Optical Dilatometry Measurements for the Quantification of Sustainable Aviation Fuel Materials Compatibility

Sustainable aviation fuel (SAF) offers a near-term opportunity to reduce aviation’s greenhouse gas emissions. Currently-approved SAFs are limited to a maximum blend ratio with conventional jet fuel due to materials compatibility issues (i.e., O-ring volume swell). Specifically, aircraft have been found to leak significant quantities of fuel when volume swell is insufficient. Here, optical dilatometer measurements of volume swell for SAFs are reported. These measurements will serve to screen candidate SAFs at an early stage of the approval process. Optical dilatometry measurements were also coupled with two-dimensional gas chromatography data to predict volume swell withfuel.https://ecommons.udayton.edu/grad_showcase/1001/thumbnail.jp

Fabrication and characterization of suspended pyrolytic carbon microstructures in various pyrolysis temperatures

The aim of this Master’s thesis is to fabricate and study the issues related to the fabrication of suspended C-MEMS microstructures, as well as to investigate the properties of unpatterned pyrolytic carbon films in relation to the pyrolysis temperatures. In recent years, suspended pyrolytic carbon microstructures have started to emerge as part of the next generation C-MEMS devices. Although the use of such structures can greatly improve the quality and expands the application of C-MEMS devices, suspended pyrolytic carbon microstructures are far more susceptible to fabrication issues than substrate-bound structures. So, in order to further advance the C-MEMS process we must first understand the underlying fabrication issues that these structures face. Suspended SU-8 microstructures with varying shapes and sizes were prepared with the use of sacrificial layers and pyrolyzed in an inert atmosphere, in order to obtain suspended pyrolytic carbon microstructures. The structures were then analyzed in terms of their structural stability (optical microscope, SEM) and contraction (profilometer). The pyrolytic carbon films were prepared by pyrolyzing unpatterned SU-8 films at four different pyrolysis temperatures between 800 and 1100 °C. The films were characterized in terms of their electrical resistivity (4-point probe), crystallinity (Raman spectroscopy) and surface roughness (AFM). During the fabrication process various issues were observed. This allowed us to determine a correlation between the shape and size of the microstructures with the specific fabrication issue, a potential reasoning as to why these issues would occur and how they can be avoided in the future. Based on the obtained results, a new analysis of the pyrolysis process was performed from a structural standpoint of SU-8 microstructures. Novel microstructures were also presented in the form of pyrolytic carbon cups, which show great promise as structures used for the trapping of micro and nanoparticles. Analysis of the pyrolytic carbon films show an increase in the electrical conductivity, surface roughness and crystallinity of the material with higher pyrolysis temperatures. The electrical resistivity drops from 1.29·10-4 to 2.92·10-5 Ωm as the pyrolysis temperature is increased from 800 to 1100 °C. At the same time, the surface roughness of the pyrolytic carbon films increases from 0.33 to 1.27 nm. The Raman spectra indicate a very high level of structural disorder and small crystallinity of the material. The crystallite size was calculated to increase from 6.45 to 9.15 nm with higher pyrolysis temperatures. Furthermore, detailed analysis of the Raman spectra also indicates a buildup of intrinsic stress at temperatures up to 1000 °C. Upon increasing the pyrolysis temperature further, the stress is gradually reduced from the material as the structure begins to anneal

Retrospektivna in trenutna vrstniška viktimizacija kot napovednika socialne samopodobe in osamljenosti pri študentih prvega letnika

Peer victimisation during school years has been found to significantly shape the way students perceive themselves and how they enter into relationships with peers, thus impacting students’ current and long-term wellbeing. However, victimisation has seldom been examined in university students. The present study aimed to investigate students’ current level of self-reported peer victimisation and perceived peer support and their retrospectively reported victimisation as predictors of their social self-concept and loneliness in their first year of university. First-year university students (N = 200; 26% male) participated in the study. The results indicated that retrospectively reported victimisation experiences during their years of schooling explained additional variance in social self-concept and loneliness beyond their concurrent peer experiences. These findings indicate that experiencing victimisation during school years could have consequences for students’ wellbeing that are not limited to the period of primary and secondary schooling, but can persist after their transition to university. Practical implications for the promotion of mental health in the higher education context are discussed. (DIPF/Orig.

Effect of laptop computer games on vision

Prolonged near work has been proposed to cause nearwork-induced transient myopia (NITM), a form of temporary nearsightedness. Although NITM has been demonstrated in other nearpoint tasks, this effect has never been studied in laptop computers. This study looked at the effects on refractive condition and visual acuity after playing a computer game on a laptop computer for 90 minutes. This task simulates real-world conditions. A Grand Seiko WR-5100K was used to take pre- and post-task refractive state measurements. Visual acuity was also assessed pre- and post-task. Overall, an initial myopic shift of 0.120 was noticed, with a return to baseline by 30 seconds post-task. A loss of visual acuity with magnitude 0.1 LogMAR was noted immediately post-task with a return to baseline accompanying the refractive state return to baseline. These findings suggest prolonged laptop usage in a real-world environment causes transient blur and brief NITM

CXCL7-Mediated Stimulation of Lymphangiogenic Factors VEGF-C, VEGF-D in Human Breast Cancer Cells

Increased expression of lymphangiogenesis factors VEGF-C/D and heparanase has been correlated with the invasion of cancer. Furthermore, chemokines may modify matrix to facilitate metastasis, and they are associated with VEGF-C and heparanase. The chemokine CXCL7 binds heparin and the G-protein-linked receptor CXCR2. We investigated the effect of CXCR2 blockade on the expression of VEGF-C/D, heparanase, and on invasion. CXCL7 siRNA and a specific antagonist of CXCR2 (SB225002) were used to treat CXCL7 stably transfected MCF10AT cells. Matrigel invasion assays were performed. VEGF-C/D expression and secretion were determined by real-time PCR and ELISA assay, and heparanase activity was quantified by ELISA. SB225002 blocked VEGF-C/D expression and secretion (P < .01). CXCL7 siRNA knockdown decreased heparanase (P < .01). Both SB225002 and CXCL7 siRNA reduced the Matrigel invasion (P < .01). The MAP kinase signaling pathway was not involved. The CXCL7/CXCR2 axis is important for cell invasion and the expression of VEGF-C/D and heparanase, all linked to invasion

Ion-chromatographic determination of glyphosate

Kromatografske metode su među najvažnijim metodama u analitičkoj kemiji jer omogućuju istovremeno odjeljivanje, identifikaciju i kvantitativno određivanje sastojaka u složenim smjesama. Ionska kromatografija (IC), često primjenjivana u industriji, vrlo je važna za analiziranje uzoraka koji sadrže ionske čestice. Najnoviji trendovi u kromatografiji općenito, pa time i u ionskoj, vezani su uz vezanje (uparivanje) više kromatografskih sustava u svrhu poboljšanja osjetljivosti analiza, ali i eventualne uštede troškova. Raspon analita je vrlo širok, od jednostavnih anorganskih iona do organskih molekula poput herbicida glifosata kojim se bavi i ovaj rad. Glifosat, često upotrebljavani herbicid, a koji može biti opasan po ljudsko zdravlje, u ovom je radu analiziran ionskom kromatografijom. Pri tome su za analizu primijenjeni 1D i 2D IC sustav. Za oba sustava razvijene su i validirane metode kromatografske analize glifosata. Primijenjena 1D metoda pokazala se nedostatnom za analizu realnog uzorka piva. 2D IC analizom uspješno je detektirana i kvantificirana koncentracija glifosata u analiziranom uzorku piva.Chromatographic methods are among the most important analytical methods since they enable simultaneously separation, identification and quantification of diverse compounds from complex matrices. Ion chromatography, often applied in industry, is very important for the analysis of samples containing ionic particles. Current trends in chromatography are related to multidimensional chromatography where two or more chromatographic systems are paired and applied for analysis in order to improve the method sensitivity and potentially reduce the analysis cost. Accordingly, same trends can be found in ion chromatography (IC) also. The range of IC analytes is very wide: from simple inorganic ions to organic molecules like herbicide glyphosate which is the analyte in this work. Glyphosate is very often used herbicide which can be dangerous to human health. This work describes development and validation of IC method for analysis of glyphosate in beer. 1D and 2D-IC systems were applied for this analysis. IC methods for glyphosate analysis were developed and validated for both systems. The applied 1D method proved to be insufficient for beer sample analysis. The applied 2D-IC method successfully detected and quantified glyphosate in analysed beer sample

Influence of chemical regeneration of TiO2/FeZSM5 on effectiveness of photocatalytic degradation of diclofenac in water under simulated solar irradiation

Porast broja stanovnika, razvoj industrije, te cjelokupni tehnološki napredak ostavili su jak utjecaj na okoliš. Broj onečišćujućih tvari koji se svakodnevno ispuštaju u okoliš, između ostalog i farmaceutika, raste sve više i više, te je potrebno pronaći metode kojima se te tvari iz okoliša mogu i ukloniti. Napredni oksidacijski procesi su se pokazali kao dobra metoda za uklanjanje farmaceutika iz okoliša, a karakterizira ih nastajanje jako reaktivnih i neselektivnih hidroksilnih radikala. Ti procesi djeluju brzo, te nakon razgradnje ostaje jako malo sekundarnog otpada. Među farmaceutike spada i diklofenak. Utjecaj diklofenaka na okoliš, te optimalne i ekonomski učinkovite načine njegove razgradnje potrebno je još detaljnije istražiti. U ovom radu ispitivao se utjecaj kemijske regeneracije TiO2-FeZ fotokatalizatora na razgradnju diklofenaka u vodenom mediju pod simuliranim sunčevim zračenjem. TiO2 je supstanca koja inače adsorbira u UV dijelu spektra. Budući da je 4-5% sunčevog zračenja od 300-400 nm, eksperiment je bilo moguće provesti i pod utjecajem sunčevog zračenja. Fotokatalizator se kemijski regenerirao ozonom. Diklofenak se uklanjao u 2 ciklusa, s tim da je u II ciklusu fotokatalizator bio kemijski regeneriran. Na kraju eksperimenta uspoređivani su rezultati I i II ciklusa, te je ustanovljeno da je nakon regeneracije fotokatalizator pokazivao nešto manju aktivnost nego prije regeneracije. Također je bilo bitno ustanoviti optimalne parametre pri kojima će regenerirani fotokatalizator davati najbolje rezultate. U tu svrhu provedeni su procesi regeneracije pri različitim uvjetima za različite pločice fotokatalizatora. Ustanovljeno je da koncentracija ozona znatno utječe na aktivnost fotokatalizatora, dok samo vrijeme ozonacije nema značajnog utjecaja. Također je ustanovljeno da je u II ciklusu najviše diklofenaka uklonjeno pri najvećoj koncentraciji ozona, i najduljem vremenu izlaganja.Population growth, development of industry, and overall technological progress have a strong influence on the environment. The number of pollutants, including pharmaceuticals, being released into the environment every day keeps growing, and for that reason, it is necessary to find appropriate methods for the removal of these pollutants from the environment. Advanced oxidation processes have been proven to be an excellent method for removal of pharmaceuticals from the environment. They are characterized with the fast reactions with the present organics, and they produce none or very small amounts of residual waste. They are characterized by the formation of very reactive and non-selective hydroxyl radicals. Diclofenac is one of the most widely available non-steroidal anti-inflammatory drugs. It's influence on the environment, and economically efficient ways of decomposing it need to be further investigated. In this work, the influence of chemical regeneration of TiO2-FeZ photocatalyst on the decomposition of diclofenac under simulated solar irradiation was examined. Diclofenac was removed in 2 cycles. In the second cycle, chemically regenerated photocatalyst by ozone was used. Based on the results, it was concluded that after the regeneration, the photocatalyst had shown lesser activity than before the regeneration. It was also important to establish the optimal values of regeneration parameters. In order to determine those parameters, different photocatalyst plates were treated with different concentrations of ozone, and they were exposed to ozone for different treatment periods. It was established that the concentration of ozone had a significant effect on the activity of the photocatalyst. However, the duration of the exposure didn't have a large effect on the results. It was also established that during the second cycle, the greatest amount of diclofenac was removed by applying the highest concentration of ozone, and highest duration of the exposure