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Although the compressive strength of ice under both quasi-static [M. Arakawa and N. Maeno, Mechanical strength of polycrystalline ice under uniaxial compression. Cold Reg. Sci. Tech 26 (1997), pp. 215–229.] and dynamic [X. Wu and V. Prakash, Dynamic compressive behavior of ice at cryogenic temperatures. Cold Reg. Sci. Tech 118 (2015), pp. 1–13.] loadings shows an anomalous temperature effect that the compression strength is insensitive to temperature in a specific temperature range below −100oC, it is still unclear whether the anomalous temperature exists for the tensile strength of ice at cryogenic temperatures. In this paper, the temperature-dependent dynamic tensile strength of ice 1 h under shock loading is investigated by molecular dynamics simulations. It is intriguing to see that the dynamic tensile strength of the ice exhibits a similar anomalous temperature effect, i.e. it is almost insensitive to temperature in the range 117 ∼ 163 K, which could be interpreted by the competitive mechanism between shock-induced pulverisation and melting. The evolution of the pentagonal-heptagonal defects and the ductile-to-brittle transformation are also observed with decreasing temperature, leading to the unique dynamic tensile behaviour of ice under shock. [ABSTRACT FROM AUTHOR]

Cold stress is one of the most detrimental environmental factors affecting plant growth and development. Melatonin (MEL), a natural indoleamine compound, responds to various environmental cues. To explore the role of MEL in the response of melon (Cucumis meloL.) seedlings to cold stress, the effects of exogenous MEL on the ascorbate–glutathione (AsA–GSH) cycle and proline metabolism were investigated. Melon seedlings were sprayed with various concentrations of MEL (0, 50, 100, 200, or 400 μM), then exposed to cold stress, 12/6°C (day/night) for 7 d, followed by recovery at 28/18°C for another 7 d. The results showed that MEL, especially the 200 μM treatment, dramatically alleviated growth inhibition caused by cold stress, manifested by increased plant growth and decreased O2•¯production rate and malondialdehyde content. Importantly, exogenous application of MEL enhanced the ratios of reduced and oxidized forms of AsA (AsA/DHA) and GSH (GSH/GSSG), and the activities of ascorbate peroxidase (APX), glutathione reductase (GR), and dehydroascorbate reductase (DHAR) involved in the ascorbate–glutathione (AsA–GSH) cycle in melon seedings grown under cold stress. Besides, MEL pretreatment further increased the contents of proline and soluble protein under cold stress. The results reveal that protective effects of MEL against cold stress in melon seedlings are most likely associated with the regulation of the AsA–GSH cycle and proline metabolism as an effective antioxidant system. [ABSTRACT FROM AUTHOR]

This paper deals with two-dimensional and three-dimensional cooperative control of multiple agents formation tracking a set of given closed orbits, where each agent has intrinsic second-order non-linear dynamics and the communication topology among agents is directed. By using our previous curve extension method, the cooperative control system can be regarded as a cascade system composed of the orbit-tracking subsystem and the formation subsystem with the orbit-tracking error as input. A novel solution is established by separatively designing the orbit-tracking control law and the formation control protocol ignoring the perturbation at first and then applying input-to-state stability theory to analyse the asymptotic stability of the cascade system. It is shown that the closed-loop system is asymptotic stability if the directed communication topology contains a directed spanning tree. The effectiveness of the analytical results is verified by numerical simulations. [ABSTRACT FROM PUBLISHER]

To meet an increasing market demand of conductive ink which is applicable to wide range of substrates, ultraviolet (UV) curing technique combined with nano-silver materials was used to fabricate UV electric conductive ink. Firstly, both silver nano-particles (AgNPs) and silver nano-wires (AgNWs)/poly (vinyl pyrrolidone) (PVP) composites were synthesized. An ethanol solution-phase approach using hydrazine hydrate as a reducing agent was presented for an easy synthesis of large-scaleAgNPswith an average diameter of 35 nm.AgNWswith diameter of 40 nm and length up to over 10 μm were synthesized by polyol method. InAgNWssynthesis process, the main influencing factors such as the molar ratio of PVP to silver nitrate, the reaction time and PVP of different degree of polymerization were investigated. Finally, nano Ag/PVP composites, polyurethane acrylate, photoinitiator 1173 and solvents were used to fabricate UV electric conductive ink, which had an electrical conductivity on paper as high as 2.1 × 105 S/m. [ABSTRACT FROM PUBLISHER]

It is widely accepted that the mechanical behaviour of lead-rubber bearing for bridge will change distinctly with temperature variation. This paper outlines an experimental study for 300 × 300 square type lead-rubber bridge bearing. The experimental results of temperature dependency for horizontal shear performance of lead-rubber bearing are presented. It can be seen that the horizontal shear stiffness of the bearing will be reduced as the temperature rises. The horizontal damping ratio of the bearing will be reduced as the temperature increases, but such a trend will not be obvious when the temperature is higher than 23°C. By using the classical regression analysis, estimation of the formula for temperature dependency for horizontal shear stiffness and horizontal damping ratio of 300 × 300 mm square lead-rubber bearings are given. [ABSTRACT FROM AUTHOR]

Effects of trace TiB2 on solidification microstructure of Ti-6Al-4V alloy were investigated. The result shows that the microstructure of the ingot was refined by the added TiB2. The grain size and α lath size were reduced gradually with the increase in TiB2. The grain size is reduced by about an order of magnitude with an addition of 0·96 wt-%TiB2, and the dendrite appears in the ingot. Such a tendency is similar to the change of the microstructure with boron addition. Ti-6Al-4V-B phase diagram and growth restriction factor Q are applied to analyse the influence mechanism of trace TiB2 on the microstructure. [ABSTRACT FROM AUTHOR]

A new design of a broadband circularly polarized (CP) square slot antenna is presented. An excellent CP bandwidth can be obtained by using a novel coplanar waveguide (CPW) fed structure, which consists of a widened square tuning stub at the end of an asymmetric inverted-L signal strip and a pair of I-shaped strips along they -axis at two opposite sides of the square tuning stub. Axial ratio (AR) bandwidth can be significantly enhanced by adjusting the length of the pair of I-shaped strips. The antenna has been investigated numerically and experimentally. Experimental results show that the antenna possesses an impedance bandwidth of as large as 50% with voltage standing wave ratio (VSWR) less than 2 and a 3 dB AR bandwidth of 51.7% relative to the centre frequency of 2.2 GHz. The 3 dB gain variations are less than 1 dBi within the CP bandwidth. [ABSTRACT FROM AUTHOR]

In this paper, we propose a computational global optimization method based on differential evolution (DE) algorithm for synthesizing large multiple concentric rings arrays to generate a pencil beam with minimum peak side lobe level (PSLL) and constrained first null beam width (FNBW). The synthesis is performed with a differential evolution technique to optimize the ring spacing, the number of the elements in each ring as well as the amplitude distribution. Simulated results of the designed synthesis illustrate the efficiency and reliability of our proposed method. [ABSTRACT FROM AUTHOR]

A pair of single chain Fv fragment (scFv) fusion proteins were constructed and characterized. Antibody chips using the pair were designed for sensitive detection of prion protein. Phage displayed antibody library was synthesized by immunizing mice with thioredoxin-mature bovine prion fusion protein (TrxA-bPrPc). After five rounds of panning against recombinant bovine prion protein (rb-PrPc) and ELISA test, two positive clones with high affinity to rb-PrPc, named Z163 and Z186, were obtained. They were conjugated with a linker-streptavidin binding protein (SBP) or human IgG1 constant fragment (Fc) to form the scFv fusion protein pair Z186-L-SBP/Z163-Fc. Western blot experiments showed that the scFv fusion pair specifically interacted with the line epitopes of the protease resistant core region bPrP27-30. Surface plasmon resonance (SPR) sensorgrams revealed that the equilibrium dissociation constants of the interactions with rb-PrPc were 3.24×10-8 M, 8.82×10-8M, and 8.10×10-9 M for Z186-L-SBP, Z163, and Z163-Fc, respectively. All binding reactions followed rapid association and slow dissociation kinetics. As a detection pair, Z186-L-SBP functioned as a capture probe and was immobilized on the streptavidin coated slides to form reactive layer of the antibody chip, and Z163-Fc labeled with fluorescence dye Cy3 functioned as a detection probe generating fluorescence signal. The antibody chip could detect existence of rb-PrPc with detection limit of 1 pg/ml. [ABSTRACT FROM AUTHOR]

Apple fruits of different cultivars were heat-treated at 38°C for 4 d immediately after harvest, then stored at 0°C for 6 weeks ('Gala') or 4 months ('Golden Delicious' and 'Red Fuji'). Upon removal from storage, fruits were kept for 7 d at 20°C as a shelf-life test. During storage and shelf-life, various ripeness parameters were measured. 'Golden Delicious' and 'Red Fuji' apples were artificially inoculated with Penicillium expansum or Botrytis cinerea before heat treatment, then stored at 20°C for 3 weeks, or 0°C for 6 weeks, and the development of fruit decay was recorded. The respiration rate decreased and the ratio of soluble solids contents (SSC): titratable acidity (TA) increased for all heat- treated fruits. For 'Gala' and 'Golden Delicious' apples, heat treatment significantly reduced ethylene evolution, reduced softening during cold storage, and reduced membrane electrolyte leakage after cold storage and shelf-life. Better quality was maintained at the end of the shelf-life for these two cultivars. However, the effects of heat treatment on ethylene production, membrane electrolyte leakage and texture parameters of 'Red Fuji' apples were not significant. The rotting caused by P expansum or B. cinerea was very severe, especially for apples stored at 20°C. However, decay was completely inhibited in 'Golden Delicious' and 'Red Fuji' apples that had been heat-treated after inoculation. It was concluded that the response to heat treatment varied according to cultivar. Pre-storage heat treatment could delay the ripening of 'Gala' and 'Golden Delicious' apples and maintain storage quality. Although heat treatment gave no beneficial effects on the quality of 'Red Fuji' apples, it could be applied to control disease in this apple cultivar. [ABSTRACT FROM AUTHOR]

Two forms of fluoroacetate-specific defluorinase (FSD) were purified from rat hepatic cytosol. The first form, FSD1 (molecular weight 38  kDa), contained 81% of the total cytosolic fluoroacetate defluorination activity and did not bind to the glutathione-affinity, orange A or mono P columns used in the purification procedures. The second form, FSD2 (molecular weight 27  kDa), contained only 13% of the fluoroacetate defluorination activity, had a pI  =  7.8, and exhibited a high glutathione S- transferase (GST)-like activity towards dichloroacetic acid. The FSD1 proteins were identified from peptide mass data and best matched with rat sorbitol dehydrogenase (SDH) (short form), although pure sheep liver SDH enzyme did not possess defluorination activity when subsequently investigated. The FSD2 protein was identified from peptide mass data and best matched with the amino acid sequence of mouse and human Zeta 1 of glutathione S- transferase (GSTZ1) and showed a high GSTZ1 specific activity. This study suggests that the major FSD component (FSD1) represents a new and unique dehalogenating or dehydrogenating enzyme present in rat liver cytosol. The minor FSD component (FSD2) is due to the GSTZ1 present in rat liver cytosol. However, it is not yet clear that FSD1 is indeed SDH and FSD2 is indeed GSTZ1, due to sequence homology being less than 60 and 45%, respectively. [ABSTRACT FROM AUTHOR]

A class of nonlinear memoryless controllers is synthesized to guarantee global uniform ultimate boundedness, with respect to some known set, for a class of imperfectly known singularly perturbed nonlinear systems, with discrete and distributed delays, provided that the singular perturbation parameter is small enough. Each feedback controller is designed using information based mainly on a nonlinear, affine in the control, 'reduced-order' system. The uncertainty, which may be time, state, delayed state and/or input dependent, is modelled by additive nonlinear perturbations influencing a known nominal, singularly perturbed time-delay system of the retarded type. A 'matched' uncertainty structural condition for the reduced-order system is not presumed in this paper. [ABSTRACT FROM AUTHOR]