    Yoon, G. H.; Kim, Y. Y.; Bendsøe, Martin P.;

    2004-01-01

    In topology optimization applications for the design of compliant mechanisms, the formation of hinges is typically encountered. Often such hinges are unphysical artifacts that appear due to the choice of discretization spaces for design and analysis. The objective of this work is to present a new...... in the multiscale design space. To imbed the shrinkage method implicitly in the optimization formulation and thus facilitate sensitivity analysis, the shrinkage method is made differentiable by means of differentiable versions of logical operators. The validity of the present method is confirmed by solving typical...... two-dimensional compliant mechanism design problems....

  12. Properties evaluation of silorane, low-shrinkage, non-flowable and flowable resin-based composites in dentistry

    Directory of Open Access Journals (Sweden)

    Rodrigo R. Maia

    2015-06-01

    Full Text Available Purpose. This study tested the null hypothesis that different classes of direct restorative dental materials: silorane-based resin, low-shrinkage and conventional (non-flowable and flowable resin-based composite (RBC do not differ from each other with regard to polymerization shrinkage, depth of cure or microhardness.Methods. 140 RBC samples were fabricated and tested by one calibrated operator. Polymerization shrinkage was measured using a gas pycnometer both before and immediately after curing with 36 J/cm2 light energy density. Depth of cure was determined, using a penetrometer and the Knoop microhardness was tested from the top surface to a depth of 5 mm.Results. Considering polymerization shrinkage, the authors found significant differences (p < 0.05 between different materials: non-flowable RBCs showed lower values compared to flowable RBCs, with the silorane-based resin presenting the smallest shrinkage. The low shrinkage flowable composite performed similarly to non-flowable with significant statistical differences compared to the two other flowable RBCs. Regarding to depth of cure, low-shrinkage flowable RBC, were most effective compared to other groups. Microhardness was generally higher for the non-flowable vs. flowable RBCs (p < 0.05. However, the values for low-shrinkage flowable did not differ significantly from those of non-flowable, but were significantly higher than those of the other flowable RBCs.Clinical Significance. RBCs have undergone many modifications as they have evolved and represent the most relevant restorative materials in today’s dental practice. This study of low-shrinkage RBCs, conventional RBCs (non-flowable and flowable and silorane-based composite—by in vitro evaluation of volumetric shrinkage, depth of cure and microhardness—reveals that although filler content is an important determinant of polymerization shrinkage, it is not the only variable that affects properties of materials that were tested in

  13. Autogenic-feedback training: A preventive method for space adaptation syndrome

    Science.gov (United States)

    Cowings, Patricia S.; Sharp, Joseph C.; Toscano, William B.; Kamiya, Joe; Miller, Neal E.

    1987-01-01

    The progress made to date on the reduction of data for Spacelab 3 Shuttle experiment, No. 3AFT23 is reported. Four astronauts participated as subjects in this experiment. Crewmen A and B served as treatment subjects (i.e., received preflight training for control of their own motion sickness symptoms) and Crewmen C and D served as control (i.e., did not receive training). A preliminary evaluation of Autogenic Feedback Training (AFT) was made from visual inspections of graphs that were generated from the preflight and inflight and inflight physiological data which included: (1) Baseline rotating chair tests for all crewmen; (2) Posttraining rotating chair tests of treatment groups subjects; (3) Preflight data from Joint Integrated Simulations for all crewmen; and (4) Flight data for all crewmen during mission days 0 through 4, and mission day 6 for treatment subjects only. A summary of the findings suggested by these data is outlined.

  14. Supplementation of autogenous bone graft with coralline hydroxyapatite in posterior spine fusion for idiopathic adolescent scoliosis.

    Science.gov (United States)

    Mashoof, A Allen; Siddiqui, Saqib A; Otero, Marilyn; Tucci, James J

    2002-10-01

    Twenty-seven consecutive patients with adolescent idiopathic scoliosis underwent posterior spinal fusion with pediatric Texas Scottish Rite Hospital instrumentation. Coralline hydroxyapatite (Interpore, Irvine, Calif) was mixed with limited autograft from posterior iliac crest (an approximate 70/30 ratio of coralline hydroxyapatite to autograft). Patient evaluation was based on clinical and radiographic findings. On initial radiographic evaluation, a "snowstorm" appearance consistent with the exoskeleton of the coralline hydroxyapatite was observed. After two years, the fusion mass had a "marble-like" appearance with distinct decreased visibility of the disk spaces in the fusion mass. This latter stage of "marbilization correlated with solid fusion clinically. All patients achieved solid fusion at an average follow-up of 27 months. Coralline hydroxyapatite is safe, biocompatible, and effective in augmenting autogenous bone graft in the treatment of idiopathic adolescent scoliosis with posterior spinal fusion. In addition to decreased donor site morbidity, this may be invaluable in cases where there is insufficient autograft available.

  15. Analysis of the inorganic component of autogenous tooth bone graft material.

    Science.gov (United States)

    Kim, Young-Kyun; Kim, Su-Gwan; Oh, Ji-Su; Jin, Seung-Chan; Son, Jun-Sik; Kim, Suk-Young; Lim, Soo-Young

    2011-08-01

    This study was performed to identify the calcium phosphate minerals, chemical element and Ca/P ratio and to examine the surface structure of autogenous tooth bone grafting material (AutoBT) which recently developed and applied clinically as a bone graft materials. The analytical results showed that AutoBT is composed of low-crystalline hydroxyapatite (HA) and possibly other calcium phosphate minerals, which is similar to the minerals of human bone tissues. And the dental crown portion was composed of high-crystalline calcium phosphate minerals (mainly HA) with higher Ca/P ratio while the root portion was mainly composed of low-crystalline calcium phosphates with relatively low Ca/P ratio.

  16. Retrograde tracing of fluorescent gold after autogenous nerve transplantation on spinal cord injured in rats

    DEFF Research Database (Denmark)

    Lin, X; Liu, W; Ding, Ming;

    2016-01-01

    Objective To investigate the changes of the fluorescent gold retrograde tracing autogenous nerve transplantation on spinal cord injured in rats. Methods The animals were divided into two groups, with modified Allen impact method to establish model of spinal cord injury. After 4 weeks......, the transplantation group using autologous sural nerve graft to repair spinal cord injury period and non-transplantation group was only exposed incision without treatment. In the 4, 6 and 8 weeks after operation, the retrograde tracing of FG Fluoro-Gold was performed to discover the recovery of the axial plasma.......01). Conclusion After spinal cord injury, autologous nerve graft was repaired and survived well and promote the recovery of spinal cord injury segment shaft pulp transportation function....

  17. Autogenous vaccination for control of yersiniosis (Yersiniosis salmonis in the salmonid aquaculture in Republic of Macedonia

    Directory of Open Access Journals (Sweden)

    Cvetkovik Aleksandar

    2009-05-01

    Full Text Available The aim of this study was to produce an autogenous vaccine from Yersinia ruckeri isolate and to test it’s efficacy in field conditions. Colonies of Yersinia ruckeri biotype I isolated from rainbow trout with haemorrhagic septicemia were cultivated in TSB and inactivated with formalin. The vaccine was diluted and administered by immersion of rainbow trout fry (~ 4.5 g BW in the vacinal suspension. The experimental infection was done 28 days post vaccination by immersing the fry in infectious suspension of the same isolate. Mortality of the control and vaccinated fish was 87% and 11%, respectively. Vaccinated fish showed high level of gained specific resistance to the infection (RPS 87,4%.

  18. Psychosomatic aspects in idiopathic infertility: effects of treatment with autogenic training.

    Science.gov (United States)

    O'Moore, A M; O'Moore, R R; Harrison, R F; Murphy, G; Carruthers, M E

    1983-01-01

    It has long been recognised that there is a relationship between emotional stress and some forms of infertility. We have endeavoured to estimate "stress' levels before and after Autogenic Training in 15 couples with infertility of at least two years' duration. Potential stress markers were: plasma prolactin, total urinary free cortisol and catecholamines, and four psychological tests: Spielberger State-Trait anxiety scale, Taylor Manifest Anxiety Scale, the Cattell 16 personality factor questionnaire, and the Eysenck Personality Questionnaire. A control group of ten normal couples was included for comparison. The biochemical finding of higher mean prolactin levels in the female patients vs their controls was of particular interest. The significant reduction of the prolactin level, in parallel with decreased anxiety scores following treatment, supports the hypothesis that the elevated prolactin levels in these patients are indeed linked with emotional stress.

  19. Autogenous wisdom tooth transplantation: A case series with 6-9 months follow-up

    Directory of Open Access Journals (Sweden)

    Tatjana Nimcenko

    2014-01-01

    Full Text Available Tooth transplantation can be considered a valid and predictable treatment option for rehabilitating young patients with permanent teeth loss. This study presents several cases of successful autogenous tooth transplantation with a 6-9 months follow-up. Tooth auto-transplantation can be considered a reasonable option for replacing missing teeth when a donor tooth is available. The auto-transplantation of a right mandibular third molar with compromised function and esthetics to replace the residual roots resulting from coronal destruction due to extensive carious lesion of the second molar in the same quadrant as shown in the presented cases can result a viable treatment alternative especially in a young patient that cannot undergo dental implant therapy. Transplantation of mature third molar seems to be a promising method for replacing a lost permanent molar tooth and restoring esthetics and function. This clinical procedure showed excellent functional and esthetical long-term results in the analyzed cases.

  20. Autogenous wisdom tooth transplantation: A case series with 6-9 months follow-up

    Science.gov (United States)

    Nimčenko, Tatjana; Omerca, Gražvydas; Bramanti, Ennio; Cervino, Gabriele; Laino, Luigi; Cicciù, Marco

    2014-01-01

    Tooth transplantation can be considered a valid and predictable treatment option for rehabilitating young patients with permanent teeth loss. This study presents several cases of successful autogenous tooth transplantation with a 6-9 months follow-up. Tooth auto-transplantation can be considered a reasonable option for replacing missing teeth when a donor tooth is available. The auto-transplantation of a right mandibular third molar with compromised function and esthetics to replace the residual roots resulting from coronal destruction due to extensive carious lesion of the second molar in the same quadrant as shown in the presented cases can result a viable treatment alternative especially in a young patient that cannot undergo dental implant therapy. Transplantation of mature third molar seems to be a promising method for replacing a lost permanent molar tooth and restoring esthetics and function. This clinical procedure showed excellent functional and esthetical long-term results in the analyzed cases. PMID:25540668

  1. Effect of Autogenous Arc Welding Processes on Tensile and Impact Properties of Ferritic Stainless Steel Joints

    Institute of Scientific and Technical Information of China (English)

    A K Lakshminarayanan; K Shanmugam; V Balasubramanian

    2009-01-01

    The effect of autogeneous arc welding processes on tensile and impact properties of ferritic stainless steel conformed to AISI 409M grade is studied.Rolled plates of 4 mm thickness have been used as the base material for preparing single pass butt welded jointa.Tensile and impact properties,microhardness,microstructure,and fracture surface morphology of continuous current gas tungsten arc welding (CCGTAW),pulsed current gas tungsten arc welding (PCGTAW),and plasma arc welding (PAW) joints are evaluated and the results are compared.It is found that the PAW joints of ferritic stainless steel show superior tensile and impact properties when compared with CCGTAW and PCGTAW joints,and this is mainly due to lower heat input,finer fusion zone grain diameter,and higher fusion zone hardness.

  2. Application of digital image correlation to full-field measurement of shrinkage strain of dental composites

    Institute of Scientific and Technical Information of China (English)

    Jian-ying LI; Andrew LAU; Alex S.L.FOK

    2013-01-01

    Objectives:Polymerization shrinkage of dental composites remains a major concern in restorative dentistry because it can lead to micro-cracking of the tooth and debonding at the tooth-restoration interface.The aim of this study was to measure the full-field polymerization shrinkage of dental composites using the optical digital image correlation (DIC) method and to evaluate how the measurement is influenced by the factors in experiment setup and image analysis.Methods:Four commercial dental composites,Premise Dentine,Z100,Z250 and Tetric EvoCeram,were tested.Composite was first placed into a slot mould to form a bar specimen with rectangular-section of 4 mm×2 mm,followed by the surface painting to create irregular speckles.Curing was then applied at one end of the specimen while the other part were covered against curing light for simulating the clinical curing condition of composite in dental cavity.The painted surface was recorded by a charge-coupled device (CCD) camera before and after curing.Subsequently,the volumetric shrinkage of the specimen was calculated with specialist DIC software based on image cross correlation.In addition,a few factors that may influence the measuring accuracy,including the subset window size,speckle size,illumination light and specimen length,were also evaluated.Results:The volumetric shrinkage of the specimen generally decreases with increasing distance from the irradiated surface with a conspicuous exception being the composite Premise Dentine as its maximum shrinkage occurred at a subsurface distance of about 1 mm instead of the irradiated surface.Zl00 had the greatest maximum shrinkage strain,followed by Z250,Tetric EvoCeram and then Premise Dentine.Larger subset window size made the shrinkage strain contour smoother.But the cost was that some details in the heterogeneity of the material were lost.Very small subset window size resulted in a lot of noise in the data,making it difficult to discern the general pattern in the strain

  3. The Short-Term Effect of Breathing Tasks Via an Incentive Spirometer on Lung Function Compared With Autogenic Drainage in Subjects With Cystic Fibrosis

    National Research Council Canada - National Science Library

    Sokol, Gil; Vilozni, Daphna; Hakimi, Ran; Lavie, Moran; Sarouk, Ifat; Bat-El Bar; Dagan, Adi; Ofek, Miryam; Efrati, Ori

    2015-01-01

    ...) 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...

  4. The use of platelet-rich fibrin (PRF) and PRF-mixed particulated autogenous bone graft in the treatment of bone defects: An experimental and histomorphometrical study

    National Research Council Canada - National Science Library

    Kökdere, Nesligül Niyaz; Baykul, Timuçin; Findik, Yavuz

    2015-01-01

    .... In recent studies, it is pointed out that, platelet-rich fibrin (PRF) which is derived autogenously from the own blood of the individuals, increase regeneration and accelerate the healing of the wound, due to the consisting various growing factors...

  5. Maxillary sinus floor augmentation with Bio-Oss or Bio-Oss mixed with autogenous bone as graft: a systematic review

    DEFF Research Database (Denmark)

    Jensen, Thomas; Schou, Søren; Stavropoulos, Andreas

    2012-01-01

    Aims: The objective of the present systematic review was to test the hypothesis of no differences in the implant treatment outcome when Bio-Oss or Bio-Oss mixed with autogenous bone is used as graft for the maxillary sinus floor augmentation (MSFA) applying the lateral window technique. Material...... was compared in one study demonstrating no statistically significant difference. The implant survival was 96% with Bio-Oss and 94% with a mixture of 80% Bio-Oss and 20% autogenous mandibular bone. Addition of a limited amount of autogenous bone to Bio-Oss seemed not to increase the amount of new bone formation...... and bone-to-implant contact compared with Bio-Oss. Conclusions: Therefore, the hypothesis of no differences between the use of Bio-Oss or Bio-Oss mixed with autogenous bone as graft for MSFA could neither be confirmed nor rejected. To cite this article: Jensen T, Schou S, Stavropoulos A, Terheyden H...

  6. Shrinkage insensitivity of NKCC1 in myosin II-depleted cytoplasts from Ehrlich ascites tumor cells

    DEFF Research Database (Denmark)

    Hoffmann, Else K; Pedersen, Stine F

    2007-01-01

    Protein phosphorylation/dephosphorylation and cytoskeletal reorganization regulate the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) during osmotic shrinkage; however, the mechanisms involved are unclear. We show that in cytoplasts, plasma membrane vesicles detached from Ehrlich ascites tumor cells (EATC...

  7. Influence of Superplasticizers on Strength and Shrinkage Cracking of Cement Mortar under Drying Conditions

    Institute of Scientific and Technical Information of China (English)

    MA Baoguo; WANG Xin'gang; LI Xiangguo; YANG Lei

    2007-01-01

    The effects of polynaphthalene series superplasticizers(PNS) with a low content of sodium sulfate (H-UNF),with a high content of sodium sulfate(C-UNF) and polycarboxylate type superplasticizer (PC) on strength and shrinkage cracking of cement mortar under drying conditions were investigated by means of multi-channel ellipse ring shrinkage cracking test, free shrinkage and strength test. The general effect of PNS and PC is to increase the initial cracking time of mortars, and decrease the cracking sensitivity of mortars. As for decreasing the cracking sensitivity of mortars, PC>H-UNF>C-UNF. To incorporate superplasticizers is apparently to increase the free shrinkage of mortars when keeping the constant w/b ratio and the content of cement pastes. As for the effect of controlling the volume stability of mortars, PC>C-UNF>H-UNF. Maximum crack width of mortars containing PC is lower, but the development rate of maximum crack width of mortars containing H-UNF is faster in comparison with control mortars. The flexural and compressive strengths of mortars at 28-day increase with increasing superplasticizer dosages under drying conditions. PC was superior to PNS in the aspect of increasing strength.

  8. Quantification of shrinkage microcracking in young mortar with fluorescence light microscopy and ESEM

    NARCIS (Netherlands)

    Bisschop, J.; Van Mier, J.C.M.

    1999-01-01

    In this paper a method is described to quantify shrinkage microcracking in young mortar by means of crack mapping. Visualisation of the microcracks is realised with two techniques: Fluorescence Light Microscopy (FLM) and Environmental Scanning Electron Microscopy (ESEM). The preliminary results obta

  9. Shrinkage of bubbles and drops in the lattice Boltzmann equation method for nonideal gases

    Science.gov (United States)

    Zheng, Lin; Lee, Taehun; Guo, Zhaoli; Rumschitzki, David

    2014-03-01

    One characteristic of multiphase lattice Boltzmann equation (LBE) methods is that the interfacial region has a finite (i.e., noninfinitesimal) thickness known as a diffuse interface. In simulations of, e.g., bubble or drop dynamics, for problems involving nonideal gases, one frequently observes that the diffuse interface method produces a spontaneous, nonphysical shrinkage of the bubble or drop radius. In this paper, we analyze in detail a single-fluid two-phase model and use a LBE model for nonideal gases in order to explain this fundamental problem. For simplicity, we only investigate the static bubble or droplet problem. We find that the method indeed produces a density shift, bubble or droplet shrinkage, as well as a critical radius below which the bubble or droplet eventually vanishes. Assuming that the ratio between the interface thickness D and the initial bubble or droplet radius r0 is small, we analytically show the existence of this density shift, bubble or droplet radius shrinkage, and critical bubble or droplet survival radius. Numerical results confirm our analysis. We also consider droplets on a solid surface with different curvatures, contact angles, and initial droplet volumes. Numerical results show that the curvature, contact angle, and the initial droplet volume have an effect on this spontaneous shrinkage process, consistent with the survival criterion.

  10. Shrinkage kinetics of a methacrylate- and a silorane-based resin composite: effect on marginal integrity

    NARCIS (Netherlands)

    Gregor, L.; Bortolotto, T.; Feilzer, A.J.; Krejci, I.

    2013-01-01

    Purpose: To evaluate the relation between the linear displacement (LD), shrinkage force (SF) and marginal adaptation of a methacrylate- and a silorane-based composite. Materials and Methods: The LD and SF of 8 samples made of Filtek Supreme XT (methacrylate-based composite) and Filtek Silorane (silo

  11. Detection and Influence of Shrinkage Pores and Nonmetallic Inclusions on Fatigue Life of Cast Aluminum Alloys

    Science.gov (United States)

    Tijani, Yakub; Heinrietz, André; Stets, Wolfram; Voigt, Patrick

    2013-12-01

    In the current study, test bars of cast aluminum alloys EN AC-AlSi8Cu3 and EN AC-AlSi7Mg0.3 were produced with a defined amounts of shrinkage pores and oxides. For this purpose, a permanent mold with heating and cooling devices for the generation of pores was constructed. The oxides were produced by contaminating the melt. The specimens and their corresponding defect distributions were examined and quantified by X-ray computer tomography (CT) and quantitative metallography, respectively. A special test algorithm for the simultaneous image analyses of pores and oxides was developed. Fatigue tests were conducted on the defective samples. It was found that the presence of shrinkage pores lowers the fatigue strength, and only few oxide inclusions were found to initiate fatigue cracks when shrinkage pores are present. The results show that the pore volume is not sufficient to characterize the influence of shrinkage pores on fatigue life. A parametric model for the calculation of fatigue life based on the pore parameters obtained from CT scans was implemented. The model accounts for the combined impact of pore location, size, and shape on fatigue life reduction.

  12. Properties of a New Dental Photocurable Matrix Resin with Low Shrinkage

    Institute of Scientific and Technical Information of China (English)

    FU Jing; JIA Fang; XU Haiping; JI Baohui; LIU Xiaoqing

    2011-01-01

    In order to reduce the amount of volumetric shrinkage that occurs in dental composites as a result of curing, a new kind of dental matrix resin combining bisphenol-S-bis(3-meth acry late-2-hydroxy propyl)ether(BisS-GMA) with the expanding monomer unsaturated spiro orthoesters 2-methylene-1, 4, 6-trispiro[4, 4] nonane (SOE) was prepared, with triethylene glycol dimethacrylate (TEGDMA) as diluent. CQ (camphorquinone) of 1wt% and DMAEMA (2-(dimethylamino) ethyl meth acrylate) of 2wt% were used as photoinitiation system to initiate the copolymerization of the matrix resins. The performance including volumetric shrinkage, degree of conversion and condition of the ring-opening reaction of SOE, as well as curing time and the tensile bond strength were investigated respectively by the dilatometer, Fourier transfer infrared, the universal testing machine, and so on.The ring-opening polymerization of SOE occurred. Meanwhile, the obtain copolymers were crosslinked. The matrix resin containing BisS-GMA and SOE showed a reduced amount of volumetric shrinkage at 1.52%, which is a promising strategy for obtaining a polymer with a low amount of volumetric shrinkage. Furthermore, the other properties were not compromised.

  13. Astrocytic mechanisms explaining neural-activity-induced shrinkage of extraneuronal space.

    Directory of Open Access Journals (Sweden)

    Ivar Østby

    2009-01-01

    Full Text Available Neuronal stimulation causes approximately 30% shrinkage of the extracellular space (ECS between neurons and surrounding astrocytes in grey and white matter under experimental conditions. Despite its possible implications for a proper understanding of basic aspects of potassium clearance and astrocyte function, the phenomenon remains unexplained. Here we present a dynamic model that accounts for current experimental data related to the shrinkage phenomenon in wild-type as well as in gene knockout individuals. We find that neuronal release of potassium and uptake of sodium during stimulation, astrocyte uptake of potassium, sodium, and chloride in passive channels, action of the Na/K/ATPase pump, and osmotically driven transport of water through the astrocyte membrane together seem sufficient for generating ECS shrinkage as such. However, when taking into account ECS and astrocyte ion concentrations observed in connection with neuronal stimulation, the actions of the Na(+/K(+/Cl(- (NKCC1 and the Na(+/HCO(3 (- (NBC cotransporters appear to be critical determinants for achieving observed quantitative levels of ECS shrinkage. Considering the current state of knowledge, the model framework appears sufficiently detailed and constrained to guide future key experiments and pave the way for more comprehensive astroglia-neuron interaction models for normal as well as pathophysiological situations.

  14. Numerical Analysis of Influence of the Mold Material on the Distribution of Shrinkage Cavities

    Directory of Open Access Journals (Sweden)

    R. Dyja

    2013-01-01

    Full Text Available Production of castings, like any other field of technology is aimed at providing high-quality product, free from defects. One of the maincauses of defects in castings is the phenomenon of shrinkage of the casting. This phenomenon causes the formation of shrinkage cavitiesand porosity in the casting. The major preventive measure is supplementing a shortage of liquid metal. For supplement to be effective, it is necessary to use risers in proper shapes. Usually, the risers are selected on the basis of determination the place of formation of hot-spots in the castings. Although in these places the shrinkage defects are most likely to occur, shape and size of these defects are also affected by other factors. The article describes the original program setting out the shape and location of possible cavities in the casting. In the program is also taken into account the effect of temperature on the change in volume of liquid metal and the resultant differences in the shape and size of formed shrinkage cavities. The aim of the article is to describe the influence that have material properties of the mold on the simulation results.

  15. Urban shrinkage, local housing markets and the role of voluntary community organisations

    DEFF Research Database (Denmark)

    Larsen, Jacob Norvig

    Since the beginning of the crisis in 2007-08 urban shrinkage has hit a large number of Danish municipalities, towns and villages outside the two major metropolitan areas in the country .Abandoned homes, plunging property prices and out-migration are among the major symptoms. As a consequence of t...

  16. A modelling study of drying shrinkage damage in concrete repair systems

    NARCIS (Netherlands)

    Lukovic, M.; Savija, B.; Schlangen, E.; Ye, G.; van Breugel, K.

    2014-01-01

    Differential shrinkage between repair material and concrete substrate is considered to be the main cause of premature failure of repair systems (Martinola, Sadouki et al. 2001, Beushausen and Alexander 2007). Magnitude of induced stresses depends on many factors, for example the amount of restraint,

  17. EFFECTS OF DYNEL FIBER BLENDING ON YARN SHRINKAGE AND WOVEN-FABRIC PROPERTIES

    Science.gov (United States)

    A 50/50 picker blend warp was woven with fillings from the various blends and twists. The fabrics were scoured and treated for water repellency . Highest...results of yarn and fabric shrinkage and air permeability. All water repellency tests were poor; fabrics with low-twist fillings were better than those

  18. Prediction of Shrinkage Porosity Defect in Sand Casting Process of LM25

    Science.gov (United States)

    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.

  19. Porous stainless steel hollow fibers with shrinkage-controlled small radial dimensions

    NARCIS (Netherlands)

    Luiten-Olieman, Mieke W.J.; Raaijmakers, Michiel J.T.; Winnubst, Louis; Wessling, Matthias; Nijmeijer, Arian; Benes, Nieck E.

    2011-01-01

    A method is presented for the preparation of thin (∼250 μm) porous stainless steel hollow fiber membranes based on dry–wet spinning of a particle-loaded polymer solution followed by heat treatment. Extraordinarily small radial dimensions were achieved by controlled shrinkage during thermal treatment

  20. Sequential shrinkage and swelling underlie P2X7-stimulated lymphocyte phosphatidylserine exposure and death.

    Science.gov (United States)

    Taylor, Simon R J; Gonzalez-Begne, Mireya; Dewhurst, Stephen; Chimini, Giovanna; Higgins, Christopher F; Melvin, James E; Elliott, James I

    2008-01-01

    Patterns of change in cell volume and plasma membrane phospholipid distribution during cell death are regarded as diagnostic means of distinguishing apoptosis from necrosis, the former being associated with cell shrinkage and early phosphatidylserine (PS) exposure, whereas necrosis is associated with cell swelling and consequent lysis. We demonstrate that cell volume regulation during lymphocyte death stimulated via the purinergic receptor P2X7 is distinct from both. Within seconds of stimulation, murine lymphocytes undergo rapid shrinkage concomitant with, but also required for, PS exposure. However, within 2 min shrinkage is reversed and swelling ensues ending in cell rupture. P2X7-induced shrinkage and PS translocation depend upon K+ efflux via KCa3.1, but use a pathway of Cl- efflux distinct from that previously implicated in apoptosis. Thus, P2X7 stimulation activates a novel pathway of cell death that does not conform to those conventionally associated with apoptosis and necrosis. The mixed apoptotic/necrotic phenotype of P2X7-stimulated cells is consistent with a potential role for this death pathway in lupus disease.

  1. Linear shrinkage test: justification for its reintroduction as a standard South African test method

    CSIR Research Space (South Africa)

    Sampson, LR

    2009-06-04

    Full Text Available Several problems with the linear shrinkage test specified in Method A4 of the THM 1 1979 were addressed as part of this investigation in an effort to improve the alleged poor reproducibility of the test and justify its reintroduction into THM 1. A...

  2. Brain shrinkage in alcoholics is not caused by changes in hydration: a pathological study.

    OpenAIRE

    Harper, C. G.; Kril, J J; Daly, J.M.

    1988-01-01

    Measurement of the water content of the cerebral white matter in 26 control and 24 alcoholic cases supports in vivo MRI studies and previous necropsy studies which appeared to show an increase in the water content in the alcoholic group. This negates the hypothesis that reversible brain shrinkage in alcoholics is caused by changes in the state of hydration.

  3. Differential brain shrinkage over 6 months shows limited association with cognitive practice.

    Science.gov (United States)

    Raz, Naftali; Schmiedek, Florian; Rodrigue, Karen M; Kennedy, Kristen M; Lindenberger, Ulman; Lövdén, Martin

    2013-07-01

    The brain shrinks with age, but the timing of this process and the extent of its malleability are unclear. We measured changes in regional brain volumes in younger (age 20-31) and older (age 65-80) adults twice over a 6 month period, and examined the association between changes in volume, history of hypertension, and cognitive training. Between two MRI scans, 49 participants underwent intensive practice in three cognitive domains for 100 consecutive days, whereas 23 control group members performed no laboratory cognitive tasks. Regional volumes of seven brain structures were measured manually and adjusted for intracranial volume. We observed significant mean shrinkage in the lateral prefrontal cortex, the hippocampus, the caudate nucleus, and the cerebellum, but no reliable mean change of the prefrontal white matter, orbital-frontal cortex, and the primary visual cortex. Individual differences in change were reliable in all regions. History of hypertension was associated with greater cerebellar shrinkage. The cerebellum was the only region in which significantly reduced shrinkage was apparent in the experimental group after completion of cognitive training. Thus, in healthy adults, differential brain shrinkage can be observed in a narrow time window, vascular risk may aggravate it, and intensive cognitive activity may have a limited effect on it.

  4. Significant reversibility of alcoholic brain shrinkage within 3 weeks of abstinence.

    Science.gov (United States)

    Trabert, W; Betz, T; Niewald, M; Huber, G

    1995-08-01

    Chronic alcoholism is often associated with brain shrinkage or atrophy. During recent years, it has been demonstrated that this shrinkage is, at least in part, reversible when abstinence is maintained. There are different hypotheses concerning the mechanisms for this reversibility, but many questions are still open. Especially the time conditions for these reversible changes are subject of discussion. Twenty-eight male patients with severe alcohol dependence were investigated in a computed tomographic study at the beginning of abstinence and 3 weeks later. Planimetric evaluation of 5 selected slices revealed a significant decrease in liquor areas and an increase of brain volume. The densitometric analysis showed an increase in brain tissue density. In a multiple regression approach it was shown that the reversibility was mostly influenced by the age of the patients. Our results support neither the hypothesis of an increase in brain water as the most important principle for reversibility in alcoholic brain shrinkage nor the hypothesis of augmented dendritic growth. Other mechanisms like reduced (during chronic intoxication) and normalized (during abstinence) cerebral hemoperfusion have to be considered as possible mechanisms for the reversibility of alcoholic brain shrinkage.

  5. The tissue shrinkage phenomenon on surgical margins in oral and oropharyngeal squamous cell carcinoma

    Institute of Scientific and Technical Information of China (English)

    David González-Ballester

    2016-01-01

    Aim: One of the most important factors associated with recurrence rate and overall survival is the status of surgical margin of resection free of disease. However, sometimes, the margins measured intra-operatively at the time of surgery differ of those measured by the pathologist in the histopathologic analysis. Faced with this dilemma, a literature review of the best available evidence was conducted in an attempt to determine how the phenomenon of tissue shrinkage may influence on the surgical margin of resection in patients undergoing oral and oropharyngeal squamous cell carcinoma (SCC).Methods: An electronic and manual search was conducted by one reviewer. A combination of controlled Medical Subjects Headings and keywords were used as search strategy. Inclusion and exclusion criteria were established.Results: Finally, after an exhaustive selection process, four articles fulfilled the inclusion criteria and were analyzed. All articles reported a decrease of surgical margin after resection. The tumor site and tumor stage seem to influence in degree of margin shrinkage.Conclusion:Tissue shrinkage on surgical margins of resection in oral SCC is a tangible phenomenon. There is a significant discrepancy between margins measured intraoperatively previous to resection and margins measured by pathologist after histologic processing. The highest percentage of retraction occurs at the time of resection. Margin shrinkage based on tumor site and tumor stage should be considered by any oncologic surgeon to ensure adequate margins of resection cleared of tumor.

  6. Shrinkages in heavy-sized cast components of nodular cast iron – NDT and fatigue

    Directory of Open Access Journals (Sweden)

    Bleicher Christoph

    2014-06-01

    Full Text Available Material defects like shrinkages, dross, pores and chunky graphite are likely to occur in thick-walled castings and are a challenge for the foundries and their customers. These defects are mostly detected with handheld ultrasonic testing (UT or X-ray analysis. Within a research project done at the Fraunhofer Institute for Structural Durability and System Reliability LBF, the fatigue of Dross, shrinkages and chunky graphite in thick-walled cast material GGG-40 was estimated based on X-ray and fatigue tests on bending specimens. High fatigue reductions were received for the different material imperfections. Based on these impressions a further research project was executed at the Fraunhofer LBF to get an estimation of the informational value of UT in relation to fatigue of shrinkages in thick-walled castings of the material EN-GJS-400-18U-LT, EN-GJS-450-18 and EN-GJS-700-2. With the help of X-ray analysis and the UT technique Sampling Phased Array (SPA information about geometry and density were derived for a numerical analysis of shrinkages in thick-walled castings concerning fatigue. The following text summarizes the fatigue results achieved in the two research projects with the help of the X-ray and UT analysis.

  7. Urban shrinkage, local housing markets and the role of voluntary community organisations

    DEFF Research Database (Denmark)

    Larsen, Jacob Norvig

    Since the beginning of the crisis in 2007-08 urban shrinkage has hit a large number of Danish municipalities, towns and villages outside the two major metropolitan areas in the country .Abandoned homes, plunging property prices and out-migration are among the major symptoms. As a consequence of t...

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

    Science.gov (United States)

    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.

  9. Shrinkage Behaviour of Spheroidal Graphite Cast Iron in Green and Dry Sand Molds for the Benchmarking of Solidification Simulation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroidal graphite cast iron have been studied, considering the parameters of carbon equivalent, inoculation, casting modulus, mold type (green or dry) and pouring temperature within specific ranges of these variables. Based on the orthogonal experiments, the metallurgical and processing parameters of the minimum casting shrinkage and the maximum casting shrinkage were obtained, and the effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroidal graphite cast iron castings were discussed. Finally,two regression equations relating these variables to the formation of shrinkage porosity were derived based upon the orthogonal experiments conducted.

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

    Science.gov (United States)

    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.

  11. Taguchi design and flower pollination algorithm application to optimize the shrinkage of triaxial porcelain containing palm oil fuel ash

    Science.gov (United States)

    Zainudin, A.; Sia, C. K.; Ong, P.; Narong, O. L. C.; Nor, N. H. M.

    2017-01-01

    In the preparation of triaxial porcelain from Palm Oil Fuel Ash (POFA), a new parameter variable must be determined. The parameters involved are the particle size of POFA, percentage of POFA in triaxial porcelain composition, moulding pressure, sintering temperature and soaking time. Meanwhile, the shrinkage is the dependent variable. The optimization process was investigated using a hybrid Taguchi design and flower pollination algorithm (FPA). The interaction model of shrinkage was derived from regression analysis and found that the shrinkage is highly dependent on the sintering temperature followed by POFA composition, moulding pressure, POFA particle size and soaking time. The interaction between sintering temperature and soaking time highly affects the shrinkage. From the FPA process, targeted shrinkage approaching zero values were predicted for 142 μm particle sizes of POFA, 22.5 wt% of POFA, 3.4 tonne moulding pressure, 948.5 °C sintering temperature and 264 minutes soaking time.

  12. Assessment of murine brain tissue shrinkage caused by different histological fixatives using magnetic resonance and computed tomography imaging.

    Science.gov (United States)

    Wehrl, Hans F; Bezrukov, Ilja; Wiehr, Stefan; Lehnhoff, Mareike; Fuchs, Kerstin; Mannheim, Julia G; Quintanilla-Martinez, Leticia; Kohlhofer, Ursula; Kneilling, Manfred; Pichler, Bernd J; Sauter, Alexander W

    2015-05-01

    Especially for neuroscience and the development of new biomarkers, a direct correlation between in vivo imaging and histology is essential. However, this comparison is hampered by deformation and shrinkage of tissue samples caused by fixation, dehydration and paraffin embedding. We used magnetic resonance (MR) imaging and computed tomography (CT) imaging to analyze the degree of shrinkage on murine brains for various fixatives. After in vivo imaging using 7 T MRI, animals were sacrificed and the brains were dissected and immediately placed in different fixatives, respectively: zinc-based fixative, neutral buffered formalin (NBF), paraformaldehyde (PFA), Bouin-Holland fixative and paraformaldehyde-lysine-periodate (PLP). The degree of shrinkage based on mouse brain volumes, radiodensity in Hounsfield units (HU), as well as non-linear deformations were obtained. The highest degree of shrinkage was observed for PLP (68.1%, P brain shrinkage and only small deformations and is therefore recommended for in vivo ex vivo comparison studies.

  13. Chest physiotherapy in cystic fibrosis: short-term effects of autogenic drainage preceded by wet inhalation of saline versus autogenic drainage preceded by intrapulmonary percussive ventilation with saline.

    Science.gov (United States)

    Van Ginderdeuren, F; Verbanck, S; Van Cauwelaert, K; Vanlaethem, S; Schuermans, D; Vincken, W; Malfroot, A

    2008-01-01

    Chest physiotherapy has been used for many years to assist in the removal of abnormal viscid bronchial secretions in cystic fibrosis (CF) patients. This study compared the short-term effects of two physiotherapy regimens in patients with CF: autogenic drainage (AD) preceded by either saline inhalation ('saline(NEB) + AD') or by intrapulmonary percussive ventilation (IPV) with saline ('saline(IPV) + AD'). In a randomized crossover design, 20 clinically stable CF patients with similar pulmonary function at baseline received either 'saline(NEB) + AD' or 'saline(IPV) + AD' on 2 consecutive days. Transcutaneous oxygen saturation, heart rate, Borg dyspnea score and mucus wet weight were evaluated after 15 min of either saline(NEB) or saline(IPV), and after a subsequent 30 min of AD. There were no significant changes in oxygen saturation, heart rate or Borg score at any point of either physiotherapy intervention. There was no significant difference in sputum wet weight recovered with either saline(NEB) (2.2 +/- 1.8 g, mean +/- SD) or saline(IPV) (1.7 +/- 1.9 g) alone. Subsequent AD did produce significantly greater amounts of sputum wet weight (p < 0.0001 for both) than in the initial saline delivery period, yet the amount of wet weight was similar irrespective of whether AD was preceded by saline(NEB) (9.7 +/- 6.5 g) or saline(IPV) (11.6 +/- 7.3 g). Recovered sputum weight is similar whether AD is preceded by saline(NEB) or saline(IPV). The much greater amount of mucus obtained during the AD period than during the saline delivery period warrants further investigation. Copyright 2007 S. Karger AG, Basel.

  14. Characterizetion of Flexural Strength, Warpage and Shrinkage of Polypropylene-Nanoclay-Nanocomposites Blend with Gigantochloa Scortechinii.

    Science.gov (United States)

    Khamis, S. Z.; Othman, M. H.; Hasan, S.; Ibrahim, M. H. I.

    2017-08-01

    This paper presents the characterization of Flexural Strength, Warpage and Shrinkage of reinforcement gigantochloa scortechinii fibre. The content of fiber were fixed at 0 wt.%, 3 wt.% and 6 wt.% in uniform increased. The selected injection moulding processing conditions were packing pressure, melt temperature, screw speed and filling time. The quality factors that need to be improved upon the characterization were flexural strength, warpage and shrinkage. This research started by drying the Gigantochloa Scortechinii fibres at 120°C. After that, 3 wt.% of the fibres were mixed with 81 wt.% of polypropylene, 15 wt.% of polypropylene grafted maleic anhydride (compatibilizer) and 1 wt. % of nanoclay. Samples with 6 wt.% of fibers were also prepared for comparison purpose. The mixing process was performed by using Brabender Lab-Compounder KETSE 20/40 and the pallets were produced using used Brabender® pelletizer with diameters of 1 to 4 mm. The optimisation process was accomplished by adopting the Taguchi L9 orthogonal array method. According to the results, for 0 wt.% GS, the flexural strength is 30.0082 MPa, the warpage is 0.0030000 mm and the shrinkage is 0.0003830 mm at packing pressure 40%, melt temperature 165°C, filled time 2 seconds and screw speed 35%. For the result 3 wt.% GS, the flexural strength is 32.2477 MPa, the warpage is 0.006670 mm and the shrinkage is 0.0003830 mm at packing pressure is 35%, melt temperature 165°C, filled times is 1 seconds and screw speed is 30%. While for the 6 wt.% GS, the results of the flexural strength is 36.9084 MPa, the warpage is 0.0066700 mm and the shrinkage is 0.0003830 mm at packing pressure is 35%, melt temperature 165°C, filled time is 2 seconds and screw speed is 30%. The existence of Gigantochloa Scortechinii fibre was also proven to effect significantly towards flexural strength with 6% increasing value ordering from 0 wt.% GS to 6 wt.% GS. while, the warpage value increasing from 0.003000 mm to 0.00667 mm and

  15. Computed tomographic measurements of mesh shrinkage after laparoscopic ventral incisional hernia repair with an expanded polytetrafluoroethylene mesh.

    Science.gov (United States)

    Schoenmaeckers, Ernst J P; van der Valk, Steef B A; van den Hout, Huib W; Raymakers, Johan F T J; Rakic, Srdjan

    2009-07-01

    The potential for shrinkage of intraperitoneally implanted meshes for laparoscopic repair of ventral and incisional hernia (LRVIH) remains a concern. Numerous experimental studies on this issue reported very inconsistent results. Expanded polytetrafluoroethylene (ePTFE) mesh has the unique property of being revealed by computed tomography (CT). We therefore conducted an analysis of CT findings in patients who had previously undergone LRVIH with an ePTFE mesh (DualMesh, WL Gore, Flagstaff, AZ, USA) in order to evaluate the shrinkage of implanted meshes. Of 656 LRVIH patients with DualMesh, all patients who subsequently underwent CT scanning were identified and only those with precisely known transverse diameter of implanted mesh and with CT scans made more than 3 months postoperatively were selected (n = 40). Two radiologists who were blinded to the size of the implanted mesh measured in consensus the maximal transverse diameter of the meshes by using the AquariusNET program (TeraRecon Inc., San Mateo, CA, USA). Mesh shrinkage was defined as the relative loss of transverse diameter as compared with the original transverse diameter of the mesh. The mean time from LRVIH to CT scan was 17.9 months (range 3-59 months). The mean shrinkage of the mesh was 7.5% (range 0-23.7%). For 11 patients (28%) there was no shrinkage at all. Shrinkage of 1-10% was found in 16 patients (40%), of 10-20% in 10 patients (25%), and of 20-24% in 3 patients (7.5%). No correlation was found regarding the elapsed time between LRVIH and CT, and shrinkage. There were two recurrences, one possibly related to shrinkage. Our observations indicate that shrinkage of DualMesh is remarkably lower than has been reported in experimental studies (8-51%). This study is the first to address the problem of shrinkage after intraperitoneal implantation of synthetic mesh in a clinical material.

  16. Properties evaluation of silorane, low-shrinkage, non-flowable and flowable resin-based composites in dentistry.

    Science.gov (United States)

    Maia, Rodrigo R; Reis, Rodrigo S; Moro, André F V; Perez, Cesar R; Pessôa, Bárbara M; Dias, Katia R H C

    2015-01-01

    Purpose. This study tested the null hypothesis that different classes of direct restorative dental materials: silorane-based resin, low-shrinkage and conventional (non-flowable and flowable) resin-based composite (RBC) do not differ from each other with regard to polymerization shrinkage, depth of cure or microhardness. Methods. 140 RBC samples were fabricated and tested by one calibrated operator. Polymerization shrinkage was measured using a gas pycnometer both before and immediately after curing with 36 J/cm(2) light energy density. Depth of cure was determined, using a penetrometer and the Knoop microhardness was tested from the top surface to a depth of 5 mm. Results. Considering polymerization shrinkage, the authors found significant differences (p flowable RBCs showed lower values compared to flowable RBCs, with the silorane-based resin presenting the smallest shrinkage. The low shrinkage flowable composite performed similarly to non-flowable with significant statistical differences compared to the two other flowable RBCs. Regarding to depth of cure, low-shrinkage flowable RBC, were most effective compared to other groups. Microhardness was generally higher for the non-flowable vs. flowable RBCs (p flowable did not differ significantly from those of non-flowable, but were significantly higher than those of the other flowable RBCs. Clinical Significance. RBCs have undergone many modifications as they have evolved and represent the most relevant restorative materials in today's dental practice. This study of low-shrinkage RBCs, conventional RBCs (non-flowable and flowable) and silorane-based composite-by in vitro evaluation of volumetric shrinkage, depth of cure and microhardness-reveals that although filler content is an important determinant of polymerization shrinkage, it is not the only variable that affects properties of materials that were tested in this study.

  17. Measurement, growth types and shrinkage of newly formed aerosol particles at an urban research platform

    Science.gov (United States)

    Salma, Imre; Németh, Zoltán; Weidinger, Tamás; Kovács, Boldizsár; Kristóf, Gergely

    2016-06-01

    Budapest platform for Aerosol Research and Training (BpART) was created for advancing long-term on-line atmospheric measurements and intensive aerosol sample collection campaigns in Budapest. A joint study including atmospheric chemistry or physics, meteorology, and fluid dynamics on several-year-long data sets obtained at the platform confirmed that the location represents a well-mixed, average atmospheric environment for the city centre. The air streamlines indicated that the host and neighbouring buildings together with the natural orography play an important role in the near-field dispersion processes. Details and features of the airflow structure were derived, and they can be readily utilised for further interpretations. An experimental method to determine particle diffusion losses in the differential mobility particle sizer (DMPS) system of the BpART facility was proposed. It is based on CPC-CPC (condensation particle counter) and DMPS-CPC comparisons. Growth types of nucleated particles observed in 4 years of measurements were presented and discussed specifically for cities. Arch-shaped size distribution surface plots consisting of a growth phase followed by a shrinkage phase were characterised separately since they supply information on nucleated particles. They were observed in 4.5 % of quantifiable nucleation events. The shrinkage phase took 1 h 34 min in general, and the mean shrinkage rate with standard deviation was -3.8 ± 1.0 nm h-1. The shrinkage of particles was mostly linked to changes in local atmospheric conditions, especially in global radiation and the gas-phase H2SO4 concentration through its proxy, or to atmospheric mixing in few cases. Some indirect results indicate that variations in the formation and growth rates of nucleated particles during their atmospheric transport could be a driving force of shrinkage for particles of very small sizes and on specific occasions.

  18. Shrinkage of dental composite in simulated cavity measured with digital image correlation.

    Science.gov (United States)

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

    2014-07-21

    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.

  19. Computed tomography evaluation of autogenous graft in sinus lift surgery; Analise por tomografia computadorizada do enxerto autogeno na cirurgia de 'sinus lift'

    Energy Technology Data Exchange (ETDEWEB)

    Ajzen, Sergio Aron; Moscatiello, Rafael Andrade; Lima, Aida Maria Custodio de; Moscatiello, Vitoria Aparecida Muglia; Helio Kiitiro Yamashita [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Dept. de Diagnostico por Imagem; Mosacatiello, Rafael Muglia; Nishiguchi, Celso Itiro [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Disciplina de Tecnica Operatoria e Cirurgia Experimental; Alves, Maria Teresa de Seixas [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Disciplina de Anatomia Patologica

    2001-02-01

    The objective was to quantify bone formation within autogenous bone grafts and autogenous bone grafts in combination with platelet-rich plasma obtained either from apheresis or centrifugation using computed tomography. This prospective, double-blind study was conducted in 34 male and female adult patients (mean age of 28 years and 8 months), with either unilateral or bilateral pneumatization of the maxillary sinuses, requiring bone graft for dental implant. All patients were submitted to computed tomography examinations prior and six months after sinus lift surgery. Fifty-three maxillary sinuses were operated and divided into three distinct groups: autogenous bone graft, autogenous bone graft in combination with platelet-rich plasma obtained by centrifugation, and autogenous bone graft in combination with platelet-rich plasma obtained by apheresis. The results showed that computed tomography demonstrated bone growth in height and width between the initial and the follow-up computed tomography scans in all three groups. However, no statistical difference was found either for bone height or width. It was concluded that clinical evidence demonstrates the effectiveness of autogenous bone grafts, particularly when used in combination with bone growth factors such as platelet-rich plasma, which allow prosthetic and functional restoration of maxillofacial structures through fixation of dental implants. (author)

  20. The use of platelet-rich fibrin (PRF) and PRF-mixed particulated autogenous bone graft in the treatment of bone defects: An experimental and histomorphometrical study.

    Science.gov (United States)

    Kökdere, Nesligül Niyaz; Baykul, Timuçin; Findik, Yavuz

    2015-01-01

    Various materials and techniques have been developed to facilitate bone healing process and reduce its healing period. In recent studies, it is pointed out that, platelet-rich fibrin (PRF) which is derived autogenously from the own blood of the individuals, increase regeneration and accelerate the healing of the wound, due to the consisting various growing factors. The aim of the experimental study is to evaluate the efficiency of PRF and PRF/autogenous graft combination on bone healing in different time intervals. A total of 24 skeletally mature New Zealand rabbits were used. Animals were divided randomly into two groups. Two bone defects with a diameter 3, 3 mm were created on the right and left tibia in all group animals. Only particulate autogeneous bone graft, only PRF, combination of PRF and autogeneous bone graft and empty bone cavity, were performed to all animals. The animals in the first experimental group were sacrificed after 30 days. The animals in the second experimental group were sacrificed after 60 days from the operation. Histomorphometrical and statistical analysis was performed. The data were analyzed using Tukey test (P PRF used alone or used in conjuction with autogenous bone graft, PRF accelerated the healing of the bone defects. There were statistically significant differences in osteoblast, osteoblast and new bone area values in PRF alone and autogenous graft with PRF than the other groups. Our preliminary result demonstrated that PRF increase new bone formation and has a positive effect on early bone healing.