Adriana Szeghalmi

The Creatine Kinase/Creatine Connection to Alzheimer's Disease: CK Inactivation, APP-CK Complexes and Focal Creatine Deposits

Cytosolic brain-type creatine kinase (BB-CK), which is coexpressed with ubiquitous mitochondrial uMtCK, is significantly inactivated by oxidation in Alzheimers disease (AD) patients. Since CK has been shown to play a fundamental role in cellular energetics of the brain, any disturbance of this enzyme may exasperate the AD disease process. Mutations in amyloid precursor protein (APP) are associated with early onset AD and result in abnormal processing of APP, and accumulation of Aβ peptide, the main constituent of amyloid plaques in AD brain. Recent data on a direct interaction between APP and the precursor of uMtCK support an emerging relationship between AD, cellular energy levels, and mitochondrial function. In addition, recently discovered creatine (Cr) deposits in the brain of transgenic AD mice, as well as in the hippocampus from AD patients, indicate a direct link between perturbed energy state, Cr metabolism, and AD. Here, we review the roles of Cr and Cr-related enzymes and consider the potential value of supplementation with Cr, a potent neuroprotective substance. As a hypothesis, we consider whether Cr, if given at an early time point of the disease, may prevent or delay the course of AD-related neurodegeneration.

Atomic layer deposition of Al 2 O 3 and TiO 2 multilayers for applications as bandpass filters and antireflection coatings

Al(2)O(3) and TiO(2) thin films have been deposited on Si wafers, quartz, BK7 glass, and polycarbonate substrates by atomic layer deposition (ALD). The refractive indices and growth rates of the materials have been determined by spectroscopic ellipsometry and transmission electron microscopy. The influence of substrate temperature and precursor on the refractive indices has been investigated. The refractive index of TiO(2) significantly increases with temperature, whereas the Al(2)O(3) films are temperature insensitive. The films deposited using H(2)O(2) as oxygen source show a slightly higher refractive index than the films prepared with H(2)O. Multilayer narrow-bandpass filters and broadband antireflective coatings have been designed and produced by ALD.

Ultrafast proton transfer of 1-hydroxy-2-acetonaphthone : Reaction path from resonance raman and transient absorption studies

The intramolecular degrees of freedom contributing to the ultrafast excited-state intramolecular proton transfer of 1-hydroxy-2-acetonaphthone are determined. Thereto, resonance Raman studies are combined with transient absorption measurements with 30-fs time resolution. Enhanced Raman intensity is found in coordinates that are dominantly associated with deformations and bond length changes in the naphthalene chromophore. This indicates that the primary changes after the optical excitation are a geometric relaxation of the chromophore. A ringing of the molecule after the ultrafast proton transfer is observed by the transient absorption measurements. It reveals the nuclear coordinates contributing to the reaction path beyond the Franck-Condon region. There, planar H-chelate ring deformations changing the donor-acceptor distance are found to dominate. The difference in the observed vibrational signatures indicates a significant turn in the reaction path.

Multilayer Fresnel zone plate for soft X-ray microscopy resolves sub-39 nm structures

Best resolutions in X-ray focusing are obtained to date by using diffractive lenses called Fresnel zone plates (FZPs). Their further improvement is nevertheless hindered by fundamental limitations in the employed manufacturing techniques. Here, we show a novel method to fabricate FZPs based on multilayer deposition with atomic layer deposition (ALD) and subsequent sectioning with focused ion beam (FIB). For the first time a multilayer FZP working in the soft X-ray range was prepared and could achieve the best resolution obtained so far for multilayer FZPs by resolving features below 39nm in size in a scanning soft X-ray microscope. The new technique presents high potential for high resolution microscopy in both the soft and hard X-ray range.

Iridium wire grid polarizer fabricated using atomic layer deposition

In this work, an effective multistep process toward fabrication of an iridium wire grid polarizer for UV applications involving a frequency doubling process based on ultrafast electron beam lithography and atomic layer deposition is presented. The choice of iridium as grating material is based on its good optical properties and a superior oxidation resistance. Furthermore, atomic layer deposition of iridium allows a precise adjustment of the structural parameters of the grating much better than other deposition techniques like sputtering for example. At the target wavelength of 250 nm, a transmission of about 45% and an extinction ratio of 87 are achieved.

High spatial resolution analysis of fungal cell biochemistry – bridging the analytical gap using synchrotron FTIR spectromicroscopy

Fungi impact humans and the environment in many ways, for good and ill. Some fungi support the growth of terrestrial plants or are used in biotechnology, and yet others are established or emerging pathogens. In some cases, the same organism may play different roles depending on the context or the circumstance. A better understanding of the relationship between fungal biochemical composition as related to the fungal growth environment is essential if we are to support or control their activities. Synchrotron FTIR (sFTIR) spectromicroscopy of fungal hyphae is a major new tool for exploring cell composition at a high spatial resolution. Brilliant synchrotron light is essential for this analysis due to the small size of fungal hyphae. sFTIR biochemical characterization of subcellular variation in hyphal composition will allow detailed exploration of fungal responses to experimental treatments and to environmental factors.

Influence of the oxygen plasma parameters on the atomic layer deposition of titanium dioxide

The influence of the oxygen plasma parameters on the morphology and optical properties of TiO2 thin films has been extensively analyzed in plasma enhanced atomic layer deposition (PEALD) processes. Crystalline aggregates with the anatase phase have been identified on the film surface at a low deposition temperature (down to 70 °C) under specific plasma conditions. Up to 70% surface coverage by anatase crystallites is obtained at low oxygen gas flow rates and high plasma power. The hillocks abundance is correlated with high ion flux and electron density and with the resulting enhanced ion bombardment of the surface. Altering the plasma conditions is an important parameter besides temperature to control the morphology of the titania film for specific applications such as photocatalysis or functional optical coatings. Specifically, photocatalytic titania coatings on polymer substrates could benefit of such low temperature PEALD processes with abundant anatase crystallites; whereas optical coatings require smooth, high refractive index titania as obtained with low plasma power and high oxygen flow rate.

Stability and annealing of alucones and alucone alloys

Hybrid organic–inorganic alucone films have been deposited using trimethylaluminum and ethylene glycol by molecular layer deposition (MLD). The stability of the coatings was monitored in ambient as well as in dry air. Alloys have also been deposited using alucone and Al2O3. The effect of thermal annealing as a function of the Al2O3 content was assessed. The stability and morphology of such organic–inorganic alloys are finely tuned by their composition. The alucones and alucone/Al2O3 alloys with the ratio of 5 cycles to 1 cycle resulted in a compact layer after thermal treatment, whereas the 1:1 composite showed numerous cracks. Slow thermal annealing at the rate of 10 °C/h of the 5:1 alloy leads to the decrease of refractive index from n = 1.52 to n = 1.34 with a thickness loss of ∼28%. Fast heating rate of 120 °C/h results in a larger thickness loss of ∼37% and the development of a more dense film with an effective refractive index of n = 1.40. The slow thermal annealing facilitates the formation of larg...

Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

The fabrication and performance of multilayer Al2O3/Ta2O5 Fresnel zone plates in the hard X-ray range and a discussion of possible future developments considering available materials are reported.

All dielectric hard x-ray mirror by atomic layer deposition

Mirrors consisting of Al2O3 and Ta2O5 (∼2 nm film thickness) nanolaminates for hard x-ray wavelengths were produced by atomic layer deposition and characterized. Atomic force microscopy and transmission electron microscopy (TEM) proved extremely smooth surfaces of the mirrors, which are critical for highest reflectance. TEM images showed sharp interfaces between the oxides. The experimental x-ray reflectivity data were theoretically modeled and indicated minimal random thickness variations in the individual layers. Additionally, a depth graded sample with a total thickness of ∼4 μm for focusing applications in transmission (Laue) geometry and capillaries was coated.