75 research outputs found
Recent Developments and Characterization Techniques in 3D printing of Corneal Stroma Tissue
Corneal stroma has a significant function in normal visual function. The corneal stroma is vulnerable because of being the thickest part of the cornea, as it can be affected easily by infections or injuries. Any problems on corneal stroma can result in blindness. Donor shortage for corneal transplantation is one of the main issues in corneal transplantation. To address this issue, the corneal tissue engineering focuses on replacing injured tissues and repairing normal functions. Currently, there are no available, engineered corneal tissues for widely accepted routine clinical treatment, but new emerging 3D printing applications are being recognized as a promising option. Recent in vitro researches revealed that the biocompatibility and regeneration possessions of 3D-printed hydrogels outperformed conventional tissue engineering approaches. The goal of this review is to highlight the current developments in the characterization of 3D cell-free and bioprinted hydrogels
3D Printed Polycaprolactone/Gelatin/Bacterial Cellulose/Hydroxyapatite Composite Scaffold for Bone Tissue Engineering
Three-dimensional (3D) printing application is a promising method for bone tissue engineering. For enhanced bone tissue regeneration, it is essential to have printable composite materials with appealing properties such as construct porous, mechanical strength, thermal properties, controlled degradation rates, and the presence of bioactive materials. In this study, polycaprolactone (PCL), gelatin (GEL), bacterial cellulose (BC), and different hydroxyapatite (HA) concentrations were used to fabricate a novel PCL/GEL/BC/HA composite scaffold using 3D printing method for bone tissue engineering applications. Pore structure, mechanical, thermal, and chemical analyses were evaluated. 3D scaffolds with an ideal pore size (~300 ”m) for use in bone tissue engineering were generated. The addition of both bacterial cellulose (BC) and hydroxyapatite (HA) into PCL/GEL scaffold increased cell proliferation and attachment. PCL/GEL/BC/HA composite scaffolds provide a potential for bone tissue engineering applications
A novel approach to treat the Thiel-Behnke corneal dystrophy using 3D printed honeycomb-shaped polymethylmethacrylate (PMMA)/Vancomycin (VAN) scaffolds
Thiel-Behnke corneal dystrophy, or honeycomb corneal dystrophy, is an autosomal dominant corneal disorder. Tissue engineering can be a novel approach to regenerate this dystrophy. In this study, the honeycomb geometry of the dystrophy mimicked with a 3D printing technology, and 40% PMMA, 40% PMMA/(0.1, 0.5, 2, and 10)% VAN scaffolds were fabricated with honeycomb geometry. As a result of the biocompatibility test with mesenchymal stem cells (MSCs), it can be said that cells on the scaffolds showed high viability and proliferation for all incubation periods. According to the antibacterial activity results, the 40% PMMA/10% VAN showed antibacterial activity against S. aureous. Mechanical results reported that with the addition of VAN into the 40% PMMA, the tensile strength value increased up to 2% VAN amount. The swelling behaviours of the scaffolds were examined in vitro, and found that the swelling rate increased with a high VAN amount. The release of VAN from the scaffolds showed sustained release behaviour, and it took 13 days to be released entirely from the scaffolds
3D printing of PVA/hexagonal boron nitride/bacterial cellulose composite scaffolds for bone tissue engineering
In this study, a novel Polyvinyl Alcohol (PVA)/Hexagonal Boron Nitride (hBN)/Bacterial Cellulose (BC) composite, bone tissue scaffolds were fabricated using 3D printing technology. The printed scaffolds were characterized by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), tensile testing, swelling behaviour, differential scanning calorimetry (DSC), and in vitro cell culture assay. Results demonstrated that bacterial cellulose addition affected the characteristic properties of the blends. Morphological studies revealed the homogenous dispersion of the bacterial cellulose within the 12 wt%PVA/0.25 wt%hBN matrix. Tensile strength of the scaffolds was decreased with the incorporation of BC and 12 wt%PVA/0.25 wt%hBN/0.5 wt%BC had the highest elongation at break value (93%). A significant increase in human osteoblast cell viability on 3D scaffolds was observed for 12 wt%PVA/0.25 wt%hBN/0.5 wt%BC. Cell morphology on composite scaffolds showed that bacterial cellulose doped scaffolds appeared to adhere to the cells. The present work deduced that bacterial cellulose doped 3D printed scaffolds with well-defined porous structures have considerable potential as a suitable tissue scaffold for bone tissue engineering (BTE)
Kinematics of the East Anatolian Fault Zone between Turkoglu (Kahramanmaras) and Celikhan (Adiyaman), eastern Turkey
Tajik Basin: A composite record of sedimentary basin evolution in response to tectonics in the Pamir
Investigation of a >6âkmâthick succession of Cretaceous to Cenozoic sedimentary rocks in the Tajik Basin reveals that this depocentre consists of three stacked basin systems that are interpreted to reflect different mechanisms of subsidence associated with tectonics in the Pamir Mountains: a Lower to midâCretaceous succession, an Upper CretaceousâLower Eocene succession and an EoceneâNeogene succession. The Lower to midâCretaceous succession consists of fluvial deposits that were primarily derived from the Triassic KarakulâMazar subductionâaccretion complex in the northern Pamir. This succession is characterized by a convexâup (accelerating) subsidence curve, thickens towards the Pamir and is interpreted as a retroarc foreland basin system associated with northward subduction of Tethyan oceanic lithosphere. The Upper Cretaceous to early Eocene succession consists of fineâgrained, marginal marine and sabkha deposits. The succession is characterized by a concaveâup subsidence curve. Regionally extensive limestone beds in the succession are consistent with late stage thermal relaxation and relative seaâlevel rise following lithospheric extension, potentially in response to Tethyan slab rollback/foundering. The Upper Cretaceousâearly Eocene succession is capped by a middle Eocene to early Oligocene (ca. 50â30 Ma) disconformity, which is interpreted to record the passage of a flexural forebulge. The disconformity is represented by a depositional hiatus, which is 10â30 Myr younger than estimates for the initiation of IndiaâAsia collision and overlaps in age with the start of prograde metamorphism recorded in the Pamir gneiss domes. Overlying the disconformity, a >4âkmâthick upper EoceneâNeogene succession displays a classic, coarsening upward unroofing sequence characterized by accelerating subsidence, which is interpreted as a retroâforeland basin associated with crustal thickening of the Pamir during IndiaâAsia collision. Thus, the Tajik Basin provides an example of a longâlived composite basin in a retrowedge position that displays a sensitivity to plate margin processes. Subsidence, sediment accumulation and basinâforming mechanisms are influenced by subduction dynamics, including periods of slabâshallowing and retreat
Investigating P- and S-wave velocity structure beneath the Marmara region (Turkey) and the surrounding area from local earthquake tomography
26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15â20 July 2017
This work was produced as part of the activities of FAPESP Research,\ud
Disseminations and Innovation Center for Neuromathematics (grant\ud
2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud
FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud
supported by a CNPq fellowship (grant 306251/2014-0)
Modelling the Stroop effect: A connectionist approach
A connectionist model, which simulates the operation of prefrontal circuits during Stroop task is proposed. The Stroop test has traditionally been used as a measure of cognitive inhibition. The task is to inhibit an over-learned, habitual response (i.e., reading color words) in favor of an unusual, novel requirement (i.e., naming incongruously printed colors of color words). The longer durations in completing the task indicate an inability to inhibit habitual but contextually inappropriate response tendencies, which is suggestive of a prefrontal dysfunction. The connectionist model is designed adapting artificial neural networks (ANNs) in such a way that each ANN corresponds to a particular neuroanatomic component of the prefrontal circuit which is likely to take part in the execution of the Stroop task. The ability of the proposed model to simulate the normal and the abnormal performance on the Stroop task is tested. The simulation results show that the model is consistent with the clinical data. (c) 2006 Elsevier B.V. All rights reserved
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Reactive diffusive transport of heavy metals in Lake Coeur d'Alene sediments
Lake Coeur d'Alene Basin, Idaho sediments have been heavily enriched with toxic metals, including Cd, Cu, Pb, and Zn, serving as a toxic, mutagenic and carcinogenic source of contaminants. Our focus is to develop a biotic/abiotic diffusive reactive transport model to evaluate the fate, transport, exposure and effects of zinc, lead, and copper in Lake Coeur d'Alene benthic sediments. The model is structured as a multicomponent reactive transport to simulate spatial and temporal distributions of metals in the benthic sediments and their effect on microbial consortia including multiple trophic groups and microbial populations in the benthic sediments. The 1-D inorganic diffusive transport model is coupled to a microbially-mediated redox reaction network which integrates syntrophic consortium biotransformation dynamics accounting for product and metal toxicity inhibition under a diffusive transport regime. The model simulates the mobilization of heavy metals initially sorbed onto hydrous ferric oxides through microbial reductive dissolution of Fe(III) minerals under redox disequilibrium conditions with simultaneous biogenic sulfide production, forming soluble metal (bi)sulfide complexes and insoluble metal sulfide minerals, and the effects of these metals on benthic microbial communities via accounting of dose, where dose is expressed in a novel fashion as a structural variable in the population dynamics of the microbial consortia
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