An Experimental Study on Thermal Stability of Biodiesel Fuel

Biodiesel fuel, as renewable energy, has been used in conventional diesel engines in pure form or as biodiesel/diesel blends for many years. However, thermal stability of biodiesel and biodiesel/diesel blends has been minimally explored. Aimed to shorten this gap, thermal stability of biodiesel is investigated at high temperatures. In this study, batch thermal stressing experiments of biodiesel fuel were performed in stainless steel coils at specific temperature and residence time range from 250 to 425 °C and 3 to 63 minutes, respectively. Evidence of different pathways of biodiesel fuel degradation is demonstrated chromatographically. It was found that biodiesel was stable at 275 °C for a residence time of 8 minutes or below, but the cis-trans isomerization reaction was observed at 28 minutes. Along with isomerization, polymerization also took place at 300 °C at 63 minutes. Small molecular weight products were detected at 350 °C at 33 minutes resulting from pyrolysis reactions and at 360 °C for 33 minutes or above, gaseous products were produced. The formed isomers and dimers were not stable, further decomposition of these compounds was observed at high temperatures. These three main reactions and the temperature ranges in which they occurred are: isomerization, 275-400 °C; polymerization (Diels-Alder reaction), 300-425 °C; pyrolysis reaction, The longer residence time and higher temperature resulted in greater decomposition. As the temperature increased to 425 °C, the colorless biodiesel became brownish. After 8 minutes, almost 84% of the original fatty acid methyl esters (FAMEs) disappeared, indicating significant fuel decomposition. A kinetic study was also carried out subsequently to gain better insight into the biodiesel thermal decomposition. A three-lump model was proposed to describe the decomposition mechanism. Based on this mechanism, a reversible first-order reaction kinetic model for the global biodiesel decomposition was shown to adequately describe the experimental data points of the concentrations or the decomposition percentage as a function of time. The forward and reverse rate constants were determined at each temperature for the model. The Arrhenius pre-exponential factors A for k1 and k2 obtained were 1.50 × 10^9 and 257 min-1, and the energies of activation Ea were 126.0 and 46.0 KJ/mol, respective. The high linearity of the Arrhenius plots (R2 \u3e 98%) further validated the rationality of the assumed reversible first-order kinetics to represent the overall biodiesel decomposition. Moreover, a Van\u27t Hoff plot was established, the reaction enthalpy ΔHo for biodiesel thermal decomposition is 80.0 KJ/mol, indicating the overall decomposition is an endothermic reaction

Influences of Teachers, Students and School Climate on Bullying Victimization: Evidence from China

Given the common occurrence of school bullying incidents and high prevalence rates of victimization in China, this study aims to explore the association between multiple school-related predictors and Chinese adolescents’ overall experiences with bullying victimization. Guided by the social-ecological framework for violence prevention, this study integrated different factors involving teachers, students, and school climate into one single research to detect the bullying problem more systematically and holistically. Further, the study applied the data from the 2018 Program for International Student Assessment while utilizing binary logistic regression analyses to perceive anti-bullying variables and their relationships with bullying victimization. The study revealed that teachers’ emotional, instrumental, and informational support other than appraisal support were negatively associated with students’ experiences of being bullied and victimized. The research also indicated that students’ sense of belonging, a cooperative school environment, and classroom disciplinary climate played a buffering role in bullying victimization while competition in school settings adversely increased overall bullying exposure. The results have highlighted the integration of various predictors in influencing multiple social relations and school environments to battle against in-person bullying. The results also have implications for stopping cyberbullying to achieve inclusive school education for all in the post-COVID-19 era

Assessment and Control of a Cavitation-Enabled Therapy for Minimally Invasive Myocardial Reduction

Hypertrophic cardiomyopathy (HCM), which occurs in 1/500 individuals globally can lead to sudden death in adults without prior symptoms. Echocardiography is commonly used to diagnose hypertrophic cardiomyopathy. Current treatment involves invasive and high-risk procedures such as surgery or catheter-based ablation of spetum to potentially prevent left ventricular outflow tract obstruction. A novel technique, called Myocardial Cavitation-Enabled Therapy (MCET), has been proposed as a means to achieve minimally invasive myocardial reduction, i.e. heart tissue ablation. MCET aims to target hypertrophic heart muscle over time without substantial tissue scarring. The treatment employs contrast echocardiography at higher than diagnostic pressure amplitudes to produce scattered microlesions (clusters of dead cells) by cavitating contrast agent microbubbles. The assessment and control of MCET is explored in three different contexts as follows: A computer-aided 3-D quantitative evaluation scheme, for acute studies, is developed to characterize macrolesions (targeted region for treatment) based on histology sections, including lesion size and lesion density. The characterization is based on brightfield and fluorescence histological images as available in acute preclinical studies. The radially symmetric model employed to characterize macrolesion density is feasible for the study using a single focused beam to perform treatment. This methodology provides a volume-oriented, quantity- sensitive therapy evaluation. Results from parametric studies of MCET demonstrate that the quantitative scoring scheme reduces visual scoring ambiguity, overcomes the limitation of traditional visual scoring and works for cases with a large histologically identified lesion count, i.e. has an appropriate dynamic range for evaluating therapeutic applications. The presented results presented here have shown that MCET-induced macrolesions grow radially as the acoustic pressure amplitude increases. Using a swept beam as a new method seems to be able to shorten treatment time. MCET shows great potential as a minimally-invasive myocardial tissue reduction therapy after long-term healing. Chronic studies of 6-week show the maturation of MCET induced microlesions with quantitative results of the fibrotic tissue fraction. And the tissue reduction in a HCM rat model is demonstrated by showing and heart muscle wall shrinkage by about 16%, which is a therapeutically useful magnitude. MCET method can be improved by addition of adjuvant treatment with steroids and hypertension medication to help fibrosis reduction. Further development and refinement in larger animals of MCET treatment for HCM should fill the need for a new clinical treatment option. Feasibility of detection, quantification and localization for microbubble cavitation is investigated for treatment monitoring and controls. A passive cavitation imaging algorithm and variations of this algorithm provide spatial information on the extent of cavitation events. Cavitation sites can be localized with reasonable spatial resolution. The described passive imaging algorithm applies to both systems: Verasonics (an ultrasound research platform) alone transmitting high intensity focused ultrasound (HIFU) and receiving signals with cavitation signatures, and Verasonics only for passive receiving with another HIFU system for therapeutic exposure. The overall therapy-monitoring scheme is able to adequately delineate the spatial location of triggered microbubble dynamics for real-time monitoring of monitoring of microlesion accumulation.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/136970/1/zhuyiy_1.pd

MVP: Meta Visual Prompt Tuning for Few-Shot Remote Sensing Image Scene Classification

Vision Transformer (ViT) models have recently emerged as powerful and versatile models for various visual tasks. Recently, a work called PMF has achieved promising results in few-shot image classification by utilizing pre-trained vision transformer models. However, PMF employs full fine-tuning for learning the downstream tasks, leading to significant overfitting and storage issues, especially in the remote sensing domain. In order to tackle these issues, we turn to the recently proposed parameter-efficient tuning methods, such as VPT, which updates only the newly added prompt parameters while keeping the pre-trained backbone frozen. Inspired by VPT, we propose the Meta Visual Prompt Tuning (MVP) method. Specifically, we integrate the VPT method into the meta-learning framework and tailor it to the remote sensing domain, resulting in an efficient framework for Few-Shot Remote Sensing Scene Classification (FS-RSSC). Furthermore, we introduce a novel data augmentation strategy based on patch embedding recombination to enhance the representation and diversity of scenes for classification purposes. Experiment results on the FS-RSSC benchmark demonstrate the superior performance of the proposed MVP over existing methods in various settings, such as various-way-various-shot, various-way-one-shot, and cross-domain adaptation.Comment: SUBMIT TO IEEE TRANSACTION

Quantitative assessment of damage during MCET: a parametric study in a rodent model

Abstract Background Myocardial cavitation-enabled therapy (MCET) has been proposed as a means to achieve minimally invasive myocardial reduction using ultrasound to produce scattered microlesions by cavitating contrast agent microbubbles. Methods Rats were treated using burst mode focused ultrasound at 1.5 MHz center frequency and varying envelope and pressure amplitudes. Evans blue staining indicated lethal cardiomyocytic injury. A previously developed quantitative scheme, evaluating the histologic treatment results, provides an insightful analysis for MCET treatment parameters. Such include ultrasound exposure amplitude and pulse modulation, contrast agent dose, and infusion rate. Results The quantitative method overcomes the limitation of visual scoring and works for a large dynamic range of treatment impact. Macrolesions are generated as an accumulation of probability driven microlesion formations. Macrolesions grow radially with radii from 0.1 to 1.6 mm as the ultrasound exposure amplitude (peak negative) increases from 2 to 4 MPa. To shorten treatment time, a swept beam was investigated and found to generate an acceptable macrolesion volume of about 40 μL for a single beam position. Conclusions Ultrasound parameters and administration of microbubbles directly influence lesion characteristics such as microlesion density and macrolesion dimension. For lesion generation planning, control of MCET is crucial, especially when targeting larger pre-clinical models.http://deepblue.lib.umich.edu/bitstream/2027.42/115462/1/40349_2015_Article_39.pd

Site-specific identification and quantitation of endogenous SUMO modifications under native conditions.

Small ubiquitin-like modifier (SUMO) modification regulates numerous cellular processes. Unlike ubiquitin, detection of endogenous SUMOylated proteins is limited by the lack of naturally occurring protease sites in the C-terminal tail of SUMO proteins. Proteome-wide detection of SUMOylation sites on target proteins typically requires ectopic expression of mutant SUMOs with introduced tryptic sites. Here, we report a method for proteome-wide, site-level detection of endogenous SUMOylation that uses α-lytic protease, WaLP. WaLP digestion of SUMOylated proteins generates peptides containing SUMO-remnant diglycyl-lysine (KGG) at the site of SUMO modification. Using previously developed immuno-affinity isolation of KGG-containing peptides followed by mass spectrometry, we identified 1209 unique endogenous SUMO modification sites. We also demonstrate the impact of proteasome inhibition on ubiquitin and SUMO-modified proteomes using parallel quantitation of ubiquitylated and SUMOylated peptides. This methodological advancement enables determination of endogenous SUMOylated proteins under completely native conditions

Multi-modal knowledge graph inference via media convergence and logic rule

Media convergence works by processing information from different modalities and applying them to different domains. It is difficult for the conventional knowledge graph to utilise multi-media features because the introduction of a large amount of information from other modalities reduces the effectiveness of representation learning and makes knowledge graph inference less effective. To address the issue, an inference method based on Media Convergence and Rule-guided Joint Inference model (MCRJI) has been proposed. The authors not only converge multi-media features of entities but also introduce logic rules to improve the accuracy and interpretability of link prediction. First, a multi-headed self-attention approach is used to obtain the attention of different media features of entities during semantic synthesis. Second, logic rules of different lengths are mined from knowledge graph to learn new entity representations. Finally, knowledge graph inference is performed based on representing entities that converge multi-media features. Numerous experimental results show that MCRJI outperforms other advanced baselines in using multi-media features and knowledge graph inference, demonstrating that MCRJI provides an excellent approach for knowledge graph inference with converged multi-media features

Analysis of risk factors of postpartum anxiety in women undergoing cesarean section

Objective To explore the incidence and risk factors of postpartum anxiety in women undergoing cesarean section after comprehensive implementation of the second child policy. Methods A total of 154 women undergoing elective cesarean section were selected. Maternal clinical data were collected at preoperative 1 d， postoperative 2 d and 6 weeks. Self-Rating Anxiety Scale （SAS） and Edinburgh Postpartum Depression Scale （EPDS） were investigated at preoperative 1 d and postoperative 6 weeks. All parturients were divided into the anxiety group and normal group according to the SAS score at postoperative 6 weeks. Univariate and multivariate Logistic regression analyses were used to explore the risk factors of postpartum anxiety. Results The activity pain at postoperative 24 h，the time of first offbed activity after operation， the time of catheter removal， the length of hospital stay， maternal total dissatisfaction with postpartum recuperation period （doing the month） were significantly associated with postpartum anxiety （all P < 0.05）. Multivariable logistic regression analysis showed that the total dissatisfaction with postpartum recuperation period （doing the month） （OR=7.741， 95%CI： 3.612-16.591， P < 0.001） was an independent risk factor for postpartum anxiety at 6 weeks after cesarean section. Conclusions The incidence of postpartum anxiety at postoperative 6 weeks is high in women undergoing cesarean section. Increasing maternal satisfaction with postpartum recuperation period can reduce the incidence of postpartum anxiety

Optical Multipath RF Self-Interference Cancellation Based on Phase Modulation for Full-Duplex Communication

Optical multipath RF self-interference cancellation (SIC) based on phase modulation for full-duplex communication is proposed and demonstrated experimentally. Phase modulation is utilized to convert the RF signal into optical domain, in which the time delay tuning, amplitude tuning and phase inversion for multipath RF SIC are completed. The comprehensive theoretical model of the optical multipath RF SIC system is established, and the factors affecting SIC performance including the time delay, amplitude and phase deviations are analyzed. The experimental results verify the feasibility of the proposed scheme for full-duplex communication with the cancellation depth of 26 dB and 28 dB over 100 MHz at central frequency of 6 GHz and 10 GHz, respectively. A figure of merit of the maximum interference to signal of interest ratio is defined to characterize the SOI recovery capability of optical RF SIC system