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Mechanical Properties of Stem Cells from Different Sources During Vascular Smooth Muscle Cell Differentiation
Get PDFVascular smooth muscle cells (VSMCs) play an important role in regulating blood flow and pressure by contracting and relaxing in response to a variety of mechanical stimuli. A fully differentiated and functional VSMC should have both the ability to contract and relax in response to environmental stimuli. In addition, it should have the proper mechanical properties to sustain the mechanically active vascular environment. Stem cells can differentiate towards VSMC lineages and so could be used as a potential treatment for vascular repair. However, few studies have assessed the time it takes for stems cells to acquire similar mechanical property to native VSMCs during differentiation. In our study, changes in the mechanical properties of differentiating bone marrow and adipose-derived stem cells were determined by using atomic force microscopy indentation. Overall, bone marrow derived stem cells achieved higher elastic moduli than adipose tissue derived stem cell during differentiation. Immunofluorescence shows that both stem cell types have increasing VSMC-specific markers over differentiation. While adipose-derived stem cells were softer, they expressed slightly higher αSMA than the bone marrow cells as investigated by RT-PCR. Further investigations are required to better determine the appropriate mechanical environment for vascular smooth muscle differentiation
Encapsulation of Bacterial Metabolic Infiltrates Isolated from Different Bacillus Strains in Chitosan Nanoparticles as Potential Green Chemistry-Based Biocontrol Agents against Radopholus similis
Get PDFCurrently there is a trend towards reducing the use of agrochemicals in developing countries. However, they are still being applied intensively in tropical countries. Thus, there is a trend towards developing new products based on natural chemicals for pest control, leading to second-generation pesticides incorporating nano- and biotechnologies. Costa Rica is one of the largest producers of bananas in the world. One of the most important pests of banana and plantain crops is the burrowing nematode, Radopholus similis (Cobb) Thorne. Highly toxic chemical compounds have traditionally been used to control this specific pest in banana plants, which can have dangerous effects on the environment and living beings as well. Biological control agents (BCA) like Bacillus isolated from nematode suppressive soils, in combination with nano- and biotechnological approaches, are gaining attention in the National Banana Corporation (CORBANA), as this plague generates great economic losses for the country. In order to perform encapsulation of active banana nematode biocontrol agents, we have been applying biopolymer carrier agents, such as chitosan and alginate, due to their recognized biocompatibility, biodegradability and low toxicity. Therefore, we have developed innovative formulations based on green chemistry approaches for encapsulating bacterial metabolic infiltrates (BMI) from four different Bacillus strains in order to improve the persistence and spread of these biocontrol agents in the soil and, consequently, becoming an effective pest control for banana plantations
Synthesis and Reinforcement of Thermostable Polymers Using Renewable Resources
Get PDFVegetable oils are being used for the production of biodegradable polymers, opening new possibilities for the synthesis of greener materials that could compete in national markets with petroleum-based polymers. In this study, castor oil and a catalyst (cobalt[II] naphtenate as promotor and MEKP as initiator) from local stores and styrene in different ratios were used to produce thermostable polymers. The kinetics of the polymerization reaction was followed by infrared spectroscopy. A polymeric material was synthetized which presents good mechanical properties. Therefore, composites were produced using 1 wt% of microcellulose extracted from biomass waste as reinforcement or 1 wt% microsilica to improve the mechanical properties. The microfillers showed an improvement in the properties of composites by showing an increase in the Young’s modulus. This easy production method can be suitable for small and medium companies who are trying to embrace responsible environmental consciousness
Uniform Query Framework for Relational and NoSQL Databases
Get PDFAs the data managed by applications has evolved over the years with the arrival of Web 2.0, a large number of new databases have been developed to manage various types of data. While the traditional relational databases continue to exist, NoSQL databases which are document oriented or key-value stores or columnar continue to evolve and are embraced very rapidly across the industry. It is not just the type of data handled by these databases that is different but also the query language they use is also different. This paper talks about a uniform query framework that can be used for traditional relational databases and NoSQL databases. This query framework can also perform joins, aggregates, filter on data from various data sources in a single query
Research on Instability Mechanism and Type of Ore Pillar based on the Fold Catastrophe Theory
Get PDFThe stability of ore pillar in mine is essential for the safe and efficient mining. Based on the energy evolvement rule in ore pillar and roadway roof system, the roadway roof and ore pillar are treated as energy release body and energy dissipation body, respectively. Therefore, the double-block mechanical model is established with energy dissipation body and energy release body, and the energy mechanism of ore pillar instability is obtained, based on the fold catastrophe mathematical theory. The research result indicates that the dynamic instability of ore pillar is a physical instability problem caused by the strain softening property of ore mass, and the instability type of ore pillar is determined by the stiffness parameter of double-block mechanical system. When the systematical stiffness parameter is greater than or equal to 1, the equilibrium position of double-block mechanical system passes through shaft K-1 or the origin, from branch 1 of unstable equilibrium state to branch 2 of stable equilibrium state by smooth transition, and the ore pillar shows quasi-static fracture. When the systematical stiffness parameter is less than 1, the equilibrium position of double-block system mutates from branch 1 of unstable equilibrium state to branch 2 of stable equilibrium state by jumping transition, and the ore pillar shows dynamic instability. The research result could provide theoretical guidance for the prevention measures of ore pillar instability
RETRACTED: The Stable Explicit Time Stepping Analysis with a New Enrichment Scheme by XFEM
No full textThe manuscript titled “The Stable Explicit Time Stepping Analysis with a New Enrichment Scheme by XFEM,” has been retracted from the Computer Modeling in Engineering & Sciences (CMES), vol. 113, no. 4. Retraction of this article is made upon the request of the authors, Xue-cong Liu, Qing Zhang, and Xiao-zhou Xia. The authors submitted their manuscript on October 7, 2017, and the authors later made a separate request to withdraw their submission when it was still being reviewed. Due to the glitches of the old submission system and failed communications between the managing editor and the corresponding author, the withdraw request was not properly and promptly received by the editor. As a result, the manuscript successfully passed a vigorous peer-review process, and got accepted for publication in CMES. To set the record straight, we hereby announce the retraction of the paper, and would like to sincerely apologize to our readers for any inconvenience this may have caused. Tech Science Press is fully committed to enforce strict ethical policies and maintain the highest possible publication standards. A new submission system (www.tspsubmission.com) was officially launched which shall facilitate authors to submit and manage their submissions, and also enable our editors and reviewers to better manage and process manuscripts submitted to the journals that we publish. As a side note, we strongly recommend authors use mainstream and reliable email services (e.g., Gmail, Hotmail and Outlook and alike) for future correspondences to avoid any hassles and problems, as the case in this incident
Numerical Simulation of Thermosolutal Convective Transitions in a Very Narrow Porous Annulus under the Influence of Lewis Number
No full textThis paper reports on the natural convection within a very narrow horizontal annular cavity filled with a porous medium saturated by a binary fluid. The main objective of this study is the identification of the effect of Lewis number on the flow structure and on the heat and mass transfer rates, in a cavity of very small radius ratio R=1.05, in the case of equal buoyancy forces (N=1), for a Rayleigh number Ra=50. The dimensionless governing equations were solved by the centered Finite Difference method using the ADI scheme. Several multicellular flows appear during the variation of the Lewis number, resulting in a direct impact on the heat and solutal transfer rates
Improved Teaching-Learning-Based Optimization Algorithm for Modeling NO<sub>X</sub> Emissions of a Boiler
No full textAn improved teaching-learning-based optimization (I-TLBO) algorithm is proposed to adjust the parameters of extreme learning machine with parallel layer perception (PELM), and a well-generalized I-TLBO-PELM model is obtained to build the model of NOX emissions of a boiler. In the I-TLBO algorithm, there are four major highlights. Firstly, a quantum initialized population by using the qubits on Bloch sphere replaces a randomly initialized population. Secondly, two kinds of angles in Bloch sphere are generated by using cube chaos mapping. Thirdly, an adaptive control parameter is added into the teacher phase to speed up the convergent speed. And then, according to actual teaching-learning phenomenon of a classroom, students learn some knowledge not only by their teacher and classmates, but also by themselves. Therefore, a self-study strategy by using Gauss mutation is introduced after the learning phase to improve the exploration ability. Finally, we test the performance of the I-TLBO-PELM model. The experiment results show that the proposed model has better regression precision and generalization ability than eight other models
Analysis of High-Cr Cast Iron/Low Carbon Steel Wear-resistant Laminated Composite Plate Prepared by Hot-rolled Symmetrical Billet
No full textThis study developed a new technology for preparing high-chromium cast iron (HCCI)/low-carbon steel (LCS) wear-resistant composite plates by hot rolling at a 1050 °C and a rolling speed of 0.2 m/s. The effects of different rolling reductions (30%, 45%, and 60%) on the microstructure (interface and HCCI layer) and mechanical properties (bonding strength, hardness, and wear resistance) of the composite plate were studied. SEM images showed that when the reduction was increased, no impurities and interlayers were found between the microscopic interfaces after hot rolling, and the bonding interface exhibited a wave-like shape. EDS analysis showed that the Cr element diffusion between two metals after hot rolling was promoted when the reduction was increased, thereby improving the bonding quality under the same rolling temperature and rolling speed. Experiments showed that due to the stress release effect of the LCS of the cladded layer, the macro-slab shape after hot rolling performed well, and the brittle HCCI layer underwent thermoplastic deformation without cracking. Moreover, the increase of rolling reduction improved the bonding quality. As the rolling reduction was increased, the volume fraction of Cr-carbides in the HCCI layer also increased, resulting in an increase of hardness and wear-resistance
Rotational Effects on Magneto-Thermoelastic Stoneley, Love and Rayleigh Waves in Fibre-Reinforced Anisotropic General Viscoelastic Media of Higher Order
Get PDFIn this paper, we investigated the propagation of the rmo elastic surface waves in fibre-reinforced anisotropic general viscoelastic media of higher order ofnth order, including time rate of strain under the influence of rotation.The general surface wave speed is derived to study the effects of rotation and thermal on surface waves. Particular cases for Stoneley, Love and Rayleigh waves are discussed. The results obtained in this investigation are more general in the sense that some earlier published results are obtained from our result as special cases. Our results for viscoelastic of order zero are well agreed to fibre-reinforced materials. Comparison was made with the results obtained in the presence and absence of rotation and parameters for fibre-reinforced of the material medium. It is also observed that, surface waves cannot propagate in a fast rotating medium. Numerical results for particular materials are given and illustrated graphically. The results indicate that the effect of rotation on fibre-reinforced anisotropic general viscoelastic media are very pronounced