Tree Recovery in PIM Sparse Mode

A PIM–SM-built multicast tree must be restructured when the underlying unicast routing tables change. We describe the PIM–SM recovery mechanisms and evaluate the recovery performance, showing its dependence on a range of network and session parameters. Our results show that a substantial packet loss can be caused by nonreductive, benign events in the network, such as an addition of a new link. We propose and evaluate an improvement to the standard PIM–SM recovery procedure aimed to reduce the packet loss caused by the benign events. Our evaluation shows that the data loss caused by these events can be significantly decreased regardless of the topology and session parameters.     

Binary oxide ceramics for enhanced phenols degradation under simulated Solar light

Solvothermal synthesis of ZrO₂–TiO₂ binary oxides and pure counterparts at 150°C in water/isopropanol media is presented. Titanium (IV) isopropoxide and zirconium (IV) propoxide were used as precursors. XRD and TEM techniques were used for structural and morphological characterization of obtained samples. XPS spectra of mixed oxide samples were compared in order to correlate composition of samples with surface properties and presence of defects. Relative positions of defect states within band‐gaps of semiconductors were estimated from UCPL spectra. UV‐Vis DRS spectra revealed that both pure oxides experienced red shift of absorption thresholds compared to reference data. Photocatalytic activities of all samples were probed under simulated Solar light on three model compounds: phenol, 4‐chlorophenol (4‐CP) and 2, 4, 6‐trichlorphenol (TCP). Pure TiO₂ showed the highest photocatalytic activity in the case of phenol. However, pure ZrO₂ and binary oxides showed higher photoactivity in degradation of 4‐CP and TCP. The activity of wide band‐gap semiconductors under simulated Solar light in photodegradation of phenol and its derivatives is most probably the consequence of formation of charge transfer complexes between pollutant molecules and semiconductors surface.     

Rubber substrates and their influence on isomerization of conjugated dienes in pheromone dispensers

Release rate and degree of isomerization of pheromones with conjugated double bonds were studied in dispensers prepared from several rubber substrates. The substrates compared were made of rubber, cured with elemental sulfur or accelerators based on organic sulfur compounds or organic peroxides. Isomerization of the double bonds occurs immediately after impregnation of the substrate, and the degree of isomerization increases during field use and/or storage. The propensity of the isomers to isomerize corresponds to their proportion in the equilibrium mixture. AnE,Z isomer is isomerized faster than theE,E isomer, and finally a near-equilibrium mixture of the four isomers is present. Minimal isomerization was found in non-sulfur-cured substrates which are the material of choice.     

Cermet compact made from semiconducting InSb with constant electrical resistance in the 4–400 K range

A study of the electrophysical properties of samples prepared by phase transformation of stoichiometric InSb into lnSb-Sb-In₂O₃ cermet compact has been performed (InSb, In₂O₃-semiconductors, antimony-metallic conductivity). Samples were prepared by isothermal partial oxidation at 200–500°C for 1–50 h. Bulk and thin-film samples annealed at 400°C for 1–50 h possess relatively constant electrical resistance over the wide temperature interval measured: 4–400 K. The conversion degree, β, and molar ratio, f = In₂O₃/2Sb were calculated from the isothermal thermogravimetry data according to the reaction equation 2InSb+3/2O₂ = In₂O₃+2Sb at temperatures T < 400°C, when no ascertainable amount of antimony is escaping from the system. The β-value increases with temperature, T, and time of oxidation annealing, t. However, instead of being constant, i.e. f = 0.5, f increases for T > 400°C and t > 1 h. The X-ray powder diffraction, thermogravimetry, differential thermogravimetry and differential thermal analysis measurements and studies revealed that metallic antimony escapes partially from the InSb-Sb-In₂O₃ system obtained at T ≥ 400°C. As a result, the mutual volume ratio of individual InSb, Sb and In₂O₃ components is changed, and so also is the overall character of the electrical resistivity of the samples. Due to the partial escape of Sb↑ from the system at T ≥ 400°C, the following reaction is appropriate: 2InSb + 3/2O₂ = In₂O₃ + (2 − z) Sb↑ = In₂O₃+Sb/f+ zSb, where z is the volatilized portion of Sb and f is the molar ratio of the reaction products, i.e. f = In₂O₃/(2 − z)Sb = 1/(2 − z). The SEM observations revealed a growing grain size with temperature and time of annealing, lowering the grain-boundary density and thus also the resistivity of the samples. The properties of the obtained ternary compact may be influenced significantly, if instead of stoichiometric InSb, the initial In-Sb with a variable In/Sb ratio is used.     

Implementation of a dynamic scheduler for apparel computer integrated manufacturing systems

A major problem faced by the typical apparel manufacturer in day-to-day operations is the need for an effective scheduler to determine actions required because of operator and/or machine non-performance. The dynamic resource allocation system (DRAS) scheduler described in this paper is the natural outgrowth of previously funded research related to the design, development, technology transfer and installation of a CIM system in an apparel plant. The already developed CIM system provides a way for the DRAS scheduler (described in this paper) to change a production process dynamically. The implementation and modeling approach of the scheduler is described. The underlying system model is based on Petri nets and object-oriented databases. Petri nets provide a dynamic model of the CIM system, while object-oriented databases provide necessary information about system components and overall system activity. The data from the CIM system is used by the scheduler in the simulation mode. The daily production plan is used as a guideline to determine how to react to and correct production problems.     

Strengthening of alloy 8090 and its fracture mechanics parameters

An investigation has been made of the tensile properties, impact-, initial fracture toughness and fracture mode of an aluminium-lithium 8090 alloy at room temperature and 77 K, depending upon the heat treatment and orientation. The peak-aged material exhibited an excellent combination of strength and toughness, equal to or exceeding that shown by the high-strength aluminium alloys of the 2000 and 7000 series. The superior strength and toughness of peak-aged plates, including that of 3% stretched material, compared to underaged material seems to be associated with the lower content of coarse insoluble precipitates, a higher density of S-precipitates in a matrix ligament (grain) which promote ductile fracture. The impact toughness of the peak-aged specimens increased at 77 K only in the L-T plate orientation, while in the T-L orientation it was somewhat lower or remained the same. The toughness increase at 77 K is discussed in terms of the role of the matrix and (sub)grain-boundary precipitates, freezing of low-melting point impurities of sodium and potassium alkaline metals at (sub)grain boundaries and the occurrence of the fine crack divider delamination toughening. The yield strength, R _o.2, increase on ageing was accompanied by a corresponding increase in initial crack divider fracture toughness, K _lc, opposite to the trends obtained for some traditional high-strength aluminium alloys. Changes of K _lc versus R _o.2 depending on orientation are discussed using models for ductile fracture toughness behaviour of aluminium alloys, based on the criterion that a critical width of the heavily strained zone at the crack tip approximates the average ligament width, d _p, i.e. the thickness of the elongated grain in the L-T and T-L plate orientations. It was also found that, for constant chemical composition and fabrication practice of the alloy, a critical plate thickness exists B 0.1 6 t _i, where _i is the initial thickness of the rolling ingot, for which the tensile strength properties in the L-T orientation are the same as that in the T-L orientation, while the plasticity (measured by elongation to failure) of the plate is a maximum. Two types of laminated cracks were observed on fracture surfaces of the specimens: large, >1 mm deep (the number of these cracks remains the same as the number of hot-rolling passes), and fine <0.4 mm (shallow laminated cracks, the number of which significantly increases with decreasing temperature, 77 K).     

Nucleobase Modified Adefovir (PMEA) Analogues as Potent and Selective Inhibitors of Adenylate Cyclases from Bordetella pertussis and Bacillus anthracis

A series of 13 acyclic nucleoside phosphonates (ANPs) as bisamidate prodrugs was prepared. Five compounds were found to be non‐cytotoxic and selective inhibitors of Bordetella pertussis adenylate cyclase toxin (ACT) in J774A.1 macrophage cell‐based assays. The 8‐aza‐7‐deazapurine derivative of adefovir (PMEA) was found to be the most potent ACT inhibitor in the series (IC₅₀=16 nm ) with substantial selectivity over mammalian adenylate cyclases (mACs). AC inhibitory properties of the most potent analogues were confirmed by direct evaluation of the corresponding phosphonodiphosphates in cell‐free assays and were found to be potent inhibitors of both ACT and edema factor (EF) from Bacillus anthracis (IC₅₀ values ranging from 0.5 to 21 nm ). Moreover, 7‐halo‐7‐deazapurine analogues of PMEA were discovered to be potent and selective mammalian AC1 inhibitors (no inhibition of AC2 and AC5) with IC₅₀ values ranging from 4.1 to 5.6 μm in HEK293 cell‐based assays.     

Tribological Performance of Ti–Si-Based in Situ Composites

In this study, a series of Ti–Si-based in situ composites was manufactured by means of a common argon arc melting technique and tribologically evaluated using a sliding ball-on-disc tester under simulated body fluid lubrication. The composite microstructure, mechanical properties, and surface roughness were characterized using light and scanning electron microscopy (SEM), vertical scanning interferometry (VSI), X-ray diffraction (XRD) analysis, and hardness measurements. The evolution of coefficients of friction (COFs) and the appearance of contacting surfaces showed that two the principal wear mechanisms were mixed elastohydrodynamic lubrication (EHL), typically followed by abrasive wear. The mixed EHL was due to the combined effect of serum solution lubrication and surface irregularities, which were produced during the routine surface preparation of samples. The mixed EHL provided the absence of wear and low and stable COFs, which did not depend on the phase composition, microstructure, or hardness of Ti–Si-based alloys. However, in most cases, the change in contact geometry led to the transition from mixed EHL to conventional boundary lubrication, accompanied by increased and unstable friction, adhesive material transfer of metal to the ceramic counterbodies, and abrasive wear. In this respect, the low wear resistance and high adhesion affinity of the titanium matrix of Ti–Si-based alloys should be improved.