Oxidation and phase transitions of epitaxial tin oxide thin films on (012)(1̄012) sapphire

We studied the structural behavior and electrical transport properties of epitaxial α-SnO thin films grown on the (012) α-Al2O3(1̄012) α-Al2O3 (sapphire) substrate. Hall effect measurements revealed that the epitaxial as-deposited SnO film is a p-type semiconductor. In situ x-ray diffraction studies show that the α-SnO phase is metastable and will transform into SnO2SnO2 with the rutile type structure when annealed at high temperatures in air. The onset of this phase transformation was observed to begin approximately at 300 °C during heating. Shortly thereafter, rutile SnO2SnO2 was observed to coexist with α-SnO and intermediate products such as Sn and Sn3O4.Sn3O4. After being annealed at temperatures above 600 °C, the film then fully transformed into the rutile SnO2SnO2 phase. Our results show that the α-SnO to SnO2SnO2 structural transformation proceeds initially by the localized disproportionate redistribution of internal oxygen at low temperature, followed by the transformation of the remaining SnO phase and intermediate phases into SnO2SnO2 via the inward diffusion of external oxygen at higher temperatures. Most of the SnO2SnO2 crystallites nucleate epitaxially on α-SnO with the orientation relationship of (101)SnO2//(001)SnO(101)SnO2//(001)SnO and their growth processes are controlled by the (101)SnO2//(001)SnO(101)SnO2//(001)SnO interfaces, leading to a (101) texture and a laminar grain shape for SnO2.SnO2. The relationship between the electrical transport properties and the structural evolution of the film has also been investigated. © 2001 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70650/2/JAPIAU-89-11-6048-1.pd

Clinical Platelet Lipidomics in Targeted and Untargeted Approach by Liquid Chromatography Coupled to Mass Spectrometry

Platelets are small cellular components of blood with a primary role in hemostasis which in contrary are also responsible for a pathological condition called thrombosis that might results in cardiovascular disease (CAD) such as heart attack and stroke. During the hemostasis, lipids play important roles, especially the fatty acids and their derivatives such as oxylipins which are involved in platelets activation. Therefore, the analysis of platelets lipidomics is particularly interesting and the platelet lipidomic landscape might be considered as a powerful tool for diagnostic and prognostic biomarkers for CAD. The thesis is mainly divided into two parts. Part I involved in liquid chromatography and mass spectrometry (LC-MS) based analytical method developments including 1) the optimization of sample preparation procedure for large-scale clinical lipidomics, 2) the method development for targeted analysis of 3-OH-FAs in biological samples human plasma and platelets, 3) the method development for profiling of branched chain and straight chain saturated fatty acids in different types of biological samples including human plasma, platelets and Staphylococcus aureus, 4) the method development for targeted analysis of oxylipins with microLC coupled with MS and 5) the method development for chiral separation of oxylipins. Part II involved in the application of the developed methods to clinical lipidomics study of CAD patients including 1) investigation of the potential of ACKR3/CXCR7 in regulating thromboinflammatory response through its impact on the platelet lipidome by targeted and untargeted lipidomics analysis, 2) investigation of the platelet lipidome by untargeted approach to highlight the significant changes between acute coronary syndrome (ACS) and chronic coronary syndrome (CCS) patients, 3) investigation of the platelet lipidome of CAD patients by untargeted lipidomics and highlighting significant changes between statin-treated and naïve patients. As a result, an advanced monophasic extraction protocol with methanol/methyl tert-butylether/ isopropanol, MeOH/MTBE/IPA (1.3:1:1, v/v/v) as extraction solvents, bead homogenizer for cell disruption and MeOH/MTBE (1:1, v/v) as reconstitution solvent which provides optimal cellular and subcellular extraction efficiencies for both polar (e.g. acylcarnitines) and apolar lipids (e.g. triglycerides TGs) and several targeted LC-MS methods with selected reaction monitoring (SRM) mode for fatty acids and their derivatives (3-OH-FAs and oxylipins) were reported. Further, the developed methods were successfully applied for the clinical platelets lipidomics studies and some conclusions were made: 1) platelet ACKR3/CXCR7 favors antiplatelet lipids over an atherothrombotic lipidome and regulates thromboinflammation which may offer a novel therapeutic strategy in CAD, 2) Lipids alteration was observed between acute coronary syndrome (ACS) and chronic coronary syndrome (CCS) patients and between CAD patients treated with statin and statin naïve patients

Epitaxial nanocrystalline tin dioxide thin films grown on (0001) sapphire by femtosecond pulsed laser deposition

Nanocrystalline tin dioxide (SnO2)(SnO2) thin films of different thicknesses were fabricated on the (0001) surface of α-Al2O3α-Al2O3 (sapphire) using femtosecond pulsed laser deposition. X-ray diffraction and transmission electron microscopy (TEM) analysis revealed that the microstructure of the films strongly depends on the film thickness. The films with a small thickness (<30 nm) are composed of nanosized columnar (100) oriented grains (3–5 nm in diameter) which grow epitaxially on the substrate with three different in-plane grain orientations. The (101) oriented grains (25 nm in diameter) appear when the film thickness becomes larger than a critical value (about 60 nm). The volume fraction of the (101) grains increases with film thickness. Cross-section TEM studies indicated that the (101) oriented grains nucleate on the top of the (100) oriented nanosized grains and show abnormal grain growth driven by surface energy minimization. As a result, the electrical transport properties are strongly dependent on the film thickness. © 2001 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70608/2/APPLAB-79-5-614-1.pd

Effect of crystal defects on the electrical properties in epitaxial tin dioxide thin films

Epitaxial (101) tin dioxide thin films with thickness ranging from 6 and 100 nm were deposited on the (102) α-Al2O3(101̄2)α-Al2O3 substrate by femtosecond pulsed laser ablation. Due to the lattice and thermal expansion mismatch with the substrate, the SnO2SnO2 film shows interfacial misfit dislocations, antiphase boundaries (APBs), and partial dislocations. The APBs lie along the (01)(1̄01) planes with a displacement of 1/2[101]. The densities of APBs and partial dislocations vary with film thickness, whereas the average spacing of misfit dislocations remains constant. Hall effect measurements showed that both electron concentration and mobility decrease with a reduction in the film thickness, which is ascribed to the scattering of electrons by crystal defects and interfaces and the effect of a native space charge region at the near-surface region of the films. The response of the films to reducing gases was found to depend on the electron concentration of the film and the relative fraction, with respect to film thickness, of material that is depleted of electrons. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70824/2/APPLAB-81-27-5168-1.pd

Tin Oxide Thin Films Grown on the (1012) Sapphire Substrate

Tin oxide thin films were deposited on the R-cut sapphire substrate by the electron-beam evaporation of a ceramic SnO 2 source. X-ray diffraction and transmission electron microscopy studies revealed that the films deposited at lower temperatures were amorphous while those grown at temperatures above 350°C consisted of the α-SnO phase with the PbO type structure. Epitaxial α-SnO films on the R-cut sapphire substrate were obtained when deposited at 600°C. Atomic force microscopy studies showed that films deposited at low temperature have a smooth surface, while epitaxial SnO films deposited at high temperatures (above 600°C) have a relatively rough surface. The atomic mobilities in the films at the various deposition temperatures and the lattice mismatch between the films and the substrates ultimately determine the microstructure and surface mophology. X-ray photoelectron spectroscopy analysis shows that the Sn/O ratios are 52.7/47.6 for the amorphous film deposited at the ambient temperature (∼30°C), 48.8/51.2 for the films deposited at 350°C, and 49.2/50.8 for the epitaxial film deposited at 600°C. Electrical properties were determined by four point probe measurements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46317/1/10832_2004_Article_359256.pd

Elucidation of mechanisms of action of Wei-Sheng-Fang-Yi-Bao-Dan in the treatment of COVID-19 and depression using network pharmacology and molecular docking

Purpose: To investigate the mechanisms of action of Wei-Sheng-Fang-Yi-Bao-Dan (WSFYBD) in the treatment of COVID-19 and depression using network pharmacology and molecular docking. Methods: First, the bioactive components and target genes of WSFYBD were retrieved from TCMSP database. The relevant gene targets of depression and COVID-19 were obtained from databases. The core WSFYBD genes for treatment were separately obtained by determining gene intersection. Cytoscape 3.8.0 software was used to draw the visual interactive networks. STRING database was employed to construct protein-protein interaction networks, while Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were used to determine the function and pathway of target genes via a Bioconductor/R. Finally, AutoDockTools software was employed for molecular docking. Results: A total of 105 potential bio-active components and 35 target genes of WSFYBD for COVID-19 therapy were identified. Also, 1905 GO entries (p &lt; 0.05) and 158 related signal pathways (p &lt; 0.05) for COVID-19 were obtained. Similarly, 114 potential bio-active components of WSFYBD and 127 potential therapeutic targets of depression were identified. Moreover, 1948 GO entries (p &lt; 0.05) and 177 related signal pathways for depression were retrieved (p &lt; 0.05). Docking results showed the main bio-active components were closely bound to the core targets. Conclusion: The mechanisms for treating COVID-19 show that WSFYBD directly acts on SARS-CoV-2 virus to prevent it from entering the host cell, or inhibits virus replication. Secondly, WSFYBD ameliorates depression by acting on key targets that control over-activated cytokines. Therefore, WSFYBD has potentials for the management of COVID-19 and depression