Diamond Surface Modification to Enhance Interfacial Thermal Conductivity in Al/Diamond Composites

Diamond/metal composites are very attractive materials for electronics because their excellent thermal properties make them suitable for use as heat sink elements in multifunctional electronic packaging systems. To enlarge the potential applications of these composites, current efforts are mainly focused on investigating different ways to improve the contact between metal and diamond. In the present work, a theoretical study has been carried out to determine the differences between the interfacial thermal conductance of aluminum/diamond and aluminum/graphite interfaces. Additionally, diamond particles were surface modified with oxygen to observe how it affects the quality of the diamond surface. The characterization of the surface of diamonds has been performed using different surface analysis techniques, especially x-ray photoelectron spectroscopy and temperature-programmed desorption.

Arte, prazer e bisturi: construção corporal através da body modification

In view of a field research carried out by a team connected to the universe of body modification, it is possible to discern some uses and meanings linked to these forms of body interventions. Body modification or body change is part of the circuit of piercings and tattoos, although they are socially less thinned and more extreme, like scarifications, subcutaneous implants, bifurcated tongues, surfaces and body suspensions. The aim of this paper is to cast an anthropological glance on these practices, joining at the same context all the subjects involved with these techniques, placing them inside the same relational focus and capturing their journeys and trajectories. The discussions are concentrated on the notion of body building and urban life style. Ideas as personal distinctness and prestige imitation are also present in this universe, as well as matters attached to genre, pleasure, art, and to the so-called alternative circuit . This way, the ethnography so far presented here, reveals the complex and contemporaneous character of these practices of body markings in which the body appears as the central element in the experiences of the subjects of this study

Mineral stress response of Vitis cell wall transcriptome: identification, characterization and expression of genes from key families involved in wall biosynthesis and modification

Doutoramento em Engenharia Agronómica - Instituto Superior de Agronomia - UL

Targeted gene modification in Fragaria vesca mediated by CRISPR/Cas9 system

Genome editing is becoming an important biotechnological tool for gene function analysis and crop improvement, being the CRISPR-Cas9 (Clustered Regularly Interspaced Short Palindromic Repeat-CRISPR associated protein 9) system the most widely used. The natural CRISPR/Cas9 system has been reduced to two components: a single-guide RNA (sgRNA) for target recognition via RNA-DNA base pairing, which is commonly expressed using a promoter for small-RNAs (U6 promoter), and the Cas9 endonuclease for DNA cleavage (1). To validate the CRISPR/Cas9 system in strawberry plants, we designed two sgRNAs directed against the floral homeotic gene APETALA3 (sgRNA-AP3#1 and sgRNA-AP3#2). This gene was selected because ap3 mutations induce clear developmental phenotypes in which petals and stamens are missing or partially converted to sepals and carpels respectively (2). In this work, we used two different U6 promoters to drive the sgRNA-AP3s expression: AtU6-26 from Arabidopsis (4), and a U6 promoter from Fragaria vesca (FvU6) (this work). We also tested two different coding sequences of Cas9: a human- (hSpCas9) (3) and a plant-codon optimized (pSpCas9) (this work). Transient expression experiments using both CRISPR/Cas9 systems (AtU6-26:sgRNA-AP3#1_35S:hSpCas9_AtU6-26:sgRNA-AP3#2 and FvU6:sgRNA-AP3#1_35S:pSpCas9_FvU6:sgRNA-AP3#2) were performed infiltrating Agrobacterium tumefaciens into F. vesca fruits. PCR amplification and sequencing analyses across the target sites showed a deletion of 188-189 bp corresponding to the region comprised between the two cutting sites of Cas9, confirming that the CRISPR/Cas9 system is functional in F. vesca. Remarkably, the two systems showed different mutagenic efficiency that could be related to differences in expression of the U6 promoters as well as differences in the Cas9 transcripts stability and translation. Stable transformants for both F. vesca (2n) and Fragaria X anannassa (8n) are currently being established to test whether is possible to obtain heritable homozygous mutants derived from CRISPR/Cas9 strategies in strawberry. Thus, our work offers a promising tool for genome editing and gene functional analysis in strawberry. This tool might represent a more efficient alternative to the sometimes inefficient RNAi silencing methods commonly used in this species.

Modeling spectral changes in singing voice for pitch modification

We present an advanced method to achieve natural modifications when applying a pitch shifting process to singing voice by modifying the spectral envelope of the audio ex- cerpt. To this end, an all-pole spectral envelope model has been selected to describe the global variations of the spectral envelope with the changes of the pitch. We performed a pitch shifting process of some sustained vowels with the envelope processing and without it, and compared both by means of a survey open to volunteers in our website.

Effect of bulk microstructure of commercially pure titanium on surface characteristics and fatigue properties after surface modification by sand blasting and acid-etching

Surface modification techniques are widely used to enhance the biological response to the implant materials. These techniques generally create a roughened surface, effectively increasing the surface area thus promoting cell adhesion. However, a negative side effect is a higher susceptibility of a roughened surface to failure due to the presence of multiple stress concentrators. The purpose of the study reported here was to examine the effects of surface modification by sand blasting and acid-etching (SLA) on the microstructure and fatigue performance of coarse-grained and ultrafine-grained (UFG) commercially pure titanium. Finer grain sizes, produced by equal channel angular pressing, resulted in lower values of surface roughness in SLA-processed material. This effect was associated with greater resistance of the UFG structure to plastic deformation. The fatigue properties of UFG Ti were found to be superior to those of coarse-grained Ti and conventional Ti-6Al-4V, both before and after SLA-treatment.

An investigation of effects of modification processes on physical properties and mechanism of drug release for sustaining drug release from modified rice

The aim of this study was to investigate the effect of modification processes on physical properties and explain the mechanism of sustained drug release from modified rice (MR). Various types of Vietnamese rice were introduced in the study as the matrices of sustained release dosage form. Rice was thermally modified in water for a determined temperature at different times with a simple process. Then tablets containing MR and isradipine, the model drug, were prepared to investigate the capability of sustained drug release. Scanning electron microscopy (SEM) was used to determine different morphologies between MR formulations. Flow property of MR was analyzed by Hausner ratio and Carr's indices. The dissolution rate and swelling/erosion behaviors of tablets were evaluated at pH 1.2 and pH6.8 at 37±0.5°C. The matrix tablet containing MR showed a sustained release as compared to the control. The SEM analyses and swelling/erosion studies indicated that the morphology as well as swelling/erosion rate of MR were modulated by modification time, drying method and incubation. It was found that the modification process was crucial because it could highly affect the granule morphologies and hence, leading to the change of flowability and swelling/erosion capacity for sustained release of drug.

Towards enhanced performance thin-film composite membranes via surface plasma modification

Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

Xylanolytic modification in wheat flour and its effect on dough rheological characteristics and bread quality attributes

Effects of various xylanase treatments applied at different stages of bread making process on dough rheological characteristics and bread quality attributes were investigated. Different doses (200, 400, 600, 800, and 1000 IU) of purified enzyme were applied at two stages (tempering and mixing). In milling and dough making processes, both types of flour (subjected to enzyme treatment during tempering and flour mixing) exhibited decreasing trend in water absorption, dough development time, dough stability, softening of dough, dough mixing time, viscosity peak, set back, and increasing tendency in peak height and pasting temperature. Treatments during tempering resulted in more significant effects as compared to applications during flour mixing. The dough rising during proofing resulted in enhancement from 137±3.21% (control) to maximum value (192.33±2.90%), when 600 IU of xylanases were applied to 1 kg of wheat grains during tempering. The bread sensory attributes also exhibited significant improvement in response to various doses of purified enzymes.

THE PERFORMANCE AND MODIFICATION OF RECYCLED ELECTRONIC WASTE PLASTICS FOR THE IMPROVEMENT OF ASPHALT PAVEMENT MATERIALS

Bulk electric waste plastics were recycled and reduced in size into plastic chips before pulverization or cryogenic grinding into powders. Two major types of electronic waste plastics were used in this investigation: acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS). This research investigation utilized two approaches for incorporating electronic waste plastics into asphalt pavement materials. The first approach was blending and integrating recycled and processed electronic waste powders directly into asphalt mixtures and binders; and the second approach was to chemically treat recycled and processed electronic waste powders with hydro-peroxide before blending into asphalt mixtures and binders. The chemical treatment of electronic waste (e-waste) powders was intended to strengthen molecular bonding between e-waste plastics and asphalt binders for improved low and high temperature performance. Superpave asphalt binder and mixture testing techniques were conducted to determine the rheological and mechanical performance of the e-waste modified asphalt binders and mixtures. This investigation included a limited emissions-performance assessment to compare electronic waste modified asphalt pavement mixture emissions using SimaPro and performance using MEPDG software. Carbon dioxide emissions for e-waste modified pavement mixtures were compared with conventional asphalt pavement mixtures using SimaPro. MEPDG analysis was used to determine rutting potential between the various e-waste modified pavement mixtures and the control asphalt mixture. The results from this investigation showed the following: treating the electronic waste plastics delayed the onset of tertiary flow for electronic waste mixtures, electronic waste mixtures showed some improvement in dynamic modulus results at low temperatures versus the control mixture, and tensile strength ratio values for treated e-waste asphalt mixtures were improved versus the control mixture.

Continuité des traits psychopathiques et contribution de la qualité des relations parents-enfant, enseignant-enfant et pairs-enfant à la modification de ces traits chez des enfants présentant un trouble des conduites

Ce mémoire de recherche investigue la continuité des traits psychopathiques chez les enfants de même que la contribution de la qualité des relations avec les parents, l’enseignant et les pairs à la variabilité de ces traits. La présente étude porte sur 281 enfants (48 % de filles) âgés de 6 à 9 ans avec un trouble des conduites. Trois dimensions de traits psychopathiques ont été évaluées chez les enfants (narcissisme, impulsivité, insensibilité), en plus d’un construit global. Ces traits ont été mesurés avec l’APSD par un parent et un enseignant à l’entrée dans l’étude (temps 0 ou T0) puis à une année d’intervalle sur une période de 4 ans (T1 à T4). Ces évaluateurs ont également évalué la qualité de leur relation avec l’enfant ainsi que celle avec les pairs (T0). Les résultats montrent que la stabilité différentielle des traits sur l’intervalle de quatre années va de faible à modérée pour chaque dimension. Cependant, l’analyse de la stabilité des niveaux moyens indique que c’est entre le T0 et le T2 que la variabilité des traits est la plus significative, la stabilité étant plus importante entre le T2 et le T4. Enfin, l’étude démontre qu’aucune des variables relationnelles ne contribue significativement à la variabilité des traits quatre ans plus tard et ce, pour chacune des dimensions ainsi que pour le construit global. stabilité, traits psychopathiques, traits antisociaux, trouble des conduites, enfants, relation avec le parent, relation avec l’enseignant, relation avec les pairs