Biomechanics and Functional Morphology of Amblypygid Predation

Amblypygids, colloquially known as whip spiders, are a charismatic order of arachnids that a characterised a unique pair of spined pedipalp appendages. Amblypygid pedipalps are hypothesised to primarily function as a prey capture device. However, the pedipalp is also used in several other functions including territorial contest and courtship, opening the possibility that the appendage could also be under the influence of sexual selection. There exists a vast degree of morphological diversity within the pedipalp, with relative length spanning nearly an order of magnitude across the group and spination varying markedly both within- and between species. The amblypygid pedipalp is therefore subject to multiple selective pressures, and both its external morphology and kinematics likely reflect this. Thus, the amblypygid pedipalp provides an ideal structure through which to study the evolution of morphological traits subject to multiple selective pressures, and the potential evolutionary trade-offs that may arise. Despite this, amblypygid pedipalp morphology and kinematics remains poorly quantified and little comparative work has been carried across the group. Here, I aim to quantify intra- and interspecific trends in amblypygid pedipalp shape and prey capture kinematics for the first time, using modern morphometric techniques and high-speed videography. In this work I present a comprehensive review of sexual dimorphism in arachnids and identify the common drivers behind this phenomenon. Building on this, I quantify sexual dimorphism in pedipalp size and shape in a single species of amblypygid using a novel geometric morphometric approach. This is followed by an broad analysis of intraspecific and interspecific trends in shape complexity of pedipalps using Elliptical Fourier Analysis. Finally, I draw a link between form and function by quantifying and comparing prey capture kinematics in a morphologically diverse set of amblypygids, using high-speed videography and motion analysis. This work provides new insights into amblypygid 8 pedipalp diversity and posits the possibility of an evolutionary trade-off between increased pedipalp length, for use in display in courtship and territorial contest, and strike performance during prey capture

Perceptions of cannabis use: What effect does the perceived use and approval among friends, perceived harm of use, and perceived risk of legal consequences have on the intentions to use cannabis?

Cannabis use among young adults is higher than any other age demographic, and research shows that cannabis use increases the risk for adverse mental health, and more so with younger initiation of use. Perceptions of use and approval among friends, and perceptions of harm from use have all been found to predict use. A gap in the research was identified with regards to the effect of the perceived risk of legal consequences on the intentions to use. The present study sought to examine the effect of the perceived risk of arrest and criminal sanctions on the intentions to use cannabis in future and compare this effect with perceived use and approval among friends and perceived harm of cannabis use. A total of 70 young adults aged between 18 and 24 years old completed a questionnaire measuring perceived use and approval among friends, perceived harm of cannabis use, perceived risk of legal consequences, and intentions to use cannabis in the next twelve months. Use and approval among friends, and perceived harm were found to be predictive of intentions to use, perceived risk of legal consequences was not. A multiple regression analysis demonstrated that perceived use and harm were significant predictors, but not approval

Impact of substituent effects on the Raman spectra of structurally related N-substituted diketopyrrolopyrroles

This document is the Accepted Manuscript version of the following article: Jesus Calvo-Castro, et al, ‘Impact of substituent effects on the Raman spectra of structurally related N-substituted diketopyrrolopyrroles’, Vibrational Spectroscopy, Vol. 83, pp. 8-16, March 2016, doi: https://doi.org/10.1016/j.vibspec.2015.12.004. This manuscript version is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.Control over vibrational frequency modes is important in optimising the performance and behaviour of conjugated organic materials employed as charge transfer mediators and optical components in optoelectronic devices. Raman spectroscopy represents a powerful technique that can be employed to determine the structural implications of molecular substitution on photophysical properties in such conjugated organic environments. Herein, we report for the first time, the optimised geometries for a series of eight systematically varied N-substituted diketopyrrolopyrroles as well as their experimental and computed Raman spectra, with special emphasis placed upon their spectral band assignments. Clear out-of-plane structural re-arrangements, including pyramidalisation of the lactam nitrogens arising from intramolecular H-bonding interactions were observed upon N-substitution in the reported systems, leading to significant vibrational frequency shifts for ν(Nsingle bondC) and ν(Cdouble bond; length as m-dashO) modes. In addition, mode scaling factors were determined and found to be comparable with those reported previously, employed using the same density functional. The following study addresses the implications of structural variation on the progression of those intense Raman modes which play a key role in tuning the photophysical properties of N-substituted diketopyrrolopyrrole systems and as such should be of broad interest to those developing functional materials based upon this molecular motifPeer reviewe

Assessing the patterns and drivers of shape complexity in the amblypygid pedipalp

Amblypygi is an arachnid order possessing a unique pair of spined pedipalps: appendages that perform in prey capture, courtship, and contest. Pedipalp length, hypothesized to be under sexual selection, varies markedly across amblypygid species, and pedipalp spination, thought to reflect selection for function in prey capture, also differs interspecifically. Differences in pedipalp shape between species may indicate that the relative strength of selection for prey capture and sexual selection vary across the group. However, interspecific differences in pedipalp shape have not been quantified, due to difficulties in identifying homologous features. For the first time, we quantify trends in amblypygid pedipalp shape complexity. We use elliptical Fourier analysis to quantify 2D complexity in pedipalp outlines across eleven species and six genera. We find that complexity significantly decreases as pedipalp length increases. This appears to be driven by relative spine length, suggesting that a trade-off exists between pedipalp length and spination. Furthermore, significant female-biased sexual dimorphism in shape complexity is present in the tibial segment of the amblypygid pedipalp. Our results provide novel insights into the drivers of amblypygid pedipalp evolution and suggest that a functional trade-off between performance in prey capture and other functions under sexual selection exist in this enigmatic structure

Design of main propulsion system for a reusable suborbital rocket

In recent years there has been an increased interest in the use of CubeSats to perform research in the realms of microgravity and earth observation. Previously, CubeSats have generally been placed into orbit as secondary payloads, piggy-backing on the launches of larger spacecraft. This has meant that CubeSat orbits and launch schedules have been decided by the requirements of other missions, restricting the manner in which they can be used. Due to the lack of flexibility in mission design afforded by traditional launch options, and the increasing competition for CubeSat launch spots, it has become desirable to develop a dedicated small satellite launch platform. This would allow for the execution of more novel and exciting missions, utilising orbits specifically designed with small satellites in mind. Tranquility Aerospace Ltd are currently engaged in the design of a two-stage vertical take-off and landing (VTVL) launcher, aimed at the small satellite market. Due to the many engineering challenges involved, they are aiming to first develop a suborbital launch vehicle in order to test the technologies necessary. This launch vehicle will be single-stage, and capable of vertical take-off and landing. As a student project at the University of Strathclyde, the main rocket propulsion system for this vehicle is being designed. This paper will outline the development of the propulsion system, including the propellant feed system, injector plate, thrust chamber and thermal control system. The key design driver is to lower the overall system mass, including the mass of the propellant. Comparisons of the impact of different subsystem configurations on performance will be assessed and discussed, and a focus will be placed on aspects of the design impacted by the requirement for reusability. The goal is to produce a fully workable design which is ready for manufacture and can be taken forward to the testing phase of development

Impact of systematic structural variation on the energetics of π−π stacking interactions and associated computed charge transfer integrals of crystalline diketopyrrolopyrroles

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Crystal Growth & Design, copyright © 2014 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see DOI: https://doi.org/10.1021/cg5010165, or ACS Articles on Request http://pubs.acs.org/page/policy/articlesonrequest/index.html/Control over solid state structure is critical for effective performance in optoelectronic devices bearing π-conjugated charge mediating organic materials. A series of five structurally related N-benzyl-substituted diketopyrrolopyrroles (DPPs) differing ... Novel crystal structures demonstrating long molecular axis, slipped, π−π cofacial stacking motifs and associated semiconductor bands in a series of N-benzylated diketopyrrolopyrroles are reported. Through variation of just 2 atoms from 60, clear crystal structure/(computed) charge transport activity interdependency is observed, with two structures exhibiting hole transport integrals comparable to Rubrene, a highly effective positive charge carrying, organic, crystalline materialPeer reviewedFinal Accepted Versio

A data-based mathematical modelling study to quantify the effects of ciprofloxacin and ampicillin on the within-host dynamics of Salmonella enterica during treatment and relapse.

Antibiotic therapy has drastically reduced the mortality and sequelae of bacterial infections. From naturally occurring to chemically synthesized, different classes of antibiotics have been successfully used without detailed knowledge of how they affect bacterial dynamics in vivo. However, a proportion of patients receiving antimicrobial therapy develop recrudescent infections post-treatment. Relapsing infections are attributable to incomplete clearance of bacterial populations following antibiotic administration; the metabolic profile of this antibiotic-recalcitrant bacterial subpopulation, the spatio-temporal context of its emergence and the variance of antibiotic-bacterial interactions in vivo remain unclear. Here, we develop and apply a mechanistic mathematical model to data from a study comparing the effects of ciprofloxacin and ampicillin on the within-host dynamics of Salmonella enterica serovar Typhimurium in murine infections. Using the inferential capacity of our model, we show that the antibiotic-recalcitrant bacteria following ampicillin, but not ciprofloxacin, treatment belong to a non-replicating phenotype. Aligning with previous studies, we independently estimate that the lymphoid tissues and spleen are important reservoirs of non-replicating bacteria. Finally, we predict that post-treatment, the progenitors of the non-growing and growing bacterial populations replicate and die at different rates. Ultimately, the liver, spleen and mesenteric lymph nodes are all repopulated by progenitors of the previously non-growing phenotype in ampicillin-treated mice.Bursary from Cambridge Mathematical Placement

Intermolecular interactions and energetics in the crystalline π–π stacks and associated model dimer systems of asymmetric halogenated diketopyrrolopyrroles

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Crystal Growth & Design, © 2016 American Chemical Society, after peer review and technical editing by the publisher. To access the final edited and published work see DOI: 10.1021/acs.cgd.5b01656/Four novel structurally analogous asymmetric, halogenated N-benzyl substituted diketopyrrolopyrroles (DPP) have been synthesized, and their crystal structures obtained. All four crystal structures exhibit π–π stacks with very small displacements along their short molecular axes, which based upon our previous studies involving symmetrical DPPs is a characteristic of N-benzyl substitution. Intermolecular interaction energies were computed for extracted crystal π–π dimer pairs by means of M06-2X density functional at the 6-311G(d) level to investigate the most energetically favored position of the halogen atoms in FBDPP and ClBDPP structures. In addition, effective stabilization energies arising from both benzyl and halogen substitution in these derivatives and in BrBDPP and IBDPP π–π dimer pairs were determined in order to probe the impact of these groups on the resulting dimer stability. Effects of the intermonomer displacements along the long molecular axis, which have been shown by us previously to significantly influence wavefunction overlap and effective electronic coupling, were investigated in detail using aligned and anti-aligned model systems of ClDPP and BrDPP. The predictions of these model systems are remarkably consistent with the observed displacements in their crystal derived π–π dimer pair equivalents, offering insight into the effective role of intermolecular contacts in crystal structures involving this molecular motif, particularly with a view toward crystal engineering in these systems. As a result, we believe that this study should be of significant interest to the growing DPP based materials community and in general to those investigating the detailed manner by which substituents can be employed in the supramolecular design of crystalline molecular architectures.Peer reviewedFinal Accepted Versio

Detection of nitroaromatic and peroxide-based explosives with amine- and phosphine-functionalized diketopyrrolopyrroles

Effective strategies for the detection and identification of explosives are highly desirable. Herein, we illustrate the efficient optoelectronic detection of nitroaromatic and peroxide-based explosives using amine- and phosphine-substituted diketopyrrolopyrroles. Selective quenching and an unprecedented enhancement of thin-film emission in the presence of nitroaromatic vapors are demonstrated via the judicious choice of amine substituents. The modulation of fluorescence emission in each case is shown to be dominated by electronic and thermodynamic effects, the vapor pressure of explosives, and the thin-film morphology. For peroxide detection, we describe an approach exploiting redox-mediated functional group transformation. The rapid oxidation of triphenylphosphine to phosphine oxide with hydrogen peroxide affords a significant increase in fluorescence emission, facilitating the sensitive turn-on detection of an important class of explosives at ppb concentrations

Detection of nitroaromatic vapours with diketopyrrolopyrrole thin films exploring the role of structural order and morphology on thin film properties and fluorescence quenching efficiency

This document is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. The Version of Record is available at: https://doi.org/10.1039/C4CC08468C.Sensitive optical detection of nitroaromatic vapours with diketopyrrolopyrrole thin films is reported for the first time and the impact of thin film crystal structure and morphology on fluorescence quenching behaviour demonstratedPeer reviewedFinal Accepted Versio