Enhancing Multi-Spectral Fingerprint Sensing for Trace Explosive Molecules with All-Silicon Metasurfaces.

Spectroscopy is a powerful tool to identify the specific fingerprints of analytes in a label-free way. However, conventional sensing methods face unavoidable barriers in analyzing trace-amount target molecules due to the difficulties of enhancing the broadband molecular absorption. Here, we propose a sensing scheme to achieve strong fingerprint absorption based on the angular-scanning strategy on an all-silicon metasurface. By integrating the mid-infrared and terahertz sensing units into a single metasurface, the sensor can efficiently identify 2,4-DNT with high sensitivity. The results reveal that the fingerprint peak in the enhanced fingerprint spectrum is formed by the linked envelope. It exhibits a significant enhancement factor exceeding 64-fold in the terahertz region and more than 55-fold in the mid-infrared region. Particularly, the corresponding identification limit of 2,4-DNT is 1.32 µg cm-2, respectively. Our study will provide a novel research idea in identifying trace-amount explosives and advance practical applications of absorption spectroscopy enhancement identification in civil and military security industries.

A Terahertz Metasurface Sensor Based on Quasi-BIC for Detection of Additives in Infant Formula.

Prohibited additives in infant formula severely affect the health of infants. Terahertz (THz) spectroscopy has enormous application potential in analyte detection due to its rich fingerprint information content. However, there is limited research on the mixtures of multiple analytes. In this study, we propose a split ring metasurface that supports magnetic dipole bound states in the continuum (BIC). By breaking the symmetry, quasi-BIC with a high quality (Q) factor can be generated. Utilizing an angle-scanning strategy, the frequency of the resonance dip can be shifted, resulting in the plotting of an envelope curve which can reflect the molecular fingerprint of the analytes. Two prohibited additives found in infant formula, melamine and vanillin, can be identified in different proportions. Furthermore, a metric similar to the resolution in chromatographic analysis is introduced and calculated to be 0.61, indicating that these two additives can be detected simultaneously. Our research provides a new solution for detecting additives in infant formula.

Evaluation of the effect of intraoperative tropisetron on postoperative rebound pain after brachial plexus block: a randomized controlled trial.

Introduction: Postoperative rebound pain after peripheral nerve block increases patient suffering and delays recovery after surgery. Objectives: We tested whether the 5HT-3 receptor antagonist and α7nAChR agonist tropisetron could prevent postoperative rebound pain. Methods: A total of 115 patients were randomized to receive 5-mg/5-mL tropisetron or the same volume of normal saline. Pain intensity was measured with the numerical rating scale of pain (NRS). Rebound pain was defined as a change from mild pain (NRS ≤ 3) measured in the postanesthesia care unit to severe pain (NRS ≥ 7) within 24 hours after peripheral nerve blockade. Logistic regression was used to identify relevant factors associated with postoperative rebound pain. Results: Tropisetron did not affect the NRS score or the incidence of rebound pain after peripheral nerve block. Logistic regression revealed that preoperative pain, bone surgery, and length of incision were risk factors for postoperative rebound pain, and patient-controlled analgesia was protective against postoperative rebound pain. Conclusion: Tropisetron does not affect the incidence of rebound pain after peripheral nerve block. Patients at high risk of postoperative rebound pain should be identified for appropriate management. Registration site: www.chictr.org.cn (ChiCTR2300069994).

Sub-anesthetic dose of esketamine decreases postoperative opioid self-administration after spine surgery: a retrospective cohort analysis.

The use of intraoperative sub-anesthetic esketamine for postoperative analgesia is controversial. In this study, the impact of sub-anesthetic esketamine on postoperative opioid self-administration was determined. Patients who underwent spinal surgery with patient-controlled analgesia (PCA) from January 2019 to December 2021 were respectively screened for analysis. Postoperative PCA was compared between patients who received a sub-anesthetic esketamine dose and patients who were not treated with esketamine (non-esketamine group) with or without propensity score matching. Negative binomial regression analysis was used to identify factors associated with postoperative PCA. Patients who received intraoperative sub-anesthetic esketamine self-administered less PCA (P = 0.001). Azasetron, esketamine, and dexamethasone lowered the self-administration of PCA (IRR with 95% confidential interval, 0.789 [0.624, 0.993]; 0.581 [0.458, 0.741]; and 0.777 [0.627, 0.959], respectively). Fixation surgery and drinking were risk factors for postoperative PCA (1.737 [1.373, 2.188] and 1.332 [1.032, 1.737] for fixation surgery and drinking, respectively). An intraoperative sub-anesthetic dose of esketamine decreases postoperative opioid self-administration. Azasetron and dexamethasone also decrease postoperative opioid consumption. The study is registered at www.chictr.org.cn (ChiCTR2300068733).

Alleviative effects of quercetin of Botrytis cinerea-induced toxicity in zebrafish (Danio rerio) larvae.

Quercetin is a kind of flavonoid substance extensively existing in the plant, which has antioxidant, anti-inflammatory, and anti-apoptosis effects. It was reported that the higher concentration of spores present in the environment could cause abnormal development in zebrafish larvae. Therefore, this study set out to investigate whether quercetin could reduce the zebrafish larvae damage caused by Botrytis cinerea exposure as well as to examine the molecular basis for this action. The findings demonstrated that 50 µM quercetin improved the developmental dysplasia of zebrafish larvae induced by 102 CFU/mL Botrytis cinerea spore suspension, reduced abnormal apoptosis, enhanced antioxidant system, relieved inflammation, reshaped intestinal morphology and recovered intestinal motility. At the molecular level, quercetin decreased the transcriptional abundance of pro-apoptotic factors (bax, p53, caspase3, and caspase9) and up-regulated the anti-apoptotic gene (bcl-2) expression to reduce apoptosis. Moreover, quercetin enhanced the activities of downstream antioxidant enzymes (SOD and CAT) to clear excess ROS and MDA due to Botrytis cinerea exposure by up-regulating the expression of antioxidant genes (nrf2, ho-1, sod, and cat) in the Keap1-Nrf2 pathway. Additionally, quercetin inhibited the elevation of TNF-α by regulating the gene expression of key targets (jak3, pi3k, pdk1, akt, and ikk2) and the content of major proteins NF-κB (P65) and IκB in the NF-κB pathway. In conclusion, this work enriched the contents of the biological research of Botrytis cinerea and provided a new direction for the drug development and targeted therapy of quercetin.

A Tunable Frequency Selective Rasorber with Broad Passband and Low Transmission Loss at X-Band.

In this paper, we propose a dual-mode frequency selective rasorber (FSR) with tunable transmission and absorption windows at the X-band, which shows a broad passband in each transmission window. The proposed tunable FSR consists of a lossy absorption layer, a lossless transmission layer, and an air gap between them. The top frequency selective surface (FSS) layer is a cross-shaped meandering line with resistors and varactors for tunable absorption, and the bottom layer is a cross-shaped gap with varactors to achieve tunable bandpass. The equivalent circuit model (ECM) is investigated, and the 3D full wave simulation is performed. The results are based on simulations, and the simulation results show that the passband can be tuned from 12 to 8 GHz with an insertion loss between 0.5 and 1.4 dB by sweeping the capacitance of the varactors. The proposed design decreases the chances of detection by adversary devices and assures spectrum-safe communication, thereby creating new avenues for radar stealth and target concealment.

Prognostic value of cancer-associated fibroblasts-related genes in lung adenocarcinoma.

Background: The incidence of lung adenocarcinoma is in the forefront of malignant tumors in the world. The purpose of this study was to investigate the role of cancer-associated fibroblast-related genes (CAFRGs) in the occurrence, diagnosis and development of lung adenocarcinoma. Methods: RNA data and corresponding clinical information of lung adenocarcinoma patients were acquired from The Cancer Genome Atlas (TCGA) database. Consensus clustering was performed to identify different molecular subgroups. The tumor immune states of different subgroups were determined by Estimation of STromal and Immune cells in MAlignant Tumor tissues using Expression data (ESTIMATE; https://bioinformatics.mdanderson.org/estimate/index.html), microenvironment cell populations (MCP)-counter (which can reliably quantify the abundance of eight immune cell populations and two stromal cell populations), and single sample gene set enrichment analysis (ssGSEA) analyses. In order to elucidate the potential mechanism of CAFRGs, functional enrichment analysis including gene ontology (GO), Kyoto Encyclopedia of Genes and Genome (KEGG), and GSEA analysis were performed on the differentially expressed genes (DEGs). Least absolute shrinkage and selection operator (LASSO) algorithm and multivariate Cox regression analysis were used to construct the prognostic risk model, which was verified by lung adenocarcinoma data from Gene Expression Omnibus (GEO) dataset GSE37745. Results: This study identified two molecular subgroups with significant differences in survival. High immunoscore and immune cell infiltration were more common in the subgroup with better prognosis. GO and KEGG analysis showed that DEGs between the two different subgroups were mainly concentrated in the mitotic cell cycle, cell proliferation, vascular development, and humoral immune response, adaptive immune-related pathways. GSEA analysis indicated that RNA degradation and P53 signaling pathway might be related to the increased invasiveness of lung adenocarcinoma. Risk models based on CAFRGs have demonstrated potent potential for predicting lung adenocarcinoma survival and have been validated in validation cohorts. The nomogram combined with risk model and clinical characteristics can predict the prognosis of patients with lung adenocarcinoma. Conclusions: The expression of CAFRGs is related to tumor immune microenvironment (TIME) of lung adenocarcinoma patients, and can predict the prognosis of lung adenocarcinoma patients.

Enhanced Optical Transmission through a Hybrid Bull's Eye Structure Integrated with a Silicon Hemisphere.

In this work, we demonstrate a novel structure that can generate extraordinary optical transmission with a silicon hemisphere placed on a conventional bull's eye structure. There is a single subwavelength aperture surrounded by concentric periodic grooves on a substrate. The extraordinary optical transmission in this work is realized by the coupling of the surface plasmon polaritons in the periodic grooves and the localized electromagnetic field generated by the Mie resonance in the silicon hemisphere. The maximum normalized-to-area transmission peak can reach up to 662 with a decreasing device area and size. The electromagnetic field distribution at different geometry parameters is analyzed to clarify the mechanisms of the work in this paper. Additionally, the use of dielectric material in the aperture can avoid ohmic losses of metal material compared with the conventional one, which may suggest that a wider range of bull's-eye-structure applications is possible.

Review of Atom Chips for Absolute Gravity Sensors.

As a powerful tool in scientific research and industrial technologies, the cold atom absolute gravity sensor (CAGS) based on cold atom interferometry has been proven to be the most promising new generation high-precision absolute gravity sensor. However, large size, heavy weight, and high-power consumption are still the main restriction factors of CAGS being applied for practical applications on mobile platforms. Combined with cold atom chips, it is possible to drastically reduce the complexity, weight, and size of CAGS. In this review, we started from the basic theory of atom chips to chart a clear development path to related technologies. Several related technologies including micro-magnetic traps, micro magneto-optical traps, material selection, fabrication, and packaging methods have been discussed. This review gives an overview of the current developments in a variety of cold atom chips, and some actual CAGS systems based on atom chips are also discussed. We summarize by listing some of the challenges and possible directions for further development in this area.

Developmental toxicity and inflammatory response induced by Botrytis cinerea in zebrafish (Danio rerio) larvae.

Botrytis cinerea can reduce the yield of fruits and vegetables by infecting plants. The conidia produced by Botrytis cinerea can be transmitted to the aquatic environment via air and water, but the effects of Botrytis cinerea on aquatic animals is unknown. In this research, the influence of Botrytis cinerea on the development, inflammation, and apoptosis of zebrafish larvae and the underlying mechanism was evaluated. Results indicated that, compared with the control group, the larvae exposed to 101-103 CFU/mL of Botrytis cinerea spore suspension had a delayed hatching rate, lower head and eye area, shorter body length, and larger yolk sac at 72 h post-fertilization. In addition, the quantitative fluorescence intensity of treated larvae displayed a dose-dependent increase in apoptosis sign, revealing that Botrytis cinerea could generate apoptosis. Subsequently, zebrafish larvae were inflamed after exposure to Botrytis cinerea spore suspension, which was characterized as inflammatory infiltration and macrophage aggregation in the intestine. The enrichment of the pro-inflammatory factor TNF-α activated the NF-κB signaling pathway, generating the increase of the transcription level of target genes (jak3, pi3k, pdk1, akt, and ikk2) and the high expression of major proteins NF-κB (P65) in this pathway. Likewise, elevated content of TNF-α could activate JNK, which turned on the P53 apoptotic pathway, leading to a significant increase in the bax, caspase3, and caspase9 transcript abundances. This study demonstrated that Botrytis cinerea could cause developmental toxicity, morphological malformation, inflammation, and cell apoptosis in zebrafish larvae, which provided data support and a theoretical basis for ecological health risk assessment and filled the gap in biological research of Botrytis cinerea.

A multi-center, randomized, double-blinded, parallel, placebo-controlled study to assess the efficacy and safety of Shenqisuxin granule in complex coronary artery disease after PCI: Study protocol.

Introduction: The Shenqisuxin granule (SQSX), a novel Chinese herbal formula, has the effect of preventing in-stent restenosis and improving angiogenesis. We intend to evaluate the efficacy and safety of SQSX to provide a possible therapeutic strategy for complex coronary artery disease (CCAD) after percutaneous coronary intervention (PCI). Methods/design: The study is a multi-center, randomized, double-blinded, parallel, placebo-controlled trial. A total of 120 participants will be randomized 1:1 into the intervention group and the control group. Based on standardized treatment, the intervention group and control group will receive SQSX and placebo for 2 months, respectively. The primary outcomes, metabolic equivalents (METS) and peak oxygen uptake (Peak VO2), and the secondary outcomes, including other indicators of cardiorespiratory fitness (CRF), the European Quality of Life Questionnaire (EQ-5D-5L), the Seattle Angina Scale (SAQ), etc., will be assessed at baseline and 2 months ± 3 days. In addition, the survey scales will also be tested at 1 month ± 3 days. Trimethylamine N-oxide (TMAO), high-sensitivity C-reactive protein (hs-CRP), and gut microbiota features will be assessed at baseline and 2 months ± 3 days to probe possible mechanism. The major adverse cardiac and cerebrovascular events (MACCE) and bleeding events will be monitored until the 12-month follow-up. Discussion: This study is launched to assess the efficacy and safety of SQSX in CCAD after PCI and probe the possible mechanism. Clinical trial registration: China Clinical Trial Registry, ChiCTR2200060979, Registered on June 14, 2022.

Probiotic coated with glycol chitosan/alginate relieves oxidative damage and gut dysmotility induced by oxytetracycline in zebrafish larvae.

Probiotic-based therapy is a promising approach, which can positively modulate bacterial composition and maintain homeostasis. However, exogenous probiotics are easily destroyed by harsh conditions in vivo; thus, their application prospects have been severely limited. Specifically, oxytetracycline (OTC), a broad-spectrum antibiotic widely used in aquaculture, results in adverse intestinal environments, such as dysbacteriosis, oxidative damage, and gut dysmotility. Here, we describe a facile method to apply glycol chitosan/alginate as armor on the surface of probiotics to effectively protect them from the changed enteric environments induced by OTC. The results demonstrated that the coated Lacticaseibacillus rhamnosus GG (LGG) for only 2 h administration could significantly improve the colonization rate of LGG, and the relative abundance of Lacticaseibacillus can reach 80% in OTC-treated larvae intestines. We also explored the specific mechanisms of the coated LGG to diminish reactive oxygen species (ROS) generation and rescue gut dysmotility for OTC treatment, including enhancing the activity of antioxidative enzymes (CAT, SOD and GPx) and increasing 5-HT synthesis. The mitigation effect of the coated LGG for 2 h administration was comparable to that of uncoated LGG for 24 h administration. Encapsulation of LGG with polysaccharides provides a unique application example for generating useful bacterial therapeutics in harsh intestinal environments.

Lactobacillus rhamnosus GG normalizes gut dysmotility induced by environmental pollutants via affecting serotonin level in zebrafish larvae.

Intestinal peristalsis is essential for gastrointestinal function, which could maintain the appropriate progression and digestion of food and reduce bacterial aggregation through mixing function. Even though certain ingredients of foodstuff are known to increase or decrease intestinal peristalsis, the role of environmental pollutants on intestinal peristalsis is relatively unknown. Therefore, the effects of four typical environmental pollutants (oxytetracycline, arsenic, polychlorinated biphenyls and chlorpyrifos) on intestinal peristalsis in the zebrafish model and then tested the recovery effect of the constipation-resistant probiotic. The results showed that 4-day environmental pollutants exposures on the zebrafish embryos at 1 day post fertilization clearly decreased the intestinal peristalsis through decreasing the serotonin (5-HT) production and down-regulating the expression of key genes involved in 5-HT synthesis. Pollutants-evoked change of gut motility could be normalized in the presence of Lactobacillus rhamnosus GG (LGG) via increasing 5-HT secretion. Exogenous 5-hydroxytryptophan (100 µg/L) could also rescue the dysfunction of gut motility in pollutants-treated zebrfish. The data identified that LGG normalized disorder of intestinal peristalsis induced by environmental pollutants through increasing 5-HT level. The stimulant effect of LGG on peristalsis may be associated with 5-HT system, which could provide references for the application of probiotics in regulation of gut dysmotility.

Independently tunable all-dielectric synthetic multi-spectral metamaterials based on Mie resonance.

A single metamaterial (MM) is generally designed to operate in only one band, and the MMs with different dimensions of meta-atoms are required to be integrated to achieve multi-spectral responses simultaneously. In this study, an all-dielectric synthetic multi-spectral metamaterial (SMM) that can efficiently operate in the visible and terahertz (THz) ranges by incorporating nanoscale features into microscale unit cells is demonstrated and investigated numerically. The resonant frequency of the proposed SMM in both regimes can be tuned independently by changing the geometric parameters such as diameter, gap, width and height of unit cells functional in two different regions, whilst maintaining high reflectance efficiency. Results show that a variety of colors can be produced from red to purple in the visible range with maximal reflectance as high as 83% while the peak frequency of the SMM can be adjusted from 8.12 to 2.13 THz in the THz range with maximum reflectance up to 94%. The reflection characteristics of the SMM mainly originate from the electric dipole (ED) and magnetic dipole (MD) resonances via Mie scattering in both regions. The strategy of this research offers the possibility of applications in bio/chemical sensing, multi-spectral imaging, filtering, detection, modulation and so on.

Performance enhancement, membrane fouling mitigation and eco-friendly strategy by electric field coupled membrane bioreactor for treating mariculture wastewater.

An eco-friendly strategy for mariculture wastewater treatment using an electric field attached membrane bioreactor (E-MBR) was evaluated and compared with a conventional membrane bioreactor (C-MBR). The removal efficiencies of total nitrogen (TN) and chemical oxygen demand (COD) increased significantly and the membrane fouling rate reduced by 44.8% in the E-MBR. The underlying mechanisms included the enriched nitrifiers and denitrifiers, the enhanced salinity-resistance, the increased activities and upregulated genes of key enzymes involved in nitrification and denitrification for improving the performance of mariculture wastewater treatment, and the enriched extracellular polymeric substance (EPS)-degrading genera, the downregulated EPS biosynthesis genes, the repressed biofilm-forming bacteria, the enhanced zeta potential absolute value and the generated H2O2 for membrane fouling mitigation by electrical stimulation. Compared with the C-MBR, the energy consumption, carbon emissions, and nitrogen footprint were reduced. These findings provide novel insights into mariculture wastewater treatment using an applied electric field.

Efficacy and Safety of Shenqisuxin Granule for Non-ST-segment Elevation Acute Coronary Syndrome: Study Protocol for a Randomized, Double-Blinded, Placebo-Controlled Trial.

Introduction: The Chinese herbal compound formula, Shenqisuxin granule (SQSX), promotes neovascularization and prevents in-stent restenosis in modern pharmaceutical studies and is expected to provide an effective strategy for non-ST-segment elevation acute coronary syndrome (NSTEACS). Thus, this study aims to examine the efficacy and safety of SQSX for NSTEACS and initially reveal its mechanism. Methods/Design: The study is a randomized, double-blinded and placebo-controlled trial. A total of 66 participants will be randomly allocated to one of the following two groups. Participants in the SQSX group will receive conventional treatment plus SQSX, while the placebo group will receive conventional treatment plus placebo, both for 14 days. The primary outcome, hs-CRP, and secondary outcome the Seattle Angina Questionnaire (SAQ) will be assessed at baseline, 7 ± 3 days and 14 ± 3 days. At all visit windows, other indicators including creatine kinase (CK), creatine kinase-myocardial band (CK-MB), cardiac troponins I (cTnI), 12-lead electrocardiograph and the syndrome scores of Qi deficiency and blood stasis will be tested and metagenomic sequencing for intestinal flora will be performed. Echocardiography and safety assessment will be performed at baseline and 14 ± 3 days. Adverse events will be monitored during the trial. Discussion: The purpose of the study is to examine the efficacy and safety of SQSX to improve NSTEACS and initially reveal its mechanism. Trial Registration: China Clinical Trial Registry, ChiCTR2000029226. Registered on January 19, 2020.

Dopamine Level Affects Social Interaction and Color Preference Possibly Through Intestinal Microbiota in Zebrafish.

Accumulating researches suggest that the microbiota reside in the gastrointestinal system can influence neurodevelopment of brain and programming of behaviors. However, the mechanism underlining the relationship between shoals' behaviors and intestinal microbiota remain controversial and the roles of responsible neurotransmitters are still unclear. Here we show that shoaling behavior affected the color preference of shoals, indicating that shoals tended to choose a favorable color environment that benefited social contact. Meanwhile, administration of the selective D1-R antagonist, SCH23390, could disrupt the social interaction that led to the deficits of color preference in shoals. More importantly, the altered microbiota caused by an antibiotic oxytetracycline (OTC) exposure decreased the sociability and weakened shoals' preference for all color combinations. When given a supplementation of Lactobacillus rhamnosus GG after OTC exposure, fish maintained the same capability of social cohesion and color preference as normal fish. Our results support a role for dopamine in shaping the color preference in shoals. Our findings show that dopamine level of brain could mediate both social recognition and color preference, and offer a possibility that the production of dopamine is coordinated through gut microbiota.

Research landscape of exosomes in platelets from 2000 to 2022: A bibliometric analysis.

Background: Blood-derived exosomes are involved in developing multiple pathological processes, with platelets being the most well-known source. Related studies have become an area of research with significant value and potential. However, no bibliometric studies in this field have yet been identified. We aimed to analyze the hotspots and academic trends of platelet exosome research through bibliometric visualization to actively grasp the research base in this field and track its developmental orientation. Methods: From 2000 to 2022, we screened all relevant publications on platelet exosome-related research from the Web of Science database, generated knowledge maps using VOSviewer and CiteSpace software, and analyzed research trends in the field. Results: A total of 722 articles were screened for inclusion based on the search strategy. The number of articles on exosome studies in platelets has expanded vastly. The USA and the People's Republic of China contributed substantially among 69 countries or regions. Amsterdam University and Semmelweis University are the research institutions with the most publications. The most studied and co-cited journals were the International Journal of Molecular Sciences and the Journal of Extracellular Vesicles. We identified 4,598 authors, with Nieuwland Rienk having the highest number of articles and Bruno Stefania having the most cited publications. Keywords of great interest include "thrombosis," "anti-inflammatory," "anti-apoptosis," "angiogenesis," "microparticles," "miRNAs," "stem cells," and "biomarkers," which are key research areas for future development. Conclusion: We used bibliometric and visualization methods to identify hotspots and trends in platelet exosome research. Platelet exosome research is widely expanding. Future research will most likely focus on "thrombosis," "anti-inflammatory," "anti-apoptosis," "angiogenesis," "microparticles," "miRNAs," "stem cells," and "biomarkers."

The Mediating Role of Perceived Stress and Academic Procrastination between Physical Activity and Depressive Symptoms among Chinese College Students during the COVID-19 Pandemic.

Depressive symptoms, a prevalent mood illness, significantly harm college students' physical and mental health. Individuals have experienced some degree of psychological harm as a result of the COVID-19 pandemic. Taking this into account, the purpose of this study was to investigate the relationship between physical activity (PA) and depressive symptoms among college students during the COVID-19 pandemic, as well as the mediating roles of perceived stress and academic procrastination. A total of 586 college students were subjected to the Physical Activity Scale (PARS-3), the Perceived Stress Scale (PSS-10), the Procrastination Assessment Scale-Students (PASS), and the Patient Health Questionnaire (PHQ-9). Findings from this research demonstrated that there was a significant positive correlation between perceived stress, academic procrastination, and depressive symptoms, while PA was significantly negatively correlated with perceived stress, academic procrastination, and depressive symptoms. The results of the chain mediation analysis showed that PA had a significant direct effect on depressive symptoms. Perceived stress, academic procrastination, and perceived stress-academic procrastination had significant mediating and chain mediating effects on the relationship between PA and depressive symptoms. In conclusion, PA among college students during the COVID-19 pandemic affects their depressive symptoms directly and indirectly through the independent mediating effect of perceived stress and academic procrastination, as well as the chain mediating effect of perceived stress and academic procrastination.

The responses of activated sludge to membrane cleaning reagent H2O2 and protection of extracellular polymeric substances.

Hydrogen peroxide (H2O2) is evaluated as a potential replacement for chlorine to control biofouling in membrane bioreactors (MBRs). However, H2O2 might diffuse into the mixed liquor and damage microorganisms during membrane cleaning. This study comprehensively analyzed the impacts of H2O2 on microbes. Key enzymes involved in phenol biodegradation were inhibited with H2O2 concentration increased, and thus phenol degradation efficiency was decreased. Increase of lactic dehydrogenase (LDH) and intracellular reactive oxygen species (ROS) indicated more severe cell rupture with H2O2 concentration increased. At the same H2O2 concentration, Extracellular polymeric substances (EPS) extraction further led to inhibiting the activity of key enzymes, decreasing phenol degradation efficiency, and enhancing LDH release and ROS production, demonstrating that the existence of EPS moderated the adverse impacts on microbes. Spectroscopic characterization revealed the increase of H2O2 decreased tryptophan protein-like substances, protein-associated bonds and polysaccharide-associated bonds. Hydroxyl and amide groups in EPS were attacked, which might lead to the consumption of H2O2, indicated EPS protect the microorganism through sacrificial reaction with H2O2.