Degradation Product-Promoted Depolymerization Strategy for Chemical Recycling of Poly(bisphenol A carbonate).

The accumulation of waste plastics has a severe impact on the environment, and therefore, the development of efficient chemical recycling methods has become an extremely important task. In this regard, a new strategy of degradation product-promoted depolymerization process was proposed. Using N,N'-dimethyl-ethylenediamine (DMEDA) as a depolymerization reagent, an efficient chemical recycling of poly(bisphenol A carbonate) (BPA-PC or PC) material was achieved under mild conditions. The degradation product 1,3-dimethyl-2-imidazolidinone (DMI) was proven to be a critical factor in facilitating the depolymerization process. This strategy does not require catalysts or auxiliary solvents, making it a truly green process. This method improves the recycling efficiency of PC and promotes the development of plastic reutilization.

Co-transport of arsenic and micro/nano-plastics in saturated soil.

Contaminants can co-exist and migrate together in the environment, causing complex (and sometimes unexpected) transport dynamics which challenge the efficient remediation of individual contaminants. The co-transport dynamics, however, remained obscure for some contaminants, such as arsenic and micro/nano-plastics (MNPs). To fill this knowledge gap, this study explored the co-transport dynamics of arsenic and MNP particles in saturated soil by combining laboratory experiments and stochastic model analysis. Isothermal adsorption and sand column transport experiments showed that the adsorption of arsenic by MNP particles followed the Freundlich model, with a maximum adsorption of 2.425 mg/g for the MNP particles with a diameter of 100 nm. In the presence of MNP particles, the efflux concentration of arsenic ions declined due to adsorption, where the decline rate decreased with the increasing MNP size and increased with the increasing adsorption capacity. Experimental results also showed that the 100 nm nano-plastic particles prohibited arsenic transport in saturated sand columns, while the 5 µm microplastics enhanced arsenic transport due to electrostatic adsorption and media pore plugging. A tempered time fractional advective-dispersion equation was then proposed to quantify the observed breakthrough curves of arsenic. The results showed that this model can reliably capture the co-transport behavior of arsenic with MNPs in the saturated soil with all coefficients of determination over 0.97, and particularly, the small MNP particles facilitated anomalous transport of arsenic. This study therefore improved the understanding and quantification of the co-transport of arsenic and MNPs in soil.

Physiological responses of black locust-rhizobia symbiosis to water stress.

The present study explores the interaction of water supply and rhizobia inoculation on CO2 and H2 O gas exchange characteristics, physiological and biochemical traits in seedlings of Robinia pseudoacacia L. originating from two provenances with contrasting climate and soil backgrounds: the Gansu Province (GS) in northwest China and the Dongbei region (DB) of northeast China. Rhizobia strains were isolated from the 50-years old Robinia forest sites grown in the coastal region of east China. Robinia seedlings with and without rhizobia inoculation were exposed to normal water supply, moderate drought, and rewatering treatments, respectively. After 2 weeks of drought treatment, photosynthetic and physiological traits (net photosynthetic rate, stomatal conductance, stable isotope signature of carbon, malondialdehyde and hydrogen peroxide content) of Robinia leaves were significantly altered, but after rewatering, a general recovery was observed. Rhizobia inoculation significantly increased the drought resistance of both Robinia provenances by promoting photosynthesis, increasing the foliar N content and reducing the accumulation of malondialdehyde and hydrogen peroxide. Among the two provenances, DB plants developed more nodules than GS plants, but GS plants were more drought-tolerant than DB plants, both inoculated or noninoculated, indicated by the foliar gas exchange parameters and biochemical traits studied. Our results also show that inoculation of rhizobia could significantly improve the drought resistance of Robinia in both provenances. The present study contributes to the scientific background for the selection of drought-resistant varieties of Robinia to ensure the success of future afforestation projects in degraded terrestrial ecosystems under global climate change.

Assessment of left ventricular myocardial work done by noninvasive pressure-strain loop technique in patients with essential hypertension.

OBJECTIVE: To investigate the value of the noninvasive pressure-strain loop (PSL) technique for assessing left ventricular myocardial work done in patients with essential hypertension. METHODS: Prospectively, 60 patients with hypertension visiting the hospital from August 2020 to July 2021 were collected and divided into the mild hypertension group (SBP 140-159 mmHg, 35 cases) and the moderate-to-severe hypertension group (SBP ≥160 mmHg, 25 cases). Another 40 cases of healthy adults were collected as the control group. The differences in the global long-axis strain (GLS) and peak strain dispersion (PSD) of the left ventricle, global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE) were compared among the three groups. The receiver operating characteristic curve was used to evaluate the PSD, GWI, GCW, and GWW. The myocardial work index (MWI) and MWI percentages in the apical, middle, and basal segments of the heart were also compared among the groups. RESULTS: (1) The PSD, GWI, GCW, and GWW were significantly different among the groups (Χ2  = 57.605, 79.203, 76.973, and 17.429, respectively, p < .05), while the GLS and GWE were not (Χ2  = 1.559 and 5.849, respectively, p > .05). (2) The GWI had the highest specificity (97.5%) and the GCW the highest sensitivity (95%) in predicting hypertension. The percentage of apical MWI gradually increased (F = 11.230, p < .05) and the percentage of basal MWI gradually decreased (F = 10.665, p < .05) from the control group to the mild hypertension group to the moderate-to-severe hypertension group; there was no significant difference in the percentage of mid-MWI (F = 0.593, p > .05). CONCLUSIONS: The noninvasive PSL technique could be used to assess myocardial work done in patients with essential hypertension.

The Value of Chinese Thyroid Imaging Report and Data System Combined With Contrast-Enhanced Ultrasound Scoring in Differential Diagnosis of Benign and Malignant Thyroid Nodules.

OBJECTIVES: To explore the diagnostic value of contrast-enhanced ultrasound (CEUS) combined with the Chinese Thyroid Imaging Reporting and Data System (C-TIRADS) for differentiation of benign and malignant thyroid nodules. METHODS: A retrospective analysis of the conventional ultrasound and CEUS data of 388 nodules in 355 patients who had undergone thyroid nodule resection was conducted. All nodules had clear pathological results. The CEUS observation indexes included the enhancement degree in the arterial phase (no enhancement, scant punctate-linear enhancement, mild enhancement, moderate enhancement, and high enhancement) and wash-out patterns (rapid wash-out, slow wash-out, and isochronous wash-out). Chi-square test between groups and receiver operating characteristic curves (ROC) were used to determine the malignant (+1 point) and benign (-1 point) observation indexes that were statistically significant for the differentiation between benign and malignant thyroid nodules. The CEUS and C-TIRADS malignant and benign indexes were combined to score and draw the ROC curve, which was compared with the ROC curve scored by C-TIRADS alone to compare the diagnostic efficacy of the two methods for differentiating between benign and malignant thyroid nodules. RESULTS: Among the CEUS observation indexes, mild enhancement and rapid wash-out were malignant indexes, while isochronous wash-out was a benign index. The best diagnostic cut-off value for the differentiation of benign and malignant thyroid nodules using the C-TIRADS score and the C-TIRADS and CEUS combined score (C-TIRADS + CEUS score) was 2. The sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) of the two methods were 79.97, 75.48, 82.9, 70.5%, and 89.7, 72.9, 83.3, 82.5%, respectively. The area under the curve values were 0.840 and 0.877 (P < .001), respectively. CONCLUSIONS: The CEUS feature of mild enhancement in the arterial phase and rapid wash-out pattern are suggestive of malignancy and isochronous wash-out pattern is suggestive of benignity. The C-TIRADS + CEUS score has a higher value for distinguishing benign from malignant thyroid nodules than the C-TIRADS score alone.

Somatic Mutation Profiling of Papillary Thyroid Carcinomas by Whole-exome Sequencing and Its Relationship with Clinical Characteristics.

The incidence of papillary thyroid carcinomas (PTCs) has increased rapidly during the past several decades. Until now, the mechanisms underlying the tumorigenesis of PTCs have remained largely unknown. Next-generation-sequencing (NGS) provides new ways to investigate the molecular pathogenesis of PTCs. To characterize the somatic alterations associated with PTCs, we performed whole-exome sequencing (WES) of PTCs from 23 Chinese patients. This study revealed somatic mutations in genes with relevant functions for tumorigenesis, such as BRAF, BCR, CREB3L2, DNMT1, IRS2, MSH6, and TP53. We also identified novel somatic gene alterations which may be potentially involved in PTC progression. Gene set enrichment analysis revealed that the cellular response to hormone stimulus, epigenetic modifications, such as protein/histone methylation and protein alkylation, as well as MAPK, PI3K-AKT, and FoxO/mTOR signaling pathways, were significantly altered in the PTCs studied here. Moreover, Protein-Protein Interaction (PPI) network analysis of our mutated gene selection highlighted EP300, KRAS, PTEN, and TP53 as major core genes. The correlation between gene mutations and clinicopathologic features of the PTCs defined by conventional ultrasonography (US) and contrast-enhanced ultrasonography (CEUS) were assessed. These analyses established significant associations between subgroups of mutations and respectively taller-than-wide, calcified, and peak time iso- or hypo-enhanced and metastatic PTCs. In conclusion, our study supplements the genomic landscape of PTCs and identifies new actionable target candidates and clinicopathology-associated mutations. Extension of this study to larger cohorts will help define comprehensive genomic aberrations in PTCs and validate target candidates. These new targets may open methods of individualized treatments adapted to the clinicopathologic specifics of the patients.

An ssDNA aptamer specific for detection and purification of hexahistidine-tagged proteins.

Aptamers are small-sized RNA or ssDNA ligands with a unique structure, which have high specificity and affinity to their cognate targets. Thus, in addition to the extensive values in various bio-medical fields, aptamers can also be alternatively used as affinity ligands in the bioprocess, such as for protein purification. In the present study, a hexahistidine specific aptamer named AptHis-C, was developed through the SELEX methodology, which has high affinity to hexahistidine, and its dissociation constant was as low as 20.8 nM. The structural prediction revealed that AptHis-C contains two connected stem-loop conformations. AptHis-C can only specifically recognize recombinant proteins with the hexahistidine-tag in simple or complex situations, and not to those with other tags. When immobilized on magnetic beads, AptHis-C can be used as a tool for hexahistidine-tagged recombinant protein purification. Its effectiveness is as good as traditional Ni-based beads. Besides, due to the intrinsic characteristics of nucleic acids, such as high thermal/chemical stability, immobilized aptamer-magnetic beads can be reused many times without an obvious decrease of purification effectiveness. This aptamer may represent a novel method for the detection and purification of hexahistidine-tagged recombinant proteins.

Applicability of time fractional derivative models for simulating the dynamics and mitigation scenarios of COVID-19.

Fractional calculus provides a promising tool for modeling fractional dynamics in computational biology, and this study tests the applicability of fractional-derivative equations (FDEs) for modeling the dynamics and mitigation scenarios of the novel coronavirus for the first time. The coronavirus disease 2019 (COVID-19) pandemic radically impacts our lives, while the evolution dynamics of COVID-19 remain obscure. A time-dependent Susceptible, Exposed, Infectious, and Recovered (SEIR) model was proposed and applied to fit and then predict the time series of COVID-19 evolution observed over the last three months (up to 3/22/2020) in China. The model results revealed that 1) the transmission, infection and recovery dynamics follow the integral-order SEIR model with significant spatiotemporal variations in the recovery rate, likely due to the continuous improvement of screening techniques and public hospital systems, as well as full city lockdowns in China, and 2) the evolution of number of deaths follows the time FDE, likely due to the time memory in the death toll. The validated SEIR model was then applied to predict COVID-19 evolution in the United States, Italy, Japan, and South Korea. In addition, a time FDE model based on the random walk particle tracking scheme, analogous to a mixing-limited bimolecular reaction model, was developed to evaluate non-pharmaceutical strategies to mitigate COVID-19 spread. Preliminary tests using the FDE model showed that self-quarantine may not be as efficient as strict social distancing in slowing COVID-19 spread. Therefore, caution is needed when applying FDEs to model the coronavirus outbreak, since specific COVID-19 kinetics may not exhibit nonlocal behavior. Particularly, the spread of COVID-19 may be affected by the rapid improvement of health care systems which may remove the memory impact in COVID-19 dynamics (resulting in a short-tailed recovery curve), while the death toll and mitigation of COVID-19 can be captured by the time FDEs due to the nonlocal, memory impact in fatality and human activities.

Exosomes Play an Important Role in the Progression of Plasma Cell Mastitis via the PI3K-Akt-mTOR Signaling Pathway.

BACKGROUND: Plasma cell mastitis (PCM) is one of the most frequently encountered inflammatory diseases of the nonlactating breast. However, its pathogenesis has remained unknown. METHODS: In this study, we observed the ultrastructure changes of PCM by a transmission electron microscope. The transcriptome expression difference of exosomes was detected by RNA-Seq; then, we confirmed the key difference genes by western blot and immunohistochemistry. Finally, we established the mouse PCM model by tissue homogenate injection to validate the role of exosomes on the progression of PCM. RESULTS: The analysis of the exosomal transcriptome expression difference between PCM and normal mammary tissues using RNA-Seq showed the differential genes and enrichment pathways involved in the course of PCM. The decreased HSP90AA1 and EEF2, excessive production of p-AKT, and p-mTOR were consistent with clinical specimens. Inhibition of exosome secretion significantly inhibited inflammatory cell infiltration, and the mammary duct had maintained a better structure in the PCM mouse model. CONCLUSION: Our results revealed the role of exosomes acting as critical signal introduction facilitators in the progression of plasma cell mastitis and identified potential key genes in the regulation of this process. These results will help to dissect the molecular mechanism of PCM and provide therapeutic targets.

A Method of Short Text Representation Based on the Feature Probability Embedded Vector.

Text representation is one of the key tasks in the field of natural language processing (NLP). Traditional feature extraction and weighting methods often use the bag-of-words (BoW) model, which may lead to a lack of semantic information as well as the problems of high dimensionality and high sparsity. At present, to solve these problems, a popular idea is to utilize deep learning methods. In this paper, feature weighting, word embedding, and topic models are combined to propose an unsupervised text representation method named the feature, probability, and word embedding method. The main idea is to use the word embedding technology Word2Vec to obtain the word vector, and then combine this with the feature weighted TF-IDF and the topic model LDA. Compared with traditional feature engineering, the proposed method not only increases the expressive ability of the vector space model, but also reduces the dimensions of the document vector. Besides this, it can be used to solve the problems of the insufficient information, high dimensions, and high sparsity of BoW. We use the proposed method for the task of text categorization and verify the validity of the method.

Value of three-section contrast-enhanced transrectal ultrasonography in the detection of prostate cancer.

BACKGROUND: To assess the efficacy of three-section contrast-enhanced transrectal ultrasonography (CETRUS) in prostate cancer (PCa) detection. METHODS: A total of 169 consecutive patients with either PSA level ≥ 4 ng/ml or abnormal digital rectal examination findings were prospectively enrolled in this single center study. All patients underwent baseline transrectal ultrasonography (TRUS) and three-section CETRUS by one investigator blinded to any clinical data before TRUS-guided transperineal biopsy. The performances of baseline TRUS, single-section, and three-section CETRUS for PCa detection were compared. RESULTS: On a per-patient basis, the sensitivity, specificity, and overall accuracy for detecting PCa with three-section CETRUS was 92.3%, 69.2%, and 78.1%, respectively. In comparison with conventional (single-section) CETRUS (sensitivity 75.4%, specificity 72.1%, and accuracy 73.4%), three-section CETRUS performed significantly better (p < 0.05, McNemar test). Additionally, the low-grade PCa detection rate for three-section CETRUS was significantly higher than that of conventional CETRUS (26.7% versus 10.2%, p < 0.05). CONCLUSIONS: Our study demonstrated a significant benefit of three-section CETRUS relative to conventional CETRUS, and this technique may find more PCa patients eligible for active surveillance. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:304-309, 2017.

Aptamers: versatile molecular recognition probes for cancer detection.

In the past two decades, aptamers have emerged as a novel class of molecular recognition probes comprising uniquely-folded short RNA or single-stranded DNA oligonucleotides that bind to their cognate targets with high specificity and affinity. Aptamers, often referred to as "chemical antibodies", possess several highly desirable features for clinical use. They can be chemically synthesized and are easily conjugated to a wide range of reporters for different applications, and are able to rapidly penetrate tissues. These advantages significantly enhance their clinical applicability, and render them excellent alternatives to antibody-based probes in cancer diagnostics and therapeutics. Aptamer probes based on fluorescence, colorimetry, magnetism, electrochemistry, and in conjunction with nanomaterials (e.g., nanoparticles, quantum dots, single-walled carbon nanotubes, and magnetic nanoparticles) have provided novel ultrasensitive cancer diagnostic strategies and assays. Furthermore, promising aptamer targeted-multimodal tumor imaging probes have been recently developed in conjunction with fluorescence, positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). The capabilities of the aptamer-based platforms described herein underscore the great potential they hold for the future of cancer detection. In this review, we highlight the most prominent recent developments in this rapidly advancing field.

Aptamers and their applications in nanomedicine.

Aptamers are composed of short RNA or single-stranded DNA sequences that, when folded into their unique 3D conformation, can bind to their targets with high specificity and affinity. Although functionally similar to protein antibodies, oligonucleotide aptamers offer several advantages over protein antibodies in biomedical and clinical applications. Through the enhanced permeability and retention effect, nanomedicines can improve the therapeutic index of a treatment and reduce side effects by enhancing accumulation at the disease site. However, this targets tumors passively and, thus, may not be ideal for targeted therapy. To construct ligand-directed "active targeting" nanobased delivery systems, aptamer-equipped nanomedicines have been tested for in vitro diagnosis, in vivo imaging, targeted cancer therapy, theranostic approaches, sub-cellular molecule detection, food safety, and environmental monitoring. This review focuses on the development of aptamer-conjugated nanomedicines and their application for in vivo imaging, targeted therapy, and theranostics.

A Highlight of Recent Advances in Aptamer Technology and Its Application.

Aptamers and SELEX (systematic evolution of ligands by exponential enrichment) technology have gained increasing attention over the past 25 years. Despite their functional similarity to protein antibodies, oligonucleotide aptamers have many unique properties that are suitable for clinical applications and industrialization. Aptamers may be superior to antibodies in fields such as biomarker discovery, in vitro and in vivo diagnosis, precisely controlled drug release, and targeted therapy. However, aptamer commercialization has not occurred as quickly as expected, and few aptamer-based products have yet successfully entered clinical and industrial use. Thus, it is important to critically review some technical barriers of aptamer and SELEX technology per se that may impede aptamer development and application. To date, how to rapidly obtain aptamers with superior bioavailability over antibodies remains the key issue. In this review, we discuss different chemical and structural modification strategies aimed to enhance aptamer bioavailability. We also discuss improvements to SELEX process steps to shorten the selection period and improve the SELEX process success rate. Applications in which aptamers are particularly suited and perform differently or superior to antibodies are briefly introduced.

The bimolecular reactive transport in heterogeneous porous media: Sub-diffusion in interpretation of laboratory experiment.

This present work consists of investigating the effects of particle size heterogeneity and flow rates on transport-reaction kinetics of CuSO4 and Na2EDTA2- in porous media, via the combination of a bimolecular reaction experiment and model simulations. In the early stages of transport, a peak is observed in the concentration breakthrough curve of the reactant CuSO4, related to the delayed mixing and reaction of the reactants. The numerical results show that an increase in flow rate promotes the mixing processes between the reactants, resulting in a larger peak concentration and a slighter tail of breakthrough curves, while an increase in medium heterogeneity leads to a more significant heavy tail. The apparent anomalous diffusion and heavy-tailing behavior can be effectively quantified by a novel truncated fractional derivative bimolecular reaction model. The truncated fractional-order model, taking into account the incomplete mixing, offers a satisfactory reproduction of the experimental data.

A fractal Richards' equation to capture the non-Boltzmann scaling of water transport in unsaturated media.

The traditional Richards' equation implies that the wetting front in unsaturated soil follows Boltzmann scaling, with travel distance growing as the square root of time. This study proposes a fractal Richards' equation (FRE), replacing the integer-order time derivative of water content by a fractal derivative, using a power law ruler in time. FRE solutions exhibit anomalous non-Boltzmann scaling, attributed to the fractal nature of heterogeneous media. Several applications are presented, fitting the FRE to water content curves from previous literature.

Prediction of post-Darcy flow based on the spatial non-local distribution of hydraulic gradient: Preliminary assessment of wastewater management.

Understanding high-velocity pollutant transport dependent on the large hydraulic gradient and/or heterogeneity of the aquifer and criteria for the onset of post-Darcy flow have attracted considerable attention in water resources and environmental engineering applications. In this study, a parameterized model is established based on the equivalent hydraulic gradient (EHG) which affected by spatial nonlocality of nonlinear head distribution due to the inhomogeneity at a wide range of scales. Two parameters relevant to the spatially non-local effect were selected to predict the development of post-Darcy flow. Over 510 sets of laboratory one-dimensional (1-D) steady hydraulic experimental data were used to validate the performance of this parameterized EHG model. The results show that (1) the spatial nonlocal effect of the whole upstream is related to the mean grain size of the medium, and the anomalous variation due to the small grain size implies the existence of the particle size threshold. (2) The parameterized EHG model can effectively capture the nonlinear trend that fails to be described by the traditional local form of nonlinear models, even if the specific discharge stabilizes at the later stages. (3) The Sub-Darcy flow distinguished by the parameterized EHG model can be equated to the post-Darcy flow, and then the criteria for the post-Darcy flow will be strictly distinguished under the premise of determining the hydraulic conductivity. The results of this study facilitate the identification and prediction of high-velocity non-Darcian flow in wastewater management and provide insight into mass transport by advection at the fine-scale.

A fractional derivative model for nuclides transport in heterogeneous fractured media.

Nuclide transport in fractured media involves the advection, dispersion, adsorption, etc. The dispersion and adsorption properties of the rock matrix have spatial variability, which results in an anomalous transport of nuclides. In this study, a time-fractional advection-diffusion equation (t-FADE) model is utilized to capture the sub-diffusion transport behavior with heavy-tail property, including the breakthrough curves (BTCs) of uranium and thorium transport in granite plates. Moreover, hydrodynamic dispersion of tritiated water, strontium and cesium in granite fractures are also studied. The results indicate that BTCs of nuclides transport in the granite fractures are unimodal and asymmetric. The decrease of the fractional order α reflects the stronger sub-diffusion. Furthermore, small initial velocity enhances sub-diffusion effect of nuclides and lengthens the breakout time of BTCs, which results in obvious heavy-tail phenomena. The analysis results demonstrate that the t-FADE model can accurately describe sub-diffusion behavior of nuclides transport. At last, the advantages of the t-FADE model in prediction and remediation of nuclides contamination are put forward.

Alterations in the "Gut-Liver Axis" on Rats with Immunological Hepatic Fibrosis.

There remains a lack of standard models that have all the characteristics of human diseases. Especially in immunological hepatic fibrosis, the bovine serum albumin (BSA)-induced liver fibrosis models have the same developmental mechanisms as human liver fibrosis models, but have received little attention. We standardized a BSA-induced liver fibrosis model in rats and thoroughly assessed its pathological characteristics. We also used 16S sequencing to assess homeostasis of the intestinal microflora of rats with BSA-induced liver fibrosis and detected various differential metabolites in the serum of these rats using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). We observed stable and unambiguous histological changes in liver tissue morphology and remarkably high concentrations of inflammatory markers in the serum of BSA-induced liver fibrosis rats. In keeping with the fact that BSA induction can cause gut microbiota disorders in rats. UHPLC-MS/MS analysis of rat serum samples in positive-ion mode and negative-ion mode revealed 17 and 25 differential metabolites, respectively. Network analysis revealed that phenylalanine or tyrosine metabolites (e.g., PAGln) were the predominant metabolites in the sera of BSA-induced liver fibrosis rats. Taken together, our results suggest that disorders of amino acid metabolism caused by the gut microbiota may play an important role in the progression of immunological hepatic fibrosis.

Understanding the consumers' multi-competing brand community engagement: A mix method approach.

Introduction: Participating in multiple competing brand communities simultaneously is common for consumers, which brings challenges for companies to manage brand communities and build strong brand-consumer relationships. Although previous studies have widely examined the drivers and outcomes of consumers' engagement in an individual community, little is known about the multi-competing brand community engagement. Methods: This paper explores the manifestation, categories, motivational drivers, and consequences of consumers' MBCE through two studies using two different methodologies to fill this gap. Results: By using netnography, study 1 shows that MBCE behaviors manifest in various ways, and can be classified into three categories: information-oriented MBCE, social-oriented MBCE, and oppositional MBCE. Study 2 indicates through a consumer survey that one reason that motivates consumers to participate in other competing brand communities is because of the attractiveness of other competing brands. Also, the results indicate that consumers' product knowledge is positively associated with MBCE. Finally, the number of competing brand community engagements is positively related to brand switching intention. Discussion: This article enriches the brand community literature and provides important implications on managing brand communities in a competing environment.