847 research outputs found
Advancing microplastic detection: a review of portable Raman spectroscopy for environmental monitoring
No full textAriel - Volume 8 Number 4
No full textExecutive Editor
James W. Lockard Jr.
Issues Editor
Neeraj K. Kanwal
Business Manager
Neeraj K. Kanwal
University News
Martin Trichtinger
World News
Doug Hiller
Opinions
Elizabeth A. McGuire
Features
Patrick P. Sokas
Sports Desk
Shahab S. Minassian
Managing Editor
Edward H. Jasper
Managing Associate
Brenda Peterson
Photography Editor
Robert D. Lehman, Jr.
Graphics
Christine M. Kuhnl
Ariel - Volume 8 Number 5
No full textExecutive Editor
James W. Lockard. Jr.
Business Manager
Neeraj K. Kanwal
University News
Martin Trichtinger
World News
Doug Hiller
Opinions
Elizabeth A. McGuire
Features
Patrick P. Sokas
Sports Desk
Shahab S. Minassian
Managing Editor
Edward H. Jasper
Managing Associate
Brenda Peterson
Photography Editor
Robert D. Lehman, Jr.
Graphics
Christine M. Kuhnl
Label-free electrochemical aptasensor for the detection of SARS-CoV-2 spike protein based on carbon cloth sputtered gold nanoparticles
No full textThe proliferation and transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), or the (COVID-19) disease, has become a threat to worldwide biosecurity. Therefore, early diagnosis of COVID-19 is crucial to combat the ongoing infection spread. In this study we propose a flexible aptamer-based electrochemical sensor for the rapid, label-free detection of SARS-CoV-2 spike protein (SP). A platform made of a porous and flexible carbon cloth, coated with gold nanoparticles, to increase the conductivity and electrochemical performance of the material, was assembled with a thiol functionalized DNA aptamer via S–Au bonds, for the selective recognition of the SARS-CoV-2 SP. The various steps for the sensor preparation were followed by using scanning electron microscopy, cyclic voltammetry and differential pulse voltammetry (DPV). The proposed platform displayed good mechanical stability, revealing negligible changes on voltammetric responses to bending at various angles. Quantification of SARS-CoV-2 SP was performed by DPV and chronopotentiometry (CP), exploiting the changes of the electrical signals due the [Fe(CN)6]3-/4- redox probe, when SARS-CoV-2 SP binds to the aptamer immobilized on the electrode surface. Current density, in DPV, and square root of the transition time, in CP, varied linearly with the log[ SARS-CoV-2 SP], providing lower limits of detection (LOD) of 0.11 ng/mL and 37.8 ng/mL, respectively. The sensor displayed good selectivity, repeatability, and was tested in diluted human saliva, spiked with different SARS-CoV-2 SP concentrations, providing LODs of 0.167 ng/mL and 46.2 ng/mL for DPV and CP, respectively
Effect of sequential or ternary starters-assisted fermentation on the phenolic and glucosinolate profiles of sauerkraut in comparison with spontaneous fermentation
No full textThis study investigated the effectiveness of two novel started-assisted sauerkraut fermentations in comparison with spontaneous fermentation. Three lactic acid bacteria strains were selected as best starters for sauerkraut processing, based on the complementarity of pro-technological (kinetics of growth and acidification) traits, phenotypic fingerprints through OmniLog Phenotype MicroArray, and phenolics metabolism. The selected strains were applied according to two different fermentation methods based on steering sequential and temporally deferred inoculum of three strains, and ternary simultaneous inoculum. Sequential and ternary starters-assisted fermentations lasted 9 and 7 days, respectively, and were compared to conventional spontaneous fermentation lasting 35 days. Sequential and ternary fermentations resulted in a higher and constant number of lactic acid bacteria compared to spontaneous fermentation, which reflected on the acidification and sugar utilization. Ternary fermentation enhanced phenolic compounds conversion (hydrocaffeic acid, hydroferulic acid, 4-ethyl catechol), ensuring at the same time higher level of aliphatic (glucobrassicanapin) and indole glucosinolates (glucobrassicin) and derivatives (ascorbigen). Short fermentation of sequential and ternary starters-assisted processing caused only slight changes in the sensory profile compared to the spontaneous process, preserved the structural integrity of sauerkraut, and did not affect the colour lightness
All organic memory devices utilizing C60 molecules and insulating polymers
No full textThe convergence of mobile technologies combined with stricter power requirements and increasing demands have strained the current memory technology. Newer technologies such as phase changing, ferroelectric, and magnetic random access memories are unsatisfactory in meeting the new requirements. We propose a new memory technology based on our initial discovery of charge storage in C60 molecules within poly (4-vinyl phenol) (PVP). To understand the memory potential, we created single-layer devices consisting of ~30nm films of PVP+C60 sandwiched between aluminum (Al) electrodes. Current versus voltage (I-V) sweeps showed a significant hysteresis of 75nA, with distinguishable memory states. Room temperature charging of C60 was confirmed indirectly through capacitance versus voltage measurements and directly by monitoring the A1g characteristic peak of C60 during Raman measurements. We demonstrated memory operations by applying read-write-erase (RWE) pulses. The PVP+C60 devices exhibited memory retention for over 1 hour and response times of around 10ns. Characteristic hysteresis was demonstrated at the nanoscale. Conduction models were fitted at room temperature to the I-V curves. It was found that combination of direct and Fowler-Nordheim tunneling were the principle conduction mechanisms.
For a more technologically viable memory device, we developed a multi-layer device structure, consisting of a polystyrene (PS) capping layer. The resulting asymmetrical I-V curve exhibited a hysteresis ratio of 103. RWE cycles were measured with clearly distinguishable states. The memory retentions were measured over 2 hours and the response time around 10ns. The stability of the multi-layer devices was improved. I-V measurements at temperatures varying from 4.2 K to 298 K were performed to construct a theoretical model. The I-V curves were found to be temperature independent and exhibited similar tunneling behaviors as the single-layer devices. A simple model for conduction and memory operation is proposed based on the I-V fits.
These devices exhibit the characteristics needed to satisfy the new demands for memory application and have the potential of becoming the first universal memory technology. They possess the high speed, non-volatility, thermal stability, and potentially high memory densities to make them ideal for use in laptops, iPhones, mp3 players, portable video players, GPS systems, and other mobile devices.Ph.D.Includes bibliographical references
Role of Citrullus colocynthis and Psidium guajava Mediated Green Synthesized Silver Nanoparticles in Disease Resistance against Aeromonas hydrophila Challenge in Labeo rohita
No full textGreen synthesis of metallic nanoparticles is an auspicious method of preparing nanoparticles using plant extracts that have lesser toxicity to animal cells and the host. In the present work, we analyzed the antibacterial activity of Citrullus colocynthis and Psidium guajava-mediated silver nanoparticles (Cc-AgNPs and Pg-AgNPs, respectively) against Aeromonas hydrophila (A. hydrophila) in an in vivo assay employing Labeo rohita (L. rohita). L. rohita were divided into six groups for both Cc-AgNPs and Pg-AgNPs treatments separately: Control, A. hydrophila infected, A. hydrophila + Ampicillin, A. hydrophila + Cc/Pg-AgNPs (25 mu g/L), A. hydrophila + Cc/Pg-AgNPs (50 mu g/L), and A. hydrophila + Cc/Pg-AgNPs (75 mu g/L). Changes in different bio-indicators such as hematological, histological, oxidative stress, and cytokine analysis were observed. Interestingly, the infected fish treated with both types of AgNPs (Cc-AgNPs and Pg-AgNPs) exhibited a higher survival rate than the untreated infected fish and demonstrated signs of recovery from the infection, providing a compelling indication of the positive impact of phytosynthesized AgNPs. Disruptions in hematological and histological parameters were found in the infected fish. Both Cc-AgNPs and Pg-AgNPs showed recovery on the hematological and histological parameters. Analysis of oxidative stress and cytokine markers also revealed provoking evidence of the positive impact of Cc-AgNPs and Pg-AgNPs treatment against disease progression in the infected fish. The major finding of the study was that the higher concentrations of the nanoparticles (50 mu g/L in the case of Cc-AgNPs and 75 mu g/L in the case of Pg-AgNPs) were more effective in fighting against disease. In conclusion, our work presents novel insights for the use of green-synthesized AgNPs as economic and innocuous antibacterial candidates in aquaculture
Biophysical attributes of an in vitro spinal cord surrogate for use in developing an intradural neuromodulation system
No full textWe have developed a spinal cord surrogate for use in testing a pial-surface spinal cord stimulator. Our surrogate is of a commercially available silicone mix, has an oval cross-sectional area that matches that of actual human spinal cord at the lower thoracic level, and has measured values of durometer A?=?(10.96?±?1.68), durometer O?=?(14.76?±?1.48), and durometer OO?=?(50.24?±?2.65). These correspond to model-inferred elastic moduli of 0.41 to 0.44 MPa, which match well with the existing low-strain rate measurements of ex vivo human spinal cord. Upcoming applications for this surrogate in developmental studies of the new stimulator system are discussed
Word length and the principle of least effort: language as an evolving, efficient code for information transfer
No full textIn 1935 the linguist George Kingsley Zipf made a now classic observation about the
relationship between a word’s length and its frequency: the more frequent a word is,
the shorter it tends to be. He claimed that this “Law of Abbreviation” is a universal
structural property of language. The Law of Abbreviation has since been documented
in a wide range of human languages, and extended to animal communication systems
and even computer programming languages. Zipf hypothesised that this universal
design feature arises as a result of individuals optimising form-meaning mappings
under competing pressures to communicate accurately but also efficiently—his famous
Principle of Least Effort.
In this thesis, I present a novel set of studies which provide direct experimental evidence
for this explanatory hypothesis. Using a miniature artificial language learning
paradigm, I show in Chapter 2 that language users optimise form-meaning mappings
in line with the Law of Abbreviation only when pressures for accuracy and efficiency
both operate during a communicative task. These results are robust across different
methods of data collection: one version of the experiment was run in the lab, and
another was run online, using a novel method I developed which allows participants
to partake in dyadic interaction through a web-based interface.
In Chapter 3, I address the growing body of work suggesting that a word’s predictability
in context may be an even stronger determiner of its length than its frequency
alone. For instance, Piantadosi et al. (2011) show that shorter words have a
lower average surprisal (i.e., tend to appear in more predictive contexts) than longer
words, in synchronic corpora across many languages. We hypothesise that the same
communicative pressures posited by the Principle of Least Effort, when acting on
speakers in situations where context manipulates the information content of words,
can give rise to these lexical distributions. Adapting the methodology developed in
Chapter 2, I show that participants use shorter words in more predictive contexts only
when subject to the competing pressures for accurate and efficient communication. In
a second experiment, I show that participants are more likely to use shorter words for
meanings with a lower average surprisal. These results suggest that communicative
pressures acting on individuals during language use can lead to the re-mapping of a
lexicon to align with “Uniform Information Density”, the principle that information
content ought to be evenly spread across an utterance, such that shorter linguistic
units carry less information than longer ones.
Over generations, linguistic behaviour such as that observed in the experiments
reported here may bring entire lexicons into alignment with the Law of Abbreviation
and Uniform Information Density. For this to happen, a diachronic process which
leads to permanent lexical change is necessary. However, crucial evidence for this
process—decreasing word length as a result of increasing frequency over time—has
never before been systematically documented in natural language. In Chapter 4,
I conduct the first large-scale diachronic corpus study investigating the relationship
between word length and frequency over time, using the Google Books Ngrams corpus
and three different word lists covering both English and French. Focusing on words
which have both long and short variants (e.g., info/information), I show that the
frequency of a word lemma may influence the rate at which the shorter variant gains
in popularity. This suggests that the lexicon as a whole may indeed be gradually
evolving towards greater efficiency.
Taken together, the behavioural and corpus-based evidence presented in this thesis
supports the hypothesis that communicative pressures acting on language-users are at
least partially responsible for the frequency-length and surprisal-length relationships
found universally across lexicons. More generally, the approach taken in this thesis
promotes a view of language as, among other things, an evolving, efficient code for
information transfer
Ariel - Volume 8 Number 2
No full textExecutive Editor
James W. Lockard , Jr.
Issue Editor
Doug Hiller
Business Manager
Neeraj K. Kanwal
University News
Richard J. Perry
World News
Doug Hiller
Opinions
Elizabeth A. McGuire
Features
Patrick P. Sokas
Sports Desk
Shahab S. Minassian
Managing Editor
Edward H. Jasper
Managing Associate
Brenda Peterson
Photography Editor
Robert D. Lehman, Jr.
Graphics
Christine M. Kuhnl
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