IR-sintering of ink-jet printed metal-nanoparticles on paper

Sintering of printed metal nanoparticles can be made not only by conventional heating, but also by, e.g., electrical, microwave, plasma, laser and flash lamp annealing. We demonstrate sintering by using low-cost incandescent lamps as an effective way of obtaining highly conductive contacts of two types of ink-jet printed metal-nanoparticle inks on paper; both alkanethiol protected gold nanoparticles and a commercially available silver nanoparticle ink. This low-cost roll-to-roll compatible sintering process is especially suitable on paper substrates because of the high diffuse reflectance, relatively high thermal stability and low thermal conductivity of paper. A volume resistivity of around 10 μΩ cm was achieved of the inkjetted silver nanoparticles within 15 s of exposure to an IR lamp, which corresponds to a conductivity of 10-20% of that of bulk silver. Too long exposure time and too high intensity, however, lead to darkening of the paper fibers. Both the crack formation and the coffee ring effect of the inkjet printed gold nanoparticles were, furthermore, found to be reduced on paper as compared to glass or plastic substrates.     

The Discrete Basis Problem

Matrix decomposition methods represent a data matrix as a product of two factor matrices: one containing basis vectors that represent meaningful concepts in the data, and another describing how the observed data can be expressed as combinations of the basis vectors. Decomposition methods have been studied extensively, but many methods return real-valued matrices. Interpreting real-valued factor matrices is hard if the original data is Boolean. In this paper, we describe a matrix decomposition formulation for Boolean data, the Discrete Basis Problem. The problem seeks for a Boolean decomposition of a binary matrix, thus allowing the user to easily interpret the basis vectors. We also describe a variation of the problem, the Discrete Basis Partitioning Problem. We show that both problems are NP-hard. For the Discrete Basis Problem, we give a simple greedy algorithm for solving it; for the Discrete Basis Partitioning Problem we show how it can be solved using existing methods. We present experimental results for the greedy algorithm and compare it against other, well known methods. Our algorithm gives intuitive basis vectors, but its reconstruction error is usually larger than with the real-valued methods. We discuss about the reasons for this behavior.     

Anger and aggression among drivers in three European countries

Recent reports of 'road rage' in the British media give the impression that driver aggression is escalating. In order to understand this phenomenon we need to know what it is about driving that provokes motorists to feel anger and then to go on to express that anger in the form of aggression. A postal questionnaire survey of more than 2500 drivers was carried out in three European countries: Britain, Finland and the Netherlands. The study had three main aims: (a) to discover how angry, if at all, a range of situations on the road make drivers, (b) to find out how many drivers are likely to react aggressively to those situations, and (c) to investigate individual and/or cultural differences in terms of anger and/or aggressive responses among motorists. Results indicate that the same types of behaviour provoke anger and aggression in all three countries, and that traffic density may play a role.     

Real‐Time Label‐Free Monitoring of Nanoparticle Cell Uptake

The surface plasmon resonance technique in combination with whole cell sensing is used for the first time for real‐time label‐free monitoring of nanoparticle cell uptake. The uptake kinetics of several types of nanoparticles relevant to drug delivery applications into HeLa cells is determined. The cell uptake of the nanoparticles is confirmed by confocal microscopy. The cell uptake of silica nanoparticles and polyethylenimine–plasmid DNA polyplexes is studied as a function of temperature, and the uptake energies are determined by Arrhenius plots. The phase transition temperature of the HeLa cell membrane is detected when monitoring cell uptake of silica nanoparticles at different temperatures. The HeLa cell uptake of the mesoporous silica nanoparticles is energy‐independent at temperatures slightly higher than the phase transition temperature of the HeLa cell membrane, while the uptake of polyethylenimine–DNA polyplexes is energy‐dependent and linear as a function of temperature with an activation energy of Ea = 62 ± 7 kJ mol^?1 = 15 ± 2 kcal mol^?1. The HeLa cell uptake of red blood cell derived extracellular vesicles is also studied as a function of the extracellular vesicle concentration. The results show a concentration dependent behavior reaching a saturation level of the extracellular vesicle uptake by HeLa cells.     

Visual measurement and tracking in laser hybrid welding

This paper presents a novel system for the automatic analysis of a hybrid welding process. High-speed imaging and laser illumination are used to measure the regularity of electric arc frequency and flight directions of filler metal droplets. A fuzzy c-means clustering method is used to detect arcs and segment the video sequences. The droplets are localized by combining principal component analysis and a support vector machine classifier. The flight of a droplet is tracked using Kalman filtering. Experiments indicate that the system is able to track the flights of droplets and to determine the regularity of the arc frequency with a high accuracy if the imaging conditions are stable.

Determining Attributes to Maximize Visibility of Objects

In recent years, there has been significant interest in the development of ranking functions and efficient top-k retrieval algorithms to help users in ad hoc search and retrieval in databases (e.g., buyers searching for products in a catalog). We introduce a complementary problem: How to guide a seller in selecting the best attributes of a new tuple (e.g., a new product) to highlight so that it stands out in the crowd of existing competitive products and is widely visible to the pool of potential buyers. We develop several formulations of this problem. Although the problems are NP-complete, we give several exact and approximation algorithms that work well in practice. One type of exact algorithms is based on Integer Programming (IP) formulations of the problems. Another class of exact methods is based on maximal frequent item set mining algorithms. The approximation algorithms are based on greedy heuristics. A detailed performance study illustrates the benefits of our methods on real and synthetic data.