scholarly journals Spatial distribution of mechanical properties in Pseudomonas aeruginosa biofilms, and their potential impacts on biofilm deformation

2021 ◽  
Author(s):  
Juan P. Pavissich ◽  
Mengfei Li ◽  
Robert Nerenberg
Keyword(s):  
Mechanical Properties ◽  
Pseudomonas Aeruginosa ◽  
Spatial Distribution

Macroprobe Mode for the Study of Segregation in Steels

1990 ◽  
Vol 48 (2) ◽  
pp. 260-261
Author(s):  
Auclair Gilles ◽  
Benoit Danièle
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
High Performance ◽  
Volume Fraction ◽  
Sheet Steel ◽  
Acquisition Time ◽  
Chemical Information ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Optical Micrographs

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.

Integration of Chemofacies and Rock Mechanical Properties Using Machine Learning Algorithms: Implications for Geomechanics and Hydraulic Fracture Stimulations in Paleozoic Formations, Saudi Arabia

2021 ◽  
Author(s):  
Maaruf Hussain ◽  
Abduljamiu Amao ◽  
Khalid Al-Ramadan ◽  
Sunday Olatunji ◽  
Ardiansyah Negara
Keyword(s):  
Machine Learning ◽  
Mechanical Properties ◽  
Saudi Arabia ◽  
Spatial Distribution ◽  
Chemical Composition ◽  
Rock Strength ◽  
Machine Learning Algorithms ◽  
Unconventional Reservoirs ◽  
Geochemical Properties ◽  
Rock Mechanical Properties

Abstract The knowledge of rock mechanical properties is critical to reducing drilling risk and maximizing well and reservoir productivity. Rock chemical composition, their spatial distribution, and porosity significantly influenced these properties. However, low porosity characterized unconventional reservoirs as such, geochemical properties considerably control their mechanical behavior. In this study, we used chemostratigraphy as a correlation tool to separate strata in highly homogenous formations where other traditional stratigraphic methods failed. In addition, we integrated the chemofacies output and reduced Young's modulus to outline predictable associations between facies and mechanical properties. Thus, providing better understanding of lithofacies-controlled changes in rock strength that are useful inputs for geomechanical models and completions stimulations.

Icequake streaks linked to potential mega-scale glacial lineations beneath an Antarctic ice stream

Geology ◽  
2019 ◽  
Vol 48 (2) ◽  
pp. 99-102
Author(s):  
C. Grace Barcheck ◽  
Susan Y. Schwartz ◽  
Slawek Tulaczyk
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
High Porosity ◽  
Back Projection ◽  
West Antarctica ◽  
S Wave ◽  
Frictional Properties ◽  
Ice Stream ◽  
Bed Materials ◽  
Bed Material

Abstract Icequakes radiating from an ice-stream base provide insights into otherwise difficult to observe sub-kilometer-scale basal heterogeneity. We detect basal icequakes beneath an ∼3-km-wide seismic sensor network installed on the Whillans Ice Plain (WIP) in West Antarctica, and we use S-wave back-projection to detect and locate thousands of basal icequakes occurring over 14 and 21 days in January 2014 and 2015, respectively. We find flow-parallel streaks of basal icequakes beneath the WIP, which we conjecture are related to the presence of mega-scale glacial lineations (MSGLs) indicated by ice-penetrating radar, with at least one streak originating in a local trough adjacent to a MSGL. Patterned basal seismicity can be caused by systematic spatial variation in basal pore pressure, bed-material frictional properties, or both. We interpret these flow-parallel icequake streaks as being due to frictionally heterogeneous bed materials in the presence of a streamlined ice-stream bed: bedform ridges correspond to aseismic, high-porosity deforming till, and some troughs to ephemeral exposures of deeper, seismogenic material such as lodged till or older sediments or rocks. Our results are consistent with MSGL formation by either erosion in troughs to expose deeper seismogenic material, or deposition of aseismic high-porosity till in bedform highs. Our results also suggest that evolving subglacial geomorphology can impact basal traction by reorganizing the spatial distribution of basal materials with varying mechanical properties.

Quantitative Evaluation of The Chemical Composition of γ-γ’Interfaces in Ni Superalloys

2001 ◽  
Vol 7 (S2) ◽  
pp. 264-265
Author(s):  
H. A. Calderon ◽  
M. Benyoucef ◽  
N. Clement
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
Chemical Composition ◽  
Large Volume ◽  
Alloy Composition ◽  
Volume Fraction ◽  
Alloying Elements ◽  
Local Distribution ◽  
Strain Fields ◽  
Ni Alloys

The excellent mechanical properties of Ni based superalloys depend upon the presence of γ’ particles (LI2 structure). Their volume fraction, spatial distribution and size determine the mechanical strength of these alloys. Ni alloys for technological applications make use of large volume fractions of precipitates where processes of coarsening and coalescence take place during service leading in some cases to deterioration of properties. Addition of different alloying elements prevents accelerated coalescence by retarding diffusion and thus improving the mechanical properties of such alloys. Coalescence can also take place under the influence of an applied stress leading to the formation of rafts of the y' phase. For example the microstructure changes during creep deformation, depending on the alloy composition, with the corresponding formation of dislocation networks and rafts of different morphologies [1]. The γ-γ’ interfaces are also different depending on the alloy composition and most likely to the local distribution of alloying elements and their strain fields.

scholarly journals Assessment of the Spatial Distribution of Mechanical Properties of the Tissue of Anterior Abdominal Wall at Maximum Functional Load

2021 ◽  
Vol 6 (3) ◽  
pp. 175-181
Author(s):  
R. B. Lysenko ◽  
◽  
V. I. Lіakhovskyi ◽  
V. R. Lysenko
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
Abdominal Wall ◽  
Transverse Direction ◽  
Anterior Abdominal Wall ◽  
Longitudinal Direction ◽  
Main Group ◽  
Treatment Center ◽  
Control Group ◽  
White Line

The purpose of the study was to investigate the changes in the mechanical properties of the anterior abdominal wall at maximum functional loads. Materials and methods. The study was conducted on 112 volunteers aged 18 to 49 years old who were examined and treated in the surgical department of the Medical Diagnostic and Treatment Center "Medion" Poltava for the period from June 2020 to May 2021. There were 60 women (53.6 %), and 52 (46.4%) men. Volunteers were divided into 2 groups: the main group (n=58), which underwent the analysis of movement and deformation changes of the anterior abdominal wall during maximal abdominal inflation during the examination, and the control group (n=54), which were operated laparoscopically due to the schedule. Results and discussion. The results of the study showed the following changes in the mechanical properties of the tissues of the anterior abdominal wall: the average deformation in the longitudinal direction was 6% in the main group and 12% in the control one; deformations in the transverse direction were 3% in the main group and 8% in the control group; deformation in the longitudinal direction exceeded the deformation in the transverse by 38-54% (on average by 46%); the area of the anterior abdominal wall in the main group increased by 10%, and in the control one – by 22% (on average by 16%). During the studies, the anterior abdominal wall underwent greater stresses in the transverse orientation than in the longitudinal one (anisotropy coefficient ~2). The Young's modulus of anterior abdominal wall in the sagittal plane is defined as 23.5±2.6 kPa, while in the transverse – 42.5±7.0 kPa. The mechanical properties of human anterior abdominal wall tissues differed along and across the white line of the abdomen: the modulus of elasticity of anterior abdominal wall tissues, with the same force of impact, in the longitudinal direction is less than the transverse average of 44% (p >0.05). That is, the longitudinal stiffness of the anterior abdominal wall is lower than the transverse one. The maximum strength of the anterior abdominal wall is across the white line of the abdomen, and the greatest elasticity – along. The anterior abdominal wall in women showed increased elasticity compared to men, while the stiffness of the anterior abdominal wall tissue in men in both directions was statistically significantly higher than in women (p >0.05). Conclusion. Reconstruction of the spatial distribution of the mechanical properties of anterior abdominal wall tissues according to the nature of their deformation at maximum functional loads provides an additional opportunity to assess the biomechanics of anterior abdominal wall. The mechanical properties of the musculo-aponeurotic structures of anterior abdominal wall in humans differ in the longitudinal and transverse directions. They have the greatest elasticity in the longitudinal direction, and the maximum rigidity and strength in the transverse direction. The strength of the anterior abdominal wall tissue in men is higher, and the elasticity is less than in women. Changes in the mechanical anisotropic characteristics of anterior abdominal wall tissues at maximum functional loads should be taken into account when performing the anterior abdominal wall alloplasty technique

Neural-Based Control of Compliant Foils With Spanwise Flexibility

2019 ◽  
Author(s):  
Annika-verena Haecker ◽  
Gabriel N. Carryon ◽  
James L. Tangorra ◽  
Thomas Sattel
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
Sensory Feedback ◽  
Flexural Rigidity ◽  
Swimming Performance ◽  
Coupled System ◽  
Neural Oscillator ◽  
Feedback Signal ◽  
Spatially Varying ◽  
Spanwise Flexibility

Abstract The ability to change the spatial distribution of a compliant foil’s flexural rigidity can enhance the foil’s swimming performance capabilities but pose challenges to neural-based control of these types of foils. The same property that makes these foil’s effective propulsors also makes them challenging to control with a neural oscillator, namely the variation in the mechanical properties will cause the amplitude and phase of the sensory feedback signal to vary depending upon the placement of the sensor. In this study we investigate the effect of sensor placement on the entrainment characteristics of a coupled-system consisting of a neural oscillator driving a series of compliant foils with spanwise flexibility (i.e. spatially varying mechanical properties in the dorsal-ventral direction). We find that acquiring sensory feedback from the foil’s stiff region produces a broader range of frequencies over which entrainment occurs compared to acquiring feedback from the compliant region of a foil. Additionally, we characterize the thrust and lift forces generated by spanwise foils as a function of the foil’s flapping frequency and flexural rigidity.

scholarly journals Soft Liner with antimicrobial activity

2020 ◽  
Author(s):  
Simone Kreve ◽  
Carla Larissa Vidal ◽  
Oswaldo Luiz Alves ◽  
Andréa Cândido dos Reis
Keyword(s):  
Mechanical Properties ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Activity ◽  
Tensile Strength ◽  
Multiple Comparison Test ◽  
Staphyloccocus Aureus ◽  
Soft Liner ◽  
Denture Liners ◽  
Agar Method ◽  
Hardness Values

Objective: To develop a material for denture relining and assess the microbiological and mechanical properties. The proposed liner was obtained through the incorporation of nanostructured silver vanadate (AgVO3) at 0, 1, 2.5, 5, and 10% polyethyl methacrylate (PEMA) containing plasticizer. Methods: Antimicrobial efficacy was evaluated by the Kirby Bauer agar method against Enterococcus faecalis, Pseudomonas aeruginosa, Candida albicans and Staphyloccocus aureus (n = 5); and mechanical properties were also assessed through roughness, such as Shore A hardness and tensile test. The results were analyzed by ANOVA and Tukey’s Multiple Comparison test (α = 0.05). Results: The material with AgVO3 at concentrations of 1% and 2.5% showed antimicrobial activity for E. faecalis, and 5% and 10% groups were effective for E. faecalis, P. aeruginosa and C. albicans. In the 5% group, hardness remained unchanged (p < 0.001). None of the tested concentrations significantly changed the roughness and the tensile strength (P > 0.05). Conclusion: Obtaining the material with antimicrobial potential promoted efficacy against E. faecalis, P. aeruginosa and C. albicans, kept the roughness property unchanged, did not change the adhesion property of the material to polymethyl methacrylate, and it maintained the hardness values compatible with resilient denture liners.

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