Does current noise arise from the competition between conductive and insulating phase at the trap-filling transition in organic semiconductors?

The relative current noise power spectral density S = S(I)(f)/I(2) observed in organic semiconductors exhibits a maximum at the trap filling transition between the ohmic and the space-charge-limited-current regime. The electrostatic conditions determining the crossover from ohmic to space-charge-limited transport at the trap filling transition are here discussed. These arguments shed light on the need to adopt a percolative fluctuations model to account for the competition between insulating and conductive phases as the voltage increases

ENGAGEMENT TO SOCIAL NETWORKING: CHALLENGES AND OPPORTUNITIES TO EDUCATORS

In recent years many students and teachers are not only very well connected with the print media but to the social/online media as well. Facebook, Twitter, Friendster My Space, etc. have become their interest especially in information dissemination among others. Educators utilized social networking sites for teaching and learning. This study explored the social networking engagement of Education students and teachers in the six universities in Cebu City, second semester of the academic year 2012-2013. This further analyzes and documents its opportunities and challenges to teaching and learning. Descriptive Study - Cross-Sectional Study was applied in this study. The use of facebook is very effective in order to collaborate with teachers and students. The use of SNS engenders opportunities as well as challenges in the all aspects of human undertaking, maybe it be personal, academic or societal in nature. Every individual is made conscious/ responsible in its utilization that would create a positive change in the world. Findings revealed that social networking has become a very good avenue to teaching and learning. The study concluded that Social Networking sites are beneficial to educators but it has also challenges and opportunities encountered by the educators

Retrogression and re-ageing of 7075 aluminium alloy : microstructural characterization

Industrial Summary: The 7075 aluminium alloy presents a low stress corrosion cracking strength when aged to achieve maximum mechanical strength, T6 temper; high stress corrosion cracking strength is attained with overageing, T7 temper; but with loss of mechanical strength. Retrogression and re-ageing treatments improves the stress corrosion behaviour of the alloy whilst maintaining the mechanical resistance of the T6 temper. The microstructures produced by the retrogression and re-ageing treatments were characterized in this study by transmission electron microscopy, electron diffraction and differential scanning calorimetry. The precipitation is extremely Æne and distributed homogeneously inside the grains, being slightly denser and more stable than that resulting from the T6 temper; whilst the grain boundary precipitation is quite different from that resulting from T6 treatment, the particles being coarser, and much closer to the precipitation resulting from T7 temper. The retrogression temperature is the main property controlling factor; a higher retrogression temperature, increasing the dissolution degree, promotes the formation of more stable precipitates on re-ageing

Neutron imaging and modelling inclined vortex driven thin films.

The vortex fluidic device (VFD) is a thin film microfluidic platform which has a wide range of applications in synthesis and other areas of science, and it is important to understand the nature of the thin film of liquid in its inclined rapidly rotating tube. Neutron imaging has been used to determine the thickness of the film in a quartz tube with its shape modelled mathematically, showing good agreement between the model and experiments. The resultant equations are useful for studying VFD mediated processing in general, for which the optimal tilt angle of the tube is typically 45°. This includes its utility for the intelligent scale-up of organic syntheses, as demonstrated in the present study by the scaling up of an imine and amide synthesis to >1 g/min

Genomic variability of Citrus tristeza virus (CTV) isolates introduced into Morocco

Genomic variability of the coat protein gene of Citrus tristeza virus isolates obtained from old Meyer lemon introductions in Morocco and more recent budwood introductions from Spain were studied. The coat protein gene of the virus was amplified directly from infected tissue by immunocapture RT-PCR and analysed by single stranded conformation polymorphism (SSCP) and sequencing. Each isolate consisted of several related genomic variants, typical of a quasi-species. Although SSCP analysis has only limited typing ability it could be used in an initial screening to discriminate between isolates of different origin and to analyse the genomic structure of each isolate. Sequence analysis showed that the isolates of Spanish origin were closely related to mild isolates characterised in Florida and in Portugal. The Meyer lemon isolate on the other hand was related to severe strains of Meyer lemon characterised in Florida some years ago and to other severe strains from Brasil. A knowledge of the coat protein gene sequence is useful to trace the origin of the isolates

Polyphenol oxidase activity and colour changes of peeled potato (cv. Monalisa) in vacuum

Minimal processing of vegetables has some undesirable physiological consequences. The shelf life of peeled raw potatoes is limited by the onset of enzymatic browning at the cut surfaces. It is generally accepted that polyphenol oxidase (PPO) is the enzyme mainly responsible for this type of browning. This work aimed to study the effect of vacuum storage at 4°C on the colour, which is the main parameter limiting the shelf life of potato (cv. Monalisa). PPO activity was evaluated as well with the aim to investigate the relation with colour changes.info:eu-repo/semantics/acceptedVersio

The design of a digital coincidence-detection trigger system for a RPC-based pet

A complex task for PET cameras is the design of an appropriate coincidence-detection trigger as it usually encompasses coincidences in a large number of channels and tight time specifications. Those requirements are even greater for a resistive plate chamber (RPC)-based detector technology as the time window specification is quite small (in the order of a few hundred picoseconds) and the number of coincidence-channels can be quite large (more than 100 in a large camera). In this work we discuss on-going work aimed at implementing the coincidence-detection algorithm inside a FPGA along with the necessary TDCs. The use of the developed solution in a first prototype of an RPC-based small animal PET and its scalability to the case of a human, all-body, PET, is discussed.info:eu-repo/semantics/publishedVersio

An integrated project of entrepreneurship and innovation in engineering education

This paper presents a new line of project based learning in the School of Engineering of University of Minho: the Innovation and Entrepreneurship Integrated Project (IEIP). Four groups, each one composed of students from different engineering integrated master courses – Mechanical, Industrial Electronics and Computers, Polymer, Industrial Management – compete against each other in developing or improving commercial products manufactured by actual industries. There have been so far five editions of the IEIP, with five different companies and five diverse products, however, all these products included components that required knowledge from all the engineering courses involved. Only with the cooperation between the students of the various courses that compose each multidisciplinary team, the success is attainable. As each student has to deal with various engineering scopes, students’ technical skills are greatly enlarged and they acquire a multidisciplinary knowledge that was not possible in another way. Their soft skills like project management, teamwork, communication ability and personal development, which are valuable requisites for their future employers, are also improved. The participating industries also take advantage of the project: the groups competing against each other act as a multiskilled work force, actually making proposals capable of improving their products, their efficiency, and reducing costs