38 research outputs found
Sonodegradation of Amitriptyline and Ibuprofen In the Presence of MXENE
Environmental pollution has intensified and accelerated due to a steady increase in the number of industries, and finding methods to remove hazardous contaminants, which can be typically divided into inorganic and organic compounds, have become inevitable. One of the widely used water treatment technologies is adsorption and various kinds of adsorbents for the removal of inorganic and organic contaminants from water have been discovered. Recently, MXene, as an emerging nanomaterial, has gained rapid attention owing to its unique characteristics and various applicability. Particularly, in the area of adsorptive application, MXene and MXene-based adsorbents have shown great potential in a large number of studies. In this regard, a comprehensive understanding of the adsorptive behavior of MXene-based nanomaterials is necessary in order to explain how they remove inorganic and organic contaminants in water. Additionally, to investigate the synergism of ultrasonication and MXene, sonodegradation of selected pharmaceuticals, amitriptyline and ibuprofen, with MXene was carried out in water source. To investigate practicality of the degradation process, the experiments were conducted in various water quality conditions, including pH, temperature, natural organic matter (NOM), and ionic strength. And, to confirm the importance of hydroxyl radicals, the effect of hydroxyl radical promoter (H2O2) and scavenger (t-BuOH) was also studied. In addition, the synergetic indices were calculated with the rate constants of ultrasonication (US) only, MXene only, and a US/MXene combined system. Overall, utilization of MXene by means of ultrasonication could enhance the removal performance of PhACs in water
Source-free Subject Adaptation for EEG-based Visual Recognition
This paper focuses on subject adaptation for EEG-based visual recognition. It
aims at building a visual stimuli recognition system customized for the target
subject whose EEG samples are limited, by transferring knowledge from abundant
data of source subjects. Existing approaches consider the scenario that samples
of source subjects are accessible during training. However, it is often
infeasible and problematic to access personal biological data like EEG signals
due to privacy issues. In this paper, we introduce a novel and practical
problem setup, namely source-free subject adaptation, where the source subject
data are unavailable and only the pre-trained model parameters are provided for
subject adaptation. To tackle this challenging problem, we propose
classifier-based data generation to simulate EEG samples from source subjects
using classifier responses. Using the generated samples and target subject
data, we perform subject-independent feature learning to exploit the common
knowledge shared across different subjects. Notably, our framework is
generalizable and can adopt any subject-independent learning method. In the
experiments on the EEG-ImageNet40 benchmark, our model brings consistent
improvements regardless of the choice of subject-independent learning. Also,
our method shows promising performance, recording top-1 test accuracy of 74.6%
under the 5-shot setting even without relying on source data. Our code can be
found at
https://github.com/DeepBCI/Deep-BCI/tree/master/1_Intelligent_BCI/Source_Free_Subject_Adaptation_for_EEG.Comment: Accepted by the 11th IEEE International Winter Conference on
Brain-Computer Interface (BCI 2023). Code is available at
https://github.com/DeepBCI/Deep-BC
DropBP: Accelerating Fine-Tuning of Large Language Models by Dropping Backward Propagation
Training deep neural networks typically involves substantial computational
costs during both forward and backward propagation. The conventional layer
dropping techniques drop certain layers during training for reducing the
computations burden. However, dropping layers during forward propagation
adversely affects the training process by degrading accuracy. In this paper, we
propose Dropping Backward Propagation (DropBP), a novel approach designed to
reduce computational costs while maintaining accuracy. DropBP randomly drops
layers during the backward propagation, which does not deviate forward
propagation. Moreover, DropBP calculates the sensitivity of each layer to
assign appropriate drop rate, thereby stabilizing the training process. DropBP
is designed to enhance the efficiency of the training process with
backpropagation, thereby enabling the acceleration of both full fine-tuning and
parameter-efficient fine-tuning using backpropagation. Specifically, utilizing
DropBP in QLoRA reduces training time by 44%, increases the convergence speed
to the identical loss level by 1.5, and enables training with a
6.2 larger sequence length on a single NVIDIA-A100 80GiB GPU in
LLaMA2-70B. The code is available at https://github.com/WooSunghyeon/dropbp
Amine???Rich Hydrogels Enhance Solar Water Oxidation via Boosting Proton???Coupled Electron Transfer
Photoelectrochemical (PEC) water oxidation is a highly challenging task that acts as a bottleneck for efficient solar hydrogen production. It is because each cycle of water oxidation is composed of four proton-coupled electron transfer (PCET) processes and conventional photoanodes and cocatalysts have limited roles in enhancing the charge separation and storage rather than in enhancing catalytic activity. In this study, a simple and generally applicable strategy to improve the PEC performance of water oxidation photoanodes through their modification with polyethyleneimine (PEI) hydrogel is reported. The rich amine groups of PEI not only allow the facile and stable modification of photoanodes by crosslinking but also contribute to improving the kinetics of PEC water oxidation by boosting the PCET. Consequently, the PEC performance of various photoanodes, such as BiVO4, Fe2O3, and TiO2, is significantly enhanced in terms of photocurrent densities and onset potentials even in the presence of notable cocatalyst, cobalt phosphate. The present study provides new insights into and strategies for the design of efficient photoelectrodes and PEC devices
Prognostic Implication of Longitudinal Changes of Left Ventricular Global Strain After Chemotherapy in Cardiac Light Chain Amyloidosis
AimCardiac involvement is the main prognostic determinant in AL amyloidosis. We sought to determine the prognostic significance of longitudinal change of left ventricular (LV) global longitudinal strain (GLS) in cardiac light chain (AL) amyloidosis patients undergoing chemotherapy.Methods and ResultWe retrospectively investigated 117 cardiac AL amyloidosis patients who underwent chemotherapy from 2005 to 2019. All patients underwent comprehensive 2D conventional transthoracic echocardiography at baseline and after completion of first-line chemotherapy. Speckle tracking analysis of images was performed offline. Absolute value of LV GLS was expressed as [LV GLS] and change of [LV GLS] after chemotherapy was expressed as Δ [LV GLS]. Clinical outcomes including cardiac response and all-cause mortality were analyzed.Baseline clinical and echocardiographic parameters were similar in patients with and without CR. Δ [LV GLS] significantly differed between the CR and non-CR groups (0.4 ± 2.8% in the CR group vs. −0.6 ± 2.5% in the non-CR group, P-value = 0.046). Δ [LV GLS] showed satisfactory predictive performance for all-cause mortality (cut-off value = 0.8%, AUC 0.643, 95% CI [0.537–0.748]). Adding Δ [LV GLS] to the Mayo stage + pre-chemotherapy [LV GLS] model showed incremental prognostic value (C-index: 0.637 vs. 0.708; Relative Integrated Discrimination Index 0.07, P-value = 0.003; Net Reclassification Improvement 0.54, P-value < 0.001). Δ [LV GLS] showed good correlation with cardiac response (AUC 0.820, 95% CI [0.737–0.904]).ConclusionIn cardiac amyloidosis patients who underwent chemotherapy, longitudinal change of [LV GLS] after chemotherapy showed significant association with overall survival as well as cardiac response
Sonodegradation of amitriptyline and ibuprofen in the presence of Ti3C2Tx MXene
This study, which investigated the sonodegradation of selected pharmaceutical active compounds (PhACs) (amitriptyline (AMT) and ibuprofen (IBP)) with MXene, was carried out in an aqueous solution. To investigate the practicality of the degradation process, the experiments were conducted in various water quality conditions, including pH, temperature, natural organic matter, and ionic strength. Based on the experimental results, the produced hydrogen peroxide, which could be a representative of the produced OH radicals, was a vital factor that affected the degradation performance of both PhACs. To confirm the importance of OH radicals, the effect of a OH radical promoter (H2O2) and scavenger (t-BuOH) was also studied. In addition, the synergism between ultrasonication (US) and MXene was evaluated with the rate constants of US only, MXene only, and a US/MXene combined system. Mineralization of the PhACs was also investigated, and removal of AMT was higher than that of IBP, which could be attributed to the physicochemical properties of the compounds and enhanced adsorption by the well-dispersed MXene. Overall, utilization of MXene by means of ultrasonication could enhance the removal performance of PhACs in water
Tensile–Shear Fracture Behavior Prediction of High-Strength Steel Laser Overlap Welds
A wider interface bead width is required for laser overlap welding by increasing the strength of the base material (BM) because the strength difference between the weld metal (WM) and the BM decreases. An insufficient interface bead width leads to interface fracturing rather than to the fracture of the BM and heat-affected zone (HAZ) during a tensile–shear test. An analytic model was developed to predict the tensile–shear fracture location without destructive testing. The model estimated the hardness of the WM and HAZ by using information such as the chemical composition and tensile strength of the BM provided by the steel makers. The strength of the weldments was calculated from the estimated hardness. The developed model considered overlap weldments with similar and dissimilar material combinations of various steel grades from 590 to 1500 MPa. The critical interface bead width for avoiding interface fracturing was suggested with an accuracy higher than 90%. Under all the experimental conditions, a bead width that was only 5% larger than the calculated value could prevent the fracture of the interface
Influence of Coagulation bath temperature on Cross-sectional shapes and tensile properties of PAN fibers
1. Introduction
Recently, many researches have been conducted on changing morphologies of fibers by controlling various process parameters. In this experiment, we manufactured the flat cross-sectional shapes of polyacrylonitrile (PAN) precursor fibers for carbon fibers with high tensile properties to fabricate thin carbon fiber papers. The coagulation bath temperature was set as a process parameter to observe how it affects the morphology and mechanical properties of PAN fibers.
2. Experimental
2.1 Fiber processing
We prepared the spinning dope solution by dissolving poly(acrylonitrile-co-methacrylic acid) (Poly(AN-co-MAA)) into dimethylformamide (DMF) and then spun with dry-jet spinning method. The mixture solvent of methanol and DMF was used as a coagulant. To observe the influence of the coagulation bath temperature on the cross-sectional shape of PAN fibers, we set the range of temperature from -10 to 30 ???. After spinning, the post-drawing process were progressed.
2.2 Characterization
The cross-sectional shapes of post-drawn PAN fibers were investigated by SEM. The tensile properties were measured by single filament tensile testing (FAVIMAT+).
3. Results and Discussion
SEM images of cross-sectional shapes of PAN fibers according to the coagulation bath temperature are shown in Fig. 1. As the temperature decreased, the roundness of the fibers was decreased. This phenomenon was due to the changes of solvent-nonsolvent exchange rate between polymer solutions and coagulant. At low temperature of coagulation bath, the diffusion rate of the solvent out of the polymer solution were predominated, resulting in slow coagulation. Therefore, the cross-sectional shapes became non-circular and the density of fibers were higher [1, 2]. When we measured the tensile properties, the strength at 30 ??? had the lowest value due to faster coagulation which allowed the skin-core structure to form more easily.
4. Conclusions
We observed the influence of the coagulation bath temperature on cross-sectional shapes and the tensile properties of PAN fibers. As the temperature were decreased, the cross-sectional shape became flat and the tensile strength was increased due to the slow coagulation. In order to manufacture the carbon fiber, the heat treatment process will be conducted. Once the conditions of heat treatment are optimized, it can be used in more various applications as well as carbon fiber papers