Embedded 3D printing in self-healing annealable composites for functional patterning of human neural constructs

Human in vitro models of neural tissue with controllable cellular composition, tunable microenvironment, and defined spatial patterning are needed to facilitate studies of brain development and disease. Towards this end, bioprinting has emerged as a promising strategy. However, precise and programmable printing of extremely soft and compliant materials that are permissive for stem cell differentiation and functional neuronal growth has been a major challenge. Therefore, solutions for engineering structurally and functionally defined human neural constructs remain scarce. Here, we present a modular platform for bioengineering of neuronal networks via direct embedded 3D printing of human stem cells inside Self-Healing Annealable Particle-Extracellular matrix (SHAPE) composites. The approach combines rheological benefits of granular soft microgel supports with the versatile biomimicry of bulk hydrogels to simultaneously enable precise freeform patterning of stem cells, and consequent generation and long-term maintenance of subtype-specific neurons within engineered networks that extend into the bulk of the annealed support. The developed approach further allows multi-ink deposition, live spatial and temporal monitoring of oxygen levels, as well as creation of vascular channels. Due to its modularity, SHAPE biomanufacturing toolbox not only offers a solution for functional modeling of mechanically sensitive neural constructs, but also has potential to be applied to a wide range of biomaterials with different crosslinking mechanisms to model tissues and diseases where recapitulation of complex architectural features and topological cues is essential.

INFLUENCE OF THE MATRIX SHAPE ON THE TECHNOLOGICAL PARAMETERS OF THE DRAWING PROCESS

The results of computer modeling of the drawing of an axisymmetric part in matrices with a cylindrical and conical working part are presented. the influence of the shape of the working part of the matrix on the processes of defect formation and product quality is established.

Differences in Performance of Models for Heterogeneous Cores during Pulse Decay Tests

Shale and fractured cores often exhibit dual-continuum medium characteristics in pulse decay testing. Dual-continuum medium models can be composed of different flow paths, interporosity flow patterns, and matrix shapes. Various dual-continuum medium models have been used by researchers to analyze the results of pulse decay tests. But the differences in their performance for pulse decay tests have not been comprehensively investigated. The characteristics of the dual-permeability model and the dual-porosity model, the slab matrix, and the spherical matrix in pulse decay testing are compared by numerical modeling in this study. The pressure and pressure derivative curves for different vessel volumes, storativity ratios, interporosity flow coefficients, and matrix-fracture permeability ratios were compared and analyzed. The study found that these models have only a small difference in the interporosity flow stage, and the difference in the matrix shape is not important, and the matrix shape cannot be identified by pulse decay tests. When the permeability of the low permeability medium is less than 1% of the permeability of the high permeability medium, the difference between the dual-permeability model and the dual-porosity model can be ignored. The dual-permeability model approaches the pseudo-steady-state model as the interporosity flow coefficient and vessel volume increase. Compared with the dual-porosity model, the dual-permeability model has a shorter horizontal section of the pressure derivative in the interporosity flow stage. Finally, the conclusions were verified against a case study. This study advances the ability of pulse decay tests to investigate the properties of unconventional reservoir cores.

Dispersion of SiO2 Nano Particles on Epoxy Based Polymer Nano Composites and its Characterization

In present work we developed and characterized the thermosetting epoxy polymer nano composites containing different weight percentage (wt. %) of SiO2 nano particles ranging from 1 to 4 wt. % were prepared through solvent casting route. grain analysis, FTIR, shape recovery, impact stress, tensile, flexural strength and hardness were studied. The properties of composites were improved at 3 wt. % SiO2 nano particles, further loading of nano particles beyond 3 wt. % properties goes to suppressed which may depends on the dispersion of particles within matrix. Shape recovery test was done in this epoxy which may open the new gate for low cost shape memory polymer as we can say novelty of this experiment. The distribution and size of nano particles in epoxy based polymer matrix were examined through AFM analysis finally outlined.

PETROGRAPHY FOR ASSESSMENT OF MOULDING COMPOUND OF ANCIENT POTTERY

Ancient ceramics are the valuable artifacts which saves the information about ancient people and their traditions. The process of making pottery is begun with the choosing and preparation of raw clay and temper material and further applying of different techniques (moulding of vessel, decoration etc.) and finally firing. Petrographical analysis of ancient pottery allows to determine the mineralogical composition of ceramic matrix, the features of their technology and to identify the raw mineral sources (Feliu et al. 2004, Papadopoulou et al. 2006, Bastie et al. 2006). Such kind investigations expand the frames of our knowledge about ancient technological traditions in pottery making. The following characteristics could be determined in thin-sections of ceramic shards: nature and features of plastic and aplastic inclusions; textural and optical characteristics of clay matrix; shape, amount and orientation of pores; features of surface treatment, decoration. This information is animportant for understanding of principles of ancient technologies. The different temper materials inside clay matrix such as sand, crushed rocks, organic materials, shells, grog can be identified accurately using petrography. The ceramic structure and characteristics of mineral changes during the firing are indicators of firing temperatures and atmosphere. A distribution of clay particles and porous inside of ceramic matrix is useful for reconstruction of moulding methods. The study of ceramic collection of the same cultural tradition and from the same region using petrography gives the possibility for differentiation of the natural and cultural factors influenced on the choose of raw materials, variations in the ceramic composition and techniques. This method is one the most precise for identification of an import pottery.