Piezoelectric properties of noncovalently functionalized 2D nanomaterials incorporated poly(vinylidene fluoride) nanocomposites

We report here for the first time the role of noncovalently functionalized 2D nanomaterials on the ferroelectric and piezoelectric behavior of poly(vinylidene fluoride) (PVDF) nanocomposites. Graphene oxide (GO), expanded graphite (EG) and hexagonal boron nitride (h-BN) were noncovalently modified via Li-salt of 6-amino hexanoic acid (Li-AHA), denoted as m-GO, m-EG and m-BN, in order to de-agglomerate and de-stack them, which were subsequently incorporated into the PVDF matrix via solution mixing, followed by compression molding. Simultaneously, PVDF nanocomposites with unmodified 0.08 wt% of 2D nanomaterials were also prepared using the same methodology. PVDF/m-BN nanocomposite showed a higher extent of polar phase (~36%) associated with PVDF phase as compared to PVDF/m-GO and PVDF/m-EG nanocomposites. Further, the highest permittivity (~58 at 10⁻¹ Hz) was achieved in PVDF/m-BN nanocomposite, which was also reflected in higher remnant polarization (~61 nC/cm²) and a significantly higher d₃₃ value (~53 pm/V). Moreover, a higher output peak to peak voltage (~13 V) was obtained for the sensor device fabricated from PVDF/m-BN nanocomposite. Thus, the role of Li-AHA-modified 2D nanomaterials in improving the morphology, dielectric, ferroelectric, and piezoelectric characteristics of the PVDF nanocomposites was clearly established.     

Selection of programme slots of television channels for giving advertisement: A graph theoretic approach

The present paper aims at developing a linear time algorithm to find a solution to the ‘maximum weight 1 colouring’ problem for an interval graph with interval weight. This algorithm has been applied to solve the problem that involves selecting different programme slots telecast on different television channels in a day so as to reach the maximum number of viewers. It is shown that all programmes of all television channels can be modelled as a weighted interval graph with interval numbers as weights. The programme slots are taken as the vertices of the graph and if the time durations of two programme slots have non-empty intersection, the corresponding vertices are considered to be connected by an edge. The number of viewers of a programme is taken as the weight of the vertex. In reality, the number of viewers of a programme is not a fixed one; generally, it lies in an interval. Thus, the weights of the vertices are taken as interval numbers. We assume that a company sets the objective of selecting the popular programme in different channels so as to make its commercial advertisement reach the maximum number of viewers. However, the constraint imposed is that all selected programmes are mutually exclusive in respect of time scheduling. The objective of the paper is, therefore, to helps the companies to select the programme slots, which are mutually exclusive with respect to the time schedule of telecasting time, in such a way that the total number of viewers of the selected programme slots rises to the optimum level. It is shown that the solution of this problem is obtained by solving the maximum weight colouring problem on an interval graph. An algorithm is designed to solve this optimization problem using O(n) time, where n represents the total number of programmes of all channels.     

Sensorless control of SRM based on a simple expression of magnetization characteristics

Switched reluctance motors (SRM) have a simpler and more rugged construction than conventional ac motors, and hence are suitable for low‐cost variable‐speed drives in many industrial applications. However, the need to use a traditional position sensor for their control is one of the disadvantages of SRM from the standpoints of cost, size, and reliability. For practical use, there is a need for sensorless drive of SRM. This paper describes position‐sensorless control of SRM based on a simple expression of their nonlinear magnetization characteristics. Successful experiments using a 1.5‐kW, 5400‐rpm SRM with a 6/4 pole configuration have verified the practicability of the proposed sensorless control scheme. © 2001 Scripta Technica, Electr Eng Jpn, 137(2): 52–60, 2001     

Viral infection. I. Regulation of protein synthesis during vaccinia viral infection of animal cells

Regulation of vaccinia viral infection was studied using three animal cell lines: KRC-7 (rat hepatoma), L929 (mouse fibroblast), and CV-1 (African green monkey kidney). KRC-7 is highly enriched in p67, a glycoprotein which protects eIF-2 alpha-subunit from phosphorylation by eIF-2 kinases. We report: (i) At 5 pfu per cell of the virus, KRC-7 is resistant to the virus. Other cells are sensitive. At 25 pfu per cell of the virus, KRC-7 is also sensitive to the virus. After productive viral infection, the cell extracts showed strong p67-DG activity and actively deglycosylated exogenous p67. After p67-deglycosylation, the cell extracts also phosphorylated eIF-2. (ii) The rate of synthesis of a major host protein (approximately 45 kDa) in infected L929 cells measured after 2 h of viral infection declined more than 50%. The rate declined thereafter. The rate of synthesis of host proteins in viral-resistant KRC-7 cells (infected with 5 pfu per cell of the virus) remained unchanged. The mechanism of resistance of KRC7 cells to vacinia virus at 5 pfu per cell of the virus was investigated. The p67 level in these cells was varied by growing the cells under different physiological conditions such as serum starvation and expression of p67-sense and p67-antisense DNA. At low p67 level in the cells, p67-DG is activated. This deglycosylates p67 and inactivates p67. This accompanies eIF-2 phosphorylation and shutoff of host protein synthesis. At high p67 level in the cells, activation of p67-DG is prevented. This prevents shut-off of host protein synthesis and viral growth.     

用工业煤气生产钢铁的环境改善和价格作用

历史上钢铁工业就是一个高能耗和影响环境的部门.在这个工业部门目前的工艺在不断提高,而且还会有较大改进.许多已实现的和待采用的革新仍受到制约,采用工业气体的技术也受到制约.工业气体对减少能量需求,减弱对环境的影响和改善整个钢铁生产的成本等方面都起到重要作用.从一个工业气体供应商的观点概述了这一可能性,特别强调采用工业气体的技术可以克服环境问题.     

Lorentz transformation of toroid polarization

In a recent paper [1] a modified system of equations of electrodynamics of moving continuous media has been obtained in account of toroid polarizations. In this letter it has been shown that these equations are invariant under Lorentz transformations. The transformation law for the toroid polarizations has also been worked out.     

Use of Basic Oxygen Furnace (BOF) Steel Slag for Acid Mine Drainage Treatment: A Laboratory Study

Mine Water and the Environment - We investigated the feasibility of using alkaline basic oxygen furnace (BOF) steel slag to treat acid mine drainage (AMD). Simulated AMD was treated with different...     

Effect of overaging and particle size on tensile deformation and fracture of particle-reinforced aluminum matrix composites

The effect of reinforcement particle size and overaging treatment on the tensile behavior and fracture morphology of a 2080/SiC/20 _p composite was investigated. Tensile behavior was profoundly influenced by particle size and matrix strength. The composite strength increased with a decrease in particle size, while overaging greatly reduced the strength of the composite, independent of particle size. Almost all particles on the fracture plane were fractured, and the amount of particle fracture in the composites was insensitive to overaging and particle size, due to the excellent bonding between SiC particles and the Al matrix. Fractography showed that void nucleation in the matrix of peak-aged composites took place primarily at very fine SiC particles, which were much smaller than the average SiC particle size. Subsequent failure took place by the tearing topography surface (TTS) mechanism. In the overaged composite, composites failed by a more conventional void nucleation and growth process, where void nucleation took place at coarsened S precipitate particles, resulting in smaller and more elongated voids.     

Long-term exposure of beta-INS cells to high glucose concentrations increases anaplerosis, lipogenesis, and lipogenic gene expression

Chronic exposure of pancreatic beta-cells to high glucose has pleiotropic action on beta-cell function. In particular, it induces key glycolytic genes, promotes glycogen deposition, and causes beta-cell proliferation and altered insulin secretion characterized by sensitization to low glucose. Postglycolytic events, in particular, anaplerosis and lipid signaling, are thought to be implicated in beta-cell activation by glucose. To understand the biochemical nature of the beta-cell adaptive process to hyperglycemia, we studied the regulation by glucose of lipogenic genes in the beta-cell line INS-1. A 3-day exposure of cells to elevated glucose (5-25 mmol/l) increased the enzymatic activities of fatty acid synthase 3-fold, acetyl-CoA carboxylase 30-fold, and malic enzyme 1.3-fold. Pyruvate carboxylase and citrate lyase expression remained constant. Similar observations were made at the protein and mRNA levels except for malic enzyme mRNA, which did not vary. Metabolic gene expression changes were associated with chronically elevated levels of citrate, malate, malonyl-CoA, and conversion of glucose carbon into lipids, even in cells that were subsequently exposed to low glucose. Similarly, fatty acid oxidation was suppressed and phospholipid and triglyceride synthesis was enhanced independently of the external glucose concentration in cells preexposed to high glucose. The results suggest that a coordinated induction of glycolytic and lipogenic genes in conjunction with glycogen and triglyceride deposition, as well as increased anaplerosis and altered lipid partitioning, contribute to the adaptive process to hyperglycemia and glucose sensitization of the beta-cell.     

The BLUE active queue management algorithms

In order to stem the increasing packet loss rates caused by an exponential increase in network traffic, the IETF has been considering the deployment of active queue management techniques such as RED (random early detection) (see Floyd, S. and Jacobson, V., IEEE/ACM Trans. Networking, vol.1, p.397-413, 1993). While active queue management can potentially reduce packet loss rates in the Internet, we show that current techniques are ineffective in preventing high loss rates. The inherent problem with these algorithms is that they use queue lengths as the indicator of the severity of congestion. In light of this observation, a fundamentally different active queue management algorithm, called BLUE, is proposed, implemented and evaluated. BLUE uses packet loss and link idle events to manage congestion. Using both simulation and controlled experiments, BLUE is shown to perform significantly better than RED, both in terms of packet loss rates and buffer size requirements in the network. As an extension to BLUE, a novel technique based on Bloom filters (see Bloom, B., Commun. ACM, vol.13, no.7, p.422-6, 1970) is described for enforcing fairness among a large number of flows. In particular, we propose and evaluate stochastic fair BLUE (SFB), a queue management algorithm which can identify and rate-limit nonresponsive flows using a very small amount of state information.