scholarly journals Growth and Coalescence of γ’-Precipitates in Nickel-Based Alloy 115NC during Slow Cooling for Membrane Manufacturing

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 134
Author(s):  
Christian Voelter ◽  
Joachim Rösler
Keyword(s):  
Morphological Changes ◽  
Three Dimensional ◽  
Selective Extraction ◽  
Small Distance ◽  
Cross Linking ◽  
Porous Structures ◽  
Slow Cooling ◽  
Directional Coarsening ◽  
Nickel Based Alloy ◽  
Basic Approaches

By coarsening of the γ’-precipitates and selective extraction of one of the two existing phases, porous structures can be produced from nickel-based superalloys. There are two basic approaches to achieve a bicontinuous γ/γ’-microstructure—directional and incoherent coarsening. Single crystalline superalloy membranes are produced by the so-called rafting of the microstructure, i.e., directional coarsening. Unlike this process, incoherently coarsened membranes lack a detailed understanding of the mechanisms leading to cross-linking of the precipitates. In this paper, the growth and coalescence of precipitates during initial slow cooling from above the γ’ solvus temperature was studied. In addition to the three-dimensional morphological changes of the precipitates, it is also shown that only little coalescence of the particles occurs despite the high γ’ content and, therefore, their very small distance. The loss of coherency that occurs during this part of coarsening must first advance through further aging before a bicontinuous microstructure is formed.

scholarly journals Nanocellulose-Based Inks—Effect of Alginate Content on the Water Absorption of 3D Printed Constructs

2019 ◽  
Vol 6 (3) ◽  
pp. 65 ◽  
Author(s):  
Eduardo Espinosa ◽  
Daniel Filgueira ◽  
Alejandro Rodríguez ◽  
Gary Chinga-Carrasco
Keyword(s):  
Water Absorption ◽  
Moisture Absorption ◽  
Cellulose Nanofibrils ◽  
Three Dimensional ◽  
Wound Dressings ◽  
Cross Linking ◽  
Porous Structures ◽  
Freeze Dried ◽  
3D Printed ◽  
The Cross

2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNF) were used as ink for three-dimensional (3D) printing of porous structures with potential as wound dressings. Alginate (10, 20, 30 and 40 wt%) was incorporated into the formulation to facilitate the ionic cross-linking with calcium chloride (CaCl2). The effect of two different concentrations of CaCl2 (50 and 100 mM) was studied. The 3D printed hydrogels were freeze-dried to produce aerogels which were tested for water absorption. Scanning Electronic Microscopy (SEM) pictures demonstrated that the higher the concentration of the cross-linker the higher the definition of the printed tracks. CNF-based aerogels showed a remarkable water absorption capability. Although the incorporation of alginate and the cross-linking with CaCl2 led to shrinkage of the 3D printed constructs, the approach yielded suitable porous structures for water and moisture absorption. It is concluded that the 3D printed biocomposite structures developed in this study have characteristics that are promising for wound dressings devices.

scholarly journals Supercritical CO2extraction of porogen phase: An alternative route to nanoporous dielectrics

2004 ◽  
Vol 19 (11) ◽  
pp. 3224-3233 ◽  
Author(s):  
J.A. Lubguban ◽  
S. Gangopadhyay ◽  
B. Lahlouh ◽  
T. Rajagopalan ◽  
N. Biswas ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Selective Extraction ◽  
Porous Structures ◽  
Saxs Data ◽  
3D Images ◽  
X Ray ◽  
X Ray Scattering ◽  
Through Diffusion ◽  
Organosilicate Thin Films ◽  
Poly Propylene

We present a supercritical CO2(SCCO2) process for the preparation of nanoporous organosilicate thin films for ultralow dielectric constant materials. The porous structure was generated by SCCO2extraction of a sacrificial poly(propylene glycol) (PPG) from a nanohybrid film, where the nanoscopic domains of PPG porogen are entrapped within the crosslinked poly(methylsilsesquioxane) (PMSSQ) matrix. As a comparison, porous structures generated by both the usual thermal decomposition (at approximately 450 °C) and by a SCCO2process for 25 and 55 wt% porogen loadings were evaluated. It is found that the SCCO2process is effective in removing the porogen phase at relatively low temperatures (<200 °C) through diffusion of the supercritical fluid into the phase-separated nanohybrids and selective extraction of the porogen phase. Pore morphologies generated from the two methods are compared from representative three-dimensional (3D) images built from small-angle x-ray scattering (SAXS) data.

scholarly journals Preparation and Characterization of TPP-Chitosan Crosslinked Scaffolds for Tissue Engineering

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3577 ◽  
Author(s):  
Ilaria Silvestro ◽  
Iolanda Francolini ◽  
Valerio Di Lisio ◽  
Andrea Martinelli ◽  
Loris Pietrelli ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Three Dimensional ◽  
Reaction Times ◽  
Chemical Properties ◽  
Biological Properties ◽  
Cross Linking ◽  
Crosslinking Reaction ◽  
Porous Structures ◽  
Factors Affecting ◽  
Physico Chemical

Scaffolds are three-dimensional porous structures that must have specific requirements to be applied in tissue engineering. Therefore, the study of factors affecting scaffold performance is of great importance. In this work, the optimal conditions for cross-linking preformed chitosan (CS) scaffolds by the tripolyphosphate polyanion (TPP) were investigated. The effect on scaffold physico-chemical properties of different concentrations of chitosan (1 and 2% w/v) and tripolyphosphate (1 and 2% w/v) as well as of cross-linking reaction times (2, 4, or 8 h) were studied. It was evidenced that a low CS concentration favored the formation of three-dimensional porous structures with a good pore interconnection while the use of more severe conditions in the cross-linking reaction (high TPP concentration and crosslinking reaction time) led to scaffolds with a suitable pore homogeneity, thermal stability, swelling behavior, and mechanical properties, but having a low pore interconnectivity. Preliminary biocompatibility tests showed a good osteoblasts’ viability when cultured on the scaffold obtained by CS 1%, TPP 1%, and an 8-h crosslinking time. These findings suggest how modulation of scaffold cross-linking conditions may permit to obtain chitosan scaffold with properly tuned morphological, mechanical and biological properties for application in the tissue regeneration field.

Thermal characterization of ABS-Graphene blended three dimensional printed functional prototypes for electro chemical energy storage

2018 ◽  
Vol 1 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Kamaljit Singh Boparai ◽  
Rupinder Singh
Keyword(s):  
Energy Storage ◽  
Structural Changes ◽  
Fused Deposition Modeling ◽  
Morphological Changes ◽  
Three Dimensional ◽  
Thermal Characterization ◽  
Chemical Energy ◽  
Flow Index ◽  
Fused Deposition

This study highlights the thermal characterization of ABS-Graphene blended three dimensional (3D) printed functional prototypes by fused deposition modeling (FDM) process. These functional prototypes have some applications as electro-chemical energy storage devices (EESD). Initially, the suitability of ABS-Graphene composite material for FDM applications has been examined by melt flow index (MFI) test. After establishing MFI, the feedstock filament for FDM has been prepared by an extrusion process. The fabricated filament has been used for printing 3D functional prototypes for printing of in-house EESD. The differential scanning calorimeter (DSC) analysis was conducted to understand the effect on glass transition temperature with the inclusion of Graphene (Gr) particles. It has been observed that the reinforced Gr particles act as a thermal reservoir (sink) and enhances its thermal/electrical conductivity. Also, FT-IR spectra realized the structural changes with the inclusion of Gr in ABS matrix. The results are supported by scanning electron microscopy (SEM) based micrographs for understanding the morphological changes.

scholarly journals Right Ventricular Global and Regional Remodeling in American-Style Football Athletes: A Longitudinal 3D Echocardiographic Study

2021 ◽  
Vol 11 (8) ◽  
pp. 3357
Author(s):  
Amir Hodzic ◽  
Gabriel Bernardino ◽  
Damien Legallois ◽  
Patrick Gendron ◽  
Hélène Langet ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Morphological Changes ◽  
Three Dimensional ◽  
Computational Method ◽  
Physiological Adaptation ◽  
Volumetric Assessment ◽  
American Style ◽  
Few Data ◽  
The Right ◽  
Field Position

Few data exist concerning the right ventricular (RV) physiological adaptation in American-style football (ASF) athletes. We aimed to analyze the RV global and regional responses among ASF-trained athletes. Fifty-nine (20 linemen and 39 non-linemen) ASF athletes were studied before and after inter-seasonal training. During this period, which lasted 7 months, all athletes were exposed to combined dynamic and static exercises. Cardiac longitudinal changes were examined using three-dimensional transthoracic echocardiography. A computational method based on geodesic distances was applied to volumetrically parcellate the RV into apical, outlet, and inlet regions. RV global and regional end-diastolic volumes increased significantly and similarly in linemen and non-linemen after training, with predominant changes in the apex and outlet regions. RV global and regional ejection fractions were preserved. Morphological changes were uniformly distributed among the four cardiac chambers, and it was independent of the field position. Assessment of RV end-diastolic global, inlet and apical volumes showed low intra-observer (3.3%, 4.1%, and 5.3%, respectively) and inter-observer (7%, 12.2%, and 9%, respectively) variability, whereas the outlet regional volumetric assessment was less reproducible. To conclude, ASF inter-seasonal training was associated with a proportionate biventricular enlargement, regardless of the field position. Regional RV analysis allowed us to quantify the amount of exercise-induced remodeling that was larger in the apical and outlet regions.

Televisualization: An Aid To Collaborative Research In Molecular Structure Biology

1998 ◽  
Vol 4 (S2) ◽  
pp. 32-33
Author(s):  
M. F. Schmid ◽  
P. Matsudaira ◽  
M. T. Dougherty ◽  
M. B. Sherman ◽  
C. Henn ◽  
...  
Keyword(s):  
Image Processing ◽  
Actin Filaments ◽  
Collaborative Research ◽  
Horseshoe Crab ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Limulus Polyphemus ◽  
Dimensional Structure ◽  
Cross Linking ◽  
Tilt Series

Collaboration between local microscopists and image processing specialists, and their remote biological colleagues, has been hampered by the difficulty of i) transferring the three-dimensional reconstructions of macromolecules resulting from the cryomicroscopy and image processing, ii) viewing the results in a meaningful way, and iii) communicating the results and the interpretations derived therefrom to each other.The acrosomal process is an intracellular quasi-crystalline organelle in the head of the sperm of the horseshoe crab Limulus polyphemus. It consists of 100 - 130 actin-scruin filaments packed together in a pseudo-hexagonal lattice and is up to 60 μm long with a diameter of 0.1 μm. Scruin-scruin interactions are responsible for cross-linking the actin filaments together in the bundle. Our goal was to reveal interfilament interactions in the bundle. We have taken tilt series images in the electron microscope to reconstruct its three-dimensional structure at 45 Å resolution.

scholarly journals Optically transparent, high-toughness elastomer using a polyrotaxane cross-linker as a molecular pulley

2018 ◽  
Vol 4 (10) ◽  
pp. eaat7629 ◽  
Author(s):  
Hiroaki Gotoh ◽  
Chang Liu ◽  
Abu Bin Imran ◽  
Mitsuo Hara ◽  
Takahiro Seki ◽  
...  
Keyword(s):  
External Force ◽  
Matrix Material ◽  
Three Dimensional ◽  
Cross Linking ◽  
High Toughness ◽  
Dimensional Network ◽  
Cyclic Molecules ◽  
Optically Transparent ◽  
The Matrix ◽  
Special Challenge

An elastomer is a three-dimensional network with a cross-linked polymer chain that undergoes large deformation with a small external force and returns to its original state when the external force is removed. Because of this hyperelasticity, elastomers are regarded as one of the best candidates for the matrix material of soft robots. However, the comprehensive performance required of matrix materials is a special challenge because improvement of some matrix properties often causes the deterioration of others. For example, an improvement in toughness can be realized by adding a large amount of filler to an elastomer, but to the impairment of optical transparency. Therefore, to produce an elastomer exhibiting optimum properties suitable for the desired purpose, very elaborate, complicated materials are often devised. Here, we have succeeded in creating an optically transparent, easily fabricated elastomer with good extensibility and high toughness by using a polyrotaxane (PR) composed of cyclic molecules and a linear polymer as a cross-linking agent. In general, elastomers having conventional cross-linked structures are susceptible to breakage as a result of loss of extensibility at high cross-linking density. We found that the toughness of the transparent elastomer prepared using the PR cross-linking agent is enhanced along with its Young’s modulus as cross-linking density is increased.

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