Abnormal metabolic network activity in REM sleep behavior disorder

OBJECTIVE: To determine whether the Parkinson disease-related covariance pattern (PDRP) expression is abnormally increased in idiopathic REM sleep behavior disorder (RBD) and whether increased baseline activity is associated with greater individual risk of subsequent phenoconversion. METHODS: For this cohort study, we recruited 2 groups of RBD and control subjects. Cohort 1 comprised 10 subjects with RBD (63.5 +/- 9.4 years old) and 10 healthy volunteers (62.7 +/- 8.6 years old) who underwent resting-state metabolic brain imaging with (18)F-fluorodeoxyglucose PET. Cohort 2 comprised 17 subjects with RBD (68.9 +/- 4.8 years old) and 17 healthy volunteers (66.6 +/- 6.0 years old) who underwent resting brain perfusion imaging with ethylcysteinate dimer SPECT. The latter group was followed clinically for 4.6 +/- 2.5 years by investigators blinded to the imaging results. PDRP expression was measured in both RBD groups and compared with corresponding control values. RESULTS: PDRP expression was elevated in both groups of subjects with RBD (cohort 1: p \u3c 0.04; cohort 2: p \u3c 0.005). Of the 17 subjects with long-term follow-up, 8 were diagnosed with Parkinson disease or dementia with Lewy bodies; the others did not phenoconvert. For individual subjects with RBD, final phenoconversion status was predicted using a logistical regression model based on PDRP expression and subject age at the time of imaging (r(2) = 0.64, p \u3c 0.0001). CONCLUSIONS: Latent network abnormalities in subjects with idiopathic RBD are associated with a greater likelihood of subsequent phenoconversion to a progressive neurodegenerative syndrome

Exchange of polycyclic aromatic hydrocarbons across the air-water interface in the Bohai and Yellow Seas

In this study, air and surface seawater samples collected from the Bohai (BS) and Yellow Seas (YS) in May 2012 were determined exchange of PAHs, especially of low-molecular-weight (LMW) PAHs (three- and four-ring PAHs) at the air-water interface. Net volatilization fluxes of LMW PAHs were 266-1454 ng/m(2)/d and decreased with distance from the coast, indicating that these PAHs transported from coastal runoff were potential contributors to the atmosphere in the BS and YS. Moreover, LMW PAHs were enriched in the dissolved phase compared with those in the particulate phase in the water column, possibly suggesting that the volatilized LMW PAHs were directly derived from wastewater discharge or petroleum pollution rather than released from contaminated sediments. The air-sea exchange fluxes of the three-ring PAHs were 2- to 20-fold higher than their atmospheric deposition fluxes in the BS and YS. The input to and output from the water reached equilibrium for four-ring PAHs. Differently, five- and six-ring PAHs were introduced into the marine environment primarily through dry and wet deposition, indicating that the water column was still a sink of these PAHs from the surrounding atmosphere. (C) 2016 Elsevier Ltd. All rights reserved

MIP Plasma Decapsulation of Copper-wired Semiconductor Devices for Failure Analysis

The majority of Integrated Circuit (IC) devices are encapsulated in wire-bonded plastic IC packages. Epoxy molding compound is used as the encapsulation material and gold was used as the bonding wire material. However, the increase of gold material price from 400 USD/ounce in year 2005 to 1400 USD/ounce in year 2013 results in a major cost issue in IC assembly and prompt industry to search for alternative bond wire materials. Due to its cost and performance advantages, copper wire bonding is steadily replacing traditional gold wire bonding in IC assembly. The share of copper wire bonding has increased from 1% in year 2007 to 10% in year 2010 and is expected to reach 30% in year 2013. In package level failure analysis, decapsulation is an important step to open the IC package to inspect the condition of internal components and locate possible failure sites for root cause analysis. Thus the requirement of a good decapsulation process is to selectively remove the epoxy molding compound encapsulation layer, while not damaging the semiconductor chip and metal bonding wires that locate inside the IC package. The mostly used conventional decapsulation technique is to use hot nitric or nitric and sulfuric mixture acid to etch away the molding compound, such process has been routinely used for gold wire bonded plastic IC package decapsulation. However, because copper wires are more susceptible to be corroded and damaged by the acid, the switching to copper wire bonding in IC industry has raised a problem for acid decapsulation. Copper bond wires suffer inevitable corrosion after acid decapsulation, thus further failure analysis on copper/aluminum bonding becomes difficult especially in the case of IC packages that went through thermal stressing conditions after quality tests. Conventional plasma decapsulation and laser-ablation also have inherent disadvantages, thus their application in copper-wired IC package decapsulation are limited. In this thesis, we introduce a solution to the copper-wired IC package decapsulation by using a Microwave Induced Plasma (MIP) system. The MIP system combines the high etching selectivity of a plasma with the speed and absence of RF fields of acid decapsulation. Characteristics of the MIP system are high power density, atmospheric pressure operation and absence of exposure of the samples to ions. As a result, fast, selective and safe decapsulation of copper wire bonded IC packages is achieved. The performance of this MIP system outperforms acid decapsulation in preservation of fine surface details on the copper wire bonds. Compared to conventional plasma etchers, the MIP system is at least 20 times faster and does not damage the functionality of the chip. The prototype setup of the MIP decapsulation system is described in Chapter 2. The core component in the MIP system is a Beenakker-type TM010 mode microwave resonant cavity, which is the plasma source that determines the plasma etching performance. Chapter 3 investigates problems when using the original Beenakker cavity as the source of the plasma. Modifications are proposed that enable generation of an atmospheric pressure high-power density stable Ar/O2/CF4 plasma. High power reflection in the MIP system is reduced by adding a variable antenna to the original coupling loop inside the cavity. Broad and stable plasma process window is achieved by adding another modification element that reduces the cavity’s quality factor. The power efficiency of the MIP system is estimated to be 80%, while the volume power density of MIP sustained by the modified Beenakker cavity is 1600 W/cm3 under 40 W input power. Based on the plasma chemistry, MIP afterglow etching recipes for a variety of materials are developed in Chapter 4. Ar/O2/CF4 plasma etching of epoxy molding compound, Si, SiO2, Si3N4, silicone, copper, aluminum, palladium, and gold are conducted. Those materials are of special interest because they are commonly used in semiconductor packages. The optimal recipes for high etching rates as well as the rate-limiting factors of etching each material are given. The results provide reference to plasma etching selectivity and preservation of certain materials during MIP decapsulation of IC packages. Chapter 5 focuses on the application of MIP afterglow etching in IC package decapsulation. Four different MIP decapsulation processes are proposed and their pros & cons are analyzed. These four processes covers all types of plastic IC package decapsulation tasks, including thermally stressed package decapsulation that cannot be handled by other techniques. After MIP afterglow decapsulation, Si3N4 passivation layer, Si die, Cu bond wires, Pd-coated Cu bond wires, Au bond wires, and Al bond pads inside the IC package can be cleanly exposed without any process-induced damage. Comparison of MIP decapsulation with the currently used alternative solution of cold acid decapsulation is made. The superior ability of preserving minute surface features by MIP decapsulation in a reasonable time that facilitates further failure-site analysis is demonstrated through case studies. The application of MIP afterglow etching in LED package decapsulation is explored in Chapter 6. High-power LED packages are cleanly decapsulated by MIP afterglow etching without influencing the functionality of the LED die. Different decapsulation processes for flip-chipped and gold wire-bonded LED packages are developed. Typical decapsulation duration for single LED package is 7 minutes for flip-chipped packages and 12 minutes for wire-bonded packages, which is at least 10 times shorter than conventional wet etching alternatives. The business development of the MIP system is described in Chapter 7. A review of the milestones in both scientific research and business development are given to show how both matter progressed together. Experiences and thoughts are shared which hopefully could be a reference for entrepreneurs in scientific world.Microelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc

Auto Tuning Reset Control Design and Application on the Precision Positioning Stage

Mechanical, Maritime and Materials EngineeringDelft Center for Systems and ControlMaster Mechanical Engineerin

The Effect of Oil on Foam for Enhanced Oil Recovery: Theory and Measurements

Foam has unique microstructure in pore networks and reduces gas mobility significantly, which improves considerably the sweep efficiency of gas injection. Foam injection is thus regarded as a promising enhanced oil recovery (EOR) technology. One key to success of foam EOR is foam stability in presence of oil. This thesis seeks to understand fundamentally both steady-state and transient foam flow with oil in porous media through theoretical analysis and coreflood measurements. A quantitative modeling study is conducted to illustrate how the two algorithms ("wet-foam" model and "dry-out" model) represent the effect of oil on foam. Experimental observations evidently show that the two foam regimes without oil also apply to foam with oil, i.e. high- and low-quality regimes depending on foam quality. Oil affects both regimes with a stronger effect on the high-quality regime. Model fitting to data shows that currently applied implicit-texture (IT) foam models are suitable to represent foam flow with oil; both wet-foam model and dry-out model are needed to describe the effect of the oil on the two foam regimes. Three-phase fractional-flow theory together with the wave curve method (WCM) is applied to understand foam displacements with oil. Theoretical solutions suggest foam displacement cannot bank up an oil bank with oil saturation greater than an upper limit for stable foam. A critical phenomenon, i.e. that some injection conditions correspond to more than one possible foam states as predicted by the IT model, has been analyzed with fractional-flow theory and the WCM. We show how to determine the unique displacing state; the choice of the displacing state depends on initial state. Fundamentally, a boundary curve in ternary saturation space is defined that captures the nature of the dependence of the displacement on initial state. In addition, a new capillary number definition for micromodels is derived from a force balance on a ganglion trapped by capillarity. The definition in particular accounts for the impact of pore geometry and its validity is verified using two-phase flow data in micromodels. Based on current findings, some open questions concerning foam-oil interactions in porous media are defined and summarized at the end of this thesis.Petroleum Engineerin

Semi-Analytical Solution to Buckling of Variable-Stiffness Composite Panels (Plates and Shallow Cylindrical Shells)

Variable-stiffness panels have previously shown enhanced buckling performance compared to constant-stiffness panels, due to the beneficial load and stiffness redistribution. Two semianalytical models based on the Galerkin method and the Ritz method have been developed in order to solve the buckling problem of variable-stiffness composite panels (plates and shallow cylindrical shells). The laminates considered are assumed to be symmetric, which results in zero extensionbending couplings. However, the bending-twisting couplings, D16 and D26, are retained in the model due to their dramatic influence on the convergence of the predicted buckling loads. In the first model the governing equations for composite plates and shallow cylindrical shells with variable stiffness are derived and then solved using the Galerkin method. The variable stiffness in this model is approximated using two-dimensional Fourier series, which, however, appears to be less accurate and less efficient as compared to the Ritz method. The Ritz method avoids using Fourier series to approximate the stiffness. Instead, the stiffness is exactly expressed in the integral of the energy functional. The detailed derivations of the energy functional which were rarely shown in literature have been presented. The buckling analysis of this model comprises two main steps. First, the in-plane loads are calculated by applying the principle of minimum complementary energy in pre-buckling state. Second, the critical buckling loads are determined from the stability equations which are obtained from the total energy functional through applying either adjacent equilibrium criterion or the principle of minimum potential energy. The total energy functional for stability analysis in this model is expressed in terms of out-of-plane displacement and the Airy stress function, which appears to be a combination of negative membrane complementary energy, bending strain energy and external work. In order to ensure fast convergence, several shape functions used in Ritz method were investigated. The in-plane loads were approximated either using the beam characteristic function or polynomial function that were orthogonalized by the Gram-Schmidt process. In addition, the predictions of in-plane loads using sine and cosine function that do not satisfy the boundary conditions of in-plane loads were significantly improved by using Lagrange multiplier method. The out-of-plane displacement was approximated using either sine function or orthogonalized polynomials. The influence of the shape functions on the convergence of the predicted buckling load was analysed and discussed for different examples. These examples included plates and shells with either constant-stiffness or variable stiffness, within which D16 and D26 were either zero or non-zero. The boundary conditions considered for these examples were four-edge simply-supported in current thesis. However, the developed model can be easily extended to consider other boundary conditions. The model can solve the buckling problem of variable-stiffness panels under prescribed inplane loads (¯Nx, ¯Ny, ¯Nxy) or prescribed in-plane displacements (¯u, ¯v). In the current thesis, only the prescribed loads ¯Nx, ¯Nxy and the prescribed end-shortenings ¯u have been investigated and compared to Abaqus model; all the results satisfactorily match the results of Abaqus models. In addition, the model have been proved to be able to predict the buckling loads of shallow cylindrical shells with variable curvatures.Aerospace structures and computational mechanicsAerospace material and structureAerospace Engineerin

A Practical Real Gas Model in CFD

Polynomial functions are generated to describe real gas properties in computational fluid dynamics (CFD). Two-variable relative least square fitting is applied. In this way the real gas model can be generated fast and easily and the computational time requested is small and precision of the function can be easily adjusted. In this paper this kind of real-gas model is implemented for toluene and super sonic stator nozzle is calculated. The obtained results are compared to the measured ones

High-Lift Low Reynolds Number Aerofoils With Specified Pressure Drop for Ducted Wind Turbine

A new high-lift aerofoil modification for the duct has been developed and will be experimentally tested in a small wind tunnel. Aerofoils for such wind tunnel ducts typically operate in the low Reynolds number range from 2 × 105 to 6 × 105. The effect of a duct and of rotor on power and pressure drop were considered separately in previous studies. This paper focuses on the optimization of aerofoil geometry for a Reynolds number of 3 × 105 taking into account of the presence of a screen, having a pressure drop similar to a real rotor. In particular, the current work concentrates on obtaining high lift, instead of high lift-to-drag ratio. Since high lift is the only desirable feature when modifying an aerofoil for ducts, the factors most related to enhanced high-lift low Reynolds numbers aerofoil performance are investigated. Previous experimental data of a three-dimension aerofoil-shaped duct model are used. Combining these data, and applying the Liebeck type high-lift design philosophy, which is to make use of an optimal pressure recovery with aft loading, variations in thickness, camber, and the shape of leading and trailing edges are analysed through the fully inversed method. The XFOIL 6.99 code was adopted as the analyse tool in this study. With the specified velocity distribution, it is found that an increase of both camber and thickness of the duct leads to an increase in lift coefficient with the presence of the pressure drop. In particular, the thickness increment for the aft part of the aerofoil generates higher lift coefficient. The installation of screen divides the duct into two parts, the duct fore part starts from the leading edge until the screen plane, while the duct aft part includes the screen plane to trailing edge. It is observed from previous experimental data that, with the screen presence, the front stagnation point moves towards the inner part of the duct. Consequently, the pressure coefficient reduces in the front part of the suction side, although the pressure differences, between the upper surface and the lower surface, of the duct fore part enlarges. Decreasing the leading edge radius, in essence, accelerates the airflow around it so that a negative area was created. Building on these results, the modified aerofoil model is fabricated and will be tested in a wind tunnel experiment. The test two-dimension model, with the assumption of symmetrical flow, is composed of an aerofoil and a uniform porous screen to simulate half part of the rotor from centreline. The aerofoil has a chord length of 20 mm and the screen has a length of 130 mm in vertical direction. To find the highest lift coefficient of this 2-dimension model, measurements will be conducted with the varying angle of attack and wind speed. Moreover, to investigate the effect of screen loading onto the configuration, there will be two different screens tested. Since the experiment will be carried out in April 2017 the comparison with the XFOIL 6.99 predictions cannot be provided at present, but will be shown during the symposium.Wind Energ

Time-dependent mechanical and transport behaviors of Callovo-Oxfordian argillite

An experimental study was carried out on the time-dependent mechanical and transport behaviors of the Callovo-Oxfordian (Cox) argillite, the geological barriers for high-level radioactive waste disposal in France. Six coupled one-step creep tests under the same confining pressure 6MPa and different deviatoric stresses were proposed to investigate the effect of deviatoric stress on the evolution of creep deformation and gas permeability in creep process. Another three multi-step creep tests under confining pressure (Pc) of 2, 6 and 12MPa were carried out to investigate the effect of confining pressure (mean stress). The results show that the creep strains can be enhanced by both the deviatoric and mean stress. The mean stress can reduce importantly the permeability of the Cox argillite but the deviatoric stress shows no evident effect. The gas permeability of the Cox argillite keeps decreasing when deviatoric stress is smaller than 84% of its peak strength at confining pressure of 6MPa. The structural anisotropic effect is also discussed according to the experimental results

Highly dispersed Cd cluster supported on TiO2 as an efficient catalyst for CO2 hydrogenation to methanol

The conversion of CO2 with high activity and high selectivity to methanol remains challenging because of both the kinetics and thermodynamics difficulties associated with the chemical reactivity of CO2. Herein, we report a new catalyst of Cd/TiO2 enabling 81% methanol selectivity at 15.8% CO2 conversion with the CH4 selectivity below 0.7%. The combination of experimental and computational studies show that the unique electronic properties of Cd cluster supported on TiO2 are responsible for the high selectivity for CO2 hydrogenation to methanol via a HCOO* pathway realized at the interface catalytic sites.ChemE/Inorganic Systems Engineerin