Fluid dynamics of flow through microscale lattice structures formed from self‐propagating photopolymer waveguides

The fluid dynamics of flow through microscale lattice structures is characterized for different unit cell sizes, flow angles, and flow rates. The structures consist of an octahedral‐type periodic unit cell, which is formed from an interconnected pattern of self‐propagating photopolymer waveguides. The periodic unit cell of each sample has a node‐to‐node spacing between 800 and 2400 μm and a truss member diameter between 148 and 277 μm. Water is directed through the microscale lattice structures, and the resulting pressure drop is investigated for two different flow angles and superficial flow rates between 0.5 and 4.8 L/min. Finite element analysis is used to determine pressure drop in the laminar flow regime. The results are used to develop a correlation describing friction factor as a function of flow direction, geometric characteristics, and Reynolds number. This work enables control of the fluid dynamics in microarchitected multifunctional truss materials through design and superficial flow angle. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

γ-(S)-Guanidinylmethyl-Modified Triplex-Forming Peptide Nucleic Acids Increase Hoogsteen-Face Affinity for a MicroRNA and Enhance Cellular Uptake

γ-Modified (i.e., (S)-aminomethyl, (S)-acetamidomethyl, (R)-4-(hydroxymethyl)triazol-1-ylmethyl, and (S)-guanidinylmethyl) triplex-forming peptide nucleic acids (TFPNAs) were synthesized and the effect of the backbone modifications on the binding to a miR-215 model was studied. Among the modifications, an appropriate pattern of three γ-(S)-guanidinylmethyl modifications increased the affinity and Hoogsteen-face selectivity for the miR-215 model without ternary (PNA)₂/RNA complex formation. Moreover, the γ-(S)-guanidinylmethyl groups were observed to facilitate internalization of the TFPNAs into living PC-3 prostate cancer cells.     

A hybrid GA-AUGMECON method to solve a cubic cell formation problem considering different worker skills

Part quality and consequently customer satisfaction besides cost functions are two of the most important issues for any firm. Balancing between these two goals leads to full utilization from manufacturing resources. Formerly, in cubic cell formation problem, where a part on a machine can be processed by various workers, worker assignment was done just by minimizing inter-cell movement criterion; so, the workers assigned into the processing cell are mostly selected rather than outsider workers. But, it is rational for the ties to be broken by skills of different workers in performing a special part on the dedicated machine. In this paper, a bi-objective cubic cell formation is presented with two non-homogeneous objective functions in order to minimize the inter-cell movements and maximize a part quality index. Quality index for each part is represented through a cubic matrix containing integer values of 1–5 (representing very bad, bad, medium, well and very well), which qualifies the process of part on a specific machine by a specific worker. To solve the problem, a hybrid GA-augmented ε-constraint method (GA-AUGMEON) is developed to reduce time consuming difficulty of AUGMECON method. To validate the model and the GA-AUGMECON algorithm, some randomly generated examples in small and large size are solved.     

Pathological liver segmentation using stochastic resonance and cellular automata

Liver segmentation continues to remain a major challenge, largely due to its intensity complexity with surrounding anatomical structures (stomach, kidney, and heart), high noise level and lack of contrast in pathological computed tomography data. In this paper, we present an approach to reconstructing the liver surface in low contrast computed tomography. The main contributions are: (1) a stochastic resonance based methodology in discrete cosine transform domain is developed to enhance the contrast of pathological liver images, (2) a new formulation is proposed to prevent the object boundary, resulted by cellular automata method, from leaking into the surrounding areas of similar intensity, and (3) a level-set method is suggested to generate intermediate segmentation contours from two segmented slices distantly located in a subject sequence. We have tested the algorithm on real datasets obtained from two sources, Hamad General Hospital and MICCAI Grand Challenge workshop. Both qualitative and quantitative evaluation performed on liver data show promising segmentation accuracy when compared with ground truth data reflecting the potential of the proposed method.     

Superior Alignment of Human iPSC-Osteoblasts Associated with Focal Adhesion Formation Stimulated by Oriented Collagen Scaffold

Human-induced pluripotent stem cells (hiPSCs) can be applied in patient-specific cell therapy to regenerate lost tissue or organ function. Anisotropic control of the structural organization in the newly generated bone matrix is pivotal for functional reconstruction during bone tissue regeneration. Recently, we revealed that hiPSC-derived osteoblasts (hiPSC-Obs) exhibit preferential alignment and organize in highly ordered bone matrices along a bone-mimetic collagen scaffold, indicating their critical role in regulating the unidirectional cellular arrangement, as well as the structural organization of regenerated bone tissue. However, it remains unclear how hiPSCs exhibit the cell properties required for oriented tissue construction. The present study aimed to characterize the properties of hiPSCs-Obs and those of their focal adhesions (FAs), which mediate the structural relationship between cells and the matrix. Our in vitro anisotropic cell culture system revealed the superior adhesion behavior of hiPSC-Obs, which exhibited accelerated cell proliferation and better cell alignment along the collagen axis compared to normal human osteoblasts. Notably, the oriented collagen scaffold stimulated FA formation along the scaffold collagen orientation. This is the first report of the superior cell adhesion behavior of hiPSC-Obs associated with the promotion of FA assembly along an anisotropic scaffold. These findings suggest a promising role for hiPSCs in enabling anisotropic bone microstructural regeneration.     

On the accuracy of diffusion models for life-cycle assessment of concrete structures

In durability analysis and life-cycle assessment of concrete structures transport of chlorides and other aggressive agents is generally described by using Fick’s laws of diffusion. This model is frequently applied in a simplified one-dimensional (1D) form. However, in practical applications the diffusion process is more properly described by two- or three-dimensional patterns of concentration gradients. In this paper, the accuracy of the 1D modelling of diffusion and its impact on the life-cycle assessment of concrete structures under corrosion is evaluated in deterministic and probabilistic terms with respect to more accurate two-dimensional (2D) formulations. The influence of the diffusion modelling on the time-variant corrosion damage of concrete cross-sections is studied with reference to the local damage of the reinforcing steel bars and the global deterioration of bending moment–curvature capacity curves. The results show that 2D diffusion models may be necessary for a realistic life-cycle assessment of concrete structures under corrosion, since 1D models can lead to significant inaccuracies depending on the geometrical aspect ratio of the cross-section, location of reinforcing steel bars and exposure conditions.     

Efficient and reliable fault analysis methodology for nanomagnetic circuits

The increasing issues in scaled Complementary Metal Oxide Semiconductor (CMOS) circuit fabrication favor the flourishing of emerging technologies. Because of their limited sizes, both CMOS and emerging technologies are particularly sensitive to defects that arise during the fabrication process. Their impact is not easy to analyze in order to take the necessary countermeasures, especially in the case of circuits of realistic complexity based on emerging technologies. In this work, we propose a new methodology supported by an efficient and reliable tool for the identification of the impact of faults in complex circuits implemented using the emerging technology we are focusing on in this case: nanomagnetic logic. The methodology is based on three main steps: (i) we performed exhaustive physical‐level simulations of basic blocks based on a detailed finite‐element tool in order to have a full characterization, to know their properties in presence of defects, and to have a solid reference point for the following steps; (ii) we developed a model (fanomag ) for the basic block behavior suitable for simulations in presence of defects of complex circuits, that is, lighter than a physical level one, but accurate enough to capture the most important features to be inherited at circuit level; (iii) starting from a physical design of complex circuits that we perform using a specific design tool we developed, that is, ToPoliNano , we simulated using fanomag , now embedded in our ToPoliNano tool, the behavior of circuits in presence of multiple sets of fabrication defects using a Monte Carlo approach now included in ToPoliNano as a new feature. In this paper, a specific type of defect is considered as a case study. The framework and methodology are conceived to be easily extended to handle other types of defects and problems due to working conditions that a designer and/or a technologist might want to focus on. The major outcome is then a powerful methodology and tool capable to analyze with a good accuracy nanomagnetic logic complex circuits and architectures both in ideal conditions and in presence of defects with remarkable performance in terms of simulation times. Copyright © 2016 John Wiley & Sons, Ltd.     

Modification of PCL Electrospun Nanofibrous Mat With Calendula officinalis Extract for Improved Interaction With Cells

Nanofibers have improved the performance of biomaterials, and could be considered effective. In this study, poly(?-caprolactone) (PCL)/Calendula officinalis nanofibers were well designed by different analyses. FTIR structural analysis showed the presence of functional groups on the nanofibrous surfaces. The SEM images showed the average size of nanofibers increased with increase in Calendula concentration. The 100° difference was obtained in the contact angle analysis with changes in Calendula concentration; however, tensile strength decreased for the Poly(?-caprolactone)/Calendula officinalis nanofibrous mat compared those unmodified ones. Cellular investigation showed better adhesion, proliferation, and tenocyte cells growth on poly(?-caprolactone)/Calendula officinalis nanofibrous samples than pure PCL nanofibrous mat. The bioavailability of PCL fibers with Calendula officinalis extract was found to be identical to that of PCL fibers, indicating that Calendula officinalis extract is a suitable material for enhancing the biocompatibility of tissue engineering scaffolds.     

浅谈选矿厂给排水设计

简单介绍了(有色金属)矿山工程选矿厂给排水设计的重要性,同时对矿山工程选矿厂给排水设计中的水量平衡、生产废水处理、高位水池的设置及回水泵站吸水池的设计提出看法。     

Potential impact of ferroelectric technology for PCS and cellular communications

Abstract

As the cellular and PCS spectrum become increasingly crowded due to the presence of a greater number of subscribers, it will become even more important for handset and base station manufacturers to come up with ways to ensure reliable system performance. In the handsets, the use of tunable filters, along with lower phase noise tunable oscillators, among other things, can help achieve the desired increase in reliability and system performance. It is in these areas where frequency agile components may be best applied. Ferroelectric thin/thick film technology is making significant improvements in reducing dielectric loss and tuning voltage requirements. Thus their application to the development of commercially useful and practical frequency agile components is gaining. This paper will consider some of the potential areas in filtering and tunable oscillator design where ferroelectric materials may be used to an advantage in future generation handsets.