Tree Species Traits but Not Diversity Mitigate Stem Breakage in a Subtropical Forest following a Rare and Extreme Ice Storm

PubMed Central

Nadrowski, Karin; Pietsch, Katherina; Baruffol, Martin; Both, Sabine; Gutknecht, Jessica; Bruelheide, Helge; Heklau, Heike; Kahl, Anja; Kahl, Tiemo; Niklaus, Pascal; Kröber, Wenzel; Liu, Xiaojuan; Mi, Xiangcheng; Michalski, Stefan; von Oheimb, Goddert; Purschke, Oliver; Schmid, Bernhard; Fang, Teng; Welk, Erik; Wirth, Christian

2014-01-01

Future climates are likely to include extreme events, which in turn have great impacts on ecological systems. In this study, we investigated possible effects that could mitigate stem breakage caused by a rare and extreme ice storm in a Chinese subtropical forest across a gradient of forest diversity. We used Bayesian modeling to correct stem breakage for tree size and variance components analysis to quantify the influence of taxon, leaf and wood functional traits, and stand level properties on the probability of stem breakage. We show that the taxon explained four times more variance in individual stem breakage than did stand level properties; trees with higher specific leaf area (SLA) were less susceptible to breakage. However, a large part of the variation at the taxon scale remained unexplained, implying that unmeasured or undefined traits could be used to predict damage caused by ice storms. When aggregated at the plot level, functional diversity and wood density increased after the ice storm. We suggest that for the adaption of forest management to climate change, much can still be learned from looking at functional traits at the taxon level. PMID:24879434

A polymer, random walk model for the size-distribution of large DNA fragments after high linear energy transfer radiation

NASA Technical Reports Server (NTRS)

Ponomarev, A. L.; Brenner, D.; Hlatky, L. R.; Sachs, R. K.

2000-01-01

DNA double-strand breaks (DSBs) produced by densely ionizing radiation are not located randomly in the genome: recent data indicate DSB clustering along chromosomes. Stochastic DSB clustering at large scales, from > 100 Mbp down to < 0.01 Mbp, is modeled using computer simulations and analytic equations. A random-walk, coarse-grained polymer model for chromatin is combined with a simple track structure model in Monte Carlo software called DNAbreak and is applied to data on alpha-particle irradiation of V-79 cells. The chromatin model neglects molecular details but systematically incorporates an increase in average spatial separation between two DNA loci as the number of base-pairs between the loci increases. Fragment-size distributions obtained using DNAbreak match data on large fragments about as well as distributions previously obtained with a less mechanistic approach. Dose-response relations, linear at small doses of high linear energy transfer (LET) radiation, are obtained. They are found to be non-linear when the dose becomes so large that there is a significant probability of overlapping or close juxtaposition, along one chromosome, for different DSB clusters from different tracks. The non-linearity is more evident for large fragments than for small. The DNAbreak results furnish an example of the RLC (randomly located clusters) analytic formalism, which generalizes the broken-stick fragment-size distribution of the random-breakage model that is often applied to low-LET data.

Dependence of rates of breakage on fines content in wet ball mill grinding

NASA Astrophysics Data System (ADS)

Bhattacharyya, Anirban

The following research fundamentally deals with the cause and implications of nonlinearities in breakage rates of materials in wet grinding systems. The innate dependence of such nonlinearities on fines content and the milling environment during wet grinding operations is also tested and observed. Preferential breakage of coarser size fractions as compared to the finer size fractions in a particle population were observed and discussed. The classification action of the pulp was deemed to be the probable cause for such a peculiarity. Ores with varying degrees of hardness and brittleness were used for wet grinding experiments, primarily to test the variations in specific breakage rates as a function of varying hardness. For this research, limestone, quartzite, and gold ore were used. The degree of hardness is of the order of: limestone, quartzite, gold ore. Selection and breakage function parameters were determined in the course of this research. Functional forms of these expressions were used to compare experimentally derived parameter estimates. Force-fitting of parameters was not done in order to examine the realtime behavior of particle populations in wet grinding systems. Breakage functions were established as being invariant with respect to such operating variables like ball load, mill speed, particle load, and particle size distribution of the mill. It was also determined that specific selection functions were inherently dependent on the particle size distribution in wet grinding systems. Also, they were consistent with inputs of specific energy, according to grind time. Nonlinearity trends were observed for 1st order specific selection functions which illustrated variations in breakage rates with incremental inputs of grind time and specific energy. A mean particle size called the fulcrum was noted below which the nonlinearities in the breakage trends were observed. This magnitude of the fulcrum value varied with percent solids and slurry filling, indicating that breakage rates were being influenced by the milling environment as a whole. Primarily, there was always an increase in the breakage rates of coarser fractions with an increase in the amount of fines in the particle population. Consequently, the breakage rates of the finer size fractions were observed to decrease with an increase in grind time. Similar trends were noticed for 2nd order specific selection functions, where incremental inputs of specific energy were provided to observe realtime trends in the nonlinearity of breakage rates closely. Although the breakage rates for coarser size fractions increase with an increase in the amount of fines, the nature of nonlinearities varied with extended grind times. 1st order and 2nd order energy-specific breakage rates were observed to notice the variation in trends with extended grind times. Implications of such nonlinearities in specific breakage rates of various materials were tested on predictive simulation techniques, using the normalized linear population balance model and compared with an incremental methodology of specific energy input.

Evaluation of the efficacy of a nonlatex condom: results from a randomized, controlled clinical trial.

PubMed

Walsh, Terri L; Frezieres, Ron G; Peacock, Karen; Nelson, Anita L; Clark, Virginia A; Bernstein, Leslie

2003-01-01

To reduce unintended pregnancy and HIV infection, it is critical to develop reliable male condoms that will attract consumers who reject conventional latex condoms. In a prospective clinical trial conducted in 1998-2000, 830 monogamous couples were randomized in equal numbers to use either a nonlatex condom or a commercial natural latex condom for six months as their only method of birth control. Couples completed detailed reports for the first five condom uses and recorded intercourse and condom use in coital diaries. Pregnancy rates associated with typical and consistent condom use were calculated using life-table analysis. Rates of clinical failure (condom breakage or slippage) were determined for the first five condom uses. During the first five uses, the nonlatex condom had a higher frequency of breakage or slippage during intercourse or withdrawal (4.0%) than latex condoms (1.3%); the breakage rate for the nonlatex condom was about eight times that of latex condoms. The six-cycle typical-use pregnancy rate did not differ significantly between users of nonlatex (10.8%) and latex condoms (6.4%). The six-cycle consistent-use pregnancy rate was higher for nonlatex condom users than for latex condom users (4.9% vs. 1.0%). The data present strong indirect support for public health messages that promote the use of latex condoms and, for individuals who cannot or are unwilling to use latex condoms, the use of nonlatex condoms for prevention of pregnancy and disease.

An Integrative Breakage Model of genome architecture, reshuffling and evolution: The Integrative Breakage Model of genome evolution, a novel multidisciplinary hypothesis for the study of genome plasticity.

PubMed

Farré, Marta; Robinson, Terence J; Ruiz-Herrera, Aurora

2015-05-01

Our understanding of genomic reorganization, the mechanics of genomic transmission to offspring during germ line formation, and how these structural changes contribute to the speciation process, and genetic disease is far from complete. Earlier attempts to understand the mechanism(s) and constraints that govern genome remodeling suffered from being too narrowly focused, and failed to provide a unified and encompassing view of how genomes are organized and regulated inside cells. Here, we propose a new multidisciplinary Integrative Breakage Model for the study of genome evolution. The analysis of the high-level structural organization of genomes (nucleome), together with the functional constrains that accompany genome reshuffling, provide insights into the origin and plasticity of genome organization that may assist with the detection and isolation of therapeutic targets for the treatment of complex human disorders. © 2015 WILEY Periodicals, Inc.

Effect of Miracle Fruit (Synsepalum dulcificum) Seed Oil (MFSO®) on the Measurable Improvement of Hair Breakage in Women with Damaged Hair

PubMed Central

Zhang, Yu; Wakeford, Charles

2017-01-01

Background: Hair breakage is a common unrecognized form of hair loss in women most often the result of hair weathering and traumatic grooming practices. Lipids are major determinants of the physical properties of the hair. Synsepalum dulcificum seed oil (MFSO®; Miracle Fruit Oil Co., Miami Beach, Florida), is an exotic fruit oil with physicochemical properties suited to providing a superior ability to reduce hair breakage. Objective: To assess the safety and efficacy of a hair oil containing MFSO and its effects on hair breakage rates. Methods: Healthy, long-haired women (age range: 19–63 years, mean age: 36.7 years, standard deviation: 10.77 years) with excessive hair breakage were randomized in this double-blind, placebo-controlled study to receive MFSO (n=24), vehicle (n=17), or argan oil (n=16). Measurements of hair length, hair diameter, and Hair Mass Index were performed at baseline, Month 4, and Month 8. Hair Breakage Index and the Healthy Hair Index values were calculated from the trichometer measurements, and subject self-assessment questionnaires were conducted. The primary efficacy endpoints were the percent change in Healthy Hair Index 75 and Healthy Hair Index 50 measurements from baseline to the eighth month. Results: The Healthy Hair Index calculations, expressed as percent change from baseline to Month 4 and from baseline to Month 8, revealed that the MFSO® treatment group improved by 103.6 percent and 215.7 percent for the Healthy Hair Index 75 and 133.7 and 188.3 percent for the Healthy Hair Index 50 values, respectively. When compared with the vehicle and the argan oil brand groups, the Healthy Hair Index levels were significantly higher (p < 0.001) for the MFSO® treatment group, indicating a much greater ability to increase the levels of unbroken hairs by reducing hair breakage. With respect to the mean percent improvements from baseline to Month 4 and Month 8, the MFSO® hair oil treatment group was better than each of the other two treatment groups by at least 117.6 percent and 234.9 percent for the Healthy Hair Index 75 and 316.5 percent and 312 percent for the Healthy Hair Index 50 values, respectively, thereby achieving the primary efficacy objective. Subjects favored the MFSO® hair oil treatment, rating it as safe, effective, and aesthetically pleasing. Conclusions: The MFSO hair oil product is a safe and effective option for the treatment of women suffering from hair breakage and damaged hair. PMID:29399260

Impact of process parameters on the breakage kinetics of poorly water-soluble drugs during wet stirred media milling: a microhydrodynamic view.

PubMed

Afolabi, Afolawemi; Akinlabi, Olakemi; Bilgili, Ecevit

2014-01-23

Wet stirred media milling has proven to be a robust process for producing nanoparticle suspensions of poorly water-soluble drugs. As the process is expensive and energy-intensive, it is important to study the breakage kinetics, which determines the cycle time and production rate for a desired fineness. Although the impact of process parameters on the properties of final product suspensions has been investigated, scant information is available regarding their impact on the breakage kinetics. Here, we elucidate the impact of stirrer speed, bead concentration, and drug loading on the breakage kinetics via a microhydrodynamic model for the bead-bead collisions. Suspensions of griseofulvin, a model poorly water-soluble drug, were prepared in the presence of two stabilizers: hydroxypropyl cellulose and sodium dodecyl sulfate. Laser diffraction, scanning electron microscopy, and rheometry were used to characterize them. Various microhydrodynamic parameters including a newly defined milling intensity factor was calculated. An increase in either the stirrer speed or the bead concentration led to an increase in the specific energy and the milling intensity factor, consequently faster breakage. On the other hand, an increase in the drug loading led to a decrease in these parameters and consequently slower breakage. While all microhydrodynamic parameters provided significant physical insight, only the milling intensity factor was capable of explaining the influence of all parameters directly through its strong correlation with the process time constant. Besides guiding process optimization, the analysis rationalizes the preparation of a single high drug-loaded batch (20% or higher) instead of multiple dilute batches. Copyright © 2013 Elsevier B.V. All rights reserved.

Novel application of DEM to modelling comminution processes

NASA Astrophysics Data System (ADS)

Delaney, Gary W.; Cleary, Paul W.; Sinnott, Matt D.; Morrison, Rob D.

2010-06-01

Comminution processes in which grains are broken down into smaller and smaller sizes represent a critical component in many industries including mineral processing, cement production, food processing and pharmaceuticals. We present a novel DEM implementation capable of realistically modelling such comminution processes. This extends on a previous implementation of DEM particle breakage that utilized spherical particles. Our new extension uses super-quadric particles, where daughter fragments with realistic size and shape distributions are packed inside a bounding parent super-quadric. We demonstrate the flexibility of our approach in different particle breakage scenarios and examine the effect of the chosen minimum resolved particle size. This incorporation of the effect of particle shape in the breakage process allows for more realistic DEM simulations to be performed, that can provide additional fundamental insights into comminution processes and into the behaviour of individual pieces of industrial machinery.

Parametric Study on Responses of a Self-Anchored Suspension Bridge to Sudden Breakage of a Hanger

PubMed Central

Jiang, Meng; Huang, Cailiang

2014-01-01

The girder of self-anchored suspension bridge is subjected to large compression force applied by main cables. So, serious damage of the girder due to breakage of hangers may cause the collapse of the whole bridge. With the time increasing, the hangers may break suddenly for their resistance capacities decrease due to corrosion. Using nonlinear static and dynamic analysis methods and adopting 3D finite element model, the responses of an actual self-anchored suspension bridge to sudden breakage of hangers are studied in this paper. The results show that the sudden breakage of a hanger causes violent vibration and large changes in internal forces of the bridge. In the process of the vibration, the maximum tension of hanger produced by breakage of a hanger exceeds 2.22 times its initial value, and the reaction forces of the bearings increase by more than 1.86 times the tension of the broken hanger. Based on the actual bridge, the influences of some factors including flexural stiffness of girder, torsion stiffness of girder, flexural stiffness of main cable, weight of girder, weight of main cable, span to sag ratio of main cable, distance of hangers, span length, and breakage time of hanger on the dynamic responses are studied in detail, and the influencing extent of the factors is presented. PMID:25045734

Parametric study on responses of a self-anchored suspension bridge to sudden breakage of a hanger.

PubMed

Qiu, Wenliang; Jiang, Meng; Huang, Cailiang

2014-01-01

The girder of self-anchored suspension bridge is subjected to large compression force applied by main cables. So, serious damage of the girder due to breakage of hangers may cause the collapse of the whole bridge. With the time increasing, the hangers may break suddenly for their resistance capacities decrease due to corrosion. Using nonlinear static and dynamic analysis methods and adopting 3D finite element model, the responses of an actual self-anchored suspension bridge to sudden breakage of hangers are studied in this paper. The results show that the sudden breakage of a hanger causes violent vibration and large changes in internal forces of the bridge. In the process of the vibration, the maximum tension of hanger produced by breakage of a hanger exceeds 2.22 times its initial value, and the reaction forces of the bearings increase by more than 1.86 times the tension of the broken hanger. Based on the actual bridge, the influences of some factors including flexural stiffness of girder, torsion stiffness of girder, flexural stiffness of main cable, weight of girder, weight of main cable, span to sag ratio of main cable, distance of hangers, span length, and breakage time of hanger on the dynamic responses are studied in detail, and the influencing extent of the factors is presented.

Tree stability under wind: simulating uprooting with root breakage using a finite element method.

PubMed

Yang, Ming; Défossez, Pauline; Danjon, Frédéric; Fourcaud, Thierry

2014-09-01

Windstorms are the major natural hazard affecting European forests, causing tree damage and timber losses. Modelling tree anchorage mechanisms has progressed with advances in plant architectural modelling, but it is still limited in terms of estimation of anchorage strength. This paper aims to provide a new model for root anchorage, including the successive breakage of roots during uprooting. The model was based on the finite element method. The breakage of individual roots was taken into account using a failure law derived from previous work carried out on fibre metal laminates. Soil mechanical plasticity was considered using the Mohr-Coulomb failure criterion. The mechanical model for roots was implemented in the numerical code ABAQUS using beam elements embedded in a soil block meshed with 3-D solid elements. The model was tested by simulating tree-pulling experiments previously carried out on a tree of Pinus pinaster (maritime pine). Soil mechanical parameters were obtained from laboratory tests. Root system architecture was digitized and imported into ABAQUS while root material properties were estimated from the literature. Numerical simulations of tree-pulling tests exhibited realistic successive root breakages during uprooting, which could be seen in the resulting response curves. Broken roots could be visually located within the root system at any stage of the simulations. The model allowed estimation of anchorage strength in terms of the critical turning moment and accumulated energy, which were in good agreement with in situ measurements. This study provides the first model of tree anchorage strength for P. pinaster derived from the mechanical strength of individual roots. The generic nature of the model permits its further application to other tree species and soil conditions.

Tree stability under wind: simulating uprooting with root breakage using a finite element method

PubMed Central

Yang, Ming; Défossez, Pauline; Danjon, Frédéric; Fourcaud, Thierry

2014-01-01

Background and Aims Windstorms are the major natural hazard affecting European forests, causing tree damage and timber losses. Modelling tree anchorage mechanisms has progressed with advances in plant architectural modelling, but it is still limited in terms of estimation of anchorage strength. This paper aims to provide a new model for root anchorage, including the successive breakage of roots during uprooting. Methods The model was based on the finite element method. The breakage of individual roots was taken into account using a failure law derived from previous work carried out on fibre metal laminates. Soil mechanical plasticity was considered using the Mohr–Coulomb failure criterion. The mechanical model for roots was implemented in the numerical code ABAQUS using beam elements embedded in a soil block meshed with 3-D solid elements. The model was tested by simulating tree-pulling experiments previously carried out on a tree of Pinus pinaster (maritime pine). Soil mechanical parameters were obtained from laboratory tests. Root system architecture was digitized and imported into ABAQUS while root material properties were estimated from the literature. Key Results Numerical simulations of tree-pulling tests exhibited realistic successive root breakages during uprooting, which could be seen in the resulting response curves. Broken roots could be visually located within the root system at any stage of the simulations. The model allowed estimation of anchorage strength in terms of the critical turning moment and accumulated energy, which were in good agreement with in situ measurements. Conclusions This study provides the first model of tree anchorage strength for P. pinaster derived from the mechanical strength of individual roots. The generic nature of the model permits its further application to other tree species and soil conditions. PMID:25006178

Influence of the power law index on the fiber breakage during injection molding by numerical simulations

NASA Astrophysics Data System (ADS)

Desplentere, Frederik; Six, Wim; Bonte, Hilde; Debrabandere, Eric

2013-04-01

In predictive engineering for polymer processes, the proper prediction of material microstructure from known processing conditions and constituent material properties is a critical step forward properly predicting bulk properties in the finished composite. Operating within the context of long-fiber thermoplastics (LFT, length > 15mm) this investigation concentrates on the influence of the power law index on the final fiber length distribution within the injection molded part. To realize this, the Autodesk Simulation Moldflow Insight Scandium 2013 software has been used. In this software, a fiber breakage algorithm is available from this release on. Using virtual material data with realistic viscosity levels allows to separate the influence of the power law index on the fiber breakage from the other material and process parameters. Applying standard settings for the fiber breakage parameters results in an obvious influence on the fiber length distribution through the thickness of the part and also as function of position in the part. Finally, the influence of the shear rate constant within the fiber breakage model has been investigated illustrating the possibility to fit the virtual fiber length distribution to the possible experimentally available data.

Interrelating the breakage and composition of mined and drill core coal

NASA Astrophysics Data System (ADS)

Wilson, Terril Edward

Particle size distribution of coal is important if the coal is to be beneficiated, or if a coal sales contract includes particle size specifications. An exploration bore core sample of coal ought to be reduced from its original cylindrical form to a particle size distribution and particle composition that reflects, insofar as possible, a process stream of raw coal it represents. Often, coal cores are reduced with a laboratory crushing machine, the product of which does not match the raw coal size distribution. This study proceeds from work in coal bore core reduction by Australian investigators. In this study, as differentiated from the Australian work, drop-shatter impact breakage followed by dry batch tumbling in steel cylinder rotated about its transverse axis are employed to characterize the core material in terms of first-order and zeroth-order breakage rate constants, which are indices of the propensity of the coal to degrade during excavation and handling. Initial drop-shatter and dry tumbling calibrations were done with synthetic cores composed of controlled low-strength concrete incorporating fly ash (as a partial substitute for Portland cement) in order to reduce material variables and conserve difficult-to-obtain coal cores. Cores of three different coalbeds--Illinois No. 6, Upper Freeport, and Pocahontas No. 5 were subjected to drop-shatter and dry batch tumbling tests to determine breakage response. First-order breakage, characterized by a first-order breakage index for each coal, occurred in the drop-shatter tests. First- and zeroth-order breakage occurred in dry batch tumbling; disappearance of coarse particles and creation of fine particles occurred in a systematic way that could be represented mathematically. Certain of the coal cores available for testing were dry and friable. Comparison of coal preparation plant feed with a crushed bore core and a bore core prepared by drop-shatter and tumbling (all from the same Illinois No.6 coal mining property) indicated that the size distribution and size fraction composition of the drop-shattered/tumbled core more closely resembled the plant feed than the crushed core. An attempt to determine breakage parameters (to allow use of selection and breakage functions and population balance models in the description of bore core size reduction) was initiated. Rank determination of the three coal types was done, indicating that higher rank associates with higher breakage propensity. The two step procedure of drop-shatter and dry batch tumbling simulates the first-order (volume breakage) and zeroth-order (abrasion of particle surfaces) that occur in excavation and handling operations, and is appropriate for drill core reduction prior to laboratory analysis.

Characterization of re-grown floc size and structure: effect of mixing conditions during floc growth, breakage and re-growth process.

PubMed

Nan, Jun; Wang, Zhenbei; Yao, Meng; Yang, Yueming; Zhang, Xiaofei

2016-12-01

The impact of mixing speed in three stages-before breakage, during breakage, and after breakage-on re-grown floc properties was investigated by using a non-intrusive optical sampling and digital image analysis technique, respectively. And then, on the basis of different influence extent of mixing speed during each stage on size and structure of re-grown flocs, coagulation performance with varying mixing speed was analyzed. The results indicated that the broken flocs could not re-grow to the size before breakage in all cases. Furthermore, increasing mixing intensity contributed to the re-formation of smaller flocs with higher degree of compactness. For slow mixing before breakage, an increase in mixing speed had less influence on re-grown floc properties due to the same breakage strength during breakage, resulting in inconspicuous variation of coagulation efficiency. For rapid mixing during breakage, larger mixing speed markedly decreased the coagulation efficiency. This could be attributed that mixing speed during breakage generated greater influence on re-grown floc size. However, as slow mixing after breakage was elevated, the coagulation efficiency presented significant rise, indicating that slow mixing after breakage had more influence on re-grown floc structure upon re-structuring and re-arrangement mechanism.

Broken replication forks trigger heritable DNA breaks in the terminus of a circular chromosome

PubMed Central

Possoz, Christophe; Durand, Adeline; Desfontaines, Jean-Michel; Barre, François-Xavier; Leach, David R. F.

2018-01-01

It was recently reported that the recBC mutants of Escherichia coli, deficient for DNA double-strand break (DSB) repair, have a decreased copy number of their terminus region. We previously showed that this deficit resulted from DNA loss after post-replicative breakage of one of the two sister-chromosome termini at cell division. A viable cell and a dead cell devoid of terminus region were thus produced and, intriguingly, the reaction was transmitted to the following generations. Using genome marker frequency profiling and observation by microscopy of specific DNA loci within the terminus, we reveal here the origin of this phenomenon. We observed that terminus DNA loss was reduced in a recA mutant by the double-strand DNA degradation activity of RecBCD. The terminus-less cell produced at the first cell division was less prone to divide than the one produced at the next generation. DNA loss was not heritable if the chromosome was linearized in the terminus and occurred at chromosome termini that were unable to segregate after replication. We propose that in a recB mutant replication fork breakage results in the persistence of a linear DNA tail attached to a circular chromosome. Segregation of the linear and circular parts of this “σ-replicating chromosome” causes terminus DNA breakage during cell division. One daughter cell inherits a truncated linear chromosome and is not viable. The other inherits a circular chromosome attached to a linear tail ending in the chromosome terminus. Replication extends this tail, while degradation of its extremity results in terminus DNA loss. Repeated generation and segregation of new σ-replicating chromosomes explains the heritability of post-replicative breakage. Our results allow us to determine that in E. coli at each generation, 18% of cells are subject to replication fork breakage at dispersed, potentially random, chromosomal locations. PMID:29522563

Stochastic damage evolution in textile laminates

NASA Technical Reports Server (NTRS)

Dzenis, Yuris A.; Bogdanovich, Alexander E.; Pastore, Christopher M.

1993-01-01

A probabilistic model utilizing random material characteristics to predict damage evolution in textile laminates is presented. Model is based on a division of each ply into two sublaminas consisting of cells. The probability of cell failure is calculated using stochastic function theory and maximal strain failure criterion. Three modes of failure, i.e. fiber breakage, matrix failure in transverse direction, as well as matrix or interface shear cracking, are taken into account. Computed failure probabilities are utilized in reducing cell stiffness based on the mesovolume concept. A numerical algorithm is developed predicting the damage evolution and deformation history of textile laminates. Effect of scatter of fiber orientation on cell properties is discussed. Weave influence on damage accumulation is illustrated with the help of an example of a Kevlar/epoxy laminate.

Dilation and breakage dissipation of granular soils subjected to monotonic loading

NASA Astrophysics Data System (ADS)

Sun, Yifei; Xiao, Yang; Ji, Hua

2016-12-01

Dilation and breakage energy dissipation of four different granular soils are investigated by using an energy balance equation. Due to particle breakage, the dilation curve does not necessarily pass through the origin of coordinates. Breakage energy dissipation is found to increase significantly at the initial loading stage and then gradually become stabilised. The incremental dissipation ratio between breakage energy and plastic work exhibits almost independence of the confining pressure. Accordingly, a plastic flow rule considering the effect of particle breakage is suggested. The critical state friction angle is found to be a combination of the basic friction between particles and the friction contributed by particle breakage.

Multi-Species Genome Comparison Sheds New Light on Evolutionary Processes, Cancer Mutations

ERIC Educational Resources Information Center

Journal of College Science Teaching, 2005

2005-01-01

An international team that includes researchers from the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health (NIH), has discovered that mammalian chromosomes have evolved by breaking at specific sites rather than randomly as long thought--and that many of the breakage hot spots are also involved in human…

Thermal breakage of a discrete one-dimensional string.

PubMed

Lee, Chiu Fan

2009-09-01

We study the thermal breakage of a discrete one-dimensional string, with open and fixed ends, in the heavily damped regime. Basing our analysis on the multidimensional Kramers escape theory, we are able to make analytical predictions on the mean breakage rate and on the breakage propensity with respect to the breakage location on the string. We then support our predictions with numerical simulations.

A thermomechanical constitutive model for cemented granular materials with quantifiable internal variables. Part I-Theory

NASA Astrophysics Data System (ADS)

Tengattini, Alessandro; Das, Arghya; Nguyen, Giang D.; Viggiani, Gioacchino; Hall, Stephen A.; Einav, Itai

2014-10-01

This is the first of two papers introducing a novel thermomechanical continuum constitutive model for cemented granular materials. Here, we establish the theoretical foundations of the model, and highlight its novelties. At the limit of no cement, the model is fully consistent with the original Breakage Mechanics model. An essential ingredient of the model is the use of measurable and micro-mechanics based internal variables, describing the evolution of the dominant inelastic processes. This imposes a link between the macroscopic mechanical behavior and the statistically averaged evolution of the microstructure. As a consequence this model requires only a few physically identifiable parameters, including those of the original breakage model and new ones describing the cement: its volume fraction, its critical damage energy and bulk stiffness, and the cohesion.

Size and Location of Defects at the Coupling Interface Affect Lithotripter Performance

PubMed Central

Li, Guangyan; Williams, James C.; Pishchalnikov, Yuri A.; Liu, Ziyue; McAteer, James A.

2012-01-01

OBJECTIVE To determine how the size and location of coupling defects caught between the therapy head of a lithotripter and the skin of a surrogate patient (acoustic window of a test chamber) affect the features of shock waves responsible for stone breakage. METHODS Model defects were placed in the coupling gel between the therapy head of a Dornier Compact-S electromagnetic lithotripter and the Mylar window of a water-filled coupling test system. A fiber-optic hydrophone was used to measure acoustic pressures and map the lateral dimensions of the focal zone of the lithotripter. The effect of coupling conditions on stone breakage was assessed using Gypsum model stones. RESULTS Stone breakage decreased in proportion to the area of the coupling defect; a centrally located defect blocking only 18% of the transmission area reduced stone breakage by an average of almost 30%. The effect on stone breakage was greater for defects located on-axis and decreased as the defect was moved laterally; an 18% defect located near the periphery of the coupling window (2.0 cm off-axis) reduced stone breakage by only ~15% compared to when coupling was completely unobstructed. Defects centered within the coupling window acted to narrow the focal width of the lithotripter; an 8.2% defect reduced the focal width ~30% compared to no obstruction (4.4 mm versus 6.5 mm). Coupling defects located slightly off center disrupted the symmetry of the acoustic field; an 18% defect positioned 1.0 cm off-axis shifted the focus of maximum positive pressure ~1.0 mm laterally. Defects on and off-axis imposed a significant reduction in the energy density of shock waves across the focal zone. CONCLUSIONS In addition to blocking the transmission of shock wave energy, coupling defects also disrupt the properties of shock waves that play a role in stone breakage, including the focal width of the lithotripter and the symmetry of the acoustic field; the effect is dependent on the size and location of defects, with defects near the center of the coupling window having the greatest effect. These data emphasize the importance of eliminating air pockets from the coupling interface, particularly defects located near the center of the coupling window. PMID:22938566

Failure analysis of broken pedicle screws on spinal instrumentation.

PubMed

Chen, Chen-Sheng; Chen, Wen-Jer; Cheng, Cheng-Kung; Jao, Shyh-Hua Eric; Chueh, Shan-Chang; Wang, Chang-Chih

2005-07-01

Revised spinal surgery is needed when there is a broken pedicle screw in the patient. This study investigated the pedicle screw breakage by conducting retrieval analyses of broken pedicle screws from 16 patients clinically and by performing stress analyses in the posterolateral fusion computationally using finite element (FE) models. Fracture surface of screws was studied by scanning electron microscope (SEM). The FE model of the posterolateral fusion with the screw showed that screws on the caudal side had larger axial stress than those on the cephalic side, supporting the clinical findings that 75% of the patients had the screw breakage on the caudal side. SEM fractography showed that all broken screws exhibited beach marks or striations on the fractured surface, indicating fatigue failure. Screws of patients with spinal fracture showed fatigue striations and final ductile fracture around the edge. Among the 16 patients who had broken pedicle screws 69% of them achieved bone union in the bone graft, showing that bone union in the bone graft did not warrant the prevention of screw breakage.

Combinatorics of the Breakage-Fusion-Bridge Mechanism

PubMed Central

Bafna, Vineet

2012-01-01

Abstract The breakage-fusion-bridge (BFB) mechanism was proposed over seven decades ago and is a source of genomic variability and gene amplification in cancer. Here we formally model and analyze the BFB mechanism, to our knowledge the first time this has been undertaken. We show that BFB can be modeled as successive inverted prefix duplications of a string. Using this model, we show that BFB can achieve a surprisingly broad range of amplification patterns. We find that a sequence of BFB operations can be found that nearly fits most patterns of copy number increases along a chromosome. We conclude that this limits the usefulness of methods like array CGH for detecting BFB. PMID:22506505

Transient and asymptotic behaviour of the binary breakage problem

NASA Astrophysics Data System (ADS)

Mantzaris, Nikos V.

2005-06-01

The general binary breakage problem with power-law breakage functions and two families of symmetric and asymmetric breakage kernels is studied in this work. A useful transformation leads to an equation that predicts self-similar solutions in its asymptotic limit and offers explicit knowledge of the mean size and particle density at each point in dimensionless time. A novel moving boundary algorithm in the transformed coordinate system is developed, allowing the accurate prediction of the full transient behaviour of the system from the initial condition up to the point where self-similarity is achieved, and beyond if necessary. The numerical algorithm is very rapid and its results are in excellent agreement with known analytical solutions. In the case of the symmetric breakage kernels only unimodal, self-similar number density functions are obtained asymptotically for all parameter values and independent of the initial conditions, while in the case of asymmetric breakage kernels, bimodality appears for high degrees of asymmetry and sharp breakage functions. For symmetric and discrete breakage kernels, self-similarity is not achieved. The solution exhibits sustained oscillations with amplitude that depends on the initial condition and the sharpness of the breakage mechanism, while the period is always fixed and equal to ln 2 with respect to dimensionless time.

Extrapolation of the dna fragment-size distribution after high-dose irradiation to predict effects at low doses

NASA Technical Reports Server (NTRS)

Ponomarev, A. L.; Cucinotta, F. A.; Sachs, R. K.; Brenner, D. J.; Peterson, L. E.

2001-01-01

The patterns of DSBs induced in the genome are different for sparsely and densely ionizing radiations: In the former case, the patterns are well described by a random-breakage model; in the latter, a more sophisticated tool is needed. We used a Monte Carlo algorithm with a random-walk geometry of chromatin, and a track structure defined by the radial distribution of energy deposition from an incident ion, to fit the PFGE data for fragment-size distribution after high-dose irradiation. These fits determined the unknown parameters of the model, enabling the extrapolation of data for high-dose irradiation to the low doses that are relevant for NASA space radiation research. The randomly-located-clusters formalism was used to speed the simulations. It was shown that only one adjustable parameter, Q, the track efficiency parameter, was necessary to predict DNA fragment sizes for wide ranges of doses. This parameter was determined for a variety of radiations and LETs and was used to predict the DSB patterns at the HPRT locus of the human X chromosome after low-dose irradiation. It was found that high-LET radiation would be more likely than low-LET radiation to induce additional DSBs within the HPRT gene if this gene already contained one DSB.

A New Local Failure Model with Application to the Longitudinal Tensile Behavior of Continuously Reinforced Titanium Composites

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2000-01-01

A new model for local fiber failures in composite materials loaded longitudinally is presented. In developing the model, the goal was to account for the effects of fiber breakage on the global response of a composite in a relatively simple and efficient manner. Towards this end, the model includes the important feature of local stress unloading, even as global loading of the composite continues. The model has been incorporated into NASA Glenn's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) and was employed to simulate the longitudinal tensile deformation and failure behavior of several silicon carbide fiber/titanium matrix (SiC/Ti) composites. The model is shown to be quite realistic and capable of accurate predictions for various temperatures, fiber volume fractions, and fiber diameters. Further- more, the new model compares favorably to Curtin's (1993) effective fiber breakage model, which has also been incorporated into MAC/GMC.

Observation of quantum criticality with ultracold atoms in optical lattices

NASA Astrophysics Data System (ADS)

Zhang, Xibo

As biological problems are becoming more complex and data growing at a rate much faster than that of computer hardware, new and faster algorithms are required. This dissertation investigates computational problems arising in two of the fields: comparative genomics and epigenomics, and employs a variety of computational techniques to address the problems. One fundamental question in the studies of chromosome evolution is whether the rearrangement breakpoints are happening at random positions or along certain hotspots. We investigate the breakpoint reuse phenomenon, and show the analyses that support the more recently proposed fragile breakage model as opposed to the conventional random breakage models for chromosome evolution. The identification of syntenic regions between chromosomes forms the basis for studies of genome architectures, comparative genomics, and evolutionary genomics. The previous synteny block reconstruction algorithms could not be scaled to a large number of mammalian genomes being sequenced; neither did they address the issue of generating non-overlapping synteny blocks suitable for analyzing rearrangements and evolutionary history of large-scale duplications prevalent in plant genomes. We present a new unified synteny block generation algorithm based on A-Bruijn graph framework that overcomes these shortcomings. In the epigenome sequencing, a sample may contain a mixture of epigenomes and there is a need to resolve the distinct methylation patterns from the mixture. Many sequencing applications, such as haplotype inference for diploid or polyploid genomes, and metagenomic sequencing, share the similar objective: to infer a set of distinct assemblies from reads that are sequenced from a heterogeneous sample and subsequently aligned to a reference genome. We model the problem from both a combinatorial and a statistical angles. First, we describe a theoretical framework. A linear-time algorithm is then given to resolve a minimum number of assemblies that are consistent with all reads, substantially improving on previous algorithms. An efficient algorithm is also described to determine a set of assemblies that is consistent with a maximum subset of the reads, a previously untreated problem. We then prove that allowing nested reads or permitting mismatches between reads and their assemblies renders these problems NP-hard. Second, we describe a mixture model-based approach, and applied the model for the detection of allele-specific methylations.

Stress analysis in a pedicle screw fixation system with flexible rods in the lumbar spine.

PubMed

Kim, Kyungsoo; Park, Won Man; Kim, Yoon Hyuk; Lee, SuKyoung

2010-01-01

Breakage of screws has been one of the most common complications in spinal fixation systems. However, no studies have examined the breakage risk of pedicle screw fixation systems that use flexible rods, even though flexible rods are currently being used for dynamic stabilization. In this study, the risk of breakage of screws for the rods with various flexibilities in pedicle screw fixation systems is investigated by calculating the von Mises stress as a breakage risk factor using finite element analysis. Three-dimensional finite element models of the lumbar spine with posterior one-level spinal fixations at L4-L5 using four types of rod (a straight rod, a 4 mm spring rod, a 3 mm spring rod, and a 2 mm spring rod) were developed. The von Mises stresses in both the pedicle screws and the rods were analysed under flexion, extension, lateral bending, and torsion moments of 10 Nm with a follower load of 400 N. The maximum von Mises stress, which was concentrated on the neck region of the pedicle screw, decreased as the flexibility of the rod increased. However, the ratio of the maximum stress in the rod to the yield stress increased substantially when a highly flexible rod was used. Thus, the level of rod flexibility should be considered carefully when using flexible rods for dynamic stabilization because the intersegmental motion facilitated by the flexible rod results in rod breakage.

Applications for carbon fibre recovered from composites

NASA Astrophysics Data System (ADS)

Pickering; Liu, Z.; Turner, TA; Wong, KH

2016-07-01

Commercial operations to recover carbon fibre from waste composites are now developing and as more recovered fibre becomes available new applications for recovered fibre are required. Opportunities to use recovered carbon fibre as a structural reinforcement are considered involving the use of wet lay processes to produce nonwoven mats. Mats with random in-plane fibre orientation can readily be produced using existing commercial processes. However, the fibre volume fraction, and hence the mechanical properties that can be achieved, result in composites with limited mechanical properties. Fibre volume fractions of 40% can be achieved with high moulding pressures of over 100 bar, however, moulding at these pressures results in substantial fibre breakage which reduces the mean fibre length and the properties of the composite manufactured. Nonwoven mats made from aligned, short carbon fibres can achieve higher fibre volume fractions with lower fibre breakage even at high moulding pressure. A process for aligning short fibres is described and a composite of over 60% fibre volume fraction has been manufactured at a pressures up to 100 bar with low fibre breakage. Further developments of the alignment process have been undertaken and a composite of 46% fibre volume fraction has been produced moulded at a pressure of 7 bar in an autoclave, exhibiting good mechanical properties that compete with higher grade materials. This demonstrates the potential for high value applications for recovered carbon fibre by fibre alignment.

Hair breakage during combing. III. The effects of bleaching and conditioning on short and long segment breakage by wet and dry combing of tresses.

PubMed

Robbins, Clarence; Kamath, Yash

2007-01-01

A recent publication (1), provided evidence for two types of hair breakage during combing, short segment breakage (approximately less than 1.27 cm) and longer segment breakage. We have confirmed these results and refined the separation distance between short and long segment breakage at about 2.54 cm. Furthermore, chemical bleaching increased both short and long segment breakage while a commercial hair conditioner decreased both types of breakage. Whether the hair is chemically bleached or conditioned, for dry combing, short segment breakage increases with increasing comb strokes, that is, short segment breakage increases as combing damages the ends of the hair, however, long segment breakage does not increase with increasing comb strokes. Wet combing provided a decrease in short segment breakage and an increase in long segment breaks, but no increase in breakage with increasing comb strokes. Mechanical combing of tresses shows similar results qualitatively, however the variance was too large and adjustments need to be made to provide for a larger number of broken hairs to bring the mechanical and hand combing results in line. For dry combing, as the comb descends through the hair, hairs above it are made parallel and those beneath are either made parallel or knot by, hairs looping around other hairs or hairs looping around comb teeth and other hairs several cm between the comb and the hair tips. As the comb advances through the looped/knotted hairs long breaks occur or as the comb descends near the tips wrapped ends can result. End wrapping by inertia & possibly static charge produces short segment breaks which are more severe if the hair is cut at 90 degrees versus a tapered cut. For wet combing, clumping of hairs by a capillary action produces fewer short segment breaks, by reducing end wrapping: however, crossed hair interactions occur & because of higher friction more severe snags arise higher up in the tress, and lower hair breaking load due to plasticization by water, producing a larger number of long segment breaks. The very best practical way to evaluate hair strength is by counting the actual number of short and long segment breaks and by considering both wet and dry combing.

The risk of capsular breakage from phacoemulsification needle contact with the lens capsule: a laboratory study.

PubMed

Meyer, Jay J; Kuo, Annie F; Olson, Randall J

2010-06-01

To determine capsular breakage risk from contact by phacoemulsification needles by machine and tip type. Experimental laboratory investigation. Infiniti (Alcon, Inc.) with Intrepid cartridges and Signature (Abbott Medical Optics, Inc.) phacoemulsification machines were tested using 19- and 20-gauge sharp and rounded tips. Actual and unoccluded flow vacuum were determined at 550 mm Hg, bottle height of 75 cm, and machine-indicated flow rate of 60 mL/minute. Breakage from brief tip contact with a capsular surrogate and human cadaveric lenses was calculated. Nineteen-gauge tips had more flow and less unoccluded flow vacuum than 20-gauge tips for both machines, with highest unoccluded flow vacuum in the Infiniti. The 19-gauge sharp tip was more likely than the 20-gauge sharp tip to cause surrogate breakage for Signature with micropulse and Ellips (Abbott Medical Optics, Inc.) ultrasound at 100% power. For Infiniti using OZil (Alcon, Inc.) ultrasound, 20-gauge sharp tips were more likely than 19-gauge sharp tips to break the membrane. For cadaveric lenses, using rounded 20-gauge tips at 100% power, breakage rates were micropulse (2.3%), Ellips (2.3%), OZil (5.3%). Breakage rates for sharp 20-gauge Ellips tips were higher than for rounded tips. Factors influencing capsular breakage may include active vacuum at the tip, flow rate, needle gauge, and sharpness. Nineteen-gauge sharp tips were more likely than 20-gauge tips to cause breakage in lower vacuum methods. For higher-vacuum methods, breakage is more likely with 20-gauge than with 19-gauge tips. Rounded-edge tips are less likely than sharp-edged tips to cause breakage. Copyright 2010 Elsevier Inc. All rights reserved.

Replication stress-induced chromosome breakage is correlated with replication fork progression and is preceded by single-stranded DNA formation.

PubMed

Feng, Wenyi; Di Rienzi, Sara C; Raghuraman, M K; Brewer, Bonita J

2011-10-01

Chromosome breakage as a result of replication stress has been hypothesized to be the direct consequence of defective replication fork progression, or "collapsed" replication forks. However, direct and genome-wide evidence that collapsed replication forks give rise to chromosome breakage is still lacking. Previously we showed that a yeast replication checkpoint mutant mec1-1, after transient exposure to replication impediment imposed by hydroxyurea (HU), failed to complete DNA replication, accumulated single-stranded DNA (ssDNA) at the replication forks, and fragmented its chromosomes. In this study, by following replication fork progression genome-wide via ssDNA detection and by direct mapping of chromosome breakage after HU exposure, we have tested the hypothesis that the chromosome breakage in mec1 cells occurs at collapsed replication forks. We demonstrate that sites of chromosome breakage indeed correlate with replication fork locations. Moreover, ssDNA can be detected prior to chromosome breakage, suggesting that ssDNA accumulation is the common precursor to double strand breaks at collapsed replication forks.

Mechanical behaviors of multi-filament twist superconducting strand under tensile and cyclic loading

NASA Astrophysics Data System (ADS)

Wang, Xu; Li, Yingxu; Gao, Yuanwen

2016-01-01

The superconducting strand, serving as the basic unit cell of the cable-in-conduit-conductors (CICCs), is a typical multi-filament twist composite which is always subjected to a cyclic loading under the operating condition. Meanwhile, the superconducting material Nb3Sn in the strand is sensitive to strain frequently relating to the performance degradation of the superconductivity. Therefore, a comprehensive study on the mechanical behavior of the strand helps understanding the superconducting performance of the strained Nb3Sn strands. To address this issue, taking the LMI (internal tin) strand as an example, a three-dimensional structural finite element model, named as the Multi-filament twist model, of the strand with the real configuration of the LMI strand is built to study the influences of the plasticity of the component materials, the twist of the filament bundle, the initial thermal residual stress and the breakage and its evolution of the filaments on the mechanical behaviors of the strand. The effective properties of superconducting filament bundle with random filament breakage and its evolution versus strain are obtained based on the damage theory of fiber-reinforced composite materials proposed by Curtin and Zhou. From the calculation results of this model, we find that the occurrence of the hysteresis loop in the cyclic loading curve is determined by the reverse yielding of the elastic-plastic materials in the strand. Both the initial thermal residual stress in the strand and the pitch length of the filaments have significant impacts on the axial and hysteretic behaviors of the strand. The damage of the filaments also affects the axial mechanical behavior of the strand remarkably at large axial strain. The critical current of the strand is calculated by the scaling law with the results of the Multi-filament twist model. The predicted results of the Multi-filament twist model show an acceptable agreement with the experiment.

Rheology of attractive emulsions

NASA Astrophysics Data System (ADS)

Datta, Sujit S.; Gerrard, Dustin D.; Rhodes, Travers S.; Mason, Thomas G.; Weitz, David A.

2011-10-01

We show how attractive interactions dramatically influence emulsion rheology. Unlike the repulsive case, attractive emulsions below random close packing, φRCP, can form soft gel-like elastic solids. However, above φRCP, attractive and repulsive emulsions have similar elasticities. Such compressed attractive emulsions undergo an additional shear-driven relaxation process during yielding. Our results suggest that attractive emulsions begin to yield at weak points through the breakage of bonds, and, above φRCP, also undergo droplet configurational rearrangements.

Rheology of attractive emulsions.

PubMed

Datta, Sujit S; Gerrard, Dustin D; Rhodes, Travers S; Mason, Thomas G; Weitz, David A

2011-10-01

We show how attractive interactions dramatically influence emulsion rheology. Unlike the repulsive case, attractive emulsions below random close packing, φ(RCP), can form soft gel-like elastic solids. However, above φ(RCP), attractive and repulsive emulsions have similar elasticities. Such compressed attractive emulsions undergo an additional shear-driven relaxation process during yielding. Our results suggest that attractive emulsions begin to yield at weak points through the breakage of bonds, and, above φ(RCP), also undergo droplet configurational rearrangements.

A Framework for Performing Multiscale Stochastic Progressive Failure Analysis of Composite Structures

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2006-01-01

A framework is presented that enables coupled multiscale analysis of composite structures. The recently developed, free, Finite Element Analysis - Micromechanics Analysis Code (FEAMAC) software couples the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with ABAQUS to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. As a result, the stochastic nature of fiber breakage in composites can be simulated through incorporation of an appropriate damage and failure model that operates within MAC/GMC on the level of the fiber. Results are presented for the progressive failure analysis of a titanium matrix composite tensile specimen that illustrate the power and utility of the framework and address the techniques needed to model the statistical nature of the problem properly. In particular, it is shown that incorporating fiber strength randomness on multiple scales improves the quality of the simulation by enabling failure at locations other than those associated with structural level stress risers.

A Framework for Performing Multiscale Stochastic Progressive Failure Analysis of Composite Structures

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2007-01-01

A framework is presented that enables coupled multiscale analysis of composite structures. The recently developed, free, Finite Element Analysis-Micromechanics Analysis Code (FEAMAC) software couples the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with ABAQUS to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. As a result, the stochastic nature of fiber breakage in composites can be simulated through incorporation of an appropriate damage and failure model that operates within MAC/GMC on the level of the fiber. Results are presented for the progressive failure analysis of a titanium matrix composite tensile specimen that illustrate the power and utility of the framework and address the techniques needed to model the statistical nature of the problem properly. In particular, it is shown that incorporating fiber strength randomness on multiple scales improves the quality of the simulation by enabling failure at locations other than those associated with structural level stress risers.

Lack of spontaneous and radiation-induced chromosome breakage at interstitial telomeric sites in murine scid cells.

PubMed

Wong, H-P; Mozdarani, H; Finnegan, C; McIlrath, J; Bryant, P E; Slijepcevic, P

2004-01-01

Interstitial telomeric sites (ITSs) in chromosomes from DNA repair-proficient mammalian cells are sensitive to both spontaneous and radiation-induced chromosome breakage. Exact mechanisms of this chromosome breakage sensitivity are not known. To investigate factors that predispose ITSs to chromosome breakage we used murine scid cells. These cells lack functional DNA-PKcs, an enzyme involved in the repair of DNA double-strand breaks. Interestingly, our results revealed lack of both spontaneous and radiation-induced chromosome breakage at ITSs found in scid chromosomes. Therefore, it is possible that increased sensitivity of ITSs to chromosome breakage is associated with the functional DNA double-strand break repair machinery. To investigate if this is the case we used scid cells in which DNA-PKcs deficiency was corrected. Our results revealed complete disappearance of ITSs in scid cells with functional DNA-PKcs, presumably through chromosome breakage at ITSs, but their unchanged frequency in positive and negative control cells. Therefore, our results indicate that the functional DNA double-strand break machinery is required for elevated sensitivity of ITSs to chromosome breakage. Interestingly, we observed significant differences in mitotic chromosome condensation between scid cells and their counterparts with restored DNA-PKcs activity suggesting that lack of functional DNA-PKcs may cause a defect in chromatin organization. Increased condensation of mitotic chromosomes in the scid background was also confirmed in vivo. Therefore, our results indicate a previously unanticipated role of DNA-PKcs in chromatin organisation, which could contribute to the lack of ITS sensitivity to chromosome breakage in murine scid cells. Copyright 2003 S. Karger AG, Basel

Genetic variation for susceptibility to storm-induced stem breakage in Solidago altissima: The role of stem height and morphology

NASA Astrophysics Data System (ADS)

Wise, Michael J.; Abrahamson, Warren G.

2010-07-01

While storms can have obvious ecological impacts on plants, plants' potential to respond evolutionarily to selection for increased resistance to storm damage has received little study. We took advantage of a thunderstorm with strong wind and hail to examine genetic variation for resistance to stem breakage in the herbaceous perennial Solidago altissima. The storm broke the apex of nearly 10% of 1883 marked ramets in a common-garden plot containing 26 genets of S. altissima. Plant genets varied 20-fold in resistance to breakage. Stem height was strongly correlated with resistance to breakage, with taller stems being significantly more susceptible. A stem's growth form (erect versus nodding) had no detectable effect on its resistance to breakage. Therefore, we rejected the hypothesis that a function of the nodding, or "candy-cane," morphology is protection of the apex from storm damage. The significant genetic variation in S. altissima for stem breakage suggests that this plant has the capacity to respond to selection imposed by storms - particularly through changes in mean stem height. Tradeoffs between breakage resistance and competition for light and pollinators may act to maintain a large amount of genetic variation in stem height.

Size and location of defects at the coupling interface affect lithotripter performance.

PubMed

Li, Guangyan; Williams, James C; Pishchalnikov, Yuri A; Liu, Ziyue; McAteer, James A

2012-12-01

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? In shock wave lithotripsy air pockets tend to get caught between the therapy head of the lithotripter and the skin of the patient. Defects at the coupling interface hinder the transmission of shock wave energy into the body, reducing the effectiveness of treatment. This in vitro study shows that ineffective coupling not only blocks the transmission of acoustic pulses but also alters the properties of shock waves involved in the mechanisms of stone breakage, with the effect dependent on the size and location of defects at the coupling interface. • To determine how the size and location of coupling defects caught between the therapy head of a lithotripter and the skin of a surrogate patient (i.e. the acoustic window of a test chamber) affect the features of shock waves responsible for stone breakage. • Model defects were placed in the coupling gel between the therapy head of a Dornier Compact-S electromagnetic lithotripter (Dornier MedTech, Kennesaw, GA, USA) and the Mylar (biaxially oriented polyethylene terephthalate) (DuPont Teijin Films, Chester, VA, USA) window of a water-filled coupling test system. • A fibre-optic probe hydrophone was used to measure acoustic pressures and map the lateral dimensions of the focal zone of the lithotripter. • The effect of coupling conditions on stone breakage was assessed using gypsum model stones. • Stone breakage decreased in proportion to the area of the coupling defect; a centrally located defect blocking only 18% of the transmission area reduced stone breakage by an average of almost 30%. • The effect on stone breakage was greater for defects located on-axis and decreased as the defect was moved laterally; an 18% defect located near the periphery of the coupling window (2.0 cm off-axis) reduced stone breakage by only ~15% compared to when coupling was completely unobstructed. • Defects centred within the coupling window acted to narrow the focal width of the lithotripter; an 8.2% defect reduced the focal width ~30% compared to no obstruction (4.4 mm vs 6.5 mm). • Coupling defects located slightly off centre disrupted the symmetry of the acoustic field; an 18% defect positioned 1.0 cm off-axis shifted the focus of maximum positive pressure ~1.0 mm laterally. • Defects on and off-axis imposed a significant reduction in the energy density of shock waves across the focal zone. • In addition to blocking the transmission of shock-wave energy, coupling defects also disrupt the properties of shock waves that play a role in stone breakage, including the focal width of the lithotripter and the symmetry of the acoustic field • The effect is dependent on the size and location of defects, with defects near the centre of the coupling window having the greatest effect. • These data emphasize the importance of eliminating air pockets from the coupling interface, particularly defects located near the centre of the coupling window. © 2012 BJU INTERNATIONAL.

5 CFR 1605.2 - Calculating, posting, and charging breakage.

Code of Federal Regulations, 2010 CFR

2010-01-01

... will calculate breakage on late contributions, makeup agency contributions, and loan payments as... is the breakage. (c) Posting contributions and loan payments. Makeup and late contributions, late... participant's account is greater than the dollar amount of the makeup or late contribution or late loan...

Correlates of condom breakage and slippage among university undergraduates.

PubMed

Yarber, William L; Graham, Cynthia A; Sanders, Stephanie A; Crosby, Richard A

2004-07-01

An anonymous questionnaire was used to explore relationships between condom breakage, slippage and possible correlates in a sample of 428 single, never married college men and women. Specific condom use errors and problems that could lead to breakage and slippage were also examined. A three-month recall period was used. Breakage/slippage was found to be associated with never receiving instruction on correct condom use (P = 0.001), more than one sex partner (P = 0.001), more frequent use of condoms (P = 0.001), and partner(s) being less than highly motivated to use condoms (P = 0.02). Those reporting that condoms had contacted a sharp object were three times as likely to report breakage (P = 0.001). Those using condoms without proper lubrication (P = 0.006) and those experiencing loss of erection during sex (P = 0.001) were more likely to report slippage. Further research should investigate the efficacy of instruction addressing specific factors that may reduce the incidence of breakage/slippage, thereby enhancing condom effectiveness.

Determinants of condom breakage among female sex workers in Karnataka, India.

PubMed

Bradley, Janet; Rajaram, S; Alary, Michel; Isac, Shajy; Washington, Reynold; Moses, Stephen; Ramesh, B M

2011-12-29

Condoms are effective in preventing the transmission of HIV and other sexually transmitted infections, when properly used. However, recent data from surveys of female sex workers (FSWs) in Karnataka in south India, suggest that condom breakage rates may be quite high. It is important therefore to quantify condom breakage rates, and examine what factors might precipitate condom breakage, so that programmers can identify those at risk, and develop appropriate interventions. We explored determinants of reported condom breakage in the previous month among 1,928 female sex workers in four districts of Karnataka using data from cross-sectional surveys undertaken from July 2008 to February 2009. Using stepwise multivariate logistic regression, we examined the possible determinants of condom breakage, controlling for several independent variables including the district and client load. Overall, 11.4% of FSWs reported at least one condom break in the previous month. FSWs were much more likely to report breakage if under 20 years of age (AOR 3.43, p = 0.005); if divorced/ separated/widowed (AOR 1.52, p = 0.012); if they were regular alcohol users (AOR 1.63, p = 0.005); if they mostly entertained clients in lodges/rented rooms (AOR 2.99, p = 0.029) or brothels (AOR 4.77, p = 0.003), compared to street based sex workers; if they had ever had anal sex (AOR 2.03, p = 0.006); if the sex worker herself (as opposed to the client) applied the condom at last use (AOR 1.90, p < 0.001); if they were inconsistent condom users (AOR 2.77, p < 0.001); and if they had never seen a condom demonstration (AOR 2.37, p < 0.001). The reported incidence of condom breakage was high in this study, and this is a major concern for HIV/STI prevention programs, for which condom use is a key prevention tool. Younger and more marginalized female sex workers were most vulnerable to condom breakage. Special effort is therefore required to seek out such women and to provide information and skills on correct condom use. More research is also needed on what specific situational parameters might be important in predisposing women to condom breakage.

Processing-microstructure models for short- and long-fiber thermoplastic composites

NASA Astrophysics Data System (ADS)

Phelps, Jay H.

The research for this thesis has explored the important microstructural variables for injection-molded thermoplastic composites with discontinuous fiber reinforcement. Two variables, the distributions of fiber orientation and fiber length after processing, have proven to be not only important for correct material property prediction but also difficult to predict using currently available modeling and simulation techniques. In this work, we develop new models for the prediction of these two microstructural variables. Previously, the Folgar-Tucker model has been widely used to predict fiber orientation in injection molded SFT composites. This model accounts for the effects of both hydrodynamics and fiber-fiber interactions in order to give a prediction for a tensorial measure of fiber orientation. However, when applied to at least some classes of LFTs, this model does not match all components of experimental fiber orientation tensor data. In order to address this shortcoming of the model, we hypothesize that Folgar and Tucker's phenomenological treatment of the effects of fiber-fiber interactions with an isotropic rotary diffusion contribution to the rate of change of orientation is insufficient for materials with longer fibers. Instead, this work develops a fiber orientation model that incorporates anisotropic rotary diffusion (ARD). From kinetic theory we derive a general family of evolution equations for the second-order orientation tensor, correcting errors in earlier treatments, and identify a specific equation that is useful for predicting orientation in LFTs. The amount of diffusivity in this model used to approximate the effect of fiber-fiber interactions in each direction is assumed to depend on a second-order space tensor, which is taken to be a function of the orientation state and the rate of deformation. Also, concentrated fiber suspensions align more slowly with respect to strain than the Folgar-Tucker model predicts. Here, we borrow the technique of Wang et al. (2008) to incorporate this behavior in an objective fashion in this new model. Model parameters are selected by matching the experimental steady-state orientation in simple shear flow, and by requiring stable steady states and physically realizable solutions. Utilizing two separate techniques, we identify model parameters for three different materials. We then show that once a set of parameters that meets all previously established criteria has been identified, the differences in model behavior are negligible within that set of parameters. The final model with the proper parameter set is suitable for use in mold filling and other flow simulations, and does give improved predictions of fiber orientation for injection molded LFTs. Although significant fiber length degradation in LFTs has been observed both in literature and in this work, there are no quantitative fiber breakage models to predict either fiber length distributions or average fiber length measures. This work reviews the suspected causes of fiber breakage during the processing of discontinuously-reinforced thermoplastics, specifically LFTs, and introduces a phenomenological fiber breakage model based on the buckling force in a hydrodynamically loaded fiber. This breakage model is incorporated into a conservation equation for total fiber length, and a phenomenological model for the evolution of the fiber length distribution is developed. From this model, we also develop separate, approximate models for the evolution of both the number-average and weight-average fiber length measures. By applying these models to both a simple numerical example and a more complex mold-filling simulation, a qualitative agreement between experiment and prediction is observed. Although these results are promising, the breakage models have only been applied to the mold cavity in injection molding simulation. Both a literature review and our experimental data strongly suggest that the majority of fiber length degradation occurs in the earlier stages of injection molding, in the screw nozzle, runners, and gate. A better understanding of the melting and flow conditions upstream of the mold cavity, the simulation of which is beyond the scope of this work, is needed before these breakage models can be properly applied to the entire injection molding process. (Abstract shortened by UMI.)

GUI to Facilitate Research on Biological Damage from Radiation

NASA Technical Reports Server (NTRS)

Cucinotta, Frances A.; Ponomarev, Artem Lvovich

2010-01-01

A graphical-user-interface (GUI) computer program has been developed to facilitate research on the damage caused by highly energetic particles and photons impinging on living organisms. The program brings together, into one computational workspace, computer codes that have been developed over the years, plus codes that will be developed during the foreseeable future, to address diverse aspects of radiation damage. These include codes that implement radiation-track models, codes for biophysical models of breakage of deoxyribonucleic acid (DNA) by radiation, pattern-recognition programs for extracting quantitative information from biological assays, and image-processing programs that aid visualization of DNA breaks. The radiation-track models are based on transport models of interactions of radiation with matter and solution of the Boltzmann transport equation by use of both theoretical and numerical models. The biophysical models of breakage of DNA by radiation include biopolymer coarse-grained and atomistic models of DNA, stochastic- process models of deposition of energy, and Markov-based probabilistic models of placement of double-strand breaks in DNA. The program is designed for use in the NT, 95, 98, 2000, ME, and XP variants of the Windows operating system.

A New Hybrid Scheme for Preventing Channel Interference and Collision in Mobile Networks

NASA Astrophysics Data System (ADS)

Kim, Kyungjun; Han, Kijun

This paper proposes a new hybrid scheme based on a given set of channels for preventing channel interference and collision in mobile networks. The proposed scheme is designed for improving system performance, focusing on enhancement of performance related to path breakage and channel interference. The objective of this scheme is to improve the performance of inter-node communication. Simulation results from this paper show that the new hybrid scheme can reduce a more control message overhead than a conventional random scheme.

Perspectives on condom breakage: a qualitative study of female sex workers in Bangalore, India.

PubMed

Gurav, Kaveri; Bradley, Janet; Chandrashekhar Gowda, G; Alary, Michel

2014-01-01

A qualitative study was conducted to obtain a detailed understanding of two key determinants of condom breakage - 'rough sex' and poor condom fit - identified in a recent telephone survey of female sex workers, in Bangalore, India. Transcripts from six focus-group discussions involving 35 female sex workers who reported condom breakage during the telephone survey were analysed. Rough sex in different forms, from over-exuberance to violence, was often described by sex workers as a result of clients' inebriation and use of sexual stimulants, which, they report, cause tumescence, excessive thrusting and sex that lasts longer than usual, thereby increasing the risk of condom breakage. Condom breakage in this setting is the result of a complex set of social situations involving client behaviours and power dynamics that has the potential to put the health and personal lives of sex workers at risk. These findings and their implications for programme development are discussed.

Using DNA origami nanostructures to determine absolute cross sections for UV photon-induced DNA strand breakage.

PubMed

Vogel, Stefanie; Rackwitz, Jenny; Schürman, Robin; Prinz, Julia; Milosavljević, Aleksandar R; Réfrégiers, Matthieu; Giuliani, Alexandre; Bald, Ilko

2015-11-19

We have characterized ultraviolet (UV) photon-induced DNA strand break processes by determination of absolute cross sections for photoabsorption and for sequence-specific DNA single strand breakage induced by photons in an energy range from 6.50 to 8.94 eV. These represent the lowest-energy photons able to induce DNA strand breaks. Oligonucleotide targets are immobilized on a UV transparent substrate in controlled quantities through attachment to DNA origami templates. Photon-induced dissociation of single DNA strands is visualized and quantified using atomic force microscopy. The obtained quantum yields for strand breakage vary between 0.06 and 0.5, indicating highly efficient DNA strand breakage by UV photons, which is clearly dependent on the photon energy. Above the ionization threshold strand breakage becomes clearly the dominant form of DNA radiation damage, which is then also dependent on the nucleotide sequence.

Detection of maize kernels breakage rate based on K-means clustering

NASA Astrophysics Data System (ADS)

Yang, Liang; Wang, Zhuo; Gao, Lei; Bai, Xiaoping

2017-04-01

In order to optimize the recognition accuracy of maize kernels breakage detection and improve the detection efficiency of maize kernels breakage, this paper using computer vision technology and detecting of the maize kernels breakage based on K-means clustering algorithm. First, the collected RGB images are converted into Lab images, then the original images clarity evaluation are evaluated by the energy function of Sobel 8 gradient. Finally, the detection of maize kernels breakage using different pixel acquisition equipments and different shooting angles. In this paper, the broken maize kernels are identified by the color difference between integrity kernels and broken kernels. The original images clarity evaluation and different shooting angles are taken to verify that the clarity and shooting angles of the images have a direct influence on the feature extraction. The results show that K-means clustering algorithm can distinguish the broken maize kernels effectively.

Determinants of condom breakage among female sex workers in Karnataka, India

PubMed Central

2011-01-01

Background Condoms are effective in preventing the transmission of HIV and other sexually transmitted infections, when properly used. However, recent data from surveys of female sex workers (FSWs) in Karnataka in south India, suggest that condom breakage rates may be quite high. It is important therefore to quantify condom breakage rates, and examine what factors might precipitate condom breakage, so that programmers can identify those at risk, and develop appropriate interventions. Methods We explored determinants of reported condom breakage in the previous month among 1,928 female sex workers in four districts of Karnataka using data from cross-sectional surveys undertaken from July 2008 to February 2009. Using stepwise multivariate logistic regression, we examined the possible determinants of condom breakage, controlling for several independent variables including the district and client load. Results Overall, 11.4% of FSWs reported at least one condom break in the previous month. FSWs were much more likely to report breakage if under 20 years of age (AOR 3.43, p = 0.005); if divorced/ separated/widowed (AOR 1.52, p = 0.012); if they were regular alcohol users (AOR 1.63, p = 0.005); if they mostly entertained clients in lodges/rented rooms (AOR 2.99, p = 0.029) or brothels (AOR 4.77, p = 0.003), compared to street based sex workers; if they had ever had anal sex (AOR 2.03, p = 0.006); if the sex worker herself (as opposed to the client) applied the condom at last use (AOR 1.90, p < 0.001); if they were inconsistent condom users (AOR 2.77, p < 0.001); and if they had never seen a condom demonstration (AOR 2.37, p < 0.001). Conclusions The reported incidence of condom breakage was high in this study, and this is a major concern for HIV/STI prevention programs, for which condom use is a key prevention tool. Younger and more marginalized female sex workers were most vulnerable to condom breakage. Special effort is therefore required to seek out such women and to provide information and skills on correct condom use. More research is also needed on what specific situational parameters might be important in predisposing women to condom breakage. PMID:22376237

Wear and breakage monitoring of cutting tools by an optical method: theory

NASA Astrophysics Data System (ADS)

Li, Jianfeng; Zhang, Yongqing; Chen, Fangrong; Tian, Zhiren; Wang, Yao

1996-10-01

An essential part of a machining system in the unmanned flexible manufacturing system, is the ability to automatically change out tools that are worn or damaged. An optoelectronic method for in situ monitoring of the flank wear and breakage of cutting tools is presented. A flank wear estimation system is implemented in a laboratory environment, and its performance is evaluated through turning experiments. The flank wear model parameters that need to be known a priori are determined through several preliminary experiments, or from data available in the literature. The resulting cutting conditions are typical of those used in finishing cutting operations. Through time and amplitude domain analysis of the cutting tool wear states and breakage states, it is found that the original signal digital specificity (sigma) 2x and the self correlation coefficient (rho) (m) can reflect the change regularity of the cutting tool wear and break are determined, but which is not enough due to the complexity of the wear and break procedure of cutting tools. Time series analysis and frequency spectrum analysis will be carried out, which will be described in the later papers.

Sacrificial bonds and hidden length in biomaterials -- a kinetic description of strength and toughness in bone

NASA Astrophysics Data System (ADS)

Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.

2013-03-01

Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features, by providing a molecular-scale mechanism of energy dissipation. One example of occurrence of sacrificial bonds and hidden length is in the polymeric glue connection between collagen fibrils in animal bone. In this talk, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the revelation of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation, at the mean-field level, allowing for the number of bonds and hidden lengths to take up non-integer values between successive, discrete bond-breakage events. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.

Phylogenetic Analysis of Genome Rearrangements among Five Mammalian Orders

PubMed Central

Luo, Haiwei; Arndt, William; Zhang, Yiwei; Shi, Guanqun; Alekseyev, Max; Tang, Jijun; Hughes, Austin L.; Friedman, Robert

2015-01-01

Evolutionary relationships among placental mammalian orders have been controversial. Whole genome sequencing and new computational methods offer opportunities to resolve the relationships among 10 genomes belonging to the mammalian orders Primates, Rodentia, Carnivora, Perissodactyla and Artiodactyla. By application of the double cut and join distance metric, where gene order is the phylogenetic character, we computed genomic distances among the sampled mammalian genomes. With a marsupial outgroup, the gene order tree supported a topology in which Rodentia fell outside the cluster of Primates, Carnivora, Perissodactyla, and Artiodactyla. Results of breakpoint reuse rate and synteny block length analyses were consistent with the prediction of random breakage model, which provided a diagnostic test to support use of gene order as an appropriate phylogenetic character in this study. We the influence of rate differences among lineages and other factors that may contribute to different resolutions of mammalian ordinal relationships by different methods of phylogenetic reconstruction. PMID:22929217

Study of Natural Fiber Breakage during Composite Processing

NASA Astrophysics Data System (ADS)

Quijano-Solis, Carlos Jafet

Biofiber-thermoplastic composites have gained considerable importance in the last century. To provide mechanical reinforcement to the polymer, fibers must be larger than a critical aspect ratio (length-to-width ratio). However, biofibers undergo breakage in length or width during processing, affecting their final aspect ratio in the composites. In this study, influence on biofiber breakage by factors related to processing conditions, fiber morphology and the flow type was investigated through: a) experiments using an internal mixer, a twin-screw extruder (TSE) or a capillary rheometer; and b) a Monte Carlo computer simulation. Composites of thermomechanical fibers of aspen or wheat straw mixed with polypropylene were studied. Internal mixer experiments analyzed wheat straw and two batches of aspen fibers, named AL and AS. AL fibers had longer average length. Processing variables included the temperature, rotors speed and fiber concentration. TSE experiments studied AL and AS fiber composites under various screws speeds, temperatures and feeding rates of the polymer and fibers. Capillary rheometers experiments determined AL fiber breakage in shear and elongational flows for composites processed at different concentrations, temperatures, and strain rates. Finally, the internal mixer experimental results where compared to Monte Carlo simulation predictions. The simulation focused on fiber length breakage due to fiber-polymer interactions. Internal mixer results showed that final fiber average length depended almost solely on processing conditions while final fiber average width depended on both processing conditions and initial fiber morphology. In the TSE, processing conditions as well as initial fiber length influenced final average length. TSE results showed that the fiber concentration regime seems to influence the effect of processing variables on fiber breakage. Capillary rheometer experiments demonstrated that biofiber breakage happens in both elongational and shear flows. In some cases, percentage of biofiber breakage in elongational flow is higher. In general, simulation predictions of final average lengths were in good agreement with experiments, indicating the importance of fiber-polymer interactions on fiber breakage. The largest discrepancies were obtained at higher fiber concentration composites; these differences might be resolved, in future simulations, by including the effect of fiber-fiber interactions.

Dynamic Simulation of Three Dimensional Architectural and Mechanical Alterations in Human Trabecular Bone during Menopause

PubMed Central

Liu, X. Sherry; Huang, Angela H.; Zhang, X. Henry; Sajda, Paul; Ji, Baohua; Guo, X. Edward

2008-01-01

A three dimensional (3D) computational simulation of dynamic process of trabecular bone remodeling was developed with all the parameters derived from physiological and clinical data. Contributions of the microstructural bone formation deficits: trabecular plate perforations, trabecular rod breakages, and isolated bone fragments, to the rapid bone loss and disruption of trabecular microarchitecture during menopause were studied. Eighteen human trabecular bone samples from femoral neck (FN) and spine were scanned using a micro computed tomography (μCT) system. Bone resorption and formation were simulated as a computational cycle corresponding to 40-day resorption/160-day formation. Resorption cavities were randomly created over the bone surface according to the activation frequency, which was strictly based on clinical data. Every resorption cavity was refilled during formation unless it caused trabecular plate perforation, trabecular rod breakage or isolated fragments. A 20-year-period starting 5 years before and ending 15 years after menopause was simulated for each specimen. Elastic moduli, standard and individual trabeculae segmentation (ITS)-based morphological parameters were evaluated for each simulated 3D image. For both spine and FN groups, the time courses of predicted bone loss pattern by microstructural bone formation deficits were fairly consistent with the clinical measurements. The percentage of bone loss due to trabecular plate perforation, trabecular rod breakage, and isolated bone fragments were 73.2%, 18.9% and 7.9% at the simulated 15 years after menopause. The ITS-based plate fraction (pBV/BV), mean plate surface area (pTb.S), plate number density (pTb.N), and mean rod thickness (rTb.Th) decreased while rod fraction (rBV/BV) and rod number density (rTb.N) increased after the simulated menopause. The dynamic bone remodeling simulation based on microstructural bone formation deficits predicted the time course of menopausal bone loss pattern of spine and FN. Microstructural plate perforation could be the primary cause of menopausal trabecular bone loss. The combined effect of trabeculae perforation, breakage, and isolated fragments resulted in fewer and smaller trabecular plates and more but thinner trabecular rods. PMID:18550463

One-group interfacial area transport in vertical air-water bubbly flow

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

Wu, Q.; Kim, S.; Ishii, M.

In the two-fluid model for two-phase flows, interfacial area concentration is one of the most important closure relations that should be obtained from careful mechanistic modeling. The objective of this study is to develop a one-group interfacial area transport equation together with the modeling of the source and sink terms due to bubble breakage and coalescence. For bubble coalescence, two mechanisms are considered to be dominant in vertical two-phase bubbly flow. These are the random collisions between bubbles due to turbulence in the flow field, and the wake entrainment process due to the relative motion of the bubbles in themore » wake region of a seeding bubble. For bubble breakup, the impact of turbulent eddies is considered. These phenomena are modeled individually, resulting in a one-group interfacial area concentration transport equation with certain parameters to be determined from experimental data. Compared to the measured axial distribution of the interfacial area concentration under various flow conditions, these parameters are obtained for the reduced one-group, one-dimensional transport equation. The results indicate that the proposed models for bubble breakup and coalescence are appropriate.« less

Needle breakage during an inferior alveolar nerve block in a child with KBG syndrome: A case report.

PubMed

Bagattoni, S; D'Alessandro, G; Marzo, G; Piana, G

2018-04-01

Needle breakage during the administration of dental analgesia is an extremely rare event. A case of needle breakage during the administration of an inferior alveolar nerve block occurred in a child with KBG syndrome. During the injection, a sudden movement of the child caused the breakage of the needle. The next day, the retrieval of the needle was performed surgically under general analgesia. Three months after the surgery the healing was good. Two years later the child underwent a dental extraction with the aid of nitrous oxide/oxygen analgesia/anxiolysis. Needle fracture is a possible event during the administration of dental analgesia in children.

A discrete element method-based approach to predict the breakage of coal

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

Gupta, Varun; Sun, Xin; Xu, Wei

Pulverization is an essential pre-combustion technique employed for solid fuels, such as coal, to reduce particle sizes. Smaller particles ensure rapid and complete combustion, leading to low carbon emissions. Traditionally, the resulting particle size distributions from pulverizers have been determined by empirical or semi-empirical approaches that rely on extensive data gathered over several decades during operations or experiments, with limited predictive capabilities for new coals and processes. Our work presents a Discrete Element Method (DEM)-based computational approach to model coal particle breakage with experimentally characterized coal physical properties. We also examined the effect of select operating parameters on the breakagemore » behavior of coal particles.« less

A discrete element method-based approach to predict the breakage of coal

DOE PAGES

Gupta, Varun; Sun, Xin; Xu, Wei; ...

2017-08-05

Pulverization is an essential pre-combustion technique employed for solid fuels, such as coal, to reduce particle sizes. Smaller particles ensure rapid and complete combustion, leading to low carbon emissions. Traditionally, the resulting particle size distributions from pulverizers have been determined by empirical or semi-empirical approaches that rely on extensive data gathered over several decades during operations or experiments, with limited predictive capabilities for new coals and processes. Our work presents a Discrete Element Method (DEM)-based computational approach to model coal particle breakage with experimentally characterized coal physical properties. We also examined the effect of select operating parameters on the breakagemore » behavior of coal particles.« less

Compaction bands in porous rocks: localization analysis using breakage mechanics

NASA Astrophysics Data System (ADS)

Das, Arghya; Nguyen, Giang; Einav, Itai

2010-05-01

It has been observed in fields and laboratory studies that compaction bands are formed within porous rocks and crushable granular materials (Mollema and Antonellini, 1996; Wong et al., 2001). These localization zones are oriented at high angles to the compressive maximum principal stress direction. Grain crushing and pore collapse are the integral parts of the compaction band formation; the lower porosity and increased tortuosity within such bands tend to reduce their permeability compared to the outer rock mass. Compaction bands may thereafter act as flow barriers, which can hamper the extraction or injection of fluid into the rocks. The study of compaction bands is therefore not only interesting from a geological viewpoint but has great economic importance to the extraction of oil or natural gas in the industry. In this paper, we study the formation of pure compaction bands (i.e. purely perpendicular to the principal stress direction) or shear-enhanced compaction bands (i.e. with angles close to the perpendicular) in high-porosity rocks using both numerical and analytical methods. A model based on the breakage mechanics theory (Einav, 2007a, b) is employed for the present analysis. The main aspect of this theory is that it enables to take into account the effect that changes in grain size distribution has on the constitutive stress-strain behaviour of granular materials at the microscopic level due to grain crushing. This microscopic phenomenon of grain crushing is explicitly linked with a macroscopic internal variable, called Breakage, so that the evolving grain size distribution can be continuously monitored at macro scale during the process of deformation. Through the inclusion of an appropriate parameter the model is also able to capture the effects of pore collapse on the macroscopic response. Its possession of few physically identifiable parameters is another important feature which minimises the effort of their recalibration, since those become less sensitive to the state of the matter (e.g. the initial porosity and grain size distribution). In our previous work (Nguyen and Einav, 2009) we showed that the breakage mechanics model is capable of capturing the experimentally observed stress-strain behaviour of sandstones under conventional triaxial loading, along with the associated evolving grain size distribution. Here, these predictions are further improved through the inclusion of the additional pore-collapse parameter. Furthermore, localization analysis that is based on the loss of positive definiteness of the determinant of the acoustic tensor (Issen and Rudnicki, 2000) is performed to determine the onset of compaction localization, as an indication of material failure. This analysis results in the prediction of the possible range of compaction band orientations. The behaviour and onset of compaction localization of different sandstones are numerically predicted in well accordance with published experimental observations. A parametric study is also carried out to emphasize the complementary effects of grain crushing and pore-collapse on the formation of compaction bands. References Einav, I. (2007a), Breakage mechanics-Part I: Theory, J. Mechan. Phys. Sol. 55(6), 1274-1297. Einav, I. (2007b), Breakage mechanics-Part II: Modelling granular materials, J. Mech. Phys. Sol. 55(6), 1298- 1320. Issen, K.A., Rudnicki, J.W. (2000), Conditions for compaction bands in porous rocks, J. Geophys. Res. Lett., 105, 21,529-21,536. Mollema, P.N., Antonellini, M.A. (1996), Compaction bands: a structural analog for anti-mode I cracks in aeolian sandstone, Tectonophysics 267:209-228. Nguyen, G.D., Einav, I. (2009), The energetics of cataclasis based on breakage mechanics, Pure Appl. Geophys., 166(10), 1693 - 1724. Wong, T-F, Baud, P., Klein, E. (2001), Localized failure modes in a compactant porous rock, J. Geophys. Res. Lett., 28, 2521-2524.

Preliminary Modulus and Breakage Calculations on Cellulose Models

USDA-ARS?s Scientific Manuscript database

The Young’s modulus of polymers can be calculated by stretching molecular models with the computer. The molecule is stretched and the derivative of the changes in stored potential energy for several displacements, divided by the molecular cross-section area, is the stress. The modulus is the slope o...

Size Effect on Specific Energy Distribution in Particle Comminution

NASA Astrophysics Data System (ADS)

Xu, Yongfu; Wang, Yidong

A theoretical study is made to derive an energy distribution equation for the size reduction process from the fractal model for the particle comminution. Fractal model is employed as a valid measure of the self-similar size distribution of comminution daughter products. The tensile strength of particles varies with particle size in the manner of a power function law. The energy consumption for comminuting single particle is found to be proportional to the 5(D-3)/3rd order of the particle size, D being the fractal dimension of particle comminution daughter. The Weibull statistics is applied to describe the relationship between the breakage probability and specific energy of particle comminution. A simple equation is derived for the breakage probability of particles in view of the dependence of fracture energy on particle size. The calculated exponents and Weibull coefficients are generally in conformity with published data for fracture of particles.

Wafer screening device and methods for wafer screening

DOEpatents

Sopori, Bhushan; Rupnowski, Przemyslaw

2014-07-15

Wafer breakage is a serious problem in the photovoltaic industry because a large fraction of wafers (between 5 and 10%) break during solar cell/module fabrication. The major cause of this excessive wafer breakage is that these wafers have residual microcracks--microcracks that were not completely etched. Additional propensity for breakage is caused by texture etching and incomplete edge grinding. To eliminate the cost of processing the wafers that break, it is best to remove them prior to cell fabrication. Some attempts have been made to develop optical techniques to detect microcracks. Unfortunately, it is very difficult to detect microcracks that are embedded within the roughness/texture of the wafers. Furthermore, even if such detection is successful, it is not straightforward to relate them to wafer breakage. We believe that the best way to isolate the wafers with fatal microcracks is to apply a stress to wafers--a stress that mimics the highest stress during cell/module processing. If a wafer survives this stress, it has a high probability of surviving without breakage during cell/module fabrication. Based on this, we have developed a high throughput, noncontact method for applying a predetermined stress to a wafer. The wafers are carried on a belt through a chamber that illuminates the wafer with an intense light of a predetermined intensity distribution that can be varied by changing the power to the light source. As the wafers move under the light source, each wafer undergoes a dynamic temperature profile that produces a preset elastic stress. If this stress exceeds the wafer strength, the wafer will break. The broken wafers are separated early, eliminating cost of processing into cell/module. We will describe details of the system and show comparison of breakage statistics with the breakage on a production line.

Condom use errors and problems in a national sample of young Croatian adults.

PubMed

Baćak, Valerio; Stulhofer, Aleksandar

2012-08-01

In this study, we examined the correlates of condom use errors and problems in a population-based study conducted in 2010 among young Croatian adults aged 18-25 years. Out of a total sample of 1,005 participants, 679 reported condom use in the preceding year. The analyses focused on four outcomes: condom breakage, condom slippage, condom-related erection loss, and delayed condom application. Eighteen percent of participants experienced breakage, 13% reported slippage, 17% reported erection loss, and 34% applied a condom after intercourse started. Multivariate logistic regression analyses were performed to examine the correlates of these condom use errors and problems. Condom breakage was less likely to be reported by women and older participants. The odds of breakage were increased for participants who reported being under the influence of drugs during sex and who reported other condom use errors and problems in the past year. Condom slippage was more likely to occur among younger participants and those who reported condom breakage and delayed condom application. Condom-related erection loss was positively associated with a higher number of sexual partners in the preceding year, condom breakage, and a higher score on the Anti-Erotic Obstacles to Condom Use Scale. Odds of delayed condom application were increased for participants who experienced condom breakage and for those who consumed alcohol before sex in the past year. Having used a condom at first sex significantly reduced the odds of applying a condom after intercourse started. In comparison to non-habitual condom users, habitual users were found less likely to report any of the assessed condom use errors and problems. Improving condom use skills remains an important task in Croatia, which is currently hampered by the absence of evidence-based sex education in schools.

A Survey of Parachute Ankle Brace Breakages

DTIC Science & Technology

2008-01-10

experience an ankle fracture , and 1.75 times more likely to experience an ankle injury of any type. Injuries to other parts of the lower body...A SURVEY OF PARACHUTE ANKLE BRACE BREAKAGES USACHPPM REPORT NO. 12-MA01Q2A-08 REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704...CONTRACT NUMBER 5b. GRANT NUMBER 4. TITLE AND SUBTITLE A Survey of Parachute Ankle Brace Breakages 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER

Paravertebral block catheter breakage by electrocautery during thoracic surgery.

PubMed

Saeki, Noboru; Sugimoto, Yuki; Mori, Yoko; Kato, Takahiro; Miyoshi, Hirotsugu; Nakamura, Ryuji; Koga, Tomomichi

2017-06-01

Advantages of thoracic paravertebral analgesia (TPA) include placement of the catheter closer to the surgical field; however, the catheter can become damaged during the operation. We experienced a case of intraoperative TPA catheter breakage that prompted us to perform an experiment to investigate possible causes. A 50-year-old male underwent a thoracoscopic lower lobectomy under general anesthesia with TPA via an intercostal approach. Following surgery, it was discovered that the catheter had become occluded, as well as cut and fused, so we reopened the incision and removed the residual catheter. From that experience, we performed an experiment to examine electrocautery-induced damage in normal (Portex™, Smith's Medical), radiopaque (Perifix SoftTip™, BBraun), and reinforced (Perifix FX™, BBraun) epidural catheters (n = 8 each). Chicken meat was penetrated by each catheter and then cut by electrocautery. In the normal group, breakage occurred in 8 and occlusion in 6 of the catheters, and in the radiopaque group breakage occurred in 8 and occlusion in 7. In contrast, breakage occurred in only 3 and occlusion in none in the reinforced group, with the 5 without breakage remaining connected only by the spring coil. Furthermore, in 7 of the reinforced catheters, electric arc-induced thermal damage was observed at the tip of the catheter. A TPA catheter for thoracic surgery should be inserted via the median approach, or it should be inserted after surgery to avoid catheter damage during surgery.

The long non-coding RNA PARTICLE is associated with WWOX and the absence of FRA16D breakage in osteosarcoma patients.

PubMed

O'Leary, Valerie Bríd; Maugg, Doris; Smida, Jan; Baumhoer, Daniel; Nathrath, Michaela; Ovsepian, Saak Victor; Atkinson, Michael John

2017-10-20

Breakage of the fragile site FRA16D disrupts the WWOX (WW Domain Containing Oxidoreductase) tumor suppressor gene in osteosarcoma. However, the frequency of breakage is not sufficient to explain the rate of WWOX loss in pathogenesis. The involvement of non-coding RNA transcripts is proposed due to their accumulation at fragile sites, where they are advocated to influence specific chromosomal regions associated with malignancy. The long ncRNA PARTICLE (promoter of MAT2A antisense radiation-induced circulating long non-coding RNA) is transiently elevated in response to irradiation and influences epigenetic silencing modification within WWOX . It now emerges that elevated PARTICLE levels are significantly associated with FRA16D non-breakage in OS patients. Although not associated with overall survival, high PARTICLE levels were found to be significantly linked to metastasis free outcome. The transcription of both PARTICLE and WWOX are transiently responsive to exposure to low doses of radiation in osteosarcoma cell lines. Herein, a relationship between WWOX and PARTICLE transcription is suggested in human osteosarcoma cell lines representing alternative genetic backgrounds. PARTICLE over-expression ameliorated WWOX promoter activity in U2OS harboring FRA16D non-breakage. It can be concluded that the lncRNA PARTICLE influences the WWOX tumor suppressor and in the absence of WWOX FRA16D breakage, it is associated with OS metastasis-free survival.

Telomere healing following DNA polymerase arrest-induced breakages is likely the main mechanism generating chromosome 4p terminal deletions.

PubMed

Hannes, Femke; Van Houdt, Jeroen; Quarrell, Oliver W; Poot, Martin; Hochstenbach, Ron; Fryns, Jean-Pierre; Vermeesch, Joris R

2010-12-01

Constitutional developmental disorders are frequently caused by terminal chromosomal deletions. The mechanisms and/or architectural features that might underlie those chromosome breakages remain largely unexplored. Because telomeres are the vital DNA protein complexes stabilizing linear chromosomes against chromosome degradation, fusion, and incomplete replication, those terminal-deleted chromosomes acquired new telomeres either by telomere healing or by telomere capture. To unravel the mechanisms leading to chromosomal breakage and healing, we sequenced nine chromosome 4p terminal deletion boundaries. A computational analysis of the breakpoint flanking region, including 12 previously published pure terminal breakage sites, was performed in order to identify architectural features that might be involved in this process. All terminal 4p truncations were likely stabilized by telomerase-mediated telomere healing. In the majority of breakpoints multiple genetic elements have a potential to induce secondary structures and an enrichment in replication stalling site motifs were identified. These findings suggest DNA replication stalling-induced chromosome breakage during early development is the first mechanistic step leading toward terminal deletion syndromes. © 2010 Wiley-Liss, Inc.

Branch breakage under snow and ice loads.

PubMed

Cannell, M G; Morgan, J

1989-09-01

Measurements were made on branches and trunks of Picea sitchensis (Bong.) Carr. to determine the relationship between (i) the bending moment at the bases of branches that cause breakage, and (ii) midpoint diameter cubed. The theory for cantilever beams was then used to calculate the basal bending moments and midpoint diameters of branches with different numbers of laterals and endpoint deflections, given previously measured values of Young's modulus, taper and weights of foliage and wood. Snow and ice loads (equal to 2 and 4 g cm(-1) of shoot, respectively) were then included in the calculation to determine whether the basal bending moments exceeded the breakage values. The likelihood of breakage increased with an increase in (i) number of laterals, and (ii) endpoint deflection under self weight (without snow or ice)-features that had previously been shown to lessen the amount of branch wood required to support a unit of foliage. However, branches which deflected moderately (> 10% of their length) under their own weight deflected greatly under snow or ice loads and might shed powdery snow before breakage occurs.

Mesoscale Fracture Analysis of Multiphase Cementitious Composites Using Peridynamics

PubMed Central

Yaghoobi, Amin; Chorzepa, Mi G.; Kim, S. Sonny; Durham, Stephan A.

2017-01-01

Concrete is a complex heterogeneous material, and thus, it is important to develop numerical modeling methods to enhance the prediction accuracy of the fracture mechanism. In this study, a two-dimensional mesoscale model is developed using a non-ordinary state-based peridynamic (NOSBPD) method. Fracture in a concrete cube specimen subjected to pure tension is studied. The presence of heterogeneous materials consisting of coarse aggregates, interfacial transition zones, air voids and cementitious matrix is characterized as particle points in a two-dimensional mesoscale model. Coarse aggregates and voids are generated using uniform probability distributions, while a statistical study is provided to comprise the effect of random distributions of constituent materials. In obtaining the steady-state response, an incremental and iterative solver is adopted for the dynamic relaxation method. Load-displacement curves and damage patterns are compared with available experimental and finite element analysis (FEA) results. Although the proposed model uses much simpler material damage models and discretization schemes, the load-displacement curves show no difference from the FEA results. Furthermore, no mesh refinement is necessary, as fracture is inherently characterized by bond breakages. Finally, a sensitivity study is conducted to understand the effect of aggregate volume fraction and porosity on the load capacity of the proposed mesoscale model. PMID:28772518

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

Li, Yang; Gong, Hao; Sun, Yue

Highlights: Black-Right-Pointing-Pointer We dissect how individual disulfide bond affects the amyloidogenicity of insulin. Black-Right-Pointing-Pointer A controlled reduction system for insulin is established in this study. Black-Right-Pointing-Pointer Disulfide breakage is associated with unfolding and increased amyloidogenicity. Black-Right-Pointing-Pointer Breakage of A6-A11 is associated with significantly increased cytotoxicity. Black-Right-Pointing-Pointer Analogs without A6-A11 have a higher potency to form high order toxic oligomers. -- Abstract: Disulfide bonds play a critical role in the stability and folding of proteins. Here, we used insulin as a model system, to investigate the role of its individual disulfide bond during the amyloid formation of insulin. Tris(2-carboxyethyl)phosphine (TCEP) wasmore » applied to reduce two of the three disulfide bonds in porcine insulin and the reduced disulfide bonds were then alkylated by iodoacetamide. Three disulfide bond-modified insulin analogs, INS-2 (lack of A6-A11), INS-3 (lack of A7-B7) and INS-6 (lack of both A6-A11 and A7-B7), were obtained. Far-UV circular dichroism (CD) spectroscopy results indicated that the secondary structure of INS-2 was the closest to insulin under neutral conditions, followed by INS-3 and INS-6, whereas in an acidic solution all analogs were essentially unfolded. To test how these modifications affect the amyloidogenicity of insulin, thioflavin-T (ThT) fluorescence and transmission electronic microscopy (TEM) were performed. Our results showed that all analogs were more prone to aggregation than insulin, with the order of aggregation rates being INS-6 > INS-3 > INS-2. Cross-linking of unmodified proteins (PICUP) assay results showed that analogs without A6-A11 (INS-2 and INS-6) have a higher potential for oligomerization than insulin and INS-3, which is accompanied with a higher cytotoxicity as the hemolytic assays of human erythrocytes suggested. The results indicated that breakage of A7-B7 induced more unfolding of the insulin structure and a higher amyloidogenicity than breakage of A6-A11, but breakage of A6-A11 caused a significant cytotoxicity increase and a higher potency to form high order toxic oligomers.« less

Study on shear properties of coral sand under cyclic simple shear condition

NASA Astrophysics Data System (ADS)

Ji, Wendong; Zhang, Yuting; Jin, Yafei

2018-05-01

In recent years, the ocean development in our country urgently needs to be accelerated. The construction of artificial coral reefs has become an important development direction. In this paper, experimental studies of simple shear and cyclic simple shear of coral sand are carried out, and the shear properties and particle breakage of coral sand are analyzed. The results show that the coral sand samples show an overall shear failure in the simple shear test, which is more accurate and effective for studying the particle breakage. The shear displacement corresponding to the peak shear stress of the simple shear test is significantly larger than that corresponding to the peak shear stress of the direct shear test. The degree of particle breakage caused by the simple shear test is significantly related to the normal stress level. The particle breakage of coral sand after the cyclic simple shear test obviously increases compared with that of the simple shear test, and universal particle breakage occurs within the whole particle size range. The increasing of the cycle-index under cyclic simple shear test results in continuous compacting of the sample, so that the envelope curve of peak shearing force increases with the accumulated shear displacement.

A Model for Fiber Length Attrition in Injection-Molded Long-Fiber Composites

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

TuckerIII, Charles L.; Phelps, Jay H; El-Rahman, Ahmed Abd

2013-01-01

Long-fiber thermoplastic (LFT) composites consist of an engineering thermoplastic matrix with glass or carbon reinforcing fibers that are initially 10 to 13 mm long. When an LFT is injection molded, flow during mold filling orients the fibers and degrades the fiber length. Fiber orientation models for injection molding are well developed, and special orientation models for LFTs have been developed. Here we present a detailed quantitative model for fiber length attrition in a flowing fiber suspension. The model tracks a discrete fiber length distribution (FLD) at each spatial node. Key equations are a conservation equation for total fiber length, andmore » a breakage rate equation. The breakage rate is based on buckling of fibers due to hydrodynamic forces, when the fibers are in unfavorable orientations. The FLD model is combined with a mold filling simulation to predict spatial and temporal variations in fiber length distribution in a mold cavity during filling. The predictions compare well to experiments on a glassfiber/ PP LFT molding. Fiber length distributions predicted by the model are easily incorporated into micromechanics models to predict the stress-strain behavior of molded LFT materials. Author to whom correspondence should be addressed; electronic mail: ctucker@illinois.edu 1« less

Influence of knee flexion angle and transverse drill angle on creation of femoral tunnels in double-bundle anterior cruciate ligament reconstruction using the transportal technique: Three-dimensional computed tomography simulation analysis.

PubMed

Choi, Chong Hyuk; Kim, Sung-Jae; Chun, Yong-Min; Kim, Sung-Hwan; Lee, Su-Keon; Eom, Nam-Kyu; Jung, Min

2018-01-01

The purpose of this study was to find appropriate flexion angle and transverse drill angle for optimal femoral tunnels of anteromedial (AM) bundle and posterolateral (PL) bundle in double-bundle ACL reconstruction using transportal technique. Thirty three-dimensional knee models were reconstructed. Knee flexion angles were altered from 100° to 130° at intervals of 10°. Maximum transverse drill angle (MTA), MTA minus 10° and 20° were set up. Twelve different tunnels were determined by four flexion angles and three transverse drill angles for each bundle. Tunnel length, wall breakage, inter-tunnel communication and graft-bending angle were assessed. Mean tunnel length of AM bundle was >30mm at 120° and 130° of flexion in all transverse drill angles. Mean tunnel length of PL bundle was >30mm during every condition. There were ≥1 cases of wall breakage except at 120° and 130° of flexion with MTA for AM bundle. There was no case of wall breakage for PL bundle. Considering inter-tunnel gap of >2mm without communication and obtuse graft-bending angle, 120° of flexion and MTA could be recommended as optimal condition for femoral tunnels of AM and PL bundles. Flexion angle and transverse drill angle had combined effect on femoral tunnel in double-bundle ACL reconstruction using transportal technique. Achieving flexion angle of 120° and transverse drill angle close to the medial femoral condyle could be recommended as optimal condition for femoral tunnels of AM and PL bundles to avoid insufficient tunnel length, wall breakage, inter-tunnel communication and acute graft-bending angle. Copyright © 2017 Elsevier B.V. All rights reserved.

Glutamate 338 is an electrostatic facilitator of C–Co bond breakage in a dynamic/electrostatic model of catalysis by ornithine aminomutase

PubMed Central

Menon, Binuraj R K; Menon, Navya; Fisher, Karl; Rigby, Stephen E J; Leys, David; Scrutton, Nigel S

2015-01-01

How cobalamin-dependent enzymes promote C–Co homolysis to initiate radical catalysis has been debated extensively. For the pyridoxal 5′-phosphate and cobalamin-dependent enzymes lysine 5,6-aminomutase and ornithine 4,5-aminomutase (OAM), large-scale re-orientation of the cobalamin-binding domain linked to C–Co bond breakage has been proposed. In these models, substrate binding triggers dynamic sampling of the B12-binding Rossmann domain to achieve a catalytically competent ‘closed’ conformational state. In ‘closed’ conformations of OAM, Glu338 is thought to facilitate C–Co bond breakage by close association with the cobalamin adenosyl group. We investigated this using stopped-flow continuous-wave photolysis, viscosity dependence kinetic measurements, and electron paramagnetic resonance spectroscopy of a series of Glu338 variants. We found that substrate-induced C–Co bond homolysis is compromised in Glu388 variant forms of OAM, although photolysis of the C–Co bond is not affected by the identity of residue 338. Electrostatic interactions of Glu338 with the 5′-deoxyadenosyl group of B12 potentiate C–Co bond homolysis in ‘closed’ conformations only; these conformations are unlocked by substrate binding. Our studies extend earlier models that identified a requirement for large-scale motion of the cobalamin domain. Our findings indicate that large-scale motion is required to pre-organize the active site by enabling transient formation of ‘closed’ conformations of OAM. In ‘closed’ conformations, Glu338 interacts with the 5′-deoxyadenosyl group of cobalamin. This interaction is required to potentiate C–Co homolysis, and is a crucial component of the approximately 1012 rate enhancement achieved by cobalamin-dependent enzymes for C–Co bond homolysis. PMID:25627283

The investigation of tethered satellite system dynamics

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1985-01-01

Progress in tethered satellite system dynamics research is reported. A retrieval rate control law with no angular feedback to investigate the system's dynamic response was studied. The initial conditions for the computer code which simulates the satellite's rotational dynamics were extended to a generic orbit. The model of the satellite thrusters was modified to simulate a pulsed thrust, by making the SKYHOOK integrator suitable for dealing with delta functions without loosing computational efficiency. Tether breaks were simulated with the high resolution computer code SLACK3. Shuttle's maneuvers were tested. The electric potential around a severed conductive tether with insulator, in the case of a tether breakage at 20 km from the Shuttle, was computed. The electrodynamic hazards due to the breakage of the TSS electrodynamic tether in a plasma are evaluated.

Relationship between architecture, filament breakage and critical current decay in Nb3Sn composite wires repeatedly in-plane bent at room temperature

NASA Astrophysics Data System (ADS)

Badica, P.; Awaji, S.; Oguro, H.; Nishijima, G.; Watanabe, K.

2006-04-01

Six Nb3Sn composite wires with different architectures ('central and near-the-edge reinforcement') were repeatedly in-plane bent at room temperature (in-plane 'pre-bending'). Breakage behaviour was revealed from scanning electron microscopy observations by semi-quantitative analysis of the filament crack formation and evolution. Cracks are formed in the transversal and longitudinal directions. Transversal cracks show some tolerance to the applied bending strain due to the fact that filaments are composite materials; residual Nb core can arrest development of a partial transversal crack initiated in the Nb3Sn outer part of the filament. Together with the density of cracks C and the evolution of this parameter with pre-bending strain, ɛpb, in different regions of the wire, R-ɛpb curves are important to understand breakage behaviour of the wires. R is the ratio (number of full transversal cracks)/(number of full transversal cracks + number of partial transversal cracks). Parameters C and R allow us to reveal and satisfactorily understand the wire architecture—breakage—critical current decay relationship when pre-bending treatment is applied. As a consequence, breakage criteria necessary to minimize Ic decay were defined and the positive influence of the reinforcement in preventing breakage was observed. It was also found that, in this regard, more Nb in the CuNb reinforcement, for the investigated wires, is better, if the heat treatment for the wire synthesis is performed at 670 °C for 96 h. A different heat treatment, 650 °C for 240 h, is less efficient in preventing filament breakage. Our results suggest the possibility of control and improvement of the breakage susceptibility of the filaments in the wires and, hence, of the bending Ic decay, through the wise design of the wire architecture (i.e. by correlating design with the choice of composing materials and heat treatments).

Development of yarn breakage detection software system based on machine vision

NASA Astrophysics Data System (ADS)

Wang, Wenyuan; Zhou, Ping; Lin, Xiangyu

2017-10-01

For questions spinning mills and yarn breakage cannot be detected in a timely manner, and save the cost of textile enterprises. This paper presents a software system based on computer vision for real-time detection of yarn breakage. The system and Windows8.1 system Tablet PC, cloud server to complete the yarn breakage detection and management. Running on the Tablet PC software system is designed to collect yarn and location information for analysis and processing. And will be processed after the information through the Wi-Fi and http protocol sent to the cloud server to store in the Microsoft SQL2008 database. In order to follow up on the yarn break information query and management. Finally sent to the local display on time display, and remind the operator to deal with broken yarn. The experimental results show that the system of missed test rate not more than 5%o, and no error detection.

ATR prohibits replication catastrophe by preventing global exhaustion of RPA.

PubMed

Toledo, Luis Ignacio; Altmeyer, Matthias; Rask, Maj-Britt; Lukas, Claudia; Larsen, Dorthe Helena; Povlsen, Lou Klitgaard; Bekker-Jensen, Simon; Mailand, Niels; Bartek, Jiri; Lukas, Jiri

2013-11-21

ATR, activated by replication stress, protects replication forks locally and suppresses origin firing globally. Here, we show that these functions of ATR are mechanistically coupled. Although initially stable, stalled forks in ATR-deficient cells undergo nucleus-wide breakage after unscheduled origin firing generates an excess of single-stranded DNA that exhausts the nuclear pool of RPA. Partial reduction of RPA accelerated fork breakage, and forced elevation of RPA was sufficient to delay such "replication catastrophe" even in the absence of ATR activity. Conversely, unscheduled origin firing induced breakage of stalled forks even in cells with active ATR. Thus, ATR-mediated suppression of dormant origins shields active forks against irreversible breakage via preventing exhaustion of nuclear RPA. This study elucidates how replicating genomes avoid destabilizing DNA damage. Because cancer cells commonly feature intrinsically high replication stress, this study also provides a molecular rationale for their hypersensitivity to ATR inhibitors. Copyright © 2013 Elsevier Inc. All rights reserved.

Force deficits and breakage rates after single lengthening contractions of single fast fibers from unconditioned and conditioned muscles of young and old rats.

PubMed

Lynch, Gordon S; Faulkner, John A; Brooks, Susan V

2008-07-01

The deficit in force generation is a measure of the magnitude of damage to sarcomeres caused by lengthening contractions of either single fibers or whole muscles. In addition, permeabilized single fibers may suffer breakages. Our goal was to understand the interaction between breakages and force deficits in "young" and "old" permeabilized single fibers from control muscles of young and old rats and "conditioned" fibers from muscles that completed a 6-wk program of in vivo lengthening contractions. Following single lengthening contractions of old-control fibers compared with young-control fibers, the twofold greater force deficits at a 10% strain support the concept of an age-related increase in the susceptibility of fibers to mechanical damage. In addition, the much higher breakage rates for old fibers at all strains tested indicate an increase with aging in the number of fibers at risk of being severely injured during any given stretch. Following the 6-wk program of lengthening contractions, young-conditioned fibers and old-conditioned fibers were not different with respect to force deficit or the frequency of breakages. A potential mechanism for the increased resistance to stretch-induced damage of old-conditioned fibers is that, through intracellular damage and subsequent degeneration and regeneration, weaker sarcomeres were replaced by stronger sarcomeres. These data indicate that, despite the association of high fiber breakage rates and large force deficits with aging, the detrimental characteristics of old fibers were improved by a conditioning program that altered both sarcomeric characteristics as well as the overall structural integrity of the fibers.

Effects of interfacial debonding and fiber breakage on static and dynamic buckling of fibers embedded in matrices

NASA Astrophysics Data System (ADS)

Serttunc, Metin

1992-09-01

Analyses were performed for static and dynamic buckling of a continuous fiber embedded in a matrix in order to determine the effects of interfacial debonding and fiber breakage on the critical buckling load and the domain of instability. A beam on elastic foundation model was used. The study showed that a local interfacial debonding between a fiber and a surrounding matrix resulted in an increase of the wavelength of the buckling mode. An increase of the wave length yielded a decrease of the static buckling load and lowered the dynamic instability domain. In general, the effect of a partial or complete interfacial debonding was more significant on the domain of dynamic instability than on the effects of static buckling load. For dynamic buckling of a fiber, a local debonding of size 10 to 20 percent of the fiber length had the most important influence on the domains of dynamic instability regardless of the location of debonding and the boundary conditions of the fiber. For static buckling, the location of a local debonding was critical to a free-simply supported fiber but not to a fiber with both ends simply supported. Fiber breakage also lowered the critical buckling load significantly.

Mathematical modeling of damage in unidirectional composites

NASA Technical Reports Server (NTRS)

Goree, J. G.; Dharani, L. R.; Jones, W. F.

1981-01-01

A review of some approximate analytical models for damaged, fiber reinforced composite materials is presented. Using the classical shear lag stress displacement assumption, solutions are presented for a unidirectional laminate containing a notch, a rectangular cut-out, and a circular hole. The models account for longitudinal matrix yielding and splitting as well as transverse matrix yielding and fiber breakage. The constraining influence of a cover sheet on the unidirectional laminate is also modeled.

The significance of relative density for particle damage in loaded and sheared gravels

NASA Astrophysics Data System (ADS)

Fityus, Stephen; Imre, Emőke

2017-06-01

For granular assemblages of strong particles, an increase in the relative density usually leads to a significant increase in shear strength, which is evident as a peak strength, accompanied by significant dilation as the peak strength is attained. This paper describes an experimental study of shearing in assemblages of weak particles, where particle breakage offsets dilation for all but the lowest of confining stresses. In such materials, prone to particle breakage, the shear strengths of loose and dense assemblages rapidly converge to similar values as confining stress increases, and any benefit of greater relative density is lost. This is attributed to the densification effect associated with the loading under a high stress prior to shearing, which is characterised by widespread particle breakage and the formation of smaller particles to occupy space between coarser ones. Interestingly, under both low and high stresses, there was a tendency for greater particle breakage in the loose samples, as a result of both shearing and compression. This result suggests that, despite the denser assemblage having its particles more rigidly constrained and less able to rearrange to avoid direct loading, the influence of greater load-spreading capacity afforded by an increased number of particle contacts in a denser sample, is more dominant in controlling breakage.

Effect of Deep Cryogenic Treatment on Cyclic Fatigue of Endodontic Rotary Nickel Titanium Instruments

PubMed Central

Yazdizadeh, Mohammad; Skini, Masoumeh; Hoseini Goosheh, Seyyed Mohsen; Jafarzadeh, Mansour; Shamohammadi, Milad; Rakhshan, Vahid

2017-01-01

Introduction: Cyclic fatigue is the common reason for breakage of rotary instruments. This study was conducted to evaluate the effect of cryogenic treatment (CT) in improving the resistance to cyclic fatigue of endodontic rotary instruments. Methods and Materials: In this in vitro study, 20 RaCe and 20 Mtwo files were randomly divided into two groups of negative control and CT. CT files were stored in liquid nitrogen at -196°C for 24 h, and then were gradually warmed to the room temperature. All files were used (at torques and speeds recommended by their manufacturers) in a simulated canal with a 45° curvature until breakage. The time to fail (TF) was recorded and used to calculate the number of cycle to fail (NCF). Groups were compared using independent-samples t-test. Results: Mean NCFs were 1248.2±68.1, 1281.6±78.6, 4126.0±179.2, and 4175.4±190.1 cycles, for the Mtwo-control, Mtwo-CT, RaCe-control, and RaCe-CT, respectively. The difference between the controls and their respective CT groups were not significant (P>0.3). The difference between the systems was significant. Conclusion: Deep CT did not improve resistance to cyclic fatigue of the evaluated rotary files. PMID:28512489

Violence, condom breakage, and HIV infection among female sex workers in Benin, West Africa.

PubMed

Tounkara, Fatoumata K; Diabaté, Souleymane; Guédou, Fernand A; Ahoussinou, Clément; Kintin, Frédéric; Zannou, Djimon M; Kpatchavi, Adolphe; Bédard, Emmanuelle; Bietra, Raphaël; Alary, Michel

2014-05-01

To examine the relationship between violence, condom breakage, and HIV prevalence among female sex workers (FSWs). Data were obtained from the 2012 cross-sectional integrated biological and behavioral survey conducted in Benin. Multivariable log-binomial regression was used to estimate the adjusted prevalence ratios of HIV infection and condom breakage in relation to violence toward FSWs. A score was created to examine the relationship between the number of violence types reported and HIV infection. Among the 981 women who provided a blood sample, HIV prevalence was 20.4%. During the last month, 17.2%, 13.5%, and 33.5% of them had experienced physical, sexual, and psychological violence, respectively. In addition, 15.9% reported at least 1 condom breakage during the previous week. There was a significant association between all types of violence and HIV prevalence. The adjusted prevalence ratios of HIV were 1.45 (95% confidence interval [95% CI], 1.05-2.00), 1.42 (95% CI, 1.02-1.98), and 1.41 (95% CI, 1.08-1.41) among those who had ever experienced physical, sexual, and psychological violence, respectively. HIV prevalence increased with the violence score (P = 0.002, test for trend), and physical and sexual violence were independently associated with condom breakage (P = 0.010 and P = 0.003, respectively). The results show that violence is associated with a higher HIV prevalence among FSWs and that condom breakage is a potential mediator for this association. Longitudinal studies designed to analyze this relationship and specific interventions integrated to current HIV prevention strategies are needed to reduce the burden of violence among FSWs.

Violence, condom breakage and HIV infection among female sex workers in Benin, West Africa

PubMed Central

Tounkara, Fatoumata K.; Diabaté, Souleymane; Guédou, Fernand A.; Ahoussinou, Clément; Kintin, Frédéric; Zannou, Djimon M.; Kpatchavi, Adolphe; Bédard, Emmanuelle; Bietra, Raphaël; Alary, Michel

2014-01-01

Objective To examine the relationship between violence, condom breakage and HIV prevalence among female sex workers (FSWs). Methods Data were obtained from the 2012 cross-sectional integrated biological and behavioural survey conducted in Benin. Multivariable log-binomial regression was used to estimate the adjusted prevalence ratios (APRs) of HIV infection and condom breakage in relation to violence towards FSWs. A score was created to examine the relationship between the number of violence types reported and HIV infection. Results Among the 981 women who provided a blood sample, HIV prevalence was 20.4%. During the last month, 17.2%, 13.5% and 33.5% of them had experienced physical, sexual and psychological violence, respectively. In addition, 15.9% reported at least one condom breakage during the previous week. There was a significant association between all types of violence and HIV prevalence. The APRs of HIV were 1.45 (95% confidence interval [95%CI]: 1.05 – 2.00), 1.42 (95%CI: 1.02 – 1.98), and 1.41 (95%CI: 1.08 – 1.41) among those who had ever experienced physical, sexual and psychological violence, respectively. HIV prevalence increased with the violence score (p=0.002, test for trend), and physical and sexual violence were independently associated with condom breakage (p values 0.010 and 0.003, respectively). Conclusion The results show that violence is associated with a higher HIV prevalence among FSWs and that condom breakage is a potential mediator for this association. Longitudinal studies designed to analyse this relationship and specific interventions integrated to current HIV prevention strategies are needed to reduce the burden of violence among FSWs. PMID:24722385

Corrigendum to "Stem breakage of salt marsh vegetation under wave forcing: A field and model study" [Estuar. Coast Shelf Sci. 200 (2018) 41-58

NASA Astrophysics Data System (ADS)

Vuik, Vincent; Suh Heo, Hannah Y.; Zhu, Zhenchang; Borsje, Bas W.; Jonkman, Sebastiaan N.

2018-03-01

The authors regret that the correct affiliation of co-author Zhenchang Zhu should be 'Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research and Utrecht University, 4400AC, Yerseke, The Netherlands'.

Influence of dioctyl phthalate (DOP) on the mechanical, optical and thermal properties of formulations for the industrial manufacture of radiation sterilizable medical disposables

NASA Astrophysics Data System (ADS)

Ahmed, Shamshad; Mehmood, Mazhar; Iqbal, Rashid

2010-03-01

Shelf life of the formulations designed for the industrial manufacture of radiation sterilizable syringes and other medical disposables is a very important issue world over. Radiation compatible formulations were developed earlier in the laboratory by the incorporation of primary and secondary antioxidants along with processing stabilizers in a random polypropylene copolymer. It has been reported in literature that the mobilizing agents namely hydrocarbons, greases, wax and the plasticizer, dioctyl phthalate (DOP) impart radiation resistance to the polypropylene by providing free volume. It was envisaged that the addition of DOP to the afore-mentioned formulation might favorably influence the mechanical, optical and thermal properties of our formulation. To study the influence of addition of DOP on the afore-mentioned properties, the addition of 1%, 2% and 3% of the mobilizer was made, followed by the irradiation of resulting heat pressed sheets to the industrial standard dose of 25 kGy. Two important characteristic mechanical properties to determine the suitability of the radiation sterilized materials comprise angle of breakage and the haze percent. After irradiation and even on accelerated ageing of the irradiated material, the angle of breakage of heat press sheets of formulations containing 1%, 2% and 3% of DOP was found to be 180°, demonstrating the role of DOP, in imparting additional radiation stability. In case of the irradiated control sample, the angle of breakage was much lower. In the heat pressed sheets containing the DOP, a remarkable retention in the tensile strength, percentage elongation at break, along with improved thermal stability was observed. The formulation devoid of DOP demonstrated poor retention of the afore-mentioned characteristic properties .The observed improvement in thermal stability of the formulations containing DOP hints at the likely possibility of reuse of these materials by autoclaving which is considered an additional attribute.

Severe intrauterine growth retardation with increased mitomycin C sensitivity: a further chromosome breakage syndrome.

PubMed Central

Woods, C G; Leversha, M; Rogers, J G

1995-01-01

We report an infant with pre- and postnatal microcephaly and growth retardation, a distinctive face, and developmental delay. The initial diagnosis was of Seckel syndrome. He became pancytopenic at 16 months and died soon after. His bone marrow was of normal cellularity but had a small lymphocyte infiltration. Increased spontaneous chromosome breakage was seen in blood and fibroblasts. Mitomycin C induced chromosome damage was increased and comparable to that seen in Fanconi anaemia. Reports of similar patients are reviewed. This entity of severe intrauterine growth retardation and increased mitomycin C sensitivity is hypothesised to be a distinct chromosome breakage syndrome. Images PMID:7643362

High Speed Videometric Monitoring of Rock Breakage

NASA Astrophysics Data System (ADS)

Allemand, J.; Shortis, M. R.; Elmouttie, M. K.

2018-05-01

Estimation of rock breakage characteristics plays an important role in optimising various industrial and mining processes used for rock comminution. Although little research has been undertaken into 3D photogrammetric measurement of the progeny kinematics, there is promising potential to improve the efficacy of rock breakage characterisation. In this study, the observation of progeny kinematics was conducted using a high speed, stereo videometric system based on laboratory experiments with a drop weight impact testing system. By manually tracking individual progeny through the captured video sequences, observed progeny coordinates can be used to determine 3D trajectories and velocities, supporting the idea that high speed video can be used for rock breakage characterisation purposes. An analysis of the results showed that the high speed videometric system successfully observed progeny trajectories and showed clear projection of the progeny away from the impact location. Velocities of the progeny could also be determined based on the trajectories and the video frame rate. These results were obtained despite the limitations of the photogrammetric system and experiment processes observed in this study. Accordingly there is sufficient evidence to conclude that high speed videometric systems are capable of observing progeny kinematics from drop weight impact tests. With further optimisation of the systems and processes used, there is potential for improving the efficacy of rock breakage characterisation from measurements with high speed videometric systems.

5 CFR 1605.21 - Plan-paid breakage and other corrections.

Code of Federal Regulations, 2010 CFR

2010-01-01

... participant's account in the wrong investment fund(s). (3) A participant will not be entitled to breakage.... 1605.21 Section 1605.21 Administrative Personnel FEDERAL RETIREMENT THRIFT INVESTMENT BOARD CORRECTION... investment gains or losses the account have received had the error not occurred, the account will be credited...

5 CFR 1605.21 - Plan-paid breakage and other corrections.

Code of Federal Regulations, 2011 CFR

2011-01-01

... participant's account in the wrong investment fund(s). (3) A participant will not be entitled to breakage.... 1605.21 Section 1605.21 Administrative Personnel FEDERAL RETIREMENT THRIFT INVESTMENT BOARD CORRECTION... investment gains or losses the account have received had the error not occurred, the account will be credited...

Aspartate 102 in the Heme Domain of Soluble Guanylyl Cyclase Has a Key Role in NO Activation

PubMed Central

Baskaran, Padmamalini; Heckler, Erin J.; van den Akker, Focco; Beuve, Annie

2012-01-01

Nitric oxide (NO) is involved in the physiology and pathophysiology of the cardiovascular and neuronal systems via activation of soluble guanylyl cyclase (sGC), a heme-containing heterodimer. Recent structural studies have allowed a better understanding of the residues that dictate the affinity and binding of NO to the heme and the resulting breakage of the bond between the heme iron and histidine 105 (H105) of the β subunit of sGC. Still, it is unknown how the breakage of the iron–His bond translates into NO-dependent increased catalysis. Structural studies on homologous H-NOX domains in various states pointed to a role for movement of the H105 containing αF helix. Our modeling of the heme-binding domain highlighted conserved residues in the vicinity of H105 that could potentially regulate the extent to which the αF helix shifts and/or propagate the activation signal once the covalent bond with H105 has been broken. These include a direct interaction of αF helix residue D102 with the backbone nitrogen of F120. Mutational analysis of this region points to an essential role of the interactions in the vicinity of H105 for heme stability and identifies aspartate 102 (D102) as having a key role in NO activation following breakage of the iron–His bond. PMID:21491881

Sacrificial bonds and hidden length in biomaterials: A kinetic constitutive description of strength and toughness in bone

NASA Astrophysics Data System (ADS)

Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.

2013-07-01

Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features by providing a molecular-scale mechanism for energy dissipation. One example is in the polymeric glue connection between collagen fibrils in animal bone. In this paper we propose a simple kinetic model that describes the breakage of sacrificial bonds and the release of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.

Treatment of adolescent patients with class II division 1 malocclusion using Eruption guidance appliance: A comparative study with Twin-block and Activator-Headgear appliances.

PubMed

Nilsson, Jenny Jiayan Luo; Shu, Xiaochen; Magnusson, Britt Hedenberg; Burt, Idil Alatli

2016-01-01

The aim of this study was to evaluate the compliance and short-term effects of eruption guidance appliance (EGA) in adolescents with class II division 1 malocclusion in comparison with twin-block appliance (TBA) and activator-headgear appliance (A-HG). Dental records of 1886 patients were viewed in this retrospective study 129 patients treated with one of these three functional appliances were identified. 123 fulfilled the inclusion criteria and data were extracted from the dental records. Gender, age, compliance, overjet change at every visit, number of appliance breakages and number of emergency visits apart from appliance breakage were studied. The data were analyzed with Chi-square test, General Linear Model and Fisher scoring test. Results showed that 47 patients were treated with EGA, 38 patients with TBA and 38 patients with A-HG. Mean ages starting the treatment were slightly lower with EGA (11.5 years) than with TBA (12.3 years) and A-HG (11.8 years). Non-compliance was higher in the EGA group (31.9%) than TBA group (26.3%) and A-HG group (23.7%). Mean overjet reduction per month was 0.6 mm for EGA which was lower than TBA group (0.7 mm) and A-HG groups (0.7 mm).The number of emergency visits and appliance breakage were lower in EGA group. However, there was no statistically significant difference between the 3 groups regarding ages,compliance, mean overjet reduction, emergency visits and appliance breakage aspects. In conclusion, this study indicates that EGA is an alternative choice in the treatment of adolescent patients with class II division 1 malocclusion. However, long-term follow-up and cephalometric prospective study should be performed to continue our understanding more about the mechanisms of EGA and more definite conclusions can be made.

Application of neural networks for the prediction of rock fragmentation in Chadormalu iron mine / Zastosowanie sieci neuronowych do prognozowania stopnia rozdrobnienia skał w kopalni rud żelaza w Chadormalu

NASA Astrophysics Data System (ADS)

Monjezi, Masoud; Ahmadi, Zabiholla; Khandelwal, Manoj

2012-12-01

Most open-pit mining operations employ blasting for primary breakage of the in-situ rock mass. Inappropriate blasting techniques can result in excessive damage to the wall rock, decreasing stability and increasing water influx. In addition, it will result in either over and/or under breakage of rocks. The presence of over broken rocks can result in decreased wall stability and require additional excavation. In contrast, the presence of under broken rocks may require secondary blasting and additional crushing. Since blasting is a major cost factor, both cases (under and over breakage) create additional costs reflected in the increase of the operation and maintenance of the machinery. Quick and accurate measurements of fragment size distribution are essential for managing fragmented rock and other materials. Various fragmentation measurement techniques are available and are being used by industry/researchers but most of the methods are time consuming and not precise. An ideally performed blasting operation enormously influences the overall mining cost. This aim can be achieved by proper prediction and attenuation of fragmentation. Prediction of fragmentation is essential for optimizing blasting operation. Poor performance of the empirical models for predicting fragmentation has urged the application of new approaches. In this paper, artificial neural network (ANN) method is implemented to develop a model to predict rock fragmentation size distribution due to blasting in Chadormalu iron mine, Iran. In the development of the proposed ANN model, ten parameters such as UCS, drilling rate, water content, burden, spacing, stemming, hole diameter, bench height, powder factor and charge per delay were incorporated. Training and testing of the model was performed by the back-propagation algorithm using 97 datasets. A four-layer ANN was found to be optimum with architecture of 10-7-5-1. A comparison has made between measured results of fragmentation with predicted results of fragmentation by ANN and multiple regression model. Sensitivity analysis was also performed to understand the effect of each influencing parameters on rock fragmentation.

Mechanism and Dynamics of Breakage of Fluorescent Microtubules

PubMed Central

Guo, Honglian; Xu, Chunhua; Liu, Chunxiang; Qu, E.; Yuan, Ming; Li, Zhaolin; Cheng, Bingying; Zhang, Daozhong

2006-01-01

The breakage of fluorescence-labeled microtubules under irradiation of excitation light is found in our experiments. Its mechanism is studied. The results indicate that free radicals are the main reason for the photosensitive breakage. Furthermore, the mechanical properties of the microtubules are probed with a dual-optical tweezers system. It is found that the fluorescence-labeled microtubules are much easier to extend compared with those without fluorescence. Such microtubules can be extended by 30%, and the force for breaking them up is only several piconewtons. In addition, we find that the breakup of the protofilaments is not simultaneous but step-by-step, which further confirms that the interaction between protofilaments is fairly weak. PMID:16387782

Crack Extension and Possibility of Debonding in Encapsulation-Based Self-Healing Materials.

PubMed

Li, Wenting; Jiang, Zhengwu; Yang, Zhenghong

2017-05-27

The breakage of capsules upon crack propagation is crucial for achieving crack healing in encapsulation-based self-healing materials. A mesomechanical model was developed in this study to simulate the process of crack propagation in a matrix and the potential of debonding. The model used the extended finite element method (XFEM) combined with a cohesive zone model (CZM) in a two-dimensional (2D) configuration. The configuration consisted of an infinite matrix with an embedded crack and a capsule nearby, all subjected to a uniaxial remote tensile load. A parametric study was performed to investigate the effect of geometry, elastic parameters and fracture properties on the fracture response of the system. The results indicated that the effect of the capsule wall on the fracture behavior of the matrix is insignificant for t c / R c ≤ 0.05. The matrix strength influenced the ultimate crack length, while the Young's modulus ratio E c / E m only affected the rate of crack propagation. The potential for capsule breakage or debonding was dependent on the comparative strength between capsule and interface (S c /S int ), provided the crack could reach the capsule. The critical value of S c ,cr /S int,cr was obtained using this model for materials design.

Large Eddy Simulation including population dynamics model for polydisperse droplet evolution

NASA Astrophysics Data System (ADS)

Aiyer, Aditya; Yang, Di; Chamecki, Marcelo; Meneveau, Charles

2017-11-01

Previous studies have shown that dispersion patterns of oil droplets in the ocean following a deep sea oil spill depend critically on droplet diameter. Hence predicting the evolution of the droplet size distribution is of critical importance for predicting macroscopic features of dispersion in the ocean. We adopt a population dynamics model of polydisperse droplet distributions for use in LES. We generalize a breakup model from Reynolds averaging approaches to LES in which the breakup is modeled as due to bombardment of droplets by turbulent eddies of various sizes. The breakage rate is expressed as an integral of a collision frequency times a breakage efficiency over all eddy sizes. An empirical fit to the integral is proposed in order to avoid having to recalculate the integral at every LES grid point and time step. The fit is tested by comparison with various stirred tank experiments. As a flow application for LES we consider a jet of bubbles and large droplets injected at the bottom of the tank. The advected velocity and concentration fields of the drops are described using an Eulerian approach. We study the change of the oil droplet distribution due to breakup caused by interaction of turbulence with the oil droplets. This research was made possible by a Grant from the Gulf of Mexico Research Initiative.

Condom Use: Slippage, Breakage, and Steps for Proper Use among Adolescents in Alternative School Settings

ERIC Educational Resources Information Center

Coyle, Karin K.; Franks, Heather M.; Glassman, Jill R.; Stanoff, Nicole M.

2012-01-01

Background: School-based human immunodeficiency virus (HIV)/sexually transmitted infection (STI), and pregnancy prevention programs often focus on consistent and correct condom use. Research on adolescents' experience using condoms, including condom slippage/breakage, is limited. This exploratory study examines proper condom use and the…

Destabilized SMC5/6 complex leads to chromosome breakage syndrome with severe lung disease

PubMed Central

van der Crabben, Saskia N.; Hennus, Marije P.; McGregor, Grant A.; Ritter, Deborah I.; Nagamani, Sandesh C.S.; Wells, Owen S.; Harakalova, Magdalena; Chinn, Ivan K.; Alt, Aaron; Vondrova, Lucie; Hochstenbach, Ron; van Montfrans, Joris M.; Terheggen-Lagro, Suzanne W.; van Lieshout, Stef; van Roosmalen, Markus J.; Renkens, Ivo; Duran, Karen; Nijman, Isaac J.; Kloosterman, Wigard P.; Hennekam, Eric; van Hasselt, Peter M.; Wheeler, David A.; Palecek, Jan J.; Lehmann, Alan R.; Oliver, Antony W.; Pearl, Laurence H.; Plon, Sharon E.; Murray, Johanne M.

2016-01-01

The structural maintenance of chromosomes (SMC) family of proteins supports mitotic proliferation, meiosis, and DNA repair to control genomic stability. Impairments in chromosome maintenance are linked to rare chromosome breakage disorders. Here, we have identified a chromosome breakage syndrome associated with severe lung disease in early childhood. Four children from two unrelated kindreds died of severe pulmonary disease during infancy following viral pneumonia with evidence of combined T and B cell immunodeficiency. Whole exome sequencing revealed biallelic missense mutations in the NSMCE3 (also known as NDNL2) gene, which encodes a subunit of the SMC5/6 complex that is essential for DNA damage response and chromosome segregation. The NSMCE3 mutations disrupted interactions within the SMC5/6 complex, leading to destabilization of the complex. Patient cells showed chromosome rearrangements, micronuclei, sensitivity to replication stress and DNA damage, and defective homologous recombination. This work associates missense mutations in NSMCE3 with an autosomal recessive chromosome breakage syndrome that leads to defective T and B cell function and acute respiratory distress syndrome in early childhood. PMID:27427983

Breakage of internal maxillary distractor: considerable complication of maxillary distraction osteogenesis.

PubMed

Aikawa, Tomonao; Iida, Seiji; Isomura, Emiko T; Namikawa, Mari; Matsuoka, Yudai; Yamada, Chiaki; Yamamoto, Taku; Takigawa, Yoko

2008-07-01

Maxillary distraction osteogenesis using intraoral distractors is now one of the standard treatments of maxillary retrusion. This report shows 2 cases of breakage of this internal maxillary distractor in patients with cleft lip and palate; one was observed during the distraction period and the other was during the retention period. The first case required a rotational movement of the distraction segment, and this movement caused the laterally dislocation of the posterior part of the distractor, where the distractor suffered some mechanical forces by mouth opening. In the latter case, breakage of distractor was observed on the radiographs taken 3 months after distraction and this complication may have been caused by mechanical force by occlusion and mastication. Both breakages were found at the joint of the anchorage plate and the extension rod, which has some flexibility for adjusting the plate to the bone surface. Therefore, surgeons should pay special attention for this mechanical weak area in this distractor not only during the advancement period, but also during the retention period and should avoid unnecessary frequent bending for adopting the bone surface, which directly weakens the joint.

Destabilized SMC5/6 complex leads to chromosome breakage syndrome with severe lung disease.

PubMed

van der Crabben, Saskia N; Hennus, Marije P; McGregor, Grant A; Ritter, Deborah I; Nagamani, Sandesh C S; Wells, Owen S; Harakalova, Magdalena; Chinn, Ivan K; Alt, Aaron; Vondrova, Lucie; Hochstenbach, Ron; van Montfrans, Joris M; Terheggen-Lagro, Suzanne W; van Lieshout, Stef; van Roosmalen, Markus J; Renkens, Ivo; Duran, Karen; Nijman, Isaac J; Kloosterman, Wigard P; Hennekam, Eric; Orange, Jordan S; van Hasselt, Peter M; Wheeler, David A; Palecek, Jan J; Lehmann, Alan R; Oliver, Antony W; Pearl, Laurence H; Plon, Sharon E; Murray, Johanne M; van Haaften, Gijs

2016-08-01

The structural maintenance of chromosomes (SMC) family of proteins supports mitotic proliferation, meiosis, and DNA repair to control genomic stability. Impairments in chromosome maintenance are linked to rare chromosome breakage disorders. Here, we have identified a chromosome breakage syndrome associated with severe lung disease in early childhood. Four children from two unrelated kindreds died of severe pulmonary disease during infancy following viral pneumonia with evidence of combined T and B cell immunodeficiency. Whole exome sequencing revealed biallelic missense mutations in the NSMCE3 (also known as NDNL2) gene, which encodes a subunit of the SMC5/6 complex that is essential for DNA damage response and chromosome segregation. The NSMCE3 mutations disrupted interactions within the SMC5/6 complex, leading to destabilization of the complex. Patient cells showed chromosome rearrangements, micronuclei, sensitivity to replication stress and DNA damage, and defective homologous recombination. This work associates missense mutations in NSMCE3 with an autosomal recessive chromosome breakage syndrome that leads to defective T and B cell function and acute respiratory distress syndrome in early childhood.

Understanding breakage in curly hair.

PubMed

Camacho-Bragado, G A; Balooch, G; Dixon-Parks, F; Porter, C; Bryant, H

2015-07-01

In 2005, the L'Oréal Institute for hair and skin research carried out a multiethnic study to investigate hair breakage in women residing in the U.S.A. In this study it was reported that a large percentage (96%) of the African-American respondents experience breakage. A combination of structural differences and grooming-induced stresses seem to contribute to the higher breakage incidence in the African-American group as the chemical composition of African-American hair is not significantly different from other ethnic groups. Some authors have proposed that the repeated elongation, torsion and flexion actions may affect the components of the hair fibre. However, considering the different properties of cuticle and cortex, one would expect a different wearing mechanism of each, leading to the ultimate failure of hair. Knowing in detail how each part of the structure fails can potentially lead to better ways to protect the hair from physical insults. To investigate crack propagation and fracture mechanisms in African-American hair. Virgin hair of excellent quality was collected, with informed consent, from a female African-American volunteer. A series of controlled mechanical stresses was applied to 10-mm hair sections using a high-resolution mechanical stage (20 mN) up to the fracture of the fibre. The surface was monitored using scanning electron microscopy imaging during the stress application. X-ray tomographic microscopy images were acquired and quantified to detect changes in energy absorption as a function of applied stress that could be linked to increase in crack density. Analysis of the mechanical response of hair combined with the two imaging techniques led us to propose the following mechanism of hair breakage: cuticle sliding; failure of the cuticle-cortex interface; nucleation of intercellular cracks and growth of cracks at the cuticle-cortex junction; and propagation of intercellular cracks towards the surface of the hair and final breakage when these cracks merge at the cuticular junction. The combination of scanning electron microscopy and X-ray tomography provided new information about the fracture of hair. Mechanical damage from grooming and some environmental factors accumulate in hair creating internal cracks that eventually result in breakage at unpredictable sites and therefore a continuous care regimen for the hair throughout the life cycle of the fibres is recommended. © 2015 The Authors BJD © 2015 British Association of Dermatologists.

FAST TRACK COMMUNICATION: The nonlinear fragmentation equation

NASA Astrophysics Data System (ADS)

Ernst, Matthieu H.; Pagonabarraga, Ignacio

2007-04-01

We study the kinetics of nonlinear irreversible fragmentation. Here, fragmentation is induced by interactions/collisions between pairs of particles and modelled by general classes of interaction kernels, for several types of breakage models. We construct initial value and scaling solutions of the fragmentation equations, and apply the 'non-vanishing mass flux' criterion for the occurrence of shattering transitions. These properties enable us to determine the phase diagram for the occurrence of shattering states and of scaling states in the phase space of model parameters.

49 CFR 179.220-18 - Bottom outlets.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-shaped breakage groove shall be cut (not cast) in the upper part of the outlet nozzle at a point... nozzle extends below the bottom of the outer shell, a V-shaped breakage groove shall be cut (not cast) in... projection of the bottom outlet equipment may not be more than that allowed by appendix E of the AAR...

Fire, ice, and metabolism

Treesearch

Kevin T. Smith

2015-01-01

Evaluation of tree injury often begins with a loss assessment. For winter storm injury, percent crow loss or branch breakage is often estimated. For injury from fire or some mechanical source to the lower trunk, the height and width of the killed vascular cambium and resulting scar are often measured. Both crown breakage and stem wounds provide the opportunity for...

Rice fissure resistance QTLs from ‘Saber’ complement those from ‘Cypress’

USDA-ARS?s Scientific Manuscript database

The economic value of broken rice is about half that of whole milled rice, so one goal of producers, millers, and rice breeders is to reduce grain breakage during the dehusking and milling processes. One of the primary causes of rice breakage is fissuring, or cracking, of the rice before it enters ...

Novel QTLs affecting rice kernel fissure resistance discovered in the cultivar ‘Saber’ augment those from ‘Cybonnet’

USDA-ARS?s Scientific Manuscript database

Kernel fissures in rice (Oryza sativa L.) caused by pre- or post-harvest stresses are the leading cause of breakage among milled rice. Such breakage causes economic losses for producers, millers, and marketers. Five QTLs for kernel fissure resistance (FR) were identified among a set of 275 RILs de...

Hair Breakage in Patients of African Descent: Role of Dermoscopy

PubMed Central

Quaresma, Maria Victória; Martinez Velasco, María Abril; Tosti, Antonella

2015-01-01

Dermoscopy represents a useful technique for the diagnosis and follow-up of hair and scalp disorders. To date, little has been published regarding dermoscopy findings of hair disorders in patients of African descent. This article illustrates how dermoscopy allows fast diagnosis of hair breakage due to intrinsic factors and chemical damage in African descent patients. PMID:27170942

A discrete element method-based approach to predict the breakage of coal

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

Gupta, Varun; Sun, Xin; Xu, Wei

Pulverization is an essential pre-combustion technique employed for solid fuels, such as coal, to reduce particle sizes. Smaller particles ensure rapid and complete combustion, leading to low carbon emissions. Traditionally, the resulting particle size distributions from pulverizers have been informed by empirical or semi-empirical approaches that rely on extensive data gathered over several decades during operations or experiments. However, the predictive capabilities for new coals and processes are limited. This work presents a Discrete Element Method based computational framework to predict particle size distribution resulting from the breakage of coal particles characterized by the coal’s physical properties. The effect ofmore » certain operating parameters on the breakage behavior of coal particles also is examined.« less

75 FR 47190 - Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-135...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-05

... kind. EMBRAER also states that the rod breakage has not been shown to cause leakage of APU oil in the gearbox, or leakage of the fuel lines in the compartment. EMBRAER states both ignition sources and... detector becomes inoperative. EMBRAER also states that in the event of fire detection failure, [[Page 47191...

A model for wave control on coral breakage and species distribution in the Hawaiian Islands

USGS Publications Warehouse

Storlazzi, C.D.; Brown, E.K.; Field, M.E.; Rodgers, K.; Jokiel, P.L.

2005-01-01

The fringing reef off southern Molokai, Hawaii, is currently being studied as part of a multi-disciplinary project led by the US Geological Survey. As part of this study, modeling and field observations were utilized to help understand the physical controls on reef morphology and the distribution of different coral species. A model was developed that calculates wave-induced hydrodynamic forces on corals of a specific form and mechanical strength. From these calculations, the wave conditions under which specific species of corals would either be stable or would break due to the imposed wave-induced forces were determined. By combining this hydrodynamic force-balance model with various wave model output for different oceanographic conditions experienced in the study area, we were able to map the locations where specific coral species should be stable (not subject to frequent breakage) in the study area. The combined model output was then compared with data on coral species distribution and coral cover at 12 sites along Molokai's south shore. Observations and modeling suggest that the transition from one coral species to another may occur when the ratio of the coral colony's mechanical strengths to the applied (wave-induced) forces may be as great as 5:1, and not less than 1:1 when corals would break. This implies that coral colony's mechanical strength and wave-induced forces may be important in defining gross coral community structure over large (orders of 10's of meters) spatial scales. ?? Springer-Verlag 2004.

Role of DNA secondary structures in fragile site breakage along human chromosome 10

PubMed Central

Dillon, Laura W.; Pierce, Levi C. T.; Ng, Maggie C. Y.; Wang, Yuh-Hwa

2013-01-01

The formation of alternative DNA secondary structures can result in DNA breakage leading to cancer and other diseases. Chromosomal fragile sites, which are regions of the genome that exhibit chromosomal breakage under conditions of mild replication stress, are predicted to form stable DNA secondary structures. DNA breakage at fragile sites is associated with regions that are deleted, amplified or rearranged in cancer. Despite the correlation, unbiased examination of the ability to form secondary structures has not been evaluated in fragile sites. Here, using the Mfold program, we predict potential DNA secondary structure formation on the human chromosome 10 sequence, and utilize this analysis to compare fragile and non-fragile DNA. We found that aphidicolin (APH)-induced common fragile sites contain more sequence segments with potential high secondary structure-forming ability, and these segments clustered more densely than those in non-fragile DNA. Additionally, using a threshold of secondary structure-forming ability, we refined legitimate fragile sites within the cytogenetically defined boundaries, and identified potential fragile regions within non-fragile DNA. In vitro detection of alternative DNA structure formation and a DNA breakage cell assay were used to validate the computational predictions. Many of the regions identified by our analysis coincide with genes mutated in various diseases and regions of copy number alteration in cancer. This study supports the role of DNA secondary structures in common fragile site instability, provides a systematic method for their identification and suggests a mechanism by which DNA secondary structures can lead to human disease. PMID:23297364

Snow breakage in a pole-sized ponderosa pine plantation ... more damage at high stand-densities

Treesearch

Robert F. Powers; William W. Oliver

1970-01-01

Damage by snow breakage to pole-sized ponderosa pine (Pinus pondvosa Laws.) increased as stand density increased. In a plantation on the west slope of California's Sierra Nevada, the tallest trees were most often broken. Thinning in the sapling stage is recommended as a preventative measure in dense plantations subject to heavy snowfall.

Trapping and breaking of in vivo nicked DNA during pulsed-field gel electrophoresis

PubMed Central

Khan, Sharik R.; Kuzminov, Andrei

2013-01-01

Pulsed field gel electrophoresis (PFGE) offers a high-resolution approach to quantify chromosomal fragmentation in bacteria, measured as percent of chromosomal DNA entering the gel. The degree of separation in PFG depends upon the size of DNA, as well as various conditions of electrophoresis, such as electric field strength (FS), time of electrophoresis, switch time and buffer composition. Here we describe a new parameter, the structural integrity of the sample DNA itself, that influences its migration through PFGs. We show that sub-chromosomal fragments containing both spontaneous and DNA damage-induced nicks are prone to breakage during PFGE. Such breakage at single strand interruptions results in artefactual decrease in molecular weight of linear DNA making accurate determination of the number of double strand breaks difficult. While breakage of nicked sub-chromosomal fragments is FS-independent, some high molecular weight sub-chromosomal fragments are also trapped within wells under the standard PFGE conditions. This trapping can be minimized by lowering the field strength and increasing the time of electrophoresis. We discuss how breakage of nicked DNA may be mechanistically linked to trapping. Our results suggest how to optimize conditions for PFGE when quantifying chromosomal fragmentation induced by DNA damage. PMID:23770235

Condom use among female commercial sex workers in Nevada's legal brothels.

PubMed Central

Albert, A E; Warner, D L; Hatcher, R A; Trussell, J; Bennett, C

1995-01-01

OBJECTIVES. The purpose of this study was to evaluate condom use and the incidence of breakage and slippage during vaginal intercourse among female prostitutes in legal Nevada brothels, where use of condoms is required by law. METHODS. Forty-one licensed prostitutes in three brothels were enrolled in a prospective trial in August 1993. Used condoms were collected to verify reported breaks visually. Retrospective breakage and slippage rates were obtained in a standardized interview. RESULTS. Condoms were used for every act of vaginal intercourse with a brothel client during the study period, as well as in the previous year. In the prospective study phase, condoms were used in 353 acts of vaginal intercourse with clients. No condoms broke, and none fell off the penis during intercourse. Only twice (0.6%) did condoms completely fall off during withdrawal. Twelve times (3.4%) during intercourse and 15 times (4.3%) during withdrawal, condoms slipped down the penis but did not fall off. CONCLUSIONS. These findings, among the lowest breakage and slippage rates published, suggest that regular condom use may lead to condom mastery and the development of techniques to reduce the likelihood of breakage and slippage. PMID:7485663

Micro-Macro Analysis and Phenomenological Modelling of Salt Viscous Damage and Application to Salt Caverns

NASA Astrophysics Data System (ADS)

Zhu, Cheng; Pouya, Ahmad; Arson, Chloé

2015-11-01

This paper aims to gain fundamental understanding of the microscopic mechanisms that control the transition between secondary and tertiary creep around salt caverns in typical geological storage conditions. We use a self-consistent inclusion-matrix model to homogenize the viscoplastic deformation of halite polycrystals and predict the number of broken grains in a Representative Elementary Volume of salt. We use this micro-macro modeling framework to simulate creep tests under various axial stresses, which gives us the critical viscoplastic strain at which grain breakage (i.e., tertiary creep) is expected to occur. The comparison of simulation results for short-term and long-term creep indicates that the initiation of tertiary creep depends on the stress and the viscoplastic strain. We use the critical viscoplastic deformation as a yield criterion to control the transition between secondary and tertiary creep in a phenomenological viscoplastic model, which we implement into the Finite Element Method program POROFIS. We model a 850-m-deep salt cavern of irregular shape, in axis-symmetric conditions. Simulations of cavern depressurization indicate that a strain-dependent damage evolution law is more suitable than a stress-dependent damage evolution law, because it avoids high damage concentrations and allows capturing the formation of a damaged zone around the cavity. The modeling framework explained in this paper is expected to provide new insights to link grain breakage to phenomenological damage variables used in Continuum Damage Mechanics.

Microrheology of highly crosslinked microtubule networks is dominated by force-induced crosslinker unbinding

PubMed Central

Yang, Yali; Bai, Mo; Klug, William S.; Levine, Alex J.

2012-01-01

We determine the time- and force-dependent viscoelastic responses of reconstituted networks of microtubules that have been strongly crosslinked by biotin-streptavidin bonds. To measure the microscale viscoelasticity of such networks, we use a magnetic tweezers device to apply localized forces. At short time scales, the networks respond nonlinearly to applied force, with stiffening at small forces, followed by a reduction in the stiffening response at high forces, which we attribute to the force-induced unbinding of crosslinks. At long time scales, force-induced bond unbinding leads to local network rearrangement and significant bead creep. Interestingly, the network retains its elastic modulus even under conditions of significant plastic flow, suggesting that crosslinker breakage is balanced by the formation of new bonds. To better understand this effect, we developed a finite element model of such a stiff filament network with labile crosslinkers obeying force-dependent Bell model unbinding dynamics. The coexistence of dissipation, due to bond breakage, and the elastic recovery of the network is possible because each filament has many crosslinkers. Recovery can occur as long as a sufficient number of the original crosslinkers are preserved under the loading period. When these remaining original crosslinkers are broken, plastic flow results. PMID:23577042

Role of Fanconi Anemia FANCG in Preventing Double-Strand Breakage and Chromosomal Rearrangement during DNA Replication

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

Tebbs, R S; Hinz, J M; Yamada, N A

The Fanconi anemia (FA) proteins overlap with those of homologous recombination through FANCD1/BRCA2, but the biochemical functions of other FA proteins are unknown. By constructing and characterizing a null fancg mutant of hamster CHO cells, we present several new insights for FA. The fancg cells show a broad sensitivity to genotoxic agents, not supporting the conventional concept of sensitivity to only DNA crosslinking agents. The aprt mutation rate is normal, but hprt mutations are reduced, which we ascribe to the lethality of large deletions. CAD and dhfr gene amplification rates are increased, implying excess chromosomal breakage during DNA replication, andmore » suggesting amplification as a contributing factor to cancer-proneness in FA patients. In S-phase cells, both spontaneous and mutagen-induced Rad51 nuclear foci are elevated. These results support a model in which FancG protein helps to prevent collapse of replication forks by allowing translesion synthesis or lesion bypass through homologous recombination.« less

Controlled manipulation of flexible carbon nanotubes through shape-dependent pushing by atomic force microscopy.

PubMed

Yang, Seung-Cheol; Qian, Xiaoping

2013-09-17

A systematic approach to manipulating flexible carbon nanotubes (CNTs) has been developed on the basis of atomic force microscope (AFM) based pushing. Pushing CNTs enables efficient transport and precise location of individual CNTs. A key issue for pushing CNTs is preventing defective distortion in repetitive bending and unbending deformation. The approach presented here controls lateral movement of an AFM tip to bend CNTs without permanent distortion. The approach investigates possible defects caused by tensile strain of the outer tube under uniform bending and radial distortion by kinking. Using the continuum beam model and experimental bending tests, dependency of maximum bending strain on the length of bent CNTs and radial distortion on bending angles at a bent point have been demonstrated. Individual CNTs are manipulated by limiting the length of bent CNTs and the bending angle. In our approach, multiwalled CNTs with 5-15 nm diameter subjected to bending deformation produce no outer tube breakage under uniform bending and reversible radial deformation with bending angles less than 110°. The lateral tip movement is determined by a simple geometric model that relies on the shape of multiwalled CNTs. The model effectively controls deforming CNT length and bending angle for given CNT shape. Experimental results demonstrate successful manipulation of randomly dispersed CNTs without visual defects. This approach to pushing can be extended to develop a wide range of CNT based nanodevice applications.

Square-lashing technique in segmental spinal instrumentation: a biomechanical study.

PubMed

Arlet, Vincent; Draxinger, Kevin; Beckman, Lorne; Steffen, Thomas

2006-07-01

Sublaminar wires have been used for many years for segmental spinal instrumentation in scoliosis surgery. More recently, stainless steel wires have been replaced by titanium cables. However, in rigid scoliotic curves, sublaminar wires or simple cables can either brake or pull out. The square-lashing technique was devised to avoid complications such as cable breakage or lamina cutout. The purpose of the study was therefore to test biomechanically the pull out and failure mode of simple sublaminar constructs versus the square-lashing technique. Individual vertebrae were subjected to pullout testing having one of two different constructs (single loop and square lashing) using either monofilament wire or multifilament cables. Four different methods of fixation were therefore tested: single wire construct, square-lashing wiring construct, single cable construct, and square-lashing cable construct. Ultimate failure load and failure mechanism were recorded. For the single wire the construct failed 12/16 times by wire breakage with an average ultimate failure load of 793 N. For the square-lashing wire the construct failed with pedicle fracture in 14/16, one bilateral lamina fracture, and one wire breakage. Ultimate failure load average was 1,239 N For the single cable the construct failed 12/16 times due to cable breakage (average force 1,162 N). 10/12 of these breakages were where the cable looped over the rod. For the square-lashing cable all of these constructs (16/16) failed by fracture of the pedicle with an average ultimate failure load of 1,388 N. The square-lashing construct had a higher pullout strength than the single loop and almost no cutting out from the lamina. The square-lashing technique with cables may therefore represent a new advance in segmental spinal instrumentation.

Online breakage detection of multitooth tools using classifier ensembles for imbalanced data

NASA Astrophysics Data System (ADS)

Bustillo, Andrés; Rodríguez, Juan J.

2014-12-01

Cutting tool breakage detection is an important task, due to its economic impact on mass production lines in the automobile industry. This task presents a central limitation: real data-sets are extremely imbalanced because breakage occurs in very few cases compared with normal operation of the cutting process. In this paper, we present an analysis of different data-mining techniques applied to the detection of insert breakage in multitooth tools. The analysis applies only one experimental variable: the electrical power consumption of the tool drive. This restriction profiles real industrial conditions more accurately than other physical variables, such as acoustic or vibration signals, which are not so easily measured. Many efforts have been made to design a method that is able to identify breakages with a high degree of reliability within a short period of time. The solution is based on classifier ensembles for imbalanced data-sets. Classifier ensembles are combinations of classifiers, which in many situations are more accurate than individual classifiers. Six different base classifiers are tested: Decision Trees, Rules, Naïve Bayes, Nearest Neighbour, Multilayer Perceptrons and Logistic Regression. Three different balancing strategies are tested with each of the classifier ensembles and compared to their performance with the original data-set: Synthetic Minority Over-Sampling Technique (SMOTE), undersampling and a combination of SMOTE and undersampling. To identify the most suitable data-mining solution, Receiver Operating Characteristics (ROC) graph and Recall-precision graph are generated and discussed. The performance of logistic regression ensembles on the balanced data-set using the combination of SMOTE and undersampling turned out to be the most suitable technique. Finally a comparison using industrial performance measures is presented, which concludes that this technique is also more suited to this industrial problem than the other techniques presented in the bibliography.

Diagnosis of Fanconi Anemia: Chromosomal Breakage Analysis

PubMed Central

Oostra, Anneke B.; Nieuwint, Aggie W. M.; Joenje, Hans; de Winter, Johan P.

2012-01-01

Fanconi anemia (FA) is a rare inherited syndrome with diverse clinical symptoms including developmental defects, short stature, bone marrow failure, and a high risk of malignancies. Fifteen genetic subtypes have been distinguished so far. The mode of inheritance for all subtypes is autosomal recessive, except for FA-B, which is X-linked. Cells derived from FA patients are—by definition—hypersensitive to DNA cross-linking agents, such as mitomycin C, diepoxybutane, or cisplatinum, which becomes manifest as excessive growth inhibition, cell cycle arrest, and chromosomal breakage upon cellular exposure to these drugs. Here we provide a detailed laboratory protocol for the accurate assessment of the FA diagnosis as based on mitomycin C-induced chromosomal breakage analysis in whole-blood cultures. The method also enables a quantitative estimate of the degree of mosaicism in the lymphocyte compartment of the patient. PMID:22693659

Fanconi anemia in brothers initially diagnosed with VACTERL association with hydrocephalus, and subsequently with Baller-Gerold syndrome

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

Rossbach, H.C.; Granan, N.H.; Rossi, A.R.

1996-01-02

Two brothers with presumed Baller-Gerold syndrome, one of whom was previously diagnosed with the association of vertebral, cardiac, renal, limb anomalies, anal atresia, tracheo-esophageal fistula (VACTERL) association with hydrocephalus, were evaluated for chromosome breakage because of severe thrombo cytopenia in one of them. Spontaneous and clastogen-induced breakage was markedly increased in both patients as compared to control individuals. Clinical manifestations and chromosome breakage, consistent with Fanconi anemia, in patients with a prior diagnosis of either Baller-Gerold syndrome, reported earlier in one other patient, or with VACTERL association with hydrocephalus, recently reported in 3 patients, underline the clinical heterogeneity of Fanconimore » anemia and raise the question of whether these syndromes are distinct disorders or phenotypic variations of the same disease. 12 refs., 3 figs., 1 tab.« less

Feasible Recycling of Industrial Waste Coal Gangue for Preparation of Mullite Based Ceramic Proppant

NASA Astrophysics Data System (ADS)

Li, Guomin; Ma, Haiqiang; Tian, Yuming; Wang, Kaiyue; Zhou, Yi; Wu, Yaqiao; Zou, Xinwei; Hao, Jianying; Bai, Pinbo

2017-09-01

Industrial waste coal gangue was successfully utilized to prepare the mullite-based ceramic proppants. The experiments involved the pelletizing technology of proppant through intensive mixer and following the sintering process under different temperatures. The crystalline phase, microstructure, density and breakage ratio of the proppants were investigated. The results showed that with the increasing of sintering temperature, the crystalline phases were transformed to rod-like mullite, which formed the cross-linked structure, improving the densification of proppants. Consequently, the breakage ratio under the closure pressure of 35 MPa exhibited declining trend and reached the minimum value of 6.8% at 1450 °C. Owing to the easy preparation, feasible design, low cost and moderate breakage ratio, the mullite-based ceramic proppant prepared by coal gangue and bauxite is promising candidate for fracturing proppants in future applications.

Investigating the Mechanisms and Potential of Silk Fiber Metallization

DTIC Science & Technology

2013-09-30

in an ALD process, when using the modified metal infiltration process as outlined by Lee et al., the titanium isopropoxide (TIP) precursor...these fibers exhibited >2-fold increase in strain to breakage, and >4.5-fold increase in strength when infiltrated with zinc, titanium , or aluminum...fibers exhibited >2-fold increase in strain to breakage, and >4.5-fold increase in strength when infiltrated with zinc, titanium , or aluminum

On-line tool breakage monitoring of vibration tapping using spindle motor current

NASA Astrophysics Data System (ADS)

Li, Guangjun; Lu, Huimin; Liu, Gang

2008-10-01

Input current of driving motor has been employed successfully as monitoring the cutting state in manufacturing processes for more than a decade. In vibration tapping, however, the method of on-line monitoring motor electric current has not been reported. In this paper, a tap failure prediction method is proposed to monitor the vibration tapping process using the electrical current signal of the spindle motor. The process of vibration tapping is firstly described. Then the relationship between the torque of vibration tapping and the electric current of motor is investigated by theoretic deducing and experimental measurement. According to those results, a monitoring method of tool's breakage is proposed through monitoring the ratio of the current amplitudes during adjacent vibration tapping periods. Finally, a low frequency vibration tapping system with motor current monitoring is built up using a servo motor B-106B and its driver CR06. The proposed method has been demonstrated with experiment data of vibration tapping in titanic alloys. The result of experiments shows that the method, which can avoid the tool breakage and giving a few error alarms when the threshold of amplitude ratio is 1.2 and there is at least 2 times overrun among 50 adjacent periods, is feasible for tool breakage monitoring in the process of vibration tapping small thread holes.

Hair breakage as a presenting sign of early or occult central centrifugal cicatricial alopecia: clinicopathologic findings in 9 patients.

PubMed

Callender, Valerie D; Wright, Dakara Rucker; Davis, Erica C; Sperling, Leonard C

2012-09-01

Central centrifugal cicatricial alopecia is the most common form of cicatricial alopecia in African American women. Treatment options are limited and mostly aimed at halting further hair loss but rarely result in hair regrowth. Therefore, it is important to recognize early clinical signs, perform a confirmatory biopsy, and begin treatment promptly. We have observed that hair breakage may be a key sign of early central centrifugal cicatricial alopecia, and this association is not clearly described in the literature. Nine patients with hair breakage on the vertex with or without scalp symptoms underwent scalp biopsies as part of their evaluation. Of these, 8 had histologic samples adequate for complete interpretation: 5 specimens (63%) showed histologic changes typical of central centrifugal cicatricial alopecia, with 1 of these showing advanced end-stage changes of cicatricial alopecia. Two (25%) revealed premature desquamation of the inner root sheath as the sole finding suggestive of early central centrifugal cicatricial alopecia and 1 (13%) was normal. Although hair breakage can have multiple causes, early central centrifugal cicatricial alopecia must be considered in the differential diagnosis, particularly in women of African ancestry. Histologic evaluation may reveal early or late findings that can help establish the diagnosis.

Duration of an intense laser pulse can determine the breakage of multiple chemical bonds

PubMed Central

Xie, Xinhua; Lötstedt, Erik; Roither, Stefan; Schöffler, Markus; Kartashov, Daniil; Midorikawa, Katsumi; Baltuška, Andrius; Yamanouchi, Kaoru; Kitzler, Markus

2015-01-01

Control over the breakage of a certain chemical bond in a molecule by an ultrashort laser pulse has been considered for decades. With the availability of intense non-resonant laser fields it became possible to pre-determine femtosecond to picosecond molecular bond breakage dynamics by controlled distortions of the electronic molecular system on sub-femtosecond time scales using field-sensitive processes such as strong-field ionization or excitation. So far, all successful demonstrations in this area considered only fragmentation reactions, where only one bond is broken and the molecule is split into merely two moieties. Here, using ethylene (C2H4) as an example, we experimentally investigate whether complex fragmentation reactions that involve the breakage of more than one chemical bond can be influenced by parameters of an ultrashort intense laser pulse. We show that the dynamics of removing three electrons by strong-field ionization determines the ratio of fragmentation of the molecular trication into two respectively three moieties. We observe a relative increase of two-body fragmentations with the laser pulse duration by almost an order of magnitude. Supported by quantum chemical simulations we explain our experimental results by the interplay between the dynamics of electron removal and nuclear motion. PMID:26271602

Safety and acceptability of a baggy latex condom.

PubMed

Macaluso, M; Blackwell, R; Carr, B; Meinzen-Derr, J; Montgomery, M; Roark, M; Lynch, M; Stringer, E M

2000-03-01

A total of 104 couples participated in a randomized crossover trial to compare a new baggy condom with a straight-shaft condom produced by the same manufacturer. Participants completed a coital log after using each condom. All couples used five condoms of each type. Among 102 couples who did not report major deviations from the protocol, the breakage rate was eight of 510 (1.6%) for the baggy condom, and six of 510 (1.2%) for the standard condom (rate difference, RD = 0. 4%, 95% confidence interval of the RD, CI = -1.0%; +1.8%). Slippage was reported in 50 baggy condom logs and in 58 standard condom logs; the slippage rate was 50 of 510 (9.8%) for the baggy condom, and 58 of 510 (11.4%) for the standard condom (RD = -1.6%, 95% CI = -5.4%; +2.2%). Slippage was most often partial (<1 inch) and may not indicate condom failure. Severe slippage rates were 11 of 510 (2.2%) for the baggy condom, and 18 of 510 (3.5%) for the standard condom (RD = -1.4%, 95% CI = -3.4%; +0.7%). The findings support the conclusion that the two condoms are equivalent with respect to breakage and slippage. The participants appeared to prefer the baggy condom, suggesting that the new product may be more acceptable to the public than the traditional straight-shaft condoms, and may be easier to use consistently over long time periods.

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

Shin, J; Park, S; Jeong, J

Purpose: In particle therapy and radiobiology, the investigation of mechanisms leading to the death of target cancer cells induced by ionising radiation is an active field of research. Recently, several studies based on Monte Carlo simulation codes have been initiated in order to simulate physical interactions of ionising particles at cellular scale and in DNA. Geant4-DNA is the one of them; it is an extension of the general purpose Geant4 Monte Carlo simulation toolkit for the simulation of physical interactions at sub-micrometre scale. In this study, we present Geant4-DNA Monte Carlo simulations for the prediction of DNA strand breakage usingmore » a geometrical modelling of DNA structure. Methods: For the simulation of DNA strand breakage, we developed a specific DNA geometrical structure. This structure consists of DNA components, such as the deoxynucleotide pairs, the DNA double helix, the nucleosomes and the chromatin fibre. Each component is made of water because the cross sections models currently available in Geant4-DNA for protons apply to liquid water only. Also, at the macroscopic-scale, protons were generated with various energies available for proton therapy at the National Cancer Center, obtained using validated proton beam simulations developed in previous studies. These multi-scale simulations were combined for the validation of Geant4-DNA in radiobiology. Results: In the double helix structure, the deposited energy in a strand allowed to determine direct DNA damage from physical interaction. In other words, the amount of dose and frequency of damage in microscopic geometries was related to direct radiobiological effect. Conclusion: In this report, we calculated the frequency of DNA strand breakage using Geant4- DNA physics processes for liquid water. This study is now on-going in order to develop geometries which use realistic DNA material, instead of liquid water. This will be tested as soon as cross sections for DNA material become available in Geant4-DNA.« less

Multiscale Phenomena in the Solid-Liquid Transition State of a Granular Material: Analysis, Modeling and Experimentation

DTIC Science & Technology

2010-11-21

The number of undergraduates funded by your agreement who graduated during this period and will receive scholarships or fellowships for further... geology and engineering – to understand and predict the multiscale behaviour of granular materials. Several pioneering achievements have led to...breakage. Purpose of the Research We have recently established, in close collaboration with experimentalists (from geology , physics

The National Shipbuilding Research Program: Solid Waste Segregation and Recycling

DTIC Science & Technology

1998-03-01

Shields , Recycling Coordinator D.C. Department of Public Works 65 K Street, NE Washington, DC 20002 202-727-5887 Task Three, Tab Three Page 42 George...SHEAR X FRONT END LOADERS = CONVEYORS X FORKLIFTS O WEIGHT SCALES X PROCESSING DROP-BALL BREAKAGE X CUTTING TORCHES GAS = PLASMA = POWDER = WATER-JET...Loaders Conveyors Forklifts Weight Scales Processing Drop-ball Breakage Cutting Torches Gas Plasma Powder Laser Water-jet Abrasive disk Shears Ferrous

Decalcification of benthic foraminifera due to "Hebei Spirit" oil spill, Korea.

PubMed

Lee, Yeon Gyu; Kim, Shin; Jeong, Da Un; Lee, Jung Sick; Woo, Han Jun; Park, Min Woo; Kim, Byeong Hak; Son, Maeng Hyun; Choi, Yang Ho

2014-10-15

In order to determine the effects on foraminifera due to spilled crude oil in the "Herbei Spirit" incident, a study of benthic foraminiferal assemblages was carried out on sediment samples collected from the Sogeunri tidal flat, Taean Peninsula, Korea. Breakages of the chambers in the Ammonia beccarii and Elphidium subincertum species of the Sogeunri tidal flat with a low pH (6.98 on average) were marked. These chamber breakages occurred in 71.6% of A. beccarii and are thought to be caused by decalcification due to the fall in pH resulting from the "Hebei Spirit" oil spill. The factors that affect breakage of the chamber in benthic foraminifera under low pH condition may be not only deto decalcification but also to exposure duration of substrata in the tidal flat spilled crude oil. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Role of Fragile Sites in Sporadic Papillary Thyroid Carcinoma

PubMed Central

Dillon, Laura W.; Lehman, Christine E.; Wang, Yuh-Hwa

2012-01-01

The incidence of thyroid cancer is increasing, especially papillary thyroid carcinoma (PTC), making it currently the fastest-growing cancer among women. Reasons for this increase remain unclear, but several risk factors including radiation exposure and improved detection techniques have been suggested. Recently, the induction of chromosomal fragile site breakage was found to result in the formation of RET/PTC1 rearrangements, a common cause of PTC. Chromosomal fragile sites are regions of the genome with a high susceptibility to forming DNA breaks and are often associated with cancer. Exposure to a variety of external agents can induce fragile site breakage, which may account for some of the observed increase in PTC. This paper discusses the role of fragile site breakage in PTC development, external fragile site-inducing agents that may be potential risk factors for PTC, and how these factors are especially targeting women. PMID:22762011

Helicopter rotor blade frequency evolution with damage growth and signal processing

NASA Astrophysics Data System (ADS)

Roy, Niranjan; Ganguli, Ranjan

2005-05-01

Structural damage in materials evolves over time due to growth of fatigue cracks in homogenous materials and a complicated process of matrix cracking, delamination, fiber breakage and fiber matrix debonding in composite materials. In this study, a finite element model of the helicopter rotor blade is used to analyze the effect of damage growth on the modal frequencies in a qualitative manner. Phenomenological models of material degradation for homogenous and composite materials are used. Results show that damage can be detected by monitoring changes in lower as well as higher mode flap (out-of-plane bending), lag (in-plane bending) and torsion rotating frequencies, especially for composite materials where the onset of the last stage of damage of fiber breakage is most critical. Curve fits are also proposed for mathematical modeling of the relationship between rotating frequencies and cycles. Finally, since operational data are noisy and also contaminated with outliers, denoising algorithms based on recursive median filters and radial basis function neural networks and wavelets are studied and compared with a moving average filter using simulated data for improved health-monitoring application. A novel recursive median filter is designed using integer programming through genetic algorithm and is found to have comparable performance to neural networks with much less complexity and is better than wavelet denoising for outlier removal. This filter is proposed as a tool for denoising time series of damage indicators.

Computational prediction of the refinement of oxide agglomerates in a physical conditioning process for molten aluminium alloy

NASA Astrophysics Data System (ADS)

Tong, M.; Jagarlapudi, S. C.; Patel, J. B.; Stone, I. C.; Fan, Z.; Browne, D. J.

2015-06-01

Physically conditioning molten scrap aluminium alloys using high shear processing (HSP) was recently found to be a promising technology for purification of contaminated alloys. HSP refines the solid oxide agglomerates in molten alloys, so that they can act as sites for the nucleation of Fe-rich intermetallic phases which can subsequently be removed by the downstream de-drossing process. In this paper, a computational modelling for predicting the evolution of size of oxide clusters during HSP is presented. We used CFD to predict the macroscopic flow features of the melt, and the resultant field predictions of temperature and melt shear rate were transferred to a population balance model (PBM) as its key inputs. The PBM is a macroscopic model that formulates the microscopic agglomeration and breakage of a population of a dispersed phase. Although it has been widely used to study conventional deoxidation of liquid metal, this is the first time that PBM has been used to simulate the melt conditioning process within a rotor/stator HSP device. We employed a method which discretizes the continuous profile of size of the dispersed phase into a collection of discrete bins of size, to solve the governing population balance equation for the size of agglomerates. A finite volume method was used to solve the continuity equation, the energy equation and the momentum equation. The overall computation was implemented mainly using the FLUENT module of ANSYS. The simulations showed that there is a relatively high melt shear rate between the stator and sweeping tips of the rotor blades. This high shear rate leads directly to significant fragmentation of the initially large oxide aggregates. Because the process of agglomeration is significantly slower than the breakage processes at the beginning of HSP, the mean size of oxide clusters decreases very rapidly. As the process of agglomeration gradually balances the process of breakage, the mean size of oxide clusters converges to a steady value. The model enables formulation of the quantitative relationship between the macroscopic flow features of liquid metal and the change of size of dispersed oxide clusters, during HSP. It predicted the variation in size of the dispersed phased with operational parameters (including the geometry and, particularly, the speed of the rotor), which is of direct use to experimentalists optimising the design of the HSP device and its implementation.

An increase in pectin methyl esterase activity accompanies dormancy breakage and germination of yellow cedar seeds.

PubMed

Ren, C; Kermode, A R

2000-09-01

Pectin methyl esterase (PME) (EC 3.1.1.11) catalyzes the hydrolysis of methylester groups of cell wall pectins. We investigated the role of this enzyme in dormancy termination and germination of yellow cedar (Chamaecyparis nootkatensis [D. Don] Spach) seeds. PME activity was not detected in dormant seeds of yellow cedar but was induced and gradually increased during moist chilling; high activity coincided with dormancy breakage and germination. PME activity was positively correlated to the degree of dormancy breakage of yellow cedar seeds. The enzyme produced in different seed parts and in seeds at different times during moist chilling, germination, and early post-germinative growth consisted of two isoforms, both basic with isoelectric points of 8.7 and 8.9 and the same molecular mass of 62 kD. The pH optimum for the enzyme was between 7.4 and 8.4. In intact yellow cedar seeds, activities of the two basic isoforms of PME that were induced in embryos and in megagametophytes following dormancy breakage were significantly suppressed by abscisic acid. Gibberellic acid had a stimulatory effect on the activities of these isoforms in embryos and megagametophytes of intact seeds at the germinative stage. We hypothesize that PME plays a role in weakening of the megagametophyte, allowing radicle emergence and the completion of germination.

Timely Endocytosis of Cytokinetic Enzymes Prevents Premature Spindle Breakage during Mitotic Exit

PubMed Central

Onishi, Masayuki; Yeong, Foong May

2016-01-01

Cytokinesis requires the spatio-temporal coordination of membrane deposition and primary septum (PS) formation at the division site to drive acto-myosin ring (AMR) constriction. It has been demonstrated that AMR constriction invariably occurs only after the mitotic spindle disassembly. It has also been established that Chitin Synthase II (Chs2p) neck localization precedes mitotic spindle disassembly during mitotic exit. As AMR constriction depends upon PS formation, the question arises as to how chitin deposition is regulated so as to prevent premature AMR constriction and mitotic spindle breakage. In this study, we propose that cells regulate the coordination between spindle disassembly and AMR constriction via timely endocytosis of cytokinetic enzymes, Chs2p, Chs3p, and Fks1p. Inhibition of endocytosis leads to over accumulation of cytokinetic enzymes during mitotic exit, which accelerates the constriction of the AMR, and causes spindle breakage that eventually could contribute to monopolar spindle formation in the subsequent round of cell division. Intriguingly, the mitotic spindle breakage observed in endocytosis mutants can be rescued either by deleting or inhibiting the activities of, CHS2, CHS3 and FKS1, which are involved in septum formation. The findings from our study highlight the importance of timely endocytosis of cytokinetic enzymes at the division site in safeguarding mitotic spindle integrity during mitotic exit. PMID:27447488

Analysis of In-Flight Collision Process During V-Type Firing Pattern in Surface Blasting Using Simple Physics

NASA Astrophysics Data System (ADS)

Chouhan, Lalit Singh; Raina, Avtar K.

2015-10-01

Blasting is a unit operation in Mine-Mill Fragmentation System (MMFS) and plays a vital role in mining cost. One of the goals of MMFS is to achieve optimum fragment size at minimal cost. Blast fragmentation optimization is known to result in better explosive energy utilization. Fragmentation depends on the rock, explosive and blast design variables. If burden, spacing and type of explosive used in a mine are kept constant, the firing sequence of blast-holes plays a vital role in rock fragmentation. To obtain smaller fragmentation size, mining professionals and relevant publications recommend V- or extended V-pattern of firing sequence. In doing so, it is assumed that the in-flight air collision breaks larger rock fragments into smaller ones, thus aiding further fragmentation. There is very little support to the phenomenon of breakage during in-flight collision of fragments during blasting in published literature. In order to assess the breakage of in-flight fragments due to collision, a mathematical simulation was carried over using basic principles of physics. The calculations revealed that the collision breakage is dependent on velocity of fragments, mass of fragments, the strength of the rock and the area of fragments over which collision takes place. For higher strength rocks, the in-flight collision breakage is very difficult to achieve. This leads to the conclusion that the concept demands an in-depth investigation and validation.

A microhydrodynamic rationale for selection of bead size in preparation of drug nanosuspensions via wet stirred media milling.

PubMed

Li, Meng; Alvarez, Paulina; Bilgili, Ecevit

2017-05-30

Although wet stirred media milling has proven to be a robust process for producing nanoparticle suspensions of poorly water-soluble drugs and thereby enhancing their bioavailability, selection of bead size has been largely empirical, lacking fundamental rationale. This study aims to establish such rationale by investigating the impact of bead size at various stirrer speeds on the drug breakage kinetics via a microhydrodynamic model. To this end, stable suspensions of griseofulvin, a model BCS Class II drug, were prepared using hydroxypropyl cellulose and sodium dodecyl sulfate. The suspensions were milled at four different stirrer speeds (1000-4000rpm) using various sizes (50-1500μm) of zirconia beads. Laser diffraction, SEM, and XRPD were used for characterization. Our results suggest that there is an optimal bead size that achieves fastest breakage at each stirrer speed and that it shifts to a smaller size at higher speed. Calculated microhydrodynamic parameters reveal two counteracting effects of bead size: more bead-bead collisions with less energy/force upon a decrease in bead size. The optimal bead size exhibits a negative power-law correlation with either specific energy consumption or the microhydrodynamic parameters. Overall, this study rationalizes the use of smaller beads for more energetic wet media milling. Copyright © 2017 Elsevier B.V. All rights reserved.

Breakage and drying behaviour of granules in a continuous fluid bed dryer: Influence of process parameters and wet granule transfer.

PubMed

De Leersnyder, F; Vanhoorne, V; Bekaert, H; Vercruysse, J; Ghijs, M; Bostijn, N; Verstraeten, M; Cappuyns, P; Van Assche, I; Vander Heyden, Y; Ziemons, E; Remon, J P; Nopens, I; Vervaet, C; De Beer, T

2018-03-30

Although twin screw granulation has already been widely studied in recent years, only few studies addressed the subsequent continuous drying which is required after wet granulation and still suffers from a lack of detailed understanding. The latter is important for optimisation and control and, hence, a cost-effective practical implementation. Therefore, the aim of the current study is to increase understanding of the drying kinetics and the breakage and attrition phenomena during fluid bed drying after continuous twin screw granulation. Experiments were performed on a continuous manufacturing line consisting of a twin-screw granulator, a six-segmented fluid bed dryer, a mill, a lubricant blender and a tablet press. Granulation parameters were fixed in order to only examine the effect of drying parameters (filling time, drying time, air flow, drying air temperature) on the size distribution and moisture content of granules (both of the entire granulate and of size fractions). The wet granules were transferred either gravimetrically or pneumatically from the granulator exit to the fluid bed dryer. After a certain drying time, the moisture content reached an equilibrium. This drying time was found to depend on the applied airflow, drying air temperature and filling time. The moisture content of the granules decreased with an increasing drying time, airflow and drying temperature. Although smaller granules dried faster, the multimodal particle size distribution of the granules did not compromise uniform drying of the granules when the target moisture content was achieved. Extensive breakage of granules was observed during drying. Especially wet granules were prone to breakage and attrition during pneumatic transport, either in the wet transfer line or in the dry transfer line. Breakage and attrition of granules during transport and drying should be anticipated early on during process and formulation development by performing integrated experiments on the granulator, dryer and mill. Copyright © 2018 Elsevier B.V. All rights reserved.

Breaking of rod-shaped model material during compression

NASA Astrophysics Data System (ADS)

Lukas, Kulaviak; Vera, Penkavova; Marek, Ruzicka; Miroslav, Puncochar; Petr, Zamostny; Zdenek, Grof; Frantisek, Stepanek; Marek, Schongut; Jaromir, Havlica

2017-06-01

The breakage of a model anisometric dry granular material caused by uniaxial compression was studied. The bed of uniform rod-like pasta particles (8 mm long, aspect ratio 1:8) was compressed (Gamlen Tablet Press) and their size distribution was measured after each run (Dynamic Image Analysing). The compression dynamics was recorded and the effect of several parameters was tested (rate of compression, volume of granular bed, pressure magnitude and mode of application). Besides the experiments, numerical modelling of the compressed breakable material was performed as well, employing the DEM approach (Discrete Element Method). The comparison between the data and the model looks promising.

Cutting Head for Ultrasonic Lithotripsy

NASA Technical Reports Server (NTRS)

Angulo, E. D.; Goodfriend, R.

1987-01-01

Kidney stones lodged in urinary tract disintegrated with increased safety and efficiency by cutting head attached to end of vibrated wire probe. Aligns probe with stone and enables probe to vibrate long enough to disintegrate stone. Design of cutting head reduces risk of metal-fatigue-induced breakage of probe tip leaving metal fragments in urinary tract. Teeth of cutting head both seat and fragment kidney stone, while extension of collar into catheter lessens mechanical strain in probe wire, increasing probe life and lessening danger of in situ probe breakage.

Nijmegen breakage syndrome.

PubMed Central

van der Burgt, I; Chrzanowska, K H; Smeets, D; Weemaes, C

1996-01-01

Nijmegen breakage syndrome (NBS), a rare autosomal recessive condition also known as ataxia telangiectasia (AT) variants V1 and V2, is characterised by microcephaly, typical facies, short stature, immunodeficiency, and chromosomal instability. We report the clinical, immunological, chromosomal, and cell biological findings in 42 patients who are included in the NBS Registry in Nijmegen. The immunological, chromosomal, and cell biological findings resemble those in AT, but the clinical findings are quite different. NBS appears to be a separate entity not allelic with AT. Images PMID:8929954

Removal of a broken trigen intertan intertrochanteric antegrade nail.

PubMed

Zheng, Xuan-Lin; Park, Young-Chang; Kim, Sungmin; An, Haemosu; Yang, Kyu-Hyun

2017-02-01

Implant breakage is a serious complication after cephalomedullary nailing for unstable intertrochanteric fracture. Failure usually occurs at the lag screw hole in the nail body. On the other hand, lag screw failure is extremely rare and occurs around the nail-lag screw junction. We experienced rare mechanical failure of the Intertan nail, which showed breakage at the lag screw hole and failure of the integrated compression screw underneath the main lag screw. Copyright © 2016 Elsevier Ltd. All rights reserved.

A method for grindability testing using the Scirocco disperser.

PubMed

Bonakdar, Tina; Ali, Muzammil; Dogbe, Selasi; Ghadiri, Mojtaba; Tinke, Arjen

2016-03-30

In the early stages of development of a new Active Pharmaceutical Ingredient (API), insufficient material quantity is available for addressing processing issues, and it is highly desirable to be able to assess processability issues using the smallest possible powder sample quantity. A good example is milling of new active pharmaceutical ingredients. For particle breakage that is sensitive to strain rate, impact testing is the most appropriate method. However, there is no commercially available single particle impact tester for fine particulate solids. In contrast, dry powder dispersers, such as the Scirocco disperser of the Malvern Mastersizer 2000, are widely available, and can be used for this purpose, provided particle impact velocity is known. However, the distance within which the particles can accelerate before impacting on the bend is very short and different particle sizes accelerate to different velocities before impact. As the breakage is proportional to the square of impact velocity, the interpretation of breakage data is not straightforward and requires an analysis of particle velocity as a function of size, density and shape. We report our work using an integrated experimental and CFD modelling approach to evaluate the suitability of this device as a grindability testing device, with the particle sizing being done immediately following dispersion by laser diffraction. Aspirin, sucrose and α-lactose monohydrate are tested using narrow sieve cuts in order to minimise variations in impact velocity. The tests are carried out at eight different air nozzle pressures. As intuitively expected, smaller particles accelerate faster and impact the wall at a higher velocity compared to the larger particles. However, for a given velocity the extent of breakage of larger particles is larger. Using a numerical simulation based on CFD, the relationship between impact velocity and particle size and density has been established assuming a spherical shape, and using one-way coupling, as the particle concentration is very low. Taking account of these dependencies, a clear unification of the change in the specific surface area as a function of particle size, density and impact velocity is observed, and the slope of the fitted line gives a measure of grindability for each material. The trend of data obtained here matches the one obtained by single particle impact testing. Hence aerodynamic dispersion of solids by the Scirocco disperser can be used to evaluate the ease of grindability of different materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative Study of Vibration Condition Indicators for Detecting Cracks in Spur Gears

NASA Technical Reports Server (NTRS)

Nanadic, Nenad; Ardis, Paul; Hood, Adrian; Thurston, Michael; Ghoshal, Anindya; Lewicki, David

2013-01-01

This paper reports the results of an empirical study on the tooth breakage failure mode in spur gears. Of four dominant gear failure modes (breakage, wear, pitting, and scoring), tooth breakage is the most precipitous and often leads to catastrophic failures. The cracks were initiated using a fatigue tester and a custom-designed single-tooth bending fixture to simulate over-load conditions, instead of traditional notching using wire electrical discharge machining (EDM). The cracks were then propagated on a dynamometer. The ground truth of damage level during crack propagation was monitored with crack-propagation sensors. Ten crack propagations have been performed to compare the existing condition indicators (CIs) with respect to their: ability to detect a crack, ability to assess the damage, and sensitivity to sensor placement. Of more than thirty computed CIs, this paper compares five commonly used: raw RMS, FM0, NA4, raw kurtosis, and NP4. The performance of combined CIs was also investigated, using linear, logistic, and boosted regression trees based feature fusion.

Damage and Repair of DNA in 5-Bromodeoxyuridine-Labeled Chinese Hamster Cells Exposed to Fluorescent Light

PubMed Central

Ben-Hur, E.; Elkind, M. M.

1972-01-01

Illumination of Chinese hamster cells with fluorescent light after 5-bromodeoxyuridine incorporation leads to extensive single-strand breakage in the DNA of the exposed cells. The rate of production of single-strand breaks is dependent on the extent to which thymine is replaced by 5-bromouracil. At least some of the breaks observed with alkaline gradients are probably produced in vivo and are probably not contingent upon alkaline hydrolysis since breakage can be demonstrated with neutral gradients also. Cells are able to rejoin most of the single-strand breaks within 60 min; however, damage to the DNA-containing material (the “complex”) initially released from cells is repaired more slowly. Cysteamine protects against single-strand breakage with a dose-modifying factor of 2.8. A comparison is made between the production of single-strand breaks by fluorescent light and X-rays, and the significance of such breaks relative to cell survival is discussed. PMID:5063839

Effect of a depilatory agent on cotton, polyester, and rayon versus human hair in a laboratory setting.

PubMed

Plesa, Jocelyn A; Shoup, Kelly; Manole, Mioara D; Hickey, Robert W

2015-03-01

We examine the ability of a depilatory agent, Nair, to dissolve strands of hair, cotton, polyester, and rayon. We conducted a bench laboratory study in which we tested single strands of hair and natural and synthetic fibers under static tension with a 10.8-g weight and application of Nair. The dependent variable, time until breakage, was recorded. If the strand did not break within 8 hours, the experiment was discontinued. Three types of hair were tested (thin, medium, and thick, as recorded per diameter). Three types of natural and synthetic fibers were tested (cotton, polyester, and rayon). All types of hair had breakage within 10 minutes of the Nair application. Synthetic materials had no breakage after 8 hours with application of Nair. Depilatory agents dissolve hair under tension within minutes. However, they do not dissolve cotton, polyester, and rayon even after many hours of application. Copyright © 2014 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

Temperature effects on flocculation, using different coagulants.

PubMed

Fitzpatrick, C S B; Fradin, E; Gregory, J

2004-01-01

Temperature is known to affect flocculation and filter performance. Jar tests have been conducted in the laboratory, using a photometric dispersion analyser (PDA) to assess the effects of temperature on floc formation, breakage and reformation. Alum, ferric sulphate and three polyaluminium chloride (PACI) coagulants have been investigated for temperatures ranging between 6 and 29 degrees C for a suspension of kaolin clay in London tap water. Results confirm that floc formation is slower at lower temperatures for all coagulants. A commercial PACl product, PAX XL 19, produces the largest flocs for all temperatures; and alum the smallest. Increasing the shear rate results in floc breakage in all cases and the flocs never reform to their original size. This effect is most notable for temperatures around 15 degrees C. Breakage, in terms of floc size reduction, is greater for higher temperatures, suggesting a weaker floc. Recovery after increased shear is greater at lower temperatures implying that floc break-up is more reversible for lower temperatures.

Genotoxicity in native fish associated with agricultural runoff events

USGS Publications Warehouse

Whitehead, Andrew; Kuivila, Kathryn; Orlando, James L.; Kotelevtsev, S.; Anderson, Susan L.

2004-01-01

The primary objective of the present study was to test whether agricultural chemical runoff was associated with in-stream genotoxicity in native fish. Using Sacramento sucker (Catostomus occidentalis), we combined field-caging experiments in an agriculturally dominated watershed with controlled laboratory exposures to field-collected water samples, and we coupled genotoxicity biomarker measurements in fish with bacterial mutagenicity analysis of water samples. We selected DNA strand breakage as a genotoxicity biomarker and Ames Salmonella mutagenicity tests as a second, supporting indicator of genotoxicity. Data from experiments conducted during rainfall runoff events following winter application of pesticides in 2000 and 2001 indicated that DNA strand breaks were significantly elevated in fish exposed to San Joaquin River (CA, USA) water (38.8, 28.4, and 53.6% DNA strand breakage in year 2000 field, year 2000 lab, and year 2001 field exposures, respectively) compared with a nearby reference site (15.4, 8.7, and 12.6% DNA strand breakage in year 2000 field, year 2000 lab, and year 2001 field exposures, respectively). Time-course measurements in field experiments supported a linkage between induction of DNA strand breakage and the timing of agricultural runoff. San Joaquin River water also caused significant reversion mutation in two Ames Salmonella tester strains. Salmonella mutagenicity corroborated in-stream effects, further strengthening a causal relationship between runoff events and genotoxicity. Potentially responsible agents are discussed in the context of timing of runoff events in the field, concordance between laboratory and field exposures, pesticide application patterns in the drainage, and analytical chemistry data.

Impact of polymeric membrane breakage on drinking water quality and an online detection method of the breakage.

PubMed

Wu, Qilong; Zhang, Zhenghua; Cao, Guodong; Zhang, Xihui

2017-10-15

Polymeric membrane has been widely used for the treatment of drinking water in China, and the total treating capacity has reached up to 3.8 million m 3 /d. However, the membrane breakage found in the membrane modules in many water treatment plants resulted in an increase in turbidity and bacterial amount in the membrane permeate. In this study, a membrane module running for 3 years in a full-scale application was examined in terms of the breaking positions and the numbers of the broken fibers. It was found that most of the breaking positions were mainly on the outlet side of the module and that the distance from these points to the outlet was about 1/10-2/10 length of the membrane module. The lab-scale tests showed that the increase of the numbers of the breaking fibers in the membrane module (the breaking fibers were from 1 to 4 of 75 fibers) resulted in the increase in turbidity, particle count and the amount of total bacteria and coliform bacteria. Meanwhile, the water quality after the filtration with broken membrane fibers was similar to the quality of the raw water, which indicated that once the membrane fiber breakage occurred in the membrane module, the quality of drinking water after membrane filtration was significantly affected. Furthermore, the breaking position closer to the outlet side of the membrane module exposed much higher microbiological risk than those in the middle or near the bottom side. A pilot scale test was conducted by using a membrane module with 6600 fibers, and the effect of the membrane breakage (1-4 broken fibers) on water quality was also investigated. The results indicated that periodical backwashing caused drastic fluctuation of turbidity, particle count and the bacterial amount in the permeate water, which might be due to the washing force and self-blocking action inside the hollow fibers. Moreover, there is a good quantitative relationship (R 2 = 0.945) between particle count and the bacterial amount, which indicated that an online detection of particle count can be used to evaluate the bacterial risk. It was also suggested that the online detection of particle count after backwashing within 100 s would be a quick and precise method to identify any fiber breakage in time. These results are very important for the safety issue in the application of polymeric membrane to water treatment plants.

Non-Immunogenic Structurally and Biologically Intact Tissue Matrix Grafts for the Immediate Repair of Ballistic-Induced Vascular and Nerve Tissue Injury in Combat

DTIC Science & Technology

2004-12-01

and -2. However, there was no product breakage. The product stabilizers breakage can be addressed by either using stronger Styrofoam or using the same...dry ice shipper is suitable for use as a 72hrs shipping container for the frozen UVG and that, if necessary, the shipping time can be extended to at...concentrations for two hours at room temperature under constant agitation (85 rpm). The step-wise equilibration was measured using a refractometer

Structural Qualification of Composite Airframes

NASA Technical Reports Server (NTRS)

Kedward, Keith T.; McCarty, John E.

1997-01-01

The development of fundamental approaches for predicting failure and elongation characteristics of fibrous composites are summarized in this document. The research described includes a statistical formulation for individual fiber breakage and fragmentation and clustered fiber breakage, termed macrodefects wherein the aligned composite may represent a structural component such as a reinforcing bar element, a rebar. Experimental work conducted in support of the future exploitation of aligned composite rebar elements is also described. This work discusses the experimental challenges associated with rebar tensile test evaluation and describes initial numerical analyses performed in support of the experimental program.

Modeling the dynamics of a phreatic eruption based on a tilt observation: Barrier breakage leading to the 2014 eruption of Mount Ontake, Japan

NASA Astrophysics Data System (ADS)

Maeda, Yuta; Kato, Aitaro; Yamanaka, Yoshiko

2017-02-01

Although phreatic eruptions are common volcanic phenomena that sometimes result in significant disasters, their dynamics are poorly understood. In this study, we address the dynamics of the phreatic eruption of Mount Ontake, Japan, in 2014 based on analyses of a tilt change observed immediately (450 s) before the eruption onset. We conducted two sets of analysis: a waveform inversion and a modified phase-space analysis. Our waveform inversion of the tilt signal points to a vertical tensile crack at a depth of 1100 m. Our modified phase-space analysis suggests that the tilt change was at first a linear function in time that then switched to exponential growth. We constructed simple analytical models to explain these temporal functions. The linear function was explained by the boiling of underground water controlled by a constant heat supply from a greater depth. The exponential function was explained by the decompression-induced boiling of water and the upward Darcy flow of the water vapor through a permeable region of small cracks that were newly created in response to ongoing boiling. We interpret that this region was intact prior to the start of the tilt change, and thus, it has acted as a permeability barrier for the upward migration of fluids; it was a breakage of this barrier that led to the eruption.

Cell death induced by flavonoid glycosides with and without copper.

PubMed

Hsu, Hsue-Yin; Tsang, Shih-Fang; Lin, Kai-Wei; Yang, Shyh-Chyun; Lin, Chun-Nan

2008-07-01

The ability of flavonoid glycosides isolated from several plants to induce DNA breakage was examined using supercoiled plasmid pBR322 DNA by agarose gel electrophoresis in the presence of Cu(II). Among all the compounds, 1, 4, and 6 could cause significant breakages of supercoiled plasmid pBR322 DNA in the presence of Cu(II). Cu(I) was not shown to be an essential intermediate in the process of pBR322 DNA breakage by using the Cu(I)-specific sequestering reagent neocuproine. A decreased cell viability was enhanced in gastric carcinoma SCM-1 cells treating with lower concentrations of 1 and 6 when cotreated with increased concentrations of Cu(II), respectively. Treatments of SCM-1 cells with 500 microM of 1 in the presence of 300 or 500 microM of Cu(II) inhibited the Cu(II)-induced apoptosis. Compound 1 (500 microM) could prevent cell death by inhibiting the 500 microM Cu(II)-induced apoptosis and necrosis, but did not have any effect on the mitochondrial membrane potential changed by 500 microM Cu(II). Both compounds 1 and 6 could inhibit the DNA breakages caused by O2- while 1 also revealed inhibitory effect on xanthine oxidase with an IC50 value of 22.7+/-6.9 microM. These results indicated that compound 1 with a higher concentration may probably mediate through the suppression of xanthine oxidase activity and reduce reactive oxygen species (ROS) induced by high concentration of Cu(II) (500 microM) and prevent the following cell death.

Mechanical properties of electrospun bilayer fibrous membranes as potential scaffolds for tissue engineering.

PubMed

Pu, Juan; Komvopoulos, Kyriakos

2014-06-01

Bilayer fibrous membranes of poly(l-lactic acid) (PLLA) were fabricated by electrospinning, using a parallel-disk mandrel configuration that resulted in the sequential deposition of a layer with fibers aligned across the two parallel disks and a layer with randomly oriented fibers, both layers deposited in a single process step. Membrane structure and fiber alignment were characterized by scanning electron microscopy and two-dimensional fast Fourier transform. Because of the intricacies of the generated electric field, bilayer membranes exhibited higher porosity than single-layer membranes consisting of randomly oriented fibers fabricated with a solid-drum collector. However, despite their higher porosity, bilayer membranes demonstrated generally higher elastic modulus, yield strength and toughness than single-layer membranes with random fibers. Bilayer membrane deformation at relatively high strain rates comprised multiple abrupt microfracture events characterized by discontinuous fiber breakage. Bilayer membrane elongation yielded excessive necking of the layer with random fibers and remarkable fiber stretching (on the order of 400%) in the layer with fibers aligned in the stress direction. In addition, fibers in both layers exhibited multiple localized necking, attributed to the nonuniform distribution of crystalline phases in the fibrillar structure. The high membrane porosity, good mechanical properties, and good biocompatibility and biodegradability of PLLA (demonstrated in previous studies) make the present bilayer membranes good scaffold candidates for a wide range of tissue engineering applications. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Gel of chamomile vs. urea cream to prevent acute radiation dermatitis in patients with head and neck cancer: a randomized controlled trial.

PubMed

Ferreira, Elaine Barros; Ciol, Marcia A; Vasques, Christiane Inocêncio; Bontempo, Priscila de Souza Maggi; Vieira, Nayara Narley Pires; Silva, Luis Felipe Oliveira E; Avelino, Samuel Ramalho; Dos Santos, Marcos Antônio; Dos Reis, Paula Elaine Diniz

2016-08-01

To compare a gel made with chamomile (Chamomilla recutita) with a cream of urea as an intervention to delay the time to occurrence of radiation dermatitis. Radiation dermatitis is one of the most common adverse effects of radiotherapy in patients with head and neck cancer. It is characterized by erythema, itching, pain, skin breakage and burning sensation, and there is no consensus on how to prevent it. The study is a randomized controlled clinical trial. We will recruit 48 individuals with head and neck cancer who will be starting their radiotherapy and randomize them to receive either gel of chamomile or cream of urea, as an intervention for prevention of radiation dermatitis. Social-demographic data will be collected at baseline, and clinical data will be collected before the initiation of radiotherapy. Participants will be followed weekly to assess development of radiation dermatitis. The protocol is funded by Conselho Nacional de Pesquisa e Desenvolvimento Científico (Brazil). The study was approved by a research ethics committee. Given the clinical relevance of preventing radiation dermatitis and the lack of evidence supporting specific preventive interventions, it is important to study new products that might be efficacious to prevent this complication. This article presents the protocol of a randomized controlled trial comparing a gel made with chamomile (intervention) with a cream of urea (control) to prevent radiation dermatitis in patients with head and neck cancer undergoing radiotherapy. © 2016 John Wiley & Sons Ltd.

Novel Image Processing Interface to Relate DSB Spatial Distribution from Immunofluorescence Foci Experiments to the State-of-the-Art Models of DNA Breakage

NASA Technical Reports Server (NTRS)

Ponomarev, A. L.; Cucinotta, F. A.

2004-01-01

A recently developed software (NASARadiationTrackImage) allows a quick and automatic segmentation of foci that indicate spatial localization of specific proteins that are visualized by immunofluorescence. Of interest are the spatial and temporal distribution of foci such as gammaH2AX, a signal of the phosphorylation of a variant of the histone H2A that has been shown to correspond to DSBs, or proteins involved in DSB processing, such as ATM, Rad51, and p53, following exposures of human cells to high charge and energy (HZE) ion irradiation. Experimental data are recorded as sets of two-dimensional images in color with cells and foci of gammaH2AX, ATM, Rad51 or others shown. Different cells, levels of radiation and timing after radiation were recorded. The software allows us to calculate the number of foci per cell, overall intensity of light in foci and their spatial organization. A simple statistical model allows for testing of foci overlap (eclipse). A more complex statistical model previously known as DNAbreak simulates track structure and random chromosome geometry. It has one adjustable parameter corresponding to an average intensity of DSB creation in cubic micrometers of DNA volume per particle track or unit dose. Its limitation is the low-resolution limit both in physical space and DSB's along DNA. It works adequately on the scale of a cell and provides further insights on how the geometry of tracks and DNA affects genomic damage of the cell and subsequent repair. Future developments of the model for the description of the time evolution of DNA damage response proteins, and more robust track structure models will be discussed.

Automatic generation of efficient orderings of events for scheduling applications

NASA Technical Reports Server (NTRS)

Morris, Robert A.

1994-01-01

In scheduling a set of tasks, it is often not known with certainty how long a given event will take. We call this duration uncertainty. Duration uncertainty is a primary obstacle to the successful completion of a schedule. If a duration of one task is longer than expected, the remaining tasks are delayed. The delay may result in the abandonment of the schedule itself, a phenomenon known as schedule breakage. One response to schedule breakage is on-line, dynamic rescheduling. A more recent alternative is called proactive rescheduling. This method uses statistical data about the durations of events in order to anticipate the locations in the schedule where breakage is likely prior to the execution of the schedule. It generates alternative schedules at such sensitive points, which can be then applied by the scheduler at execution time, without the delay incurred by dynamic rescheduling. This paper proposes a technique for making proactive error management more effective. The technique is based on applying a similarity-based method of clustering to the problem of identifying similar events in a set of events.

How quantum entanglement in DNA synchronizes double-strand breakage by type II restriction endonucleases.

PubMed

Kurian, P; Dunston, G; Lindesay, J

2016-02-21

Macroscopic quantum effects in living systems have been studied widely in pursuit of fundamental explanations for biological energy transport and sensing. While it is known that type II endonucleases, the largest class of restriction enzymes, induce DNA double-strand breaks by attacking phosphodiester bonds, the mechanism by which simultaneous cutting is coordinated between the catalytic centers remains unclear. We propose a quantum mechanical model for collective electronic behavior in the DNA helix, where dipole-dipole oscillations are quantized through boundary conditions imposed by the enzyme. Zero-point modes of coherent oscillations would provide the energy required for double-strand breakage. Such quanta may be preserved in the presence of thermal noise by the enzyme's displacement of water surrounding the DNA recognition sequence. The enzyme thus serves as a decoherence shield. Palindromic mirror symmetry of the enzyme-DNA complex should conserve parity, because symmetric bond-breaking ceases when the symmetry of the complex is violated or when physiological parameters are perturbed from optima. Persistent correlations in DNA across longer spatial separations-a possible signature of quantum entanglement-may be explained by such a mechanism. Copyright © 2015 Elsevier Ltd. All rights reserved.

The prooxidant action of dietary antioxidants leading to cellular DNA breakage and anticancer effects: implications for chemotherapeutic action against cancer.

PubMed

Ullah, M F; Ahmad, Aamir; Khan, Husain Y; Zubair, H; Sarkar, Fazlul H; Hadi, S M

2013-11-01

Plant-derived dietary antioxidants have attracted considerable interest in recent past for their ability to induce apoptosis and regression of tumors in animal models. While it is believed that the antioxidant properties of these agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, it could not account for apoptosis induction and chemotherapeutic observations. In this article, we show that dietary antioxidants can alternatively switch to a prooxidant action in the presence of transition metals such as copper. Such a prooxidant action leads to strand breaks in cellular DNA and growth inhibition in cancer cells. Further, the cellular DNA breakage and anticancer effects were found to be significantly enhanced in the presence of copper ions. Moreover, inhibition of antioxidant-induced DNA strand breaks and oxidative stress by Cu(I)-specific chelators bathocuproine and neocuproine demonstrated the role of endogenous copper in the induction of the prooxidant mechanism. Since it is well established that tissue, cellular, and serum copper levels are considerably elevated in various malignancies, such a prooxidant cytotoxic mechanism better explains the anticancer activity of dietary antioxidants against cancer cells.

Correlation between the length reduction of carbon nanotubes and the electrical percolation threshold of melt compounded polyolefin composites.

PubMed

Vasileiou, Alexandros A; Kontopoulou, Marianna; Gui, Hua; Docoslis, Aristides

2015-01-28

The objectives of this work are to quantify the degree of multiwalled carbon nanotube (MWCNT) length reduction upon melt compounding and to demonstrate unambiguously that the length reduction is mainly responsible for the increase in electrical percolation threshold of the resulting composites. Polyolefin matrices of varying viscosities and different functional groups are melt compounded with MWCNTs. A simple method is developed to solubilize the polymer matrix and isolate the MWCNTs, enabling detailed imaging analysis. In spite of the perceived strength of the MWCNTs, the results demonstrate that the shear forces developed during melt mixing are sufficient to cause significant nanotube breakage and length reduction. Breakage is promoted when higher MWCNT contents are used, due to increased probability of particle collisions. Furthermore, the higher shear forces transmitted to the nanotubes in the presence of higher matrix viscosities and functional groups that promote interfacial interactions, shift the nanotube distribution toward smaller sizes. The length reduction of the MWCNTs causes significant increases in the percolation threshold, due to the loss of interconnectivity, which results in fewer conductive pathways. These findings are validated by comparing the experimental percolation threshold values with those predicted by the improved interparticle distance theoretical model.

How quantum entanglement in DNA synchronizes double-strand breakage by type II restriction endonucleases

PubMed Central

Kurian, P.; Dunston, G.; Lindesay, J.

2015-01-01

Macroscopic quantum effects in living systems have been studied widely in pursuit of fundamental explanations for biological energy transport and sensing. While it is known that type II endonucleases, the largest class of restriction enzymes, induce DNA double-strand breaks by attacking phosphodiester bonds, the mechanism by which simultaneous cutting is coordinated between the catalytic centers remains unclear. We propose a quantum mechanical model for collective electronic behavior in the DNA helix, where dipole-dipole oscillations are quantized through boundary conditions imposed by the enzyme. Zero-point modes of coherent oscillations would provide the energy required for double-strand breakage. Such quanta may be preserved in the presence of thermal noise by the enzyme’s displacement of water surrounding the DNA recognition sequence. The enzyme thus serves as a decoherence shield. Palindromic mirror symmetry of the enzyme-DNA complex should conserve parity, because symmetric bond-breaking ceases when the symmetry of the complex is violated or when physiological parameters are perturbed from optima. Persistent correlations in DNA across longer spatial separations—a possible signature of quantum entanglement—may be explained by such a mechanism. PMID:26682627

Telomere formation on macronuclear chromosomes of Oxytricha trifallax and O. fallax: alternatively processed regions have multiple telomere addition sites

PubMed Central

Williams, Kevin R; Doak, Thomas G; Herrick, Glenn

2002-01-01

Background Ciliates employ massive chromatid breakage and de novo telomere formation during generation of the somatic macronucleus. Positions flanking the 81-MAC locus are reproducibly cut. But those flanking the Common Region are proposed to often escape cutting, generating three nested macronuclear chromosomes, two retaining "arms" still appended to the Common Region. Arm-distal positions must differ (in cis) from the Common Region flanks. Results The Common-Region-flanking positions also differ from the arm-distal positions in that they are "multi-TAS" regions: anchored PCR shows heterogeneous patterns of telomere addition sites, but arm-distal sites do not. The multi-TAS patterns are reproducible, but are sensitive to the sequence of the allele being processed. Thus, random degradation following chromatid cutting does not create this heterogeneity; these telomere addition sites also must be dictated by cis-acting sequences. Conclusions Most ciliates show such micro-heterogeneity in the precise positions of telomere addition sites. Telomerase is believed to be tightly associated with, and act in concert with, the chromatid-cutting nuclease: heterogeneity must be the result of intervening erosion activity. Our "weak-sites" hypothesis explains the correlation between alternative chromatid cutting at the Common Region boundaries and their multi-TAS character: when the chromatid-breakage machine encounters either a weak binding site or a weak cut site at these regions, then telomerase dissociates prematurely, leaving the new end subject to erosion by an exonuclease, which pauses at cis-acting sequences; telomerase eventually heals these resected termini. Finally, we observe TAS positioning influenced by trans-allelic interactions, reminiscent of transvection. PMID:12199911

Hunting for huntingtin associated factors: Identification and characterization of huntingtin expanded polyglutamine aggregate associated factors and their impact on Huntington disease model cellular toxicity

DTIC Science & Technology

2016-05-20

ID) domains. ... 21 Figure 6: Western blotting confirms that TAPI-identified proteins are trapped in large, detergent- resistant Htt-polyQ...aggregates stained with iodine, which is used to detect starch ; hence they were named ‘amyloid,’ or ‘ starch -like’ (18; 187). Since that time, great...β-rich structure of amyloid that results in strong resistance to degradation, detergents, proteolysis, and mechanical breakage (49). Amyloid

Percutaneous self-injury to the femoral region caused by bur breakage during surgical extraction of a patient's impacted third molar.

PubMed

Yu, Tae Hoon; Lee, Jun; Kim, Bong Chul

2015-10-01

Extraction of an impacted third molar is one of the most frequently performed techniques in oral and maxillofacial surgery. Surgeons can suffer numerous external injuries while extracting a tooth, with percutaneous injuries to the hand being the most commonly reported. In this article, we present a case involving a percutaneous injury of the surgeon's femoral region caused by breakage of the fissure bur connected to the handpiece during extraction of the third molar. We also propose precautions to prevent such injuries and steps to be undertaken when they occur.

Modeling of Hydraulic Fracture Propagation at the kISMET Site Using a Fully Coupled 3D Network-Flow and Quasi- Static Discrete Element Model

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

Zhou, Jing; Huang, Hai; Mattson, Earl

Aimed at supporting the design of hydraulic fracturing experiments at the kISMET site, ~1500 m below ground in a deep mine, we performed pre-experimental hydraulic fracturing simulations in order to estimate the breakdown pressure, propagation pressure, fracture geometry, and the magnitude of induced seismicity using a newly developed fully coupled three-dimensional (3D) network flow and quasi-static discrete element model (DEM). The quasi-static DEM model, which is constructed by Delaunay tessellation of the rock volume, considers rock fabric heterogeneities by using the “disordered” DEM mesh and adding random perturbations to the stiffness and tensile/shear strengths of individual DEM elements and themore » elastic beams between them. A conjugate 3D flow network based on the DEM lattice is constructed to calculate the fluid flow in both the fracture and porous matrix. One distinctive advantage of the model is that fracturing is naturally described by the breakage of elastic beams between DEM elements. It is also extremely convenient to introduce mechanical anisotropy into the model by simply assigning orientation-dependent tensile/shear strengths to the elastic beams. In this paper, the 3D hydraulic fracturing model was verified against the analytic solution for a penny-shaped crack model. We applied the model to simulate fracture propagation from a vertical open borehole based on initial estimates of rock mechanical properties and in-situ stress conditions. The breakdown pressure and propagation pressure are directly obtained from the simulation. In addition, the released elastic strain energies of individual fracturing events were calculated and used as a conservative estimate for the magnitudes of the potential induced seismic activities associated with fracturing. The comparisons between model predictions and experimental results are still ongoing.« less

Sexually transmitted diseases among female commercial sex workers in Finote Selam town, northwest Ethiopia: a community-based cross-sectional study.

PubMed

Anteneh, Zelalem Alamrew; Agumas, Yirdaw Amare; Tarekegn, Molalign

2017-01-01

Female commercial sex workers (FCSWs) are considered a high-risk group for acquiring sexually transmitted diseases (STDs), yet the reported prevalence varies in studies around the world. The aim of this study was to determine the magnitude and associated factors of STDs among female sex workers. A community-based cross-sectional study was conducted among female sex workers in Finote Selam town. A total of 389 sex workers were studied using census method. Data were collected using an interview with structured questionnaires. The data were entered and analyzed by using SPSS version 20 software package. The findings of this study showed that the overall prevalence of STDs was 20.6%. The reported prevalence of genital discharge, ulcer, and bubo was 15.9%, 15.2%, and 11.6%, respectively. In the multivariable logistic regression analysis, respondents who did not use a condom were about four times at higher risk of STDs than those who were using a condom consistently (adjusted odds ratio [AOR] = 4.07; 95% confidence interval [CI]: 1.812, 9.139). Respondents who experienced condom breakages were more than 12 times more likely to report STDs than those who never experienced condom breakages (AOR = 12.291, 95% CI: 5.701, 26.495). The findings of this study showed that one in five commercial sex workers in Finote Selam town had STDs. Sex without a condom and condom breakage during sexual intercourse showed a significant association with STDs. Therefore, the Woreda Health Office in collaboration with nongovernmental organizations in the area should work on safe sex promotion to enhance consistent condom use and reduce condom breakage through continuous education among commercial sex workers.

Isolation of the human chromosomal band Xq28 within somatic cell hybrids by fragile X site breakage.

PubMed Central

Warren, S T; Knight, S J; Peters, J F; Stayton, C L; Consalez, G G; Zhang, F P

1990-01-01

The chromosomal fragile-site mapping to Xq27.3 is associated with a frequent form of mental retardation and is prone to breakage after induced deoxyribonucleotide pool perturbation. The human hypoxanthine phosphoribosyltransferase (HPRT) and glucose-6-phosphate dehydrogenase (G6PD) genes flank the fragile X chromosome site and can be used to monitor integrity of the site in human-hamster somatic cell hybrids deficient in the rodent forms of these activities. After induction of the fragile X site, negative selection for HPRT and positive enrichment for G6PD resulted in 31 independent colonies of HPRT-,G6PD+ phenotype. Southern blot analysis demonstrated the loss of all tested markers proximal to the fragile X site with retention of all tested human Xq28 loci in a majority of the hybrids. In situ hybridization with a human-specific probe demonstrated the translocation of a small amount of human DNA to rodent chromosomes in these hybrids, suggesting chromosome breakage at the fragile X site and the subsequent translocation of Xq28. Southern blot hybridization of hybrid-cell DNA, resolved by pulsed-field gel electrophoresis, for human-specific repetitive sequences revealed abundant CpG-islands within Xq28, consistent with its known gene density. The electrophoretic banding patterns of human DNA among the hybrids were remarkably consistent, suggesting that fragile X site breakage is limited to a relatively small region in Xq27-28. These somatic cell hybrids, containing Xq27.3-qter as the sole human DNA, will aid the search for DNA associated with the fragile X site and will augment the high resolution genomic analysis of Xq28, including the identification of candidate genes for genetic-disease loci mapping to this region. Images PMID:2339126

Driving force analysis of proton tunnelling across a reactivity series for an enzyme-substrate complex.

PubMed

Hothi, Parvinder; Hay, Sam; Roujeinikova, Anna; Sutcliffe, Michael J; Lee, Michael; Leys, David; Cullis, Paul M; Scrutton, Nigel S

2008-11-24

Quantitative structure-activity relationships are widely used to probe C-H bond breakage by quinoprotein enzymes. However, we showed recently that p-substituted benzylamines are poor reactivity probes for the quinoprotein aromatic amine dehydrogenase (AADH) because of a requirement for structural change in the enzyme-substrate complex prior to C-H bond breakage. This rearrangement is partially rate limiting, which leads to deflated kinetic isotope effects for p-substituted benzylamines. Here we report reactivity (driving force) studies of AADH with p-substituted phenylethylamines for which the kinetic isotope effect (approximately 16) accompanying C-H/C-(2)H bond breakage is elevated above the semi-classical limit. We show bond breakage occurs by quantum tunnelling and that within the context of the environmentally coupled framework for H-tunnelling the presence of the p-substituent places greater demand on the apparent need for fast promoting motions. The crystal structure of AADH soaked with phenylethylamine or methoxyphenylethylamine indicates that the structural change identified with p-substituted benzylamines should not limit the reaction with p-substituted phenylethylamines. This is consistent with the elevated kinetic isotope effects measured with p-substituted phenylethylamines. We find a good correlation in the rate constant for proton transfer with bond dissociation energy for the reactive C-H bond, consistent with a rate that is limited by a Marcus-like tunnelling mechanism. As the driving force becomes larger, the rate of proton transfer increases while the Marcus activation energy becomes smaller. This is the first experimental report of the driving force perturbation of H-tunnelling in enzymes using a series of related substrates. Our study provides further support for proton tunnelling in AADH.

The role of glutathione in DNA damage by potassium bromate in vitro.

PubMed

Parsons, J L; Chipman, J K

2000-07-01

We have investigated the role of reduced glutathione (GSH) in the genetic toxicity of the rodent renal carcinogen potassium bromate (KBrO(3)). A statistically significant increase in the concentration of 8-oxodeoxyguanosine (8-oxodG) relative to deoxyguanosine was measured following incubation of calf thymus DNA with KBrO(3) and GSH or N-acetylcysteine (NACys). This was dependent on these thiols and was associated with the loss of GSH and production of oxidized glutathione. A short-lived (<6 min) intermediate was apparent which did not react with the spin trap dimethylpyrroline N-oxide. DNA oxidation was not evident when potassium chlorate (KClO(3)) or potassium iodate (KIO(3)) were used instead of KBrO(3), though GSH depletion also occurred with KIO(3), but not with KClO(3). Other reductants and thiols in combination with KBrO(3) did not cause a significant increase in DNA oxidation. DNA strand breakage was also induced by KBrO(3) in human white blood cells (5 mM) and rat kidney epithelial cells (NRK-52E, 1.5 mM). This was associated with an apparent small depletion of thiols in NRK-52E cells at 15 min and with an elevation of 8-oxodG at a delayed time of 24 h. Depletion of intra-cellular GSH by diethylmaleate in human lymphocytes decreased the amount of strand breakage induced by KBrO(3). Extracellular GSH, however, protected against DNA strand breakage by KBrO(3), possibly due to the inability of the reactive product to enter the cell. In contrast, membrane-permeant NACys enhanced KBrO(3)-induced DNA strand breakage in these cells. DNA damage by KBrO(3) is therefore largely dependent on access to intracellular GSH.

[Effect of electroacupuncture on the behavior and hippocampal ultrastructure in APP 695 V 717 I transgenic mice].

PubMed

Xue, Wei-Guo; Ge, Gui-Ling; Zhang, Zhong; Xu, Hong; Bai, Li-Min

2009-10-01

To investigate the ultrastructural basis underlying electroacupuncture (EA) induced improvement of Alzheimer disease (AD) in transgenic mice. Twelve APP 695 V 717 I transgenic mice were randomly divided into model group and EA group; and other 6 negative transgenic mice (C 57 BL/6 J) were made up of normal control group. After 3 months treatment by EA (15 min per other day, 2 Hz/100 Hz, 3-4 mA) applied to "Baihui" (GV 20) and "Yongquan" (KI 1), the learning and memory ability of mice was measured by Lashley III water maze test, and the ultrastructural changes of hippocampal CA 1 region was observed by electronic microscopy. The swimming escape latency and the number of navigating errors (dead-end forward swimming) in model group were significantly longer and more than those in normal control group (P < 0.05); and those in EA group were considerably shorter and fewer than those in model group (P < 0.05), suggesting an improvement of learning-memory ability after EA. Comparison of the ultrastructure of the neurons in the hippocampal CA 1 region showed swelling of the mitochondria, broken or disappearance of the mitochondrial cristae, degeneration of the synapses, breakage and vague outline of the basement membrane of the blood capillaries in mice of model group; and basically distinct outline of the mitochondrial cristae and microvessels, and more synaptic vesicles in EA group. EA may effectively improve the learning-memory capacity of the APP transgenic AD mice and alleviate the pathological changes of neurons of the hippocampal CA 1 region, which may be one of the mechanisms underlying the improvement of AD by EA.

Evolutionary dynamics of nematode operons: easy come, slow go.

PubMed

Qian, Wenfeng; Zhang, Jianzhi

2008-03-01

Operons are widespread in prokaryotes, but are uncommon in eukaryotes, except nematode worms, where approximately 15% of genes reside in over 1100 operons in the model organism Caenorhabditis elegans. It is unclear how operons have become abundant in nematode genomes. The "one-way street" hypothesis asserts that once formed by chance, operons are very difficult to break, because the breakage would leave downstream genes in an operon without a promoter, and hence, unexpressed. To test this hypothesis, we analyzed the presence and absence of C. elegans operons in Caenorhabditis briggsae, Caenorhabditis remanei, and Caenorhabditis brenneri, using Pristionchus pacificus and Brugia malayi as outgroups, and identified numerous operon gains and losses. Coupled with experimental examination of trans-splicing patterns, our comparative genomic analysis revealed diverse molecular mechanisms of operon losses, including inversion, insertion, and relocation, but the presence of internal promoters was not found to facilitate operon losses. In several cases, the data allowed inference of mechanisms by which downstream genes are expressed after operon breakage. We found that the rate of operon gain is approximately 3.3 times that of operon loss. Thus, the evolutionary dynamics of nematode operons is better described as "easy come, slow go," rather than a "one-way street." Based on a mathematic model of operon gains and losses and additional assumptions, we projected that the number of operons in C. elegans will continue to rise by 6%-18% in future evolution before reaching equilibrium between operon gains and losses.

Large-Amplitude Deformation and Bond Breakage in Shock-Induced Reactions of Explosive Molecules

NASA Astrophysics Data System (ADS)

Kay, Jeffrey

The response of explosive molecules to large-amplitude mechanical deformation plays an important role in shock-induced reactions and the initiation of detonation in explosive materials. In this presentation, the response of a series of explosive molecules (nitromethane, 2,4,6-trinitrotoluene [TNT], and 2,4,6-triamino-1,3,5-trinitrobenzene [TATB]) to a variety of large-amplitude deformations are examined using ab initio quantum chemical calculations. Large-amplitude motions that result in bond breakage are described, and the insights these results provide into both previous experimental observations and previous theoretical predictions of shock-induced reactions are discussed.

Apparatus And Method For Producing Single Crystal Metallic Objects

DOEpatents

Huang, Shyh-Chin; Gigliotti, Jr., Michael Francis X.; Rutkowski, Stephen Francis; Petterson, Roger John; Svec, Paul Steven

2006-03-14

A mold is provided for enabling casting of single crystal metallic articles including a part-defining cavity, a sorter passage positioned vertically beneath and in fluid communication with the part-defining cavity, and a seed cavity positioned vertically beneath and in fluid communication with the sorter passage. The sorter passage includes a shape suitable for encouraging a single crystal structure in solidifying molten metal. Additionally, a portion of the mold between the sorter passage and the part-defining cavity includes a notch for facilitating breakage of a cast article proximate the notch during thermal stress build-up, so as to prevent mold breakage or the inclusion of part defects.

Management of displaced comminuted patellar fracture with titanium cable cerclage.

PubMed

Yang, Li; Yueping, Ouyang; Wen, Yuan

2010-08-01

Management of a displaced comminuted patellar fracture is challenging. Tension band wiring and lag screw fixation are not suitable for such a fracture pattern. Stainless steel wiring with various configurations has been the mainstay of treatment. However, issues of loss of fixation and breakage of wire have not been resolved yet. Partial or total patellectomy is the last resort with a detrimental effect on quadriceps power. Braided titanium cable is stronger in tensile strength and better in fatigue resistance than the stainless steel monofilament wire, and the tension of fixation could be controlled by a graded instrument in its application. We used titanium cable to treat 21 consecutive patients with displaced comminuted patellar fracture. Patients were followed up for a mean period of 24 months (12 to 32 months). The mean score at the final follow-up was 27 points (25 to 30) using the Böstman method. There was no complication except breakage of one cable at the sixth week after the operation and the fracture had united despite the breakage. This technique is simple and effective for these difficult fractures and avoided prolonged immobilisation of the knee. Copyright 2010 Elsevier B.V. All rights reserved.

Autologous platelet lysates local injections for treatment of tibia non-union with breakage of the nickelclad: a case report.

PubMed

Jiang, Hong-Jiang; Tan, Xun-Xiang; Ju, Hai-Yang; Su, Jin-Ping; Yan, Wei; Song, Xiu-Gang; Qin, Li-Wu; Ju, Chang-Jun; Wang, Ling-Shuang; Zou, De-Bao

2016-01-01

Nonunions of the tibia represent challenging orthopedic problems, which require the surgeon to analyze numerous factors and choose an appropriate treatment. This article presents a case report of tibia and fibula fracture patient who failed the internal fixation surgery and successfully recovered after one course of percutaneous autologous platelet lysates injection. The patient received an internal nickelclad breakage at 9 months post-surgery but reluctant to accept a second surgery, then autologous platelet lysates (APL) injection which is a less invasive method was recommended. The injections were carried once a week for three times. Radiologic evaluation was conducted every month until recovery. To the best of our knowledge, this is the first reported case of tibia delayed union with breakage of the plate resolved with APL injection. Improved clinical evidence was observed at 4 and 6 months after injection. The patient got good bony union at 8 months post-injection. The patient didn't feel any discomfort postinjection, no complications such as infection, refracture etc. were observed. APL percutaneous injection could be a new therapeutic option for the treatment of nonunion or delayed healing fractures.

Biodegradable fixation for craniomaxillofacial surgery: a 10-year experience involving 761 operations and 745 patients

PubMed Central

Turvey, T. A.; Proffit, W. P.; Phillips, C.

2011-01-01

Patient acceptance, safety, and efficacy of poly-L/DL-lactic acid (PLLDL) bone plates and screws in craniomaxillofacial surgery are reported in this article. Included in the sample are 745 patients who underwent 761 separate operations, including more than 1400 surgical procedures (orthognathic surgery (685), bone graft reconstruction (37), trauma (191) and transcranial surgery (20)). The success (no breakage or inflammation requiring additional operating room treatment) was 94%. Failure occurred because of breakage (14) or exuberant inflammation (31). All breakage occurred at mandibular sites and the majority of inflammatory failure occurred in the maxilla or orbit (29), with only two in the mandible. Failures were evenly distributed between the two major vendors. PLLDL 70/30 bone plates and screws may be used successfully in a variety of craniomaxillofacial surgical applications. The advantages include the gradual transference of physiological forces to the healing bone, the reduced need for a second operation to remove the material and its potential to serve as a vehicle to deliver bone-healing proteins to fracture/osteotomy sites. Bone healing was noted at all sites, even where exuberant inflammation required a second surgical intervention. PMID:21185695

Ground breakage and associated effects in the Cook Inlet area, Alaska, resulting from the March 27, 1964 earthquake: Chapter F in The Alaska earthquake, March 27, 1964: regional effects

USGS Publications Warehouse

Foster, Helen L.; Karlstrom, Thor N.V.

1967-01-01

The great 1964 Alaska earthquake caused considerable ground breakage in the Cook Inlet area of south-central Alaska. The breakage occurred largely in thick deposits of unconsolidated sediments. The most important types of ground breakage were (1) fracturing or cracking and the extrusion of sand and gravel with ground water along fractures in various types of landforms, and (2) slumping and lateral extension of unconfined faces, particularly along delta fronts. The principal concentration of ground breakage within the area covered by this report was in a northeast-trending zone about 60 miles long and 6 miles wide in the northern part of the Kenai Lowland. The zone cut across diverse topography and stratigraphy. Cracks were as much as 30 feet across and 25 feet deep. Sand, gravel, and pieces of coal and lignite were extruded along many fissures. It is suggested that the disruption in this zone may be due to movement along a fault in the underlying Tertiary rocks. The outwash deltas of Tustumena and Skilak Lakes in the Kenai Lowland, of Eklutna Lake and Lake George in the Chugach Mountains, of Bradley Lake in the Kenai Mountains, and at the outlet of upper Beluga Lake at the base of the Alaska Range showed much slumping, as did the delta of the Susitna River. Parts of the flood plains of the Skilak River, Fox River, and Eagle River were extensively cracked. A few avalanches and slumps occurred along the coast of Cook Inlet in scattered localities. Some tidal flats were cracked. However, in view of the many thick sections of unconsolidated sediments and the abundance of steep slopes, the cracking was perhaps less than might have been expected. Observations along the coasts indicated changes in sea level which, although caused partly by compaction of unconsolidated sediments, may largely be attributed to crus1tal deformation accompanying the earthquake. Most of the Cook Inlet area was downwarped, although the northwest side of Cook Inlet may have been slightly unwarped. Maximum change in the Cook Inlet area was probably less than 6 feet. Little or no regional tilting was detected in the lake basins of Tustumena and Skilak Lakes.

Transverse and Oblique Long Bone Fracture Evaluation by Low Order Ultrasonic Guided Waves: A Simulation Study

PubMed Central

Li, Ying; Liu, Dan; Xu, Kailiang; Le, Lawrence H.; Wang, Weiqi

2017-01-01

Ultrasonic guided waves have recently been used in fracture evaluation and fracture healing monitoring. An axial transmission technique has been used to quantify the impact of the gap breakage width and fracture angle on the amplitudes of low order guided wave modes S0 and A0 under a 100 kHz narrowband excitation. In our two dimensional finite-difference time-domain (2D-FDTD) simulation, the long bones are modeled as three layers with a soft tissue overlay and marrow underlay. The simulations of the transversely and obliquely fractured long bones show that the amplitudes of both S0 and A0 decrease as the gap breakage widens. Fixing the crack width, the increase of the fracture angle relative to the cross section perpendicular to the long axis enhances the amplitude of A0, while the amplitude of S0 shows a nonmonotonic trend with the decrease of the fracture angle. The amplitude ratio between the S0 and A0 modes is used to quantitatively evaluate the fracture width and angles. The study suggests that the low order guided wave modes S0 and A0 have potentials for transverse and oblique bone fracture evaluation and fracture healing monitoring. PMID:28182135

Cellulose Crystal Dissolution in Imidazolium-Based Ionic Liquids: A Theoretical Study.

PubMed

Uto, Takuya; Yamamoto, Kazuya; Kadokawa, Jun-Ichi

2018-01-11

The highly crystalline nature of cellulose results in poor processability and solubility, necessitating the search for solvents that can efficiently dissolve this material. Thus, ionic liquids (ILs) have recently been shown to be well suited for this purpose, although the corresponding dissolution mechanism has not been studied in detail. Herein, we adopt a molecular dynamics (MD) approach to study the dissolution of model cellulose crystal structures in imidazolium-based ILs and gain deep mechanistic insights, demonstrating that dissolution involves IL penetration-induced cleavage of hydrogen bonds between cellulose molecular chains. Moreover, we reveal that in ILs with high cellulose dissolving power (powerful solvents, such as 1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium chloride), the above molecular chains are peeled from the crystal phase and subsequently dispersed in the solvent, whereas no significant structural changes are observed in poor-dissolving-power solvents. Finally, we utilize MD trajectory analysis to show that the solubility of microcrystalline cellulose is well correlated with the number of intermolecular hydrogen bonds in cellulose crystals. The obtained results allow us to conclude that both anions and cations of high-dissolving-power ILs contribute to the stepwise breakage of hydrogen bonds between cellulose chains, whereas this breakage does not occur to a sufficient extent in poorly solubilizing ILs.

Transverse and Oblique Long Bone Fracture Evaluation by Low Order Ultrasonic Guided Waves: A Simulation Study.

PubMed

Li, Ying; Liu, Dan; Xu, Kailiang; Ta, Dean; Le, Lawrence H; Wang, Weiqi

2017-01-01

Ultrasonic guided waves have recently been used in fracture evaluation and fracture healing monitoring. An axial transmission technique has been used to quantify the impact of the gap breakage width and fracture angle on the amplitudes of low order guided wave modes S 0 and A 0 under a 100 kHz narrowband excitation. In our two dimensional finite-difference time-domain (2D-FDTD) simulation, the long bones are modeled as three layers with a soft tissue overlay and marrow underlay. The simulations of the transversely and obliquely fractured long bones show that the amplitudes of both S 0 and A 0 decrease as the gap breakage widens. Fixing the crack width, the increase of the fracture angle relative to the cross section perpendicular to the long axis enhances the amplitude of A 0, while the amplitude of S 0 shows a nonmonotonic trend with the decrease of the fracture angle. The amplitude ratio between the S 0 and A 0 modes is used to quantitatively evaluate the fracture width and angles. The study suggests that the low order guided wave modes S 0 and A 0 have potentials for transverse and oblique bone fracture evaluation and fracture healing monitoring.

Holmium:Yttrium Aluminum Garnet Laser and Guidewires: Is There a Durability Difference Among Guidewires Against Laser Energy? An In Vitro Experimental Study.

PubMed

Bagbanci, Sahin

2017-05-01

To evaluate the durability differences between five different type of guidewires against laser energy in an in vitro experimental ureteral model. The study was performed at the Department of Urology, Medicine Faculty of Ahi Evran University. An in vitro experimental ureteral model was created for the work; a silicon ureteral model in a saline-filled container. Experiments were performed on five different type of guidewires; ZIPwire, Sensor polytetrafluoroethylene (PTFE) Nitinol guidewire, Roadrunner ® PC wire guide, Amplatz Super Stiff, and Zebra Urologic Guidewire. These guidewires were grouped from one to five, respectively. Laser fibers were contacted to the guidewire, and laser energy was fired to the premarked tip and body parts in different adjustments. The breakage of the guidewires was detected only on the flexible tip parts in group 1a, group 1b, group 2a, group 2b, group 4a, and group 4b. The body parts of the guidewires were resistant to laser energy in all groups and did not break. The breakage of the guidewires occurred after 3 J × 10 Hz (30 W) experiment. Group 1a and 1b were different from group 2a, 2b, 4a, and 4b according to Kruskal-Wallis H test. The body parts of the guidewires in all study groups were resistant to laser energy. The tip parts of Zipwire ™ , Sensor ™ PTFE Nitinol, and Amplatz Super Stiff ™ guidewire should be kept away from the surgical field when the high power settings of the laser are being used. The body parts of the guidewires can be utilized in the surgical field safely.

RNA Polymerase Collision versus DNA Structural Distortion: Twists and Turns Can Cause Break Failure

PubMed Central

Pannunzio, Nicholas R.; Lieber, Michael R.

2016-01-01

Summary The twisting of DNA due to the movement of RNA polymerases is the basis of numerous classic experiments in molecular biology. Recent mouse genetic models indicate that chromosomal breakage is common at sites of transcriptional turbulence. Two key studies on this point mapped breakpoints to sites of either convergent or divergent transcription, but arrived at different conclusions as to which is more detrimental and why. The issue turns on whether DNA strand separation is the basis for the chromosomal instability or collision of RNA polymerases? PMID:27153532

Advanced Durability Analysis. Volume 2. Analytical Predictions, Test Results and Analytical Correlations

DTIC Science & Technology

1989-02-27

34 - 0.75") associated with fuel leakage/ligament breakage.,- No matter what form, location or combination the as-maiufactured flaws may "have in...the fractographic data used, the fractographic crack size range used for the back-extrapolation and the crack growth rate model used, (6) it must be...Growth Rate Parameters 3.3.1.2 Estimation of EIFSD 36 Parameters 3.3.1.3 Goodness-of-Fit. Plots 37 3.3.1.4 Discussion of Results 50 3.3.2 Straight-Bore

[Needle breakage during mandibular block anaesthesia: prevention and retrieval].

PubMed

Baart, J A; van Amerongen, W E; de Jong, K J M; Allard, R H B

2006-12-01

Disposable needles for dental local anaesthesia do not break easily. Still, needle breakage does occur, and is mainly caused by unexpected movements of the patient or pre-use bending of the needle by the dentist. If a dental needle breaks while administering local anaesthesia, the dentist should prevent panic. If the patient opens his mouth wide the needle might still be visible. If so, the needle is removed. If the needle is no longer visible, the site where the needle has penetrated the mucosa should be marked with a permanent marker. The dentist will contact a maxillofacial surgeon for immediate consultation. The maxillofacial surgeon will try to retrieve the broken dental needle under general anaesthesia.

A patient with polymerase E1 deficiency (POLE1): clinical features and overlap with DNA breakage/instability syndromes.

PubMed

Thiffault, Isabelle; Saunders, Carol; Jenkins, Janda; Raje, Nikita; Canty, Kristi; Sharma, Mukta; Grote, Lauren; Welsh, Holly I; Farrow, Emily; Twist, Greyson; Miller, Neil; Zwick, David; Zellmer, Lee; Kingsmore, Stephen F; Safina, Nicole P

2015-05-07

Chromosome instability syndromes are a group of inherited conditions associated with chromosomal instability and breakage, often leading to immunodeficiency, growth retardation and increased risk of malignancy. We performed exome sequencing on a girl with a suspected chromosome instability syndrome that manifested as growth retardation, microcephaly, developmental delay, dysmorphic features, poikiloderma, immune deficiency with pancytopenia, and myelodysplasia. She was homozygous for a previously reported splice variant, c.4444 + 3A > G in the POLE1 gene, which encodes the catalytic subunit of DNA polymerase E. This is the second family with POLE1-deficency, with the affected individual demonstrating a more severe phenotype than previously described.

Droplets size evolution of dispersion in a stirred tank

NASA Astrophysics Data System (ADS)

Kysela, Bohus; Konfrst, Jiri; Chara, Zdenek; Sulc, Radek; Jasikova, Darina

2018-06-01

Dispersion of two immiscible liquids is commonly used in chemical industry as wall as in metallurgical industry e. g. extraction process. The governing property is droplet size distribution. The droplet sizes are given by the physical properties of both liquids and flow properties inside a stirred tank. The first investigation stage is focused on in-situ droplet size measurement using image analysis and optimizing of the evaluation method to achieve maximal result reproducibility. The obtained experimental results are compared with multiphase flow simulation based on Euler-Euler approach combined with PBM (Population Balance Modelling). The population balance model was, in that specific case, simplified with assumption of pure breakage of droplets.

Computer simulation of data on chromosome aberrations produced by X rays or alpha particles and detected by fluorescence in situ hybridization.

PubMed

Chen, A M; Lucas, J N; Simpson, P J; Griffin, C S; Savage, J R; Brenner, D J; Hlatky, L R; Sachs, R K

1997-11-01

With fluorescence in situ hybridization (FISH), many different categories of chromosome aberrations can be recognized-dicentrics, translocations, rings and various complex aberrations such as insertions or three-way interchanges. Relative frequencies for the various aberration categories indicate mechanisms of radiation-induced damage and reflect radiation quality. Data obtained with FISH support a proximity version of the classic random breakage-and-reunion model for the formation of aberrations. A Monte Carlo computer implementation of the model, called the CAS (chromosome aberration simulator), is generalized here to high linear energy transfer (LET) and compared to published data for human cells irradiated with X rays or 238Pu alpha particles. For each kind of radiation, the CAS has two adjustable parameters: the number of interaction sites per cell nucleus and the number of reactive double-strand breaks (DSBs) per gray. Aberration frequencies for various painted chromosomes, of varying lengths, and for 11 different categories of simple or complex aberrations were simulated and compared to the data. The optimal number of interaction sites was found to be approximately 13 for X irradiation and approximately 25 for alpha-particle irradiation. The relative biological effectiveness (RBE) of alpha particles for the induction of reactive DSBs (which are a minority of all DSBs) was found to be approximately 4. The two-parameter CAS model adequately matches data for many different categories of aberrations. It can use data obtained with FISH for any one painting pattern to predict results for any other kind of painting pattern or whole-genome staining, and to estimate a suggested overall numerical damage indicator for chromosome aberration studies, the total misrejoining number.

An in silico investigation into the causes of telomere length heterogeneity and its implications for the Hayflick limit.

PubMed

Golubev, A; Khrustalev, S; Butov, A

2003-11-21

In telomerase-negative cell populations the mean telomere length (TL) decreases with increasing population doubling number (PD). A critically small TL is believed to stop cell proliferation at a cell-, age- and species-specific PD thus defining the Hayflick limit. However, positively skewed TL distributions are broad compared to differences between initial and final mean TL and strongly overlap at middle and late PD, which is inconsistent with a limiting role of TL. We used computer-assisted modelling to define what set of premises may account for the above. Our model incorporates the following concepts. DNA end replication problem: telomeres loose 1 shortening unit (SU) upon each cell division. Free radical-caused TL decrease: telomeres experience random events resulting in the loss of a random SU number within a remaining TL. Stochasticity of gene expression and cell differentiation: cells experience random events inducing mitoses or committing cells to proliferation arrest, the latter option requiring a specified number of mitoses to be passed. Cells whose TL reaches 1SU cannot divide. The proliferation kinetics of such virtual cells conforms to the transition probability model of cell cycle. When no committing events occur and at realistic SU estimates of the initial TL, maximal PD values far exceed the Hayflick limit observed in normal cells and are consistent with the crisis stage entered by transformed cells that have surpassed the Hayflick limit. At intermediate PD, symmetrical TL distributions are yielded. Upon introduction of committing events making the ratio of the rates of proliferating and committing events (P/C) range from 1.10 to 1.25, TL distributions at intermediate PD become positively skewed, and virtual cell clones show bimodal size distributions. At P/C as high as 1.25 the majority of virtual cells at maximal PD contain telomeres with TL>1SU. A 10% increase in P/C within the 1.10-1.25 range produces a two-fold increase in the maximal PD, which can reach values of up to 25 observed in rodent and some human cells. Increasing the number of committed mitoses from 0 to 10 can increases PD to about 50 observed in human fibroblasts. Introduction of the random TL breakage makes the shapes of TL distributions quite dissimilar from those observed in real cells. Telomere length decrease is a correlate of cell proliferation that cannot alone account for the Hayflick limit, which primarily depends on parameters of cell population kinetics. Free radical damage influences the Hayflick limit not through TL but rather by affecting the ratio of the rates of events that commit cells to mitoses or to proliferation arrest.

Physical and Clinical Evaluation of Hip Spica Cast applied with Three-slab Technique using Fibreglass Material

PubMed Central

Bitar, KM; Ferdhany, ME; Saw, A

2016-01-01

Introduction: Hip spica casting is an important component of treatment for developmental dysplasia of the hip (DDH) and popular treatment method for femur fractures in children. Breakage at the hip region is a relatively common problem of this cast. We have developed a three-slab technique of hip spica application using fibreglass as the cast material. The purpose of this review was to evaluate the physical durability of the spica cast and skin complications with its use. Methodology: A retrospective review of children with various conditions requiring hip spica immobilisation which was applied using our method. Study duration was from 1st of January 2014 until 31st December 2015. Our main outcomes were cast breakage and skin complications. For children with hip instability, the first cast would be changed after one month, and the second cast about two months later. Results: Twenty-one children were included, with an average age of 2.2 years. The most common indication for spica immobilisation was developmental dysplasia of the hip. One child had skin irritation after spica application. No spica breakage was noted. Conclusion: This study showed that the three-slab method of hip spica cast application using fibreglass material was durable and safe with low risk of skin complications. PMID:28553442

Mobilization of Copper ions by Flavonoids in Human Peripheral Lymphocytes Leads to Oxidative DNA Breakage: A Structure Activity Study.

PubMed

Arif, Hussain; Rehmani, Nida; Farhan, Mohd; Ahmad, Aamir; Hadi, Sheikh Mumtaz

2015-11-09

Epidemiological studies have linked dietary consumption of plant polyphenols with lower incidence of various cancers. In particular, flavonoids (present in onion, tomato and other plant sources) induce apoptosis and cytotoxicity in cancer cells. These can therefore be used as lead compounds for the synthesis of novel anticancer drugs with greater bioavailability. In the present study, we examined the chemical basis of cytotoxicity of flavonoids by studying the structure-activity relationship of myricetin (MN), fisetin (FN), quercetin (QN), kaempferol (KL) and galangin (GN). Using single cell alkaline gel electrophoresis (comet assay), we established the relative efficiency of cellular DNA breakage as MN > FN > QN > KL > GN. Also, we determined that the cellular DNA breakage was the result of mobilization of chromatin-bound copper ions and the generation of reactive oxygen species. The relative DNA binding affinity order was further confirmed using molecular docking and thermodynamic studies through the interaction of flavonoids with calf thymus DNA. Our results suggest that novel anti-cancer molecules should have ortho-dihydroxy groups in B-ring and hydroxyl groups at positions 3 and 5 in the A-ring system. Additional hydroxyl groups at other positions further enhance the cellular cytotoxicity of the flavonoids.

The gene for the ataxia-telagiectasia variant, Nijmegen breakage syndrome, maps to a 1-cM interval on chromosome 8q21

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

Saar, K.; Stumm, M.; Wegner, R.D.

1997-03-01

Nijmegen breakage syndrome (NBS; Seemanova II syndrome) and Berlin breakage syndrome (BBS), also known as ataxia-telangiectasia variants, are two clinically indistinguishable autosomal recessive familial cancer syndromes that share with ataxia-telangiectasia similar cellular, immunological, and chromosomal but not clinical findings. Classification in NBS and BBS was based on complementation of their hypersensitivity to ionizing radiation in cell-fusion experiments. Recent investigations have questioned the former classification into two different disease entities, suggesting that NBS/BBS is caused by mutations in a single radiosensitivity gene. We now have performed a whole-genome screen in 14 NBS/BBS families and have localized the gene for NBS/BBS tomore » a 1-cM interval on chromosome 8q21, between markers D8S271 and D8S270, with a peak LOD score of 6.86 at D8S1811. This marker also shows strong allelic association to both Slavic NBS and German BBS patients, suggesting the existence of one major mutation of Slavic origin. Since the same allele is seen in both former complementation groups, genetic homogeneity of NBS/BBS can be considered as proved. 21 refs., 2 figs., 2 tabs.« less

Mobilization of Copper ions by Flavonoids in Human Peripheral Lymphocytes Leads to Oxidative DNA Breakage: A Structure Activity Study

PubMed Central

Arif, Hussain; Rehmani, Nida; Farhan, Mohd; Ahmad, Aamir; Hadi, Sheikh Mumtaz

2015-01-01

Epidemiological studies have linked dietary consumption of plant polyphenols with lower incidence of various cancers. In particular, flavonoids (present in onion, tomato and other plant sources) induce apoptosis and cytotoxicity in cancer cells. These can therefore be used as lead compounds for the synthesis of novel anticancer drugs with greater bioavailability. In the present study, we examined the chemical basis of cytotoxicity of flavonoids by studying the structure–activity relationship of myricetin (MN), fisetin (FN), quercetin (QN), kaempferol (KL) and galangin (GN). Using single cell alkaline gel electrophoresis (comet assay), we established the relative efficiency of cellular DNA breakage as MN > FN > QN > KL > GN. Also, we determined that the cellular DNA breakage was the result of mobilization of chromatin-bound copper ions and the generation of reactive oxygen species. The relative DNA binding affinity order was further confirmed using molecular docking and thermodynamic studies through the interaction of flavonoids with calf thymus DNA. Our results suggest that novel anti-cancer molecules should have ortho-dihydroxy groups in B-ring and hydroxyl groups at positions 3 and 5 in the A-ring system. Additional hydroxyl groups at other positions further enhance the cellular cytotoxicity of the flavonoids. PMID:26569217

Cellular DNA breakage by soy isoflavone genistein and its methylated structural analogue biochanin A.

PubMed

Ullah, Mohd Fahad; Shamim, Uzma; Hanif, Sarmad; Azmi, Asfar S; Hadi, Sheikh M

2009-11-01

Epidemiological studies have indicated that populations with high isoflavone intake through soy consumption have lower rates of breast, prostate, and colon cancer. The isoflavone polyphenol genistein in soybean is considered to be a potent chemopreventive agent against cancer. In order to explore the chemical basis of chemopreventive activity of genistein, in this paper we have examined the structure-activity relationship between genistein and its structural analogue biochanin A. We show that both genistein and its methylated derivative biochanin A are able to mobilize nuclear copper in human lymphocyte, leading to degradation of cellular DNA. However, the relative rate of DNA breakage was greater in the case of genistein. Further, the cellular DNA degradation was inhibited by copper chelator (neocuproine/bathocuproine) but not by compounds that specifically bind iron and zinc (desferrioxamine mesylate and histidine, respectively). We also compared the antioxidant activity of the two isoflavones against tert-butylhydroperoxide-induced oxidative breakage in lymphocytes. Again genistein was found to be more effective than biochanin A in providing protection against oxidative stress induced by tert-butylhydroperoxide. It would therefore appear that the structural features of isoflavones that are important for antioxidant properties are also the ones that contribute to their pro-oxidant action through a mechanism that involves redox cycling of chromatin-bound nuclear copper.

Influence of van der Waals forces on increasing the strength and toughness in dynamic fracture of nanofibre networks: a peridynamic approach

NASA Astrophysics Data System (ADS)

Bobaru, F.

2007-07-01

The peridynamic method is used here to analyse the effect of van der Waals forces on the mechanical behaviour and strength and toughness properties of three-dimensional nanofibre networks under imposed stretch deformation. The peridynamic formulation allows for a natural inclusion of long-range forces (such as van der Waals forces) by considering all interactions as 'long-range'. We use van der Waals interactions only between different fibres and do not need to model individual atoms. Fracture is introduced at the microstructural (peridynamic bond) level for the microelastic type bonds, while van der Waals bonds can reform at any time. We conduct statistical studies to determine a certain volume element for which the network of randomly oriented fibres becomes quasi-isotropic and insensitive to statistical variations. This qualitative study shows that the presence of van der Waals interactions and of heterogeneities (sacrificial bonds) in the strength of the bonds at the crosslinks between fibres can help in increasing the strength and toughness of the nanofibre network. Two main mechanisms appear to control the deformation of nanofibre networks: fibre reorientation (caused by deformation and breakage) and fibre accretion (due to van der Waals interaction). Similarities to the observed toughness of polymer adhesive in the abalone shell composition are explained. The author would like to dedicate this work to the 60th anniversary of Professor Subrata Mukherjee.

DNA strand breakage and lipid peroxidation after exposure to welding fumes in vivo.

PubMed

Chuang, Cheng-Hung; Huang, Chong-En; Chen, Hsiu-Ling

2010-01-01

A remarkable number of complex aerosols are generated from welding processes. The objective of this study was to compare DNA damage and lipid peroxidation in plasma and in lung and in liver tissue of rats exposed to welding fumes in an exposure chamber with those of control animals. Three air samples from the chamber were also collected to assess the exposure dose for each exposure (total samplings = 18). Eight male Sprague-Dawley rats were exposed to welding fumes at a concentration of 1540.76 mg/m(3) for 10 min/day six times on day 1, day 3, day 7, day 15, day 30 and day 40. Lung, liver and kidney injury was measured following exposure, as well as in unexposed control rats (n = 4 at the beginning of the study). DNA strand breakage [tail moment (TMOM)] in exposed animals showed significant differences at day 1, day 4, day 7 and day 15 relative to the levels in control animals. Malondialdehyde (MDA, a lipid peroxidation product) levels increased gradually post-welding to 0.4 microM at 7 days. MDA and TMOM both reached maximum levels 7 days after the first exposure. At the start, an increasing trend in DNA strand breakage was more obvious than increases in MDA levels; MDA seemed to reflect long-term effects of exposure to welding fumes since it increased after 7 days and was sustained to 40 days in vivo. Significant differences in both MDA levels and DNA strand breakage were seen in lung, liver and kidney 40 days after the first fume inhalation. We conclude that acute exposure of rats to welding fumes causes noticeable oxidative damage and lipid peroxidation effects and that DNA damage may recover after long and repeat exposure. More chronic inhalation and low-dose studies are needed in order to further assess the effects of inhalation of welding fumes on DNA and to elucidate the possible causal mechanisms associated with the biologically damaging effects of welding fumes.

Monitoring of DNA breakage in embryonic stages of the African catfish Clarias gariepinus (Burchell, 1822) after exposure to lead nitrate using alkaline comet assay.

PubMed

Osman, Alaa G M; Mekkawy, Imam A; Verreth, Johan; Wuertz, Sven; Kloas, Werner; Kirschbaum, Frank

2008-12-01

Increasing lead contamination in Egyptian ecosystems and high lead concentrations in food items have raised concern for human health and stimulated studies on monitoring ecotoxicological impact of lead-caused genotoxicity. In this work, the alkaline comet assay was modified for monitoring DNA strand breakage in sensitive early life stages of the African catfish Clarias gariepinus. Following exposure to 100, 300, and 500 microg/L lead nitrate, DNA strand breakage was quantified in embryos at 30, 48, 96, 144, and 168 h post-fertilization (PFS). For quantitative analysis, four commonly used parameters (tail % DNA, %TDNA; head % DNA, %HDNA; tail length, TL; tail moment, TM) were analyzed in 96 nuclei (in triplicates) at each sampling point. The parameter %TDNA revealed highest resolution and lowest variation. A strong correlation between lead concentration, time of exposure, and DNA strand breakage was observed. Here, genotoxicity detected by comet assay preceded the manifested malformations assessed with conventional histology. Qualitative evaluation was carried out using five categories are as follows: undamaged (%TDNA < or = 10%), low damaged (10% < %TDNA < or = 25%), median damaged (25 < %TDNA < or = 50%), highly damaged (50 < %TDNA < or = 75%), and extremely damaged (%TDNA > 75%) nuclei confirming a dose and time-dependent shift towards increased frequencies of highly and extremely damaged nuclei. A protective capacity provided by a hardened chorion is a an interesting finding in this study as DNA damage in the prehatching stages 30 h-PFS and 48 h-PFS was low in all treatments (qualitative and quantitative analyses). These results clearly show that the comet assay is a sensitive tool for the detection of genotoxicity in vulnerable early life stages of the African catfish and is a method more sensitive than histological parameters for monitoring genotoxic effects. 2008 Wiley Periodicals, Inc.

Diagnosis of Fanconi anemia in patients with bone marrow failure

PubMed Central

Pinto, Fernando O.; Leblanc, Thierry; Chamousset, Delphine; Le Roux, Gwenaelle; Brethon, Benoit; Cassinat, Bruno; Larghero, Jérôme; de Villartay, Jean-Pierre; Stoppa-Lyonnet, Dominique; Baruchel, André; Socié, Gérard; Gluckman, Eliane; Soulier, Jean

2009-01-01

Background Patients with bone marrow failure and undiagnosed underlying Fanconi anemia may experience major toxicity if given standard-dose conditioning regimens for hematopoietic stem cell transplant. Due to clinical variability and/or potential emergence of genetic reversion with hematopoietic somatic mosaicism, a straightforward Fanconi anemia diagnosis can be difficult to make, and diagnostic strategies combining different assays in addition to classical breakage tests in blood may be needed. Design and Methods We evaluated Fanconi anemia diagnosis on blood lymphocytes and skin fibroblasts from a cohort of 87 bone marrow failure patients (55 children and 32 adults) with no obvious full clinical picture of Fanconi anemia, by performing a combination of chromosomal breakage tests, FANCD2-monoubiquitination assays, a new flow cytometry-based mitomycin C sensitivity test in fibroblasts, and, when Fanconi anemia was diagnosed, complementation group and mutation analyses. The mitomycin C sensitivity test in fibroblasts was validated on control Fanconi anemia and non-Fanconi anemia samples, including other chromosomal instability disorders. Results When this diagnosis strategy was applied to the cohort of bone marrow failure patients, 7 Fanconi anemia patients were found (3 children and 4 adults). Classical chromosomal breakage tests in blood detected 4, but analyses on fibroblasts were necessary to diagnose 3 more patients with hematopoietic somatic mosaicism. Importantly, Fanconi anemia was excluded in all the other patients who were fully evaluated. Conclusions In this large cohort of patients with bone marrow failure our results confirmed that when any clinical/biological suspicion of Fanconi anemia remains after chromosome breakage tests in blood, based on physical examination, history or inconclusive results, then further evaluation including fibroblast analysis should be made. For that purpose, the flow-based mitomycin C sensitivity test here described proved to be a reliable alternative method to evaluate Fanconi anemia phenotype in fibroblasts. This global strategy allowed early and accurate confirmation or rejection of Fanconi anemia diagnosis with immediate clinical impact for those who underwent hematopoietic stem cell transplant. PMID:19278965

PIERCE1 is critical for specification of left-right asymmetry in mice.

PubMed

Sung, Young Hoon; Baek, In-Jeoung; Kim, Yong Hwan; Gho, Yong Song; Oh, S Paul; Lee, Young Jae; Lee, Han-Woong

2016-06-16

The specification of left-right asymmetry of the visceral organs is precisely regulated. The earliest breakage of left-right symmetry occurs as the result of leftward flow generated by asymmetric beating of nodal cilia, which eventually induces asymmetric Nodal/Lefty/Pitx2 expression on the left side of the lateral plate mesoderm. PIERCE1 has been identified as a p53 target gene involved in the DNA damage response. In this study, we found that Pierce1-null mice exhibit severe laterality defects, including situs inversus totalis and heterotaxy with randomized situs and left and right isomerisms. The spectrum of laterality defects was closely correlated with randomized expression of Nodal and its downstream genes, Lefty1/2 and Pitx2. The phenotype of Pierce1-null mice most closely resembled that of mutant mice with impaired ciliogenesis and/or ciliary motility of the node. We also found the loss of asymmetric expression of Cerl2, the earliest flow-responding gene in the node of Pierce1-null embryos. The results suggest that Pierce1-null embryos have defects in generating a symmetry breaking signal including leftward nodal flow. This is the first report implicating a role for PIERCE1 in the symmetry-breaking step of left-right asymmetry specification.

Impact analysis of natural fiber and synthetic fiber reinforced polymer composite

NASA Astrophysics Data System (ADS)

Sangamesh, Ravishankar, K. S.; Kulkarni, S. M.

2018-05-01

Impact analysis of the composite structure is essential for many fields like automotive, aerospace and naval structure which practically difficult to characterize. In the present study impact analysis of carbon-epoxy (CE) and jute-epoxy (JE) laminates were studied for three different thicknesses. The 3D finite element model was adopted to study the impact forces experienced, energy absorption and fracture behavior of the laminated composites. These laminated composites modeled as a 3D deformable solid element and an impactor at a constant velocity were modeled as a discrete rigid element. The energy absorption and fracture behaviors for various material combinations and thickness were studied. The fracture behavior of these composite showed progressive damage with matrix failure at the initial stage followed by complete fiber breakage.

Cluster pattern analysis of energy deposition sites for the brachytherapy sources 103Pd, 125I, 192Ir, 137Cs, and 60Co.

PubMed

Villegas, Fernanda; Tilly, Nina; Bäckström, Gloria; Ahnesjö, Anders

2014-09-21

Analysing the pattern of energy depositions may help elucidate differences in the severity of radiation-induced DNA strand breakage for different radiation qualities. It is often claimed that energy deposition (ED) sites from photon radiation form a uniform random pattern, but there is indication of differences in RBE values among different photon sources used in brachytherapy. The aim of this work is to analyse the spatial patterns of EDs from 103Pd, 125I, 192Ir, 137Cs sources commonly used in brachytherapy and a 60Co source as a reference radiation. The results suggest that there is both a non-uniform and a uniform random component to the frequency distribution of distances to the nearest neighbour ED. The closest neighbouring EDs show high spatial correlation for all investigated radiation qualities, whilst the uniform random component dominates for neighbours with longer distances for the three higher mean photon energy sources (192Ir, 137Cs, and 60Co). The two lower energy photon emitters (103Pd and 125I) present a very small uniform random component. The ratio of frequencies of clusters with respect to 60Co differs up to 15% for the lower energy sources and less than 2% for the higher energy sources when the maximum distance between each pair of EDs is 2 nm. At distances relevant to DNA damage, cluster patterns can be differentiated between the lower and higher energy sources. This may be part of the explanation to the reported difference in RBE values with initial DSB yields as an endpoint for these brachytherapy sources.

Cluster pattern analysis of energy deposition sites for the brachytherapy sources 103Pd, 125I, 192Ir, 137Cs, and 60Co

NASA Astrophysics Data System (ADS)

Villegas, Fernanda; Tilly, Nina; Bäckström, Gloria; Ahnesjö, Anders

2014-09-01

Analysing the pattern of energy depositions may help elucidate differences in the severity of radiation-induced DNA strand breakage for different radiation qualities. It is often claimed that energy deposition (ED) sites from photon radiation form a uniform random pattern, but there is indication of differences in RBE values among different photon sources used in brachytherapy. The aim of this work is to analyse the spatial patterns of EDs from 103Pd, 125I, 192Ir, 137Cs sources commonly used in brachytherapy and a 60Co source as a reference radiation. The results suggest that there is both a non-uniform and a uniform random component to the frequency distribution of distances to the nearest neighbour ED. The closest neighbouring EDs show high spatial correlation for all investigated radiation qualities, whilst the uniform random component dominates for neighbours with longer distances for the three higher mean photon energy sources (192Ir, 137Cs, and 60Co). The two lower energy photon emitters (103Pd and 125I) present a very small uniform random component. The ratio of frequencies of clusters with respect to 60Co differs up to 15% for the lower energy sources and less than 2% for the higher energy sources when the maximum distance between each pair of EDs is 2 nm. At distances relevant to DNA damage, cluster patterns can be differentiated between the lower and higher energy sources. This may be part of the explanation to the reported difference in RBE values with initial DSB yields as an endpoint for these brachytherapy sources.

Trichorrhexis nodosa

MedlinePlus

Hair shaft fracture; Brittle hair; Fragile hair; Hair breakage ... may recommend measures to reduce damage to your hair such as: Gentle ... chemicals such as those used in straightening compounds and ...

Distributed strain measurement and possible breakage detection of optical-fiber-embedded composite structure using slope-assisted Brillouin optical correlation-domain reflectometry

NASA Astrophysics Data System (ADS)

Lee, Heeyoung; Ochi, Yutaka; Matsui, Takahiro; Matsumoto, Yukihiro; Tanaka, Yosuke; Nakamura, Hitoshi; Mizuno, Yosuke; Nakamura, Kentaro

2018-07-01

Slope-assisted Brillouin optical correlation-domain reflectometry (SA-BOCDR) is a recently developed structural health monitoring technique for measurements of strain, temperature, and loss distributions along optical fibers. Although the basic operational principle of this method has been clarified, no measurements using optical fibers embedded in actual structures have been reported. As a first step towards such practical applications, in this study, we present an example of an SA-BOCDR-based diagnosis using a composite structure with carbon fiber-reinforced plastics. The system’s output agrees well with the actual strain distributions. We were also able to detect the breakage of the embedded fiber, thus demonstrating the promise of SA-BOCDR for practical applications.

Dicentric breakage at telomere fusions

PubMed Central

Pobiega, Sabrina; Marcand, Stéphane

2010-01-01

Nonhomologous end-joining (NHEJ) inhibition at telomeres ensures that native chromosome ends do not fuse together. But the occurrence and consequences of rare telomere fusions are not well understood. It is notably unclear whether a telomere fusion could be processed to restore telomere ends. Here we address the behavior of individual dicentrics formed by telomere fusion in the yeast Saccharomyces cerevisiae. Our approach was to first stabilize and amplify fusions between two chromosomes by temporarily inactivating one centromere. Next we analyzed dicentric breakage following centromere reactivation. Unexpectedly, dicentrics often break at the telomere fusions during progression through mitosis, a process that restores the parental chromosomes. This unforeseen result suggests a rescue pathway able to process telomere fusions and to back up NHEJ inhibition at telomeres. PMID:20360388

Addressing Machining Issues for the Intermetallic Compound 60-NITINOL

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; Wozniak, Walter A.; McCue, Terry R.

2012-01-01

60-NITINOL (60 wt.% Ni - 40 wt.% Ti) is being studied as a material for advanced aerospace components. Frequent wire breakage during electrical-discharge machining of this material was investigated. The studied material was fabricated from hot isostatically pressed 60-NITINOL powder obtained through a commercial source. Bulk chemical analysis of the material showed that the composition was nominal but had relatively high levels of certain impurities, including Al and O. It was later determined that Al2O3 particles had contaminated the material during the hot isostatic pressing procedure and that these particles were the most likely cause of the wire breakage. The results of this investigation highlight the importance of material cleanliness to its further implementation.

Physical simulation and theoretical evolution for ground fissures triggered by underground coal mining

PubMed Central

Yu, Xiang; Yang, Yi; Yang, Zeng-Qiang

2018-01-01

Underground coal mining activities are prone to cause movement and breakage in geological strata and also lead to mining subsidence and even ground fissures. Along the direction working panel advancing, ground fissures may occur in roof in front and/or behind working panel. However, the investigations of previous similarity tests in lab only emphasize on the region behind working panel. By improving strata material property in construction and mounting artificial pressure devices, two physical simulation tests were conducted and successfully investigated the simulated results. Then, the mechanical model of “cantilever beam and elastic foundation beam” was proposed to calculate the stress distribution and the crack initiation angle in overlying strata and it well explains the mechanisms of ground fissures generation and propagation. Results show that, the maximum internal force in roof always occurred in front of working panel. However, because the void space in gob due to excavation is large enough to cause the bend and rotation of roof strata, compare to the triaxially compressed region in front of working panel, the roof always broke off at some positions above gob since the stress concentration resulting from such bend and rotation of strata could easily reach the limit strength of strata rocks. Also, the length of cantilever beam changed dynamically as respect to the panel advancing and the breakage intervals. Thus, the breakage position where the internal force first reached the limit tensile strength is not fixed and there will be two different kinds of relative positions between the crack initiation point and the working panel. The crack initiation direction is always perpendicular to the internal force, and the crack propagation direction is affected by the initiation angle, overburden-separation degree and the position of the hydraulic shields. If there is no overburden-separation or less, the roofs will break off as a composite beam and the propagation direction will be roughly along the central line between the initial broken point and the support position. Otherwise, the roof strata will bend with the support shields moving forward, then the fracture angle will be close to the initiation angle and the fault surface will be stepped. PMID:29513703

Physical simulation and theoretical evolution for ground fissures triggered by underground coal mining.

PubMed

Yang, Jing-Hu; Yu, Xiang; Yang, Yi; Yang, Zeng-Qiang

2018-01-01

Underground coal mining activities are prone to cause movement and breakage in geological strata and also lead to mining subsidence and even ground fissures. Along the direction working panel advancing, ground fissures may occur in roof in front and/or behind working panel. However, the investigations of previous similarity tests in lab only emphasize on the region behind working panel. By improving strata material property in construction and mounting artificial pressure devices, two physical simulation tests were conducted and successfully investigated the simulated results. Then, the mechanical model of "cantilever beam and elastic foundation beam" was proposed to calculate the stress distribution and the crack initiation angle in overlying strata and it well explains the mechanisms of ground fissures generation and propagation. Results show that, the maximum internal force in roof always occurred in front of working panel. However, because the void space in gob due to excavation is large enough to cause the bend and rotation of roof strata, compare to the triaxially compressed region in front of working panel, the roof always broke off at some positions above gob since the stress concentration resulting from such bend and rotation of strata could easily reach the limit strength of strata rocks. Also, the length of cantilever beam changed dynamically as respect to the panel advancing and the breakage intervals. Thus, the breakage position where the internal force first reached the limit tensile strength is not fixed and there will be two different kinds of relative positions between the crack initiation point and the working panel. The crack initiation direction is always perpendicular to the internal force, and the crack propagation direction is affected by the initiation angle, overburden-separation degree and the position of the hydraulic shields. If there is no overburden-separation or less, the roofs will break off as a composite beam and the propagation direction will be roughly along the central line between the initial broken point and the support position. Otherwise, the roof strata will bend with the support shields moving forward, then the fracture angle will be close to the initiation angle and the fault surface will be stepped.

Soil mechanics: breaking ground.

PubMed

Einav, Itai

2007-12-15

In soil mechanics, student's models are classified as simple models that teach us unexplained elements of behaviour; an example is the Cam clay constitutive models of critical state soil mechanics (CSSM). 'Engineer's models' are models that elaborate the theory to fit more behavioural trends; this is usually done by adding fitting parameters to the student's models. Can currently unexplained behavioural trends of soil be explained without adding fitting parameters to CSSM models, by developing alternative student's models based on modern theories?Here I apply an alternative theory to CSSM, called 'breakage mechanics', and develop a simple student's model for sand. Its unique and distinctive feature is the use of an energy balance equation that connects grain size reduction to consumption of energy, which enables us to predict how grain size distribution (gsd) evolves-an unprecedented capability in constitutive modelling. With only four parameters, the model is physically clarifying what CSSM cannot for sand: the dependency of yielding and critical state on the initial gsd and void ratio.

The investigation of tethered satellite system dynamics

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1984-01-01

Tethered satellite system (TSS) dynamics were studied. The dynamic response of the TSS during the entire stationkeeping phase for the first electrodynamic mission was investigated. An out of plane swing amplitude and the tether's bowing were observed. The dynamics of the slack tether was studied and computer code, SLACK2, was improved both in capabilities and computational speed. Speed hazard related to tether breakage or plasma contactor failure was examined. Preliminary values of the potential difference after the failure and of the drop of the electric field along the tether axis have been computed. The update of the satellite rotational dynamics model is initiated.

Inventory Control.

ERIC Educational Resources Information Center

Byrum, David L., Ed.

1984-01-01

Describes an electronic thermometer using a precision temperature sensor (includes detailed schematic of circuits) and inexpensive ring holders for round-bottomed flasks. Also describes a method for reducing funnel breakage. (JN)

Attributing mortality among drivers of population decline in Acropora palmata in the Florida Keys (USA)

NASA Astrophysics Data System (ADS)

Williams, D. E.; Miller, M. W.

2012-06-01

Acropora palmata populations have experienced steep declines over the past 30 years. Although numerous culprits are recognized, their relative contributions to the decline are poorly quantified, making it difficult to prioritize effective conservation measures. In 2004, a demographic monitoring program was implemented in the Florida Keys (USA), aimed at determining the relative importance of various stressors affecting A. palmata. A subset of randomly selected A. palmata colonies within 15 fore-reef plots was tagged and surveyed three to four times per year over 7 years. Colony size, live tissue, prevalence of disease, snail ( Coralliophila abbreviata) predation, physical damage and other conditions were assessed at each survey. The estimated effect of each condition causing recent mortality was ranked, and together, these parameters were used to attribute the population-level tissue loss associated with each condition. In addition, all new colonies in the study plots were counted and assessed annually in order to track trends in total colony count and live tissue abundance. Between 2004 and 2010, the study population has shown more than 50% decline in live area from three main conditions: fragmentation, disease and snail predation. Approximately half of this decline occurred during the catastrophic 2005 hurricane season from which recovery has been minimal. Meanwhile, colony abundance has shown gradual decline throughout the study. Snail predation was the most prevalent condition. However, it ranked third in attributed tissue loss, behind breakage that occurred during the 2005 hurricane season, and disease. Thermal bleaching of A. palmata was not observed during this study. Because mortality continues to outpace recruitment and growth, intervention to ameliorate losses to the more manageable threats including predation and breakage could result in substantial conservation of live tissue, buying time for the abatement of less tractable threats to A. palmata recovery such as climate change and disease.

Stress induced by premature chromatin condensation triggers chromosome shattering and chromothripsis at DNA sites still replicating in micronuclei or multinucleate cells when primary nuclei enter mitosis.

PubMed

Terzoudi, Georgia I; Karakosta, Maria; Pantelias, Antonio; Hatzi, Vasiliki I; Karachristou, Ioanna; Pantelias, Gabriel

2015-11-01

Combination of next-generation DNA sequencing, single nucleotide polymorphism array analyses and bioinformatics has revealed the striking phenomenon of chromothripsis, described as complex genomic rearrangements acquired in a single catastrophic event affecting one or a few chromosomes. Via an unproven mechanism, it is postulated that mechanical stress causes chromosome shattering into small lengths of DNA, which are then randomly reassembled by DNA repair machinery. Chromothripsis is currently examined as an alternative mechanism of oncogenesis, in contrast to the present paradigm that considers a stepwise development of cancer. While evidence for the mechanism(s) underlying chromosome shattering during cancer development remains elusive, a number of hypotheses have been proposed to explain chromothripsis, including ionizing radiation, DNA replication stress, breakage-fusion-bridge cycles, micronuclei formation and premature chromosome compaction. In the present work, we provide experimental evidence on the mechanistic basis of chromothripsis and on how chromosomes can get locally shattered in a single catastrophic event. Considering the dynamic nature of chromatin nucleoprotein complex, capable of rapid unfolding, disassembling, assembling and refolding, we first show that chromatin condensation at repairing or replicating DNA sites induces the mechanical stress needed for chromosome shattering to ensue. Premature chromosome condensation is then used to visualize the dynamic nature of interphase chromatin and demonstrate that such mechanical stress and chromosome shattering can also occur in chromosomes within micronuclei or asynchronous multinucleate cells when primary nuclei enter mitosis. Following an aberrant mitosis, chromosomes could find themselves in the wrong place at the wrong time so that they may undergo massive DNA breakage and rearrangement in a single catastrophic event. Specifically, our results support the hypothesis that premature chromosome condensation induces mechanical stress and triggers shattering and chromothripsis in chromosomes or chromosome arms still undergoing DNA replication or repair in micronuclei or asynchronous multinucleate cells, when primary nuclei enter mitosis. Copyright © 2015 Elsevier B.V. All rights reserved.

Novel microbiological and spatial statistical methods to improve strength of epidemiological evidence in a community-wide waterborne outbreak.

PubMed

Jalava, Katri; Rintala, Hanna; Ollgren, Jukka; Maunula, Leena; Gomez-Alvarez, Vicente; Revez, Joana; Palander, Marja; Antikainen, Jenni; Kauppinen, Ari; Räsänen, Pia; Siponen, Sallamaari; Nyholm, Outi; Kyyhkynen, Aino; Hakkarainen, Sirpa; Merentie, Juhani; Pärnänen, Martti; Loginov, Raisa; Ryu, Hodon; Kuusi, Markku; Siitonen, Anja; Miettinen, Ilkka; Santo Domingo, Jorge W; Hänninen, Marja-Liisa; Pitkänen, Tarja

2014-01-01

Failures in the drinking water distribution system cause gastrointestinal outbreaks with multiple pathogens. A water distribution pipe breakage caused a community-wide waterborne outbreak in Vuorela, Finland, July 2012. We investigated this outbreak with advanced epidemiological and microbiological methods. A total of 473/2931 inhabitants (16%) responded to a web-based questionnaire. Water and patient samples were subjected to analysis of multiple microbial targets, molecular typing and microbial community analysis. Spatial analysis on the water distribution network was done and we applied a spatial logistic regression model. The course of the illness was mild. Drinking untreated tap water from the defined outbreak area was significantly associated with illness (RR 5.6, 95% CI 1.9-16.4) increasing in a dose response manner. The closer a person lived to the water distribution breakage point, the higher the risk of becoming ill. Sapovirus, enterovirus, single Campylobacter jejuni and EHEC O157:H7 findings as well as virulence genes for EPEC, EAEC and EHEC pathogroups were detected by molecular or culture methods from the faecal samples of the patients. EPEC, EAEC and EHEC virulence genes and faecal indicator bacteria were also detected in water samples. Microbial community sequencing of contaminated tap water revealed abundance of Arcobacter species. The polyphasic approach improved the understanding of the source of the infections, and aided to define the extent and magnitude of this outbreak.

Modeling solute clustering in the diffusion layer around a growing crystal.

PubMed

Shiau, Lie-Ding; Lu, Yung-Fang

2009-03-07

The mechanism of crystal growth from solution is often thought to consist of a mass transfer diffusion step followed by a surface reaction step. Solute molecules might form clusters in the diffusion step before incorporating into the crystal lattice. A model is proposed in this work to simulate the evolution of the cluster size distribution due to the simultaneous aggregation and breakage of solute molecules in the diffusion layer around a growing crystal in the stirred solution. The crystallization of KAl(SO(4))(2)12H(2)O from aqueous solution is studied to illustrate the effect of supersaturation and diffusion layer thickness on the number-average degree of clustering and the size distribution of solute clusters in the diffusion layer.

A lightweight solar array study

NASA Technical Reports Server (NTRS)

Josephs, R. H.

1977-01-01

A sample module was assembled to model a portion of a flexible extendable solar array, a type that promises to become the next generation of solar array design. The resulting study of this module is intended to provide technical support to the array designer for lightweight component selection, specifications, and tests. Selected from available lightweight components were 127-micron-thick wrap-around contacted solar cells, 34- micron-thick sputtered glass covers, and as a substrate a 13-micron-thick polyimide film clad with a copper printed circuit. Each component displayed weaknesses. The thin solar cells had excessive breakage losses. Sputtered glass cover adhesion was poor, and the covered cell was weaker than the cell uncovered. Thermal stresses caused some cell delamination from the model solar array substrate.

Numerical, micro-mechanical prediction of crack growth resistance in a fibre-reinforced/brittle matrix composite

NASA Technical Reports Server (NTRS)

Jenkins, Michael G.; Ghosh, Asish; Salem, Jonathan A.

1990-01-01

Micromechanics fracture models are incorporated into three distinct fracture process zones which contribute to the crack growth resistance of fibrous composites. The frontal process zone includes microcracking, fiber debonding, and some fiber failure. The elastic process zone is related only to the linear elastic creation of new matrix and fiber fracture surfaces. The wake process zone includes fiber bridging, fiber pullout, and fiber breakage. The R-curve predictions of the model compare well with empirical results for a unidirectional, continuous fiber C/C composite. Separating the contributions of each process zone reveals the wake region to contain the dominant crack growth resistance mechanisms. Fractography showed the effects of the micromechanisms on the macroscopic fracture behavior.

Numerical simulation of abutment pressure redistribution during face advance

NASA Astrophysics Data System (ADS)

Klishin, S. V.; Lavrikov, S. V.; Revuzhenko, A. F.

2017-12-01

The paper presents numerical simulation data on the abutment pressure redistribution in rock mass during face advance, including isolines of maximum shear stress and pressure epures. The stress state of rock in the vicinity of a breakage heading is calculated by the finite element method using a 2D nonlinear model of a structurally heterogeneous medium with regard to plasticity and internal self-balancing stress. The thus calculated stress field is used as input data for 3D discrete element modeling of the process. The study shows that the abutment pressure increases as the roof span extends and that the distance between the face breast and the peak point of this pressure depends on the elastoplastic properties and internal self-balancing stress of a rock medium.

The genome-wide DNA sequence specificity of the anti-tumour drug bleomycin in human cells.

PubMed

Murray, Vincent; Chen, Jon K; Tanaka, Mark M

2016-07-01

The cancer chemotherapeutic agent, bleomycin, cleaves DNA at specific sites. For the first time, the genome-wide DNA sequence specificity of bleomycin breakage was determined in human cells. Utilising Illumina next-generation DNA sequencing techniques, over 200 million bleomycin cleavage sites were examined to elucidate the bleomycin genome-wide DNA selectivity. The genome-wide bleomycin cleavage data were analysed by four different methods to determine the cellular DNA sequence specificity of bleomycin strand breakage. For the most highly cleaved DNA sequences, the preferred site of bleomycin breakage was at 5'-GT* dinucleotide sequences (where the asterisk indicates the bleomycin cleavage site), with lesser cleavage at 5'-GC* dinucleotides. This investigation also determined longer bleomycin cleavage sequences, with preferred cleavage at 5'-GT*A and 5'- TGT* trinucleotide sequences, and 5'-TGT*A tetranucleotides. For cellular DNA, the hexanucleotide DNA sequence 5'-RTGT*AY (where R is a purine and Y is a pyrimidine) was the most highly cleaved DNA sequence. It was striking that alternating purine-pyrimidine sequences were highly cleaved by bleomycin. The highest intensity cleavage sites in cellular and purified DNA were very similar although there were some minor differences. Statistical nucleotide frequency analysis indicated a G nucleotide was present at the -3 position (relative to the cleavage site) in cellular DNA but was absent in purified DNA.

Flavonoids-induced redox cycling of copper ions leads to generation of reactive oxygen species: A potential role in cancer chemoprevention.

PubMed

Arif, Hussain; Sohail, Aamir; Farhan, Mohd; Rehman, Ahmed Abdur; Ahmad, Aamir; Hadi, S M

2018-01-01

Flavonoids, a class of polyphenols are known to be effective inducers of apoptosis and cytotoxicity in cancer cells. It is believed that antioxidant activity of polyphenols cannot fully account for induction of apoptosis and chemotherapeutic prevention in various cancers. In this article, by employing single cell alkaline gel electrophoresis (comet assay), we established that antioxidants, flavonoids such as (myricetin=MN, fisetin=FN, quercetin=QN, kaempferol=KL and galangin=GN) can cause cellular DNA breakage, also act as pro-oxidant in presence of transition metal ion such as copper. It was observed that the extent of cellular DNA breakage was found significantly higher in presence of copper. Hydroxyl radicals are generated as a sign of flavonoids' pro-oxidant nature through redox recycling of copper ions. Further, a dose-dependent inhibition of proliferation of breast cancer cells MDA-MB-231 by MN was found leading to pro-oxidant cell death, as assessed by MTT assay. Since levels of copper are considerably elevated in tissue, cell and serum during various malignancies, suggesting that cancer cells would be more subject to copper induced oxidative DNA breakage. Such a copper dependent pro-oxidant cytotoxic mechanism better explains the anticancer activity and preferential cytotoxicity of dietary phytochemicals against cancer cells. Copyright © 2017 Elsevier B.V. All rights reserved.

[Subtalar arthrodesis].

PubMed

Fuhrmann, R A; Pillukat, T

2016-06-01

Realignment and stabilization of the hindfoot by subtalar joint arthrodesis. Idiopathic/posttraumatic arthritis, inflammatory arthritis of the subtalar joint with/without hindfoot malalignment. Optional flatfoot/cavovarus foot reconstruction. Inflammation, vascular disturbances, nicotine abuse. Approach dependent on assessment. Lateral approach: Supine position. Incision above the sinus tarsi. Exposure of subtalar joint. Removal of cartilage and breakage of the subchondral sclerosis. In valgus malalignment, interposition of corticocancellous bone segment; in varus malalignment resection of bone segment from the calcaneus. Reposition and temporarily stabilization with Kirschner wires. Imaging of hindfoot alignment. Stabilization with cannulated screws. Posterolateral approach: Prone position. Incision parallel to the lateral Achilles tendon border. Removal of cartilage and breakage of subchondral sclerosis. Medial approach: Supine position. Incision just above and parallel to the posterior tibial tendon. Removal of cartilage and breakage of subchondral sclerosis. Stabilization with screws. Lower leg walker with partial weightbearing. Active exercises of the ankle. After a 6‑week X‑ray, increase of weightbearing. Full weightbearing not before 8 weeks; with interpositioning bone grafts not before 10-12 weeks. Stable walking shoes. Active mobilization of the ankle. Of 43 isolated subtalar arthrodesis procedures, 5 wound healing disorders and no infections developed. Significantly improved AOFAS hindfood score. Well-aligned heel observed in 34 patients; 5 varus and 2 valgus malalignments. Sensory disturbances in 8 patients; minor ankle flexion limitations. Full bone healing in 36 subtalar joints, pseudarthrosis in 4 patients.

ZERODUR - bending strength: review of achievements

NASA Astrophysics Data System (ADS)

Hartmann, Peter

2017-08-01

Increased demand for using the glass ceramic ZERODUR® with high mechanical loads called for strength data based on larger statistical samples. Design calculations for failure probability target value below 1: 100 000 cannot be made reliable with parameters derived from 20 specimen samples. The data now available for a variety of surface conditions, ground with different grain sizes and acid etched for full micro crack removal, allow stresses by factors four to ten times higher than before. The large sample revealed that breakage stresses of ground surfaces follow the three parameter Weibull distribution instead of the two parameter version. This is more reasonable considering that the micro cracks of such surfaces have a maximum depth which is reflected in the existence of a threshold breakage stress below which breakage probability is zero. This minimum strength allows calculating minimum lifetimes. Fatigue under load can be taken into account by using the stress corrosion coefficient for the actual environmental humidity. For fully etched surfaces Weibull statistics fails. The precondition of the Weibull distribution, the existence of one unique failure mechanism, is not given anymore. ZERODUR® with fully etched surfaces free from damages introduced after etching endures easily 100 MPa tensile stress. The possibility to use ZERODUR® for combined high precision and high stress application was confirmed by the successful launch and continuing operation of LISA Pathfinder the precursor experiment for the gravitational wave antenna satellite array eLISA.

How often do condoms fail? : A cross-sectional study exploring incomplete use of condoms, condom failures, and other condom problems among Black and White MSM in the Southern U.S

PubMed Central

Hernández-Romieu, Alfonso C.; Siegler, Aaron; Sullivan, Patrick S.; Crosby, Richard; Rosenberg, Eli S.

2015-01-01

Objectives Compare the occurrence of risk-inducing condom events (condom failures and incomplete use) and the frequency of their antecedents (condom errors, fit/feel problems, and erection problems) between Black and White MSM, and determine the associations between risk-inducing condom events and their antecedents. Methods We studied cross-sectional data of 475 MSM who indicated using a condom as an insertive partner in the previous 6 months enrolled in a cohort study in Atlanta, GA. Results Nearly 40% of Black MSM reported breakage or incomplete use, and they were more likely to report breakage, early removal, and delayed application of a condom than White MSM. Only 31% and 54% of MSM reported correct condom use and suboptimal fit/feel of a condom respectively. The use of oil-based lubricants and suboptimal fit/feel were associated with higher odds of reporting breakage (P = 0.009). Suboptimal fit/feel was also associated with higher odds of incomplete use of condoms (P <0.0001). Conclusions Incomplete use of condoms and condom failures were especially common among Black MSM. Our findings indicate that condoms likely offered them less protection against HIV/STI when compared to White MSM. More interventions are needed, particularly addressing the use of oil-based lubricants and suboptimal fit/feel of condoms. PMID:25080511

Sensitivity to chromosomal breakage as risk factor in young adults with oral squamous cell carcinoma.

PubMed

Braakhuis, Boudewijn J M; Nieuwint, Aggie W M; Oostra, Anneke B; Joenje, Hans; Flach, Géke B; Graveland, A Peggy; Brakenhoff, Ruud H; Leemans, C René

2016-03-01

Oral squamous cell carcinoma (OSCC) may develop in young adults. In contrast to older patients, the well-known etiological factors, exposure to tobacco and alcohol, play a minor role in the carcinogenesis in this patient group. It has been suggested that an intrinsic susceptibility to environmental genotoxic exposures plays a role in the development of OSCC in these patients. The hypothesis was tested whether young OSCC patients have an increased sensitivity to induced chromosomal damage. Fourteen OSCC patients with an average age of 32 years (range 20-42) were selected. Peripheral blood lymphocytes and skin fibroblasts of patients and 14 healthy controls were subjected to the chromosome breakage test with Mitomycin C. This test is routinely used to identify Fanconi anemia patients, who are well-known for their inherited high sensitivity to this type of DNA damage, but also for the high risk to develop OSCC. Human papilloma virus status of the carcinomas was also determined. None of the 14 young patients with OSCC had an increased response in the MMC-chromosomal breakage test. All tumors tested negative for human papilloma virus. No evidence was obtained for the existence of a constitutional hypersensitivity to DNA chromosomal damage as a potential risk factor for OSCC in young adults. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Multiplex single-tube screening for mutations in the Nijmegen Breakage Syndrome (NBS1) gene in Hodgkin's and non-Hodgkin's lymphoma patients of Slavic origin.

PubMed

Soucek, Pavel; Gut, Ivan; Trneny, Marek; Skovlund, Eva; Grenaker Alnaes, Grethe; Kristensen, Tom; Børresen-Dale, Anne-Lise; Kristensen, Vessela N

2003-05-01

Patients with Nijmegen Breakage Syndrome (NBS) have a high risk to develop malignant diseases, most frequently B-cell lymphomas. It has been demonstrated that this chromosomal breakage syndrome results from mutations in the NBS1 gene that cause either a loss of full-length protein expression or expression of a variant protein. A large proportion of the known NBS patients are of Slavic origin who carry a major founder mutation 657del5 in exon 6 of the NBS1 gene. The prevalence of this mutation in Slav populations is reported to be high, possibly contributing to higher cancer risk in these populations. Therefore, if mutations in NBS1 are associated with higher risk of developing lymphoid cancers it would be most likely to be observed in these populations. A multiplex assay for four of the most frequent NBS1 mutations was designed and a series of 119 lymphoma patients from Slavic origin as well as 177 healthy controls were tested. One of the patients was a heterozygote carrier of the ACAAA deletion mutation in exon 6 (1/119). No mutation was observed in the control group, despite the reported high frequency (1/177). The power of this study was 30% to detect a relative risk of 2.0.

Genetics Home Reference: Warsaw breakage syndrome

MedlinePlus

... helicase. Helicases are enzymes that attach (bind) to DNA and temporarily unwind the two spiral strands (double helix) of the DNA molecule. This unwinding is necessary for copying ( replicating ) ...

657del5 mutation in the NBS1 gene is associated with Nijmegen breakage syndrome in a Turkish family.

PubMed

Tekin, Mustafa; Doğu, F; Taçyíldiz, N; Akar, E; Ikincioğullari, A; Oğur, G; Yavuz, G; Babacan, E; Akar, N

2002-07-01

We report on a consanguineous Turkish family whose first son died of anal atresia and whose second son presented with severe pre- and post-natal growth retardation as well as striking microcephaly, immunodeficiency, congenital heart disease, chromosomal instability and rhabdomyosarcoma in the anal region. The proband was found to carry the homozygous 657del5 mutation in the NBS1 gene, which is responsible for Nijmegen breakage syndrome (NBS) in most of the Slav populations. Our family, the first diagnosed with NBS in the Turkish population, represents one of the most severely affected examples of the syndrome, with profound pre- and post-natal growth retardation associated with structural abnormalities, and expands the clinical spectrum of this rare disorder.

Gas production in the radiolysis of Poly(dimethysiloxanes)

NASA Astrophysics Data System (ADS)

LaVerne, Jay A.; Tratnik, Nicole A. I.; Sasgen, Andrea

2018-01-01

A variety of small poly(dimethyl siloxanes) were irradiated with γ-rays followed by the determination of the production of methane and molecular hydrogen and characterization of spectroscopic changes in the medium. The yields of methane was found to be about twice that of molecular hydrogen indicating that breakage of the C-Si bond occurs at a frequency comparable to the breakage of the C-H bond. Both yields slowly decrease with increasing molecular weight of the medium. The presence of oxygen decreases the yield of both gases suggesting radical precursors to methane and molecular hydrogen, presumably the methyl radical and H atom, respectively. Temperature gravimetric analysis and UV-visible spectroscopy both suggest the formation of higher molecular weight compounds with radiolysis, which agrees with bond loss and formation observed in infrared spectroscopy.

Fully Coupled Micro/Macro Deformation, Damage, and Failure Prediction for SiC/Ti-15-3 Laminates

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.; Lerch, Brad A.

2001-01-01

The deformation, failure, and low cycle fatigue life of SCS-6/Ti-15-3 composites are predicted using a coupled deformation and damage approach in the context of the analytical generalized method of cells (GMC) micromechanics model. The local effects of inelastic deformation, fiber breakage, fiber-matrix interfacial debonding, and fatigue damage are included as sub-models that operate on the micro scale for the individual composite phases. For the laminate analysis, lamination theory is employed as the global or structural scale model, while GMC is embedded to operate on the meso scale to simulate the behavior of the composite material within each laminate layer. While the analysis approach is quite complex and multifaceted, it is shown, through comparison with experimental data, to be quite accurate and realistic while remaining extremely efficient.

Local Debonding and Fiber Breakage in Composite Materials Modeled Accurately

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2001-01-01

A prerequisite for full utilization of composite materials in aerospace components is accurate design and life prediction tools that enable the assessment of component performance and reliability. Such tools assist both structural analysts, who design and optimize structures composed of composite materials, and materials scientists who design and optimize the composite materials themselves. NASA Glenn Research Center's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) software package (http://www.grc.nasa.gov/WWW/LPB/mac) addresses this need for composite design and life prediction tools by providing a widely applicable and accurate approach to modeling composite materials. Furthermore, MAC/GMC serves as a platform for incorporating new local models and capabilities that are under development at NASA, thus enabling these new capabilities to progress rapidly to a stage in which they can be employed by the code's end users.

Efficacy and Safety of Pueraria lobata Extract in Gray Hair Prevention: A Randomized, Double-Blind, Placebo-Controlled Study

PubMed Central

Jo, Seong Jin; Shin, Hyoseung; Paik, Seung Hwan; Na, Sun Jae; Jin, Yingji; Park, Won Seok; Kim, Su Na

2013-01-01

Background Graying of hair-a sign of aging-raises cosmetic concerns. Individuals with gray hair often look older than others their age; therefore, some dye their hair for aesthetic purposes. However, hair colorants can induce many problems including skin irritation, allergic reaction and hair-breakage. Objective This randomized, double-blind clinical trial was performed in order to examine the effects of APHG-1001, a compound including an extract from Pueraria lobata, on graying hair. Methods A total of 44 female subjects were randomly treated with either APHG-1001 or placebo twice daily for 24 weeks. Using the phototrichogram analysis, a count of newly developed gray hair was estimated. Investigator assessment and subject self-assessment were also performed in order to evaluate the efficacy of the compound. Results The mean number of newly developed gray hair at 24 weeks was 6.3/cm2 in the APHG-1001 group and 11.4/cm2 in the placebo group; the difference was statistically significant (p<0.05). However, the investigator assessment and subject self-assessment did not show any significant change in the gross appearance of hair grayness by the end of the study. No severe adverse events in either group were observed. Moreover, the incidence of adverse events did not differ between the groups. Conclusion This clinical trial revealed that APHG-1001, which contains an extract of P. lobata, could prevent the development of new gray hair without any remarkable adverse effects. Thus, it can be considered as a viable treatment option for the prevention of gray hair. PMID:23717015

Modeling wood dynamics, jam formation, and sediment storage in a gravel-bed stream

NASA Astrophysics Data System (ADS)

Eaton, B. C.; Hassan, M. A.; Davidson, S. L.

2012-12-01

In small and intermediate sized streams, the interaction between wood and bed material transport often determines the nature of the physical habitat, which in turn influences the health of the stream's ecosystem. We present a stochastic model that can be used to simulate the effects on physical habitat of forest fires, climate change, and other environmental disturbances that alter wood recruitment. The model predicts large wood (LW) loads in a stream as well as the volume of sediment stored by the wood; while it is parameterized to describe gravel bed streams similar to a well-studied field prototype, Fishtrap Creek, British Columbia, it can be calibrated to other systems as well. In the model, LW pieces are produced and modified over time as a result of random tree-fall, LW breakage, LW movement, and piece interaction to form LW jams. Each LW piece traps a portion of the annual bed material transport entering the reach and releases the stored sediment when the LW piece is entrained and moved. The equations governing sediment storage are based on a set of flume experiments also scaled to the field prototype. The model predicts wood loads ranging from 70 m3/ha to more than 300 m3/ha, with a mean value of 178 m3/ha: both the range and the mean value are consistent with field data from streams with similar riparian forest types and climate. The model also predicts an LW jam spacing that is consistent with field data. Furthermore, our modeling results demonstrate that the high spatial and temporal variability in sediment storage, sediment transport, and channel morphology associated with LW-dominated streams occurs only when LW pieces interact and form jams. Model runs that do not include jam formation are much less variable. These results suggest that river restoration efforts using engineered LW pieces that are fixed in place and not permitted to interact will be less successful at restoring the geomorphic processes responsible for producing diverse, productive physical habitats than efforts using LW pieces that are free to move, interact, and form LW jams.

Anesthetic cartridge system under evaluation.

PubMed

Cooley, R L; Lubow, R M

1981-01-01

The problem of glass breakage in the local anesthetic cartridge system was evaluated under laboratory conditions with a mechanical testing machine. The anticipated breakage of the glass did not occur with any frequency, as the rubber stopper produced more uniform failures of the system. The glass cartridge appeared to be quite reliable and resistant to breakage.Local anesthetics have been used for many years to provide patients temporary freedom from pain. Local anesthetic solutions are in wide use in both dentistry and medicine and are the most frequently used drugs in dentistry. Various estimates place the number of injections at approximately one half million daily or 125 million injections per year.These drugs and the armamentarium necessary to administer them have proven to be safe and reliable. Only rarely are there reports of sensitivity to the anesthetic solution or breakage of needles.. Sterility of the solutions has not been a problem as they are carefully processed and evaluated at the factory. Although there are sporadic reports of loss of sterility, this has been attributed to the reuse of the anesthetic cartridges on more than one patient. Monheim states "The success of the cartridge system in dentistry has been due to the sincerity, honesty, and high standards of the manufacturers in giving the profession a near-perfect product." However, on occassion a glass cartridge will break or shatter when inserting the harpoon into the rubber stopper or even during injection. Cooley et al reported on eye injuries occurring in the dental office, one of which was due to glass from a local anesthetic cartridge that exploded and propelled particles into the patient's eye. Forrest evaluated syringes, needles, and cartridges and reported that one brand (made in Britain) fractured more often than any other, but that the fracture rate was too low to be of any consequence.It is apparent that glass cartridges will fracture or burst from time to time. This study evaluates the cartridge system with carefully controlled laboratory procedures. The cartridges were tested under various pressures and conditions in an attempt to determine the causes of failure and when such failure may be anticipated.

Physical and thermal properties of blood storage bags: implications for shipping frozen components on dry ice.

PubMed

Hmel, Peter J; Kennedy, Anthony; Quiles, John G; Gorogias, Martha; Seelbaugh, Joseph P; Morrissette, Craig R; Van Ness, Kenneth; Reid, T J

2002-07-01

Frozen blood components are shipped on dry ice. The lower temperature (-70 degrees C in contrast to usual storage at -30 degrees C) and shipping conditions may cause a rent in the storage bag, breaking sterility and rendering the unit useless. The rate of loss can reach 50 to 80 percent. To identify those bags with lower probability of breaking during shipment, the thermal and physical properties of blood storage bags were examined. Blood storage bags were obtained from several manufacturers and were of the following compositions: PVC with citrate, di-2-ethylhexylphthalate (DEHP), or tri-2-ethylhexyl-tri-mellitate (TEHTM) plasticizer; polyolefin (PO); poly(ethylene-co-vinyl acetate) (EVA); or fluorinated polyethylene propylene (FEP). The glass transition temperature (Tg) of each storage bag was determined. Bag thickness and measures of material strength (tensile modulus [MT] and time to achieve 0.5 percent strain [T0.5%]) were evaluated. M(T) and T0.5% measurements were made at 25 and -70 degrees C. Response to applied force at -70 degrees C was measured using an impact testing device and a drop test. The Tg of the bags fell into two groups: 70 to 105 degrees C (PO, FEP) and -50 to -17 degrees C (PVC with plasticizer, EVA). Bag thickness ranged from 0.14 to 0.41 mm. Compared to other materials, the ratios of M(T) and T0.5% for PVC bags were increased (p < or = 0.001) indicating that structural changes for PVC were more pronounced upon cooling from 25 to -70 degrees C. Bags containing EVA were more shock resistant, resulting in the lowest rate of breakage (10% breakage) when compared with PO (60% breakage, p = 0.0573) or PVC (100% breakage, p = 0.0001). Blood storage bags made of EVA appear better suited for shipping frozen blood components on dry ice and are cost-effective replacements for PVC bags. For the identification of blood storage bags meeting specific storage requirements, physical and thermal analyses of blood storage bags may be useful and remove empiricism from the process.

The radiation hypersensitivity of cells at mitosis.

PubMed

Stobbe, C C; Park, S J; Chapman, J D

2002-12-01

Mitotic cells are hypersensitive to ionizing radiation, exhibiting single-hit inactivation coefficients near to those of repair deficient cell lines and lymphocytes. To elucidate possible mechanisms for this hypersensitivity, the kinetics of oxygen radiosensitization, the proportion of indirect effect by OH radicals and the kinetics of radiation-induced DNA strand breakage in the chromatin of mitotic cells were investigated. Synchronized populations of >90% mitotic HT-29 cells were obtained by the mitotic shake-off method. Cells were irradiated at < or =4 degrees C with (137)Cs gamma-rays. Cellular oxygen concentration was varied by gassing cell suspensions prior to and during irradiation with mixtures of pure N(2) that contained 5% CO(2) and measured quantities of O(2). The indirect effect of OH radicals was investigated with the radical scavenger, DMSO. DNA strand breakage was measured by the comet assay. Mitotic HT-29 cell inactivation is well described by a single-hit inactivation coefficient (alpha) of 1.14 +/- 0.06 Gy(-1). The oxygen enhancement ratio of mitotic cells (at 10% survival) was found to be approximately 2.0, significantly lower than the value of 2.8 measured for interphase (asynchronous) cells. More than 60% of mitotic cell killing was eliminated when the media contained 2 M DMSO, indicating that indirect effect is as important in the killing of mitotic cells as it is for interphase cells. The chromatin in mitotic cells was found to be ~2.8 times more sensitive to radiation-induced DNA single-strand breakage than the chromatin of interphase cells. The alpha-inactivation coefficient of mitotic HT-29 cells was ~30 times larger than that of interphase cells. Mitotic cell chromatin appears to contain intrinsic DNA breaks that are not lethal. In addition, chromatin in mitotic cells was found to be more susceptible to radiation-induced DNA strand-breakage than the dispersed chromatin of interphase cells. How the enhanced production of these simple DNA lesions (that are usually reparable) translates into the lethal (non-reparable) events associated with alpha-inactivation is not known. The compaction/dispersion status of DNA throughout the cell cycle appears to be an important factor for determining intrinsic cell radiosensitivity and might be manipulated for radiotherapeutic advantage.

47 CFR 80.863 - Antenna system.

Code of Federal Regulations, 2010 CFR

2010-10-01

... suspended between masts or other supports liable to whipping, a safety link which, under heavy stress, will operate to greatly reduce such stress without breakage of the antenna, the halyards, or other antenna...

Modified Withdrawal Slot Increases Silicon Production

NASA Technical Reports Server (NTRS)

Piotrowsky, P. A.; Duncan, C. S.

1988-01-01

New shape reduces ribbon breakage and resulting idle time. Shape for slot through which single-crystal silicon ribbon pulled from melt increases productivity. Reduces tendency of emerging ribbon to grow thin and break.

The investigation of tethered satellite system dynamics

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1985-01-01

The tether control law to retrieve the satellite was modified in order to have a smooth retrieval trajectory of the satellite that minimizes the thruster activation. The satellite thrusters were added to the rotational dynamics computer code and a preliminary control logic was implemented to simulate them during the retrieval maneuver. The high resolution computer code for modelling the three dimensional dynamics of untensioned tether, SLACK3, was made fully operative and a set of computer simulations of possible tether breakages was run. The distribution of the electric field around an electrodynamic tether in vacuo severed at some length from the shuttle was computed with a three dimensional electrodynamic computer code.

Grain size distribution in sheared polycrystals

NASA Astrophysics Data System (ADS)

Sarkar, Tanmoy; Biswas, Santidan; Chaudhuri, Pinaki; Sain, Anirban

2017-12-01

Plastic deformation in solids induced by external stresses is of both fundamental and practical interest. Using both phase field crystal modeling and molecular dynamics simulations, we study the shear response of monocomponent polycrystalline solids. We subject mesocale polycrystalline samples to constant strain rates in a planar Couette flow geometry for studying its plastic flow, in particular its grain deformation dynamics. As opposed to equilibrium solids where grain dynamics is mainly driven by thermal diffusion, external stress/strain induce a much higher level of grain deformation activity in the form of grain rotation, coalescence, and breakage, mediated by dislocations. Despite this, the grain size distribution of this driven system shows only a weak power-law correction to its equilibrium log-normal behavior. We interpret the grain reorganization dynamics using a stochastic model.

Genetics Home Reference: Grange syndrome

MedlinePlus

... fragile bones that are prone to breakage, and learning disabilities. Most people with this disorder also have heart ... of Grange syndrome , such as bone abnormalities and learning disabilities. Learn more about the gene associated with Grange ...

Proposed method for determining the thickness of glass in solar collector panels

NASA Technical Reports Server (NTRS)

Moore, D. M.

1980-01-01

An analytical method was developed for determining the minimum thickness for simply supported, rectangular glass plates subjected to uniform normal pressure environmental loads such as wind, earthquake, snow, and deadweight. The method consists of comparing an analytical prediction of the stress in the glass panel to a glass breakage stress determined from fracture mechanics considerations. Based on extensive analysis using the nonlinear finite element structural analysis program ARGUS, design curves for the structural analysis of simply supported rectangular plates were developed. These curves yield the center deflection, center stress and corner stress as a function of a dimensionless parameter describing the load intensity. A method of estimating the glass breakage stress as a function of a specified failure rate, degree of glass temper, design life, load duration time, and panel size is also presented.

The NBS1-Treacle complex controls ribosomal RNA transcription in response to DNA damage

PubMed Central

Larsen, Dorthe H; Hari, Flurina; Clapperton, Julie A; Gwerder, Myriam; Gutsche, Katrin; Altmeyer, Matthias; Jungmichel, Stephanie; Toledo, Luis I; Fink, Daniel; Rask, Maj-Britt; Grøfte, Merete; Lukas, Claudia; Nielsen, Michael L; Smerdon, Stephen J; Lukas, Jiri; Stucki, Manuel

2016-01-01

Chromosome breakage elicits transient silencing of ribosomal RNA synthesis, but the mechanisms involved remained elusive. Here we discover an in-trans signaling mechanism that triggers pan-nuclear silencing of rRNA transcription in response to DNA damage. This is associated with transient recruitment of the Nijmegen breakage syndrome protein 1 (NBS1), a central regulator of DNA damage responses, into the nucleoli. We further identified TCOF1-Treacle, a nucleolar factor implicated in ribosome biogenesis and mutated in Treacher Collins syndrome, as an interaction partner of NBS1, and demonstrate that NBS1 translocation and accumulation in the nucleoli is Treacle-dependent. Finally, we provide evidence that Treacle-mediated NBS1 recruitment into the nucleoli regulates rRNA silencing in-trans in the presence of distant chromosome breaks. PMID:25064736

The NBS1-Treacle complex controls ribosomal RNA transcription in response to DNA damage.

PubMed

Larsen, Dorthe H; Hari, Flurina; Clapperton, Julie A; Gwerder, Myriam; Gutsche, Katrin; Altmeyer, Matthias; Jungmichel, Stephanie; Toledo, Luis I; Fink, Daniel; Rask, Maj-Britt; Grøfte, Merete; Lukas, Claudia; Nielsen, Michael L; Smerdon, Stephen J; Lukas, Jiri; Stucki, Manuel

2014-08-01

Chromosome breakage elicits transient silencing of ribosomal RNA synthesis, but the mechanisms involved remained elusive. Here we discover an in trans signalling mechanism that triggers pan-nuclear silencing of rRNA transcription in response to DNA damage. This is associated with transient recruitment of the Nijmegen breakage syndrome protein 1 (NBS1), a central regulator of DNA damage responses, into the nucleoli. We further identify TCOF1 (also known as Treacle), a nucleolar factor implicated in ribosome biogenesis and mutated in Treacher Collins syndrome, as an interaction partner of NBS1, and demonstrate that NBS1 translocation and accumulation in the nucleoli is Treacle dependent. Finally, we provide evidence that Treacle-mediated NBS1 recruitment into the nucleoli regulates rRNA silencing in trans in the presence of distant chromosome breaks.

Radiation-induced genomic instability and its implications for radiation carcinogenesis

NASA Technical Reports Server (NTRS)

Huang, Lei; Snyder, Andrew R.; Morgan, William F.

2003-01-01

Radiation-induced genomic instability is characterized by an increased rate of genetic alterations including cytogenetic rearrangements, mutations, gene amplifications, transformation and cell death in the progeny of irradiated cells multiple generations after the initial insult. Chromosomal rearrangements are the best-characterized end point of radiation-induced genomic instability, and many of the rearrangements described are similar to those found in human cancers. Chromosome breakage syndromes are defined by chromosome instability, and individuals with these diseases are cancer prone. Consequently, chromosomal instability as a phenotype may underlie some fraction of those changes leading to cancer. Here we attempt to relate current knowledge regarding radiation-induced chromosome instability with the emerging molecular information on the chromosome breakage syndromes. The goal is to understand how genetic and epigenetic factors might influence the onset of chromosome instability and the role of chromosomal instability in carcinogenesis.

Permeability Changes of Integrin-Containing Multivesicular Structures Triggered by Picornavirus Entry

PubMed Central

Soonsawad, Pan; Weerachatyanukul, Wattana; Rintanen, Nina; Espinoza, Juan; McNerney, Gregory; Marjomäki, Varpu; Cheng, R. Holland

2014-01-01

Cellular uptake of clustered α2β1-integrin induces the formation of membrane compartments that subsequently mature into a multivesicular body (MVB). Enhanced internalization mediated by clustered integrins was observed upon infection by the picornavirus echovirus 1 (EVI). We elucidated the structural features of virus-induced MVBs (vMVBs) in comparison to antibody-induced control MVBs (mock infection) by means of high-pressure cryo fixation of cells followed by immuno electron tomography during early entry of the virus. Three-dimensional tomograms revealed a marked increase in the size and complexity of these vMVBs and the intraluminal vesicles (ILVs) at 2 and 3.5 hours post infection (p.i.), in contrast to the control MVBs without virus. Breakages in the membranes of vMVBs were detected from tomograms after 2 and especially after 3.5 h suggesting that these breakages could facilitate the genome release to the cytoplasm. The in situ neutral-red labeling of viral genome showed that virus uncoating starts as early as 30 min p.i., while an increase of permeability was detected in the vMVBs between 1 and 3 hours p.i., based on a confocal microscopy assay. Altogether, the data show marked morphological changes in size and permeability of the endosomes in the infectious entry pathway of this non-enveloped enterovirus and suggest that the formed breakages facilitate the transfer of the genome to the cytoplasm for replication. PMID:25299706

Periodontal health and compliance: A comparison between Essix and Hawley retainers.

PubMed

Manzon, Licia; Fratto, Giovanni; Rossi, Eros; Buccheri, Alfio

2018-06-01

Many studies on removable retainers have focused on retention efficacy and characteristics. However, studies on plaque accumulation, periodontal health, breakages, and patient compliance are still lacking. Thus, in this study, we aimed at evaluating these parameters in 2 groups of young patients wearing Essix or Hawley retainers for a 6-month period. Seventy subjects were included. Periodontal health was investigated by measuring the plaque, gingival, calculus, and bleeding on probing indexes. Evaluations were performed at 1, 3, and 6 months of wearing. Accumulation of plaque on the retainers was also evaluated. Furthermore, compliance on wearing retainers and breakage data were collected by specific questionnaires. Subjects wearing Essix retainers had significantly higher levels of plaque, gingival, and calculus indexes and increased percentages of bleeding sites, compared with subjects wearing Hawley retainers. The Essix group also had increased accumulations of plaque and calculus on the retainers. Nonetheless, subjects of the Essix group had better overall experiences, self-perceptions, and comfort compared with those of the Hawley group. Essix retainers had higher incidences of little and serious breakages compared with Hawley retainers. Our results suggest that Essix retainers are well accepted by patients for their esthetic and oral comfort characteristics. However, Essix retainers may cause greater accumulations of plaque on both teeth and retainers, presumably because of inhibition of the cleaning effect of saliva caused by the thermoplastic material or the reduced opportunity for good hygiene on the retainer. Copyright © 2018 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Engineering Upper Hinge Improves Stability and Effector Function of a Human IgG1

PubMed Central

Yan, Boxu; Boyd, Daniel; Kaschak, Timothy; Tsukuda, Joni; Shen, Amy; Lin, Yuwen; Chung, Shan; Gupta, Priyanka; Kamath, Amrita; Wong, Anne; Vernes, Jean-Michel; Meng, Gloria Y.; Totpal, Klara; Schaefer, Gabriele; Jiang, Guoying; Nogal, Bartek; Emery, Craig; Vanderlaan, Martin; Carter, Paul; Harris, Reed; Amanullah, Ashraf

2012-01-01

Upper hinge is vulnerable to radical attacks that result in breakage of the heavy-light chain linkage and cleavage of the hinge of an IgG1. To further explore mechanisms responsible for the radical induced hinge degradation, nine mutants were designed to determine the roles that the upper hinge Asp and His play in the radical reactions. The observation that none of these substitutions could inhibit the breakage of the heavy-light chain linkage suggests that the breakage may result from electron transfer from Cys231 directly to the heavy-light chain linkage upon radical attacks, and implies a pathway separate from His229-mediated hinge cleavage. On the other hand, the substitution of His229 with Tyr showed promising advantages over the native antibody and other substitutions in improving the stability and function of the IgG1. This substitution inhibited the hinge cleavage by 98% and suggests that the redox active nature of Tyr did not enable it to replicate the ability of His to facilitate radical induced degradation. We propose that the lower redox potential of Tyr, a residue that may be the ultimate sink for oxidizing equivalents in proteins, is responsible for the inhibition. More importantly, the substitution increased the antibody's binding to FcγRIII receptors by 2–3-fold, and improved ADCC activity by 2-fold, while maintaining a similar pharmacokinetic profile with respect to the wild type. Implications of these observations for antibody engineering and development are discussed. PMID:22203673

Engineering upper hinge improves stability and effector function of a human IgG1.

PubMed

Yan, Boxu; Boyd, Daniel; Kaschak, Timothy; Tsukuda, Joni; Shen, Amy; Lin, Yuwen; Chung, Shan; Gupta, Priyanka; Kamath, Amrita; Wong, Anne; Vernes, Jean-Michel; Meng, Gloria Y; Totpal, Klara; Schaefer, Gabriele; Jiang, Guoying; Nogal, Bartek; Emery, Craig; Vanderlaan, Martin; Carter, Paul; Harris, Reed; Amanullah, Ashraf

2012-02-17

Upper hinge is vulnerable to radical attacks that result in breakage of the heavy-light chain linkage and cleavage of the hinge of an IgG1. To further explore mechanisms responsible for the radical induced hinge degradation, nine mutants were designed to determine the roles that the upper hinge Asp and His play in the radical reactions. The observation that none of these substitutions could inhibit the breakage of the heavy-light chain linkage suggests that the breakage may result from electron transfer from Cys(231) directly to the heavy-light chain linkage upon radical attacks, and implies a pathway separate from His(229)-mediated hinge cleavage. On the other hand, the substitution of His(229) with Tyr showed promising advantages over the native antibody and other substitutions in improving the stability and function of the IgG1. This substitution inhibited the hinge cleavage by 98% and suggests that the redox active nature of Tyr did not enable it to replicate the ability of His to facilitate radical induced degradation. We propose that the lower redox potential of Tyr, a residue that may be the ultimate sink for oxidizing equivalents in proteins, is responsible for the inhibition. More importantly, the substitution increased the antibody's binding to FcγRIII receptors by 2-3-fold, and improved ADCC activity by 2-fold, while maintaining a similar pharmacokinetic profile with respect to the wild type. Implications of these observations for antibody engineering and development are discussed.

Double Intracavernous Breakage of Sachse's Knife Blade: Management of a Rare Complication Performing Direct Vision Internal Urethrotomy.

PubMed

Benincasa, Alfonso; Saita, Alberto; Pinto, Angelo; Pilerci, Carmine; Francesco, Lamberti; Russo, Aniello; Benincasa, Giuseppe

2017-01-01

Background: Although the breakage of a Sachse's knife blade is already a rare event while performing optical internal urethrotomy, a double failure appears to be at the same time a unique and a challenging complication to manage since no reference has emerged from literature review. Case Presentation: A male patient, 80 years of age, underwent retreatment of recurrent urethral stricture that occurred after transurethral resection of the prostate. The latter was complicated by severe intraoperative urethrorrhagia; this is the reason he was transferred from another institution where at first a suprapubic cystostomy was carried out, followed by urethral recanalization through internal urethrotomy and finally he underwent intracavernous Sachse's knife blade discharge. Preoperative evaluation included combined retrograde and voiding urethrography and CT to evaluate the complete resolution of the urethral stenosis and to establish the correct location of the blades inside the corpus cavernosum. A transperineal approach to the left corpus cavernosum was carried out with manageable removal of the foreign body and postoperative assessment showed no early considerable complications for the patient. Conclusion: To our knowledge, this is the first case of double breakage of Sachse's knife blade performing optical internal urethrotomy reported in literature. Although it may appear to be an easy procedure, close attention to its execution must always be paid to prevent major complications. A transperineal approach has proven to be effective and safe without creating any further outcomes to the patient.

DNA damage in spermatozoa from infertile men with varicocele evaluated by sperm chromatin dispersion and DBD-FISH.

PubMed

Cortés-Gutiérrez, Elva I; Dávila-Rodríguez, Martha I; Fernández, José Luis; López-Fernández, Carmen; Aragón-Tovar, Anel R; Urbina-Bernal, Luis C; Gosálvez, Jaime

2016-01-01

Evaluation of DNA integrity is an important test, possessing greater diagnostic and prognostic significance for couples requiring assisted reproduction. In this study, we evaluate the levels of DNA damage in infertile patients with varicocele with respect to fertile males by the sperm chromatin dispersion (SCD) test. The presence of DNA breaks in spermatozoa was confirmed by DNA breakage detection-fluorescence in situ hybridization (DBD-FISH). In this study, the frequency of sperm cells with fragmented DNA was studied in a group of 20 infertile patients with varicocele and compared with 20 fertile males. The spermatozoa were processed to classify different levels of DNA fragmentation using the Halosperm(®) kit, an improved SCD test, and DBD-FISH. Patients with varicocele showed 25.54 ± 28.17 % of spermatozoa with fragmented DNA, significantly higher than those of the group of fertile subjects (11.54 ± 3.88 %). The proportion of degraded cells in total sperm cells with fragmented DNA was sixfold higher in the case of patients with varicocele. The presence of DNA breaks in spermatozoa was confirmed by DBD-FISH. 5-bp Classical satellite-2 regions showed greater sensitivity to damage or "breakage" than alphoid satellite regions. Our finding preliminary demonstrated an increase of DNA fragmentation associated to severe sperm damage, in infertile patients with varicocele with respect to fertile males. 5-bp Classical satellite-2 regions showed greater sensitivity to damage or "breakage" than alphoid satellite regions.

Laying date, incubation and egg breakage as determinants of bacterial load on bird eggshells: experimental evidence.

PubMed

Soler, Juan José; Ruiz-Rodríguez, Magdalena; Martín-Vivaldi, Manuel; Peralta-Sánchez, Juan Manuel; Ruiz-Castellano, Cristina; Tomás, Gustavo

2015-09-01

Exploring factors guiding interactions of bacterial communities with animals has become of primary importance for ecologists and evolutionary biologists during the last years because of their likely central role in the evolution of animal life history traits. We explored the association between laying date and eggshell bacterial load (mesophilic bacteria, Enterobacteriaceae, Staphylococci, and Enterococci) in natural and artificial magpie (Pica pica) nests containing fresh commercial quail (Coturnix coturnix) eggs. We manipulated hygiene conditions by spilling egg contents on magpie and artificial nests and explored experimental effects during the breeding season. Egg breakage is a common outcome of brood parasitism by great spotted cuckoos (Clamator glandarius) on the nests of magpie, one of its main hosts. We found that the treatment increased eggshell bacterial load in artificial nests, but not in magpie nests with incubating females, which suggests that parental activity prevents the proliferation of bacteria on the eggshells in relation to egg breakage. Moreover, laying date was positively related to eggshell bacterial load in active magpie nests, but negatively in artificial nests. The results suggest that variation in parental characteristics of magpies rather than climatic variation during the breeding season explained the detected positive association. Because the eggshell bacterial load is a proxy of hatching success, the detected positive association between eggshell bacterial loads and laying date in natural, but not in artificial nests, suggests that the generalized negative association between laying date and avian breeding success can be, at least partially, explained by differential bacterial effects.

On-eye breakage and recovery of mini-scleral contact lens without compromise for the ocular surface.

PubMed

Macedo-de-Araújo, Rute J; van der Worp, Eef; González-Méijome, José M

2018-06-01

To report the on-eye breakage of a mini-scleral contact lens in a healthy cornea after being hit by a speeding object, without causing any severe corneal damage. A 24-year-old Caucasian male involved in a clinical study reported the in situ breakage of a mini-scleral contact lens during motorbike maintenance. The patient reported eye redness and irritation that significantly decreased after all the pieces of the lens were recovered from the eye. Ocular examinations within 48 h showed absence of corneal damage other than superficial punctate keratitis inferiorly and no fragments of the lens were found in the conjunctival sac. The patient was wearing a 15.2 mm mini-scleral lens in a high Dk material. The evolution of rigid materials towards higher Dk values has resulted in a decreased hardness and modulus values, so these materials are more elastic when subjected to mechanical stress, which could be a beneficial aspect in absorbing the energy of an impact before breaking in pieces. This case report shows that ScCL could have a protective effect to the corneal surface from the direct impact of a high-speed object. Mechanical material properties, wide supporting area and post-lens tear volume acted as protective factors helping to absorb and distribute the kinetic energy of the impacting object. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Novel Microbiological and Spatial Statistical Methods to Improve Strength of Epidemiological Evidence in a Community-Wide Waterborne Outbreak

PubMed Central

Jalava, Katri; Rintala, Hanna; Ollgren, Jukka; Maunula, Leena; Gomez-Alvarez, Vicente; Revez, Joana; Palander, Marja; Antikainen, Jenni; Kauppinen, Ari; Räsänen, Pia; Siponen, Sallamaari; Nyholm, Outi; Kyyhkynen, Aino; Hakkarainen, Sirpa; Merentie, Juhani; Pärnänen, Martti; Loginov, Raisa; Ryu, Hodon; Kuusi, Markku; Siitonen, Anja; Miettinen, Ilkka; Santo Domingo, Jorge W.; Hänninen, Marja-Liisa; Pitkänen, Tarja

2014-01-01

Failures in the drinking water distribution system cause gastrointestinal outbreaks with multiple pathogens. A water distribution pipe breakage caused a community-wide waterborne outbreak in Vuorela, Finland, July 2012. We investigated this outbreak with advanced epidemiological and microbiological methods. A total of 473/2931 inhabitants (16%) responded to a web-based questionnaire. Water and patient samples were subjected to analysis of multiple microbial targets, molecular typing and microbial community analysis. Spatial analysis on the water distribution network was done and we applied a spatial logistic regression model. The course of the illness was mild. Drinking untreated tap water from the defined outbreak area was significantly associated with illness (RR 5.6, 95% CI 1.9–16.4) increasing in a dose response manner. The closer a person lived to the water distribution breakage point, the higher the risk of becoming ill. Sapovirus, enterovirus, single Campylobacter jejuni and EHEC O157:H7 findings as well as virulence genes for EPEC, EAEC and EHEC pathogroups were detected by molecular or culture methods from the faecal samples of the patients. EPEC, EAEC and EHEC virulence genes and faecal indicator bacteria were also detected in water samples. Microbial community sequencing of contaminated tap water revealed abundance of Arcobacter species. The polyphasic approach improved the understanding of the source of the infections, and aided to define the extent and magnitude of this outbreak. PMID:25147923

CAD-CAM plates versus conventional fixation plates for primary mandibular reconstruction: A biomechanical in vitro analysis.

PubMed

Rendenbach, Carsten; Sellenschloh, Kay; Gerbig, Lucca; Morlock, Michael M; Beck-Broichsitter, Benedicta; Smeets, Ralf; Heiland, Max; Huber, Gerd; Hanken, Henning

2017-11-01

CAD/CAM reconstruction plates have become a viable option for mandible reconstruction. The aim of this study was to determine whether CAD/CAM plates provide higher fatigue strength compared with conventional fixation systems. 1.0 mm miniplates, 2.0 mm conventional locking plates (DePuy Synthes, Umkirch, Germany), and 2.0 mm CAD/CAM plates (Materialise, Leuven, Belgium/DePuy Synthes) were used to reconstruct a polyurethane mandible model (Synbone, Malans, CH) with cortical and cancellous bone equivalents. Mastication was simulated via cyclic dynamic testing using a universal testing machine (MTS, Bionix, Eden Prairie, MN, USA) until material failure reached a rate of 1 Hz with increasing loads on the left side. No significant difference was found between the groups until a load of 300 N. At higher loads, vertical displacement differed increasingly, with a poorer performance of miniplates (p = 0.04). Plate breakage occurred in miniplates and conventional locking plates. Screw breakage was recorded as the primary failure mechanism in CAD/CAM plates. Stiffness was significantly higher with the CAD/CAM plates (p = 0.04). CAD/CAM plates and reconstruction plates provide higher fatigue strength than miniplates, and stiffness is highest in CAD/CAM systems. All tested fixation methods seem sufficiently stable for mandible reconstruction. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Structure of semiconducting versus fast-ion conducting glasses in the Ag-Ge-Se system.

PubMed

Zeidler, Anita; Salmon, Philip S; Whittaker, Dean A J; Piarristeguy, Andrea; Pradel, Annie; Fischer, Henry E; Benmore, Chris J; Gulbiten, Ozgur

2018-01-01

The transition from a semiconductor to a fast-ion conductor with increasing silver content along the Ag x (Ge 0.25 Se 0.75 ) (100- x ) tie line (0≤ x ≤25) was investigated on multiple length scales by employing a combination of electric force microscopy, X-ray diffraction, and neutron diffraction. The microscopy results show separation into silver-rich and silver-poor phases, where the Ag-rich phase percolates at the onset of fast-ion conductivity. The method of neutron diffraction with Ag isotope substitution was applied to the x =5 and x =25 compositions, and the results indicate an evolution in structure of the Ag-rich phase with change of composition. The Ag-Se nearest-neighbours are distributed about a distance of 2.64(1) Å, and the Ag-Se coordination number increases from 2.6(3) at x =5 to 3.3(2) at x =25. For x =25, the measured Ag-Ag partial pair-distribution function gives 1.9(2) Ag-Ag nearest-neighbours at a distance of 3.02(2) Å. The results show breakage of Se-Se homopolar bonds as silver is added to the Ge 0.25 Se 0.75 base glass, and the limit of glass-formation at x ≃28 coincides with an elimination of these bonds. A model is proposed for tracking the breakage of Se-Se homopolar bonds as silver is added to the base glass.

Structure of semiconducting versus fast-ion conducting glasses in the Ag–Ge–Se system

PubMed Central

2018-01-01

The transition from a semiconductor to a fast-ion conductor with increasing silver content along the Agx(Ge0.25Se0.75)(100−x) tie line (0≤x≤25) was investigated on multiple length scales by employing a combination of electric force microscopy, X-ray diffraction, and neutron diffraction. The microscopy results show separation into silver-rich and silver-poor phases, where the Ag-rich phase percolates at the onset of fast-ion conductivity. The method of neutron diffraction with Ag isotope substitution was applied to the x=5 and x=25 compositions, and the results indicate an evolution in structure of the Ag-rich phase with change of composition. The Ag–Se nearest-neighbours are distributed about a distance of 2.64(1) Å, and the Ag–Se coordination number increases from 2.6(3) at x=5 to 3.3(2) at x=25. For x=25, the measured Ag–Ag partial pair-distribution function gives 1.9(2) Ag–Ag nearest-neighbours at a distance of 3.02(2) Å. The results show breakage of Se–Se homopolar bonds as silver is added to the Ge0.25Se0.75 base glass, and the limit of glass-formation at x≃28 coincides with an elimination of these bonds. A model is proposed for tracking the breakage of Se–Se homopolar bonds as silver is added to the base glass. PMID:29410843

Fragile DNA Motifs Trigger Mutagenesis at Distant Chromosomal Loci in Saccharomyces cerevisiae

PubMed Central

Saini, Natalie; Zhang, Yu; Nishida, Yuri; Sheng, Ziwei; Choudhury, Shilpa; Mieczkowski, Piotr; Lobachev, Kirill S.

2013-01-01

DNA sequences capable of adopting non-canonical secondary structures have been associated with gross-chromosomal rearrangements in humans and model organisms. Previously, we have shown that long inverted repeats that form hairpin and cruciform structures and triplex-forming GAA/TTC repeats induce the formation of double-strand breaks which trigger genome instability in yeast. In this study, we demonstrate that breakage at both inverted repeats and GAA/TTC repeats is augmented by defects in DNA replication. Increased fragility is associated with increased mutation levels in the reporter genes located as far as 8 kb from both sides of the repeats. The increase in mutations was dependent on the presence of inverted or GAA/TTC repeats and activity of the translesion polymerase Polζ. Mutagenesis induced by inverted repeats also required Sae2 which opens hairpin-capped breaks and initiates end resection. The amount of breakage at the repeats is an important determinant of mutations as a perfect palindromic sequence with inherently increased fragility was also found to elevate mutation rates even in replication-proficient strains. We hypothesize that the underlying mechanism for mutagenesis induced by fragile motifs involves the formation of long single-stranded regions in the broken chromosome, invasion of the undamaged sister chromatid for repair, and faulty DNA synthesis employing Polζ. These data demonstrate that repeat-mediated breaks pose a dual threat to eukaryotic genome integrity by inducing chromosomal aberrations as well as mutations in flanking genes. PMID:23785298

Deformation, Failure, and Fatigue Life of SiC/Ti-15-3 Laminates Accurately Predicted by MAC/GMC

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2002-01-01

NASA Glenn Research Center's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) (ref.1) has been extended to enable fully coupled macro-micro deformation, failure, and fatigue life predictions for advanced metal matrix, ceramic matrix, and polymer matrix composites. Because of the multiaxial nature of the code's underlying micromechanics model, GMC--which allows the incorporation of complex local inelastic constitutive models--MAC/GMC finds its most important application in metal matrix composites, like the SiC/Ti-15-3 composite examined here. Furthermore, since GMC predicts the microscale fields within each constituent of the composite material, submodels for local effects such as fiber breakage, interfacial debonding, and matrix fatigue damage can and have been built into MAC/GMC. The present application of MAC/GMC highlights the combination of these features, which has enabled the accurate modeling of the deformation, failure, and life of titanium matrix composites.

Depth estimation of multi-layered impact damage in PMC using lateral thermography

NASA Astrophysics Data System (ADS)

Whitlow, Travis; Kramb, Victoria; Reibel, Rick; Dierken, Josiah

2018-04-01

Characterization of impact damage in polymer matrix composites (PMCs) continues to be a challenge due to the complex internal structure of the material. Nondestructive characterization approaches such as normal incident immersion ultrasound and flash thermography are sensitive to delamination damage, but do not provide information regarding damage obscured by the delaminations. Characterization of material state below a delamination requires a technique which is sensitive to in-plane damage modes such as matrix cracking and fiber breakage. Previous studies of the lateral heat flow through a composite laminate showed that the diffusion time was sensitive to the depth of the simulated damage zone. The current study will further evaluate the lateral diffusion model to provide sensitivity limits for the modeled flaw dimensions. Comparisons between the model simulations and experimental data obtained using a concentrated heat source and machined targets will also be presented.

Genetics Home Reference: recombinant 8 syndrome

MedlinePlus

... with a change in chromosome 8 called an inversion . An inversion involves the breakage of a chromosome in two ... typically not lost as a result of this inversion in chromosome 8 , so people usually do not ...

Genetics Home Reference: core binding factor acute myeloid leukemia

MedlinePlus

... the CBFB gene. One such rearrangement, called an inversion , involves breakage of a chromosome in two places; ... is reversed and reinserted into the chromosome. The inversion involved in CBF-AML (written as inv(16)) ...

CFD-PBM coupled simulation of a nanobubble generator with honeycomb structure

NASA Astrophysics Data System (ADS)

Ren, F.; Noda, N. A.; Ueda, T.; Sano, Y.; Takase, Y.; Umekage, T.; Yonezawa, Y.; Tanaka, H.

2018-06-01

In recent years, nanobubble technologies have drawn great attention due to their wide applications in many fields of science and technology. The nitrogen nanobubble water circulation can be used to slow the progressions of oxidation and spoilage for the seafood long- term storage. From previous studies, a kind of honeycomb structure for high-efficiency nanobubble generation has been proposed. In this paper, the bubbly flow in the honeycomb structure was studied. The numerical simulations of honeycomb structure were performed by using a computational fluid dynamics–population balance model (CFD-PBM) coupled model. The numerical model was based on the Eulerian multiphase model and the population balance model (PBM) was used to calculate the gas bubble size distribution. The bubble coalescence and breakage were included. Considering the effect of bubble diameter on the fluid flow, the phase interactions were coupled with the PBM. The bubble size distributions in the honeycomb structure under different work conditions were predicted. The experimental results were compared with the simulation predictions.

Micromechanical Fatigue Visco-Damage Model for Short Glass Fiber Reinforced Polyamide-66

NASA Astrophysics Data System (ADS)

Despringre, N.; Chemisky, Y.; Robert, G.; Meraghni, F.

This work presents a micromechanical fatigue damage model developed for short glass fiber reinforced PA66. It has been developed to predict the high cycle fatigue behavior of PA66/GF30. The model is based on an extended Mori-Tanaka method which includes coated inclusions, matrix viscoelasticity and the evolution of micro-scale damage. The developed model accounts for the nonlinear matrix viscoelasticity and the reinforcement orientation. The description of the damage processes is based on the experimental investigation of damage mechanisms previously performed through in-situ SEM tests and X-ray micro-computed tomography observations. Damage chronologies have been proposed involving three different processes: interface debonding/coating, matrix micro-cracking and fiber breakages. Their occurrence strongly depends on the microstructure and the relative humidity. Each damage mechanism is introduced through an evolution law coupled to local stress fields. The developed model is implemented using a UMAT subroutine. Its experimental validation is achieved under stress or strain controlled fatigue tests.

Riparian Vegetation Uprooting Due to High Floods: Field, Experiments and Modeling

NASA Astrophysics Data System (ADS)

Francalanci, S.; Calvani, G.; Errico, A.; Giambastiani, Y.; Paris, E.; Preti, F.; Solari, L.

2017-12-01

The morphodynamic evolution of river channel is a complex combination of many concurrent aspects such as the hydrological regime, sediment transport and the presence of riparian vegetation.Only recently, the vegetation has been included in the study of the complex process of river evolution. Juvenile riparian vegetation interacts with sediment transport and river planform morphology, while, on the other hand, well-established rigid vegetation can be uprooted only during the most intense flood events. Consequently, uprooting and breakage of plants during high flow conditions may give rise to significant changes in the flow field and sediment transport between the rising and falling limbs of the hydrograph. In this work, we focused on vegetation uprooting during high flood events, combining field, laboratory and modelling approaches. Field tests were conducted in order to estimate the resistance of root apparatus to uprooting; the field site is Arno River (Italy), where several tall trees were stressed with a known increasing force until the root breakage occurred. We found that the resistance of vegetation scales with the geometric dimension of the plants, and it is well interpreted by the theoretical model (Preti et al 2010). Moreover, laboratory experiments were conducted to better understand the interaction of rigid riparian vegetation and sediment transport in shaping the morphodynamics of river bed in the case of altered hydrological events: we reproduced a bar morphology with hydraulic conditions that are typical of gravel bed rivers in terms of water depth, bed slope and bed load, that is the dominant mode of transport. Then we reproduced the colonizing effect of riparian vegetation on emerged river bars, and we simulated a sequence of peak hydrographs, in order to understand the interaction with bedload transport and verify the stability of the vegetated system towards intense floods. Results showed that the resistance of the root apparatus is well predicted by the theoretical model and that the highest intense floods produce such forcing on the system that plant uprooting can occur. ReferencesPreti, F., Dani, A., Laio, F., 2010. Root profile assessment by means of hydrological, pedological and above-ground vegetation information for bio-engineering purposes. Ecol. Eng. 36, 305-316

A study of energy-size relationship and wear rate in a lab-scale high pressure grinding rolls unit

NASA Astrophysics Data System (ADS)

Rashidi Dashtbayaz, Samira

This study is focused on two independent topics of energy-size relationship and wear-rate measurements on a lab-scale high pressure grinding rolls (HPGR). The first part of this study has been aimed to investigate the influence of the operating parameters and the feed characteristics on the particle-bed breakage using four different ore samples in a 200 mm x 100 mm lab-scale HPGR. Additionally, multistage grinding, scale-up from a lab-scale HPGR, and prediction of the particle size distributions have been studied in detail. The results obtained from energy-size relationship studies help with better understanding of the factors contributing to more energy-efficient grinding. It will be shown that the energy efficiency of the two configurations of locked-cycle and open multipass is completely dependent on the ore properties. A test procedure to produce the scale-up data is presented. The comparison of the scale-up factors between the data obtained on the University of Utah lab-scale HPGR and the industrial machine at the Newmont Boddington plant confirmed the applicability of lab-scale machines for trade-off studies. The population balance model for the simulation of product size distributions has shown to work well with the breakage function estimated through tests performed on the HPGR at high rotational speed. Selection function has been estimated by back calculation of population balance model with the help of the experimental data. This is considered to be a major step towards advancing current research on the simulation of particle size distribution by using the HPGR machine for determining the breakage function. Developing a technique/setup to measure the wear rate of the HPGR rolls' surface is the objective of the second topic of this dissertation. A mockup was initially designed to assess the application of the linear displacement sensors for measuring the rolls' weight loss. Upon the analysis of that technique and considering the corresponding sources of errors, the application of the 2D distance measurement sensors was studied to directly determine the wear rate on the lab-sale HPGR roll. Results obtained from various grinding tests revealed that the operating variations were beyond the expected wear rate. Based on the valuable outcomes from the two mentioned experimental designs, a cup-disc arrangement similar to piston-die apparatus was developed to indirectly measure the wear rate on the HPGR roll. The preliminary outputs proved to be promising for further investigation into the development of this method in order to relate the measured data on the cup-disc apparatus to the actual wear rate on the HPGR rolls.

Ultrafast fragmentation dynamics of triply charged carbon dioxide: Vibrational-mode-dependent molecular bond breakage

NASA Astrophysics Data System (ADS)

Yang, HongJiang; Wang, Enliang; Dong, WenXiu; Gong, Maomao; Shen, Zhenjie; Tang, Yaguo; Shan, Xu; Chen, Xiangjun

2018-05-01

The a b i n i t i o molecular dynamics (MD) simulations using an atom-centered density matrix propagation method have been carried out to investigate the fragmentation of the ground-state triply charged carbon dioxide, CO23 +→C+ + Oa+ + Ob+ . Ten thousands of trajectories have been simulated. By analyzing the momentum correlation of the final fragments, it is demonstrated that the sequential fragmentation dominates in the three-body dissociation, consistent with our experimental observations which were performed by electron collision at impact energy of 1500 eV. Furthermore, the MD simulations allow us to have detailed insight into the ultrafast evolution of the molecular bond breakage at a very early stage, within several tens of femtoseconds, and the result shows that the initial nuclear vibrational mode plays a decisive role in switching the dissociation pathways.

Breakage of IUDs in utero. (Letter).

PubMed

Jackson, M C

1977-06-01

I was interested in the note in the February 1977 issue of the "IPPF MEdical Bulletin" by Biale et al. about the breakage of IUDs in utero. They do not say where and by whom their loops were made, and omit 1 highly important factor in their assessment, i.e., the quality of the plastic. I think we all know that there was a batch of loops produced in Hong Kong in the early 1970s which started, within months of insertion, breaking up in utero; I spent many anxious hours extracting the pieces, and Gladys Dodds must have spent weeks and months removing the thousands of "HK loops" she had inserted in Hong Kong. Conversely, not long ago I removed a Lippes Loop (given me by Jack Lippes) which I had inserted in 1962. It had been in situ for 14 years and it was as resilient as when it went in and was in perfect shape.

Cortical Actomyosin Breakage Triggers Shape Oscillations in Cells and Cell Fragments

PubMed Central

Paluch, Ewa; Piel, Matthieu; Prost, Jacques; Bornens, Michel; Sykes, Cécile

2005-01-01

Cell shape and movements rely on complex biochemical pathways that regulate actin, microtubules, and substrate adhesions. Some of these pathways act through altering the cortex contractility. Here we examined cellular systems where contractility is enhanced by disassembly of the microtubules. We found that adherent cells, when detached from their substrate, developed a membrane bulge devoid of detectable actin and myosin. A constriction ring at the base of the bulge oscillated from one side of the cell to the other. The movement was accompanied by sequential redistribution of actin and myosin to the membrane. We observed this oscillatory behavior also in cell fragments of various sizes, providing a simplified, nucleus-free system for biophysical studies. Our observations suggest a mechanism based on active gel dynamics and inspired by symmetry breaking of actin gels growing around beads. The proposed mechanism for breakage of the actomyosin cortex may be used for cell polarization. PMID:15879479

Visual Identification of Light-Driven Breakage of the Silver-Dithiocarbamate Bond by Single Plasmonic Nanoprobes

PubMed Central

Gao, Peng Fei; Yuan, Bin Fang; Gao, Ming Xuan; Li, Rong Sheng; Ma, Jun; Zou, Hong Yan; Li, Yuan Fang; Li, Ming; Huang, Cheng Zhi

2015-01-01

Insight into the nature of metal-sulfur bond, a meaningful one in life science, interface chemistry and organometallic chemistry, is interesting but challenging. By utilizing the localized surface plasmon resonance properties of silver nanoparticles, herein we visually identified the photosensitivity of silver-dithiocarbamate (Ag-DTC) bond by using dark field microscopic imaging (iDFM) technique at single nanoparticle level. It was found that the breakage of Ag-DTC bond could be accelerated effectively by light irradiation, followed by a pH-dependent horizontal or vertical degradation of the DTC molecules, in which an indispensable preoxidation process of the silver was at first disclosed. These findings suggest a visualization strategy at single plasmonic nanoparticle level which can be excellently applied to explore new stimulus-triggered reactions, and might also open a new way to understand traditional organic reaction mechanisms. PMID:26493773

Minimizing tooth bending stress in spur gears with simplified shapes of fillet and tool shape determination

NASA Astrophysics Data System (ADS)

Pedersen, N. L.

2015-06-01

The strength of a gear is typically defined relative to durability (pitting) and load capacity (tooth-breakage). Tooth-breakage is controlled by the root shape and this gear part can be designed because there is no contact between gear pairs here. The shape of gears is generally defined by different standards, with the ISO standard probably being the most common one. Gears are manufactured using two principally different tools: rack tools and gear tools. In this work, the bending stress of involute teeth is minimized by shape optimization made directly on the final gear. This optimized shape is then used to find the cutting tool (the gear envelope) that can create this optimized gear shape. A simple but sufficiently flexible root parameterization is applied and emphasis is put on the importance of separating the shape parameterization from the finite element analysis of stresses. Large improvements in the stress level are found.

Clinical ascertainment of Nijmegen breakage syndrome (NBS) and prevalence of the major mutation, 657del5, in three Slav populations.

PubMed

Varon, R; Seemanova, E; Chrzanowska, K; Hnateyko, O; Piekutowska-Abramczuk, D; Krajewska-Walasek, M; Sykut-Cegielska, J; Sperling, K; Reis, A

2000-11-01

Nijmegen breakage syndrome (NBS) is a chromosomal instability disorder, clinically characterised by microcephaly, immunodeficiency, radiosensitivity and a very high predisposition to lymphoid malignancy. Recently, it was demonstrated that mutations in the NBS1 gene are responsible for NBS. Most of the NBS patients known so far are of Slav origin and carry a major founder mutation 657del5 in exon 6 of the NBS1 gene. In this study we estimated the prevalence of the 657del5 mutation in the Czech Republic, Poland and the Ukraine. We found an unexpectedly high carrier frequency of the 657del5 mutation (1/177) in the three Slav populations, a factor that may contribute to cancer frequency in those countries. In addition, we show that NBS patients are often diagnosed late and therefore receive inappropriate therapy.

Relationships Between Smelter Grade Alumina Characteristics and Strength Determined by Nanoindentation and Ultrasound-Mediated Particle Breakage

NASA Astrophysics Data System (ADS)

Wijayaratne, Hasini; McIntosh, Grant; Hyland, Margaret; Perander, Linus; Metson, James

2017-06-01

The mechanical strength of smelter grade alumina (SGA) is of considerable practical significance for the aluminum reduction process. Attrition of alumina during transportation and handling generates an increased level of fines. This results in generation of dust, poor flow properties, and silo segregation that interfere with alumina feeding systems. These lead to process instabilities which in turn result in current efficiency losses that are costly. Here we are concerned with developing a fundamental understanding of SGA strength in terms of its microstructure. Nanoindentation and ultrasound-mediated particle breakage tests have been conducted to study the strength. Strength of SGA samples both industry calcined and laboratory prepared, decrease with increasing α-alumina (corundum) content contrary to expectation. The reducing strength of alumina with increasing degree of calcination is attributed to the development of a macroporous and abrasion-prone microstructure resulting from the `pseudomorphic' transformation of precursor gibbsite during the calcination process.

Fault detection of gearbox using time-frequency method

NASA Astrophysics Data System (ADS)

Widodo, A.; Satrijo, Dj.; Prahasto, T.; Haryanto, I.

2017-04-01

This research deals with fault detection and diagnosis of gearbox by using vibration signature. In this work, fault detection and diagnosis are approached by employing time-frequency method, and then the results are compared with cepstrum analysis. Experimental work has been conducted for data acquisition of vibration signal thru self-designed gearbox test rig. This test-rig is able to demonstrate normal and faulty gearbox i.e., wears and tooth breakage. Three accelerometers were used for vibration signal acquisition from gearbox, and optical tachometer was used for shaft rotation speed measurement. The results show that frequency domain analysis using fast-fourier transform was less sensitive to wears and tooth breakage condition. However, the method of short-time fourier transform was able to monitor the faults in gearbox. Wavelet Transform (WT) method also showed good performance in gearbox fault detection using vibration signal after employing time synchronous averaging (TSA).

Gametocidal chromosomes enhancing chromosome aberration in common wheat induced by 5-azacytidine.

PubMed

Su, W-Y; Cong, W-W; Shu, Y-J; Wang, D; Xu, G-H; Guo, C-H

2013-07-08

The gametocidal (Gc) chromosome from Aegilops spp induces chromosome mutation, which is introduced into common wheat as a tool of chromosome manipulation for genetic improvement. The Gc chromosome functions similar to a restriction-modification system in bacteria, in which DNA methylation is an important regulator. We treated root tips of wheat carrying Gc chromosomes with the hypomethylation agent 5-azacytidine; chromosome breakage and micronuclei were observed in these root tips. The frequency of aberrations differed in wheat containing different Gc chromosomes, suggesting different functions inducing chromosome breakage. Gc chromosome 3C caused the greatest degree of chromosome aberration, while Gc chromosome 3C(SAT) and 2C caused only slight chromosome aberration. Gc chromosome 3C induced different degrees of chromosome aberration in wheat varieties Triticum aestivum var. Chinese Spring and Norin 26, demonstrating an inhibition function in common wheat.

The Synthesis and Structural Characterization of Graft Copolymers Composed of γ-PGA Backbone and Oligoesters Pendant Chains

NASA Astrophysics Data System (ADS)

Kwiecień, Iwona; Radecka, Iza; Kowalczuk, Marek; Jelonek, Katarzyna; Orchel, Arkadiusz; Adamus, Grażyna

2017-10-01

The novel copolymers composed of poly-γ-glutamic acid (γ-PGA) and oligoesters have been developed. The structures of the obtained copolymers including variety of end groups were determined at the molecular level with the aid of electrospray ionization multistage mass spectrometry (ESI-MSn). The fragmentation experiment performed for the selected sodium adducts of the copolymers confirmed that the developed methods lead to the formation of graft copolymers composed of poly-γ-glutamic acid (γ-PGA) backbone and oligoesters pendant chains. Moreover, it was established that fragmentation of selected sodium adducts of graft copolymers proceeded via random breakage of amide bonds along the backbone and ester bonds of the oligoesters pendant chains. Considering potential applications of the synthesized copolymers in the area of biomaterials, the hydrolytic degradation under laboratory conditions and in vitro cytotoxicity tests were performed. The ESI-MSn technique applied in this study has been proven to be a useful tool in structural studies of novel graft copolymers as well as their degradation products. [Figure not available: see fulltext.

Combined quantum-mechanics/molecular-mechanics dynamics simulation of A-DNA double strands irradiated by ultra-low-energy carbon ions

NASA Astrophysics Data System (ADS)

Ngaojampa, C.; Nimmanpipug, P.; Yu, L. D.; Anuntalabhochai, S.; Lee, V. S.

2011-02-01

In order to promote understanding of the fundamentals of ultra-low-energy ion interaction with DNA, molecular dynamics simulations using combined quantum-mechanics/molecular-mechanics of poly-AT and poly-GC A-DNA double strands irradiated by <200 eV carbon ions were performed to investigate the molecular implications of mutation bias. The simulations were focused on the responses of the DNA backbones and nitrogenous bases to irradiation. Analyses of the root mean square displacements of the backbones and non-hydrogen atoms of base rings of the simulated DNA structure after irradiation revealed a potential preference of DNA double strand separation, dependent on the irradiating energy. The results show that for the backbones, the large difference in the displacement between poly-GC and poly-AT in the initial time period could be the reason for the backbone breakage; for the nitrogenous base pairs, A-T is 30% more sensitive or vulnerable to ion irradiation than G-C, demonstrating a preferential, instead of random, effect of irradiation-induced mutation.

Defects in the Fanconi Anemia Pathway and Chromatid Cohesion in Head and Neck Cancer.

PubMed

Stoepker, Chantal; Ameziane, Najim; van der Lelij, Petra; Kooi, Irsan E; Oostra, Anneke B; Rooimans, Martin A; van Mil, Saskia E; Brink, Arjen; Dietrich, Ralf; Balk, Jesper A; Ylstra, Bauke; Joenje, Hans; Feller, Stephan M; Brakenhoff, Ruud H

2015-09-01

Failure to repair DNA damage or defective sister chromatid cohesion, a process essential for correct chromosome segregation, can be causative of chromosomal instability (CIN), which is a hallmark of many types of cancers. We investigated how frequent this occurs in head and neck squamous cell carcinoma (HNSCC) and whether specific mechanisms or genes could be linked to these phenotypes. The genomic instability syndrome Fanconi anemia is caused by mutations in any of at least 16 genes regulating DNA interstrand crosslink (ICL) repair. Since patients with Fanconi anemia have a high risk to develop HNSCC, we investigated whether and to which extent Fanconi anemia pathway inactivation underlies CIN in HNSCC of non-Fanconi anemia individuals. We observed ICL-induced chromosomal breakage in 9 of 17 (53%) HNSCC cell lines derived from patients without Fanconi anemia. In addition, defective sister chromatid cohesion was observed in five HNSCC cell lines. Inactivation of FANCM was responsible for chromosomal breakage in one cell line, whereas in two other cell lines, somatic mutations in PDS5A or STAG2 resulted in inadequate sister chromatid cohesion. In addition, FANCF methylation was found in one cell line by screening an additional panel of 39 HNSCC cell lines. Our data demonstrate that CIN in terms of ICL-induced chromosomal breakage and defective chromatid cohesion is frequently observed in HNSCC. Inactivation of known Fanconi anemia and chromatid cohesion genes does explain CIN in the minority of cases. These findings point to phenotypes that may be highly relevant in treatment response of HNSCC. ©2015 American Association for Cancer Research.

An Intensified Vibratory Milling Process for Enhancing the Breakage Kinetics during the Preparation of Drug Nanosuspensions.

PubMed

Li, Meng; Zhang, Lu; Davé, Rajesh N; Bilgili, Ecevit

2016-04-01

As a drug-sparing approach in early development, vibratory milling has been used for the preparation of nanosuspensions of poorly water-soluble drugs. The aim of this study was to intensify this process through a systematic increase in vibration intensity and bead loading with the optimal bead size for faster production. Griseofulvin, a poorly water-soluble drug, was wet-milled using yttrium-stabilized zirconia beads with sizes ranging from 50 to 1500 μm at low power density (0.87 W/g). Then, this process was intensified with the optimal bead size by sequentially increasing vibration intensity and bead loading. Additional experiments with several bead sizes were performed at high power density (16 W/g), and the results were compared to those from wet stirred media milling. Laser diffraction, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and dissolution tests were used for characterization. Results for the low power density indicated 800 μm as the optimal bead size which led to a median size of 545 nm with more than 10% of the drug particles greater than 1.8 μm albeit the fastest breakage. An increase in either vibration intensity or bead loading resulted in faster breakage. The most intensified process led to 90% of the particles being smaller than 300 nm. At the high power intensity, 400 μm beads were optimal, which enhanced griseofulvin dissolution significantly and signified the importance of bead size in view of the power density. Only the optimally intensified vibratory milling led to a comparable nanosuspension to that prepared by the stirred media milling.

Low-Energy Electron-Induced Strand Breaks in Telomere-Derived DNA Sequences-Influence of DNA Sequence and Topology.

PubMed

Rackwitz, Jenny; Bald, Ilko

2018-03-26

During cancer radiation therapy high-energy radiation is used to reduce tumour tissue. The irradiation produces a shower of secondary low-energy (<20 eV) electrons, which are able to damage DNA very efficiently by dissociative electron attachment. Recently, it was suggested that low-energy electron-induced DNA strand breaks strongly depend on the specific DNA sequence with a high sensitivity of G-rich sequences. Here, we use DNA origami platforms to expose G-rich telomere sequences to low-energy (8.8 eV) electrons to determine absolute cross sections for strand breakage and to study the influence of sequence modifications and topology of telomeric DNA on the strand breakage. We find that the telomeric DNA 5'-(TTA GGG) 2 is more sensitive to low-energy electrons than an intermixed sequence 5'-(TGT GTG A) 2 confirming the unique electronic properties resulting from G-stacking. With increasing length of the oligonucleotide (i.e., going from 5'-(GGG ATT) 2 to 5'-(GGG ATT) 4 ), both the variety of topology and the electron-induced strand break cross sections increase. Addition of K + ions decreases the strand break cross section for all sequences that are able to fold G-quadruplexes or G-intermediates, whereas the strand break cross section for the intermixed sequence remains unchanged. These results indicate that telomeric DNA is rather sensitive towards low-energy electron-induced strand breakage suggesting significant telomere shortening that can also occur during cancer radiation therapy. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalytic therapy of cancer by ascorbic acid involves redox cycling of exogenous/endogenous copper ions and generation of reactive oxygen species.

PubMed

Hadi, S M; Ullah, M F; Shamim, U; Bhatt, S H; Azmi, A S

2010-01-01

Catalytic therapy is a cancer treatment modality based on the generation of reactive oxygen species (ROS) through administration of ascorbate/medicinal herbal extracts and copper. It is known that antioxidants such as ascorbate also exhibit prooxidant activity in the presence of transition metals such as copper. Based on our work and that in the literature, in this review we propose a mechanism for the cytotoxic action of ascorbate against cancer cells. It involves redox cycling of exogenous/endogenous copper ions and the consequent generation of ROS leading to oxidative DNA breakage. Using human peripheral lymphocytes and the Comet assay, we have shown that ascorbic acid is able to cause oxidative breakage in cellular DNA. Such DNA degradation is inhibited by neocuproine (a Cu(I) sequestering agent) and scavengers of ROS indicating that the cellular DNA breakage involves the generation of Cu(I) and formation of ROS. Similar results are also obtained with plant polyphenol antioxidants that are important constituents of medicinal herbal extracts. Copper is an essential component of chromatin and can take part in redox reactions. It is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies. Therefore, cancer cells may be more subject to electron transfer between copper ions and ascorbate/plant polyphenols to generate ROS. In this review we cite evidence to indicate that in catalytic therapy cytotoxic action against cancer cells involves redox cycling of exogenous/endogenous copper ions. Copyright © 2010 S. Karger AG, Basel.

Oral administration of copper to rats leads to increased lymphocyte cellular DNA degradation by dietary polyphenols: implications for a cancer preventive mechanism.

PubMed

Khan, Husain Y; Zubair, Haseeb; Ullah, Mohd F; Ahmad, Aamir; Hadi, Sheikh M

2011-12-01

To account for the observed anticancer properties of plant polyphenols, we have earlier proposed a mechanism which involves the mobilization of endogenous copper ions by polyphenols leading to the generation of reactive oxygen species (ROS) that serve as proximal DNA cleaving agents and lead to cell death. Over the last decade we have proceeded to validate our hypothesis with considerable success. As a further confirmation of our hypothesis, in this paper we first show that oral administration of copper to rats leads to elevated copper levels in lymphocytes. When such lymphocytes with a copper overload were isolated and treated with polyphenols EGCG, genistein and resveratrol, an increased level of DNA breakage was observed. Further, preincubation of lymphocytes having elevated copper levels with the membrane permeable copper chelator neocuproine, resulted in inhibition of polyphenol induced DNA degradation. However, membrane impermeable chelator of copper bathocuproine, as well as iron and zinc chelators were ineffective in causing such inhibition in DNA breakage, confirming the involvement of endogenous copper in polyphenol induced cellular DNA degradation. It is well established that serum and tissue concentrations of copper are greatly increased in various malignancies. In view of this fact, the present results further confirm our earlier findings and strengthen our hypothesis that an important anticancer mechanism of plant polyphenols could be the mobilization of intracellular copper leading to ROS-mediated cellular DNA breakage. In this context, it may be noted that cancer cells are under considerable oxidative stress and increasing such stress to cytotoxic levels could be a successful anticancer approach.

Effects of Visual Force Feedback on Robot-Assisted Surgical Task Performance

PubMed Central

Reiley, Carol E.; Akinbiyi, Takintope; Burschka, Darius; Chang, David C.; Okamura, Allison M.; Yuh, David D.

2009-01-01

Background Direct haptic (force or tactile) feedback is negligible in current surgical robotic systems. The relevance of haptic feedback in robot-assisted performances of surgical tasks is controversial. We studied the effects of visual force feedback (VFF), a haptic feedback surrogate, on tying surgical knots with fine sutures similar to those used in cardiovascular surgery. Methods Using a modified da Vinci robotic system (Intuitive Surgical, Inc.) equipped with force-sensing instrument tips and real-time VFF overlays in the console image, ten surgeons each tied 10 knots with and 10 knots without VFF. Four surgeons had significant prior da Vinci experience while the remaining six surgeons did not. Performance parameters, including suture breakage and secure knots, peak and standard deviation of applied forces, and completion times using 5-0 silk sutures were recorded. Chi-square and Student’s t-test analyses determined differences between groups. Results Among surgeon subjects with robotic experience, no differences in measured performance parameters were found between robot-assisted knot ties executed with and without VFF. Among surgeons without robotic experience, however, VFF was associated with lower suture breakage rates, peak applied forces, and standard deviations of applied forces. VFF did not impart differences in knot completion times or loose knots for either surgeon group. Conclusions VFF resulted in reduced suture breakage, lower forces, and decreased force inconsistencies among novice robotic surgeons, although elapsed time and knot quality were unaffected. In contrast, VFF did not affect these metrics among experienced da Vinci surgeons. These results suggest that VFF primarily benefits novice robot-assisted surgeons, with diminishing benefits among experienced surgeons. PMID:18179942

Self-Reported Penis Size and Experiences with Condoms Among Gay and Bisexual Men

PubMed Central

Grov, Christian; Wells, Brooke E.

2018-01-01

As researchers and community-based providers continue to encourage latex condom use as a chief strategy to prevent HIV transmission among men who have sex with men, research is needed to better explore the intersecting associations among penis size (length and circumference), condom feel, ease of finding condoms, recent experience of condom failure (breakage and slippage), and unprotected anal sex. Data were taken from a 2010 community-based survey of self-identified gay and bisexual men in New York City (n = 463). More than half (51.4 %) reported penile length as 6–8 in. long (15–20 cm) and 31.5 % reported penile circumference as 4–6 in. around (10–15 cm). Variation in self-reported penile dimensions was significantly associated with men’s attitudes toward the typical/average condom, difficulty finding condoms that fit, and the experience of condom breakage. Men who had engaged in recent unprotected insertive anal intercourse reported significantly higher values for both penile length and circumference, and these men were significantly more likely to report that the average/typical condom was “too tight.” Most men had measured their length (86.2 %) and/or circumference (68.9 %), suggesting that penile measurement might be a common and acceptable practice among gay and bisexual men. As HIV and STI prevention providers continue to serve as leading distributers of free condoms, these findings further highlight the need for condom availability to be in a variety of sizes. Improving condom fit and attitudes toward condoms may also improve condom use and minimize condom slippage and breakage. PMID:22552706

Heavy ion-induced DNA double-strand breaks in yeast.

PubMed

Kiefer, Jürgen; Egenolf, Ralf; Ikpeme, Samuel

2002-02-01

Induction of DSBs in the diploid yeast, Saccharomyces cerevisiae, was measured by pulsed-field gel electrophoresis (PFGE) after the cells had been exposed on membrane filters to a variety of energetic heavy ions with values of linear energy transfer (LET) ranging from about 2 to 11,500 keV/microm, (241)Am alpha particles, and 80 keV X rays. After irradiation, the cells were lysed, and the chromosomes were separated by PFGE. The gels were stained with ethidium bromide, placed on a UV transilluminator, and analyzed using a computer-coupled camera. The fluorescence intensities of the larger bands were found to decrease exponentially with dose or particle fluence. The slope of this line corresponds to the cross section for at least one double-strand break (DSB), but closely spaced multiple breaks cannot be discriminated. Based on the known size of the native DNA molecules, breakage cross sections per base pair were calculated. They increased with LET until they reached a transient plateau value of about 6 x 10(-7) microm(2) at about 300-2000 keV/microm; they then rose for the higher LETs, probably reflecting the influence of delta electrons. The relative biological effectiveness for DNA breakage displays a maximum of about 2.5 around 100-200 keV/microm and falls below unity for LET values above 10(3) keV/microm. For these yeast cells, comparison of the derived breakage cross sections with the corresponding cross section for inactivation derived from the terminal slope of the survival curves shows a strong linear relationship between these cross sections, extending over several orders of magnitude.

Technical Report on Modeling for Quasispecies Abundance Inference with Confidence Intervals from Metagenomic Sequence Data

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

McLoughlin, K.

2016-01-11

The overall aim of this project is to develop a software package, called MetaQuant, that can determine the constituents of a complex microbial sample and estimate their relative abundances by analysis of metagenomic sequencing data. The goal for Task 1 is to create a generative model describing the stochastic process underlying the creation of sequence read pairs in the data set. The stages in this generative process include the selection of a source genome sequence for each read pair, with probability dependent on its abundance in the sample. The other stages describe the evolution of the source genome from itsmore » nearest common ancestor with a reference genome, breakage of the source DNA into short fragments, and the errors in sequencing the ends of the fragments to produce read pairs.« less

Study of Plasma Motor Generator (PMG) tether system for orbit reboost

NASA Technical Reports Server (NTRS)

1987-01-01

Detailed designs were produced for a 2 kW plasma motor generator tether system based largely on existing hardware and hardware designs. Specifically, the hollow cathode design and electronics are derived from ion propulsion equipment. A prototype tether was constructed and will be tested for deployment, strength, resistance to breakage and abrasion and electrical properties. In addition, laboratory development models of the electronics will be used to operate two plasma motor generator hollow cathode assemblies with this tether to verify electrical performance parameters for the complete system. Results show that a low cost demonstration of a plasma motor generator tether system appears to be feasible by the middle of the 1990s.

Fundamentals of magnet-actuated droplet manipulation on an open hydrophobic surface.

PubMed

Long, Zhicheng; Shetty, Abhishek M; Solomon, Michael J; Larson, Ronald G

2009-06-07

We systematically investigate droplet movement, coalescence, and splitting on an open hydrophobic surface. These processes are actuated by magnetic beads internalized in an oil-coated aqueous droplet using an external magnet. Results are organized into an 'operating diagram' that describes regions of droplet stable motion, breakage, and release from the magnet. The results are explained theoretically with a simple model that balances magnetic, friction, and capillary-induced drag forces and includes the effects of particle type, droplet size, surrounding oil layer, surface tension, and viscosity. Finally, we discuss the implications of the results for the design of magnet-actuated droplet systems for applications such as nucleic acid purification, immunoassay and drug delivery.

Fundamentals of magnet-actuated droplet manipulation on an open hydrophobic surface†

PubMed Central

Long, Zhicheng; Shetty, Abhishek M.; Solomon, Michael J.; Larson, Ronald G.

2010-01-01

We systematically investigate droplet movement, coalescence, and splitting on an open hydrophobic surface. These processes are actuated by magnetic beads internalized in an oil-coated aqueous droplet using an external magnet. Results are organized into an ‘operating diagram’ that describes regions of droplet stable motion, breakage, and release from the magnet. The results are explained theoretically with a simple model that balances magnetic, friction, and capillary-induced drag forces and includes the effects of particle type, droplet size, surrounding oil layer, surface tension, and viscosity. Finally, we discuss the implications of the results for the design of magnet-actuated droplet systems for applications such as nucleic acid purification, immunoassay and drug delivery. PMID:19458864

Implementation of AIMS in measuring aggregate resistance to polishing, abrasion, and breakage.

DOT National Transportation Integrated Search

2014-05-01

The feasibility of using the Micro-Deval apparatus along with the second-generation Aggregate Imaging System : (AIMS) to develop a procedure for measuring aggregate polishing resistance, and to measure aggregate shape : properties was investigated. E...

HOW to Identify and Control Stem Rusts of Jack Pine

Treesearch

Kathryn Robbins; Dale K. Smeltzer; D. W. French

Damage to jack pine caused by rust fungi includes growth reduction, cankers, death (by girdling or wind breakage), and creation of entryways for other fungi and insects. Seedlings and saplings are more seriously affected than older trees.

Anesthetic Cartridge System Under Evaluation

PubMed Central

Cooley, Robert L.; Lubow, Richard M.

1981-01-01

The problem of glass breakage in the local anesthetic cartridge system was evaluated under laboratory conditions with a mechanical testing machine. The anticipated breakage of the glass did not occur with any frequency, as the rubber stopper produced more uniform failures of the system. The glass cartridge appeared to be quite reliable and resistant to breakage. Local anesthetics have been used for many years to provide patients temporary freedom from pain. Local anesthetic solutions are in wide use in both dentistry and medicine and are the most frequently used drugs in dentistry. Various estimates place the number of injections at approximately one half million daily or 125 million injections per year. These drugs and the armamentarium necessary to administer them have proven to be safe and reliable. Only rarely are there reports of sensitivity to the anesthetic solution or breakage of needles.. Sterility of the solutions has not been a problem as they are carefully processed and evaluated at the factory. Although there are sporadic reports of loss of sterility, this has been attributed to the reuse of the anesthetic cartridges on more than one patient. Monheim states “The success of the cartridge system in dentistry has been due to the sincerity, honesty, and high standards of the manufacturers in giving the profession a near-perfect product.” However, on occassion a glass cartridge will break or shatter when inserting the harpoon into the rubber stopper or even during injection. Cooley et al reported on eye injuries occurring in the dental office, one of which was due to glass from a local anesthetic cartridge that exploded and propelled particles into the patient's eye. Forrest evaluated syringes, needles, and cartridges and reported that one brand (made in Britain) fractured more often than any other, but that the fracture rate was too low to be of any consequence. It is apparent that glass cartridges will fracture or burst from time to time. This study evaluates the cartridge system with carefully controlled laboratory procedures. The cartridges were tested under various pressures and conditions in an attempt to determine the causes of failure and when such failure may be anticipated. ImagesFigure 1Figure 2Figure 3Figure 4Figure 9Figure 10 PMID:6939350

Reduced bone breakage and increased bone strength in free range laying hens fed omega-3 polyunsaturated fatty acid supplemented diets.

PubMed

Tarlton, John F; Wilkins, Lindsay J; Toscano, Michael J; Avery, Nick C; Knott, Lynda

2013-02-01

The omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) are the immediate precursors to a number of important mediators of immunity, inflammation and bone function, with products of omega-6 generally thought to promote inflammation and favour bone resorption. Western diets generally provide a 10 to 20-fold deficit in omega-3 PUFAs compared with omega-6, and this is thought to have contributed to the marked rise in incidence of disorders of modern human societies, such as heart disease, colitis and perhaps osteoporosis. Many of our food production animals, fed on grains rich in omega-6, are also exposed to a dietary deficit in omega-3, with perhaps similar health consequences. Bone fragility due to osteoporotic changes in laying hens is a major economic and welfare problem, with our recent estimates of breakage rates indicating up to 95% of free range hens suffer breaks during lay. Free range hens housed in full scale commercial systems were provided diets supplemented with omega-3 alpha linolenic acid, and the skeletal benefits were investigated by comparison to standard diets rich in omega-6. There was a significant 40-60% reduction in keel bone breakage rate, and a corresponding reduction in breakage severity in the omega-3 supplemented hens. There was significantly greater bone density and bone mineral content, alongside increases in total bone and trabecular volumes. The mechanical properties of the omega-3 supplemented hens were improved, with strength, energy to break and stiffness demonstrating significant increases. Alkaline phosphatase (an osteoblast marker) and tartrate-resistant acid phosphatase (an osteoclast marker) both showed significant increases with the omega-3 diets, indicating enhanced bone turnover. This was corroborated by the significantly lower levels of the mature collagen crosslinks, hydroxylysyl pyridinoline, lysyl pyridinoline and histidinohydroxy-lysinonorleucine, with a corresponding significant shift in the mature:immature crosslink ratio. The improved skeletal health in laying hens corresponds to as many as 68million fewer hens suffering keel fractures in the EU each year. The biomechanical and biochemical evidence suggests that increased bone turnover has enhanced the bone mechanical properties, and that this may suggest potential benefits for human osteoporosis. Copyright © 2012 Elsevier Inc. All rights reserved.

Numerical study of a stochastic particle algorithm solving a multidimensional population balance model for high shear granulation

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

Braumann, Andreas; Kraft, Markus, E-mail: mk306@cam.ac.u; Wagner, Wolfgang

2010-10-01

This paper is concerned with computational aspects of a multidimensional population balance model of a wet granulation process. Wet granulation is a manufacturing method to form composite particles, granules, from small particles and binders. A detailed numerical study of a stochastic particle algorithm for the solution of a five-dimensional population balance model for wet granulation is presented. Each particle consists of two types of solids (containing pores) and of external and internal liquid (located in the pores). Several transformations of particles are considered, including coalescence, compaction and breakage. A convergence study is performed with respect to the parameter that determinesmore » the number of numerical particles. Averaged properties of the system are computed. In addition, the ensemble is subdivided into practically relevant size classes and analysed with respect to the amount of mass and the particle porosity in each class. These results illustrate the importance of the multidimensional approach. Finally, the kinetic equation corresponding to the stochastic model is discussed.« less

Constitutive Model Constants for Al7075-T651 and Al7075-T6

NASA Astrophysics Data System (ADS)

Brar, N. S.; Joshi, V. S.; Harris, B. W.

2009-12-01

Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these materials. Although the two tempers show similar elongation at breakage, the ultimate tensile strength of T651 temper is generally lower than the T6 temper. Johnson-Cook strength model constants (A, B, n, C, and m) for the two alloys are determined from high strain rate tension stress-strain data at room and high temperature to 250°C. The Johnson-Cook fracture model constants are determined from quasi-static and medium strain rate as well as high temperature tests on notched and smooth tension specimens. Although the J-C strength model constants are similar, the fracture model constants show wide variations. Details of the experimental method used and the results for the two alloys are presented.

Vibration-Resistant Support for Halide Lamps

NASA Technical Reports Server (NTRS)

Kiss, J.

1987-01-01

Lamp envelope protected against breakage. Old and new mounts for halide arc lamp sealed in housing with parabolic refector and quartz window. New version supports lamp with compliant garters instead of rigid brazed joint at top and dimensionally unstable finger stock at bottom.

Chromosome Bridges Maintain Kinetochore-Microtubule Attachment throughout Mitosis and Rarely Break during Anaphase.

PubMed

Pampalona, Judit; Roscioli, Emanuele; Silkworth, William T; Bowden, Brent; Genescà, Anna; Tusell, Laura; Cimini, Daniela

2016-01-01

Accurate chromosome segregation during cell division is essential to maintain genome stability, and chromosome segregation errors are causally linked to genetic disorders and cancer. An anaphase chromosome bridge is a particular chromosome segregation error observed in cells that enter mitosis with fused chromosomes/sister chromatids. The widely accepted Breakage/Fusion/Bridge cycle model proposes that anaphase chromosome bridges break during mitosis to generate chromosome ends that will fuse during the following cell cycle, thus forming new bridges that will break, and so on. However, various studies have also shown a link between chromosome bridges and aneuploidy and/or polyploidy. In this study, we investigated the behavior and properties of chromosome bridges during mitosis, with the idea to gain insight into the potential mechanism underlying chromosome bridge-induced aneuploidy. We find that only a small number of chromosome bridges break during anaphase, whereas the rest persist through mitosis into the subsequent cell cycle. We also find that the microtubule bundles (k-fibers) bound to bridge kinetochores are not prone to breakage/detachment, thus supporting the conclusion that k-fiber detachment is not the cause of chromosome bridge-induced aneuploidy. Instead, our data suggest that while the microtubules bound to the kinetochores of normally segregating chromosomes shorten substantially during anaphase, the k-fibers bound to bridge kinetochores shorten only slightly, and may even lengthen, during anaphase. This causes some of the bridge kinetochores/chromosomes to lag behind in a position that is proximal to the cell/spindle equator and may cause the bridged chromosomes to be segregated into the same daughter nucleus or to form a micronucleus.

Factors affecting continued use of ceramic water purifiers distributed to tsunami-affected communities in Sri Lanka.

PubMed

Casanova, Lisa M; Walters, Adam; Naghawatte, Ajith; Sobsey, Mark D

2012-11-01

There is little information about continued use of point-of-use technologies after disaster relief efforts. After the 2004 tsunami, the Red Cross distributed ceramic water filters in Sri Lanka. This study determined factors associated with filter disuse and evaluate the quality of household drinking water. A cross-sectional survey of water sources and treatment, filter use and household characteristics was administered by in-person oral interview, and household water quality was tested. Multivariable logistic regression was used to model probability of filter non-use. At the time of survey, 24% of households (107/452) did not use filters; the most common reason given was breakage (42%). The most common household water sources were taps and wells. Wells were used by 45% of filter users and 28% of non-users. Of households with taps, 75% had source water Escherichia coli in the lowest World Health Organisation risk category (<1/100 ml), vs. only 30% of households reporting wells did. Tap households were approximately four times more likely to discontinue filter use than well households. After 2 years, 24% of households were non-users. The main factors were breakage and household water source; households with taps were more likely to stop use than households with wells. Tap water users also had higher-quality source water, suggesting that disuse is not necessarily negative and monitoring of water quality can aid decision-making about continued use. To promote continued use, disaster recovery filter distribution efforts must be joined with capacity building for long-term water monitoring, supply chains and local production. © 2012 Blackwell Publishing Ltd.

Comparing Sanitation Delivery Modalities in Urban Informal Settlement Schools: A Randomized Trial in Nairobi, Kenya

PubMed Central

Bohnert, Kate; Chard, Anna N.; Mwaki, Alex; Kirby, Amy E.; Muga, Richard; Nagel, Corey L.; Thomas, Evan A.; Freeman, Matthew C.

2016-01-01

The provision of safely managed sanitation in informal settlements is a challenge, especially in schools that require durable, clean, sex-segregated facilities for a large number of children. In informal settlements in Nairobi, school sanitation facilities demand considerable capital costs, yet are prone to breakage and often unhygienic. The private sector may be able to provide quality facilities and services to schools at lower costs as an alternative to the sanitation that is traditionally provided by the government. We conducted a randomized trial comparing private sector service delivery (PSSD) of urine-diverting dry latrines with routine waste collection and maintenance and government standard delivery (GSD) of cistern-flush toilets or ventilated improved pit latrines. The primary outcomes were facility maintenance, use, exposure to fecal contamination, and cost. Schools were followed for one school year. There were few differences in maintenance and pathogen exposure between PSSD and GSD toilets. Use of the PSSD toilets was 128% higher than GSD toilets, as measured with electronic motion detectors. The initial cost of private sector service delivery was USD 2053 (KES 210,000) per school, which was lower than the average cost of rehabilitating the government standard flush-type toilets (USD 9306 (KES 922,638)) and constructing new facilities (USD 114,889 (KES 1,169,668)). The private sector delivery of dry sanitation provided a feasible alternative to the delivery of sewage sanitation in Nairobi informal settlements and might elsewhere in sub-Saharan Africa. PMID:27916914

Comparing Sanitation Delivery Modalities in Urban Informal Settlement Schools: A Randomized Trial in Nairobi, Kenya.

PubMed

Bohnert, Kate; Chard, Anna N; Mwaki, Alex; Kirby, Amy E; Muga, Richard; Nagel, Corey L; Thomas, Evan A; Freeman, Matthew C

2016-11-30

The provision of safely managed sanitation in informal settlements is a challenge, especially in schools that require durable, clean, sex-segregated facilities for a large number of children. In informal settlements in Nairobi, school sanitation facilities demand considerable capital costs, yet are prone to breakage and often unhygienic. The private sector may be able to provide quality facilities and services to schools at lower costs as an alternative to the sanitation that is traditionally provided by the government. We conducted a randomized trial comparing private sector service delivery (PSSD) of urine-diverting dry latrines with routine waste collection and maintenance and government standard delivery (GSD) of cistern-flush toilets or ventilated improved pit latrines. The primary outcomes were facility maintenance, use, exposure to fecal contamination, and cost. Schools were followed for one school year. There were few differences in maintenance and pathogen exposure between PSSD and GSD toilets. Use of the PSSD toilets was 128% higher than GSD toilets, as measured with electronic motion detectors. The initial cost of private sector service delivery was USD 2053 (KES 210,000) per school, which was lower than the average cost of rehabilitating the government standard flush-type toilets (USD 9306 (KES 922,638)) and constructing new facilities (USD 114,889 (KES 1,169,668)). The private sector delivery of dry sanitation provided a feasible alternative to the delivery of sewage sanitation in Nairobi informal settlements and might elsewhere in sub-Saharan Africa.

Evaluation of the LithoGold LG-380 Lithotripter: In Vitro Acoustic Characterization and Assessment of Renal Injury in the Pig Model

PubMed Central

Pishchalnikov, Yuri A.; Williams, James C.; Connors, Bret A.; Handa, Rajash K.; Lingeman, James E.; Evan, Andrew P.

2013-01-01

Abstract Purpose Conduct a laboratory evaluation of a novel low-pressure, broad focal zone electrohydraulic lithotripter (TRT LG-380). Methods Mapping of the acoustic field of the LG-380, along with a Dornier HM3, a Storz Modulith SLX, and a XiXin CS2012 (XX-ES) lithotripter was performed using a fiberoptic hydrophone. A pig model was used to assess renal response to 3000 shockwaves (SW) administered by a multistep power ramping protocol at 60 SW/min, and when animals were treated at the maximum power setting at 120 SW/min. Injury to the kidney was assessed by quantitation of lesion size and routine measures of renal function. Results SW amplitudes for the LG-380 ranged from (P+/P-) 7/-1.8 MPa at PL-1 to 21/-4 MPa at PL-11 while focal width measured ∼20 mm, wider than the HM3 (8 mm), SLX (2.6 mm), or XX-ES (18 mm). For the LG-380, there was gradual narrowing of the focal width to ∼10 mm after 5000 SWs, but this had negligible effect on breakage of model stones, because stones positioned at the periphery of the focal volume (10 mm off-axis) broke nearly as well as stones at the target point. Kidney injury measured less than 0.1% FRV (functional renal volume) for pigs treated using a gradual power ramping protocol at 60 SW/min and when SWs were delivered at maximum power at 120 SW/min. Conclusions The LG-380 exhibits the acoustic characteristics of a low-pressure, wide focal zone lithotripter and has the broadest focal width of any lithotripter yet reported. Although there was a gradual narrowing of focal width as the electrode aged, the efficiency of stone breakage was not affected. Because injury to the kidney was minimal when treatment followed either the recommended slow SW-rate multistep ramping protocol or when all SWs were delivered at fast SW-rate using maximum power, this appears to be a relatively safe lithotripter. PMID:23228113

Treatment of thoracolumbar burst fractures with variable screw placement or Isola instrumentation and arthrodesis: case series and literature review.

PubMed

Alvine, Gregory F; Swain, James M; Asher, Marc A; Burton, Douglas C

2004-08-01

The controversy of burst fracture surgical management is addressed in this retrospective case study and literature review. The series consisted of 40 consecutive patients, index included, with 41 fractures treated with stiff, limited segment transpedicular bone-anchored instrumentation and arthrodesis from 1987 through 1994. No major acute complications such as death, paralysis, or infection occurred. For the 30 fractures with pre- and postoperative computed tomography studies, spinal canal compromise was 61% and 32%, respectively. Neurologic function improved in 7 of 14 patients (50%) and did not worsen in any. The principal problem encountered was screw breakage, which occurred in 16 of the 41 (39%) instrumented fractures. As we have previously reported, transpedicular anterior bone graft augmentation significantly decreased variable screw placement (VSP) implant breakage. However, it did not prevent Isola implant breakage in two-motion segment constructs. Compared with VSP, Isola provided better sagittal plane realignment and constructs that have been found to be significantly stiffer. Unplanned reoperation was necessary in 9 of the 40 patients (23%). At 1- and 2-year follow-up, 95% and 79% of patients were available for study, and a satisfactory outcome was achieved in 84% and 79%, respectively. These satisfaction and reoperation rates are consistent with the literature of the time. Based on these observations and the loads to which implant constructs are exposed following posterior realignment and stabilization of burst fractures, we recommend that three- or four-motion segment constructs, rather than two motion, be used. To save valuable motion segments, planned construct shortening can be used. An alternative is sequential or staged anterior corpectomy and structural grafting.

Telomere dysfunction and chromosome structure modulate the contribution of individual chromosomes in abnormal nuclear morphologies.

PubMed

Pampalona, J; Soler, D; Genescà, A; Tusell, L

2010-01-05

The cytokinesis-block micronucleus assay has emerged as a biomarker of chromosome damage relevant to cancer. Although it was initially developed to measure micronuclei, it is also useful for measuring nucleoplasmic bridges and nuclear buds. Abnormal nuclear morphologies are frequently observed in malignant tissues and short-term tumour cell cultures. Changes in chromosome structure and number resulting from chromosome instability are important factors in oncogenesis. Telomeres have become key players in the initiation of chromosome instability related to carcinogenesis by means of breakage-fusion-bridge cycles. To better understand the connection between telomere dysfunction and the appearance of abnormal nuclear morphologies, we have characterised the presence of micronuclei, nucleoplasmic bridges and nuclear buds in human mammary primary epithelial cells. These cells can proliferate beyond the Hayflick limit by spontaneously losing expression of the p16(INK4a) protein. Progressive telomere shortening leads to the loss of the capping function, and the appearance of end-to-end chromosome fusions that can enter into breakage-fusion-bridge cycles generating massive chromosomal instability. In human mammary epithelial cells, different types of abnormal nuclear morphologies were observed, however only nucleoplasmatic bridges and buds increased significantly with population doublings. Fluorescent in situ hybridisation using centromeric and painting specific probes for chromosomes with eroded telomeres has revealed that these chromosomes are preferentially included in the different types of abnormal nuclear morphologies observed, thus reflecting their common origin. Accordingly, real-time imaging of cell divisions enabled us to determine that anaphase bridge resolution was mainly through chromatin breakage and the formation of symmetric buds in daughter nuclei. Few micronuclei emerged in this cell system thus validating the scoring of nucleoplasmic bridges and nuclear buds for measuring chromosome instability in telomere-dysfunction cell environments.

Shock Wave Injury to the Kidney in SWL: Review and Perspective

NASA Astrophysics Data System (ADS)

McAteer, James A.; Evan, Andrew P.; Willis, Lynn R.; Connors, Bret A.; Williams, James C.; Pishchalnikov, Yuri A.; Lingeman, James E.

2007-04-01

Shock wave lithotripsy (SWL) is a first-line option for treatment for urinary calculi—particularly effective for the removal of uncomplicated stones from the upper urinary tract. The success of lithotripsy is tempered, however, by the occurrence of acute injury that has been reported to progress to long-term complications. SW trauma to the kidney is a vascular lesion characterized by parenchymal and subcapsular bleeding. The acute lesion is dose-dependent, and typically localized to the focal volume of the lithotripter. Cavitation has been implicated in vessel rupture, but SW-shear has the potential to be a primary mechanism for damage as well. Possible chronic adverse effects of SWL may include new-onset hypertension, development of diabetes, and exacerbation of stone disease. If acute trauma could be reduced, it seems likely that serious long-term effects could be minimized, or even eliminated. Reducing the dose of SW's needed for stone breakage is one option. Improved coupling improves stone breakage, and slowing SW rate significantly improves stone-free outcomes. Experiments with animals now show that treatment protocols can be designed to protect against tissue injury. Initiating treatment with low energy SW's dramatically reduces lesion size, and reducing the rate of SW delivery virtually eliminates SW trauma altogether. SWL stands to gain from new advances in technology, as lithotripters become safer and more effective. Perhaps the greatest progress will be made when we have determined the physical mechanisms of SW action both for stone breakage and tissue damage, and have better characterized the biological response to SW's—as this will provide the principles needed to achieve the best combination of safety and efficiency with whatever lithotripter is at hand.

Condom Use Errors and Problems: A Comparative Study of HIV-Positive Versus HIV-Negative Young Black MSM

PubMed Central

Crosby, Richard; Mena, Leandro; Yarber, William L.; Graham, Cynthia A.; Sanders, Stephanie A.; Milhausen, Robin R.

2015-01-01

Objective To describe self-reported frequencies of selected condom use errors and problems among young (ages 15–29) Black MSM (YBMSM) and to compare the observed prevalence of these errors/problems by HIV serostatus. Methods Between September 2012 October 2014, electronic interview data were collected from 369 YBMSM attending a federally supported STI clinic located in the southern U.S. Seventeen condom use errors and problems were assessed. Chi-square tests were used to detect significant differences in the prevalence of these 17 errors and problems between HIV-negative and HIV-positive men. Results The recall period was the past 90 days. The overall mean number of errors/problems was 2.98 (sd=2.29). The mean for HIV-negative men was 2.91 (sd=2.15) and the mean for HIV-positive men was 3.18 (sd=2.57). These means were not significantly different (t=1.02, df=367, P=.31). Only two significant differences were observed between HIV-negative and HIV-positive men. Breakage (P = .002) and slippage (P = .005) were about twice as likely among HIV-positive men. Breakage occurred for nearly 30% of the HIV-positive men compared to about 15% among HIV-negative men. Slippage occurred for about 16% of the HIV-positive men compared to about 9% among HIV-negative men. Conclusion A need exists to help YBMSM acquire the skills needed to avert breakage and slippage issues that could lead to HIV transmission. Beyond these two exceptions, condom use errors and problems were ubiquitous in this population regardless of HIV serostatus. Clinic-based intervention is warranted for these young men, including education about correct condom use and provision of free condoms and long-lasting lubricants. PMID:26462188

Investigation on the durability of man-made vitreous fibers in rat lungs.

PubMed Central

Bellmann, B; Muhle, H; Kamstrup, O; Draeger, U F

1994-01-01

Two types of sized stonewool with median lengths of 6.7 and 10.1 microns and median diameters of 0.63 and 0.85 microns, and crocidolite with fibers of median length of 4.8 microns and median diameter of 0.18 microns were instilled intratracheally into female Wistar rats. A single dose of 2 mg in 0.3 ml saline was used for the stonewool samples and 0.1 mg in 0.3 ml saline for crocidolite. The evenness of distribution of fibers in the lung was checked by scanning electron microscopy (SEM). Five animals per group were sacrificed after 2 days, 1, 3, 6, and 12 months. After low-temperature ashing of the lungs about 200 fibers per animal were analyzed by SEM for length and diameter. The number and mass of fibers in the total lung were calculated. For the stonewool samples the decrease in the number of fibers in the lung ash followed approximately first order kinetics resulting in half-times of 90 and 120 days. The analysis of fiber number and diameter of different length fractions was used to estimate the contribution of three processes of fiber elimination: transport by macrophages for short fibers, breakage of fibers, and dissolution of fibers. (The process of transport by macrophages was found fastest for fibers with length < 2.5 microns). For the elimination of critical fibers with length > 5 microns, the breakage and dissolution were the most important processes. The breakage of fibers was predominant for one of the stonewool samples. The preferential type of the mechanism of fiber elimination is dependent on chemical composition and size distribution. PMID:7882927

Familial Xp22.33-Xp22.12 deletion delineated by chromosomal microarray analysis causes proportionate short stature.

PubMed

Cho, Sung Yoon; Ki, Chang-Seok; Jang, Ja-Hyun; Sohn, Young Bae; Park, Sung Won; Kim, Se Hwa; Kim, Su Jin; Jin, Dong-Kyu

2012-06-01

Patients with Xp deletions have short stature and may have some somatic traits typical of Turner syndrome (TS), whereas gonadal function is generally preserved. In most studies of these patients, microsatellites have been used to determine the break point of the Xp deletion. In the present study, we describe the clinical, cytogenetic, and chromosomal microarray (CMA) analysis of a family with an Xp22.33-Xp22.12 deletion. Two female siblings, aged 8 years 9 months and 11 years 10 months, presented with short stature. The older sibling's height (index case) was 137.9 cm (-1.81 SDS) and the younger sibling's height was 118.6 cm (-2.13 SDS). The mother and both daughters had only a short stature; a skeletal survey showed normal findings except for mildly shortened 4th and 5th metacarpal bones. No features of TS were present. The deletion appeared terminal with a breakpoint within Xp22.2 located about 19.9 Mb from the Xp telomere. The deletion contained 102 protein-coding genes. A probe of the end breakage point was located at the 19,908,986th base of the X chromosome, and a probe of the marginal normal region near the breakage point was located at the 19,910,848th base of the X chromosome. Therefore, the breakage point was concluded to be located between these two probes. In summary, we report a familial case of an Xp deletion. The findings of our study may be helpful in further analyzing the phenotypes associated with Xp deletions. Copyright © 2012 Wiley Periodicals, Inc.

Real-time direct and diffraction X-ray imaging of irregular silicon wafer breakage.

PubMed

Rack, Alexander; Scheel, Mario; Danilewsky, Andreas N

2016-03-01

Fracture and breakage of single crystals, particularly of silicon wafers, are multi-scale problems: the crack tip starts propagating on an atomic scale with the breaking of chemical bonds, forms crack fronts through the crystal on the micrometre scale and ends macroscopically in catastrophic wafer shattering. Total wafer breakage is a severe problem for the semiconductor industry, not only during handling but also during temperature treatments, leading to million-dollar costs per annum in a device production line. Knowledge of the relevant dynamics governing perfect cleavage along the {111} or {110} faces, and of the deflection into higher indexed {hkl} faces of higher energy, is scarce due to the high velocity of the process. Imaging techniques are commonly limited to depicting only the state of a wafer before the crack and in the final state. This paper presents, for the first time, in situ high-speed crack propagation under thermal stress, imaged simultaneously in direct transmission and diffraction X-ray imaging. It shows how the propagating crack tip and the related strain field can be tracked in the phase-contrast and diffracted images, respectively. Movies with a time resolution of microseconds per frame reveal that the strain and crack tip do not propagate continuously or at a constant speed. Jumps in the crack tip position indicate pinning of the crack tip for about 1-2 ms followed by jumps faster than 2-6 m s(-1), leading to a macroscopically observed average velocity of 0.028-0.055 m s(-1). The presented results also give a proof of concept that the described X-ray technique is compatible with studying ultra-fast cracks up to the speed of sound.

Shock and vibration effects on performance reliability and mechanical integrity of proton exchange membrane fuel cells: A critical review and discussion

NASA Astrophysics Data System (ADS)

Haji Hosseinloo, Ashkan; Ehteshami, Mohsen Mousavi

2017-10-01

Performance reliability and mechanical integrity are the main bottlenecks in mass commercialization of PEMFCs for applications with inherent harsh environment such as automotive and aerospace applications. Imparted shock and vibration to the fuel cell in such applications could bring about numerous issues including clamping torque loosening, gas leakage, increased electrical resistance, and structural damage and breakage. Here, we provide a comprehensive review and critique of the literature focusing on the effects of mechanically harsh environment on PEMFCs, and at the end, we suggest two main future directions in FC technology research that need immediate attention: (i) developing a generic and adequately accurate dynamic model of PEMFCs to assess the dynamic response of FC devices, and (ii) designing effective and robust shock and vibration protection systems based on the developed models in (i).

Fundamental analysis of the failure of polymer-based fiber reinforced composites

NASA Technical Reports Server (NTRS)

Kanninen, M. F.; Rybicki, E. F.; Griffith, W. I.; Broek, D.

1975-01-01

A mathematical model predicting the strength of unidirectional fiber reinforced composites containing known flaws and with linear elastic-brittle material behavior was developed. The approach was to imbed a local heterogeneous region surrounding the crack tip into an anisotropic elastic continuum. This (1) permits an explicit analysis of the micromechanical processes involved in the fracture, and (2) remains simple enough to be useful in practical computations. Computations for arbitrary flaw size and orientation under arbitrary applied loads were performed. The mechanical properties were those of graphite epoxy. With the rupture properties arbitrarily varied to test the capabilities of the model to reflect real fracture modes, it was shown that fiber breakage, matrix crazing, crack bridging, matrix-fiber debonding, and axial splitting can all occur during a period of (gradually) increasing load prior to catastrophic failure. The calculations also reveal the sequential nature of the stable crack growth process proceding fracture.

Analysis of a Precambrian resonance-stabilized day length

NASA Astrophysics Data System (ADS)

Bartlett, Benjamin C.; Stevenson, David J.

2016-06-01

During the Precambrian era, Earth's decelerating rotation would have passed a 21 h period that would have been resonant with the semidiurnal atmospheric thermal tide. Near this point, the atmospheric torque would have been maximized, being comparable in magnitude but opposite in direction to the lunar torque, halting Earth's rotational deceleration, maintaining a constant day length, as detailed by Zahnle and Walker (1987). We develop a computational model to determine necessary conditions for formation and breakage of this resonant effect. Our simulations show the resonance to be resilient to atmospheric thermal noise but suggest a sudden atmospheric temperature increase like the deglaciation period following a possible "snowball Earth" near the end of the Precambrian would break this resonance; the Marinoan and Sturtian glaciations seem the most likely candidates for this event. Our model provides a simulated day length over time that resembles existing paleorotational data, though further data are needed to verify this hypothesis.

Experimental and CFD-PBM approach coupled with a simplified dynamic analysis of mass transfer in phenol biodegradation in a three phase system of an aerated two-phase partitioning bioreactor for environmental applications

NASA Astrophysics Data System (ADS)

Moradkhani, Hamed; Anarjan Kouchehbagh, Navideh; Izadkhah, Mir-Shahabeddin

2017-03-01

A three-dimensional transient modeling of a two-phase partitioning bioreactor, combining system hydrodynamics, two simultaneous mass transfer and microorganism growth is modeled using computational fluid dynamics code FLUENT 6.2. The simulation is based on standard "k-ɛ" Reynolds-averaged Navier-Stokes model. Population balance model is implemented in order to describe gas bubble coalescence, breakage and species transport in the reaction medium and to predict oxygen volumetric mass transfer coefficient (kLa). Model results are verified against experimental data and show good agreement as 13 classes of bubble size is taking into account. Flow behavior in different operational conditions is studied. Almost at all impeller speeds and aeration intensities there were acceptable distributions of species caused by proper mixing. The magnitude of dissolved oxygen percentage in aqueous phase has a direct correlation with impeller speed and any increasing of the aeration magnitude leads to faster saturation in shorter periods of time.

A Progressive Damage Model for Predicting Permanent Indentation and Impact Damage in Composite Laminates

NASA Astrophysics Data System (ADS)

Ji, Zhaojie; Guan, Zhidong; Li, Zengshan

2017-10-01

In this paper, a progressive damage model was established on the basis of ABAQUS software for predicting permanent indentation and impact damage in composite laminates. Intralaminar and interlaminar damage was modelled based on the continuum damage mechanics (CDM) in the finite element model. For the verification of the model, low-velocity impact tests of quasi-isotropic laminates with material system of T300/5228A were conducted. Permanent indentation and impact damage of the laminates were simulated and the numerical results agree well with the experiments. It can be concluded that an obvious knee point can be identified on the curve of the indentation depth versus impact energy. Matrix cracking and delamination develops rapidly with the increasing impact energy, while considerable amount of fiber breakage only occurs when the impact energy exceeds the energy corresponding to the knee point. Predicted indentation depth after the knee point is very sensitive to the parameter μ which is proposed in this paper, and the acceptable value of this parameter is in range from 0.9 to 1.0.

5 CFR 1605.14 - Misclassified retirement system coverage.

Code of Federal Regulations, 2010 CFR

2010-01-01

... is a FERCCA correction, the employing agency must submit makeup employee contributions on late... correction, the employing agency must submit makeup employee contributions on current payment records; in such cases, the employee is not entitled to breakage. Agency makeup contributions may be submitted on...

50 CFR 260.99 - Buildings and structures.

Code of Federal Regulations, 2010 CFR

2010-10-01

... suspended over exposed food in any step of preparation shall be of the safety type or otherwise protected to prevent food contamination in case of breakage. (b) Ventilation. There shall be sufficient ventilation in... PROCESSED FOOD PRODUCTS INSPECTION AND CERTIFICATION Inspection and Certification of Establishments and...

Phase-detected Brillouin optical correlation-domain reflectometry

NASA Astrophysics Data System (ADS)

Mizuno, Yosuke; Hayashi, Neisei; Fukuda, Hideyuki; Nakamura, Kentaro

2018-05-01

Optical fiber sensing techniques based on Brillouin scattering have been extensively studied for structural health monitoring owing to their capability of distributed strain and temperature measurement. Although a higher signal-to-noise ratio (leading to high spatial resolution and high-speed measurement) is generally obtained for two-end-access systems, they reduce the degree of freedom in embedding the sensors into structures, and render the measurement no longer feasible when extremely high loss or breakage occurs at a point of the sensing fiber. To overcome these drawbacks, a one-end-access sensing technique called Brillouin optical correlation-domain reflectometry (BOCDR) has been developed. BOCDR has a high spatial resolution and cost efficiency, but its conventional configuration suffered from relatively low-speed operation. In this paper, we review the recently developed high-speed configurations of BOCDR, including phase-detected BOCDR, with which we demonstrate real-time distributed measurement by tracking a propagating mechanical wave. We also demonstrate breakage detection with a wide strain dynamic range.

Safety assessment of underground vehicles passing over highly resilient curved tracks in the presence of a broken rail

NASA Astrophysics Data System (ADS)

Suárez, B.; Rodriguez, P.; Vázquez, M.; Fernández, I.

2012-01-01

Vehicle-track interaction for a new resilient slab track designed to reduce noise and vibration levels was analysed, in order to assess the derailment risk on a curved track when encountering a broken rail. Sensitivity of the rail support spacing of the relative position of the rail breakage between two adjacent rail supports and of running speed were analysed for two different elasticities of the rail fastening system. In none of the cases analysed was observed an appreciable difference between either of the elastic systems. As was expected, the most unfavourable situations were those with greater rail support spacing and those with greater distance from the breakage to the nearest rail support, although in none of the simulations performed did a derailment occur when running over the broken rail. When varying the running speed, the most favourable condition was obtained for an intermediate speed, due to the superposition of two antagonistic effects.

R&D on dental implants breakage

NASA Astrophysics Data System (ADS)

Croitoru, Sorin Mihai; Popovici, Ion Alexandru

2017-09-01

Most used dental implants for human dental prostheses are of two steps type: first step means implantation and, after several months healing and osseointegration, second step is prosthesis fixture. For sure, dental implants and prostheses are meant to last for a lifetime. Still, there are unfortunate cases when dental implants break. This paper studies two steps dental implants breakage and proposes a set of instruments for replacement and restoration of the broken implant. First part of the paper sets the input data of the study: structure of the studied two steps dental implants based on two Romanian patents and values of the loading forces found in practice and specialty papers. In the second part of the paper, using DEFORM 2D™ FEM simulation software, worst case scenarios of loading dental implants are studied in order to determine which zones and components of the dental implant set are affected (broken). Last part of the paper is dedicated to design and presentation of a set for extracting and cutting tools used to restore the broken implant set.

Hallermann-Streiff syndrome associated with small cerebellum, endocrinopathy and increased chromosomal breakage.

PubMed

Hou, J W

2003-07-01

Hallermann-Streiff syndrome (HSS) is a rare clinic entity of unknown aetiology. Further clinical and metabolic-genetic evaluations are indicated. A 2-mo-old female baby presented with ocular abnormalities and severe failure to thrive since birth. The clinical features were compatible with the diagnosis of HSS. Further imaging, metabolic and cytogenetic examinations were performed. Features characteristic of HSS were dyscephaly with mandibular and nasal cartilage hypoplasia, microphthalmia, bilateral cataracts with congenital glaucoma, natal teeth and proportionate dwarfism. Rare anomalies such as choanal atresia and small cerebellum, very low insulin-like growth factor I level, hypothyroidism, generalized organic aciduria were also noticed. An increased chromosomal breakage rate is suggestive of the existence of some DNA repair defects in HSS patients. The associated anomalies in this patient may broaden the clinical spectrum of HSS. Underlying conditions of organic aciduria, growth factor deficiency and impaired DNA repair are likely to contribute to the progeria-like facies, congenital cataracts and growth failure.

[Induced abortion and use of contraceptive methods among prostitutes in Almería (Spain)].

PubMed

Cabrerizo Egea, María Jesús; Barroso García, María Pilar; Rodríguez-Contreras Pelayo, Rafael

2015-01-01

To analyze the performance of induced abortion (IA) in prostitutes in Almería (Spain) and its association with the use of contraceptive methods. A cross-sectional study was conducted in 110 women. A bivariate analyses using either the χ(2) test or Fisher's exact test was carried out (significance level <0.05), with calculation of odds ratios and 95% confidence intervals. A total of 52.7% of women had undergone at least one IA. All of these women used condoms and 35.5% of them also used another contraceptive method. No statistically significant association was found between condom breakage and the performance of IA or in the use of other contraceptive methods. A high percentage of this group of women had undergone IA, despite widespread condom use. However, there was a high percentage of condom breakage and a low percentage of use of emergency contraceptive pills after risky sexual relationships. Copyright © 2014 SESPAS. Published by Elsevier Espana. All rights reserved.

Holokinetic centromeres and efficient telomere healing enable rapid karyotype evolution.

PubMed

Jankowska, Maja; Fuchs, Jörg; Klocke, Evelyn; Fojtová, Miloslava; Polanská, Pavla; Fajkus, Jiří; Schubert, Veit; Houben, Andreas

2015-12-01

Species with holocentric chromosomes are often characterized by a rapid karyotype evolution. In contrast to species with monocentric chromosomes where acentric fragments are lost during cell division, breakage of holocentric chromosomes creates fragments with normal centromere activity. To decipher the mechanism that allows holocentric species an accelerated karyotype evolution via chromosome breakage, we analyzed the chromosome complements of irradiated Luzula elegans plants. The resulting chromosomal fragments and rearranged chromosomes revealed holocentromere-typical CENH3 and histone H2AThr120ph signals as well as the same mitotic mobility like unfragmented chromosomes. Newly synthesized telomeres at break points become detectable 3 weeks after irradiation. The presence of active telomerase suggests a telomerase-based mechanism of chromosome healing. A successful transmission of holocentric chromosome fragments across different generations was found for most offspring of irradiated plants. Hence, a combination of holokinetic centromere activity and the fast formation of new telomeres at break points enables holocentric species a rapid karyotype evolution involving chromosome fissions and rearrangements.

Phase-detected Brillouin optical correlation-domain reflectometry

NASA Astrophysics Data System (ADS)

Mizuno, Yosuke; Hayashi, Neisei; Fukuda, Hideyuki; Nakamura, Kentaro

2018-06-01

Optical fiber sensing techniques based on Brillouin scattering have been extensively studied for structural health monitoring owing to their capability of distributed strain and temperature measurement. Although a higher signal-to-noise ratio (leading to high spatial resolution and high-speed measurement) is generally obtained for two-end-access systems, they reduce the degree of freedom in embedding the sensors into structures, and render the measurement no longer feasible when extremely high loss or breakage occurs at a point of the sensing fiber. To overcome these drawbacks, a one-end-access sensing technique called Brillouin optical correlation-domain reflectometry (BOCDR) has been developed. BOCDR has a high spatial resolution and cost efficiency, but its conventional configuration suffered from relatively low-speed operation. In this paper, we review the recently developed high-speed configurations of BOCDR, including phase-detected BOCDR, with which we demonstrate real-time distributed measurement by tracking a propagating mechanical wave. We also demonstrate breakage detection with a wide strain dynamic range.

Metallurgical investigation of wire breakage of tyre bead grade.

PubMed

Palit, Piyas; Das, Souvik; Mathur, Jitendra

2015-10-01

Tyre bead grade wire is used for tyre making application. The wire is used as reinforcement inside the polymer of tyre. The wire is available in different size/section such as 1.6-0.80 mm thin Cu coated wire. During tyre making operation at tyre manufacturer company, wire failed frequently. In this present study, different broken/defective wire samples were collected from wire mill for detailed investigation of the defect. The natures of the defects were localized and similar in nature. The fracture surface was of finger nail type. Crow feet like defects including button like surface abnormalities were also observed on the broken wire samples. The defect was studied at different directions under microscope. Different advanced metallographic techniques have been used for detail investigation. The analysis revealed that, white layer of surface martensite was formed and it caused the final breakage of wire. In this present study we have also discussed about the possible reason for the formation of such kind of surface martensite (hard-phase).

Seismicity and recent faulting in eastern California and western and central Nevada: A preliminary report

NASA Technical Reports Server (NTRS)

Abdel-Gawad, M. (Principal Investigator); Silverstein, J.; Tubbesing, L.

1973-01-01

The author has identified the following significant results. ERTS-1 imagery covering the eastern California-Nevada seismic belt were utilized to study the fault pattern in relation to the distribution of earthquake epicenters and Quaternary volcanic rocks. Many suspected faults not previously mapped were identified. These include several suspected shear zones in Nevada, faults showing evidence of recent breakage, and major lineaments. Highly seismic areas are generally characterized by Holocene faulting and Quaternary volcanic activity. However, several major fault segments showing evidence of recent breakage are associated with little or no seismicity. The tectonic pattern strongly suggests that the eastern California-Nevada seismic belt coincides with a major crustal rift associated with zones of lateral shear. New data on potentially active fault zones have direct practical applications in national and local earthquake hazard reduction programs. Positive contacts have been made with Kern and Ventura Counties to make results of this investigation available for application to their earthquake hazards definition projects.

Heterogeneity of humoral immune abnormalities in children with Nijmegen breakage syndrome: an 8-year follow-up study in a single centre

PubMed Central

Gregorek, H; Chrzanowska, K H; Michałkiewicz, J; Syczewska, M; Madaliński, K

2002-01-01

During an 8-year period of observation, defects of immune responses were characterized and monitored in 40 of 50 Polish children with Nijmegen breakage syndrome referred to the Children's Memorial Health Institute in Warsaw. The following parameters were determined at diagnosis: (1) concentrations of serum IgM, IgG, IgA; (2) concentrations of IgG subclasses; and (3) lymphocyte subpopulations. In addition, naturally acquired specific antibodies against Streptococcus pneumoniae were determined in 20 patients with a history of recurrent respiratory infections. During follow-up, total serum immunoglobulins and IgG subclasses were monitored systematically in 17 patients who did not receive immunomodulatory therapy. Moreover, anti-HBs antibody response was measured after vaccination of 20 children against HBV. We found that the immune deficiency in NBS is profound, highly variable, with a tendency to progress over time. Systematic monitoring of the humoral response, despite good clinical condition, is essential for early medical intervention. PMID:12390322

Predicting the Agglomeration of Cohesive Particles in a Gas-Solid Flow and its Effect on the Solids Flow

NASA Astrophysics Data System (ADS)

Kellogg, Kevin; Liu, Peiyuan; Lamarche, Casey; Hrenya, Christine

2017-11-01

In flows of cohesive particles, agglomerates will readily form and break. These agglomerates are expected to complicate how particles interact with the surrounding fluid in multiphase flows, and consequently how the solids flow. In this work, a dilute flow of particles driven by gas against gravity is studied. A continuum framework, composed of a population balance to predict the formation of agglomerates, and kinetic-theory-based balances, is used to predict the flow of particles. The closures utilized for the birth and death rates due to aggregation and breakage in the population balance take into account how the impact velocity (the granular temperature) affects the outcome of a collision as aggregation, rebound, or breakage. The agglomerate size distribution and solids velocity predicted by the continuum framework are compared to discrete element method (DEM) simulations, as well to experimental results of particles being entrained from the riser of a fluidized bed. Dow Corning Corporation.

Perspective on Lithotripsy Adverse Effects

NASA Astrophysics Data System (ADS)

Knoll, Thomas; Wendt-Nordahl, Gunnar

2008-09-01

Shock wave lithotripsy (SWL) is an effective and without any doubt the least invasive procedure to treat upper urinary tract calculi. Acute complications are rarely reported and do not require specific treatment in most cases. However, one should be aware that energy levels sufficient for stone breakage are capable of damaging tissue as well, and significant hematoma—not only in the kidney but as well in surrounding organs—has been observed. Furthermore, only little is known about the long-term effects of SWL. Some authors have reported an increased incidence of hypertension and possibly also diabetes mellitus. Such chronic diseases—if indeed related to prior SWL—may be a late result of acute SWL-related trauma but the discussion on the underlying pathogenesis is controversial. Many factors have to be considered, such as the natural history of recurrent stone formers, technical principles of SWL, and differences in treatment protocols. Promising studies are currently underway to optimize stone breakage while limiting potential collateral damage. With this progress, SWL remains a safe treatment option for most urinary calculi.

Slow softening of Kanzi apples (Malus×domestica L.) is associated with preservation of pectin integrity in middle lamella.

PubMed

Gwanpua, Sunny George; Verlinden, Bert E; Hertog, Maarten L A T M; Nicolai, Bart M; Hendrickx, Marc; Geeraerd, Annemie

2016-11-15

Kanzi is a recently developed apple cultivar that has an extremely low ethylene production, and maintains its crispiness during ripening. To identify key determinants of the slow softening behaviour of Kanzi apples, a comparative analysis of pectin biochemistry and tissue fracture pattern during different ripening stages of Kanzi apples was performed against Golden Delicious, a rapid softening cultivar. While substantial pectin depolymerisation and solubilisation was observed during softening in Golden Delicious apples, no depolymerisation or increased solubilisation was observed in Kanzi apples. Moreover, tissue failure during ripening was mainly by cell breakage in Kanzi apples and, in contrast, by cell separation in Golden Delicious apples. Kanzi apples had lower activity of beta-galactosidase, with no decline in the extent of branching of the pectin chain. A sudden decrease in firmness observed during senescence in Kanzi apples was not due to middle lamella dissolution, as tissue failure still occurred by cell breakage. Copyright © 2016 Elsevier Ltd. All rights reserved.

CFD simulation of liquid-liquid dispersions in a stirred tank bioreactor

NASA Astrophysics Data System (ADS)

Gelves, R.

2013-10-01

In this paper simulations were developed in order to allow the examinations of drop sizes in liquid-liquid dispersions (oil-water) in a stirred tank bioreactor using CFD simulations (Computational Fluid Dynamics). The effects of turbulence, rotating flow, drop breakage were simulated by using the k-e, MRF (Multiple Reference Frame) and PBM (Population Balance Model), respectively. The numerical results from different operational conditions are compared with experimental data obtained from an endoscope technique and good agreement is achieved. Motivated by these simulated and experimental results CFD simulations are qualified as a very promising tool for predicting hydrodynamics and drop sizes especially useful for liquid-liquid applications which are characterized by the challenging problem of emulsion stability due to undesired drop sizes.

Batch and continuous production of stable dense suspensions of drug nanoparticles in a wet stirred media mill

NASA Astrophysics Data System (ADS)

Afolabi, Afola we mi

One way to improve the bioavailability of poorly water-soluble drugs is to reduce particle size of drug crystals down to nanoscale via wet stirred media milling. An increase in total surface area per mass loading of the drug and specific surface area as well as reduced external mass transfer resistance allow a faster dissolution of the poorly-water soluble drug from nanocrystals. To prevent aggregation of nanoparticles, polymers and surfactants are dissolved in water acting as stabilizers via adsorption onto the drug crystals. In the last two decades, ample experimental data were generated in the area of wet stirred media milling for the production of drug nanoparticle suspensions. However, a fundamental scientific/engineering understanding of various aspects of this process is still lacking. These challenges include elucidation of the governing mechanism(s) during nanoparticle formation and physical stabilization of the nanosuspension with the use of polymers and surfactants (formulation parameters), understanding the impact of process parameters in the context of first-principle-based models, and production of truly nanosized drug particles (10-100 nm) with acceptable physical stability and minimal contamination with the media. Recirculation mode of milling operation, where the drug suspension in a holding tank continuously circulates through the stirred media mill, has been commonly used in lab, pilot, and commercial scales. Although the recirculation is continuous, the recirculation operation mode is overall a batch operation, requiring significant number of batches for a large-volume pharmaceutical product. Hence, development and investigation of a truly continuous process should offer significant advantages. To explain the impact of some of the processing parameters, stress intensity and stress number concepts were widely used in literature, which do not account for the effect of suspension viscosity explicitly. The impact of the processing parameters has not been explained in a predictive and reliable manner. In this dissertation, a comprehensive investigation of the production of Griseofulvin nanosuspensions in a wet stirred media mill operating in both the recirculation and continuous modes has been conducted to address the aforementioned fundamental challenges. Griseofulvin has been selected as a model poorly water-soluble BCS Class II drug. Impact of various formulation parameters such as stabilizer type and loading as well as processing parameters such as rotor speed, bead loading, bead size, suspension flow rate and drug loading was studied. A major novelty of the present contribution is that the impact of processing and formulation parameters has been analyzed and interpreted using a combined experimental-theoretical (microhydrodynamic model) approach. Such a comprehensive approach allowed us to intensify the process for the production of sub-100 nm drug particles, which could not be produced with top-down approaches in the literature so far. In addition, a multi-pass mode of continuous operation was developed and the so-called "Rehbinder effect", which has not been shown for the breakage of drug particles, was also elucidated. The dissertation work (1) indicated the need for a minimum polymeric stabilizer-to-drug ratio for proper stabilization of drug nanosuspensions as dictated by polymer adsorption and synergistic interactions between a polymeric stabilizer and a surfactant, (2) demonstrated the existence of an optimum polymer concentration from a breakage rate perspective in the presence of a surfactant, which results from the competing effects of viscous dampening and enhanced steric stabilization at higher polymer concentration, (3) developed fundamental understanding of the breakage dynamics-processing-formulation relationships and rationalized preparation of a single highly drug- loaded batch (20% or higher) instead of multiple dilute batches, (4) designed an intensified process for faster preparation of sub-100 nm particles with reduced specific energy consumption and media wear (i.e. minimal drug contamination), and (5) provided first evidence for the proof of Rehbinder effect during the milling of drugs. Not only do the polymers and surfactants allow proper physical stabilization of the nanoparticles in the suspensions, but they also do facilitate drug particle breakage. This dissertation also discusses applications of nanosuspensions and practical issues encountered during wet media milling.

[Effect of Moxibustion Preconditioning with Seed-sized Moxa Cones on Myocardial Infarction Size and Beclin 1 Expression in Myocardial Ischemia-reperfusion Injury Rats].

PubMed

Bai, Hua; Lu, Sheng-Feng; Chen, Wan-Ying; Zhong, Ze-Hao; Gu, Yi-Huang

2017-12-25

To observe the effect of moxibustion (Moxi) preconditioning with seed-sized moxa cones on myocardial ischemia-reperfusion injury (MI/RI) at different stages, and to analyze the correlation between this effect and the expression of autophagy related protein Beclin 1. This study contains two parts: 1) changes of myocardial pathological injury and percentages of myocardial infarcted area at different time-points after modeling and Moxi intervention, and 2) effect of Moxi on contents of serum cardiac troponin T(cTnT) and expression of myocardial Bcl-2, Bax and Beclin 1 proteins. In the first part, 42 SD rats were randomly divided into model group, 1 day (d) Moxi group, 2 d Moxi group, 3 d Moxi group，4 d Moxi group, 5 d Moxi group and 7 d Moxi group. The model of MI/RI was established by ligating the left anterior descending coronary artery (LAD) for 30 min and reperfusion for 240 min. The electrocardiogram (ECG) of standard limb lead Ⅱ was monitored and the heart was taken 4 h after reperfusion for examining myocardial infarcted size with triphenyl tetrazolium chloride (TTC) staining. In the second part, 48 SD rats were randomized into sham-operation, model, moxibustion and autophagy inhibitor (3-MA) groups, with 12 rats in each group. The serum cTnT level was assayed and histopathological changes of the myocardial tissue below the ligation site were examined with HE staining, and the expression levels of Bcl-2, Bax and Beclin 1 proteins in the myocardial tissue below the LAD-ligated site were detected using Western blot. Compared with the model group, the percentages of myocardial infarcted area were significantly decreased in the 4 d, 5 d and 7 d Moxi groups ( P <0.05), but without significant differences among the 3 Moxi groups ( P >0.05). The state of MI-induced breakage and disordered arrangement of myocardial fibers with interstitial edema and inflammatory cell infiltration at the MI stage in the Moxi group and at the reperfusion stage in the autophagy inhibitor group was relatively lighter. The levels of serum cTnT content and Bax/Bcl-2 and Beclin 1 protein expression at the MI and reperfusion stages were significantly higher in the model group than in the sham-operation group ( P <0.01), and considerably lower in the Moxi and autophagy groups than in the model group ( P <0.01). The serum cTnT content, ratio of Bax/Bcl-2 expression and Beclin 1 expression levels at the MI and reperfusion stages were significantly lower in the autophagy inhibitor group than in the Moxi group ( P <0.05). Moxibustion with seed-sized moxa cones at "Neiguan" (PC 6) can effectively alleviate myocardial ischemia in MI/RI rats, which is probably related to its effect in down-regulating Bax/Bcl-2 and Beclin 1 expression and in inhibiting autophagy.

MG/CA RATIOS IN STRESSED FORAMINIFERA, AMPHISTEGINA GIBBOSA, FROM THE FLORIDA KEYS. (R825869)

EPA Science Inventory

Abstract

Since 1991, significant proportions of Amphistegina populations in the Florida Keys and elsewhere have exhibited stress symptoms that include loss of symbiont color (`bleaching'), anomalous shell breakage and reproductive damage. Previous studie...

5 CFR 1605.1 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... this date on payment records to report makeup or late contributions or late loan payments. Attributable... makeup or late contribution, the attributable pay date is the “as of” date of the erroneous makeup or late contribution. Breakage means the loss incurred or the gain realized on makeup or late...

ANEUPLOIDY AND CHROMOSOME BREAKAGE IN SWIM-UP VERSUS UNPROCESSED SEMEN FROM TWENTY HEALTHY MEN

EPA Science Inventory

Toxicologic and epidemiologic studies have investigated a number of factors believed to induce cytogenetic damage in human sperm cells in order to estimate heritable risk to future generations. Most of these studies, however, have not enriched research semen specimens for fertil...

5 CFR 1605.11 - Makeup of missed or insufficient contributions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... associated breakage to the participant's account in accordance with § 1605.2. (c) Employee makeup... employing agency acknowledges that an error has occurred which has caused a smaller amount of employee... establish a schedule to make up the deficient contributions through future payroll deductions. Employee...

EVALUATION OF CHROMOSOME BREAKAGE AND DNA INTEGRITY IN SPERM: AN INVESTIGATION OF REMOTE SEMEN COLLECTION CONDITIONS

EPA Science Inventory

Home collection of ejaculated semen would facilitate participation rates and geographic diversity in reproductive epidemiology studies. Our study addressed concerns that home collection and overnight mail return might induce chromosome/DNA damage. We collected semen from 10 hea...

Fine Mapping and Introgressing a Fissure Resistance Locus

USDA-ARS?s Scientific Manuscript database

Rice (Oryza sativa L.) kernel fissuring is a major concern of both rice producers and millers. Fissures are small cracks in rice kernels that increase breakage among kernels when transported or milled, which decrease the value of processed rice. This study employed molecular gene tagging methods to ...

Impact of experimental gins on fiber quality parameters

USDA-ARS?s Scientific Manuscript database

Stripper harvested cotton usually contains approximately 6 to 8 times higher levels of trash than machine picked cotton. Ginning in stripper areas should be made more efficient at removing the trash particles while preserving fiber quality. Fiber breakage is a concern at two junctures: the saw gins ...

Single-step affinity purification for fungal proteomics.

PubMed

Liu, Hui-Lin; Osmani, Aysha H; Ukil, Leena; Son, Sunghun; Markossian, Sarine; Shen, Kuo-Fang; Govindaraghavan, Meera; Varadaraj, Archana; Hashmi, Shahr B; De Souza, Colin P; Osmani, Stephen A

2010-05-01

A single-step protein affinity purification protocol using Aspergillus nidulans is described. Detailed protocols for cell breakage, affinity purification, and depending on the application, methods for protein release from affinity beads are provided. Examples defining the utility of the approaches, which should be widely applicable, are included.

5 CFR 1620.46 - Agency responsibilities.

Code of Federal Regulations, 2010 CFR

2010-01-01

... eligible employees and notify them of their options under these regulations and the time period within... making payments to the record keeper for all contributions and attributable breakage will obtain from... making the payments to the record keeper will determine the procedure to follow in order to collect...

48 CFR 31.205-19 - Insurance and indemnification.

Code of Federal Regulations, 2011 CFR

2011-10-01

... keeping with sound business practice, are allowable; and (ii) Minor losses, such as spoilage, breakage, and disappearance of small hand tools that occur in the ordinary course of business and that are not... business. (b) For purposes of applying the provisions of this subsection, the Government considers...

Breakage mechanics for granular materials in surface-reactive environments

NASA Astrophysics Data System (ADS)

Zhang, Yida; Buscarnera, Giuseppe

2018-03-01

It is known that the crushing behaviour of granular materials is sensitive to the state of the fluids occupying the pore space. Here, a thermomechanical theory is developed to link such macroscopic observations with the physico-chemical processes operating at the microcracks of individual grains. The theory relies on the hypothesis that subcritical fracture propagation at intra-particle scale is the controlling mechanism for the rate-dependent, water-sensitive compression of granular specimens. First, the fracture of uniaxially compressed particles in surface-reactive environments is studied in light of irreversible thermodynamics. Such analysis recovers the Gibbs adsorption isotherm as a central component linking the reduction of the fracture toughness of a solid to the increase of vapour concentration. The same methodology is then extended to assemblies immersed in wet air, for which solid-fluid interfaces have been treated as a separate phase. It is shown that this choice brings the solid surface energy into the dissipation equations of the granular matrix, thus providing a pathway to (i) integrate the Gibbs isotherm with the continuum description of particle assemblies and (ii) reproduce the reduction of their yield strength in presence of high relative humidity. The rate-effects involved in the propagation of cracks and the evolution of breakage have been recovered by considering non-homogenous dissipation potentials associated with the creation of surface area at both scales. It is shown that the proposed model captures satisfactorily the compression response of different types of granular materials subjected to varying relative humidity. This result was achieved simply by using parameters based on the actual adsorption characteristics of the constituting minerals. The theory therefore provides a physically sound and thermodynamically consistent framework to study the behaviour of granular solids in surface-reactive environments.

Rheology of granular materials composed of crushable particles.

PubMed

Nguyen, Duc-Hanh; Azéma, Émilien; Sornay, Philippe; Radjaï, Farhang

2018-04-11

We investigate sheared granular materials composed of crushable particles by means of contact dynamics simulations and the bonded-cell model for particle breakage. Each particle is paved by irregular cells interacting via cohesive forces. In each simulation, the ratio of the internal cohesion of particles to the confining pressure, the relative cohesion, is kept constant and the packing is subjected to biaxial shearing. The particles can break into two or more fragments when the internal cohesive forces are overcome by the action of compressive force chains between particles. The particle size distribution evolves during shear as the particles continue to break. We find that the breakage process is highly inhomogeneous both in the fragment sizes and their locations inside the packing. In particular, a number of large particles never break whereas a large number of particles are fully shattered. As a result, the packing keeps the memory of its initial particle size distribution, whereas a power-law distribution is observed for particles of intermediate size due to consecutive fragmentation events whereby the memory of the initial state is lost. Due to growing polydispersity, dense shear bands are formed inside the packings and the usual dilatant behavior is reduced or cancelled. Hence, the stress-strain curve no longer passes through a peak stress, and a progressive monotonic evolution towards a pseudo-steady state is observed instead. We find that the crushing rate is controlled by the confining pressure. We also show that the shear strength of the packing is well expressed in terms of contact anisotropies and force anisotropies. The force anisotropy increases while the contact orientation anisotropy declines for increasing internal cohesion of the particles. These two effects compensate each other so that the shear strength is nearly independent of the internal cohesion of particles.

Minimising Backbreak at the Dewan Cement Limestone Quarry Using an Artificial Neural Network

NASA Astrophysics Data System (ADS)

Muhammad, Khan; Shah, Akram

2017-12-01

Backbreak, defined as excessive breakage behind the last row of blastholes in blasting operations at a quarry, causes destabilisation of rock slopes, improper fragmentation, minimises drilling efficiency. In this paper an artificial neural network (ANN) is applied to predict backbreak, using 12 input parameters representing various controllable factors, such as the characteristics of explosives and geometrical blast design, at the Dewan Cement limestone quarry in Hattar, Pakistan. This ANN was trained with several model architectures. The 12-2-1 ANN model was selected as the simplest model yielding the best result, with a reported correlation coefficient of 0.98 and 0.97 in the training and validation phases, respectively. Sensitivity analysis of the model suggested that backbreak can be reduced most effectively by reducing powder factor, blasthole inclination, and burden. Field tests were subsequently carried out in which these sensitive parameters were varied accordingly; as a result, backbreak was controlled and reduced from 8 m to less than a metre. The resulting reduction in powder factor (kg of explosives used per m3 of blasted material) also reduced blasting costs.

Towards quality by design in pharmaceutical manufacturing: modelling and control of air jet mills

NASA Astrophysics Data System (ADS)

Bhonsale, Satyajeet; Telen, Dries; Stokbroekx, Bard; Van Impe, Jan

2017-06-01

Milling is an important step in pharmaceutical manufacturing as it not only determines the final formulation of the drug product, but also influences the bioavailability and dissolution rate of the active pharmaceutical ingredient (API). In this respect, the air jet mill (AJM) is most commonly used in the pharmaceutical industry as it is a non-contaminating and non-degrading self-classifying process capable of delivering narrow particle size distributions (PSD). Keeping the principles of Quality by Design in mind, the Critical Process Parameters (CPPs) of the AJM have been identified to be the pressures at the grinding nozzles, and the feed rate which affect the PSD, surface charge and the morphology of the product (i.e. the Critical Material Attributes (CMAs)). For the purpose of this research, the PSD is considered to be the only relevant CMA. A population balance based model is proposed to simulate the dynamics milling operation by utilizing the concept of breakage functions. This model agrees qualitatively with experimental observations of the air jet mill unit present at Janssen Pharmaceutica but further steps for model validation need to be carried out.

29 CFR 1926.500 - Scope, application, and definitions applicable to this subpart.

Code of Federal Regulations, 2012 CFR

2012-07-01

... protection requirements for employees performing steel erection work (except for towers and tanks) are... protection systems, except in relation to steel erection activities and the use of equipment covered by... refusal, breakage, or separation of component parts. Load refusal is the point where the ultimate strength...

29 CFR 1926.500 - Scope, application, and definitions applicable to this subpart.

Code of Federal Regulations, 2011 CFR

2011-07-01

... protection requirements for employees performing steel erection work (except for towers and tanks) are... protection systems, except in relation to steel erection activities and the use of equipment covered by... refusal, breakage, or separation of component parts. Load refusal is the point where the ultimate strength...

29 CFR 1926.500 - Scope, application, and definitions applicable to this subpart.

Code of Federal Regulations, 2013 CFR

2013-07-01

... protection requirements for employees performing steel erection work (except for towers and tanks) are... protection systems, except in relation to steel erection activities and the use of equipment covered by... refusal, breakage, or separation of component parts. Load refusal is the point where the ultimate strength...

18 CFR 367.1630 - Account 163, Stores expense undistributed.

Code of Federal Regulations, 2010 CFR

2010-04-01

... damages. (7) Insurance on materials and supplies and on stores equipment. (8) Losses due to breakage... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Account 163, Stores expense undistributed. 367.1630 Section 367.1630 Conservation of Power and Water Resources FEDERAL ENERGY...

49 CFR 176.710 - Care following leakage or sifting of radioactive materials.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 2 2011-10-01 2011-10-01 false Care following leakage or sifting of radioactive materials. 176.710 Section 176.710 Transportation Other Regulations Relating to Transportation PIPELINE AND... sifting of radioactive materials. (a) In case of fire, collision, or breakage involving any shipment of...

27 CFR 25.292 - Daily records of operations.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., or destroyed. (15) Beer received from other breweries or received from pilot brewing plants. (16) Beer and cereal beverage lost due to breakage, theft, casualty, or other unusual cause. (17) Brewing materials sold or transferred to pilot brewing plants (including the name and address of the person to whom...

27 CFR 25.292 - Daily records of operations.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., or destroyed. (15) Beer received from other breweries or received from pilot brewing plants. (16) Beer and cereal beverage lost due to breakage, theft, casualty, or other unusual cause. (17) Brewing materials sold or transferred to pilot brewing plants (including the name and address of the person to whom...

Exploring biosensor applications with cotton cellulose nanocrystalline protein and peptide conjugates

USDA-ARS?s Scientific Manuscript database

Sensor I: Nano-crystalline preparations were produced through acid hydrolysis and mechanical breakage of the cotton fibers from a scoured and bleached cotton fabric and a scoured and bleached, mercerized fabric, which was shown to produce cellulose I (NCI) and cellulose II (NCII) crystals respective...

Hazard report. Internal wire breakage in reusable electrosurgical active electrode cables may cause sparking and surgical fires.

PubMed

2009-07-01

Breaks in the internal wires of reusable electrosurgical active electrode cables can increase the risk of injuries and surgical fires. Careful visual and manual inspection during reprocessing and immediately before use, coupled with periodic replacement, can help limit the risk.

Associations between single nucleotide polymorphisms in folate uptake and metabolizing genes with blood folate, homocysteine and DNA uracil concentrations

USDA-ARS?s Scientific Manuscript database

Background: Folate is an essential nutrient which supports nucleotide synthesis and biological methylation reactions. Diminished folate status results in chromosome breakage and is associated with several diseases including colorectal cancer. Folate status is also inversely related to plasma homocys...

Dissection of genetic architecture of grain chalk using NIR spectroscopy

USDA-ARS?s Scientific Manuscript database

Chalk is a major quality characteristic that causes grain breakage during milling and loss of crop value. In this study, we sought to elucidate the quantitatively inherited grain chalk trait in rice and to conduct genome-wide association mapping to identify SNPs and candidate genes associated with ...

49 CFR 238.303 - Exterior calendar day mechanical inspection of passenger equipment.

Code of Federal Regulations, 2010 CFR

2010-10-01

... to prevent the pin from falling out of place in case of breakage. (5) The suspension system... pneumatic suspension system component inflates or deflates, as applicable, correctly and otherwise operates... secondary braking system is in operating mode and does not have any known defective condition which prevents...

49 CFR 178.338-17 - Pumps and compressors.

Code of Federal Regulations, 2010 CFR

2010-10-01

... PACKAGINGS Specifications for Containers for Motor Vehicle Transportation § 178.338-17 Pumps and compressors. (a) Liquid pumps and gas compressors, if used, must be of suitable design, adequately protected against breakage by collision, and kept in good condition. They may be driven by motor vehicle power take...

49 CFR 178.337-15 - Pumps and compressors.

Code of Federal Regulations, 2010 CFR

2010-10-01

... PACKAGINGS Specifications for Containers for Motor Vehicle Transportation § 178.337-15 Pumps and compressors. (a) Liquid pumps or gas compressors, if used, must be of suitable design, adequately protected against breakage by collision, and kept in good condition. They may be driven by motor vehicle power take...

Chile stand management for mechanical green chile harvest

USDA-ARS?s Scientific Manuscript database

Currently the red chile crop is mechanically harvested. Because the pods will be dehydrated before consumption, breakage and bruising of red pods is not a concern. Green chile, however, is currently hand harvested because of the fragile nature of the fruit and the need to avoid pod damage. Hand h...

49 CFR 179.220-18 - Bottom outlets.

Code of Federal Regulations, 2013 CFR

2013-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non... their attachments shall be secured to car by at at least 3/8-inch chain, or its equivalent, except that... jacketed, in which case the breakage groove or its equivalent must be below the steam chamber but above the...

14 CFR 25.855 - Cargo or baggage compartments.

Code of Federal Regulations, 2013 CFR

2013-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Fire Protection § 25... applicable test criteria prescribed in part I of appendix F of this part or other approved equivalent methods... movement of cargo in the compartment, and (2) Their breakage or failure will not create a fire hazard. (f...

14 CFR 25.855 - Cargo or baggage compartments.

Code of Federal Regulations, 2011 CFR

2011-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Fire Protection § 25... applicable test criteria prescribed in part I of appendix F of this part or other approved equivalent methods... movement of cargo in the compartment, and (2) Their breakage or failure will not create a fire hazard. (f...

14 CFR 25.855 - Cargo or baggage compartments.

Code of Federal Regulations, 2010 CFR

2010-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Fire Protection § 25... applicable test criteria prescribed in part I of appendix F of this part or other approved equivalent methods... movement of cargo in the compartment, and (2) Their breakage or failure will not create a fire hazard. (f...

14 CFR 25.855 - Cargo or baggage compartments.

Code of Federal Regulations, 2014 CFR

2014-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Fire Protection § 25... applicable test criteria prescribed in part I of appendix F of this part or other approved equivalent methods... movement of cargo in the compartment, and (2) Their breakage or failure will not create a fire hazard. (f...

14 CFR 25.855 - Cargo or baggage compartments.

Code of Federal Regulations, 2012 CFR

2012-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Fire Protection § 25... applicable test criteria prescribed in part I of appendix F of this part or other approved equivalent methods... movement of cargo in the compartment, and (2) Their breakage or failure will not create a fire hazard. (f...

Flexor tendon repair with a knotless, bidirectional barbed suture: an in vivo biomechanical analysis.

PubMed

Maddox, Grady E; Ludwig, Jonathan; Craig, Eric R; Woods, David; Joiner, Aaron; Chaudhari, Nilesh; Killingsworth, Cheryl; Siegal, Gene P; Eberhardt, Alan; Ponce, Brent

2015-05-01

To compare and analyze biomechanical properties and histological characteristics of flexor tendons either repaired by a 4-strand modified Kessler technique or using barbed suture with a knotless repair technique in an in vivo model. A total of 25 chickens underwent surgical transection of the flexor digitorum profundus tendon followed by either a 4-strand Kessler repair or a knotless repair with barbed suture. Chickens were randomly assigned to 1 of 3 groups with various postoperative times to death. Harvested tendons were subjected to biomechanical testing or histologic analysis. Harvested tendons revealed failures in 25% of knotless repairs (8 of 32) and 8% of 4-strand Kessler repairs (2 of 24). Biomechanical testing revealed no significant difference in tensile strength between 4-strand Kessler and barbed repairs; however, this lack of difference may be attributed to lower statistical power. We noted a trend toward a gradual decrease in strength over time for barbed repairs, whereas we noticed the opposite for the 4-strand Kessler repairs. Mode of failure during testing differed between repair types. The barbed repairs tended toward suture breakage as opposed to 4-strand Kessler repairs, which demonstrated suture pullout. Histological analysis identified no difference in the degree of inflammation or fibrosis; however, there was a vigorous foreign body reaction around the 4-strand Kessler repair and no such response around the barbed repairs. In this model, knotless barbed repairs trended toward higher in vivo failure rates and biomechanical inferiority under physiologic conditions, with each repair technique differing in mode of failure and respective histologic reaction. We are unable to recommend the use of knotless barbed repair over the 4-strand modified Kessler technique. For the repair techniques tested, surgeons should prefer standard Kessler repairs over the described knotless technique with barbed suture. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Cracking-assisted fabrication of nanoscale patterns for micro/nanotechnological applications

NASA Astrophysics Data System (ADS)

Kim, Minseok; Kim, Dong-Joo; Ha, Dogyeong; Kim, Taesung

2016-05-01

Cracks are frequently observed in daily life, but they are rarely welcome and are considered as a material failure mode. Interestingly, cracks cause critical problems in various micro/nanofabrication processes such as colloidal assembly, thin film deposition, and even standard photolithography because they are hard to avoid or control. However, increasing attention has been given recently to control and use cracks as a facile, low-cost strategy for producing highly ordered nanopatterns. Specifically, cracking is the breakage of molecular bonds and occurs simultaneously over a large area, enabling fabrication of nanoscale patterns at both high resolution and high throughput, which are difficult to obtain simultaneously using conventional nanofabrication techniques. In this review, we discuss various cracking-assisted nanofabrication techniques, referred to as crack lithography, and summarize the fabrication principles, procedures, and characteristics of the crack patterns such as their position, direction, and dimensions. First, we categorize crack lithography techniques into three technical development levels according to the directional freedom of the crack patterns: randomly oriented, unidirectional, or multidirectional. Then, we describe a wide range of novel practical devices fabricated by crack lithography, including bioassay platforms, nanofluidic devices, nanowire sensors, and even biomimetic mechanosensors.

Biomechanical investigation of an alternative concept to angular stable plating using conventional fixation hardware.

PubMed

Windolf, Markus; Klos, Kajetan; Wähnert, Dirk; van der Pol, Bas; Radtke, Roman; Schwieger, Karsten; Jakob, Roland P

2010-05-21

Angle-stable locking plates have improved the surgical management of fractures. However, locking implants are costly and removal can be difficult. The aim of this in vitro study was to evaluate the biomechanical performance of a newly proposed crossed-screw concept ("Fence") utilizing conventional (non-locked) implants in comparison to conventional LC-DCP (limited contact dynamic compression plate) and LCP (locking compression plate) stabilization, in a human cadaveric diaphyseal gap model. In eight pairs of human cadaveric femora, one femur per pair was randomly assigned to receive a Fence construct with either elevated or non-elevated plate, while the contralateral femur received either an LCP or LC-DCP instrumentation. Fracture gap motion and fatigue performance under cyclic loading was evaluated successively in axial compression and in torsion. Results were statistically compared in a pairwise setting. The elevated Fence constructs allowed significantly higher gap motion compared to the LCP instrumentations (axial compression: p

Fiber Breakage Model for Carbon Composite Stress Rupture Phenomenon: Theoretical Development and Applications

NASA Technical Reports Server (NTRS)

Murthy, Pappu L. N.; Phoenix, S. Leigh; Grimes-Ledesma, Lorie

2010-01-01

Stress rupture failure of Carbon Composite Overwrapped Pressure Vessels (COPVs) is of serious concern to Science Mission and Constellation programs since there are a number of COPVs on board space vehicles with stored gases under high pressure for long durations of time. It has become customary to establish the reliability of these vessels using the so called classic models. The classical models are based on Weibull statistics fitted to observed stress rupture data. These stochastic models cannot account for any additional damage due to the complex pressure-time histories characteristic of COPVs being supplied for NASA missions. In particular, it is suspected that the effects of proof test could significantly reduce the stress rupture lifetime of COPVs. The focus of this paper is to present an analytical appraisal of a model that incorporates damage due to proof test. The model examined in the current paper is based on physical mechanisms such as micromechanics based load sharing concepts coupled with creep rupture and Weibull statistics. For example, the classic model cannot accommodate for damage due to proof testing which every flight vessel undergoes. The paper compares current model to the classic model with a number of examples. In addition, several applications of the model to current ISS and Constellation program issues are also examined.

Non-random distribution of DNA double-strand breaks induced by particle irradiation

NASA Technical Reports Server (NTRS)

Lobrich, M.; Cooper, P. K.; Rydberg, B.; Chatterjee, A. (Principal Investigator)

1996-01-01

Induction of DNA double-strand breaks (dsbs) in mammalian cells is dependent on the spatial distribution of energy deposition from the ionizing radiation. For high LET particle radiations the primary ionization sites occur in a correlated manner along the track of the particles, while for X-rays these sites are much more randomly distributed throughout the volume of the cell. It can therefore be expected that the distribution of dsbs linearly along the DNA molecule also varies with the type of radiation and the ionization density. Using pulsed-field gel and conventional gel techniques, we measured the size distribution of DNA molecules from irradiated human fibroblasts in the total range of 0.1 kbp-10 Mbp for X-rays and high LET particles (N ions, 97 keV/microns and Fe ions, 150 keV/microns). On a mega base pair scale we applied conventional pulsed-field gel electrophoresis techniques such as measurement of the fraction of DNA released from the well (FAR) and measurement of breakage within a specific NotI restriction fragment (hybridization assay). The induction rate for widely spaced breaks was found to decrease with LET. However, when the entire distribution of radiation-induced fragments was analysed, we detected an excess of fragments with sizes below about 200 kbp for the particles compared with X-irradiation. X-rays are thus more effective than high LET radiations in producing large DNA fragments but less effective in the production of smaller fragments. We determined the total induction rate of dsbs for the three radiations based on a quantitative analysis of all the measured radiation-induced fragments and found that the high LET particles were more efficient than X-rays at inducing dsbs, indicating an increasing total efficiency with LET. Conventional assays that are based only on the measurement of large fragments are therefore misleading when determining total dsb induction rates of high LET particles. The possible biological significance of this non-randomness for dsb induction is discussed.

Comparison of Wiltse's paraspinal approach and open book laminectomy for thoracolumbar burst fractures with greenstick lamina fractures: a randomized controlled trial.

PubMed

Chen, Zhi-da; Wu, Jin; Yao, Xiao-Tao; Cai, Tao-Yi; Zeng, Wen-Rong; Lin, Bin

2018-03-02

Posterior short-segment pedicle screw fixation is used to treat thoracolumbar burst fractures. However, no randomized controlled studies have compared the efficacy of the two approaches--the Wiltse's paraspinal approach and open book laminectomy in the treatment of thoracolumbar burst fractures with greenstick lamina fractures. Patients with burst fractures of the thoracolumbar spine without neurological deficit were randomized to receive either the Wiltse's paraspinal approach (group A, 24 patients) or open book laminectomy (group B, 23 patients). Patients were followed postoperatively for average of 27.4 months. Clinical and radiographic data of the two approaches were collected and compared. Our results showed the anterior segmental height, kyphotic angle, visual analog scale (VAS) score, and Smiley-Webster Scale (SWS) score significantly improved postoperatively in both groups, indicating that both the Wiltse's paraspinal approach and open book laminectomy can effectively treat thoracolumbar burst fractures with greenstick lamina fractures. The Wiltse's paraspinal approach was found to have significantly shorter operating time, less blood loss, and shorter length of hospital stay compared to open book laminectomy. However, there were two (2/24) patients in group A that had neurological deficits postoperatively and required a second exploratory operation. Dural tears and/or cauda equina entrapment were subsequently found in four patients in group B and all two patients of neurological deficits in group A during operation. No screw loosening, plate breakage, or other internal fixation failures were found at final follow-up. The results demonstrated that either of the two surgical approaches can achieve satisfactory results in treating thoracolumbar burst fractures in patients with greenstick lamina fractures. However, if there is any clinical or radiographic suspicion of a dural tear and/or cauda equina entrapment pre-operation, patients should receive an open book laminectomy to avoid a second exploratory operation. More research is still needed to optimize clinical decision-making regarding surgical approach.

Periodic Inspections of Kahului and Laupahoehoe Breakwaters, Hawaii

DTIC Science & Technology

1994-09-01

the sea-side of the head and trunk of the west breakwater is beginning to show a slight concentration, or cluster , of breakage and this area should...type of Survey; AERIAL Date Survey Morthing(Y) ft. Easti( gmX ) ft. ELev.(Z) ft. Relative Movement (TXZ) Cumulative Movemenit (YX2) 93/01/08 AERIAL

Glassy-winged sharpshooter feeding does not cause air embolisms in xylem of well-watered plants.

USDA-ARS?s Scientific Manuscript database

Plant xylem vessels are under negative hydrostatic pressure (tension) as evapotranspiration of water from the leaf surface pulls the column of water in xylem upwards. When xylem fluid flux is under extreme tension, any puncture or breakage of the xylem vessel wall can cause formation of air embolis...

76 FR 37831 - Petitions for Modification of Application of Existing Mandatory Safety Standards

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-28

... strata breakage for the mine; (2) to facilitate methane drainage, degasification casing of suitable... on the shift prior to mining through the well. The methane monitor(s) on the continuous mining.... (8) When mining is in progress, tests for methane will be made with a hand-held methane detector at...

Characterization of prototype secondary lithium battery

NASA Technical Reports Server (NTRS)

Somoano, R.

1980-01-01

The performance characteristics of ambient temperature secondary lithium batteries were determined through continuous cycle tests with periodic current and voltage measurements. Cycle life of the lithium anode was found to be an important problem area as was the formation of dentrite breakage and subsequent shorting. Energy density was increased by using more efficient cathode structures.

The High Cost of Vandalism.

ERIC Educational Resources Information Center

Slaybaugh, David J.; Koneval, Virginia L.

This paper reports the results of a school vandalism survey made in school districts having populations of 6,000 or more. The report indicates what types of vandalism are most prevalent, which districts are hit hardest, and what parts of the school are most often attacked. The survey recognized four aspects of vandalism: (1) glass breakage; (2)…

Final Environmental Assessment for Force Structure Changes at Langley Air Force Base, VA

DTIC Science & Technology

2011-10-01

Shepard Blvd, Hampton, VA, 23665, DEQ PC No. 20095002, PC Case Status - Release Confirmed, Case Closed. Langley Air Force Base- Building 333, 90 Oak...NOISEXPO ‘77, Chicago , IL. March. White, R. 1972. Effects of Repetitive Sonic Booms on Glass Breakage. FAA Report FAA-RD-72- 43. April. 6

Preserving rice quality: fine mapping and introgressing a fissure resistance locus

USDA-ARS?s Scientific Manuscript database

Rice (Oryza sativa L.) kernel fissuring is a major concern of both rice producers and millers. Fissures are small cracks in the rice kernels that increase the percentage of breakage among the kernels when they are transported and milled, which decreases the value of processed rice. This study employ...

77 FR 71697 - Safety Zone; Overhead Cable Replacement, Maumee River, Toledo, OH

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-04

... that may lead to the discovery of a significant environmental impact from this rule. List of Subjects..., Toledo, OH (docket number USCG-2012-0948) in support of the replacement of electrical cables suspended... an equipment failure, an unforeseen breakage of one of the electrical cables and inclement weather...

Heterogeneous Diagnoses Underlying Radial Ray Anomalies.

PubMed

Sevilla-Montoya, Rosalba; Aguinaga, Mónica; Martínez, Alejandro; Razo, Guadalupe; Molina, Bertha; Frías, Sara; Grether, Patricia

2017-03-01

To review perinatal Radial Ray Anomaly (RRA) cases born at the National Institute of Perinatology, Mexico, and to reveal the heterogeneous diagnoses of these patients. All patients with RRA over a 18 mo period were included; 4/15 were detected prenatally and 11/15 postnatally. Karyotype was performed for all patients with bilateral RRA; and chromosomal breakage analysis, when the karyotype was normal. Fifteen RRA patients were identified: one with trisomy 18, three with an isolated defect, six with monogenic disease, four with a genetic association and one with diabetic embryopathy. Five were stillborn and two died during the early neonatal period; all of whom presented with multiple defects. Three of the live born patients and one stillborn with multiple defects had Fanconi anemia. RRAs carry a high perinatal mortality rate (47%) when they occur in association with other defects. The assessment of these patients needs to involve the combined use of ultrasound, clinical, genetic, cytogenetic and molecular testing. The present results indicate that the chromosome breakage test should always be performed to rule out Fanconi anemia in this group.

Experimental measurements and evaluation of the expanded water repellent perlite used for the cargo containment system of LNG carrier

NASA Astrophysics Data System (ADS)

Li, Manfeng; Ju, Yonglin

2017-10-01

To minimize the water absorption and to improve the thermal insulated properties of the insulation materials used for the cargo containment systems (CCSs) of LNG carrier, a kind of expanded water-repellent perlite has been developed by coating hydrophobic membrane onto the outer surface of the expanded perlite to change its physical and chemical characteristics. Considering the CCSs operated in a wide temperature range from environmental temperature to cryogenic temperature, the thermal analysis has been conducted to quantitatively determine the thermal insulted properties of the insulation materials. Furthermore, a double-sided guarded hot plate apparatus (GHP) is specifically designed and fabricated for the measurement of the thermal conductivities of the insulation specimens operated down to liquid nitrogen temperature. The breakage ratio associated with the water absorption and the thermal conductivity of the expanded water-repellent perlite is firstly proposed, and then a series of experiments are carried out to determine the thermal conductivity of the expanded water-repellent perlite ranging from room temperature to cryogenic temperature based on the different breakage ratios.

Shock wave lithotripsy: advances in technology and technique

PubMed Central

Lingeman, James E.; McAteer, James A.; Gnessin, Ehud; Evan, Andrew P.

2010-01-01

Shock wave lithotripsy (SWL) is the only noninvasive method for stone removal. Once considered as a primary option for the treatment of virtually all stones, SWL is now recognized to have important limitations that restrict its use. In particular, the effectiveness of SWL is severely limited by stone burden, and treatment with shock waves carries the risk of acute injury with the potential for long-term adverse effects. Research aiming to characterize the renal response to shock waves and to determine the mechanisms of shock wave action in stone breakage and renal injury has begun to suggest new treatment strategies to improve success rates and safety. Urologists can achieve better outcomes by treating at slower shock wave rate using a step-wise protocol. The aim is to achieve stone comminution using as few shock waves and at as low a power level as possible. Important challenges remain, including the need to improve acoustic coupling, enhance stone targeting, better determine when stone breakage is complete, and minimize the occurrence of residual stone fragments. New technologies have begun to address many of these issues, and hold considerable promise for the future. PMID:19956196

CH/sub 3/xxx/sup 13/CO/sub 2/ pairs in irradiated single crystals of CH/sub 3//sup 13/CO/sub 2/Lix2D/sub 2/0. [Gamma rays

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

Toriyama, K.; Iwasaki, M.

1976-10-01

The CH/sub 3/ radical trapped in irradiated single crystals of CH/sub 3//sup 13/CO/sub 2/Lix2D/sub 2/O has been found to interact with a /sup 13/CO/sub 2/ molecule, which is formed from the C--C bond breakage as a counterpart. The /sup 13/C superhyperfine coupling tensor was determined to be (-4.0, -3.3, -3.5) G. The /sup 13/CO/sub 2/ molecule is located in the direction of the unpaired electron orbital of CH/sub 3/ with the molecular axis perpendicular to it. The spectrum arising from the electron excess center CH/sub 3/ /sup 13/CO/sub 2//sup 2 -/ was also detected together with the CH/sub 3/ radical.more » Our results indicate that the CH/sub 3/xxx/sup 13/CO/sub 2/ pair is essentially a positive hole center formed from one electron loss followed by the C--C bond breakage. (AIP)« less

Primordial evolvability: Impasses and challenges.

PubMed

Vasas, Vera; Fernando, Chrisantha; Szilágyi, András; Zachár, István; Santos, Mauro; Szathmáry, Eörs

2015-09-21

While it is generally agreed that some kind of replicating non-living compounds were the precursors of life, there is much debate over their possible chemical nature. Metabolism-first approaches propose that mutually catalytic sets of simple organic molecules could be capable of self-replication and rudimentary chemical evolution. In particular, the graded autocatalysis replication domain (GARD) model, depicting assemblies of amphiphilic molecules, has received considerable interest. The system propagates compositional information across generations and is suggested to be a target of natural selection. However, evolutionary simulations indicate that the system lacks selectability (i.e. selection has negligible effect on the equilibrium concentrations). We elaborate on the lessons learnt from the example of the GARD model and, more widely, on the issue of evolvability, and discuss the implications for similar metabolism-first scenarios. We found that simple incorporation-type chemistry based on non-covalent bonds, as assumed in GARD, is unlikely to result in alternative autocatalytic cycles when catalytic interactions are randomly distributed. An even more serious problem stems from the lognormal distribution of catalytic factors, causing inherent kinetic instability of such loops, due to the dominance of efficiently catalyzed components that fail to return catalytic aid. Accordingly, the dynamics of the GARD model is dominated by strongly catalytic, but not auto-catalytic, molecules. Without effective autocatalysis, stable hereditary propagation is not possible. Many repetitions and different scaling of the model come to no rescue. Despite all attempts to show the contrary, the GARD model is not evolvable, in contrast to reflexively autocatalytic networks, complemented by rare uncatalyzed reactions and compartmentation. The latter networks, resting on the creation and breakage of chemical bonds, can generate novel ('mutant') autocatalytic loops from a given set of environmentally available compounds. Real chemical reactions that make or break covalent bonds, rather than mere incorporation of components, are necessary for open-ended evolvability. The issue of whether or not several concrete chemical systems (rather than singular curiosities) could realize reflexively autocatalytic macromolecular networks will ultimately determine the relevance of metabolism-first approaches to the origin of life, as stepping stones towards true open-endedness that requires the combination of rich combinatorial chemistry controlled by information stored in template replicators. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of ultrasound pretreatment on the characteristic evolutions of drinking water treatment sludge and its impact on coagulation property of sludge recycling process.

PubMed

Zhou, Zhiwei; Yang, Yanling; Li, Xing

2015-11-01

Large amounts of drinking water treatment sludge (DWTS) are produced during the flocculation or flotation process. The recycling of DWTS is important for reducing and reclaiming the waste residues from drinking water treatment. To improve the coagulation step of the DWTS recycling process, power ultrasound was used as a pretreatment to disintegrate the DWTS and degrade or inactivate the constituents that are difficult to remove by coagulation. The effects of ultrasound pretreatment on the characteristics of DWTS, including the extent of disintegration, variation in DWTS floc characteristics, and DWTS dewaterability, were investigated. The capacity of the recycling process to remove particulates and organic matter from low-turbidity surface water compared to a control treatment process without DWTS was subsequently evaluated. The coagulation mechanism was further investigated by analyzing the formation, breakage, and re-growth of re-coagulated flocs. Our results indicated that under the low energy density applied (0.03-0.033 W/mL) for less than 15 min at a frequency of 160 kHz, the level of organic solubilization was less elevated, which was evidenced by the lower release of proteins and polysaccharides and lower fluorescence intensities of humic- and protein-like substances. The applied ultrasound conditions had an adverse effect on the dewaterability of the DWTS. Ultrasound pretreatment had no significant impact on the pH or surface charge of the DWTS flocs, whereas particle size decreased slightly and the specific surface area was moderately increased. The pollution removal capacity decreased somewhat for the recycled sonicated DWTS treatment, which was primarily ascribed to organic solubilization rather than variability in the floc characteristics of sonicated DWTS. The main coagulation mechanism was floc sweeping and physical adsorption. The breakage process of the flocs formed by the recycling process displayed distinct irreversibility, and the flocs were stronger and more resistant to breakage compared to those from the control treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of Ultraviolet Exposure on Impact Resistance of Ophthalmic Lenses.

PubMed

Chou, B Ralph; Dain, Stephen J; Cheng, Brian B

2015-12-01

To investigate the effect of ultraviolet radiation (UVR) on the impact resistance of organic ophthalmic lens materials. Plano power CR39, Phoenix, Trilogy, and polycarbonate lenses with various scratch-resistant (SR) and/or antireflection (AR) coatings were obtained in batches of 40 units. All lenses had a nominal thickness of 2 mm. Half of each batch was conditioned following the European Standard EN 168 protocol for the test of resistance to UVR (exposed group). The remaining lenses comprised an unexposed group for that combination of lens substrate and coating treatment. Each group was subjected to ballistic impact with 6-mm steel balls following the ZEST protocol to determine its mean breakage velocity. The difference in mean breakage velocity between exposed and unexposed groups of each combination of lens substrate and coating was assessed for statistical significance. Exposed uncoated CR39 showed a reduction in fracture velocity of 10.3 m/s whereas CR39 with ultra hard coat had a reduction of 3.5 m/s and CR39 with AR and SR coating had a reduction of 4.1 m/s. Scratch-resistant coated Phoenix had a reduction of 4.8 m/s whereas AR-coated Phoenix had a reduction of 3.7 m/s. The corresponding reductions for Trilogy were 3.9 and 17.8 m/s. All differences were significant at the p level of less than 0.05. Although we were unable to break unexposed SR-coated polycarbonate lenses with our test apparatus, exposed SR-coated polycarbonate had a mean breakage velocity of 142 m/s. Our data suggest that extended UVR exposure causes a significant reduction in the impact resistance of the ophthalmic lens substrates commonly used for occupational eye protectors. Protective lenses that have been exposed to high levels of UVR for extended periods should be replaced regularly to maintain optimal impact protection, even if they do not show visible damage owing to wear and tear.

Application of correspondence analysis in the assessment of mine tailings dam breakage risk in the Mediterranean region.

PubMed

Salgueiro, Ana Rita; Pereira, Henrique Garcia; Rico, Maria-Teresa; Benito, Gerado; Díez-Herreo, Andrés

2008-02-01

A new statistical approach for preliminary risk evaluation of breakage in tailings dam is presented and illustrated by a case study regarding the Mediterranean region. The objective of the proposed method is to establish an empirical scale of risk, from which guidelines for prioritizing the collection of further specific information can be derived. The method relies on a historical database containing, in essence, two sets of qualitative data: the first set concerns the variables that are observable before the disaster (e.g., type and size of the dam, its location, and state of activity), and the second refers to the consequences of the disaster (e.g., failure type, sludge characteristics, fatalities categorization, and downstream range of damage). Based on a modified form of correspondence analysis, where the second set of attributes are projected as "supplementary variables" onto the axes provided by the eigenvalue decomposition of the matrix referring to the first set, a "qualitative regression" is performed, relating the variables to be predicted (contained in the second set) with the "predictors" (the observable variables). On the grounds of the previously derived relationship, the risk of breakage in a new case can be evaluated, given observable variables. The method was applied in a case study regarding a set of 13 test sites where the ranking of risk obtained was validated by expert knowledge. Once validated, the procedure was included in the final output of the e-EcoRisk UE project (A Regional Enterprise Network Decision-Support System for Environmental Risk and Disaster Management of Large-Scale Industrial Spills), allowing for a dynamic historical database updating and providing a prompt rough risk evaluation for a new case. The aim of this section of the global project is to provide a quantified context where failure cases occurred in the past for supporting analogue reasoning in preventing similar situations.

[Analysis of reason and strategy for the failure of posterior pedicle screw short-segment internal fixation on thoracolumbar fractures].

PubMed

Xing, Jin-Ming; Peng, Wen-Ming; Shi, Chu-Yun; Xu, Lei; Pan, Qi-Huao

2013-03-01

To analyze the reason and strategy for failure of posterior pedicle screw short-segment internal fixation on thoracolumbar fractures. From March 2008 to December 2010,the clinical data of 18 patients with thoracolumbar fracture failed in posterior pedicle screw short-segment internal fixation were retrospectively analyzed. There were 11 males and 7 females with an average age of 37.2 years (ranged, 19 to 63). The time from the first operation to complication occurrence was from 6 to 44 months with an average of 14.3 months. Of them,fusion failure was in 7 cases (combined with screw breakage in 4 cases), the progressive neuro-dysfunction was in 5 cases,the progressive lumbodorsal pain was in 6 cases. All 18 patients with kyphosis were treated with anterior internal fixation remaining posterior fixation (9 cases) and anterior internal fixation after posterior fixation removal (9 cases). All the patients were followed up from 18 to 50 months with an average of 30.5 months. No intetnal fixation loosening and breakage were found, moreover, X-ray and lamellar CT showed bone healing well. Preoperative, postoperative at 3 months and at final follow-up, ODI score was respectively 31.6+/-5.1, 8.6+/-5.7, 8.3+/-3.2; VAS score was respectively 7.2+/-2.3, 2.3+/-0.7, 2.1+/-1.1; kyphosis angle was respectively (-21.2/-+7.8 degreeso, (-5.3+/-6.8 degrees ), (-5.8+/-7.8 )degrees. Compared with preoperative data ,above-listed items had obviously ameliorated(P<0.05). Treatment of thoracolumbar fracture with posterior pedicle screw short-segment internal fixation may result in the complications such as bone nonunion ,internal fixation breakage and progressive kyphosis. Anterior reconstruction may be a good strategy for the failure of posterior operation.

Biomechanical effect of the configuration of screw hole style on locking plate fixation in proximal humerus fracture with a simulated gap: A finite element analysis.

PubMed

Zhang, Ya-Kui; Wei, Hung-Wen; Lin, Kang-Ping; Chen, Wen-Chuan; Tsai, Cheng-Lun; Lin, Kun-Jhih

2016-06-01

Locking plate fixation for proximal humeral fractures is a commonly used device. Recently, plate breakages were continuously reported that the implants all have a mixture of holes allowing placement of both locking and non-locking screws (so-called combi plates). In commercialized proximal humeral plates, there still are two screw hole styles included "locking and dynamic holes separated" and "locking hole only" configurations. It is important to understand the biomechanical effect of different screw hole style on the stress distribution in bone plate. Finite element method was employed to conduct a computational investigation. Three proximal humeral plate models with different screw hole configurations were reconstructed depended upon an identical commercialized implant. A three-dimensional model of a humerus was created using process of thresholding based on the grayscale values of the CT scanning of an intact humerus. A "virtual" subcapital osteotomy was performed. Simulations were performed under an increasing axial load. The von Mises stresses around the screw holes of the plate shaft, the construct stiffness and the directional displacement within the fracture gap were calculated for comparison. The mean value of the peak von Mises stresses around the screw holes in the plate shaft was the highest for combi hole design while it was smallest for the locking and dynamic holes separated design. The stiffness of the plate-bone construct was 15% higher in the locking screw only design (132.6N/mm) compared with the combi design (115.0N/mm), and it was 4% higher than the combi design for the locking and dynamic holes separated design (119.5N/mm). The displacement within the fracture gap was greatest in the combi hole design, whereas it was smallest for the locking hole only design. The computed results provide a possible explanation for the breakages of combi plates revealed in clinical reports. The locking and dynamic holes separated design may be a better configuration to reduce the risk of plate fracture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Kinetic study of ferronickel slag grinding at variation of ball filling and ratio of feed to grinding balls

NASA Astrophysics Data System (ADS)

Sanwani, Edy; Ikhwanto, Muhammad

2017-01-01

The objective of this paper is to investigate the effect of ball filling and ratio of feed to grinding balls on the kinetic of grinding of ferronickel slag in a laboratory scale ball mill. The experiments were started by crushing the ferronickel slag samples using a roll crusher to produce -3 mesh (-6.7 mm) product. This product, after sampling and sample dividing processes, was then used as feed for grinding process. The grinding was performed with variations of ball filling and ratio of feed to grinding balls for 150 minutes. At every certain time interval, particle size analysis was carried out on the grinding product. The results of the experiments were also used to develop linear regression model of the effect of grinding variables on the P80 of the product. Based on this study, it was shown that P80 values of the grinding products declined sharply until 70 minutes of grinding time due to the dominant mechanism of impact breakage and then decreased slowly after 70 minutes until 150 minutes of grinding time due to dominant mechanism of attrition breakage. Kinetics study of the grinding process on variations of grinding ball filling showed that the optimum rate of formation of fine particles for 20%, 30%, 40% and 50% mill volume was achieved at a particle size of 400 µm in which the best initial rate of formation occurred at 50% volume of mill. At the variations of ratio of feed to grinding balls it was shown that the optimum rate of grinding for the ratio of 1:10, 1: 8 and 1: 6 was achieved at a particle size of 400 µm and for the ratio of 1: 4 was at 841 µm in which the best initial rate of formation occurred at a 1:10 ratio. In this study, it was also produced two regression models that can predict the P80 value of the grinding product as a function of the variables of grinding time, ball filling and the ratio of the feed to grinding balls.

Protective effects of pulmonary epithelial lining fluid on oxidative stress and DNA single-strand breaks caused by ultrafine carbon black, ferrous sulphate and organic extract of diesel exhaust particles

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

Chuang, Hsiao-Chi; Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan; Cheng, Yi-Ling

Pulmonary epithelial lining fluid (ELF) is the first substance to make contact with inhaled particulate matter (PM) and interacts chemically with PM components. The objective of this study was to determine the role of ELF in oxidative stress, DNA damage and the production of proinflammatory cytokines following physicochemical exposure to PM. Ultrafine carbon black (ufCB, 15 nm; a model carbonaceous core), ferrous sulphate (FeSO{sub 4}; a model transition metal) and a diesel exhaust particle (DEP) extract (a model organic compound) were used to examine the acellular oxidative potential of synthetic ELF and non-ELF systems. We compared the effects of exposuremore » to ufCB, FeSO{sub 4} and DEP extract on human alveolar epithelial Type II (A549) cells to determine the levels of oxidative stress, DNA single-strand breaks and interleukin-8 (IL-8) production in ELF and non-ELF systems. The effects of ufCB and FeSO{sub 4} on the acellular oxidative potential, cellular oxidative stress and DNA single-strand breakage were mitigated significantly by the addition of ELF, whereas there was no decrease following treatment with the DEP extract. There was no significant effect on IL-8 production following exposure to samples that were suspended in ELF/non-ELF systems. The results of the present study indicate that ELF plays an important role in the initial defence against PM in the pulmonary environment. Experimental components, such as ufCB and FeSO{sub 4}, induced the production of oxidative stress and led to DNA single-strand breaks, which were moderately prevented by the addition of ELF. These findings suggest that ELF plays a protective role against PM-driven oxidative stress and DNA damage. -- Highlights: ► To determine the role of ELF in ROS, DNA damage and IL-8 after exposure to PM. ► ufCB, FeSO{sub 4} and DEP extract were used to examine the protective effects of ELF. ► PM-driven oxidative stress and DNA single-strand breakage were mitigated by ELF. ► The findings suggest that ELF has a protective role against PM. ► The synthetic ELF system could reduce the use of animals in PM-driven ROS testing.« less

Crystallization of sodium chloride from a concentrated calcium chloride-potassium chloride-sodium chloride solution in a CMSMPR crystallizer: Observation of crystal size distribution and model validation

NASA Astrophysics Data System (ADS)

Choi, Byung Sang

Compared to overwhelming technical data available in other advanced technologies, knowledge about particle technology, especially in particle synthesis from a solution, is still poor due to the lack of available equipment to study crystallization phenomena in a crystallizer. Recent technical advances in particle size measurement such as Coulter counter and laser light scattering have made in/ex situ study of some of particle synthesis, i.e., growth, attrition, and aggregation, possible with simple systems. Even with these advancements in measurement technology, to grasp fully the crystallization phenomena requires further theoretical and technical advances in understanding such particle synthesis mechanisms. Therefore, it is the motive of this work to establish the general processing parameters and to produce rigorous experimental data with reliable performance and characterization that rigorously account for the crystallization phenomena of nucleation, growth, aggregation, and breakage including their variations with time and space in a controlled continuous mixed-suspension mixed-product removal (CMSMPR) crystallizer. This dissertation reports the results and achievements in the following areas: (1) experimental programs to support the development and validation of the phenomenological models and generation of laboratory data for the purpose of testing, refining, and validating the crystallization process, (2) development of laboratory well-mixed crystallizer system and experimental protocols to generate crystal size distribution (CSD) data, (3) the effects of feed solution concentration, crystallization temperature, feed flow rate, and mixing speed, as well as different types of mixers resulting in the evolution of CSDs with time from a concentrated brine solution, (4) with statistically designed experiments the effects of processing variables on the resultant particle structure and CSD at steady state were quantified and related to each of those operating conditions by studying the detailed crystallization processes, such as nucleation, growth, and breakage, as well as agglomeration. The purification of CaCl2 solution involving the crystallization of NaCl from the solution mixture of CaCl2, KCl, and NaCl as shipped from Dow Chemical, Ludington, in a CMSMPR crystallizer was studied as our model system because of its nucleation and crystal growth tendencies with less agglomeration. This project also generated a significant body of experimental data that are available at URL that is http://www.che.utah.edu/˜ring/CrystallizationWeb.

Two-compartmental population balance modeling of a pulsed spray fluidized bed granulation based on computational fluid dynamics (CFD) analysis.

PubMed

Liu, Huolong; Li, Mingzhong

2014-11-20

In this work a two-compartmental population balance model (TCPBM) was proposed to model a pulsed top-spray fluidized bed granulation. The proposed TCPBM considered the spatially heterogeneous granulation mechanisms of the granule growth by dividing the granulator into two perfectly mixed zones of the wetting compartment and drying compartment, in which the aggregation mechanism was assumed in the wetting compartment and the breakage mechanism was considered in the drying compartment. The sizes of the wetting and drying compartments were constant in the TCPBM, in which 30% of the bed was the wetting compartment and 70% of the bed was the drying compartment. The exchange rate of particles between the wetting and drying compartments was determined by the details of the flow properties and distribution of particles predicted by the computational fluid dynamics (CFD) simulation. The experimental validation has shown that the proposed TCPBM can predict evolution of the granule size and distribution within the granulator under different binder spray operating conditions accurately. Copyright © 2014 Elsevier B.V. All rights reserved.

Finite Element Simulation of Aluminium/GFRP Fibre Metal Laminate under Tensile Loading

NASA Astrophysics Data System (ADS)

Merzuki, M. N. M.; Rejab, M. R. M.; Romli, N. K.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Salleh, Salwani Mohd

2018-03-01

The response of a fibre metal laminate (FML) model to the tensile loading is predicted through a computational approach. The FML consisted with layers of aluminum alloy and embedded with one layer of composite material, Glass fibre Reinforced Plastic (GFRP). The glass fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy. A compression moulding technique was used in the process of a FML fabrication. The aluminium has been roughen by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure behaviour of the FML under the tensile loading. The responses on the FML under the tensile loading were numerically performed. The FML was modelled and analysed by using Abaqus/CAE 6.13 version. Based on the experimental and FE data of the tensile, the ultimate tensile stress is 120 MPa where delamination and fibre breakage happened. A numerical model was developed and agreed well with the experimental results. The laminate has an inelastic respond to increase the tensile loads which due to the plasticity of the aluminium layers.

Fundamental analysis of the failure of polymer-based fiber reinforced composites

NASA Technical Reports Server (NTRS)

Kanninen, M. F.; Rybicki, E. F.; Griffith, W. I.; Broek, D.

1976-01-01

A mathematical model is described which will permit predictions of the strength of fiber reinforced composites containing known flaws to be made from the basic properties of their constituents. The approach was to embed a local heterogeneous region (LHR) surrounding the crack tip into an anisotropic elastic continuum. The model should (1) permit an explicit analysis of the micromechanical processes involved in the fracture process, and (2) remain simple enough to be useful in practical computations. Computations for arbitrary flaw size and orientation under arbitrary applied load combinations were performed from unidirectional composites with linear elastic-brittle constituent behavior. The mechanical properties were nominally those of graphite epoxy. With the rupture properties arbitrarily varied to test the capability of the model to reflect real fracture modes in fiber composites, it was shown that fiber breakage, matrix crazing, crack bridging, matrix-fiber debonding, and axial splitting can all occur during a period of (gradually) increasing load prior to catastrophic fracture. The computations reveal qualitatively the sequential nature of the stable crack process that precedes fracture.

CRADA opportunities in removal of particulates from hot-gas streams by filtration

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

Smith, D H

1995-06-01

Our analyses of samples and operating data from the Pressurized Fluidized Bed Combustion (PFBC), cyclone, and filtration units of the Tidd Clean Coal demonstration facility show that calcined dolomitic sorbent reacted with SO{sub 2} (and O{sub 2}) to form Sulfates (CaSO{sub 4} and CaMgn [SO{sub 4}]n+1) not only in the PFBC bed, but also in the filtration vessel. Analyses of limited data from the journal literature suggest that the filter-vessel reactions may have produced sulfate {open_quotes}necks,{close_quotes} which bonded the particles together, thus substantially increasing the critical angle of repose and shear tensile strengths of the filtered powders. This proposed mechanismmore » rationalizes the {open_quotes}bridging{close_quotes} and other particle-accumulation problems that caused filter breakage. Engineering services potentially available to resolve these problems include elucidation and modeling of ex-situ and in-situ filter-vessel chemistry, measurement and modeling of particulate materials properties, and measurement and modeling of cleaning back-pulse aerodynamics and cleaning efficiencies.« less

Impact analyses for negative flexural responses (hogging) in railway prestressed concrete sleepers

NASA Astrophysics Data System (ADS)

Kaewunruen, S.; Ishida, T.; Remennikov, AM

2016-09-01

By nature, ballast interacts with railway concrete sleepers in order to provide bearing support to track system. Most train-track dynamic models do not consider the degradation of ballast over time. In fact, the ballast degradation causes differential settlement and impact forces acting on partial and unsupported tracks. Furthermore, localised ballast breakages underneath railseat increase the likelihood of centrebound cracks in concrete sleepers due to the unbalanced support under sleepers. This paper presents a dynamic finite element model of a standard-gauge concrete sleeper in a track system, taking into account the tensionless nature of ballast support. The finite element model was calibrated using static and dynamic responses in the past. In this paper, the effects of centre-bound ballast support on the impact behaviours of sleepers are highlighted. In addition, it is the first to demonstrate the dynamic effects of sleeper length on the dynamic design deficiency in concrete sleepers. The outcome of this study will benefit the rail maintenance criteria of track resurfacing in order to restore ballast profile and appropriate sleeper/ballast interaction.

Resilience of branching and massive corals to wave loading under sea level rise--a coupled computational fluid dynamics-structural analysis.

PubMed

Baldock, Tom E; Karampour, Hassan; Sleep, Rachael; Vyltla, Anisha; Albermani, Faris; Golshani, Aliasghar; Callaghan, David P; Roff, George; Mumby, Peter J

2014-09-15

Measurements of coral structural strength are coupled with a fluid dynamics-structural analysis to investigate the resilience of coral to wave loading under sea level rise and a typical Great Barrier Reef lagoon wave climate. The measured structural properties were used to determine the wave conditions and flow velocities that lead to structural failure. Hydrodynamic modelling was subsequently used to investigate the type of the bathymetry where coral is most vulnerable to breakage under cyclonic wave conditions, and how sea level rise (SLR) changes this vulnerability. Massive corals are determined not to be vulnerable to wave induced structural damage, whereas branching corals are susceptible at wave induced orbital velocities exceeding 0.5m/s. Model results from a large suite of idealised bathymetry suggest that SLR of 1m or a loss of skeleton strength of order 25% significantly increases the area of reef flat where branching corals are exposed to damaging wave induced flows. Copyright © 2014 Elsevier Ltd. All rights reserved.

25 CFR 542.2 - What are the definitions for this part?

Code of Federal Regulations, 2011 CFR

2011-04-01

... games, or gaming machines on a per day or cumulative basis. Ante means a player's initial wager or... in and supervising the operation and conduct of a craps game. Breakage means the difference between.... Card game means a game in which the gaming operation is not party to wagers and from which the gaming...

25 CFR 542.2 - What are the definitions for this part?

Code of Federal Regulations, 2013 CFR

2013-04-01

... games, or gaming machines on a per day or cumulative basis. Ante means a player's initial wager or... in and supervising the operation and conduct of a craps game. Breakage means the difference between.... Card game means a game in which the gaming operation is not party to wagers and from which the gaming...

25 CFR 542.2 - What are the definitions for this part?

Code of Federal Regulations, 2010 CFR

2010-04-01

... games, or gaming machines on a per day or cumulative basis. Ante means a player's initial wager or... in and supervising the operation and conduct of a craps game. Breakage means the difference between.... Card game means a game in which the gaming operation is not party to wagers and from which the gaming...

25 CFR 542.2 - What are the definitions for this part?

Code of Federal Regulations, 2012 CFR

2012-04-01

... games, or gaming machines on a per day or cumulative basis. Ante means a player's initial wager or... in and supervising the operation and conduct of a craps game. Breakage means the difference between.... Card game means a game in which the gaming operation is not party to wagers and from which the gaming...

25 CFR 542.2 - What are the definitions for this part?

Code of Federal Regulations, 2014 CFR

2014-04-01

... games, or gaming machines on a per day or cumulative basis. Ante means a player's initial wager or... in and supervising the operation and conduct of a craps game. Breakage means the difference between.... Card game means a game in which the gaming operation is not party to wagers and from which the gaming...

46 CFR 199.175 - Survival craft and rescue boat equipment.

Code of Federal Regulations, 2010 CFR

2010-10-01

... breakage-resistant material. (9) Fire extinguisher. The fire extinguisher must be approved under approval series 162.028. The fire extinguisher must be type B-C, size II, or larger. Two type B-C, size I fire... portions of the hull. (4) Bucket. The bucket must be made of corrosion-resistant material and should either...

How "Bright" is it to Use CFLs? A Look at the Controversy

ERIC Educational Resources Information Center

Miller, Roxanne Greitz

2008-01-01

Commonly referred to as CFLs, compact fluorescent light bulbs are rapidly replacing traditional incandescent light bulbs for residential use. However, controversy and even comic parody have arisen surrounding CFL use. CFLs contain small amounts of mercury, and several public forums and news agencies have been announcing that the breakage of a CFL…

49 CFR 173.24a - Additional general requirements for non-bulk packagings and packages.

Code of Federal Regulations, 2011 CFR

2011-10-01

... design. Except as provided in § 172.312 of this subchapter: (1) Inner packaging closures. A combination... packed, secured and cushioned to prevent their breakage or leakage and to control their shifting within... Group I packaging may be used for a Packing Group II material with a specific gravity not exceeding the...

49 CFR 173.24a - Additional general requirements for non-bulk packagings and packages.

Code of Federal Regulations, 2014 CFR

2014-10-01

... design. Except as provided in § 172.312 of this subchapter: (1) Inner packaging closures. A combination... packed, secured and cushioned to prevent their breakage or leakage and to control their shifting within... Group I packaging may be used for a Packing Group II material with a specific gravity not exceeding the...

Identification of genetic loci underlying the kernel fissure-resistance exhibited by 'cypress' and 'saber'

USDA-ARS?s Scientific Manuscript database

The economic value of broken rice is about half that of whole milled rice, so one goal of producers, millers, and rice breeders is to reduce broken grains that result from the dehusking and milling processes One of the primary causes of rice breakage is fissuring, or cracking, of the rice before it ...

Construction of Ag/AgCl Reference Electrode from Used Felt-Tipped Pen Barrel for Undergraduate Laboratory

ERIC Educational Resources Information Center

Inamdar, Shaukatali N.; Bhat, Mohsin A.; Haram, Santosh K.

2009-01-01

A reference electrode is one of the prerequisites of electrochemical investigations. Many electrodes are commercially available but are expensive and prone to accidental breakage by students. Here we report a simple, easy-to-fabricate, inexpensive, reliable, unbreakable, and reproducible Ag/AgCl reference electrode. The empty barrel of a…

49 CFR 179.220-18 - Bottom outlets.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-18 Bottom outlets. (a) The... equivalent, except that bottom outlet closure plugs may be attached by 1/4-inch chain. When the bottom outlet... valve body may be steam jacketed, in which case the breakage groove or its equivalent must be below the...

Fine mapping and introgressing qFIS1-2, a major QTL for kernel fissure resistance in rice (Oryza sativa L.)

USDA-ARS?s Scientific Manuscript database

Rice (Oryza sativa L.) kernel fissuring increases breakage during milling and decreases the value of processed rice. This study employed molecular gene tagging methods to fine-map a fissure resistance (FR) locus in ‘Cybonnet’, a semidwarf tropical japonica cultivar, as well as transfer this trait to...

Condom Discomfort and Associated Problems with Their Use among University Students

ERIC Educational Resources Information Center

Grosby, Richard; Yarber, William L.; Sanders, Stephanie A.; Graham, Cynthia A.

2005-01-01

In addition to consistent use, condoms must be used correctly. The purpose of this study was to identify prevalence and types of condom-associated discomfort among university students, the outcomes of this discomfort, and the role of discomfort in condom breakage. We conducted a cross-sectional study of 206 students attending a private university…

Computational fluid dynamics investigation of turbulence models for non-newtonian fluid flow in anaerobic digesters.

PubMed

Wu, Binxin

2010-12-01

In this paper, 12 turbulence models for single-phase non-newtonian fluid flow in a pipe are evaluated by comparing the frictional pressure drops obtained from computational fluid dynamics (CFD) with those from three friction factor correlations. The turbulence models studied are (1) three high-Reynolds-number k-ε models, (2) six low-Reynolds-number k-ε models, (3) two k-ω models, and (4) the Reynolds stress model. The simulation results indicate that the Chang-Hsieh-Chen version of the low-Reynolds-number k-ε model performs better than the other models in predicting the frictional pressure drops while the standard k-ω model has an acceptable accuracy and a low computing cost. In the model applications, CFD simulation of mixing in a full-scale anaerobic digester with pumped circulation is performed to propose an improvement in the effective mixing standards recommended by the U.S. EPA based on the effect of rheology on the flow fields. Characterization of the velocity gradient is conducted to quantify the growth or breakage of an assumed floc size. Placement of two discharge nozzles in the digester is analyzed to show that spacing two nozzles 180° apart with each one discharging at an angle of 45° off the wall is the most efficient. Moreover, the similarity rules of geometry and mixing energy are checked for scaling up the digester.

Kinetic theory for DNA melting with vibrational entropy

NASA Astrophysics Data System (ADS)

Sensale, Sebastian; Peng, Zhangli; Chang, Hsueh-Chia

2017-10-01

By treating DNA as a vibrating nonlinear lattice, an activated kinetic theory for DNA melting is developed to capture the breakage of the hydrogen bonds and subsequent softening of torsional and bending vibration modes. With a coarse-grained lattice model, we identify a key bending mode with GHz frequency that replaces the hydrogen vibration modes as the dominant out-of-phase phonon vibration at the transition state. By associating its bending modulus to a universal in-phase bending vibration modulus at equilibrium, we can hence estimate the entropic change in the out-of-phase vibration from near-equilibrium all-atom simulations. This and estimates of torsional and bending entropy changes lead to the first predictive and sequence-dependent theory with good quantitative agreement with experimental data for the activation energy of melting of short DNA molecules without intermediate hairpin structures.

A review of numerical techniques approaching microstructures of crystalline rocks

NASA Astrophysics Data System (ADS)

Zhang, Yahui; Wong, Louis Ngai Yuen

2018-06-01

The macro-mechanical behavior of crystalline rocks including strength, deformability and failure pattern are dominantly influenced by their grain-scale structures. Numerical technique is commonly used to assist understanding the complicated mechanisms from a microscopic perspective. Each numerical method has its respective strengths and limitations. This review paper elucidates how numerical techniques take geometrical aspects of the grain into consideration. Four categories of numerical methods are examined: particle-based methods, block-based methods, grain-based methods, and node-based methods. Focusing on the grain-scale characters, specific relevant issues including increasing complexity of micro-structure, deformation and breakage of model elements, fracturing and fragmentation process are described in more detail. Therefore, the intrinsic capabilities and limitations of different numerical approaches in terms of accounting for the micro-mechanics of crystalline rocks and their phenomenal mechanical behavior are explicitly presented.

Comparison of tensile strength among simple interrupted, cruciate, intradermal, and subdermal suture patterns for incision closure in ex vivo canine skin specimens.

PubMed

Zellner, Eric M; Hedlund, Cheryl S; Kraus, Karl H; Burton, Andrew F; Kieves, Nina R

2016-06-15

OBJECTIVE To compare suture placement time, tension at skin separation and suture line failure, and mode of failure among 4 suture patterns. DESIGN Randomized trial. SAMPLE 60 skin specimens from the pelvic limbs of 30 purpose-bred Beagles. PROCEDURES Skin specimens were harvested within 2 hours after euthanasia and tested within 6 hours after harvest. An 8-cm incision was made in each specimen and sutured with 1 of 4 randomly assigned suture patterns (simple interrupted, cruciate, intradermal, or subdermal). Suture placement time and percentage of skin apposition were evaluated. Specimens were mounted in a calibrated material testing machine and distracted until suture line failure. Tensile strength at skin-edge separation and suture-line failure and mode of failure were compared among the 4 patterns. RESULTS Mean suture placement time for the cruciate pattern was significantly less than that for other patterns. Percentage of skin apposition did not differ among the 4 patterns. Mean tensile strength at skin-edge separation and suture-line failure for the simple interrupted and cruciate patterns were significantly higher than those for the intradermal and subdermal patterns. Mean tensile strength at skin-edge separation and suture-line failure did not differ significantly between the intradermal and subdermal patterns or the simple interrupted and cruciate patterns. The primary mode of failure for the simple interrupted pattern was suture breakage, whereas that for the cruciate, intradermal, and subdermal patterns was tissue failure. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested external skin sutures may be preferred for closure of incisions under tension to reduce risk of dehiscence.

Two-year survival analysis of twisted wire fixed retainer versus spiral wire and fiber-reinforced composite retainers: a preliminary explorative single-blind randomized clinical trial.

PubMed

Sobouti, Farhad; Rakhshan, Vahid; Saravi, Mahdi Gholamrezaei; Zamanian, Ali; Shariati, Mahsa

2016-03-01

Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (α = 0.05). In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results.

Two-year survival analysis of twisted wire fixed retainer versus spiral wire and fiber-reinforced composite retainers: a preliminary explorative single-blind randomized clinical trial

PubMed Central

Sobouti, Farhad; Rakhshan, Vahid; Saravi, Mahdi Gholamrezaei; Zamanian, Ali

2016-01-01

Objective Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. Methods In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (α = 0.05). Results In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). Conclusions Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results. PMID:27019825

Force and torque modelling of drilling simulation for orthopaedic surgery.

PubMed

MacAvelia, Troy; Ghasempoor, Ahmad; Janabi-Sharifi, Farrokh

2014-01-01

The advent of haptic simulation systems for orthopaedic surgery procedures has provided surgeons with an excellent tool for training and preoperative planning purposes. This is especially true for procedures involving the drilling of bone, which require a great amount of adroitness and experience due to difficulties arising from vibration and drill bit breakage. One of the potential difficulties with the drilling of bone is the lack of consistent material evacuation from the drill's flutes as the material tends to clog. This clogging leads to significant increases in force and torque experienced by the surgeon. Clogging was observed for feed rates greater than 0.5 mm/s and spindle speeds less than 2500 rpm. The drilling simulation systems that have been created to date do not address the issue of drill flute clogging. This paper presents force and torque prediction models that account for this phenomenon. The two coefficients of friction required by these models were determined via a set of calibration experiments. The accuracy of both models was evaluated by an additional set of validation experiments resulting in average R² regression correlation values of 0.9546 and 0.9209 for the force and torque prediction models, respectively. The resulting models can be adopted by haptic simulation systems to provide a more realistic tactile output.

Modeling of microalgal shear-induced flocculation and sedimentation using a coupled CFD-population balance approach.

PubMed

Golzarijalal, Mohammad; Zokaee Ashtiani, Farzin; Dabir, Bahram

2018-01-01

In this study, shear-induced flocculation modeling of Chlorella sp. microalgae was conducted by combination of population balance modeling and CFD. The inhomogeneous Multiple Size Group (MUSIG) and the Euler-Euler two fluid models were coupled via Ansys-CFX-15 software package to achieve both fluid and particle dynamics during the flocculation. For the first time, a detailed model was proposed to calculate the collision frequency and breakage rate during the microalgae flocculation by means of the response surface methodology as a tool for optimization. The particle size distribution resulted from the model was in good agreement with that of the jar test experiment. Furthermore, the subsequent sedimentation step was also examined by removing the shear rate in both simulations and experiments. Consequently, variation in the shear rate and its effects on the flocculation behavior, sedimentation rate and recovery efficiency were evaluated. Results indicate that flocculation of Chlorella sp. microalgae under shear rates of 37, 182, and 387 s -1 is a promising method of pre-concentration which guarantees the cost efficiency of the subsequent harvesting process by recovering more than 90% of the biomass. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:160-174, 2018. © 2017 American Institute of Chemical Engineers.

Quantification of DNA cleavage specificity in Hi-C experiments.

PubMed

Meluzzi, Dario; Arya, Gaurav

2016-01-08

Hi-C experiments produce large numbers of DNA sequence read pairs that are typically analyzed to deduce genomewide interactions between arbitrary loci. A key step in these experiments is the cleavage of cross-linked chromatin with a restriction endonuclease. Although this cleavage should happen specifically at the enzyme's recognition sequence, an unknown proportion of cleavage events may involve other sequences, owing to the enzyme's star activity or to random DNA breakage. A quantitative estimation of these non-specific cleavages may enable simulating realistic Hi-C read pairs for validation of downstream analyses, monitoring the reproducibility of experimental conditions and investigating biophysical properties that correlate with DNA cleavage patterns. Here we describe a computational method for analyzing Hi-C read pairs to estimate the fractions of cleavages at different possible targets. The method relies on expressing an observed local target distribution downstream of aligned reads as a linear combination of known conditional local target distributions. We validated this method using Hi-C read pairs obtained by computer simulation. Application of the method to experimental Hi-C datasets from murine cells revealed interesting similarities and differences in patterns of cleavage across the various experiments considered. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Localization of alkali-labile sites in donkey (Equus asinus) and stallion (Equus caballus) spermatozoa.

PubMed

Cortés-Gutiérrez, Elva I; Dávila-Rodríguez, Martha I; López-Fernández, Carmen; Fernández, José Luis; Crespo, Francisco; Gosálvez, Jaime

2014-01-15

The presence of constitutive alkali-labile sites (ALS) has been investigated using a protocol of DNA breakage detection-fluorescence in situ hybridization and comet assay in spermatozoa of donkey (Equus asinus) and stallion (Equus caballus). These results were compared with those obtained using a similar experimental approach using somatic cells. The relative abundance of ALS was of the order of four times more in spermatozoa than in somatic cells. Alkali-labile sites showed a tendency to cluster localized at the equatorial-distal regions of the sperm. The amount of hybridized signal in the ALS in the sperm of donkey (Equus asinus) was 1.3 times greater than in stallion (Equus caballus), and the length of the comet tail obtained in donkey sperm was 1.6 times longer than that observed in stallion (P < 0.05); however, these differences were not appreciated in somatic cells. In conclusion, ALS localization in sperm is not a randomized event and a different pattern of ALS distribution occurs for each species. These results suggest that ALS represents a species-specific issue related to chromatin organization in sperm and somatic cells in mammalian species, and they might diverge even with very short phylogenetic distances. Copyright © 2014 Elsevier Inc. All rights reserved.

Mechanisms of inhibition of viral replication in plants

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

Not Available

1990-01-01

We have made a number of interesting observations of importance to the fields of virology and plant molecular biology. Topics include the genome of cucumber mosaic virus (CMV), recombination of the CMV genome, transgenic plants and viral movement genes, mapping resistance breakage sequences in the tomato mosaic virus (TMV) genome, and mapping pathogeneticity domains and viral RNA heterogeneity. 1 fig., 1 tab.

Cutting head for ultrasonic lithotripsy

NASA Technical Reports Server (NTRS)

Anguluo, E. D.; Goodfriend, R. (Inventor)

1985-01-01

A cutting head for attachment to the end of the wire probe of an ultrasonic kidney stone disintegration instrument is described. The cutting head has a plurality of circumferentially arranged teeth formed at one end thereof to provide a cup shaped receptacle for kidney stones encountered during the disintegration procedure. An integral reduced diameter collar diminishes stress points in the wire and reduce breakage thereof.

Cutting Head for Ultrasonic Lithotripsy

NASA Technical Reports Server (NTRS)

Angulo, Earl D. (Inventor); Goodfriend, Roger (Inventor)

1989-01-01

A cutting head for attachment to the end of the wire probe of an ultrasonic kidney stone disintegration instrument. The cutting head has a plurality of circumferentially arranged teeth formed at one end thereof to provide a cup-shaped receptacle for kidney stones encountered during the disintegration procedure. An integral reduced diameter collar diminishes stress points in the wire and reduces breakage thereof.

Handbook for predicting slash weight of trees in the Northeast.

Treesearch

Duane R. Freeman; Robert M. Loomis; Peter J. Roussopoulos

1982-01-01

Tables are provided for estimating tree crown weights based on species and diameters (d.b.h.) for 10 conifer and 9 hardwood species or species groups of the North Central and Northeastern United States. Procedures are given for predicting slash weights resulting from: cutting timber, trampling during logging activities, and defect and breakage left on the site after...

49 CFR 173.4 - Small quantities for highway and rail.

Code of Federal Regulations, 2012 CFR

2012-10-01

... solid materials; (iii) One (1) g (0.04 ounce) for authorized materials meeting the definition of a... drops made from a height of 1.8 m (5.9 feet) directly onto a solid unyielding surface without breakage... package: (A) One drop flat on bottom; (B) One drop flat on top; (C) One drop flat on the long side; (D...

Peculiar Traits of Coarse AP (Briefing Charts)

DTIC Science & Technology

2014-12-01

coarse AP Bircumshaw, Newman Active centers are sources of AP decomposition gases AP low temperature decomposition (LTD) Most unstable AP particles ...delay before coarse AP ejection *Coarse AP particle flame retardancy 19 Air Force Research Laboratory Distribution A: Approved for public release...distribution unlimited. PA clearance #. Combustion bomb trials 2 AP phase change may enable coarse particle breakage Fractured coarse AP ejection agrees

Establishment of a long-term fire salvage study in an interior ponderosa pine forest

Treesearch

Martin W. Ritchie; Eric E. Knapp

2014-01-01

An experiment designed to evaluate the treatment effects of salvaging merchantable fire-killed trees on surface fuels and regeneration was established after a wildfire in northeastern California. The study was then monitored for 10 years. Surface fuel accumulations were rapid, corresponding with a high rate of snag decay and subsequent breakage or windthrow. Pine snags...

Window flaw detection by backscatter lighting

NASA Technical Reports Server (NTRS)

Crockett, L. K.; Minton, F. R.

1978-01-01

Portable fiber-optic probe detects tiny flaws in transparent materials. Probe transmits light through surface to illuminate interior of material by backscattering off its edges. Light-sensitive contact paper records scratch pattern. Technique can be used for rapid visual checks. Flexible fiber optics are safely used in explosive or flammable areas; they present no hazard of breakage or contamination in controlled environments.

A study of wood baseball bat breakage

Treesearch

Patrick Drane; James Sherwood; Renzo Colosimo; David Kretschmann

2012-01-01

Over the span of three months in 2008, 2232 baseball bats broke while being used during Major League Baseball (MLB) games; of which 756 were classified as Multi Piece Failures (MPFs). This rate of failure motivated Major League Baseball to explore options for potential changes in the bat regulations to reduce the rate. After a study of the information that could be...

Resveratrol-3-O-glucuronide and resveratrol-4’-O-glucuronide reduce DNA strand breakage but not apoptosis in Jurkat T cells treated with camptothecin

USDA-ARS?s Scientific Manuscript database

Resveratrol has been reported to inhibit or induce DNA damage depending upon the type of cell and experimental conditions. Dietary resveratrol is present in the body mostly as metabolites and little is known about the activities of these metabolic products. We evaluated physiologically obtainable ...

Ruptured-yolk peritonitis and organochlorine residues in a royal tern

USGS Publications Warehouse

Blus, L.J.; Locke, L.N.; Stafford, C.J.

1977-01-01

Ruptured-yolk peritonitis was responsible for the death of a royal tern. Lodgment of eggs in the oviduct was probably due to reverse peristalsis brought about by breakage of the thin-shelled eggs and secondary bacterial infection. The thin shells were apparently not related to the low levels of DDE and other organochlorine pollutants found in tissues and egg contents.

Integration of Host Strain Bioengineering and Bioprocess Development Using Ultra-Scale Down Studies to Select the Optimum Combination: An Antibody Fragment Primary Recovery Case Study

PubMed Central

Aucamp, Jean P; Davies, Richard; Hallet, Damien; Weiss, Amanda; Titchener-Hooker, Nigel J

2014-01-01

An ultra scale-down primary recovery sequence was established for a platform E. coli Fab production process. It was used to evaluate the process robustness of various bioengineered strains. Centrifugal discharge in the initial dewatering stage was determined to be the major cause of cell breakage. The ability of cells to resist breakage was dependant on a combination of factors including host strain, vector, and fermentation strategy. Periplasmic extraction studies were conducted in shake flasks and it was demonstrated that key performance parameters such as Fab titre and nucleic acid concentrations were mimicked. The shake flask system also captured particle aggregation effects seen in a large scale stirred vessel, reproducing the fine particle size distribution that impacts the final centrifugal clarification stage. The use of scale-down primary recovery process sequences can be used to screen a larger number of engineered strains. This can lead to closer integration with and better feedback between strain development, fermentation development, and primary recovery studies. Biotechnol. Bioeng. 2014;111: 1971–1981. © 2014 Wiley Periodicals, Inc. PMID:24838387

Detecting the activation of a self-healing mechanism in concrete by acoustic emission and digital image correlation.

PubMed

Tsangouri, E; Aggelis, D G; Van Tittelboom, K; De Belie, N; Van Hemelrijck, D

2013-01-01

Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process.

Protective effect of conditioning agents on Afro-ethnic hair chemically treated with thioglycolate-based straightening emulsion.

PubMed

Dias, Tania Cristina de Sá; Baby, André Rolim; Kaneko, Telma Mary; Velasco, Maria Valéria Robles

2008-06-01

Straightening is a chemical process by which excessively curly hair is straightened in an irreversible way. Generally, products are formulated as emulsions with high pH value (9.0-12.0), which, after applied on hair, cause considerable damage, making it dry and fragile. This research work evaluated the protective effect of lauryl PEG/PPG-18/18 methicone, cyclopentasiloxane (and) PEG-12 dimethicone cross-polymer, jojoba oil, and aqua (and) cystine bis-PG propyl silanetriol, as conditioning agents, on Afro-ethnic hair locks treated with thioglycolate-based straightening emulsions by protein loss, combability, and traction to rupture. Standard Afro-ethnic hair locks were prepared following a protocol for straightening emulsion application. Considering the assays performed, the addition of conditioning agents to the straightening emulsion with ammonium thioglycolate benefited the hair fiber, thus diminishing protein loss, protecting the hair thread, and improving resistance to breakage. Jojoba oil and lauryl PEG/PPG-18/18 methicone were the conditioning agents that presented the best results. Straightening emulsions with ammonium thioglycolate containing aqua (and) cystine bis-PG propyl silanetriol and cyclopentasiloxane (and) PEG-12 dimethicone cross-polymer were the ones that provided higher breakage resistance of the thread.

VehiHealth: An Emergency Routing Protocol for Vehicular Ad Hoc Network to Support Healthcare System.

PubMed

Bhoi, S K; Khilar, P M

2016-03-01

Survival of a patient depends on effective data communication in healthcare system. In this paper, an emergency routing protocol for Vehicular Ad hoc Network (VANET) is proposed to quickly forward the current patient status information from the ambulance to the hospital to provide pre-medical treatment. As the ambulance takes time to reach the hospital, ambulance doctor can provide sudden treatment to the patient in emergency by sending patient status information to the hospital through the vehicles using vehicular communication. Secondly, the experienced doctors respond to the information by quickly sending a treatment information to the ambulance. In this protocol, data is forwarded through that path which has less link breakage problem between the vehicles. This is done by calculating an intersection value I v a l u e for the neighboring intersections by using the current traffic information. Then the data is forwarded through that intersection which has minimum I v a l u e . Simulation results show VehiHealth performs better than P-GEDIR, GyTAR, A-STAR and GSR routing protocols in terms of average end-to-end delay, number of link breakage, path length, and average response time.

Association between genomic instability and evolutionary chromosomal rearrangements in Neotropical Primates.

PubMed

Puntieri, Fiona; Andrioli, Nancy B; Nieves, Mariela

2018-06-14

During the last decades the mammalian genome has been proposed to have regions prone to breakage and reorganization concentrated in certain chromosomal bands that seem to correspond to evolutionary breakpoints. These bands are likely to be involved in chromosome fragility or instability. In Primates, some biomarkers of genetic damage may be associated with various degrees of genomic instability. Here, we investigated the usefulness of Sister Chromatid Exchange (SCE) as a biomarker of potential sites of frequent chromosome breakage and rearrangement in Alouatta caraya, Ateles chamek, Ateles paniscus and Cebus cay. These Neotropical species have particular genomic and chromosomal features allowing the analysis of genomic instability for comparative purposes. We determined the frequency of spontaneous induction of SCEs and assessed the relationship between these and structural rearrangements implicated in the evolution of the primates of interest. Overall, A. caraya and C. cay presented a low proportion of statistically significant unstable bands, suggesting fairly stable genomes and the existence of some kind of protection against endogenous damage. In contrast, Ateles showed a highly significant proportion of unstable bands; these were mainly found in the rearranged regions, which is consistent with the numerous genomic reorganizations that might have occurred during the evolution of this genus.

An investigation of gear mesh failure prediction techniques. M.S. Thesis - Cleveland State Univ.

NASA Technical Reports Server (NTRS)

Zakrajsek, James J.

1989-01-01

A study was performed in which several gear failure prediction methods were investigated and applied to experimental data from a gear fatigue test apparatus. The primary objective was to provide a baseline understanding of the prediction methods and to evaluate their diagnostic capabilities. The methods investigated use the signal average in both the time and frequency domain to detect gear failure. Data from eleven gear fatigue tests were recorded at periodic time intervals as the gears were run from initiation to failure. Four major failure modes, consisting of heavy wear, tooth breakage, single pits, and distributed pitting were observed among the failed gears. Results show that the prediction methods were able to detect only those gear failures which involved heavy wear or distributed pitting. None of the methods could predict fatigue cracks, which resulted in tooth breakage, or single pits. It is suspected that the fatigue cracks were not detected because of limitations in data acquisition rather than in methodology. Additionally, the frequency response between the gear shaft and the transducer was found to significantly affect the vibration signal. The specific frequencies affected were filtered out of the signal average prior to application of the methods.

Impact damage to dinocysts from the Late Eocene Chesapeake Bay event

USGS Publications Warehouse

Edwards, L.E.; Powars, D.S.

2003-01-01

The Chesapeake Bay impact structure, formed by a comet or meteorite that struck the Virginia continental shelf about 35.5 million years ago, is the focus of an extensive coring project by the U.S. Geological Survey and its cooperators. Organic-walled dinocysts recovered from impact-generated deposits in a deep core inside the 85-90 km-wide crater include welded organic clumps and fused, partially melted and bubbled dinocysts unlike any previously observed. Other observed damage to dinocysts consists of breakage, pitting, and folding in various combinations. The entire marine Cretaceous, Paleocene, and Eocene section that was once present at the site has been excavated and redeposited under extreme conditions that include shock, heat, collapse, tsunamis, and airfall. The preserved dinocysts reflect these conditions and, as products of a known impact, may serve as guides for recognizing impact-related deposits elsewhere. Features that are not unique to impacts, such as breakage and folding, may offer new insights into crater-history studies in general, and to the history of the Chesapeake Bay impact structure in particular. Impact-damaged dinocysts also are found sporadically in post-impact deposits and add to the story of continuing erosion and faulting of crater material.

Failure modes of microstructured fibers with sacrificial bonds made by instability-assisted 3D printing

NASA Astrophysics Data System (ADS)

Zou, Shibo; Therriault, Daniel; Gosselin, Frederick

A simple modification by increasing the deposition height on a commercially available 3D printer makes it a mechanical sewing machine due to the fluid mechanical instability. A variety of stitches-like patterns can be produced, similar to those by the Newtonian fluid mechanical sewing machine\\x9D, but with more interesting characteristics in the additional third dimension, which creates weakly fused bonds in some patterns. With these bonds, the fabricated fibers exhibit improved toughness in uniaxial tensile test. The toughening mechanism is found to be similar to the one in spider silk - the breaking of sacrificial bonds and the releasing of hidden length contribute significant dissipated energy to the system. However, the mechanical performance of these microstructured fibers is restricted by early fiber breakage as the number of sacrificial bonds increases. Here, we seek to understand the failure mechanisms of the microstructured fibers through tensile tests and finite element simulations. Static and dynamic failure are both found to cause early fiber breakage. These findings are helpful for the design optimization of microstructured fibers with high toughness and ductility, which can find potential use in impact protection and safety-critical applications.

Traumas of the middle skull base with TMJ involvement. Case report.

PubMed

Bottini, D J; Gnoni, G; De Angelis, B; Savo, P; Trimarco, A; Cervelli, G; Cervelli, V

2006-03-01

The authors report their experience with temporomandibular joint (TMJ) traumas involving breakage of the roof of the glenoid cavity, an infrequent event that occurs in those cases in which, as a result of the condylar neck not fracturing, the traumatic energy is transmitted to the middle skull base. As the literature contains no valid series for establishing standardized protocols for the treatment of these fractures, we propose our own orthopedic-functional approach. The patient observed by us had suffered a cranio-facial trauma and presented the classical symptoms and signs of TMJ traumas and complete bilateral Bell paralysis. He was subjected to a CAT scan and then to 2-stage treatment consisting of functional rest with liquid diet followed by physiotherapy. An almost total recovery in TMJ function was observed after 1 month. At 1-year follow-up the facial paralysis had resolved completely. On the basis of our experience, breakages of the glenoid cavity can be compared, in terms of treatment procedure, to intracapsular fractures of the TMJ with surgery confined to cases of ankylosis sequelae. To avoid the onset of ankylosis careful control of clinical, functional and radiological follow-up is required.

Effects of -1.5°C Super-chilling on quality of Atlantic salmon (Salmo salar) pre-rigor Fillets: Cathepsin activity, muscle histology, texture and liquid leakage.

PubMed

Bahuaud, D; Mørkøre, T; Langsrud, Ø; Sinnes, K; Veiseth, E; Ofstad, R; Thomassen, M S

2008-11-15

The aim of this study was to evaluate the impact of super-chilling on the quality of Atlantic salmon (Salmo salar) pre-rigor fillets. The fillets were kept for 45min in a super-chilling tunnel at -25°C with an air speed in the tunnel at 2.5m/s, to reach a fillet core temperature of -1.5°C, prior to ice storage in a cold room for 4 weeks. Super-chilling seemed to form intra- and extracellular ice crystals in the upper layer of the fillets and prevent myofibre contraction. Lysosome breakages followed by release of cathepsin B and L during storage and myofibre-myofibre detachments were accelerated in the super-chilled fillets. Super-chilling resulted in higher liquid leakage and increased myofibre breakages in the fillets, while texture values of fillets measured instrumentally were not affected by super-chilling one week after treatment. Optimisation of the super-chilling technique is needed to avoid the formation of ice crystals, which may cause irreversible destruction of the myofibres, in order to obtain high quality products. Copyright © 2008 Elsevier Ltd. All rights reserved.

A novel technique to prevent guide wire related complications while inserting the 4.0 mm cannulated screws.

PubMed

Qi, Bao-Chang; Ju, Wei-Na; Wang, Tie-Jun; Yu, Tie-Cheng; Zhao, Yi; Sun, Da-Hui

2015-01-01

Cannulated screws (4.0 mm) provide inter-fragmentary compression and stability to fractures. A guide wire is used to define the screw trajectory and hold the fracture fragment while the screw is being inserted. The cannulated shaft typically accommodates a 1.25 mm guide pin. Since the guide pin is very slender and undergoes elastic deformation during insertion, there is a high probability of pin breakage. The authors have devised a new way to place the 4.0 mm cannulated screws in a manner that prevents the intraoperative complication of guide wire breakage. For this technique, predrilling was achieved using a 2.0 mm K-wire which was subsequently replaced with a 1.25 mm guide pin under the protection of sleeve. 4.0 mm cannulated screws were then inserted into a defined trajectory over the guide pin. Using the technique, over 20 patients were managed in our department over a period of two years without any complications. We have observed that patients treated with this method experience short operation time, combined with good clinical outcome and we recommend its use in cases where cannulated screw use is warranted.

Casein Kinase 1 and Phosphorylation of Cohesin Subunit Rec11 (SA3) Promote Meiotic Recombination through Linear Element Formation.

PubMed

Phadnis, Naina; Cipak, Lubos; Polakova, Silvia; Hyppa, Randy W; Cipakova, Ingrid; Anrather, Dorothea; Karvaiova, Lucia; Mechtler, Karl; Smith, Gerald R; Gregan, Juraj

2015-05-01

Proper meiotic chromosome segregation, essential for sexual reproduction, requires timely formation and removal of sister chromatid cohesion and crossing-over between homologs. Early in meiosis cohesins hold sisters together and also promote formation of DNA double-strand breaks, obligate precursors to crossovers. Later, cohesin cleavage allows chromosome segregation. We show that in fission yeast redundant casein kinase 1 homologs, Hhp1 and Hhp2, previously shown to regulate segregation via phosphorylation of the Rec8 cohesin subunit, are also required for high-level meiotic DNA breakage and recombination. Unexpectedly, these kinases also mediate phosphorylation of a different meiosis-specific cohesin subunit Rec11. This phosphorylation in turn leads to loading of linear element proteins Rec10 and Rec27, related to synaptonemal complex proteins of other species, and thereby promotes DNA breakage and recombination. Our results provide novel insights into the regulation of chromosomal features required for crossing-over and successful reproduction. The mammalian functional homolog of Rec11 (STAG3) is also phosphorylated during meiosis and appears to be required for fertility, indicating wide conservation of the meiotic events reported here.

Detecting the Activation of a Self-Healing Mechanism in Concrete by Acoustic Emission and Digital Image Correlation

PubMed Central

Tsangouri, E.; Aggelis, D. G.; Van Tittelboom, K.; De Belie, N.; Van Hemelrijck, D.

2013-01-01

Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process. PMID:24381518

The breakage behaviour of Aspirin under quasi-static indentation and single particle impact loading: effect of crystallographic anisotropy.

PubMed

Olusanmi, D; Roberts, K J; Ghadiri, M; Ding, Y

2011-06-15

The influence of crystallographic structural anisotropy on the breakage behaviour of Aspirin under impact loading is highlighted. Under both quasi-static testing conditions, using nano-indentation, and dynamic impact tests, Aspirin demonstrates clear anisotropy in its slip and fracture behaviour. During nano-indentation on the (100) and (001) faces, cracks were propagated along the [010] direction. While the hardness was found to be comparatively similar for both these faces, it was observed that slip due to plastic deformation occurred more readily on the (100) than the (001) crystal planes suggesting the former as the preferred slip plane. Furthermore, the fracture toughness on the (001) planes was found to be distinctly lower than that of the (100) planes, indicating the former as the preferred cleavage plane. Observations of the crystal morphology of damaged particles after dynamic impact testing showed that both the chipping and fragmentation of Aspirin mostly occurred via cleavage in a manner consistent with the observed fracture behaviour following nano-indentation. This work highlights the importance of cleavage as a dominant factor underpinning the fracture mechanism of Aspirin under both quasi-static and impact loading conditions. Copyright © 2011 Elsevier B.V. All rights reserved.

A 130,000-year-old archaeological site in southern California, USA.

PubMed

Holen, Steven R; Deméré, Thomas A; Fisher, Daniel C; Fullagar, Richard; Paces, James B; Jefferson, George T; Beeton, Jared M; Cerutti, Richard A; Rountrey, Adam N; Vescera, Lawrence; Holen, Kathleen A

2017-04-26

The earliest dispersal of humans into North America is a contentious subject, and proposed early sites are required to meet the following criteria for acceptance: (1) archaeological evidence is found in a clearly defined and undisturbed geologic context; (2) age is determined by reliable radiometric dating; (3) multiple lines of evidence from interdisciplinary studies provide consistent results; and (4) unquestionable artefacts are found in primary context. Here we describe the Cerutti Mastodon (CM) site, an archaeological site from the early late Pleistocene epoch, where in situ hammerstones and stone anvils occur in spatio-temporal association with fragmentary remains of a single mastodon (Mammut americanum). The CM site contains spiral-fractured bone and molar fragments, indicating that breakage occured while fresh. Several of these fragments also preserve evidence of percussion. The occurrence and distribution of bone, molar and stone refits suggest that breakage occurred at the site of burial. Five large cobbles (hammerstones and anvils) in the CM bone bed display use-wear and impact marks, and are hydraulically anomalous relative to the low-energy context of the enclosing sandy silt stratum. 230 Th/U radiometric analysis of multiple bone specimens using diffusion-adsorption-decay dating models indicates a burial date of 130.7 ± 9.4 thousand years ago. These findings confirm the presence of an unidentified species of Homo at the CM site during the last interglacial period (MIS 5e; early late Pleistocene), indicating that humans with manual dexterity and the experiential knowledge to use hammerstones and anvils processed mastodon limb bones for marrow extraction and/or raw material for tool production. Systematic proboscidean bone reduction, evident at the CM site, fits within a broader pattern of Palaeolithic bone percussion technology in Africa, Eurasia and North America. The CM site is, to our knowledge, the oldest in situ, well-documented archaeological site in North America and, as such, substantially revises the timing of arrival of Homo into the Americas.

Comparison of patient acceptance of the Forsus Fatigue Resistant Device with and without mini-implant anchorage: a randomized controlled trial.

PubMed

Elkordy, Sherif A; Fayed, Mona M Salah; Abouelezz, Amr M; Attia, Khaled H

2015-11-01

The objective of this 2-arm parallel randomized controlled trial was to evaluate patient acceptance of the mini-implant anchored Forsus Fatigue Resistant Device (FFRD) (3M Unitek, Monrovia, Calif). The study included 32 skeletal Class II girls. The eligibility criteria included a deficient mandible, a horizontal or neutral growth pattern, an increased overjet, and a full set of erupted permanent teeth. After the leveling and alignment stage, FFRDs and mini-implants were inserted; they were removed after the teeth reached an edge-to-edge incisor relationship. The patients were afterward asked to fill out assessment questionnaires regarding their experience with the FFRD. The primary outcome of this study was to assess patient acceptance of the appliance and satisfaction with the results. The secondary outcomes were interference with functional activities, noticeability by others, pain, swelling, gum problems caused by the appliance, and appliance breakage. Computer random sequence generation was done using block sizes of 6 and 4. Allocation concealment was achieved with sequentially numbered opaque sealed envelopes. Blinding of the clinicians and the patients to the intervention was impossible, but it was done for the outcome assessment and the statistician. The 32 patients were randomly allocated in a 1:1 ratio into 2 groups: 16 patients (mean age, 13.25 ± 1.12 years) received the FFRD alone (FFRD group), and 16 patients (mean age, 13.07 ± 1.41 years) had mini-implants in conjunction with FFRDs (FMI group). No statistically significant differences were reported between the 2 groups regarding ease of appliance insertion, noticeability by others, pain, swelling, effects on eating and speech, and gum bleeding; 100% and 87.5% were satisfied with the results in the FFRD and FMI groups, respectively, with a ridit value of 0.57 (95% confidence interval, 0.43-0.71; P = 0.36). No serious harm was observed other than swelling of the cheeks, which occurred in 4 patients. There were no significant differences between the patients' acceptance of the FFRD and the mini-implant anchored FFRD. They were highly satisfied with the results. Neither group reported significant functional limitations. This trial was not registered. The protocol was not published before trial commencement. The study was self-funded by the authors. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Influence of pinches on magnetic reconnection in turbulent space plasmas

NASA Astrophysics Data System (ADS)

Olshevsky, Vyacheslav; Lapenta, Giovanni; Markidis, Stefano; Divin, Andrey

A generally accepted scenario of magnetic reconnection in space plasmas is the breakage of magnetic field lines in X-points. In laboratory, reconnection is widely studied in pinches, current channels embedded into twisted magnetic fields. No model of magnetic reconnection in space plasmas considers both null-points and pinches as peers. We have performed a particle-in-cell simulation of magnetic reconnection in a three-dimensional configuration where null-points are present nitially, and Z-pinches are formed during the simulation. The X-points are relatively stable, and no substantial energy dissipation is associated with them. On contrary, turbulent magnetic reconnection in the pinches causes the magnetic energy to decay at a rate of approximately 1.5 percent per ion gyro period. Current channels and twisted magnetic fields are ubiquitous in turbulent space plasmas, so pinches can be responsible for the observed high magnetic reconnection rates.

Compaction dynamics of crunchy granular material

NASA Astrophysics Data System (ADS)

Guillard, François; Golshan, Pouya; Shen, Luming; Valdès, Julio R.; Einav, Itai

2017-06-01

Compaction of brittle porous material leads to a wide variety of densification patterns. Static compaction bands occurs naturally in rocks or bones, and have important consequences in industry for the manufacturing of powder tablets or metallic foams for example. Recently, oscillatory compaction bands have been observed in brittle porous media like snow or cereals. We will discuss the great variety of densification patterns arising during the compaction of puffed rice, including erratic compaction at low velocity, one or several travelling compaction bands at medium velocity and homogeneous compaction at larger velocity. The conditions of existence of each pattern are studied thanks to a numerical spring lattice model undergoing breakage and is mapped to the phase diagram of the patterns based on dimensionless characteristic quantities. This also allows to rationalise the evolution of the compaction behaviour during a single test. Finally, the localisation of compaction bands is linked to the strain rate sensitivity of the material.

Controlled Dissolution of Phenytoin by Hybridizing with Silica Nanoparticles

NASA Astrophysics Data System (ADS)

Goto, H.; Isobe, T.; Senna, M.

1999-06-01

A sparingly soluble model drug, phenytoin (5,5-diphenyl-hydantoin, denoted as PT), was incorporated during or after hydrolysis and polycondensation of tetra orthoethyl silicate (TEOS) to obtain silica-drug hybrids. We also compare the hybrids obtained by sol-gel process with those obtained by simple adsorption on nonporous silica particles. The initial rate of dissolution in water increases by a factor of 40 with respect to the intact PT by aging silica before drug addition. The IR results show that νC=O in the position 2 of PT and νN-H shift toward the higher wavenumber, showing that intermolecular hydrogen bonds between C=O and N-H are loosened or broken to form new hydrogen bonds between C=O in PT and Si-OH in silica. The dissolution rate of PT is determined by the degree of the breakage of hydrogen bonds between PT molecules and the intensity of the interaction between silica and PT.

Algorithmic structural segmentation of defective particle systems: a lithium-ion battery study.

PubMed

Westhoff, D; Finegan, D P; Shearing, P R; Schmidt, V

2018-04-01

We describe a segmentation algorithm that is able to identify defects (cracks, holes and breakages) in particle systems. This information is used to segment image data into individual particles, where each particle and its defects are identified accordingly. We apply the method to particle systems that appear in Li-ion battery electrodes. First, the algorithm is validated using simulated data from a stochastic 3D microstructure model, where we have full information about defects. This allows us to quantify the accuracy of the segmentation result. Then we show that the algorithm can successfully be applied to tomographic image data from real battery anodes and cathodes, which are composed of particle systems with very different morpohological properties. Finally, we show how the results of the segmentation algorithm can be used for structural analysis. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Laser debonding of ceramic orthodontic brackets: a theoretical approach

NASA Astrophysics Data System (ADS)

Kearney, Kristine L.; Marangoni, Roy D.; Rickabaugh, Jeff L.

1992-06-01

Ceramic brackets are an esthetic substitute for conventional stainless steel brackets in orthodontic patients. However, ceramic brackets are more brittle and have higher bond strengths which can lead to bracket breakage and enamel damage during debonding. It has been demonstrated that various lasers can facilitate ceramic bracket removal. One mechanism with the laser is through the softening of the bracket adhesive. The high energy density from the laser on the bracket and adhesive can have a resultant deleterious thermal effect on the pulp of the tooth which may lead to pulpal death. A theoretical computer model of bracket, adhesive, enamel and dentin has been generated for predicting heat flow through this system. Heat fluxes at varying intensities and modes have been input into the program and the resultant temperatures at various points or nodes were determined. Further pursuit should lead to optimum parameters for laser debonding which would have minimal effects on the pulp.

49 CFR 173.4 - Small quantities for highway and rail.

Code of Federal Regulations, 2011 CFR

2011-10-01

... drops made from a height of 1.8 m (5.9 feet) directly onto a solid unyielding surface without breakage... package: (A) One drop flat on bottom; (B) One drop flat on top; (C) One drop flat on the long side; (D) One drop flat on the short side; and (E) One drop on a corner at the junction of three intersecting...

Magnetized Target Fusion - Field Reversed Configuration Formation and Injection (MTF-FRC)

DTIC Science & Technology

2009-11-06

from accidental breakage and personnel from injury in that event. The pumps for the vacuum system included a Varian dry scroll pump that was...a dry scroll (oil-free) mechanical pump could be used, as mTorr pressures would be sufficient for the vacuum switch voltage hold-off and operation...56 FIGURE 46. ROUGHING PUMP AND VACUUM -GAUGE CONTROLLERS BENEATH THETA COIL CABLE HEADER

Damage from wind and other causes in mixed white fir-red fir stands adjacent to clearcuttings

Treesearch

Donald T. Gordon

1973-01-01

Damage to timber surrounding clearcuttings and in one light selection cutting in mixed white fir-red fir stands was monitored for 6 years in northeastern California. In some years, bark beetles apparently killed more trees than did wind damage, but in two of the study years, severe wind storms caused much damage. One storm produced mainly break-age, apparently...

Aircraft Crash Survival Design Guide. Volume 5. Aircraft Postcrash Survival

DTIC Science & Technology

1980-01-01

The use of flexible hose armored with a steel- braided harness is strongly suggested in areas of anticipated dragging or structural impingement. In... Hose end coupling Metal tank fitting Breakaway valve Frangible section i ITEM LOWEST FAILURE LOAD (LB)* FAILURE MODE Flex hose 3000 Tensile breakage...61 21 Typical breakaway load calculation for in-line breakaway valve. . . . . . . . . 62 22 Standard hose fitting dimensions

Geomorphological impacts of a tornado disturbance in a subtropical forest

Treesearch

Jonathan Phillips; Daniel A. Marion; Chad Yocum; Stephanie H. Mehlhope; Jeff W. Olson

2015-01-01

We studied tree uprooting associated with an EF2 tornado that touched down in portions of the Ouachita Mountains in western Arkansas in 2009. In the severe blowdown areas all trees in the mixed shortleaf pine–hardwood forest were uprooted or broken, with no relationship between tree species or size and whether uprooting or breakage occurred. There was also no...

Susceptibility of central hardwood trees to stem breakage due to ice glazing

Treesearch

KaDonna C. Randolph

2014-01-01

During January 26-28, 2009, a winter storm dropped a mix of rain, ice, and snow from Texas across the Ohio River Valley and into New England. The storm caused multiple fatalities and millions of dollars of property damage and was called "the biggest natural disaster in modern Kentucky history" (Brammer and Funk 2009: 13). The storm disturbed an estimated 2.4...

Embedding Optical Fibers In Cast Metal Parts

NASA Technical Reports Server (NTRS)

Gibler, William N.; Atkins, Robert A.; Lee, Chung E.; Taylor, Henry F.

1995-01-01

Use of metal strain reliefs eliminates breakage of fibers during casting process. Technique for embedding fused silica optical fibers in cast metal parts devised. Optical fiber embedded in flange, fitting, or wall of vacuum or pressure chamber, to provide hermetically sealed feedthrough for optical transmission of measurement or control signals. Another example, optical-fiber temperature sensor embedded in metal structural component to measure strain or temperature inside component.

Outcome of hematopoietic cell transplantation for DNA double-strand break repair disorders.

PubMed

Slack, James; Albert, Michael H; Balashov, Dmitry; Belohradsky, Bernd H; Bertaina, Alice; Bleesing, Jack; Booth, Claire; Buechner, Jochen; Buckley, Rebecca H; Ouachée-Chardin, Marie; Deripapa, Elena; Drabko, Katarzyna; Eapen, Mary; Feuchtinger, Tobias; Finocchi, Andrea; Gaspar, H Bobby; Ghosh, Sujal; Gillio, Alfred; Gonzalez-Granado, Luis I; Grunebaum, Eyal; Güngör, Tayfun; Heilmann, Carsten; Helminen, Merja; Higuchi, Kohei; Imai, Kohsuke; Kalwak, Krzysztof; Kanazawa, Nubuo; Karasu, Gülsün; Kucuk, Zeynep Y; Laberko, Alexandra; Lange, Andrzej; Mahlaoui, Nizar; Meisel, Roland; Moshous, D; Muramatsu, Hideki; Parikh, Suhag; Pasic, Srdjan; Schmid, Irene; Schuetz, Catharina; Schulz, Ansgar; Schultz, Kirk R; Shaw, Peter J; Slatter, Mary A; Sykora, Karl-Walter; Tamura, Shinobu; Taskinen, Mervi; Wawer, Angela; Wolska-Kuśnierz, Beata; Cowan, Morton J; Fischer, Alain; Gennery, Andrew R

2018-01-01

Rare DNA breakage repair disorders predispose to infection and lymphoreticular malignancies. Hematopoietic cell transplantation (HCT) is curative, but coadministered chemotherapy or radiotherapy is damaging because of systemic radiosensitivity. We collected HCT outcome data for Nijmegen breakage syndrome, DNA ligase IV deficiency, Cernunnos-XRCC4-like factor (Cernunnos-XLF) deficiency, and ataxia-telangiectasia (AT). Data from 38 centers worldwide, including indication, donor, conditioning regimen, graft-versus-host disease, and outcome, were analyzed. Conditioning was classified as myeloablative conditioning (MAC) if it contained radiotherapy or alkylators and reduced-intensity conditioning (RIC) if no alkylators and/or 150 mg/m 2 fludarabine or less and 40 mg/kg cyclophosphamide or less were used. Fifty-five new, 14 updated, and 18 previously published patients were analyzed. Median age at HCT was 48 months (range, 1.5-552 months). Twenty-nine patients underwent transplantation for infection, 21 had malignancy, 13 had bone marrow failure, 13 received pre-emptive transplantation, 5 had multiple indications, and 6 had no information. Twenty-two received MAC, 59 received RIC, and 4 were infused; information was unavailable for 2 patients. Seventy-three of 77 patients with DNA ligase IV deficiency, Cernunnos-XLF deficiency, or Nijmegen breakage syndrome received conditioning. Survival was 53 (69%) of 77 and was worse for those receiving MAC than for those receiving RIC (P = .006). Most deaths occurred early after transplantation, suggesting poor tolerance of conditioning. Survival in patients with AT was 25%. Forty-one (49%) of 83 patients experienced acute GvHD, which was less frequent in those receiving RIC compared with those receiving MAC (26/56 [46%] vs 12/21 [57%], P = .45). Median follow-up was 35 months (range, 2-168 months). No secondary malignancies were reported during 15 years of follow-up. Growth and developmental delay remained after HCT; immune-mediated complications resolved. RIC HCT resolves DNA repair disorder-associated immunodeficiency. Long-term follow-up is required for secondary malignancy surveillance. Routine HCT for AT is not recommended. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Factors affecting the outcomes of modified tension band wiring techniques in transverse patellar fractures.

PubMed

Hsu, Kai-Lan; Chang, Wei-Lun; Yang, Chyun-Yu; Yeh, Ming-Long; Chang, Chih-Wei

2017-12-01

Modified tension band wiring has been widely used to treat transverse patellar fractures. However, few studies have evaluated the clinical outcomes using different methods of Kirschner wire bending, location of the tension band, and depths of Kirschner wires. Thus, we tried to clarify these factors according to our clinical outcomes. This retrospective cohort study recruited consecutive patients underwent surgical fixation for patellar fractures using modified tension band technique between January 2010 and December 2015. Different factors in this procedure, including the bending manner of the Kirschner wires, their depth, and location of the tension band with respect to the superior and inferior border of the patella were recorded and analysed. The primary outcome was early loss of fixation. The secondary outcomes were minor loss of reduction, implant breakage, deep infection, and the need for implant removal. This study included 170 patients with patellar fractures. Regarding the bending method, similar results were obtained with bilaterally or proximally bent Kirschner wires. Regarding length, the tension band was placed closely (within 25% of the patella length) in 124 patients and distantly in 46 patients. The rates of loss of reduction and implant breakage were significantly higher in the distantly placed tension bands. Regarding depth, 37 patellar fractures were fixed with the Kirschner wires at the superficial one third of the patellae while the K- wires at the middle layer of patella were used in the remaining 133 patellar fractures. A significantly higher rate of minor loss of reduction was obtained using the superficial Kirschner wires. The modified tension band technique for transverse patella fractures provides favourable clinical outcomes, with low failure (5%) and infection (2%) rates. Implant irritation is the major complication, and almost half of cases require implant removal. The location of the tension band with respect to the superior and inferior border of the patella plays an important role in clinical outcomes. Placing the wire close to the patella may prevent major loss of reduction and implant breakage. Superficially placed Kirschner wires also affect clinical outcomes by increasing the rate of minor loss of reduction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Seed release in serotinous lodgepole pine forests after mountain pine beetle outbreak.

PubMed

Teste, François P; Lieffers, Victor J; Landhausser, Simon M

2011-01-01

There are concerns that large-scale stand mortality due to mountain pine beetle (MPB) could greatly reduce natural regeneration of serotinous Rocky Mountain (RM) lodgepole pine (Pinus contorta var. latifolia) because the closed cones are held in place without the fire cue for cone opening. We selected 20 stands (five stands each of live [control], 3 years since MPB [3-yr-MPB], 6 years since MPB [6-yr-MPB], and 9 years since MPB [9-yr-MPB] mortality) in north central British Columbia, Canada. The goal was to determine partial loss of serotiny due to fall of crown-stored cones via breakage of branches and in situ opening of canopy cones throughout the 2008 and 2009 growing seasons. We also quantified seed release by the opening of forest-floor cones, loss of seed from rodent predation, and cone burial. Trees killed by MPB three years earlier dropped approximately 3.5 times more cones via branch breakage compared to live stands. After six years, MPB-killed stands had released 45% of their canopy seed bank through cone opening, cone fall due to breakage, and squirrel predation. Further losses of canopy seed banks are expected with time since we found 9-yr-MPB stands had 38% more open canopy cones. This was countered by the development of a modest forest-floor seed bank (6% of the original canopy seed bank) from burial of cones; this seed bank may be ecologically important if a fire or anthropogenic disturbance reexposes these cones. If adequate levels of regeneration are to occur, disturbances to create seedbeds must occur shortly after tree mortality, before the seed banks are lost. Our findings also suggest that the sustained seed rain (over at least nine years) after MPB outbreak may be beneficial for population growth of ground-foraging vertebrates. Our study adds insight to the seed ecology of serotinous pines under a potentially continental-wide insect outbreak, threatening vast forests adapted to regeneration after fire. Key words: biotic disturbance; cone burial; cone opening; Dendroctonus ponderosae; ground-foraging vertebrates; mountain pine beetle; natural regeneration; Pinus contorta var. latifolia; Rocky Mountain lodgepole pine; seed banks; serotiny (canopy seed storage); Tamiasciurus hudsonicus.

Female condoms scheduled to reach U.S. market this year.

PubMed

1991-08-01

3 female condoms, or "vaginal pouches" as they are called by the FDA (US Food and Drug Administration) are expected to be marketed in the US in 1991, the Bikini Condom from International Prophylactics Inc., Princeton NJ; Women's Choice from M.D. Personal Products, Hayward CA; and Reality from Wisconsin Pharmacal Co., Jackson, WI. The advantages of the female condoms are control for women over contraception and sexually transmitted diseases (STDs), availability over the counter, no need for spermicides, thicker than male condoms with better barrier effectiveness and less breakage and slippage, and reported heightened sensation for women. The disadvantages are difficulty for inexperienced women to insert, unappealing appearance of part of device protruding from vagina, interference with foreplay, cost of $1.50-$2.40 each, few reports of vaginal irritation. The Bikini Condom looks like a G-string panty with a condom pouch that is automatically introduced into the vagina with coitus. Bikini had a breakage rate of 0.5%, compared to 1-2% for male condoms, an acceptance level of 56%, and can be used 5-10 times. It effectively blocked STDs and HIV (human immunodeficiency virus). Women's Choice has a 2-inch diameter flexible ring that covers the introitus, and a thickened dome of latex resembling a diaphragm at the deep end, lubricated with silicone. 20% of women reported increased clitoral and labial sensation during use. It prevented transfer of semen acid phosphatase, and enzyme smaller than STDs and viruses. Reality condom is a polyurethane sheath with an inner ring similar to a diaphragm, but fitting more loosely, and an outer ring covering part of the vulva, all inserted with an applicator. It had a leakage rate of 0.6% compared to 3.5% for male condoms, and a slippage rate of 2.7% compared to 8.1% slippage and breakage of male condoms. 5% of users reported vaginal irritation. 65% of women and 80% of men liked Reality. Generally people in female condom trials either strongly liked or disliked them. They are so novel that they appeal to people with an "open mind," and to those with experience with condoms and other barrier methods.

Survival of bonded lingual retainers with chemical or photo polymerization over a 2-year period: a single-center, randomized controlled clinical trial.

PubMed

Pandis, Nikolaos; Fleming, Padhraig S; Kloukos, Dimitrios; Polychronopoulou, Argy; Katsaros, Christos; Eliades, Theodore

2013-08-01

The objective of this trial was to compare the survival rates of mandibular lingual retainers bonded with either chemically cured or light-cured adhesive after orthodontic treatment. Patients having undergone orthodontic treatment at a private orthodontic office were randomly allocated to fixed retainers placed with chemically cured composite or light-cured composite. Eligibility criteria included no active caries, restorations, or fractures on the mandibular anterior teeth, and adequate oral hygiene. The main outcome was any type of first-time lingual retainer breakage; pattern of failure (adapted adhesive remnant index scores) was a secondary outcome. Randomization was accomplished with random permuted blocks of 20 patients with allocation concealed in sequentially numbered, opaque, sealed envelopes. Blinding was applicable for outcome assessment only. Patients were reviewed at 1, 3, and 6 months and then every 6 months after placement of the retainer until completion of the study. Data were analyzed using survival analysis including Cox regression; sensitivity analysis was carried out after data imputation for subjects lost to follow-up. Two hundred twenty patients (median age, 16 years; interquartile range, 2; range, 12-47 years) were randomized in a 1:1 ratio to either chemical or light curing. Baseline characteristics were similar between groups, the median follow-up period was 2.19 years (range, 0.003-3.64 years), and 16 patients were lost to follow-up. At a minimum follow-up of 2 years, 47 of 110 (42.7%) and 55 of 110 (50.0%) retainers had some type of failure with chemically cured and light-cured adhesive, respectively (log-rank test, P = 0.35). Data were analyzed on an intention-to-treat basis, and the hazard ratio (HR) was 1.15 (95% confidence interval [CI], 0.88-1.70; P = 0.47). There was weak evidence that age is a significant predictor for lingual retainer failures (HR, 0.96; 95% CI, 0.93-1.00; P = 0.08). Adhesive remnant index scoring was possible for only 66 of the 102 (64.7%) failures and did not differ between composites (Fisher exact test, P = 0.16). No serious harm was observed other than gingivitis associated with plaque accumulation. The results of this study indicated no evidence that survival of mandibular lingual retainers differs between chemically and light-cured adhesives. The overall failure rate was 46.4%; however, this included any type of failure, which may have exaggerated the overall failure rate. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Research on the Digital Communication and Development of Yunnan Bai Embroidery

NASA Astrophysics Data System (ADS)

Xu, Wu; Jin, Chunjie; Su, Ying; Wu, Lei; He, Jin

2017-12-01

Our country attaches great importance to the protection and development of intangible culture these days, but the shortcoming of discoloration, breakage and occupying too much space still exist in the traditional way of museum protection. This paper starts from the analysis of the above problems, and then cogitates why and how to use the virtual reality (VR) technology to better solve these problems and analyzes this specific object of the Yunnan Bai embroidery in order to achieve its full human value and economic value. Firstly, using 3D MAX to design and produce the three-dimensional model of the embroideries of Bai nationality. Secondly, using the large number of embroidery model data that we collect to construct the Yunnan Bai embroidery model database. Next, creating a digital display system of virtual embroidery and putting the digital display system to the PC client websites and mobile phone applications to achieve information sharing. Finally, through the use of virtual display technology for three-dimensional design of embroidery, the embroidery clothing, bedding and other works with modern style can be designed so as to continuously pursue and give full play to the charm and economic value of embroidery.

The Aspects About of Objectively Appraisals of Modeling Gypsum Quality and Composites of Phonic-Absorbent and Orthopedic on Base of Gypsum

NASA Astrophysics Data System (ADS)

Pop, P. A.; Ungur, P. A.; Lazar, L.; Marcu, F.

2009-11-01

The EU Norms about of protection environment, outside and inside ambient, and human health demands has lead at obtain of new materials on the base of airborne material, with high thermo and phonic-absorbent properties, porous and lightweight. The α and β-modeling gypsum plaster quality and lightweight depend on many factors as: fabrication process, granulation, roast temperature, work temperature, environment, additives used, breakage, etc. Also, the objectively appraisal of modeling gypsum quality depends of proper tests methods selection, which are legislated in norms, standards and recommendations. In Romanian Standards SR EN 13279-1/2005 and SR EN 13279-2/2005, adaptable from EU Norms EN 13279-1/2004 and EN 13279-2/2004, the characteristics gypsum family tests are well specification, as: granule-metric analysis, determination of water/plaster ratio, setting time, mechanical characteristics, adhesions and water restrain. For plaster with special use (phonic-absorbent and orthopedic materials, etc.) these determinations are not concluding, being necessary more parameters finding, as: elastic constant, phonic-absorbent coefficient, porosity, working, etc., which is imposed the completion of norms and standards with new determinations.

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

NASA Astrophysics Data System (ADS)

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

2016-07-01

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

Monoclonal antibody disulfide reduction during manufacturing

PubMed Central

Hutterer, Katariina M.; Hong, Robert W.; Lull, Jonathon; Zhao, Xiaoyang; Wang, Tian; Pei, Rex; Le, M. Eleanor; Borisov, Oleg; Piper, Rob; Liu, Yaoqing Diana; Petty, Krista; Apostol, Izydor; Flynn, Gregory C.

2013-01-01

Manufacturing-induced disulfide reduction has recently been reported for monoclonal human immunoglobulin gamma (IgG) antibodies, a widely used modality in the biopharmaceutical industry. This effect has been tied to components of the intracellular thioredoxin reduction system that are released upon cell breakage. Here, we describe the effect of process parameters and intrinsic molecule properties on the extent of reduction. Material taken from cell cultures at the end of production displayed large variations in the extent of antibody reduction between different products, including no reduction, when subjected to the same reduction-promoting harvest conditions. Additionally, in a reconstituted model in which process variables could be isolated from product properties, we found that antibody reduction was dependent on the cell line (clone) and cell culture process. A bench-scale model using a thioredoxin/thioredoxin reductase regeneration system revealed that reduction susceptibility depended on not only antibody class but also light chain type; the model further demonstrates that the trend in reducibility was identical to DTT reduction sensitivity following the order IgG1λ > IgG1κ > IgG2λ > IgG2κ. Thus, both product attributes and process parameters contribute to the extent of antibody reduction during production. PMID:23751615

Modeling of gas-liquid mass transfer in a stirred tank bioreactor agitated by a Rushton turbine or a new pitched blade impeller.

PubMed

Gelves, Ricardo; Dietrich, A; Takors, Ralf

2014-03-01

A combined computational fluid dynamics (CFD) and population balance model (PBM) approach has been applied to simulate hydrodynamics and mass transfer in a 0.18 m(3) gas-liquid stirred bioreactor agitated by (1) a Rushton turbine, and (2) a new pitched blade geometry with rotating cartridges. The operating conditions chosen were motivated by typical settings used for culturing mammalian cells. The effects of turbulence, rotating flow, bubbles breakage and coalescence were simulated using the k-ε, multiple reference frame (MRF), Sliding mesh (SM) and PBM approaches, respectively. Considering the new pitched blade geometry with rotating aeration microspargers, [Formula: see text] mass transfer was estimated to be 34 times higher than the conventional Rushton turbine set-up. Notably, the impeller power consumption was modeled to be about 50 % lower. Independent [Formula: see text] measurements applying the same operational conditions confirmed this finding. Motivated by these simulated and experimental results, the new aeration and stirring device is qualified as a very promising tool especially useful for cell culture applications which are characterized by the challenging problem of achieving relatively high mass transfer conditions while inserting only low stirrer energy.

Residual Strength Prediction of Fuselage Structures with Multiple Site Damage

NASA Technical Reports Server (NTRS)

Chen, Chuin-Shan; Wawrzynek, Paul A.; Ingraffea, Anthony R.

1999-01-01

This paper summarizes recent results on simulating full-scale pressure tests of wide body, lap-jointed fuselage panels with multiple site damage (MSD). The crack tip opening angle (CTOA) fracture criterion and the FRANC3D/STAGS software program were used to analyze stable crack growth under conditions of general yielding. The link-up of multiple cracks and residual strength of damaged structures were predicted. Elastic-plastic finite element analysis based on the von Mises yield criterion and incremental flow theory with small strain assumption was used. A global-local modeling procedure was employed in the numerical analyses. Stress distributions from the numerical simulations are compared with strain gage measurements. Analysis results show that accurate representation of the load transfer through the rivets is crucial for the model to predict the stress distribution accurately. Predicted crack growth and residual strength are compared with test data. Observed and predicted results both indicate that the occurrence of small MSD cracks substantially reduces the residual strength. Modeling fatigue closure is essential to capture the fracture behavior during the early stable crack growth. Breakage of a tear strap can have a major influence on residual strength prediction.

A model problem for estimation of moving-film time relaxation at sudden change of boundary conditions

NASA Astrophysics Data System (ADS)

Smirnovsky, Alexander A.; Eliseeva, Viktoria O.

2018-05-01

The study of the film flow occurred under the influence of a gas slug flow is of definite interest in heat and mass transfer during the motion of a coolant in the second circuit of a nuclear water-water reactor. Thermohydraulic codes are usually used for analysis of the such problems in which the motion of the liquid film and the vapor is modeled on the basis of a one-dimensional balance equations. Due to a greater inertia of the liquid film motion, film flow parameters changes with a relaxation compared with gas flow. We consider a model problem of film flow under the influence of friction from gas slug flow neglecting such effects as wave formation, droplet breakage and deposition on the film surface, evaporation and condensation. Such a problem is analogous to the well-known problems of Couette and Stokes flows. An analytical solution has been obtained for laminar flow. Numerical RANS-based simulation of turbulent flow was performed using OpenFOAM. It is established that the relaxation process is almost self-similar. This fact opens a possibility of obtaining valuable correlations for the relaxation time.

Cutting process simulation of flat drill

NASA Astrophysics Data System (ADS)

Tamura, Shoichi; Matsumura, Takashi

2018-05-01

Flat drills at a point angle of 180 deg. have recently been developed for drilling of automobile parts with the inclination of the workpiece surfaces. The paper studies the cutting processes of the flat drills in the analytical simulation. A predictive force model is applied to simulation of the cutting force with the chip flow direction. The chip flow model is piled up with orthogonal cuttings in the plane containing the cutting velocities and the chip flow velocities, in which the chip flow direction is determined to minimize the cutting energy. Then, the cutting force is predicted in the determined in the chip flow model. The typical cutting force of the flat drill is discussed with comparing to that of the standard drill. The typical differences are confirmed in the cutting force change during the tool engagement and disengagement. The cutting force, then, is simulated in drilling for an inclined workpiece with a flat drill. The horizontal components in the cutting forces are simulated with changing the inclination angle of the plate. The horizontal force component in the flat drilling is stable to be controlled in terms of the machining accuracy and the tool breakage.

Modelling of Coke Layer Collapse during Ore Charging in Ironmaking Blast Furnace by DEM

NASA Astrophysics Data System (ADS)

Narita, Yoichi; Mio, Hiroshi; Orimoto, Takashi; Nomura, Seiji

2017-06-01

A technical issue in an ironmaking blast furnace operation is to realize the optimum layer thickness and the radial distribution of burden (ore and coke) to enhance its efficiency and productivity. When ore particles are charged onto the already-embedded coke layer, the coke layer-collapse phenomenon occurs. The coke layer-collapse phenomenon has a significant effect on the distribution of ore and coke layer thickness in the radial direction. In this paper, the mechanical properties of coke packed bed under ore charging were investigated by the impact-loading test and the large-scale direct shear test. Experimental results show that the coke particle is broken by the impact force of ore charging, and the particle breakage leads to weaken of coke-layer strength. The expression of contact force for coke in Discrete Element Method (DEM) was modified based on the measured data, and it followed by the 1/3-scaled experiment on coke's collapse phenomena. Comparing a simulation by modified model to the 1/3-scaled experiment, they agreed well in the burden distribution.