Studies in the Behaviour of Molecular Beams

This thesis describes the design, construction and development of a molecular beam apparatus for the study of interactions of gases with solid surfaces in systems of catalytic interest. The apparatus has been used in an investigation of the displacement, from palladium surfaces, of the surface species resulting from the adsorption of ethylene C-14 by beams of acetylene and ethylene. The apparatus produced ultimate static vacua of about 5 x 10e-9 torr. The palladium was in the form of a film, freshly deposited in vacuo, to which was admitted ethylene C-14 at a pressure of greater than 5 x 10e-2 torr, known to provide saturation of the surface with adsorbed species. The fate of the isotopically labelled surface species was followed in vacuum desorption and in beam-displacement reactions. The detector for radioactivity was, in the final form of the apparatus, a lithium-drifted silicon solid-state detector mounted close to the target inside the beam system. The maximum flux intensity which could be directed on to the surface was 2.5 x 10e13 molecules/cm 2/sec as against a background of scattered beam material of 4.1 x 10e13 molecules/cm 2/sec. The beam was produced from a source whose pressure was 2 x 10e-3 torr and whose temperature could be varied between 1

Quantification of the Energetic and Microcirculatory Heterogeneity in the Renal System

Acute kidney injury (AKI) is a syndrome characterized by the rapid loss of kidney function and is typically diagnosed by an increase in blood-urea-nitrogen and serum creatinine, a decrease in the glomerular filtration rate (GFR), and a decrease in urine output. AKI can be brought on by a myriad of events: physical damage to the kidney, cardiac arrest, blood loss, toxicologic effects from pharmacological drug use, and in most cases seen, sepsis. These events introduce global and or local ischemic insult to the kidney, causing a decrease in renal functionality. Originally, global renal hypoperfusion was thought to be the culprit causing AKI. However, evidence is showing that AKI can occur in the absence of this, proved by the normal or even increased blood flow seen in sepsis-induced AKI. In fact, studies are finding similar results that show microcirculatory dysfunction, inflammation, and tubular oxidative stress are the driving physiological factors for sepsis-induced AKI. The development and use of intravital video microscopy (IVVM) allows \textit{in vivo} studies of biological systems to be conducted. The excitation and emission of Flourophores are used to visualize specific structures and interactions within a system, and provide the means for analysis. Visualization of renal system structure and dynamics have be captured using IVVM, specifically ATP generation activity seen in the tubular epithelial cells and the microvascular dysfunction of blood flow associated with sepsis-induced AKI. The work proposed here focuses on using these images to quantify and explain the heterogeneity seen in the microhemodynamics of the cortical peritubular capillaries as well as mitochondrial energetics of the renal system. The information learned regarding oxygen delivery and energy consumption can be used to further understand the physio/pathophysio-logical interactions of the renal system in states of health and AKI

Delineating the role of βIV-Tubulins in pancreatic cancer: βIVb-tubulin inhibition sensitizes pancreatic cancer cells to vinca alkaloids

Pancreatic cancer (PC) is a lethal disease which is characterized by chemoresistance. Components of the cell cytoskeleton are therapeutic targets in cancer. βIV-tubulin is one such component that has two isotypes—βIVa and βIVb. βIVa and βIVb isotypes only differ in two amino acids at their C-terminus. Studies have implicated βIVa-tubulin or βIVb-tubulin expression with chemoresistance in prostate, breast, ovarian and lung cancer. However, no studies have examined the role of βIV-tubulin in PC or attempted to identify isotype specific roles in regulating cancer cell growth and chemosensitivity. We aimed to determine the role of βIVa- or βIVb-tubulin on PC growth and chemosensitivity. PC cells (MiaPaCa-2, HPAF-II, AsPC1) were treated with siRNA (control, βIVa-tubulin or βIVb-tubulin). The ability of PC cells to form colonies in the presence or absence of chemotherapy was measured by clonogenic assays. Inhibition of βIVa-tubulin in PC cells had no effect chemosensitivity. In contrast, inhibition of βIVb-tubulin in PC cells sensitized to vinca alkaloids (Vincristine, Vinorelbine and Vinblastine), which was accompanied by increased apoptosis and enhanced cell cycle arrest. We show for the first time that βIVb-tubulin, but not βIVa-tubulin, plays a role in regulating vinca alkaloid chemosensitivity in PC cells. The results from this study suggest βIVb-tubulin may be a novel therapeutic target and predictor of vinca alkaloid sensitivity for PC and warrants further investigation

Receipt, Property tax, 1854

https://egrove.olemiss.edu/aldrichcorr_c/1080/thumbnail.jp

Absence of juvenile effects confirmed in stable carbon and oxygen isotopes of European larch trees

Članek obravnava razmerja ogljikovih in kisikovih izotopov v branikah blizu stržena na prsni višini (cca 1,2 m) treh evropskih macesnov (Larix decidua Mill.), rastočih v mešanem gozdu s predraslimi hrasti in nasajenimi evropskimi macesni v zahodnem Walesu, Velika Britanija. Neklimatskega naraščajočega trenda v razmerjih ogljikovih izotopov, ki ga je sicer opaziti pri drugih vrstah v letih juvenilne rasti, ni, in tudi razmerje stabilnih izotopov ne kaže pomembnih trendov med odraščanjem drevesa. Rezultati iz prvih desetih branik ob strženu se bistveno ne razlikujejo od naslednjih dveh nizov desetih branik. O izostanku juvenilnega efekta v ogljikovih izotopih evropskega macesna so že poročali v zvezi z macesni, rastočimi v nesklenjenih sestojih v Franciji in to pripisali nezastrtosti krošenj in posledične neuporabe ogljikovega dioksida, ki ga pri dihanju oddajajo drevesa. Analizirana drevesa v zahodnem Walesu so rasla v nasadu s predraslimi hrasti, ki so bili starejši od podraslih macesnov. Macesni, kot svetloljubne drevesne vrste, so morali tekmovati za prostor in svetlobo, zato domnevamo, da je morebiten pojav juvenilnega efekta pri stabilnih izotopih prej posledica sprememb v hidravlični prevodnosti lesa, kot pa česa drugega. Ker današnja praksa izogibanja juvenilnega lesa omejuje potencial stabilnih izotopov drevesnih branik za dendroklimatološke in fiziološke raziskave, bi bile potrebnih dodatne raziskave o učinkih juvenilne rasti na pojav juvenilnega efekta v meritvah stabilnih izotopov

On Exchange of Orbital Angular Momentum Between Twisted Photons and Atomic Electrons

We obtain an expression for the matrix element for a twisted (Laguerre-Gaussian profile) photon scattering from a hydrogen atom. We consider photons incoming with an orbital angular momentum (OAM) of $\ell \hbar$, carried by a factor of $e^{i \ell \phi}$ not present in a plane-wave or pure Gaussian profile beam. The nature of the transfer of $+2\ell$ units of OAM from the photon to the azimuthal atomic quantum number of the atom is investigated. We obtain simple formulae for these OAM flip transitions for elastic forward scattering of twisted photons when the photon wavelength $\lambda$ is large compared with the atomic target size $a$, and small compared the Rayleigh range $z_R$, which characterizes the collimation length of the twisted photon beam.Comment: 16 page