DETOXIFICATION OF SELECTED CHLORO-ORGANICS BY OXIDATION TECHNIQUE USING CHELATE MODIFIED FENTON REACTION

The use of hydroxyl radical based reaction (Fenton reaction) for the destruction of organic pollutants has been widely reported in the literature. However, the low pH requirement and rapid hydrogen peroxide consumption rate make the application of conventional Fenton reaction difficult for in-situ treatment. In this study, we conducted a modified Fenton reaction by introducing a chelating agent into the reaction system that could prevent Fe(OH)3 (s) precipitation even at a neutral pH condition and reduce the H2O2 consumption rate by controlling the Fe2+ concentration. A chelating agent (mono-chelate or poly-chelate) combines with Fe2+ or Fe3+ to form stable metal-chelate complexes in solution. This decreases the concentration of Fe2+ in the solution so that reactions can be carried for longer contact times. Experimental results (citrate was the chelating agent) for 2,4,6-trichlorophenol (TCP) showed that TCP degradations were greater than 95% after 2.5 h and 24 h reaction times at fixed pH 5 and 6, respectively. For the same reaction time, the normalized chloride formations were 85% at pH 5 and 88% at pH 6. Several other chlorinated organic compounds were also chosen as the model compounds for detoxification studies because of their chemical structures: trichloroethylene (unsaturated hydrocarbon), carbon tetrachloride (highly oxidized compound), 2,2-dichlorobiphenyl, and biphenyl (a dual-aromatic ring structure). Poly-chelating agents (such as polyacrylic acid-PAA) provide multiple Fe2+/Fe3+ binding sites in the modified Fenton reaction for the oxidation of contaminants (2,2-dichlorobiphenyl, and biphenyl) at a neutral pH environment. Numerical simulation based on the kinetic model developed from the well known Fenton reaction and iron-chelate chemistry fits experiment data well for both standard and chelate modified Fenton reactions. In this dissertation, it was proven that both monomeric (citrate) and polymeric (PAA) chelate modified Fenton reactions were effective for dechlorination of carbon tetrachloride from aqueous phase by the superoxide radical anion. On the other hand, PAA (a poly-chelating agent) can also be used for solid surface modification by polymerization of acrylic acid (monomer). The successful degradations of biphenyl and trichloroethylene by the PAA functionalized silica particles/membrane demonstrate the versatile applications of the chelate modified Fenton reaction

Scale-aware Test-time Click Adaptation for Pulmonary Nodule and Mass Segmentation

Pulmonary nodules and masses are crucial imaging features in lung cancer screening that require careful management in clinical diagnosis. Despite the success of deep learning-based medical image segmentation, the robust performance on various sizes of lesions of nodule and mass is still challenging. In this paper, we propose a multi-scale neural network with scale-aware test-time adaptation to address this challenge. Specifically, we introduce an adaptive Scale-aware Test-time Click Adaptation method based on effortlessly obtainable lesion clicks as test-time cues to enhance segmentation performance, particularly for large lesions. The proposed method can be seamlessly integrated into existing networks. Extensive experiments on both open-source and in-house datasets consistently demonstrate the effectiveness of the proposed method over some CNN and Transformer-based segmentation methods. Our code is available at https://github.com/SplinterLi/SaTTCAComment: 11 pages, 3 figures, MICCAI 202

Prospects of gravitational waves in the minimal left-right symmetric model

The left-right symmetric model (LRSM) is a well-motivated framework to restore parity and implement seesaw mechanisms for the tiny neutrino masses at or above the TeV-scale, and has a very rich phenomenology at both the high-energy and high-precision frontiers. In this paper we examine the phase transition and resultant gravitational waves (GWs) in the minimal version of LRSM. Taking into account all the theoretical and experimental constraints on LRSM, we identify the parameter regions with strong first-order phase transition and detectable GWs in the future experiments. It turns out in a sizeable region of the parameter space, GWs can be generated in the phase transition with the strength of $10^{-17}$ to $10^{-12}$ at the frequency of 0.1 to 10 Hz, which can be detected by BBO and DECIGO. Furthermore, GWs in the LRSM favor a relatively light $SU(2)_R$-breaking scalar $H_3^0$, which is largely complementary to the direct searches of a long-lived neutral scalar at the high-energy colliders. It is found that the other heavy scalars and the right-handed neutrinos in the LRSM also play an important part for GW signal production in the phase transition.Comment: 41 pages, 10 figures, 5 tables, added references, improved tex

Time-Delayed Data Informed Reinforcement Learning for Approximate Optimal Tracking Control

This paper proposes a time-delayed data informed reinforcement learning method, referred as incremental adaptive dynamic programming, to learn approximate solutions to optimal tracking control problems (OTCPs) of high-dimensional nonlinear systems. Departing from available solutions to OTCPs, our developed tracking control scheme settles the curse of complexity problem in value function approximation from a decoupled way, circumvents the learning inefficiency regarding varying desired trajectories by avoiding introducing a reference trajectory dynamics into the learning process, and requires neither an accurate nor identified dynamics using time-delayed signals. Specifically, the intractable OTCP of a high-dimensional uncertain system is first converted into multiple manageable sub-OTCPs of low-dimensional incremental subsystems constructed using time-delayed data. Then, the resulting sub-OTCPs are approximately solved by a parallel critic learning structure. The proposed tracking control scheme is developed with rigorous theoretical analysis of system stability and weight convergence, and validated experimentally on a 3-DoF robot manipulator

Design of the Tsinghua Tabletop Kibble Balance

The Kibble balance is a precision instrument for realizing the mass unit, the kilogram, in the new international system of units (SI). In recent years, an important trend for Kibble balance experiments is to go tabletop, in which the instrument's size is notably reduced while retaining a measurement accuracy of $10^{-8}$. In this paper, we report a new design of a tabletop Kibble balance to be built at Tsinghua University. The Tsinghua Kibble balance aims to deliver a compact instrument for robust mass calibrations from 10 g to 1 kg with a targeted measurement accuracy of 50 $\mu$g or less. Some major features of the Tsinghua Kibble balance system, including the design of a new magnet, one-mode measurement scheme, the spring-compensated magnet moving mechanism, and magnetic shielding considerations, are discussed.Comment: 8 pages, 9 figure