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Retinal vessel segmentation is crucial for diagnosing and monitoring various eye diseases such as diabetic retinopathy, glaucoma, and hypertension. In this study, we examine how sharpness-aware minimization (SAM) can improve RF-UNet's generalization performance. RF-UNet is a novel model for retinal vessel segmentation. We focused our experiments on the digital retinal images for vessel extraction (DRIVE) dataset, which is a benchmark for retinal vessel segmentation, and our test results show that adding SAM to the training procedure leads to notable improvements. Compared to the non-SAM model (training loss of 0.45709 and validation loss of 0.40266), the SAM-trained RF-UNet model achieved a significant reduction in both training loss (0.094225) and validation loss (0.08053). Furthermore, compared to the non-SAM model (training accuracy of 0.90169 and validation accuracy of 0.93999), the SAM-trained model demonstrated higher training accuracy (0.96225) and validation accuracy (0.96821). Additionally, the model performed better in terms of sensitivity, specificity, AUC, and F1 score, indicating improved generalization to unseen data. Our results corroborate the notion that SAM facilitates the learning of flatter minima, thereby improving generalization, and are consistent with other research highlighting the advantages of advanced optimization methods. With wider implications for other medical imaging tasks, these results imply that SAM can successfully reduce overfitting and enhance the robustness of retinal vessel segmentation models. Prospective research avenues encompass verifying the model on vaster and more diverse datasets and investigating its practical implementation in real-world clinical situations.
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Algoritmos , Vasos Retinianos , Humanos , Vasos Retinianos/diagnóstico por imagen , Procesamiento de Imagen Asistido por Computador/métodos , Retinopatía Diabética/diagnóstico por imagenRESUMEN
Transformer-based methodologies in object detection have recently piqued considerable interest and have produced impressive results. DETR, an end-to-end object detection framework, ingeniously integrates the Transformer architecture, traditionally used in NLP, into computer vision for sequence-to-sequence prediction. Its enhanced variant, DINO, featuring improved denoising anchor boxes, has showcased remarkable performance on the COCO val2017 dataset. However, it often encounters challenges when applied to scenarios involving small object detection. Thus, we propose an innovative method for feature enhancement tailored to recursive prediction tasks, with a particular emphasis on augmenting small object detection performance. It primarily involves three enhancements: refining the backbone to favor feature maps that are more sensitive to small targets, incrementally augmenting the number of queries for small objects, and advancing the loss function for better performance. Specifically, The study incorporated the Switchable Atrous Convolution (SAC) mechanism, which features adaptable dilated convolutions, to increment the receptive field and thus elevate the innate feature extraction capabilities of the primary network concerning diminutive objects. Subsequently, a Recursive Small Object Prediction (RSP) module was designed to enhance the feature extraction of the prediction head for more precise network operations. Finally, the loss function was augmented with the Normalized Wasserstein Distance (NWD) metric, tailoring the loss function to suit small object detection better. The efficacy of the proposed model is empirically confirmed via testing on the VISDRONE2019 dataset. The comprehensive array of experiments indicates that our proposed model outperforms the extant DINO model in terms of average precision (AP) small object detection.
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The anesthetic drug, ketamine (KTM) has been shown to induce therapeutic effects against major depressive disorder (MDD), however the related underlying mechanisms remain unclear. In the present study, HT22 neuronal cells were treated with glutamate to imitate oxidative stress injury in MDD, and it was hypothesized that the cannabinoid type 1 (CB1) receptor mediates KTM-induced neuroprotection via ameliorating mitochondrial function in glutamate-treated neuronal cells. Compared with the control, glutamate decreased cell viability and intracellular antioxidants, including glutathione (GSH), catalase and superoxide dismutase 2 levels, and inhibited mitochondrial function simultaneously. Moreover, glutamate increased lactate dehydrogenase release, cellular apoptosis level, cleaved caspase-3 expression and intracellular oxidants, such as reactive oxygen species, oxidized GSH and mitochondrial superoxide in the cells. The presence of KTM, however, significantly decreased the glutamate-induced oxidative stress injury, ameliorated the antioxidant/oxidant levels in the cells, enhanced mitochondrial function and upregulated CB1 receptor expression (P<0.05). Co-administration of the CB1 receptor antagonist AM251 markedly abolished the KTM-induced cytoprotective effects and ameliorations of antioxidant/oxidant levels and mitochondrial function, and also reversed CB1 upregulation (P<0.05). These observations indicated that KTM decreases the oxidative stress injury caused by glutamate in HT22 neuronal cells, and the neuroprotective effects may be mediated by the CB1 receptor.
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Heart failure and cardiac remodeling are both characterized by mitochondrial dysfunction. Healthy mitochondria are required for adequate contractile activity and appropriate regulation of cell survival. In the mammalian heart, enhancement of the mitochondrial unfolded protein response (UPRmt) is cardioprotective under pressure overload conditions. We explored the UPRmt and the underlying regulatory mechanism in terms of hypertension-induced cardiac remodeling and the cardioprotective effect of metformin. Male spontaneously hypertensive rats and angiotensin II-treated neonatal rat cardiomyocytes were used to induce cardiac hypertrophy. The results showed that hypertension induced the formation of aberrant mitochondria, characterized by a reduced mtDNA/nDNA ratio and swelling, as well as lower levels of mitochondrial complexes I to V and inhibition of the expression of one protein subunit of each of complexes I to IV. Such changes eventually enlarged cardiomyocytes and increased cardiac fibrosis. Metformin treatment increased the mtDNA/nDNA ratio and regulated the UPRmt, as indicated by increased expression of activating transcription factor 5, Lon protease 1, and heat shock protein 60, and decreased expression of C/EBP homologous protein. Thus, metformin improved mitochondrial ultrastructure and function in spontaneously hypertensive rats. In vitro analyses revealed that metformin reduced the high levels of angiotensin II-induced mitochondrial reactive oxygen species in such animals and stimulated nuclear translocation of heat shock factor 1 (HSF1). Moreover, HSF1 small-interfering RNA reduced the metformin-mediated improvements in mitochondrial morphology and the UPRmt by suppressing hypertrophic signals and cardiomyocyte apoptosis. These results suggest that HSF1/UPRmt signaling contributes to the beneficial effects of metformin. Metformin-mediated targeting of mitochondrial protein homeostasis and modulation of HSF1 levels have potential therapeutic implications in terms of cardiac remodeling.
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Factores de Transcripción del Choque Térmico , Metformina , Miocitos Cardíacos , Respuesta de Proteína Desplegada , Animales , Masculino , Ratas , Angiotensina II/farmacología , Cardiomegalia/metabolismo , Cardiomegalia/tratamiento farmacológico , Cardiomegalia/patología , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Factores de Transcripción del Choque Térmico/efectos de los fármacos , Factores de Transcripción del Choque Térmico/metabolismo , Hipertensión/metabolismo , Hipertensión/tratamiento farmacológico , Metformina/farmacología , Mitocondrias Cardíacas/metabolismo , Mitocondrias Cardíacas/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Ratas Endogámicas SHR , Ratas Endogámicas WKY , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Respuesta de Proteína Desplegada/efectos de los fármacos , Remodelación Ventricular/efectos de los fármacosRESUMEN
Synthetic aperture radar (SAR) sensor often produces a shadow in pairs with the target due to its slant-viewing imaging. As a result, shadows in SAR images can provide critical discriminative features for classifiers, such as target contours and relative positions. However, shadows possess unique properties that differ from targets, such as low intensity and sensitivity to depression angles, making it challenging to extract depth features from shadows directly using convolutional neural networks (CNN). In this paper, we propose a new SAR image-classification framework to utilize target and shadow information comprehensively. First, we design a SAR image segmentation method to extract target regions and shadow masks. Second, based on SAR projection geometry, we propose a data-augmentation method to compensate for the geometric distortion of shadows due to differences in depression angles. Finally, we introduce a feature-enhancement module (FEM) based on depthwise separable convolution (DSC) and convolutional block attention module (CBAM), enabling deep networks to fuse target and shadow features adaptively. The experimental results on the Moving and Stationary Target Acquisition and Recognition (MSTAR) dataset show that when only using target and shadow information, the published deep-learning models can still achieve state-of-the-art performance after embedding the FEM.
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Background: Since China's dynamic zero-COVID policy is cancelled on December 7, 2022, the rapidly growing number of patients has brought a major public health challenge. This study aimed to assess whether there were differences in the severity and mortality risk factors for patients hospitalized for COVID-19 pneumonia between the early wave and the very late stage of the pandemic. Methods: A retrospective cross-sectional study was carried out using data from 223 hospitalized patients diagnosed with COVID-19 pneumonia during the Omicron surge in Xi'an People's Hospital (Xi'an Fourth Hospital) from December 8, 2022, to January 31, 2023. Univariable and multivariable logistic regression analyses were used to identify potential risk factors associated with the severity and mortality of COVID-19 pneumonia during the first wave of the pandemic after the dynamic zero-COVID policy was retracted. Differences in the severity and mortality risk factors were assessed at different stages of the pandemic, mainly from demographic, clinical manifestation, laboratory tests and radiological findings of patients on admission. Results: The mean age of the 223 participants was 71.2 ± 17.4. Compared with the patients in the initial stage of the pandemic, the most common manifestation among patients in this study was cough (90.6%), rather than fever (79.4%). Different from the initial stage of the pandemic, older age, chest tightness, elevated neutrophil-to-lymphocyte ratio (NLR), decreased albumin (ALB) level and ground glass opacification (GGO) in radiological finding were identified as severity risk factors, instead of mortality risk factors for COVID-19 patients in the very late stage of the pandemic. Arterial partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) ≤300 mmHg, cardiovascular disease and laboratory findings including elevated levels of D-dimer, α-hydroxybutyrate dehydrogenase (α-HBDH), total bilirubin (TBIL), alanine aminotransferase (ALT), urea nitrogen (BUN), creatinine (CR), fasting blood glucose (FBG) and decreased platelet count (PLT) were still associated with mortality in the very late stage of the pandemic. Conclusion: Monitoring continuously differences in the severity and mortality risk factors for COVID-19 patients between different stages of the pandemic could provide evidence for exploring uncharted territory in the coming post-pandemic era.
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Background: Stress ulcer prophylaxis (SUP) prescribed in patients admitted to surgical wards with a low risk of stress-related mucosal disease (SRMD) accounted for a considerable proportion of improper use of proton pump inhibitors (PPIs). This study aimed to analyze the appropriateness of SUP prescribing patterns and identify its associated factors in the orthopedics department of a tertiary hospital in the Northwestern China. Methods: In this cross-sectional study, information regarding the demographic and clinical characteristics of 1,200 fracture inpatients who underwent surgical operations from January 2020 to August 2021 were collected from medical records. Established criteria were used to assess the appropriateness of the prescribing pattern for SUP, and the incidence of inappropriate SUP medication was calculated. Logistic regression analyses were used to identify factors associated with inappropriate SUP medication. Results: Approximately, 42.4% of the study population was interpreted as inappropriate prescription of SUP. A total of 397 (33.1%) patients received SUP without a proper indication (overprescription), and the incidence of inappropriate SUP medication was calculated to be 43.11 per 100 patient-days. In addition, 112 (9.3%) inpatients for whom SUP was indicated did not receive SUP (underprescription). PPIs were prescribed in 96.1% of the inpatients who used acid suppression therapy (AST), and intravenous PPIs accounted for 95.3% thereof. In a multivariate logistic regression analysis, age above 65 years and prolonged hospitalization were associated with overprescription of SUP. Increased number of drugs excluding PPIs, the concurrent use of systemic corticosteroids, comorbidity of hypertension, and unemployed or retired status in inpatients were associated with a reduced likelihood of overprescription for SUP. Conversely, prolonged hospitalization, the concurrent use of systemic corticosteroids or anticoagulants, and unemployed status in inpatients were positively associated with underprescription of SUP. Conclusion: There was a high prevalence of inappropriate SUP prescription among noncritically ill inpatients of fracture who underwent surgical operations. We delineated the associated factors with inappropriate SUP medication, which indicated that more information was required for clinicians about rationality and efficiency of their prescribing practices. Effective intervention strategies should be executed by clinical pharmacists to reduce improper SUP medication.
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Background: The management of Key Monitoring Drugs has become one of important aspects to control the growth of pharmaceutical expenditures in China. The first batch of the China National Key Monitoring Drugs (NKMDs) policy was released in July 2019. However, little is known about the impact of the national stewardship on the trends of NKMDs prescribing practice in hospitals, especially in the Northwestern China. Methods: We collected 8-years of monthly NKMDs usage data from a tertiary hospital between 2014 and 2021. A segmented regression model of interrupted time series (ITS) analysis was used to evaluate the Defined Daily Doses (DDDs) and spending trends of ten NMKDs in the hospital throughout the study period. The pre-implementation period was from January 2014 to November 2019 and the post-implementation period was from December 2019 to June 2021. Results: Prior to the implementation of the NKMDs policy, there was an increasing trend both in DDDs and spending for 8 of 10 NKMDs. The interventions managed by clinical pharmacists after the implementation of the national stewardship policy led to a significant decreasing trend of DDDs in the 19 months following implementation, of 430 fewer DDDs per month in total, compared to the pre-implementation period (p < 0.001). A similar decrease in spending was seen in the post-implementation period, with a trend of $4,682 less total spending on medications in those months compared to the pre-implementation trend (p = 0.003). There was a significant decrease in both monthly DDDs and spending for 6 of the 10 medications in the post-implementation period, while there was a significant increased trend both in monthly DDDs and spending on 1 medication in that period. Conclusion: Using ITS analysis, the total DDDs and spending on 10 NKMDs in this hospital indicated sustained reductions over 19 months after multidimensional interventions under the implementation of the national policy guidance. The national stewardship policy could therefore be considered an effective strategy. Additional comprehensive policies should be introduced to further improve the rational use of NKMDs.
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Attenuating ß amyloid- (Aß-) induced microglial activation is considered to be effective in treating Alzheimer's disease (AD). Berberine (BBR) can reduce microglial activation in Aß-treated microglial cells; the mechanism, however, is still illusive. Silencing of cytokine signaling factor 1 (SOCS1) is the primary regulator of many cytokines involved in immune reactions, whose upregulation can reverse the activation of microglial cells. Microglia could be activated into two different statuses, classic activated state (M1 state) and alternative activated state (M2 state), and M1 state is harmful, but M2 is beneficial. In the present study, N9 microglial cells were exposed to Aß to imitate microglial activation in AD. And Western blot and immunocytochemistry were taken to observe inducible nitric oxide synthase (iNOS), Arginase-1 (Arg-1), and SOCS1 expressions, and the enzyme-linked immunosorbent assay (ELISA) was used to measure inflammatory and neurotrophic factor release. Compared with the normal cultured control cells, Aß exposure markedly increased the level of microglial M1 state markers (P < 0.05), including iNOS protein expression, tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), and IL-6 releases, and BBR administration upregulated SOSC1 expression and the level of microglial M2 state markers (P < 0.05), such as Arg-1 expression, brain-derived neurotrophic factor (BDNF), and glial cell-derived neurotrophic factor (GDNF) releases, downregulating the SOCS1 expression by using siRNA, however, significantly reversed the BBR-induced effects on microglial M1 and M2 state markers and SOCS1 expression (P < 0.05). These findings indicated that BBR can inhibit Aß-induced microglial activation via modulating the microglial M1/M2 activated state, and SOCS1 mediates the process.
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Péptidos beta-Amiloides/metabolismo , Microglía/metabolismo , Proteína 1 Supresora de la Señalización de Citocinas/metabolismo , Enfermedad de Alzheimer/metabolismo , Arginasa/metabolismo , Berberina/farmacología , Línea Celular , China , Citocinas/metabolismo , Humanos , Inflamación/patología , Macrófagos/metabolismo , Microglía/fisiología , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Proteína 1 Supresora de la Señalización de Citocinas/fisiología , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Infrasonic signals measured before an earthquake carry information about the size and development speed of the source fracture, the stress at the fracture site and the elastic properties of the geologic medium. The infrasonic signal has a stable time scale, and compared with other precursors, infrasound has a unique sensitivity to earthquake disasters. However, to date, there has been no relevant theoretical research on the mechanism of infrasonic anomalies, and information on the development of fracture sources cannot be obtained from these characteristics, which makes the application of this anomaly in earthquake prediction challenging. In this study, we obtained the characteristics of short-term and impending infrasonic anomalies based on the infrasound data of more than 100 strong earthquakes. With a range of elastic medium models with a large number of fractures, we completed the theoretical simulation of the formation process of infrasonic precursors during the formation of the main fractures, analyzed the physical evolution of acoustic signals when cracks are generated, and quantitatively described the stages of large fracture formation caused by the initiation and propagation of seismic cracks. Specifically, this study revealed the causes of various and complex forms of infrasonic precursors near the critical point and the causes of the time- and space-dependent characteristics of these precursors, such as a noticeable attenuation of the pulse number, a low frequency and a large amplitude, which verified the effectiveness of infrasonic anomalies as strong earthquake precursors.
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Simulación por Computador , Desastres , Terremotos , Acústica , Planificación en DesastresRESUMEN
Angiotensin II- (Ang II-) induced cardiac hypertrophy and apoptosis are major characteristics of early-stage heart failure. Choline exerts cardioprotective effects; however, its effects on Ang II-induced cardiomyocyte apoptosis are unclear. In this study, the role and underlying mechanism of choline in regulating Ang II-induced cardiomyocyte apoptosis were investigated using a model of cardiomyocyte apoptosis, which was induced by exposing neonatal rat cardiomyocytes to Ang II (10-6 M, 48 h). Choline promoted heat shock transcription factor 1 (HSF1) nuclear translocation and the intracellular domain of Notch1 (NICD) expression. Consequently, choline attenuated Ang II-induced increases in mitochondrial reactive oxygen species (mtROS) and promotion of proapoptotic protein release from mitochondria, including cytochrome c, Omi/high-temperature requirement protein A2, and second mitochondrial activator of caspases/direct inhibitor of apoptosis-binding protein with low P. The reversion of these events attenuated Ang II-induced increases in cardiomyocyte size and numbers of terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling-positive cells, presumably via type 3 muscarinic acetylcholine receptor (M3AChR). Indeed, downregulation of M3AChR or Notch1 blocked choline-mediated upregulation of NICD and nuclear HSF1 expression, as well as inhibited mitochondrial apoptosis pathway and cardiomyocyte apoptosis, indicating that M3AChR and Notch1/HSF1 activation confer the protective effects of choline. In vivo studies were performed in parallel, in which rats were infused with Ang II for 4 weeks to induce cardiac apoptosis. The results showed that choline alleviated cardiac remodeling and apoptosis of Ang II-infused rats in a manner related to activation of the Notch1/HSF1 pathway, consistent with the in vitro findings. Taken together, our results reveal that choline impedes oxidative damage and cardiomyocyte apoptosis by activating M3AChR and Notch1/HSF1 antioxidant signaling, and suggest a novel role for the Notch1/HSF1 signaling pathway in the modulation of cardiomyocyte apoptosis.
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Angiotensina II/efectos adversos , Colina/metabolismo , Factores de Transcripción del Choque Térmico/metabolismo , Miocitos Cardíacos/metabolismo , Animales , Apoptosis , Masculino , Ratas , Ratas Sprague-Dawley , Transducción de SeñalRESUMEN
Among the GTPase family members, guanylate-binding protein-1 (GBP-1) is the most thoroughly studied member in a plethora of human cancers. GBP-2, on the other hand, remains limitedly studied. We wonder how GBP-2 participates in colorectal carcinoma (CRC) as well as the paclitaxel (PTX)-resistance of CRC. In this study, the authors are determined to dig into the role that GBP-2 plays in the sensitivity of CRC to PTX, therefore, possibly indicating a promising gene therapy target for CRC. Forced expression of GBP-2 gene was done by plasmid transfection. Reverse transcriptase-polymerase chain reaction and immunoblot were conducted to detect the expression of GBP-2 messenger RNA (mRNA) and protein, respectively. Colony foci formation assay, transwell invasion assay, and flow cytofluorometry were done to determine the proliferation, invasion, and apoptosis of PTX-resistant and PTX-sensitive CRC cell lines, respectively. The level of GBP-2 mRNA and protein in PTX-resistant CRC cell lines was significantly lower than in nonresistant cell lines. Forced exogenous expression of GBP-2 in PTX-resistant CRC cell lines resulted in more sensitivity to PTX because of the demonstration of less cell proliferation, invasion, and more apoptosis. Wnt signaling was suppressed when GBP-2 was upregulated by transfection of GBP-2 overexpression plasmids, and Wnt signaling did not affect GBP-2 expression. GBP-2 upregulation could enhance the killing effect of PTX in both PTX-sensitive CRC cells and PTX-resistant CRC cells by suppressing Wnt signaling.
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Biomarcadores de Tumor/metabolismo , Neoplasias Colorrectales/tratamiento farmacológico , Resistencia a Antineoplásicos , Proteínas de Unión al GTP/metabolismo , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Paclitaxel/farmacología , Vía de Señalización Wnt/efectos de los fármacos , Antineoplásicos Fitogénicos/farmacología , Apoptosis , Biomarcadores de Tumor/genética , Proliferación Celular , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Proteínas de Unión al GTP/genética , Humanos , Células Tumorales CultivadasRESUMEN
To assess the adherence level of antihypertensive treatment and identify any associated risk factors in a sample of hypertensive patients from China.A cross-sectional study involving 488 Chinese hypertensive patients was conducted in a tertiary hospital in Xi'an, China. Data were collected regarding socio-demographic factors and hypertension-related clinical characteristics. The adherence to treatment was assessed using the previously validated instrument: therapeutic adherence scale for hypertensive patients.A total of 27.46% of patients were compliant with their antihypertensive treatments. Three factors were identified to be independently associated with antihypertensive treatment adherence: gender (Pâ=â.034), residence (Pâ=â.029), duration of high blood pressure (Pâ<â.001). Gender, residence, occupation, and the duration of antihypertensive drugs treatment used were found to have significant effects on treatment adherence in certain categories.Treatment adherence among hypertensive patients in China was poor. More attention and effective strategies should be designed to address factors affecting treatment adherence. Education about hypertension knowledge should be strengthened for patients. Moreover, the importance of lifestyle modification during hypertension treatment is often neglected by patients, therefore, there is an urgent need to educate hypertensive patients about the adherence to lifestyle modifications.
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Antihipertensivos/uso terapéutico , Hipertensión/terapia , Cumplimiento de la Medicación/estadística & datos numéricos , Adulto , Anciano , Anciano de 80 o más Años , Distribución de Chi-Cuadrado , China , Estudios Transversales , Femenino , Humanos , Hipertensión/clasificación , Masculino , Persona de Mediana Edad , Factores de Riesgo , Factores Socioeconómicos , Encuestas y CuestionariosRESUMEN
Bacterial cellulose (BC) is a new kind of cellulose with great potential in enhancing preparation of isotactic Polypropylene (iPP) composites, which have been found with excellent performance. However, the interface compatibility between BC and iPP is poor. In this study, iPP/BC composites were prepared by solution mixing. Esterification modified BC (CO) and Maleic anhydride grafted polypropylene (MAPP) added as a compatibilizer was both used to improve the interfacial compatibility of the iPP/BC composites. The rheology and isothermal crystallization behavior of the composites was tested and discussed. The result shows that the complex viscosity and storage modulus of the composite significantly increase in the rule iPP, iPP/BC2, iPP/CO2, and M-iPP/BC3, which indicates that the compatibility of the composite increases as this rule. According to the isothermal crystallization kinetics result, the crystal growth mode of iPP was not affected by the addition of BC and the interfacial compatibility. The spherulite growth rate of the iPP/BC composite increases with increasing crystallization temperature. Especially, the value decreases as the same rule with the complex viscosity and storage modulus of the composite at the same isothermal crystallization temperature. These results suggest that the interface compatibility of iPP/BC composites is greatly improved and the interface compatibility of the M-iPP/BC3 is better than the iPP/CO2.
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Microcrystalline cellulose (MCC) offers great potential to improve the mechanical and crystallization properties of isotactic polybutene-1 (iPB) because of its low cost, biodegradability, renewability and excellent mechanical properties. However, the compatibility of polar MCC and non-polar iPB is poor. In this study, maleic anhydride grafted polybutene (MAPB) was prepared by the solution method and was used as a compatibilizer in the fabrication of iPB/MCC composites by using a twin screw extruder. The ultimate tensile strength, tensile modulus, flexural strength, flexural modulus of the iPB/MCC composites increased by 3.1%, 16.5%, 10.7%, 6.5%, respectively, compared with that of pure iPB. With MAPB addition, these values increased by 17.2%, 31%, 17.5% and 10%, respectively, compared with that of pure iPB. The heat-distortion temperature and thermal-decomposition temperature of all composites increased with an increased MCC content. The non-isothermal crystallization of the iPB/MCC composites shows that MCC addition can promote iPB crystallization, because the non-isothermal crystallization curve of the composites moves toward a higher temperature, especially after MAPB addition. Scanning electron micrographs indicate that the compatibility of the iPB/MCC has been enhanced significantly.
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Matrine, a monomer of traditional Chinese medicine Sophora flavescens, is a potential drug for treatment of arrhythmia. The aim of the study is to elucidate the protective effects of matrine on arrhythmic rat induced by myocardial infarction (MI) and further explore underlying targets. Experiments were performed to investigate the effects of long-term oral administration of matrine on coronary ligation induced arrhythmia, measured in whole animals, via surface electrocardiogram (ECG). Whole-cell patch-clamp technique was used to record the action potential and potassium ionic currents in myocytes isolated from rat hearts. The cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) was measured using the scanning confocal microscopy. Mortality rate was 19/30 (63%) in MI group and 10/30 (33%) in matrine group (p<0.05). This represented a 1.9-fold reduction in long-term mortality rate. The prolonged action potential duration (APD) induced by MI were significantly shortened by long-term treatment of matrine. Matrine restored Kv4.2/I(to), Kir2.1/I(K1) in rat ventricular myocytes after MI. Abnormaly decreased [Ca(2+)](i) mediated by ischemia can be recovered by matrine. Our results suggested that long-term oral administration of matrine reduced arrhythmia and mortality. Electrophysiological experiment revealed that long-term matrine treatment played an important role in anti-arrhythmia through ionic mechanism. Knowledge of matrine from this work may provide insight into the development of new drugs for long-term myocardial infarction treatment.