Climate Change Effects on Volcanoes in the Tropics: A review of the deglaciation of Antisana and its effects on subsequent water streams and rivers over 20 years

Located in the Northern end of Ecuador lies the stunning glacier of Antisana which attracts many tourists and whose runoff provides a significant amount of water supply for Quito. Climate change is posing threats to many ecosystems world wide but will have a more substantial impact on the volcanoes in the tropics because they do not have a seasonally altered climate. Small changes in the air temperature can have larger impacts on these areas that are adapted to constant temperatures with seasonal precipitation changes. Climate change, in recent years, had caused an increase in the glacial retreat of the Antisana volcano. This increase in melt and deglaciation has further implications for the Quito’s water supply, the surrounding ecosystem of the glacier and subglacial run-off areas, and can impact the quality of water run-off from the Antisana Glacier. This study examines the implications of the melt from the glacier by providing a meta-analysis about the flow of subsequent streams, impacts on water resources for nearby cities, a makeup of environmental impacts from the viewpoint of macroinvertebrate sampling, and a review of the deglaciation from a review of articles and investigation into satellite imagery. The results from this study did not have any significant findings about the retreat of the Antisana glacier in relation to the impact on surrounding ecosystems and water resources for the nearby city of Quito. Situado en el extremo norte de Ecuador se encuentra el glaciar impresionante de Antisana que atrae a muchos turistas y cuya escorrentía proporciona una cantidad significativa de suministro de agua para Quito. El cambio climático está planteando amenazas para muchos ecosistemas en todo el mundo, pero tendrá un impacto más sustancial de los volcanes en los trópicos porque no tienen un clima alterado estacionalmente. Pequeños cambios en la temperatura del aire pueden tener impactos mayores en estas áreas que se adaptan a temperaturas constantes con cambios de precipitación estacionales. El ca mbio climático, en los últimos años, había causado un aumento en el retiro glaciar del volcán Antisana. Este aumento de la fusión y la desglaciación tiene otras implicaciones para el suministro de agua de Quito, el ecosistema circundante del glaciar y las zonas de escorrentimiento subglaciales, y puede afectar la calidad de la escorrentía de agua del glaciar Antisana. Este estudio examina las implicaciones de la fusión desde el glaciar proporcionando un metaanálisis sobre el flujo de corrientes posteriores, impactos en los recursos hídricos para ciudades cercanas, una composición de los impactos ambientales desde el punto de vista del muestreo de macroinvertebrados, y una revisión de la desglaciación a partir de una revisión de artículos e investigación sobre imágenes satelitales. Los resultados de este estudio no tuvieron hallazgos significativos sobre la retirada del glaciar Antisana en relación con el impacto en los ecosistemas circundantes y los recursos hídricos para la ciudad cercana de Quito

Development of technique for AR coating and nickel and copper metallization of solar cells: FPS project, product development

Silicon nitride and nickel pastes are investigated in conjunction with a brush copper plating process for the purpose of identifying one or more fabrication sequences which yield at least 10 percent efficient N(+)/P(+) flat plate solar cells. The adhesion of all nickel pastes is reduced significantly when subjected to acidic and alkaline brush copper plating solutions as a result of a combination of thermally induced stress and chemical attack of the frit, which occurs at the interface with the silicon solar cell. The AgF is penetrating the 800 a of Si3N4 and ohmic contact is occurring at all fire-in tempertures. During the brush plating process, fingers and buss bars tend to spread

Host‐Guest Chemistry of Truncated Tetrahedral Imine Cages with Ammonium Ions

Three shape-persistent [4+4] imine cages with truncated tetrahedral geometry with different window sizes were studied as hosts for the encapsulation of tetra-n-alkylammonium salts of various bulkiness. In various solvents the cages behave differently. For instance, in dichloromethane the cage with smallest window size takes up NEt$_{4}$t$^{+}$ but not NMe$_{4}$t$^{+}$, which is in contrast to the two cages with larger windows hosting both ions. To find out the reason for this, kinetic experiments were carried out to determine the velocity of uptake but also to deduce the activation barriers for these processes. To support the experimental results, calculations for the guest uptakes have been performed by molecular mechanics’ simulations. Finally, the complexation of pharmaceutical interested compounds, such as acetylcholine, muscarine or denatonium have been determined by NMR experiments

Effects of Added Vegetation on Sand Bar Stability and Stream Hydrodynamics

Vegetation was added to a fully developed sandy point bar in the meander of a constructed stream. Significant changes in the flow structure and bed topography were observed. As expected, the addition of vegetative resistance decreased the depth-averaged streamwise velocity over the bar and increased it in the open region. In addition, the secondary circulation increased in strength but became confined to the deepest section of the channel. Over the point bar, the secondary flow was entirely outward, i.e., toward the outer bank. The changes in flow led to changes in bar shape. Although the region of the bar closest to the inner bank accumulated sediment, erosion of the bar and the removal of plants by scouring were observed at the interface between the planted bar and the open channel.National Science Foundation (U.S.) (Grant No. EAR 0738352

The propargyl rearrangement to functionalised allyl-boron and borocation compounds

A diverse range of Lewis acidic alkyl, vinyl and aryl boranes and borenium compounds that are capable of new carbon–carbon bond formation through selective migratory group transfer have been synthesised. Utilising a series of heteroleptic boranes [PhB(C6F5)2 (1), PhCH2CH2B(C6F5)2 (2), and E-B(C6F5)2(C6F5)C=C(I)R (R=Ph 3 a, nBu 3 b)] and borenium cations [phenylquinolatoborenium cation ([QOBPh][AlCl4], 4)], it has been shown that these boron-based compounds are capable of producing novel allyl- boron and boronium compounds through complex rearrangement reactions with various propargyl esters and carbamates. These reactions yield highly functionalised, synthetically useful boron substituted organic compounds with substantial molecular complexity in a one-pot reaction

Homogeneous and heterogenised new gold C-scorpionate complexes as catalysts for cyclohexane oxidation

Gold(III) complexes of type [AuCl2{eta(2)-RC(R'pz)(3)}]Cl [R = R' = H (1), R = CH2OH, R' = H (2) and R = H, R' = 3,5-Me-2(3), pz = pyrazol-1-yl] were supported on carbon materials (activated carbon, carbon xerogel and carbon nanotubes) and used for the oxidation of cyclohexane to cyclohexanol and cyclohexanone, with aqueous H2O2, under mild conditions

Forecasting the Pharmacokinetics With Limited Early Frames in Dynamic Brain PET Imaging Using Neural Ordinary Differential Equation

In dynamic brain positron emission tomography (PET) studies, acquiring a time series of images, typically lasting more than an hour, is necessary to derive pharmacokinetic parameters. Analytically, these parameters are estimated by establishing kinetic models such as compartment models that consist of sets of ordinary differential equations (ODE), and by fitting the sparse time-activity curve (TAC) of the tracer. Yet, these models are simplified approximations of highly complex underlying processes, and sufficient samples of TAC are required throughout the entire acquisition, which is not only impractical but also hindered by patient involuntary motion and intrinsic noise. Therefore, recovering samples in missing timeframes is often required, which, in practice, is achieved by interpolation or extrapolation. Here, we introduce a novel deep-learning-based method that utilizes neural ODE (N-ODE) to predict TAC in the extended timeframes by mimicking analytical method in a data-driven manner. By training N-ODE to solve and fit sets of ODE such that the solution replicates the observed TAC, the N-ODE converges to the functional shapes that best describe the underlying pharmacokinetic processes. We customized N-ODE to predict the full-dynamic images (12 frames, 60min), hence pharmacokinetic parameters, given limited early-frame images (7 to 9 frames, 20 to 30min). For proof of concept, the proposed N-ODE was applied to simulated and clinical 18F-PI-2620 brain PET. We demonstrated that the proposed N-ODE delivered promising performance, indicated by bias, variance, and mean absolute error as well as pharmacokinetic parameters such as rate constants, standardized uptake value ratio (SUVr), and binding potential (BPND)

Correlation of Perfusion MRI and F-18-FDG PET Imaging Biomarkers for Monitoring Regorafenib Therapy in Experimental Colon Carcinomas with Immunohistochemical Validation

Objectives To investigate a multimodal, multiparametric perfusion MRI/F-18-fluoro-deoxyglucose (F-18-FDG)-PET imaging protocol for monitoring regorafenib therapy effects on experimental colorectal adenocarcinomas in rats with immunohistochemical validation. Materials and Methods Human colorectal adenocarcinoma xenografts (HT-29) were implanted subcutaneously in n = 17 (n = 10 therapy group;n = 7 control group) female athymic nude rats (Hsd: RH-Foxn1(mu)). Animals were imaged at baseline and after a one-week daily treatment protocol with regorafenib (10 mg/kg bodyweight) using a multimodal, multiparametric perfusion MRI/F-18-FDG-PET imaging protocol. In perfusion MRI, quantitative parameters of plasma flow (PF, mL/100 mL/min), plasma volume (PV,%) and endothelial permeability-surface area product (PS, mL/100 mL/min) were calculated. In F-18-FDG-PET, tumor-to-background-ratio (TTB) was calculated. Perfusion MRI parameters were correlated with TTB and immunohistochemical assessments of tumor microvascular density (CD-31) and cell proliferation (Ki-67). Results Regorafenib significantly (p<0.01) suppressed PF (81.1 +/- 7.5 to 50.6 +/- 16.0 mL/100mL/min), PV (12.1 +/- 3.6 to 7.5 +/- 1.6%) and PS (13.6 +/- 3.2 to 7.9 +/- 2.3 mL/100mL/min) as well as TTB (3.4 +/- 0.6 to 1.9 +/- 1.1) between baseline and day 7. Immunohistochemistry revealed significantly (p<0.03) lower tumor microvascular density (CD-31, 7.0 +/- 2.4 vs. 16.1 +/- 5.9) and tumor cell proliferation (Ki-67, 434.0 +/- 62.9 vs. 663.0 +/- 98.3) in the therapy group. Perfusion MRI parameters Delta PF, Delta PV and Delta PS showed strong and significant (r = 0.67-0.78;p<0.01) correlations to the PET parameter Delta TTB and significant correlations (r = 0.57-0.67;p<0.03) to immunohistochemical Ki-67 as well as to CD-31-stainings (r = 0.49-0.55;p<0.05). Conclusions A multimodal, multiparametric perfusion MRI/PET imaging protocol allowed for non-invasive monitoring of regorafenib therapy effects on experimental colorectal adenocarcinomas in vivo with significant correlations between perfusion MRI parameters and F-18-FDG-PET validated by immunohistochemistry