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- Jussi, Johnny, 1989-
(författare)
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Fluorescent quantum dots and graphene-based sensors for forensic applications
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A key emerging concept within the forensic sciences today areportable measurementdevices, where a much more efficient usage of the resources involved with crime-solving is possible if confirmatory measurements can be realised directly at a crimescene with such devices. Today, the majority of the presently used methods duringcriminal investigation at a crime scene involves measurements of a presumptivenature, which is a vital tool as it enables the screening of samples. In this thesis,the overarching goal is the development of tool kits for the analysis of biosampleson-site at a crime scene. This is mainly investigated through two routes: theusage of Quantum Dots (QDs) as a recognition element in sensory applications andfabrication of a graphene-based device for the detection of illicit drugs.The investigations conducted for the studies presented in this thesis focuses onsensory applications with a forensic detection scheme in mind: study I reveals in-trinsic properties of QDs to better understand sensing mechanisms upon bindinginteractions; study II demonstrates the fabrication of a graphene-based device forthe detection of illicit drugs; study III showcases the functionalised and bioconju-gated of QDs for a specific investigation into a biological process; study IV furtherthe investigation into the possible side-effects of QDs on biological specimens.In study I we numerically and experimentally investigate the intrinsic blinkingcharacteristics of CdSe-CdS/ZnS QDs. This includes a thorough examination of theexperimental parameters of the measurement setup: the bin time and excitationpower. Different mechanisms between the off- and on-state probability distributionsare found, wherein the on-state follows the random telegraph signal theory and theoff-state follows the inverse power law distribution.In study II, the detection of illicit drugs (amphetamine and cocaine) is achievedthrough graphene-based sensors processed to contain metal electrodes with superioradhesion and low contact resistance. The construction of a microfluidic system isfurther realised for a detection of molecules based on non-covalent interactions.With this system, a wavelength-dependent photoactivity for amphetamine and arange of its chemical analogs is demonstrated. A molecule dependent interactionwith the graphene surface is shown of the graphene surface either in the form ofp-doping (cocaine) or n-doping (amphetamine).Study III investigates the endocytic pathway of the vascular cell adhesionmolecule 1 (VCAM1) in Human Umbilical Vein Endothelial Cells (HUVECs) in-iiiivABSTRACTduced by Tumor Necrosis Factorα(TNFα) with the usage of 3-Mercaptopropionicacid coated (3MPA)-QDs and 5-Carboxyfluorescein (5FAM) functionalised and la-belled with VCAM1 binding peptides, respectively. Internalisation of the VCAM1molecules into lysosomes is shown with light microscopy through observations ofdifferent pathways of the 5FAM labelled peptides and functionalised QDs.In study IV we investigate the adverse effects of 3MPA-QDs on the humanairway epithelium by an examination of the calcium response in lung cells upon astimulation with QDs. The cellular response to the deposition of QDs is observedwith light microscopy and electrical measurements as a global increase of Ca2+in the epithelial layers and a transient decrease in the electrical response. Theseobservations imply that the influx of calcium caused by the QD deposition is inducedby mechanical stressIn an additional ongoing study, the age determination of dried blood spotsare investigated with the usage of protein markers commonly found in the blood.Human serum (HS) is spiked with a marker of interest to mimic those of normallevels in adult human males. After which the HS is allowed to undergo an ageingprocess in a 96 well plate and further analysed in terms of the enzymatic activitywith commercially available kits. The preliminary test results show that there is ameasurable change of activity dependenton the utilised marker that may act as abasis for the age determination of dried blod spots
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- Bazargan, Mohsen
(författare)
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Numerical and laboratory studies of seismic properties and elements of rock fabric from the microscale to the macroscale
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Physical properties of rocks studied in the laboratory are useful to provide constraints on the dynamics of Earth’s interior. This may include direct constraints on in-situ seismic properties, such as elastic wave velocity measurements that can be compared to seismological data, or petrofabric indicators such as anisotropy of magnetic susceptibility (AMS). Another approach that provides predictive insight into the physical properties of Earth’s interior are computer models. Numerical modelling, in particular, can be used to investigate the dynamic propagation of elastic waves or the flow of a material to generate a fabric or texture (i.e., petrofabric in rocks). This thesis focuses on an integrative approach, utilizing both laboratory measurements and numerical modelling, to understand physical properties and petrofabric development in rocks originating in Earth’s crust. The physical properties of rocks are affected by both intrinsic sources (e.g., inherent to crystals) and extrinsic sources (e.g., layering, microcracks, shape preferred orientation of crystals, grain size, presence of geological fluids). A versatile numerical elastic wave propagation model is constructed with COMSOL Multiphysicsâ and benchmarked against a stainless-steel standard used for laboratory elastic wave measurements. The numerical model is flexible and enables setup of composite materials with different sample geometries, which is of importance when modeling the physical properties of rocks in realistic geological scenarios. Using the elastic wave propagation model, this thesis explores different scenarios and their influence on seismic properties, including the effect of grain size on bulk elastic wave speed and compositional layering on seismic anisotropy. The first application focuses on a joint laboratory and numerical study of similar composition gabbro samples, with distinctly different grain size. The numerical model is used to evaluate the relationship between wavelength and grain size. The second application utilizes laboratory measurements as input data for the models, to determine seismic properties of compositionally layered materials. It is shown that the seismic properties, and in particular anisotropy, of a layered material depends on 1) the combination of the inherent rock properties and layering and 2) the wavelength (l) to layer thickness ratio (d). Importantly, independent of scale, the physical properties are wavelength dependent, showing a decrease (apparent dispersion) in velocity, when transitioning from a ray medium (l/d < 1) to an effective medium (l/d > 10). In the second part of this thesis, another COMSOL Multiphysics modelling approach is used to investigate how crystals rotate in a magmatic flow, and how a petrofabric in different magmatic rocks may develop. A set of different magmatic flow scenarios are explored, with direct application to natural examples of dykes and magma chambers. These numerical models may serve as useful predictors of petrofabric in igneous rocks where determination of flow direction of magma is of interest.
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- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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- Mao, Jia, et al.
(författare)
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A 90nm CMOS UHF/UWB asymmetric transceiver for RFID readers
- 2011
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Ingår i: European Solid-State Circuits Conference. - 9781457707018 ; , s. 179-182
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents an integrated asymmetric transceiver in 90nm CMOS technology for RFID reader. The proposed reader uses UHF transmitter to power up and inventory the tags. In the reverse link, a non-coherent Ultra-wide Band (UWB) receiver is deployed for data reception with high throughput and ranging capability. The transmitter delivers 160 kb/s ASK modulated data by an integrated modulator and a Digital Controlled Oscillator (DCO) in UHF band with 11% tuning range. The DCO consume 6 mW with 0.12 mm2 area. On the other side, adopting two integration channels, the 3-5 GHz energy detection receiver supports maximum 33 Mb/s data rate both in OOK and PPM modulations. The receiver front-end provides 59 dB voltage gain and 8.5 dB noise figure (NF). Measurement results shows that the receiver achieves an input sensitivity of -79 dBm at 10 Mb/s, with power consumption of 15.5 mW.
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