Three-dimensional quantitative description of symbiont ultrastructure within the algal layer oftwo members of the lichen family Umbilicariaceae

1992 ◽  
Vol 24 (3) ◽  
pp. 281-297 ◽  
Author(s):  
F. Valladares ◽  
C. Ascaso
Keyword(s):  
Surface Density ◽  
Cellular Structure ◽  
Quantitative Description ◽  
Three Dimensional ◽  
Volume Density ◽  
Lichen Species ◽  
Cellular Structures ◽  
Systematic Sampling ◽  
Protoplast Volume ◽  
Cellular Organelles

AbstractThe ultrastructure of the symbionts within the algal layer of Lasallia hispamca and Umbilicaria spodochroa has been investigated by applying stereological techniques to quantify cellular organelles and structures. The stereological parameters calculated were volume density (Vv) and surface density (Sv). To obtain these parameters for each cellular structure, a systematic sampling of photographic fields of the algal layer for each sample was utilized.Significant differences between the two lichen species with respect to both symbionts were observed. The cellular structures of the photobiont that differed the most between the two lichen species were the chloroplast, which differed by 15°0, in the Vv values and 25°0, in the Sv values, the pyrenoid (as a whole and in the diameter of pyrenoglobuli) and the mitochondria. With respect to the mycobiont, the vacuolar apparatus was of great importance in characterizing the two species, as was to a lesser extent the protoplast volume occupied by concentric bodies.

DESIGN STRATEGY OF THREE-DIMENSIONAL PRINTED CAGES TO REDUCE IMPACT-INDUCED DEBRIS ALONG THE LOAD-TRANSFERRING PATH

2021 ◽  
pp. 2050021
Author(s):  
Shang-Chih Lin ◽  
Yu-Pao Hsu ◽  
Ching-Hsiao Yu ◽  
Chun-Ming Chen ◽  
Po-Quang Chen
Keyword(s):  
Finite Element ◽  
Cellular Structure ◽  
Three Dimensional ◽  
Peak Stress ◽  
Transforaminal Lumbar Interbody Fusion ◽  
Design Strategy ◽  
Cellular Structures ◽  
The Finite Element Method ◽  
3D Printed ◽  
The Impact

Peri-implant debris certainly lead to osteolysis, necrosis, pseudotumor formation, tissue granulation, fibrous capsule contractions, and even implant failure. For the three-dimensional (3D) printed cage, impaction during cage insertion is one of the most potential sources of fracture debris. A finite-element study was carried out to reduce the impact-induced debris of the 3D-printed cage. This study focused on the design strategy of solid and cellular structures along the load-transferring path. Using the finite-element method, the cellular structure of the transforaminal lumbar interbody fusion (TLIF) cage was systematically modified in the following four variations: a noncellular cage (NC), a fully cellular (FC) cage, a solid cage with a cellular structure in the middle concave (MC) zone, and a strengthened cage (SC) in the MC zone. Three comparison indices were considered: the stresses at the cage-instrument interfaces, in the MC zone, and along the specific load-transferring path. The NC and FC were the least and most highly stressed variations at the cage-instrument interfaces and in the MC zone, respectively. Along the entirely load-transferring path, the FC was still the most highly stressed variation. It showed a higher risk of stress fracture for the FC cage. For the MC and SC, the MC zone was consistently more stressed than the directly impacted zone. The further strengthened design of the SC had a lower peak stress (approximately 29.2%) in the MC zone compared with the MC. Prior to 3D printing, the load-transferring path from the cage-instrument interfaces to the cage-tissue interfaces should be determined. The cage-instrument interfaces should be printed as a solid structure to avoid impact-induced fracture. The other stress-concentrated zones should be cautiously designed to optimize the coexistence strategy of the solid and cellular structures.

The Application of Stereological Methods to the Study of Drug-Induced Changes in Cells

1973 ◽  
Vol 31 ◽  
pp. 536-537
Author(s):  
R.P. Bolender
Keyword(s):  
Cellular Structure ◽  
Structural Information ◽  
Three Dimensional ◽  
Biochemical Data ◽  
Cellular Structures ◽  
Combined Approach ◽  
Drug Induced ◽  
Virtual Absence ◽  
Experimental Pharmacology ◽  
Induced Changes

Ideally, the cell biologist would like to find ways in which morphological and biochemical data can be used synergistically to study cells under normal, experimental, and pathological states. With such a system, it would then be possible to begin to study the intricate relationships of cellular structure to function. The factor limiting such a combined approach has been the virtual absence of quantitative structural information. Fortunately, however, a technique, called stereology, exists which allows one to obtain three dimensional information about cellular structures from 2 dimensional micrographs. This report will demonstrate how these methods can be applied to experimental pharmacology.

scholarly journals Viscoelastic Properties of Cell Structures Manufactured Using a Photo-Curable Additive Technology—PJM

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1895
Author(s):  
Tomasz Kozior ◽  
Czesław Kundera
Keyword(s):  
Viscoelastic Properties ◽  
Cellular Structure ◽  
Material Selection ◽  
Cellular Structures ◽  
Test Results ◽  
Additive Technology ◽  
Polymer Resin ◽  
Cell Structures ◽  
Relaxation Curves ◽  
The Impact

This research paper reviews the test results involving viscoelastic properties of cellular structure models made with the PolyJet Matrix—PJM additive technology. The designed test specimens were of complex cellular structure and made of three various photo-curable polymer resin types. Materials were selected taking into account the so-called “soft” and “tough” material groups. Compressive stress relaxation tests were conducted in accordance with the recommendations of standard ISO 3384, and the impact of the geometric structure shape and material selection on viscoelastic properties, as well as the most favorable geometric variants of the tested cellular structure models were determined. Mathematica and Origin software was used to conduct a statistical analysis of the test results and determine five-parameter functions approximating relaxation curves. The most favorable rheological was adopted and its mean parameters determined, which enables to match both printed model materials and their geometry in the future, to make a component with a specific rheological response. Furthermore, the test results indicated that there was a possibility of modelling cellular structures within the PJM technology, using support material as well.

scholarly journals Preparation and properties of silicone rubber materials with foam/solid alternating multilayered structures

2021 ◽  
Author(s):  
Wenhuan Zhang ◽  
Zhaoping Deng ◽  
Hongwei Yuan ◽  
Shikai Luo ◽  
Huayin Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silicone Rubber ◽  
Cellular Structure ◽  
Cellular Structures ◽  
Compressive Property ◽  
Solid Layer ◽  
Multilayered Structures ◽  
Element Analysis ◽  
Morphology And Mechanical Properties

AbstractIn this paper, silicone rubber materials with foam/solid alternating multilayered structures were successfully constructed by combining the two methods of multilayered hot-pressing and supercritical carbon dioxide (SCCO2) foaming. The cellular morphology and mechanical properties of the foam/solid alternating multilayered silicone rubber materials were systematically studied. The results show that the growth of the cell was restrained by the solid layer, resulting in a decrease in the cell size. In addition, the introduction of the solid layer effectively improved the mechanical properties of the microcellular silicone rubber foam. The tensile strength and compressive strength of the foam/solid alternating multilayered silicone rubber materials reached 5.39 and 1.08 MPa, which are 46.1% and 237.5% of the pure silicone rubber foam, respectively. Finite element analysis (FEA) was applied and the results indicate that the strength and proportion of the solid layer played important roles in the tensile strength of the foam/solid alternating multilayered silicone rubber materials. Moreover, the small cellular structures in silicone rubber foam can provided a high supporting counterforce during compression, meaning that the microcellular structure of silicone rubber foam improved the compressive property compared to that for the large cellular structure of silicone rubber foam.

Control of Hierarchically Ordered Positive and Negative Replicas of Wood Cellular Structures by Surfactant-Directed Sol-Gel Mineralization

2002 ◽  
Vol 726 ◽  
Author(s):  
Yongsoon Shin ◽  
Jun Liu ◽  
Li-Qiong Wang ◽  
Jeong Ho Chang ◽  
William D. Samuels ◽  
...  
Keyword(s):  
Silicic Acid ◽  
Cell Walls ◽  
Cellular Structure ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Silica Particles ◽  
Low Ph ◽  
Cellular Structures ◽  
Inner Surface

AbstractWe here report the synthesis of ordered ceramic materials with hierarchy produced by an in-situ mineralization of ordered wood cellular structures with surfactant-templated sol-gel at different pH. At low pH, a silicic acid is coated onto inner surface of wood cellular structure and it penetrates into pores left, where degraded lignin and hemicellulose are leached out, to form a positive replica, while at high pH the precipitating silica particles due to fast condensation clog the cells and pit structures to form a negative replica of wood. The calcined monoliths produced in different pHs contain ordered wood cellular structures, multi-layered cell walls, pits, vessels well-preserved with positive or negative contrasts, respectively. The surfactant-templated mineralization produces ordered hexagonal nanopores with 20Å in the cell walls after calcination.

scholarly journals Multiscale, thermomechanical topology optimization of self-supporting cellular structures for porous injection molds

2019 ◽  
Vol 25 (9) ◽  
pp. 1482-1492
Author(s):  
Tong Wu ◽  
Andres Tovar
Keyword(s):  
Topology Optimization ◽  
Mechanical Performance ◽  
Mechanical Load ◽  
Design Method ◽  
Three Dimensional ◽  
Optimization Method ◽  
Cellular Structures ◽  
Injection Mold ◽  
Computationally Efficient ◽  
Content Type

Purpose This paper aims to establish a multiscale topology optimization method for the optimal design of non-periodic, self-supporting cellular structures subjected to thermo-mechanical loads. The result is a hierarchically complex design that is thermally efficient, mechanically stable and suitable for additive manufacturing (AM). Design/methodology/approach The proposed method seeks to maximize thermo-mechanical performance at the macroscale in a conceptual design while obtaining maximum shear modulus for each unit cell at the mesoscale. Then, the macroscale performance is re-estimated, and the mesoscale design is updated until the macroscale performance is satisfied. Findings A two-dimensional Messerschmitt Bolkow Bolhm (MBB) beam withstanding thermo-mechanical load is presented to illustrate the proposed design method. Furthermore, the method is implemented to optimize a three-dimensional injection mold, which is successfully prototyped using 420 stainless steel infiltrated with bronze. Originality/value By developing a computationally efficient and manufacturing friendly inverse homogenization approach, the novel multiscale design could generate porous molds which can save up to 30 per cent material compared to their solid counterpart without decreasing thermo-mechanical performance. Practical implications This study is a useful tool for the designer in molding industries to reduce the cost of the injection mold and take full advantage of AM.

scholarly journals Environmentally induced changes in mitochondria and endoplasmic reticulum of Saccharomyces carlsbergensis yeast.

1976 ◽  
Vol 71 (1) ◽  
pp. 123-135 ◽  
Author(s):  
C H Damsky
Keyword(s):  
Endoplasmic Reticulum ◽  
Surface Density ◽  
Volume Density ◽  
Sharp Reduction ◽  
Inner Mitochondrial Membrane ◽  
Large Fluctuations ◽  
Mitochondrial Volume ◽  
Culture Environment ◽  
Induced Changes

The effects of culture environment on the volume density and surface density of mitochondria and endoplasmic reticulum in a facultative yeast were studied. When compared with cells grown aerobically on a nonrepressive substrate, cells grown in the absence of oxygen showed a sharp reduction in both volume density of mitochondria and surface density of the inner mitochondrial membrane (imm) in the remaining mitochondrial profiles. Use of fermentable (repressive) substrates under aerobic conditions restricted the volume density of mitochondria to a much greater extent than the surface density of imm. The range of mitochondrial volume densities in these experiments was 4-11%. Surface density of endoplasmic reticulum (ER) was sensitive to growth rate and in particular to changes in oxygen tension, showing large fluctuations during both anaerobic and aerobic adaptation. These fluctuations in ER are discussed in relation to the known role of this organelle in lipid metabolism.

scholarly journals MILES FORMULAE FOR BOOLEAN MODELS OBSERVED ON LATTICES

2011 ◽  
Vol 28 (2) ◽  
pp. 77 ◽  
Author(s):  
Joachim Ohser ◽  
Werner Nagel ◽  
Katja Schladitz
Keyword(s):  
Mean Curvature ◽  
Surface Density ◽  
Euler Number ◽  
Volume Density ◽  
Random Sets ◽  
Boolean Models ◽  
Intrinsic Volumes ◽  
Binary Images ◽  
Density Surface ◽  
The Mean

The densities of the intrinsic volumes – in 3D the volume density, surface density, the density of the integral of the mean curvature and the density of the Euler number – are a very useful collection of geometric characteristics of random sets. Combining integral and digital geometry we develop a method for efficient and simultaneous calculation of the intrinsic volumes of random sets observed in binary images in arbitrary dimensions. We consider isotropic and reflection invariant Boolean models sampled on homogeneous lattices and compute the expectations of the estimators of the intrinsic volumes. It turns out that the estimator for the surface density is proved to be asymptotically unbiased and thusmultigrid convergent for Boolean models with convex grains. The asymptotic bias of the estimators for the densities of the integral of the mean curvature and of the Euler number is assessed for Boolean models of balls of random diameters. Miles formulae with corresponding correction terms are derived for the 3D case.

scholarly journals Fracture behavior of cellular structures obtained by selective laser melting

2020 ◽  
pp. 35-47
Author(s):  
I. S. Kamantsev ◽  
◽  
Yu. N. Loginov ◽  
S. V. Belikov ◽  
S. I. Stepanov ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Selective Laser Melting ◽  
Fatigue Fracture ◽  
Fracture Resistance ◽  
Cellular Structure ◽  
Fracture Behavior ◽  
Cellular Structures ◽  
Laser Melting ◽  
Cellular Architecture ◽  
Fatigue Fracture Resistance

An example of samples with a cellular architecture, obtained by selective laser melting, is used to study the influence of the building direction of cellular objects on the characteristics of fracture under cyclic loading. The origin of their fracture has been revealed. The mechanism providing increased fatigue fracture resistance of objects which, along with the cellular structure, have anisotropy of properties due to the technological features of their production has been determined.

scholarly journals Three-dimensional detonation cellular structures in rectangular ducts using an improved CESE scheme

2016 ◽  
Vol 25 (11) ◽  
pp. 114702
Author(s):  
Yang Shen ◽  
Hua Shen ◽  
Kai-Xin Liu ◽  
Pu Chen ◽  
De-Liang Zhang
Keyword(s):  
Three Dimensional ◽  
Cellular Structures
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