Mechanisms of High Temperature Degradation of Thermal Barrier Coatings.

Thermal barrier coatings (TBCs) are crucial for increasing the turbine inlet temperature (and hence efficiency) of gas turbine engines. The thesis describes PhD research aimed at improving understanding of the thermal cycling failure mechanisms of electron beam physical vapour deposited (EB-PVD) yttria stabilised zirconia (YSZ) TBCs on single crystal superalloys. The research consisted of three different stages. The first stage involved designing a coupled one-dimensional thermodynamic-kinetic oxidation and diffusion model capable of predicting the concentration profiles of alloying elements in a single-phase γ nickel-rich Ni-Al-Cr ternary alloy by the finite difference method. The aim of this investigation was to improve the understanding of interactions between alloying species and developing oxide. The model demonstrated that in the early stages of oxidation, Al consumption by oxide scale growth is faster than Al replenishment by diffusion towards the scale, resulting in an initial Al depletion in the alloy near the scale. The second stage involved a systematic study of the life-time of TBC systems on different single crystal superalloys. The study aimed at demonstrating that the compatibility of modern nickel-based single crystal superalloys with TBC systems is influenced strongly by the content of alloying element additions in the superalloy substrate. The results can be explained by postulating that the fracture toughness parameters controlling decohesion are influenced strongly by small changes in composition arising from interdiffusion with the bond coat, which itself inherits elemental changes from the substrate. The final stage of study involved a detailed study of different bond coats (two β-structured Pt-Al types and a γ/γ’ Pt-diffusion type) in TBC systems based on an EB-PVD YSZ top coat and a substrate material of CMSX-4 superalloy. Generation of stress in the thermally grown oxide (TGO) on thermal cycling, and its relief by plastic deformation and fracture, were investigated experimentally in detail

Transcranial Direct Current Stimulation for the Reduction of Alcohol Craving

BACKGROUND: Craving is implicated the maintenance of alcohol abuse and dependence as well as relapse during attempts at recovery. An early investigation by Boggio et al. (2008b) demonstrated that transcranial direct current stimulation (tDCS) applied over dorsolateral prefrontal cortex (DLPFC) was effective in reducing craving among individuals with alcohol dependence. The present study is the first to continue to explore the potential of tDCS to manipulate craving in the context of alcohol use and abuse. METHODS: 18 adult participants completed assessments of alcohol abuse severity, and of alcohol craving and mood before and after transcranial stimulation. Active and sham tDCS of DLPFC was utilized in two separate experimental sessions. The protocol was revised midway through the study to include potential induction of craving through the visual presentation of alcohol cues. RESULTS: Within the revised protocol, a comparison of pre- to post-stimulation difference scores for active versus sham stimulation produced a reduction in craving that approached significance (p = .06). A comparison of pre- to post-stimulation scores for active stimulation produced a significant reduction in craving (p = .03), whereas a comparison of pre- to post-stimulation scores for sham stimulation was nonsignificant(p = .42). A significant linear relationship existed between response to active stimulation and both alcohol abuse severity and retrospective accounts of alcohol craving. CONCLUSIONS: The findings showed that tDCS applied to the DLPFC may be effective in reducing alcohol craving among individuals with alcohol use disorders who experience frequent or intense cravings. The use of minimum cutoff scores on assessments of alcohol abuse severity and alcohol craving may aid in identifying individuals who would benefit from tDCS treatment. Additional research may demonstrate the utility of noninvasive brain stimulation in clinical alcohol abuse treatment settings

The Effects of the Vitamin E Isomers Gamma Tocopherol and Gamma Tocotrienol on the NFkB Pathway in the PC-3 Cell Line.

Regions along the Mediterranean and Southern Asia have lower prostate cancer incidence compared to the rest of the world. It has been hypothesized that one of the potential contributing factors for this low incidence includes a higher intake of vitamin E (tocopherols and tocotrienols). This study examines the potential of gamma tocopherol (GT) and gamma tocotrienol (GT3) to reduce prostate cancer proliferation by examining their effects on the NFκB pathway. NFκB is known to inhibit apoptosis in cancer cells. Our data shows that both GT and GT3 are capable of down regulation of NFκB precursors and up regulation of Caspase 8, indicating an induction of apoptosis

Ples z družbeno smrtjo: nekropolitika uprizarjanja afro-slovenstva

Slovenes of African descent find themselves in a calculus of biopower. This points to the precariousness of life (or flesh), which is deemed as less “worthy.” We are at a historical moment in which Afro-pessimism offers a “realistic” glimpse into the past and future of Blackness in the White supremacist contexts of the West, due almost solely to the enormity of systemic violence that Black flesh has endured. In light of this very real political urgency, there is a very real need for security, which in the short term might best be accomplished through concepts such as identity and authenticity. However, Afro-Slovene acts of living reject in passing the priorities that “progress” evokes through the standardization of Euro-normalizing biopolitical orders and slip the categories used to confine them to a limited form of existence. This analysis focuses on the Afro-Slovene insistence on living otherwise as a form of resistance to the tyranny of linear progressive subjectivities, without shedding responsibility for the need to confront race and racism head on.Slovenci afriškega porekla se znajdejo v kalkulaciji biomoči. To kaže na negotovost življenja (ali mesa), ki velja za manj »vredno«. Smo v zgodovinskem trenutku, v katerem afropesimizem ponuja »realističen« vpogled v preteklost in prihodnost Črnskosti v okvirih belih supremacističnih kontekstov Zahoda, in sicer skoraj izključno zaradi obsežnosti sistemskega nasilja, ki ga je pretrpelo »Črnsko meso«. V luči te konkretne politične nujnosti obstaja zelo resnična potreba po varnosti, ki jo je kratkoročno mogoče najbolje doseči s koncepti, kot sta identiteta in avtentičnost. Vendar pa afro-slovenski načini življenja zavračajo prioritete, ki jih prek standardizacije evronormalizacijskih biopolitičnih praks spodbuja »napredek«, s tem pa se izmuznejo kategorijam, ki jih silijo v omejeno obliko obstoja. Ta analiza se osredotoča na afro-slovensko vztrajanje pri drugačnem načinu življenja kot obliki upora proti tiraniji linearnih progresivnih subjektivitet, ne da bi pri tem zavračalo odgovornost za potrebo po neposrednem soočenju s problematiko rase in rasizma

Gelfand duality for compact pospaces

It is well known that the category of compact Hausdorff spaces is dually equivalent to the category of commutative C^\star-algebras. More generally, this duality can be seen as a part of a square of dualities between compact Hausdorff spaces, C^\star-algebras, compact regular frames and de Vries algebras. Three of these dualities have been extended to dualities between compact pospaces, stably compact frames and proximity frames, the fourth part of the square being lacking. We propose the category of bounded Archimedean l-semi-algebra to complete what will be the outside square of dualities and to extend to category of C^\star-algebras