Low Temperature Plasticity of Ultrafine‐Grained AE42 and AZ31 Magnesium Alloys

The low temperature peculiarities of plastic deformation of AZ31 and AE42 magnesium alloys processed by equal‐channel angular pressing (ECAP) were studied in temperature range 0.5–293 K. At 4.2 K and lower, the stress–strain curves become serrated with the jerk stress frequency and amplitude sensitive to the flow stress, temperature and processing history. The yield stress of the samples before and after ECAP is determined by both the grain size refinement and basal texture evolution. The slope of the temperature dependencies of the yield stress is typical for the thermally activated interaction of dislocations with a spectrum of local obstacles. The activation of the dynamic recovery is responsible for the decrease of the work hardening rate of the samples (i) with a temperature increase and (ii) after ECAP.     

A FPGA-based Library for On-Line Signal Processing

A library of on-line arithmetic structures is presented. Their ability to produce and consume the most significant digit first allows subsequent computations to begin earlier, shortens the execution time of variable precision and composite operations, and simplifies interconnection networks which can help preserve high clock rates in large digit-serial designs. More importantly, designers can interconnect individual units without designing intermediate structures to reformat data, a luxury that is currently unavailable to FPGA designers wishing to use bit-serial arithmetic. The on-line structures introduced are small, and can be easily combined to yield more powerful blocks. The library's applicability to signal processing applications is demonstrated with the DFT, DCT, and FIR filter. Results indicate high area efficiency and rapid execution speed.     

Multiscale modeling of circular and elliptical particles in laminar shear flow

Drug delivery systems for cancer prevention and pain management have been improved related to classical cancer chemotherapy. Nanotechnology with nanoparticles offers new ways in transport of drug molecules and contrast agents by the blood flow through the circulatory system. In this study, we use multiscale mesoscopic bridging procedure of the finite elements (FE) coupled with dissipative particle dynamics (DPD) and lattice Boltzmann (LB) method to model the motion of circular and elliptical particles in a 2-D laminar flow. Four examples are considered: 1) one sedimenting cylinder in a channel, 2) two sedimenting cylinders in a channel, 3) motion of four elliptical particles in a linear shear flow, and 4) motion of circular and elliptical particle in the arterial bifurcation geometry. A good agreement with solution from the literature available was found. These results show that the multiscale approach with coupled FE and DPD/LB methods can effectively be applied to model motion of micro/nanoparticles for a drug delivery system.     

ARTreat Project: three-dimensional numerical simulation of plaque formation and development in the arteries

Atherosclerosis is a progressive disease characterized by the accumulation of lipids and fibrous elements in arteries. It is characterized by dysfunction of endothelium and vasculitis, and accumulation of lipid, cholesterol, and cell elements inside blood vessel wall. In this study, a continuum-based approach for plaque formation and development in 3-D is presented. The blood flow is simulated by the 3-D Navier-Stokes equations, together with the continuity equation while low-density lipoprotein (LDL) transport in lumen of the vessel is coupled with Kedem-Katchalsky equations. The inflammatory process was solved using three additional reaction-diffusion partial differential equations. Transport of labeled LDL was fitted with our experiment on the rabbit animal model. Matching with histological data for LDL localization was achieved. Also, 3-D model of the straight artery with initial mild constriction of 30% plaque for formation and development is presented.     

Examination of glycan profiles from IgG-depleted human immunoglobulins facilitated by microscale affinity chromatography

Among the most important proteins involved in disease and healing processes are the immunoglobulins (Igs). Although many of the Igs have been studied through proteomics, aside from IgG, immunoglobulin carbohydrates have not been extensively characterized in different states of health. It seems valuable to develop techniques that permit an understanding of changes in the structures and abundances of Ig glycans in the context of disease onset and progression. We have devised a strategy for characterization of the glycans for the Ig classes other than IgG (i.e., A, D, E, and M) that contain kappa light chains that requires only a few microliters of biological material. First, we designed a microcolumn containing recombinant Protein L that was immobilized on macroporous silica particles. A similarly designed Protein G microcolumn was utilized to first perform an online depletion of the IgG from the sample, human blood serum, and thereby facilitate enrichment of the other Igs. Even though only 3 μL of serum was used in these analyses, we were able to recover a significantly enriched fraction of non-IgG immunoglobulins. The enrichment properties of the Protein L column were characterized using a highly sensitive label-free quantitative proteomics LC-MS/MS approach, and the glycomic profiles of enriched immunoglobulins were measured by MALDI-TOF MS. As a proof of principle, a comparative study was conducted using blood serum from a small group of lung cancer patients and a group of age-matched cancer-free individuals to demonstrate that the method is suitable for investigation of glycosylation changes in disease. The results were in agreement with a glycomic investigation of whole blood serum from a much larger lung cancer cohort.     

Desktop 3-axis parallel kinematic milling machine

Parallel kinematic machines (PKM) are still a research-and-development topic in many laboratories although many of them, unfortunately, have no PKM at all. Therefore, the use of a desktop educational 3-axis parallel kinematic milling machine is suggested as a help in the process of acquiring basic experiences in the field of PKM. The developed desktop educational 3-axis parallel kinematic milling machine is based on a newly developed 3-DOF spatial parallel mechanism. This paper describes the structure of the machine, modeling approach, and control and programming system based on PC Linux platform with real-time extension and EMC2 (the Enhanced Machine Controller) software system.     

Localized Sensor Area Coverage with Low Communication Overhead

We propose several localized sensor area coverage protocols for heterogeneous sensors, each with arbitrary sensing and transmission radii. The approach has a very small communication overhead since prior knowledge about neighbor existence is not required. Each node selects a random time out and listens to messages sent by other nodes before the time out expires. Sensor nodes whose sensing area is not fully covered (or fully covered but with a disconnected set of active sensors) when the deadline expires decide to remain active for the considered round and transmit an activity message announcing it. There are four variants in our approach, depending on whether or not withdrawal and retreat messages are transmitted. Covered nodes decide to sleep, with or without transmitting a withdrawal message to inform neighbors about the status. After hearing from more neighbors, active sensors may observe that they became covered and may decide to alter their original decision and transmit a retreat message. Our simulations show a largely reduced message overhead while preserving coverage quality for the ideal MAC/physical layer. Compared to an existing method (based on hello messages followed by retreat ones and where excessive message loss contributed to excessive coverage holes), our approach has shown robustness in a model with collisions and/or a realistic physical layer.     

Atorvastatin Modulates Bile Acid Homeostasis in Mice with Diet-Induced Nonalcoholic Steatohepatitis

Bile acids (BA) play a significant role in the pathophysiology of nonalcoholic steatohepatitis (NASH). The present study evaluates the modulation of bile acid metabolomics by atorvastatin, a cholesterol-lowering agent commonly used to treat cardiovascular complications accompanying NASH. NASH was induced in mice by 24 weeks of consuming a high–saturated fat, high-fructose, and high-cholesterol diet (F), with atorvastatin administered orally (20 mg/kg/day) during the last three weeks. Biochemical and histological analyses confirmed the effectiveness of the F diet in inducing NASH. Untreated NASH animals had significantly reduced biliary secretion of BA and increased fecal excretion of BA via decreased apical sodium-dependent bile salt transporter (Asbt)-mediated reabsorption. Atorvastatin decreased liver steatosis and inflammation in NASH animals consistently with a reduction in crucial lipogenic enzyme stearoyl–coenzyme A (CoA) desaturase-1 and nuclear factor kappa light chain enhancer of activated B-cell pro-inflammatory signaling, respectively. In this group, atorvastatin also uniformly enhanced plasma concentration, biliary secretion and fecal excretion of the secondary BA, deoxycholic acid (DCA). However, in the chow diet–fed animals, atorvastatin decreased plasma concentrations of BA, and reduced BA biliary secretions. These changes stemmed primarily from the increased fecal excretion of BA resulting from the reduced Asbt-mediated BA reabsorption in the ileum and suppression of synthesis in the liver. In conclusion, our results reveal that atorvastatin significantly modulates BA metabolomics by altering their intestinal processing and liver synthesis in control and NASH mice.     

Localized network layer protocols in wireless sensor networks based on optimizing cost over progress ratio

We present a simple framework for designing network layer protocols for sensor networks including localized routing, broadcasting, area coverage, and so on. The framework is general enough and is applicable to a variety of problems, network assumptions, and optimality criteria. Our simple framework is based on optimizing the ratio of the cost of making certain decisions (e.g., selecting a forwarding neighbor for routing) to the progress made in doing so (e.g., reduction in distance to destination). We show how to apply this general guideline for the design of hop count, power awareness, maximal lifetime, beaconless and physical-layer-based routing, minimal energy broadcasting, sensor area coverage, and multicasting protocols. Moreover, we show that in the case of routing, the best known strictly localized position-based techniques are, in almost all cases, special cases of the described general cost-to-progress ratio paradigm.     

Design guidelines for routing protocols in ad hoc and sensor networks with a realistic physical layer

We present guidelines on how to design network layer protocols when the unit disk graph (UDG) model is replaced by a more realistic physical layer model. Instead of merely using the transmission radius in the UDG model, physical, MAC, and network layers share the information about a bit and/or packet reception probability as a function of distance between nodes. We assume that all nodes use the same transmission power for sending messages, and that a packet is received when all its bits are correctly received. The MAC layer reacts to this probabilistic reception information by adjusting the number of acknowledgments and/or retransmissions. We observe that an optimal route discovery protocol cannot be based on a single retransmission by each node, because such a search may fail to reach the destination or find the optimal path. Next, we discuss that gaining neighbor knowledge information with "hello" packets is not a trivial protocol. We describe localized position-based routing protocols that aim to minimize the expected hop count (in case of hop-by-hop acknowledgments and fixed bit rate) or maximize the probability of delivery (when acknowledgments are not sent). We propose a guideline for the design of greedy position-based routing protocols with known destination locations. The node currently holding the message forwards it to a neighbor (closer to the destination than itself) that minimizes the ratio of cost over progress, where the cost measure depends on the assumptions and metrics used, while the progress measures the difference in distances to the destination. We consider two basic medium access layer approaches, with fixed and variable packet lengths. This article serves as a preliminary contribution toward the development of network layer protocols that match the assumptions and criteria already used in simulators and ultimately in real equipment.