Imaging of DNA hybridization on microscopic polypyrrole patterns using scanning electrochemical microscopy (SECM): the HRP bio-catalyzed oxidation of 4-chloro-1-naphthol

We illustrate in this paper the successful combination of the direct and feedback mode of scanning electrochemical microscopy (SECM) for the writing of oligonucleotide patterns on thin gold films alongside the imaging of DNA hybridization. The patterning process was achieved using the direct mode of SECM, where the electrical field established between the SECM tip and the gold interface was used to drive the local deposition of micrometre sized polypyrrole spots to which a 15mer oligonucleotide (ODN) strand was linked covalently. Imaging of the deposited polypyrrole-ODNs was achieved by means of the feedback mode of SECM using Ru(NH3)63+ as the mediator. The detection of the hybridization reaction of the ODN probes with their biotinylated complementary strands using SECM was possible after subsequent reactions with streptavidin and biotinylated horseradish peroxidase (HRP). The HRP-biocatalyzed oxidation of 4-chloro-1-naphthol (1) in the presence of H2O2, and the precipitation of the insoluble product 4-chloro-1-naphthon (2) on the hybridized areas on the gold film caused a local alteration of conductivity. Such a change in conductivity was sensitively detected by the SECM tip and allowed imaging of DNA arrays in a fast and straightforward way

Targeting adequate thermal stability and fire safety in selecting ionic liquid-based electrolytes for energy storage

CAPLUS AN 2014:16740(Journal; Online Computer File)International audienceThe energy storage market relating to lithium based systems regularly grows in size and expands in terms of a portfolio of energy and power demanding applications. Thus safety focused research must more than ever accompany related technological breakthroughs regarding performance of cells, resulting in intensive research on the chemistry and materials science to design more reliable batteries. Formulating electrolyte solutions with nonvolatile and hardly flammable ionic liquids instead of actual carbonate mixtures could be safer. However, few definitions of thermal stability of electrolytes based on ionic liquids have been reported in the case of abuse conditions (fire, shortcut, overcharge or overdischarge). This work investigates thermal stability up to combustion of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C1C4Im][NTf2]) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([PYR14][NTf2]) ionic liquids, and their corresponding electrolytes containing lithium bis(trifluoromethanesulfonyl)imide LiNTf2. Their possible routes of degradation during thermal abuse testings were investigated by thermodynamic studies under several experimental conditions. Their behaviours under fire were also tested, including the analysis of emitted compounds

Connection-Saving Gate Assignment: A Computational Approach

The growth of the commercial aviation industry has yielded many interesting problems in the field of Operations Research, many of which are now able to be solved as both technology and mathematical optimization improve. A particularly interesting problem in airport operations re- search is the Aircraft Gate Assignment Problem (AGAP), which seeks to create a feasible match- ing between planes and flights at an airport. This problem is well-suited to modeling with Integer Programming, and has attracted research since the 1970s. Researchers of the AGAP have considered many different objectives, ranging from airline-focused objectives to more passenger-focused objective functions. In this paper, we build on the the work done by scholars of the AGAP, and present a new objective that focuses on reducing possible passenger misconnections, which we argue benefits both parties. Missed connections cost airlines hundreds of thousands of dollars annually. While some of this is inevitable, there are cases where small adjustments would allow connecting passengers to get to the gate of their flight before the door closes. This paper focuses on those small adjustments that make all the difference. Specifically, we assign flights to gates such that the number of passengers that misconnect is minimized. In effect, this is accomplished by assigning flights with passengers on them with tight connections nearby gates. Special care is given to international flights and the effect of customs clearance and security screening, and our model is applied to a real day’s operation for United Airlines at Dulles International Airport in Virginia. We found that our model has a statistically significant effect on reducing the number of passengers at risk of missing their connecting flights

The prevention of mobile phone theft: a case study of crime as pollution; rational choices and consumer demand.

This thesis makes two contributions to environmental criminology. The first contribution is a rational choice event model for mobile phone thieves. This is based on interviews with 40 mobile phone thieves. In addition, the deterrent effects of 23 designs of phone are assessed. Comparisons are made between the responses of offenders and non-offenders; and between experienced offenders and less experienced offenders. The results show that mobile phone thieves make discerning choices about which model of phone to steal at the point of theft. The factors affecting handset choice reflect Clarke s (1999) CRAVED characteristics. Mobile phone thieves are differentially deterred by a variety of design solutions, the most effective of which reduce the resale value of stolen handsets. In contrast with offenders, non-offenders are more easily deterred, and statistically significantly more deterred for five of the 23 designs presented in this thesis; do not appreciate the importance of resale value; and are not so aware of the possibilities for circumventing or neutralising security technology. The differences between offender and non-offender responses mean that offenders are arguably best placed to assess product use and misuse in the process of designing-out crime. The second contribution of this thesis is a Mobile Phone Theft Index which controls for phone availability in the absence of handset sales data. Mobile phone theft is arguably a form of pollution (Roman and Farrell, 2002) and can, therefore, be controlled using traditional pollution control instruments (Farrell and Roman, 2006). Informing the public of their risk of victimisation according to handset ownership would make security a marketable aspect of handset design, incentivising industry to decrease theft rates. Industry action to date shows evidence of obstructionism and pre-regulatory initiatives (Newman, 2004) meaning that a novel instrument such as the Index is necessary to alter the current status quo where industry costs UK society an estimated £1.2 billion per year (Mailley and Farrell, 2006)

The crime drop and the security hypothesis

Major crime drops were experienced in the United States and most other industrialised countries for a decade from the early to mid-1990s. Yet there is little agreement over explanation or lessons for policy. Here it is proposed that change in the quantity and quality of security was a key driver of the crime drop. From evidence relating to vehicle theft in two countries it is concluded that electronic immobilisers and central locking were particularly effective. It is suggested that reduced car theft may have induced drops in other crime including violence. From this platform a broader security hypothesis, linked to routine activity and opportunity theory, is outlined

Preventing phone theft and robbery: the need for government action and international coordination

The banning of stolen handsets from networks has been around for 20 years, but remains little used internationally. Where used, its effectiveness is hindered by implementation problems, reprogramming, easy fencing opportunities, and international trafficking. Kill-switches where the user remotely disables a handset and deletes data have potential but, if non-permanent, are likely to experience similar limitations. This study proposes a set of responses to be adopted by national governments with international coordination

‘A school is not a product of any one person or of any one mind’: the impact of Charles H. Scott and other Scottish Artists on the Vancouver School of Applied Art and Design

No abstract available

Étude de l'influence des patrons de soudage laser sur les propriétés mécaniques des joints soudés par recouvrement

RÉSUMÉ : Le procédé de soudage laser gagne actuellement en popularité dans l'industrie manufacturière. Les joints laser soudés par recouvrement peuvent présenter une infinité de patrons ou motifs de soudage, inhérents à la trajectoire parcourue par le faisceau laser soudeur. Pour le moment les différentes études menées se sont simplement limitées à des formes simples. Treize patrons de soudage sont sélectionnés au sein de cette étude, en lien avec le fabricant de matériel roulant ferroviaire Bombardier Transport, afin d'étudier leurs influences sur les propriétés mécaniques que sont les résistances à la traction et à la fatigue. Une étude morphologique est, préalablement aux études mécaniques, menée afin de sélectionner les paramètres des procédés, mais aussi afin de mesurer les différentes surfaces de connexion entre les plaques soudées. L'étude sur les propriétés de traction se concentre sur la recherche de la résistance ultime de chacun des patrons. Il appert que la résistance en traction des joints soudés dépend principalement de la taille de la surface de connexion et peu du patron de soudage. L'étude sur les propriétés de fatigue se limite à la recherche de la limite d'endurance à cinq millions de cycles pour un ratio de chargement de 0,5 de chaque patron à l'aide de la méthode de l'escalier. La famille des patrons circulaires s'est manifestée comme la meilleure. Des courbes de fatigue sont également tracées pour certains patrons. La pente de ces courbes s'est révélée hautement tributaire des patrons de soudage. Les ruptures par fatigue sont celles qui apparaissent le plus souvent lors de l'utilisation de pièces mécaniques et notamment dans le milieu ferroviaire. Cette recherche propose donc une modélisation du comportement en fatigue des patrons sélectionnés à l'aide de la méthode des éléments finis et des méthodes de dimensionnement à la fatigue des assemblages soudés. Le principe de Neuber est utilisé afin de modéliser la soudure. La contrainte équivalente uniaxiale complètement renversée maximale au sein de chaque patron est finalement calculée afin d'être corrélée aux limites d'endurance mesurées précédemment. -- Mot(s) clé(s) en français : patrons, soudage laser, 201LN, morphologie des soudures, essais de traction, essais de fatigue, méthode de l'escalier, méthode des éléments finis. -- ABSTRACT : The laser welding process is currently gaining popularity in the manufacturing industry. Laser welded lap joints may present an infinity of patterns or weld shape. Patterns depends on the path taken by the laser beam during the welding. Until now studies addressed only on simple laser patterns. Thirteen welding patterns are selected in this research with the railway rolling stock manufacturer Bombardier Transportation. The goal of this research is to study the pattern influence on the mechanical properties (tensile and fatigue). A morphological study is firstly conducted in order to choose the process parameters but also to measure the connexion surface sizes between the welded sheets. The studies of the tensile properties focus on the determination of the ultimate strength of each pattern. It appears that the tensile strength of the welded joints depends mostly on the connexion surface size and only a little on the welding pattern. The study of the fatigue properties restricts itself on the assessment of the fatigue limit according to the staircase method for each welding pattern. The stress ratio is 0.5 and the run out is fixed to five million cycles. The circular pattern family turns up to be the best. Fatigue curves are also presented for some patterns. Their slopes come out to be very dependent upon the welding patterns. Fatigue breaks are the most common failure of mechanical components, and so on the railways industry. Hence this research proposes a numerical modelling by means of the finite element analysis and by means of fatigue assessment methods for welded structures. Neuber's concept is used for representing the weld part. The maximal equivalent stress completely reversed uniaxial in each pattern is finally calculated in order to be correlated with the fatigue limits previously measured. -- Mot(s) clé(s) en anglais : patterns, laser welding, 201LN, weld morphologies, tensile tests, fatigue tests, staircase method, finite element method

Organic Electronics for Point-of-Care Metabolite Monitoring.

In this review we focus on demonstrating how organic electronic materials can solve key problems in biosensing thanks to their unique material properties and implementation in innovative device configurations. We highlight specific examples where these materials solve multiple issues related to complex sensing environments, and we benchmark these examples by comparing them to state-of-the-art commercially available sensing using alternative technologies. We have categorized our examples by sample type, focusing on sensing from body fluids in vitro and on wearable sensors, which have attracted significant interest owing to their integration with everyday life activities. We finish by describing a future trend for in vivo, implantable sensors, which aims to build on current progress from sensing in biological fluids ex vivo