Electric vehicles (EV) have become very popular in recent years because they are a more sustainable, efficient, and environmentally friendly transportation option than traditional fossil-fuel vehicles. Increased EV charging can cause overheating, accelerated aging, and eventual early failure of the distribution transformers, as the distribution networks have not been established foreseeing a large number of EVs as loads. This thesis makes contributions in two main areas to help reduce the accelerated aging of distribution transformers as the number of EVs on the road continues to rise. Firstly, vehicle smart charging is investigated to spread out the EV charging loads and hence decrease transformer heating and aging. Most EV smart charging algorithms require the use of extensive and costly infrastructure, including sensors, communication networks, controllable chargers, and central smart agents. This thesis proposes a new vehicle-directed smart charging strategy, called Random-In-Window (RIW) which allows individual vehicles to spread out their charging without any costly additional infrastructure. Detailed simulation results prove the advantages of this proposed algorithm. Secondly, to further reduce EV charging loads on the grid, a large-scale solar-charged electric vehicle (SEV) is proposed. While RIW smart charging has only grid benefits, SEVs can contribute to grid benefit, driver benefit, and environmental benefit, as shown through detailed simulation results, making it a viable solution to transformer aging mitigation. To turn the SEV concept into reality, this research also proposes a fast maximum power point tracking algorithm for partially shaded conditions, and an algorithm which optimizes photovoltaic (PV) cell size and arrangement along with the power electronic converter design for on-board solar charging. Thus, the proposed solutions in this research can help reduce distribution transformer aging as EV penetrations continue to rise and increase the environmental benefits of EVs through optimized solar charging. / Thesis / Doctor of Philosophy (PhD) / Overheating, accelerated aging, and eventual early failure of the distribution transformers caused by EV charging stress is a pressing concern that needs to be addressed. This thesis proposes two new vehicle-directed smart charging strategies and a concept of solar-charged electric vehicle (SEV) to help reduce the accelerated aging of distribution transformers. System level analysis of the mitigation of transformer aging using these two approaches with added driver and environmental benefits warrants the manufacturing and design challenges of the SEVs. Thus, this thesis proposes a fast and novel global maximum power point tracking algorithm well suited to fast moving vehicles for maximum solar power extraction at all times, especially during partial shading conditions, and an optimization process of the on-board PV cell dimension and number of such cells in series and parallel in the array based on power electronic converter for higher efficiency, lower cost, and lower mass.

Nanotechnology applications have emerged enormously in recent times. Of particular interest is that area that overlaps the areas of nanotechnology, biology and medicine: nanomedicine. One advantage of nanomedicines is it that it can be used as an enabling technology by pharmaceutical researchers and industry to overcome issues associated with the low bioavailability of hydrophobic drugs. In the first part of the current study, nanosuspensions of two of hydrophobic steroid drugs: hydrocortisone and prednisolone were produced. Nanosuspensions were prepared using a bottom-up approach: the anti-solvent precipitation method using microfluidic reactors. Surface modification was carried out on these nanosuspensions using cationic surfactants to obtain nanoparticles with different levels of surface positive charge as indicated by ¿-potential values. Dynamic light scattering (DLS) and transmission electron microscope (TEM) techniques were used to characterize the prepared nanoparticles. Powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) were also used to characterize hydrocortisone nanoparticles. In the second part, cellular uptake of both coated and uncoated nanoparticles by HaCaT keratinocytes cell line was examined and indicated by quantifying the anti- inflammatory effect of nanoparticles on the LPS-induced inflammation. Also, TEM was employed to evaluate the cellular uptake of hydrocortisone nanoparticles. Results showed higher ant-inflammatory effect of coated nanoparticles over uncoated nanoparticles. Furthermore, the anti-inflammatory effect of coated nanoparticles was correlated to the degree of positive surface charge. / Libyan government

No description available.

Over the past two decades, vibrational sum-frequency generation (VSFG) has been applied as a versatile technique for probing the structure and dynamics of molecules at surfaces and interfaces. The excellent surface specificity of the SFG allows for probing different kinds of liquid interfaces with no or negligible contribution from adjacent and much deeper bulk phase. VSFG spectroscopy has provided evidence that the structure of the water at interfaces is different from the bulk. With the ultrafast pulses, VSFG can also be used as a probe of ultrafast vibrational dynamics at interfaces. However, apart from a few pioneering studies, the extension of VSFG into time domain has not been explored extensively. Here VSFG is used as a probe of ultrafast vibrational dynamics of water at silica interfaces. Silica is an excellent model system for the solid phase where one can systematically vary the surface charge via bulk pH adjustment. The extension of the surface electric field, the interfacial thickness and surface accumulation of ions at a charged silica surface were studied using IR pump-VSFG probe spectroscopy. A vibrational lifetime (T1) of about 250 fs, similar to bulk H2O, was observed for the O-H stretch of H2O/silica interface when the silica surface is negatively charged. At the neutral surface, where the thickness of interfacial water is smaller than at the charged surface, the vibrational lifetime of O-H stretch becomes more than two times longer (T1~ 600 fs) due to the decreased number of neighboring water molecules, probed by SFG. The fast T1 at negatively charged surface begins to slow down by screening of the penetration of surface electric field via adding salt which suggests the primary reason for similar vibrational dynamics of water at charged interface with bulk water is the penetration of electric field. By decoupling of OH of HDO in D2O, a frequency dependent vibrational lifetime is observed with faster T1 at the red compared to the blue side of the hydrogen bond spectral region. This correlates with the redshift of the SFG spectra with increasing charged surface and is consistent with a theoretical model that relates the vibrational lifetime to the strength of the hydrogen bond network. / Chemistry

<p dir="ltr">Introduction: Radiotherapy is a treatment modality that is prescribed for more than 50% of cancer patients around the globe. Through decades of clinical application, RT has witnessed considerable advancements achieving significant tumor control with minimal damage to healthy tissues. Recently, a paradigm shift has recognized RT's potential to induce anti-tumor immune responses, where patients receiving radiation to the primary tumor also resolved lesions outside the treatment field. This out-of-field response also referred to as an abscopal effect, is believed to promote immunogenic cell death (ICD) initiated by the radiation-induced DNA damage and subsequent activation of the cGAS-STING-IFNβ pathways. However, clinical realization of an abscopal effect remains rare. We <i><u>hypothesize</u></i> by selectively irradiating cancer cells with high metastatic potential within a solid tumor (intra-tumor radiotherapy treatment planning) with high metastatic potential, a more efficient anti-tumor response can be achieved while minimizing inflammatory responses from surrounding tumor and normal tissues, obfuscating a potential adaptive immune response, thus help in overcoming the rarity observed in the clinical practice. To achieve this <i><u>objective</u></i>, radiotherapy treatment plans targeting hypoxic regions (known to harbor a metastatic phenotype) within a solid tumor and optimally activating IFNβ will be investigated.</p><p dir="ltr">Methods: Hypoxic conditions within tumor microenvironments significantly reduce DNA damage, conferring a radioresistant phenotype that leads to RT failure. To address the inherent radioresistance and immunosuppression of hypoxic tumors, high linear energy transfer (LET) modalities are used. Our research aims to enhance the specificity and efficiency of ICD, particularly in highly metastatic (hypoxic) regions within the tumor, by employing heavy charged particle (HCP) beams to optimize DSB induction. Empirical mathematical models have been developed to predict the dose-response of IFNb based on in vitro data and Monte Carlo methods of DSB-induction. These methods are used in maximizing type I interferon (IFNβ) production and subsequent immune response while minimizing the inflammatory response and damage to surrounding tissue. Immunogenic treatment plans, iTPS, have been developed to integrate charged particle beam models for proton, helium, and carbon ions and the above-empirical models into FLUKA Monte Carlo simulations and subsequently evaluated in clinical case studies of brain and lung cancer. Next, new biophysical models accounting for tumor hypoxia were developed and integrated into the iTPS, and clinical case studies were reevaluated.</p><p dir="ltr">Results: SA(1): Developed and integrated charged particle beam models into FLUKA MC for both homogeneous and heterogeneous treatment planning. Empirical equations for RBE_{DSB, pO2}, LET, and IFNβ dose-response were incorporated into FLUKA for voxel-based simulations across oxygen levels. SA(2): RBE_DSB-weighted optimization yielded uniform IFNβ production. High LET enabled carbon ion beams to require the lowest doses, achieving superior peak-to-entrance ratios of 15.85 compared to 10.78 and 7.60 for helium and proton beams, respectively. Patient simulations demonstrated carbon ions' superiority, with D_95% values of 7.68 Gy for the brain and 7.60 Gy for lung tumors, excelling in IFNβ production. SA(3): An optimized treatment plan for uniform IFNβ in hypoxia utilizing empirical equations for RBE_DSB across hypoxia levels was created for different charged particles. MCC13 adjustments based on OER_DSB from MCDS were confirmed by measured data in U251 cell lines, showing an OER of 1.5 between normoxia and 1% hypoxia, closely matching MCDS predictions within a 7% discrepancy. Carbon ions achieved optimal IFNβ at 11.02 Gy for brain tumors under 0.1% hypoxia in FLUKA simulations.</p><p dir="ltr">Conclusions: Our results from both homogeneous target and patient cases demonstrate that charged particles have the potential to elicit higher levels of IFNβ at lower doses compared to photon irradiations in different pO₂ levels. High LET irradiation not only ensures a highly localized IFNβ response in the target but also effectively spares surrounding normal tissues, thereby minimizing treatment-related toxicity. This finding underscores the superiority of high LET irradiation in achieving targeted immunogenic effects while enhancing the therapeutic window by reducing damage to normal cells.</p>

No / The 70 eV electron impact mass spectra of a wide range of 2-substituted benzazoles are reported and discussed. Particular attention is paid to the mechanistic significance and analytical utility of [M–H]+ and [M–X]+ signals in the spectra of benzazoles in which the 2-substituent contains a terminal aryl group with one or more substituents, X. Loss of H or X occurs preferentially from an ortho-position from ionized 2-benzylbenzimidazoles, 2-phenethylbenzimidazoles, 2-styrylbenzimidazoles, 2-styrylbenzoxazoles and 2-styrylbenzothiazoles. In the three styrylbenzazole series, the [M–H]+ and/or [M–X]+ signals dominate the spectra. This unusually facile loss of H or X may be attributed to a proximity effect, in which cyclization of the ionized molecule is followed by elimination of an ortho-substituent to give an exceptionally stable polycyclic ion. Formation of a new five- or six-membered ring by the proximity effect occurs rapidly; cyclization to a seven-membered ring takes place rather less readily; but formation of a ring with only four atoms or more than seven atoms is not observed to a significant extent. The proximity effect competes effectively with loss of a methyl radical by simple cleavage of an ethyl, isopropyl and even a t-butyl group in the pendant aromatic ring of ionized 2-(4-alkylstyryl) benzazoles.

No / Piperacillin, a potent ß-lactam antibiotic, is effective in a large variety of Gram+ and Gram¿ bacterial infections but its administration is limited to the parenteral route as it is not absorbed when given orally. In an attempt to overcome this problem, we have synthesized a novel series of charged liposaccharide complexes of piperacillin comprising a sugar moiety derived from d-glucose conjugated to a lipoamino acid residue with varying side-chain length (cationic entity) and the piperacillin anion. A complete multiple reaction monitoring LC¿MS/MS method was developed to detect and characterize the synthesized complexes. The same method was then successfully applied to assess the in vitro apparent permeability values of the charged liposaccharide complexes in Caco-2 monolayers. / BBSRC

Radiotherapy is used in clinics to treat cancer with highly energetic ionizing particles. The radiation dose can be measured indirectly by means of radiation detectors or dosimeters. The dose deposited in a detector can be related to dose deposited in a point within the patient. In theory, however, this is only possible under charged particle equilibrium (CPE). The motivation behind the dissertation was driven by the difficult, yet crucial, dosimetry in non-CPE regions. Inaccurate dose assessment performed with standard dosimetry using ionization chambers may significantly impact the outcomes of radiotherapy treatments. Therefore, advanced dosimetry methods tailored specifically to suit non-CPE conditions must be used. This work aims to improve dosimetry in two types of non-CPE conditions that pose dosimetric challenges: regions near interfaces of tissues with low- and high- density media and in small photon fields. To achieve the main dissertation objectives, an enhanced film dosimetry protocol with a novel film calibration approach was implemented. This calibration method is based on the percent depth dose (PDD) tables and was shown to be efficient and accurate. As a result, the PDD calibration method was used for the film dosimetry process throughout the dissertation work. Monte Carlo (MC) calculations for the small field dosimetry were performed using phase-space files (PSFs) provided by Varian for TrueBeam linac. The MC statistical uncertainty in these types of calculations is limited by the number of particles (due to latent variance) in the used PSFs. This study investigated the behaviour of the latent variances (LV) with beam energy, depth in phantom, and calculation resolution (voxel size). LV was evaluated for standard 10x10 cm2 fields as well as small fields (down to 1.3 mm diameter). The results showed that in order to achieve sub-percent LV in open 10x10 cm2 field MC simulations a single PSF can be used, whereas for small SRS fields (1.3—10 mm) more PSFs (66—8 PSFs) would have to be summed. The first study in this dissertation compared the performance of several dosimetric methods in three multi-layer heterogeneous phantoms with water/air, water/lung, and water/steel interfaces irradiated with 6 and 18 MV photon beams. MC calculations were used, along with Acuros XB, anisotropic analytical algorithm (AAA), GafChromic EBT2 film, and MOSkin dosimeters. PDDs were calculated and measured in these heterogeneous phantoms. The result of this study showed that Acuros XB, AAA, and MC calculations were within 1% in the regions with CPE. At media interfaces and buildup regions, differences between Acuros XB and MC were in the range of +4.4% to -12.8%. MOSkin and EBT2 measurements agreed to MC calculations within ~ 2.5%-4.5%. AAA did not predict the backscatter dose from the high-density heterogeneity. For the third, multilayer lung phantom, 6 MV beam PDDs calculated by all treatment planning system (TPS) algorithms were within 2% of MC. 18 MV PDDs calculated by Acuros XB and AAA differed from MC by up to 3.2 and 6.8%, respectively. MOSkin and EBT2 each differed from MC by up to 3%. All dosimetric techniques, except AAA, agreed within 3% in the regions with particle equilibrium. Differences between the dosimetric techniques were larger for the 18 MV than the 6 MV beam. This study provided a comparative performance evaluation of several advanced dosimeters in heterogeneous phantoms. This combination of experimental and calculation dosimetry techniques was used for the first time to evaluate the dose near these interfaces. The second study in the dissertation aims to improve dose measurement accuracy in small radiotherapy fields. Field output factors of 6 MV beams from TrueBeam linear accelerator (linac) collimated with 1.27-40 mm diameter cones were calculated and measured using MC and EBT3 films. A set of detector specific correction factors for two widely used dosimeters (EFD-3G diode and PTW-60019 microDiamond detectors) were determined based on GafChromic EBT3 film measurements and calculated using MC methods. MC calculations were performed for microDiamond detector in parallel and perpendicular orientations relative to the beam axis. The result of this study showed that the measured OFs agreed within 2.4% for fields ≥10 mm. For the cones of 1.27, 2.46, and 3.77 mm diameter maximum differences were 17.9%, 1.8% and 9.0%, respectively. MC calculated OF in water agreed with those obtained using EBT3 film within 2.2% for all fields. MC calculated output correction factors for microDiamond detector in fields ≥10 mm ranged within 0.975-1.020 for perpendicular and parallel orientations. MicroDiamond detector correction factors calculated for the 1.27, 2.46 and 3.77 mm fields were 1.974, 1.139 and 0.982 with detector in parallel orientation, and these factors were 1.150, 0.925 and 0.914 in perpendicular orientation. EBT3 and MC obtained correction factors agreed within 3.7% for fields of ≥3.77 mm and within 5.9% for smaller cones. This work provided output correction factors for microDiamond and EFD-3G detectors in very small fields of 1.27 – 3.77 mm diameter and demonstrated over and under-response of these detectors in such fields. These correction factors allow improve the accuracy of dose measurements in small photon fields using these detectors. / Graduate / 2019-08-30

This thesis contains a study of the robustness of the artificial neural network used in the ATLAS track reconstruction algorithm as a tool to recover tracks in dense environments. Different variations, motivated by potential discrepancies between data and simulation, are performed to the neural network’s input while monitoring the corresponding change in the output. Within reasonable variation magnitudes, the neural networks prove to be robust to most variations. In addition, a measurement of charged particle distributions is summarised. This is one of the first such measurements carried out for proton-proton colli- sions at √s = 13 TeV, limited to a phase space defined by transverse momentum pT &gt; 100 MeV and absolute pseudorapidity |η| &lt; 2.5. Tracks are corrected for de- tector inefficiencies and unfolded to particle-level. The result is compared to the prediction of different models. Overall, the EPOS and Pythia 8 A2 models show the best agreement with the data. / Spår från elektriskt laddade partiklar rekonstrueras i ATLAS genom att kombinera mätningar från de innersta subdetektorerna. I de extrema miljöer som skapas i proton-proton-kollisionerna i Large Hadron Collider vid CERN är det av yttersta vikt att algoritmen för att rekonstruera spår är högpresterande. Uppgiften är särskilt svår i partikelrika miljöer där flera partiklar färdas nära varandra, åtskilda av avstånd jämförbara med storleken på detektorns utläsningselement. Ett artificiellt neuralt nätverk används i algoritmen för att klassificera mätdata från pixeldetektorn, belägen närmast interaktionspunkten, för att lyckas identifiera spår i partikelrika miljöer som annars hade gått förlorade. I denna avhandling utreds det neurala nätverkets stabilitet. Dess känslighet studeras genom att manuellt manipulera dess indata och därefter utvärdera dess resultat. Nätverket tränas med simulerad data. Variationerna i indata är utformade för att undersöka skillnader mellan data och simulering, orsakade av osäkerheter i simuleringsmodellen eller osäkerheter i pixeldetektorns kalibrering. Av de undersökta variationerna har en osäkerhet i skalan eller utläsningströskeln för pixeldetektorns kalibrering den största effekten på nätverkets resultat. Andra variationer har en betydligt mindre påverkan. Avhandlingen presenterar också en studie av distributioner av elektriskt laddade partiklar producerade i proton-proton-kollisioner. Det är en av de första studierna av partikeldistributioner för Large Hadron Colliders andra körning med mass-centrum-energi √s = 13 TeV. Mätningen är begränsad till fasrymden definierad av en transversell rörelsemängd pT &gt; 100 MeV, och absolut rapiditet |η| &lt; 2.5. Spår av partiklar rekonstrueras och korrigeras för detektorns ineffektiviteter för att presenteras på partikelnivå. Dessa jämförs sedan med förutsägelser från olika modeller. Modellerna EPOS och Pythia 8 A2 är generellt de som bäst överensstämmer med data. Författaren har undersökt partiklar som migrerar in och ut ur fasrymden. Andelen spår associerade till partiklar som migrerat utifrån uppskattas med simulerad data, till som mest 10% nära fasrymdens gränser. Osäkerheten på denna andel uppskattas till att vara som mest 4.5%, huvudsakligen orsakad av osäkerheten på mängden material i de innersta subdetektorerna. / <p>QC 20160817</p>

Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: See full text for abstract / AFRIKAANSE OPSOMMING: Sien volteks vir opsomming