Effect of contact angle and drop spacing on the bulging frequency of inkjet-printed silver lines on FC-coated glass

The morphologies of inkjet-printed narrow silver lines on fluorocarbon film-coated glass substrates were measured with varying contact angles and drop spacing to study the actual stability of line printing by using a practical inkjet system. From a practical stability point of view, three types of the lines were observed: stable, unstable, and meta-stable. The stable lines were free from any bulging or breaking; the unstable lines had repetitive and periodic instabilities; and the meta-stable lines had no repetitive instability but had irregular bulges that appear sparsely. Unstable line printing resulted from either the dynamic or static instability of bead flow, which arose when the pressure-driven bead flow was too large or too small compared with droplet deposition rate, respectively. Whether the printing would be stable or meta-stable was determined by the anti-bulging stability of the flow against other disturbances. The anti-bulging stability increased when the bead flow rate was balanced with the printing rate, whereas it decreased for the present system when the flow-balance became sensitive to drop spacing.     

Escherichia coli contamination of the river Thames in different seasons and weather conditions

Contamination of public water ways with sewage represents a serious environmental and health risk. We monitored pollution of the river Thames by enumerating the indicator organism Escherichia coli. Samples were taken from a site in central London near Waterloo Bridge in different seasons. E. coli were quantified using a membrane filtration method, and correlated with the tidal variations of the river and meteorological data on rainfall and temperature. More frequent and severe incidents of pollution occurred in the autumn. Heavy rainfall resulted in sharp peaks of E. coli contamination that implies a potential increase of numbers of pathogenic micro‐organisms. Sixty percent of all samples were found to be in excess of the accepted upper limit of pollution set by European Union (EU) legislation for bathing water. This study demonstrated that frequent sewage pollution of the Thames results in high numbers of E. coli and incidents of detectable levels of pathogenic bacteria demonstrating the need for regular monitoring of bacterial pollution.     

Pregnancy outcomes are not improved by administering gonadotropin-releasing hormone at initiation of a 5-day CIDR-Cosynch resynchronization protocol for lactating dairy cows

Using a 5-d controlled internal drug-release (CIDR)-Cosynch resynchronization protocol, the objective of this study was to determine the effect of the initial GnRH injection on pregnancy per artificial insemination (P/AI) to the second artificial insemination in lactating Holstein dairy cows. On 37 ± 3 d (mean ± standard deviation) after the first artificial insemination, and upon nonpregnancy diagnosis (d 0 of the experiment), lactating cows eligible for a second artificial insemination (n = 429) were enrolled in a 5-d CIDR-Cosynch protocol. On d 0, all cows received a CIDR insert and were assigned randomly to receive the initial GnRH injection (GnRH; n = 226) of the protocol or no-GnRH (n = 203). Blood samples were collected from a sub-group of cows (n = 184) on d 0 and analyzed for progesterone (P4) concentration. On d 5, CIDR inserts were removed, and all cows received 1 injection of PGF_2α. On d 6 and 7, cows were observed once daily by employees for tail-chalk removal, and cows detected in estrus on d 6 or 7 received artificial insemination that day (EDAI), and did not receive the final GnRH injection. The remaining cows not detected in estrus by d 8 received GnRH and timed artificial insemination (TAI). Pregnancy status was confirmed by transrectal palpation of uterine contents at 37 ± 3 d (mean ± standard deviation) after the second artificial insemination. Eliminating the initial GnRH injection had no effect on P/AI compared with cows receiving GnRH (27 vs. 21%), respectively. Similarly, method of insemination (EDAI vs. TAI) and its interaction with treatment had no effect on P/AI. Primiparous cows had greater P/AI than multiparous cows (31 vs. 21%). Mean P4 concentrations (n = 184) at the initiation of the protocol did not differ between treatments (4.51 ± 0.35 ng/mL no-GnRH vs. 3.96 ± 0.34 ng/mL of GnRH). When P4 concentrations were categorized as high (≥1 ng/mL) or low (<1 ng/mL), P/AI tended to be greater for high P4 concentrations (n = 136) compared with low (n = 48) P4 concentrations (26 vs. 16%, respectively). No differences were observed in the proportion of cows with high or low P4 between treatments. Collectively, these results provide evidence that eliminating the initial GnRH in a 5-d CIDR-Cosynch resynchronization protocol for lactating dairy cows did not reduce P/AI in this study.     

Stability and robustness of time‐delay systems

Abstract

Using some properties of matrix measures and matrix's spectral radius, a new stability criterion for a linear time‐delay system is derived. This result is also extended to interval time‐delay systems.     

Implication of Size-Controlled Graphite Nanosheets as Building Blocks for Thermal Conductive Three-Dimensional Framework Architecture of Nanocarbons

Preparation of three-dimensional (3D) networks has received significant attention as an effective approach for applications involving transport phenomena, such as thermal management materials, and several nanomaterials have been examined as potential building blocks of 3D networks for the improvement of heat conduction in polymer nanocomposites. For that purpose, nanocarbons such as graphene and graphite nanoplatelets have been spotlighted as suitable filler materials because of their excellent thermal conductivities (ca. 10²–10³ W·(m·K)^?1 along their lateral axes) and morphological merits. However, the implications of morphological features such as the lateral length and thickness of graphene or graphene-like materials have not yet been identified. In this study, a controlled dissociation of bulk graphite to graphite nanosheets (GNSs) using a low-cost, ecofriendly bead mill process was extensively examined and, when configured in a 3D framework architecture formation, the size-controlled GNSs demonstrated that the thermal conductivities of a 3D interconnected framework of GNSs and the corresponding polymer nanocomposite were intimately correlated with the size of the GNSs, thus demonstrating the successful preparation of an efficient thermal management material without highly sophisticated efforts. The capability of controlling the lateral size and thickness of the GNSs as well as the use of a 3D interconnected framework architecture should greatly assist the commercialization of high-quality graphene-based thermal management materials in a scalable production process.     

An Empirical Study on Factors Influencing Consumers' Initial Trust in Wearable Commerce

This paper focuses on the factors influencing consumers' initial trust in wearable commerce. Specifically, a conceptual model for wearable commerce is created and hypotheses are developed to study the initial trust. Through a survey of 266 valid questionnaires, we carry out an empirical analysis via Structure Equation Modeling method. The results show that five proposed factors (privacy concern, trust propensity, performance expectancy, facilitating conditions, hedonic motivation) all have significant effects on initial trust in wearable commerce. The conclusion is valuable to future research on wearable commerce. Theoretical and practical implications are also presented.     

Megasonic agitation for enhanced electrodeposition of copper

In this paper we propose an agitation method based on megasonic acoustic streaming to overcome the limitations in plating rate and uniformity of the metal deposits during the electroplating process. Megasonic agitation at a frequency of 1 MHz allows the reduction of the thickness of the Nernst diffusion layer to less than 600 nm. Two applications that demonstrate the benefits of megasonic acoustic streaming are presented: the formation of uniform ultra-fine pitch flip-chip bumps and the metallisation of high aspect ratio microvias. For the latter application, a multi-physics based numerical simulation is implemented to describe the hydrodynamics introduced by the acoustic waves as they travel inside the deep microvias.     

Some microwave applications of BaSrTiO3 and high temperature superconductors

Abstract

The group at the University of Colorado has been working on the applications of BaSrTiO₃ and high temperature superconductors to microwave circuits and systems with support from Superconducting Core Technologies, NASA and ONR. This work has included the development of a voltage tunable oscillator, a phase shifter, and a voltage tunable phased array antenna system. An important aspect of this program is the lattice match between the high temperature superconductor and the ferroelectric materials which enables us to grow thin films of either material on each other. By choosing the appropriate barium stronium ratio we are able to obtain changes in the dielectric constant of 5 to 1 in bulk capacitors at 77 K, the liquid nitrogen boiling temperature. Phase shifts of a little less than 126° at 10 Ghz have been obtained by applying 5 volts on a one centimeter coplanar line. The proposed phased array systems should enable us to point the beam radiated from the antenna in an arbitrary direction using two control voltages of less than 50 volts. We believe this approach leads to the possibility of inexpensive electronically scannable antenna systems which could be used for mobile communications with satellites and cellular systems.