Mining bridge and brick motifs from complex biological networks for functionally and statistically significant discovery.

A major task for postgenomic systems biology researchers is to systematically catalogue molecules and their interactions within living cells. Advancements in complex-network theory are being made toward uncovering organizing principles that govern cell formation and evolution, but we lack understanding of how molecules and their interactions determine how complex systems function. Molecular bridge motifs include isolated motifs that neither interact nor overlap with others, whereas brick motifs act as network foundations that play a central role in defining global topological organization. To emphasize their structural organizing and evolutionary characteristics, we define bridge motifs as consisting of weak links only and brick motifs as consisting of strong links only, then propose a method for performing two tasks simultaneously, which are as follows: 1) detecting global statistical features and local connection structures in biological networks and 2) locating functionally and statistically significant network motifs. To further understand the role of biological networks in system contexts, we examine functional and topological differences between bridge and brick motifs for predicting biological network behaviors and functions. After observing brick motif similarities between E. coli and S. cerevisiae, we note that bridge motifs differentiate C. elegans from Drosophila and sea urchin in three types of networks. Similarities (differences) in bridge and brick motifs imply similar (different) key circuit elements in the three organisms. We suggest that motif-content analyses can provide researchers with global and local data for real biological networks and assist in the search for either isolated or functionally and topologically overlapping motifs when investigating and comparing biological system functions and behaviors.     

Ag(x)VOPO(4): A Demonstration of the Dependence of Battery-Related Electrochemical Properties of Silver Vanadium Phosphorous Oxides on Ag / V Ratios

As a part of our on-going study on silver vanadium phosphorous oxides (Ag_xV_yO_zPO₄), we report here the first study of the electrochemical reduction of a low Ag/V ratio silver vanadium phosphorous oxide, Ag_0.48VOPO₄·1.9H₂O. Reminiscent of Ag₂VO₂PO₄ reduction, in situ formation of silver metal nanoparticles along with an associated increase in conductivity were observed after reduction of Ag_0.48VOPO₄·1.9H₂O with 0.37 electron equivalents. However, in contrast to our lithium/Ag₂VO₂PO₄ cells, our lithium/Ag_0.48VOPO₄·1.9H₂O cells displayed an even higher voltage on discharge and a characteristic multi-plateau voltage profile, where vanadium reduction was the first reduction step.     

Effect of environmental humidity on rate of thermal outgassing

This investigation presents a super-dry venting system that allows the rate of thermal outgassing of an aluminum chamber (length 2 m) to return rapidly to 1 × 10⁻¹³ mbar L s⁻¹ cm⁻² in 4 h without baking. A glove box and an air shower, which provided dehumidified environments with water vapor concentrations of 0.1 ppm and 5 ppm respectively, were utilized to assess the effect of environmental humidity on the rate of thermal outgassing. With super-dry nitrogen venting inside and exposure to the glove box, a thermal outgassing rate of q₁ ∼ 1 × 10⁻¹¹ mbar L s⁻¹ cm⁻² was achieved.     

Antioxidant, anti-inflammatory and anti-browning activities of hot water extracts of oriental herbal teas

Traditionally, antioxidants are used to scavenge reactive oxygen species (ROS), which are harmful by-products of aerobic metabolism. Inulae Flos, Horsetail, Chinese Leucas, Broomweed and Indian Wikstroemia are five herbal teas commonly consumed by Asians. Our aim was to investigate the hot water extracts of these five herbal teas for their total phenolics/flavonoid contents and antioxidant capacities. Furthermore, with inflammation and hyper-pigmentation considered as two biological processes associated with elevated cellular oxidative stress, Inulae Flos water extract was chosen for further evaluation of its inhibitory effects on the production of LPS-induced inflammatory mediators (such as, TNF-α, IL-6, IL-1β) in RAW 264.7 cells and its anti-tyrosinase activity. Our findings suggest that Inulae Flos might be an alternative source as a potential antioxidant, and a noteworthy inhibitor of production of pro-inflammatory cytokines in a dose-dependent manner. Moreover, it could also serve as a potential natural food additive to prevent browning.     

Preparation and characterization of delafossite CuCrO2 film on flexible substrate

Delafossite CuCrO₂ film was successfully prepared on a flexible plastic substrate using a heat transfer process. The metallic acetate of the first layer decomposed to form a carbonized layer for use as a release layer. The thin film was deposited on the first layer by chemical solution deposition and heat treated to form a CuCrO₂ film. After that, the delafossite CuCrO₂ film was transferred from a Si substrate to a polymethyl methacrylate (PMMA) substrate. The CuCrO₂/PMMA film structure, morphology, and optical properties were studied by different characterization techniques. X-ray diffraction analysis and Raman spectrum analysis confirmed that the delafossite CuCrO₂ film was transferred onto the PMMA substrate. XPS analysis showed that the metallic acetate was annealed in N₂ to form a carbonized layer. The resistivity of the CuCrO₂/PMMA was gauged by a four-point probe method, and the visible light transmittance was approximately 58%.     

Copper oxide nanoparticle made by flame spray pyrolysis for photoelectrochemical water splitting – Part I. CuO nanoparticle preparation

Copper oxide (CuO) semiconductor nanoparticles are of interest because of their promising use for electronic and optoelectronic devices, and the size of the CuO particles for these applications is important. In this work, near spherical CuO nanoparticles with aspect ratio of 1.2–1.3 were made by a flame spray pyrolysis (FSP) method. In FPS, flame temperature, residence time, precursor concentration can be used to control particle size. As the precursor concentration increased from 0.5% to 35% w/w, primary particle diameter increased from 7 ± 2 to 20 ± 11 nm. Larger primary particle diameters were observed in the low gas flow system (set B) due to the long residence time in the high temperature zone. For the dependence of temperature on particle diameter, particles grew to similar diameter, i.e. ∼11 nm, in both flame conditions within the hot temperature zone (80% of melting point of CuO) but for particles having longer residence time, i.e. 550 ms in set B, the standard deviation of particle diameter is 45% larger than for particles with 66 ms as residence time in set A. Modeling gave a result for CuO final particle diameter, based on collision/sintering theory with sintering by solid state diffusion, of 6.7 and 9.0 nm for set A and set B, respectively, with surface tension assumed to be 0.5 J/m².Comparison with the experiment results, 11 ± 4 nm diameter for both flame conditions, indicates the simulations were reasonable.     

Channel Capacity of Multiple-Input Multiple-Output Systems for Optimal Antenna Spacing by Particle Swarm Optimizer

The geometrical shape of antenna arrays for maximizing the average channel capacity of the system in a multiple-input multiple-output link is investigated. The optimum element spacing of the transmitting antenna is also included. The frequency responses of transceiver antenna with different element spacing are computed by ray-tracing techniques, and the channel frequency response is further used to calculate corresponding channel capacity. The transmitter is set in the center of the indoor environment and the receivers are with uniform intervals distribution in the whole wooden table. Linear shaped array, L shaped array, T shaped array and rectangular shaped array with non-uniform inter-element spacing are investigated for both line-of-sight and non-LOS scenarios. The optimal element spacing of antenna for maximizing the channel capacity is searched by particle swarm optimizer. Numerical results have shown that our proposed method is effective for increasing average channel capacity. It is also found that L shaped array has the highest channel capacity and the improvement ratio for rectangular shaped array is the largest.     

The role of surface functionalization in the solar light-induced production of reactive oxygen species by single-walled carbon nanotubes in water

Risk assessment of engineered nanomaterials necessitates the need for information on reactivity and persistence of these materials in the environment. To this end, we report on reactivity of single-walled carbon nanotubes (SWCNTs) that: (i) have been functionalized by acid oxidation to contain carboxylic acid groups, (ii) have been further functionalized by esterification with polyethylene oxide groups, or (iii) were unmodified (i.e., unfunctionalized), with all materials used as received from the manufacturer. Aqueous colloidal dispersions of both types of functionalized SWCNTs generated reactive oxygen species (ROS) including singlet oxygen (¹O₂), superoxide anion , and hydroxyl radicals (OH) in light within the solar spectrum (λ = 300–410 nm) under oxic conditions. Under similar experimental conditions (i.e., several days under light near solar intensity) but with a surfactant added as a dispersing agent, aqueous dispersions of unfunctionalized SWCNTs exhibited no measurable ROS production. Defects in the surface caused by functionalization, as well as differences in amorphous carbon and metal impurity content within different SWCNT preparations, may facilitate some ROS production. Adding β-nicotinamide adenine dinucleotide to dispersions of carboxylated SWCNTs resulted in generation in the absence of light, suggesting dark reaction electron transfer as a potential mechanism of toxicity.     

Phase distribution and phase analysis in Cu6Sn5, Ni3Sn4, and the Sn-rich corner in the ternary Sn-Cu-Ni isotherm at 240°C

Metallurgical reactions between solders and under bump metallization (UBM) are key issues for the solder joint reliability in microelectronic packaging. A phase diagram consisting of solders and UBM materials are required to further understand the interfacial reactions and related phase transformation. In this study, series of ternary Sn-Cu-Ni alloys were designed, fabricated, and heat-treated at 240°C. Equilibrium phases of Sn, Ni₃Sn₄, and Cu₆Sn₅ were identified by XRD, and microstructure evidence in backscattered electron image (BEI) micrograph. Through detailed EPMA quantitative analysis, three acme compositions of the ternary region in the Sn-Cu-Ni isotherm near the Sn-rich corner were evaluated and determined. Furthermore, x-ray color mapping of tin, copper, and nickel were applied to study the phase distribution of the alloys with the aid of electron microprobe analysis (EPMA). According to the intensities of Sn, Cu, and Ni, collected by x-ray color mapping, special software was employed to map the corresponding concentrations on the Sn-Cu-Ni ternary isotherm. The degree of composition homogeneity and the phase distribution were further evaluated by phase-analysis techniques. Semiquantitative measurements by phase analysis can be extended to evaluate the phase boundaries with a statistical variation under 5% as compared to the quantitative analysis by EPMA. Finally, the isothermal section of the ternary Sn-Cu-Ni system near the Sn-rich corner at 240°C was constructed.     

Persuasive messages on information system acceptance: A theoretical extension of elaboration likelihood model and social influence theory

Firms invest millions of dollars in the introduction of new information systems for long-term benefit. If employees are not willing to accept a new information system, such investments may be wasted. Employee acceptance of a new information system is in part determined by external influences. However, previous research has neglected the paths of persuasive strategies and external social influences on information system acceptance. Linkages between persuasive strategies and external social influences are also scarce. By integrating social influence theory and an elaboration likelihood model, this study explores the influence of persuasive messages (source credibility and argument quality) on social influence, affective response and cognitive response. This study also investigates the interrelationships among affective response, cognitive response and behavior intention. Furthermore, the moderating roles of social influences on the impact of affective response and cognitive response on behavior intention are identified.