Nano Molecular‐Platform: A Protocol to Write Energy Transmission Program Inside a Molecule for Bio‐Inspired Supramolecular Engineering

In a coded self‐assembly, a simple code is written in the molecule, which self‐assembles the molecules into a fractal like structure, which acts as a seed for the next step. As the molecule turns into a complex seed, the code transforms into another form and several seeds self‐assemble into another structure, which acts as a seed for the next step. Until now, this technology was considered as a prerogative of nature. Here, a dendritic network is used to write a basic code by synthetically attaching 32 molecular rotors and doping two controller molecules in its cavity. The code live, which is an energy transmission path in the molecule, is imaged. When the energy transmission path or code is triggered, a series of products generate one after another spontaneously. Two examples are: i) dendritic seed (5–6 nm)→paired nanowire (≈12 nm)→nanowire (≈200 nm)→microwire (500 nm)→wire like rod (1–2 μm)→jelly→rectangular sheet (5 μm). ii) dendritic seed→nano‐sphere (20 nm)→micro‐sphere (500 nm)→large balls(1 μm)→oval shape rod (5–10 μm)→Y, L or T shaped rod assembly. The energy level interactions are tracked using spectroscopy how exactly a directed energy transfer code generates multi‐step synthesis from nano to the visible scale.     

Synthesis of satellite footprint patterns from rectangular planar array antenna by using swarm‐based optimization algorithms

A pattern synthesis method based on Firefly Algorithm (FA) and Artificial Bee Colony (ABC) optimization has been presented to generate satellite footprint patterns from a rectangular planar array of isotropic antennas by modifying the amplitude, phase, and the state of the array elements. Three cases comprising three different footprints of rectangular, square, and circular boundary are generated from the same array by using two different swarm‐based optimization algorithms FA and ABC. Both the algorithms, following the proposed procedures are able to generate the three different footprint patterns while maintaining a satisfactory lower peak side lobe level and ripple. A comparative analysis has been carried out between FA, ABC, and Genetic Algorithm (GA) for the presented problem in terms of fitness value for the three different cases. The superiority of FA and ABC over GA has been established in terms of finding better solutions for all the three cases of the proposed problem. Copyright © 2013 John Wiley & Sons, Ltd.     

Nano boron nitride laminated poly(ethyl methacrylate)/poly(vinyl alcohol) composite films imprinted with silver nanoparticles as gas barrier and bacteria resistant packaging materials

Herein, nano boron nitride (BN) laminated poly(ethyl methacrylate) (PEMA)/poly(vinyl alcohol) (PVA) nanocomposite films are fabricated by using a simple in situ polymerization technique with incorporation of silver nanoparticles (Ag NPs). Structural investigations of PEMA/PVA/Ag@BN nanocomposite thin films are carried out by Fourier-transform infrared spectroscopy, dynamic light scattering, X-ray diffraction analysis, ¹H nuclear magnetic resonance, ¹³C nuclear magnetic resonance, and mass spectrometry. The change in morphology of PEMA/PVA matrix due to the reinforcement of BN platelets are identified by electron microscopic studies. The unique tortuous paths are achieved by the dispersion of BN platelets by which gas penetration is restricted with enhancing the barrier properties of the material by 6.5 folds at 5 wt% BN content as compared with neat PEMA/PVA. Acid and alkali resistant along with biodegradability behavior of as-synthesized nanocomposites are studied. From limiting oxygen index (LOI) results, it is found that the prepared materials are fire retardant in nature owing to effective reinforcement of BN layers. Antibacterial activities of PEMA/PVA/Ag@BN nanocomposite are studied by Xanthomonas citri or axonopodis pv. Citri, Escherichia coli, and Xanthomonas oryzae pv. Oryzae because of Ag NPs reinforcement. The substantial improvements in gas barrier, fire retardant, and antibacterial properties enable the materials for packaging application.     

Finite element analysis of cavitating facet interaction in a fully lamellar titanium aluminide alloy under creep conditions

Creep constrained grain boundary cavitation in a fully lamellar (FL) form of a titanium aluminide intermetallic alloy has been studied using finite element (FE) techniques. Two different forms of FL models were considered. Cavitation was modeled in the presence of grain boundary sliding (GBS) for the case of straight former γ grain boundaries. Models of cavitation without GBS were also performed for a FL microstructure with serrated forme γ grain boundaries. The effect of cavitating facet interaction on rupture life has been studied. A comparison between the FL forms and a dual-phase equizxed microstructure having the same phase ratio (α₂/γ) was also made to examine the relative susceptibility of these microstructures to high-temperature damage. It has been observed that the overall effect of interaction between cavitating facets increases the rupture time significantly when these facets are on adjacent grains. However, in the presence of GBS, cavitation on the facet with narrower separation effectively reduces the cavity growth rate on the facet with wider separation. ANIRBAN CHAKRABORTY, formerly Graduate Student Researcher with the Chemical & Biochemical Engineering and Materials Science (CBEMS) Department, University of California, Irvine. This article is based on a presentation made in the symposium “Fundamentals of Gamma Titanium Aluminides”, presented at the TMS Annual Meeting, February 10–12, 1997, Orlando, Florida, under the auspices of the ASM/MSD Flow & Fracture and Phase Transformations Committees.     

On observability with delay: antitheses and syntheses

The idea of observability with delay for discrete-event dynamic systems in a finite state machine framework has been proposed (Ozveren and Wilsky 1990). This note points out some shortcomings in the existing definitions and proposes an alternative one. It also derives necessary and sufficient conditions for the above property that can be tested for easily     

Pore morphology in sintered ZrO2–8 mol% Y2O3 ceramic: a small-angle neutron scattering investigation

Pore morphology and pore size distribution in yttria-stabilized zirconia (ZrO₂–8 mol% Y₂O₃) have been investigated, for two sintering temperatures, namely 1200 and 1270 °C, using small-angle neutron scattering. The results show that the reduction in the porosity, at 1270 °C compared to that at 1200 °C, occurs by the elimination of the pores at the lower end of the pore size distribution. In addition, the polydispersity is also lower at 1270 °C and the nature of the distribution is altered significantly near the smaller radius range. The average pore size shifts towards the higher radius range. The specific surface area of the pores is also diminished at 1270 °C because of the elimination of the finer pores.     

Hybrid mode-switched control of DC-DC boost converter circuits

This paper has proposed a new switching scheme for controlling dc-dc boost converter circuits. The converter is represented as a hybrid system with three modes of operation. The switching among these modes is governed by the adjustable reference voltage and a reference current which are calculated by an energy balance principle. The scheme has been applied to a realistic converter circuit modeled with various parasitic components. All the specifications related to the ripple voltage, line and load regulation are shown to be achievable by relating them to the switching surfaces, namely a reference voltage and a reference current. The state trajectories have been shown to reach a hybrid limit cycle already proved to be super-stable from consideration of chaos. Numerical results clearly bring out the advantages of the proposed control scheme.     

Xe-p9, a Xenopus Suc1/Cks protein, is essential for the Cdc2-dependent phosphorylation of the anaphase- promoting complex at mitosis

Degradation of mitotic cyclins on exit from M phase occurs by ubiquitin-mediated proteolysis. The ubiquitination of mitotic cyclins is regulated by the anaphase-promoting complex (APC) or cyclosome. Xe-p9, the Xenopus homolog of the Suc1/Cks protein, is required for some step in mitotic cyclin destruction in Xenopus egg extracts. Specifically, if p9 is removed from interphase egg extracts, these p9-depleted extracts are unable to carry out the proteolysis of cyclin B after entry into mitosis and thus remain arrested in M phase. To explore the molecular basis of this defect, we depleted p9 from extracts that had already entered M phase and thus contained an active APC. We found that ubiquitin-mediated proteolysis of cyclin B was not compromised under these circumstances, suggesting that p9 is not directly required for ubiquitination or proteolysis. Further analysis of extracts from which p9 had been removed during interphase showed that, at the beginning of mitosis, these extracts are unable to carry out the hyperphosphorylation of the Cdc27 component of the APC, which coincides with the initial activation of the APC. p9 can be found in a complex with a small fraction of the Cdc27 protein during M phase but not interphase. The phosphorylation of the Cdc27 protein (either associated with the APC or in an isolated, bacterially expressed form) by recombinant Cdc2/cyclin B is strongly enhanced by p9. Our results indicate that p9 directly regulates the phosphorylation of the APC by Cdc2/cyclin B. These studies indicate that the Suc1/Cks protein modulates substrate recognition by a cyclin-dependent kinase.     

Reliability bounds and other inequalities for discrete life distributions

In this paper we give sharp bounds on the reliability of discrete IFR, IFRA, NBU, DFR, DFRA and NWU classes, based on one known moment. Subsequently the discrete analogues of several continuous-time results related to maintained systems are also presented.     

Sol-gel preparation of silica glass

This paper is a preliminary report on the preparation of silica glass containing very low amount of hydroxyl by the sol-gel processing technique. Gels were prepared from optimized amounts of tetraethyl orthosilicate, fumed silica and water. Acids and bases in small quantities were added for catalysing hydrolysis and adjusting the pH. Dried gels were heated up to 1400°C in various atmospheres to obtain transparent silica glass of the required density and very low (<5 ppm) hydroxyl content.