Impact of Gas-Phase Mechanisms on Weather Research Forecasting Model with Chemistry (WRF/Chem) Predictions: Mechanism Implementation and Comparative Evaluation

EPA Science Inventory

Gas-phase mechanisms provide important oxidant and gaseous precursors for secondary aerosol formation. Different gas-phase mechanisms may lead to different predictions of gases, aerosols, and aerosol direct and indirect effects. In this study, WRF/Chem-MADRID simulations are cond...

Evaluation of mechanical deformation and distributive magnetic loads with different mechanical constraints in two parallel conducting bars

NASA Astrophysics Data System (ADS)

Lee, Ho-Young; Lee, Se-Hee

2017-08-01

Mechanical deformation, bending deformation, and distributive magnetic loads were evaluated numerically and experimentally for conducting materials excited with high current. Until now, many research works have extensively studied the area of magnetic force and mechanical deformation by using coupled approaches such as multiphysics solvers. In coupled analysis for magnetoelastic problems, some articles and commercial software have presented the resultant mechanical deformation and stress on the body. To evaluate the mechanical deformation, the Lorentz force density method (LZ) and the Maxwell stress tensor method (MX) have been widely used for conducting materials. However, it is difficult to find any experimental verification regarding mechanical deformation or bending deformation due to magnetic force density. Therefore, we compared our numerical results to those from experiments with two parallel conducting bars to verify our numerical setup for bending deformation. Before showing this, the basic and interesting coupled simulation was conducted to test the mechanical deformations by the LZ (body force density) and the MX (surface force density) methods. This resulted in MX gave the same total force as LZ, but the local force distribution in MX introduced an incorrect mechanical deformation in the simulation of a solid conductor.

Effect of Polymer Form and its Consolidation on Mechanical Properties and Quality of Glass/PBT Composites

NASA Astrophysics Data System (ADS)

Durai Prabhakaran, R. T.; Pillai, Saju; Charca, Samuel; Oshkovr, Simin Ataollahi; Knudsen, Hans; Andersen, Tom Løgstrup; Bech, Jakob Ilsted; Thomsen, Ole Thybo; Lilholt, Hans

2014-04-01

The aim of this study was to understand the role of the processing in determining the mechanical properties of glass fibre reinforced polybutylene terephthalate composites (Glass/PBT). Unidirectional (UD) composite laminates were manufactured by the vacuum consolidation technique using three different material systems included in this study; Glass/CBT (CBT160 powder based resin), Glass/PBT (prepreg tapes), and Glass/PBT (commingled yarns). The different types of thermoplastic polymer resin systems used for the manufacturing of the composite UD laminate dictate the differences in final mechanical properties which were evaluated by through compression, flexural and short beam transverse bending tests. Microscopy was used to evaluate the quality of the processed laminates, and fractography was used to characterize the observed failure modes. The study provides an improved understanding of the relationships between processing methods, resin characteristics, and mechanical performance of thermoplastic resin composite materials.

Scanning electron microscopic evaluation of the influence of manual and mechanical glide path on the surface of nickel-titanium rotary instruments in moderately curved root canals: An in-vivo study.

PubMed

Patel, Dishant; Bashetty, Kusum; Srirekha, A; Archana, S; Savitha, B; Vijay, R

2016-01-01

The aim of this study was to evaluate the influence of manual versus mechanical glide path (GP) on the surface changes of two different nickel-titanium rotary instruments used during root canal therapy in a moderately curved root canal. Sixty systemically healthy controls were selected for the study. Controls were divided randomly into four groups: Group 1: Manual GP followed by RaCe rotary instruments, Group 2: Manual GP followed by HyFlex rotary instruments, Group 3: Mechanical GP followed by RaCe rotary instruments, Group 4: Mechanical GP followed by HyFlex rotary instruments. After access opening, GP was prepared and rotary instruments were used according to manufacturer's instructions. All instruments were evaluated for defects under standard error mean before their use and after a single use. The scorings for the files were given at apical and middle third. Chi-squared test was used. The results showed that there is no statistical difference between any of the groups. Irrespective of the GP and rotary files used, more defects were present in the apical third when compared to middle third of the rotary instrument. Within the limitations of this study, it can be concluded that there was no effect of manual or mechanical GP on surface defects of subsequent rotary file system used.

A comparative study on the mechanical energy of the normal, ACL, osteoarthritis, and Parkinson subjects.

PubMed

Bahreinizad, Hossein; Salimi Bani, Milad; Hasani, Mojtaba; Karimi, Mohammad Taghi; Sharifmoradi, Keyvan; Karimi, Alireza

2017-08-09

The influence of various musculoskeletal disorders has been evaluated using different kinetic and kinematic parameters. But the efficiency of walking can be evaluated by measuring the effort of the subject, or by other words the energy that is required to walk. The aim of this study was to identify mechanical energy differences between the normal and pathological groups. Four groups of 15 healthy subjects, 13 Parkinson subjects, 4 osteoarthritis subjects, and 4 ACL reconstructed subjects have participated in this study. The motions of foot, shank and thigh were recorded using a three dimensional motion analysis system. The kinetic, potential and total mechanical energy of each segment was calculated using 3D markers positions and anthropometric measurements. Maximum value and sample entropy of energies was compared between the normal and abnormal subjects. Maximum value of potential energy of OA subjects was lower than the normal subjects. Furthermore, sample entropy of mechanical energy for Parkinson subjects was low in comparison to the normal subjects while sample entropy of mechanical energy for the ACL subjects was higher than that of the normal subjects. Findings of this study suggested that the subjects with different abilities show different mechanical energy during walking.

Establishing Biomechanical Mechanisms in Mouse Models: Practical Guidelines for Systematically Evaluating Phenotypic Changes in the Diaphyses of Long Bones

PubMed Central

Jepsen, Karl J; Silva, Matthew J; Vashishth, Deepak; Guo, X Edward; van der Meulen, Marjolein CH

2016-01-01

Mice are widely used in studies of skeletal biology, and assessment of their bones by mechanical testing is a critical step when evaluating the functional effects of an experimental perturbation. For example, a gene knockout may target a pathway important in bone formation and result in a “low bone mass” phenotype. But how well does the skeleton bear functional loads; eg, how much do bones deform during loading and how resistant are bones to fracture? By systematic evaluation of bone morphological, densitometric, and mechanical properties, investigators can establish the “biomechanical mechanisms” whereby an experimental perturbation alters whole-bone mechanical function. The goal of this review is to clarify these biomechanical mechanisms and to make recommendations for systematically evaluating phenotypic changes in mouse bones, with a focus on long-bone diaphyses and cortical bone. Further, minimum reportable standards for testing conditions and outcome variables are suggested that will improve the comparison of data across studies. Basic biomechanical principles are reviewed, followed by a description of the cross-sectional morphological properties that best inform the net cellular effects of a given experimental perturbation and are most relevant to biomechanical function. Although morphology is critical, whole-bone mechanical properties can only be determined accurately by a mechanical test. The functional importance of stiffness, maximum load, postyield displacement, and work-to-fracture are reviewed. Because bone and body size are often strongly related, strategies to adjust whole-bone properties for body mass are detailed. Finally, a comprehensive framework is presented using real data, and several examples from the literature are reviewed to illustrate how to synthesize morphological, tissue-level, and whole-bone mechanical properties of mouse long bones. PMID:25917136

Type synthesis for 4-DOF parallel press mechanism using GF set theory

NASA Astrophysics Data System (ADS)

He, Jun; Gao, Feng; Meng, Xiangdun; Guo, Weizhong

2015-07-01

Parallel mechanisms is used in the large capacity servo press to avoid the over-constraint of the traditional redundant actuation. Currently, the researches mainly focus on the performance analysis for some specific parallel press mechanisms. However, the type synthesis and evaluation of parallel press mechanisms is seldom studied, especially for the four degrees of freedom(DOF) press mechanisms. The type synthesis of 4-DOF parallel press mechanisms is carried out based on the generalized function(GF) set theory. Five design criteria of 4-DOF parallel press mechanisms are firstly proposed. The general procedure of type synthesis of parallel press mechanisms is obtained, which includes number synthesis, symmetrical synthesis of constraint GF sets, decomposition of motion GF sets and design of limbs. Nine combinations of constraint GF sets of 4-DOF parallel press mechanisms, ten combinations of GF sets of active limbs, and eleven combinations of GF sets of passive limbs are synthesized. Thirty-eight kinds of press mechanisms are presented and then different structures of kinematic limbs are designed. Finally, the geometrical constraint complexity( GCC), kinematic pair complexity( KPC), and type complexity( TC) are proposed to evaluate the press types and the optimal press type is achieved. The general methodologies of type synthesis and evaluation for parallel press mechanism are suggested.

The Effect of Instructional Objectives and General Objectives on Student Self-Evaluation of Psychomotor Performance in Power Mechanics.

ERIC Educational Resources Information Center

Janeczko, Robert John

The major purpose of this study was to ascertain the relative effects of student exposure to instructional objectives upon student self-evaluation of psychomotor activities in a college-level power mechanics course. A randomized posttest-only control group design was used with two different approaches to the statement of the objectives. Four…

The Evaluation of Industry Practical of Mechanical Engineering in Vocational Education: A CIPP Model Approach

NASA Astrophysics Data System (ADS)

Kamaludin, M.; Munawar, W.; Mahdan, D.; Simanjuntak, M. V.; Wendi, H. F.

2018-02-01

The learning system is not only studied on campus but also practicing in the world of work. Industry Practical aims to enable students to develop their skills in accordance with the real world of work. To know the success of the implementation of industry practical program then held evaluation. The evaluation of the program in this study used the CIPP evaluation approach (Context, Input, Process, Product). The purpose of this research is to know the extent of achievement and success of industry practical program at vocational school in Bandung with descriptive research method using mix method approach. The sample in this research is students majoring in mechanical engineering in the city of Bandung who have done industry practical.

Hand dermatitis in auto mechanics and machinists.

PubMed

Donovan, Jeffrey C H; Kudla, Irena; Holness, D Linn

2007-09-01

Auto mechanics and machinists presenting with suspected allergic contact dermatitis (ACD) have traditionally been patch-tested with a standard screening tray and a specialty tray such as the Oil and Cooling Fluid Series. While this has proven useful for patch-testing the machinist, there is a need for the development of a more specific allergen testing tray for the auto mechanic. The objective of the study was to compare clinical features and patch-test results of auto mechanics and machinists with hand dermatitis to evaluate differences in allergen profiles. We performed a chart review of 33 auto mechanics and 24 machinists referred to our Occupational Contact Dermatitis Clinic from 2002 to 2005 for evaluation of hand dermatitis. With a panel of 84 allergens, 52 positive reactions were detected in 17 cases of ACD in mechanics. The profiles were different from the cases of ACD diagnosed in 10 of 24 machinists. Mechanics and machinists differ in the spectrum of occupational exposures. Patch testing with greater numbers of allergens likely identifies a larger proportion of mechanics with occupationally relevant ACD. Further study is needed to determine the most appropriate allergens to include in a clinically useful "mechanic's tray."

Force decay of elastomeric chains - a mechanical design and product comparison study.

PubMed

Balhoff, David A; Shuldberg, Matthew; Hagan, Joseph L; Ballard, Richard W; Armbruster, Paul C

2011-03-01

To evaluate the percentage force decay of elastomeric chain products utilizing three different design mechanisms simulating canine retraction; and to evaluate the percentage force decay of elastomeric chain products from four different companies. In vitro, laboratory study. LSUHSC Dental School, New Orleans, LA, USA. Closed (non-spaced), grey elastomeric chains from four companies were selected for the study. Three acrylic resin jigs were constructed to provide a framework for three simulated space closure mechanisms. The 6-5-3, the chain loop, and the 6-3 were the configuration mechanisms used in the study. An electronic force gauge was used to measure the percentage force decay associated with each elastomeric chain over 28 days at preselected times. There was a significant difference in the mean percentage force decay for the three different mechanisms (P < 0·001). For all four companies, the 6-3 mechanical design had the smallest mean percentage force decay. There was a significant difference in the mean percentage force decay for the different companies (P < 0·001). For all three mechanisms, Ormco had the smallest percentage force decay while Unitek had the highest percentage force decay. The significant difference in the mean percentage force decay for the different mechanisms suggests that the 6-3 design is a more efficient means of closing extraction spaces utilizing elastomeric chains.

Social Information Processing Mechanisms and Victimization: A Literature Review.

PubMed

van Reemst, Lisa; Fischer, Tamar F C; Zwirs, Barbara W C

2016-01-01

The aim of the current literature review, which is based on 64 empirical studies, was to assess to what extent mechanisms of the Social Information Processing (SIP) model of Crick and Dodge (1994) are related to victimization. The reviewed studies have provided support for the relation between victimization and several social information processing mechanisms, especially the interpretation of cues and self-efficacy (as part of the response decision). The relationship between victimization and other mechanisms, such as the response generation, was only studied in a few articles. Until now research has often focused on just one step of the model, instead of attempting to measure the associations between multiple mechanisms and victimization in multivariate analyses. Such analyses would be interesting to gain more insight into the SIP model and its relationship with victimization. The few available longitudinal studies show that mechanisms both predict victimization (internal locus of control, negative self-evaluations and less assertive response selection) and are predicted by victimization (hostile attribution of intent and negative evaluations of others). Associations between victimization and SIP mechanisms vary across different types and severity of victimization (stronger in personal and severe victimization), and different populations (stronger among young victims). Practice could focus on these stronger associations and the interpretation of cues. More research is needed however, to investigate whether intervention programs that address SIP mechanisms are suitable for victimization and all relevant populations. © The Author(s) 2014.

Evaluation of function, performance, and preference as transfemoral amputees transition from mechanical to microprocessor control of the prosthetic knee.

PubMed

Hafner, Brian J; Willingham, Laura L; Buell, Noelle C; Allyn, Katheryn J; Smith, Douglas G

2007-02-01

To evaluate differences in function, performance, and preference between mechanical and microprocessor prosthetic knee control technologies. A-B-A-B reversal design. Home, community, and laboratory environments. Twenty-one unilateral, transfemoral amputees. Mechanical control prosthetic knee versus microprocessor control prosthetic knee (Otto Bock C-Leg). Stair rating, hill rating and time, obstacle course time, divided attention task accuracy and time, Amputee Mobility Predictor score, step activity, Prosthesis Evaluation Questionnaire score, Medical Outcomes Study 36-Item Short-Form Health Survey score, self-reported frequency of stumbles and falls, and self-reported concentration required for ambulation. Stair descent score, hill descent time, and hill sound-side step length showed significant (P<.01) improvement with the C-Leg. Users reported a significant (P<.05) decrease in frequency of stumbles and falls, frustration with falling, and difficulty in multitasking while using the microprocessor knee. Subject satisfaction with the C-Leg was significantly (P<.001) greater than the mechanical control prosthesis. The study population showed improved performance when negotiating stairs and hills, reduced frequency of stumbling and falling, and a preference for the microprocessor control C-Leg as compared with the mechanical control prosthetic knee.

Process Evaluation of AISI 4340 Steel Manufactured by Laser Powder Bed Fusion

NASA Astrophysics Data System (ADS)

Jelis, Elias; Hespos, Michael R.; Ravindra, Nuggehalli M.

2018-01-01

Laser powder bed fusion (L-PBF) involves the consolidation of metal powder, layer by layer, through laser melting and solidification. In this study, process parameters are optimized for AISI 4340 steel to produce dense and homogeneous structures. The optimized process parameters produce mechanical properties at the center of the build plate that are comparable to wrought in the vertical and horizontal orientations after heat treatment and machining. Four subsequent builds are filled with specimens to evaluate the mechanical behavior as a function of location and orientation. Variations in the mechanical properties are likely due to recoater blade interactions with the powder and uneven gas flow. The results obtained in this study are analyzed to assess the reliability and reproducibility of the process. A different build evaluates the performance of near-net-shaped tensile specimens angled 35°-90° from the build plate surface (horizontal). Ductility measurements and surface roughness vary significantly as a function of the build angle. In the stress-relieved and as-built conditions, the mechanical behavior of vertically oriented specimens exhibits somewhat lower and more variable ductility than horizontally oriented specimens. Therefore, several process variables affect the mechanical properties of parts produced by the L-PBF process.

Educational Software Evaluation Form for Teachers

ERIC Educational Resources Information Center

Kara, Yilmaz

2007-01-01

The purpose of the study was to develop an educational software evaluation form to provide an evaluation and selection instrument of educational software that met the requirements of some balance between mechanics, content and pedagogy that is user friendly. The subjects for the study comprised a group of 32 biology teachers working in secondary…

From Theory-Inspired to Theory-Based Interventions: A Protocol for Developing and Testing a Methodology for Linking Behaviour Change Techniques to Theoretical Mechanisms of Action.

PubMed

Michie, Susan; Carey, Rachel N; Johnston, Marie; Rothman, Alexander J; de Bruin, Marijn; Kelly, Michael P; Connell, Lauren E

2018-05-18

Understanding links between behaviour change techniques (BCTs) and mechanisms of action (the processes through which they affect behaviour) helps inform the systematic development of behaviour change interventions. This research aims to develop and test a methodology for linking BCTs to their mechanisms of action. Study 1 (published explicit links): Hypothesised links between 93 BCTs (from the 93-item BCT taxonomy, BCTTv1) and mechanisms of action will be identified from published interventions and their frequency, explicitness and precision documented. Study 2 (expert-agreed explicit links): Behaviour change experts will identify links between 61 BCTs and 26 mechanisms of action in a formal consensus study. Study 3 (integrated matrix of explicit links): Agreement between studies 1 and 2 will be evaluated and a new group of experts will discuss discrepancies. An integrated matrix of BCT-mechanism of action links, annotated to indicate strength of evidence, will be generated. Study 4 (published implicit links): To determine whether groups of co-occurring BCTs can be linked to theories, we will identify groups of BCTs that are used together from the study 1 literature. A consensus exercise will be used to rate strength of links between groups of BCT and theories. A formal methodology for linking BCTs to their hypothesised mechanisms of action can contribute to the development and evaluation of behaviour change interventions. This research is a step towards developing a behaviour change 'ontology', specifying relations between BCTs, mechanisms of action, modes of delivery, populations, settings and types of behaviour.

Parameterization of 18th January 2011 earthquake in Dalbadin Region, Southwest Pakistan

NASA Astrophysics Data System (ADS)

Shafiq-Ur-Rehman; Azeem, Tahir; Abd el-aal, Abd el-aziz Khairy; Nasir, Asma

2013-12-01

An earthquake of magnitude 7.3 Mw occurred on 18th January 2011 in Southwestern Pakistan, Baluchistan province (Dalbadin Region). The area has complex tectonics due to interaction of Indian, Eurasian and Arabian plates. Both thrust and strike slip earthquakes are dominant in this region with minor, localized normal faulting events. This earthquake under consideration (Dalbadin Earthquake) posed constraints in depth and focal parameters due to lack of data for evaluation of parameters from Pakistan, Iran or Afghanistan region. Normal faulting mechanism has been proposed by many researchers for this earthquake. In the present study the earthquake was relocated using the technique of travel time residuals. Relocated coordinates and depth were utilized to calculate the focal mechanism solution with outcome of a dominant strike slip mechanism, which is contrary to normal faulting. Relocated coordinates and resulting mechanism are more reliable than many reporting agencies as evaluation in this study is augmented by data from local seismic monitoring network of Pakistan. The tectonics in the area is governed by active subduction along the Makran Subduction Zone. This particular earthquake has strike slip mechanism due to breaking of subducting oceanic plate. This earthquake is located where oceanic lithosphere is subducting along with relative movements between Lut and Helmand blocks. Magnitude of this event i.e. Mw = 7.3, re evaluated depth and a previous study of mechanism of earthquake in same region (Shafiq et al., 2011) also supports the strike slip movement.

Short communication: Effect of on-farm feeding practices on rumen protected lysine products.

PubMed

Ji, P; Tucker, H A; Clark, R E; Miura, M; Ballard, C S

2016-02-01

Two independent studies were conducted to determine whether mechanical mixing of total mixed ration (TMR) or TMR dry matter alters Lys release from 6 rumen-protected Lys (RPL) products (A, B, C, D, E, and F). In the first study, routine mixing procedures were simulated to determine if inclusion of RPL products in TMR altered in situ release of Lys. Following mixing, Dacron bags containing RPL products were ruminally incubated for 0, 6, 12, or 24 h to determine Lys release. The second study occurred independently of the first, in which Lys release from RPL products was evaluated when incorporated into a TMR that differed in dry matter (DM) content. Bags containing TMR and RPL product mixture were stored at room temperature for 0, 6, 18, and 24 h to simulate RPL product exposure to TMR when mixed and delivered once per day. Concentration of free Lys in both studies was determined using ultra-performance liquid chromatography. Following mechanical mixing, ruminal Lys release was significantly greater for C and tended to increase for F. Mechanical mixing did not alter ruminal Lys release from other RPL products evaluated. Hours of ruminal incubation significantly altered Lys release for all products evaluated, and a significant interaction of mechanical mixing and hours of ruminal incubation was observed for A and C. Exposure to lower TMR DM (40.5 versus 51.8%) significantly increased Lys release from B but did not alter Lys release from the other RPL products evaluated. Moreover, time of exposure to TMR significantly increased Lys release from all RPL products evaluated, and a significant interaction of TMR DM and time of exposure to TMR was observed for B and E. These data suggest mechanical mixing and variation in TMR DM may compromise the rumen protection of RPL products; therefore, on-farm feeding practices may alter efficacy of RPL products in dairy rations. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Study of Mechanization in DOD Libraries and Information Centers.

ERIC Educational Resources Information Center

Booz, Allen Applied Research, Inc., Bethesda, MD.

This report summarizes the on-site study of mechanization in DoD libraries and information centers. Included are presentations and evaluations on thesaurus building, file structure, input processing, serial control, selective dissemination of information, circulation control, equipments being used, recommendations on information retrieval systems,…

Design and Evaluation of an Electronic Override Mechanism for Medication Alerts to Facilitate Communication Between Prescribers and Pharmacists.

PubMed

Russ, Alissa L; Chen, Siying; Melton, Brittany L; Saleem, Jason J; Weiner, Michael; Spina, Jeffrey R; Daggy, Joanne K; Zillich, Alan J

2015-07-01

Computerized medication alerts can often be bypassed by entering an override rationale, but prescribers' override reasons are frequently ambiguous to pharmacists who review orders. To develop and evaluate a new override mechanism for adverse reaction and drug-drug interaction alerts. We hypothesized that the new mechanism would improve usability for prescribers and increase the clinical appropriateness of override reasons. A counterbalanced, crossover study was conducted with 20 prescribers in a simulated prescribing environment. We modified the override mechanism timing, navigation, and text entry. Instead of free-text entry, the new mechanism presented prescribers with a predefined set of override reasons. We assessed usability (learnability, perceived efficiency, and usability errors) and used a priori criteria to evaluate the clinical appropriateness of override reasons entered. Prescribers rated the new mechanism as more efficient (Wilcoxon signed-rank test, P = 0.032). When first using the new design, 5 prescribers had difficulty finding the new mechanism, and 3 interpreted the navigation to mean that the alert could not be overridden. The number of appropriate override reasons significantly increased with the new mechanism compared with the original mechanism (median change of 3.0; interquartile range = 3.0; P < 0.0001). When prescribers were given a menu-based choice for override reasons, clinical appropriateness of these reasons significantly improved. Further enhancements are necessary, but this study is an important first step toward a more standardized menu of override choices. Findings may be used to improve communication through e-prescribing systems between prescribers and pharmacists. © The Author(s) 2015.

CRITICAL MECHANICAL PROPERTIES OF STRUCTURAL LIGHT-WEIGHT CONCRETE AND THE EFFECTS OF THESE PROPERTIES ON THE DESIGN OF THE PAVEMENT STRUCTURE.

DOT National Transportation Integrated Search

1965-01-01

In this study, critical mechanical properties of structural lightweight concrete were determined and utilized in the evaluation of a design of concrete pavements. Also presented are the critical mechanical properties resulting from unrestrained and r...

Study of hepatocyte plasma membrane mechanical properties using optical trapping

NASA Astrophysics Data System (ADS)

Vedyaykin, A. D.; Morozova, N. E.; Pobegalov, G. E.; Arseniev, A. N.; Khodorkoskii, M. A.; Sabantsev, A. V.

2014-12-01

In this paper we describe the use of membrane tether formation technique which is widely used to study mechanical properties of plasma membranes. This method was successfully used for the direct measurement of parameters characterizing membranes mechanical properties (static tether tension force and effective membrane viscosity) of human hepatocytes (HepG2 hepatocellular carcinoma line). These results allow using this method in future for diagnostics of the cell membrane, evaluating the influence on the mechanical parameters of various factors, including toxins and drugs.

Experimental study of evaluation of mechanical parameters of heterogeneous porous structure

NASA Astrophysics Data System (ADS)

Gerasimov, O.; Koroleva, E.; Sachenkov, O.

2017-06-01

The paper deals with the problem of determining the mechanical macroparameters of the porous material in case of knowing the information about it’s structure. Fabric tensor and porosity was used to describe structure of the material. Experimental study presented. In research two-component liquid polyurethane plastics of cold curing Lasilcast (Lc-12) was used. Then samples was scanned on computer tomography. Resulting data was analyzed. Regular subvolume was cut out after analyses. Then mechanical tests was performed. As a result we get information about fabric tensor, porosity, Young’s modulus and Poisson ratio of the sample. In the abstract presented results for some samples. Taking into account the law of porosity variation, we considered the problem of evaluating the mechanical macro parameters depending on the nature of the porous structure. To evaluate the macroparameters, we built the dependence of the Young’s modules and Poisson ratio of the material on the rotation angle α and the pore ellipticity parameter λ. The sensitivity of the deformations to the elastic constants was also estimated.

Scanning electron microscopic evaluation of the influence of manual and mechanical glide path on the surface of nickel-titanium rotary instruments in moderately curved root canals: An in-vivo study

PubMed Central

Patel, Dishant; Bashetty, Kusum; Srirekha, A.; Archana, S.; Savitha, B.; Vijay, R.

2016-01-01

Aim: The aim of this study was to evaluate the influence of manual versus mechanical glide path (GP) on the surface changes of two different nickel-titanium rotary instruments used during root canal therapy in a moderately curved root canal. Materials and Methods: Sixty systemically healthy controls were selected for the study. Controls were divided randomly into four groups: Group 1: Manual GP followed by RaCe rotary instruments, Group 2: Manual GP followed by HyFlex rotary instruments, Group 3: Mechanical GP followed by RaCe rotary instruments, Group 4: Mechanical GP followed by HyFlex rotary instruments. After access opening, GP was prepared and rotary instruments were used according to manufacturer's instructions. All instruments were evaluated for defects under standard error mean before their use and after a single use. The scorings for the files were given at apical and middle third. Statistical Analysis Used: Chi-squared test was used. Results: The results showed that there is no statistical difference between any of the groups. Irrespective of the GP and rotary files used, more defects were present in the apical third when compared to middle third of the rotary instrument. Conclusion: Within the limitations of this study, it can be concluded that there was no effect of manual or mechanical GP on surface defects of subsequent rotary file system used. PMID:27994317

Evaluating Risk Awareness in Undergraduate Students Studying Mechanical Engineering

ERIC Educational Resources Information Center

Langdon, G. S.; Balchin, K.; Mufamadi, P.

2010-01-01

This paper examines the development of risk awareness among undergraduate students studying mechanical engineering at a South African university. A questionnaire developed at the University of Liverpool was modified and used on students from the first, second and third year cohorts to assess their awareness in the areas of professional…

Characterization of Solid Polymers, Ceramic Gap Filler, and Closed-Cell Polymer Foam Using Low-Load Test Methods

NASA Technical Reports Server (NTRS)

Herring, Helen M.

2008-01-01

Various solid polymers, polymer-based composites, and closed-cell polymer foam are being characterized to determine their mechanical properties, using low-load test methods. The residual mechanical properties of these materials after environmental exposure or extreme usage conditions determines their value in aerospace structural applications. In this experimental study, four separate polymers were evaluated to measure their individual mechanical responses after thermal aging and moisture exposure by dynamic mechanical analysis. A ceramic gap filler, used in the gaps between the tiles on the Space Shuttle, was also tested, using dynamic mechanical analysis to determine material property limits during flight. Closed-cell polymer foam, used for the Space Shuttle External Tank insulation, was tested under low load levels to evaluate how the foam's mechanical properties are affected by various loading and unloading scenarios.

Mechanical property loss and the occurrence of wood decay during experimental outdoor aging of wood based panels

Treesearch

Charles G. Carll; Alex C. Wiedenhoeft

2007-01-01

Small specimens of sheathing-grade oriented strandboard (OSB) and sheathing-grade plywood were evaluated for retention of mechanical properties in exterior exposure over a series of exposure times. In contrast to previous studies of this nature, specimens at prolonged exposure times were also evaluated (in something more than a cursory manner) for presence of decay....

Noise measurements during high-frequency oscillatory and conventional mechanical ventilation.

PubMed

Berens, R J; Weigle, C G

1995-10-01

To evaluate the noise levels with high-frequency oscillatory ventilation and conventional mechanical ventilation. An observational, prospective study. Pediatric intensive care unit. The caretakers and environment of the pediatric intensive care unit. High-frequency oscillatory and conventional mechanical ventilation. Caretakers evaluated noise using a visual analog scale. Noise was measured with a decibel meter and an octave band frequency filter. There was twice as much noise perceived by the caretakers and as measured on the decibel A scale. All measures showed significantly greater noise, especially at low frequencies, with high-frequency oscillatory ventilation. High-frequency oscillatory ventilation exposes the patient to twice as much noise as does the use of conventional mechanical ventilation.

Customizing the Connectivity Map Approach for Functional Evaluation in Toxicogenomics Studies (SOT)

EPA Science Inventory

Evaluating effects on the transcriptome can provide insight on putative chemical-specific mechanisms of action (MOAs). With whole genome transcriptomics technologies becoming more amenable to high-throughput screening, libraries of chemicals can be evaluated in vitro to produce l...

Mechanics of the injected pulsejet into gelatin gel and evaluation of the effect by puncture and crack generation and growth

NASA Astrophysics Data System (ADS)

Kato, T.; Arafune, T.; Washio, T.; Nakagawa, A.; Ogawa, Y.; Tominaga, T.; Sakuma, I.; Kobayashi, E.

2014-08-01

Recently, fluid jets have become widely used in medical devices and have been created and evaluated in clinical environments. Such devices are classified into two broad groups; those adopting continuous jets and those adopting discrete (or pulsed) jets. We developed a discrete jet device for brain cancer treatment, called a laser-induced liquid jet (LILJ) system. Although several studies have evaluated the availability and described the treatment mechanisms of fluid jet devices, the mechanisms of the fluid and injected material remain under-investigated. In this paper, we report the mechanism of frequent pulsejet injections into a viscoelastic biological material; namely, simulated gelatin brain tissue. The mechanism is evaluated by the injection depth, an easily measured parameter. To explain the injection mechanism, we propose that the pulsejet is pressured by forces introduced by resistance on the side surface of the hole and the reaction force proportionate to the injection depth. The pulsejet generated and propagated cracks in the gelatin, and the resistance eventually fractured the side surface of the hole. We evaluated the proposed model by measuring the behavior of pulsejets injected into gelatin by the LILJ. From the results, the following conclusions were obtained. First, the proposed model accurately describes the behavior of the injected pulsejet. Second, whether the hole or crack growth largely increases the final injection depth can be evaluated from differences in the decay constant. Finally, crack growth increases the final injection depth when the number of the injected pulsejets is greater than the inverse of the decay constant.

Evaluation of equipment and methods to map lost circulation zones in geothermal wells

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

McDonald, W.J.; Leon, P.A.; Pittard, G.

A study and evaluation of methods to locate, characterize, and quantify lost circulation zones are described. Twenty-five methods of mapping and quantifying lost circulation zones were evaluated, including electrical, acoustical, mechanical, radioactive, and optical systems. Each tool studied is described. The structured, numerical evaluation plan, used as the basis for comparing the 25 tools, and the resulting ranking among the tools is presented.

Explore the reaction mechanism of the Maillard reaction: a density functional theory study.

PubMed

Ren, Ge-Rui; Zhao, Li-Jiang; Sun, Qiang; Xie, Hu-Jun; Lei, Qun-Fang; Fang, Wen-Jun

2015-05-01

The mechanism of Maillard reaction has been investigated by means of density functional theory calculations in the gaseous phase and aqueous solution. The Maillard reaction is a cascade of consecutive and parallel reaction. In the present model system study, glucose and glycine were taken as the initial reactants. On the basis of previous experimental results, the mechanisms of Maillard reaction have been proposed, and the possibility for the formation of different compounds have been evaluated through calculating the relative energy changes for different steps of reaction under different pH conditions. Our calculations reveal that the TS3 in Amadori rearrangement reaction is the rate-determining step of Maillard reaction with the activation barriers of about 66.7 and 68.8 kcal mol(-1) in the gaseous phase and aqueous solution, respectively. The calculation results are in good agreement with previous studies and could provide insights into the reaction mechanism of Maillard reaction, since experimental evaluation of the role of intermediates in the Maillard reaction is quite complicated.

Experimental evaluation of multiscale tendon mechanics.

PubMed

Fang, Fei; Lake, Spencer P

2017-07-01

Tendon's primary function is a mechanical link between muscle and bone. The hierarchical structure of tendon and specific compositional constituents are believed to be critical for proper mechanical function. With increased appreciation for tendon importance and the development of various technological advances, this review paper summarizes recent experimental approaches that have been used to study multiscale tendon mechanics, includes an overview of studies that have evaluated the role of specific tissue constituents, and also proposes challenges/opportunities facing tendon study. Tendon has been demonstrated to have specific structural characteristics (e.g., multi-level hierarchy, crimp pattern, helix) and complex mechanical properties (e.g., non-linearity, anisotropy, viscoelasticity). Physical mechanisms including uncrimping, fiber sliding, and collagen reorganization have been shown to govern tendon mechanical responses under both static and dynamic loading. Several tendon constituents with relatively small quantities have been suggested to play a role in its mechanics, although some results are conflicting. Further research should be performed to understand the interplay and communication of tendon mechanical properties across levels of the hierarchical structure, and further show how each of these components contribute to tendon mechanics. The studies summarized and discussed in this review have helped elucidate important aspects of multiscale tendon mechanics, which is a prerequisite for analyzing stress/strain transfer between multiple scales and identifying key principles of mechanotransduction. This information could further facilitate interpreting the functional diversity of tendons from different species, different locations, and even different developmental stages, and then better understand and identify fundamental concepts related to tendon degeneration, disease, and healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1353-1365, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Multimedia-assisted breathwalk-aware system.

PubMed

Yu, Meng-Chieh; Wu, Huan; Lee, Ming-Sui; Hung, Yi-Ping

2012-12-01

Breathwalk is a science of combining specific patterns of footsteps synchronized with the breathing. In this study, we developed a multimedia-assisted Breathwalk-aware system which detects user's walking and breathing conditions and provides appropriate multimedia guidance on the smartphone. Through the mobile device, the system enhances user's awareness of walking and breathing behaviors. As an example application in slow technology, the system could help meditator beginners learn "walking meditation," a type of meditation which aims to be as slow as possible in taking pace, to synchronize footstep with breathing, and to land every footstep with toes first. In the pilot study, we developed a walking-aware system and evaluated whether multimedia-assisted mechanism is capable of enhancing beginner's walking awareness while walking meditation. Experimental results show that it could effectively assist beginners in slowing down the walking speed and decreasing incorrect footsteps. In the second experiment, we evaluated the Breathwalk-aware system to find a better feedback mechanism for learning the techniques of Breathwalk while walking meditation. The experimental results show that the visual-auditory mechanism is a better multimedia-assisted mechanism while walking meditation than visual mechanism and auditory mechanism.

Experimental and theoretical study on DPPH radical scavenging mechanism of some chalcone quinoline derivatives

NASA Astrophysics Data System (ADS)

Hamlaoui, Ikram; Bencheraiet, Reguia; Bensegueni, Rafik; Bencharif, Mustapha

2018-03-01

In this study, the antioxidant capacity of three chalcone derivatives was evaluated by DPPH free radical scavenging. Experimental data showed low antioxidant activity (IC50±SD) of these molecules in comparison with BHT. The mechanism of DPPH radical scavenging elucidated by means of density functional theory (DFT) calculations. The tested compounds and their corresponding radicals and anions were optimized using B3LYP functional with 6-31G (d,p) basis set in the gas phase. The C-PCM model was used to perform solvent medium calculations. On the basis of theoretical calculations, it was shown that HAT mechanism was predominant in the gas phase, whereas SET-PT and SPLET mechanisms were favored in the presence of the solvent. Moreover, the HOMO orbitals and spin density distribution was evaluated to predict the probable sites for free radical attack.

Effects and safety of mechanical bathing as a complementary therapy for terminal stage cancer patients from the physiological and psychological perspective: a pilot study.

PubMed

Fujimoto, Sawako; Iwawaki, Yoko; Takishita, Yukie; Yamamoto, Yoko; Murota, Masako; Yoshioka, Saori; Hayano, Azusa; Hosokawa, Toyoshi; Yamanaka, Ryuya

2017-11-01

In palliative care hospitals in Japan, mechanical bathing is conducted to maintain cleanliness. However, the physiological and psychological influence of mechanical bathing on patients has not been sufficiently studied. The objective of this study was to assess, using physiological and psychological indices, the effects of mechanical bathing care for patients in the terminal stage of cancer. Mechanical bathing was performed using a Marine Court SB7000 in a supine or semi-seated position. The heart rate variability analysis method was used to measure autonomic nervous system function. The patients' state of anxiety was assessed using the State-Trait Anxiety Inventory (STAI), a psychological index, and patients' verbal responses were also collected after mechanical bathing. Twenty-four patients were enrolled in this study. Their sympathetic and parasympathetic nervous activity did not differ before and after bathing. A significant difference was found between pre- and post-bathing anxiety, as evaluated by STAI (P < 0.0001). In the patient's verbal responses that was collected, the most frequently mentioned descriptors were 'comfortable' and 'relaxed'. Patients were more relaxed after mechanical bathing according to STAI evaluation and their verbal responses. The findings suggest that the method of bathing used in this study is safe and pain-relieving for terminal stage cancer patients. It is thus possible to provide safe and comfortable care for terminal stage cancer patients using mechanical baths. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Quality of protection evaluation of security mechanisms.

PubMed

Ksiezopolski, Bogdan; Zurek, Tomasz; Mokkas, Michail

2014-01-01

Recent research indicates that during the design of teleinformatic system the tradeoff between the systems performance and the system protection should be made. The traditional approach assumes that the best way is to apply the strongest possible security measures. Unfortunately, the overestimation of security measures can lead to the unreasonable increase of system load. This is especially important in multimedia systems where the performance has critical character. In many cases determination of the required level of protection and adjustment of some security measures to these requirements increase system efficiency. Such an approach is achieved by means of the quality of protection models where the security measures are evaluated according to their influence on the system security. In the paper, we propose a model for QoP evaluation of security mechanisms. Owing to this model, one can quantify the influence of particular security mechanisms on ensuring security attributes. The methodology of our model preparation is described and based on it the case study analysis is presented. We support our method by the tool where the models can be defined and QoP evaluation can be performed. Finally, we have modelled TLS cryptographic protocol and presented the QoP security mechanisms evaluation for the selected versions of this protocol.

Bilateral robots for upper-limb stroke rehabilitation: State of the art and future prospects.

PubMed

Sheng, Bo; Zhang, Yanxin; Meng, Wei; Deng, Chao; Xie, Shengquan

2016-07-01

Robot-assisted bilateral upper-limb training grows abundantly for stroke rehabilitation in recent years and an increasing number of devices and robots have been developed. This paper aims to provide a systematic overview and evaluation of existing bilateral upper-limb rehabilitation devices and robots based on their mechanisms and clinical-outcomes. Most of the articles studied here were searched from nine online databases and the China National Knowledge Infrastructure (CNKI) from year 1993 to 2015. Devices and robots were categorized as end-effectors, exoskeletons and industrial robots. Totally ten end-effectors, one exoskeleton and one industrial robot were evaluated in terms of their mechanical characteristics, degrees of freedom (DOF), supported control modes, clinical applicability and outcomes. Preliminary clinical results of these studies showed that all participants could gain certain improvements in terms of range of motion, strength or physical function after training. Only four studies supported that bilateral training was better than unilateral training. However, most of clinical results cannot definitely verify the effectiveness of mechanisms and clinical protocols used in robotic therapies. To explore the actual value of these robots and devices, further research on ingenious mechanisms, dose-matched clinical protocols and universal evaluation criteria should be conducted in the future. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Relationship between notch strengthening threshold and mechanical property for ductile cast iron

NASA Astrophysics Data System (ADS)

Ikeda, T.; Noda, N.-A.; Sano, Y.; Umetani, T.; Kai, N.

2018-06-01

In this study, dynamic tensile tests were conducted at the various strain rates and temperatures for traditional ductile cast iron. Then, the notch strength {σ }{{B}}{{noth}} and the static tensile strength at room temperature {σ }{{B,}\\quad {{RT}}}{{smooth}} were discussed in terms of the strain rate- temperature parameter R, which is known to be useful for evaluating the combined influence of strain rate and temperature. This study focuses on the notch strengthening threshold R ≧ R th where {σ }{{B}}{{noth}} is larger than {σ }{{B,}\\quad {{RT}}}{{smooth}} and therefore notched components can be used safely. In other words, if R ≧ R th, {σ }{{B,}\\quad {{RT}}}{{smooth}} can be used to evaluate notched components in mechanical design to prevent the instantaneous fracture. In this study, it was found that the R th value can be predicted from the static tensile property and Brinell hardness. Since the traditional ductile cast iron considered in this paper has a broad range of mechanical properties, the present approach and discussion can be applied to evaluate other materials under various temperature and strain rate.

Evaluation of Mechanical Properties and Morphological Studies of Rice Husk (Treated/Untreated)-CaCO3 Reinforced Epoxy Hybrid Composites

NASA Astrophysics Data System (ADS)

Verma, Deepak; Joshi, Garvit; Gupta, Ayush

2016-10-01

Natural fiber reinforced composites are a very popular area of research because of the easy availability and biodegradability of these fibers. The manufacturing of natural fiber composite is done by reinforcing fibers in the particulate form, fiber form or in woven mat form. Natural fiber composites also utilize industrial wastes as a secondary reinforcements like fly ash, sludge etc. By keeping all these point of views in the present investigation the effect of rice husk flour (chemically treated/untreated) and micro sized calcium carbonate with epoxy resin have been evaluated. The diameter of rice husk flour was maintained at 600 µm through mechanical sieving machine. The husk flour was chemically treated with NaOH (5 % w/v). Mechanical properties like hardness, flexural impact and compression strength were evaluated and found to be superior in modified or chemically treated flour as compared to unmodified or untreated flour reinforced composites. Scanning electron microscopy (SEM) study was also undertaken for the developed composites. SEM study shows the distribution of the rice husk flour and calcium carbonate over the matrix.

Exploring for the optimal structural design for the 3D-printing technology for cranial reconstruction: a biomechanical and histological study comparison of solid vs. porous structure.

PubMed

Lim, Jun Young; Kim, Namhyun; Park, Jong-Chul; Yoo, Sun K; Shin, Dong Ah; Shim, Kyu-Won

2017-09-01

Cranioplasty for recovering skull defects carries the risk for a number of complications. Various materials are used, including autologous bone graft, metallic materials, and non-metallic materials, each of which has advantages and disadvantages. If the use of autologous bone is not feasible, those artificial materials also have constraints in the case of complex anatomy and/or irregular defects. This study used metal 3D-printing technology to overcome these existing drawbacks and analyze the clinical and mechanical performance requirements. To find an optimal structure that satisfied the structural and mechanical stability requirements, we evaluated biomechanical stability using finite element analysis (FEA) and mechanical testing. To ensure clinical applicability, the model was subjected to histological evaluation. Each specimen was implanted in the femur of a rabbit and was evaluated using histological measurements and push-out test. We believe that our data will provide the basis for future applications of a variety of unit structures and further clinical trials and research, as well as the direction for the study of other patient-specific implants.

Mechanisms in Cardiovascular Diseases: How Useful Are Medical Textbooks, eMedicine, and YouTube?

ERIC Educational Resources Information Center

Azer, Samy A.

2014-01-01

The aim of this study was to assess the contents of medical textbooks, eMedicine (Medscape) topics, and YouTube videos on cardiovascular mechanisms. Medical textbooks, eMedicine articles, and YouTube were searched for cardiovascular mechanisms. Using appraisal forms, copies of these resources and videos were evaluated independently by three…

The Effectiveness Evaluation among Different Player-Matching Mechanisms in a Multi-Player Quiz Game

ERIC Educational Resources Information Center

Tsai, Fu-Hsing

2016-01-01

This study aims to investigate whether different player-matching mechanisms in educational multi-player online games (MOGs) can affect students' learning performance, enjoyment perception and gaming behaviors. Based on the multi-player quiz game, TRIS-Q, developed by Tsai, Tsai and Lin (2015) using a free player-matching (FPM) mechanism, the same…

Physical, mechanical, and fire properties of oriented strandboard with fire retardant treated veneers

Treesearch

Nadir Ayrilmis; Zeki Candan; Robert White

2007-01-01

This study evaluated physical, mechanical and fire properties of oriented strand boards (OSB) covered with fire retardant treated veneers. The beech (Fagus orientalis Lipsky) veneers were treated with either monoammonium phosphate, diammonium phosphate, lime water or a borax/boric acid (1 : 1 by weight) mixture. Physical and mechanical properties of the specimens were...

Mechanical Properties of Friction Stir Welds in A12195-T8

NASA Technical Reports Server (NTRS)

Kinchen, David G.; Li, Zhixian; Adams, Glynn P.

1999-01-01

An extensive study of the mechanical properties of friction stir welded Al-Li 2195 has been conducted by Lockheed Martin Michoud Space Systems under contract to NASA. The study was part of a development program in which weld parameters were defined for using FSW to assemble large-scale aluminum cryogenic tanks. In excess of 300 feet of 0.320 in. gage plate material was welded and tested. The tests include room temperature and cryogenic temperature tensile tests and surface crack tension (SCT) tests, nondestructive evaluation, metallurgical studies, and photostress analysis. The results of the testing demonstrated improved mechanical properties with FSW as compared to typical fusion welding processes. Increases in ultimate tensile strength, cryogenic enhancement and elongation were observed with the tensile test results. Increased fracture toughness was observed with the SCT results. Nondestructive evaluations were conducted on all welded Joints. No volumetric defects were indicated. Surface indications on the root side of the welds did not significantly affect weld strength. The results of the nondestructive evaluations were confirmed via metallurgical studies. Photostress analysis revealed strain concentrations in multi-pass and heat-repaired FSW's. Details of the tests and results are presented.

FTIR spectra and mechanical strength analysis of some selected rubber derivatives.

PubMed

Gunasekaran, S; Natarajan, R K; Kala, A

2007-10-01

Rubber materials have wide range of commercial applications such as, infant diapers, famine hygiene products, drug delivery devices and incontinency products such as rubber tubes, tyres, etc. In the present work, studies on mechanical properties of some selected rubber materials viz., natural rubber (NR), styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM) have been carried out in three states viz., raw, vulcanized and reinforced. To enhance the quality of rubber elastomers, an attempt is made to prepare new elastomers called polyblends. In the present study an attempt is made to blend NR with NBR and with EPDM. We here report, a novel approach for the evaluation of various physico-mechanical properties such as mechanical strength, tensile strength, elongation and hardness. The method is simple, direct and fast and involves infrared spectral measurements for the evaluation of these properties. With the applications of modern infrared spectroscopy, the mechanical strength of these rubber materials have been analyzed by calculating the internal standards among the methyl and methylene group vibrational frequencies obtained from FTIR spectroscopy. Also the tensile strength measurements carried out by universal testing machine. The results pertaining physico-mechanical properties of the rubber derivatives undertaken in the present study obtained by IR-based method are in good agreement with data resulted from the standard methods.

FTIR spectra and mechanical strength analysis of some selected rubber derivatives

NASA Astrophysics Data System (ADS)

Gunasekaran, S.; Natarajan, R. K.; Kala, A.

2007-10-01

Rubber materials have wide range of commercial applications such as, infant diapers, famine hygiene products, drug delivery devices and incontinency products such as rubber tubes, tyres, etc. In the present work, studies on mechanical properties of some selected rubber materials viz., natural rubber (NR), styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM) have been carried out in three states viz., raw, vulcanized and reinforced. To enhance the quality of rubber elastomers, an attempt is made to prepare new elastomers called polyblends. In the present study an attempt is made to blend NR with NBR and with EPDM. We here report, a novel approach for the evaluation of various physico-mechanical properties such as mechanical strength, tensile strength, elongation and hardness. The method is simple, direct and fast and involves infrared spectral measurements for the evaluation of these properties. With the applications of modern infrared spectroscopy, the mechanical strength of these rubber materials have been analyzed by calculating the internal standards among the methyl and methylene group vibrational frequencies obtained from FTIR spectroscopy. Also the tensile strength measurements carried out by universal testing machine. The results pertaining physico-mechanical properties of the rubber derivatives undertaken in the present study obtained by IR-based method are in good agreement with data resulted from the standard methods.

Nondestructive evaluation tools and experimental studies for monitoring the health of space propulsion systems

NASA Technical Reports Server (NTRS)

Generazio, Edward R.

1991-01-01

An overview is given of background and information on space propulsion systems on both the programmatic and technical levels. Feasibility experimental studies indicate that nondestructive evaluation tools such as ultrasonic, eddy current and x-ray may be successfully used to monitor the life limiting failure mechanisms of space propulsion systems. Encouraging results were obtained for monitoring the life limiting failure mechanisms for three space propulsion systems; the degradation of tungsten arcjet and magnetoplasmadynamic electrodes; presence and thickness of spallable electrically conducting molybdenum films in ion thrusters; and the degradation of the catalyst in hydrazine thrusters.

A realist evaluation of a physical activity participation intervention for children and youth with disabilities: what works, for whom, in what circumstances, and how?

PubMed

Willis, C E; Reid, S; Elliott, C; Rosenberg, M; Nyquist, A; Jahnsen, R; Girdler, S

2018-03-15

The need to identify strategies that facilitate involvement in physical activity for children and youth with disabilities is recognised as an urgent priority. This study aimed to describe the association between context, mechanisms and outcome(s) of a participation-focused physical activity intervention to understand what works, in what conditions, and how. This study was designed as a realist evaluation. Participant recruitment occurred through purposive and theoretical sampling of children and parents participating in the Local Environment Model intervention at Beitostolen Healthsports Centre in Norway. Ethnographic methods comprising participant observation, interviews, and focus groups were employed over 15 weeks in the field. Data analysis was completed using the context-mechanism-outcome framework of realist evaluation. Context-mechanism-outcome connections were generated empirically from the data to create a model to indicate how the program activated mechanisms within the program context, to enable participation in physical activity. Thirty one children with a range of disabilities (mean age 12y 6 m (SD 2y 2 m); 18 males) and their parents (n = 44; 26 mothers and 18 fathers) participated in the study. Following data synthesis, a refined program theory comprising four context themes, five mechanisms, and six outcomes, were identified. The mechanisms (choice, fun, friends, specialised health professionals, and time) were activated in a context that was safe, social, learning-based and family-centred, to elicit outcomes across all levels of the International Classification of Functioning, Disability and Health. The interaction of mechanisms and context as a whole facilitated meaningful outcomes for children and youth with disabilities, and their parents. Whilst optimising participation in physical activity is a primary outcome of the Local Environment Model, the refined program theory suggests the participation-focused approach may act as a catalyst to promote a range of outcomes. Findings from this study may inform future interventions attempting to enable participation in physical activity for children and youth with disabilities.

Feasibility Study of a Rotorcraft Health and Usage Monitoring System (HUMS): Results of Operator's Evaluation (MS Word file)

DOT National Transportation Integrated Search

1996-02-01

The objective of this study was to evaluate the feasibility of a state of the : art health and usage monitoring system (HUMS) to provide monitoring of critical : mechanical systems on the helicopter, including motors, drive train, engines : and life ...

On the evidence for species coexistence: a critique of the coexistence program.

PubMed

Siepielski, Adam M; McPeek, Mark A

2010-11-01

A major challenge in ecology is to understand how the millions of species on Earth are organized into biological communities. Mechanisms promoting coexistence are one such class of organizing processes, which allow multiple species to persist in the same trophic level of a given web of species interactions. If some mechanism promotes the coexistence of two or more species, each species must be able to increase when it is rare and the others are at their typical abundances; this invasibility criterion is fundamental evidence for species coexistence regardless of the mechanism. In an attempt to evaluate the level of empirical support for coexistence mechanisms in nature, we surveyed the literature for empirical studies of coexistence at a local scale (i.e., species found living together in one place) to determine whether these studies satisfied the invasibility criterion. In our survey, only seven of 323 studies that drew conclusions about species coexistence evaluated invasibility in some way in either observational or experimental studies. In addition, only three other studies evaluated necessary but not sufficient conditions for invasibility (i.e., negative density dependence and a trade-off in performance that influences population regulation). These results indicate that, while species coexistence is a prevalent assumption for why species are able to live together in one place, critical empirical tests of this fundamental assumption of community structure are rarely performed. These tests are central to developing a more robust understanding of the relative contributions of both deterministic and stochastic processes structuring biological communities.

VIPER: Chronic Pain after Amputation: Inflammatory Mechanisms, Novel Analgesic Pathways, and Improved Patient Safety

DTIC Science & Technology

2017-10-01

Through analysis of data obtained in the Molecular Signatures of Chronic Pain Subtypes study termed Veterans Integrated Pain Evaluation Research...immune cells (macrophages) to chronic pain while also evaluating novel analgesics in relevant animal models. The current proposal also attempts to...analysis of data obtained in the Molecular Signatures of Chronic Pain Subtypes study termed Veterans Integrated Pain Evaluation Research (VIPER

Graphical Tests for Power Comparison of Competing Designs.

PubMed

Hofmann, H; Follett, L; Majumder, M; Cook, D

2012-12-01

Lineups have been established as tools for visual testing similar to standard statistical inference tests, allowing us to evaluate the validity of graphical findings in an objective manner. In simulation studies lineups have been shown as being efficient: the power of visual tests is comparable to classical tests while being much less stringent in terms of distributional assumptions made. This makes lineups versatile, yet powerful, tools in situations where conditions for regular statistical tests are not or cannot be met. In this paper we introduce lineups as a tool for evaluating the power of competing graphical designs. We highlight some of the theoretical properties and then show results from two studies evaluating competing designs: both studies are designed to go to the limits of our perceptual abilities to highlight differences between designs. We use both accuracy and speed of evaluation as measures of a successful design. The first study compares the choice of coordinate system: polar versus cartesian coordinates. The results show strong support in favor of cartesian coordinates in finding fast and accurate answers to spotting patterns. The second study is aimed at finding shift differences between distributions. Both studies are motivated by data problems that we have recently encountered, and explore using simulated data to evaluate the plot designs under controlled conditions. Amazon Mechanical Turk (MTurk) is used to conduct the studies. The lineups provide an effective mechanism for objectively evaluating plot designs.

Added value of cardiac computed tomography for evaluation of mechanical aortic valve: Emphasis on evaluation of pannus with surgical findings as standard reference.

PubMed

Suh, Young Joo; Lee, Sak; Im, Dong Jin; Chang, Suyon; Hong, Yoo Jin; Lee, Hye-Jeong; Hur, Jin; Choi, Byoung Wook; Chang, Byung-Chul; Shim, Chi Young; Hong, Geu-Ru; Kim, Young Jin

2016-07-01

The added value of cardiac computed tomography (CT) with transesophageal echocardiography (TEE) for evaluating mechanical aortic valve (AV) dysfunction has not yet been investigated. The purposes of this study were to investigate the added value of cardiac CT for evaluation of mechanical AVs and diagnoses of pannus compared to TEE, with surgical findings of redo-aortic valve replacement (AVR) used as a standard reference. 25 patients who underwent redo-AVR due to mechanical AV dysfunction and cardiac CT before redo-AVR were included. The presence of pannus, encroachment ratio by pannus, and limitation of motion (LOM) were evaluated on CT. The diagnostic performance of pannus detection was compared using TEE, CT, and CT+TEE, with surgical findings as a standard reference. The added value of CT for diagnosing the cause of mechanical AV dysfunction was assessed compared to TTE+TEE. In two patients, CT analysis was not feasible due to severe metallic artifacts. On CT, pannus and LOM were found in 100% (23/23) and 60.9% (14/23). TEE identified pannus in 48.0% of patients (12/25). CT, TEE, and CT+TEE correctly identified pannus with sensitivity of 92.0%, 48.0%, and 92.0%, respectively (P=0.002 for CT vs. TEE). In 11 of 13 cases (84.6%) with inconclusive or negative TEE results for pannus, CT detected the pannus. Among 13 inconclusive cases of TTE+TEE for the cause of mechanical AV dysfunction, CT suggested 6 prosthetic valve obstruction (PVO) by pannus, 4 low-flow low-gradient PVO, and one LOM without significant PVO. Cardiac CT showed added diagnostic value with TEE in the detection of pannus as the cause of mechanical AV dysfunction. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Comparison between a clinical diagnosis method and the surveillance technique of the Center for Disease Control and Prevention for identification of mechanical ventilator-associated pneumonia.

PubMed

Waltrick, Renata; Possamai, Dimitri Sauter; de Aguiar, Fernanda Perito; Dadam, Micheli; de Souza Filho, Valmir João; Ramos, Lucas Rocker; Laurett, Renata da Silva; Fujiwara, Kênia; Caldeira Filho, Milton; Koenig, Álvaro; Westphal, Glauco Adrieno

2015-01-01

>To evaluate the agreement between a new epidemiological surveillance method of the Center for Disease Control and Prevention and the clinical pulmonary infection score for mechanical ventilator-associated pneumonia detection. This was a prospective cohort study that evaluated patients in the intensive care units of two hospitals who were intubated for more than 48 hours between August 2013 and June 2014. Patients were evaluated daily by physical therapist using the clinical pulmonary infection score. A nurse independently applied the new surveillance method proposed by the Center for Disease Control and Prevention. The diagnostic agreement between the methods was evaluated. A clinical pulmonary infection score of ≥ 7 indicated a clinical diagnosis of mechanical ventilator-associated pneumonia, and the association of a clinical pulmonary infection score ≥ 7 with an isolated semiquantitative culture consisting of ≥ 104 colony-forming units indicated a definitive diagnosis. Of the 801 patients admitted to the intensive care units, 198 required mechanical ventilation. Of these, 168 were intubated for more than 48 hours. A total of 18 (10.7%) cases of mechanical ventilation-associated infectious conditions were identified, 14 (8.3%) of which exhibited possible or probable mechanical ventilator-associated pneumonia, which represented 35% (14/38) of mechanical ventilator-associated pneumonia cases. The Center for Disease Control and Prevention method identified cases of mechanical ventilator-associated pneumonia with a sensitivity of 0.37, specificity of 1.0, positive predictive value of 1.0, and negative predictive value of 0.84. The differences resulted in discrepancies in the mechanical ventilator-associated pneumonia incidence density (CDC, 5.2/1000 days of mechanical ventilation; clinical pulmonary infection score ≥ 7, 13.1/1000 days of mechanical ventilation). The Center for Disease Control and Prevention method failed to detect mechanical ventilator-associated pneumonia cases and may not be satisfactory as a surveillance method.

Students' Learning Strategies with Multiple Representations: Explanations of the Human Breathing Mechanism

ERIC Educational Resources Information Center

Won, Mihye; Yoon, Heojeong; Treagust, David F.

2014-01-01

The purpose of this study was to understand how students utilized multiple representations to learn and explain science concepts, in this case the human breathing mechanism. The study was conducted with Grade 11 students in a human biology class. Semistructured interviews and a two-tier diagnostic test were administered to evaluate students'…

Cognitive Mechanism Underlying the Relationship between Rapid Automatized Naming and Reading: A Longitudinal Study on Bilingual Children

ERIC Educational Resources Information Center

Yeung, Susanna S.

2016-01-01

Rapid automatized naming has been demonstrated as an important correlate of various reading outcomes. However, the cognitive mechanism underlying the RAN-reading relationship is not well understood. The primary goal of this study is to evaluate three major theoretical accounts for the RAN--reading relationship: phonological processing account,…

Efficacy of respiratory muscle training in weaning of mechanical ventilation in patients with mechanical ventilation for 48hours or more: A Randomized Controlled Clinical Trial.

PubMed

Sandoval Moreno, L M; Casas Quiroga, I C; Wilches Luna, E C; García, A F

2018-02-02

To evaluate the efficacy of respiratory muscular training in the weaning of mechanical ventilation and respiratory muscle strength in patients on mechanical ventilation of 48hours or more. Randomized controlled trial of parallel groups, double-blind. Ambit: Intensive Care Unit of a IV level clinic in the city of Cali. 126 patients in mechanical ventilation for 48hours or more. The experimental group received daily a respiratory muscle training program with treshold, adjusted to 50% of maximal inspiratory pressure, additional to standard care, conventional received standard care of respiratory physiotherapy. MAIN INTEREST VARIABLES: weaning of mechanical ventilation. Other variables evaluated: respiratory muscle strength, requirement of non-invasive mechanical ventilation and frequency of reintubation. intention-to-treat analysis was performed with all variables evaluated and analysis stratified by sepsis condition. There were no statistically significant differences in the median weaning time of the MV between the groups or in the probability of extubation between groups (HR: 0.82 95% CI: 0.55-1.20 P=.29). The maximum inspiratory pressure was increased in the experimental group on average 9.43 (17.48) cmsH20 and in the conventional 5.92 (11.90) cmsH20 (P=.48). The difference between the means of change in maximal inspiratory pressure was 0.46 (P=.83 95%CI -3.85 to -4.78). respiratory muscle training did not demonstrate efficacy in the reduction of the weaning period of mechanical ventilation nor in the increase of respiratory muscle strength in the study population. Registered study at ClinicalTrials.gov (NCT02469064). Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Test-retest reliability of quantitative sensory testing for mechanical somatosensory and pain modulation assessment of masticatory structures.

PubMed

Costa, Y M; Morita-Neto, O; de Araújo-Júnior, E N S; Sampaio, F A; Conti, P C R; Bonjardim, L R

2017-03-01

Assessing the reliability of medical measurements is a crucial step towards the elaboration of an applicable clinical instrument. There are few studies that evaluate the reliability of somatosensory assessment and pain modulation of masticatory structures. This study estimated the test-retest reliability, that is over time, of the mechanical somatosensory assessment of anterior temporalis, masseter and temporomandibular joint (TMJ) and the conditioned pain modulation (CPM) using the anterior temporalis as the test site. Twenty healthy women were evaluated in two sessions (1 week apart) by the same examiner. Mechanical detection threshold (MDT), mechanical pain threshold (MPT), wind-up ratio (WUR) and pressure pain threshold (PPT) were assessed on the skin overlying the anterior temporalis, masseter and TMJ of the dominant side. CPM was tested by comparing PPT before and during the hand immersion in a hot water bath. anova and intra-class correlation coefficients (ICCs) were applied to the data (α = 5%). The overall ICCs showed acceptable values for the test-retest reliability of mechanical somatosensory assessment of masticatory structures. The ICC values of 75% of all quantitative sensory measurements were considered fair to excellent (fair = 8·4%, good = 33·3% and excellent = 33·3%). However, the CPM paradigm presented poor reliability (ICC = 0·25). The mechanical somatosensory assessment of the masticatory structures, but not the proposed CPM protocol, can be considered sufficiently reliable over time to evaluate the trigeminal sensory function. © 2016 John Wiley & Sons Ltd.

Development of an external ceramic insulation for the space shuttle orbiter. Part 2: Optimization

NASA Technical Reports Server (NTRS)

Tanzilli, R. A. (Editor)

1973-01-01

The basic insulation improvement study concentrated upon evaluating variables which could result in significant near-term gains in mechanical behavior and insulation effectiveness of the baseline system. The approaches undertaken included: evaluation of small diameter fibers, optimization of binder: slurry characteristics, evaluation of techniques for controlling fiber orientation, optimization of firing cycle, and the evaluation of methods for improving insulation efficiency. A detailed discussion of these basic insulation improvement studies is presented.

Effects of mechanical stimulation on the reprogramming of somatic cells into human-induced pluripotent stem cells.

PubMed

Kim, Young Mi; Kang, Yun Gyeong; Park, So Hee; Han, Myung-Kwan; Kim, Jae Ho; Shin, Ji Won; Shin, Jung-Woog

2017-06-08

Mechanical stimuli play important roles in the proliferation and differentiation of adult stem cells. However, few studies on their effects on induced pluripotent stem cells (iPSCs) have been published. Human dermal fibroblasts were seeded onto flexible membrane-bottom plates, and infected with retrovirus expressing the four reprogramming factors OCT4, SOX2, KLF, and c-MYC (OSKM). The cells were subjected to equiaxial stretching (3% or 8% for 2, 4, or 7 days) and seeded on feeder cells (STO). The reprogramming into iPSCs was evaluated by the expression of pluripotent markers, in vitro differentiation into three germ layers, and teratoma formation. Equiaxial stretching enhanced reprogramming efficiency without affecting the viral transduction rate. iPSCs induced by transduction of four reprogramming factors and application of equiaxial stretching had characteristics typical of iPSCs in terms of pluripotency and differentiation potentials. This is the first study to show that mechanical stimuli can increase reprogramming efficiency. However, it did not enhance the infection rate, indicating that mechanical stimuli, defined as stretching in this study, have positive effects on reprogramming rather than on infection. Additional studies should evaluate the mechanism underlying the modulation of reprogramming of somatic cells into iPSCs.

Interfacial Micromechanics in Fibrous Composites: Design, Evaluation, and Models

PubMed Central

Lei, Zhenkun; Li, Xuan; Qin, Fuyong; Qiu, Wei

2014-01-01

Recent advances of interfacial micromechanics in fiber reinforced composites using micro-Raman spectroscopy are given. The faced mechanical problems for interface design in fibrous composites are elaborated from three optimization ways: material, interface, and computation. Some reasons are depicted that the interfacial evaluation methods are difficult to guarantee the integrity, repeatability, and consistency. Micro-Raman study on the fiber interface failure behavior and the main interface mechanical problems in fibrous composites are summarized, including interfacial stress transfer, strength criterion of interface debonding and failure, fiber bridging, frictional slip, slip transition, and friction reloading. The theoretical models of above interface mechanical problems are given. PMID:24977189

Mechanical Performance Evaluation of Self-Compacting Concrete with Fine and Coarse Recycled Aggregates from the Precast Industry.

PubMed

Santos, Sara A; da Silva, Pedro R; de Brito, Jorge

2017-08-04

This paper intends to evaluate the feasibility of reintroducing recycled concrete aggregates in the precast industry. The mechanical properties of self-compacting concrete (SCC) with incorporation of recycled aggregates (RA) (coarse recycled aggregates (CRA) and fine recycled aggregates (FRA)) from crushed precast elements were evaluated. The goal was to evaluate the ability of producing SCC with a minimum pre-established performance in terms of mechanical strength, incorporating variable ratios of RA (FRA/CRA%: 0/0%, 25/25%, 50/50%, 0/100% and 100/0%) produced from precast source concretes with similar target performances. This replication in SCC was made for two strength classes (45 MPa and 65 MPa), with the intention of obtaining as final result concrete with recycled aggregates whose characteristics are compatible with those of a SCC with natural aggregates in terms of workability and mechanical strength. The results enabled conclusions to be established regarding the SCC's produced with fine and coarse recycled aggregates from the precast industry, based on its mechanical properties. The properties studied are strongly affected by the type and content of recycled aggregates. The potential demonstrated, mainly in the hardened state, by the joint use of fine and coarse recycled aggregate is emphasized.

Mechanical Performance Evaluation of Self-Compacting Concrete with Fine and Coarse Recycled Aggregates from the Precast Industry

PubMed Central

Santos, Sara A.; da Silva, Pedro R.; de Brito, Jorge

2017-01-01

This paper intends to evaluate the feasibility of reintroducing recycled concrete aggregates in the precast industry. The mechanical properties of self-compacting concrete (SCC) with incorporation of recycled aggregates (RA) (coarse recycled aggregates (CRA) and fine recycled aggregates (FRA)) from crushed precast elements were evaluated. The goal was to evaluate the ability of producing SCC with a minimum pre-established performance in terms of mechanical strength, incorporating variable ratios of RA (FRA/CRA%: 0/0%, 25/25%, 50/50%, 0/100% and 100/0%) produced from precast source concretes with similar target performances. This replication in SCC was made for two strength classes (45 MPa and 65 MPa), with the intention of obtaining as final result concrete with recycled aggregates whose characteristics are compatible with those of a SCC with natural aggregates in terms of workability and mechanical strength. The results enabled conclusions to be established regarding the SCC’s produced with fine and coarse recycled aggregates from the precast industry, based on its mechanical properties. The properties studied are strongly affected by the type and content of recycled aggregates. The potential demonstrated, mainly in the hardened state, by the joint use of fine and coarse recycled aggregate is emphasized. PMID:28777316

Decellularization of Human Internal Mammary Artery: Biomechanical Properties and Histopathological Evaluation.

PubMed

Kajbafzadeh, Abdol-Mohammad; Khorramirouz, Reza; Kameli, Seyede Maryam; Hashemi, Javad; Bagheri, Amin

2017-01-01

This study undertook to create small-diameter vascular grafts and assess their structure and mechanical properties to withstand arterial implantation. Twenty samples of intact human internal mammary arteries (IMAs) were collected and decellularized using detergent-based methods. To evaluate residual cellular and extracellular matrix (ECM) components, histological analysis was performed. Moreover, collagen typing and ECM structure were analyzed by Picrosirius red and Movat's pentachrome staining. Scanning electron microscopy was also applied to assess microarchitecture of both endothelial and adventitial surfaces of native and decellularized arterial samples. Furthermore, mechanical tests were performed to evaluate the rigidity and suture strength of the arteries. Human IMAs were completely decellularized in all three segments (proximal, middle, and distal). ECM proteins such as collagen and elastic fibers were efficiently preserved and no structural distortion in intima, media, and adventitial surfaces was observed. The parameters of the mechanical tests revealed no significant differences in the mechanical properties of decellularized arteries in comparison to native arteries with considerable strength, suture retention, and stress relaxation (Young's modulus [MPa] = 0.22 ± 0.023 [native] and 0.22 ± 0.015 [acellular]; and suture strength 0.56 ± 0.19 [native] vs. 0.56 ± 0.12 [acellular], respectively). Decellularized IMA represents a potential arterial scaffold as an alternative to autologous grafts for future arterial bypass surgeries. By this technique, microarchitecture and mechanical integrity of decellularized arteries were considerably similar to native arteries. The goal of this study was to introduce an efficient method for complete decellularization of human IMA and evaluate the ECM and biomechanical properties.

Dynamic MRI to quantify musculoskeletal motion: A systematic review of concurrent validity and reliability, and perspectives for evaluation of musculoskeletal disorders.

PubMed

Borotikar, Bhushan; Lempereur, Mathieu; Lelievre, Mathieu; Burdin, Valérie; Ben Salem, Douraied; Brochard, Sylvain

2017-01-01

To report evidence for the concurrent validity and reliability of dynamic MRI techniques to evaluate in vivo joint and muscle mechanics, and to propose recommendations for their use in the assessment of normal and impaired musculoskeletal function. The search was conducted on articles published in Web of science, PubMed, Scopus, Academic search Premier, and Cochrane Library between 1990 and August 2017. Studies that reported the concurrent validity and/or reliability of dynamic MRI techniques for in vivo evaluation of joint or muscle mechanics were included after assessment by two independent reviewers. Selected articles were assessed using an adapted quality assessment tool and a data extraction process. Results for concurrent validity and reliability were categorized as poor, moderate, or excellent. Twenty articles fulfilled the inclusion criteria with a mean quality assessment score of 66% (±10.4%). Concurrent validity and/or reliability of eight dynamic MRI techniques were reported, with the knee being the most evaluated joint (seven studies). Moderate to excellent concurrent validity and reliability were reported for seven out of eight dynamic MRI techniques. Cine phase contrast and real-time MRI appeared to be the most valid and reliable techniques to evaluate joint motion, and spin tag for muscle motion. Dynamic MRI techniques are promising for the in vivo evaluation of musculoskeletal mechanics; however results should be evaluated with caution since validity and reliability have not been determined for all joints and muscles, nor for many pathological conditions.

A finite element evaluation of mechanical function for 3 distal extension partial dental prosthesis designs with a 3-dimensional nonlinear method for modeling soft tissue.

PubMed

Nakamura, Yoshinori; Kanbara, Ryo; Ochiai, Kent T; Tanaka, Yoshinobu

2014-10-01

The mechanical evaluation of the function of partial removable dental prostheses with 3-dimensional finite element modeling requires the accurate assessment and incorporation of soft tissue behavior. The differential behaviors of the residual ridge mucosa and periodontal ligament tissues have been shown to exhibit nonlinear displacement. The mathematic incorporation of known values simulating nonlinear soft tissue behavior has not been investigated previously via 3-dimensional finite element modeling evaluation to demonstrate the effect of prosthesis design on the supporting tissues. The purpose of this comparative study was to evaluate the functional differences of 3 different partial removable dental prosthesis designs with 3-dimensional finite element analysis modeling and a simulated patient model incorporating known viscoelastic, nonlinear soft tissue properties. Three different designs of distal extension removable partial dental prostheses were analyzed. The stress distributions to the supporting abutments and soft tissue displacements of the designs tested were calculated and mechanically compared. Among the 3 dental designs evaluated, the RPI prosthesis demonstrated the lowest stress concentrations on the tissue supporting the tooth abutment and also provided wide mucosa-borne areas of support, thereby demonstrating a mechanical advantage and efficacy over the other designs evaluated. The data and results obtained from this study confirmed that the functional behavior of partial dental prostheses with supporting abutments and soft tissues are consistent with the conventional theories of design and clinical experience. The validity and usefulness of this testing method for future applications and testing protocols are shown. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Mechanical and bond strength properties of light-cured and chemically cured glass ionomer cements.

PubMed

McCarthy, M F; Hondrum, S O

1994-02-01

The purpose of this study was to evaluate the mechanical and bond strength properties of a commercially available light-cured glass ionomer cement and of a chemically cured glass ionomer cement. Sixty recently extracted human molars were randomly divided into six equal groups, and the bond strengths of the two cement types were evaluated at 1 hour, 24 hours, and 7 days. Stainless steel lingual buttons were bonded to prepared enamel surfaces, and the samples were placed in a water bath at 37 degrees C until testing. The shear bond strength of each sample was determined with a universal testing instrument. The mechanical strength properties of the two cements were then evaluated. The transverse flexural strength, compressive strength, rigidity, and diametral tensile strength were tested for each cement at 1 hour, 24 hours, and 7 days. The results of the mechanical property strength tests were then compared with the results of the bond strength tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanical Behaviour of 3D Multi-layer Braided Composites: Experimental, Numerical and Theoretical Study

NASA Astrophysics Data System (ADS)

Deng, Jian; Zhou, Guangming; Ji, Le; Wang, Xiaopei

2017-12-01

Mechanical properties and failure mechanisms of a newly designed 3D multi-layer braided composites are evaluated by experimental, numerical and theoretical studies. The microstructure of the composites is introduced. The unit cell technique is employed to address the periodic arrangement of the structure. The volume averaging method is used in theoretical solutions while FEM with reasonable periodic boundary conditions and meshing technique in numerical simulations. Experimental studies are also conducted to verify the feasibility of the proposed models. Predicted elastic properties agree well with the experimental data, indicating the feasibility of the proposed models. Numerical evaluation is more accurate than theoretical assessment. Deformations and stress distributions of the unit cell under tension shows displacement and traction continuity, guaranteeing the rationality of the applied periodic boundary conditions. Although compression and tension modulus are close, the compressive strength only reaches 70% of the tension strength. This indicates that the composites can be weakened in compressive loading. Additionally, by analysing the micrograph of fracture faces and strain-stress curves, a brittle failure mechanism is observed both in composites under tension and compression.

Quality of Protection Evaluation of Security Mechanisms

PubMed Central

Ksiezopolski, Bogdan; Zurek, Tomasz; Mokkas, Michail

2014-01-01

Recent research indicates that during the design of teleinformatic system the tradeoff between the systems performance and the system protection should be made. The traditional approach assumes that the best way is to apply the strongest possible security measures. Unfortunately, the overestimation of security measures can lead to the unreasonable increase of system load. This is especially important in multimedia systems where the performance has critical character. In many cases determination of the required level of protection and adjustment of some security measures to these requirements increase system efficiency. Such an approach is achieved by means of the quality of protection models where the security measures are evaluated according to their influence on the system security. In the paper, we propose a model for QoP evaluation of security mechanisms. Owing to this model, one can quantify the influence of particular security mechanisms on ensuring security attributes. The methodology of our model preparation is described and based on it the case study analysis is presented. We support our method by the tool where the models can be defined and QoP evaluation can be performed. Finally, we have modelled TLS cryptographic protocol and presented the QoP security mechanisms evaluation for the selected versions of this protocol. PMID:25136683

Child Routines and Self-Regulation Serially Mediate Parenting Practices and Externalizing Problems in Preschool Children

ERIC Educational Resources Information Center

Bater, Lovina Rose; Jordan, Sara Sytsma

2017-01-01

Background: Studies clearly indicate that parenting practices relate to child externalizing behaviors, although the mechanisms underlying this relation are less well understood. There has been limited evaluation of child routines and self-regulation in relation to these variables, and no known studies have evaluated all of these variables…

Fatigue behavior of a cross-ply ceramic matrix composite at elevated temperature under tension-tension loading. Master`s thesis

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

Steiner, C.D.

This study investigated the fatigue behavior and damage mechanisms of a (0/90)4s SiC/MAS ceramic matrix composite under tension-tension loading at two elevated temperatures and two frequencies. Stress and strain hystereses, maximum and minimum strain, and modulus of elasticity were evaluated to characterize the material behavior. Microscopy and fractography were used to evaluate damage progression and mechanisms. Fatigue life was independent of frequency at both temperatures.

STABILIZATION OF LEAD-BASED PAINT WASTE

EPA Science Inventory

This study evaluated the ability of a cementitious stabilizing agent to reduce leachable lead from lead-based paint waste removed from substrate via blasting, and to evaluate the mechanism by which the reduction occurs. Testing demonstrated that the representative cementitious ag...

A feasibility study on the design and walking operation of a biped locomotor via dynamic simulation

NASA Astrophysics Data System (ADS)

Wang, Mingfeng; Ceccarelli, Marco; Carbone, Giuseppe

2016-06-01

A feasibility study on the mechanical design and walking operation of a Cassino biped locomotor is presented in this paper. The biped locomotor consists of two identical 3 degrees-of-freedom tripod leg mechanisms with a parallel manipulator architecture. Planning of the biped walking gait is performed by coordinating the motions of the two leg mechanisms and waist. A threedimensional model is elaborated in SolidWorks® environment in order to characterize a feasible mechanical design. Dynamic simulation is carried out in MSC.ADAMS® environment with the aims of characterizing and evaluating the dynamic walking performance of the proposed design. Simulation results show that the proposed biped locomotor with proper input motions of linear actuators performs practical and feasible walking on flat surfaces with limited actuation and reaction forces between its feet and the ground. A preliminary prototype of the biped locomotor is built for the purpose of evaluating the operation performance of the biped walking gait of the proposed locomotor.

Evaluation of glass transition temperature and dynamic mechanical properties of autopolymerized hard direct denture reline resins.

PubMed

Takase, Kazuma; Watanabe, Ikuya; Kurogi, Tadafumi; Murata, Hiroshi

2015-01-01

This study assessed methods for evaluation of glass transition temperature (Tg) of autopolymerized hard direct denture reline resins using dynamic mechanical analysis and differential scanning calorimetry in addition to the dynamic mechanical properties. The Tg values of 3 different reline resins were determined using a dynamic viscoelastometer and differential scanning calorimeter, and rheological parameters were also determined. Although all materials exhibited higher storage modulus and loss modulus values, and a lower loss tangent at 37˚C with a higher frequency, the frequency dependence was not large. Tg values obtained by dynamic mechanical analysis were higher than those by differential scanning calorimetry and higher frequency led to higher Tg, while more stable Tg values were also obtained by that method. These results suggest that dynamic mechanical analysis is more advantageous for characterization of autopolymerized hard direct denture reline resins than differential scanning calorimetry.

An adaptive quantum mechanics/molecular mechanics method for the infrared spectrum of water: incorporation of the quantum effect between solute and solvent.

PubMed

Watanabe, Hiroshi C; Banno, Misa; Sakurai, Minoru

2016-03-14

Quantum effects in solute-solvent interactions, such as the many-body effect and the dipole-induced dipole, are known to be critical factors influencing the infrared spectra of species in the liquid phase. For accurate spectrum evaluation, the surrounding solvent molecules, in addition to the solute of interest, should be treated using a quantum mechanical method. However, conventional quantum mechanics/molecular mechanics (QM/MM) methods cannot handle free QM solvent molecules during molecular dynamics (MD) simulation because of the diffusion problem. To deal with this problem, we have previously proposed an adaptive QM/MM "size-consistent multipartitioning (SCMP) method". In the present study, as the first application of the SCMP method, we demonstrate the reproduction of the infrared spectrum of liquid-phase water, and evaluate the quantum effect in comparison with conventional QM/MM simulations.

Evaluation of Polycaprolactone Scaffold with Basic Fibroblast Growth Factor and Fibroblasts in an Athymic Rat Model for Anterior Cruciate Ligament Reconstruction

PubMed Central

Kabir, Nima; Arshi, Armin; Nazemi, Azadeh; Wu, Ben; Petrigliano, Frank A.; McAllister, David R.

2015-01-01

Anterior cruciate ligament (ACL) rupture is a common ligamentous injury often necessitating surgery. Current surgical treatment options include ligament reconstruction with autograft or allograft, which have their inherent limitations. Thus, there is interest in a tissue-engineered substitute for use in ACL regeneration. However, there have been relatively few in vivo studies to date. In this study, an athymic rat model of ACL reconstruction was used to evaluate electrospun polycaprolactone (PCL) grafts, with and without the addition of basic fibroblast growth factor (bFGF) and human foreskin fibroblasts. We examined the regenerative potential of tissue-engineered ACL grafts using histology, immunohistochemistry, and mechanical testing up to 16 weeks postoperatively. Histology showed infiltration of the grafts with cells, and immunohistochemistry demonstrated aligned collagen deposition with minimal inflammatory reaction. Mechanical testing of the grafts demonstrated significantly higher mechanical properties than immediately postimplantation. Acellular grafts loaded with bFGF achieved 58.8% of the stiffness and 40.7% of the peak load of healthy native ACL. Grafts without bFGF achieved 31.3% of the stiffness and 28.2% of the peak load of healthy native ACL. In this in vivo rodent model study for ACL reconstruction, the histological and mechanical evaluation demonstrated excellent healing and regenerative potential of our electrospun PCL ligament graft. PMID:25744933

The Fire and Fire Surrogates Study: Providing guidelines for fire in future forest watershed management decisions

Treesearch

Carleton B. Edminster; C. Phillip Weatherspoon; Daniel G. Neary

2000-01-01

As part of the 1998 Joint USDA/USDI Fire Science Program, the Fire and Fire Surrogates Study was proposed to establish and evaluate cross-comparisons of fuels treatment practices and techniques to reduce wildfire risk. This study evaluates prescribed fire, thinning, and various mechanical treatment methods for treating, removing, or using woody biomass. Site-specific...

Ecological effects of alternative fuel-reduction treatments: highlights of the National Fire and Fire Surrogate study (FFS)

Treesearch

James D. McIver; Scott L. Stephens; James K. Agee; Jamie Barbour; Ralph E. J. Boerner; Carl B. Edminster; Karen L. Erickson; Kerry L. Farris; Christopher J. Fettig; Carl E. Fiedler; Sally Haase; Stephen C. Hart; Jon E. Keeley; Eric E. Knapp; John F. Lehmkuhl; Jason J. Moghaddas; William Otrosina; Kenneth W. Outcalt; Dylan W. Schwilk; Carl N. Skinner; Thomas A. Waldrop; C. Phillip Weatherspoon; Daniel A. Yaussy; Andrew Youngblood; Steve Zack

2012-01-01

The 12-site National Fire and Fire Surrogate study (FFS) was a multivariate experiment that evaluated ecological consequences of alternative fuel-reduction treatments in seasonally dry forests of the US. Each site was a replicated experiment with a common design that compared an un-manipulated control, prescribed fire, mechanical and mechanical + fire treatments....

Alabama's Foundation Program: An Adequate and Equitable School Funding Mechanism?

ERIC Educational Resources Information Center

Coe, Dennis Randal

2016-01-01

The purpose of this study was to determine the extent to which the foundation program was an adequate and equitable funding mechanism for public schools in the state of Alabama. This study analyzed funding and academic data and evaluated adequacy and equity through the lenses of poverty, geographic location, local tax effort, and type of school…

Contrasting motivational orientation and evaluative coding accounts: on the need to differentiate the effectors of approach/avoidance responses.

PubMed

Kozlik, Julia; Neumann, Roland; Lozo, Ljubica

2015-01-01

Several emotion theorists suggest that valenced stimuli automatically trigger motivational orientations and thereby facilitate corresponding behavior. Positive stimuli were thought to activate approach motivational circuits which in turn primed approach-related behavioral tendencies whereas negative stimuli were supposed to activate avoidance motivational circuits so that avoidance-related behavioral tendencies were primed (motivational orientation account). However, recent research suggests that typically observed affective stimulus-response compatibility phenomena might be entirely explained in terms of theories accounting for mechanisms of general action control instead of assuming motivational orientations to mediate the effects (evaluative coding account). In what follows, we explore to what extent this notion is applicable. We present literature suggesting that evaluative coding mechanisms indeed influence a wide variety of affective stimulus-response compatibility phenomena. However, the evaluative coding account does not seem to be sufficient to explain affective S-R compatibility effects. Instead, several studies provide clear evidence in favor of the motivational orientation account that seems to operate independently of evaluative coding mechanisms. Implications for theoretical developments and future research designs are discussed.

Contrasting motivational orientation and evaluative coding accounts: on the need to differentiate the effectors of approach/avoidance responses

PubMed Central

Kozlik, Julia; Neumann, Roland; Lozo, Ljubica

2015-01-01

Several emotion theorists suggest that valenced stimuli automatically trigger motivational orientations and thereby facilitate corresponding behavior. Positive stimuli were thought to activate approach motivational circuits which in turn primed approach-related behavioral tendencies whereas negative stimuli were supposed to activate avoidance motivational circuits so that avoidance-related behavioral tendencies were primed (motivational orientation account). However, recent research suggests that typically observed affective stimulus–response compatibility phenomena might be entirely explained in terms of theories accounting for mechanisms of general action control instead of assuming motivational orientations to mediate the effects (evaluative coding account). In what follows, we explore to what extent this notion is applicable. We present literature suggesting that evaluative coding mechanisms indeed influence a wide variety of affective stimulus–response compatibility phenomena. However, the evaluative coding account does not seem to be sufficient to explain affective S–R compatibility effects. Instead, several studies provide clear evidence in favor of the motivational orientation account that seems to operate independently of evaluative coding mechanisms. Implications for theoretical developments and future research designs are discussed. PMID:25983718

Sprint mechanics return to competition follow-up after hamstring injury on a professional soccer player: A case study with an inertial sensor unit based methodological approach.

PubMed

Setuain, Igor; Lecumberri, Pablo; Izquierdo, Mikel

2017-10-03

The present research aimed to describe an inertial unit (IU)-based sprint mechanics evaluation model for assessing players' readiness to return to competition after suffering a grade I hamstring injury. A professional male football player (age 19years; height 177cm; weight 70kg, midfielder, Spanish, 3° Division) with a grade 1 biceps femoris injury was evaluated at pre-season, at return to play after injury and at the end of the competitive season. Sprint mechanics were analyzed via the use of an inertial orientation tracker (Xsens Technologies B.V. Enschede, Netherlands) attached over the L3-L4 region of the subject's lumbar spine. Sprint mechanics such as horizontal components of ground reaction force were assessed in both legs during sprinting actions. Findings and interpretation: Both the coefficient of the horizontal force application (SFV) and the ratio of forces (DRF) applied at increasing velocity were decreased in the injured limb compared with the contralateral healthy limb at the return to play evaluation (73% and 76% reductions, respectively) and returned to symmetrical levels at the end-season evaluation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanisms of deterioration of nutrients. [retention of flavor during freeze drying

NASA Technical Reports Server (NTRS)

Karel, M.; Flink, J. M.

1975-01-01

The retention of flavor during freeze drying was studied with model systems. Mechanisms by which flavor retention phenomena is explained were developed and process conditions specified so that flavor retention is optimized. The literature is reviewed and results of studies of the flavor retention behavior of a number of real food products, including both liquid and solid foods are evaluated. Process parameters predicted by the mechanisms to be of greatest significance are freezing rate, initial solids content, and conditions which result in maintenance of sample structure. Flavor quality for the real food showed the same behavior relative to process conditions as predicted by the mechanisms based on model system studies.

Activity profiles of 309 ToxCast™ chemicals evaluated across 292 biochemical targets

EPA Science Inventory

Understanding the potential health risks posed by environmental chemicals is a significant challenge elevated by the large number of diverse chemicals with generally uncharacterized exposures, mechanisms, and toxicities. The present study is a performance evaluation and critical ...

Quantum mechanical calculations related to ionization and charge transfer in DNA

NASA Astrophysics Data System (ADS)

Cauët, E.; Valiev, M.; Weare, J. H.; Liévin, J.

2012-07-01

Ionization and charge migration in DNA play crucial roles in mechanisms of DNA damage caused by ionizing radiation, oxidizing agents and photo-irradiation. Therefore, an evaluation of the ionization properties of the DNA bases is central to the full interpretation and understanding of the elementary reactive processes that occur at the molecular level during the initial exposure and afterwards. Ab initio quantum mechanical (QM) methods have been successful in providing highly accurate evaluations of key parameters, such as ionization energies (IE) of DNA bases. Hence, in this study, we performed high-level QM calculations to characterize the molecular energy levels and potential energy surfaces, which shed light on ionization and charge migration between DNA bases. In particular, we examined the IEs of guanine, the most easily oxidized base, isolated and embedded in base clusters, and investigated the mechanism of charge migration over two and three stacked guanines. The IE of guanine in the human telomere sequence has also been evaluated. We report a simple molecular orbital analysis to explain how modifications in the base sequence are expected to change the efficiency of the sequence as a hole trap. Finally, the application of a hybrid approach combining quantum mechanics with molecular mechanics brings an interesting discussion as to how the native aqueous DNA environment affects the IE threshold of nucleobases.

Neuroimaging studies of practice-related change: fMRI and meta-analytic evidence of a domain-general control network for learning.

PubMed

Chein, Jason M; Schneider, Walter

2005-12-01

Functional magnetic resonance imaging and a meta-analysis of prior neuroimaging studies were used to characterize cortical changes resulting from extensive practice and to evaluate a dual-processing account of the neural mechanisms underlying human learning. Three core predictions of the dual processing theory are evaluated: 1) that practice elicits generalized reductions in regional activity by reducing the load on the cognitive control mechanisms that scaffold early learning; 2) that these control mechanisms are domain-general; and 3) that no separate processing pathway emerges as skill develops. To evaluate these predictions, a meta-analysis of prior neuroimaging studies and a within-subjects fMRI experiment contrasting unpracticed to practiced performance in a paired-associate task were conducted. The principal effect of practice was found to be a reduction in the extent and magnitude of activity in a cortical network spanning bilateral dorsal prefrontal, left ventral prefrontal, medial frontal (anterior cingulate), left insular, bilateral parietal, and occipito-temporal (fusiform) areas. These activity reductions are shown to occur in common regions across prior neuroimaging studies and for both verbal and nonverbal paired-associate learning in the present fMRI experiment. The implicated network of brain regions is interpreted as a domain-general system engaged specifically to support novice, but not practiced, performance.

The effect of helium-oxygen-assisted mechanical ventilation on chronic obstructive pulmonary disease exacerbation: A systemic review and meta-analysis.

PubMed

Wu, Xu; Shao, Chuan; Zhang, Liang; Tu, Jinjing; Xu, Hui; Lin, Zhihui; Xu, Shuguang; Yu, Biyun; Tang, Yaodong; Li, Shanqun

2018-03-01

Chronic obstructive pulmonary disease (COPD) is often accompanied by acute exacerbations. Patients of COPD exacerbation suffering from respiratory failure often need the support of mechanical ventilation. Helium-oxygen can be used to reduce airway resistance during mechanical ventilation. The aim of this study is to evaluate the effect of helium-oxygen-assisted mechanical ventilation on COPD exacerbation through a meta-analysis. A comprehensive literature search through databases of Pub Med (1966∼2016), Ovid MEDLINE (1965∼2016), Cochrane EBM (1991∼2016), EMBASE (1974∼2016) and Ovid MEDLINE was performed to identify associated studies. Randomized clinical trials met our inclusion criteria that focus on helium-oxygen-assisted mechanical ventilation on COPD exacerbation were included. The quality of the papers was evaluated after inclusion and information was extracted for meta-analysis. Six articles and 392 patients were included in total. Meta-analysis revealed that helium-oxygen-assisted mechanical ventilation reduced Borg dyspnea scale and increased arterial PH compared with air-oxygen. No statistically significant difference was observed between helium-oxygen and air-oxygen as regards to WOB, PaCO 2 , OI, tracheal intubation rates and mortality within hospital. Our study suggests helium-oxygen-assisted mechanical ventilation can help to reduce Borg dyspnea scale. In terms of the tiny change of PH, its clinical benefit is negligible. There is no conclusive evidence indicating the beneficial effect of helium-oxygen-assisted mechanical ventilation on clinical outcomes or prognosis of COPD exacerbation. © 2017 John Wiley & Sons Ltd.

Nondestructive evaluation of hydrogel mechanical properties using ultrasound

PubMed Central

Walker, Jason M.; Myers, Ashley M.; Schluchter, Mark D.; Goldberg, Victor M.; Caplan, Arnold I.; Berilla, Jim A.; Mansour, Joseph M.; Welter, Jean F.

2012-01-01

The feasibility of using ultrasound technology as a noninvasive, nondestructive method for evaluating the mechanical properties of engineered weight-bearing tissues was evaluated. A fixture was designed to accurately and reproducibly position the ultrasound transducer normal to the test sample surface. Agarose hydrogels were used as phantoms for cartilage to explore the feasibility of establishing correlations between ultrasound measurements and commonly used mechanical tissue assessments. The hydrogels were fabricated in 1–10% concentrations with a 2–10 mm thickness. For each concentration and thickness, six samples were created, for a total of 216 gel samples. Speed of sound was determined from the time difference between peak reflections and the known height of each sample. Modulus was computed from the speed of sound using elastic and poroelastic models. All ultrasonic measurements were made using a 15 MHz ultrasound transducer. The elastic modulus was also determined for each sample from a mechanical unconfined compression test. Analytical comparison and statistical analysis of ultrasound and mechanical testing data was carried out. A correlation between estimates of compressive modulus from ultrasonic and mechanical measurements was found, but the correlation depended on the model used to estimate the modulus from ultrasonic measurements. A stronger correlation with mechanical measurements was found using the poroelastic rather than the elastic model. Results from this preliminary testing will be used to guide further studies of native and engineered cartilage. PMID:21773854

"Gear mechanism" of bariatric interventions revealed by untargeted metabolomics.

PubMed

Samczuk, Paulina; Luba, Magdalena; Godzien, Joanna; Mastrangelo, Annalaura; Hady, Hady Razak; Dadan, Jacek; Barbas, Coral; Gorska, Maria; Kretowski, Adam; Ciborowski, Michal

2018-03-20

Mechanisms responsible for metabolic gains after bariatric surgery are not entirely clear. The purpose of this study was evaluation of metabolic changes after laparoscopic Roux-en-Y gastric bypass or laparoscopic sleeve gastrectomy in semi-annual follow up. The study participants were selected from obese patients with T2DM who underwent one of the mentioned bariatric procedures. Serum metabolic fingerprinting by use of liquid and gas chromatography with mass spectrometry detection was performed on samples obtained from studied patients before, one, and six months post-surgery. Performed analyses resulted in 49 significant and identified metabolites. Comparison of the two described procedures has allowed to detect metabolites linked with numerous pathways, processes and diseases. Based on the metabolites detected and pathways affected, we propose a "gear mechanism" showing molecular changes evoked by both bariatric procedures. Critical evaluation of clinical data and obtained metabolomics results enables us to conclude that both procedures are very similar in terms of general clinical outcome, but they strongly differ from each other in molecular mechanisms leading to the final effect. For the first time general metabolic effect of bariatric procedures is described. New hypotheses concerning molecular mechanisms induced by bariatric surgeries and new gut microbiota modulations are presented. Copyright © 2018 Elsevier B.V. All rights reserved.

Cyanoacrylate medical glue application in intervertebral disc annulus defect repair: Mechanical and biocompatible evaluation.

PubMed

Kang, Ran; Li, Haisheng; Lysdahl, Helle; Quang Svend Le, Dang; Chen, Menglin; Xie, Lin; Bünger, Cody

2017-01-01

In an attempt to find an ideal closure method during annulus defect repair, we evaluate the use of medical glue by mechanical and biocompatible test. Cyanoacrylate medical glue was applied together with a multilayer microfiber/nanofiber polycaprolactone scaffold and suture in annulus repair. Continuous axial loading and fatigue mechanical test was performed. Furthermore, the in vitro response of mesenchymal stem cell (MSC) to the glue was evaluated by cell viability assay. The in vivo response of annulus tissue to the glue and scaffold was also studied in porcine lumbar spine; histological sections were evaluated after 3 months. Cyanoacrylate glue significantly improved the closure effect in the experimental group with failure load 2825.7 ± 941.6 N, compared to 774.1 ± 281.3 N in the control group without glue application (p < 0.01). The experimental group also withstood the fatigue test. No toxic effect was observed by in vitro cell culture and in vivo implantation. On the basis of this initial evaluation, the use of cyanoacrylate medical glue improves closure effect with no toxicity in annulus defect repair. This method of annulus repair merits further effectiveness study in vivo. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 14-20, 2017. © 2015 Wiley Periodicals, Inc.

Assessment and Evaluation of National Human Resource Development System Competitiveness in Emerging Countries

ERIC Educational Resources Information Center

Oh, HunSeok; Seo, DongIn; Kim, JuSeuk; Yoo, SangOk; Seong, HeeChang

2015-01-01

This study assessed and evaluated the competitiveness of national human resource development (NHRD) systems in emerging countries with potential for growth. The literature on emerging countries and NHRD systems was reviewed. The study developed a model mechanism with forty-one indices and nine sub-components for the NHRD system assessment in…

Decision-making and evaluation of science causal claims: Effects of goals on uses of evidence and explanatory mechanism

NASA Astrophysics Data System (ADS)

Wong, Jacqueline Yin Sang

2015-10-01

Evidence and explanatory mechanism are central to scientific practices. Using such information could also inform decisions about issues in which science can play some role, from policy issues like climate change to personal issues like vaccination. While research suggests that people tend to focus on non-science considerations when making science-related decisions, there is also evidence that people can reason very productively with evidence and mechanism. This study examines how the goals participants pursue when reading a science report influences how they attend to information about causal mechanism and evidence. Two hundred and seventeen high school students were asked either to evaluate the truth of a scientific claim, to make a personal decision based on the claim, or to make a social policy decision based on the claim using an online task-based survey. All three groups of participants attended to evidence and mechanism, but participants with different goals requested different types of information and were influenced by evidence and mechanism for different reasons. The findings suggest that goals influence how participants use evidence and mechanism.

Models and Mechanisms for Evaluating Government-Funded Research: An International Comparison

ERIC Educational Resources Information Center

Coryn, Chris L. S.; Hattie, John A.; Scriven, Michael; Hartmann, David J.

2007-01-01

This research describes, classifies, and comparatively evaluates national models and mechanisms used to evaluate research and allocate research funding in 16 countries. Although these models and mechanisms vary widely in terms of how research is evaluated and financed, nearly all share the common characteristic of relating funding to some measure…

Powder compression mechanics of spray-dried lactose nanocomposites.

PubMed

Hellrup, Joel; Nordström, Josefina; Mahlin, Denny

2017-02-25

The aim of this study was to investigate the structural impact of the nanofiller incorporation on the powder compression mechanics of spray-dried lactose. The lactose was co-spray-dried with three different nanofillers, that is, cellulose nanocrystals, sodium montmorillonite and fumed silica, which led to lower micron-sized nanocomposite particles with varying structure and morphology. The powder compression mechanics of the nanocomposites and physical mixtures of the neat spray-dried components were evaluated by a rational evaluation method with compression analysis as a tool, using the Kawakita equation and the Shapiro-Konopicky-Heckel equation. Particle rearrangement dominated the initial compression profiles due to the small particle size of the materials. The strong contribution of particle rearrangement in the materials with fumed silica continued throughout the whole compression profile, which prohibited an in-depth material characterization. However, the lactose/cellulose nanocrystals and the lactose/sodium montmorillonite nanocomposites demonstrated high yield pressure compared with the physical mixtures indicating increased particle hardness upon composite formation. This increase has likely to do with a reinforcement of the nanocomposite particles by skeleton formation of the nanoparticles. In summary, the rational evaluation of mechanical properties done by applying powder compression analysis proved to be a valuable tool for mechanical evaluation for this type of spray-dried composite materials, unless they demonstrate particle rearrangement throughout the whole compression profile. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface modification of carbon nanotubes using 3-aminopropyltriethoxysilane to improve mechanical properties of nanocomposite based polymer matrix: Experimental and Density functional theory study

NASA Astrophysics Data System (ADS)

Hamed Mashhadzadeh, A.; Fereidoon, Ab.; Ghorbanzadeh Ahangari, M.

2017-10-01

In current study we combined theoretical and experimental studies to evaluate the effect of functionalization and silanization on mechanical behavior of polymer-based/CNT nanocomposites. Epoxy was selected as thermoset polymer, polypropylene and poly vinyl chloride were selected as thermoplastic polymers. The whole procedure is divided to two sections . At first we applied density functional theory (DFT) to analyze the effect of functionalization on equilibrium distance and adsorption energy of unmodified, functionalized by sbnd OH group and silanized epoxy/CNT, PP/CNT and PVC/CNT nanocomposites and the results showed that functionalization increased adsorption energy and reduced the equilibrium distance in all studied nanocomposites and silanization had higher effect comparing to OH functionalizing. Then we prepared experimental samples of all mentioned nanocomposites and tested their tensile and flexural strength properties. The obtained results showed that functionalization increased the studied mechanical properties in all evaluated nanocomposites. Finally we compared the results of experimental and theoretical sections with each other and estimated a suitable agreement between these parts.

Extended performance electric propulsion power processor design study. Volume 2: Technical summary

NASA Technical Reports Server (NTRS)

Biess, J. J.; Inouye, L. Y.; Schoenfeld, A. D.

1977-01-01

Electric propulsion power processor technology has processed during the past decade to the point that it is considered ready for application. Several power processor design concepts were evaluated and compared. Emphasis was placed on a 30 cm ion thruster power processor with a beam power rating supply of 2.2KW to 10KW for the main propulsion power stage. Extension in power processor performance were defined and were designed in sufficient detail to determine efficiency, component weight, part count, reliability and thermal control. A detail design was performed on a microprocessor as the thyristor power processor controller. A reliability analysis was performed to evaluate the effect of the control electronics redesign. Preliminary electrical design, mechanical design and thermal analysis were performed on a 6KW power transformer for the beam supply. Bi-Mod mechanical, structural and thermal control configurations were evaluated for the power processor and preliminary estimates of mechanical weight were determined.

Dynamic MRI to quantify musculoskeletal motion: A systematic review of concurrent validity and reliability, and perspectives for evaluation of musculoskeletal disorders

PubMed Central

Lempereur, Mathieu; Lelievre, Mathieu; Burdin, Valérie; Ben Salem, Douraied; Brochard, Sylvain

2017-01-01

Purpose To report evidence for the concurrent validity and reliability of dynamic MRI techniques to evaluate in vivo joint and muscle mechanics, and to propose recommendations for their use in the assessment of normal and impaired musculoskeletal function. Materials and methods The search was conducted on articles published in Web of science, PubMed, Scopus, Academic search Premier, and Cochrane Library between 1990 and August 2017. Studies that reported the concurrent validity and/or reliability of dynamic MRI techniques for in vivo evaluation of joint or muscle mechanics were included after assessment by two independent reviewers. Selected articles were assessed using an adapted quality assessment tool and a data extraction process. Results for concurrent validity and reliability were categorized as poor, moderate, or excellent. Results Twenty articles fulfilled the inclusion criteria with a mean quality assessment score of 66% (±10.4%). Concurrent validity and/or reliability of eight dynamic MRI techniques were reported, with the knee being the most evaluated joint (seven studies). Moderate to excellent concurrent validity and reliability were reported for seven out of eight dynamic MRI techniques. Cine phase contrast and real-time MRI appeared to be the most valid and reliable techniques to evaluate joint motion, and spin tag for muscle motion. Conclusion Dynamic MRI techniques are promising for the in vivo evaluation of musculoskeletal mechanics; however results should be evaluated with caution since validity and reliability have not been determined for all joints and muscles, nor for many pathological conditions. PMID:29232401

Evaluation of the Effectiveness of the Integration of a LITEE Case Study for a Freshman Level Mechanical Engineering Course at The University of Toledo

ERIC Educational Resources Information Center

Franchetti, Matthew

2011-01-01

The purpose of this paper is to report the findings of the integration of a manufacturing case study to a freshman level mechanical engineering course at The University of Toledo. The approach to integrate this case study into the class was completed via weekly assignments analyzing the case, small group discussion, and weekly group discussion.…

Proceedings of the ARPA/AFML Review of Progress in Quantitative Nondestructive Evaluation (NDE)

DTIC Science & Technology

1977-09-01

degradation mechanisms. TABLE II. Experimental Methods for Study of Kolsture Effects Part 1: Malattira Dairadatlon Motatura taka up Intarlaalaat ahaar...1) To determine the effects of moisture de- gradation on the mechanical properties of a gra- phlte-epoxy composite under study for use on B-l. 2...a larger degree of reversibility in moisture damage effects . These are early results; further study of these Interesting results are required

A realistic evaluation: the case of protocol-based care

PubMed Central

2010-01-01

Background 'Protocol based care' was envisioned by policy makers as a mechanism for delivering on the service improvement agenda in England. Realistic evaluation is an increasingly popular approach, but few published examples exist, particularly in implementation research. To fill this gap, within this paper we describe the application of a realistic evaluation approach to the study of protocol-based care, whilst sharing findings of relevance about standardising care through the use of protocols, guidelines, and pathways. Methods Situated between positivism and relativism, realistic evaluation is concerned with the identification of underlying causal mechanisms, how they work, and under what conditions. Fundamentally it focuses attention on finding out what works, for whom, how, and in what circumstances. Results In this research, we were interested in understanding the relationships between the type and nature of particular approaches to protocol-based care (mechanisms), within different clinical settings (context), and what impacts this resulted in (outcomes). An evidence review using the principles of realist synthesis resulted in a number of propositions, i.e., context, mechanism, and outcome threads (CMOs). These propositions were then 'tested' through multiple case studies, using multiple methods including non-participant observation, interviews, and document analysis through an iterative analysis process. The initial propositions (conjectured CMOs) only partially corresponded to the findings that emerged during analysis. From the iterative analysis process of scrutinising mechanisms, context, and outcomes we were able to draw out some theoretically generalisable features about what works, for whom, how, and what circumstances in relation to the use of standardised care approaches (refined CMOs). Conclusions As one of the first studies to apply realistic evaluation in implementation research, it was a good fit, particularly given the growing emphasis on understanding how context influences evidence-based practice. The strengths and limitations of the approach are considered, including how to operationalise it and some of the challenges. This approach provided a useful interpretive framework with which to make sense of the multiple factors that were simultaneously at play and being observed through various data sources, and for developing explanatory theory about using standardised care approaches in practice. PMID:20504293

[Non-randomized evaluation studies (TREND)].

PubMed

Vallvé, Carles; Artés, Maite; Cobo, Erik

2005-12-01

Nonrandomized intervention trials are needed when randomized clinical trials cannot be performed. To report the results from nonrandomized intervention studies transparently, the TREND (Transparent Reporting of Evaluations with Nonrandomized Designs) checklist should be used. This implies that nonrandomized studies should follow the remaining methodological tools usually employed in randomized trials and that the uncertainty introduced by the allocation mechanism should be explicitly reported and, if possible, quantified.

Two Maintenance Mechanisms of Verbal Information in Working Memory

ERIC Educational Resources Information Center

Camos, V.; Lagner, P.; Barrouillet, P.

2009-01-01

The present study evaluated the interplay between two mechanisms of maintenance of verbal information in working memory, namely articulatory rehearsal as described in Baddeley's model, and attentional refreshing as postulated in Barrouillet and Camos's Time-Based Resource-Sharing (TBRS) model. In four experiments using complex span paradigm, we…

A National Program for Instructional Development in Veterinary Pathology.

ERIC Educational Resources Information Center

Ward, Billy, C.

1979-01-01

Results of a study by the American College of Veterinary Pathologists to investigate mechanisms to facilitate sharing of audiovisual programs include a content analysis in veterinary pathology, a guidebook for the preparation of instruction, 20 instructional programs, a lesson evaluation mechanism, and a proposal for sharing programs. (JMD)

INHALATION STUDIES OF MT. ST. HELENS VOLCANIC ASH IN ANIMALS: RESPIRATORY MECHANICS, AIRWAY REACTIVITY AND DEPOSITION

EPA Science Inventory

Effects of fine volcanic ash aerosol on pulmonary mechanical properties of awake guinea pigs were evaluated during exposure by inhalation. Ash penetration into the lungs as well as tissue response to ash were determined by transmission electron microscopy. The reactivity of airwa...

Mechanics of Wound Closure: Emerging Tape-Based Wound Closure Technology vs. Traditional Methods.

PubMed

Levi, Kemal; Ichiryu, Kei; Kefel, Pelin; Keller, Juergen; Grice, Jon; Belson, Ori; Storne, Eric; Safa, Bauback

2016-10-12

To date, there is still a lack of understanding of how wound closure methods perform comparatively under daily bodily movement during the course of healing and how they affect the mechanics of healing. The present study is a first step in understanding and objectively quantifying the gap. The study provides both a new method of metrology for noninvasive evaluation of skin mechanics at the onset of wound healing and an emerging tape-based wound closure technology. The latter shows better performance with respect to commonly used staples and sutures, holding the wound intact and providing uniform mechanical support across the incision.

Reinforced chitosan-based heart valve scaffold and utility of bone marrow-derived mesenchymal stem cells for cardiovascular tissue engineering

NASA Astrophysics Data System (ADS)

Albanna, Mohammad Zaki

Recent research has demonstrated a strong correlation between the differentiation profile of mesenchymal stem cells (MSCs) and scaffold stiffness. Chitosan is being widely studied for tissue engineering applications due to its biocompatibility and biodegradability. However, its use in load-bearing applications is limited due to moderate to low mechanical properties. In this study, we investigated the effectiveness of a fiber reinforcement method for enhancing the mechanical properties of chitosan scaffolds. Chitosan fibers were fabricated using a solution extrusion and neutralization method and incorporated into porous chitosan scaffolds. The effects of different fiber/scaffold mass ratios, fiber mechanical properties and fiber lengths on scaffold mechanical properties were studied. The results showed that incorporating fibers improved scaffold strength and stiffness in proportion to the fiber/scaffold mass ratio. A fiber-reinforced heart valve leaflet scaffold achieved strength values comparable to the radial values of human pulmonary and aortic valves. Additionally, the effects of shorter fibers (2 mm) were found to be up to 3-fold greater than longer fibers (10 mm). Despite this reduction in fiber mechanical properties caused by heparin crosslinking, the heparin-modified fibers still improved the mechanical properties of the reinforced scaffolds, but to a lesser extent than the unmodified fibers. The results demonstrate that chitosan fiber-reinforcement can be used to generate tissue-matching mechanical properties in porous chitosan scaffolds and that fiber length and mechanical properties are important parameters in defining the degree of mechanical improvement. We further studied various chemical and physical treatments to improve the mechanical properties of chitosan fibers. With combination of chemical and physical treatments, fiber stiffness improved 40fold compared to unmodified fibers. We also isolated ovine bone marrow-derived MSCs and evaluated their utility for cardiovascular tissue engineering applications. Moreover, we evaluated the effect of various glycosaminoglycans (GAGs) on MSCs morphology and proliferation. Lastly, we studied the effect of stiffness of mechanically improved chitosan fibers on MSCs viability, attachment and proliferation. Results showed that MSCs proliferation improved in proportion to fiber stiffness.

Buildup factor and mechanical properties of high-density cement mixed with crumb rubber and prompt gamma ray study

NASA Astrophysics Data System (ADS)

Aim-O, P.; Wongsawaeng, D.; Tancharakorn, S.; Sophon, M.

2017-09-01

High-density cement mixed with crumb rubber has been studied to be a gamma ray and neutron shielding material, especially for photonuclear reactions that may occur from accelerators where both types of radiation exist. The Buildup factors from gamma ray scattering, prompt and secondary gamma ray emissions from neutron capture and mechanical properties were evaluated. For buildup factor studies, two different geometries were used: narrow beam and broad beam. Prompt Gamma Neutron Activation Analysis (PGNAA) was carried out to determine the prompt and secondary gamma ray emissions. The compressive strength of samples was evaluated by using compression testing machine which was central point loading crushing test. The results revealed that addition of crumb rubber increased the buildup factor. Gamma ray spectra following PGNAA revealed no prompt or secondary gamma ray emission. Mechanical testing indicated that the compressive strength of the shielding material decreased with increasing volume percentage of crumb rubber.

Kinetics of Mechanical Stretch-Induced Nitric Oxide Production in Rat Ventricular Cardiac Myocytes.

PubMed

Shim, A L; Mitrokhin, V M; Gorbacheva, L R; Savinkova, I G; Pustovit, K B; Mladenov, M I; Kamkin, A G

2017-09-01

Discrete mechanical stretch of isolated spontaneously contracting cardiac myocytes was employed to examine the kinetics of NO production in these cells. NO oscillations were detected with fluorescent dye 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate. The mechanisms underlying stretch-induced changes in NO concentration remain unclear and further studies are needed to evaluate the role of NO oscillation in the regulation of cardiomyocyte function.

Evaluation of Basalt Fibre Composites for Marine Applications

NASA Astrophysics Data System (ADS)

Davies, P.; Verbouwe, W.

2018-04-01

Basalt fibres offer potential for use in marine structures, but few data exist to evaluate the influence of seawater immersion on their mechanical behaviour. This paper provides the results from a study in which basalt fibre reinforced epoxy composites were aged in natural seawater at different temperatures. Tests were performed under quasi-static and cyclic loading, first in the as-received state then after saturation in natural seawater. Results are compared to those for an E-glass reinforced composite with the same epoxy matrix. They indicate similar mechanical performance for both materials after seawater saturation.

Estimating Durability of Reinforced Concrete

NASA Astrophysics Data System (ADS)

Varlamov, A. A.; Shapovalov, E. L.; Gavrilov, V. B.

2017-11-01

In this article we propose to use the methods of fracture mechanics to evaluate concrete durability. To evaluate concrete crack resistance characteristics of concrete directly in the structure in order to implement the methods of fracture mechanics, we have developed special methods. Various experimental studies have been carried out to determine the crack resistance characteristics and the concrete modulus of elasticity during its operating. A comparison was carried out for the results obtained with the use of the proposed methods and those obtained with the standard methods for determining the concrete crack resistance characteristics.

Electroactive polymer gels based on epoxy resin

NASA Astrophysics Data System (ADS)

Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

2007-04-01

Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

Emergence of Joint Attention through Bootstrap Learning based on the Mechanisms of Visual Attention and Learning with Self-evaluation

NASA Astrophysics Data System (ADS)

Nagai, Yukie; Hosoda, Koh; Morita, Akio; Asada, Minoru

This study argues how human infants acquire the ability of joint attention through interactions with their caregivers from a viewpoint of cognitive developmental robotics. In this paper, a mechanism by which a robot acquires sensorimotor coordination for joint attention through bootstrap learning is described. Bootstrap learning is a process by which a learner acquires higher capabilities through interactions with its environment based on embedded lower capabilities even if the learner does not receive any external evaluation nor the environment is controlled. The proposed mechanism for bootstrap learning of joint attention consists of the robot's embedded mechanisms: visual attention and learning with self-evaluation. The former is to find and attend to a salient object in the field of the robot's view, and the latter is to evaluate the success of visual attention, not joint attention, and then to learn the sensorimotor coordination. Since the object which the robot looks at based on visual attention does not always correspond to the object which the caregiver is looking at in an environment including multiple objects, the robot may have incorrect learning situations for joint attention as well as correct ones. However, the robot is expected to statistically lose the learning data of the incorrect ones as outliers because of its weaker correlation between the sensor input and the motor output than that of the correct ones, and consequently to acquire appropriate sensorimotor coordination for joint attention even if the caregiver does not provide any task evaluation to the robot. The experimental results show the validity of the proposed mechanism. It is suggested that the proposed mechanism could explain the developmental mechanism of infants' joint attention because the learning process of the robot's joint attention can be regarded as equivalent to the developmental process of infants' one.

MONITORED NATURAL ATTENUATION FOR INORGANIC CONTAMINANT REMEDIATION IN GROUND WATER: LINES OF EVIDENCE

EPA Science Inventory

Evaluation of MNA for inorganic contaminants requires detailed studies on the aqueous phase and the solid phase. This presentation covers the lines of evidence that may be collected during site investigations to evaluate natural attenuation mechanisms and site-specific capaciti...

Comparison of mechanical energy profiles of passive and active below-knee prostheses: a case study.

PubMed

Takahashi, Kota Z; Horne, John R; Stanhope, Steven J

2015-04-01

With the recent technological advancements of prosthetic lower limbs, there is currently a great desire to objectively evaluate existing prostheses. Using a novel biomechanical analysis, the purpose of this case study was to compare the mechanical energy profiles of anatomical and two disparate prostheses: a passive prosthesis and an active prosthesis. An individual with a transtibial amputation who customarily wears a passive prosthesis (Elation, Össur) and an active prosthesis (BiOM, iWalk, Inc.) and 11 healthy subjects participated in an instrumented gait analysis. The total mechanical power and work of below-knee structures during stance were quantified using a unified deformable segment power analysis. Active prosthesis generated greater peak power and total positive work than passive prosthesis and healthy anatomical limbs. The case study will enhance future efforts to objectively evaluate prosthetic functions during gait in individuals with transtibial amputations. A prosthetic limb should closely replicate the mechanical energy profiles of anatomical limbs. The unified deformable (UD) analysis may be valuable to facilitate future clinical prescription and guide fine adjustments of prosthetic componentry to optimize gait outcomes. © The International Society for Prosthetics and Orthotics 2014.

Gear and Transmission Research at NASA Lewis Research Center

NASA Technical Reports Server (NTRS)

Townsend, Dennis P.

1997-01-01

This paper is a review of some of the research work of the NASA Lewis Research Center Mechanical Components Branch. It includes a brief review of the NASA Lewis Research Center and the Mechanical Components Branch. The research topics discussed are crack propagation of gear teeth, gear noise of spiral bevel and other gears, design optimization methods, methods we have investigated for transmission diagnostics, the analytical and experimental study of gear thermal conditions, the analytical and experimental study of split torque systems, the evaluation of several new advanced gear steels and transmission lubricants and the evaluation of various aircraft transmissions. The area of research needs for gearing and transmissions is also discussed.

Ultrastructural and mechanical changes in tubular epithelial cells by angiotensin II and aldosterone as observed with atomic force microscopy.

PubMed

Quan, Fu-Shi; Jeong, Kyung Hwan; Lee, Gi-Ja

2018-07-01

Tubular epithelial cells (TECs) play an important pathophysiological role in the promotion of renal fibrosis. Quantitative analysis of the mechanical changes in TECs may be helpful in evaluating novel pharmacological strategies. Atomic force microscopy (AFM) is a common nanotechnology tool used for imaging and measuring interaction forces in biological systems. In this study, we used AFM to study ultrastructural and mechanical changes in TECs mediated by the renin-angiotensin-aldosterone system. We quantitatively analyzed changes in the mechanical properties of TECs using three extrinsic factors, namely, chemical fixation, angiotensin II (AT II), and aldosterone (AD). Fixed TECs were 11 times stiffer at the cell body and 3 times stiffer at the cell-cell junction compared to live TECs. After stimulation with AT II, live TECs were four times stiffer at the junctional area than at the cell body, while fixed TECs after AT II stimulation were approximately two times stiffer at the both cell body and cell-cell junction compared to fixed unstimulated TECs. Fixed TECs also reflected changes in the mechanical properties of TECs at the cell body region after AD stimulation. Together, our results suggest that cell stiffness at the cell body region may serve as an effective index for evaluating drugs and stimulation, regardless of whether the cells are live or fixed at the time of analysis. In addition, studying the changes to the intrinsic mechanical property of TECs after application of external stimuli may be useful for investigating pathophysiologic mechanisms and effective therapeutic strategies for renal injury. Copyright © 2018 Elsevier Ltd. All rights reserved.

Poor chest compression quality with mechanical compressions in simulated cardiopulmonary resuscitation: a randomized, cross-over manikin study.

PubMed

Blomberg, Hans; Gedeborg, Rolf; Berglund, Lars; Karlsten, Rolf; Johansson, Jakob

2011-10-01

Mechanical chest compression devices are being implemented as an aid in cardiopulmonary resuscitation (CPR), despite lack of evidence of improved outcome. This manikin study evaluates the CPR-performance of ambulance crews, who had a mechanical chest compression device implemented in their routine clinical practice 8 months previously. The objectives were to evaluate time to first defibrillation, no-flow time, and estimate the quality of compressions. The performance of 21 ambulance crews (ambulance nurse and emergency medical technician) with the authorization to perform advanced life support was studied in an experimental, randomized cross-over study in a manikin setup. Each crew performed two identical CPR scenarios, with and without the aid of the mechanical compression device LUCAS. A computerized manikin was used for data sampling. There were no substantial differences in time to first defibrillation or no-flow time until first defibrillation. However, the fraction of adequate compressions in relation to total compressions was remarkably low in LUCAS-CPR (58%) compared to manual CPR (88%) (95% confidence interval for the difference: 13-50%). Only 12 out of the 21 ambulance crews (57%) applied the mandatory stabilization strap on the LUCAS device. The use of a mechanical compression aid was not associated with substantial differences in time to first defibrillation or no-flow time in the early phase of CPR. However, constant but poor chest compressions due to failure in recognizing and correcting a malposition of the device may counteract a potential benefit of mechanical chest compressions. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Cardiac mechanics: Physiological, clinical, and mathematical considerations

NASA Technical Reports Server (NTRS)

Mirsky, I. (Editor); Ghista, D. N.; Sandler, H.

1974-01-01

Recent studies concerning the basic physiological and biochemical principles underlying cardiac muscle contraction, methods for the assessment of cardiac function in the clinical situation, and mathematical approaches to cardiac mechanics are presented. Some of the topics covered include: cardiac ultrastructure and function in the normal and failing heart, myocardial energetics, clinical applications of angiocardiography, use of echocardiography for evaluating cardiac performance, systolic time intervals in the noninvasive assessment of left ventricular performance in man, evaluation of passive elastic stiffness for the left ventricle and isolated heart muscle, a conceptual model of myocardial infarction and cardiogenic shock, application of Huxley's sliding-filament theory to the mechanics of normal and hypertrophied cardiac muscle, and a rheological modeling of the intact left ventricle. Individual items are announced in this issue.

Uncovering the Hidden Meaning of Cross-Curriculum Comparison Results on the Force Concept Inventory

ERIC Educational Resources Information Center

Ding, Lin; Caballero, Marcos D.

2014-01-01

In a recent study, Caballero and colleagues conducted a large-scale evaluation using the Force Concept Inventory (FCI) to compare student learning outcomes between two introductory physics curricula: the Matter and Interactions (M&I) mechanics course and a pedagogically-reformed-traditional-content (PRTC) mechanics course. Using a conventional…

Measuring Clearance Mechanics Based on Dynamic Leg Length

ERIC Educational Resources Information Center

Khamis, Sam; Danino, Barry; Hayek, Shlomo; Carmeli, Eli

2018-01-01

The aim of this study was to quantify clearance mechanics during gait. Seventeen children diagnosed with hemiplegic cerebral palsy underwent a three-dimensional gait analysis evaluation. Dynamic leg lengths were measured from the hip joint center to the heel, to the ankle joint center and to the forefoot throughout the gait cycle. Significant…

Learning Activity Packets for Auto Mechanics II. Section A--Engine Rebuilding.

ERIC Educational Resources Information Center

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

Eight learning activity packets (LAPs) are provided for the instructional area of engine rebuilding in the auto mechanics II program. They accompany an instructor's guide available separately. The LAPs outline the study activities and performance tasks for these eight units: (1) engine condition evaluation; (2) engine removal; (3) engine…

Efficacy and putative mode of action of native and commercial antagonistic yeasts against postharvest pathogens of pear.

PubMed

Lutz, M Cecilia; Lopes, Christian A; Rodriguez, M Eugenia; Sosa, M Cristina; Sangorrín, Marcela P

2013-06-17

Putative mechanisms of action associated with the biocontrol capacity of four yeast strains (Cryptoccocus albidus NPCC 1248, Pichia membranifaciens NPCC 1250, Cryptoccocus victoriae NPCC 1263 and NPCC 1259) against Penicillium expansum and Botrytis cinerea were studied by means of in vitro and in situ assays. C. albidus(YP), a commercial yeast was also evaluated for comparative purposes. The yeast strains exhibited a variety of different mechanisms including: wound colonization, germination inhibition, biofilm formation, secretion of killer toxins, competition for nutrient and secretion of hydrolytic enzymes (protease, chitinase and glucanase). The relationship between strains (and their associated antagonist mechanisms) and in situ antagonist activity was also evaluated. Results indicate that mechanisms such as production of hydrolytic enzymes, the ability for colonization of wounds, production of killer toxin and inhibition of germination are the most important for biocontrol activity. Our study indicate that multiple modes of action may explain why P. membranifaciens NPCC 1250 and C. victoriae NPCC 1263 provided excellent control of postharvest pears disease. Copyright © 2013 Elsevier B.V. All rights reserved.

Study of the effect of gamma irradiation on a commercial polycyclooctene I. Thermal and mechanical properties

NASA Astrophysics Data System (ADS)

García-Huete, N.; Laza, J. M.; Cuevas, J. M.; Vilas, J. L.; Bilbao, E.; León, L. M.

2014-09-01

A gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical, chemical and mechanical properties. Gamma irradiation originates free radicals able to induce chain scission or recombination of radicals, which induces annihilation, branching or crosslinking processes. The aim of this work is to research the structural, thermal and mechanical changes induced on a commercial polycyclooctene (PCO) when it is irradiated with a gamma source of 60Co at different doses (25-200 kGy). After gamma irradiation, gel content was determined by Soxhlet extraction in cyclohexane. Furthermore, thermal properties were evaluated before and after Soxhlet extraction by means of Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC), as well as mechanical properties were measured by Dynamic Mechanical Thermal Analysis (DMTA). The results showed the variations of the properties depending on the irradiation dose. Finally, a first approach to evaluate qualitatively the shape memory behaviour of all irradiated PCO samples was performed by a visually monitoring shape recovery process.

Effect of Casting Defect on Mechanical Properties of 17-4PH Stainless Steel

NASA Astrophysics Data System (ADS)

Kim, Jong-Yup; Lee, Joon-Hyun; Nahm, Seung-Hoon

Damage and integrity evaluation techniques should be developed steadily in order to ensure the reliability and the economic efficiency of gas turbine engines. Casting defects may exist in most casting components of gas turbine engines, and the defects could give serious effect on mechanical properties and fracture toughness. Therefore, it is very important to understand the effect of casting defects on the above properties in order to predict the safety and life of components. In this study, specimens with internal casting defects, made from 17-4PH stainless steel, were prepared and evaluated and characterized based on the volume fraction of defects. The relation between mechanical properties such as tensile, low cycle fatigue and fracture toughness and volume fraction of defect has been investigated. As a result of the analysis, the mechanical properties of 17-4PH decreased as the defect volume fraction increased with very good linearity. The mechanical properties also showed an inversely proportional relationship to electrical resistivity.

Correcting for compensating mechanisms related to productivity costs in economic evaluations of health care programmes.

PubMed

Jacob-Tacken, Karin H M; Koopmanschap, Marc A; Meerding, Willem Jan; Severens, Johan L

2005-05-01

In the economic evaluation of health care programmes, productivity costs are often estimated using patients' wages for the period of absence. However, the use of such methods for short periods of absence is controversial. A previous study found that short-term absence is often compensated for during normal working hours and therefore does not lead to productivity losses. As such, the application of any approach almost certainly overestimates productivity costs. In this study, we examined the productivity costs for five different patient populations and one employee population, using the classical method and by identifying when extra effort was needed. In general, the results showed that productivity costs based on identifying extra effort were 25-30% of the classical estimates. For absences of just one day, productivity costs were relevant in only 17-19% of cases. For absences of two weeks or longer, productivity costs were relevant in 35-39% of cases. Measurement of the compensating mechanisms seemed to be valid, since there is considerable agreement between the opinion of supervisors and their employees about whether compensation covers productivity costs. There was much less agreement between supervisors and their employees on specific compensating mechanisms, however. The measurement of compensating mechanisms also seemed to be valid, because--as expected--different compensating mechanisms were reported for different occupations. In our study populations, compensating mechanisms appeared to differ with occupational characteristics, like part-time work, managerial work and shift work. Copyright 2004 John Wiley & Sons, Ltd

Chemical kinetic reaction mechanism for the combustion of propane

NASA Technical Reports Server (NTRS)

Jachimowski, C. J.

1984-01-01

A detailed chemical kinetic reaction mechanism for the combustion of propane is presented and discussed. The mechanism consists of 27 chemical species and 83 elementary chemical reactions. Ignition and combustion data as determined in shock tube studies were used to evaluate the mechanism. Numerical simulation of the shock tube experiments showed that the kinetic behavior predicted by the mechanism for stoichiometric mixtures is in good agrement with the experimental results over the entire temperature range examined (1150-2600K). Sensitivity and theoretical studies carried out using the mechanism revealed that hydrocarbon reactions which are involved in the formation of the HO2 radical and the H2O2 molecule are very important in the mechanism and that the observed nonlinear behavior of ignition delay time with decreasing temperature can be interpreted in terms of the increased importance of the HO2 and H2O2 reactions at the lower temperatures.

Evaluation of Jacobian determinants by Monte Carlo methods: Application to the quasiclassical approximation in molecular scattering

NASA Technical Reports Server (NTRS)

Labudde, R. A.

1971-01-01

A technique is described which can be used to evaluate Jacobian determinants which occur in classical mechanical and quasiclassical approximation descriptions of molecular scattering. The method may be valuable in the study of reactive scattering using the quasiclassical approximation.

Evaluation of the SafeLane overlay system for crash reduction on bridge deck surfaces.

DOT National Transportation Integrated Search

2010-03-01

The winter performance of the SafeLane commercial overlay system has been evaluated at four installations on : bridge decks in the state of Minnesota. The study was conducted over a period of a total of three years. Analyses : included mechanical ...

Effect of progressive wear on the contact mechanics of hip replacements--does the realistic surface profile matter?

PubMed

Wang, Ling; Yang, Wenjian; Peng, Xifeng; Li, Dichen; Dong, Shuangpeng; Zhang, Shu; Zhu, Jinyu; Jin, Zhongmin

2015-04-13

The contact mechanics of artificial metal-on-polyethylene hip joints are believed to affect the lubrication, wear and friction of the articulating surfaces and may lead to the joint loosening. Finite element analysis has been widely used for contact mechanics studies and good agreements have been achieved with current experimental data; however, most studies were carried out with idealist spherical geometries of the hip prostheses rather than the realistic worn surfaces, either for simplification reason or lacking of worn surface profile. In this study, the worn surfaces of the samples from various stages of hip simulator testing (0 to 5 million cycles) were reconstructed as solid models and were applied in the contact mechanics study. The simulator testing results suggested that the center of the head has various departure value from that of the cup and the value of the departure varies with progressively increased wear. This finding was adopted into the finite element study for better evaluation accuracy. Results indicated that the realistic model provided different evaluation from that of the ideal spherical model. Moreover, with the progressively increased wear, large increase of the contact pressure (from 12 to 31 MPa) was predicted on the articulating surface, and the predicted maximum von Mises stress was increased from 7.47 to 13.26 MPa, indicating the marked effect of the worn surface profiles on the contact mechanics of the joint. This study seeks to emphasize the importance of realistic worn surface profile of the acetabular cup especially following large wear volume. Copyright © 2015 Elsevier Ltd. All rights reserved.

Protocol of the PLeural Effusion And Symptom Evaluation (PLEASE) study on the pathophysiology of breathlessness in patients with symptomatic pleural effusions.

PubMed

Thomas, Rajesh; Azzopardi, Maree; Muruganandan, Sanjeevan; Read, Catherine; Murray, Kevin; Eastwood, Peter; Jenkins, Sue; Singh, Bhajan; Lee, Y C Gary

2016-08-03

Pleural effusion is a common clinical problem that can complicate many medical conditions. Breathlessness is the most common symptom of pleural effusion of any cause and the most common reason for pleural drainage. However, improvement in breathlessness following drainage of an effusion is variable; some patients experience either no benefit or a worsening of their breathlessness. The physiological mechanisms underlying breathlessness in patients with a pleural effusion are unclear and likely to be multifactorial with patient-related and effusion-related factors contributing. A comprehensive study of the physiological and symptom responses to drainage of pleural effusions may provide a clearer understanding of these mechanisms, and may identify predictors of benefit from drainage. The ability to identify those patients whose breathlessness will (or will not) improve after pleural fluid drainage can help avoid unnecessary pleural drainage procedures, their associated morbidities and costs. The PLeural Effusion And Symptom Evaluation (PLEASE) study is a prospective study to comprehensively evaluate factors contributing to pleural effusion-related breathlessness. The PLEASE study is a single-centre prospective study of 150 patients with symptomatic pleural effusions that require therapeutic drainage. The study aims to identify key factors that underlie breathlessness in patients with pleural effusions and develop predictors of improvement in breathlessness following effusion drainage. Participants will undergo evaluation pre-effusion and post-effusion drainage to assess their level of breathlessness at rest and during exercise, respiratory and other physiological responses as well as respiratory muscle mechanics. Pre-drainage and post-drainage parameters will be collected and compared to identify the key factors and mechanisms that correlate with improvement in breathlessness. Approved by the Sir Charles Gairdner Group Human Research Ethics Committee (HREC number 2014-079). Registered with the Australian New Zealand Clinical Trials Registry (ACTRN12616000820404). Results will be published in peer-reviewed journals and presented at scientific meetings. ACTRN12616000820404; Pre-results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Explicit expressions of quantum mechanical rotation operators for spins 1 to 2

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

Kocakoç, Mehpeyker, E-mail: mkocakoc@cu.edu.tr; Tapramaz, Recep, E-mail: recept@omu.edu.tr

2016-03-25

Quantum mechanical rotation operators are the subject of quantum mechanics, mathematics and pulsed magnetic resonance spectroscopies, namely NMR, EPR and ENDOR. They are also necessary for spin based quantum information systems. The rotation operators of spin 1/2 are well known and can be found in related textbooks. But rotation operators of other spins greater than 1/2 can be found numerically by evaluating the series expansions of exponential operator obtained from Schrödinger equation, or by evaluating Wigner-d formula or by evaluating recently established expressions in polynomial forms discussed in the text. In this work, explicit symbolic expressions of x, y andmore » z components of rotation operators for spins 1 to 2 are worked out by evaluating series expansion of exponential operator for each element of operators and utilizing linear curve fitting process. The procedures gave out exact expressions of each element of the rotation operators. The operators of spins greater than 2 are under study and will be published in a separate paper.« less

Validation of Intensive Care and Mechanical Ventilation Codes in Medicare Data.

PubMed

Wunsch, Hannah; Kramer, Andrew; Gershengorn, Hayley B

2017-07-01

To assess the reliability of codes relevant to critically ill patients in administrative data. Retrospective cohort study linking data from Acute Physiology and Chronic Health Evaluation Outcomes, a clinical database of ICU patients with data from Medicare Provider Analysis and Review. We linked data based on matching for sex, date of birth, hospital, and date of admission to hospital. Forty-six hospitals in the United States participating in Acute Physiology and Chronic Health Evaluation Outcomes. All patients in Acute Physiology and Chronic Health Evaluation Outcomes greater than or equal to 65 years old who could be linked with hospitalization records in Medicare Provider Analysis and Review from January 1, 2009, through September 30, 2012. Of 62,451 patients in the Acute Physiology and Chronic Health Evaluation Outcomes dataset, 80.1% were matched with data in Medicare Provider Analysis and Review. All but 2.7% of Acute Physiology and Chronic Health Evaluation Outcomes ICU patients had either an ICU or coronary care unit charge in Medicare Provider Analysis and Review. In Acute Physiology and Chronic Health Evaluation Outcomes, 37.0% received mechanical ventilation during the ICU stay versus 24.1% in Medicare Provider Analysis and Review. The Medicare Provider Analysis and Review procedure codes for mechanical ventilation had high specificity (96.0%; 95% CI, 95.8-96.2), but only moderate sensitivity (58.4%; 95% CI, 57.7-59.1), with a positive predictive value of 89.6% (95% CI, 89.1-90.1) and negative predictive value of 79.7% (95% CI, 79.4-80.1). For patients with mechanical ventilation codes, Medicare Provider Analysis and Review overestimated the percentage with a duration greater than 96 hours (36.6% vs 27.3% in Acute Physiology and Chronic Health Evaluation Outcomes). There was discordance in the hospital discharge status (alive or dead) for only 0.47% of all linked records (κ = 1.00). Medicare Provider Analysis and Review data contain robust information on hospital mortality for patients admitted to the ICU but have limited ability to identify all patients who received mechanical ventilation during a critical illness. Estimates of use of mechanical ventilation in the United States should likely be revised upward.

Structure of the Soot Growth Region of Laminar Premixer Methane/Oxygen Flames

NASA Technical Reports Server (NTRS)

Xu, F.; Faeth, G. M.

1999-01-01

Soot is a dominant feature of hydrocarbon/air flames, affecting their reaction mechanisms and structure. As a result, soot processes affect capabilities for computational combustion as well as predictions of flame radiation and pollution emissions. Motivated by these observations, the present investigation extended past work on soot growth in laminar premixed flames, seeking to evaluate model predictions of flame structure. Xu et al. report direct measurements of soot residence times, soot concentrations, soot structure, gas temperatures and gas compositions for premixed flames similar to those studied by Harris and Weiner and Ramer et al. respectively. It was found that predictions of major stable gas species concentrations based on mechanisms of Leung and Lindstedt and Frenklach and coworkers, were in good agreement with the measurements. The results were also used to evaluate the hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms of Frenklach and coworkers and Colket and Hall. It was found that these mechanisms were effective using quite reasonable correlations for the steric factors appearing in the theories. The successful evaluation of the HACA mechanism of soot growth in Refs. 1 and 2 is encouraging but one aspect of this evaluation is a concern. In particular, H-atom concentrations play a crucial role in the HACA mechanism and it was necessary to estimate these concentrations because they were not measured directly. These estimates were made assuming local thermodynamic equilibrium between H, and H based on measured temperatures and H2 concentrations and the equilibrium constant data of Kee et al.. This approach was justified by the flame structure predictions; nevertheless, direct evaluation of equilibrium estimates of H-atom concentrations in the soot growth regions of laminar premixed flames is needed to provide more convincing proof of this behavior. Thus, the objective of the present investigation was to complete new measurements of the structure of the soot growth region of laminar premixed flames and to use these results to evaluate whether H and H2 are in thermodynamic equilibrium and to extend the earlier evaluation of predictions of concentrations of major gas species.

An optimized transversely isotropic, hyper-poro-viscoelastic finite element model of the meniscus to evaluate mechanical degradation following traumatic loading

PubMed Central

Wheatley, Benjamin B.; Fischenich, Kristine M.; Button, Keith D.; Haut, Roger C.; Haut Donahue, Tammy L.

2015-01-01

Inverse finite element (FE) analysis is an effective method to predict material behavior, evaluate mechanical properties, and study differences in biological tissue function. The meniscus plays a key role in load distribution within the knee joint and meniscal degradation is commonly associated with the onset of osteoarthritis. In the current study, a novel transversely isotropic hyper-poro-viscoelastic constitutive formulation was incorporated in a FE model to evaluate changes in meniscal material properties following tibiofemoral joint impact. A non-linear optimization scheme was used to fit the model output to indentation relaxation experimental data. This study is the first to investigate rate of relaxation in healthy versus impacted menisci. Stiffness was found to be decreased (p=0.003), while the rate of tissue relaxation increased (p=0.010) at twelve weeks post impact. Total amount of relaxation, however, did not change in the impacted tissue (p=0.513). PMID:25776872

Evidence for transgenerational metabolic programming in Drosophila

PubMed Central

Buescher, Jessica L.; Musselman, Laura P.; Wilson, Christina A.; Lang, Tieming; Keleher, Madeline; Baranski, Thomas J.; Duncan, Jennifer G.

2013-01-01

SUMMARY Worldwide epidemiologic studies have repeatedly demonstrated an association between prenatal nutritional environment, birth weight and susceptibility to adult diseases including obesity, cardiovascular disease and type 2 diabetes. Despite advances in mammalian model systems, the molecular mechanisms underlying this phenomenon are unclear, but might involve programming mechanisms such as epigenetics. Here we describe a new system for evaluating metabolic programming mechanisms using a simple, genetically tractable Drosophila model. We examined the effect of maternal caloric excess on offspring and found that a high-sugar maternal diet alters body composition of larval offspring for at least two generations, augments an obese-like phenotype under suboptimal (high-calorie) feeding conditions in adult offspring, and modifies expression of metabolic genes. Our data indicate that nutritional programming mechanisms could be highly conserved and support the use of Drosophila as a model for evaluating the underlying genetic and epigenetic contributions to this phenomenon. PMID:23649823

Kinematic Analysis and Performance Evaluation of Novel PRS Parallel Mechanism

NASA Astrophysics Data System (ADS)

Balaji, K.; Khan, B. Shahul Hamid

2018-02-01

In this paper, a 3 DoF (Degree of Freedom) novel PRS (Prismatic-Revolute- Spherical) type parallel mechanisms has been designed and presented. The combination of striaght and arc type linkages for 3 DOF parallel mechanism is introduced for the first time. The performances of the mechanisms are evaluated based on the indices such as Minimum Singular Value (MSV), Condition Number (CN), Local Conditioning Index (LCI), Kinematic Configuration Index (KCI) and Global Conditioning Index (GCI). The overall reachable workspace of all mechanisms are presented. The kinematic measure, dexterity measure and workspace analysis for all the mechanism have been evaluated and compared.

Evaluation of a Post-Processing Approach for Multiscale Analysis of Biphasic Mechanics of Chondrocytes

PubMed Central

Sibole, Scott C.; Maas, Steve; Halloran, Jason P.; Weiss, Jeffrey A.; Erdemir, Ahmet

2014-01-01

Understanding the mechanical behavior of chondrocytes as a result of cartilage tissue mechanics has significant implications for both evaluation of mechanobiological function and to elaborate on damage mechanisms. A common procedure for prediction of chondrocyte mechanics (and of cell mechanics in general) relies on a computational post-processing approach where tissue level deformations drive cell level models. Potential loss of information in this numerical coupling approach may cause erroneous cellular scale results, particularly during multiphysics analysis of cartilage. The goal of this study was to evaluate the capacity of 1st and 2nd order data passing to predict chondrocyte mechanics by analyzing cartilage deformations obtained for varying complexity of loading scenarios. A tissue scale model with a sub-region incorporating representation of chondron size and distribution served as control. The postprocessing approach first required solution of a homogeneous tissue level model, results of which were used to drive a separate cell level model (same characteristics as the subregion of control model). The 1st data passing appeared to be adequate for simplified loading of the cartilage and for a subset of cell deformation metrics, e.g., change in aspect ratio. The 2nd order data passing scheme was more accurate, particularly when asymmetric permeability of the tissue boundaries were considered. Yet, the method exhibited limitations for predictions of instantaneous metrics related to the fluid phase, e.g., mass exchange rate. Nonetheless, employing higher-order data exchange schemes may be necessary to understand the biphasic mechanics of cells under lifelike tissue loading states for the whole time history of the simulation. PMID:23809004

Supervision, support and mentoring interventions for health practitioners in rural and remote contexts: an integrative review and thematic synthesis of the literature to identify mechanisms for successful outcomes.

PubMed

Moran, Anna M; Coyle, Julia; Pope, Rod; Boxall, Dianne; Nancarrow, Susan A; Young, Jennifer

2014-02-13

To identify mechanisms for the successful implementation of support strategies for health-care practitioners in rural and remote contexts. This is an integrative review and thematic synthesis of the empirical literature that examines support interventions for health-care practitioners in rural and remote contexts. This review includes 43 papers that evaluated support strategies for the rural and remote health workforce. Interventions were predominantly training and education programmes with limited evaluations of supervision and mentoring interventions. The mechanisms associated with successful outcomes included: access to appropriate and adequate training, skills and knowledge for the support intervention; accessible and adequate resources; active involvement of stakeholders in programme design, implementation and evaluation; a needs analysis prior to the intervention; external support, organisation, facilitation and/or coordination of the programme; marketing of the programme; organisational commitment; appropriate mode of delivery; leadership; and regular feedback and evaluation of the programme. Through a synthesis of the literature, this research has identified a number of mechanisms that are associated with successful support interventions for health-care practitioners in rural and remote contexts. This research utilised a methodology developed for studying complex interventions in response to the perceived limitations of traditional systematic reviews. This synthesis of the evidence will provide decision-makers at all levels with a collection of mechanisms that can assist the development and implementation of support strategies for staff in rural and remote contexts.

Supervision, support and mentoring interventions for health practitioners in rural and remote contexts: an integrative review and thematic synthesis of the literature to identify mechanisms for successful outcomes

PubMed Central

2014-01-01

Objective To identify mechanisms for the successful implementation of support strategies for health-care practitioners in rural and remote contexts. Design This is an integrative review and thematic synthesis of the empirical literature that examines support interventions for health-care practitioners in rural and remote contexts. Results This review includes 43 papers that evaluated support strategies for the rural and remote health workforce. Interventions were predominantly training and education programmes with limited evaluations of supervision and mentoring interventions. The mechanisms associated with successful outcomes included: access to appropriate and adequate training, skills and knowledge for the support intervention; accessible and adequate resources; active involvement of stakeholders in programme design, implementation and evaluation; a needs analysis prior to the intervention; external support, organisation, facilitation and/or coordination of the programme; marketing of the programme; organisational commitment; appropriate mode of delivery; leadership; and regular feedback and evaluation of the programme. Conclusion Through a synthesis of the literature, this research has identified a number of mechanisms that are associated with successful support interventions for health-care practitioners in rural and remote contexts. This research utilised a methodology developed for studying complex interventions in response to the perceived limitations of traditional systematic reviews. This synthesis of the evidence will provide decision-makers at all levels with a collection of mechanisms that can assist the development and implementation of support strategies for staff in rural and remote contexts. PMID:24521004

Uni-Directional Cell Stretching Device

NASA Technical Reports Server (NTRS)

Feeback, Daniel L. (Inventor); Clarke, Mark S. F. (Inventor)

2000-01-01

The present invention relates to an apparatus and method for applying various degrees of linear, mechanical loads on mammalian tissues, and in particular, for effecting linear stretching of tissue and simulating changes in hydrostatic pressures encountered during tissue contraction in vivo. The apparatus is useful for the study of mechanical loading in human tissue, and specifically, for permitting the evaluation of the effects of mechanical loading of skeletal or cardiac tissue and of the effects of removal of mechanical loading due to inactivity or the like, and the subsequent reapplication of load to these tissues.

Interrelationship of mechanical and corrosion-mechanical characteristics of type 12KhN4MF steel

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

Voronin, V.P.; Goncharov, A.F.; Maslov, V.A.

1985-11-01

Investigations presented include a comparative evaluation of the corrosionmechanical characteristics of specimens of high-strength chrome-nickelmolybdenum steel taking into consideration the different methods of melting of the original metal. A comparison of the corrosion-mechanical test results obtained with the results of acceptance tests are presented. A study of the fracture surfaces and the specimen material with the use of fractographic, macroscopic, and microscopic analyses is given. The systematization of the corrosion-mechanical test results with the use of methods of mathematical statistics are presented.

In vitro methods for evaluating skin hydration under diapers and incontinence products.

PubMed

Tate, M L; Wright, A S

2017-11-01

Excessive skin hydration from wearing wet undergarments, such as infant diapers and adult incontinence products, has been historically problematic. Skin damage occurs from wetness (urine) and limited product breathability. Evaporative water loss has been measured on adult arms (armband method) or infant torsos (on-baby method), after wearing a saline-insulted diaper product. The current study developed a reliable in vitro method of evaluating diaper and incontinence products for improvements in skin dryness. A simulated skin substrate was applied to a heated mechanical arm or baby torso. A disposable diaper or incontinence product was wrapped around the arm or baby torso, and loaded with saline. Hydration of the simulated skin was measured by evaporimetry and compared with clinical data from adult armband evaluations. The heated mechanical arm and baby torso accurately distinguished products for skin dryness. Eight diaper products were evaluated and compared to human test results. The torso in vitro and mechanical arm evaluations demonstrated strong correlations to human epidermal water loss evaluations, with repeatable results. Additionally, the bench test has been used for adult incontinence products, and it proved to differentiate those products as well as infant products. A rapid and reliable means of evaluation has been developed, and it is predictive of human subject testing. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Cytotoxicity evaluation of ceramic particles of different sizes and shapes.

PubMed

Yamamoto, Akiko; Honma, Rieko; Sumita, Masae; Hanawa, Takao

2004-02-01

When artificial hip or knee joints are implanted in the human body, they release metallic, ceramic, and polymeric debris into the surrounding tissues. The toxicity of the released particles is of two types: chemical, caused by the released soluble ions and monomers, and mechanical, a result of mechanical stimulation produced by the insoluble particles. In this study, the cytotoxicity of particles of TiO2, Al2O3, ZrO2, Si3N4, and SiC for murine fibroblasts and macrophages were examined to evaluate just their mechanical toxicity because these particles are not expected to release soluble metal ions. Different sizes and shapes of TiO2 particles were used to evaluate the effect of size and shape on particle cytotoxicity. The results suggest that the cytotoxicity of ceramic particles does not depend on their chemical species. Cytotoxicity levels were lower than those of corresponding metal ions, indicating that the mechanical toxicity of particles is lower than the chemical toxicity of released soluble ions and monomers. The differences in size did not affect the mechanical toxicity of these particles. The dendritic particles had a higher cytotoxicity level for macrophages than did spindle and spheric particles. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 244-256, 2004

N-vinylpyrrolidone modified glass-ionomer resins for improved dental restoratives

NASA Astrophysics Data System (ADS)

Xie, Dong

The studies described in this dissertation focus on improvement of mechanical properties of current glass-ionomer cements. Thermal properties and microstructures of the cements were correlated with their mechanical strengths. The first study evaluated mechanical properties of selected commercial glass-ionomer cements and examined their microstructures. The results showed that resin-modified glass-ionomer cements (RM GICs) exhibited much higher flexural (FS) and diametral tensile strengths (DTS), compared to conventional GICs (C GICs). In addition, they exhibited comparable compressive strength (CS), relatively low microhardness and less wear resistance than C GICs. The C GICs exhibited brittle behavior, whereas the RM GICs underwent substantial plastic deformation in compression. The mechanical properties of the GICs were closely related to their microstructures. Factors such as the density of the microstructure, the integrity of the interface between the glass particles and polymer matrix, particle size and the number and size of voids have important roles in determining the mechanical properties. The second study evaluated thermal properties of these GICs. The results showed that the RM GICs exhibited higher thermal transition temperatures than those of the C GICs, thermal expansion coefficients of these cements were close to those of human teeth, and the indentation creep of the RM GICs were higher than the C GICs. The third study explored and evaluated the effect of a water-soluble monomer, N-vinylpyrrolidone (NVP), on the performance of current C GICs, indicating a significant improvement in both mechanical and working properties. The fourth study demonstrated the process of determining the optimal molar ratio of the NVP-containing copolymers, using design of experiment. The results showed that the optimal molar ratio for these copolymers was 7:1:3 for poly(acrylic acid-co-itaconic acid-co-N-vinylpyrrolidone), based on the FS test. The molar ratio of 8:2:1 (AA:IA:NVP) was considered as the best molar ratio for these copolymers, based on the DTS and CS tests. The fifth study formulated the NVP-containing RM GICs using a statistical design of experiment. The results indicated that the best graft ratio for 2-isocyanatoethyl methacrylate (IEM) in this system was 15% of the terpolymer by a molar ratio. The optimal formulation was found to be at the weight ratio of 55:15:30 (RM NVP-containing terpolymer: 2-hydroxyethyl methacrylate (HEMA): Hsb2O). Stress-strain curves showed that a relatively high amount of water in the formulation led to higher elastic modulus and proportional limit and lower malleability, whereas a relatively high amount of HEMA gave the opposite results. The sixth study evaluated the NVP modified GICs (NVPM GICs) with the best molar ratios and optimal formulations in the mechanical, thermal and working properties. The results showed that the effect of molecular weight on mechanical properties of the NVPM GICs were evident. Different glass powders exhibited different effects on properties of the NVPM GICs, due to different compositions, size and affinity. Powder/liquid ratios had significant effects on the mechanical properties of NVPM GICs, especially on FS. P/W ratios are only beneficial to the NVPM GICs mixed with the Fuji II glass powders. The NVPM GICs showed a higher WT than the models, due to water retention of the NVP ring. Thermal expansion coefficients for the NVPM GICs were close to those for the natural tooth. Mismatch between the glass powders used and the polymer matrix was a big concern in this study and should be solved in the future.

Evaluation of physico-mechanical properties of mycelium reinforced green biocomposites made from cellulosic fibers

USDA-ARS?s Scientific Manuscript database

Biodegradable and sustainable feedstock’s are increasingly replacing petroleum based materials commonly used for single or multi use packaging applications. A study was conducted to evaluate the potential of an innovative biocomposite material patented by Ecovative Design LLC for use in commercial p...

Faculty Development for Educators: A Realist Evaluation

ERIC Educational Resources Information Center

Sorinola, Olanrewaju O.; Thistlethwaite, Jill; Davies, David; Peile, Ed

2015-01-01

The effectiveness of faculty development (FD) activities for educators in UK medical schools remains underexplored. This study used a realist approach to evaluate FD and to test the hypothesis that motivation, engagement and perception are key mechanisms of effective FD activities. The authors observed and interviewed 33 course participants at one…

Making the Grade: Using Instructional Feedback and Evaluation to Inspire Evidence-Based Teaching

ERIC Educational Resources Information Center

Brickman, Peggy; Gormally, Cara; Martella, Amedee Marchand

2016-01-01

Typically, faculty receive feedback about teaching via two mechanisms: end-of-semester student evaluations and peer observation. However, instructors require more sustained encouragement and constructive feedback when implementing evidence-based teaching practices. Our study goal was to characterize the landscape of current instructional-feedback…

Reports of the National Juvenile Justice Assessment Centers. Juvenile Delinquency Prevention Experiments: A Review and Analysis.

ERIC Educational Resources Information Center

Berleman, William C.

Ten delinquency prevention studies are reviewed that incorporated rigorous evaluative procedures (specifically the classic experimental design) for assessing programmatic outcomes. Following an introduction, the evaluation mechanisms built into each project are described, since they were used for determination of the effectiveness of the…

In vitro mechanical stimulation facilitates stress dissipation and sealing ability at the conventional glass ionomer cement-dentin interface.

PubMed

Toledano, Manuel; Osorio, Raquel; Osorio, Estrella; Cabello, Inmaculada; Toledano-Osorio, Manuel; Aguilera, Fátima S

2018-06-01

The aim of this study was to evaluate the induced changes in the chemical and mechanical performance at the glass-ionomer cement-dentin interface after mechanical load application. A conventional glass-ionomer cement (GIC) (Ketac Bond), and a resin-modified glass-ionomer cement (RMGIC) (Vitrebond Plus) were used. Bonded interfaces were stored in simulated body fluid, and then tested or submitted to the mechanical loading challenge. Different loading waveforms were applied: No cycling, 24 h cycled in sine or loaded in sustained hold waveforms. The cement-dentin interface was evaluated using a nano-dynamic mechanical analysis, estimating the complex modulus and tan δ. Atomic Force Microscopy (AFM) imaging, Raman analysis and dye assisted confocal microscopy evaluation (CLSM) were also performed. The complex modulus was lower and tan delta was higher at interfaces promoted with the GIC if compared to the RMGIC unloaded. The conventional GIC attained evident reduction of nanoleakage. Mechanical loading favored remineralization and promoted higher complex modulus and lower tan delta values at interfaces with RMGIC, where porosity, micropermeability and nanoleakage were more abundant. Mechanical stimuli diminished the resistance to deformation and increased the stored energy at the GIC-dentin interface. The conventional GIC induced less porosity and nanoleakage than RMGIC. The RMGIC increased nanoleakage at the porous interface, and dye sorption appeared within the cement. Both cements created amorphous and crystalline apatites at the interface depending on the type of mechanical loading. Remineralization, lower stress concentration and resistance to deformation after mechanical loading improved the sealing of the GIC-dentin interface. In vitro oral function will favor high levels of accumulated energy and permits micropermeability at the RMGIC-dentin interface which will become remineralized. Copyright © 2018 Elsevier Ltd. All rights reserved.

Vocal emotion of humanoid robots: a study from brain mechanism.

PubMed

Wang, Youhui; Hu, Xiaohua; Dai, Weihui; Zhou, Jie; Kuo, Taitzong

2014-01-01

Driven by rapid ongoing advances in humanoid robot, increasing attention has been shifted into the issue of emotion intelligence of AI robots to facilitate the communication between man-machines and human beings, especially for the vocal emotion in interactive system of future humanoid robots. This paper explored the brain mechanism of vocal emotion by studying previous researches and developed an experiment to observe the brain response by fMRI, to analyze vocal emotion of human beings. Findings in this paper provided a new approach to design and evaluate the vocal emotion of humanoid robots based on brain mechanism of human beings.

Evaluation of the phase properties of hydrating cement composite using simulated nanoindentation technique

NASA Astrophysics Data System (ADS)

Gautham, S.; Sindu, B. S.; Sasmal, Saptarshi

2017-10-01

Properties and distribution of the products formed during the hydration of cementitious composite at the microlevel are investigated using a nanoindentation technique. First, numerical nanoindentation using nonlinear contact mechanics is carried out on three different phase compositions of cement paste, viz. mono-phase Tri-calcium Silicate (C3S), Di-calcium Silicate (C2S) and Calcium-Silicate-Hydrate (CSH) individually), bi-phase (C3S-CSH, C2S-CSH) and multi-phase (more than 10 individual phases including water pores). To reflect the multi-phase characteristics of hydrating cement composite, a discretized multi-phase microstructural model of cement composite during the progression of hydration is developed. Further, a grid indentation technique for simulated nanoindentation is established, and employed to evaluate the mechanical characteristics of the hydrated multi-phase cement paste. The properties obtained from the numerical studies are compared with those obtained from experimental grid nanoindentation. The influence of composition and distribution of individual phase properties on the properties obtained from indentation are closely investigated. The study paves the way to establishing the procedure for simulated grid nanoindentation to evaluate the mechanical properties of heterogeneous composites, and facilitates the design of experimental nanoindentation.

Effects of diazinon on the lymphocytic cholinergic system of Nile tilapia fish (Oreochromis niloticus).

PubMed

Toledo-Ibarra, G A; Díaz-Resendiz, K J G; Pavón-Romero, L; Rojas-García, A E; Medina-Díaz, I M; Girón-Pérez, M I

2016-08-01

Fish rearing under intensive farming conditions can be easily disturbed by pesticides, substances that have immunotoxic properties and may predispose to infections. Organophosphorus pesticides (OPs) are widely used in agricultural activities; however, the mechanism of immunotoxicity of these substances is unclear. The aim of this study was to evaluate the effect of diazinon pesticides (OPs) on the cholinergic system of immune cells as a possible target of OP immunotoxicity. We evaluated ACh levels and cholinergic (nicotinic and muscarinic) receptor concentration. Additionally, AChE activity was evaluated in mononuclear cells of Nile tilapia (Oreochromis niloticus), a freshwater fish mostly cultivated in tropical regions around the world. The obtained results indicate that acute exposure to diazinon induces an increase in ACh concentration and a decrease in nAChR and mAChR concentrations and AChE activity in fish immune cells, This suggests that the non-neuronal lymphocytic cholinergic system may be the main target in the mechanism of OP immunotoxicity. This study contributes to the understanding of the mechanisms of immunotoxicity of pollutants and may help to take actions for animal health improvement. Copyright © 2016 Elsevier B.V. All rights reserved.

Review of gastroesophageal reflux disease (GERD) in the diabetic patient.

PubMed

Punjabi, Paawan; Hira, Angela; Prasad, Shanti; Wang, Xiangbing; Chokhavatia, Sita

2015-09-01

This article reviews the known pathophysiological mechanisms of comorbid gastroesophageal reflux disease (GERD) in the diabetic patient, discusses therapeutic options in care, and provides an approach to its evaluation and management. We searched for review articles published in the past 10 years through a PubMed search using the filters diabetes mellitus, GERD, pathophysiology, and management. The search only yielded a handful of articles, so we independently included relevant studies from these review articles along with related citations as suggested by PubMed. We found diabetic patients are more prone to developing GERD and may present with atypical manifestations. A number of mechanisms have been proposed to elucidate the connection between these two diseases. Studies involving treatment options for comorbid disease suggest conflicting drug-drug interactions. Currently, there are no published guidelines specifically for the evaluation and management of GERD in the diabetic patient. Although there are several proposed mechanisms for the higher prevalence of GERD in the diabetic patient, this complex interrelationship requires further research. Understanding the pathophysiology will help direct diagnostic evaluation. In our review, we propose a management algorithm for GERD in the diabetic patient. © 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

Computerized approaches to enhance understanding of organic reaction mechanisms: CAN reaction mechanisms and CPLEX prelaboratory methodology

NASA Astrophysics Data System (ADS)

Al-Shammari, Abdulrahman G. Alhamzani

2008-10-01

Two approaches to enhance the understanding of organic reaction mechanisms are described. First, a new method for teaching organic reaction mechanisms that can be used in a Computer-Assisted Instruction (CAI) environment is proposed and tested (Chapter 1). The method concentrates upon the important intermediate structures, which are assumed to be on the reaction coordinate, and which can be evaluated and graded by currently available computer techniques. At the same time, the "curved arrows" that show the electron flow in a reaction mechanism are neglected, since they cannot be evaluated and graded with currently available computer techniques. By allowing student practice for learning organic reaction mechanisms using the Curved Arrow Neglect (CAN) method within a "Practice Makes Perfect" CAI method, student performance in the drawing of traditional reaction mechanisms, in which students had to include the "curved arrows" on their written classroom exams, was significantly enhanced. Second, computerized prelaboratory experiments (CPLEX) for organic chemistry laboratory 1 & 2 courses have been created, used, and evaluated (Chapters 2 and 3). These computerized prelabs are unique because they combine both "dry lab" actions with detailed animations of the actual chemistry occurring at the molecular level. The "dry lab" serves to simulate the actual physical manipulations of equipment and chemicals that occur in the laboratory experiment through the use of drag-and-drop computer technology. At the same time, these physical actions are accompanied on a separate part of the computer screen by animations showing the chemistry at the molecular level that is occurring in the experiment. These CPLEX modules were made into Internet accessible modules. The students were allowed to access the CPLEX modules prior to performing the actual laboratory experiment. A detailed evaluation of students' perception of the modules was accomplished via survey methodology during the entire implementation process over the course of three semesters. Results of the survey data indicate that students thought that they better understood the chemical principles and procedures of the laboratory experiment. Interestingly, students prefer the CPLEX prelaboratory materials, compared to the traditional textbooks, by a wide margin (Chapter 2). The utility of CPLEX was further demonstrated by enabling a study of the effectiveness of animated reaction mechanisms to promote student learning. While most instructors believe that animated mechanisms aid student understanding of reactions, there has been no quantitative data to-date to support this view. In this work, a quantitative study, using an experimental/control group study, was conducted to provide data on the effectiveness of animated reaction mechanisms to promote student learning. Analysis of student answers, using an appropriate rubric, demonstrated that there was a statistically significant improvement in students' scores in the mechanistic question of a pre-laboratory quiz in the post-treatment results of the experimental group which had had access to the animated reaction mechanisms (Chapter 3).

Selection, Evaluation, and Modification of a Standard Operating Procedure as a Mechanism for Introducing an Undergraduate Student to Chemical Research: A Case Study

ERIC Educational Resources Information Center

Claycomb, Gregory D.; Venable, Frances A.

2015-01-01

In an effort to broaden the selection of research opportunities available to a student registered in a one-semester, upper-level independent study course at a primarily undergraduate institution (PUI), a highly motivated student was asked to select, evaluate, and modify a standard operating procedure (SOP). The student gained valuable experience…

Phenomenological and mechanics aspects of nondestructive evaluation and characterization by sound and ultrasound of material and fracture properties

NASA Technical Reports Server (NTRS)

Fu, L. S. W.

1982-01-01

Developments in fracture mechanics and elastic wave theory enhance the understanding of many physical phenomena in a mathematical context. Available literature in the material, and fracture characterization by NDT, and the related mathematical methods in mechanics that provide fundamental underlying principles for its interpretation and evaluation are reviewed. Information on the energy release mechanism of defects and the interaction of microstructures within the material is basic in the formulation of the mechanics problems that supply guidance for nondestructive evaluation (NDE).

Research on the teaching evaluation reform of agricultural eco-environmental protection specialties under the background of deep integration of production and education

NASA Astrophysics Data System (ADS)

Ma, Guosheng

2018-02-01

With the implementation of the personnel training mode of deep integration between production and education, the original evaluation method cannot adapt to the goal of personnel training, so that the traditional teaching evaluation methods need to be reformed urgently. This paper studies and analyzes the four main problems in the teaching evaluation of agricultural eco-environmental protection specialties, and puts forward three measures to reform the teaching evaluation methods: establishing diversified evaluation indexes, establishing diversified evaluation subjects, and establishing diversified evaluation feedback mechanisms.

Particle size concentration distribution and influences on exhaled breath particles in mechanically ventilated patients.

PubMed

Wan, Gwo-Hwa; Wu, Chieh-Liang; Chen, Yi-Fang; Huang, Sheng-Hsiu; Wang, Yu-Ling; Chen, Chun-Wan

2014-01-01

Humans produce exhaled breath particles (EBPs) during various breath activities, such as normal breathing, coughing, talking, and sneezing. Airborne transmission risk exists when EBPs have attached pathogens. Until recently, few investigations had evaluated the size and concentration distributions of EBPs from mechanically ventilated patients with different ventilation mode settings. This study thus broke new ground by not only evaluating the size concentration distributions of EBPs in mechanically ventilated patients, but also investigating the relationship between EBP level and positive expiratory end airway pressure (PEEP), tidal volume, and pneumonia. This investigation recruited mechanically ventilated patients, with and without pneumonia, aged 20 years old and above, from the respiratory intensive care unit of a medical center. Concentration distributions of EBPs from mechanically ventilated patients were analyzed with an optical particle analyzer. This study finds that EBP concentrations from mechanically ventilated patients during normal breathing were in the range 0.47-2,554.04 particles/breath (0.001-4.644 particles/mL). EBP concentrations did not differ significantly between the volume control and pressure control modes of the ventilation settings in the mechanically ventilated patients. The patient EBPs were sized below 5 µm, and 80% of them ranged from 0.3 to 1.0 µm. The EBPs concentrations in patients with high PEEP (> 5 cmH₂O) clearly exceeded those in patients with low PEEP (≤ 5 cmH₂O). Additionally, a significant negative association existed between pneumonia duration and EBPs concentration. However, tidal volume was not related to EBPs concentration.

Effect of treatment pressure on treatment quality and bending properties of red pine lumber

Treesearch

Patricia K. Lebow; Stan T. Lebow; William J. Nelson

2010-01-01

Although higher treatment pressures have the potential to improve preservative penetration, higher pressures may possibly result in greater reduction in mechanical properties. The present study evaluated the effect of treatment pressure on the treatment quality and mechanical properties of red pine (Pinus resinosa Ait.) lumber. End-matched sections of red pine lumber...

Education and Coronary Heart Disease Risk: Potential Mechanisms Such as Literacy, Perceived Constraints, and Depressive Symptoms

ERIC Educational Resources Information Center

Loucks, Eric B.; Gilman, Stephen E.; Howe, Chanelle J.; Kawachi, Ichiro; Kubzansky, Laura D.; Rudd, Rima E.; Martin, Laurie T.; Nandi, Arijit; Wilhelm, Aude; Buka, Stephen L.

2015-01-01

Objective: Education is inversely associated with coronary heart disease (CHD) risk; however the mechanisms are poorly understood. The study objectives were to evaluate the extent to which rarely measured factors (literacy, time preference, sense of control) and more commonly measured factors (income, depressive symptomatology, body mass index) in…

Dense Neighborhoods and Mechanisms of Learning: Evidence from Children with Phonological Delay

ERIC Educational Resources Information Center

Gierut, Judith A.; Morrisette, Michele L.

2015-01-01

There is a noted advantage of dense neighborhoods in language acquisition, but the learning mechanism that drives the effect is not well understood. Two hypotheses--long-term auditory word priming and phonological working memory--have been advanced in the literature as viable accounts. These were evaluated in two treatment studies enrolling twelve…

Susceptibility of volcanic ash-influenced soil in northern Idaho to mechanical compaction

Treesearch

Deborah S. Page-Dumroese

1993-01-01

Timber harvesting and mechanical site preparation can reduce site productivity if they excessively disturb or compact the soil. Volcanic ash-influenced soils with low undisturbed bulk densities and rock content are particularly susceptible. This study evaluates the effects of harvesting and site preparation on changes in the bulk density of ash-influenced forest soils...

Application of neural networks in the acousto-ultrasonic evaluation of metal-matrix composite specimens

NASA Technical Reports Server (NTRS)

Cios, Krzysztof J.; Tjia, Robert E.; Vary, Alex; Kautz, Harold E.

1992-01-01

Acousto-ultrasonics (AU) is a nondestructive evaluation (NDE) technique that was devised for the testing of various types of composite materials. A study has been done to determine how effectively the AU technique may be applied to metal-matrix composites (MMCs). The authors use the results and data obtained from that study and apply neural networks to them, particularly in the assessment of mechanical property variations of a specimen from AU measurements. It is assumed that there is no information concerning the important features of the AU signal which relate to the mechanical properties of the specimen. Minimally processed AU measurements are used while relying on the network's ability to extract the significant features of the signal.

Evaluation of biodegradable plastics for rubber seedling applications

NASA Astrophysics Data System (ADS)

Mansor, Mohd Khairulniza; Dayang Habibah A. I., H.; Kamal, Mazlina Mustafa

2015-08-01

The main negative consequence of conventional plastics in agriculture is related to handling the wastes plasticand the associated environmental impact. Hence, a study of different types of potentially biodegradable plastics used for nursery applications have been evaluated on its mechanical,water absorption propertiesand Fourier transform infra-red (FTIR) spectroscopy. Supplied samples from different companies were designated as SF, CF and CO. Most of the polybags exhibited mechanical properties quite similar to the conventional plastics (polybag LDPE). CO polybag which is based on PVA however had extensively higher tensile strength and water absorption properties. FTIR study revealed a characteristics absorbance of conventional plastic, SF, CF and CO biodegradable polybag are associated with polyethylene, poly(butylene adipate-co-terephthalate) (PBAT), polyethylene and polyvinyl alcohol (PVA) structures respectively.

Laser-assisted manufacturing of super-insulation materials

NASA Astrophysics Data System (ADS)

Wang, Zhen; Zhang, Tao; Park, Byung Kyu; Lee, Woo Il; Hwang, David

2017-02-01

Being lightweight materials with good mechanical and thermal properties, hollow glass micro-particles (HGMPs) have been widely studied for multiple applications. In this study, it is shown that by using reduced binder fraction diluted in solvent, enables minimal contacts among the HGMPs assisted by a natural capillary trend, as confirmed by optical and electron microscope imaging. Such material architecture fabricated in a composite level proves to have enhanced thermal insulation performance through quantitative thermal conductivity measurement. Mechanical strength has also been evaluated in terms of particle-binder bonding by tensile test via in-situ microscope inspection. Effect of laser treatment was examined for further improvement of thermal and mechanical properties by selective binder removal and efficient redistribution of remaining binder components. The fabricated composite materials have potential applications to building insulation materials for their scalable manufacturing nature, improved thermal insulation performance and reasonable mechanical strength. Further studies are needed to understand mechanical and thermal properties of the resulting composites, and key fabrication mechanisms involved with laser treatment of complex multi-component and multi-phase systems.

Evaluation of fracture toughness and mechanical properties of ternary thiol-ene-methacrylate systems as resin matrix for dental restorative composites.

PubMed

Beigi, Saeed; Yeganeh, Hamid; Atai, Mohammad

2013-07-01

Study and evaluation of fracture toughness, flexural and dynamic mechanical properties, and crosslink density of ternary thiol-ene-methacrylate systems and comparison with corresponding conventional methacrylate system were considered in the present study. Urethane tetra allyl ether monomer (UTAE) was synthesized as ene monomer. Different formulations were prepared based on combination of UTAE, BisGMA/TEGDMA and a tetrathiol monomer (PETMP). The photocuring reaction was conducted under visible light using BD/CQ combination as photoinitiator system. Mechanical properties were evaluated via measuring flexural strength, flexural modulus and fracture toughness. Scanning electron microscopy (SEM) was utilized to study the morphology of the fractured specimen's cross section. Viscoelastic properties of the samples were also determined by dynamic mechanical thermal analysis (DMTA). The same study was performed on a conventional methacrylate system. The data were analyzed and compared by ANOVA and Tukey HSD tests (significance level=0.05). The results showed improvement in fracture toughness of the specimens containing thiol-ene moieties. DMTA revealed a lower glass transition temperature and more homogenous structure for thiol-ene containing specimens in comparison to the system containing merely methacrylate monomer. The flexural modulus and flexural strength of the specimens with higher thiol-ene content were lower than the neat methacrylate system. The SEM micrographs of the fractured surface of specimens with higher methacrylate content were smooth and mirror-like (shiny) which represent brittle fracture. The thiol-ene-methacrylate system can be used as resin matrix of dental composites with enhanced fracture toughness in comparison to the methacrylate analogous. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Biocomposites from abaca strands and polypropylene. Part I: Evaluation of the tensile properties.

PubMed

Vilaseca, Fabiola; Valadez-Gonzalez, Alex; Herrera-Franco, Pedro J; Pèlach, M Angels; López, Joan Pere; Mutjé, Pere

2010-01-01

In this paper, abaca strands were used as reinforcement of polypropylene matrix and their tensile mechanical properties were studied. It was found relevant increments on the tensile properties of the abaca strand-PP composites despite the lack of good adhesion at fiber-matrix interface. Afterwards, it was stated the influence of using maleated polypropylene (MAPP) as compatibilizer to promote the interaction between abaca strands and polypropylene. The intrinsic mechanical properties of the reinforcement were evaluated and used for modeling both the tensile strength and elastic modulus of the composites. For these cases, the compatibility factor for the ultimate tensile strength was deduced from the modified rule of mixtures. Additionally, the experimental fiber orientation coefficient was measured, allowing determining the interfacial shear strengths of the composites and the critical fiber length of the abaca strand reinforcement. The mechanical improvement was compared to that obtained for fiberglass-reinforced PP composites and evaluated under an economical and technical point of view.

Chromaffin cells as a model to evaluate mechanisms of cell death and neuroprotective compounds.

PubMed

de Los Rios, Cristobal; Cano-Abad, Maria F; Villarroya, Mercedes; López, Manuela G

2018-01-01

In this review, we show how chromaffin cells have contributed to evaluate neuroprotective compounds with diverse mechanisms of action. Chromaffin cells are considered paraneurons, as they share many common features with neurons: (i) they synthesize, store, and release neurotransmitters upon stimulation and (ii) they express voltage-dependent calcium, sodium, and potassium channels, in addition to a wide variety of receptors. All these characteristics, together with the fact that primary cultures from bovine adrenal glands or chromaffin cells from the tumor pheochromocytoma cell line PC12 are easy to culture, make them an ideal model to study neurotoxic mechanisms and neuroprotective drugs. In the first part of this review, we will analyze the different cytotoxicity models related to calcium dyshomeostasis and neurodegenerative disorders like Alzheimer's or Parkinson's. Along the second part of the review, we describe how different classes of drugs have been evaluated in chromaffin cells to determine their neuroprotective profile in different neurodegenerative-related models.

Achilles tendons from decorin- and biglycan-null mouse models have inferior mechanical and structural properties predicted by an image-based empirical damage model

PubMed Central

Gordon, J.A.; Freedman, B.R.; Zuskov, A.; Iozzo, R.V.; Birk, D.E.; Soslowsky, L.J.

2015-01-01

Achilles tendons are a common source of pain and injury, and their pathology may originate from aberrant structure function relationships. Small leucine rich proteoglycans (SLRPs) influence mechanical and structural properties in a tendon-specific manner. However, their roles in the Achilles tendon have not been defined. The objective of this study was to evaluate the mechanical and structural differences observed in mouse Achilles tendons lacking class I SLRPs; either decorin or biglycan. In addition, empirical modeling techniques based on mechanical and image-based measures were employed. Achilles tendons from decorin-null (Dcn−/−) and biglycan-null (Bgn−/−) C57BL/6 female mice (N=102) were used. Each tendon underwent a dynamic mechanical testing protocol including simultaneous polarized light image capture to evaluate both structural and mechanical properties of each Achilles tendon. An empirical damage model was adapted for application to genetic variation and for use with image based structural properties to predict tendon dynamic mechanical properties. We found that Achilles tendons lacking decorin and biglycan had inferior mechanical and structural properties that were age dependent; and that simple empirical models, based on previously described damage models, were predictive of Achilles tendon dynamic modulus in both decorin- and biglycan-null mice. PMID:25888014

Achilles tendons from decorin- and biglycan-null mouse models have inferior mechanical and structural properties predicted by an image-based empirical damage model.

PubMed

Gordon, J A; Freedman, B R; Zuskov, A; Iozzo, R V; Birk, D E; Soslowsky, L J

2015-07-16

Achilles tendons are a common source of pain and injury, and their pathology may originate from aberrant structure function relationships. Small leucine rich proteoglycans (SLRPs) influence mechanical and structural properties in a tendon-specific manner. However, their roles in the Achilles tendon have not been defined. The objective of this study was to evaluate the mechanical and structural differences observed in mouse Achilles tendons lacking class I SLRPs; either decorin or biglycan. In addition, empirical modeling techniques based on mechanical and image-based measures were employed. Achilles tendons from decorin-null (Dcn(-/-)) and biglycan-null (Bgn(-/-)) C57BL/6 female mice (N=102) were used. Each tendon underwent a dynamic mechanical testing protocol including simultaneous polarized light image capture to evaluate both structural and mechanical properties of each Achilles tendon. An empirical damage model was adapted for application to genetic variation and for use with image based structural properties to predict tendon dynamic mechanical properties. We found that Achilles tendons lacking decorin and biglycan had inferior mechanical and structural properties that were age dependent; and that simple empirical models, based on previously described damage models, were predictive of Achilles tendon dynamic modulus in both decorin- and biglycan-null mice. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Systematic Review Exploring the Social Cognitive Theory of Self-Regulation as a Framework for Chronic Health Condition Interventions

PubMed Central

Tougas, Michelle E.; Hayden, Jill A.; McGrath, Patrick J.; Huguet, Anna; Rozario, Sharlene

2015-01-01

Background Theory is often recommended as a framework for guiding hypothesized mechanisms of treatment effect. However, there is limited guidance about how to use theory in intervention development. Methods We conducted a systematic review to provide an exemplar review evaluating the extent to which use of theory is identified and incorporated within existing interventions. We searched electronic databases PubMed, PsycINFO, CENTRAL, and EMBASE from inception to May 2014. We searched clinicaltrials.gov for registered protocols, reference lists of relevant systematic reviews and included studies, and conducted a citation search in Web of Science. We included peer-reviewed publications of interventions that referenced the social cognitive theory of self-regulation as a framework for interventions to manage chronic health conditions. Two reviewers independently assessed articles for eligibility. We contacted all authors of included studies for information detailing intervention content. We describe how often theory mechanisms were addressed by interventions, and report intervention characteristics used to address theory. Results Of 202 articles that reported using the social cognitive theory of self-regulation, 52% failed to incorporate self-monitoring, a main theory component, and were therefore excluded. We included 35 interventions that adequately used the theory framework. Intervention characteristics were often poorly reported in peer-reviewed publications, 21 of 35 interventions incorporated characteristics that addressed each of the main theory components. Each intervention addressed, on average, six of eight self-monitoring mechanisms, two of five self-judgement mechanisms, and one of three self-evaluation mechanisms. The self-monitoring mechanisms ‘Feedback’ and ‘Consistency’ were addressed by all interventions, whereas the self-evaluation mechanisms ‘Self-incentives’ and ‘External rewards’ were addressed by six and four interventions, respectively. The present review establishes that systematic review is a feasible method of identifying use of theory as a conceptual framework for existing interventions. We identified the social cognitive theory of self-regulation as a feasible framework to guide intervention development for chronic health conditions. PMID:26252889

Evaluation of isoprene degradation in the detailed tropospheric chemical mechanism, MCM v3, using environmental chamber data

NASA Astrophysics Data System (ADS)

Pinho, P. G.; Pio, C. A.; Jenkin, M. E.

The isoprene degradation mechanism included in version 3 of the Master Chemical Mechanism (MCM v3) has been evaluated and refined, using the Statewide Air Pollution Research Center (SAPRC) environmental chamber datasets on the photo-oxidation of isoprene and its degradation products, methacrolein (MACR) and methylvinyl ketone (MVK). Prior to this, the MCM v3 butane degradation chemistry was also evaluated using chamber data on the photo-oxidation of butane, and its degradation products, methylethyl ketone (MEK), acetaldehyde (CH 3CHO) and formaldehyde (HCHO), in conjunction with an initial evaluation of the chamber-dependent auxiliary mechanisms for the series of relevant chambers. The MCM v3 mechanisms for both isoprene and butane generally performed well and were found to provide an acceptable reaction framework for describing the NO x-photo-oxidation experiments on the above systems, although a number of parameter modifications and refinements were identified which resulted in an improved performance. All these relate to the magnitude of sources of free radicals from organic chemical process, such as carbonyl photolysis rates and the yields of radicals from the reactions of O 3 with unsaturated oxygenates, and specific recommendations are made for refinements. In addition to this, it was necessary to include a representation of the reactions of O( 3P) with isoprene, MACR and MVK (which were not previously treated in MCM v3), and conclusions are drawn concerning the required extent of free radical formation from these reactions. Throughout the study, the performance of MCM v3 was also compared with that of the SAPRC-99 mechanism, which was developed and optimized in conjunction with the chamber datasets.

Model-based analysis of the effect of different operating conditions on fouling mechanisms in a membrane bioreactor.

PubMed

Sabia, Gianpaolo; Ferraris, Marco; Spagni, Alessandro

2016-01-01

This study proposes a model-based evaluation of the effect of different operating conditions with and without pre-denitrification treatment and applying three different solids retention times on the fouling mechanisms involved in membrane bioreactors (MBRs). A total of 11 fouling models obtained from literature were used to fit the transmembrane pressure variations measured in a pilot-scale MBR treating real wastewater for more than 1 year. The results showed that all the models represent reasonable descriptions of the fouling processes in the MBR tested. The model-based analysis confirmed that membrane fouling started by pore blocking (complete blocking model) and by a reduction of the pore diameter (standard blocking) while cake filtration became the dominant fouling mechanism over long-term operation. However, the different fouling mechanisms occurred almost simultaneously making it rather difficult to identify each one. The membrane "history" (i.e. age, lifespan, etc.) seems the most important factor affecting the fouling mechanism more than the applied operating conditions. Nonlinear regression of the most complex models (combined models) evaluated in this study sometimes demonstrated unreliable parameter estimates suggesting that the four basic fouling models (complete, standard, intermediate blocking and cake filtration) contain enough details to represent a reasonable description of the main fouling processes occurring in MBRs.

Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering.

PubMed

Jahnavi, S; Saravanan, U; Arthi, N; Bhuvaneshwar, G S; Kumary, T V; Rajan, S; Verma, R S

2017-04-01

Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44 + , αSMA + , Vimentin + and CD105 - human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. Copyright © 2016 Elsevier B.V. All rights reserved.

An Empirical Study of the Transmission Power Setting for Bluetooth-Based Indoor Localization Mechanisms

PubMed Central

Castillo-Cara, Manuel; Lovón-Melgarejo, Jesús; Bravo-Rocca, Gusseppe; Orozco-Barbosa, Luis; García-Varea, Ismael

2017-01-01

Nowadays, there is a great interest in developing accurate wireless indoor localization mechanisms enabling the implementation of many consumer-oriented services. Among the many proposals, wireless indoor localization mechanisms based on the Received Signal Strength Indication (RSSI) are being widely explored. Most studies have focused on the evaluation of the capabilities of different mobile device brands and wireless network technologies. Furthermore, different parameters and algorithms have been proposed as a means of improving the accuracy of wireless-based localization mechanisms. In this paper, we focus on the tuning of the RSSI fingerprint to be used in the implementation of a Bluetooth Low Energy 4.0 (BLE4.0) Bluetooth localization mechanism. Following a holistic approach, we start by assessing the capabilities of two Bluetooth sensor/receiver devices. We then evaluate the relevance of the RSSI fingerprint reported by each BLE4.0 beacon operating at various transmission power levels using feature selection techniques. Based on our findings, we use two classification algorithms in order to improve the setting of the transmission power levels of each of the BLE4.0 beacons. Our main findings show that our proposal can greatly improve the localization accuracy by setting a custom transmission power level for each BLE4.0 beacon. PMID:28590413

An Empirical Study of the Transmission Power Setting for Bluetooth-Based Indoor Localization Mechanisms.

PubMed

Castillo-Cara, Manuel; Lovón-Melgarejo, Jesús; Bravo-Rocca, Gusseppe; Orozco-Barbosa, Luis; García-Varea, Ismael

2017-06-07

Nowadays, there is a great interest in developing accurate wireless indoor localization mechanisms enabling the implementation of many consumer-oriented services. Among the many proposals, wireless indoor localization mechanisms based on the Received Signal Strength Indication (RSSI) are being widely explored. Most studies have focused on the evaluation of the capabilities of different mobile device brands and wireless network technologies. Furthermore, different parameters and algorithms have been proposed as a means of improving the accuracy of wireless-based localization mechanisms. In this paper, we focus on the tuning of the RSSI fingerprint to be used in the implementation of a Bluetooth Low Energy 4.0 (BLE4.0) Bluetooth localization mechanism. Following a holistic approach, we start by assessing the capabilities of two Bluetooth sensor/receiver devices. We then evaluate the relevance of the RSSI fingerprint reported by each BLE4.0 beacon operating at various transmission power levels using feature selection techniques. Based on our findings, we use two classification algorithms in order to improve the setting of the transmission power levels of each of the BLE4.0 beacons. Our main findings show that our proposal can greatly improve the localization accuracy by setting a custom transmission power level for each BLE4.0 beacon.

Extended performance electric propulsion power processor design study. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Biess, J. J.; Inouye, L. Y.; Schoenfeld, A. D.

1977-01-01

Several power processor design concepts were evaluated and compared. Emphasis was placed on a 30cm ion thruster power processor with a beam supply rating of 2.2kW to 10kW. Extensions in power processor performance were defined and were designed in sufficient detail to determine efficiency, component weight, part count, reliability and thermal control. Preliminary electrical design, mechanical design, and thermal analysis were performed on a 6kW power transformer for the beam supply. Bi-Mod mechanical, structural, and thermal control configurations were evaluated for the power processor, and preliminary estimates of mechanical weight were determined. A program development plan was formulated that outlines the work breakdown structure for the development, qualification and fabrication of the power processor flight hardware.

Development of a degradable composite for orthopaedic use: mechanical evaluation of an hydroxyapatite-polyhydroxybutyrate composite material.

PubMed

Boeree, N R; Dove, J; Cooper, J J; Knowles, J; Hastings, G W

1993-08-01

This study evaluates the mechanical properties of a composite material comprising polyhydroxybutyrate with hydroxyapatite added in proportions varying from 0 to 50%. Among the three methods of production, injection moulding was found to result in the most satisfactory mechanical properties. The tensile and compressive strength and the modulus of elasticity of composite produced in this way fell within the range for fresh human bone from different anatomical sites. With the additional advantages of biocompatibility, biodegradability and the potential for piezoelectric stimulation of new local bone formation, it was concluded that the injection-moulded composite material has considerable potential for use in orthopaedic surgery, both as a material to construct certain orthopaedic implants and as an alternative to corticocancellous bone graft.

Hygrothermal damage mechanisms in graphite-epoxy composites

NASA Technical Reports Server (NTRS)

Crossman, F. W.; Mauri, R. E.; Warren, W. J.

1979-01-01

T300/5209 and T300/5208 graphite epoxy laminates were studied experimentally and analytically in order to: (1) determine the coupling between applied stress, internal residual stress, and moisture sorption kinetics; (2) examine the microscopic damage mechanisms due to hygrothermal cycling; (3) evaluate the effect of absorbed moisture and hygrothermal cycling on inplane shear response; (4) determine the permanent loss of interfacial bond strength after moisture absorption and drying; and (5) evaluate the three dimensional stress state in laminates under a combination of hygroscopic, thermal, and mechanical loads. Specimens were conditioned to equilibrium moisture content under steady exposure to 55% or 95% RH at 70 C or 93 C. Some specimens were tested subsequent to moisture conditioning and 100 cycles between -54 C and either 70 C or 93 C.

Understanding the workplace culture of a special care nursery.

PubMed

Wilson, Valerie J; McCormack, Brendan G; Ives, Glenice

2005-04-01

This paper presents findings from the first phase of a research study focusing on implementation and evaluation of emancipatory practice development strategies. Understanding the culture of practice is essential to undertaking effective developments in practice. Culture is a dominant feature of discussions about modernizing health care, yet few studies have been undertaken that systematically evaluate the development of effective practice cultures. The study intervention is that of emancipatory practice development with an integrated evaluation approach based on Realistic Evaluation. The aim of Realistic Evaluation is to evaluate relationships between Context (setting), Mechanism (process characteristics) and Outcome (arising from the context-mechanism configuration). This first phase of the study focuses on uncovering the context (in particular the culture) of the Special Care Nursery in order to evaluate the emancipatory practice development processes and outcomes. Data collection methods included survey, participant observation and interview. Cognitive mapping, constant comparative method and coding were used to analyse the data. Findings. Four key categories were identified: Teamwork, Learning in Practice, Inevitability of Change and Family-Centred Care and collectively these formed a central category of Core Values and Beliefs. A number of themes were identified in each category, and reflected tensions that existed between differing values and beliefs within the culture of the unit. Understanding values and beliefs is an important part of understanding a workplace culture. Whilst survey methods are capable of outlining espoused workplace characteristics, observation of staff interactions and perceptions gives an understanding of culture as a living entity manifested through interpersonal relationships. Attempts at changing workplace cultures should start from the clarification of values held among staff in that culture.

Issues in development, evaluation, and use of the NASA Preflight Adaptation Trainer (PAT)

NASA Technical Reports Server (NTRS)

Lane, Norman E.; Kennedy, Robert S.

1988-01-01

The Preflight Adaptation Trainer (PAT) is intended to reduce or alleviate space adaptation syndrome by providing opportunities for portions of that adaptation to occur under normal gravity conditions prior to space flight. Since the adaptation aspects of the PAT objectives involve modification not only of the behavior of the trainee, but also of sensiomotor skills which underly the behavioral generation, the defining of training objectives of the PAT utilizes four mechanisms: familiarization, demonstration, training and adaptation. These mechanisms serve as structural reference points for evaluation, drive the content and organization of the training procedures, and help to define the roles of the PAT instructors and operators. It was determined that three psychomotor properties are most critical for PAT evaluation: reliability; sensitivity; and relevance. It is cause for concern that the number of measures available to examine PAT effects exceed those that can be properly studied with the available sample sizes; special attention will be required in selection of the candidate measure set. The issues in PAT use and application within a training system context are addressed through linking the three training related mechanisms of familiarization, demonstration and training to the fourth mechanism, adaptation.

How Hedstrom files fail during clinical use? A retrieval study based on SEM, optical microscopy and micro-XCT analysis.

PubMed

Zinelis, Spiros; Al Jabbari, Youssef S

2018-05-01

This study was conducted to evaluate the failure mechanism of clinically failed Hedstrom (H)-files. Discarded H-files (n=160) from #8 to #40 ISO sizes were collected from different dental clinics. Retrieved files were classified according to their macroscopic appearance and they were investigated under scanning electron microscopy (SEM) and X-ray micro-computed tomography (mXCT). Then the files were embedded in resin along their longitudinal axis and after metallographic grinding and polishing, studied under an incident light microscope. The macroscopic evaluation showed that small ISO sizes (#08-#15) failed by extensive plastic deformation, while larger sizes (≥#20) tended to fracture. Light microscopy and mXCT results coincided showing that unused and plastically deformed files were free of internal defects, while fractured files demonstrate the presence of intense cracking in the flute region. SEM analysis revealed the presence of striations attributed to the fatigue mechanism. Secondary cracks were also identified by optical microscopy and their distribution was correlated to fatigue under bending loading. Experimental results demonstrated that while overloading of cutting instruments is the predominating failure mechanism of small file sizes (#08-#15), fatigue should be considered the fracture mechanism for larger sizes (≥#20).

Energy demand in patients with stroke who are sedated and receiving mechanical ventilation.

PubMed

Bardutzky, Juergen; Georgiadis, Dimitrios; Kollmar, Rainer; Schwarz, Stefan; Schwab, Stefan

2004-02-01

The purpose of this study was 1) to determine the total energy expenditure (TEE) in patients with acute stroke who are sedated and receiving mechanical ventilation; and 2) to compare the TEE between patients with ischemic and hemorrhagic stroke. Thirty-four consecutive nonseptic patients with stroke requiring sedation and mechanical ventilation were prospectively examined; 13 of the patients had experienced spontaneous intracerebral hemorrhage and 21 cerebral ischemia of the middle cerebral artery territory. The TEE was evaluated using continuous indirect calorimetry during the first 5 days after admission to the intensive care unit. The serum albumin concentration was determined on admission and on Day 5. The TEE varied from 1560 +/- 240 to 1623 +/- 251 kcal/day. A highly significant correlation between the TEE and the basal energy expenditure (BEE), as predicted using the Harris-Benedict equation, was observed in both groups. No significant differences in the TEE were detected between the two groups or among the different study days. A highly significant correlation was found between the TEE and the predicted BEE in patients with acute stroke who have been sedated and have received mechanical ventilation. No significant differences were observed between patients with hemorrhagic and ischemic stroke. Further studies are needed to evaluate the effect of tailored feeding on clinical outcome in these patients.

Studies on densification, mechanical, micro-structural and structure–properties relationship of magnesium aluminate spinel refractory aggregates prepared from Indian magnesite

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

Ghosh, Chandrima; Ghosh, Arup; Haldar, Manas Kamal, E-mail: manashaldar@cgcri.res.in

The present work intends to study the development of magnesium aluminate spinel aggregates from Indian magnesite in a single firing stage. The raw magnesite has been evaluated in terms of chemical analysis, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, and X-ray diffraction. The experimental batch containing Indian magnesite and calcined alumina has been sintered in the temperature range of 1550 °C–1700 °C. The sintered material has been characterized in terms of physico-chemical properties like bulk density, apparent porosity, true density, relative density and thermo-mechanical/mechanical properties like hot modulus of rupture, thermal shock resistance, cold modulus of rupture and structural propertiesmore » by X-ray diffraction in terms of phase identification and evaluation of crystal structure parameters of corresponding phases by Rietveld analysis. The microstructures developed at different temperatures have been analyzed by field emission scanning electron microscope study and compositional analysis of the developed phase has been carried out by energy dispersive X-ray study. - Highlights: • The studies have been done to characterize the developed magnesium aluminate spinel. • The studies reveal correlation between refractory behavior of spinel and developed microstructures. • The studies show the values of lattice parameters of developed phases.« less

Assessment of weaning indexes based on diaphragm activity in mechanically ventilated subjects after cardiovascular surgery. A pilot study

PubMed Central

Ortega, Isabel Cristina Muñoz; Valdivieso, Alher Mauricio Hernández; Lopez, Joan Francesc Alonso; Villanueva, Miguel Ángel Mañanas; Lopez, Luis Horacio Atehortúa

2017-01-01

Objective The aim of this pilot study was to evaluate the feasibility of surface electromyographic signal derived indexes for the prediction of weaning outcomes among mechanically ventilated subjects after cardiac surgery. Methods A sample of 10 postsurgical adult subjects who received cardiovascular surgery that did not meet the criteria for early extubation were included. Surface electromyographic signals from diaphragm and ventilatory variables were recorded during the weaning process, with the moment determined by the medical staff according to their expertise. Several indexes of respiratory muscle expenditure from surface electromyography using linear and non-linear processing techniques were evaluated. Two groups were compared: successfully and unsuccessfully weaned patients. Results The obtained indexes allow estimation of the diaphragm activity of each subject, showing a correlation between high expenditure and weaning test failure. Conclusion Surface electromyography is becoming a promising procedure for assessing the state of mechanically ventilated patients, even in complex situations such as those that involve a patient after cardiovascular surgery. PMID:28977261

Anti-nociceptive, anti-hyperalgesic and anti-arthritic activity of amides and extract obtained from Piper amalago in rodents.

PubMed

da Silva Arrigo, Jucicléia; Balen, Eloise; Júnior, Ubirajara Lanza; da Silva Mota, Jonas; Iwamoto, Renan Donomae; Barison, Andersson; Sugizaki, Mario Mateus; Leite Kassuya, Cândida Aparecida

2016-02-17

Piper amalago (Piperaceae) has been used in folk medicine as an analgesic. This study aimed to evaluate the pharmacological effects of extract and pure amides obtained from P. amalago on pain to provide a pharmacological basis for their use in traditional medicine. This study evaluated the anti-nociceptive, anti-hyperalgesic, anti-arthritic and anti-depressive activities of the ethanolic extract of P. amalago (EEPA) and the amides N-[7-(3',4'-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl] pyrrolidine (1) and N-[7-(3',4'-methylenedioxyphenyl)-2(E),4(E)-heptadienoyl] pyrrolidine (2) obtained from P. amalago in animal models. Mice treated daily with EEPA (100mg/kg, p.o.) were assayed for 20 days for knee edema (micrometer measurement), mechanical hyperalgesia (analgesiometer analysis), heat sensitivity and immobility (forced swim test) in the Complete Freund's Adjuvant (CFA) model. Cold (acetone test) and mechanical hyperalgesia (electronic von Frey analysis) responses were evaluated for 15 days in rats treated with oral EEPA (100mg/kg) in the spared nerve injury (SNI) model. Meanwhile, mice were evaluated for carrageenan-induced edema and mechanical hyperalgesia and for nociception using the formalin model after a single administration of EEPA (100mg/kg) or amides 1 and 2 (1mg/kg). Amides (1) and (2) were detected and isolated from the EEPA. The EEPA inhibited mechanical hyperalgesia, knee edema, and heat hyperalgesia, but not depressive-like behavior, induced by the intraplantar injection of CFA. When evaluated in the SNI model, the EEPA inhibited mechanical and cold hyperalgesia. The EEPA, 1 and 2 prevented the mechanical hyperalgesia induced by carrageenan and the anti-nociceptive effects in both phases of formalin nociception. The EEPA did not induce alterations in the open field test. The EEPA was effective for inhibition of pain and arthritic parameters but was not effective against depressive-like behavior; additionally, it did not alter locomotor activity. The amides obtained seemed to be the active component(s) present in the EEPA because they proved to be anti-nociceptive and anti-hyperalgesic in models of acute pain. Considering that few drugs are currently available for the treatment of chronic pain, especially neuropathic pain, the present results may have clinical relevance and open new possibilities for the development of new anti-hyperalgesic and anti-arthritic agents from P. amalago. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Using interviews to understand the assignment mechanism in a nonexperimental study: the case of eighth grade algebra.

PubMed

Rickles, Jordan H

2011-10-01

Many inquiries regarding the causal effects of policies or programs are based on research designs where the treatment assignment process is unknown, and thus valid inferences depend on tenuous assumptions about the assignment mechanism. This article draws attention to the importance of understanding the assignment mechanism in policy and program evaluation studies, and illustrates how information collected through interviews can develop a richer understanding of the assignment mechanism. Focusing on the issue of student assignment to algebra in 8th grade, I show how a preliminary data collection effort aimed at understanding the assignment mechanism is particularly beneficial in multisite observational studies in education. The findings, based on ten interviews and administrative data from a large school district, draw attention to the often ignored heterogeneity in the assignment mechanism across schools. These findings likely extend beyond the current research project in question to related educational policy issues such as ability grouping, tracking, differential course taking, and curricular intensity, as well as other social programs in which the assignment mechanism can differ across sites.

3D-printing zirconia implants; a dream or a reality? An in-vitro study evaluating the dimensional accuracy, surface topography and mechanical properties of printed zirconia implant and discs.

PubMed

Osman, Reham B; van der Veen, Albert J; Huiberts, Dennis; Wismeijer, Daniel; Alharbi, Nawal

2017-11-01

The aim of this study was to evaluate the dimensional accuracy, surface topography of a custom designed, 3D-printed zirconia dental implant and the mechanical properties of printed zirconia discs. A custom designed implant was 3D-printed in zirconia using digital light processing technique (DLP). The dimensional accuracy was assessed using the digital-subtraction technique. The mechanical properties were evaluated using biaxial flexure strength test. Three different build angles were adopted to print the specimens for the mechanical test; 0°(Vertical), 45° (Oblique) and 90°(Horizontal) angles. The surface topography, crystallographic phase structure and surface roughness were evaluated using scanning electron microscopy analysis (SEM), X-ray diffractometer and confocal microscopy respectively. The printed implant was dimensionally accurate with a root mean square (RMSE) value of 0.1mm. The Weibull analysis revealed a statistically significant higher characteristic strength (1006.6MPa) of 0° printed specimens compared to the other two groups and no significant difference between 45° (892.2MPa) and 90° (866.7MPa) build angles. SEM analysis revealed cracks, micro-porosities and interconnected pores ranging in size from 196nm to 3.3µm. The mean Ra (arithmetic mean roughness) value of 1.59µm (±0.41) and Rq (root mean squared roughness) value of 1.94µm (±0.47) was found. A crystallographic phase of primarily tetragonal zirconia typical of sintered Yttria tetragonal stabilized zirconia (Y-TZP) was detected. DLP prove to be efficient for printing customized zirconia dental implants with sufficient dimensional accuracy. The mechanical properties showed flexure strength close to those of conventionally produced ceramics. Optimization of the 3D-printing process parameters is still needed to improve the microstructure of the printed objects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimization of mechanical performance of oxidative nano-particle electrode nitrile butadiene rubber conducting polymer actuator.

PubMed

Kim, Baek-Chul; Park, S J; Cho, M S; Lee, Y; Nam, J D; Choi, H R; Koo, J C

2009-12-01

Present work delivers a systematical evaluation of actuation efficiency of a nano-particle electrode conducting polymer actuator fabricated based on Nitrile Butadiene Rubber (NBR). Attempts are made for maximizing mechanical functionality of the nano-particle electrode conducting polymer actuator that can be driven in the air. As the conducting polymer polypyrrole of the actuator is to be fabricated through a chemical oxidation polymerization process that may impose certain limitations on both electrical and mechanical functionality of the actuator, a coordinated study for optimization process of the actuator is necessary for maximizing its performance. In this article actuation behaviors of the nano-particle electrode polypyrrole conducting polymer is studied and an optimization process for the mechanical performance maximization is performed.

[Volume Homeostasis and Renal Function in Rats Exposed to Simulated and Actual Microgravity

NASA Technical Reports Server (NTRS)

Tucker, Bryan J.

1993-01-01

This project has investigated mechanisms that influence alterations in compartmental fluid and electrolyte balance in microgravity and evaluates countermeasures to control renal fluid and electrolyte losses. Determining the alterations due to space flight in fluid compartments and renal function is an important component in understanding long term adaptation to spaceflight and the contribution to post-flight orthostatic intolerance. Four definition phase studies and two studies examining neuro-humoral and vascular mechanisms have been completed.

Characterization and Evaluation of TiB2-AlN Composites for Armor Applications

DTIC Science & Technology

2013-09-01

identified structural defects and studied the fracture mechanisms (15, 16). 2 2. Experimental One TiB2 powder was used for this study. The TiB2...on phase formation and grain size effects compounded with residual stress on the fracture mechanisms . However, it was determined that the composite...Temperature. Annu. Book ASTM Stand. 2002, Vol. 15.01. 18. ASTM C 1421-10. Standard Test Methods for Determination of Fracture Toughness of

Quest for Accountability: Exploring the Evaluation Process of Universities

ERIC Educational Resources Information Center

Minelli, Eliana; Rebora, Gianfranco; Turri, Matteo

2015-01-01

The article explores the organisational impact of evaluation and control mechanisms on universities from the point of view of accountability. Three case studies are analysed with the aim of understanding the significance of these systems both at corporate governance level and in relation to their influence on the behaviour of the academic staff.…

Intensifying the Dominant Response II: Nonconscious Negative Affect, Cognitive Demand, and Conversations.

ERIC Educational Resources Information Center

Monahan, Jennifer L.; Laliker, Melanie

2002-01-01

Examines mechanisms that may account for why evaluations made by participants involved in conversations are more influenced by subliminal negative cues than are evaluations made by observers. Explains three studies in which subliminal priming tasks were used with differing cognitive loads and self-preservation concerns among a group of…

The Neural Substrates of Self-Evaluation of Mental Fatigue: A Magnetoencephalography Study

PubMed Central

Ishii, Akira; Tanaka, Masaaki; Watanabe, Yasuyoshi

2014-01-01

There have been several studies of the neural mechanisms underlying sensation of fatigue. However, little is known about the neural mechanisms underlying self-evaluation of the level of fatigue. The aim of this study was to identify the neural substrates involved in self-evaluation of the level of mental fatigue. We used magnetoencephalography (MEG) with high temporal resolution on 14 healthy participants. During MEG recordings, participants were asked to evaluate their level of mental fatigue in time with execution cues (evaluation trials) or to do nothing in time with execution cues (control trials). The MEG data were analyzed with equivalent current dipole (ECD) and spatial filtering methods to localize the neural activity related to the evaluation of mental fatigue. The daily level of fatigue sensation was assessed using the Checklist Individual Strength questionnaire. In evaluation trials, ECDs were observed in the posterior cingulate cortex (PCC) in seven of 14 participants, with a mean latency of 366.0 ms. The proportion of the participants with ECDs in the PCC was higher in evaluation trials than in control trials (P<0.05, McNemar test). The extent of the decreased delta band power in the PCC (Brodmann’s area 31) 600–700 ms after the onset of the execution cue and that in the dorsolateral prefrontal cortex (DLPFC; Brodmann’s area 9) 800–900 ms after the onset of the execution cue were greater in the evaluation trials than in the control trials. The decrease in delta band power in the DLPFC was positively related to that in the PCC and to the daily level of fatigue sensation. These data suggest that the PCC and DLPFC are involved in the self-evaluation of mental fatigue. PMID:24752677

Institute for Atom-Efficient Chemical Transformations Energy Frontier

Science.gov Websites

Synthesis Search Argonne ... Search Argonne Home > Institute for Atom-Efficient Chemical Transformations Synthesis Characterization Computational Studies Evaluation and Mechanisms/Catalytic Experimentation Using

Improvement and evaluation of thermal, electrical, sealing and mechanical contacts, and their interface materials

NASA Astrophysics Data System (ADS)

Luo, Xiangcheng

Material contacts, including thermal, electrical, seating (fluid sealing and electromagnetic sealing) and mechanical (pressure) contacts, together with their interface materials, were, evaluated, and in some cases, improved beyond the state of the art. The evaluation involved the use of thermal, electrical and mechanical methods. For thermal contacts, this work evaluated and improved the heat transfer efficiency between two contacting components by developing various thermal interface pastes. Sodium silicate based thermal pastes (with boron nitride particles as the thermally conductive filler) as well as polyethylene glycol (PEG) based thermal pastes were developed and evaluated. The optimum volume fractions of BN in sodium silicate based pastes and PEG based pastes were 16% and 18% respectively. The contribution of Li+ ions to the thermal contact conductance in the PEG-based paste was confirmed. For electrical contacts, the relationship between the mechanical reliability and electrical reliability of solder/copper and silver-epoxy/copper joints was addressed. Mechanical pull-out testing was conducted on solder/copper and silver-epoxy/copper joints, while the contact electrical resistivity was measured. Cleansing of the copper surface was more effective for the reliability of silver-epoxy/copper joint than that of solder/copper joint. For sealing contacts, this work evaluated flexible graphite as an electromagnetic shielding gasket material. Flexible graphite was found to be at least comparable to conductive filled silicone (the state of the art) in terms of the shielding effectiveness. The conformability of flexible graphite with its mating metal surface under repeated compression was characterized by monitoring the contact electrical resistance, as the conformability is important to both electromagnetic scaling and fluid waling using flexible graphite. For mechanical contacts, this work focused on the correlation of the interface structure (such as elastic/plastic deformation, oxidation, strain hardening, passive layer damage, fracture, etc.) with the electrical contact resistance, which was measured in real time for contacts under dynamic compression, thus allowing both reversible and irreversible changes to be observed. The materials studied included metals (carbon steel, stainless steel, aluminum and copper), carbon fiber reinforced polymer-matrix composite (nylon-6), ceramic (mortar) and graphite, due to their relevance to fastening, concrete structures, electric brushes and electrical pressure contacts.

Direct metal laser sintering titanium dental implants: a review of the current literature.

PubMed

Mangano, F; Chambrone, L; van Noort, R; Miller, C; Hatton, P; Mangano, C

2014-01-01

Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed.

Direct Metal Laser Sintering Titanium Dental Implants: A Review of the Current Literature

PubMed Central

Mangano, F.; Chambrone, L.; van Noort, R.; Miller, C.; Hatton, P.; Mangano, C.

2014-01-01

Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed. PMID:25525434

Air pollution, inflammation and preterm birth in Mexico City: study design and methods.

PubMed

O'Neill, Marie S; Osornio-Vargas, Alvaro; Buxton, Miatta A; Sánchez, Brisa N; Rojas-Bracho, Leonora; Castillo-Castrejon, Marisol; Mordhukovich, Irina B; Brown, Daniel G; Vadillo-Ortega, Felipe

2013-03-15

Preterm birth is one of the leading causes of perinatal mortality and is associated with long-term adverse health consequences for surviving infants. Preterm birth rates are rising worldwide, and no effective means for prevention currently exists. Air pollution exposure may be a significant cause of prematurity, but many published studies lack the individual, clinical data needed to elucidate possible biological mechanisms mediating these epidemiological associations. This paper presents the design of a prospective study now underway to evaluate those mechanisms in a cohort of pregnant women residing in Mexico City. We address how air quality may act together with other factors to induce systemic inflammation and influence the duration of pregnancy. Data collection includes: biomarkers relevant to inflammation in cervico-vaginal exudate and peripheral blood, along with full clinical information, pro-inflammatory cytokine gene polymorphisms and air pollution data to evaluate spatial and temporal variability in air pollution exposure. Samples are collected on a monthly basis and participants are followed for the duration of pregnancy. The data will be used to evaluate whether ambient air pollution is associated with preterm birth, controlling for other risk factors. We will evaluate which time windows during pregnancy are most influential in the air pollution and preterm birth association. In addition, the epidemiological study will be complemented with a parallel toxicology invitro study, in which monocytic cells will be exposed to air particle samples to evaluate the expression of biomarkers of inflammation. Copyright © 2012 Elsevier B.V. All rights reserved.

Air pollution, inflammation and preterm birth in Mexico City: Study design and methods

PubMed Central

O’Neill, Marie S.; Osornio-Vargas, Alvaro; Buxton, Miatta A.; Sanchez, Brisa N.; Rojas-Bracho, Leonora; Castillo-Castrejon, Marisol; Mordhukovich, Irina B.; Brown, Daniel G.; Vadillo-Ortega, Felipe

2012-01-01

Preterm birth is one of the leading causes of perinatal mortality and is associated with long-term adverse health consequences for surviving infants. Preterm birth rates are rising worldwide, and no effective means for prevention currently exists. Air pollution exposure may be a significant cause of prematurity, but many published studies lack the individual, clinical data needed to elucidate possible biological mechanisms mediating these epidemiological associations. This paper presents the design of a prospective study now underway to evaluate those mechanisms in a cohort of pregnant women residing in Mexico City. We address how air quality may act together with other factors to induce systemic inflammation and influence the duration of pregnancy. Data collection includes: biomarkers relevant to inflammation in cervico-vaginal exudate and peripheral blood, along with full clinical information, pro-inflammatory cytokine gene polymorphisms and air pollution data to evaluate spatial and temporal variability in air pollution exposure. Samples are collected on a monthly basis and participants are followed for the duration of pregnancy. The data will be used to evaluate whether ambient air pollution is associated with preterm birth, controlling for other risk factors. We will evaluate which time windows during pregnancy are most influential in the air pollution and preterm birth association. In addition, the epidemiological study will be complemented with a parallel toxicology invitro study, in which monocytic cells will be exposed to air particle samples to evaluate the expression of biomarkers of inflammation. PMID:23177781

[Effect of bemithyl (bemactor) on the bronchial epithelium regeneration and the main protector mechanisms of the respiratory system in chronic inflammation].

PubMed

Kobylianskiĭ, V I; Artiushkin, A V; Svetavskaia, M A

1999-01-01

To improve the efficiency of the therapy of respiratory diseases, the influence of a drug belonging to the group of actoprotectors--bemithyl (bemactor) on the main protector mechanisms of respiratory organs was evaluated, using functional-morphological studies of mucocilliary apparatus and local bronchial immunity. Bemithyl was found to produce no direct influence on these mechanisms, but the use of bemithyl by special technology is perspective for these purposes.

Comparative evaluation of gas-turbine engine combustion chamber starting and stalling characteristics for mechanical and air-injection

NASA Technical Reports Server (NTRS)

Dyatlov, I. N.

1983-01-01

The effectiveness of propellant atomization with and without air injection in the combustion chamber nozzle of a gas turbine engine is studied. Test show that the startup and burning performance of these combustion chambers can be improved by using an injection during the mechanical propellant atomization process. It is shown that the operational range of combustion chambers can be extended to poorer propellant mixtures by combined air injection mechanical atomization of the propellant.

Prevention of the Posttraumatic Fibrotic Response in Joints

DTIC Science & Technology

2015-10-01

used on a regular basis. Major Task 4: Evaluating the efficacy of inhibitory chIgG to reduce the consequences of traumatic joint injury. During...the second year of study, we successfully employed all assays needed to evaluate the utility of the inhibitory antibody to reduce the flexion...1. Major Task 5: Task 4. Data analysis and statistical evaluation of results. All data from the mechanical measurements, from the biochemical

Nakagami-m parametric imaging for characterization of thermal coagulation and cavitation erosion induced by HIFU.

PubMed

Han, Meng; Wang, Na; Guo, Shifang; Chang, Nan; Lu, Shukuan; Wan, Mingxi

2018-07-01

Nowadays, both thermal and mechanical ablation techniques of HIFU associated with cavitation have been developed for noninvasive treatment. A specific challenge for the successful clinical implementation of HIFU is to achieve real-time imaging for the evaluation and determination of therapy outcomes such as necrosis or homogenization. Ultrasound Nakagami-m parametric imaging highlights the degrading shadowing effects of bubbles and can be used for tissue characterization. The aim of this study is to investigate the performance of Nakagami-m parametric imaging for evaluating and differentiating thermal coagulation and cavitation erosion induced by HIFU. Lesions were induced in basic bovine serum albumin (BSA) phantoms and ex vivo porcine livers using a 1.6 MHz single-element transducer. Thermal and mechanical lesions induced by two types of HIFU sequences respectively were evaluated using Nakagami-m parametric imaging and ultrasound B-mode imaging. The lesion sizes estimated using Nakagami-m parametric imaging technique were all closer to the actual sizes than those of B-mode imaging. The p-value obtained from the t-test between the mean m values of thermal coagulation and cavitation erosion was smaller than 0.05, demonstrating that the m values of thermal lesions were significantly different from that of mechanical lesions, which was confirmed by ex vivo experiments and histologic examination showed that different changes result from HIFU exposure, one of tissue dehydration resulting from the thermal effect, and the other of tissue homogenate resulting from mechanical effect. This study demonstrated that Nakagami-m parametric imaging is a potential real-time imaging technique for evaluating and differentiating thermal coagulation and cavitation erosion. Copyright © 2018 Elsevier B.V. All rights reserved.

Compaction behavior and deformation mechanism of directly compressible textured mannitol in a rotary tablet press simulator.

PubMed

Tarlier, Nicolas; Soulairol, Ian; Bataille, Bernard; Baylac, Gilles; Ravel, Patrice; Nofrerias, Isaac; Lefèvre, Philippe; Sharkawi, Tahmer

2015-11-10

Textured mannitol powder is widely used as a pharmaceutical excipient for tablet compaction. In order to choose the right tableting parameters, it is necessary to understand its mechanical behavior during deformation under industrial tableting conditions. The aim of this study was to evaluate the mechanical behavior during deformation of a textured mannitol using a rotary tablet press simulator. Mean yield pressure (Py) obtained by Heckel modeling, Walker coefficients (W) and Stress Rate Sensitivity (SRS) were compared to reference excipients, known for either their plastic (microcrystalline cellulose) or fragmentary (lactose and dibasic calcium phosphate) deformation behavior. Py, W and SRS values showed that the studied textured mannitol has a fragmentary deformation mechanism. Furthermore, this mechanical behavior was not sensitive to lubrication, which is characteristic of fragmentary excipients. Copyright © 2015 Elsevier B.V. All rights reserved.

Mechanical and biological properties of the micro-/nano-grain functionally graded hydroxyapatite bioceramics for bone tissue engineering.

PubMed

Zhou, Changchun; Deng, Congying; Chen, Xuening; Zhao, Xiufen; Chen, Ying; Fan, Yujiang; Zhang, Xingdong

2015-08-01

Functionally graded materials (FGM) open the promising approach for bone tissue repair. In this study, a novel functionally graded hydroxyapatite (HA) bioceramic with micrograin and nanograin structure was fabricated. Its mechanical properties were tailored by composition of micrograin and nanograin. The dynamic mechanical analysis (DMA) indicated that the graded HA ceramics had similar mechanical property compared to natural bones. Their cytocompatibility was evaluated via fluorescent microscopy and MTT colorimetric assay. The viability and proliferation of rabbit bone marrow mesenchymal stem cells (BMSCs) on ceramics indicated that this functionally graded HA ceramic had better cytocompatibility than conventional HA ceramic. This study demonstrated that functionally graded HA ceramics create suitable structures to satisfy both the mechanical and biological requirements of bone tissues. Copyright © 2015 Elsevier Ltd. All rights reserved.

Toward toxicity testing of nanomaterials in the 21st century: a paradigm for moving forward.

PubMed

Lai, David Y

2012-01-01

A challenge-facing hazard identification and safety evaluation of engineered nanomaterials being introduced to market is the diversity and complexity of the types of materials with varying physicochemical properties, many of which can affect their toxicity by different mechanisms. In general, in vitro test systems have limited usefulness for hazard identification of nanoparticles due to various issues. Meanwhile, conducting chronic toxicity/carcinogenicity studies in rodents for every new nanomaterial introduced into the commerce is impractical if not impossible. New toxicity testing systems which rely on predictive, high-throughput technologies may be the ultimate goal of evaluating the potential hazard of nanomaterials. However, at present, this approach alone is unlikely to succeed in evaluating the toxicity of the wide array of nanomaterials and requires validation from in vivo studies. This article proposes a paradigm for toxicity testing and elucidation of the molecular mechanisms of reference materials for specific nanomaterial classes/subclasses using short-term in vivo animal studies in conjunction with high-throughput screenings and mechanism-based short-term in vitro assays. The hazard potential of a particular nanomaterial can be evaluated by conducting only in vitro high-throughput assays and mechanistic studies and comparing the data with those of the reference materials in the specific class/subclass-an approach in line with the vision for 'Toxicity Testing in the 21st Century' of chemicals. With well-designed experiments, testing nanomaterials of varying/selected physicochemical parameters may be able to identify the physicochemical parameters contributing to toxicity. The data so derived could be used for the development of computer model systems to predict the hazard potential of specific nanoparticles based on property-activity relationships. Copyright © 2011 John Wiley & Sons, Inc.

Compensatory mechanisms in fish populations: Literature reviews: Volume 2, Compensation in fish populations subject to catastrophic impact: Final report

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

Jude, D.J.; Mansfield, P.J.; Schneeberger, P.J.

1987-05-01

This study comprises an extensive literature review, critical evaluations of case histories, and considered recommendations for future research on the mechanisms and extent of compensation by various fish species subject to catastrophic impacts. ''Catastrophic impact'' was defined as an event which removes some limitation (such as food or space) on a fish population. Those events studied included new species introduction, toxic spills, exploitation of specific fish populations, and drawdown. The fish studied each had more than one compensatory mechanism available, and thus were able to respond to a catastrophic event even if an option was removed. Predation, overfishing, competition, disease,more » and parasitism are all potential catastrophies, but were found not to cause a catastrophic impact (except in special cases). In general, compensatory responses were determined to vary widely, even for species which perform fairly similar functions in an ecosystem. The extensive nature of this study, however, pointed up the many data gaps in the existing literature; recommendations are therefore made for followup research and expansion of ongoing monitoring programs, based on an evaluation of their relative importance.« less

Impact of formulation and saliva on acid milk gel friction behavior.

PubMed

Joyner Melito, Helen S; Pernell, Chris W; Daubert, Christopher R

2014-05-01

Rheological analysis is commonly used to evaluate mechanical properties in studies of food behavior. However, rheological analysis is often insufficient to describe food texture as evaluated by descriptive sensory analysis. Additionally, traditional rheometry does not account for changes in food behavior as a function of saliva incorporation into the food during mastication. The objectives of this study were to evaluate friction behavior of acid milk gels with and without the addition of saliva, and to determine relationships between frictional behaviors and mechanical and sensory behaviors. Acid milk gels were prepared with 12.5% total solids comprising nonfat dry milk, whey protein isolate, waxy maize starch, and gelatin in different ratios. The addition of starch was found to have significant impact on acid milk gel frictional behavior. Addition of saliva resulted in a change in frictional behavior over the entire sliding speed range measured. Correlations were found between rheological, tribological, and sensory behavior, suggesting that an underlying mechanism may impact both viscosity and friction behavior. Additional study is needed to further explore the links between food structure, rheology, tribology, and sensory texture. Application of tribology in food science allows measurement of friction behavior of foods. Matching both rheological and tribological behavior is important to creating reduced-fat or reduced-sugar products with similar mouthfeel to the original product. © 2014 Institute of Food Technologists®

[Application of finite element method in spinal biomechanics].

PubMed

Liu, Qiang; Zhang, Jun; Sun, Shu-Chun; Wang, Fei

2017-02-25

The finite element model is one of the most important methods in study of modern spinal biomechanics, according to the needs to simulate the various states of the spine, calculate the stress force and strain distribution of the different groups in the state, and explore its principle of mechanics, mechanism of injury, and treatment effectiveness. In addition, in the study of the pathological state of the spine, the finite element is mainly used in the understanding the mechanism of lesion location, evaluating the effects of different therapeutic tool, assisting and completing the selection and improvement of therapeutic tool, in order to provide a theoretical basis for the rehabilitation of spinal lesions. Finite element method can be more provide the service for the patients suffering from spinal correction, operation and individual implant design. Among the design and performance evaluation of the implant need to pay attention to the individual difference and perfect the evaluation system. At present, how to establish a model which is more close to the real situation has been the focus and difficulty of the study of human body's finite element.Although finite element method can better simulate complex working condition, it is necessary to improve the authenticity of the model and the sharing of the group by using many kinds of methods, such as image science, statistics, kinematics and so on. Copyright© 2017 by the China Journal of Orthopaedics and Traumatology Press.

In vitro evaluation of three-dimensional single-walled carbon nanotube composites for bone tissue engineering.

PubMed

Gupta, Ashim; Main, Benjamin J; Taylor, Brittany L; Gupta, Manu; Whitworth, Craig A; Cady, Craig; Freeman, Joseph W; El-Amin, Saadiq F

2014-11-01

The purpose of this study was to develop three-dimensional single-walled carbon nanotube composites (SWCNT/PLAGA) using 10-mg single-walled carbon nanotubes (SWCNT) for bone regeneration and to determine the mechanical strength of the composites, and to evaluate the interaction of MC3T3-E1 cells via cell adhesion, growth, survival, proliferation, and gene expression. PLAGA (polylactic-co-glycolic acid) and SWCNT/PLAGA microspheres and composites were fabricated, characterized, and mechanical testing was performed. MC3T3-E1 cells were seeded and cell adhesion/morphology, growth/survival, proliferation, and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated microspheres with uniform shape and smooth surfaces, and uniform incorporation of SWCNT into PLAGA matrix. The microspheres bonded in a random packing manner while maintaining spacing, thus resembling trabeculae of cancellous bone. Addition of SWCNT led to greater compressive modulus and ultimate compressive strength. Imaging studies revealed that MC3T3-E1 cells adhered, grew/survived, and exhibited normal, nonstressed morphology on the composites. SWCNT/PLAGA composites exhibited higher cell proliferation rate and gene expression compared with PLAGA. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration, for bone tissue engineering, and are promising for orthopedic applications as they possess the combined effect of increased mechanical strength, cell proliferation, and gene expression. © 2014 Wiley Periodicals, Inc.

Overview of ultrasound-induced lung hemorrhage

NASA Astrophysics Data System (ADS)

O'Brien, William D.; Simpson, Douglas G.; Frizzell, Leon A.; Oelze, Michael L.; Zachary, James F.

2003-10-01

It is well documented that ultrasound-induced lung hemorrhage can occur in mice, rats, rabbits, pigs, and monkeys. Our own experimental studies have focused on mice, rats, and pigs as animal models. The characteristics of the lesions produced in mice, rats and pigs were similar to those described in studies by our research group and others, suggesting a common pathogenesis for the initiation and propagation of the lesions at the macroscopic and microscopic levels. Five experimental in vivo studies have been conducted to evaluate whether cavitation is responsible for ultrasound-induced lung hemorrhage. The studies evaluated the dependencies of hydrostatic pressure, frequency, pulse polarity, contrast agents and lung inflation, and the results of each study appeared inconsistent with the hypothesis that the mechanism for the production of a lung hemorrhage was inertial cavitation. Other dependencies evaluated included beam width, pulse repetition frequency, pulse duration, exposure duration, and animal species and age. The thresholds for producing ultrasound-induced lung hemorrhage, in general, were less than the FDA's regulatory limit of a Mechanical Index (MI) of 1.9. Further, the MI does not appear to provide a risk-based index for lung hemorrhage. [Work supported by NIH Grant No. R01EB02641.

Durability and mechanical properties of silane cross-linked wood thermoplastic composites

Treesearch

Magnus Bengtsson; Nicole M. Stark; Kristiina Oksman

2007-01-01

In this study, silane cross-linked wood–polyethylene composite profiles were manufactured by reactive extrusion. These composites were evaluated regarding their durability and mechanical properties in comparison with two non-cross-linked wood– polyethylene composites. An addition of only 2% w/w of silane solution during manufacturing was enough to achieve almost 60%...

Physical and mechanical properties and fire, decay, and termite resistance of treated oriented strandboard

Treesearch

Nadir Ayrilmis; S Nami Kartal; Theodore L. Laufenberg; Jerrold E. Winandy; Robert H. White

2005-01-01

This study evaluated the effects of a number of chemicals on the physical and mechanical properties and fire, decay, and termite resistance of oriented strandboard (OSB) panels. Disodium octaborate tetrahydrate (DOT), boric acid (BA), melamine phosphate (MP), and a BA/DOT mixture were sprayed onto the furnish at varying concentrations. The panels were tested for...

The Mechanical Waves Conceptual Survey: An Analysis of University Students' Performance, and Recommendations for Instruction

ERIC Educational Resources Information Center

Barniol, Pablo; Zavala, Genaro

2017-01-01

The Mechanical Waves Conceptual Survey (MWCS), presented in 2009, is the most important test to date that has been designed to evaluate university students' understanding of four main topics: propagation, superposition, reflection, and standing waves. In a literature review, we detected a significant need for a study that uses this test as an…

Experimental analysis of the bearing greases lifetime

NASA Astrophysics Data System (ADS)

Albagachiev, A. U.; Smirnov, N. I.; Prozhega, M. V.; Smirnov, N. N.

2018-04-01

The purpose of the presented work is to increase the lifetime of space mechanisms bearings. The authors reviewed the studies of the bearings and linear mechanisms operating in air and in vacuum. A testing equipment is developed to assess the lubricity and lifetime of greases in the air. Criteria for the evaluation of relative lifetime are defined. Four types of space greases are tested.

Voices of the Stakeholders: A Case of Power Mechanics in Kenya

ERIC Educational Resources Information Center

Kitainge, Kisilu Mashtakh

2003-01-01

The primary purpose of this study was to find out the attitudes of trainers and trainees towards the 8-4-4 power mechanics course offered in secondary schools in Kenya. The attitudes and other related aspects obtained from the trainers and trainees were used as evaluative devices for the course and hence the graduates of the course. A comparison…

How do you modernize a health service? A realist evaluation of whole-scale transformation in london.

PubMed

Greenhalgh, Trisha; Humphrey, Charlotte; Hughes, Jane; Macfarlane, Fraser; Butler, Ceri; Pawson, Ray

2009-06-01

Large-scale, whole-systems interventions in health care require imaginative approaches to evaluation that go beyond assessing progress against predefined goals and milestones. This project evaluated a major change effort in inner London, funded by a charitable donation of approximately $21 million, which spanned four large health care organizations, covered three services (stroke, kidney, and sexual health), and sought to "modernize" these services with a view to making health care more efficient, effective, and patient centered. This organizational case study draws on the principles of realist evaluation, a largely qualitative approach that is centrally concerned with testing and refining program theories by exploring the complex and dynamic interaction among context, mechanism, and outcome. This approach used multiple data sources and methods in a pragmatic and reflexive manner to build a picture of the case and follow its fortunes over the three-year study period. The methods included ethnographic observation, semistructured interviews, and scrutiny of documents and other contemporaneous materials. As well as providing ongoing formative feedback to the change teams in specific areas of activity, we undertook a more abstract, interpretive analysis, which explored the context-mechanism-outcome relationship using the guiding question "what works, for whom, under what circumstances?" In this example of large-scale service transformation, numerous projects and subprojects emerged, fed into one another, and evolved over time. Six broad mechanisms appeared to be driving the efforts of change agents: integrating services across providers, finding and using evidence, involving service users in the modernization effort, supporting self-care, developing the workforce, and extending the range of services. Within each of these mechanisms, different teams chose widely differing approaches and met with differing success. The realist analysis of the fortunes of different subprojects identified aspects of context and mechanism that accounted for observed outcomes (both intended and unintended). This study was one of the first applications of realist evaluation to a large-scale change effort in health care. Even when an ambitious change program shifts from its original goals and meets unforeseen challenges (indeed, precisely because the program morphs and adapts over time), realist evaluation can draw useful lessons about how particular preconditions make particular outcomes more likely, even though it cannot produce predictive guidance or a simple recipe for success. Noting recent calls by others for the greater use of realist evaluation in health care, this article considers some of the challenges and limitations of this method in the light of this experience and suggests that its use will require some fundamental changes in the worldview of some health services researchers.

Prevalence and mechanism of tricuspid regurgitation following implantation of endocardial leads for pacemaker or cardioverter-defibrillator.

PubMed

Al-Mohaissen, Maha A; Chan, Kwan Leung

2012-03-01

Endocardial lead-induced tricuspid regurgitation has not been well recognized, either clinically or echocardiographically, and yet it is likely a preventable iatrogenic disease. In severe cases, it can lead to right ventricular failure and require tricuspid valve surgery. This complication will become increasingly important, because the numbers of permanent pacemakers and implantable cardioverter-defibrillators are expected to increase because of the aging population and the expanding capabilities of these devices. Published studies are largely retrospective, and serial studies to assess the time course of the development of tricuspid regurgitation are lacking. The mechanisms and severity of tricuspid regurgitation may not be well evaluated by two-dimensional echocardiography. Real-time three-dimensional echocardiography appears to be a promising technique to evaluate the mechanism of tricuspid regurgitation and may allow the early detection of patients who will develop severe lead-induced tricuspid regurgitation. A better understanding of the mechanism of lead-induced tricuspid regurgitation will be essential to the development of preventive strategies, which can then be tested in future clinical trials. Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

Balancing mechanical strength with bioactivity in chitosan-calcium phosphate 3D microsphere scaffolds for bone tissue engineering: air- vs. freeze-drying processes.

PubMed

Nguyen, D T; McCanless, J D; Mecwan, M M; Noblett, A P; Haggard, W O; Smith, R A; Bumgardner, J D

2013-01-01

The objective of this study was to evaluate the potential benefit of 3D composite scaffolds composed of chitosan and calcium phosphate for bone tissue engineering. Additionally, incorporation of mechanically weak lyophilized microspheres within those air-dried (AD) was considered for enhanced bioactivity. AD microsphere, alone, and air- and freeze-dried microsphere (FDAD) 3D scaffolds were evaluated in vitro using a 28-day osteogenic culture model with the Saos-2 cell line. Mechanical testing, quantitative microscopy, and lysozyme-driven enzymatic degradation of the scaffolds were also studied. FDAD scaffold showed a higher concentration (p < 0.01) in cells per scaffold mass vs. AD constructs. Collagen was ∼31% greater (p < 0.01) on FDAD compared to AD scaffolds not evident in microscopy of microsphere surfaces. Alternatively, AD scaffolds demonstrated a superior threefold increase in compressive strength over FDAD (12 vs. 4 MPa) with minimal degradation. Inclusion of FD spheres within the FDAD scaffolds allowed increased cellular activity through improved seeding, proliferation, and extracellular matrix production (as collagen), although mechanical strength was sacrificed through introduction of the less stiff, porous FD spheres.

Toward understanding the efficacy and mechanism of Opuntia spp. as a natural coagulant for potential application in water treatment.

PubMed

Miller, Sarah M; Fugate, Ezekiel J; Craver, Vinka Oyanedel; Smith, James A; Zimmerman, Julie B

2008-06-15

Historically, there is evidence to suggest that communities in the developing world have used plant-based materials as one strategy for purifying drinking water. In this study, the coagulant properties of Opuntia spp., a species of cactus, are quantitatively evaluated for the first time. Opuntia spp. was evaluated for turbidity removal from synthetic water samples, and steps were made toward elucidating the underlying coagulation mechanism. In model turbid water using kaolin clay particles at pH 10, Opuntia spp. reduced turbidity by 98% for a range of initial turbidities. This is similar to the observed coagulation activities previously described for Moringa oleifera, a widely studied natural coagulant. Although it has been reported that Moringa oleifera predominantly operates through charge neutralization, comparison of zeta potential measurements and transmission electron microscopy images of flocs formed by Opuntia spp. suggest that these natural coagulants operate through different mechanisms. It is suggested that Opuntia spp. operates predominantly through a bridging coagulation mechanism. Once optimized, application of these readily available plants as a part of point-of-use water treatment technology may offer a practical, inexpensive, and appropriate solution for producing potable water in some developing communities.

Mechanical Model Analysis for Quantitative Evaluation of Liver Fibrosis Based on Ultrasound Tissue Elasticity Imaging

NASA Astrophysics Data System (ADS)

Shiina, Tsuyoshi; Maki, Tomonori; Yamakawa, Makoto; Mitake, Tsuyoshi; Kudo, Masatoshi; Fujimoto, Kenji

2012-07-01

Precise evaluation of the stage of chronic hepatitis C with respect to fibrosis has become an important issue to prevent the occurrence of cirrhosis and to initiate appropriate therapeutic intervention such as viral eradication using interferon. Ultrasound tissue elasticity imaging, i.e., elastography can visualize tissue hardness/softness, and its clinical usefulness has been studied to detect and evaluate tumors. We have recently reported that the texture of elasticity image changes as fibrosis progresses. To evaluate fibrosis progression quantitatively on the basis of ultrasound tissue elasticity imaging, we introduced a mechanical model of fibrosis progression and simulated the process by which hepatic fibrosis affects elasticity images and compared the results with those clinical data analysis. As a result, it was confirmed that even in diffuse diseases like chronic hepatitis, the patterns of elasticity images are related to fibrous structural changes caused by hepatic disease and can be used to derive features for quantitative evaluation of fibrosis stage.

Influence of Different Ceramic Systems on Marginal Misfit.

PubMed

Vargas, S P; Neves, A C C; Vitti, R; Amaral, M; Henrique, M N; Silva-Concílio, L R

2017-09-01

the aim of this study was to evaluate the marginal misfit at the interface between a ceramic coping and its abutment. Twenty-four specimens were made with solid abutments. The specimens were divided into 3 groups according to the ceramic system (n = 8): Lava (zirconia), IPS e.max Press (lithium disilicate), and IPS Empress Esthetic (leucite). All copings were cemented with resin luting agent (RelyX U200) and the marginal misfit were evaluated at 3 different times: initial, after cementation, and after mechanical cycling using a linear measuring microscope (Measuring Microscope STM-Olympus) at a magnification of 40x. All specimens were subjected to mechanical cycling (1 million cycles) by an universal testing machine (Instron 8800). The results were statistically analyzed using Analysis of Variance and Student's t-test (α = 0.05). all groups showed an increase in the marginal misfit after cementation. The lithium disilicate group demonstrated the lowest interacial gap values at each evaluation (p = 0.001). The zirconia and leucite groups showed similar interfacial gap values (initial, p = 0.244; and post cementation, p = 0.751). the cementation increase the marginal misfit, but the mechanical cycling did not influence the marginal misfit of the ceramics systems evaluated. Copyright© 2017 Dennis Barber Ltd.

Translation and cultural adaptation of the Brazilian Portuguese version of the Behavioral Pain Scale.

PubMed

Morete, Márcia Carla; Mofatto, Sarah Camargo; Pereira, Camila Alves; Silva, Ana Paula; Odierna, Maria Tereza

2014-01-01

The objective of this study was to translate and culturally adapt the Behavioral Pain Scale to Brazilian Portuguese and to evaluate the psychometric properties of this scale. This study was conducted in two phases: the Behavioral Pain Scale was translated and culturally adapted to Brazilian Portuguese and the psychometric properties of this scale were subsequently assessed (reliability and clinical utility). The study sample consisted of 100 patients who were older than 18 years of age, admitted to an intensive care unit, intubated, mechanically ventilated, and subjected or not to sedation and analgesia from July 2012 to December 2012. Pediatric and non-intubated patients were excluded. The study was conducted at a large private hospital that was situated in the city of São Paulo (SP). Regarding reproducibility, the results revealed that the observed agreement between the two evaluators was 92.08% for the pain descriptor "adaptation to mechanical ventilation", 88.1% for "upper limbs", and 90.1% for "facial expression". The kappa coefficient of agreement for "adaptation to mechanical ventilation" assumed a value of 0.740. Good agreement was observed between the evaluators with an intraclass correlation coefficient of 0.807 (95% confidence interval: 0.727-0.866). The Behavioral Pain Scale was easy to administer and reproduce. Additionally, this scale had adequate internal consistency. The Behavioral Pain Scale was satisfactorily adapted to Brazilian Portuguese for the assessment of pain in critically ill patients.

Evaluation of Rhodosporidium fluviale as biocontrol agent against Botrytis cinerea on apple fruit.

PubMed

Sansone, G; Lambrese, Y; Calvente, V; Fernández, G; Benuzzi, D; Sanz Ferramola, M

2018-05-01

The aim of the present work was to evaluate the ability of the native yeast Rhodosporidium fluviale to control Botrytis cinerea on apple fruit and to study the possible mechanisms of action with the goal of improving the control of gray mold. For this, the influence of application time of the yeast was studied simulating preventive and curative effects. Also, the effect of nonviable cells of the yeast in the biocontrol was assessed. According to the results obtained, the following mechanisms of action of R. fluviale could be proposed: 1- competition for space, 2- direct interaction between antagonist and pathogen, 3- induction of β-1,3-glucanase in apple tissue, 4- Probable production of glucanase in the apple wounds and 5- antifungal action of cellular components, probably chitin, present in the wall of yeast cells that could be the explanation for the activity of nonviable cells. Significance and Impact of the Study: Botrytis cinerea Pers: Fr, which causes gray mold of fruits and vegetables around the world, is difficult to control successfully because it is genetically variable and rapidly develops resistance to the chemicals commonly used for its control. This study is a contribution to the biocontrol of this phytopathogen fungus. The evaluation of the native yeast Rhodosporidium fluviale as biocontrol agent and the elucidation of possible mechanisms of action, including the participation of nonviable cells of this yeast, have not been reported up to date. © 2018 The Society for Applied Microbiology.

Dynamic analysis of six-bar mechanical press for deep drawing

NASA Astrophysics Data System (ADS)

Mitsi, S.; Tsiafis, I.; Bouzakis, K. D.

2017-02-01

This paper analyzes the dynamical behavior of a six-bar linkage used in mechanical presses for metal forming such as deep drawing. In the under study mechanism, a four-bar linkage is connected to a slider through an articulated binary link. The motion of the six-bar linkage is studied by kinematic analysis developing an analytical method. Furthermore, using an iterative method and d’ Alembert’s principle, the joint forces and drive moment are evaluated considering joint frictions. The simulation results obtained with a MATLAB program are validated by comparing the theoretical values of the input moment with the ones obtained from the conservation of energy law.

Vocal Emotion of Humanoid Robots: A Study from Brain Mechanism

PubMed Central

Wang, Youhui; Hu, Xiaohua; Zhou, Jie; Kuo, Taitzong

2014-01-01

Driven by rapid ongoing advances in humanoid robot, increasing attention has been shifted into the issue of emotion intelligence of AI robots to facilitate the communication between man-machines and human beings, especially for the vocal emotion in interactive system of future humanoid robots. This paper explored the brain mechanism of vocal emotion by studying previous researches and developed an experiment to observe the brain response by fMRI, to analyze vocal emotion of human beings. Findings in this paper provided a new approach to design and evaluate the vocal emotion of humanoid robots based on brain mechanism of human beings. PMID:24587712

In vitro and in vivo mechanical evaluations of plasma-sprayed hydroxyapatite coatings on titanium implants: the effect of coating characteristics.

PubMed

Yang, C Y; Lin, R M; Wang, B C; Lee, T M; Chang, E; Hang, Y S; Chen, P Q

1997-12-05

This study was undertaken to evaluate the effect of coating characteristics on the mechanical strengths of the plasma-sprayed HA-coated Ti-6Al-4V implant system both in vitro and in vivo. Two types of HA coatings (HACs) with quite different microstructures, concentrations of impurity-phases, and indices-of-crystallinity were used. In vitro testings were done by measuring the bonding-strength at the Ti-6Al-4V-HAC interface, with HACs that had and had not been immersed in a pH-buffered, serum-added simulated body fluid (SBF). The shear-strength at the HAC-bone interface was investigated in a canine transcortical femoral model after 12 and 24 weeks of implantation. The results showed a bonding degradation of approximately 32% or higher of the original strength after 4 weeks of immersion in SBF, and this predominantly depended on the constructed microstructure of the HACs. After the push-out measurements, it was demonstrated that the HACs with higher bonding-strength in vitro would correspondingly result in significantly higher shear-strength at each implant period in vivo. Nevertheless, there were no substantial histological variations between the two types of HACs evaluated. The most important point elucidated in this study was that, among coating characteristics, the microstructure was the key factor in influencing the mechanical stability of the HACs both in vitro and in vivo. As a consequence, a denser HAC was needed to ensure mechanical stability at both interfaces.

Failure mechanisms and lifetime prediction methodology for polybutylene pipe in water distribution system

NASA Astrophysics Data System (ADS)

Niu, Xiqun

Polybutylene (PB) is a semicrystalline thermoplastics. It has been widely used in potable water distribution piping system. However, field practice shows that failure occurs much earlier than the expected service lifetime. What are the causes and how to appropriately evaluate its lifetime motivate this study. In this thesis, three parts of work have been done. First is the understanding of PB, which includes material thermo and mechanical characterization, aging phenomena and notch sensitivity. The second part analyzes the applicability of the existing lifetime testing method for PB. It is shown that PB is an anomaly in terms of the temperature-lifetime relation because of the fracture mechanism transition across the testing temperature range. The third part is the development of the methodology of lifetime prediction for PB pipe. The fracture process of PB pipe consists of three stages, i.e., crack initiation, slow crack growth (SCG) and crack instability. The practical lifetime of PB pipe is primarily determined by the duration of the first two stages. The mechanism of crack initiation and the quantitative estimation of the time to crack initiation are studied by employing environment stress cracking technique. A fatigue slow crack growth testing method has been developed and applied in the study of SCG. By using Paris-Erdogan equation, a model is constructed to evaluate the time for SCG. As a result, the total lifetime is determined. Through this work, the failure mechanisms of PB pipe has been analyzed and the lifetime prediction methodology has been developed.

Operation analysis of a Chebyshev-Pantograph leg mechanism for a single DOF biped robot

NASA Astrophysics Data System (ADS)

Liang, Conghui; Ceccarelli, Marco; Takeda, Yukio

2012-12-01

In this paper, operation analysis of a Chebyshev-Pantograph leg mechanism is presented for a single degree of freedom (DOF) biped robot. The proposed leg mechanism is composed of a Chebyshev four-bar linkage and a pantograph mechanism. In contrast to general fully actuated anthropomorphic leg mechanisms, the proposed leg mechanism has peculiar features like compactness, low-cost, and easy-operation. Kinematic equations of the proposed leg mechanism are formulated for a computer oriented simulation. Simulation results show the operation performance of the proposed leg mechanism with suitable characteristics. A parametric study has been carried out to evaluate the operation performance as function of design parameters. A prototype of a single DOF biped robot equipped with two proposed leg mechanisms has been built at LARM (Laboratory of Robotics and Mechatronics). Experimental test shows practical feasible walking ability of the prototype, as well as drawbacks are discussed for the mechanical design.

International Conference on the Mechanical Technology of Inertial Devices, University of Newcastle-upon-Tyne, England, Apr. 7-9, 1987, Proceedings

NASA Astrophysics Data System (ADS)

Various papers on the mechanical technology of inertial devices are presented. The topics addressed include: development of a directional gyroscope for remotely piloted vehicles and similar applications; a two-degree-of-freedom gyroscope with frictionless inner and outer gimbal pickoffs; oscillogyro design, manufacture, and performance; development of miniature two-axis rate gyroscope; mechanical design aspects of the electrostatically suspended gyroscope; role of gas-lubricated bearings in current and future sensors; development of a new microporous retainer material for precision ball bearings; design study for a high-stability, large-centrifuge test bed; evaluation of a two-axis rate gyro; operating principles of a two-axis angular rate transducer; and nutation frequency analysis. Also considered are: triaxial laser gyro; mechanical design considerations for a ring laser gyro dither mechanism; environmental considerations in the design of fiberoptic gyroscopes; manufacturing aspects of some critical high-precision mechanical components of inertial devices; dynamics and control of a gyroscopic force measurement system; high precision and high performance motion systems; use of multiple acceleration references to obtain high precision centrifuge data at low cost; gyro testing and evaluation at the Communications Research Centre; review of the mechanical design and development of a high-performance accelerometer; and silicon microengineering for accelerometers.

Mechanical and biological evaluations of beta-tricalcium phosphate/silicone rubber composite as a novel soft-tissue implant.

PubMed

Zhang, Yi-ming; Wang, Shao-liang; Lei, Ze-yuan; Fan, Dong-li

2009-09-01

Although silicone rubber (SR) implants are most commonly used and effective for soft-tissue augmentation, they still have been implicated in many adverse reactions. To overcome this problem, a novel composite beta-tricalcium phosphate/silicone rubber (beta-TCP/SR) was prepared by adding beta-TCP into a SR matrix. This study was to evaluate its application potential by investigating the mechanical properties and biocompatibility of beta-TCP/SR. Mechanical properties, including Shore A hardness and tensile strength, were evaluated with 3-mm-thick samples and a universal testing machine. Cytocompatibility tests were conducted in vitro using 0.2-mm-thick beta-TCP/SR samples by seeding fibroblasts onto different samples. Soft-tissue response to beta-TCP/SR and pull-out measurements were investigated 4 weeks and 24 weeks after implantation. The main mechanical properties were all significantly changed after mixing beta-TCP into the SR matrix, except for tearing strength. The cytocompatibility test showed enhanced adhesion and proliferation of fibroblasts onto beta-TCP/SR. Fibrous tissue ingrowth after resorption of beta-TCP was observed by in vivo histologic analysis. The peri-implant capsules in the beta-TCP/SR group were thinner than in the SR group 24 weeks after implantation. In a 24-week test, the maximum force required to pull out the beta-TCP/SR sheet was about six times greater than that needed for SR. Although some mechanical properties were significantly changed, the results of the cytocompatibility test and in vivo animal study still suggest that beta-TCP/SR may be more suitable as a soft-tissue implant than SR and has the potential to be used in plastic surgery.

Mechanical properties, morphology, and hydrolytic degradation behavior of polylactic acid / natural rubber blends

NASA Astrophysics Data System (ADS)

Buys, Y. F.; Aznan, A. N. A.; Anuar, H.

2018-01-01

Due to its biodegradability and renewability, polylactic acid (PLA) has been receiving enormous attention as a potential candidate to replace petroleum based polymers. However, PLA has limitation due to its inherent brittleness. In order to overcome this limitation, blending PLA with elastomeric materials such as natural rubber (NR) are commonly reported. In previous, several researches on PLA/NR blend had been reported, with most of them evaluated the mechanical properties. On the other hand, study of degradation behavior is significance of importance, as controlling materials degradation is required in some applications. This research studied the effect of blend composition on mechanical properties, morphology development, and hydrolytic degradation behavior of PLA/NR blends. Various compositions of PLA/NR blends were prepared by melt blending technique. Tensile test and impact test of the blends were performed to evaluate the mechanical properties. Addition of NR improved the elongation at break and impact strength of the blends, but reduced the tensile strength and stiffness of the specimens. Dynamic Mechanical Analysis (DMA) measurements of the blends displayed two peaks at temperature -70˚C which corresponded to T g of NR and 65˚C which corresponded to T g of PLA. Field Emission Scanning Electron Microscopy (FE-SEM) micrograph of 70/30 PLA/NR specimen also showed two distinct phases, which lead to indication that PLA/NR blends are immiscible. Hydrolytic degradation behavior was evaluated by measuring the remaining weight of the samples immersed in sodium hydroxide solution for a predetermined times. It was shown that the degradation behavior of PLA/NR blends is affected by composition of the blends, with 100 PLA and 70/30 PLA/NR blend showed the fastest degradation rate and 100 NR displayed the slowest one.

Statistical process control applied to mechanized peanut sowing as a function of soil texture.

PubMed

Zerbato, Cristiano; Furlani, Carlos Eduardo Angeli; Ormond, Antonio Tassio Santana; Gírio, Lucas Augusto da Silva; Carneiro, Franciele Morlin; da Silva, Rouverson Pereira

2017-01-01

The successful establishment of agricultural crops depends on sowing quality, machinery performance, soil type and conditions, among other factors. This study evaluates the operational quality of mechanized peanut sowing in three soil types (sand, silt, and clay) with variable moisture contents. The experiment was conducted in three locations in the state of São Paulo, Brazil. The track-sampling scheme was used for 80 sampling locations of each soil type. Descriptive statistics and statistical process control (SPC) were used to evaluate the quality indicators of mechanized peanut sowing. The variables had normal distributions and were stable from the viewpoint of SPC. The best performance for peanut sowing density, normal spacing, and the initial seedling growing stand was found for clayey soil followed by sandy soil and then silty soil. Sandy or clayey soils displayed similar results regarding sowing depth, which was deeper than in the silty soil. Overall, the texture and the moisture of clayey soil provided the best operational performance for mechanized peanut sowing.

Statistical process control applied to mechanized peanut sowing as a function of soil texture

PubMed Central

Furlani, Carlos Eduardo Angeli; da Silva, Rouverson Pereira

2017-01-01

The successful establishment of agricultural crops depends on sowing quality, machinery performance, soil type and conditions, among other factors. This study evaluates the operational quality of mechanized peanut sowing in three soil types (sand, silt, and clay) with variable moisture contents. The experiment was conducted in three locations in the state of São Paulo, Brazil. The track-sampling scheme was used for 80 sampling locations of each soil type. Descriptive statistics and statistical process control (SPC) were used to evaluate the quality indicators of mechanized peanut sowing. The variables had normal distributions and were stable from the viewpoint of SPC. The best performance for peanut sowing density, normal spacing, and the initial seedling growing stand was found for clayey soil followed by sandy soil and then silty soil. Sandy or clayey soils displayed similar results regarding sowing depth, which was deeper than in the silty soil. Overall, the texture and the moisture of clayey soil provided the best operational performance for mechanized peanut sowing. PMID:28742095

The Investigation on Strain Strengthening Induced Martensitic Phase Transformation of Austenitic Stainless Steel: A Fundamental Research for the Quality Evaluation of Strain Strengthened Pressure Vessel

NASA Astrophysics Data System (ADS)

Li, Bo; Cai Ren, Fa; Tang, Xiao Ying

2018-03-01

The manufacture of pressure vessels with austenitic stainless steel strain strengthening technology has become an important technical means for the light weight of cryogenic pressure vessels. In the process of increasing the strength of austenitic stainless steel, strain can induce the martensitic phase transformation in austenite phase. There is a quantitative relationship between the transformation quantity of martensitic phase and the basic mechanical properties. Then, the martensitic phase variables can be obtained by means of detection, and the mechanical properties and safety performance are evaluated and calculated. Based on this, the quantitative relationship between strain hardening and deformation induced martensite phase content is studied in this paper, and the mechanism of deformation induced martensitic transformation of austenitic stainless steel is detailed.

Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems

DTIC Science & Technology

2017-02-22

patients using long-term liquid oxygen differ from those on traditional treatment with oxygen concentrators and/or compressed gas cylinders? A...AFRL-SA-WP-SR-2017-0006 Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems Thomas Blakeman, MSc, RRT; Dario...To) August 2014 – September 2016 4. TITLE AND SUBTITLE Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems 5a. CONTRACT NUMBER

The mechanical properties of polyimide films after exposure to high pH

NASA Technical Reports Server (NTRS)

Croall, Catharine I.; St.clair, Terry L.

1992-01-01

Wiring failures linked to insulation damage have drawn much attention in the aerospace industry and concerns have developed regarding the stability and safety of polyimide insulated electrical wire. Several polyimides were selected for evaluation for resistance to degradation by various aqueous alkaline solutions. The polyimides under evaluation include commercially available films such as Kapton (tk), Apical (tk), LaRC(tk)-TPI, and Upilex(tk)R and S, as well as a number of experimental films prepared by NASA Langley. Thermally imidized films were studied for their retention of mechanical properties after exposure to high pH solutions under stressed conditions.

Criteria for Evaluating the Performance of Compilers

DTIC Science & Technology

1974-10-01

cannot be made to fit, then an auxiliary mechanism outside the parser might be used . Finally, changing the choice of parsing tech - nique to a...was not useful in providing a basic for compiler evaluation. The study of the first question eztablished criteria and methodb for assigning four...program. The study of the second question estab- lished criteria for defining a "compiler Gibson mix", and established methods for using this "mix" to

Quality evaluation of value sets from cancer study common data elements using the UMLS semantic groups

PubMed Central

Solbrig, Harold R; Chute, Christopher G

2012-01-01

Objective The objective of this study is to develop an approach to evaluate the quality of terminological annotations on the value set (ie, enumerated value domain) components of the common data elements (CDEs) in the context of clinical research using both unified medical language system (UMLS) semantic types and groups. Materials and methods The CDEs of the National Cancer Institute (NCI) Cancer Data Standards Repository, the NCI Thesaurus (NCIt) concepts and the UMLS semantic network were integrated using a semantic web-based framework for a SPARQL-enabled evaluation. First, the set of CDE-permissible values with corresponding meanings in external controlled terminologies were isolated. The corresponding value meanings were then evaluated against their NCI- or UMLS-generated semantic network mapping to determine whether all of the meanings fell within the same semantic group. Results Of the enumerated CDEs in the Cancer Data Standards Repository, 3093 (26.2%) had elements drawn from more than one UMLS semantic group. A random sample (n=100) of this set of elements indicated that 17% of them were likely to have been misclassified. Discussion The use of existing semantic web tools can support a high-throughput mechanism for evaluating the quality of large CDE collections. This study demonstrates that the involvement of multiple semantic groups in an enumerated value domain of a CDE is an effective anchor to trigger an auditing point for quality evaluation activities. Conclusion This approach produces a useful quality assurance mechanism for a clinical study CDE repository. PMID:22511016

Prevention of the Posttraumatic Fibrotic Response in Joints

DTIC Science & Technology

2015-10-01

are currently used on a regular basis. Major Task 4: Evaluating the efficacy of inhibitory chIgG to reduce the consequences of traumatic joint...injury. During the second year of study, we successfully employed all assays needed to evaluate the utility of the inhibitory antibody to reduce the...32nd week 1. Major Task 5: Task 4. Data analysis and statistical evaluation of results. All data from the mechanical measurements, from the

The Long and Winding Road: Grades, Psychological Disengagement and Motivation among Female Students in (Non-)Traditional Career Paths

ERIC Educational Resources Information Center

Rinfret, Natalie; Tougas, Francine; Beaton, Ann M.; Laplante, Joelle; Ngo Manguelle, Christiane; Lagacé, Marie Claude

2014-01-01

The purpose of this study was to evaluate the links between grades, psychological disengagement mechanisms (discounting evaluative feedback and devaluing school), and motivation among female students in traditional and non-traditional career paths. We predicted that the association between grades and discounting is affected by the importance of…

An Evaluation of a Welding Fumes Exhaust System. Agricultural Experiment Station Research Report 284.

ERIC Educational Resources Information Center

Jacobs, C. O.

A study evaluated the feasibility of introducing unheated outside air into the airstream of a cross-flow welding exhaust system to reduce heating energy costs of a school welding laboratory. The physical facility used was the agricultural mechanics laboratory at the University of Arizona, which is similar to facilities in which instruction in…

THE APPLICATION OF COMPUTATIONAL METHODS TO UNDERSTANDING THE HEALTH EFFECTS OF CHEMICALS IN THE ENVIRONMENT AND EVALUATING RISK: POLYCYCLIC AROMATIC HYDROCARBONS

EPA Science Inventory

Computational approaches have been applied to studying the toxicology of environmental agents for more than 50 years. These approaches have been used to enhance existing data, to provide understanding of the mechanisms of toxicity and as an aid in the evaluation of risks. However...

[Preparation of hydrophilic matrix sustained release tablets of total lactones from Andrographis paniculata and study on its in vitro release mechanism].

PubMed

Xu, Fang-Fang; Shi, Wei; Zhang, Hui; Guo, Qing-Ming; Wang Zhen-Zhong; Bi, Yu-An; Wang, Zhi-Min; Xiao, Wei

2015-01-01

In this study, hydrophilic matrix sustained release tablets of total lactones from Andrographis paniculata were prepared and the in vitro release behavior were also evaluated. The optimal prescription was achieved by studying the main factor of the type and amount of hydroxypropyl methylcellulose (HPMC) using single factor test and evaluating through cumulative release of three lactones. No burst drug release from the obtained matrix tablets was observed. Drug release sustained to 14 h. The release mechanism of three lactones from A. paniculata was accessed by zero-order, first-order, Higuchi and Peppas equation. The release behavior of total lactones from A. paniculata was better agreed with Higuchi model and the drug release from the tablets was controlled by degradation of the matrix. The preparation of hydrophilic matrix sustained release tablets of total lactones from A. paniculata with good performance of drug release was simple.

Animal models of pituitary neoplasia

PubMed Central

Lines, K.E.; Stevenson, M.; Thakker, R.V.

2016-01-01

Pituitary neoplasias can occur as part of a complex inherited disorder, or more commonly as sporadic (non-familial) disease. Studies of the molecular and genetic mechanisms causing such pituitary tumours have identified dysregulation of >35 genes, with many revealed by studies in mice, rats and zebrafish. Strategies used to generate these animal models have included gene knockout, gene knockin and transgenic over-expression, as well as chemical mutagenesis and drug induction. These animal models provide an important resource for investigation of tissue-specific tumourigenic mechanisms, and evaluations of novel therapies, illustrated by studies into multiple endocrine neoplasia type 1 (MEN1), a hereditary syndrome in which ∼30% of patients develop pituitary adenomas. This review describes animal models of pituitary neoplasia that have been generated, together with some recent advances in gene editing technologies, and an illustration of the use of the Men1 mouse as a pre clinical model for evaluating novel therapies. PMID:26320859

A mechanical jig for measuring ankle supination and pronation torque in vitro and in vivo.

PubMed

Fong, Daniel Tik-Pui; Chung, Mandy Man-Ling; Chan, Yue-Yan; Chan, Kai-Ming

2012-07-01

This study presents the design of a mechanical jig for evaluating the ankle joint torque on both cadaver and human ankles. Previous study showed that ankle sprain motion was a combination of plantarflexion and inversion. The device allows measurement of ankle supination and pronation torque with one simple axis in a single step motion. More importantly, the ankle orientation allows rotation starting from an anatomical position. Six cadaveric specimens and six human subjects were tested with simulated and voluntary rotation respectively. The presented mechanical jig makes possible the determination of supination torque for studying ankle sprain injury and the estimation of pronation torque for examining peroneal muscle response. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

Mechanical bowel preparation and oral antibiotic prophylaxis in colorectal surgery: Analysis of evidence and narrative review.

PubMed

Badia, Josep M; Arroyo-García, Nares

2018-05-14

The role of oral antibiotic prophylaxis and mechanical bowel preparation in colorectal surgery remains controversial. The lack of efficacy of mechanical preparation to improve infection rates, its adverse effects, and multimodal rehabilitation programs have led to a decline in its use. This review aims to evaluate current evidence on antegrade colonic cleansing combined with oral antibiotics for the prevention of surgical site infections. In experimental studies, oral antibiotics decrease the bacterial inoculum, both in the bowel lumen and surgical field. Clinical studies have shown a reduction in infection rates when oral antibiotic prophylaxis is combined with mechanical preparation. Oral antibiotics alone seem to be effective in reducing infection in observational studies, but their effect is inferior to the combined preparation. In conclusion, the combination of oral antibiotics and mechanical preparation should be considered the gold standard for the prophylaxis of postoperative infections in colorectal surgery. Copyright © 2018 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.

Modal analysis of the human neck in vivo as a criterion for crash test dummy evaluation

NASA Astrophysics Data System (ADS)

Willinger, R.; Bourdet, N.; Fischer, R.; Le Gall, F.

2005-10-01

Low speed rear impact remains an acute automative safety problem because of a lack of knowledge of the mechanical behaviour of the human neck early after impact. Poorly validated mathematical models of the human neck or crash test dummy necks make it difficult to optimize automotive seats and head rests. In this study we have constructed an experimental and theoretical modal analysis of the human head-neck system in the sagittal plane. The method has allowed us to identify the mechanical properties of the neck and to validate a mathematical model in the frequency domain. The extracted modal characteristics consist of a first natural frequency at 1.3±0.1 Hz associated with head flexion-extension motion and a second mode at 8±0.7 Hz associated with antero-posterior translation of the head, also called retraction motion. Based on this new validation parameters we have been able to compare the human and crash test dummy frequency response functions and to evaluate their biofidelity. Three head-neck systems of current test dummies dedicated for use in rear-end car crash accident investigations have been evaluated in the frequency domain. We did not consider any to be acceptable, either because of excessive rigidity of their flexion-extension mode or because they poorly reproduce the head translation mode. In addition to dummy evaluation, this study provides new insight into injury mechanisms when a given natural frequency can be linked to a specific neck deformation.

An exploration of group-based HIV/AIDS treatment and care models in Sub-Saharan Africa using a realist evaluation (Intervention-Context-Actor-Mechanism-Outcome) heuristic tool: a systematic review.

PubMed

Mukumbang, Ferdinand C; Van Belle, Sara; Marchal, Bruno; van Wyk, Brian

2017-08-25

It is increasingly acknowledged that differentiated care models hold potential to manage large volumes of patients on antiretroviral therapy (ART). Various group-based models of ART service delivery aimed at decongesting local health facilities, encouraging patient retention in care, and enhancing adherence to medication have been implemented across sub-Saharan Africa. Evidence from the literature suggests that these models of ART service delivery are more effective than corresponding facility-based care and superior to individual-based models. Nevertheless, there is little understanding of how these care models work to achieve their intended outcomes. The aim of this study was to review the theories explicating how and why group-based ART models work using a realist evaluation framework. A systematic review of the literature on group-based ART support models in sub-Saharan Africa was conducted. We searched the Google Scholar and PubMed databases and supplemented these with a reference chase of the identified articles. We applied a theory-driven approach-narrative synthesis-to synthesise the data. Data were analysed using the thematic content analysis method and synthesised according to aspects of the Intervention-Context-Actor-Mechanism-Outcome heuristic-analytic tool-a realist evaluation theory building tool. Twelve articles reporting primary studies on group-based models of ART service delivery were included in the review. The six studies that employed a quantitative study design failed to identify aspects of the context and mechanisms that work to trigger the outcomes of group-based models. While the other four studies that applied a qualitative and the two using a mixed methods design identified some of the aspects of the context and mechanisms that could trigger the outcomes of group-based ART models, these studies did not explain the relationship(s) between the theory elements and how they interact to produce the outcome(s). Although we could distill various components of the Intervention-Context-Actor-Mechanism-Outcome analytic tool from different studies exploring group-based programmes, we could not, however, identify a salient programme theory based on the Intervention-Context-Actor-Mechanism-Outcome heuristic analysis. The scientific community, policy makers and programme implementers would benefit more if explanatory findings of how, why, for whom and in what circumstances programmes work are presented rather than just reporting on the outcomes of the interventions.

Online Reflective Writing Mechanisms and Its Effects on Self-Regulated Learning: A Case of Web-Based Portfolio Assessment System

ERIC Educational Resources Information Center

Liang, Chaoyun; Chang, Chi-Cheng; Shu, Kuen-Ming; Tseng, Ju-Shih; Lin, Chun-Yu

2016-01-01

The purpose of the present study was to design reflective writing mechanisms in a web-based portfolio assessment system and evaluate its effects on self-regulated learning. Participants were two classes of juniors majoring in data processing and taking a course called "Website design" at a vocational high school in Taiwan. One class was…

A Novel Tool to Facilitate the Learning of Buffering Mechanism by Undergraduate Students of the Biological Area

ERIC Educational Resources Information Center

Carvalho, Eduardo O.; Nantes, Iseli L.

2008-01-01

In this study, the application and evaluation of a novel didactic tool (buffer kit) is described to make it easy for students in the biological area to overcome their conceptual deficiencies that render the learning of the buffering mechanism difficult. The buffer kit was constructed with double-face EVA cards with a conjugated acid formula…

Changes in Body Inertia During Bed Rest Studies

NASA Technical Reports Server (NTRS)

Todd, Beth A.

1999-01-01

Development of effective exercise countermeasures is crucial for long duration human space flight. To analyze the mechanical effects of a particular exercise on the musculoskeletal system, the inertial properties of segments of the body must be quantified. Since bone mineral density loss is related to the lack of mechanical stress and strain on the skeletal system, physical analysis can be very useful for countermeasure evaluation.

Mechanisms of repetitive retrograde contractions in response to sustained esophageal distension: a study evaluating patients with postfundoplication dysphagia.

PubMed

Carlson, Dustin A; Kahrilas, Peter J; Ritter, Katherine; Lin, Zhiyue; Pandolfino, John E

2018-03-01

Repetitive retrograde contractions (RRCs) in response to sustained esophageal distension are a distinct contractility pattern observed with functional luminal imaging probe (FLIP) panometry that are common in type III (spastic) achalasia. RRCs are hypothesized to be indicative of either impaired inhibitory innervation or esophageal outflow obstruction. We aimed to apply FLIP panometry to patients with postfundoplication dysphagia (a model of esophageal obstruction) to explore mechanisms behind RRCs. Adult patients with dysphagia after Nissen fundoplication ( n = 32) or type III achalasia ( n = 25) were evaluated with high-resolution manometry (HRM) and upper endoscopy with FLIP. HRM studies were assessed for outflow obstruction and spastic features: premature contractility, hypercontractility, and impaired deglutitive inhibition during multiple-rapid swallows. FLIP studies were analyzed to determine the esophagogastric junction (EGJ)-distensibility index and contractility pattern, including RRCs. Barium esophagram was evaluated when available. RRCs were present in 8/32 (25%) fundoplication and 19/25 (76%) achalasia patients ( P < 0.001). EGJ outflow obstruction was detected in 21 (67%) fundoplication patients by HRM, FLIP, or esophagram [6 (29%) had RRCs]. On HRM, none of the fundoplication patients had premature contractility, whereas 3/4 with defective inhibition on multiple-rapid swallows and 2/4 with hypercontractility had RRCs. Regression analysis demonstrated HRM with spastic features, but not esophageal outflow obstruction, as a predictor for RRCs. RRCs in response to sustained esophageal distension appear to be a manifestation of spastic esophageal motility. Although future study to further clarify the significance of RRCs is needed, RRCs on FLIP panometry should prompt evaluation for a major motor disorder. NEW & NOTEWORTHY Repetitive retrograde contractions (RRCs) are a common response to sustained esophageal distension among spastic achalasia patients when evaluated with the functional luminal imaging probe. We evaluated patients with postfundoplication dysphagia, i.e., patients with suspected mechanical obstruction, and found that RRCs occasionally occurred among postfundoplication patients, but often in association with manometric features of esophageal neuromuscular imbalance. Thus, RRCs appear to be a manifestation of spastic esophageal dysmotility, likely from neural imbalance resulting in excess excitation.

Antimicrobial Activity and Probable Mechanisms of Action of Medicinal Plants of Kenya: Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus

PubMed Central

Mwitari, Peter G.; Ayeka, Peter A.; Ondicho, Joyce; Matu, Esther N.; Bii, Christine C.

2013-01-01

Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus are used traditionally in Kenya for treatment of microbial infections and cancer. Information on their use is available, but scientific data on their bioactivity, safety and mechanisms of action is still scanty. A study was conducted on the effect of organic extracts of these plants on both bacterial and fungal strains, and their mechanisms of action. Extracts were evaluated through the disc diffusion assay. Bacteria and yeast test strains were cultured on Mueller-Hinton agar and on Sabouraud dextrose agar for the filamentous fungi. A 0.5 McFarland standard suspension was prepared. Sterile paper discs 6 mm in diameter impregnated with 10 µl of the test extract (100 mg/ml) were aseptically placed onto the surface of the inoculated media. Chloramphenicol (30 µg) and fluconazole (25 µg) were used as standards. Discs impregnated with dissolution medium were used as controls. Activity of the extracts was expressed according to zone of inhibition diameter. MIC was determined at 0.78–100 mg/ml. Safety studies were carried using Cell Counting Kit 8 cell proliferation assay protocol. To evaluate extracts mechanisms of action, IEC-6 cells and RT-PCR technique was employed in vitro to evaluate Interleukin 7 cytokine. Investigated plants extracts have both bactericidal and fungicidal activity. W. ugandensis is cytotoxic at IC50<50 µg/ml with MIC values of less than 0.78 mg/ml. Prunus africana shuts down expression of IL 7 mRNA at 50 µg/ml. W. somnifera has the best antimicrobial (1.5625 mg/ml), immunopotentiation (2 times IL 7 mRNA expression) and safety level (IC50>200 µg/ml). Fractions from W. ugandensis and W. somnifera too demonstrated antimicrobial activity. Mechanisms of action can largely be attributed to cytotoxicity, Gene silencing and immunopotentiation. Use of medicinal plants in traditional medicine has been justified and possible mechanisms of action demonstrated. Studies to isolate and characterize the bioactive constituents continue. PMID:23785437

Evaluating the Amount of Tooth Movement and Root Resorption during Canine Retraction with Friction versus Frictionless Mechanics Using Cone Beam Computed Tomography

PubMed Central

Makhlouf, Mohamed; Aboul–Ezz, Amr; Fayed, Mona Salah; Hafez, Hend

2018-01-01

BACKGROUND: The current study was carried out to compare the amount of tooth movement during canine retraction comparing two different retraction mechanics; friction mechanics represented by a NiTi closed coil spring versus frictionless mechanics represented by T - loop, and their effect on root resorption using Cone Beam Computed Tomography (CBCT). METHOD: Ten patients were selected in a split-mouth study design that had a malocclusion that necessitates the extraction of maxillary first premolars and retraction of maxillary canines. The right maxillary canines were retracted using T - loops fabricated from 0.017 X 0.025 TMA wires. The left maxillary canines received NiTi coil spring with 150 gm of retraction force. Pre retraction and post retraction Cone Beam Computed Tomography were taken to evaluate the amount of tooth movement and root resorption using three-dimensional planes. RESULTS: T - loop side showed statistically significant higher mean anteroposterior measurement than NiTi coil spring side, indicating a lower amount of canine movement pre and post a canine retraction. Concerning the root resorption, there was no statistically significant change in the mean measurements of canine root length post retraction. CONCLUSION: The NiTi coil spring side showed more distal movement more than the T-loop side. Both retraction mechanics with controlled retraction force, do not cause root resorption. PMID:29531610

Evaluating the Amount of Tooth Movement and Root Resorption during Canine Retraction with Friction versus Frictionless Mechanics Using Cone Beam Computed Tomography.

PubMed

Makhlouf, Mohamed; Aboul-Ezz, Amr; Fayed, Mona Salah; Hafez, Hend

2018-02-15

The current study was carried out to compare the amount of tooth movement during canine retraction comparing two different retraction mechanics; friction mechanics represented by a NiTi closed coil spring versus frictionless mechanics represented by T - loop, and their effect on root resorption using Cone Beam Computed Tomography (CBCT). Ten patients were selected in a split-mouth study design that had a malocclusion that necessitates the extraction of maxillary first premolars and retraction of maxillary canines. The right maxillary canines were retracted using T - loops fabricated from 0.017 X 0.025 TMA wires. The left maxillary canines received NiTi coil spring with 150 gm of retraction force. Pre retraction and post retraction Cone Beam Computed Tomography were taken to evaluate the amount of tooth movement and root resorption using three-dimensional planes. T - loop side showed statistically significant higher mean anteroposterior measurement than NiTi coil spring side, indicating a lower amount of canine movement pre and post a canine retraction. Concerning the root resorption, there was no statistically significant change in the mean measurements of canine root length post retraction. The NiTi coil spring side showed more distal movement more than the T-loop side. Both retraction mechanics with controlled retraction force, do not cause root resorption.

Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

NASA Astrophysics Data System (ADS)

Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

2018-04-01

Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

Quality of abdominal computed tomography angiography: hand versus mechanical intravenous contrast administration in children.

PubMed

Ayyala, Rama S; Zurakowski, David; Lee, Edward Y

2015-11-01

Abdominal CT angiography has been increasingly used for evaluation of various conditions related to abdominal vasculature in the pediatric population. However, no direct comparison has evaluated the quality of abdominal CT angiography in children using hand versus mechanical administration of intravenous (IV) contrast agent. To compare hand versus mechanical administration of IV contrast agent in the quality of abdominal CT angiography in the pediatric population. We retrospectively reviewed the electronic medical record to identify pediatric patients (≤18 years) who had abdominal CT angiography between August 2012 and August 2013. The information obtained includes: (1) type of administration of IV contrast agent (hand [group 1] versus mechanical [group 2]), (2) size (gauge) of IV catheter, (3) amount of contrast agent administered and (4) rate of contrast agent administration (ml/s). Two reviewers independently performed qualitative and quantitative evaluation of abdominal CT angiography image quality. Qualitative evaluation of abdominal CT angiography image quality was performed by visual assessment of the degree of contrast enhancement in the region of interest (ROI) based on a 4-point scale. Quantitative evaluation of each CT angiography examination was performed by measuring the Hounsfield unit (HU) using an ROI within the abdominal aorta at two levels (celiac axis and the inferior mesenteric artery) for each child. Analysis of variance (ANOVA) using the F-test was applied to compare contrast enhancement within the abdominal aorta at two levels (celiac axis and inferior mesenteric artery) between hand administration and mechanical administration of IV contrast methods with adjustment for age. We identified 46 pediatric patients (24 male, 22 female; mean age 7.3 ± 5.5 years; range 5 weeks to 18 years) with abdominal CT angiography performed during the study period. Of these patients, 16 (35%; 1.7 ± 2.2 years; range 5 weeks to 5 years) had hand administration of IV contrast agent and 30 (65%; 10.2 ± 4.2 years; range 4-18 years) had mechanical administration of IV contrast agent. All 46 abdominal CT angiography studies were of diagnostic quality based on qualitative evaluation (all ≥3). All abdominal CT angiography studies from both groups showed diagnostic quality of contrast enhancement (>150 HU) at both the celiac axis and the inferior mesenteric artery (IMA) levels. The contrast enhancement of the abdominal aorta was not significantly different between the IV contrast administration methods at either the celiac axis level (360 ± 158 vs. 353 ± 116, P = 0.24) or the IMA level (340 ± 140 vs. 351 ± 90, P = 0.27), adjusting for age. Diagnostic-quality abdominal CT angiography can be achieved using hand administration of IV contrast agent in infants and young children (≤5 years).

Mechanical properties and material characterization of polysialate structural composites

NASA Astrophysics Data System (ADS)

Foden, Andrew James

One of the major concerns in using Fiber Reinforced Composites in applications that are subjected to fire is their resistance to high temperature. Some of the fabrics used in FRC, such as carbon, are fire resistant. However, almost all the resins used cannot withstand temperatures higher than 200°C. This dissertation deals with the development and use of a potassium aluminosilicate (GEOPOLYMER) resin that is inorganic and can sustain more than 1000°C. The results presented include the mechanical properties of the unreinforced polysialate matrix in tension, flexure, and compression as well as the strain capacities and surface energy. The mechanical properties of the matrix reinforced with several different fabrics were obtained in flexure, tension, compression and shear. The strength and stiffness of the composite was evaluated for each loading condition. Tests were conducted on unexposed samples as well as samples exposed to temperatures from 200 to 1000°C. Fatigue properties were determined using flexural loading. A study of the effect of several processing variables on the properties of the composite was undertaken to determine the optimum procedure for manufacturing composite plates. The processing variables studied were the curing temperature and pressure, and the post cure drying time required to remove any residual water. The optimum manufacturing conditions were determined using the void content, density, fiber volume fraction, and flexural strength. Analytical models are presented based on both micro and macro mechanical analysis of the composite. Classic laminate theory is used to evaluate the state of the composite as it is being loaded to determine the failure mechanisms. Several failure criteria theories are considered. The analysis is then used to explain the mechanical behavior of the composite that was observed during the experimental study.

Accelerated aging studies of UHMWPE. I. Effect of resin, processing, and radiation environment on resistance to mechanical degradation.

PubMed

Edidin, A A; Herr, M P; Villarraga, M L; Muth, J; Yau, S S; Kurtz, S M

2002-08-01

The resin and processing route have been identified as potential variables influencing the mechanical behavior, and hence the clinical performance, of ultra-high molecular weight polyethylene (UHMWPE) orthopedic components. Researchers have reported that components fabricated from 1900 resin may oxidize to a lesser extent than components fabricated from GUR resin during shelf aging after gamma sterilization in air. Conflicting reports on the oxidation resistance for 1900 raise the question of whether resin or manufacturing method, or an interaction between resin and manufacturing method, influences the mechanical behavior of UHMWPE. We conducted a series of accelerated aging studies (no aging, aging in oxygen or in nitrogen) to systematically examine the influence of resin (GUR or 1900), manufacturing method (bulk compression molding or extrusion), and sterilization method (none, in air, or in nitrogen) on the mechanical behavior of UHMWPE. The small punch testing technique was used to evaluate the mechanical behavior of the materials, and Fourier transform infrared spectroscopy was used to characterize the oxidation in selected samples. Our study showed that the sterilization environment, aging condition, and specimen location (surface or subsurface) significantly affected the mechanical behavior of UHMWPE. Each of the three polyethylenes evaluated seem to degrade according to a similar pathway after artificial aging in oxygen and gamma irradiation in air. The initial ability of the materials to exhibit post-yield strain hardening was significantly compromised by degradation. In general, there were only minor differences in the aging behavior of molded and extruded GUR 1050, whereas the molded 1900 material seemed to degrade slightly faster than either of the 1050 materials. Copyright 2002 Wiley Periodicals, Inc.

Music therapy as an adjunctive treatment in the management of stress for patients being weaned from mechanical ventilation.

PubMed

Hunter, Bryan C; Oliva, Rosemary; Sahler, Olle Jane Z; Gaisser, D'Arcy; Salipante, Diane M; Arezina, Clare H

2010-01-01

This project investigated music therapy (MT) in managing anxiety associated with weaning from mechanical ventilation. The use of sedation to treat anxiety during weaning is problematic because side effects (e.g., respiratory depression) are precisely the symptoms that cause the weaning process to be interrupted and consequently prolonged. Study goals were to determine the feasibility of incorporating MT into the weaning process and to evaluate the efficacy of the intervention, based on levels of anxiety, Days to Wean (DTW), and patient/nurse satisfaction. Adult patients received multiple MT sessions per week while undergoing weaning trials from mechanical ventilation. Feasibility was determined by successful enrollment in the study and nurse survey. Efficacy was evaluated through anxiety, as measured by heart rate, respiratory rate, and patient/nurse survey; DTW; and patient/nurse satisfaction. Nurse surveys reported that MT was successfully incorporated into the milieu and 61 subjects were enrolled. Significant differences in heart rate and respiratory rate were found from the beginning to the end of MT sessions (p < .05 and p < .0001, respectively), indicating a more relaxed state. No significant difference in mean DTW was found between study and control subjects. Patient/nurse satisfaction was high. Music therapy can be used successfully to treat anxiety associated with weaning from mechanical ventilation. Limitations and suggestions for further research are discussed.

Mechanism of mesenchymal stem cell-induced neuron recovery and anti-inflammation.

PubMed

Huang, Peng; Gebhart, Nichole; Richelson, Elliott; Brott, Thomas G; Meschia, James F; Zubair, Abba C

2014-10-01

After ischemic or hemorrhagic stroke, neurons in the penumbra surrounding regions of irreversible injury are vulnerable to delayed but progressive damage as a result of ischemia and hemin-induced neurotoxicity. There is no effective treatment to rescue such dying neurons. Mesenchymal stem cells (MSCs) hold promise for rescue of these damaged neurons. In this study, we evaluated the efficacy and mechanism of MSC-induced neuro-regeneration and immune modulation. Oxygen-glucose deprivation (OGD) was used in our study. M17 neuronal cells were subjected to OGD stress then followed by co-culture with MSCs. Rescue effects were evaluated using proliferation and apoptosis assays. Cytokine assay and quantitative polymerase chain reaction were used to explore the underlying mechanism. Antibody and small molecule blocking experiments were also performed to further understand the mechanism. We showed that M17 proliferation was significantly decreased and the rate of apoptosis increased after exposure to OGD. These effects could be alleviated via co-culture with MSCs. Tumor necrosis factor-α was found elevated after OGD stress and was back to normal levels after co-culture with MSCs. We believe these effects involve interleukin-6 and vascular endothelial growth factor signaling pathways. Our studies have shown that MSCs have anti-inflammatory properties and the capacity to rescue injured neurons. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Comparative analysis of torsional and bending behavior through finite-element models of 5 Ni-Ti endodontic instruments.

PubMed

Arbab-Chirani, Reza; Chevalier, Valérie; Arbab-Chirani, Shabnam; Calloch, Sylvain

2011-01-01

The objectives of this study were to compare numerically the bending and torsional mechanical behavior of 5 endodontic rotary Ni-Ti instruments with equivalent size and various designs for tapers, pitch, and cutting blades.First, the geometries of Hero (20/0.06), HeroShaper (20/0.06), ProFile (20/0.06), Mtwo (20/0.06), and ProTaper F1 were generated by finite element code. Then, the 2 most representative clinical loadings, i.e., bending and torsion, were studied with an ad hoc model for the superelasticity of Ni-Ti. Bending was generated by tip deflection and torsion by a constant twist-angle of the tip. Mechanical behavior of these 5 endodontic rotary Ni-Ti instruments could be evaluated and compared. Protaper F1 presented the greatest level of bending stress and torque. Hero and HeroShaper were more rigid than ProFile and Mtwo. This numerical comparison evaluated the effects of the geometrical parameters on the instrumental mechanical behavior. The 5 endodontic instruments, investigated in the present study, do not have the same bending and torsional mechanical behavior. Each clinician must be aware of these behavior differences so as to use the adequate file according to the clinical situation and to the manufacturer's recommendations. Copyright © 2011 Mosby, Inc. All rights reserved.

Assessment and Evaluation for Programme Learning Outcomes in Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia

NASA Astrophysics Data System (ADS)

Pauline, Ong; Taib, Hariati; AzwirAzlan, Mohd; Fitriah Nasir, Nurul; Azham Azmi, Mohd; Salleh, Saliha Md; Zain, Badrul Aisham Md; Mahzan, Shahruddin; Hafeez Zainulabidin, Muhd; Ahmad, Sufizar; Rahman, Nasrull Abd; Ngali, Zamani; Rahman, Hamimah Abd

2017-01-01

Universiti Tun Hussein Onn Malaysia (UTHM) is the 15th of the 20 public universities established in Malaysia. UTHM consists of eight faculties. One of them is the Faculty of Mechanical and Manufacturing Engineering (FKMP). The programme offered - Bachelor of Mechanical Engineering with Honours (BDD), undergoes continuous auditing and accreditation by the Engineering Accreditation Council (EAC). To fulfill the requirement for accreditation, EAC requires the faculty to assess and evaluate the programme learning outcomes’ (PLOs) attainment of the graduates, such that all graduates are targeted to achieve the performance indicator (PI) upon graduation. This paper discusses the methods developed by the FKMP for PLOs’ measurement and evaluation. Two approaches are utilized in this regards, (i) the direct assessment based on students’ performance in courses, and (ii) the indirect assessment based the industrial and graduates’ perception. The PLOs’ attainment for graduates of cohort 2010-2012 are analysed in this study. Consolidation data shows that the PI for majority of the PLOs are achieved, indicating that the programme offered complies with the standard expected by different stakeholders.

Gastroprotective Effect of Geopropolis from Melipona scutellaris Is Dependent on Production of Nitric Oxide and Prostaglandin.

PubMed

Ribeiro-Junior, Jerônimo Aparecido; Franchin, Marcelo; Cavallini, Miriam Elias; Denny, Carina; de Alencar, Severino Matias; Ikegaki, Masaharu; Rosalen, Pedro Luiz

2015-01-01

The aim of this study was to evaluate the gastroprotective activity of ethanolic extract of geopropolis (EEGP) from Melipona scutellaris and to investigate the possible mechanisms of action. The gastroprotective activity of the EEGP was evaluated using model ulcer induced by ethanol. To elucidate the possible mechanisms of action, we investigated the involvement of the nonprotein sulfhydryl (NP-SH) groups, nitric oxide and prostaglandins. In addition, the antisecretory activity of EEGP was also evaluated by pylorus ligated model. The EEGP orally administrated (300 mg/kg) reduced the ulcerative lesions induced by the ethanol (P < 0.05). Regarding the mechanism of action, the prior administration of nitric oxide and prostaglandins antagonists suppressed the activity of gastroprotective EEGP (P < 0.05). On the other hand the gastroprotective activity of EEGP was kept in the group pretreated with the antagonist of the NP-SH groups; furthermore the antisecretory activity was not significant (P > 0.05). These results support the alternative medicine use of geopropolis as gastroprotective and the activities observed show to be related to nitric oxide and prostaglandins production.

Gastroprotective Effect of Geopropolis from Melipona scutellaris Is Dependent on Production of Nitric Oxide and Prostaglandin

PubMed Central

Ribeiro-Junior, Jerônimo Aparecido; Franchin, Marcelo; Cavallini, Miriam Elias; Denny, Carina; de Alencar, Severino Matias; Ikegaki, Masaharu; Rosalen, Pedro Luiz

2015-01-01

The aim of this study was to evaluate the gastroprotective activity of ethanolic extract of geopropolis (EEGP) from Melipona scutellaris and to investigate the possible mechanisms of action. The gastroprotective activity of the EEGP was evaluated using model ulcer induced by ethanol. To elucidate the possible mechanisms of action, we investigated the involvement of the nonprotein sulfhydryl (NP-SH) groups, nitric oxide and prostaglandins. In addition, the antisecretory activity of EEGP was also evaluated by pylorus ligated model. The EEGP orally administrated (300 mg/kg) reduced the ulcerative lesions induced by the ethanol (P < 0.05). Regarding the mechanism of action, the prior administration of nitric oxide and prostaglandins antagonists suppressed the activity of gastroprotective EEGP (P < 0.05). On the other hand the gastroprotective activity of EEGP was kept in the group pretreated with the antagonist of the NP-SH groups; furthermore the antisecretory activity was not significant (P > 0.05). These results support the alternative medicine use of geopropolis as gastroprotective and the activities observed show to be related to nitric oxide and prostaglandins production. PMID:25949263

A Study on Coexistence Capability Evaluations of the Enhanced Channel Hopping Mechanism in WBANs

PubMed Central

Wei, Zhongcheng; Sun, Yongmei; Ji, Yuefeng

2017-01-01

As an important coexistence technology, channel hopping can reduce the interference among Wireless Body Area Networks (WBANs). However, it simultaneously brings some issues, such as energy waste, long latency and communication interruptions, etc. In this paper, we propose an enhanced channel hopping mechanism that allows multiple WBANs coexisted in the same channel. In order to evaluate the coexistence performance, some critical metrics are designed to reflect the possibility of channel conflict. Furthermore, by taking the queuing and non-queuing behaviors into consideration, we present a set of analysis approaches to evaluate the coexistence capability. On the one hand, we present both service-dependent and service-independent analysis models to estimate the number of coexisting WBANs. On the other hand, based on the uniform distribution assumption and the additive property of Possion-stream, we put forward two approximate methods to compute the number of occupied channels. Extensive simulation results demonstrate that our estimation approaches can provide an effective solution for coexistence capability estimation. Moreover, the enhanced channel hopping mechanism can significantly improve the coexistence capability and support a larger arrival rate of WBANs. PMID:28098818

The Multi-Country Evaluation of the Integrated Management of Childhood Illness Strategy: Lessons for the Evaluation of Public Health Interventions

PubMed Central

Bryce, Jennifer; Victora, Cesar G.; Habicht, Jean-Pierre; Vaughan, J. Patrick; Black, Robert E.

2004-01-01

The Multi-Country Evaluation of the Integrated Management of Childhood Illness (IMCI) includes studies of the effectiveness, cost, and impact of the IMCI strategy in Bangladesh, Brazil, Peru, Tanzania, and Uganda. Seven questions were addressed when the evaluation was designed: who would be in charge, through what mechanisms IMCI could affect child health, whether the focus would be efficacy or effectiveness, what indicators would be measured, what types of inference would be made, how costs would be incorporated, and what elements would constitute the plan of analysis. We describe how these questions were answered, the challenges encountered in implementing the evaluation, and the 5 study designs. The methodological insights gained can improve future evaluations of public health programs. PMID:14998804

Morphological and Mechanical Properties of Polypropylene[PP]/Poly(Ethylene Vinyl Acetate)[EVA] Blends. I. Homopolymer PP/Eva Systems

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

Ramirez-Vargas, E.

2000-10-01

Morphological and mechanical properties of polypropylene [PP]/poly(ethylene vinyl acetate) [EVA] blends have been studied. Infrared results using thin films first indicated a transition toward compatibility between both components at concentrations above 40% EVA. The transition was verified with different experimental techniques and it was associated to morphological changes and mechanical properties. The PP/EVA blends were mechanically evaluated in terms of impact and tensile strength to determine the influence of blending on the performance properties of these materials. Agreement was found between the transition and the enhancement of both elongation at break and impact strength.

An evaluation of instruments for scoring physiological and behavioral cues of pain, non-pain related distress, and adequacy of analgesia and sedation in pediatric mechanically ventilated patients: A systematic review.

PubMed

Dorfman, Tamara L; Sumamo Schellenberg, Elizabeth; Rempel, Gwen R; Scott, Shannon D; Hartling, Lisa

2014-04-01

Advancing technology allows for successful treatment of children with life-threatening illnesses. Effectively assessing and optimally treating a child's distress during their stay in the Pediatric Intensive Care Unit (PICU) is paramount. Objective measures of distress in mechanically ventilated pediatric patients are increasingly available but few have been evaluated. The objectives of this systematic review were to identify available instruments appropriate for measuring physiological and behavioral cues of pain, non-pain related distress, and adequacy of analgesia and sedation in mechanically ventilated pediatric patients, and evaluate these instruments in terms of their psychometric properties. A systematic review of original and validation reports of objective instruments to measure pain and non-pain related distress, and adequacy of analgesia and sedation in mechanically ventilated PICU patients was undertaken. A comprehensive search was conducted in 10 databases from January 1970 to June 2011. Reference lists of relevant articles were reviewed to identify additional articles. Studies were included in the review if they met pre-established eligibility criteria. Two independent reviewers reviewed studies for inclusion, assessed quality, and extracted data. Twenty-five articles were included, identifying 15 instruments. The instruments had different foci including: assessing pain, non-pain related distress, and sedation (n=2); assessing pain exclusively (n=4); assessing sedation exclusively (n=7), assessing sedation in mechanically ventilated muscle relaxed PICU patients (n=1); and assessing delirium in mechanically ventilated PICU patients (n=1). The Comfort Scale demonstrated the greatest clinical utility in the assessment of pain, non-pain related distress, and sedation in mechanically ventilated pediatric patients. Modified FLACC and the MAPS are more appropriate, however, for the assessment of procedural pain and other brief painful events. More work is required on instruments for the assessment of distress in mechanically ventilated muscle relaxed PICU patients, and the assessment of delirium in PICU patients. This review provides essential information to guide PICU clinicians in choosing instruments to assess pain, non-pain related distress, and adequacy of analgesia and sedation in mechanically ventilated pediatric patients. Effective knowledge translation is essential in the implementation, adoption, and successful use of these instruments. Copyright © 2013 Elsevier Ltd. All rights reserved.

A new method for measuring mechanical properties of laryngeal mucosa.

PubMed

Hemler, R J; Wieneke, G H; van Riel, A M; Lebacq, J; Dejonckere, P H

2001-03-01

A study of the effect of exogenous hazardous agents or conditions on the mechanical characteristics of vocal fold mucosa should meet three methodological criteria. 1) The outer surface of the mucosa should be exposed to the agent or condition while the inner surface is exposed to a physiological environment. 2) Even slight changes in mechanical characteristics should be detected. 3) The applied strain should be within physiological ranges. To date, no such method has been described in the literature. A method meeting the listed criteria is proposed and evaluated here.

Activations of the dorsolateral prefrontal cortex and thalamus during agentic self-evaluation are negatively associated with trait self-esteem.

PubMed

Jiang, Ke; Wu, Shi; Shi, Zhenhao; Liu, Mingyan; Peng, Maoying; Shen, Yang; Yang, Juan

2018-08-01

Individual self-esteem is dominated more by agency than by communion. However, prior research has mainly focused on one's agentic/communal self-evaluation, while little is known about how one endorses others' agentic/communal evaluation of the self. The present study investigated the associations between trait self-esteem and fundamental dimensions of social cognition, i.e. agency vs. communion, during both self-evaluation and endorsement of others' evaluation of oneself. We also investigated the neural mechanisms underlying the relationship between trait self-esteem and agentic self-evaluation. Behavioral results revealed that self-esteem was positively correlated with the agentic ratings from self-evaluation and endorsement of others' evaluation of the self, and that the agentic self-evaluation was a significant full mediator between self-esteem and endorsement of others' agentic evaluation. Whole-brain regression analysis revealed that self-esteem was negatively correlated with right dorsolateral prefrontal and bilateral thalamic response to agentic self-evaluation. A possible interpretation is that low self-esteem people both hold a more self-critical attitude about the self and have less certainty or clarity of their self-concepts than high self-esteem people do. These findings have important implication for understanding the neural and cognitive mechanisms underlying self-esteem's effect on one's agentic self-evaluations. Copyright © 2018 Elsevier B.V. All rights reserved.

Critical evaluation of Jet-A spray combustion using propane chemical kinetics in gas turbine combustion simulated by KIVA-2

NASA Technical Reports Server (NTRS)

Nguyen, H. L.; Ying, S.-J.

1990-01-01

Jet-A spray combustion has been evaluated in gas turbine combustion with the use of propane chemical kinetics as the first approximation for the chemical reactions. Here, the numerical solutions are obtained by using the KIVA-2 computer code. The KIVA-2 code is the most developed of the available multidimensional combustion computer programs for application of the in-cylinder combustion dynamics of internal combustion engines. The released version of KIVA-2 assumes that 12 chemical species are present; the code uses an Arrhenius kinetic-controlled combustion model governed by a four-step global chemical reaction and six equilibrium reactions. Researchers efforts involve the addition of Jet-A thermophysical properties and the implementation of detailed reaction mechanisms for propane oxidation. Three different detailed reaction mechanism models are considered. The first model consists of 131 reactions and 45 species. This is considered as the full mechanism which is developed through the study of chemical kinetics of propane combustion in an enclosed chamber. The full mechanism is evaluated by comparing calculated ignition delay times with available shock tube data. However, these detailed reactions occupy too much computer memory and CPU time for the computation. Therefore, it only serves as a benchmark case by which to evaluate other simplified models. Two possible simplified models were tested in the existing computer code KIVA-2 for the same conditions as used with the full mechanism. One model is obtained through a sensitivity analysis using LSENS, the general kinetics and sensitivity analysis program code of D. A. Bittker and K. Radhakrishnan. This model consists of 45 chemical reactions and 27 species. The other model is based on the work published by C. K. Westbrook and F. L. Dryer.

Occipital artery vasculitis not identified as a mechanism of occipital neuralgia-related chronic migraine headaches.

PubMed

Ducic, Ivica; Felder, John M; Janis, Jeffrey E

2011-10-01

Recent evidence has shown that some cases of occipital neuralgia are attributable to musculofascial compression of the greater occipital nerve and improve with neurolysis. A mechanical interaction at the intersection of the nerve and the occipital artery may also be capable of producing neuralgia, although that mechanism remains one theoretical possibility among several. The authors evaluated the possibility of unrecognized vasculitis of the occipital artery as a potential mechanism of occipital neuralgia arising from the occipital artery/greater occipital nerve junction. Twenty-five patients with preoperatively documented bilateral occipital neuralgia-related chronic headaches underwent peripheral nerve surgery with decompression of the greater occipital nerve bilaterally, including the area of its intersection with the occipital artery. In 15 patients, a 2-cm segment of the occipital artery was excised and submitted for pathologic evaluation. All patients were evaluated intraoperatively for evidence of arterially mediated greater occipital nerve compression, and the configuration of the nerve-vessel intersection was noted. None of the 15 specimens submitted for pathologic evaluation showed vasculitis. Intraoperatively, all 50 sites examined showed an intimate physical association between the occipital artery and greater occipital nerve. Surgical specimens from this first in vivo study provided no histologic evidence of vasculitis as a cause of greater occipital nerve irritation at the occipital artery/greater occipital nerve junction in patients with chronic headaches caused by occipital neuralgia. Based on these findings, mechanical (and not primary inflammatory) irritation of the nerve by the occipital artery remains an important theoretical cause for otherwise idiopathic cases. The authors have adopted an operative technique that includes physical separation of the nerve-artery intersection (in addition to musculofascial neurolysis) for a more thorough surgical treatment of occipital neuralgia. Therapeutic, IV.

An atomistic-based chemophysical environment for evaluating asphalt oxidation and antioxidants.

PubMed

Pan, Tongyan; Sun, Lu; Yu, Qifeng

2012-12-01

Asphalt binders in service conditions are subject to oxidative aging that involves the reactions between oxygen molecules and the component species of bulk asphalt. As a result, significant alterations can occur to the desired physical and/or mechanical properties of asphalt. A common practice to alleviate asphalt aging has been to employ different chemical additives or modifiers as antioxidants. The current state of knowledge in asphalt oxidation and antioxidant evaluation is centered on determining the degradation of asphalt physical properties, mainly the viscosity and ductility. Such practices, although meeting direct engineering needs, do not contribute to the fundamental understanding of the aging and anti-oxidation mechanisms, and thereby developing anti-aging strategies. From this standpoint, this study was initiated to study the chemical and physical bases of asphalt oxidation, as well as the anti-oxidation mechanisms of bio-based antioxidants using the coniferyl-alcohol lignin as an example. A quantum chemistry (QC) based chemophysical environment is developed, in which the various chemical reactions between asphalt component species and oxygen, as well as the incurred physical changes are studied. X-ray photoelectron spectroscopy (XPS) was used to validate the modified and unmodified asphalt models.

Privacy in Pharmacogenetics: An End-to-End Case Study of Personalized Warfarin Dosing.

PubMed

Fredrikson, Matthew; Lantz, Eric; Jha, Somesh; Lin, Simon; Page, David; Ristenpart, Thomas

2014-08-01

We initiate the study of privacy in pharmacogenetics, wherein machine learning models are used to guide medical treatments based on a patient's genotype and background. Performing an in-depth case study on privacy in personalized warfarin dosing, we show that suggested models carry privacy risks, in particular because attackers can perform what we call model inversion : an attacker, given the model and some demographic information about a patient, can predict the patient's genetic markers. As differential privacy (DP) is an oft-proposed solution for medical settings such as this, we evaluate its effectiveness for building private versions of pharmacogenetic models. We show that DP mechanisms prevent our model inversion attacks when the privacy budget is carefully selected . We go on to analyze the impact on utility by performing simulated clinical trials with DP dosing models. We find that for privacy budgets effective at preventing attacks, patients would be exposed to increased risk of stroke, bleeding events, and mortality . We conclude that current DP mechanisms do not simultaneously improve genomic privacy while retaining desirable clinical efficacy, highlighting the need for new mechanisms that should be evaluated in situ using the general methodology introduced by our work.

Privacy in Pharmacogenetics: An End-to-End Case Study of Personalized Warfarin Dosing

PubMed Central

Fredrikson, Matthew; Lantz, Eric; Jha, Somesh; Lin, Simon; Page, David; Ristenpart, Thomas

2014-01-01

We initiate the study of privacy in pharmacogenetics, wherein machine learning models are used to guide medical treatments based on a patient’s genotype and background. Performing an in-depth case study on privacy in personalized warfarin dosing, we show that suggested models carry privacy risks, in particular because attackers can perform what we call model inversion: an attacker, given the model and some demographic information about a patient, can predict the patient’s genetic markers. As differential privacy (DP) is an oft-proposed solution for medical settings such as this, we evaluate its effectiveness for building private versions of pharmacogenetic models. We show that DP mechanisms prevent our model inversion attacks when the privacy budget is carefully selected. We go on to analyze the impact on utility by performing simulated clinical trials with DP dosing models. We find that for privacy budgets effective at preventing attacks, patients would be exposed to increased risk of stroke, bleeding events, and mortality. We conclude that current DP mechanisms do not simultaneously improve genomic privacy while retaining desirable clinical efficacy, highlighting the need for new mechanisms that should be evaluated in situ using the general methodology introduced by our work. PMID:27077138

Long-Term In Vitro Degradation of a High-Strength Brushite Cement in Water, PBS, and Serum Solution

PubMed Central

Ajaxon, Ingrid; Öhman, Caroline; Persson, Cecilia

2015-01-01

Bone loss and fractures may call for the use of bone substituting materials, such as calcium phosphate cements (CPCs). CPCs can be degradable, and, to determine their limitations in terms of applications, their mechanical as well as chemical properties need to be evaluated over longer periods of time, under physiological conditions. However, there is lack of data on how the in vitro degradation affects high-strength brushite CPCs over longer periods of time, that is, longer than it takes for a bone fracture to heal. This study aimed at evaluating the long-term in vitro degradation properties of a high-strength brushite CPC in three different solutions: water, phosphate buffered saline, and a serum solution. Microcomputed tomography was used to evaluate the degradation nondestructively, complemented with gravimetric analysis. The compressive strength, chemical composition, and microstructure were also evaluated. Major changes from 10 weeks onwards were seen, in terms of formation of a porous outer layer of octacalcium phosphate on the specimens with a concomitant change in phase composition, increased porosity, decrease in object volume, and mechanical properties. This study illustrates the importance of long-term evaluation of similar cement compositions to be able to predict the material's physical changes over a relevant time frame. PMID:26587540

Efficacy of anti-retraction devices in preventing bacterial contamination of dental unit water lines.

PubMed

Berlutti, Francesca; Testarelli, Luca; Vaia, Francesco; De Luca, Massimo; Dolci, Giovanni

2003-02-01

In this study we examine the efficacy of anti-retraction devices in preventing microbial contamination of dental unit water lines (DUWLs). The study was performed on 54 randomly selected DUs in use at private and public institutions for over six months. The selected DUs were all currently commercially available. To evaluate the efficiency of anti-retraction devices, two different methods were employed, mechanical and microbiological. The ADA/ANSI specification #47 (corresponding to a water retraction of less than 40.3 microl) was used for the evaluation of the retraction determined using the mechanical method; the presence/absence of test microorganisms in DUWLs upstream the turbine after the test was used for evaluating the microbiological assay. Both evaluation methods indicated correct amounts of retraction and prevention of DUWL contamination occurred in only two cases (3.7%). Correct retraction was noted in six other dental units (DUs), but their DUWLs became contaminated during testing. Six other produced the opposite results-improper retraction, yet no contamination. The remaining 40 DUs (74.0%) failed both evaluations. The results showed that the overwhelming majority of the anti-retraction devices did not prevent retraction when the turbine stopped running, leading to a contamination of the water lines, and to a consequent possible cross-contamination of the patients.

Coatings could protect composites from hostile space environment

NASA Technical Reports Server (NTRS)

Whitaker, Ann F.

1991-01-01

An experiment has been conducted on about 100 different material/process combinations, most of which were candidates for use in solar arrays having high power-to-weight ratios. These substances were exposed to the LEO environment during Long-Duration Exposure Facility Experiment A0171 in order to evaluate the synergistic effects of the LEO environment on the materials' mechanical, electrical, and optical properties. Materials evaluated include solar cells, cover slips having antireflectance coatings, adhesives, encapsulants, reflective materials, mast and harness materials, structural composites, and thermal control thin films. About one-sixth of the experiment tray was devoted to composite-material tensile specimens, which were specifically to be studied for changes in their mechanical properties. Preliminary results of the surface-damage evaluation are presented. These surface effects are dominated by atomic-oxygen erosion and micrometeoroid/space debris impacts.

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

Toro, Javier, E-mail: jjtoroca@unal.edu.c; Requena, Ignacio, E-mail: requena@decsai.ugr.e; Zamorano, Montserrat, E-mail: zamorano@ugr.e

The evaluation of Environmental Impact Assessment (EIA) systems is a highly recommended strategy for enhancing their effectiveness and quality. This paper describes an evaluation of EIA in Colombia, using the model and the control mechanisms proposed and applied in other countries by Christopher Wood and Ortolano. The evaluation criteria used are based on Principles of Environmental Impact Assessment Best Practice, such as effectiveness and control features, and they were contrasted with the opinions of a panel of Colombian EIA experts as a means of validating the results of the study. The results found that EIA regulations in Colombia were ineffectivemore » because of limited scope, inadequate administrative support and the inexistence of effective control mechanisms and public participation. This analysis resulted in a series of recommendations regarding the further development of the EIA system in Colombia with a view to improving its quality and effectiveness.« less

Fundamental Effects of Aging on Creep Properties of Solution-Treated Low-Carbon N-155 Alloy

NASA Technical Reports Server (NTRS)

Frey, D N; Freeman, J W; White, A E

1950-01-01

A method is developed whereby the fundamental mechanisms are investigated by which processing, heat treatment, and chemical composition control the properties of alloys at high temperatures. The method used metallographic examination -- both optical and electronic --studies of x-ray diffraction-line widths, intensities, and lattice parameters, and hardness surveys to evaluate fundamental structural conditions. Mechanical properties at high temperatures are then measured and correlated with these measured structural conditions. In accordance with this method, a study was made of the fundamental mechanism by which aging controlled the short-time creep and rupture properties of solution-treated low-carbon n-155 alloy at 1200 degrees F.

Fracture-Based Mesh Size Requirements for Matrix Cracks in Continuum Damage Mechanics Models

NASA Technical Reports Server (NTRS)

Leone, Frank A.; Davila, Carlos G.; Mabson, Gerald E.; Ramnath, Madhavadas; Hyder, Imran

2017-01-01

This paper evaluates the ability of progressive damage analysis (PDA) finite element (FE) models to predict transverse matrix cracks in unidirectional composites. The results of the analyses are compared to closed-form linear elastic fracture mechanics (LEFM) solutions. Matrix cracks in fiber-reinforced composite materials subjected to mode I and mode II loading are studied using continuum damage mechanics and zero-thickness cohesive zone modeling approaches. The FE models used in this study are built parametrically so as to investigate several model input variables and the limits associated with matching the upper-bound LEFM solutions. Specifically, the sensitivity of the PDA FE model results to changes in strength and element size are investigated.

Characterization of Thermal and Mechanical Impact on Aluminum Honeycomb Structures

NASA Technical Reports Server (NTRS)

Robinson, Christen M.

2013-01-01

This study supports NASA Kennedy Space Center's research in the area of intelligent thermal management systems and multifunctional thermal systems. This project addresses the evaluation of the mechanical and thermal properties of metallic cellular solid (MCS) materials; those that are lightweight; high strength, tunable, multifunctional and affordable. A portion of the work includes understanding the mechanical properties of honeycomb structured cellular solids upon impact testing under ambient, water-immersed, liquid nitrogen-cooled, and liquid nitrogen-immersed conditions. Additionally, this study will address characterization techniques of the aluminum honeycomb's ability to resist multiple high-rate loadings or impacts in varying environmental conditions, using various techniques for the quantitative and qualitative determination for commercial applicability.

Radiation induced rotation of interplanetary dust particles - A feasibility study for a space experiment

NASA Technical Reports Server (NTRS)

Ratcliff, K. F.; Misconi, N. Y.; Paddack, S. J.

1980-01-01

Irregular interplanetary dust particles may acquire a considerable spin rate due to two non-statistical dynamical mechanisms induced by solar radiation. These arise from variations in surface albedo discussed by Radzievskii (1954) and from irregularities in surface geometry discussed by Paddack (1969). An experiment is reported which will lead to an evaluation in space of the effectiveness of these two spin mechanisms. The technique of optical levitation in an argon laser beam provides a stable trap for particles 10-60 microns in diameter. The objective is to design an optical trap for dielectric particles in vacuum to study these rotation mechanisms in the gravity-free environment of a Spacelab experiment.

Experimental study of cyclic creep and high-cycle fatigue of welded joints of St3 steel by the DIC technique

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

Kibitkin, Vladimir V., E-mail: vvk@ispms.tsc.ru; Solodushkin, Andrey I., E-mail: s.ai@sibmail.com; Pleshanov, Vasily S., E-mail: vsp@ispms.tsc.ru

In the paper the mechanisms of plastic deformation and fracture of welded joints of steel St3 were investigated at high-cycle fatigue and cyclic creep by the digital image correlation (DIC) technique. The evolution of strain rate is studied for the following regions: base metal, HAZ, and fusion zone. This strain rate evolution can be considered as a mechanical response of material. Three stages of deformation evolution are shown: deformation hardening (I), fatigue crack initiation (II), and the last stage is related to main crack (III). Two criteria are offered to evaluate the current mechanical state of welded joints.

An interdisciplinary framework for participatory modeling design and evaluation—What makes models effective participatory decision tools?

NASA Astrophysics Data System (ADS)

Falconi, Stefanie M.; Palmer, Richard N.

2017-02-01

Increased requirements for public involvement in water resources management (WRM) over the past century have stimulated the development of more collaborative decision-making methods. Participatory modeling (PM) uses computer models to inform and engage stakeholders in the planning process in order to influence collaborative decisions in WRM. Past evaluations of participatory models focused on process and final outcomes, yet, were hindered by diversity of purpose and inconsistent documentation. This paper presents a two-stage framework for evaluating PM based on mechanisms for improving model effectiveness as participatory tools. The five dimensions characterize the "who, when, how, and why" of each participatory effort (stage 1). Models are evaluated as "boundary objects," a concept used to describe tools that bridge understanding and translate different bodies of knowledge to improve credibility, salience, and legitimacy (stage 2). This evaluation framework is applied to five existing case studies from the literature. Though the goals of participation can be diverse, the novel contribution of the two-stage proposed framework is the flexibility it has to evaluate a wide range of cases that differ in scope, modeling approach, and participatory context. Also, the evaluation criteria provide a structured vocabulary based on clear mechanisms that extend beyond previous process-based and outcome-based evaluations. Effective models are those that take advantage of mechanisms that facilitate dialogue and resolution and improve the accessibility and applicability of technical knowledge. Furthermore, the framework can help build more complete records and systematic documentation of evidence to help standardize the field of PM.

Fracture mechanics methodology: Evaluation of structural components integrity

NASA Astrophysics Data System (ADS)

Sih, G. C.; de Oliveira Faria, L.

1984-09-01

The application of fracture mechanics to structural-design problems is discussed in lectures presented in the AGARD Fracture Mechanics Methodology course held in Lisbon, Portugal, in June 1981. The emphasis is on aeronautical design, and chapters are included on fatigue-life prediction for metals and composites, the fracture mechanics of engineering structural components, failure mechanics and damage evaluation of structural components, flaw-acceptance methods, and reliability in probabilistic design. Graphs, diagrams, drawings, and photographs are provided.

Earth orbit navigation study. Volume 2: System evaluation

NASA Technical Reports Server (NTRS)

1972-01-01

An overall systems evaluation was made of five candidate navigation systems in support of earth orbit missions. The five systems were horizon sensor system, unkown landmark tracking system, ground transponder system, manned space flight network, and tracking and data relay satellite system. Two reference missions were chosen: a low earth orbit mission and a transfer trajectory mission from low earth orbit to geosynchronous orbit. The specific areas addressed in the evaluation were performance, multifunction utilization, system mechanization, and cost.

Study of laser heated propulsion devices. Part 1: Evaluation of laser devices, fuels and energy coupling mechanisms

NASA Technical Reports Server (NTRS)

Hofer, O. C.

1982-01-01

Closed cycle, CW waveform and short wavelength laser devices are desirable characteristics for laser propulsion. The choice of specific wavelengths for hydrogen fuel affects the operational conditions under which a laser supported absorption (LSA) wave is initiated and maintained. The mechanisms of initiating and maintaining LSA waves depend on the wavelength of the laser. Consequently, the shape and size of the hot core plasma is also dependent on wavelength and pressure. Detailed modeling of these mechanisms must be performed before their actual significance can be ascertained. Inverse bremsstrahlung absorption mechanism is the dominant mechanism for coupling energy into the plasma, but other mechanisms which are wavelength dependent can dictate the LSA wave plasma initiation and maintenance conditions. Multiphoton mechanisms become important at visible or shorter wavelengths. These are important mechanisms in creating the initial H2 gas breakdown and supplying the precursor electrons required to sustain the plasma.

The Effects of Coping Interventions on Ability to Perform Under Pressure

PubMed Central

Kent, Sofie; Devonport, Tracey J.; Lane, Andrew M.; Nicholls, Wendy; Friesen, Andrew P.

2018-01-01

The ability to perform under pressure is necessary to achieve goals in various domains of life. We conducted a systematic review to synthesise findings from applied studies that focus on interventions developed to enhance an individual’s ability to cope under performance pressure. Following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, a comprehensive search of five electronic databases was conducted. This yielded 66,618 records, of which 23 peer review papers met inclusion criteria of containing an intervention that targeted coping skills for performing under pressure. Using the Standard Quality Assessment for evaluation of primary research papers (Kmet et al., 2004) to assess quality, included studies performed well on reporting research objectives, research design, and statistical procedures. Sixteen studies showed poor quality in controlling for potentially confounding factors and small sample sizes. A narrative aggregate synthesis identified intervention studies that provided an educational focus (n = 9), consultancy sessions (n = 6), simulation training (n = 5) and emotion regulation strategies (n = 3). Findings highlight a need to; 1) establish a contextualized pressure task which will generate high levels of ecological validity for participants. Having established a suitable pressure task, 2) research should assess the effects of pressure by evaluating conscious and nonconscious effects and associated coping mechanisms, which should inform the subsequent development of interventions, and 3) assess interventions to enhance understanding of the ways in which they improve coping with pressure, or may fail, and the mechanisms which may explain these outcomes. Key points Simulation studies that exposed individuals to ‘pressure’ settings produced the most consistent improvements to performance, in comparison to a control group. This systematic review highlights limitations with the design, execution, and evaluation of pressure interventions. Future research should attempt to better consider the approach used to generate meaningful performance pressures and assess the consequences of pressure by evaluating conscious and non-conscious effects and coping mechanisms through which coping with pressure might be improved. PMID:29535577

Assessment of left atrial mechanical functions and atrial electromechanical delay in Juvenile idiopathic arthritis by tissue Doppler echocardiography.

PubMed

El Eraky, Azza Z; Handoka, Nesrin M; Ghaly, Mona Sayed; Nasef, Samah Ismail; Eldahshan, Nahed A; Ibrahim, Ahmed M; Shalaby, Sherein

2016-11-24

Juvenile idiopathic arthritis (JIA) is a systemic chronic inflammatory disease. Studies using tissue Doppler imaging (TDI) for the evaluation of cardiac functions of children with JIA are limited. Thus, this study was conducted to evaluate Left ventricular function, left atrial mechanical functions and atrial electromechanical delay in JIA. This study was carried out as a across sectional study. A total of 34 patients with active JIA and 34 controls were included. Atrial electromechanical delay and left atrial (LA) mechanical functions in addition to systolic and diastolic left ventricular (LV) functions were measured by using conventional echocardiography and TDI. Assessment of disease activity was done using Juvenile arthritis disease activity score (JADAS-27). JIA patients had abnormal atrial electromechanical coupling as established from prolonged lateral mitral annulus (PA lateral), septal mitral annulus (PA septum), inter-atrial and intra-atrial electromechanical delays compared with healthy controls. Left ventricular filling abnormalities were found characterized by a reduced E/A ratio (1.07 ± 0.56 vs. 1.48 ± 0.16, p = 0.01). E/Em was significantly higher in patients with JIA (7.58 ± 1.79 vs. 4.74 ± 1.45, p = 0.003) denoting impaired diastolic function. Left atrial mechanical functions assessment showed significantly decreased LA passive emptying fraction, increased LA active emptying fraction and LA total emptying volume in JIA patients (p = 0.01, p = 0.01, p = 0.03 respectively). Atrial electromechanical coupling intervals, and LA mechanical functions were impaired which can be considered as an early form of subclinical cardiac involvement in JIA patients. Significant diastolic functional abnormalities exist in JIA.

Heterogeneous Production of Sulfate Aerosol over China.

NASA Astrophysics Data System (ADS)

Shao, J.; Alexander, B.; Chen, Q.; Zhang, L.; Wang, Y.; Xie, Z.; He, P.

2017-12-01

Sulfate is thought to be the main contributor to the growth of PM2.5 during the severe haze pollution over China, but most studies have shown that traditional gas- and aqueous-phase chemistry cannot explain the rapid sulfate production during haze events, suggesting a missing heterogeneous oxidation mechanism. In this work, we implement heterogeneous sulfate formation into a 3-D global chemical transport model (GEOS-Chem) to evaluate the different pathways for global and regional sulfate production, including SO2 oxidation by NO2, O3, H2O2, and TMI+O2. Heterogeneous sulfate production rates and the dominant heterogeneous sulfate formation mechanism depends on calculations of aerosol pH, which is in turn is dependent upon thermodynamic state assumptions. We evaluate the influence of aerosol pH and potential impacts of aerosol ionic strength on sulfate production rates and mechanisms in the model, and its implications for PM2.5 in Chinese haze events.

Understanding and Evaluating Human Thermal Comfort at Tertiary Level Using a Computer-Based Laboratory Teaching Tool

ERIC Educational Resources Information Center

Pellegrini, Marco

2014-01-01

Phase changes in water are experienced in everyday life but students often struggle to understand mechanisms that regulate them. Human thermal comfort is closely related to humidity, evaporative heat loss and heat transfer. The purpose of the present study is to assist students in the evaluation of human thermal comfort. Such a goal is achievable…

From detection monitoring to evaluation monitoring - a case study involving crown dieback in northern white-cedar

Treesearch

KaDonna Randolph; William Bechtold; Randall Morin; Stanley Zarnoch

2009-01-01

The Forest Inventory and Analysis (FIA) Phase 3 plot network is a crucial part of the U.S. Forest Health Monitoring program's detection monitoring system, where select indicators are monitored for signals that may indicate deteriorating forest health. When a negative signal is identified, evaluation monitoring provides a mechanism whereby a potential problem can...

Feeding Difficulties in Children with Esophageal Atresia.

PubMed

Mahoney, Lisa; Rosen, Rachel

2016-06-01

The current available literature evaluating feeding difficulties in children with esophageal atresia was reviewed. The published literature was searched through PubMed using a pre-defined search strategy. Feeding difficulties are commonly encountered in children and adults with repaired esophageal atresia [EA]. The mechanism for abnormal feeding includes both esophageal and oropharyngeal dysphagia. Esophageal dysphagia is commonly reported in patients with EA and causes include dysmotility, anatomic lesions, esophageal outlet obstruction and esophageal inflammation. Endoscopic evaluation, esophageal manometry and esophograms can be useful studies to evaluate for causes of esophageal dysphagia. Oropharyngeal dysfunction and aspiration are also important mechanisms for feeding difficulties in patients with EA. These patients often present with respiratory symptoms. Videofluoroscopic swallow study, salivagram, fiberoptic endoscopic evaluation of swallowing and high-resolution manometry can all be helpful tools to identify aspiration. Once diagnosed, management goals include reduction of aspiration during swallowing, reducing full column reflux into the oropharynx and continuation of oral feeding to maintain skills. We review specific strategies which can be used to reduce aspiration of gastric contents, including thickening feeds, changing feeding schedule, switching formula, trialing transpyloric feeds and fundoplication. Copyright © 2015 Elsevier Ltd. All rights reserved.

GENE EXPRESSION ANALYSIS IN THE VENTRAL PROSTATE OF RATS EXPOSED TO VINCLOZOLIN OR PROCYMIDONE

EPA Science Inventory

Vinclozolin and procymidone are antiandrogens that are thought to share a common androgen receptor (AR) mediated mechanism of action. This assessment is based primarily on morphological, AR binding, and in vitro transcriptional activation studies. Studies designed to evaluate t...

REMOVAL OF HIGH-LEVEL ARSENIC BY ZERO-VALENT IRON

EPA Science Inventory

The objectives of this study were to conduct batch and column studies to (i) assess the effectiveness of zero-valent iron for arsenic remediation in groundwater, (ii) determine removal mechanisms of arsenic, and (iii) evaluate implications of these processes with regard to the st...

Identifying potential working mechanisms behind the positive effects of exercise therapy on pain and function in osteoarthritis; a systematic review.

PubMed

Runhaar, J; Luijsterburg, P; Dekker, J; Bierma-Zeinstra, S M A

2015-07-01

Although physical exercise is the commonly recommended for osteoarthritis (OA) patients, the working mechanism behind the positive effects of physical exercise on pain and function is a black box phenomenon. In the present study we aimed to identify possible mediators in the relation between physical exercise and improvements of pain and function in OA patients. A systematic search for all studies evaluating the effects of physical exercise in OA patients and select those that additionally reported the change in any physiological factor from pre-to post-exercise. In total, 94 studies evaluating 112 intervention groups were included. Most included studies evaluated subjects with solely knee OA (96 out of 112 groups). Based on the measured physiological factors within the included studies, 12 categories of possible mediators were formed. Muscle strength and ROM/flexibility were the most measured categories of possible mediators with 61 and 21 intervention groups measuring one or more physiological factors within these categories, respectively. 60% (31 out of 52) of the studies showed a significant increase in knee extensor muscle strength and 71% (22 out of 31) in knee flexor muscle strength over the intervention period. All 5 studies evaluating extension impairments and 10 out of 12 studies (83%) measuring proprioception found a significant change from pre-to post-intervention. An increase of upper leg strength, a decrease of extension impairments and improvement in proprioception were identified as possible mediators in the positive association between physical exercise and OA symptoms. Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Methodologies in determining mechanical properties of thin films using nanoindentation

NASA Astrophysics Data System (ADS)

Han, Seung Min Jane

Thin films are critical components of microelectronic and MEMS devices, and evaluating their mechanical properties is of current interest. As the dimensions of the devices become smaller and smaller, however, understanding the mechanical properties of materials at sub-micron length scales becomes more challenging. The conventional methods for evaluating strengths of materials in bulk form cannot be applied, and new methodologies are required for accurately evaluating mechanical properties of thin films. In this work, development of methodologies using the nanoindenter was pursued in three parts: (1) creation of a new method for extracting thin film hardness, (2) use of combinatorial methods for determining compositions with desired mechanical properties, and (3) use of microcompression testing of sub-micron sized pillars to understand plasticity in Al-Sc multilayers. The existing nanoindentation hardness model by Oliver & Pharr is unable to accurately determine the hardness of thin films on substrates with an elastic mismatch. Thus, a new method of analysis for extracting thin film hardness from film/substrate systems, that eliminates the effect of elastic mismatch of the underlying substrate, surface roughness, and also pile-up/sink-in, is needed. Such a method was developed in the first part of this study. The feasibility of using the nanoindentation hardness together with combinatorial methods to efficiently scan through mechanical properties of Ti-Al metallic alloys was examined in the second part of this study. The combinatorial approach provides an efficient method that can be used to determine alloy compositions that might merit further exploration and development as bulk materials. Finally, the mechanical properties of Al-Al3Sc multilayers with bilayer periods ranging from 6-100 nm were examined using microcompression. The sub-micron sized pillars were prepared using the focused ion beam (FIB) and compression tested with the flat tip of the nanoindenter. The measured yield strengths show the trend of increasing strength with decreasing bilayer period, and agree with the nanoindentation hardness results using the suitable Tabor correction factor. Strain softening was observed at large strains, and a new model for the true stress and true strain was developed to account for the inhomogeneous deformation geometry.

Influence of heat treatment on structural, mechanical and wear properties of crosslinked UHMWPE.

PubMed

Chiesa, R; Moscatelli, M; Giordano, C; Siccardi, F; Cigada, A

2004-01-01

New crosslinked ultra high molecular weight polyethylenes (UHMWPEs) have recently been developed, characterized and introduced in clinical applications. UHMWPE cross-linking treatments are very promising for reducing osteolysis induced by wear debris. The irradiation type, gamma or beta, the dosage and the thermal treatment performed during or following the irradiation process are all factors affecting polyethylene wear resistance. Thermal stabilization treatments performed after or during the irradiation process at a temperature above melting point (i.e. >130 degrees C) have been proven to effectively remove the free radicals generated during irradiation from UHMWPE, but their effect on the mechanical properties of UHMWPE are not completely clear. In addition to wear rate reduction, maintaining good mechanical properties is fundamental aspect in designing the new generation of crosslinked UHMWPE for artificial load bearing materials, especially considering the application in total knee replacements. In this study, we investigated the influence of different stabilization treatments, performed after gamma irradiation, on structural, wear and mechanical properties of UHMWPE. We performed four different stabilization treatments, with different temperatures and cooling rates, on 100 kGy gamma irradiated UHMWPE. Structural properties of UHMWPE were assessed by differential scanning calorimetry (DSC). To assess the mechanical performance of the materials, uni-axial tensile tests were performed according to the ASTM D638 standard, bi-axial tension performance was evaluated by small punch tests (ASTM F2183-02), toughness resistance was evaluated by the Izod method (ASTM F648), and cold flow resistance was analysed by a dynamic compressive test. Evaluation of wear resistance was by a multidirectional pin-on-disk screening machine. Materials considered were in "aged" and "non-aged" conditions. Results confirmed that cross-linking greatly enhances UHMWPE wear resistance, but introduces some detrimental effects on the mechanical properties. In this study, we found that the negative ef-fects on the mechanical properties of crosslinked UHMWPE can be modulated, to some extent, by choosing a thermal stabiliza-tion treatment at a correct temperature and cooling rate. (Journal of Applied Biomaterials & Biomechanics 2004; 2: 20-8).

Anisotropic mechanical behaviors and their structural dependences of crossed-lamellar structure in a bivalve shell.

PubMed

Jiao, D; Liu, Z Q; Qu, R T; Zhang, Z F

2016-02-01

Crossed-lamellar structure is one of the most common organizations found in mollusk shells and may serve as a natural mimetic model for designing bio-inspired synthetic materials. Nonetheless, the mechanical behaviors and corresponding mechanisms have rarely been investigated for individual macro-layer of such structure. The integrated effects of orientation and hydration also remain unclear. In this study, the mechanical behaviors and their structural dependences of pure crossed-lamellar structure in Saxidomus purpuratus shell were systematically examined by three-point bending and compression tests. Mechanical properties and fracture mechanisms were revealed to depend strongly on the orientation, hydration state and loading condition. Three basic cracking modes of inter-platelet, trans-platelet, and along the interfaces between first-order lamellae were identified, and the interfacial separation was enhanced by hydration. Macroscopic compressive fracture was accomplished through axial splitting during which multiple toughening mechanisms were activated. The competition among different cracking modes was quantitatively evaluated by analyzing their driving stresses and resistances from fundamental mechanics. This study helps to clarify the mechanical behaviors of naturally occurring crossed-lamellar structure, and accordingly, aids in designing new bio-inspired synthetic materials by mimicking it. Copyright © 2015 Elsevier B.V. All rights reserved.

An alternative continence tube for continent urinary reservoirs: evaluation of surgical technique, pressure and continence study in an ex-vivo model.

PubMed

Honeck, Patrick; Michel, Maurice Stephan; Trojan, Lutz; Alken, Peter

2009-02-01

Despite the large number of surgical techniques for continent cutaneous diversion described in literature, the creation of a reliable, continent and easily catheterizable continence mechanism remains a complex surgical procedure. Aim of this study was the evaluation of a new method for a catheterizable continence mechanism using stapled pig intestine. Small and large pig intestines were used for construction. A 3 or 6 cm double row stapling system was used. Three variations using small and large intestine segments were constructed. A 3 or 6 cm long stapler line was placed alongside a 12 Fr catheter positioned at the antimesenterial side creating a partially two-luminal segment. Construction time for the tube was measured. The created tube was then embedded into the pouch. Pressure evaluation of the continence mechanism was performed for each variation. Intermittent external manual compression was used to simulate sudden pressure exposure. All variations were 100% continent under filling volumes of up to 700 ml and pressure levels of 58 +/- 6 cm H(2)O for large intestine and 266 ml and 87 +/- 18 cm H(2)O for small intestine, respectively. With further filling above the mentioned capacity suture insufficiency occurred but no tube insufficiency. Construction time for all variations was less than 12 min. The described technique is an easy and fast method to construct a continence mechanism using small or large intestine. Our ex vivo experiments have shown sufficient continence situation in an ex-vivo model. Further investigations in an in-vivo model are needed to confirm these results.

Studies of Membrane Associated Energy Transduction Mechanisms in Pathological States: Chemical and Biochemical Studies of PGB sub x.

DTIC Science & Technology

1981-08-30

count and aastric acid secretion are evaluated. As shown in Table I the bleedinq score in the groups given P(M in doses of 1 to 5 mxAg were...gastric acid output of the 1 mg/g PGBx group was -21 - -= :’r 0.236 + 0.173 meq/three hours and the control group was 0.189 + 0.139 per three hours. The t...AD-AlSO 289 HMNNEMANN MEDICAL COLL AND HOSPITAL PHILADELPHIA PA -ETC F/6 6/ 1 STUDIES OF MERANE ASSOCIATED ENERGY TRANSDUCTION MECHANISMS I-ETCfU) AUG

A novel dental implant abutment with micro-motion capability--development and biomechanical evaluations.

PubMed

Chen, Yen-Yin; Chen, Weng-Pin; Chang, Hao-Hueng; Huang, Shih-Hao; Lin, Chun-Pin

2014-02-01

The aim of this study was to develop a novel dental implant abutment with a micro-motion mechanism that imitates the biomechanical behavior of the periodontal ligament, with the goal of increasing the long-term survival rate of dental implants. Computer-aided design software was used to design a novel dental implant abutment with an internal resilient component with a micro-motion capability. The feasibility of the novel system was investigated via finite element analysis. Then, a prototype of the novel dental implant abutment was fabricated, and the mechanical behavior was evaluated. The results of the mechanical tests and finite element analysis confirmed that the novel dental implant abutment possessed the anticipated micro-motion capability. Furthermore, the nonlinear force-displacement behavior apparent in this micro-motion mechanism imitated the movement of a human tooth. The slope of the force-displacement curve of the novel abutment was approximately 38.5 N/mm before the 0.02-mm displacement and approximately 430 N/mm after the 0.03-mm displacement. The novel dental implant abutment with a micro-motion mechanism actually imitated the biomechanical behavior of a natural tooth and provided resilient function, sealing, a non-separation mechanism, and ease-of-use. Copyright © 2013 Academy of Dental Materials. All rights reserved.

Electron Transfer Mechanism in Gold Surface Modified with Self-Assembly Monolayers from First Principles

NASA Astrophysics Data System (ADS)

Lima, Filipe C. D. A.; Iost, Rodrigo M.; Crespilho, Frank N.; Caldas, Marília J.; Calzolari, Arrigo; Petrilli, Helena M.

2013-03-01

We report the investigation of electron tunneling mechanism of peptide ferrocenyl-glycylcystamine self-assembled monolayers (SAMs) onto Au (111) electrode surfaces. Recent experimental investigations showed that electron transfer in peptides can occur across long distances by separating the donor from the acceptor. This mechanism can be further fostered by the presence of electron donor terminations of Fc terminal units on SAMs but the charge transfer mechanism is still not clear. We study the interaction of the peptide ferrocenyl-glycylcystamine on the Au (111) from first principles calculations to evaluate the electron transfer mechanism. For this purpose, we used the Kohn Sham (KS) scheme for the Density Functional Theory (DFT) as implemented in the Quantum-ESPRESSO suit of codes, using Vandebilt ultrasoft pseudopotentials and GGA-PBE exchange correlation functional to evaluate the ground-state atomic and electronic structure of the system. The analysis of KS orbital at the Fermi Energy showed high electronic density localized in Fc molecules and the observation of a minor contribution from the solvent and counter ion. Based on the results, we infer evidences of electron tunneling mechanism from the molecule to the Au(111). We acknowledge FAPESP for grant support. Also, LCCA/USP, RICE and CENAPAD for computational resources.

Effect of fiber distribution and realignment on the nonlinear and inhomogeneous mechanical properties of human supraspinatus tendon under longitudinal tensile loading.

PubMed

Lake, Spencer P; Miller, Kristin S; Elliott, Dawn M; Soslowsky, Louis J

2009-12-01

Tendon exhibits nonlinear stress-strain behavior that may be partly due to movement of collagen fibers through the extracellular matrix. While a few techniques have been developed to evaluate the fiber architecture of other soft tissues, the organizational behavior of tendon under load has not been determined. The supraspinatus tendon (SST) of the rotator cuff is of particular interest for investigation due to its complex mechanical environment and corresponding inhomogeneity. In addition, SST injury occurs frequently with limited success in treatment strategies, illustrating the need for a better understanding of SST properties. Therefore, the objective of this study was to quantitatively evaluate the inhomogeneous tensile mechanical properties, fiber organization, and fiber realignment under load of human SST utilizing a novel polarized light technique. Fiber distributions were found to become more aligned under load, particularly during the low stiffness toe-region, suggesting that fiber realignment may be partly responsible for observed nonlinear behavior. Fiber alignment was found to correlate significantly with mechanical parameters, providing evidence for strong structure-function relationships in tendon. Human SST exhibits complex, inhomogeneous mechanical properties and fiber distributions, perhaps due to its complex loading environment. Surprisingly, histological grade of degeneration did not correlate with mechanical properties.

IARC use of oxidative stress as key mode of action characteristic for facilitating cancer classification: Glyphosate case example illustrating a lack of robustness in interpretative implementation.

PubMed

Bus, James S

2017-06-01

The International Agency for Research on Cancer (IARC) has formulated 10 key characteristics of human carcinogens to incorporate mechanistic data into cancer hazard classifications. The analysis used glyphosate as a case example to examine the robustness of IARC's determination of oxidative stress as "strong" evidence supporting a plausible cancer mechanism in humans. The IARC analysis primarily relied on 14 human/mammalian studies; 19 non-mammalian studies were uninformative of human cancer given the broad spectrum of test species and extensive use of formulations and aquatic testing. The mammalian studies had substantial experimental limitations for informing cancer mechanism including use of: single doses and time points; cytotoxic/toxic test doses; tissues not identified as potential cancer targets; glyphosate formulations or mixtures; technically limited oxidative stress biomarkers. The doses were many orders of magnitude higher than human exposures determined in human biomonitoring studies. The glyphosate case example reveals that the IARC evaluation fell substantially short of "strong" supporting evidence of oxidative stress as a plausible human cancer mechanism, and suggests that other IARC monographs relying on the 10 key characteristics approach should be similarly examined for a lack of robust data integration fundamental to reasonable mode of action evaluations. Copyright © 2017 Elsevier Inc. All rights reserved.

Experimental evaluation and design of unfilled and concrete-filled FRP composite piles, task 1 - mechanical properties of FRP piles.

DOT National Transportation Integrated Search

2014-10-01

The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP : composite piles for load-bearing in bridges. This report covers Task 1, Mechanical Properties of FRP Piles. : Mechanical and geotechnic...

Acoustic emission from composite materials. [nondestructive tests

NASA Technical Reports Server (NTRS)

Visconti, I. C.; Teti, R.

1979-01-01

The two basic areas where the acoustic emission (AE) technique can be applied are materials research and the evaluation of structural reliability. This experimental method leads to a better understanding of fracture mechanisms and is an NDT technique particularly well suited for the study of propagating cracks. Experiments are described in which acoustic emissions were unambiguously correlated with microstructural fracture mechanisms. The advantages and limitations of the AE technique are noted.

Stressed Stability Techniques for Adjuvant Formulations.

PubMed

Hasija, Manvi; Sheung, Anthony; Rahman, Nausheen; Ausar, Salvador F

2017-01-01

Stressed stability testing is crucial to the understanding of mechanisms of degradation and the effects of external stress factors on adjuvant stability. These studies vastly help the development of stability indicating tests and the selection of stabilizing conditions for long term storage. In this chapter, we provide detailed protocols for the execution of forced degradation experiments that evaluate the robustness of adjuvant formulations against thermal, mechanical, freeze-thawing, and photo stresses.

Evaluation of the sorption mechanism of ionic liquids onto multi-walled carbon nanotubes.

PubMed

Wojsławski, Jerzy; Białk-Bielińska, Anna; Paszkiewicz, Monika; Toński, Michał; Stepnowski, Piotr; Dołżonek, Joanna

2018-01-01

The knowledge of the sorption mechanism of different chemicals onto third generation carbon sorbents such as carbon nanotubes (CNTs) is needed in order to project systems for the effective removal of pollutants from the environment. This paper reports evaluation of the sorption mechanism of selected ionic liquids (ILs), being considered as potential pollutant in environment, onto various CNTs. CNTs characterized by the smallest diameter and the biggest surface area showed the highest sorption capacity to isolate ILs from an aqueous solution. CNTs with a bigger diameter, a functionalized surface and particularly a helical shape showed a lower sorption capacity. The sorption mechanism has been defined as complex, including van der Waals, π-π and electrostatic interactions with dominating π-π interactions. Due to the relatively high sorption coefficient (355.98 ± 20.69-6397.10 ± 355.42 L kg -1 depending on the IL) the study showed that multi-walled carbon nanotubes can potentially be used to effectively isolate ILs from an aqueous solution. Moreover, proved in this study, the fast sorption kinetic, and uncomplicated regeneration process, leading to an even higher sorption capacity, means that CNTs are promising material which could find potential applications in the treatment of water contaminated by ILs. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comprehensive review of plants and their active constituents with wound healing activity in traditional Iranian medicine.

PubMed

Hosein Farzaei, Mohammad; Abbasabadi, Zahra; Reza Shams-Ardekani, Mohammad; Abdollahi, Mohammad; Rahimi, Roja

2014-07-01

Wound healing is a complex cascade of events with various cellular and biochemical processes that result in reconstruction and regeneration of damaged tissue. The objective of the current study was to scientifically evaluate the medicinal plants said to produce wound healing activity in traditional Iranian medicine (TIM). Electronic databases were searched for the names of medicinal plants claimed in TIM literature for having wound healing activity. Articles were evaluated to obtain any in vitro, animal, or clinical evidence of their efficacy and possible mechanisms involved in would healing. Mechanisms of action for some of these plants, including Tamarix spp., Rosa spp., Piper betle, Plantago major, Oxalis spp., Olea europaea, Malva spp., Linum usitatissimum, and Tamarindus indica, have not been yet clarified. In contrast, some herbs such as Vitis vinifera, Quercus spp., Punica granatum, Pinus spp., Polygonum spp., Lilium spp., Gentiana lutea, Arnebia euchroma, Aloe spp., and Caesalpinia spp. have various biological and pharmacological mechanisms that have been verified for wound healing activity. Overall, TIM resources have introduced various medicinal plants for wounds with confirmed effectiveness according to current pharmacological studies. These herbal remedies could be considered as future drugs for healing of wounds. Further pharmacological and clinical investigations are recommended for exploring safety, exact mechanisms, and efficacy of these herbal remedies. .

Multimodality cellular and molecular imaging of concomitant tumour enhancement in a syngeneic mouse model of breast cancer metastasis.

PubMed

Parkins, Katie M; Dubois, Veronica P; Hamilton, Amanda M; Makela, Ashley V; Ronald, John A; Foster, Paula J

2018-06-12

The mechanisms that influence metastatic growth rates are poorly understood. One mechanism of interest known as concomitant tumour resistance (CTR) can be defined as the inhibition of metastasis by existing tumour mass. Conversely, the presence of a primary tumour has also been shown to increase metastatic outgrowth, termed concomitant tumour enhancement (CTE). The majority of studies evaluating CTR/CTE in preclinical models have relied on endpoint histological evaluation of tumour burden. The goal of this research was to use conventional magnetic resonance imaging (MRI), cellular MRI, and bioluminescence imaging to study the impact of a primary tumour on the development of brain metastases in a syngeneic mouse model. Here, we report that the presence of a 4T1 primary tumour significantly enhances total brain tumour burden in Balb/C mice. Using in vivo BLI/MRI we could determine this was not related to differences in initial arrest or clearance of viable cells in the brain, which suggests that the presence of a primary tumour can increase the proliferative growth of brain metastases in this model. The continued application of our longitudinal cellular and molecular imaging tools will yield a better understanding of the mechanism(s) by which this physiological inhibition (CTR) and/or enhancement (CTE) occurs.

Evaluating the influence of motor control on selective attention through a stochastic model: the paradigm of motor control dysfunction in cerebellar patient.

PubMed

Veneri, Giacomo; Federico, Antonio; Rufa, Alessandra

2014-01-01

Attention allows us to selectively process the vast amount of information with which we are confronted, prioritizing some aspects of information and ignoring others by focusing on a certain location or aspect of the visual scene. Selective attention is guided by two cognitive mechanisms: saliency of the image (bottom up) and endogenous mechanisms (top down). These two mechanisms interact to direct attention and plan eye movements; then, the movement profile is sent to the motor system, which must constantly update the command needed to produce the desired eye movement. A new approach is described here to study how the eye motor control could influence this selection mechanism in clinical behavior: two groups of patients (SCA2 and late onset cerebellar ataxia LOCA) with well-known problems of motor control were studied; patients performed a cognitively demanding task; the results were compared to a stochastic model based on Monte Carlo simulations and a group of healthy subjects. The analytical procedure evaluated some energy functions for understanding the process. The implemented model suggested that patients performed an optimal visual search, reducing intrinsic noise sources. Our findings theorize a strict correlation between the "optimal motor system" and the "optimal stimulus encoders."

Influence of internal composition on physicochemical properties of alginate aqueous-core capsules.

PubMed

Ben Messaoud, Ghazi; Sánchez-González, Laura; Probst, Laurent; Desobry, Stéphane

2016-05-01

To enhance physicochemical properties of alginate aqueous-core capsules, conventional strategies were focused in literature on designing composite and coated capsules. In the present study, own effect of liquid-core composition on mechanical and release properties was investigated. Capsules were prepared by dripping a CaCl2 solution into an alginate gelling solution. Viscosity of CaCl2 solution was adjusted by adding cationic, anionic and non-ionic naturally derived polymers, respectively chitosan, xanthan gum and guar gum. In parallel, uniform alginate hydrogels were prepared by different methods (pouring, in situ forming and mixing). Mechanical stability of capsules and plane hydrogels were respectively evaluated by compression experiments and small amplitude oscillatory shear rheology and then correlated. Capsules permeability was evaluated by monitoring diffusion of encapsulated cochineal dye, riboflavin and BSA. The core-shell interactions were investigated by ATR-FTIR. Results showed that inner polymer had an impact on membrane stability and could act as an internal coating or provide mechanical reinforcement. Mechanical properties of alginate capsules were in a good agreement with rheological behavior of plane hydrogels. Release behavior of the entrapped molecules changed considerably. This study demonstrated the importance of aqueous-core composition, and gave new insights for possible adjusting of microcapsules physicochemical properties by modulating core-shell interactions. Copyright © 2016 Elsevier Inc. All rights reserved.

The imperative for controlled mechanical stresses in unraveling cellular mechanisms of mechanotransduction

PubMed Central

Anderson, Eric J; Falls, Thomas D; Sorkin, Adam M; Tate, Melissa L Knothe

2006-01-01

Background In vitro mechanotransduction studies are designed to elucidate cell behavior in response to a well-defined mechanical signal that is imparted to cultured cells, e.g. through fluid flow. Typically, flow rates are calculated based on a parallel plate flow assumption, to achieve a targeted cellular shear stress. This study evaluates the performance of specific flow/perfusion chambers in imparting the targeted stress at the cellular level. Methods To evaluate how well actual flow chambers meet their target stresses (set for 1 and 10 dyn/cm2 for this study) at a cellular level, computational models were developed to calculate flow velocity components and imparted shear stresses for a given pressure gradient. Computational predictions were validated with micro-particle image velocimetry (μPIV) experiments. Results Based on these computational and experimental studies, as few as 66% of cells seeded along the midplane of commonly implemented flow/perfusion chambers are subjected to stresses within ±10% of the target stress. In addition, flow velocities and shear stresses imparted through fluid drag vary as a function of location within each chamber. Hence, not only a limited number of cells are exposed to target stress levels within each chamber, but also neighboring cells may experience different flow regimes. Finally, flow regimes are highly dependent on flow chamber geometry, resulting in significant variation in magnitudes and spatial distributions of stress between chambers. Conclusion The results of this study challenge the basic premise of in vitro mechanotransduction studies, i.e. that a controlled flow regime is applied to impart a defined mechanical stimulus to cells. These results also underscore the fact that data from studies in which different chambers are utilized can not be compared, even if the target stress regimes are comparable. PMID:16672051

Micromechanical Characterization and Texture Analysis of Direct Cast Titanium Alloys Strips

NASA Technical Reports Server (NTRS)

2000-01-01

This research was conducted to determine a post-processing technique to optimize mechanical and material properties of a number of Titanium based alloys and aluminides processed via Melt Overflow Solidification Technique (MORST). This technique was developed by NASA for the development of thin sheet titanium and titanium aluminides used in high temperature applications. The materials investigated in this study included conventional titanium alloy strips and foils, Ti-1100, Ti-24Al-11Nb (Alpha-2), and Ti-48Al-2Ta (Gamma). The methodology used included micro-characterization, heat-treatment, mechanical processing and mechanical testing. Characterization techniques included optical, electron microscopy, and x-ray texture analysis. The processing included heat-treatment and mechanical deformation through cold rolling. The initial as-cast materials were evaluated for their microstructure and mechanical properties. Different heat-treatment and rolling steps were chosen to process these materials. The properties were evaluated further and a processing relationship was established in order to obtain an optimum processing condition. The results showed that the as-cast material exhibited a Widmanstatten (fine grain) microstructure that developed into a microstructure with larger grains through processing steps. The texture intensity showed little change for all processing performed in this investigation.

Maytenus erythroxylon Reissek (Celastraceae) ethanol extract presents antidiarrheal activity via antimotility and antisecretory mechanisms.

PubMed

Formiga, Rodrigo de Oliveira; Quirino, Zelma Glebya Maciel; Diniz, Margareth de Fátima Formiga Melo; Marinho, Alexsandro Fernandes; Tavares, Josean Fechine; Batista, Leônia Maria

2017-06-28

To investigate the acute toxicity, phytochemical profile, antidiarrheal activity and mechanisms of action of Maytenus erythroxylon ( M. erythroxylon ) ethanol extract. A castor oil-induced diarrhea model was used to evaluate antidiarrheal activity. Intestinal transit and gastric emptying protocols were used to evaluate a possible antimotility effect. K ATP channels, nitric oxide, presynaptic α2-adrenergic and tissue adrenergic receptors were investigated to uncover antimotility mechanisms of action and castor oil-induced enteropooling to elucidate antisecretory mechanisms. All tested doses of the extract (62.5, 125, 250 and 500 mg/kg) possessed antidiarrheal activity, with a significant decrease of the evacuation index. This activity is possibly related to a reduced gastric emptying (125, 250 and 500 mg/kg) and to a decreased percentage of intestinal transit for all tested doses. That last effect seems to be modulated by nitric oxide, K ATP channels and tissue adrenergic receptors. Besides, the extract also presented antisecretory effect due to a decrease of intestinal fluid accumulation. The antidiarrheal effect of M. erythroxylon found in this study involves antimotility and antisecretory mechanisms that may be attributed to the chemical compounds found in this species: saponins, flavonoids, tannins, triterpenes and steroids.

The Influence of Mo, Cr and B Alloying on Phase Transformation and Mechanical Properties in Nb Added High Strength Dual Phase Steels

NASA Astrophysics Data System (ADS)

Girina, O.; Fonstein, N.; Yakubovsky, O.; Panahi, D.; Bhattacharya, D.; Jansto, S.

The influence of Nb, Mo, Cr and B on phase transformations and mechanical properties are studied in a 0.15C-2.0Mn-0.3Si-0.020Ti dual phase steel separately and in combination. The formation and decomposition of austenite together with recrystallization of ferrite are evaluated by dilatometry and constructed CCT-diagrams in laboratory processed cold rolled material cooled after full austenitization and from intercritical temperature range. The effect of alloying elements on formation of austenite through their effect on initial hot rolled structure is taken into account. The interpretation of phase transformations during heating and cooling is supported by metallography. The effect of alloying elements on mechanical properties and structure are evaluated by annealing simulations. It has been shown that mechanical properties are strongly influenced by alloying additions such as Nb, Mo, Cr and B through their effect on ferrite formation during continuous cooling and corresponding enrichment of remaining austenite by carbon. Depending on combined effect of these alloying elements, different phase transformations can be promoted during cooling. This allows controlling of final microstructural constituents and mechanical properties.

Cation solvation with quantum chemical effects modeled by a size-consistent multi-partitioning quantum mechanics/molecular mechanics method.

PubMed

Watanabe, Hiroshi C; Kubillus, Maximilian; Kubař, Tomáš; Stach, Robert; Mizaikoff, Boris; Ishikita, Hiroshi

2017-07-21

In the condensed phase, quantum chemical properties such as many-body effects and intermolecular charge fluctuations are critical determinants of the solvation structure and dynamics. Thus, a quantum mechanical (QM) molecular description is required for both solute and solvent to incorporate these properties. However, it is challenging to conduct molecular dynamics (MD) simulations for condensed systems of sufficient scale when adapting QM potentials. To overcome this problem, we recently developed the size-consistent multi-partitioning (SCMP) quantum mechanics/molecular mechanics (QM/MM) method and realized stable and accurate MD simulations, using the QM potential to a benchmark system. In the present study, as the first application of the SCMP method, we have investigated the structures and dynamics of Na + , K + , and Ca 2+ solutions based on nanosecond-scale sampling, a sampling 100-times longer than that of conventional QM-based samplings. Furthermore, we have evaluated two dynamic properties, the diffusion coefficient and difference spectra, with high statistical certainty. Furthermore the calculation of these properties has not previously been possible within the conventional QM/MM framework. Based on our analysis, we have quantitatively evaluated the quantum chemical solvation effects, which show distinct differences between the cations.

Maytenus erythroxylon Reissek (Celastraceae) ethanol extract presents antidiarrheal activity via antimotility and antisecretory mechanisms

PubMed Central

Formiga, Rodrigo de Oliveira; Quirino, Zelma Glebya Maciel; Diniz, Margareth de Fátima Formiga Melo; Marinho, Alexsandro Fernandes; Tavares, Josean Fechine; Batista, Leônia Maria

2017-01-01

AIM To investigate the acute toxicity, phytochemical profile, antidiarrheal activity and mechanisms of action of Maytenus erythroxylon (M. erythroxylon) ethanol extract. METHODS A castor oil-induced diarrhea model was used to evaluate antidiarrheal activity. Intestinal transit and gastric emptying protocols were used to evaluate a possible antimotility effect. KATP channels, nitric oxide, presynaptic α2-adrenergic and tissue adrenergic receptors were investigated to uncover antimotility mechanisms of action and castor oil-induced enteropooling to elucidate antisecretory mechanisms. RESULTS All tested doses of the extract (62.5, 125, 250 and 500 mg/kg) possessed antidiarrheal activity, with a significant decrease of the evacuation index. This activity is possibly related to a reduced gastric emptying (125, 250 and 500 mg/kg) and to a decreased percentage of intestinal transit for all tested doses. That last effect seems to be modulated by nitric oxide, KATP channels and tissue adrenergic receptors. Besides, the extract also presented antisecretory effect due to a decrease of intestinal fluid accumulation. CONCLUSION The antidiarrheal effect of M. erythroxylon found in this study involves antimotility and antisecretory mechanisms that may be attributed to the chemical compounds found in this species: saponins, flavonoids, tannins, triterpenes and steroids. PMID:28706420

Energetic Assessment of the Nonexercise Activities under Free-Living Conditions.

PubMed

Sun, Shijie; Tang, Qiang; Quan, Haiying; Lu, Qi; Sun, Ming; Zhang, Kuan

2016-01-01

Nonexercise activities (NAs) are common types of physical activity in daily life and critical component in energy expenditure. However, energetic assessment of NA, particularly in free-living subjects, is a technical challenge. In this study, mechanical modeling and portable device were used to evaluate five common types of NA in daily life: sit to stand, lie to sit, bowing while standing, squat, and right leg over left. A human indirect calorimeter was used to measure the activity energy expenditure of NA. Mechanical work and mechanical efficiency of NA were calculated for mechanical modeling. Thirty-two male subjects were recruited for the study (20 subjects for the development of models and 12 subjects for evaluation of models). The average (mean ± SD) mechanical work of 5 NAs was 2.31 ± 0.50, 2.88 ± 0.57, 1.75 ± 0.55, 3.96 ± 1.25, and 1.25 ± 0.51 J/kg·m, respectively. The mean mechanical efficiencies of those activities were 22.0 ± 3.3%, 26.5 ± 5.1%, 19.8 ± 3.7%, 24.0 ± 5.5%, and 26.3 ± 5.5%. The activity energy expenditure estimated by the models was not significantly different from the measurements by the calorimeter (p > 0.05) with accuracies of 102.2 ± 20.7%, 103.7 ± 25.8%, 105.6 ± 14.6%, 101.1 ± 28.0%, and 95.8 ± 20.7%, respectively, for those activities. These findings suggest that the mechanical models combined with a portable device can provide an alternative method for the energetic analysis of nonexercise activities under free-living condition.

Development and Processing Improvement of Aerospace Aluminum Alloys

NASA Technical Reports Server (NTRS)

Lisagor, W. Barry; Bales, Thomas T.

2007-01-01

This final report, in multiple presentation format, describes a comprehensive multi-tasked contract study to improve the overall property response of selected aerospace alloys, explore further a newly-developed and registered alloy, and correlate the processing, metallurgical structure, and subsequent properties achieved with particular emphasis on the crystallographic orientation texture developed. Modifications to plate processing, specifically hot rolling practices, were evaluated for Al-Li alloys 2195 and 2297, for the recently registered Al-Cu-Ag alloy, 2139, and for the Al-Zn-Mg-Cu alloy, 7050. For all of the alloys evaluated, the processing modifications resulted in significant improvements in mechanical properties. Analyses also resulted in an enhanced understanding of the correlation of processing, crystallographic texture, and mechanical properties.

Application of the GRC Stirling Convertor System Dynamic Model

NASA Technical Reports Server (NTRS)

Regan, Timothy F.; Lewandowski, Edward J.; Schreiber, Jeffrey G. (Technical Monitor)

2004-01-01

The GRC Stirling Convertor System Dynamic Model (SDM) has been developed to simulate dynamic performance of power systems incorporating free-piston Stirling convertors. This paper discusses its use in evaluating system dynamics and other systems concerns. Detailed examples are provided showing the use of the model in evaluation of off-nominal operating conditions. The many degrees of freedom in both the mechanical and electrical domains inherent in the Stirling convertor and the nonlinear dynamics make simulation an attractive analysis tool in conjunction with classical analysis. Application of SDM in studying the relationship of the size of the resonant circuit quality factor (commonly referred to as Q) in the various resonant mechanical and electrical sub-systems is discussed.

Effect of food azo dye tartrazine on learning and memory functions in mice and rats, and the possible mechanisms involved.

PubMed

Gao, Yonglin; Li, Chunmei; Shen, Jingyu; Yin, Huaxian; An, Xiulin; Jin, Haizhu

2011-08-01

Tartrazine is an artificial azo dye commonly used in human food and pharmaceutical products. The present study was conducted to evaluate the toxic effect of tartrazine on the learning and memory functions in mice and rats. Animals were administered different doses of tartrazine for a period of 30 d and were evaluated by open-field test, step-through test, and Morris water maze test, respectively. Furthermore, the biomarkers of the oxidative stress and pathohistology were also measured to explore the possible mechanisms involved. The results indicated that tartrazine extract significantly enhanced active behavioral response to the open field, increased the escape latency in Morris water maze test and decreased the retention latency in step-through tests. The decline in the activities of catalase, glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) as well as a rise in the level of malonaldehyde (MDA) were observed in the brain of tartrazine-treated rats, and these changes were associated with the brain from oxidative damage. The dose levels of tartrazine in the present study produced a few adverse effects in learning and memory functions in animals. The mechanisms might be attributed to promoting lipid peroxidation products and reactive oxygen species, inhibiting endogenous antioxidant defense enzymes and the brain tissue damage. Tartrazine is an artificial azo dye commonly used in human food and pharmaceutical products. Since the last assessment carried out by the Joint FAO/WHO Expert Committee on Food Additives in 1964, many new studies have been conducted. However, there is a little information about the effects on learning and memory performance. The present study was conducted to evaluate the toxic effect of tartrazine on the learning and memory functions in animals and its possible mechanism involved. Based on our results, we believe that more extensive assessment of food additives in current use is warranted. © 2011 Institute of Food Technologists®

Application of nanoscopic dynamic mechanical analysis for evaluating the mechanical behavior of hard tissues and bonded interfaces

NASA Astrophysics Data System (ADS)

Ryou, Heonjune

2011-12-01

In this study Dynamic Mechanical Analysis (DMA) was applied to dentin, the macro hybrid layer and intact hybrid layers of the bonded dental restorative interface using nanoindentation. Both intertubular and peritubular dentin were evaluated by DMA using discrete and scanning mode nanoindentation. The complex (E*), loss (E"), and storage (E') moduli were quantified over a range of indentation loads and scanning frequencies. The storage modulus of the peritubular cuff (22.19 GPa0.05). A model bonded interface (i.e. the macro hybrid) was evaluated using scanning DMA. A new approach for hydrating samples using ethylene glycol solution was developed and then applied to identify the importance of hydration on the measured properties. Fully hydrated samples exhibited mean values of E*, E' and E" of 3.54 GPa, 3.42 GPa and 0.86 GPa, respectively, whereas fully dehydrated samples exhibited values of 4.01 GPa, 3.88 GPa and 0.94 GPa, respectively. There were significant differences in the complex modulus (p<0.05) and storage modulus (p<0.001) between the hydrated and dehydrated conditions. However, differences in the loss moduli with hydration were not significantly different (p>0.05). A dynamic loading frequency of 100 Hz and scanning frequency of 0.2 Hz were identified to provide the most reliable results in scanning the collagen-based systems. Lastly, the optimal testing parameters obtained from studying the macro hybrid layer were used to evaluate intact resin-dentin bonded interfaces. The property maps clearly distinguished variations in properties as a function of the constituents. It was identified that scanning based nanoDMA is a potent tool for evaluating mechanical properties of the hybrid layer but testing parameters and maintenance of the hydration are critical to the interpretation of apparent mechanical behavior.

Advantages and disadvantages of mechanical vs. manual anastomosis in colorectal surgery. A prospective study.

PubMed

Cajozzo, M; Compagno, G; DiTora, P; Spallitta, S I; Bazan, P

1990-02-01

The merits of mechanical versus manual anastomosis were evaluated in a prospective study of 48 patients undergoing resection of colonic or rectal cancer. The analyzed factors included the time required for construction of the anastomosis, the length of hospital stay, the cost/benefit ratio and complications. The anastomosis was manually performed with monolayer polyglactin 910 sutures in 24 cases and mechanically with an E.E.A. stapler in 24. The anastomosis time averaged 14 min in the suture group and 14.3 min in the stapling group, and the respective hospitalization times were 16 and 17 days. The mean cost was 48,000 lire in the manual, and 200,000 lire in the mechanical group. Four complications occurred in each group. Apart from the cost, no intergroup difference was statistically significant.

Microstructure, strengthening mechanisms and hot deformation behavior of an oxide-dispersion strengthened UFG Al6063 alloy

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

Asgharzadeh, H.; Kim, H.S.; Simchi, A., E-mail: simchi@sharif.edu

2013-01-15

An ultrafine-grained Al6063/Al{sub 2}O{sub 3} (0.8 vol.%, 25 nm) nanocomposite was prepared via powder metallurgy route through reactive mechanical alloying and hot powder extrusion. Scanning electron microcopy, transmission electron microscopy, and back scattered electron diffraction analysis showed that the grain structure of the nanocomposite is trimodal and composed of nano-size grains (< 0.1 {mu}m), ultrafine grains (0.1-1 {mu}m), and micron-size grains (> 1 {mu}m) with random orientations. Evaluation of the mechanical properties of the nanocomposite based on the strengthening-mechanism models revealed that the yield strength of the ultrafine-grained nanocomposite is mainly controlled by the high-angle grain boundaries rather than nanometricmore » alumina particles. Hot deformation behavior of the material at different temperatures and strain rates was studied by compression test and compared to coarse-grained Al6063 alloy. The activation energy of the hot deformation process for the nanocomposite was determined to be 291 kJ mol{sup -1}, which is about 64% higher than that of the coarse-grained alloy. Detailed microstructural analysis revealed that dynamic recrystallization is responsible for the observed deformation softening in the ultrafine-grained nanocomposite. - Highlights: Black-Right-Pointing-Pointer The strengthening mechanisms of Al6063/Al{sub 2}O{sub 3} nanocomposite were evaluated. Black-Right-Pointing-Pointer Hot deformation behavior of the nanocomposite was studied. Black-Right-Pointing-Pointer The hot deformation activation energy was determined using consecutive models. Black-Right-Pointing-Pointer The restoration mechanisms and microstructural changes are presented.« less

A Model-Based Product Evaluation Protocol for Comparison of Safety-Engineered Protection Mechanisms of Winged Blood Collection Needles.

PubMed

Haupt, C; Spaeth, J; Ahne, T; Goebel, U; Steinmann, D

2016-05-01

To evaluate differences in product characteristics and user preferences of safety-engineered protection mechanisms of winged blood collection needles. Randomized model-based simulation study. University medical center. A total of 33 third-year medical students. Venipuncture was performed using winged blood collection needles with 4 different safety mechanisms: (a) Venofix Safety, (b) BD Vacutainer Push Button, (c) Safety-Multifly, and (d) Surshield Surflo. Each needle type was used in 3 consecutive tries: there was an uninstructed first handling, then instructions were given according to the operating manual; subsequently, a first trial and second trial were conducted. Study end points included successful activation, activation time, single-handed activation, correct activation, possible risk of needlestick injury, possibility of deactivation, and preferred safety mechanism. The overall successful activation rate during the second trial was equal for all 4 devices (94%-100%). Median activation time was (a) 7 s, (b) 2 s, (c) 9 s, and (d) 7 s. Single-handed activation during the second trial was (a) 18%, (b) 82%, (c) 15%, and (d) 45%. Correct activation during the second trial was (a) 3%, (b) 64%, (c) 15%, and (d) 39%. Possible risk of needlestick injury during the second trial was highest with (d). Possibility of deactivation was (a) 0%, (b) 12%, (c) 9%, and (d) 18%. Individual preferences for each system were (a) 11, (b) 17, (c) 5, and (d) 0. The main reason for preference was the comprehensive safety mechanism. Significant differences exist between safety mechanisms of winged blood collection needles.

An experimental apparatus to simulate body-powered prosthetic usage: Development and preliminary evaluation.

PubMed

Gao, Fan; Rodriguez, Johanan; Kapp, Susan

2016-06-01

Harness fitting in the body-powered prosthesis remains more art than science due to a lack of consistent and quantitative evaluation. The aim of this study was to develop a mechanical, human-body-shaped apparatus to simulate body-powered upper limb prosthetic usage and evaluate its capability of quantitative examination of harness configuration. The apparatus was built upon a torso of a wooden mannequin and integrated major mechanical joints to simulate terminal device operation. Sensors were used to register cable tension, cable excursion, and grip force simultaneously. The apparatus allowed the scapula to move up to 127 mm laterally and the load cell can measure the cable tension up to 445 N. Our preliminary evaluation highlighted the needs and importance of investigating harness configurations in a systematic and controllable manner. The apparatus allows objective, systematic, and quantitative evaluation of effects of realistic harness configurations and will provide insightful and working knowledge on harness fitting in upper limb amputees using body-powered prosthesis. © The International Society for Prosthetics and Orthotics 2015.

A study of the feasibility of mechanical pumps for use with the Pioneer-Venus probe mass spectrometer inlet system

NASA Technical Reports Server (NTRS)

Thomas, N. C.; Crosmer, W. E.; Nowak, D.

1973-01-01

A survey of mechanical vacuum pumps was completed. A small Roots blower for flight mass spectrometer applications was evaluated with respect to system operating parameters in a number of different modes of operation. The survey indicated that a metal bellows pump might be a viable alternative for the systems requirements. The results of the study are given, including current status of possible flight-type pumps, a systems analysis using available pumps, and recommendations for fabrication and tests of a potential flight-type pump.

Forms of attention and attentional disorders.

PubMed

O'Donnell, Brian F

2002-05-01

Difficulties in attention or concentration are observed in many clinical syndromes. Cognitive studies of normal attention and neuropsychological studies of brain dysfunction indicate that attention reflects a variety of mechanisms. These processes include the startle response, the orienting response, selective attention, vigilance, and divided attention. Understanding the specific mechanisms involved in attention deficits or lapses may be helpful in planning and evaluating remediation programs and in altering patients' environments to compensate for specific attention deficits. In this article, forms of attention and disorders of attention are discussed, with emphasis on their importance to every day activities.

Researching evaluation influence: a review of the literature.

PubMed

Herbert, James Leslie

2014-10-01

The impact of an evaluation is an important consideration in designing and carrying out evaluations. Evaluation influence is a way of thinking about the effect that an evaluation can have in the broadest possible terms, which its proponents argue will lead to a systematic body of evidence about influential evaluation practices. This literature review sets out to address three research questions: How have researchers defined evaluation influence; how is this reflected in the research; and what does the research suggest about the utility of evaluation influence as a conceptual framework. Drawing on studies that had cited one of the key evaluation influence articles and conducted original research on some aspect of influence this article reviewed the current state of the literature toward the goal of developing a body of evidence about how to practice influential evaluation. Twenty-eight studies were found that have drawn on evaluation influence, which were categorized into (a) descriptive studies, (b) analytical studies, and (c) hypothesis testing. Despite the prominence of evaluation influence in the literature, there is slow progress toward a persuasive body of literature. Many of the studies reviewed offered vague and inconsistent definitions and have applied influence in an unspecified way in the research. It is hoped that this article will stimulate interest in the systematic study of influence mechanisms, leading to improvements in the potential for evaluation to affect positive social change. © The Author(s) 2014.

Mechanical response of 3D Insert® PCL to compression.

PubMed

Brunelli, M; Perrault, C M; Lacroix, D

2017-01-01

3D polymeric scaffolds are increasingly used for in vitro experiments aiming to mimic the environment found in vivo, to support for cellular growth and to induce differentiation through the application of external mechanical cues. In research, experimental results must be shown to be reproducible to be claimed as valid and the first clause to ensure consistency is to provide identical initial experimental conditions between trials. As a matter of fact, 3D structures fabricated in batch are supposed to present a highly reproducible geometry and consequently, to give the same bulk response to mechanical forces. This study aims to measure the overall mechanical response to compression of commercially available 3D Insert PCL scaffolds (3D PCL) fabricated in series by fuse deposition and evaluate how small changes in the architecture of scaffolds affect the mechanical response. The apparent elastic modulus (Ea) was evaluated by performing quasi-static mechanical tests at various temperatures showing a decrease in material stiffness from 5MPa at 25°C to 2.2MPa at 37°C. Then, a variability analysis revealed variations in Ea related to the repositioning of the sample into the testing machine, but also consistent differences comparing different scaffolds. To clarify the source of the differences measured in the mechanical response, the same scaffolds previously undergoing compression, were scanned by micro computed tomography (μCT) to identify any architectural difference. Eventually, to clarify the contribution given by differences in the architecture to the standard deviation of Ea, their mechanical response was qualitatively compared to a compact reference material such as polydimethylsiloxane (PDMS). This study links the geometry, architecture and mechanical response to compression of 3D PCL scaffolds and shows the importance of controlling such parameters in the manufacturing process to obtain scaffolds that can be used in vitro or in vivo under reproducible conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

The individual therapy process questionnaire: development and validation of a revised measure to evaluate general change mechanisms in psychotherapy.

PubMed

Mander, Johannes

2015-01-01

There is a dearth of measures specifically designed to assess empirically validated mechanisms of therapeutic change. To fill in this research gap, the aim of the current study was to develop a measure that covers a large variety of empirically validated mechanisms of change with corresponding versions for the patient and therapist. To develop an instrument that is based on several important change process frameworks, we combined two established change mechanisms instruments: the Scale for the Multiperspective Assessment of General Change Mechanisms in Psychotherapy (SACiP) and the Scale of the Therapeutic Alliance-Revised (STA-R). In our study, 457 psychosomatic inpatients completed the SACiP and the STA-R and diverse outcome measures in early, middle and late stages of psychotherapy. Data analyses were conducted using factor analyses and multilevel modelling. The psychometric properties of the resulting Individual Therapy Process Questionnaire were generally good to excellent, as demonstrated by (a) exploratory factor analyses on both patient and therapist ratings, (b) CFA on later measuring times, (c) high internal consistencies and (d) significant outcome predictive effects. The parallel forms of the ITPQ deliver opportunities to compare the patient and therapist perspectives for a broader range of facets of change mechanisms than was hitherto possible. Consequently, the measure can be applied in future research to more specifically analyse different change mechanism profiles in session-to-session development and outcome prediction. Key Practitioner Message This article describes the development of an instrument that measures general mechanisms of change in psychotherapy from both the patient and therapist perspectives. Post-session item ratings from both the patient and therapist can be used as feedback to optimize therapeutic processes. We provide a detailed discussion of measures developed to evaluate therapeutic change mechanisms. Copyright © 2014 John Wiley & Sons, Ltd.

A method of determining bending properties of poultry long bones using beam analysis and micro-CT data.

PubMed

Vaughan, Patrick E; Orth, Michael W; Haut, Roger C; Karcher, Darrin M

2016-01-01

While conventional mechanical testing has been regarded as a gold standard for the evaluation of bone heath in numerous studies, with recent advances in medical imaging, virtual methods of biomechanics are rapidly evolving in the human literature. The objective of the current study was to evaluate the feasibility of determining the elastic and failure properties of poultry long bones using established methods of analysis from the human literature. In order to incorporate a large range of bone sizes and densities, a small number of specimens were utilized from an ongoing study of Regmi et al. (2016) that involved humeri and tibiae from 3 groups of animals (10 from each) including aviary, enriched, and conventional housing systems. Half the animals from each group were used for 'training' that involved the development of a regression equation relating bone density and geometry to bending properties from conventional mechanical tests. The remaining specimens from each group were used for 'testing' in which the mechanical properties from conventional tests were compared to those predicted by the regression equations. Based on the regression equations, the coefficients of determination for the 'test' set of data were 0.798 for bending bone stiffness and 0.901 for the yield (or failure) moment of the bones. All regression slopes and intercepts values for the tests versus predicted plots were not significantly different from 1 and 0, respectively. The study showed the feasibility of developing future methods of virtual biomechanics for the evaluation of poultry long bones. With further development, virtual biomechanics may have utility in future in vivo studies to assess laying hen bone health over time without the need to sacrifice large groups of animals at each time point. © 2016 Poultry Science Association Inc.

Report on carcinogens monograph on 1-bromopropane.

PubMed

2013-09-01

The National Toxicology Program conducted a cancer evaluation on 1 bromopropane for possible listing in the Report on Carcinogens (RoC). The cancer evaluation is captured in the RoC monograph, which was peer reviewed in a public forum. The monograph consists of two components: (Part 1) the cancer evaluation, which reviews the relevant scientific information, assesses its quality, applies the RoC listing criteria to the scientific information, and provides the NTP recommendation for listing status for 1 bromopropane in the RoC, and (Part 2) the substance profile proposed for the RoC, containing the NTP's listing status recommendation, a summary of the scientific evidence considered key to reaching that decision, and data on properties, use, production, exposure, and Federal regulations and guidelines to reduce exposure to 1-bromopropane. This monograph provides an assessment of the available scientific information on 1 bromopropane, including human exposure and properties, disposition and toxicokinetics, cancer studies in experimental animals, and studies of mechanisms and other related effects, including relevant toxicological effects, genetic toxicology, and mechanisms of carcinogenicity. From this assessment, the NTP recommended that 1 bromopropane be listed as reasonably anticipated to be a human carcinogen in the RoC based on sufficient evidence from studies in experimental animals, which found inhalation exposure to 1-bromopropane caused skin tumors in male rats, large intestine tumors in female and male rats, and lung tumors in female mice. Also noted was that 1 bromopropane, either directly or via reactive metabolites, caused molecular alterations that typically are associated with carcinogenesis, including genotoxicity, oxidative stress, and glutathione depletion. These alterations, observed in mainly in vitro and toxicity studies in rodents, are relevant to possible mechanisms of human carcinogenicity and support the relevance of the cancer studies in experimental animals to humans.

Study on the repeatability of manufacturing nano-silica (SiO2) reinforced composite laminates

NASA Astrophysics Data System (ADS)

Prince Jeya Lal, L.; Ramesh, S.; Natarajan, Elango

2018-04-01

Repeatability to manufacture nano-silica reinforced composite laminates with consistent mechanical properties is studied. In this study, composite laminates are manufactured by hand layup and there after mechanical properties of the laminates are evaluated under tensile and flexural loading conditions. Composite laminates are fabricated and tested under equivalent conditions. Plain weave E-Glass fabric and epoxy LY556 are used as reinforcement and matrix. Nano-silica of size 17nm is used as filler. To enhance the reliability of composite characterization, utmost care is taken to avoid defects like voids, surface defects and under-saturations. Homogeneous distribution of nano silica in matrix is analyzed using TEM study. Inconsistencies in mechanical properties are quantified by coefficient of variation. In this study, the coefficient of variation is estimated in terms of break load for tensile test is 4.45 and for flexural test is 2.27 and is well within the limits.

HIGH-LEVEL ARSENITE REMOVAL FROM GROUNDWATER BY ZERO-VALENT IRON

EPA Science Inventory

The objectives of this study were to conduct batch and column studies to (i) assess the effectiveness of zero-valent iron for arsenic remediation in groundwater, (ii) determine removal mechanisms of arsenic, and (iii) evaluate implications of these processes with regard to the st...

Characterization and evaluation physical properties biodegradable plastic composite from seaweed (Eucheuma cottonii)

NASA Astrophysics Data System (ADS)

Deni, Glar Donia; Dhaningtyas, Shalihat Afifah; Fajar, Ibnu; Sudarno

2015-12-01

The characterization and evaluation of biodegradable plastic composed of a mixture PVA - carrageenan - chitosan was conducted in this study. Obtained data were then compared to commercial biodegradable plastic. Characteristic of plastic was mechanical tested such as tensile - strength and elongation. Plastic degradation was studied using composting method for 7 days and 14 days. The results showed that the increase carrageenan will decrease tensile-strength and elongation plastic composite. In addition, increase carrageenan would increase the degraded plastics composite.

Performance evaluation of buried pipe installation.

DOT National Transportation Integrated Search

2010-05-01

The purpose of this study is to determine the effects of geometric and mechanical parameters characterizing the soil structure interaction developed in a buried pipe installation located under roads/highways. The drainage pipes or culverts installed ...

Exploratory study : vehicle mileage fees in Texas.

DOT National Transportation Integrated Search

2011-01-01

This project evaluates Vehicle Mileage (VM) fees as a possible funding mechanism for meeting the State of Texas : long-term transportation needs. Researchers conducted listening sessions with the general public and stakeholders to : gather input o...

Research on dynamic routing mechanisms in wireless sensor networks.

PubMed

Zhao, A Q; Weng, Y N; Lu, Y; Liu, C Y

2014-01-01

WirelessHART is the most widely applied standard in wireless sensor networks nowadays. However, it does not provide any dynamic routing mechanism, which is important for the reliability and robustness of the wireless network applications. In this paper, a collection tree protocol based, dynamic routing mechanism was proposed for WirelessHART network. The dynamic routing mechanism was evaluated through several simulation experiments in three aspects: time for generating the topology, link quality, and stability of network. Besides, the data transmission efficiency of this routing mechanism was analyzed. The simulation and evaluation results show that this mechanism can act as a dynamic routing mechanism for the TDMA-based wireless sensor network.

Evaluation of Surlyn 8920 as PHE Visor Material and Evaluations of New Adhesives for Improving Bonding Between Teflon and Stainless Steel at Cryogenic Temperature

NASA Technical Reports Server (NTRS)

Ray, Asit K.

1991-01-01

Two studies are presented, and in the first study, Surlyn 8920 (an ionic and amorphous low density polyethylene made by Dupont) was evaluated as a possible replacement of Plexyglass G as PHE visor material. Four formulations of the polymer were made by adding different amounts of UV stabilizer, energy quencher, and antioxident in a Brabender Plasticorder. The formulated polymers were molded in the form of sheets in a compression molder. Cut samples from the molded sheets were exposed in a weatherometer and tested on Instron Tensile Tester for strength and elongation. Specially molded samples of the formulated polymers were subjected to Charpy Impact Tests. In the second study, preliminary evaluations of adhesives for improvement of bonding between Teflon and stainless steel (SS) were performed. Kapton, a high temperature polyimide made by Dupont, and a rubber based adhesive made by Potter Paint Co., were evaluated against industrial quality epoxy, the current material used to bond Teflon and SS. The degreased surfaces of the SS discs were etched mechanically, with a few of these etched chemically. The surfaces of the SS discs were etched mechanically, with a few of these etched chemically. Bonding strengths were evaluated using lap shear tests on the Instron Tensile Tester for the samples bonded by Kapton and industrial quality epoxy. Bond strengths were also evaluated using a pull test on the Instron for the samples bonded by Potter adhesive (CWL-152) and industrial quality epoxy. Based on limited lap shear data, Kapton gave bond strength favorable compared to that of industrial epoxy. Based on limited pull test data, Kapton bonded and CWL-152 bonded samples showed poor strength compared to epoxy bonded sample.

Evaluation of different crosslinking agents on hybrid biomimetic collagen-hydroxyapatite composites for regenerative medicine.

PubMed

Krishnakumar, Gopal Shankar; Gostynska, Natalia; Dapporto, Massimiliano; Campodoni, Elisabetta; Montesi, Monica; Panseri, Silvia; Tampieri, Anna; Kon, Elizaveta; Marcacci, Maurilio; Sprio, Simone; Sandri, Monica

2018-01-01

This study focuses on the development of novel bone-like scaffolds by bio-inspired, pH-driven, mineralization of type I collagen matrix with magnesium-doped hydroxyapatite nanophase (MgHA/Coll). To this aim, this study evaluates the altered modifications in the obtained composite due to different crosslinkers such as dehydrothermal treatment (DHT), 1,4-butanediol diglycidyl ether (BDDGE) and ribose in terms of morphological, physical-chemical and biological properties. The physical-chemical properties of the composites evaluated by XRD, FTIR, ICP and TGA demonstrated that the chemical mimesis of bone was effectively achieved using the in-lab biomineralization process. Furthermore, the presence of various crosslinkers greatly promoted beneficial enzymatic resistivity and swelling ability. The morphological results revealed highly porous and fibrous micro-architecture with total porosity above 85% with anisotropic pore size within the range of 50-200μm in all the analysed composites. The mechanical behaviour in response to compressive forces demonstrated enhanced compressive modulus in all crosslinked composites, suggesting that mechanical behaviour is largely dependent on the type of crosslinker used. The biomimetic compositional and morphological features of the composites elicited strong cell-material interaction. Therefore, the results showed that by activating specific crosslinking mechanisms, hybrid composites can be designed and tailored to develop tissue-specific biomimetic biomaterials for hard tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

An efficient laboratory workflow for environmental risk assessment of organic chemicals.

PubMed

Zhu, Linyan; Santiago-Schübel, Beatrix; Xiao, Hongxia; Thiele, Björn; Zhu, Zhiliang; Qiu, Yanling; Hollert, Henner; Küppers, Stephan

2015-07-01

In this study, we demonstrate a fast and efficient workflow to investigate the transformation mechanism of organic chemicals and evaluate the toxicity of their transformation products (TPs) in laboratory scale. The transformation process of organic chemicals was first simulated by electrochemistry coupled online to mass spectrometry (EC-MS). The simulated reactions were scaled up in a batch EC reactor to receive larger amounts of a reaction mixture. The mixture sample was purified and concentrated by solid phase extraction (SPE) for the further ecotoxicological testing. The combined toxicity of the reaction mixture was evaluated in fish egg test (FET) (Danio rerio) compared to the parent compound. The workflow was verified with carbamazepine (CBZ). By using EC-MS seven primary TPs of CBZ were identified; the degradation mechanism was elucidated and confirmed by comparison to literature. The reaction mixture and one primary product (acridine) showed higher ecotoxicity in fish egg assay with 96 h EC50 values of 1.6 and 1.0 mg L(-1) than CBZ with the value of 60.8 mg L(-1). The results highlight the importance of transformation mechanism study and toxicological effect evaluation for organic chemicals brought into the environment since transformation of them may increase the toxicity. The developed process contributes a fast and efficient laboratory method for the risk assessment of organic chemicals and their TPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

The work is never ending: uncovering teamwork sustainability using realistic evaluation.

PubMed

Frykman, Mandus; von Thiele Schwarz, Ulrica; Muntlin Athlin, Åsa; Hasson, Henna; Mazzocato, Pamela

2017-03-20

Purpose The purpose of this paper is to uncover the mechanisms influencing the sustainability of behavior changes following the implementation of teamwork. Design/methodology/approach Realistic evaluation was combined with a framework (DCOM®) based on applied behavior analysis to study the sustainability of behavior changes two and a half years after the initial implementation of teamwork at an emergency department. The DCOM® framework was used to categorize the mechanisms of behavior change interventions (BCIs) into the four categories of direction, competence, opportunity, and motivation. Non-participant observation and interview data were used. Findings The teamwork behaviors were not sustained. A substantial fallback in managerial activities in combination with a complex context contributed to reduced direction, opportunity, and motivation. Reduced direction made staff members unclear about how and why they should work in teams. Deterioration of opportunity was evident from the lack of problem-solving resources resulting in accumulated barriers to teamwork. Motivation in terms of management support and feedback was reduced. Practical implications The implementation of complex organizational changes in complex healthcare contexts requires continuous adaption and managerial activities well beyond the initial implementation period. Originality/value By integrating the DCOM® framework with realistic evaluation, this study responds to the call for theoretically based research on behavioral mechanisms that can explain how BCIs interact with context and how this interaction influences sustainability.

In vivo skin effects of a dimethylaminoethanol (DMAE) based formulation.

PubMed

Tadini, K A; Campos, P M B G Maia

2009-12-01

Dimethylaminoethanol (DMAE) has been used in anti-aging formulations but few scientifically based data address its efficacy. The aim of this study was to evaluate the effects of DMAE-based formulations on hairless mice and human skin. Formulations containing with or without DMAE were applied to the dorsum of hairless mice. Histopathological and histometric evaluations were carried out after seven days. Formulations were also applied to the ventral forearm and the lateral periocular area of human volunteers. Stratum corneum water content and skin mechanical properties were analyzed using Corneometer and Cutometer, before and after a single and repeated application. Histometric evaluations showed that formulations with or without DMAE increased the viable epidermis thickness, but only the DMAE-supplemented formulation led to increased dermal thickness. DMAE also induced increase in collagen fiber thickness, which was observed in the histopathological study. After the single and the 8-week period application on human skin, formulations with and without DMAE enhanced the stratum corneum water content in the forearm skin. Mechanical properties were not significantly modified. So, we can suggest that DMAE action is related to its effects on the dermis as observed in the histopathological and histometric studies and showed hydration effects on skin.

Seismic performance evaluation of an infilled rocking wall frame structure through quasi-static cyclic testing

NASA Astrophysics Data System (ADS)

Pan, Peng; Wu, Shoujun; Wang, Haishen; Nie, Xin

2018-04-01

Earthquake investigations have illustrated that even code-compliant reinforced concrete frames may suffer from soft-story mechanism. This damage mode results in poor ductility and limited energy dissipation. Continuous components offer alternatives that may avoid such failures. A novel infilled rocking wall frame system is proposed that takes advantage of continuous component and rocking characteristics. Previous studies have investigated similar systems that combine a reinforced concrete frame and a wall with rocking behavior used. However, a large-scale experimental study of a reinforced concrete frame combined with a rocking wall has not been reported. In this study, a seismic performance evaluation of the newly proposed infilled rocking wall frame structure was conducted through quasi-static cyclic testing. Critical joints were designed and verified. Numerical models were established and calibrated to estimate frame shear forces. The results evaluation demonstrate that an infilled rocking wall frame can effectively avoid soft-story mechanisms. Capacity and initial stiffness are greatly improved and self-centering behavior is achieved with the help of the infilled rocking wall. Drift distribution becomes more uniform with height. Concrete cracks and damage occurs in desired areas. The infilled rocking wall frame offers a promising approach to achieving seismic resilience.

3T magnetic resonance imaging testing of externally programmable shunt valves

PubMed Central

Zabramski, Joseph M.; Preul, Mark C.; Debbins, Josef; McCusker, Daniel J.

2012-01-01

Background: Exposure of externally programmable shunt-valves (EPS-valves) to magnetic resonance imaging (MRI) may lead to unexpected changes in shunt settings, or affect the ability to reprogram the valve. We undertook this study to examine the effect of exposure to a 3T MRI on a group of widely used EPS-valves. Methods: Evaluations were performed on first generation EPS-valves (those without a locking mechanism to prevent changes in shunt settings by external magnets other than the programmer) and second generation EPS-valves (those with a locking mechanisms). Fifteen new shunt-valves were divided into five groups of three identical valves each, and then exposed to a series of six simulated MRI scans. After each of the exposures, the valves were evaluated to determine if the valve settings had changed, and whether the valves could be reprogrammed. The study produced 18 evaluations for each line of shunt-valves. Results: Exposure of the first generation EPS-valves to a 3T magnetic field resulted in frequent changes in the valve settings; however, all valves retained their ability to be reprogrammed. Repeated exposure of the second generation EPS-valves has no effect on shunt valve settings, and all valves retained their ability to be interrogated and reprogrammed. Conclusions: Second generation EPS-valves with locking mechanisms can be safely exposed to repeated 3T MRI systems, without evidence that shunt settings will change. The exposure of the first generation EPS-valves to 3T MRI results in frequent changes in shunt settings that necessitate re-evaluation soon after MRI to avoid complications. PMID:22937481

Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

NASA Astrophysics Data System (ADS)

Kim, Sang-Young; Shim, Chun Sik; Sturtevant, Caleb; Kim, Dave (Dae-Wook); Song, Ha Cheol

2014-09-01

Glass Fiber Reinforced Plastic (GFRP) structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties

Immunological mechanisms for desensitization and tolerance in food allergy1

PubMed Central

Rachid, Rima; Umetsu, Dale T.

2013-01-01

Food allergy is a major public health concern in westernized countries, estimated to affect 5% of children and 3-4 % of adults. Allergen specific immunotherapy for food allergy is currently being actively evaluated, but is still experimental. The optimal protocol, in terms of the route of administration of the food, target maintenance dose, duration of maintenance therapy and the optimal patient for these procedures are still being worked out. The mechanisms underlying successful food desensitization are also unclear, in part because there is no standard immunotherapy protocol. The mechanisms involved however, may include mast cell and basophil suppression, development of food-specific IgG4 antibodies, reduction in the food specific IgE/IgG4 ratio, up-regulation and expansion of natural or inducible regulatory T cells, a skewing from a Th2 to a Th1 profile and the development of anergy and/or deletion in antigen specific cells. Additional studies are required to elucidate and understand these mechanisms by which desensitization and tolerance are achieved, and which may reveal valuable biomarkers for evaluating and following food allergic patients on immunotherapy. PMID:22821087

Does glimepiride alter the pharmacokinetics of sildenafil citrate in diabetic nephropathy animals: investigating mechanism of interaction by molecular modeling studies.

PubMed

Tripathi, Alok Shiomurti; Timiri, Ajay Kumar; Mazumder, Papiya Mitra; Chandewar, Anil

2015-10-01

The present study evaluates possible drug interactions between glimepiride (GLIM) and sildenafil citrate (SIL) in streptozotocin (STZ)-induced diabetic nephropathic (DN) animals and also postulates the possible mechanism of interaction based on molecular modeling studies. Diabetic nephropathy was induced by single dose of STZ (60 mg kg(-1), i.p.) and was confirmed by assessing blood and urine biochemical parameters 28 days after induction. Selected DN animals were used to explore the drug interaction between GLIM (0.5 mg kg(-1), p.o.) and SIL (2.5 mg kg(-1), p.o.) on the 29th and 70th day of the protocol. Possible drug interaction was assessed by evaluating the plasma drug concentration using HPLC-UV and changes in biochemical parameters in blood and urine were also determined. The mechanism of the interaction was postulated from the results of a molecular modeling study using the Maestro module of Schrodinger software. DN was confirmed as there was significant alteration in blood and urine biochemical parameters in STZ-treated groups. The concentration of SIL increased significantly (P < 0.001) in rat plasma when co-administered with GLIM on the 70th day of the protocol. Molecular modeling revealed important interactions with rat serum albumin and CYP2C9. GLIM has a strong hydrophobic interaction with binding site residues of rat serum albumin compared to SIL, whereas for CYP2C9, GLIM forms a stronger hydrogen bond than SIL with polar contacts and hydrophobic interactions. The present study concludes that bioavailability of SIL increases when co-administered chronically with GLIM in the management of DN animals, and the mechanism is supported by molecular modeling studies.

Evaluating web-based cognitive-affective remediation in recent trauma survivors: study rationale and protocol.

PubMed

Fine, Naomi B; Achituv, Michal; Etkin, Amit; Merin, Ofer; Shalev, Arieh Y

2018-01-01

Background : The immediate aftermath of traumatic events is a period of enhanced neural plasticity, following which some survivors remain with post-traumatic stress disorder (PTSD) whereas others recover. Evidence points to impairments in emotional reactivity, emotion regulation, and broader executive functions as critically contributing to PTSD. Emerging evidence further suggests that the neural mechanisms underlying these functions remain plastic in adulthood and that targeted retraining of these systems may enhance their efficiency and could reduce the likelihood of developing PTSD. Administering targeted neurocognitive training shortly after trauma exposure is a daunting challenge. This work describes a study design addressing that challenge. The study evaluated the direct effects of cognitive remediation training on neurocognitive mechanisms that hypothetically underlay PTSD, and the indirect effect of this intervention on emerging PTSD symptoms. Method : We describe a study rationale, design, and methodological choices involving: (a) participants' enrolment; (b) implementation and management of a daily self-administered, web-based intervention; (c) reliable, timely screening and assessment of treatment of eligible survivors; and (d) defining control conditions and outcome measures. We outline the rationale of choices made regarding study sample, timing of intervention, measurements, monitoring participants' adherence, and ways to harmonize and retain interviewers' fidelity and mitigate eventual burnout by repeated contacts with recently traumatized survivors. Conclusion : Early web-based interventions targeting causative mechanisms of PTSD can be informed by the model presented in this paper.

Characterization, Long-Term Behavior Evaluation and Thermomechanical Properties of Untreated and Treated Flax Fiber-Reinforced Composites

NASA Astrophysics Data System (ADS)

Amiri, Ali

In recent years there has been a resurgence of interest in the usage of natural fiber reinforced composites in more advanced structural applications. Consequently, the need for improving their mechanical properties as well as service life and long-term behavior modeling and predictions has arisen. In a step towards further development of these materials, in this study, two newly developed biobased resins, derived from soybean oil, methacrylated epoxidized sucrose soyate and double methacrylated epoxidized sucrose soyate are combined with untreated and alkaline treated flax fiber to produce novel biocomposites. Vinyl ester reinforced with flax fiber is used as control in addition to comparing properties of biobased composites against commercial pultruded composites. Effects of alkaline treatment of flax fiber as well as addition of 1% acrylic resin to vinyl ester and the two mentioned biobased resins on mechanical properties are studied. Properties are evaluated in short-term and also, after being exposed to accelerated weathering (i.e. UV and moisture). Moreover, long-term creep of these novel biobased composites and effect of fiber and matrix treatment on viscoelastic behavior is investigated using Time-temperature superposition (TTS) principle. Based on the results of this study, the TTS provides an accelerated method for evaluation of mechanical properties of biobased composites, and satisfactory master curves are achieved by use of this principle. Also, fiber and matrix treatments were effective in increasing mechanical properties of biobased composites in short-term, and treatments delayed the creep response and slowed the process of creep in composites under study in the steady state region. Overall, results of this study reveal the successful production of biocomposites having properties that meet or exceed those of conventional pultruded members while maintaining high biocontent. Composites using treated flax fiber and newly developed resins showed less degradation in properties after accelerated weather exposure. Procedures and methods developed throughout this study, as well as results presented are essential to further development of these novel materials and utilizing them in more advanced structural applications. Results presented in this dissertation have been published as 5 peer reviewed journal articles, 2 book chapters and have been presented in 6 national and international conferences.

Fracture Toughness Evaluation of a Ni2MnGa Alloy Through Micro Indentation Under Magneto-Mechanical Loading

NASA Astrophysics Data System (ADS)

Goanţă, Viorel; Ciocanel, Constantin

2017-12-01

Ni2MnGa is a ferromagnetic alloy that exhibits the shape memory effect either induced by an externally applied magnetic field or mechanical stress. Due to the former, the alloy is commonly called magnetic shape memory alloy or MSMA. The microstructure of the MSMA consists of tetragonal martensite variants (three in the most general case) that are characterized by a magnetization vector which is aligned with the short side of the tetragonal unit cell. Exposing the MSMA to a magnetic field causes the magnetization vector to rotate and align with the external field, eventually leading to variant reorientation. The variant reorientation is observed macroscopically in the form of recoverable strain of up to 6% [1, 2]. As the magnetic field induced reorientation happens instantaneously [1, 3], MSMAs are suitable for fast actuation, sensing, or power harvesting applications. However, actuation applications are limited by the maximum actuation stress of the material that is about 3.5MPa at approximately 2 to 3% reorientation strain. During MSMA fatigue magneto-mechanical characterization studies [4, 5] it was observed that cracks nucleate and grow on the surface of material samples, after a relatively small number of cycles, leading to loss in material performance. This triggered the need for understanding the mechanisms that govern crack nucleation and growth in MSMAs, as well as the nature of the material, i.e. ductile or brittle. The experimental study reported in this paper was carried out to determine material's fracture toughness, the predominant crack growth directions, and the orientation of the cracks relative to the mechanical loading direction and to the material's microstructure. A fixture has been developed to allow Vickers micro indentation of 3mm by 3mm by 20mm Ni2MnGa samples exposed to different levels of magnetic field and/or mechanical stress. Using the measured characteristics of the impression generated during micro indentation, the lengths of propagated cracks, and appropriate equations (introduced in the paper), and the fracture toughness was evaluated as a function of the magneto-mechanical loading experienced by the material. The influence of the magneto-mechanical loading on the growth of already nucleated cracks has also been evaluated.

Nursing diagnoses in patients having mechanical ventilation support in a respiratory intensive care unit in Turkey.

PubMed

Yücel, Şebnem Çinar; Eşer, Ismet; Güler, Elem Kocaçal; Khorshid, Leyla

2011-10-01

This research was carried out to find out the nursing diagnoses in patients who have mechanical ventilation support in a respiratory intensive care unit. The study was conducted with 51 evaluations of critically ill adult patients who underwent invasive and non-invasive mechanical ventilation therapy in 2008. Data collection was based on Gordon's 11 Functional Health Patterns, and nursing diagnoses were determined according to North American Nursing Diagnosis Association-International (NANDA-I) Taxonomy II. The nursing diagnoses were determined by two researchers separately. The consistency between the nursing diagnoses defined by the two researchers was evaluated by using Cohen's kappa (κ). Forty men (78.4%) and 11 women (21.6%) whose mean ages were 70.19 (SD = 8.96) years were included in the study. Nineteen subgroups of nursing diagnoses about safety/protection domain, and 15 subgroups about activity/rest domain were seen at different rates in the patients. There was a statistically significant difference between mechanical ventilation via tracheostomy or endotracheal tube and decreased cardiac output (d.f. = 1, χ(2) = 4.760, P = 0.029). The relationship between the length of time under mechanical ventilation and impaired physical mobility was considerably significant (d.f. = 3, χ(2) = 24.459, P = 0.000). It was found out that there was a high degree of agreement (96.8%) between the nursing diagnoses defined by the two researchers separately (κ = 0.936, SE = 0.08). © 2011 Blackwell Publishing Asia Pty Ltd.

Evaluation of disintegration properties of orally rapidly disintegrating tablets using a novel disintegration tester.

PubMed

Kondo, Keita; Niwa, Toshiyuki; Danjo, Kazumi

2012-01-01

This report describes a new disintegration tester that can determine not only the disintegration time of orally rapidly disintegrating tablets (ODT), but also the disintegration behavior and mechanism. Using the tester, the disintegration properties of the tablets prepared in a previous study were examined. The purpose of this study is to confirm the utility of the tester as an instrument for evaluating the disintegration properties of ODT and determine relations among time, behavior and mechanism of the disintegration. Results demonstrated that in vitro disintegration time in the tester is similar to that in the commercial disintegration tester for ODT and is highly correlated with oral disintegration time. Observations of disintegration process revealed that a difference in disintegration behavior between tablets compressed at 50-75 MPa and 100 MPa; the disintegration behavior of the tablets were designated immediate disintegrating type and gradual disintegrating type, respectively. The dynamic swelling profile and water absorption profile indicated that the disintegration mechanism of the tablets involved wicking action induced by swelling of the disintegrant; the disintegration time was closely related to the initial rates of swelling and water absorption. Furthermore, the mechanism of water absorption of tablets compressed at 50-75 MPa and 100 MPa shows anomalous diffusion and case-II transport, respectively. The shift in this mechanism is consistent with differences in disintegration time and behavior between the tablets. These findings suggest that information on disintegration properties obtained by our tester is useful for understanding of disintegration phenomena of ODT.

Influence of crosslinking on the mechanical behavior of 3D printed alginate scaffolds: Experimental and numerical approaches.

PubMed

Naghieh, Saman; Karamooz-Ravari, Mohammad Reza; Sarker, M D; Karki, Eva; Chen, Xiongbiao

2018-04-01

Tissue scaffolds fabricated by three-dimensional (3D) bioprinting are attracting considerable attention for tissue engineering applications. Because the mechanical properties of hydrogel scaffolds should match the damaged tissue, changing various parameters during 3D bioprinting has been studied to manipulate the mechanical behavior of the resulting scaffolds. Crosslinking scaffolds using a cation solution (such as CaCl 2 ) is also important for regulating the mechanical properties, but has not been well documented in the literature. Here, the effect of varied crosslinking agent volume and crosslinking time on the mechanical behavior of 3D bioplotted alginate scaffolds was evaluated using both experimental and numerical methods. Compression tests were used to measure the elastic modulus of each scaffold, then a finite element model was developed and a power model used to predict scaffold mechanical behavior. Results showed that crosslinking time and volume of crosslinker both play a decisive role in modulating the mechanical properties of 3D bioplotted scaffolds. Because mechanical properties of scaffolds can affect cell response, the findings of this study can be implemented to modulate the elastic modulus of scaffolds according to the intended application. Copyright © 2018 Elsevier Ltd. All rights reserved.

Full kinetics investigation of the formation reaction of phosphonate esters in the gas-phase: a theoretical study.

PubMed

Kazemian, Mohammad Amin; Habibi-Khorassani, Sayyed Mostafa; Maghsoodlu, Malek Taher; Ebrahimi, Ali

2014-04-01

In the present work, the proposed multiple-mechanisms have been investigated theoretically for the reaction between triphenyl phosphite and dimethyl acetylenedicarboxylate in the presence of N-H acid such as aniline for generation of phosphonate esters using ab initio molecular orbital theory in gas phase. The profile of the potential energy surface was constructed at the HF/6-311G(d,p) level of theory. The kinetics of the gas phase reaction was studied by evaluating the reaction path of various mechanisms. Between 12 speculative proposed mechanisms {step₁, step₂ (with four possibilities), step₃ (with three possibilities), and step₄} only the third speculative mechanism was recognized as a desirable mechanism. Theoretical kinetics data involving k and E(a), activation (ΔG(‡), ΔS(‡) and ΔH(‡)), and thermodynamic parameters (ΔG°, ΔS° and ΔH°) were calculated for each step of the various mechanisms. Step₁ of the desirable mechanism was identified as the rate determining step. Comparison of the theoretical desirable mechanism with the rate law that has been previously obtained by UV spectrophotometry experiments indicated that the results are in good agreement.

Civilian Protection in the Eastern DRC: Evaluation of the MONUSCO Peacekeeping Operation

DTIC Science & Technology

2012-03-01

mechanisms whereby norms are created, changed and exercise their influence …More detailed study of individual cases is needed to clarify the role of...IN THE EASTERN DRC: EVALUATION OF THE MONUSCO PEACEKEEPING OPERATION by Thomas F. Copeland March 2012 Thesis Advisors: Arturo Sotomayor...from the NAVAL POSTGRADUATE SCHOOL March 2012 Author: Thomas F. Copeland Approved by: Arturo Sotomayor Thesis Advisor

Development and Perceptual Evaluation of Amplitude-Based F0 Control in Electrolarynx Speech

ERIC Educational Resources Information Center

Saikachi, Yoko; Stevens, Kenneth N.; Hillman, Robert E.

2009-01-01

Purpose: Current electrolarynx (EL) devices produce a mechanical speech quality that has been largely attributed to the lack of natural fundamental frequency (F0) variation. In order to improve the quality of EL speech, in the present study the authors aimed to develop and evaluate an automatic F0 control scheme, in which F0 was modulated based on…

ThinTool: a spreadsheet model to evaluate fuel reduction thinning cost, net energy output, and nutrient impacts

Treesearch

Sang-Kyun Han; Han-Sup Han; William J. Elliot; Edward M. Bilek

2017-01-01

We developed a spreadsheet-based model, named ThinTool, to evaluate the cost of mechanical fuel reduction thinning including biomass removal, to predict net energy output, and to assess nutrient impacts from thinning treatments in northern California and southern Oregon. A combination of literature reviews, field-based studies, and contractor surveys was used to...

Electromagnetic Thermography Nondestructive Evaluation: Physics-based Modeling and Pattern Mining

PubMed Central

Gao, Bin; Woo, Wai Lok; Tian, Gui Yun

2016-01-01

Electromagnetic mechanism of Joule heating and thermal conduction on conductive material characterization broadens their scope for implementation in real thermography based Nondestructive testing and evaluation (NDT&E) systems by imparting sensitivity, conformability and allowing fast and imaging detection, which is necessary for efficiency. The issue of automatic material evaluation has not been fully addressed by researchers and it marks a crucial first step to analyzing the structural health of the material, which in turn sheds light on understanding the production of the defects mechanisms. In this study, we bridge the gap between the physics world and mathematical modeling world. We generate physics-mathematical modeling and mining route in the spatial-, time-, frequency-, and sparse-pattern domains. This is a significant step towards realizing the deeper insight in electromagnetic thermography (EMT) and automatic defect identification. This renders the EMT a promising candidate for the highly efficient and yet flexible NDT&E. PMID:27158061

Chicken eggshell as suitable calcium source at home.

PubMed

Brun, Lucas R; Lupo, Maela; Delorenzi, Damián A; Di Loreto, Verónica E; Rigalli, Alfredo

2013-09-01

Taken into consideration that the deficiency of calcium (Ca) in the diet is a common problem, the aim of this work was to study the chicken eggshell as Ca source at home. It was evaluated: (1) different mechanisms to process eggshells and find an easy way to determine the required amount of Ca at home and; (2) the flavor and the texture for eggshell fortified food. Chemical and mechanical methods of eggshell processing were evaluated. Changes in flavor and texture were evaluated in volunteers coordinated by a professional chef. A single eggshell contains 2.07 ± 0.18 g of Ca; therefore half an eggshell could provide the amount of Ca needed by adult human beings per day. The best way to use chicken eggshell as Ca dietary supplement is powdered to add to bread, pizza or spaghetti as there were small changes in texture and no changes in flavor.

Deformation Mechanisms and Biocompatibility of the Superelastic Ti-23Nb-0.7Ta-2Zr-0.5N Alloy

NASA Astrophysics Data System (ADS)

Castany, P.; Gordin, D. M.; Drob, S. I.; Vasilescu, C.; Mitran, V.; Cimpean, A.; Gloriant, T.

2016-03-01

In this study, we have synthesized a new Ti-23Nb-0.7Ta-2Zr-0.5N alloy composition with the aim to obtain useful mechanical properties to be used in medicine such as high strength, good superelastic property, low modulus, and large ductility. Thus, mechanical properties including superelasticity and plasticity were investigated in relation with the different deformation mechanisms observed (stress-induced martensitic transformation, twinning and dislocation slip). On the other hand, the corrosion resistance in simulated body fluid (Ringer solution) and the in vitro cell behavior (MG63 human osteoblasts) of such biomedical alloy were also evaluated in order to assess its biocompatibility.

Antidiabetic Drugs in Alzheimer's Disease: Mechanisms of Action and Future Perspectives

PubMed Central

Femminella, Grazia Daniela; Bencivenga, Leonardo; Petraglia, Laura; Visaggi, Lucia; Gioia, Lucia; Grieco, Fabrizio Vincenzo; de Lucia, Claudio; Komici, Klara; Edison, Paul

2017-01-01

Diabetes mellitus (DM) and Alzheimer's disease (AD) are two highly prevalent conditions in the elderly population and major public health burden. In the past decades, a pathophysiological link between DM and AD has emerged and central nervous system insulin resistance might play a significant role as a common mechanism; however, other factors such as inflammation and oxidative stress seem to contribute to the shared pathophysiological link. Both preclinical and clinical studies have evaluated the possible neuroprotective mechanisms of different classes of antidiabetic medications in AD, with some promising results. Here, we review the evidence on the mechanisms of action of antidiabetic drugs and their potential use in AD. PMID:28656154

Relationship between fatigue life in the creep-fatigue region and stress-strain response

NASA Technical Reports Server (NTRS)

Berkovits, A.; Nadiv, S.

1988-01-01

On the basis of mechanical tests and metallographic studies, strainrange partitioned lives were predicted by introducing stress-strain materials parameters into the Universal Slopes Equation. This was the result of correlating fatigue damage mechanisms and deformation mechanisms operating at elevated temperatures on the basis of observed mechanical and microstructural behavior. Correlation between high temperature fatigue and stress strain properties for nickel base superalloys and stainless steel substantiated the method. Parameters which must be evaluated for PP- and CC- life are the maximum stress achievable under entirely plastic and creep conditions respectively and corresponding inelastic strains, and the two more pairs of stress strain parameters must be ascertained.

Academic cheating as a function of defense mechanisms and object relations.

PubMed

Juni, Samuel; Gross, Julie; Sokolowska, Joanna

2006-06-01

This study examined relationships between academic cheating behaviors by using self-reports of past cheating behavior, providing a situational experiment with the opportunity to cheat, and evaluating defense mechanisms and object relations as measured by the Defense Mechanisms Inventory. Subjects included 75 female and 8 male university students ranging in age from 18 to 51 years (M=25.5, SD=6.9). Analysis showed variations in students' self-reported cheating history relative to their measured object relations status and type of defense mechanisms. Actual cheating in the experimental setting was not significantly related to any of these variables. Findings are discussed based on a critique of heterogeneity of the cheating construct.

Mechanisms for achieving adolescent-friendly services in Ecuador: a realist evaluation approach

PubMed Central

Goicolea, Isabel; Coe, Anna-Britt; Hurtig, Anna-Karin; San Sebastian, Miguel

2012-01-01

Background Despite evidence showing that adolescent-friendly health services (AFSs) increase young people's access to these services, health systems across the world are failing to integrate this approach. In Latin America, policies aimed at strengthening AFS abound. However, such services are offered only in a limited number of sites, and providers’ attitudes and respect for confidentiality have not been addressed to a sufficient extent. Methods The aim of this study was to explore the mechanisms that triggered the transformation of an ‘ordinary’ health care facility into an AFS in Ecuador. For this purpose, a realist evaluation approach was used in order to analyse three well-functioning AFSs. Information was gathered at the national level and from each of the settings including: (i) statistical information and unpublished reports; (ii) in-depth interviews and focus group discussions with policy makers, health care providers, users and adolescents participating in youth organisations and (iii) observations at the health care facilities. Thematic analysis was carried out, driven by the realist evaluation approach, namely exploring the connections between mechanisms, contexts and outcomes. Results The results highlighted that the development of the AFSs was mediated by four mechanisms: grounded self-confidence in trying new things, legitimacy, a transformative process and an integral approach to adolescents. Along this process, contextual factors at the national and institutional levels were further explored. Conclusion The Ministry of Health of Ecuador, based on the New Guidelines for Comprehensive Care of Adolescent Health, has started the scaling up of AFSs. Our research points towards the need to recognise and incorporate these mechanisms as part of the implementation strategy from the very beginning of the process. Although contextually limited to Ecuador, many mechanisms and good practices in these AFS may be relevant to the Latin American setting and elsewhere. PMID:22855646

Effect of different aging methods on the mechanical behavior of multi-layered ceramic structures.

PubMed

Borba, Márcia; de Araújo, Maico D; Fukushima, Karen A; Yoshimura, Humberto N; Griggs, Jason A; Della Bona, Álvaro; Cesar, Paulo F

2016-12-01

To evaluate the effect of two aging methods (mechanical cycling and autoclave) on the mechanical behavior of veneer and framework ceramic specimens with different configurations (monolithic, two and three-layers). Three ceramics used as framework for fixed dental prostheses (YZ-Vita In-Ceram YZ; IZ-Vita In-Ceram Zirconia; AL-Vita In-Ceram AL) and two veneering porcelains (VM7 and VM9) were studied. Bar-shaped specimens were produced in three different designs: monolithic, two layers (porcelain-framework) and three layers (porcelain-framework-porcelain). Specimens were tested for three-point flexural strength at 1MPa/s in 37°C artificial saliva. Three different experimental conditions were evaluated (n=10): control; mechanical cycling (2Hz, 37°C artificial saliva); and autoclave aging (134°C, 2 bars, 5h). Bi-layered specimens were tested in both conditions: with porcelain or framework ceramic under tension. Fracture surfaces were analyzed using stereomicroscope and scanning electron microscopy. Results were statistically analyzed using Kruskal-Wallis and Student-Newman-Keuls tests. Only for AL group, mechanical cycling and autoclave aging significantly decreased the flexural strength values in comparison to the control (p<0.01). YZ, AL, VM7 and VM9 monolithic groups showed no strength degradation. For multi-layered specimens, when the porcelain layer was tested in tension (bi and tri-layers), the aging methods evaluated also had no effect on strength (p≥0.05). Total and partial failure modes were identified. Mechanical cycling and autoclave aging protocols had no effect on the flexural strength values and failure behavior of YZ and IZ ceramic structures. Yet, AL monolithic structures showed a significant decrease in flexural strength with any of the aging methods. Copyright © 2016. Published by Elsevier Ltd.

Analysis of Complaints from Patients During Mechanical Ventilation After Cardiac Surgery: A Retrospective Study.

PubMed

Wang, Yi; Li, Hua; Zou, Honglin; Li, Yaxiong

2015-08-01

This study analyzed major complaints from patients during mechanical ventilation after cardiac surgery and identified the most common complaints to reduce adverse psychologic responses. Retrospective. A single tertiary university hospital. Patients with heart disease who were on mechanical ventilation after cardiac surgery (N = 800). The major complaints of the patients during mechanical ventilation after cardiac surgery were analyzed. Patients' comfort was evaluated using a visual analog scale, and the factors affecting comfort were analyzed. The average visual analog scale score in all patients was 5.8±2.0, and most patients presented moderate discomfort. The factors affecting comfort included dry mouth, thirst, tracheal intubation, aspiration of sputum, communication barriers, limited mobility, fear/anxiety, patient-ventilator dyssynchrony, and poor environmental conditions. Of these factors, 8 were independent predictors of the visual analog scale score. Patients considered mechanical ventilation to be the worst part of their hospitalization. The study identified 8 independent factors causing discomfort in patients during mechanical ventilation after cardiac surgery. Clinicians should take appropriate measures and implement nursing interventions to reduce suffering, physical and psychologic trauma, and adverse psychologic responses and to promote recovery. Copyright © 2015 Elsevier Inc. All rights reserved.

Effect of Surfactants on Mechanical, Thermal, and Photostability of a Monoclonal Antibody.

PubMed

Agarkhed, Meera; O'Dell, Courtney; Hsieh, Ming-Ching; Zhang, Jingming; Goldstein, Joel; Srivastava, Arvind

2018-01-01

The purpose of this work was to evaluate the effect of commonly used surfactants (at 0.01% w/v concentration) on mechanical, thermal, and photostability of a monoclonal antibody (MAb1) of IgG1 sub-class and to evaluate the minimum concentration of surfactant (Polysorbate 80) required in protecting MAb1 from mechanical stress. Surfactants evaluated were non-ionic surfactants, Polysorbate 80, Polysorbate 20, Pluronic F-68 (polyoxyethylene-polyoxypropylene block polymer), Brij 35 (polyoxyethylene lauryl ether), Triton X-100, and an anionic surfactant, Caprylic acid (1-Heptanecarboxylic acid). After evaluating effect of surfactants and determining stabilizing effect of Polysorbate 80 against mechanical stress without compromising thermal and photostability of MAb1, the minimum concentration of Polysorbate 80 required for mechanical stability was further examined. Polysorbate 80 concentration was varied from 0 to 0.02%. Mechanical stability was evaluated by agitation of MAb1 at 300 rotations per minute at room temperature for 72 h. Samples were analyzed for purity by SEC-HPLC, turbidity by absorbance at 350 nm, visible particles by visual inspection, and sub-visible particles by light obscuration technique on a particle analyzer. All non-ionic surfactants tested showed a similar effect in protecting against mechanical stress and did not exhibit any significant negative effect on thermal and photostability. However, Caprylic acid had a slightly negative effect on mechanical and photostability when compared to the non-ionic surfactants or sample without surfactant. This work demonstrated that polysorbate 80 is better than other surfactants tested and that a concentration of at least 0.005% (w/v) Polysorbate 80 is needed to protect MAb1 against mechanical stress.

COUPLED IRON CORROSION AND CHROMATE REDUCTION: MECHANISMS FOR SUBSURFACE REMEDIATION

EPA Science Inventory

The reduction of chromium from the Cr(VI) to the Cr- (Ill) state by the presence of elemental, or zero-oxidation-state, iron metal was studied to evaluate the feasibility of such a process for subsurface chromate remediation. Reactions were studied in systems of natural aquifer m...

Green tea polyphenols attenuate deterioration of bone microarchitecture in female rats with systemic chronic inflammation

USDA-ARS?s Scientific Manuscript database

Introduction: Our previous study demonstrated that green tea polyphenols (GTP) benefit bone health in female rats with chronic inflammation, because of GTP’s antioxidant capacity. The current study further evaluates whether GTP can restore bone microstructure along with related mechanism in rats wit...

An Improvement in Instructional Quality: Can Evaluation of Teaching Effectiveness Make a Difference?

ERIC Educational Resources Information Center

Ngware, Moses Waithanji; Ndirangu, Mwangi

2005-01-01

Purpose: To report study findings on teaching effectiveness and feedback mechanisms in Kenyan universities, which can guide management in developing a comprehensive quality control policy. Design/methodology/approach: The study adopted an exploratory descriptive design. Three public and two private universities were randomly selected to…

In silico simulation and in vitro evaluation of an elastomeric scaffold using ultrasonic shear wave imaging

NASA Astrophysics Data System (ADS)

Yu, Jiao; Nie, Erwei; Zhu, Yanying; Hong, Yi

2018-03-01

Biodegradable elastomeric scaffolds for soft tissue repair represent a growing area of biomaterials research. Mechanical strength is one of the key factors to consider in the evaluation of candidate materials and the designs for tissue scaffolds. It is desirable to develop non-invasive evaluation methods of the mechanical property of scaffolds which would provide options for monitoring temporal mechanical property changes in situ. In this paper, we conduct in silico simulation and in vitro evaluation of an elastomeric scaffold using a novel ultrasonic shear wave imaging (USWI). The scaffold is fabricated from a biodegradable elastomer, poly(carbonate urethane) urea using salt leaching method. A numerical simulation is performed to test the robustness of the developed inversion algorithm for the elasticity map reconstruction which will be implemented in the phantom experiment. The generation and propagation of shear waves in a homogeneous tissue-mimicking medium with a circular scaffold inclusion is simulated and the elasticity map is well reconstructed. A PVA phantom experiment is performed to test the ability of USWI combined with the inversion algorithm to non-invasively characterize the mechanical property of a porous, biodegradable elastomeric scaffold. The elastic properties of the tested scaffold can be easily differentiated from the surrounding medium in the reconstructed image. The ability of the developed method to identify the edge of the scaffold and characterize the elasticity distribution is demonstrated. Preliminary results in this pilot study support the idea of applying the USWI based method for non-invasive elasticity characterization of tissue scaffolds.

Effect of Heat Treatment on Some Mechanical Properties of Laminated Window Profiles Manufactured Using Two Types of Adhesives

PubMed Central

Korkut, Derya Sevim; Korkutand, Suleyman; Dilik, Tuncer

2008-01-01

The mechanical properties of laminated window profiles manufactured using two types of adhesives were determined. The objective of this study is to evaluate the effects of heat treatment on some mechanical properties of laminated window profiles that manufactured from Kosipo (Entandrophragma candollei Harms.) using differenet type adhesives. Commercially produced polyurethane based Macroplast UR 7221 and polyvinyl acetate (PVAc) adhesive were used for experiments. The overall test results were found to be comparable to those obtained in the previous studies. Both types of adhesives resulted in significant differences in their strength characteristics at 95% confidence level. Adhesive UR 7221 improved the overall properties of the samples in contrast to PVAc. PMID:19325761

Study on the early warning mechanism for the security of blast furnace hearths

NASA Astrophysics Data System (ADS)

Zhao, Hong-bo; Huo, Shou-feng; Cheng, Shu-sen

2013-04-01

The campaign life of blast furnace (BF) hearths has become the limiting factor for safety and high efficiency production of modern BFs. However, the early warning mechanism of hearth security has not been clear. In this article, based on heat transfer calculations, heat flux and erosion monitoring, the features of heat flux and erosion were analyzed and compared among different types of hearths. The primary detecting elements, mathematical models, evaluating standards, and warning methods were discussed. A novel early warning mechanism with the three-level quantificational standards was proposed for BF hearth security.

Cemented fixation with PMMA or Bis-GMA resin hydroxyapatite cement: effect of implant surface roughness.

PubMed

Walsh, W R; Svehla, M J; Russell, J; Saito, M; Nakashima, T; Gillies, R M; Bruce, W; Hori, R

2004-09-01

Implant surface roughness is an important parameter governing the overall mechanical properties at the implant-cement interface. This study investigated the influence of surface roughness using polymethylmethcrylate (PMMA) and a Bisphenol-a-glycidylmethacyrlate resin-hydroxyapatite cement (CAP). Mechanical fixation at the implant-cement interface was evaluated in vitro using static shear and fatigue loading with cobalt chrome alloy (CoCr) dowels with different surface roughness preparations. Increasing surface roughness improved the mechanical properties at the implant-cement interface for both types of cement. CAP cement fixation was superior to PMMA under static and dynamic loading.

Mechanistic Study of Nickel-Catalyzed Ynal Reductive Cyclizations Through Kinetic Analysis

PubMed Central

Baxter, Ryan D.; Montgomery, John

2011-01-01

The mechanism of nickel-catalyzed, silane-mediated reductive cyclization of ynals has been evaluated. The cyclizations are first-order in [Ni] and [ynal] and zeroth-order in [silane]. These results, in combination with the lack of rapid silane consumption upon reaction initiation are inconsistent with mechanisms involving reaction initiation by oxidative addition of Ni(0) to the silane. Silane consumption occurs only when both the alkyne and aldehyde and are present. Mechanisms involving rate-determining oxidative cyclization to a metallacycle followed by rapid reaction with the silane are consistent with the data obtained. PMID:21438642

Identifying psychotic defenses in a clinical interview.

PubMed

Berney, Sylvie; de Roten, Yves; Beretta, Véronique; Kramer, Ueli; Despland, Jean-Nicolas

2014-05-01

The Defense Mechanisms Rating Scales (DMRS), one of the most widely used and validated instruments in the study of defense mechanisms, does not include psychotic defenses. The Psychotic-DMRS (P-DMRS) has been developed to include 6 psychotic defense mechanisms: psychotic denial, autistic withdrawal, distortion, delusional projection, fragmentation, and concretization. We discuss psychotic defenses, including the difference between psychotic defenses and psychotic symptoms. Six clinical illustrations demonstrate how the 6 P-DMRS defenses can be identified in patients' narratives selected from the transcripts of dynamic interviews. Implications with respect to patient evaluation and treatment are discussed. © 2014 Wiley Periodicals, Inc.

Does sunshine prime loyal … or summer? Effects of associative relatedness on the evaluative priming effect in the valent/neutral categorisation task.

PubMed

Werner, Benedikt; von Ramin, Elisabeth; Spruyt, Adriaan; Rothermund, Klaus

2018-02-01

After 30 years of research, the mechanisms underlying the evaluative priming effect are still a topic of debate. In this study, we tested whether the evaluative priming effect can result from (uncontrolled) associative relatedness rather than evaluative congruency. Stimuli that share the same evaluative connotation are more likely to show some degree of non-evaluative associative relatedness than stimuli that have a different evaluative connotation. Therefore, unless associative relatedness is explicitly controlled for, evaluative priming effects reported in earlier research may be driven by associative relatedness instead of evaluative relatedness. To address this possibility, we performed an evaluative priming study in which evaluative congruency and associative relatedness were manipulated independently from each other. The valent/neutral categorisation task was used to ensure evaluative stimulus processing in the absence of response priming effects. Results showed an effect of associative relatedness but no (overall) effect of evaluative congruency. Our findings highlight the importance of controlling for associative relatedness when testing for evaluative priming effects.

The role of chemistry in under-predictions of NO2 in the upper troposphere

NASA Astrophysics Data System (ADS)

Henderson, B. H.; Pinder, R. W.; Goliff, W. S.; Stockwell, W. R.; Fahr, A.; Sarwar, G.; Hutzell, W. T.; Mathur, R.; Vizuete, W.; Cohen, R. C.

2009-12-01

Global and regional atmospheric models under-predict upper troposphere NO2 compared to satellite and aircraft observations. The upper tropospheric under-prediction of NO2 could be a function of emissions, transport, chemistry or some combination. Previous researchers have linked poor performance in the model to over-prediction of the OH and under-prediction of the HO2 by chemistry (Olson et al. 2006, Bertram et al. 2007). This study isolates upper tropospheric chemistry to evaluate the chemical contribution to NO2 under-predictions and to diagnose OH and HO2 discrepancies.

We use a 0-dimensional time dependent model to evaluate seven chemical mechanisms. Because chamber data representing upper tropospheric conditions does not exist, we evaluate the predictions based against an observation-based aging model. Following Bertram et al (2007), we use the NOx:HNO3 ratio to categorize the chemical age of thousands of 10 second average observations between 8 and 10km. Measurements of 10 inorganics and 32 hydrocarbons are translated to model species for each of seven chemical mechanisms. We chose mechanisms ranging from condensed to semi-explicit. The seven mechanisms' design scopes range from urban to global scale. Results include simulations from Model for OZone And Related chemical Tracers (MOZART), Carbon Bond 05 (CB05), State Air Pollution Research Center (SAPRC) 99, SAPRC 07, GEOS-Chem, Regional Atmospheric Chemical Mechanism version 2, and the LEEDS Master Chemical Mechanism.

Results from each chemical mechanism are compared to aircraft observations and to those obtained with other chemical mechanisms. Each mechanism is then further evaluated using integrated reaction rate analysis to identify sources of NO2 bias. We find that the largest contributors to the NO2 bias are over-predictions of PAN and HNO3. The formation of PAN is sensitive to the acetone photolysis rate. The conversion of NOx to HNO3 is most sensitive to hydroxyl radical concentrations. Hydroxyl radical sources and sinks have been quantified for each chemical mechanism using IRR analysis. Based on our modeling experience and results, we make recommendations for better simulating upper tropospheric photochemistry and we identify future research needs.

Bertram et al. Direct Measurements of the Convective Recycling of the Upper Troposphere. Science (2007)
Olson et al. A reevaluation of airborne HOx observations from NASA field campaigns. J Geophys Res-Atmos (2006) vol. 111 pp. D10301

Evaluation of the Etiologies of Implant Fracture in Patients With Fractures of the Implants of Lower Limbs’ Long Bones

PubMed Central

Yeganeh, Ali; Otoukesh, Babak; Kaghazian, Peyman; Yeganeh, Nima; Boddohi, Bahram; Moghtadaei, Mehdi

2015-01-01

Background: Orthopedics implants are important tools for treatment of bone fractures. Despite available recommendations for designing and making the implants, there are multiple cases of fracture of these implants in the body. Hence, in this study the frequency of failure of implants in long bones of lower extremities was evaluated. Methods and Materials: In this cross-sectional study, two types of fractured implants in the body were analyzed and underwent metalogical, mechanical, and modeling and stress-bending analysis. Results: The results revealed that the main cause of fractures was decreased mechanical resistance due to inappropriate chemical composition (especially decreased percentages of Nickel and Molybdenum). Conclusions: It may be concluded that following the standard chemical composition and use of optimal making method are the most important works for prevention of failure of implants. PMID:26843735

Ethanolic extract of Piper betle Linn. leaves reduces nociception via modulation of arachidonic acid pathway.

PubMed

De, Soumita; Maroo, Niteeka; Saha, Piu; Hazra, Samik; Chatterjee, Mitali

2013-01-01

The objective of this study was to evaluate the peripheral analgesic effect of Piper betle leaf extract (PBE) along with establishing its putative mechanism of action. Male Swiss albino mice after pre-treatment (1 h) with different doses of PBE were injected 0.8% (v/v) acetic acid i.p.; the onset and number of writhes were noted up to 15 min. To evaluate the mechanism of action, the murine peritoneal exudate was incubated with PBE for 1 h, followed by exposure to arachidonic acid (AA) and generation of reactive oxygen species (ROS) was measured by flow cytometry using 2',7'-dichlorodihydrofluorescein diacetate. PBE in a dose dependent manner significantly reduced acetic acid induced writhing response in mice (P < 0.001). In peritoneal exudates, PBE significantly inhibited AA induced generation of ROS, P < 0.01. The present study indicates that PBE has promising analgesic activity, worthy of future pharmacological consideration.

Serum Magnesium after Kidney Transplantation: A Systematic Review.

PubMed

Garnier, Anne-Sophie; Duveau, Agnès; Planchais, Martin; Subra, Jean-François; Sayegh, Johnny; Augusto, Jean-François

2018-06-06

Magnesium (Mg) status has recently drawn close attention in chronic kidney disease and in kidney transplant recipients. This review aims to evaluate the body of evidence linking hypomagnesemia to clinical consequences in these specific populations. After a brief summary of the main mechanisms involved in Mg regulation and of Mg status in end-stage renal disease, the review focuses on the relationship between hypomagnesemia and cardiovascular risk in kidney transplant recipients. A body of evidence in recent studies points to a negative impact of hypomagnesemia on post-transplant diabetes mellitus (PTDM) and cardiovascular risk, which currently represent the main threat for morbidity and mortality in kidney transplantation. Deleterious biological mechanisms induced by hypomagnesemia are also discussed. While data analysis enables us to conclude that hypomagnesemia is linked to the development of PTDM, studies prospectively evaluating the impact of hypomagnesemia correction after kidney transplantation are still lacking and needed.

Configuration study for a 30 GHz monolithic receive array, volume 1

NASA Technical Reports Server (NTRS)

Nester, W. H.; Cleaveland, B.; Edward, B.; Gotkis, S.; Hesserbacker, G.; Loh, J.; Mitchell, B.

1984-01-01

Gregorian, Cassegrain, and single reflector systems were analyzed in configuration studies for communications satellite receive antennas. Parametric design and performance curves were generated. A preliminary design of each reflector/feed system was derived including radiating elements, beam-former network, beamsteering system, and MMIC module architecture. Performance estimates and component requirements were developed for each design. A recommended design was selected for both the scanning beam and the fixed beam case. Detailed design and performance analysis results are presented for the selected Cassegrain configurations. The final design point is characterized in detail and performance measures evaluated in terms of gain, sidelobe level, noise figure, carrier-to-interference ratio, prime power, and beamsteering. The effects of mutual coupling and excitation errors (including phase and amplitude quantization errors) are evaluated. Mechanical assembly drawings are given for the final design point. Thermal design requirements are addressed in the mechanical design.

Precision toxicology based on single cell sequencing: an evolving trend in toxicological evaluations and mechanism exploration.

PubMed

Zhang, Boyang; Huang, Kunlun; Zhu, Liye; Luo, Yunbo; Xu, Wentao

2017-07-01

In this review, we introduce a new concept, precision toxicology: the mode of action of chemical- or drug-induced toxicity can be sensitively and specifically investigated by isolating a small group of cells or even a single cell with typical phenotype of interest followed by a single cell sequencing-based analysis. Precision toxicology can contribute to the better detection of subtle intracellular changes in response to exogenous substrates, and thus help researchers find solutions to control or relieve the toxicological effects that are serious threats to human health. We give examples for single cell isolation and recommend laser capture microdissection for in vivo studies and flow cytometric sorting for in vitro studies. In addition, we introduce the procedures for single cell sequencing and describe the expected application of these techniques to toxicological evaluations and mechanism exploration, which we believe will become a trend in toxicology.

HMSPP nanocomposite and Brazilian bentonite properties after gamma radiation exposure

NASA Astrophysics Data System (ADS)

Fermino, D. M.; Parra, D. F.; Oliani, W. L.; Lugao, A. B.; Díaz, F. R. V.

2013-03-01

This work concerns the study of the mechanical and thermal behavior of the nanocomposite high melt strength polypropylene (HMSPP) (obtained at a dose of 12.5 kGy) and a bentonite clay Brazilian Paraiba (PB), which is known as "chocolate" and is used in concentrations of 5% and 10% by weight, in comparison to the American Cloisite 20A clay nanocomposites. An agent compatibilizer polypropylene-graft (PP-g-AM) was added at a 3% concentration, and the clay was dispersed using the melt intercalation technique using a twin-screw extruder. The specimens were prepared by the injection process. The mechanical behavior was evaluated by strength, flexural strength and impact tests. The thermal behavior was evaluated by the techniques of differential scanning calorimetry (DSC) and thermogravimetry (TGA). The morphology of the nanocomposites was studied with scanning electron microscopy (SEM), while the organophilic bentonite and nanocomposites were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).

On the importance of 3D, geometrically accurate, and subject-specific finite element analysis for evaluation of in-vivo soft tissue loads.

PubMed

Moerman, Kevin M; van Vijven, Marc; Solis, Leandro R; van Haaften, Eline E; Loenen, Arjan C Y; Mushahwar, Vivian K; Oomens, Cees W J

2017-04-01

Pressure ulcers are a type of local soft tissue injury due to sustained mechanical loading and remain a common issue in patient care. People with spinal cord injury (SCI) are especially at risk of pressure ulcers due to impaired mobility and sensory perception. The development of load improving support structures relies on realistic tissue load evaluation e.g. using finite element analysis (FEA). FEA requires realistic subject-specific mechanical properties and geometries. This study focuses on the effect of geometry. MRI is used for the creation of geometrically accurate models of the human buttock for three able-bodied volunteers and three volunteers with SCI. The effect of geometry on observed internal tissue deformations for each subject is studied by comparing FEA findings for equivalent loading conditions. The large variations found between subjects confirms the importance of subject-specific FEA.

Expansion of flight simulator capability for study and solution of aircraft directional control problems on runways

NASA Technical Reports Server (NTRS)

Kibbee, G. W.

1978-01-01

The development, evaluation, and evaluation results of a DC-9-10 runway directional control simulator are described. An existing wide bodied flight simulator was modified to this aircraft configuration. The simulator was structured to use either two of antiskid simulations; (1) an analog mechanization that used aircraft hardware; or (2) a digital software simulation. After the simulation was developed it was evaluated by 14 pilots who made 818 simulated flights. These evaluations involved landings, rejected takeoffs, and various ground maneuvers. Qualitatively most pilots evaluated the simulator as realistic with good potential especially for pilot training for adverse runway conditions.

Neural mechanisms underlying urgent and evaluative behaviors: An fMRI study on the interaction of automatic and controlled processes.

PubMed

Megías, Alberto; Navas, Juan Francisco; Petrova, Dafina; Cándido, Antonio; Maldonado, Antonio; Garcia-Retamero, Rocio; Catena, Andrés

2015-08-01

Dual-process theories have dominated the study of risk perception and risk-taking over the last two decades. However, there is a lack of objective brain-level evidence supporting the two systems of processing in every-day risky behavior. To address this issue, we propose the dissociation between evaluative and urgent behaviors as evidence of dual processing in risky driving situations. Our findings show a dissociation of evaluative and urgent behavior both at the behavioral and neural level. fMRI data showed an increase of activation in areas implicated in motor programming, emotional processing, and visuomotor integration in urgent behavior compared to evaluative behavior. These results support a more automatic processing of risk in urgent tasks, relying mainly on heuristics and experiential appraisal. The urgent task, which is characterized by strong time pressure and the possibility for negative consequences among others factors, creates a suitable context for the experiential-affective system to guide the decision-making process. Moreover, we observed greater frontal activation in the urgent task, suggesting the participation of cognitive control in safe behaviors. The findings of this research are relevant for the study of the neural mechanisms underlying dual process models in risky perception and decision-making, especially because of their proximity to everyday activities. © 2015 Wiley Periodicals, Inc.

Reliability Issues and Solutions in Flexible Electronics Under Mechanical Fatigue

NASA Astrophysics Data System (ADS)

Yi, Seol-Min; Choi, In-Suk; Kim, Byoung-Joon; Joo, Young-Chang

2018-07-01

Flexible devices are of significant interest due to their potential expansion of the application of smart devices into various fields, such as energy harvesting, biological applications and consumer electronics. Due to the mechanically dynamic operations of flexible electronics, their mechanical reliability must be thoroughly investigated to understand their failure mechanisms and lifetimes. Reliability issue caused by bending fatigue, one of the typical operational limitations of flexible electronics, has been studied using various test methodologies; however, electromechanical evaluations which are essential to assess the reliability of electronic devices for flexible applications had not been investigated because the testing method was not established. By employing the in situ bending fatigue test, we has studied the failure mechanism for various conditions and parameters, such as bending strain, fatigue area, film thickness, and lateral dimensions. Moreover, various methods for improving the bending reliability have been developed based on the failure mechanism. Nanostructures such as holes, pores, wires and composites of nanoparticles and nanotubes have been suggested for better reliability. Flexible devices were also investigated to find the potential failures initiated by complex structures under bending fatigue strain. In this review, the recent advances in test methodology, mechanism studies, and practical applications are introduced. Additionally, perspectives including the future advance to stretchable electronics are discussed based on the current achievements in research.

Reliability Issues and Solutions in Flexible Electronics Under Mechanical Fatigue

NASA Astrophysics Data System (ADS)

Yi, Seol-Min; Choi, In-Suk; Kim, Byoung-Joon; Joo, Young-Chang

2018-03-01

Flexible devices are of significant interest due to their potential expansion of the application of smart devices into various fields, such as energy harvesting, biological applications and consumer electronics. Due to the mechanically dynamic operations of flexible electronics, their mechanical reliability must be thoroughly investigated to understand their failure mechanisms and lifetimes. Reliability issue caused by bending fatigue, one of the typical operational limitations of flexible electronics, has been studied using various test methodologies; however, electromechanical evaluations which are essential to assess the reliability of electronic devices for flexible applications had not been investigated because the testing method was not established. By employing the in situ bending fatigue test, we has studied the failure mechanism for various conditions and parameters, such as bending strain, fatigue area, film thickness, and lateral dimensions. Moreover, various methods for improving the bending reliability have been developed based on the failure mechanism. Nanostructures such as holes, pores, wires and composites of nanoparticles and nanotubes have been suggested for better reliability. Flexible devices were also investigated to find the potential failures initiated by complex structures under bending fatigue strain. In this review, the recent advances in test methodology, mechanism studies, and practical applications are introduced. Additionally, perspectives including the future advance to stretchable electronics are discussed based on the current achievements in research.

Index of mechanical work in gait of children with cerebral palsy.

PubMed

Dziuba, Alicja Katarzyna; Tylkowska, Małgorzata; Jaroszczuk, Sebastian

2014-01-01

The pathological gait of children with cerebral palsy involves higher mechanical work, which limits their ability to function properly in society. Mechanical work is directly related to walking speed and, although a number of studies have been carried out in this field, few of them analysed the effect of the speed. The study aimed to develop standards for mechanical work during gait of children with cerebral palsy depending on the walking speed. The study covered 18 children with cerebral palsy and 14 healthy children. The BTS Smart software and the author's software were used to evaluate mechanical work, kinetic, potential and rotational energy connected with motion of the children body during walk. Compared to healthy subjects, mechanical work in children with cerebral palsy increases with the degree of disability. It can be expressed as a linear function of walking speed and shows strong and statistically significant correlations with walking gait. A negative statistically significant correlation between the degree of disability and walking speed can be observed. The highest contribution to the total mechanical energy during gait is from mechanical energy of the feet. Instantaneous value of rotational energy is 700 times lower than the instantaneous mechanical energy. An increase in walking speed causes the increase in the effect of the index of kinetic energy on total mechanical work. The method described can provide an objective supplementation for doctors and physical therapists to perform a simple and immediate diagnosis without much technical knowledge.

Adaptive, Active and Multifunctional Composite and Hybrid Materials Program: Composite and Hybrid Materials ERA

DTIC Science & Technology

2014-04-01

Microvascular Self - Healing Composites Mechanical Evaluation ................................................................................11...Thermoplastic SMP Foam Microstructure- Mechanical Stress-Strain Relationships 2.2.2 Microvascular Self - Healing Composites Mechanical Evaluation 2.3.1 Z...materials, and embedded sensory and circulatory systems. Damage repair of torn or injured tissue was demonstrated by the use of self - healing polymer

NO—CO—O2 Reaction on a Metal Catalytic Surface using Eley—Rideal Mechanism

NASA Astrophysics Data System (ADS)

Waqar, Ahmad

2008-10-01

Interactions among the reacting species NO, CO and O2 on metal catalytic surfaces are studied by means of Monte Carlo simulation using the Eley-Rideal (ER) mechanism. The study of this three-component system is important for understanding of the reaction kinetics by varying the relative ratios of the reactants. It is found that contrary to the conventional Langmuir-Hinshelwood (LH) thermal mechanism in which two irreversible phase transitions are obtained between active states and poisoned states, a single phase transition is observed when the ER mechanism is combined with the LH mechanism. The phase diagrams of the surface coverage and the steady state production of CO2, N2 and N2 O are evaluated as a function of the partial pressures of the reactants in the gas phase. The continuous production of CO2 starts as soon as the CO pressure is switched on and the second order phase transition at the first critical point is eliminated, which is in agreement with the experimental findings.

Wood plastic composites from agro-waste materials: Analysis of mechanical properties.

PubMed

Nourbakhsh, Amir; Ashori, Alireza

2010-04-01

This article presents the application of agro-waste materials (i.e., corn stalk, reed stalk, and oilseed stalk) in order to evaluate and compare their suitability as reinforcement for thermoplastics as an alternative to wood fibers. The effects of fiber loading and CaCO(3) content on the mechanical properties were also studied. Overall trend shows that with addition of agro-waste materials, tensile and flexural properties of the composites are significantly enhanced. Oilseed fibers showed superior mechanical properties due to their high aspect ratio and chemical characteristics. The order of increment in the mechanical properties of the composites is oilseed stalk >corn stalk>reed stalk at all fiber loadings. The tensile and flexural properties of the composite significantly decreased with increasing CaCO(3) content, due to the reduction of interface bond between the fiber and matrix. It can be concluded from this study that the used agro-waste materials are attractive reinforcements from the standpoint of their mechanical properties. Copyright 2009 Elsevier Ltd. All rights reserved.

Formability of a wrought Mg alloy evaluated by impression testing

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

Mohamed, Walid; Gollapudi, Srikant; Charit, Indrajit

This study is focused on furthering our understanding of the different factors that influence the formability of Magnesium alloys. Towards this end, formability studies were undertaken on a wrought Mg-2Zn-1Mn (ZM21) alloy. In contrast to conventional formability studies, the impression testing method was adopted here to evaluate the formability parameter, B, at temperatures ranging from 298 to 473 K. The variation of B of ZM21 with temperature and its rather limited values were discussed in the light of different deformation mechanisms such as activation of twinning, slip, grain boundary sliding (GBS) and dynamic recrystallization (DRX). It was found that themore » material characteristics such as grain size, texture and testing conditions such as temperature and strain rate, were key determinants of the mechanism of plastic deformation. A by-product of this analysis was the observation of an interesting correlation between the Zener-Hollomon parameter, Z, and the ability of Mg alloys to undergo DRX.« less

Assembly of Space CFRP Structures with Racing Sailing Boats Technology

NASA Astrophysics Data System (ADS)

Nieto, Jose; Yuste, Laura; Pipo, Alvaro; Santarsiero, Pablo; Bureo, Rafael

2014-06-01

Carbon Fiber Reinforced Plastic (CFRP) is commonly used in space applications to get structures with good mechanical performances and a reduced mass. Most of larger parts of spatial structures are already made of CFRP but the achieved weight saving may be jeopardized by the use of metallic brackets as joining elements. This paper describes the work carried out to study and evaluate ways of reducing weight and costs of the joints between structural elements commonly used in space applications.The main objective of this project is to adapt design solutions coming from the racing sailing boats technology to space applications: the use of out-of autoclave (OoA) cured CFRP joints. In addition to that other CFRP solution common in space business, 3D- RTM Bracket, has been evaluated.This development studies the manufacturing and assembly feasibility making use of these CFRP technologies.This study also compares traditional metallic solutions with innovative CFRP ones in terms of mechanical performances at elementary level. Weight and cost of presented solutions are also compared.

Mechanical phenotyping of cells and extracellular matrix as grade and stage markers of lung tumor tissues.

PubMed

Panzetta, Valeria; Musella, Ida; Rapa, Ida; Volante, Marco; Netti, Paolo A; Fusco, Sabato

2017-07-15

The mechanical cross-talk between cells and the extra-cellular matrix (ECM) regulates the properties, functions and healthiness of the tissues. When this is disturbed it changes the mechanical state of the tissue components, singularly or together, and cancer, along with other diseases, may start and progress. However, the bi-univocal mechanical interplay between cells and the ECM is still not properly understood. In this study we show how a microrheology technique gives us the opportunity to evaluate the mechanics of cells and the ECM at the same time. The mechanical phenotyping was performed on the surgically removed tissues of 10 patients affected by adenocarcinoma of the lung. A correlation between the mechanics and the grade and stage of the tumor was reported and compared to the mechanical characteristics of the healthy tissue. Our findings suggest a sort of asymmetric modification of the mechanical properties of the cells and the extra-cellular matrix in the tumor, being the more compliant cell even though it resides in a stiffer matrix. Overall, the simultaneous mechanical characterization of the tissues constituents (cells and ECM) provided new support for diagnosis and offered alternative points of analysis for cancer mechanobiology. When the integrity of the mechanical cross-talk between cells and the extra-cellular matrix is disturbed cancer, along with other diseases, may initiate and progress. Here, we show how a new technique gives the opportunity to evaluate the mechanics of cells and the ECM at the same time. It was applied on surgically removed tissues of 10 patients affected by adenocarcinoma of the lung and a correlation between the mechanics and the grade and stage of the tumor was reported and compared to the mechanical characteristics of the healthy tissue. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Kenaf/PP and EFB/PP: Effect of fibre loading on the mechanical properties of polypropylene composites

NASA Astrophysics Data System (ADS)

Anuar, N. I. S.; Zakaria, S.; Harun, J.; Wang, C.

2017-07-01

Kenaf and empty fruit bunch (EFB) fibre which are the important natural fibres in Malaysia were studied as nonwoven polymer composites. The effect of fibre loading on kenaf polypropylene and EFB polypropylene nonwoven composite was studied at different mixture ratio. Kenaf polypropylene nonwoven composite (KPNC) and EFB polypropylene nonwoven composite (EPNC) were prepared by carding and needle-punching techniques, followed by a compression moulding at 6 mm thickness. This study was conducted to identify the optimum fibre loading of nonwoven polypropylene composite and their effect on the mechanical strength. The study was designed at 40%, 50%, 60% and 70% of fibre content in nonwoven mat and composite. The tensile strength, flexural strength and compression strength were tested to evaluate the composite mechanical properties. It was found that the mechanical properties for both kenaf and EFB nonwoven composites were influenced by the fibre content. KPNC showed higher mechanical strength than EPNC. The highest flexural strength was obtained at 60% KPNC and the lowest value was showed by 40% EPNC. The tensile and flexural strength for both KPNC and EPNC decreased after the fibre loading of 60%.

First-principles investigation of mechanical properties of silicene, germanene and stanene

NASA Astrophysics Data System (ADS)

Mortazavi, Bohayra; Rahaman, Obaidur; Makaremi, Meysam; Dianat, Arezoo; Cuniberti, Gianaurelio; Rabczuk, Timon

2017-03-01

Two-dimensional allotropes of group-IV substrates including silicene, germanene and stanene have recently attracted considerable attention in nanodevice fabrication industry. These materials involving the buckled structure have been experimentally fabricated lately. In this study, first-principles density functional theory calculations were utilized to investigate the mechanical properties of single-layer and free-standing silicene, germanene and stanene. Uniaxial tensile and compressive simulations were carried out to probe and compare stress-strain properties; such as the Young's modulus, Poisson's ratio and ultimate strength. We evaluated the chirality effect on the mechanical response and bond structure of the 2D substrates. Our first-principles simulations suggest that in all studied samples application of uniaxial loading can alter the electronic nature of the buckled structures into the metallic character. Our investigation provides a general but also useful viewpoint with respect to the mechanical properties of silicene, germanene and stanene.

A Micro-Mechanism-Based Continuum Corrosion Fatigue Damage Model for Steels

NASA Astrophysics Data System (ADS)

Sun, Bin; Li, Zhaoxia

2018-05-01

A micro-mechanism-based corrosion fatigue damage model is developed for studying the high-cycle corrosion fatigue of steel from multi-scale viewpoint. The developed physical corrosion fatigue damage model establishes micro-macro relationships between macroscopic continuum damage evolution and collective evolution behavior of microscopic pits and cracks, which can be used to describe the multi-scale corrosion fatigue process of steel. As a case study, the model is used to predict continuum damage evolution and number density of the corrosion pit and short crack of steel component in 5% NaCl water under constant stress amplitude at 20 kHz, and the numerical results are compared with experimental results. It shows that the model is effective and can be used to evaluate the continuum macroscopic corrosion fatigue damage and study microscopic corrosion fatigue mechanisms of steel.

A Micro-Mechanism-Based Continuum Corrosion Fatigue Damage Model for Steels

NASA Astrophysics Data System (ADS)

Sun, Bin; Li, Zhaoxia

2018-04-01

A micro-mechanism-based corrosion fatigue damage model is developed for studying the high-cycle corrosion fatigue of steel from multi-scale viewpoint. The developed physical corrosion fatigue damage model establishes micro-macro relationships between macroscopic continuum damage evolution and collective evolution behavior of microscopic pits and cracks, which can be used to describe the multi-scale corrosion fatigue process of steel. As a case study, the model is used to predict continuum damage evolution and number density of the corrosion pit and short crack of steel component in 5% NaCl water under constant stress amplitude at 20 kHz, and the numerical results are compared with experimental results. It shows that the model is effective and can be used to evaluate the continuum macroscopic corrosion fatigue damage and study microscopic corrosion fatigue mechanisms of steel.

Gender differences in defense mechanisms, ways of coping with stress and sense of identity in adolescent suicide attempts.

PubMed

Foto-Özdemir, Dilşad; Akdemir, Devrim; Çuhadaroğlu-Çetin, Füsun

2016-01-01

The main aim of this study was to investigate the gender differences in defense mechanisms, ways of coping with stress and identity formation in relation to adolescent suicidal behavior. This study involved 64 adolescents between 12-17 years of age, who were admitted to the emergency service with a suicide attempt. They were evaluated with a semi-structured clinical interview (K-SADS), Ways of Coping Inventory (WCI), Defense Mechanisms Inventory (DMI) and Sense of Identity Assessment Form (SIAF). 60.9% (n = 39) of the adolescents were female, and 39.1% (n=25) were male. There were no statistically significant differences between the girls and the boys with respect to the clinical characteristics of the suicide attempt and the rate of psychiatric disorders. Of the 64 adolescents with suicide attempt, 47 (73.4%) had at least one, and 26 (40.6%) had more than one psychiatric disorder according to K-SADS. Disruptive behavior disorders were more frequent in males, whereas depression was more frequent in girls. The data indicated the importance of identity confusion, major depression and ADHD in adolescents with suicide attempt in both genders. 43.6% (n=17) of the girls and 36% (n=9) of the boys obtained scores higher than the cut-off point of SIAF indicating identity confusion. Professional help seeking and NSSI behaviors before the suicide attempt were more common in adolescents with identity confusion. While there were differences between genders with respect to the defense mechanisms used, no significant difference was found in terms of ways of coping. Evaluation of DMI scores revealed that the turning against object subscale score was significantly higher in boys compared to girls. While evaluating the adolescents at risk, their defense mechanisms, way of coping and sense of identity, as well as their psychiatric diagnosis should be assessed in detail in order to identify the suicidal thoughts and prevent possible suicide attempts.

Use of genomic data in risk assessment case study: II. Evaluation of the dibutyl phthalate toxicogenomic data set

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

Euling, Susan Y., E-mail: euling.susan@epa.gov; White, Lori D.; Kim, Andrea S.

An evaluation of the toxicogenomic data set for dibutyl phthalate (DBP) and male reproductive developmental effects was performed as part of a larger case study to test an approach for incorporating genomic data in risk assessment. The DBP toxicogenomic data set is composed of nine in vivo studies from the published literature that exposed rats to DBP during gestation and evaluated gene expression changes in testes or Wolffian ducts of male fetuses. The exercise focused on qualitative evaluation, based on a lack of available dose–response data, of the DBP toxicogenomic data set to postulate modes and mechanisms of action formore » the male reproductive developmental outcomes, which occur in the lower dose range. A weight-of-evidence evaluation was performed on the eight DBP toxicogenomic studies of the rat testis at the gene and pathway levels. The results showed relatively strong evidence of DBP-induced downregulation of genes in the steroidogenesis pathway and lipid/sterol/cholesterol transport pathway as well as effects on immediate early gene/growth/differentiation, transcription, peroxisome proliferator-activated receptor signaling and apoptosis pathways in the testis. Since two established modes of action (MOAs), reduced fetal testicular testosterone production and Insl3 gene expression, explain some but not all of the testis effects observed in rats after in utero DBP exposure, other MOAs are likely to be operative. A reanalysis of one DBP microarray study identified additional pathways within cell signaling, metabolism, hormone, disease, and cell adhesion biological processes. These putative new pathways may be associated with DBP effects on the testes that are currently unexplained. This case study on DBP identified data gaps and research needs for the use of toxicogenomic data in risk assessment. Furthermore, this study demonstrated an approach for evaluating toxicogenomic data in human health risk assessment that could be applied to future chemicals. - Highlights: ► We evaluate the dibutyl phthalate toxicogenomic data for use in risk assessment. ► We focus on information about the mechanism of action for the developing testis. ► Multiple studies report effects on testosterone and insl3-related pathways. ► We identify additional affected pathways that may explain some testis effects. ► The case study is a template for evaluating toxicogenomic data in risk assessment.« less

Radiolabeling of Cramoll 1,4: Evaluation of the Biodistribution

PubMed Central

Ferreira de Carvalho Patricio, Beatriz; Lima-Ribeiro, Maria Helena Madruga; Correia, Maria Tereza dos Santos; Carneiro-Leão, Ana Maria dos Anjos; Albernaz, Marta de Souza; Barboza, Thiago; de Souza, Sergio Augusto Lopes; Santos-Oliveira, Ralph

2011-01-01

The cramoll 1,4 is a well-studied lectin. However, few studies about its biodistribution have been done before. In this study, we radiolabeled the cramol 1,4 with Tc-99m and analyzed the biodistribution. The results showed that the cramol has an abnormal uptake by the bowel with reflections on its clearance mechanism. PMID:21760823

On the Generation and Use of TCP Acknowledgments

NASA Technical Reports Server (NTRS)

Allman, Mark

1998-01-01

This paper presents a simulation study of various TCP acknowledgment generation and utilization techniques. We investigate the standard version of TCP and the two standard acknowledgment strategies employed by receivers: those that acknowledge each incoming segment and those that implement delayed acknowledgments. We show the delayed acknowledgment mechanism hurts TCP performance, especially during slow start. Next we examine three alternate mechanisms for generating and using acknowledgments designed to mitigate the negative impact of delayed acknowledgments. The first method is to generate delayed ACKs only when the sender is not using the slow start algorithm. The second mechanism, called byte counting, allows TCP senders to increase the amount of data being injected into the network based on the amount of data acknowledged rather than on the number of acknowledgments received. The last mechanism is a limited form of byte counting. Each of these mechanisms is evaluated in a simulated network with no competing traffic, as well as a dynamic environment with a varying amount of competing traffic. We study the costs and benefits of the alternate mechanisms when compared to the standard algorithm with delayed ACKs.

(1)H NMR-based metabonomics revealed protective effect of Naodesheng bioactive extract on ischemic stroke rats.

PubMed

Luo, Lan; Zhen, Lifeng; Xu, Yatao; Yang, Yongxia; Feng, Suxiang; Wang, Shumei; Liang, Shengwang

2016-06-20

Stroke is a leading cause of death and disability in the world. However, current therapies are limited. Naodesheng, a widely used traditional Chinese medicine prescription, has shown a good clinical curative effect on ischemic stroke. Also, Naodesheng has been suggested to have neuroprotective effect on focal cerebral ischemia rats, but the underlying molecular mechanism remains unclear. The present study was designed to evaluate the effect of Naodesheng bioactive extract on the metabolic changes in brain tissue, plasma and urine induced by cerebral ischemia perfusion injury, and explore the possible metabolic mechanisms by using a (1)H NMR-based metabonomics approach. A middle cerebral artery occlusion rat model was established and confirmed by the experiments of neurobehavioral abnormality evaluation, brain tissue TTC staining and pathological examination. The metabolic changes in brain tissue, plasma and urine were then assessed by a (1)H NMR technique combined with multivariate statistical analysis method. These NMR data showed that cerebral ischemia reperfusion induced great metabolic disorders in brain tissue, plasma and urine metabolisms. However, Naodesheng bioactive extract could reverse most of the imbalanced metabolites. Meanwhile, it was found that both the medium and high dosages of Naodesheng bioactive extract were more effective on the metabolic changes than the low dosage, consistent with histopathological assessments. These results revealed that Naodesheng had protective effect on ischemic stroke rats and the underlying mechanisms involved multiple metabolic pathways, including energy metabolism, amino acid metabolism, oxidative stress and inflammatory injury. The present study could provide evidence that metabonomics revealed its capacity to evaluate the holistic efficacy of traditional Chinese medicine and explore the underlying mechanisms. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Interaction of arch type and footwear on running mechanics.

PubMed

Butler, Robert J; Davis, Irene S; Hamill, Joseph

2006-12-01

Running shoes are designed to accommodate various arch types to reduce the risk of lower extremity injuries sustained during running. Yet little is known about the biomechanical changes of running in the recommended footwear that may allow for a reduction in injuries. To evaluate the effects of motion control and cushion trainer shoes on running mechanics in low- and high-arched runners. Controlled laboratory study. Twenty high-arched and 20 low-arched recreational runners (>10 miles per week) were recruited for the study. Three-dimensional kinematic and kinetics were collected as subjects ran at 3.5 ms(-1) +/- 5% along a 25-m runway. The motion control shoe evaluated was the New Balance 1122, and the cushioning shoe evaluated was the New Balance 1022. Repeated-measures analyses of variance were used to determine if low- and high-arched runners responded differently to motion control and cushion trainer shoes. A significant interaction was observed in the instantaneous loading rate such that the low-arched runners had a lower instantaneous loading rate in the motion control condition, and the high-arched runners had a lower instantaneous loading rate in the cushion trainer condition. Significant main effects for shoe were observed for peak positive tibial acceleration, peak-to-peak tibial acceleration, mean loading rate, peak eversion, and eversion excursion. These results suggest that motion control shoes control rearfoot motion better than do cushion trainer shoes. In addition, cushion trainer shoes attenuate shock better than motion control shoes do. However, with the exception of instantaneous loading rate, these benefits do not differ between arch type. Running footwear recommendations should be based on an individual's running mechanics. If a mechanical analysis is not available, footwear recommendations can be based empirically on the individual's arch type.

SSRI-reduced platelet reactivity in non-responding patients with life-long Recurrent Depressive Disorder: Detection and involved mechanisms.

PubMed

Aleksovski, Boris; Neceva, Violeta; Vujović, Viktorija; Manusheva, Nensi; Rendevski, Vladimir; Novotni, Antoni; Filipce, Ana; Spasovska, Anastazija; Sofijanova, Aspazija; Aleksovski, Vasko; Gjorgoski, Icko

2018-05-01

Adverse effects with bleeding disorders are often associated with the administration of SSRI in depression, although the exact mechanisms remain contradicting. This study is aimed at detecting and exploring the mechanisms of SSRI-induced changes in platelet reactivity in non-responding patients with Recurrent Depressive Disorder (RDD) and life-long exposure to antidepressants. Thirty-one patients and thirty-one healthy controls were included in the study. A comprehensive approach which includes evaluation of peripheral markers and microscopic analyses of platelet morphology changes has been used. RDD SSRI patients have shown blunted aggregatory responses towards collagen and epinephrine. Evident differences in the microscopic evaluation of platelet morphology were observed between the groups, with inherent absence of micro-aggregates and platelet shape changes within the patients; after quantification, the sensitivity and specificity of this method were assessed as high. The abnormalities were found in association with lower platelet serotonin content and high fluctuations of free plasma serotonin levels. Changes in the levels of CRP, fibrinogen and nitric oxide were not observed. Macroplatelets were also detected within RDD SSRI patients via increased MPV, PDW and P-LCR, which were associated with discoid shape and without procoagulant activity. The microscopic evaluation might be useful as a simple method for detection of SSRI-reduced platelet function for research purposes or systematic correlations with other biochemical parameters. The mechanisms involved in SSRI-reduced platelet function in non-responding RDD patients are complex, including combined effects of lower platelet serotonin content, high fluctuations in plasma serotonin concentration and abnormal α-AR function. Copyright © 2018 Elsevier Ltd. All rights reserved.

Development of novel dental nanocomposites reinforced with polyhedral oligomeric silsesquioxane (POSS).

PubMed

Wu, Xiaorong; Sun, Yi; Xie, Weili; Liu, Yanju; Song, Xueyu

2010-05-01

It has been the focus to develop low shrinkage dental composite resins in recent ten years. A major difficulty in developing low shrinkage dental materials is that their deficiency in mechanical properties cannot satisfy the clinical purpose. The aim of this study is to develop novel dental nanocomposites incorporated with polyhedral oligomeric silsesquioxane (POSS). It is especially interesting to evaluate the volumetric shrinkage and mechanical properties, improve the shrinkage, working performances and service life of dental composite resins. The effect of added POSS on the composites' mechanical properties has been evaluated. The weight percentages of added POSS are 0, 2, 5, 10 and 15wt% respectively. Fourier-transform infra-red spectroscopy and X-ray diffraction were used to characterize their microstructures. Physico-mechanical properties that were investigated included volumetric shrinkage, flexural strength, flexural modulus, compressive strength, compressive modulus, Viker's hardness and fracture energy. Furthermore, the possible reinforced mechanism has been discussed. The shrinkage of novel nanocomposites decreased from 3.53% to 2.18%. The nanocomposites incorporated with POSS showed greatly improved mechanical properties, for example, with only 2wt% POSS added, the nanocompsite's flexural strength increased 15%, compressive strength increased 12%, hardness increased 15% and uncommonly, even the toughness of resins was obviously increased. With 5wt% POSS polymerized, compressive strength increased from 192MPa to 251MPa and compressive modulus increased from 3.93GPa to 6.62GPa, but flexure strength began to decline from 87MPa to 75MPa. This finding indicated that the reinforcing mechanism of flexure state maybe different from that of compressive state. The mechanical properties and volumetric shrinkage of dental composite resins polymerized with POSS can be improved significantly. In current study, the nanocomposite with 2wt% POSS incorporated is observed to achieve the best improved effects. 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Mechanical degradation of TiO2 nanotubes with and without nanoparticulate silver coating

PubMed Central

Shivaram, Anish; Bose, Susmita; Bandyopadhyay, Amit

2016-01-01

The primary objective of this research was to evaluate the extent of mechanical degradation on TiO2 nanotubes on Ti with and without nano-particulate silver coating using two different lengths of TiO2 nanotubes- 300nm and ~ 1µm, which were fabricated on commercially pure Titanium (cp-Ti) rods using anodization method using two different electrolytic mediums - (1) deionized (DI) water with 1% HF, and (2) ethylene glycol with 1% HF, 0.5 wt%. NH4F and 10% DI water. Nanotubes fabricated rods were implanted into equine cadaver bone to evaluate mechanical damage at the surface. Silver was electrochemically deposited on these nanotubes and using a release study, silver ion concentrations were measured before and after implantation, followed by surface characterization using a Field Emission Scanning Electron Microscope (FESEM). In vitro cell-material interaction study was performed using human fetal osteoblast cells (hFOB) to understand the effect of silver coating using an MTT assay for proliferation and to determine any cytotoxic effect on the cells and to study its biocompatibility. No significant damage due to implantation was observed for nanotubes up to ~1 µm length under current experimental conditions. Cell-materials interaction showed no cytotoxic effects on the cells due to silver coating and anodization of samples. PMID:27017285

Stress-related psychological symptoms contribute to axial pain persistence after motor vehicle collision: path analysis results from a prospective longitudinal study.

PubMed

Feinberg, Rose K; Hu, JunMei; Weaver, Mark A; Fillingim, Roger B; Swor, Robert A; Peak, David A; Jones, Jeffrey S; Rathlev, Niels K; Lee, David C; Domeier, Robert M; Hendry, Phyllis L; Liberzon, Israel; McLean, Samuel A

2017-04-01

Posttraumatic stress disorder (PTSD) symptoms and pain after traumatic events such as motor vehicle collision (MVC) have been proposed to be mutually promoting. We performed a prospective multicenter study that enrolled 948 individuals who presented to the emergency department within 24 hours of MVC and were discharged home after evaluation. Follow-up evaluations were completed 6 weeks, 6 months, and 1 year after MVC. Path analysis results supported the hypothesis that axial pain after MVC consistently promotes the maintenance of hyperarousal and intrusive symptoms, from the early weeks after injury through 1 year. In addition, path analysis results supported the hypothesis that one or more PTSD symptom clusters had an influence on axial pain outcomes throughout the year after MVC, with hyperarousal symptoms most influencing axial pain persistence in the initial months after MVC. The influence of hyperarousal symptoms on pain persistence was only present among individuals with genetic vulnerability to stress-induced pain, suggesting specific mechanisms by which hyperarousal symptoms may lead to hyperalgesia and allodynia. Further studies are needed to better understand the specific mechanisms by which pain and PTSD symptoms enhance one another after trauma, and how such mechanisms vary among specific patient subgroups, to better inform the development of secondary preventive interventions.

Evaluation of an intact, an ACL-deficient, and a reconstructed human knee joint finite element model.

PubMed

Vairis, Achilles; Stefanoudakis, George; Petousis, Markos; Vidakis, Nectarios; Tsainis, Andreas-Marios; Kandyla, Betina

2016-02-01

The human knee joint has a three-dimensional geometry with multiple body articulations that produce complex mechanical responses under loads that occur in everyday life and sports activities. Understanding the complex mechanical interactions of these load-bearing structures is of use when the treatment of relevant diseases is evaluated and assisting devices are designed. The anterior cruciate ligament (ACL) in the knee is one of four main ligaments that connects the femur to the tibia and is often torn during sudden twisting motions, resulting in knee instability. The objective of this work is to study the mechanical behavior of the human knee joint and evaluate the differences in its response for three different states, i.e., intact, ACL-deficient, and surgically treated (reconstructed) knee. The finite element models corresponding to these states were developed. For the reconstructed model, a novel repair device was developed and patented by the author in previous work. Static load cases were applied, as have already been presented in a previous work, in order to compare the calculated results produced by the two models the ACL-deficient and the surgically reconstructed knee joint, under the exact same loading conditions. Displacements were calculated in different directions for the load cases studied and were found to be very close to those from previous modeling work and were in good agreement with experimental data presented in literature. The developed finite element model for both the intact and the ACL-deficient human knee joint is a reliable tool to study the kinematics of the human knee, as results of this study show. In addition, the reconstructed human knee joint model had kinematic behavior similar to the intact knee joint, showing that such reconstruction devices can restore human knee stability to an adequate extent.

Nondestructive evaluation of orthopaedic implant stability in THA using highly nonlinear solitary waves

NASA Astrophysics Data System (ADS)

Yang, Jinkyu; Silvestro, Claudio; Sangiorgio, Sophia N.; Borkowski, Sean L.; Ebramzadeh, Edward; De Nardo, Luigi; Daraio, Chiara

2012-01-01

We propose a new biomedical sensing technique based on highly nonlinear solitary waves to assess orthopaedic implant stability in a nondestructive and efficient manner. We assemble a granular crystal actuator consisting of a one-dimensional tightly packed array of spherical particles, to generate acoustic solitary waves. Via direct contact with the specimen, we inject acoustic solitary waves into a biomedical prosthesis, and we nondestructively evaluate the mechanical integrity of the bone-prosthesis interface, studying the properties of the waves reflected from the contact zone between the granular crystal and the implant. The granular crystal contains a piezoelectric sensor to measure the travelling solitary waves, which allows it to function also as a sensor. We perform a feasibility study using total hip arthroplasty (THA) samples made of metallic stems implanted in artificial composite femurs using polymethylmethacrylate for fixation. We first evaluate the sensitivity of the proposed granular crystal sensor to various levels of prosthesis insertion into the composite femur. Then, we impose a sequence of harsh mechanical loading on the THA samples to degrade the mechanical integrity at the stem-cement interfaces, using a femoral load simulator that simulates aggressive, accelerated physiological loading. We investigate the implant stability via the granular crystal sensor-actuator during testing. Preliminary results suggest that the reflected waves respond sensitively to the degree of implant fixation. In particular, the granular crystal sensor-actuator successfully detects implant loosening at the stem-cement interface following violent cyclic loading. This study suggests that the granular crystal sensor and actuator has the potential to detect metal-cement defects in a nondestructive manner for orthopaedic applications.

Comparison of Superelasticity of Nickel Titanium Orthodontic Arch wires using Mechanical Tensile Testing and Correlating with Electrical Resistivity

PubMed Central

Sivaraj, Aravind

2013-01-01

Background: Application of light and continuous forces for optimum physiological response and least damage to the tooth supporting structures should be the primary aim of the orthodontist. Nickel titanium alloys with the properties of excellent spring back, super elasticity and wide range of action is one of the natural choices for the clinicians to achieve this goal. In recent periods, various wire manufacturers have come with a variety of wires exhibiting different properties. It is the duty of the clinician to select appropriate wires during various stages of treatment for excellent results. For achieving this evaluation of the properties of these wires is essential. Materials & Methods: This study is focussed on evaluating the super elastic property of eight groups of austenite active nickel titanium wires. Eight groups of archwires bought from eight different manufacturers were studied. These wires were tested through mechanical tensile testing and electrical resistivity methods. Results: Unloading curves were carefully assessed for superelastic behaviour on deactivation. Rankings of the wires tested were based primarily upon the unloading curve’s slope Conclusion: Ortho organisers wires ranked first and superior, followed by American Orthodontics and Ormco A wires. Morelli and GAClowland NiTi wires were ranked last. It can be concluded that the performance of these wires based on rankings should be further evaluated by clinical studies. How to cite this article: Sivaraj A. Comparison of Superelasticity of Nickel Titanium Orthodontic Arch wires using Mechanical Tensile Testing and Correlating with Electrical Resistivity. J Int Oral Health 2013; 5(3):1-12. PMID:24155596

Quantitative Ultrasonic Evaluation of Mechanical Properties of Engineering Materials

NASA Technical Reports Server (NTRS)

Vary, A.

1978-01-01

Progress in the application of ultrasonic techniques to nondestructive measurement of mechanical strength of engineering materials is reviewed. A dormant concept in nondestructive evaluation (NDE) is invoked. The availability of ultrasonic methods that can be applied to actual parts to assess their potential susceptibility to failure under design conditions is discussed. It was shown that ultrasonic methods yield measurements of elastic moduli, microstructure, hardness, fracture toughness, tensile strength, yield strength, and shear strength for a wide range of materials (including many types of metals, ceramics, and fiber composites). It was also indicated that although most of these methods were shown feasible in laboratory studies, more work is needed before they can be used on actual parts in processing, assembly, inspection, and maintenance lines.

Nucleation of the Widmanstatten Pattern in Iron Meteorites

NASA Technical Reports Server (NTRS)

Yang, J.; Goldstein, J. I.

2004-01-01

The Widmanstatten pattern develops at low temperatures during the evolution of the asteroids. We have studied the origin of the Widmanstatten pattern in order to obtain metallographic cooling rates in the temperature range (approx. 700 to 300 deg C). This paper summarizes our recent evaluation of the various mechanisms for the formation of the Widmanstatten pattern. All chemical groups of the iron meteorites are considered. We also propose a new mechanism for the formation of the Widmanstatten pattern in the low P metal phase of iron, stony-iron and stony meteorites. The results of this evaluation enables us to more accurately determine metallographic cooling rates particularly when incorporated with other recent advances in Fe-Ni and Fe-Ni (P saturated) phase diagrams and interdiffusion coefficients.

Utility of cardiac computed tomography for evaluation of pannus in mechanical aortic valve.

PubMed

Suh, Young Joo; Kim, Young Jin; Lee, Sak; Hong, Yoo Jin; Lee, Hye-Jeong; Hur, Jin; Choi, Byoung Wook; Chang, Byung-Chul

2015-08-01

The clinical significance of pannus detected on computed tomography (CT) has not yet been investigated. The purposes of this study were to investigate the clinical significance of pannus detected on cardiac CT in patients who underwent aortic valve replacement (AVR) with mechanical valves, and to determine predictors for pannus severity. A total of 92 patients who underwent cardiac CT and TTE and who had undergone mechanical AVR were included. The geometric orifice area (GOA), the presence of limitation of motion (LOM) and pannus were evaluated on CT. The GOA, presence of LOM, and presence and severity of pannus were compared with echocardiographic parameters. Logistic regression analysis was performed to determine the predictors for pannus severity. The GOA on CT positively correlated with effective orifice area on TTE (r = 0.733, P < 0.0001). Pannus was found in 77.2% and LOM in 14.0%. With increasing pannus severity, mean transvalvular pressure gradient (PG) was significantly higher (P < 0.0001). Patients with elevated PG showed a smaller GOA, a higher incidence of pannus, more severe pannus and LOM than patients with normal PG (P < 0.05). Small valve size (≤19 mm), Carbomedics valve, rheumatic etiology, and young age at AVR (<48.8 years) were independent predictors of moderate to severe pannus (P < 0.05). Cardiac CT is helpful in the evaluation of pannus formation in patients with mechanical aortic valves. Moderate to severe pannus formation frequently occurred in patients with small mechanical valve size, Carbomedics valves, rheumatic heart disease and young age at AVR.

Aroma Effects on Physiologic and Cognitive Function Following Acute Stress: A Mechanism Investigation

PubMed Central

Oken, Barry S.

2016-01-01

Abstract Objective: Aromas may improve physiologic and cognitive function after stress, but associated mechanisms remain unknown. This study evaluated the effects of lavender aroma, which is commonly used for stress reduction, on physiologic and cognitive functions. The contribution of pharmacologic, hedonic, and expectancy-related mechanisms of the aromatherapy effects was evaluated. Methods: Ninety-two healthy adults (mean age, 58.0 years; 79.3% women) were randomly assigned to three aroma groups (lavender, perceptible placebo [coconut], and nonperceptible placebo [water] and to two prime subgroups (primed, with a suggestion of inhaling a powerful stress-reducing aroma, or no prime). Participants' performance on a battery of cognitive tests, physiologic responses, and subjective stress were evaluated at baseline and after exposure to a stress battery during which aromatherapy was present. Participants also rated the intensity and pleasantness of their assigned aroma. Results: Pharmacologic effects of lavender but not placebo aromas significantly benefited post-stress performance on the working memory task (F(2, 86) = 5.41; p = 0.006). Increased expectancy due to positive prime, regardless of aroma type, facilitated post-stress performance on the processing speed task (F(1, 87) = 8.31; p = 0.005). Aroma hedonics (pleasantness and intensity) played a role in the beneficial lavender effect on working memory and physiologic function. Conclusions: The observable aroma effects were produced by a combination of mechanisms involving aroma-specific pharmacologic properties, aroma hedonic properties, and participant expectations. In the future, each of these mechanisms could be manipulated to produce optimal functioning. PMID:27355279

Development and evaluation of P/M processing techniques to improve and control the mechanical properties of metal injection molded parts

NASA Astrophysics Data System (ADS)

Sago, James Alan

Metal Injection Molding (MIM) is one of the most rapidly growing areas of powder metallurgy (P/M) but the growth of MIM into new markets and more demanding applications is limited by two fundamental barriers, the availability of low cost metal powders and a lack of knowledge and understanding of how mechanical properties, especially toughness, are affected by the many parameters in the MIM process. The goals of this study were to investigate solutions to these challenges for MIM. Mechanical alloying (MA) is a technique which can produce a wide variety of powder compositions in a size range suited to MIM and in smaller batches. However MA typically suffers from low production volumes and long milling times. This study will show that a saucer mill can produce sizable volumes of MA powders in times typically less than an hour. The MA process was also used to produce powders of 17-4PH stainless steel and the NiTi shape memory alloy for a MIM feedstock. This study shows that the MA powder characteristics led to successful MIM processing of parts. Previous studies have shown that the toughness of individual MIM parts can vary widely within a single production run and from one producer to another. In the last part of the study a Design of Experiments (DOE) approach was used to evaluate the effects of MIM processing parameters on the mechanical properties. Analysis of Variance produced mathematical models for Charpy impact toughness, hardness, density, and carbon content. Tensile properties did not produce a good model due to processing problems. The models and recommendations for improving both toughness and reproducibility of toughness are presented.

Small, high pressure ratio compressor: Aerodynamic and mechanical design

NASA Technical Reports Server (NTRS)

Bryce, C. A.; Erwin, J. R.; Perrone, G. L.; Nelson, E. L.; Tu, R. K.; Bosco, A.

1973-01-01

The Small, High-Pressure-Ratio Compressor Program was directed toward the analysis, design, and fabrication of a centrifugal compressor providing a 6:1 pressure ratio and an airflow rate of 2.0 pounds per second. The program consists of preliminary design, detailed areodynamic design, mechanical design, and mechanical acceptance tests. The preliminary design evaluate radial- and backward-curved blades, tandem bladed impellers, impeller-and diffuser-passage boundary-layer control, and vane, pipe, and multiple-stage diffusers. Based on this evaluation, a configuration was selected for detailed aerodynamic and mechanical design. Mechanical acceptance test was performed to demonstrate that mechanical design objectives of the research package were met.

An investigative study of polymer adsorption onto montmorillonite clay

NASA Astrophysics Data System (ADS)

McConnell Boykin, Cheri Lynn

For colloidal systems with adsorbed polymer, the mechanisms governing stabilization and flocculation are defined by the critical overlap concentration, c*. Below c*, steric stabilization or bridging flocculation are viable mechanisms of adsorption, while above c* associative thickening stabilization, depletion stabilization or depletion flocculation may occur. While these types of systems have been described by their mechanism of interaction, few studies have been geared towards evaluating and actually defining these interactions. This research focuses on elucidating the mechanisms of interaction for a series of polyacrylamide copolymers adsorbed onto montmorillonite clay. The well-defined copolymers synthesized and characterized for these studies include: nonionic polyacrylamide, (PAm); cationic poly(acrylamide-co-[3-(methacryloylamino) propyl] trimethylammonium chloride), (PAmMaap Quat); nonionic/anionic poly(acrylamide-co-acrylic acid), (PAmAA); and anionic poly(acrylamide-co-[2-acrylamido-2-methylpropane sulfonic acid]), (PAmAmps). By combining the results from the following experiments it was possible to determine the mechanisms of interaction for each of the clay/polymer systems at pH 3, 7 and 10. The adsorption capacity of each of the copolymers was determined from constructing adsorption isotherms while the polymer conformation was determined from 13C NMR line-broadening experiments. FTIR spectroscopy verified which surface of the clay was involved in adsorption along with the polymer moiety bound to the surface. Finally, the stabilization behavior was evaluated from statistically designed phase diagrams as a function of polymer and clay concentrations. By evaluating the phase behavior as well as c* for the polymer/solvent systems, it was determined that there was no direct correlation between c* for a polymer/solvent system and the mechanism of interaction for colloid/polymer/solvent systems previously defined by Vincent, Sato and Napper. In general, the nonionic polymers act as H-bond acceptors (amide and acid moieties) and donators (acid groups) which result in associatively stabilized homogeneous montmorillonite clay dispersions. The cationic copolymers exhibit strong, irreversible interactions with the clay resulting in heterogeneous bridging flocculation, which was shown to be dependent on the charge density of the copolymer. Furthermore, the anionic copolymers show no signs of adsorption, but create a network of repulsive forces with the montmorillonite clay, which ultimately results in depletion stabilization with some degree of depletion flocculation.

In situ MEMS testing: correlation of high-resolution X-ray diffraction with mechanical experiments and finite element analysis.

PubMed

Schifferle, Andreas; Dommann, Alex; Neels, Antonia

2017-01-01

New methods are needed in microsystems technology for evaluating microelectromechanical systems (MEMS) because of their reduced size. The assessment and characterization of mechanical and structural relations of MEMS are essential to assure the long-term functioning of devices, and have a significant impact on design and fabrication. Within this study a concept for the investigation of mechanically loaded MEMS materials on an atomic level is introduced, combining high-resolution X-ray diffraction (HRXRD) measurements with finite element analysis (FEA) and mechanical testing. In situ HRXRD measurements were performed on tensile loaded single crystal silicon (SCSi) specimens by means of profile scans and reciprocal space mapping (RSM) on symmetrical (004) and (440) reflections. A comprehensive evaluation of the rather complex XRD patterns and features was enabled by the correlation of measured with simulated, 'theoretical' patterns. Latter were calculated by a specifically developed, simple and fast approach on the basis of continuum mechanical relations. Qualitative and quantitative analysis confirmed the admissibility and accuracy of the presented method. In this context [001] Poisson's ratio was determined providing an error of less than 1.5% with respect to analytical prediction. Consequently, the introduced procedure contributes to further going investigations of weak scattering being related to strain and defects in crystalline structures and therefore supports investigations on materials and devices failure mechanisms.

In situ MEMS testing: correlation of high-resolution X-ray diffraction with mechanical experiments and finite element analysis

PubMed Central

Schifferle, Andreas; Dommann, Alex; Neels, Antonia

2017-01-01

Abstract New methods are needed in microsystems technology for evaluating microelectromechanical systems (MEMS) because of their reduced size. The assessment and characterization of mechanical and structural relations of MEMS are essential to assure the long-term functioning of devices, and have a significant impact on design and fabrication. Within this study a concept for the investigation of mechanically loaded MEMS materials on an atomic level is introduced, combining high-resolution X-ray diffraction (HRXRD) measurements with finite element analysis (FEA) and mechanical testing. In situ HRXRD measurements were performed on tensile loaded single crystal silicon (SCSi) specimens by means of profile scans and reciprocal space mapping (RSM) on symmetrical (004) and (440) reflections. A comprehensive evaluation of the rather complex XRD patterns and features was enabled by the correlation of measured with simulated, ‘theoretical’ patterns. Latter were calculated by a specifically developed, simple and fast approach on the basis of continuum mechanical relations. Qualitative and quantitative analysis confirmed the admissibility and accuracy of the presented method. In this context [001] Poisson’s ratio was determined providing an error of less than 1.5% with respect to analytical prediction. Consequently, the introduced procedure contributes to further going investigations of weak scattering being related to strain and defects in crystalline structures and therefore supports investigations on materials and devices failure mechanisms. PMID:28533825

Impact of polymer modification on mechanical and viscoelastic properties.

DOT National Transportation Integrated Search

2015-10-01

This study was initiated with the aim of evaluating the relative impact of different cross-linking agents : on the rheological and morphological properties of polymer modified asphalt binders (PMAs). To : complete this objective, two cross-linking ag...

Recommendations for extending asphalt pavement surface life within Washington State.

DOT National Transportation Integrated Search

2016-10-01

This study identifies and evaluates hot mix asphalt (HMA) mix design and construction techniques with potential for improving WSDOT pavement surface life. WSDOT pavement failure mechanisms are found to be predominantly cracking. Rutting may reach a f...

Evaluation of thin asphalt overlay practice preserving Nebraska's asphalt pavements.

DOT National Transportation Integrated Search

2015-06-01

This study examined the current thin asphalt overlay practices implemented in Nebraska. To that end, the mechanical : properties and performance characteristics of the two mixtures (i.e., SLX and SPH) were compared by carrying out : laboratory tests ...

A realist evaluation of the management of a well- performing regional hospital in Ghana

PubMed Central

2010-01-01

Background Realist evaluation offers an interesting approach to evaluation of interventions in complex settings, but has been little applied in health care. We report on a realist case study of a well performing hospital in Ghana and show how such a realist evaluation design can help to overcome the limited external validity of a traditional case study. Methods We developed a realist evaluation framework for hypothesis formulation, data collection, data analysis and synthesis of the findings. Focusing on the role of human resource management in hospital performance, we formulated our hypothesis around the high commitment management concept. Mixed methods were used in data collection, including individual and group interviews, observations and document reviews. Results We found that the human resource management approach (the actual intervention) included induction of new staff, training and personal development, good communication and information sharing, and decentralised decision-making. We identified 3 additional practices: ensuring optimal physical working conditions, access to top managers and managers' involvement on the work floor. Teamwork, recognition and trust emerged as key elements of the organisational climate. Interviewees reported high levels of organisational commitment. The analysis unearthed perceived organisational support and reciprocity as underlying mechanisms that link the management practices with commitment. Methodologically, we found that realist evaluation can be fruitfully used to develop detailed case studies that analyse how management interventions work and in which conditions. Analysing the links between intervention, mechanism and outcome increases the explaining power, while identification of essential context elements improves the usefulness of the findings for decision-makers in other settings (external validity). We also identified a number of practical difficulties and priorities for further methodological development. Conclusion This case suggests that a well-balanced HRM bundle can stimulate organisational commitment of health workers. Such practices can be implemented even with narrow decision spaces. Realist evaluation provides an appropriate approach to increase the usefulness of case studies to managers and policymakers. PMID:20100330

A realist evaluation of the management of a well-performing regional hospital in Ghana.

PubMed

Marchal, Bruno; Dedzo, McDamien; Kegels, Guy

2010-01-25

Realist evaluation offers an interesting approach to evaluation of interventions in complex settings, but has been little applied in health care. We report on a realist case study of a well performing hospital in Ghana and show how such a realist evaluation design can help to overcome the limited external validity of a traditional case study. We developed a realist evaluation framework for hypothesis formulation, data collection, data analysis and synthesis of the findings. Focusing on the role of human resource management in hospital performance, we formulated our hypothesis around the high commitment management concept. Mixed methods were used in data collection, including individual and group interviews, observations and document reviews. We found that the human resource management approach (the actual intervention) included induction of new staff, training and personal development, good communication and information sharing, and decentralised decision-making. We identified 3 additional practices: ensuring optimal physical working conditions, access to top managers and managers' involvement on the work floor. Teamwork, recognition and trust emerged as key elements of the organisational climate. Interviewees reported high levels of organisational commitment. The analysis unearthed perceived organisational support and reciprocity as underlying mechanisms that link the management practices with commitment. Methodologically, we found that realist evaluation can be fruitfully used to develop detailed case studies that analyse how management interventions work and in which conditions. Analysing the links between intervention, mechanism and outcome increases the explaining power, while identification of essential context elements improves the usefulness of the findings for decision-makers in other settings (external validity). We also identified a number of practical difficulties and priorities for further methodological development. This case suggests that a well-balanced HRM bundle can stimulate organisational commitment of health workers. Such practices can be implemented even with narrow decision spaces. Realist evaluation provides an appropriate approach to increase the usefulness of case studies to managers and policymakers.

Assessment of start-up mechanisms for anaerobic fluidized bed reactor in series based on mathematical simulation

NASA Astrophysics Data System (ADS)

Sudibyo, Hanifrahmawan; Guntama, Dody; Budhijanto, Wiratni

2017-05-01

Anaerobic digestion is associated with long hydraulic residence time and hence leads to huge reactor volume, especially for high rate input to the reactor. To overcome this major drawback, one of the possibilities is optimizing the schemes of reactor configuration and start-up mechanisms. This study aimed to determine the most promising start-up mechanism for anaerobic digestion reactors in series, with respect to the shortest hydraulic residence time to reach the highest biogas production rate. The reactor to be studied is anaerobic fluidized bed reactor (AFBR) which is known as the most efficient reactor for high organic loading rate. Case to be studied is landfill leachate digestion. Although reactor optimization can be conducted experimentally, it could be expensive and time consuming. This study proposed the utilization of mathematical modeling to screen the possibilities towards the best options to be verified experimentally. Kinetic study of landfill leachate anaerobic digestion was first conducted to depict the rate of microbial growth and the rate of substrate consumption. Kinetics constants obtained from this batch experiment were then used in the mathematical model representing AFBR. Several mechanisms were simulated in this study. In the first mechanism, all digesters were started simultaneously. In the second mechanism, each digester was started until it achieved steady-state condition before the next digester was started. The third mechanism was start-up scenario for single reactor as opposed to the previous two mechanisms. These all three mechanisms were simulated for either one-through stream and recycling a portion of the reactor effluent. The mathematical simulation result was used to evaluate each mechanism based on hydraulic residence time required for all digesters in series to reach the steady-state condition, the extent of pollutant removal, and the rate of biogas production. In the need of high sCOD removal, the second mechanism emerged as the best one.

Fighting Crime by Fighting Misconceptions and Blind Spots in Policy Theories: An Evidence-Based Evaluation of Interventions and Assumed Causal Mechanisms

ERIC Educational Resources Information Center

van Noije, Lonneke; Wittebrood, Karin

2010-01-01

How effective are policy interventions to fight crime and how valid is the policy theory that underlies them? This is the twofold research question addressed in this article, which presents an evidence-based evaluation of Dutch social safety policy. By bridging the gap between actual effects and assumed effects, this study seeks to make fuller use…

Chondroprotective supplementation promotes the mechanical properties of injectable scaffold for human nucleus pulposus tissue engineering.

PubMed

Foss, Berit L; Maxwell, Thomas W; Deng, Ying

2014-01-01

A result of intervertebral disc (IVD) degeneration, the nucleus pulposus (NP) is no longer able to withstand applied load leading to pain and disability. The objective of this study is to fabricate a tissue-engineered injectable scaffold with chondroprotective supplementation in vitro to improve the mechanical properties of a degenerative NP. Tissue-engineered scaffolds were fabricated using different concentrations of alginate and calcium chloride and mechanically evaluated. Fabrication conditions were based on structural and mechanical resemblance to the native NP. Chondroprotective supplementation, glucosamine (GCSN) and chondroitin sulfate (CS), were added to scaffolds at concentrations of 0:0µg/mL (0:0-S), 125:100µg/mL (125:100-S), 250:200µg/mL (250:200-S), and 500:400µg/mL (500:400-S), GCSN and CS, respectively. Scaffolds were used to fabricate tissue-engineered constructs through encapsulation of human nucleus pulposus cells (HNPCs). The tissue-engineered constructs were collected at days 1, 14, and 28 for biochemical and biomechanical evaluations. Confocal microscopy showed HNPC viability and rounded morphology over the 28 day period. MTT analysis resulted in significant increases in cell proliferation for each group. Collagen type II ELISA quantification and compressive aggregate moduli (HA) showed increasing trends for both 250:200-S and the 500:400-S groups on Day 28 with significantly greater HA compared to 0:0-S group. Glycosaminoglycan and water content decreased for all groups. Results indicate the increased mechanical properties of the 250:200-S and the 500:400-S was due to production of a functional matrix. This study demonstrated potential for a chondroprotective supplemented injectable scaffold to restore biomechanical function of a degenerative disc through the production of a mechanically functional matrix. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mechanical constraints on fault geometries and structural styles in extensional geologic settings

NASA Astrophysics Data System (ADS)

Hughes, A. N.

2017-12-01

The geologic structures that accommodate crustal extension in various tectonic environments, including rifts basins, passive margins, and gravitational collapse systems, exhibit a wide range of geometric styles. While several previous studies have focused on the mechanical controls on crustal-scale rift margin geometry, less attention has been paid to the role of mechanics in the style of the individual structures or groups of structures that deform the brittle upper crust. The main modes of extensional structures that have been observed—including parallel fault arrays, half-grabens, grabens, and core complexes—inherently imply mechanical conditions that favor their formation, but an exhaustive evaluation of the circumstances that favor the creation of each of these primary types has yet to be explored, and thus is the focus of this study. This issue is addressed through the construction of a series of 2D forward mechanical models using the discrete element modeling approach. With the intent of representing the wide range of realistic geologic circumstances in which these structures form, a suite of models were constructed by varying parameters such as rock section thickness and strength properties, detachment zone friction, thickness, and dip, extension rate, and various boundary conditions such as erosion and syntectonic sedimentation. The results of these models were then evaluated in order to identify the combinations of parameters that favor the development of each of the main structural styles. Furthermore, the ability to interrogate the stress and strain fields in the models helps shed light on the specific mechanisms that give rise to these different manifestations of extensional strain. Application of these insights to interpretations of extensional structures in rift basins will help to provide a useful framework for understanding the connection between the observed structural style in a region and the conditions that gave rise to its occurrence.

Studies to further investigate the inhibition of human liver microsomal CYP2C8 by the acyl-β-glucuronide of gemfibrozil.

PubMed

Jenkins, S M; Zvyaga, T; Johnson, S R; Hurley, J; Wagner, A; Burrell, R; Turley, W; Leet, J E; Philip, T; Rodrigues, A D

2011-12-01

In previous studies, gemfibrozil acyl-β-glucuronide, but not gemfibrozil, was found to be a mechanism-based inhibitor of cytochrome P450 2C8. To better understand whether this inhibition is specific for gemfibrozil acyl-β-glucuronide or whether other glucuronide conjugates are potential substrates for inhibition of this enzyme, we evaluated several pharmaceutical compounds (as their acyl glucuronides) as direct-acting and metabolism-dependent inhibitors of CYP2C8 in human liver microsomes. Of 11 compounds that were evaluated as their acyl glucuronide conjugates, only gemfibrozil acyl-β-glucuronide exhibited mechanism-based inhibition, indicating that CYP2C8 mechanism-based inhibition is very specific to certain glucuronide conjugates. Structural analogs of gemfibrozil were synthesized, and their glucuronide conjugates were prepared to further examine the mechanism of inhibition. When the aromatic methyl groups on the gemfibrozil moiety were substituted with trifluoromethyls, the resulting glucuronide conjugate was a weaker inhibitor of CYP2C8 and mechanism-based inhibition was abolished. However, the glucuronide conjugates of monomethyl gemfibrozil analogs were mechanism-based inhibitors of CYP2C8, although not as potent as gemfibrozil acyl-β-glucuronide itself. The ortho-monomethyl analog was a more potent inhibitor than the meta-monomethyl analog, indicating that CYP2C8 favors the ortho position for oxidation and potential inhibition. Molecular modeling of gemfibrozil acyl-β-glucuronide in the CYP2C8 active site is consistent with the ortho-methyl position being the favored site of covalent attachment to the heme. Moreover, hydrogen bonding to four residues (Ser100, Ser103, Gln214, and Asn217) is implicated.

Rat disc torsional mechanics: effect of lumbar and caudal levels and axial compression load.

PubMed

Espinoza Orías, Alejandro A; Malhotra, Neil R; Elliott, Dawn M

2009-03-01

Rat models with altered loading are used to study disc degeneration and mechano-transduction. Given the prominent role of mechanics in disc function and degeneration, it is critical to measure mechanical behavior to evaluate changes after model interventions. Axial compression mechanics of the rat disc are representative of the human disc when normalized by geometry, and differences between the lumbar and caudal disc have been quantified in axial compression. No study has quantified rat disc torsional mechanics. Compare the torsional mechanical behavior of rat lumbar and caudal discs, determine the contribution of combined axial load on torsional mechanics, and compare the torsional properties of rat discs to human lumbar discs. Cadaveric biomechanical study. Cyclic torsion without compressive load followed by cyclic torsion with a fixed compressive load was applied to rat lumbar and caudal disc levels. The apparent torsional modulus was higher in the lumbar region than in the caudal region: 0.081+/-0.026 (MPa/degrees, mean+/-SD) for lumbar axially loaded; 0.066+/-0.028 for caudal axially loaded; 0.091+/-0.033 for lumbar in pure torsion; and 0.056+/-0.035 for caudal in pure torsion. These values were similar to human disc properties reported in the literature ranging from 0.024 to 0.21 MPa/degrees. Use of the caudal disc as a model may be appropriate if the mechanical focus is within the linear region of the loading regime. These results provide support for use of this animal model in basic science studies with respect to torsional mechanics.

Daily Goals Formulation and Enhanced Visualization of Mechanical Ventilation Variance Improves Mechanical Ventilation Score.

PubMed

Walsh, Brian K; Smallwood, Craig; Rettig, Jordan; Kacmarek, Robert M; Thompson, John; Arnold, John H

2017-03-01

The systematic implementation of evidence-based practice through the use of guidelines, checklists, and protocols mitigates the risks associated with mechanical ventilation, yet variation in practice remains prevalent. Recent advances in software and hardware have allowed for the development and deployment of an enhanced visualization tool that identifies mechanical ventilation goal variance. Our aim was to assess the utility of daily goal establishment and a computer-aided visualization of variance. This study was composed of 3 phases: a retrospective observational phase (baseline) followed by 2 prospective sequential interventions. Phase I intervention comprised daily goal establishment of mechanical ventilation. Phase II intervention was the setting and monitoring of daily goals of mechanical ventilation with a web-based data visualization system (T3). A single score of mechanical ventilation was developed to evaluate the outcome. The baseline phase evaluated 130 subjects, phase I enrolled 31 subjects, and phase II enrolled 36 subjects. There were no differences in demographic characteristics between cohorts. A total of 171 verbalizations of goals of mechanical ventilation were completed in phase I. The use of T3 increased by 87% from phase I. Mechanical ventilation score improved by 8.4% in phase I and 11.3% in phase II from baseline ( P = .032). The largest effect was in the low risk V T category, with a 40.3% improvement from baseline in phase I, which was maintained at 39% improvement from baseline in phase II ( P = .01). mechanical ventilation score was 9% higher on average in those who survived. Daily goal formation and computer-enhanced visualization of mechanical ventilation variance were associated with an improvement in goal attainment by evidence of an improved mechanical ventilation score. Further research is needed to determine whether improvements in mechanical ventilation score through a targeted, process-oriented intervention will lead to improved patient outcomes. (ClinicalTrials.gov registration NCT02184208.). Copyright © 2017 by Daedalus Enterprises.

Mechanics and pathomechanics in the overhead athlete.

PubMed

Kibler, W Ben; Wilkes, Trevor; Sciascia, Aaron

2013-10-01

Optimal performance of the overhead throwing task requires precise mechanics that involve coordinated kinetic and kinematic chains to develop, transfer, and regulate the forces the body needs to withstand the inherent demands of the task and to allow optimal performance. These chains have been evaluated and the basic components, called nodes, have been identified. Impaired performance and/or injury, the DTS, is associated with alterations in the mechanics that are called pathomechanics. They can occur at multiple locations throughout the kinetic chain. They must be evaluated and treated as part of the overall problem. Observational analysis of the mechanics and pathomechanics using the node analysis method can be useful in highlighting areas of alteration that can be evaluated for anatomic injury or altered physiology. The comprehensive kinetic chain examination can evaluate sites of kinetic chain breakage, and a detailed shoulder examination can assess joint internal derangement of altered physiology that may contribute to the pathomechanics. Treatment of the DTS should be comprehensive, directed toward restoring physiology and mechanics and optimizing anatomy. This maximizes the body’s ability to develop normal mechanics to accomplish the overhead throwing task. Copyright © 2013 Elsevier Inc. All rights reserved.

Effect of Heliox on Respiratory Outcomes during Rigid Bronchoscopy in Term Lambs.

PubMed

Sowder, Justin C; Dahl, Mar Janna; Zuspan, Kaitlin R; Albertine, Kurt H; Null, Donald M; Barneck, Mitchell D; Grimmer, J Fredrik

2018-03-01

Objective To (1) compare physiologic changes during rigid bronchoscopy during spontaneous and mechanical ventilation and (2) evaluate the efficacy of a helium-oxygen (heliox) gas mixture as compared with room air during rigid bronchoscopy. Study Design Crossover animal study evaluating physiologic parameters during rigid bronchoscopy. Outcomes were compared with predicted computational fluid analysis. Setting Simulated ventilation via computational fluid dynamics analysis and term lambs undergoing rigid bronchoscopy. Methods Respiratory and physiologic outcomes were analyzed in a lamb model simulating bronchoscopy during foreign body aspiration to compare heliox with room air. The main outcome measures were blood oxygen saturation, heart rate, blood pressure, partial pressure of oxygen, and partial pressure of carbon dioxide. Computational fluid dynamics analysis was performed with SOLIDWORKS within a rigid pediatric bronchoscope during simulated ventilation comparing heliox with room air. Results For room air, lambs desaturated within 3 minutes during mechanical ventilation versus normal oxygen saturation during spontaneous ventilation ( P = .01). No improvement in respiratory outcomes was seen between heliox and room air during mechanical ventilation. Computational fluid dynamics analysis demonstrates increased turbulence within size 3.5 bronchoscopes when comparing heliox and room air. Meaningful comparisons could not be made due to the intolerance of the lambs to heliox in vivo. Conclusion During mechanical ventilation on room air, lambs desaturate more quickly during rigid bronchoscopy on settings that should be adequate. Heliox does not improve ventilation during rigid bronchoscopy.

Quantitative Imaging of Young's Modulus of Soft Tissues from Ultrasound Water Jet Indentation: A Finite Element Study

PubMed Central

Lu, Min-Hua; Mao, Rui; Lu, Yin; Liu, Zheng; Wang, Tian-Fu; Chen, Si-Ping

2012-01-01

Indentation testing is a widely used approach to evaluate mechanical characteristics of soft tissues quantitatively. Young's modulus of soft tissue can be calculated from the force-deformation data with known tissue thickness and Poisson's ratio using Hayes' equation. Our group previously developed a noncontact indentation system using a water jet as a soft indenter as well as the coupling medium for the propagation of high-frequency ultrasound. The novel system has shown its ability to detect the early degeneration of articular cartilage. However, there is still lack of a quantitative method to extract the intrinsic mechanical properties of soft tissue from water jet indentation. The purpose of this study is to investigate the relationship between the loading-unloading curves and the mechanical properties of soft tissues to provide an imaging technique of tissue mechanical properties. A 3D finite element model of water jet indentation was developed with consideration of finite deformation effect. An improved Hayes' equation has been derived by introducing a new scaling factor which is dependent on Poisson's ratios v, aspect ratio a/h (the radius of the indenter/the thickness of the test tissue), and deformation ratio d/h. With this model, the Young's modulus of soft tissue can be quantitatively evaluated and imaged with the error no more than 2%. PMID:22927890

Cell free DNA: A Novel Predictor of Neurological Outcome after Intravenous Thrombolysis and/or Mechanical Thrombectomy in Acute Ischemic Stroke Patients

PubMed Central

Wijatmiko, Teddy; Vajpeyee, Manisha; Taywade, Onjal

2018-01-01

Purpose Several blood markers have been evaluated in stroke patients, but their role remains limited in clinical practice. This study was designed to evaluate the utility of cell free DNA (cf DNA) in stroke patients undergoing therapeutic intervention in the form of mechanical thrombectomy in acute ischemic stroke patients. Materials and Methods Twenty-six patients with ischemic stroke who were managed with interventions like intravenous thrombolysis (IVT) and mechanical thrombectomy were recruited consecutively in this study. The cf DNA was extracted by using circulating nucleic acid kit and measured by real-time quantitative PCR assay for β-globin gene. The neurological outcome was measured by modified Rankin scale (mRS) score at three months after the onset of symptoms. Results Cf DNA levels correlated with severity of stroke at the time of admission (r=0.421, P=0.032) and poor outcome at three months (r=0.606, P=0.001). Therapeutic intervention in the form of mechanical thrombectomy or IVT was associated with improved outcome in patients with cf DNA <10,000 kilogenome-equivalents/L (P=<0.05). Conclusion Cf DNA level correlated well with the 3 month outcome in acute ischemic stroke patients. It can be a potential supplementary marker to predict neurological outcome after therapeutic intervention. PMID:29535894

Properties of bioadhesive ketoprofen liquid suppositories: preparation, determination of gelation temperature, viscosity studies and evaluation of mechanical properties using texture analyzer by 4 × 4 factorial design.

PubMed

Ozgüney, Işık; Kardhiqi, Anita

2014-12-01

Development and evaluation of thermosensitive and bioadhesive liquid suppositories containing ketoprofen (KP). This study was conducted to develope thermosensitive and bioadhesive liquid suppositories containing KP using poloxamer and different bioadhesive polymers and to investigate their gelation temperature, viscosity and mechanical properties. Bioadhesive liquid suppositories were prepared by the cold method using poloxamer 407 (P 407), Poloxamer 188 (P 188) and various amounts of different bioadhesive polymers. Their gelation temperatures, viscosity values and mechanical properties were determined using texture analyzer by 4 × 4 factorial design. It was seen that in presence of KP, gelation temperature of formulation P 407/P 188 (4/20%) significantly decreased from 64 to 37.1 °C. It is to be noted that addition of increasing concentrations of bioadhesive polymers lowered gelation temperature and its decrease was highest with addition of Carbopol 934 P (C). Results of texture profile analysis (TPA) showed that formulations containing C have significantly higher hardness and adhesiveness values than other bioadhesive formulations. According to TPA, gel structure of liquid suppository formulation F5, containing P 407/P 188/KP/C (4/20/2.5/0.8%), exhibited the greatest hardness, compressibilty, adhesiveness and besides greatest viscosity. According to mechanical properties and viscosity values, it was concluded that F5 could be a promising formulation.

Evaluation of Endotracheal Tube Scraping on Airway Resistance.

PubMed

Scott, J Brady; Dubosky, Meagan N; Vines, David L; Sulaiman, Adewunmi S; Jendral, Kyle R; Singh, Gagan; Patel, Ankeet; Kaplan, Carl A; Gurka, David P; Balk, Robert A

2017-11-01

Spontaneous breathing trials (SBTs) are used to assess the readiness for discontinuation of mechanical ventilation. When airway resistance (R aw ) is elevated, the imposed work of breathing can lead to prolongation of mechanical ventilation. Biofilm and mucus build-up within the endotracheal tube (ETT) can increase R aw . Scraping the ETT can remove the biofilm build-up and decrease mechanical R aw . The primary aim of this study was to evaluate the impact of ETT scraping on R aw . The secondary aim was to determine whether decreasing R aw would impact subsequent SBT success. Intubated, mechanically ventilated subjects were enrolled if they failed an SBT and had an R aw of > 10 cm H 2 O/L/s. SBT failure was based on institutional guidelines, and R aw was calculated by subtracting the difference between the measured peak and plateau pressures using a square flow waveform with an inspiratory flow set at 60 L/min. The endOclear device was inserted into the ETT and withdrawn per manufacturer's guidelines. Scraping was repeated until the ETT was cleared. Change in R aw was compared pre- and post-ETT scraping using a paired t test. A Mann-Whitney U test evaluated the difference in percentage change in R aw between SBT groups. Twenty-nine subjects completed the study. The mean pre- and post-ETT scraping R aw values were 15.17 ± 3.83 and 12.05 ± 3.19 cm H 2 O/L/s, respectively ( P < .001). Subsequent SBT success was 48%; however, there was no difference in percentage change in R aw between subsequent passed SBT (18.61% [interquartile range 8.90-33.93%]) and failed SBT (23.88% [interquartile range 0.00-34.80%]), U = 78.5, z = -0.284, P = .78. No adverse events were noted with ETT scraping. This study demonstrated that ETT scraping can reduce R aw . The decrease in R aw post-ETT scraping did not affect subsequent SBT success. Copyright © 2017 by Daedalus Enterprises.

Stiffness, working stroke, and force of single-myosin molecules in skeletal muscle: elucidation of these mechanical properties via nonlinear elasticity evaluation.

PubMed

Kaya, Motoshi; Higuchi, Hideo

2013-11-01

In muscles, the arrays of skeletal myosin molecules interact with actin filaments and continuously generate force at various contraction speeds. Therefore, it is crucial for myosin molecules to generate force collectively and minimize the interference between individual myosin molecules. Knowledge of the elasticity of myosin molecules is crucial for understanding the molecular mechanisms of muscle contractions because elasticity directly affects the working and drag (resistance) force generation when myosin molecules are positively or negatively strained. The working stroke distance is also an important mechanical property necessary for elucidation of the thermodynamic efficiency of muscle contractions at the molecular level. In this review, we focus on these mechanical properties obtained from single-fiber and single-molecule studies and discuss recent findings associated with these mechanical properties. We also discuss the potential molecular mechanisms associated with reduction of the drag effect caused by negatively strained myosin molecules.

Direct Associations or Internal Transformations? Exploring the Mechanisms Underlying Sequential Learning Behavior

PubMed Central

Gureckis, Todd M.; Love, Bradley C.

2009-01-01

We evaluate two broad classes of cognitive mechanisms that might support the learning of sequential patterns. According to the first, learning is based on the gradual accumulation of direct associations between events based on simple conditioning principles. The other view describes learning as the process of inducing the transformational structure that defines the material. Each of these learning mechanisms predict differences in the rate of acquisition for differently organized sequences. Across a set of empirical studies, we compare the predictions of each class of model with the behavior of human subjects. We find that learning mechanisms based on transformations of an internal state, such as recurrent network architectures (e.g., Elman, 1990), have difficulty accounting for the pattern of human results relative to a simpler (but more limited) learning mechanism based on learning direct associations. Our results suggest new constraints on the cognitive mechanisms supporting sequential learning behavior. PMID:20396653

Computed tomography is not justified in every pediatric blunt trauma patient with a suspicious mechanism of injury.

PubMed

Hershkovitz, Yehuda; Zoarets, Itai; Stepansky, Albert; Kozer, Eran; Shapira, Zahar; Klin, Baruch; Halevy, Ariel; Jeroukhimov, Igor

2014-07-01

Computed tomography (CT) has become an important tool for the diagnosis of intra-abdominal and chest injuries in patients with blunt trauma. The role of CT in conscious asymptomatic patients with a suspicious mechanism of injury remains controversial. This controversy intensifies in the management of pediatric blunt trauma patients, who are much more susceptible to radiation exposure. The objective of this study was to evaluate the role of abdominal and chest CT imaging in asymptomatic pediatric patients with a suspicious mechanism of injury. Forty-two pediatric patients up to 15 years old were prospectively enrolled. All patients presented with a suspicious mechanism of blunt trauma and multisystem injury. They were neurologically intact and had no signs of injury to the abdomen or chest. Patients underwent CT imaging of the chest and abdomen as part of the initial evaluation. Thirty-one patients (74%) had a normal CT scan. Two patients of 11 with an abnormal CT scan required a change in management and were referred for observation in the Intensive Care Unit. None of the patients required surgical intervention. The routine use of CT in asymptomatic pediatric patients with a suspicious mechanism of blunt trauma injury is not justified. Copyright © 2014 Elsevier Inc. All rights reserved.

A Parametric Finite-Element Model for Evaluating Segmented Mirrors with Discrete, Edgewise Connectivity

NASA Technical Reports Server (NTRS)

Gersh-Range, Jessica A.; Arnold, William R.; Peck, Mason A.; Stahl, H. Philip

2011-01-01

Since future astrophysics missions require space telescopes with apertures of at least 10 meters, there is a need for on-orbit assembly methods that decouple the size of the primary mirror from the choice of launch vehicle. One option is to connect the segments edgewise using mechanisms analogous to damped springs. To evaluate the feasibility of this approach, a parametric ANSYS model that calculates the mode shapes, natural frequencies, and disturbance response of such a mirror, as well as of the equivalent monolithic mirror, has been developed. This model constructs a mirror using rings of hexagonal segments that are either connected continuously along the edges (to form a monolith) or at discrete locations corresponding to the mechanism locations (to form a segmented mirror). As an example, this paper presents the case of a mirror whose segments are connected edgewise by mechanisms analogous to a set of four collocated single-degree-of-freedom damped springs. The results of a set of parameter studies suggest that such mechanisms can be used to create a 15-m segmented mirror that behaves similarly to a monolith, although fully predicting the segmented mirror performance would require incorporating measured mechanism properties into the model. Keywords: segmented mirror, edgewise connectivity, space telescope

Association between ventilatory settings and development of acute respiratory distress syndrome in mechanically ventilated patients due to brain injury.

PubMed

Tejerina, Eva; Pelosi, Paolo; Muriel, Alfonso; Peñuelas, Oscar; Sutherasan, Yuda; Frutos-Vivar, Fernando; Nin, Nicolás; Davies, Andrew R; Rios, Fernando; Violi, Damian A; Raymondos, Konstantinos; Hurtado, Javier; González, Marco; Du, Bin; Amin, Pravin; Maggiore, Salvatore M; Thille, Arnaud W; Soares, Marco Antonio; Jibaja, Manuel; Villagomez, Asisclo J; Kuiper, Michael A; Koh, Younsuck; Moreno, Rui P; Zeggwagh, Amine Ali; Matamis, Dimitrios; Anzueto, Antonio; Ferguson, Niall D; Esteban, Andrés

2017-04-01

In neurologically critically ill patients with mechanical ventilation (MV), the development of acute respiratory distress syndrome (ARDS) is a major contributor to morbidity and mortality, but the role of ventilatory management has been scarcely evaluated. We evaluate the association of tidal volume, level of PEEP and driving pressure with the development of ARDS in a population of patients with brain injury. We performed a secondary analysis of a prospective, observational study on mechanical ventilation. We included 986 patients mechanically ventilated due to an acute brain injury (hemorrhagic stroke, ischemic stroke or brain trauma). Incidence of ARDS in this cohort was 3%. Multivariate analysis suggested that driving pressure could be associated with the development of ARDS (odds ratio for unit increment of driving pressure 1.12; confidence interval for 95%: 1.01 to 1.23) whereas we did not observe association for tidal volume (in ml per kg of predicted body weight) or level of PEEP. ARDS was associated with an increase in mortality, longer duration of mechanical ventilation, and longer ICU length of stay. In a cohort of brain-injured patients the development of ARDS was not common. Driving pressure was associated with the development of this disease. Copyright © 2016 Elsevier Inc. All rights reserved.

Evaluation of Mechanical Properties of Plywood Treated with a new Wood Preservative (CEB) Chemical

NASA Astrophysics Data System (ADS)

Kalawate, Aparna; Shahoo, Shadhu Charan; Khatua, Pijus Kanti; Das, Himadri Sekhar

2017-04-01

The objective of this study was to explore the physical and mechanical properties of the plywood made with phenolic glue and rubber wood as core veneer with CEB as a wood preservative. The studied properties were glue shear strength in dry, wet mycological, modulus of elasticity, modulus of rupture and tensile strength in parallel to grain direction as per IS:1734 part-4, 11 and 9 (1983) respectively. Results of the above mentioned tests were compared with the prescribed values given in IS 710-2010 and results revealed that samples conformed the prescribed values.

Echocardiographic Evaluation of Left Atrial Mechanics: Function, History, Novel Techniques, Advantages, and Pitfalls.

PubMed

Leischik, Roman; Littwitz, Henning; Dworrak, Birgit; Garg, Pankaj; Zhu, Meihua; Sahn, David J; Horlitz, Marc

2015-01-01

Left atrial (LA) functional analysis has an established role in assessing left ventricular diastolic function. The current standard echocardiographic parameters used to study left ventricular diastolic function include pulsed-wave Doppler mitral inflow analysis, tissue Doppler imaging measurements, and LA dimension estimation. However, the above-mentioned parameters do not directly quantify LA performance. Deformation studies using strain and strain-rate imaging to assess LA function were validated in previous research, but this technique is not currently used in routine clinical practice. This review discusses the history, importance, and pitfalls of strain technology for the analysis of LA mechanics.

Causal Scale of Rotors in a Cardiac System

NASA Astrophysics Data System (ADS)

Ashikaga, Hiroshi; Prieto-Castrillo, Francisco; Kawakatsu, Mari; Dehghani, Nima

2018-04-01

Rotors of spiral waves are thought to be one of the potential mechanisms that maintain atrial fibrillation (AF). However, disappointing clinical outcomes of rotor mapping and ablation to eliminate AF raise a serious doubt on rotors as a macro-scale mechanism that causes the micro-scale behavior of individual cardiomyocytes to maintain spiral waves. In this study, we aimed to elucidate the causal relationship between rotors and spiral waves in a numerical model of cardiac excitation. To accomplish the aim, we described the system in a series of spatiotemporal scales by generating a renormalization group, and evaluated the causal architecture of the system by quantifying causal emergence. Causal emergence is an information-theoretic metric that quantifies emergence or reduction between micro- and macro-scale behaviors of a system by evaluating effective information at each scale. We found that the cardiac system with rotors has a spatiotemporal scale at which effective information peaks. A positive correlation between the number of rotors and causal emergence was observed only up to the scale of peak causation. We conclude that rotors are not the universal mechanism to maintain spiral waves at all spatiotemporal scales. This finding may account for the conflicting benefit of rotor ablation in clinical studies.

Hydrogen Separation by Natural Zeolite Composite Membranes: Single and Multicomponent Gas Transport.

PubMed

Farjoo, Afrooz; Kuznicki, Steve M; Sadrzadeh, Mohtada

2017-10-06

Single and multicomponent gas permeation tests were used to evaluate the performance of metal-supported clinoptilolite membranes. The efficiency of hydrogen separation from lower hydrocarbons (methane, ethane, and ethylene) was studied within the temperature and pressure ranges of 25-600 °C and 110-160 kPa, respectively. The hydrogen separation factor was found to reduce noticeably in the gas mixture compared with single gas experiments at 25 °C. The difference between the single and multicomponent gas results decreased as the temperature increased to higher than 300 °C, which is when the competitive adsorption-diffusion mechanism was replaced by Knudsen diffusion or activated diffusion mechanisms. To evaluate the effect of gas adsorption, the zeolite surface isotherms of each gas in the mixture were obtained from 25 °C to 600 °C. The results indicated negligible adsorption of individual gases at temperatures higher than 300 °C. Increasing the feed pressure resulted in a higher separation efficiency for the individual gases compared with the multicomponent mixture, due to the governing effect of the adsorptive mechanism. This study provides valuable insight into the application of natural zeolites for the separation of hydrogen from a mixture of hydrocarbons.

Hydrogen Separation by Natural Zeolite Composite Membranes: Single and Multicomponent Gas Transport

PubMed Central

Farjoo, Afrooz; Kuznicki, Steve M.

2017-01-01

Single and multicomponent gas permeation tests were used to evaluate the performance of metal-supported clinoptilolite membranes. The efficiency of hydrogen separation from lower hydrocarbons (methane, ethane, and ethylene) was studied within the temperature and pressure ranges of 25–600 °C and 110–160 kPa, respectively. The hydrogen separation factor was found to reduce noticeably in the gas mixture compared with single gas experiments at 25 °C. The difference between the single and multicomponent gas results decreased as the temperature increased to higher than 300 °C, which is when the competitive adsorption–diffusion mechanism was replaced by Knudsen diffusion or activated diffusion mechanisms. To evaluate the effect of gas adsorption, the zeolite surface isotherms of each gas in the mixture were obtained from 25 °C to 600 °C. The results indicated negligible adsorption of individual gases at temperatures higher than 300 °C. Increasing the feed pressure resulted in a higher separation efficiency for the individual gases compared with the multicomponent mixture, due to the governing effect of the adsorptive mechanism. This study provides valuable insight into the application of natural zeolites for the separation of hydrogen from a mixture of hydrocarbons. PMID:28984833

Mechanical oscillatory behavior of a C60 fullerene tunneling through open carbon nanocones

NASA Astrophysics Data System (ADS)

Sadeghi, F.; Ansari, R.

2017-07-01

This paper deals with the mechanical oscillatory behavior of a C60 fullerene inside open carbon nanocones (CNCs). The fullerene molecule is assumed to enter the nanocone through its small end or wide end. Following our previously published study, semi-analytical expressions for the evaluation of vdW interactions are presented which facilitate obtaining a formula for oscillation frequency. The equation of motion is numerically solved to attain the time histories of separation distance and velocity of the fullerene molecule. Based on the conservation of the mechanical energy law, a new semi-analytical formula is also derived to accurately evaluate the oscillation frequency of the system. With respect to the present formulation, a detailed parametric study is conducted to gain an insight into the effects of both geometrical parameters (small-end radius, wide-end radius and vertex angle of nanocone) and initial conditions (initial separation distance and initial velocity) on the oscillatory behavior of C60 fullerene-open CNC oscillators. For given geometrical parameters and initial conditions, it is shown that higher oscillation frequencies can be achieved when the fullerene molecule enters the open nanocone through its small end.

Internal fixators: a safe option for managing distal femur fractures?

PubMed Central

Batista, Bruno Bellaguarda; Salim, Rodrigo; Paccola, Cleber Antonio Jansen; Kfuri, Mauricio

2014-01-01

OBJECTIVE: Evaluate safety and reliability of internal fixator for the treatment of intra-articular and periarticular distal femur fractures. METHODS: Retrospective data evaluation of 28 patients with 29 fractures fixed with internal fixator was performed. There was a predominance of male patients (53.5%), with 52% of open wound fractures, 76% of AO33C type fractures, and a mean follow up of 21.3 months. Time of fracture healing, mechanical axis deviation, rate of infection and postoperative complications were registered. RESULTS: Healing rate was 93% in this sample, with an average time of 5.5 months. Twenty-seven percent of patients ended up with mechanical axis deviation, mostly resulting from poor primary intra-operative reduction. There were two cases of implant loosening; two implant breakage, and three patients presented stiff knee. No case of infection was observed. Healing rate in this study was comparable with current literature; there was a high degree of angular deviation, especially in the coronal plane. CONCLUSION: Internal fixators are a breakthrough in the treatment of knee fractures, but its use does not preclude application of principles of anatomical articular reduction and mechanical axis restoration. Level of Evidence II, Retrospective Study. PMID:25061424

Genomics of lactation: role of nutrigenomics and nutrigenetics in the fatty acid composition of human milk.

PubMed

Sosa-Castillo, Elizabeth; Rodríguez-Cruz, Maricela; Moltó-Puigmartí, Carolina

2017-08-01

Human milk covers the infant's nutrient requirements during the first 6 months of life. The composition of human milk progressively changes during lactation and it is influenced by maternal nutritional factors. Nowadays, it is well known that nutrients have the ability to interact with genes and modulate molecular mechanisms impacting physiological functions. This has led to a growing interest among researchers in exploring nutrition at a molecular level and to the development of two fields of study: nutrigenomics, which evaluates the influence of nutrients on gene expression, and nutrigenetics, which evaluates the heterogeneous individual response to nutrients due to genetic variation. Fatty acids are one of the nutrients most studied in relation to lactation given their biologically important roles during early postnatal life. Fatty acids modulate transcription factors involved in the regulation of lipid metabolism, which in turn causes a variation in the proportion of lipids in milk. This review focuses on understanding, on the one hand, the gene transcription mechanisms activated by maternal dietary fatty acids and, on the other hand, the interaction between dietary fatty acids and genetic variation in genes involved in lipid metabolism. Both of these mechanisms affect the fatty acid composition of human milk.

Adverse Effect of Antifouling Compounds on the Reproductive Mechanisms of the Ascidian Ciona intestinalis

PubMed Central

Gallo, Alessandra; Tosti, Elisabetta

2013-01-01

Fertilization and embryo development that occur in sea water are sensitive to xenobiotics from anthropogenic sources. In this work, we evaluated the influence of two antifouling biocides, tributyltin (TBT) and diuron, on the reproductive mechanisms of the marine invertebrate Ciona intestinalis. By using electrophysiological techniques, we examined the impact of these compounds on the electrical properties of the mature oocytes and of events occurring at fertilization. With different toxicity assays, we studied the effect of the two biocides on the gametes by evaluating fertilization rate and embryo development. Results show that sodium (Na+) currents were significantly reduced by either of the two biocides, whereas conductance was significantly increased. The fertilization current frequency and amplitude, fertilization rate and larval development were affected only by TBT. This study suggests that: (i) the two biocides affect either the electrical properties of the oocyte plasma membrane and the reproductive success representing a risk factor for the survival of the species exposed to environmental pollution; (ii) the ascidian Ciona intestinalis may represent a good model organism to test toxicity of marine pollutants. Possible mechanisms of action of the two biocides are discussed. PMID:24065165

Rat Disc Torsional Mechanics: Effect of Lumbar and Caudal Levels and Axial Compression Load

PubMed Central

Elliott, Dawn M; Espinoza Orías, Alejandro A; Malhotra, Neil R

2009-01-01

Background Context Rat models with altered loading are used to study disc degeneration and mechano-transduction. Given the prominent role of mechanics in disc function and degeneration, it is critical to measure mechanical behavior in order to evaluate changes following model interventions. Axial compression mechanics of the rat disc are representative of the human disc when normalized by geometry, and differences between the lumbar and caudal disc have been quantified in axial compression. No study has quantified rat disc torsional mechanics. Purpose Compare the torsional mechanical behavior of rat lumbar and caudal discs, determine the contribution of combined axial load on torsional mechanics, and compare the torsional properties of rat discs to human lumbar discs. Study Design Cadaveric biomechanical study. Methods Cyclic torsion without compressive load followed by cyclic torsion with a fixed compressive load was applied to rat lumbar and caudal disc levels. Results The apparent torsional modulus was higher in the lumbar region than in the caudal region,: 0.081±0.026 (MPa/°, Mean±SD) for lumbar axially loaded; 0.066±0.028 caudal axially loaded; 0.091±0.033 for lumbar in pure torsion; and 0.056±0.035 for caudal in pure torsion. These values were similar to human disc properties reported in the literature ranging from 0.024 to 0.21 MPa/°. Conclusions Use of the caudal disc as a model may be appropriate if the mechanical focus is within the linear region of the loading regime. These results provide support for use of this animal model in basic science studies with respect to torsional mechanics. PMID:18495544

Contribution of facet joints, axial compression, and composition to human lumbar disc torsion mechanics.

PubMed

Bezci, Semih E; Eleswarapu, Ananth; Klineberg, Eric O; O'Connell, Grace D

2018-02-12

Stresses applied to the spinal column are distributed between the intervertebral disc and facet joints. Structural and compositional changes alter stress distributions within the disc and between the disc and facet joints. These changes influence the mechanical properties of the disc joint, including its stiffness, range of motion, and energy absorption under quasi-static and dynamic loads. There have been few studies evaluating the role of facet joints in torsion. Furthermore, the relationship between biochemical composition and torsion mechanics is not well understood. Therefore, the first objective of this study was to investigate the role of facet joints in torsion mechanics of healthy and degenerated human lumbar discs under a wide range of compressive preloads. To achieve this, each disc was tested under four different compressive preloads (300-1200 N) with and without facet joints. The second objective was to develop a quantitative structure-function relationship between tissue composition and torsion mechanics. Facet joints have a significant contribution to disc torsional stiffness (∼60%) and viscoelasticity, regardless of the magnitude of axial compression. The findings from this study demonstrate that annulus fibrosus GAG content plays an important role in disc torsion mechanics. A decrease in GAG content with degeneration reduced torsion mechanics by more than an order of magnitude, while collagen content did not significantly influence disc torsion mechanics. The biochemical-mechanical and compression-torsion relationships reported in this study allow for better comparison between studies that use discs of varying levels of degeneration or testing protocols and provide important design criteria for biological repair strategies. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Efficacy of stapler pharyngeal closure after total laryngectomy: A systematic review.

PubMed

Aires, Felipe T; Dedivitis, Rogério A; Castro, Mario Augusto F; Bernardo, Wanderley Marques; Cernea, Claudio Roberto; Brandão, Lenine Garcia

2014-05-01

Some primary studies compare manual and mechanical pharyngeal closures after total laryngectomy. The purpose of this study was to evaluate the advantages of the mechanical suture in pharyngeal closure. The literature survey included research in MEDLINE, EMBASE, and LILACS. The intervention analyzed was stapler-assisted pharyngeal closure, whereas the control group was manual suture pharyngeal closure. The survey resulted in 319 studies. However, 4 studies were selected (417 patients). In the group of patients in whom the stapler was used, the incidence of pharyngocutaneous fistula was 8.7%, whereas in the other, it was 22.9%, with an absolute risk reduction of 15% (95% confidence interval [CI], 0.02-0.28; p = .02; I(2) = 66%). Regarding the surgical time, the average difference was 80 minutes in favor of the stapler group (95% CI, 23.16-136.58 minutes; p < .006). The difference for starting oral feeding was 8 days in favor of the mechanical suture (95% CI, 4.01-11.73 days; p < .001). Patients who underwent mechanical suture had a shorter hospitalization period. Copyright © 2013 Wiley Periodicals, Inc.

The quality evaluation of frankfurter-type sausages from hand and mechanically deboned turkey meat.

PubMed

Radomyski, T; Niewiarowicz, A

1987-03-01

A quality evaluation was made of frankfurter-type sausages made from hand and mechanically deboned meat from various parts of turkey carcasses. The results led to the conclusions that despite some differences in objective measurements of the sausage quality, mechanically deboned turkey meat can be considered as an exclusive meat raw material for the production of frankfurter-type sausages. The quality of sausages from mechanically deboned turkey meat from wings and frames with skin was the least satisfactory.

Progressing quality control in environmental impact assessment beyond legislative compliance: An evaluation of the IEMA EIA Quality Mark certification scheme

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

Bond, Alan, E-mail: alan.bond@uea.ac.uk; Research Unit for Environmental Sciences and Management, North-West University; Fischer, Thomas B, E-mail: fischer@liverpool.ac.uk

The effectiveness of Environmental Impact Assessment (EIA) systems is contingent on a number of control mechanisms: procedural; judicial; evaluative; public and government agency; professional; and development aid agency. If we assume that procedural and judicial controls are guaranteed in developed EIA systems, then progressing effectiveness towards an acceptable level depends on improving the performance of other control mechanisms over time. These other control mechanisms are either absent, or are typically centrally controlled, requiring public finances; this we argue is an unpopular model in times of greater Government austerity. Here we evaluate a market-based mechanism for improving the performance of evaluativemore » and professional control mechanisms, the UK Institute of Environmental Management and Assessments' EIA Quality Mark. We do this by defining dimensions of effectiveness for the purposes of our evaluation, and by identifying international examples of the approaches taken to delivering the other control measures to validate the approach taken in the EIA Quality Mark. We then evaluate the EIA Quality Mark, when used in combination with legal procedures and an active judiciary, against the effectiveness dimensions and use time-series analysis of registrant data to examine its ability to progress practice. We conclude that the EIA Quality Mark has merit as a model for a market-based mechanism, and may prove a more financially palatable approach for delivering effective EIA in mature systems in countries that lack centralised agency oversight. It may, therefore, be of particular interest to some Member States of the European Union for ensuring forthcoming certification requirements stemming from recent amendments to the EIA Directive. - Highlights: • Quality control mechanisms in EIA are identified. • Effectiveness of EIA is conceptualised for evaluation purposes. • The UK IEMA EIA Quality Mark is introduced as a market-based mechanism. • The EIA Quality Mark is found to progress quality in many, but not all, areas.« less

Development of a problem solving evaluation instrument; untangling of specific problem solving assets

NASA Astrophysics Data System (ADS)

Adams, Wendy Kristine

The purpose of my research was to produce a problem solving evaluation tool for physics. To do this it was necessary to gain a thorough understanding of how students solve problems. Although physics educators highly value problem solving and have put extensive effort into understanding successful problem solving, there is currently no efficient way to evaluate problem solving skill. Attempts have been made in the past; however, knowledge of the principles required to solve the subject problem are so absolutely critical that they completely overshadow any other skills students may use when solving a problem. The work presented here is unique because the evaluation tool removes the requirement that the student already have a grasp of physics concepts. It is also unique because I picked a wide range of people and picked a wide range of tasks for evaluation. This is an important design feature that helps make things emerge more clearly. This dissertation includes an extensive literature review of problem solving in physics, math, education and cognitive science as well as descriptions of studies involving student use of interactive computer simulations, the design and validation of a beliefs about physics survey and finally the design of the problem solving evaluation tool. I have successfully developed and validated a problem solving evaluation tool that identifies 44 separate assets (skills) necessary for solving problems. Rigorous validation studies, including work with an independent interviewer, show these assets identified by this content-free evaluation tool are the same assets that students use to solve problems in mechanics and quantum mechanics. Understanding this set of component assets will help teachers and researchers address problem solving within the classroom.

Neuropsychological Treatment of Attention Deficit Disorder in Infancy

ERIC Educational Resources Information Center

Solovieva, Yulia; Quintanar, Luis

2017-01-01

The syndrome of attention deficit disorder is one of the most frequent pictures of disabilities in pre-scholars. The present study analyses the results of fulfillment of tasks for mechanisms of control and spatial functions. 14 pre-scholars with attention deficit disorder took part in the study. The neuropsychological evaluation was applied before…

Single particle effects, Biostack, and risk evaluation - Studies on the radiation risk from Galactic cosmic rays

NASA Technical Reports Server (NTRS)

Curtis, Stanley B.

1993-01-01

The possible health risks posed by Galactic cosmic rays, especially the possible heightened cancer risk, are examined. The results of the Biostack studies of the biological effects of high-energy cosmic rays are discussed. The biological mechanisms involved in possible harm due to cosmic rays are considered.

Left Atrial Mechanical Functions in Professional Soccer Players: A Pilot Study

ERIC Educational Resources Information Center

Kartal, Alper; Güngör, Hasan; Kartal, Resat; Ergin, Esin

2017-01-01

Long-term regular exercise is associated with physiologic and morphologic alterations in the heart chambers. The aim of this study to evaluate left atrium (LA) phasic functions in professional football players and compare with control subjects. Left atrial volume was calculated at end-systole (Vmax), end-diastole and pre-atrial contraction by…

Acid Etching and Plasma Sterilization Fail to Improve Osseointegration of Grit Blasted Titanium Implants

PubMed Central

Saksø, Mikkel; Jakobsen, Stig S; Saksø, Henrik; Baas, Jørgen; Jakobsen, Thomas; Søballe, Kjeld

2012-01-01

Interaction between implant surface and surrounding bone influences implant fixation. We attempted to improve the bone-implant interaction by 1) adding surface micro scale topography by acid etching, and 2) removing surface-adherent pro-inflammatory agents by plasma cleaning. Implant fixation was evaluated by implant osseointegration and biomechanical fixation. The study consisted of two paired animal sub-studies where 10 skeletally mature Labrador dogs were used. Grit blasted titanium alloy implants were inserted press fit in each proximal tibia. In the first study grit blasted implants were compared with acid etched grit blasted implants. In the second study grit blasted implants were compared with acid etched grit blasted implants that were further treated with plasma sterilization. Implant performance was evaluated by histomorphometrical investigation (tissue-to-implant contact, peri-implant tissue density) and mechanical push-out testing after four weeks observation time. Neither acid etching nor plasma sterilization of the grit blasted implants enhanced osseointegration or mechanical fixation in this press-fit canine implant model in a statistically significant manner. PMID:22962567

Relationship between fatigue life in the creep-fatigue region and stress-strain response

NASA Technical Reports Server (NTRS)

Berkovits, A.; Nadiv, S.

1988-01-01

On the basis of mechanical tests and metallographic studies, strainrange partitioned lives were predicted by introducing stress-strain materials parameters into the Universal Slopes Equation. This was the result of correlating fatigue damage mechanisms and deformation mechanisms operating at elevated temperatures on the basis of observed mechanical and microstructural behavior. Correlation between high temperature fatigue and stress strain properties for nickel base superalloys and stainless steel substantiated the method. Parameters which must be evaluated for PP- and CC- life are the maximum stress achievable under entirely plastic and creep conditions respectively and corresponding inelastic strains, and the elastic modulus. For plasticity/creep interaction conditions (PC and CP) two more pairs of stress strain parameters must be ascertained.

Investigation on Microstructure and Mechanical Properties of Continuous and Pulsed Current Gas Tungsten Arc Welded alloy 600

NASA Astrophysics Data System (ADS)

Srikanth, A.; Manikandan, M.

2018-02-01

The present study investigates the microstructure and mechanical properties of joints fabricated by Continuous and pulsed current gas tungsten arc welded alloy 600. Welding was done by autogenous mode. The macro examination was carried out to evaluate the welding defects in the weld joints. Optical and Scanning Electron Microscope (SEM) were performed to assess the microstructural changes in the fusion zone. Energy Dispersive Spectroscopy (EDS) analysis was carried to evaluate the microsegregation of alloying elements in the fusion zone. The tensile test was conducted to assess the strength of the weld joints. The results show that no welding defects were observed in the fusion zones of Continuous and Pulsed current Gas Tungsten Arc Welding. The refined microstructure was found in the pulsed current compared to continuous current mode. Microsegregation was not noticed in the weld grain boundary of continuous and pulsed current mode. The pulsed current shows improved mechanical properties compared to the continuous current mode.

Feeding Problems and Their Underlying Mechanisms in the Esophageal Atresia–Tracheoesophageal Fistula Patient

PubMed Central

Mahoney, Lisa; Rosen, Rachel

2017-01-01

Feeding difficulties such as dysphagia, coughing, choking, or vomiting during meals, slow eating, oral aversion, food refusal, and stressful mealtimes are common in children with repaired esophageal atresia (EA) and the reasons for this are often multifactorial. The aim of this review is to describe the possible underlying mechanisms contributing to feeding difficulties in patients with EA and approaches to management. Underlying mechanisms for these feeding difficulties include esophageal dysphagia, oropharyngeal dysphagia and aspiration, and aversions related to prolonged gastrostomy tube feeding. The initial diagnostic evaluation for feeding difficulties in a patient with EA may involve an esophagram, videofluoroscopic imaging or fiberoptic endoscopic evaluation during swallowing, upper endoscopy with biopsies, pH-impedance testing, and/or esophageal motility studies. The main goal of management is to reduce the factors contributing to feeding difficulties and may include reducing esophageal stasis, maximizing reflux therapies, treating underlying lung disease, dilating strictures, and altering feeding methods, routes, or schedules. PMID:28620597

The effect of copper, chromium, and zirconium on the microstructure and mechanical properties of Al-Zn-Mg-Cu alloys

NASA Technical Reports Server (NTRS)

Wagner, John A.; Shenoy, R. N.

1991-01-01

The present study evaluates the effect of the systematic variation of copper, chromium, and zirconium contents on the microstructure and mechanical properties of a 7000-type aluminum alloy. Fracture toughness and tensile properties are evaluated for each alloy in both the peak aging, T8, and the overaging, T73, conditions. Results show that dimpled rupture essentially characterize the fracture process in these alloys. In the T8 condition, a significant loss of toughness is observed for alloys containing 2.5 pct Cu due to the increase in the quantity of Al-Cu-Mg-rich S-phase particles. An examination of T8 alloys at constant Cu levels shows that Zr-bearing alloys exhibit higher strength and toughness than the Cr-bearing alloys. In the T73 condition, Cr-bearing alloys are inherently tougher than Zr-bearing alloys. A void nucleation and growth mechanism accounts for the loss of toughness in these alloys with increasing copper content.

Effect of Friction Stir Process Parameters on the Mechanical and Thermal Behavior of 5754-H111 Aluminum Plates.

PubMed

Serio, Livia Maria; Palumbo, Davide; De Filippis, Luigi Alberto Ciro; Galietti, Umberto; Ludovico, Antonio Domenico

2016-02-23

A study of the Friction Stir Welding (FSW) process was carried out in order to evaluate the influence of process parameters on the mechanical properties of aluminum plates (AA5754-H111). The process was monitored during each test by means of infrared cameras in order to correlate temperature information with eventual changes of the mechanical properties of joints. In particular, two process parameters were considered for tests: the welding tool rotation speed and the welding tool traverse speed. The quality of joints was evaluated by means of destructive and non-destructive tests. In this regard, the presence of defects and the ultimate tensile strength (UTS) were investigated for each combination of the process parameters. A statistical analysis was carried out to assess the correlation between the thermal behavior of joints and the process parameters, also proving the capability of Infrared Thermography for on-line monitoring of the quality of joints.

Fabrication and Physical Evaluation of Gelatin-Coated Carbonate Apatite Foam.

PubMed

Hara, Kanae; Fujisawa, Kenji; Nagai, Hirokazu; Takamaru, Natsumi; Ohe, Go; Tsuru, Kanji; Ishikawa, Kunio; Miyamoto, Youji

2016-08-23

Carbonate apatite (CO₃Ap) foam has gained much attention in recent years because of its ability to rapidly replace bone. However, its mechanical strength is extremely low for clinical use. In this study, to understand the potential of gelatin-reinforced CO₃Ap foam for bone replacement, CO₃Ap foam was reinforced with gelatin and the resulting physical characteristics were evaluated. The mechanical strength increased significantly with the gelatin reinforcement. The compressive strength of gelatin-free CO₃Ap foam was 74 kPa whereas that of the gelatin-reinforced CO₃Ap foam, fabricated using 30 mass % gelatin solution, was approximately 3 MPa. Heat treatment for crosslinking gelatin had little effect on the mechanical strength of the foam. The gelatin-reinforced foam did not maintain its shape when immersed in a saline solution as this promoted swelling of the gelatin; however, in the same conditions, the heat-treated gelatin-reinforced foam proved to be stable. It is concluded, therefore, that heat treatment is the key to the fabrication of stable gelatin-reinforced CO₃Ap foam.

Effect of Friction Stir Process Parameters on the Mechanical and Thermal Behavior of 5754-H111 Aluminum Plates

PubMed Central

Serio, Livia Maria; Palumbo, Davide; De Filippis, Luigi Alberto Ciro; Galietti, Umberto; Ludovico, Antonio Domenico

2016-01-01

A study of the Friction Stir Welding (FSW) process was carried out in order to evaluate the influence of process parameters on the mechanical properties of aluminum plates (AA5754-H111). The process was monitored during each test by means of infrared cameras in order to correlate temperature information with eventual changes of the mechanical properties of joints. In particular, two process parameters were considered for tests: the welding tool rotation speed and the welding tool traverse speed. The quality of joints was evaluated by means of destructive and non-destructive tests. In this regard, the presence of defects and the ultimate tensile strength (UTS) were investigated for each combination of the process parameters. A statistical analysis was carried out to assess the correlation between the thermal behavior of joints and the process parameters, also proving the capability of Infrared Thermography for on-line monitoring of the quality of joints. PMID:28773246