Investigation of AlInN barrier ISFET structures with GaN capping for pH detection

In the last decade the interest in nitride-based sensors (gas, ions...) and bio-sensors is increased. In the case of ion sensitive FET (ISFET), gate voltages induced by ions adsorbed onto the gate region modulate the source-drain currents.

CIMBNC- Combination and interactions of three kinds of nanoclays structural modifiers, for the colored bio-nanocomposites optimization

Biopolymers do not have competitive prices, which has prevented their industrial exploitation on a global scale so far. In this context, Using nanoclays, improvements in certain biopolymer properties, mainly mechanical and thermal, have been achieved. However, research has been much less focused on changing optical properties through the incorporation of nanoclays. At the same time, current research has focused on obtaining nanopigments, by organic dyes adsoptions into different nanoclays in order to achieve sustainable colouring and high performance materials. By combining advances in these lines of research, biodegradable composites with optimal mechanical and optical properties can be obtained. The aim of this work is to find the optimal formulation of naturally sourced nanopigments, incorporate them into a biological origin epoxy resin, and obtain a significant improvement in their mechanical, and optical properties. We combine three structural modifiers in the nanopigment synthesis: surfactant, silane and mordant salt. The latter was selected in order to replicate the mordant textile dyeing with natural dyes. Using a Taguchi’s desing L8, we look for the effect of the presence of the modifiers, the pH acidification, and the interactions effect between the synthesis factors. Three natural dyes were selected: chlorophyll, beta-carotene, and beetroot extract. Furthermore we use two kinds of laminar nanoclays, differentiated by the ion exchange charge: montmorillonite, and hydrotalcite. Then the thermal, mechanical and colorimetric characterization of the bionanocomposite materials was carried out. The optimal conditions to obtain the best bionanocomposite materials are using acid pH, and modifying the nanoclays with mordant and surfactant.

Contributions to Physics-Based Aeroservoelastic Uncertainty Analysis

Thesis (Ph.D.)--University of Washington, 2016-06

Reference values for whole body and cerebral multi-frequency bio-impedance data in neonates less than 12 h postpartum

Multiple frequency bio-electrical impedance analysis (MFBIA) may be useful for monitoring fluid balance in newborn infants or to provide early prediction of the outcome following perinatal asphyxia. A reference range of data is needed for identification of babies with abnormal impedance values. This was a cross-sectional observational study in 84 term and near-term healthy neonates less than 12 h postpartum. Whole body and cerebral MFBIA measurements were performed at the bedside in the post-natal ward. Gestational age, post-natal age, gender, birthweight, head circumference and foot length measures were recorded. Reference values for impedance at the characteristic frequency (Z(C)) and resistance at zero frequency (R-0) are reported for whole body and cerebral impedance. Significant correlations (p < 0.05) were observed between whole body impedance and birthweight, footlength and head circumference. Females had a significantly higher whole body R0 than males. Cerebral impedance did not correlate significantly with any of the demographic measures and therewere no gender differences observed for cerebral impedance. The reference range for whole body multi-frequency bio-impedance values in term and near-term infants within the first 12 h postpartum can be calculated from the footlength (FL) using the following equations: Z(C) = (942.9 - 4.818* FL) +/- 124.6 Omega; R-0 = (1042 - 4.520(*)FL) +/- 135.5 Omega. For cerebral impedance the reference range is 29.5-48.7 Omega for Z(C) and 33.7-58.0 Omega for R-0.

The development and optimisation of a fast pyrolysis process for bio-oil production

A two-tier study is presented in this thesis. The first involves the commissioning of an extant but at the time, unproven bubbling fluidised bed fast pyrolysis unit. The unit was designed for an intended nominal throughput of 300 g/h of biomass. The unit came complete with solids separation, pyrolysis vapour quenching and oil collection systems. Modifications were carried out on various sections of the system including the reactor heating, quenching and liquid collection systems. The modifications allowed for fast pyrolysis experiments to be carried out at the appropriate temperatures. Bio-oil was generated using conventional biomass feedstocks including Willow, beechwood, Pine and Miscanthus. Results from this phase of the research showed however, that although the rig was capable of processing biomass to bio-oil, it was characterised by low mass balance closures and recurrent operational problems. The problems included blockages, poor reactor hydrodynamics and reduced organic liquid yields. The less than optimal performance of individual sections, particularly the feed and reactor systems of the rig, culminated in a poor overall performance of the system. The second phase of this research involved the redesign of two key components of the unit. An alternative feeding system was commissioned for the unit. The feed system included an off the shelf gravimetric system for accurate metering and efficient delivery of biomass. Similarly, a new bubbling fluidised bed reactor with an intended nominal throughput of 500g/h of biomass was designed and constructed. The design leveraged on experience from the initial commissioning phase with proven kinetic and hydrodynamic studies. These units were commissioned as part of the optimisation phase of the study. Also as part of this study, two varieties each, of previously unreported feedstocks namely Jatropha curcas and Moringa olifiera oil seed press cakes were characterised to determine their suitability as feedstocks for liquid fuel production via fast pyrolysis. Consequently, the feedstocks were used for the production of pyrolysis liquids. The quality of the pyrolysis liquids from the feedstocks were then investigated via a number of analytical techniques. The oils from the press cakes showed high levels of stability and reduced pH values. The improvements to the design of the fast pyrolysis unit led to higher mass balance closures and increased organic liquid yields. The maximum liquid yield obtained from the press cakes was from African Jatropha press cake at 66 wt% on a dry basis.

Characteristics of the upper phase of bio-oil obtained from co-pyrolysis of sewage sludge with wood, rapeseed and straw

Sewage sludge was pyrolysed with 40% mixed wood, 40% rapeseed and 40% straw. The reason for the mixture of different biomass is to investigate the impact of co-pyrolysis on the upper phase of bio-oil in terms of changes to composition, elemental analysis, viscosity, water content, pH, higher heating value and acid number that could impact on their applications. The biomass was pyrolysed in a laboratory at 450 °C and bio-oil was collected from two cooling traps. The bio-oil obtained from co-pyrolysis of sewage sludge with wood, rapeseed and straw was analysed for composition using the gas chromatography mass spectrometry. The upper phase from the co-pyrolysis process was also characterised for ultimate analysis, higher heating values, water content, viscosity, pH and acid number. There was an increase in the amount of upper phase produced with co-pyrolysis of 40% rapeseed. It was also found that the upper phase from sewage sludge with mixed wood has the highest viscosity, acid number and lowest pH. The bio-oil containing 40% straw was found to have a pH of 6.5 with a very low acid number while the 40% rapeseed was found to have no acid number. Sewage sludge with 40% rapeseed was found to have the highest energy content of 34.8 MJ/kg, 40% straw has 32.5 MJ/kg while the 40% mixed wood pyrolysis oil has the lowest energy content of 31.3 MJ/kg. The 40% rapeseed fraction was found to have the highest water content of 8.2% compared to other fractions.

Catalytic pyrolysis of rice husk for bio-oil production

Catalytic pyrolysis experiments have been carried out on Brunei rice husk (BRH) to obtain bio-oil using a fixed-bed pyrolysis rig. ZSM-5, Al-MCM-41, Al-MSU-F and Brunei rice husk ash (BRHA) were used as the catalysts for the catalytic pyrolysis experiments and comparison was done to analyse the changes in the bio-oil properties and yield. Properties of the liquid catalytic and non-catalytic bio-oil were analysed in terms of water content, pH, acid number, viscosity, density and calorific value. The bio-oil chemical composition shows that ZSM-5 increases the production of aromatic hydrocarbons and light phenols, whilst Al-MCM-41 reduces the acetic acid production. The catalytic runs increased the calorific value and water content in the bio-oil, whilst viscosity, density and acid number is decreased. © 2012 Elsevier B.V. All rights reserved.

Impact of Miscanthus x giganteus senescence times on fast pyrolysis bio-oil quality

In this study the impact of senescence and harvest time in Miscanthus on the quality of fast pyrolysis liquid (bio-oil) was investigated. Bio-oil was produced using a 1kgh fast pyrolysis reactor to obtain a quantity of bio-oil comparable with existing industrial reactors. Bio-oil stability was measured using viscosity, water content, pH and heating value changes under specific conditions. Plant developmental characteristics were significantly different (P=0.05) between all harvest points. The stage of crop senescence was correlated with nutrient remobilisation (N, P, K; r=0.9043, r=0.9920, r=0.9977 respectively) and affected bio-oil quality. Harvest time and senescence impacted bio-oil quality and stability. For fast pyrolysis processing of Miscanthus, the harvest time of Miscanthus can be extended to cover a wider harvest window whilst still maintaining bio-oil quality but this may impact mineral depletion in, and long term sustainability of, the crop unless these minerals can be recycled. © 2012 Elsevier Ltd.

Novel pH‐and temperature‐responsive methacrylamide microgels

A novel transition temperature in MeAM copolymer microgels is reported. Despite the fact that MeAM homopolymers do not show thermosensitive properties, a specific synthetic strategy leads to a thermo-responsive swelling behavior that could be potentially useful in medical and/or industrial applications. The pH and temperature-dependent swelling response of microgels of MeAM copolymerized with 2-aminomethylpyridine and ethylenediamine is reported. The changes in particle sizes, which depend on the nature of the surrounding environment, are recorded by QELS. The relation between copolymer structure and its novel behavior is analyzed by several techniques (1H NMR, TGA).

Specific pH‐responsive folate‐conjugate microgels designed for antitumor therapy

Colloidal nanosized folate-conjugated hydrogels for targeted chemotherapy were prepared via a versatile and efficient postsynthetic modification pathway starting from P(NPA-co-NIPAM). The modifications included the introduction of 4-methylpyridine as pH-sensitive pendant groups and the conjugation of folic acid to the microgel network. The microgels showed a specific swelling at pH?

Results of the IEA round robin on viscosity and stability of fast pyrolysis bio-oils

An international round robin study of the stability of fast pyrolysis bio-oil was undertaken. Fifteen laboratories in five different countries contributed. Two bio-oil samples were distributed to the laboratories for stability testing and further analysis. The stability test was defined in a method provided with the bio-oil samples. Viscosity measurement was a key input. The change in viscosity of a sealed sample of bio-oil held for 24 h at 80 °C was the defining element of stability. Subsequent analyses included ultimate analysis, density, moisture, ash, filterable solids, and TAN/pH determination, and gel permeation chromatography. The results showed that kinematic viscosity measurement was more generally conducted and more reproducibly performed versus dynamic viscosity measurement. The variation in the results of the stability test was great and a number of reasons for the variation were identified. The subsequent analyses proved to be at the level of reproducibility, as found in earlier round robins on bio-oil analysis. Clearly, the analyses were more straightforward and reproducible with a bio-oil sample low in filterable solids (0.2%), compared to one with a higher (2%) solids loading. These results can be helpful in setting standards for use of bio-oil, which is just coming into the marketplace. © 2012 American Chemical Society.

Catalytic intermediate pyrolysis of Brunei rice husk for bio-oil production

Rice husks from Brunei were subjected via intermediate pyrolysis for bio-oil production. Two main objectives were set out for this study. The application of intermediate pyrolysis on Brunei rice husk for the production of bio-oil is the main objective of this experiment. Characterisation of the rice husks was inclusive as a pre-requisite step to assess the suitability as feedstock for production of liquid fuels. Following on from the characterisation results, a temperature of 450°C was established as the optimum temperature for the production of bio-oil. A homogenous bio-oil was obtained from the pyrolysis of dry rice husk, and the physicochemical properties and chemical compositions were analysed. The second objective is the introduction of catalysts into the pyrolysis process which aims to improve the bio-oil quality, and maximise the desired liquid bio-oil properties. The incorporation of the catalysts was done via a fixed tube reactor into the pyrolysis system. Ceramic monoliths were used as the catalyst support, with montmorillonite clay as a binder to attach the catalysts onto the catalyst support. ZSM-5, Al-MCM-41, Al-MSU-F and Brunei rice husk ash (BRHA) together with its combination were adopted as catalysts. Proposed criterions dictated the selection of the best catalysts, subsequently leading to the optimisation process for bio-oil production. ZSM-5/Al-MCM-41 proved the most desirable catalyst, which increases the production of aromatics and phenols, decreased the organic acids and improved the physicochemical properties such as the pH, viscosity, density and H:C molar ratios. Variation in the ratio and positioning of both catalysts were the significant key factor for the catalyst optimisation study.

Decolourisation of Acid orange 7 in a microbial fuel cell with a laccase-based biocathode: Influence of mitigating pH changes in the cathode chamber

Biocathodes may be a suitable replacement of platinum in microbial fuel cells (MFCs) if the cost of MFCs is to be reduced. However, the use of enzymes as bio-cathodes is fraught with loss of activity as time progresses. A possible cause of this loss in activity might be pH increase in the cathode as pH gradients in MFCs are well known. This pH increase is however, accompanied by simultaneous increase in salinity; therefore salinity may be a confounding variable. This study investigated various ways of mitigating pH changes in the cathode of MFCs and their effect on laccase activity and decolourisation of a model azo dye Acid orange 7 in the anode chamber. Experiments were run with catholyte pH automatically controlled via feedback control or by using acetate buffers (pH 4.5) of various strength (100 mM and 200 mM), with CMI7000 as the cation exchange membrane. A comparison was also made between use of CMI7000 and Nafion 117 as the transport properties of cations for both membranes (hence their potential effects on pH changes in the cathode) are different.

Charge migration induced by attosecond pulses in bio-relevant molecules

After sudden ionization of a large molecule, the positive charge can migrate throughout the system on a sub-femtosecond time scale, purely guided by electronic coherences. The possibility to actively explore the role of the electron dynamics in the photo-chemistry of bio-relevant molecules is of fundamental interest for understanding, and perhaps ultimately controlling, the processes leading to damage, mutation and, more generally, to the alteration of the biological functions of the macromolecule. Attosecond laser sources can provide the extreme time resolution required to follow this ultrafast charge flow. In this review we will present recent advances in attosecond molecular science: after a brief description of the results obtained for small molecules, recent experimental and theoretical findings on charge migration in bio-relevant molecules will be discussed.