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1.
Bioengineered ; 2021 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-34637694

RESUMO

We aimed to evaluate the protective effects of ulinastatin (UTI) on rats with acute lung injury induced by lipopolysaccharide (LPS) via the Toll like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-kappa B (NF-κB) signaling pathway. Forty-eight male Wistar rats were randomly divided into model, control, dexamethasone (DXM) and UTI groups. The body weight loss ratio and wet-to-dry weight ratio (W/D) of lung tissue were calculated at 10 h. The permeability of pulmonary vascular endothelium was detected by Evans blue method. Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1ß levels in bronchial lavage fluid were detected by enzyme-linked immunosorbent assay. Total cells and neutrophils were counted by microscopy. TLR4, MyD88 and NF-κB expressions were detected by Western blotting. Compared with model group, DXM and UTI groups had significantly higher body weights and lower W/D values (P<0.05). In DXM and UTI groups, the lung tissue structure was close to normal, inflammatory cell infiltration was alleviated, and hematoxylin-eosin staining scores were significantly lower than that of model group (P<0.05). Compared with model group, the concentrations of Evans blue, IL-1ß, IL-6 and TNF-α levels, and protein expressions of TLR4, MyD88 and NF-κB in DXM and UTI groups decreased significantly (P<0.05). UTI inhibits LPS-induced activation of the TLR4/MyD88/NF-κB signaling pathway, thereby alleviating inflammatory response and protecting against lung injury.

2.
Artigo em Inglês | MEDLINE | ID: mdl-34639622

RESUMO

Complete and high-resolution temperature observation data are important input parameters for agrometeorological disaster monitoring and ecosystem modelling. Due to the limitation of field meteorological observation conditions, observation data are commonly missing, and an appropriate data imputation method is necessary in meteorological data applications. In this paper, we focus on filling long gaps in meteorological observation data at field sites. A deep learning-based model, BiLSTM-I, is proposed to impute missing half-hourly temperature observations with high accuracy by considering temperature observations obtained manually at a low frequency. An encoder-decoder structure is adopted by BiLSTM-I, which is conducive to fully learning the potential distribution pattern of data. In addition, the BiLSTM-I model error function incorporates the difference between the final estimates and true observations. Therefore, the error function evaluates the imputation results more directly, and the model convergence error and the imputation accuracy are directly related, thus ensuring that the imputation error can be minimized at the time the model converges. The experimental analysis results show that the BiLSTM-I model designed in this paper is superior to other methods. For a test set with a time interval gap of 30 days, or a time interval gap of 60 days, the root mean square errors (RMSEs) remain stable, indicating the model's excellent generalization ability for different missing value gaps. Although the model is only applied to temperature data imputation in this study, it also has the potential to be applied to other meteorological dataset-filling scenarios.

3.
Nanomicro Lett ; 13(1): 205, 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34633586

RESUMO

There are plenty of issues need to be solved before the practical application of Li- and Mn-rich cathodes, including the detrimental voltage decay and mediocre rate capability, etc. Element doping can effectively solve the above problems, but cause the loss of capacity. The introduction of appropriate defects can compensate the capacity loss; however, it will lead to structural mismatch and stress accumulation. Herein, a three-in-one method that combines cation-polyanion co-doping, defect construction, and stress engineering is proposed. The co-doped Na+/SO42- can stabilize the layer framework and enhance the capacity and voltage stability. The induced defects would activate more reaction sites and promote the electrochemical performance. Meanwhile, the unique alternately distributed defect bands and crystal bands structure can alleviate the stress accumulation caused by changes of cell parameters upon cycling. Consequently, the modified sample retains a capacity of 273 mAh g-1 with a high-capacity retention of 94.1% after 100 cycles at 0.2 C, and 152 mAh g-1 after 1000 cycles at 2 C, the corresponding voltage attenuation is less than 0.907 mV per cycle.

4.
Chemistry ; 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34634149

RESUMO

Organic materials with multiple emissions tunable by external stimuli represent a great challenge. TTPyr, crystallizing in different polymorphs, shows a very rich photophyisics comprising excitation-dependent fluorescence and phosphorescence at ambient conditions, and mechanochromic and thermochromic behavior. Transformation among the different species has been followed by thermal and X-ray diffraction analysis and the emissive features interpreted through structural results and DFT/TDDFT calculations. Particularly intriguing is the polymorph obtained at high temperature, TTPyr(HT), whose non-centrosymmetric structure guarantees an SHG efficiency 10 times higher than that of standard urea. Its crystal packing, where only the TT units are strongly rigidified by π-π stacking interactions while the Pyr moieties possess partial conformational freedom, is responsible for the observed dual fluorescence. The potentialities of TTPyr for bioimaging have been successfully established.

5.
Hum Cell ; 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34635983

RESUMO

Fracture healing is a complex event with the involvement of many cell systems, cytokines, as well as mRNAs. Herein, we report the interactions among long noncoding RNA X-inactive specific transcript (XIST)/microRNA-135 (miR-135)/cAMP response element-binding protein 1 (CREB1) axis during fracture healing. We observed increased expression of XIST in patients with long-term unhealed fracture by microarray analysis. Subsequently, a mouse model with tibial fracture and a cell model using osteoblast-like MC3T3-E1 cells were generated. The XIST overexpression during fracture healing decreased proliferation and differentiation of MC3T3-E1 cells, while silencing of XIST facilitated MC3T3-E1 cell growth. Furthermore, miR-135 targeted CREB1 and negatively regulated its expression. XIST acted as a sponge for miR-135, thereby upregulating CREB1 and promoting the activity of the TNF-α/RANKL pathway. Transfection of miR-135 inhibitor or CREB1 overexpression blocked the stimulating effects of XIST knockdown on MC3T3-E1 cell growth. Besides, specific inhibitors of the TNF-α/RANKL pathway reversed the repressive role of XIST in cell osteogenic differentiation. All in all, these findings suggest that XIST knockdown induces the differentiation of osteoblast-like cells via regulation of the miR-135/CREB1/TNF-α/RANKL axis. XIST, as a consequence, represents an attractive therapeutic strategy to accelerate fracture healing.

6.
Artigo em Inglês | MEDLINE | ID: mdl-34619053

RESUMO

Background: To date, the clinical management of advanced hepatocellular carcinoma (HCC) patients remains tough and the mechanisms of E2F transcription factor 1 (E2F1) underlying HCC are obscure. Materials and Methods: Our study integrated datasets mined from several public databases to comprehensively understand the deregulated expression status of E2F1. Tissue microarrays and immunohistochemistry staining was used to validate E2F1 expression level. The prognostic value of E2F1 was assessed. In-depth subgroup analyses were implemented to compare the differentially expressed levels of E2F1 in HCC patients with various tumor stages. Functional enrichments were used to address the predominant targets of E2F1 and shedding light on their potential roles in HCC. Results: We confirmed the elevated expression of E2F1 in HCC. Subgroup analyses indicated that elevated E2F1 level was independent of various stages in HCC. E2F1 possessed moderate discriminatory capability in differentiating HCC patients from non-HCC controls. Elevated E2F1 correlated with Asian race, tumor classification, neoplasm histologic grade, eastern cancer oncology group, and plasma AFP levels. Furthermore, high E2F1 correlated with poor survival condition and pooled HR signified E2F1 as a risk factor for HCC. Enrichment analysis of differentially expressed genes, coexpressed genes, and putative targets of E2F1 emphasized the importance of cell cycle pathway, where CCNE1 and CCNA2 served as hub genes. Conclusions: We confirmed the upregulation of E2F1 and explored the prognostic value of E2F1 in HCC patients. Two putative targeted genes (CCNE1 and CCNA2) of E2F1 were identified for their potential roles in regulating cell cycle and promote antiapoptotic activity in HCC patients.

7.
mBio ; : e0213021, 2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34607455

RESUMO

Gram-negative bacteria have a multicomponent and constitutively active periplasmic chaperone system to ensure the quality control of their outer membrane proteins (OMPs). Recently, OMPs have been identified as a new class of vulnerable targets for antibiotic development, and therefore a comprehensive understanding of OMP quality control network components will be critical for discovering antimicrobials. Here, we demonstrate that the periplasmic chaperone Spy protects certain OMPs against protein-unfolding stress and can functionally compensate for other periplasmic chaperones, namely Skp and FkpA, in the Escherichia coli K-12 MG1655 strain. After extensive in vivo genetic experiments for functional characterization of Spy, we use nuclear magnetic resonance and circular dichroism spectroscopy to elucidate the mechanism by which Spy binds and folds two different OMPs. Along with holding OMP substrates in a dynamic conformational ensemble, Spy binding enables OmpX to form a partially folded ß-strand secondary structure. The bound OMP experiences temperature-dependent conformational exchange within the chaperone, pointing to a multitude of local dynamics. Our findings thus deepen the understanding of functional compensation among periplasmic chaperones during OMP biogenesis and will promote the development of innovative antimicrobials against pathogenic Gram-negative bacteria. IMPORTANCE Outer membrane proteins (OMPs) play critical roles in bacterial pathogenicity and provide a new niche for antibiotic development. A comprehensive understanding of the OMP quality control network will strongly impact antimicrobial discovery. Here, we systematically demonstrate that the periplasmic chaperone Spy has a role in maintaining the homeostasis of certain OMPs. Remarkably, Spy utilizes a unique chaperone mechanism to bind OmpX and allows it to form a partially folded ß-strand secondary structure in a dynamic exchange of conformations. This mechanism differs from that of other E. coli periplasmic chaperones such as Skp and SurA, both of which maintain OMPs in disordered conformations. Our study thus deepens the understanding of the complex OMP quality control system and highlights the differences in the mechanisms of ATP-independent chaperones.

8.
J Gen Intern Med ; 2021 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-34608564

RESUMO

BACKGROUND: Electronic consultation (eConsultation) offers a potential mechanism to increase access to specialty care, address knowledge gaps, and overcome therapeutic inertia in patients with type 2 diabetes (T2DM) being managed by primary care physicians (PCPs). OBJECTIVE: To develop and implement a system to provide unsolicited endocrinology eConsult for T2DM patients with HbA1c 8.5-10.5% managed by PCPs. DESIGN: Cluster-randomized matched cohort study with implementation evaluation. PARTICIPANTS: PCPs affiliated with Massachusetts General Hospital (MGH). INTERVENTIONS: Unsolicited endocrinology eConsultation. MAIN MEASURES: The primary clinical outcome was mean change in HbA1c at 6 months. Secondary process outcomes included referral completion rate, prescription rates of glucose-lowering medications, differences in rate of other management recommendations, change in all glucose-lowering medications, and number of face-to-face endocrinology visits. KEY RESULTS: 161 PCPs were randomly assigned to intervention (n=81) and control (n=80) arms. eConsultations were triggered on 130 patients from intervention arm PCPs. Intervention arm patients had a 0.89 (SD 1.45) decrease in HbA1c compared to 0.69 (SD 1.32) decrease in the control arm (p=0.28). There were significant differences in prescribing of glucose-lowering medications between arms. There was a 19.3% increase in patients prescribed GLP-1 RA or SGLT2i in the intervention arm compared to a 6.9% increase in control (p=0.003). There were also significant increases in prescription rates of metformin (3.1% vs -3.1%, p=0.03) and sulfonylureas (1.5% vs -6.9%, p=0.03). At 6-month follow-up, the intervention arm had 13 in-person endocrinology visits compared to 29 (p=0.012) in the control arm. PCPs were more likely to accept recommendations regarding adherence to or dose adjustment of current medications than initiation of new medications. CONCLUSIONS: The implementation of an unsolicited endocrinology eConsult system for patients with poorly controlled T2DM is feasible. Unsolicited eConsultation was associated with increased prescribing of glucose-lowering medications without significant difference in HbA1c. TRIAL REGISTRATION: Clinicaltrials.gov registration: NCT03542084.

9.
BMC Urol ; 21(1): 145, 2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34645421

RESUMO

BACKGROUND: Urinary bladder lymphangioma is a rare and benign lesion that is often causes symptoms related to irritation and urinary tract obstruction. Because a lymphangioma may resemble a true neoplasm of the urinary bladder clinically, the lesion must be removed for accurate histologic diagnosis and to rule out malignancy. CASE PRESENTATION: We present a case of a 40-year-old female who was evaluated for painless gross hematuria. Clinical and diagnostic work up revealed a sharply defined mass involving the wall and bulging into the cavity on the dome of the bladder. Partial cystectomy was performed and histologic findings were compatible with cavernous lymphangioma. The symptom of hematuria relieved after the procedure and the patient was in good status without evidence of recurrence by cystoscopy at follow-up 6 months later. CONCLUSIONS: Lymphangioma of the urinary bladder is treated with surgical excision and seems to have no recurrence once completely resected, but long-time follow-up may be needed.

10.
Appl Opt ; 60(21): 6080-6090, 2021 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-34613281

RESUMO

Cracks are one of the most common types of surface defects that occur on various engineering infrastructures. Visual-based crack detection is a challenging step due to the variation of size, shape, and appearance of cracks. Existing convolutional neural network (CNN)-based crack detection networks, typically using encoder-decoder architectures, may suffer from loss of spatial resolution in the high-to-low and low-to-high resolution processes, affecting the accuracy of prediction. Therefore, we propose HRNete, an enhanced version of a high-resolution network (HRNet), by removing the downsampling operation in the initial stage, reducing the number of high-resolution representation layers, using dilated convolution, and introducing hierarchical feature integration. Experiments show that the proposed HRNete with relatively few parameters can achieve more accuracy and robust performance than other recent approaches.

11.
PLoS One ; 16(10): e0253858, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34618818

RESUMO

Research indicates that Staphylococcus aureus colonization in the elderly with predisposing risks is associated with subsequent infection. However, the molecular epidemiology and risk factors for S. aureus colonization among residents and staff in nursing homes (NHs) in China remain unclear. A multicenter study was conducted in three NHs in Shanghai between September 2019 and October 2019. We explored the prevalence, molecular epidemiology, and risk factors for S. aureus colonization. All S. aureus isolates were characterized based on antimicrobial resistance, virulence genes, multilocus sequence typing (MLST), staphylococcus protein A (spa) typing, and staphylococcal cassette chromosome mec (SCCmec) typing. NH records were examined for potential risk factors for S. aureus colonization. S. aureus and methicillin-resistant S. aureus (MRSA) isolates were detected in 109 (100 residents and 9 staff, 19.8%, 109/551) and 28 (24 residents and 4 staff, 5.1%, 28/551) subjects among 496 residents and 55 staff screened, respectively. Compared to methicillin-susceptible S. aureus isolates, all 30 MRSA isolates had higher resistance rates to most antibiotics except minocycline, rifampicin, linezolid, vancomycin, and teicoplanin. Sequence type (ST) 1 (21.3%) was the most common sequence type, and t127 (20.5%) was the most common spa type among 122 S. aureus isolates. SCCmec type I (70%) was the dominant clone among all MRSA isolates. CC1 (26/122, 21.3%) was the predominant complex clone (CC), followed by CC398 (25/122, 20.5%), CC5 (20/122, 16.4%) and CC188 (18/122, 14.8%). Female sex (OR, 1.70; 95% CI, 1.04-2.79; P = 0.036) and invasive devices (OR, 2.19; 95% CI, 1.26-3.81; P = 0.006) were independently associated with S. aureus colonization.

12.
Neural Netw ; 144: 465-477, 2021 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-34600219

RESUMO

Deep convolutional neural network compression has attracted lots of attention due to the need to deploy accurate models on resource-constrained edge devices. Existing techniques mostly focus on compressing networks for image-level classification, and it is not clear if they generalize well on network architectures for more challenging pixel-level tasks, e.g., dense crowd counting or semantic segmentation. In this paper, we propose an adaptive correlation-driven sparsity learning (ACSL) framework for channel pruning that outperforms state-of-the-art methods on both image-level and pixel-level tasks. In our ACSL framework, we first quantify the data-dependent channel correlation information with a channel affinity matrix. Next, we leverage these inter-dependencies to induce sparsity into the channels with the introduced adaptive penalty strength. After removing the redundant channels, we obtain compact and efficient models, which have significantly less number of parameters while maintaining comparable performance with the original models. We demonstrate the advantages of our proposed approach on three popular vision tasks, i.e., dense crowd counting, semantic segmentation, and image-level classification. The experimental results demonstrate the superiority of our framework. In particular, for crowd counting on the Mall dataset, the proposed ACSL framework is able to reduce up to 94% parameters (VGG16-Decoder) and 84% FLOPs (ResNet101), while maintaining the same performance of (at times outperforming) the original model.

13.
Soft Matter ; 17(40): 8995-9007, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34611687

RESUMO

Biosilicification allows the formation of complex and delicate biogenic silica in near-neutral solutions under ambient conditions. Studies have revealed that, during biosilicification, basic amino acid residues and long-chain polyamines of organic substrates interact electrostatically with negatively charged silicate precursors in solution, catalyzing the polycondensation of silicic acid and accelerating the formation of silica. This mechanism has inspired researchers to explore polymers bearing chemical similarity with these organic matrices as cationic templates for biomimetic silicification. Such templates can be classified into two general categories based on the physical forms applied. One is a solution of water-soluble cationic polymers, either natural or synthetic, used as is for silicification. The other category includes various microscopically shaped entities made of cationic polymer-containing molecules, in the form of micelles, vesicles, crystalline aggregates, latex particles, and microgels. Combined with controlled polymerization and other techniques, these preorganized templates can be tailor designed in terms of sizes and morphologies to allow further expansion of properties and functions. In this review, notable research progress for both categories of silicification under biomimetic conditions is discussed. With the merits of silica and cationic polymers seamlessly integrated, the potential of such versatile nanocomposites in biomedical as well as energy and environmental applications is also briefly highlighted.

14.
Ultrason Sonochem ; 79: 105785, 2021 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-34653917

RESUMO

In order to investigate the effects of thermoultrasonic treatment (TUT) on the formation of colloidal micro-nano particles (MNPs) and the quality of halibut bone soup, nutrients, particle characteristics, and flavor characteristics were analyzed. The morphology of MNPs was studied using an optical microscope. Results showed that TUT could increase the nutrient content (total sugars, 22.15 mg/100 mL; water soluble proteins, 173.24 mg/mL; fatty acids, 1779.7 mg/100 mL; solids, 3.16 g/100 mL), reduce the particle size (605.92 nm) and interfacial tension. Meanwhile, TUT make the halibut bone soup has better emulsifying characteristics and stability. The contents of flavor substances, such as esters, 5'-nucleotides, organic acids in the halibut bone soup were more abundant, while the contents of hexanal and 1-octen-3-ol and fishy off-flavor were reduced in TUT group. The overall odor and taste outline were more harmonious. Therefore, TUT can be used in the production of high quality fish bone soup, and TUT could be considered as a good deep processing technology for halibut bone and improve economic efficiency.

15.
Ann Palliat Med ; 10(9): 9820-9829, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34628908

RESUMO

BACKGROUND: Lumbar degenerative disease (LDD) is a narrowing of the spinal canal and intervertebral foramina caused by aging and degeneration of lumbar spine tissue. Minimally invasive internal lumbar spine fixation is emerging in the treatment of LDD. However, no standard early rehabilitation protocol for orthopedic robot-assisted minimally invasive internal lumbar spine fixation exits. To investigate the effect of a nurse-led early rehabilitation program in the postoperative recovery of patients with lumbar degenerative lesions undergoing orthopedic robot-assisted minimally invasive lumbar internal fixation. METHODS: Eighty patients with minimally invasive orthopedic robot-assisted lumbar degenerative lesions admitted to our hospital between January 2019 and January 2021 were recruited to this study. The patients were randomly allocated to a control group (n=40), involving conventional care, and an observation group (n=38; 40 initially and 2 later excluded) including a nurse-led early rehabilitation program added on the basis of the control group. The primary outcomes were the general postoperative conditions, scores of daily living ability, the degree of low back pain and functional recovery. Participants were also compared in terms of their compliance with the care regimen and the incidence of complications. RESULTS: Participants in the observation group had a significantly shorter first time on the floor after surgery (P<0.001) and shorter hospital stay (P=0.003). Meanwhile, participants in the observation group had higher Barthel index (BI) scores (P=0.039), lower visual analogue scale (VAS) scores (P=0.028), and Oswestry disability index (ODI) scores (P=0.002) at 3 days postoperatively, and there was no difference in the three scores between the two groups at 1 month postoperatively (all P>0.05). The compliance of participants in the observation group was significantly higher than that of the control group (P<0.001). Participants in the observation group were less likely to experience constipation (P=0.043) and bloating (P=0.012) within 1 month after surgery. CONCLUSIONS: Implementation of a nurse-led early rehabilitation program in patients undergoing orthopedic robotic-assisted minimally invasive treatment of lumbar degenerative lesions can significantly improve patient compliance, significantly shorten postoperative flooring and hospitalization time, reduce the incidence of gastrointestinal adverse events, and accelerate postoperative recovery. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2100048698.


Assuntos
Papel do Profissional de Enfermagem , Fusão Vertebral , Humanos , Vértebras Lombares/cirurgia , Procedimentos Cirúrgicos Minimamente Invasivos , Resultado do Tratamento
16.
Cell Death Discov ; 7(1): 297, 2021 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-34663800

RESUMO

DNA (cytosine-5)-methyltransferase 3A (DNMT3A) mutations occur in ~20% of de novo acute myeloid leukemia (AML) patients, and >50% of these mutations in AML samples are heterozygous missense alterations within the methyltransferase domain at residue R882. DNMT3A R882 mutations in AML patients promote resistance to anthracycline chemotherapy and drive relapse. In this study, we performed high-throughput screening and identified that oridonin, an ent-kaurene diterpenoid extracted from the Chinese herb Rabdosia rubescens, inhibits DNMT3A R882 mutant leukemic cells at a low-micromolar concentration (IC50 = 2.1 µM) by activating both RIPK1-Caspase-8-Caspase-3-mediated apoptosis and RIPK1-RIPK3-MLKL-mediated necroptosis. The inhibitory effect of oridonin against DNMT3A R882 mutant leukemia cells can also be observed in vivo. Furthermore, oridonin inhibits clonal hematopoiesis of hematopoietic stem cells (HSCs) with Dnmt3a R878H mutation comparing to normal HSCs by inducing apoptosis and necroptosis. Overall, oridonin is a potential and promising drug candidate or lead compound targeting DNMT3A R882 mutation-driven clonal hematopoiesis and leukemia.

17.
Nanoscale ; 13(32): 13610-13616, 2021 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-34477635

RESUMO

Biofilm-related infections, such as dental plaque, chronic sinusitis, native valve endocarditis, and chronic airway infections in cystic fibrosis have brought serious suffering to patients and financial burden to society. Materials that can eliminate mature biofilms without developing drug resistance are promising tools to treat biofilm-related infections, and thus they are in urgent demand. Herein, we designed and readily prepared organic nanoparticles (NPs) with highly efficient photothermal conversion by harvesting energy via excited-state intramolecular motions and enlarging molar absorptivity. The photothermal NPs can sufficiently eliminate mature bacterial biofilms upon low-power near-infrared laser irradiation. NPs hold great promise for the rapid eradication of bacterial biofilms by photothermal therapy.


Assuntos
Antibacterianos , Nanopartículas , Antibacterianos/farmacologia , Biofilmes , Humanos , Terapia Fototérmica
18.
IEEE Trans Cybern ; PP2021 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-34495864

RESUMO

In this article, we consider an iterative adaptive dynamic programming (ADP) algorithm within the Hamiltonian-driven framework to solve the Hamilton-Jacobi-Bellman (HJB) equation for the infinite-horizon optimal control problem in continuous time for nonlinear systems. First, a novel function, ``min-Hamiltonian,'' is defined to capture the fundamental properties of the classical Hamiltonian. It is shown that both the HJB equation and the policy iteration (PI) algorithm can be formulated in terms of the min-Hamiltonian within the Hamiltonian-driven framework. Moreover, we develop an iterative ADP algorithm that takes into consideration the approximation errors during the policy evaluation step. We then derive a sufficient condition on the iterative value gradient to guarantee closed-loop stability of the equilibrium point as well as convergence to the optimal value. A model-free extension based on an off-policy reinforcement learning (RL) technique is also provided. Finally, numerical results illustrate the efficacy of the proposed framework.

19.
Comput Math Methods Med ; 2021: 2973108, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34484414

RESUMO

The X-ray radiation from computed tomography (CT) brought us the potential risk. Simply decreasing the dose makes the CT images noisy and diagnostic performance compromised. Here, we develop a novel denoising low-dose CT image method. Our framework is based on an improved generative adversarial network coupling with the hybrid loss function, including the adversarial loss, perceptual loss, sharpness loss, and structural similarity loss. Among the loss function terms, perceptual loss and structural similarity loss are made use of to preserve textural details, and sharpness loss can make reconstruction images clear. The adversarial loss can sharp the boundary regions. The results of experiments show the proposed method can effectively remove noise and artifacts better than the state-of-the-art methods in the aspects of the visual effect, the quantitative measurements, and the texture details.

20.
Zhongguo Zhong Yao Za Zhi ; 46(15): 3886-3892, 2021 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-34472264

RESUMO

This study established high-performance liquid chromatography(HPLC) fingerprints of Chinese medicines derived from Apocynum venetum and Poacynum pictum in Xinjiang and explored their composition differences with the combination of content determination, similarity analysis, cluster analysis and principal component analysis. The HPLC conditions included Phenomenex Kinetex C_(18) column(4.6 mm ×100 mm, 2.6 µm), acetonitrile-0.01% trifluoroacetic acid aqueous solution as mobile phase, gradient elution, flow rate of 0.6 mL·min~(-1), detection wavelength of 281 nm and column temperature of 25 ℃. The content of chlorogenic acid, quercetin-3-O-sophoroside, rutin, hyperin, isoquercitrin, trifolin and astragalin was determined in 31 batches of medicinal materials, and fingerprint research and chemometric analysis were performed with Similarity Evaluation System for Chromatographic Fingerprint of Traditional Chinese Medicine(Version 2004 A) and SPSS 21.0. In the Chinese Pharmacopoeia 2020, the quality of Apocyni Veneti Folium is controlled by character identification, microscopic identification, thin layer chromatography identification and quantitative determination of hyperin. There were 21 common peaks of A. venetum and P. pictum in the HPLC fingerprints, 5 of which were identified as chlorogenic acid, hyperin, isoquercitrin, trifolin and astragalin, with their content also determined. Except for 3 batches of medicinal materials, the similarity of other 28 batches was higher than 0.83, indicating good similarity. Two categories were formed in the cluster analysis based on content determination, which showed that some differences existed in similarities between different regions of Xinjiang. The medicinal materials were ranked by quality with principal component analysis, and the results indicated that the top 15 all came from northern Xinjiang. The quality difference of A. venetum and P. pictum had a correlation with the place of origin. This study provides a reference for the analysis and evaluation of A. venetum and P. pictum from different habitats and the selection of introduction and cultivation areas.


Assuntos
Apocynum , Medicamentos de Ervas Chinesas , China , Cromatografia Líquida de Alta Pressão , Medicina Tradicional Chinesa
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