Computational modelling of hybrid masonry systems

In this work we investigate the seismic strength, behavior, and performance of the hybrid masonry structural system. The computational modeling efforts aim to characterize the inelastic behavior of hybrid masonry panels. In particular, we study the influence of the boundary conditions (gap or no gap, reinforced or bearing contact zone), the story shear, overturning moment, and the influence of the panel aspect ratio. Several computational models with various levels of complexity are used in our study in an effort to identify the simplest model capable of capturing the salient features of these structural systems. A non-linear (plastic) constitutive model for the simulation of masonry is considered; this constitutive model is coupled with a damage mechanics model to simulate both the inelastic deformation of masonry in normal compression and tension and the damage due to cracking and micro-cracking. In what we call type I hybrid masonry, the masonry does not make direct contact with the beams or columns of the steel frame. The frame and the masonry are connected only through connector plates. The hybrid masonry provides many advantages, such as improving the resistance to seismic loads, impeding the extent of the damage in the masonry and so on. There is no gap between beam and masonry for Type II, so the masonry shares the gravity load with the steel frame and benefits from the vertical compression. Type III is an extension of Type II systems with the addition of connectors along the sides of the panel, which resist vertical shear forces. For Type II and Type III hybrid masonry, because the beam is in contact with the masonry, another very important aspect needs to be considered for the numerical simulation: we require a contact formulation capable of modelling the transfer of normal and tangential forces between steel and masonry. Preliminary computational results are presented in this paper that will be in the future correlated with laboratory test results from the large-scale tests done at the University of Illinois at Urbana Champaign

Nonlocal approach for the analysis of damage in hybrid masonry under cyclic loading

Hybrid masonry is a recent technology that facilitates the use of concrete masonry unit blocks in connection with steel components in seismic areas. A continuum damage mechanics formulation is utilized due to the quasi-brittle character of masonry panels. A two scalar damage model that accounts for tension and compression is im- plemented with its local and nonlocal formulation. The nontrivial process of calibrating the parameters is addressed and numerical examples are presented to demonstrate the capabilities of the computational framework utilized

Prospect of aquaponics for the sustainable development of food production in urban

Aquaponics refers to a system that combines aquaculture (raising aquatic animals like fish) with hydroponics (cultivating vegetable plants in water) in a symbiotic environment. This system has great potential as a new industrialised food production approach to meet the needs of rapid urbanisation. An evolutional food production system with high productivity and low resource consumption is desirable. Aquaponics is designed based on excellent ecology recycling system, i.e. the food residues and metabolic products in the effluent of aquaculture are pollutants to the environment; they are also the source of nutrients that can be converted and mineralised via microbial treatment and eventually up taken by plants in the hydroponics section. The effluent of hydroponics section is then recycled as clean water for the aquaculture section. Home-based aquaponics (HA), factory-based aquaponics (FA) and building-based aquaponics (BA) are the typical forms of aquaponics for different urban development. The sustainability of aquaponics practices is evaluated using the “triple-bottomline” approach, which requires assessment of impacts on environmental, economic and societal systems. There is a lack of systematic research and modelling work reported on aquaponics, especially in terms of ecological manipulation. Understanding the conversion of the pollutants in the combined system is essential to achieve the optimal manipulation of ecology for optimal system operation. Future work will focus on the production of pollutants in aquaculture, the conversion and degradation of the pollutants in the microbial treatment section, and uptake of organic nutrients and inorganic salts in the hydroponics section. Development of a model, capable of describing the release of pollutants, conversion and uptake of nutrients and the production of metabolic products, is desirable. The model could be developed based on the mass balance of nutrition, productivity of fish and plants and the environmental factors. The aquaponics system could be simulated and analysed using this model so as to provide an optimal system for the design and implementation of different type of aquaponics

Synthesis, Biological Evaluation and Mechanism Studies of Deoxytylophorinine and Its Derivatives as Potential Anticancer Agents

Previous studies indicated that (+)-13a-(S)-Deoxytylophorinine (1) showed profound anti-cancer activities both in vitro and in vivo and could penetrate the blood brain barrier to distribute well in brain tissues. CNS toxicity, one of the main factors to hinder the development of phenanthroindolizidines, was not obviously found in 1. Based on its fascinating activities, thirty-four derivatives were designed, synthesized; their cytotoxic activities in vitro were tested to discover more excellent anticancer agents. Considering the distinctive mechanism of 1 and interesting SAR of deoxytylophorinine and its derivatives, the specific impacts of these compounds on cellular progress as cell signaling transduction pathways and cell cycle were proceeded with seven representative compounds. 1 as well as three most potent compounds, 9, 32, 33, and three less active compounds, 12, 16, 35, were selected to proform this study to have a relatively deep view of cancer cell growth-inhibitory characteristics. It was found that the expressions of phospho-Akt, Akt, phospho-ERK, and ERK in A549 cells were greater down-regulated by the potent compounds than by the less active compounds in the Western blot analysis. To the best of our knowledge, this is the first report describing phenanthroindolizidines alkaloids display influence on the crucial cell signaling proteins, ERK. Moreover, the expressions of cyclin A, cyclin D1 and CDK2 proteins depressed more dramatically when the cells were treated with 1, 9, 32, and 33. Then, these four excellent compounds were subjected to flow cytometric analysis, and an increase in S-phase was observed in A549 cells. Since the molecular level assay results of Western blot for phospho-Akt, Akt, phospho-ERK, ERK, and cyclins were relevant to the potency of compounds in cellular level, we speculated that this series of compounds exhibit anticancer activities through blocking PI3K and MAPK signaling transduction pathways and interfering with the cell cycle progression

Systematic molecular dynamics study of load, speed, and temperature effects on atomic stick-slip friction

Nanotechnology is leading to rapid development of mechanical components whose structure and function are controlled at the atomic scale. Friction plays a critical role in such devices, and one of the primary challenges for their design is that the moving interfaces often exhibit atomic stick-slip friction. It can be difficult to directly compare stick-slip friction results reported by different groups because the models used vary greatly and reported friction parameters are often not the same. There has been little consistency between trends reported in such studies. We have neither a complete nor a consistent picture of how operating conditions affect atomic stick-slip friction. Therefore, in this paper, we have performed a systematic study on the effects of load, speed, and temperature. We predict their effects both individually and in combination to clearly explain the role they play in atomic stick-slip and provide a fundamental understanding of why those dependencies exist. We performed molecular dynamics simulation of an Ag tip sliding on a Cu substrate. The interactions between all atoms in the simulation were modeled using EAM potentials which were recently developed based on first-principles data and fitting to experiment. All simulations were performed using the IMD molecular dynamics simulation package. The simulations were run in the NVT ensemble with the temperature control being performed using a Nos´e-Hoover thermostat. We performed simulations at sliding velocities of 1, 5, and 10 m/s, average normal stresses of 0, 100, 200, 300, 400, and 500 MPa, and temperatures of 10, 100, 200, 300 and 400 K. Simulations were run for all possible combinations of the loads, speeds and temperatures specified above. We then determined the average, minimum and maximum values of the shear stress as functions of velocity, load, and temperature. The atom diffusion was also investigated to show what happened during stick-slip under different operational conditions. Finally, the dislocation theory was used to explain the stick-slip. The common neighbor method (CNA) was used to show the crystal structure alternating between face center cubic (FCC) hexagonal close packed (hpc). The displacement and shear stress were measured in the contact area to show why and how the stick-slip happened

Computational modelling of hybrid masonry systems

In this work we investigate the seismic strength, behavior, and performance of the hybrid masonry structural system. The computational modeling efforts aim to characterize the inelastic behavior of hybrid masonry panels. In particular, we study the influence of the boundary conditions (gap or no gap, reinforced or bearing contact zone), the story shear, overturning moment, and the influence of the panel aspect ratio. Several computational models with various levels of complexity are used in our study in an effort to identify the simplest model capable of capturing the salient features of these structural systems. A non-linear (plastic) constitutive model for the simulation of masonry is considered; this constitutive model is coupled with a damage mechanics model to simulate both the inelastic deformation of masonry in normal compression and tension and the damage due to cracking and micro-cracking. In what we call type I hybrid masonry, the masonry does not make direct contact with the beams or columns of the steel frame. The frame and the masonry are connected only through connector plates. The hybrid masonry provides many advantages, such as improving the resistance to seismic loads, impeding the extent of the damage in the masonry and so on. There is no gap between beam and masonry for Type II, so the masonry shares the gravity load with the steel frame and benefits from the vertical compression. Type III is an extension of Type II systems with the addition of connectors along the sides of the panel, which resist vertical shear forces. For Type II and Type III hybrid masonry, because the beam is in contact with the masonry, another very important aspect needs to be considered for the numerical simulation: we require a contact formulation capable of modelling the transfer of normal and tangential forces between steel and masonry. Preliminary computational results are presented in this paper that will be in the future correlated with laboratory test results from the large-scale tests done at the University of Illinois at Urbana Champaign

Neutrophil-Mediated Delivery of Therapeutic Nanoparticles across Blood Vessel Barrier for Treatment of Inflammation and Infection

Endothelial cells form a monolayer in lumen of blood vessels presenting a great barrier for delivery of therapeutic nanoparticles (NPs) into extravascular tissues where most diseases occur, such as inflammation disorders and infection. Here, we report a strategy for delivering therapeutic NPs across this blood vessel barrier by nanoparticle in situ hitchhiking activated neutrophils. Using intravital microscopy of TNF-α-induced inflammation of mouse cremaster venules and a mouse model of acute lung inflammation, we demonstrated that intravenously (iv) infused NPs made from denatured bovine serum albumin (BSA) were specifically internalized by activated neutrophils, and subsequently, the neutrophils containing NPs migrated across blood vessels into inflammatory tissues. When neutrophils were depleted using anti-Gr-1 in a mouse, the transport of albumin NPs across blood vessel walls was robustly abolished. Furthermore, it was found that albumin nanoparticle internalization did not affect neutrophil mobility and functions. Administration of drug-loaded albumin NPs markedly mitigated the lung inflammation induced by LPS (lipopolysaccharide) or infection by Pseudomonas aeruginosa. These results demonstrate the use of an albumin nanoparticle platform for in situ targeting of activated neutrophils for delivery of therapeutics across the blood vessel barriers into diseased sites. This study demonstrates our ability to hijack neutrophils to deliver nanoparticles to targeted diseased sites