Search

Your search keyword '"Pike, Andrew"' showing total 512 results
Start Over Author "Pike, Andrew"
512 results on '"Pike, Andrew"'

1. Low-Temperature Synthesis of Stable CaZn$_2$P$_2$ Zintl Phosphide Thin Films as Candidate Top Absorbers

Author

Quadir, Shaham, Yuan, Zhenkun, Esparza, Guillermo, Dugu, Sita, Mangum, John, Pike, Andrew, Hasan, Muhammad Rubaiat, Kassa, Gideon, Wang, Xiaoxin, Coban, Yagmur, Liu, Jifeng, Kovnir, Kirill, Fenning, David P., Reid, Obadiah G., Zakutayev, Andriy, Hautier, Geoffroy, and Bauers, Sage R.

Subjects
Condensed Matter - Materials Science
Abstract

The development of tandem photovoltaics and photoelectrochemical solar cells requires new absorber materials with band gaps in the range of ~1.5-2.3 eV, for use in the top cell paired with a narrower-gap bottom cell. An outstanding challenge is finding materials with suitable optoelectronic and defect properties, good operational stability, and synthesis conditions that preserve underlying device layers. This study demonstrates the Zintl phosphide compound CaZn$_2$P$_2$ as a compelling candidate semiconductor for these applications. We prepare phase pure, 500 nm-thick CaZn$_2$P$_2$ thin films using a scalable reactive sputter deposition process at growth temperatures as low as 100 {\deg}C, which is desirable for device integration. UV-vis spectroscopy shows that CaZn$_2$P$_2$ films exhibit an optical absorptivity of ~10$^4$ cm$^-$$^1$ at ~1.95 eV direct band gap. Room-temperature photoluminescence (PL) measurements show near-band-edge optical emission, and time-resolved microwave conductivity (TRMC) measurements indicate a photoexcited carrier lifetime of ~30 ns. CaZn$_2$P$_2$ is highly stable in both ambient conditions and moisture, as evidenced by PL and TRMC measurements. Experimental data are supported by first-principles calculations, which indicate the absence of low-formation-energy, deep intrinsic defects. Overall, our study should motivate future work integrating this potential top cell absorber material into tandem solar cells.

Published
2024

2. Assessing carrier mobility, dopability, and defect tolerance in the chalcogenide perovskite BaZrS$_3$

Author

Yuan, Zhenkun, Dahliah, Diana, Claes, Romain, Pike, Andrew, Fenning, David P., Rignanese, Gian-Marco, and Hautier, Geoffroy

Subjects
Condensed Matter - Materials Science
Abstract

The chalcogenide perovskite BaZrS$_3$ has attracted much attention as a promising solar absorber for thin-film photovoltaics. Here, we use first-principles calculations to evaluate its carrier transport and defect properties. We find that BaZrS$_3$ has a phonon-limited electron mobility of 37 cm$^2$/Vs comparable to that in halide perovskites but lower hole mobility of 11 cm$^2$/Vs. The defect computations indicate that BaZrS$_3$ is intrinsically n-type due to shallow sulfur vacancies, but that strong compensation by sulfur vacancies will prevent attempts to make it p-type. We also establish that BaZrS$_3$ shows some degree of defect tolerance, presenting only few low formation energy, deep intrinsic defects. Among the deep defects, sulfur interstitials are the dominant nonradiative recombination centers but exhibit a moderate capture coefficient. Our work highlights the material's intrinsic limitations in carrier mobility and p-type doping and suggests focusing on suppressing the formation of sulfur interstitials to reach longer carrier lifetime.

Published
2024

3. FeMnNiAlCr High Entropy Alloys with High-Efficiency Surface Oxide Solar Absorbers for Concentrating Solar Power Systems

Author

Gao, Xiaoxue, Jiang, Edwin, Pike, Andrew, Lee, Eldred, Wu, Margaret, Wang, Huan, Somers, Sheppard, Li, Weiyang, Hautier, Geoffroy, Baker, Ian, and Liu, Jifeng

Subjects
Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

High entropy alloys (HEAs) have attracted substantial interest in recent years. Thus far, most investigations have focused on their applications as structural materials rather than functional materials. In this paper, we show that FeMnNiAlCr HEAs can potentially be applied as both a structural and functional material for high-efficiency concentrated solar thermal power (CSP) systems working at >700 degrees C. The HEA itself would be used in high-temperature tubing to carry working fluids, while its surface oxide would act as a high-efficiency solar thermal absorber. These HEAs have demonstrated yield strengths 2-3x greater than that of stainless steel at 700 degrees C and a creep lifetime >800 h at 700 degrees C under a typical CSP tubing mechanical load of 35 MPa. Their Mn-rich surface oxides maintain a high optical-to-thermal conversion efficiency of ~87% under 1000x solar concentration for 20 simulated day-night thermal cycles between 750 degrees C and environmental temperature. These HEAs have also sustained immersion in unpurified bromide molten salts for 14 days at 750{\deg}C with <2% weight loss, in contrast to 70% weight loss from a 316 stainless steel reference. The simultaneous achievement of promising mechanical, optical, and thermochemical properties in this FeMnNiAlCr system opens the door to new applications of HEAs in solar energy harvesting.

Published
2023

4. Discovery of the Zintl-phosphide BaCd$_{2}$P$_{2}$ as a long carrier lifetime and stable solar absorber

Author

Yuan, Zhenkun, Dahliah, Diana, Hasan, Muhammad Rubaiat, Kassa, Gideon, Pike, Andrew, Quadir, Shaham, Claes, Romain, Chandler, Cierra, Xiong, Yihuang, Kyveryga, Victoria, Yox, Philip, Rignanese, Gian-Marco, Dabo, Ismaila, Zakutayev, Andriy, Fenning, David P., Reid, Obadiah G., Bauers, Sage, Liu, Jifeng, Kovnir, Kirill, and Hautier, Geoffroy

Subjects
Condensed Matter - Materials Science
Abstract

Thin-film photovoltaics offers a path to significantly decarbonize our energy production. Unfortunately, current materials commercialized or under development as thin-film solar cell absorbers are far from optimal as they show either low power conversion efficiency or issues with earth-abundance and stability. Entirely new and disruptive materials platforms are rarely discovered as the search for new solar absorbers is traditionally slow and serendipitous. Here, we use first principles high-throughput screening to accelerate this process. We identify new solar absorbers among known inorganic compounds using considerations on band gap, carrier transport, optical absorption but also on intrinsic defects which can strongly limit the carrier lifetime and ultimately the solar cell efficiency. Screening about 40,000 materials, we discover the Zintl-phosphide BaCd$_{2}$P$_{2}$ as a potential high-efficiency solar absorber. Follow-up experimental work confirms the predicted promises of BaCd$_{2}$P$_{2}$ highlighting an optimal band gap for visible absorption, bright photoluminescence, and long carrier lifetime of up to 30 ns even for unoptimized powder samples. Importantly, BaCd$_{2}$P$_{2}$ does not contain any critical elements and is highly stable in air and water. Our work opens an avenue for a new family of stable, earth-abundant, high-performance Zintl-based solar absorbers. It also demonstrates how recent advances in first principles computation can accelerate the search of photovoltaic materials by combining high-throughput screening with experiment.

Published
2023
Full Text
View/download PDF

7. Unlocking the thermoelectric potential of the Ca14AlSb11 structure type

Author

Justl, Andrew P, Ricci, Francesco, Pike, Andrew, Cerretti, Giacomo, Bux, Sabah K, Hautier, Geoffroy, and Kauzlarich, Susan M

Subjects
Macromolecular and Materials Chemistry, Chemical Sciences
Abstract

Yb14MnSb11 and Yb14MgSb11 are among the best p-type high-temperature (>1200 K) thermoelectric materials, yet other compounds of this Ca14AlSb11 structure type have not matched their stability and efficiency. First-principles computations show that the features in the electronic structures that have been identified to lead to high thermoelectric performances are present in Yb14ZnSb11, which has been presumed to be a poor thermoelectric material. We show that the previously reported low power factor of Yb14ZnSb11 is not intrinsic and is due to the presence of a Yb9Zn4+xSb9 impurity uniquely present in the Zn system. Phase-pure Yb14ZnSb11 synthesized through a route avoiding the impurity formation reveals its exceptional high-temperature thermoelectric properties, reaching a peak zT of 1.2 at 1175 K. Beyond Yb14ZnSb11, the favorable band structure features for thermoelectric performance are universal among the Ca14AlSb11 structure type, opening the possibility for high-performance thermoelectric materials.

Published
2022

12. Microarray analyses reveal strain-specific antibody responses to Plasmodium falciparum apical membrane antigen 1 variants following natural infection and vaccination

Author

Bailey, Jason A, Berry, Andrea A, Travassos, Mark A, Ouattara, Amed, Boudova, Sarah, Dotsey, Emmanuel Y, Pike, Andrew, Jacob, Christopher G, Adams, Matthew, Tan, John C, Bannen, Ryan M, Patel, Jigar J, Pablo, Jozelyn, Nakajima, Rie, Jasinskas, Algis, Dutta, Sheetij, Takala-Harrison, Shannon, Lyke, Kirsten E, Laurens, Matthew B, Niangaly, Amadou, Coulibaly, Drissa, Kouriba, Bourema, Doumbo, Ogobara K, Thera, Mahamadou A, Felgner, Philip L, and Plowe, Christopher V

Subjects
Medical Microbiology, Biomedical and Clinical Sciences, Clinical Sciences, Prevention, Biotechnology, Malaria, Vector-Borne Diseases, Immunization, Infectious Diseases, Rare Diseases, HIV/AIDS, Vaccine Related, Prevention of disease and conditions, and promotion of well-being, 3.4 Vaccines, Infection, Good Health and Well Being, Antibodies, Protozoan, Antibody Formation, Antigens, Protozoan, Malaria Vaccines, Malaria, Falciparum, Membrane Proteins, Plasmodium falciparum, Protozoan Proteins
Abstract

Vaccines based on Plasmodium falciparum apical membrane antigen 1 (AMA1) have failed due to extensive polymorphism in AMA1. To assess the strain-specificity of antibody responses to malaria infection and AMA1 vaccination, we designed protein and peptide microarrays representing hundreds of unique AMA1 variants. Following clinical malaria episodes, children had short-lived, sequence-independent increases in average whole-protein seroreactivity, as well as strain-specific responses to peptides representing diverse epitopes. Vaccination resulted in dramatically increased seroreactivity to all 263 AMA1 whole-protein variants. High-density peptide analysis revealed that vaccinated children had increases in seroreactivity to four distinct epitopes that exceeded responses to natural infection. A single amino acid change was critical to seroreactivity to peptides in a region of AMA1 associated with strain-specific vaccine efficacy. Antibody measurements using whole antigens may be biased towards conserved, immunodominant epitopes. Peptide microarrays may help to identify immunogenic epitopes, define correlates of vaccine protection, and measure strain-specific vaccine-induced antibodies.

Published
2020

14. Antibodies to Peptides in Semiconserved Domains of RIFINs and STEVORs Correlate with Malaria Exposure

Author

Zhou, Albert E, Berry, Andrea A, Bailey, Jason A, Pike, Andrew, Dara, Antoine, Agrawal, Sonia, Stucke, Emily M, Ouattara, Amed, Coulibaly, Drissa, Lyke, Kirsten E, Laurens, Matthew B, Adams, Matthew, Takala-Harrison, Shannon, Pablo, Jozelyn, Jasinskas, Algis, Nakajima, Rie, Niangaly, Amadou, Kouriba, Bourema, Kone, Abdoulaye K, Rowe, J Alexandra, Doumbo, Ogobara K, Thera, Mahamadou A, Patel, Jigar J, Tan, John C, Felgner, Philip L, Plowe, Christopher V, and Travassos, Mark A

Subjects
Infectious Diseases, Pediatric, Clinical Research, Rare Diseases, Malaria, Vector-Borne Diseases, 2.1 Biological and endogenous factors, Aetiology, Infection, Good Health and Well Being, Adolescent, Adult, Age Factors, Antibodies, Protozoan, Antigens, Protozoan, Child, Child, Preschool, Clinical Trials, Phase I as Topic, Clinical Trials, Phase II as Topic, Endemic Diseases, Female, Humans, Immunity, Innate, Infant, Interspersed Repetitive Sequences, Male, Mali, Middle Aged, Peptides, Plasmodium falciparum, Protein Array Analysis, Young Adult, RIFIN, STEVOR, malaria, microarrays, peptide, semiconserved domain, severe malaria, variant surface antigen, Plasmodium falciparum, Immunology, Microbiology
Abstract

The repetitive interspersed family (RIFIN) and the subtelomeric variable open reading frame (STEVOR) family represent two of three major Plasmodium falciparum variant surface antigen families involved in malaria pathogenesis and immune evasion and are potential targets in the development of natural immunity. Protein and peptide microarrays populated with RIFINs and STEVORs associated with severe malaria vulnerability in Malian children were probed with adult and pediatric sera to identify epitopes that reflect malaria exposure. Adult sera recognized and reacted with greater intensity to all STEVOR proteins than pediatric sera did. Serorecognition of and seroreactivity to peptides within the semiconserved domain of STEVORs increased with age and seasonal malaria exposure, while serorecognition and seroreactivity increased for the semiconserved and second hypervariable domains of RIFINs only with age. Serologic responses to RIFIN and STEVOR peptides within the semiconserved domains may play a role in natural immunity to severe malaria.IMPORTANCE Malaria, an infectious disease caused by the parasite Plasmodium falciparum, causes nearly 435,000 deaths annually worldwide. RIFINs and STEVORs are two variant surface antigen families that are involved in malaria pathogenesis and immune evasion. Recent work has shown that a lack of humoral immunity to these proteins is associated with severe malaria vulnerability in Malian children. This is the first study to have compared serologic responses of children and adults to RIFINs and STEVORs in settings of malaria endemicity and to examine such serologic responses before and after a clinical malaria episode. Using microarrays, we determined that the semiconserved domains in these two parasite variant surface antigen families harbor peptides whose seroreactivity reflects malaria exposure. A similar approach has the potential to illuminate the role of variant surface antigens in the development of natural immunity to clinical malaria. Potential vaccines for severe malaria should include consideration of peptides within the semiconserved domains of RIFINs and STEVORs.

Published
2019

16. Children with cerebral malaria or severe malarial anaemia lack immunity to distinct variant surface antigen subsets

Author

Travassos, Mark A, Niangaly, Amadou, Bailey, Jason A, Ouattara, Amed, Coulibaly, Drissa, Lyke, Kirsten E, Laurens, Matthew B, Pablo, Jozelyn, Jasinskas, Algis, Nakajima, Rie, Berry, Andrea A, Adams, Matthew, Jacob, Christopher G, Pike, Andrew, Takala-Harrison, Shannon, Liang, Li, Kouriba, Bourema, Kone, Abdoulaye K, Rowe, J Alexandra, Moulds, JoAnn, Diallo, Dapa A, Doumbo, Ogobara K, Thera, Mahamadou A, Felgner, Philip L, and Plowe, Christopher V

Subjects
Malaria, Pediatric, Brain Disorders, Rare Diseases, Infectious Diseases, Vector-Borne Diseases, Clinical Research, Aetiology, 2.1 Biological and endogenous factors, Infection, Good Health and Well Being, Anemia, Antigens, Protozoan, Case-Control Studies, Child, Preschool, Female, Humans, Infant, Malaria, Cerebral, Malaria, Falciparum, Male, Plasmodium falciparum
Abstract

Variant surface antigens (VSAs) play a critical role in severe malaria pathogenesis. Defining gaps, or "lacunae", in immunity to these Plasmodium falciparum antigens in children with severe malaria would improve our understanding of vulnerability to severe malaria and how protective immunity develops. Using a protein microarray with 179 antigen variants from three VSA families as well as more than 300 variants of three other blood stage P. falciparum antigens, reactivity was measured in sera from Malian children with cerebral malaria or severe malarial anaemia and age-matched controls. Sera from children with severe malaria recognized fewer extracellular PfEMP1 fragments and were less reactive to specific fragments compared to controls. Following recovery from severe malaria, convalescent sera had increased reactivity to certain non-CD36 binding PfEMP1s, but not other malaria antigens. Sera from children with severe malarial anaemia reacted to fewer VSAs than did sera from children with cerebral malaria, and both of these groups had lacunae in their seroreactivity profiles in common with children who had both cerebral malaria and severe malarial anaemia. This microarray-based approach may identify a subset of VSAs that could inform the development of a vaccine to prevent severe disease or a diagnostic test to predict at-risk children.

Published
2018

22. Natural immunity to malaria preferentially targets the endothelial protein C receptor-binding regions of PfEMP1s

Author

Tewey, Madison A., primary, Coulibaly, Drissa, additional, Lawton, Jonathan G., additional, Stucke, Emily M., additional, Zhou, Albert E., additional, Berry, Andrea A., additional, Bailey, Jason A., additional, Pike, Andrew, additional, Dara, Antoine, additional, Ouattara, Amed, additional, Lyke, Kirsten E., additional, Ifeonu, Olukemi, additional, Laurens, Matthew B., additional, Adams, Matthew, additional, Takala-Harrison, Shannon, additional, Niangaly, Amadou, additional, Kouriba, Bourema, additional, Koné, Abdoulaye K., additional, Rowe, J. Alexandra, additional, Doumbo, Ogobara K., additional, Patel, Jigar J., additional, Tan, John C., additional, Felgner, Philip L., additional, Plowe, Christopher V., additional, Thera, Mahamadou A., additional, and Travassos, Mark A., additional

Published
2023
Full Text
View/download PDF

23. Discovery of the Zintl-phosphide BaCd2P2as a long carrier lifetime and stable solar absorber

Author

Yuan, Zhenkun, Dahliah, Diana, Hasan, Muhammad Rubaiat, Kassa, Gideon, Pike, Andrew, Quadir, Shaham, Claes, Romain, Chandler, Cierra, Xiong, Yihuang, Kyveryga, Victoria, Yox, Philip, Rignanese, Gian-Marco, Dabo, Ismaila, Zakutayev, Andriy, Fenning, David P., Reid, Obadiah G., Bauers, Sage, Liu, Jifeng, Kovnir, Kirill, and Hautier, Geoffroy

Abstract

Thin-film photovoltaics (PV) offers a path to decarbonize global energy production. Unfortunately, existing thin-film solar absorbers have major issues associated with either elemental abundance, stability, or performance. Entirely new and disruptive materials platforms are rarely discovered, and their search is traditionally slow and serendipitous. Here, we report a first-principles high-throughput (HT) computational screening for new solar absorbers among 40,000 known inorganic materials. Next to band gap and carrier effective masses, we also use computed intrinsic defects as they can limit the carrier lifetime. We identify the Zintl-phosphide BaCd2P2as a potential high-efficiency solar absorber. Follow-up experiments confirm the promises of BaCd2P2, highlighting an optimal band gap, bright photoluminescence (PL), and long carrier lifetime, even in unoptimized powder samples. Importantly, BaCd2P2contains no critical elements and is stable in air and water. Our work demonstrates how computational screening combined with experiments can accelerate the search for photovoltaic materials.

Published
2024
Full Text
View/download PDF

26. Data from Potent, Selective Inhibitors of Fibroblast Growth Factor Receptor Define Fibroblast Growth Factor Dependence in Preclinical Cancer Models

Author

Squires, Matthew, primary, Ward, George, primary, Saxty, Gordan, primary, Berdini, Valerio, primary, Cleasby, Anne, primary, King, Peter, primary, Angibaud, Patrick, primary, Perera, Tim, primary, Fazal, Lynsey, primary, Ross, Douglas, primary, Jones, Charlotte Griffiths, primary, Madin, Andrew, primary, Benning, Rajdeep K., primary, Vickerstaffe, Emma, primary, O'Brien, Alistair, primary, Frederickson, Martyn, primary, Reader, Michael, primary, Hamlett, Christopher, primary, Batey, Michael A., primary, Rich, Sharna, primary, Carr, Maria, primary, Miller, Darcey, primary, Feltell, Ruth, primary, Thiru, Abarna, primary, Bethell, Susanne, primary, Devine, Lindsay A., primary, Graham, Brent L., primary, Pike, Andrew, primary, Cosme, Jose, primary, Lewis, Edward J., primary, Freyne, Eddy, primary, Lyons, John, primary, Irving, Julie, primary, Murray, Christopher, primary, Newell, David R., primary, and Thompson, Neil T., primary

Published
2023
Full Text
View/download PDF

27. Supplementary Methods, Figures 1-4, Tables 1-2 from Potent, Selective Inhibitors of Fibroblast Growth Factor Receptor Define Fibroblast Growth Factor Dependence in Preclinical Cancer Models

Author

Squires, Matthew, primary, Ward, George, primary, Saxty, Gordan, primary, Berdini, Valerio, primary, Cleasby, Anne, primary, King, Peter, primary, Angibaud, Patrick, primary, Perera, Tim, primary, Fazal, Lynsey, primary, Ross, Douglas, primary, Jones, Charlotte Griffiths, primary, Madin, Andrew, primary, Benning, Rajdeep K., primary, Vickerstaffe, Emma, primary, O'Brien, Alistair, primary, Frederickson, Martyn, primary, Reader, Michael, primary, Hamlett, Christopher, primary, Batey, Michael A., primary, Rich, Sharna, primary, Carr, Maria, primary, Miller, Darcey, primary, Feltell, Ruth, primary, Thiru, Abarna, primary, Bethell, Susanne, primary, Devine, Lindsay A., primary, Graham, Brent L., primary, Pike, Andrew, primary, Cosme, Jose, primary, Lewis, Edward J., primary, Freyne, Eddy, primary, Lyons, John, primary, Irving, Julie, primary, Murray, Christopher, primary, Newell, David R., primary, and Thompson, Neil T., primary

Published
2023
Full Text
View/download PDF

35. Study of the cytochrome C3 from Shewanella NCIMB400 and the flavocytochrome B2 from Saccharomyces cerevisiae

Author

Pike, Andrew

Subjects
571.4
Abstract

A cytochrome c3 has been purified from Shewanella sp. NCIMB400 and the gene encoding it, cycA has been cloned and sequenced along with some flanking sequence. The mature protein is 86 amino acids in length and contains four covalently bound haem groups, with a molecular weight of 11780 Da. The electronic absorption spectrum is characteristic of a low-spin c-type cytochrome with an α-peak at 551nm. A redox titration of the four haems, yielded of values at -60 mV and -200 mV, within the range observed for cytochromes c3. Resonance Raman spectra of the protein contain bands characteristic of low-spin haems, consistent with bis-histidine ligation for all haems. The deduced amino acid sequence from the cycA gene is 86 residues long for mature cytochrome c3 and has an additional 25 amino acid, periplasm directing presequence. The predicted sequence contains four, CXXCH haem binding motifs. This is consistent with the presence of four c-type haems in the mature protein. A total of eight histidines in the amino acid sequence is consistent with four bis-histidine ligated haems. Two additional reading frames, in the same orientation, lie on either side of the cycA gene. The reading frames show sequence similarly with two cytoplasmic proteins and are clearly unrelated to cytochrome c3. Flavocytochrome b2 (L-lactate : cytochrome c oxidoreductase (E. C. 1.1.2.3.)) is a homotetrameric enzyme from the mitochondria of Saccharomyces cerevisiae. Each monomer consists of an N-terminal cytochrome domain and a C-terminal flavin domain, joined by a short flexible peptide. The haem domain has been identified as being mobile from the crystal structure of the Saccharomyces cerevisiae enzyme and a nuclear magnetic resonance study of Hansenula anomala flavocytochrome b2. The rate of flavin to haem electron transfer observed in the wild-type enzyme is ˜ 1500 s-1. This rate has is lower than expected considering the distance between the cofactors is ˜10Å.

Published
1998

36. Design of chemoresistive silicon sensors for application in gas monitoring

Author

Pike, Andrew Charles

Subjects
532, TP Chemical technology
Abstract

The growing concerns over our exposure to hazardous substances have been addressed by stringent legislation to ensure air quality. A wide variety of applications have therefore arisen which require the reliable detection of hazardous gases. Hence, the motivation behind the research presented in this thesis was the aim of developing a portable gas monitor to detect nitrogen dioxide, carbon monoxide and volatile organic compounds (e.g. benzene, toluene). The need to improve gas sensor technology for suitability to this demanding application has been identified. Thus, the objectives were to develop a number of ultra-low power devices consisting of an array of chemoresistive gas sensors for incorporation into an intelligent sensor system. The operation of these sensors relies on the measurement of a change in resistance of a gas-sensitive material when exposed to specific gases. Silicon technology has been employed in order to obtain reproducible, miniaturised sensors with a low unit cost. Furthermore, chemoresistors employing metal oxide semiconductor (MOS), metal-substituted phthalocyanine (XPc) and conducting polymer (CP) materials have been used because of their sensitivity to the gases of interest. Common problems associated with these materials are poor specificity to a target gas and poor stability. However, the approach to minimising these problems was to design arrays of cross-sensitive chemoresistors for use in a microprocessor-based intelligent sensor system. The microprocessor applies a pattern recognition algorithm to the sensor outputs to extract the required information. This thesis describes the design, fabrication and characterisation of these sensor arrays. MOS and XPc materials have shown an optimum performance at elevated temperatures. Micromachining techniques have therefore been employed to integrate resistance heaters in a micro-hotplate structure, which can allow temperatures of 600°C to be attained in —15 ms with a typical power consumption of —150 mW/sensor. A pulsed mode of operation should provide average power consumptions of less than 1 mW. A low power consumption is critical for a portable batterypowered instrument. The design, modelling and characterisation of the micro-hotplate structures have also been described. The design and development of a novel automated gas sensor test system was also fundamental to this research, in order to accurately characterise sensor responses and to validate theoretical models. The research objectives have been fulfilled in that a number of sensor array devices have been produced, which are suitable for a portable intelligent instrument. The different designs and materials are compatible for integration into a hybrid sensor. The advancements achieved in sensor technology provide a foundation for future research into the production of a portable intelligent sensor system.

Published
1996

37. Genome of Rhodnius prolixus, an insect vector of Chagas disease, reveals unique adaptations to hematophagy and parasite infection

Author

Mesquita, Rafael D., Vionette-Amaral, Raquel J., Lowenberger, Carl, Rivera-Pomar, Rolando, Monteiro, Fernando A., Minx, Patrick, Spieth, John, Carvalho, A. Bernardo, Panzera, Francisco, Lawson, Daniel, Torres, André Q., Ribeiro, Jose M. C., Sorgine, Marcos H. F., Waterhouse, Robert M., Montague, Michael J., Abad-Franch, Fernando, Alves-Bezerra, Michele, Amaral, Laurence R., Araujo, Helena M., Araujo, Ricardo N., Aravind, L., Atella, Georgia C., Azambuja, Patricia, Berni, Mateus, Bittencourt-Cunha, Paula R., Braz, Gloria R. C., Calderón-Fernández, Gustavo, Carareto, Claudia M. A., Christensen, Mikkel B., Costa, Igor R., Costa, Samara G., Dansa, Marilvia, Daumas-Filho, Carlos R. O., De-Paula, Iron F., Dias, Felipe A., Dimopoulos, George, Emrich, Scott J., Esponda-Behrens, Natalia, Fampa, Patricia, Fernandez-Medina, Rita D., da Fonseca, Rodrigo N., Fontenele, Marcio, Fronick, Catrina, Fulton, Lucinda A., Gandara, Ana Caroline, Garcia, Eloi S., Genta, Fernando A., Giraldo-Calderón, Gloria I., Gomes, Bruno, Gondim, Katia C., Granzotto, Adriana, Guarneri, Alessandra A., Guigó, Roderic, Harry, Myriam, Hughes, Daniel S. T., Jablonka, Willy, Jacquin-Joly, Emmanuelle, Juárez, M. Patricia, Koerich, Leonardo B., Lange, Angela B., Latorre-Estivalis, José Manuel, Lavore, Andrés, Lawrence, Gena G., Lazoski, Cristiano, Lazzari, Claudio R., Lopes, Raphael R., Lorenzo, Marcelo G., Lugon, Magda D., Majerowicz, David, Marcet, Paula L., Mariotti, Marco, Masuda, Hatisaburo, Megy, Karine, Melo, Ana C. A., Missirlis, Fanis, Mota, Theo, Noriega, Fernando G., Nouzova, Marcela, Nunes, Rodrigo D., Oliveira, Raquel L. L., Oliveira-Silveira, Gilbert, Ons, Sheila, Orchard, Ian, Pagola, Lucia, Paiva-Silva, Gabriela O., Pascual, Agustina, Pavan, Marcio G., Pedrini, Nicolás, Peixoto, Alexandre A., Pereira, Marcos H., Pike, Andrew, Polycarpo, Carla, Prosdocimi, Francisco, Ribeiro-Rodrigues, Rodrigo, Robertson, Hugh M., Salerno, Ana Paula, Salmon, Didier, Santesmasses, Didac, Schama, Renata, Seabra-Junior, Eloy S., Silva-Cardoso, Livia, Silva-Neto, Mario A. C., Souza-Gomes, Matheus, Sterkel, Marcos, Taracena, Mabel L., Tojo, Marta, Tu, Zhijian Jake, Tubio, Jose M. C., Ursic-Bedoya, Raul, Venancio, Thiago M., Walter-Nuno, Ana Beatriz, Wilson, Derek, Warren, Wesley C., Wilson, Richard K., Huebner, Erwin, Dotson, Ellen M., and Oliveira, Pedro L.

Published
2015

41. Temperature-Dependent Coherent Tunneling across Graphene–Ferritin Biomolecular Junctions

Author

Gupta, Nipun Kumar, primary, Karuppannan, Senthil Kumar, additional, Pasula, Rupali Reddy, additional, Vilan, Ayelet, additional, Martin, Jens, additional, Xu, Wentao, additional, May, Esther Maria, additional, Pike, Andrew R., additional, Astier, Hippolyte P. A. G., additional, Salim, Teddy, additional, Lim, Sierin, additional, and Nijhuis, Christian A., additional

Published
2022
Full Text
View/download PDF

45. Impedimetric Polyaniline-Based Aptasensor for Aflatoxin B 1 Determination in Agricultural Products.

Author

Ong, Jing Yi, Phang, Sook-Wai, Goh, Choo Ta, Pike, Andrew, and Tan, Ling Ling

Subjects
FARM produce, AFLATOXINS, MOLECULAR size, PISTACHIO, IMPEDANCE spectroscopy, CARBON-carbon bonds
Abstract

An impedimetric aptasensor based on a polyaniline (PAni) support matrix is developed through the surface modification of a screen-printed carbon electrode (SPE) for aflatoxin B1 (AFB1) detection in foodstuffs and feedstuffs for food safety. The PAni is synthesized with the chemical oxidation method and characterized with potentiostat/galvanostat, FTIR, and UV–vis spectroscopy techniques. The stepwise fabrication procedure of the PAni-based aptasensor is characterized by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The impedimetric aptasensor is optimized using the EIS technique, and its feasibility of detecting AFB1 in real sample matrices is evaluated via a recovery study in spiked foodstuffs and feedstuffs, such as pistachio nuts, cinnamons, cloves, corn, and soybeans, with a good recovery percentage, ranging from 87.9% to 94.7%. The charge transfer resistance (RCT) at the aptasensor interface increases linearly with the AFB1 concentration in the range of 3 × 10−2 nM to 8 × 10−2 nM, with a regression coefficient (R2) value of 0.9991 and detection limit of 0.01 nM. The proposed aptasensor is highly selective towards AFB1 and partially selective to AFB2 and ochratoxin A (OTA) due to their similar structures that differ only at the carbon–carbon double bond located at C8 and C9 and the large molecule size of OTA. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

48. Role of Order in the Mechanism of Charge Transport across Single-Stranded and Double-Stranded DNA Monolayers in Tunnel Junctions

Author

Gupta, Nipun Kumar, primary, Wilkinson, Edward A., additional, Karuppannan, Senthil Kumar, additional, Bailey, Lily, additional, Vilan, Ayelet, additional, Zhang, Ziyu, additional, Qi, Dong-Chen, additional, Tadich, Anton, additional, Tuite, Eimer M., additional, Pike, Andrew R., additional, Tucker, James H. R., additional, and Nijhuis, Christian A., additional

Published
2021
Full Text
View/download PDF

49. Diverse, Potent, and Efficacious Inhibitors That Target the EED Subunit of the Polycomb Repressive Complex 2 Methyltransferase

Author

Bagal, Sharan K., primary, Gregson, Clare, additional, O’ Donovan, Daniel H., additional, Pike, Kurt G., additional, Bloecher, Andrew, additional, Barton, Peter, additional, Borodovsky, Alexandra, additional, Code, Erin, additional, Fillery, Shaun M., additional, Hsu, Jessie Hao-Ru, additional, Kawatkar, Sameer P., additional, Li, Chengzhi, additional, Longmire, David, additional, Nai, Youfeng, additional, Nash, Samuel C., additional, Pike, Andrew, additional, Robinson, James, additional, Read, Jon A., additional, Rawlins, Phillip B., additional, Shen, Minhui, additional, Tang, Jia, additional, Wang, Peng, additional, Woods, Haley, additional, and Williamson, Beth, additional

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results