A study on the relationship between biodegradability enhancement and oxidation of 1,4-dioxane using ozone and hydrogen peroxide

Advanced oxidation involving O₃/H₂O₂ was used to eliminate 1,4-dioxane and to enhance the biodegradability of dioxane-contaminated water. Oxidation experiments were carried out in a bubble column reactor operating in fed-batch. The rate of dioxane removal and enhancement in biodegradability was investigated at hydrogen peroxide to ozone ratios between 0 and 0.6 mol:mol and pH between 5 and 11. A theoretical model was also applied to predict the experimental data and to investigate the effects of dioxane concentration, pH, and H₂O₂ concentration. The model predictions fit the experimental data well and there was a linear correlation between dioxane oxidation and BOD enhancement. At low dioxane concentrations, the oxidation rate was first order and it gradually approached zero order with increasing dioxane concentration. Also, the biodegradability of the solution increased with pH up to about 9 and it stayed constant with further pH increase. Hydrogen peroxide initially enhanced dioxane removal and biodegradability enhancement of the solution. However, at H₂O₂:O₃ ratios greater than about 0.4-0.45 mol:mol, i.e. about 2.90 mM for H₂O₂ concentration, H₂O₂ had negative impacts and resulted in reduced dioxane removal and biodegradability increase.     

Integrated all-optical infrared switchable plasmonic quantum cascade laser

We report a type of infrared switchable plasmonic quantum cascade laser, in which far field light in the midwave infrared (MWIR, 6.1 μm) is modulated by a near field interaction of light in the telecommunications wavelength (1.55 μm). To achieve this all-optical switch, we used cross-polarized bowtie antennas and a centrally located germanium nanoslab. The bowtie antenna squeezes the short wavelength light into the gap region, where the germanium is placed. The perturbation of refractive index of the germanium due to the free carrier absorption produced by short wavelength light changes the optical response of the antenna and the entire laser intensity at 6.1 μm significantly. This device shows a viable method to modulate the far field of a laser through a near field interaction.     

Chemical Vapor Deposition and Atomic Layer Deposition of Coatings for Mechanical Applications

Chemical vapor deposition (CVD) of films and coatings involves the chemical reaction of gases on or near a substrate surface. This deposition method can produce coatings with tightly controlled dimensions and novel structures. Furthermore, the non-line-of-sight-deposition capability of CVD facilitates the coating of complex-shaped mechanical components. Atomic layer deposition (ALD) is also a chemical gas phase thin film deposition technique, but unlike CVD, it utilizes “self-limiting” surface adsorption reactions (chemisorption) to control the thickness of deposited films. This article provides an overview of CVD and ALD, discusses some of their fundamental and practical aspects, and examines their advantages and limitations versus other vapor processing techniques such as physical vapor deposition in regard to coatings for mechanical applications. Finally, site-specific cross-sectional transmission electron microscopy inside the wear track of an ALD ZnO/ZrO₂ 8 bilayers nanolaminate coating determined the mechanisms that control the friction and wear.     

Fusion of magnetometer and gradiometer sensors of MEG in the presence of multiplicative error

Novel neuroimaging techniques have provided unprecedented information on the structure and function of the living human brain. Multimodal fusion of data from different sensors promises to radically improve this understanding, yet optimal methods have not been developed. Here, we demonstrate a novel method for combining multichannel signals. We show how this method can be used to fuse signals from the magnetometer and gradiometer sensors used in magnetoencephalography (MEG), and through extensive experiments using simulation, head phantom and real MEG data, show that it is both robust and accurate. This new approach works by assuming that the lead fields have multiplicative error. The criterion to estimate the error is given within a spatial filter framework such that the estimated power is minimized in the worst case scenario. The method is compared to, and found better than, existing approaches. The closed-form solution and the conditions under which the multiplicative error can be optimally estimated are provided. This novel approach can also be employed for multimodal fusion of other multichannel signals such as MEG and EEG. Although the multiplicative error is estimated based on beamforming, other methods for source analysis can equally be used after the lead-field modification.     

A miniaturized system for spike-triggered intracortical microstimulation in an ambulatory rat

This paper reports on a miniaturized system for spike-triggered intracortical microstimulation (ICMS) in an ambulatory rat. The head-mounted microdevice comprises a previously developed application-specific integrated circuit fabricated in 0.35-μm two-poly four-metal complementary metal-oxide-semiconductor technology, which is assembled and packaged on a miniature rigid-flex substrate together with a few external components for programming, supply regulation, and wireless operation. The microdevice operates autonomously from a single 1.55-V battery, measures 3.6 cm × 1.3 cm × 0.6 cm, weighs 1.7 g (including the battery), and is capable of stimulating as well as recording the neural response to ICMS in biological experiments with anesthetized laboratory rats. Moreover, it has been interfaced with silicon microelectrodes chronically implanted in the cerebral cortex of an ambulatory rat and successfully delivers electrical stimuli to the second somatosensory area when triggered by neural activity from the rostral forelimb area with a user-adjustable spike-stimulus time delay. The spike-triggered ICMS is further shown to modulate the neuronal firing rate, indicating that it is physiologically effective.     

Developing a Scaling Equation as a Function of Pressure and Temperature to Determine the Amount of Asphaltene Precipitation

A simple and applicable scaling equation as a function of pressure, temperature, molecular weight, dilution ratio (solvent), and weight percent of precipitated asphaltene has been developed. This equation can be used to determine the weight percent of precipitated asphaltene in the presence of difference precipitants (solvents) and the amount of solvent at onset point. Since increasing the pressure of crude oil decreases the amount of asphaltene precipitation, the effect of reservoir pressure has been taken into account in developing this equation. The results obtained by using this equation are substantially different and more accurate from other developed scaling equations for asphaltene precipitation. By considering the effect of reservoir pressure in developing the scaling equation and application of a genetic algorithm, the unknown parameters of the scaling equation are simultaneously and without any reservation obtained. The most important application of this unique equation is in the determination of critical point of asphaltene precipitation, known as onset point, and asphaltene precipitation in gas injection operations for enhanced oil recovery. The results predicted using the scaling equations are compared with the authors' experimental and literature precipitation data and it is shown that they are in good agreement with our experimental data. The scaling equation can be used in the design of gas-injected reservoir to prevent precipitation of the asphaltene aggregates in the reservoir.     

A novel numerical modeling paradigm for bio particle tracing in non-inertial microfluidics devices

Microsystem Technologies - In this work, we report on the design and implementation of a new method for the two dimensional (2D) simulation of rigid spherical particles trajectory which are to be...     

Determination of an unknown radiation term in an inverse problem of heat equation

A linear conduction equation with radiative boundary condition is considered, in which the function representing radiative flux is unknown, and is to be determined from overspecified data. Exact and approximate explicit solutions are presented for the temperature and radiation term. Some uniqueness and stability results are presented. Finally some numerical results will be given.     

A chance-constrained portfolio selection model with random-rough variables

Traditional portfolio selection (PS) models are based on the restrictive assumption that the investors have precise information necessary for decision-making. However, the information available in the financial markets is often uncertain. This uncertainty is primarily the result of unquantifiable, incomplete, imprecise, or vague information. The uncertainty associated with the returns in PS problems can be addressed using random-rough (Ra-Ro) variables. We propose a new PS model where the returns are stochastic variables with rough information. More precisely, we formulate a Ra-Ro mathematical programming model where the returns are represented by Ra-Ro variables and the expected future total return maximized against a given fractile probability level. The resulting change-constrained (CC) formulation of the PS optimization problem is a non-linear programming problem. The proposed solution method transforms the CC model in an equivalent deterministic quadratic programming problem using interval parameters based on optimistic and pessimistic trust levels. As an application of the proposed method and to show its flexibility, we consider a probability maximizing version of the PS problem where the goal is to maximize the probability that the total return is higher than a given reference value. Finally, a numerical example is provided to further elucidate how the solution method works.

     

Assessing the effectiveness of disease awareness programs: Evidence from Google Trends data for the world awareness dates

Objectives

The process of disease awareness distribution on the web was studied. The contribution of WHO world awareness days to the total awareness process over the internet was investigated.