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1.
ACS Chem Neurosci ; 13(2): 177-184, 2022 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-35000390

RESUMO

Methylations in living cells are methyl groups attached to amino acids, DNA, RNA, and so on. However, their biochemical roles have not been fully defined. A theory has been postulated that methylation leads to hyperconjugation, and the electron-donating feature weakens a nearby chemical bond, which increases the bond length of C4-N4 of 5-methylcytosine, therefore weakening the C4-N4 bond and resulting in stronger protonation or hydrogen bonding of the N4 nitrogen atom. Protonation can give rise to the generation of mutagenic and carcinogenic strong acids such as HCl, which are also capable of solubilizing stressful, insoluble, and stiff salts. Insoluble and rigid salts such as calcium oxalate and/or calcium phosphate were recently proposed as a primary cause of some neurodegenerative disorders. Protonation of nitrogen atoms in 5-methylcytosine enhances the interaction with negatively charged phosphate groups and contributes to the formation of compact heterochromatin. The electronegativity of the oxygen atoms in the modifications of 5-hydroxymethylcytosine or 5-formylcytosine can shorten the lengths of adjacent bonds with no increase of cation affinity in N4. The carboxyl group in 5-carboxylcytosine is a weak acid capable of antagonizing mutagenic HCl and modestly helping solubilize insoluble salts. Electron delocalization of the methyl group in N4-methylcytosine results in a lower affinity of N4 to cations. The positive charge at N3 in the resonance structure of 3-methylcytosine is lessened by the electron-donating attribute of the methyl group attached to the N3 atom, consequently reducing acid formation. The electron delocalization of three methyl groups decreases the positive charge in the amino nitrogen in the side group of lysine 4 in histone H3, weakening interactions with phosphate groups and consequently activating gene expression. The carbonyl oxygen in 8-oxo-7,8-dihydroguanine draws protons and accumulates HCl, accounting for its moderate mutation propensity and potential capacity to solubilize stiff salts. The biochemical insight will further our understanding on the crosstalk of genetics and epigenetics in the etiology of neurodegenerative diseases.

2.
J Hazard Mater ; 423(Pt A): 127124, 2022 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-34523472

RESUMO

Magnetic spinel ferrite (CuFe2O4) has been applied to catalyze ozone for treating the practical shale gas produced water (PW) in our previous study. In this work, CuFe2O4/titanium nanotubes (TNTs) catalyst was successfully prepared by an impregnation-calcination method. Characterization results revealed that the crystal form of CuFe2O4 was bound to the surface of TNTs, the particle size is much smaller than the pure CuFe2O4 crystal particle, which could weaken the influence of the internal diffusion process on its catalytic efficiency. The experimental results showed that the removal ratio of CODCr in the CuFe2O4/TNTs/O3 system was approximately 14% higher than that of the CuFe2O4/O3 system. The dissolution of metal elements decreased to one-third that of the CuFe2O4/O3 system. The inhibition ratio of PW on the growth of E. coli K12 decreased 68% after the CuFe2O4/TNTs catalytic oxidation process. Experimental results of complete capture experiments illustrated that the yield of HO• of the CuFe2O4/TNTs/O3 system was 10-19% higher than that of the CuFe2O4/O3 system. The elemental valence analysis revealed that the transition of Cu(II)-Cu(III) and Fe(II)-Fe(III) coexisted in the catalytic system. Besides, the surface hydroxyl groups promoted the electron transfer process and enhanced the ozone adsorption affinity. The proposed catalytic mechanisms of the CuFe2O4/TNTs/O3 system were proposed via the above analysis.


Assuntos
Nanotubos , Ozônio , Poluentes Químicos da Água , Catálise , Escherichia coli , Compostos Férricos , Fenômenos Magnéticos , Gás Natural , Titânio , Água
3.
J Environ Manage ; 302(Pt B): 114111, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34800771

RESUMO

In this study, the visible-light-induced intimately coupled photocatalysis and biodegradation (ICPB) technology was fabricated using the TiO2/bagasse cellulose composite as the carrier and Phanerochaete mixed activated sludge as the biological source. The ICPB degradation effect of elemental chlorine free (ECF) bleaching wastewater was evaluated via the response surface design. Then, the wastewater was characterized, including absorbable organic halogen (AOX), dissolved organic carbon (DOC), chemical oxygen demand (COD), chroma, pH, suspended solids, and the organic compound changes in wastewater were analyzed by fourier transform infrared spectroscopy (FT-IR). Under the optimal conditions of pH 7, carrier filling rate of 5%, aeration rate of 2 L/min, and reaction time of 7 h, the degradation efficiencies of AOX, COD, and DOC were 95%, 91%, and 82%, respectively. The X-ray photoelectron spectroscopy (XPS) results of the ICPB carrier after the reaction were almost identical to those before the reaction. The biomass and its activity on the ICPB system were analyzed by the dominant bacteria during degradation (Curaneotrichosporon, Paenibacillus, Cellulonas, Phanerochaete, Dechlorobacter, Rhodotorula, Sphingobacterium, and Ruminiclostridium), which had a good degradation effect on wastewater. This study affords a novel method for the degradation of ECF bleaching wastewater and a new idea for ICPB technology optimization.


Assuntos
Águas Residuárias , Biodegradação Ambiental , Espectroscopia de Infravermelho com Transformada de Fourier , Titânio
4.
Talanta ; 236: 122847, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635237

RESUMO

Nucleocapsid protein (N protein) is the most abundant protein in SARS-CoV2 and is highly conserved, and there are no homologous proteins in the human body, making it an ideal biomarker for the early diagnosis of SARS-CoV2. However, early detection of clinical specimens for SARS-CoV2 remains a challenge due to false-negative results with viral RNA and host antibodies based testing. In this manuscript, a microfluidic chip with femtoliter-sized wells was fabricated for the sensitive digital detection of N protein. Briefly, ß-galactosidase (ß-Gal)-linked antibody/N protein/aptamer immunocomplexes were formed on magnetic beads (MBs). Afterwards, the MBs and ß-Gal substrate fluorescein-di-ß-d-galactopyranoside (FDG) were injected into the chip together. Each well of the chip would only hold one MB as confined by the diameter of the wells. The MBs in the wells were sealed by fluorocarbon oil, which confines the fluorescent (FL) product generated from the reaction between ß-Gal and FDG in the individual femtoliter-sized well and creates a locally high concentration of the FL product. The FL images of the wells were acquired using a conventional inverted FL microscope. The number of FL wells with MBs (FL wells number) and the number of wells with MBs (MBs wells number) were counted, respectively. The percentage of FL wells was calculated by dividing (FL wells number) by (MBs wells number). The higher the percentage of FL wells, the higher the N protein concentration. The detection limit of this digital method for N protein was 33.28 pg/mL, which was 300 times lower than traditional double-antibody sandwich based enzyme-linked immunosorbent assay (ELISA).


Assuntos
Imunoensaio/métodos , Proteínas do Nucleocapsídeo , SARS-CoV-2 , Anticorpos , COVID-19/diagnóstico , Humanos , Proteínas do Nucleocapsídeo/isolamento & purificação , RNA Viral
5.
Mol Cancer ; 20(1): 161, 2021 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-34876132

RESUMO

BACKGROUND: Circular RNAs (circRNAs), a class of noncoding RNAs (ncRNAs), may modulate gene expression by binding to miRNAs. Additionally, recent studies show that circRNAs participate in some pathological processes. However, there is a large gap in the knowledge about circDOCK1 expression and its biological functions in osteogenic sarcoma (OS). METHODS: Differentially expressed circRNAs in OS cell lines and tissues were identified by circRNA microarray analysis and quantitative real-time PCR (qRT-PCR). To explore the actions of circDOCK1 in vivo and in vitro, circDOCK1 was knocked down or overexpressed. To assess the binding and regulatory associations among miR-339-3p, circDOCK1 and IGF1R, we performed rescue experiments, RNA immunoprecipitation (RIP), RNA pulldown assays and dual-luciferase assays. Moreover, we performed apoptosis assays to reveal the regulatory effects of the circDOCK1/miR-339-3p/IGF1R axis on cisplatin sensitivity. RESULTS: CircDOCK1 expression remained stable in the cytoplasm and was higher in OS tissues and cells than in the corresponding controls. Overexpression of circDOCK1 increased oncogenicity in vivo and malignant transformation in vitro. In the U2OS and MG63 cell lines, circDOCK1 modulated tumor progression by regulating IGF1R through sponging of miR-339-3p. Additionally, in the U2OS/DDP and MG63/DDP cell lines, cisplatin sensitivity was regulated by circDOCK1 via the miR-339-3p/IGF1R axis. CONCLUSIONS: CircDOCK1 can promote progression and regulate cisplatin sensitivity in OS via the miR-339-3p/IGF1R axis. Thus, the circDOCK1/miR-339-3p/IGF1R axis may be a key mechanism and therapeutic target in OS.

6.
J Sep Sci ; 2021 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-34889052

RESUMO

Cinnarizine (CNZ) is a weak base, which can produce supersaturation and precipitation during gastrointestinal transit, affecting its absorption in vivo. Therefore, it is necessary to investigate whether the oral bioavailability of cinnarizine can be improved after co-administration with precipitation inhibitors or not. In order to evaluate the pharmacokinetic behavior of cinnarizine in rats, a simple, rapid, sensitive, and environmentally friendly supercritical fluid chromatography-tandem mass spectrometric method was established and validated. In this method, flunarizine, a structural analogue of cinnarizine, was selected as the internal standard, and cinnarizine was extracted from rat plasma using evaporation-free liquid-liquid extraction method. The analytes were separated on a TorusTM 1-AA column (3.0 mm × 100 mm, 1.7 µm) within 2.0 min, using a gradient elution procedure. The transitions of cinnarizine and flunarizine were m/z 369.1 → 167.1 and m/z 405.1 → 203.1, respectively. Cinnarizine showed good linear correlation in the range of 1-500 ng/mL with a lower limit of quantification (LLOQ) of 1 ng/mL. The intra-day and inter-day precision and accuracy of all quality control samples were within ±15%. This high-throughput, accurate, sensitive, and reproducible method has been successfully applied to study the effects of the precipitation inhibitor cinnarizine on the pharmacokinetics in rats. This article is protected by copyright. All rights reserved.

7.
Nanomicro Lett ; 14(1): 14, 2021 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-34870784

RESUMO

Here, this work presents an air-stable ultrabright inverted organic light-emitting device (OLED) by using zinc ion-chelated polyethylenimine (PEI) as electron injection layer. The zinc chelation is demonstrated to increase the conductivity of the PEI by three orders of magnitude and passivate the polar amine groups. With these physicochemical properties, the inverted OLED shows a record-high external quantum efficiency of 10.0% at a high brightness of 45,610 cd m-2 and can deliver a maximum brightness of 121,865 cd m-2. Besides, the inverted OLED is also demonstrated to possess an excellent air stability (humidity, 35%) with a half-brightness operating time of 541 h @ 1000 cd m-2 without any protection nor encapsulation.

8.
Artigo em Inglês | MEDLINE | ID: mdl-34874870

RESUMO

This article proposes two adaptive asymptotic tracking control schemes for a class of interconnected systems with unmodeled dynamics and prescribed performance. By applying an inherent property of radial basis function (RBF) neural networks (NNs), the design difficulties aroused from the unknown interactions among subsystems and unmodeled dynamics are overcome. Then, in order to ensure that the tracking errors can be suppressed in the specified range, the constrained control problem is transformed into the stabilization problem by using an auxiliary function. Based on the adaptive backstepping method, a time-triggered controller is constructed. It is proven that under the framework of Barbalat's lemma, all the variables in the closed-loop system are bounded and the tracking errors are further ensured to converge to zero asymptotically. Furthermore, the event-triggered strategy with a variable threshold is adopted to make more precise control such that the better system performance can be obtained, which reduces the system communication burden under the condition of limited communication resources. Finally, an illustrative example is provided to demonstrate the effectiveness of the proposed control scheme.

9.
Mater Sci Eng C Mater Biol Appl ; 131: 112517, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34857298

RESUMO

At present, membrane fouling is a thorny issue that limits the development of polyvinylidene fluoride (PVDF) composite membrane, which seriously affects its separation performance and service lifespan. Herein, an imidazole-functionalized graphene oxide (Im-GO) with hydrophilicity and antibacterial performance was synthesized, and it was used as a modifier to improve the anti-organic fouling and antibacterial properties of PVDF membrane. The anti-organic fouling test showed that the maximum flux recovery ratios against bovine serum albumin and humic acid were 88.9% and 94.5%, respectively. Conspicuously, the grafted imidazole groups could effectively prevent the bacteria from growing on the membrane surface. It was gratifying that the antibacterial modifier Im-GO was almost not lost from the hybrid membranes even by the ultrasonic treatment, which was different from the conventional release-killing antibacterial agents. Owing to the long-term anti-organic fouling and antibacterial properties, Im-GO/PVDF hybrid membranes exhibit a great application potential in the fields of rough separation and concentration of biomedical products.

10.
Medicine (Baltimore) ; 100(51): e28109, 2021 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-34941052

RESUMO

ABSTRACT: To evaluate diagnostic performance of perfusion-weighted imaging in differentiating benign from malignant breast lesions, and the correlation between the prognostic factors/subtypes of breast cancers and the perfusion parameters.A total of 76 patients (59 cases with breast cancer) were included in our study. The Wilcoxon rank-sum test or the Kruskal-Wallis test were adopted for comparisons according to the dichotomous histopathologic prognostic factors or immunohistochemical subtypes. Receiver operating characteristic curves were used to determine the area under the curve (AUC) values for perfusion parameters to assess discrimination ability.Confirming by pathology after operation, the percentage of benign lesions is 22.37% (17/76), malignant lesions (breast cancer) is 77.63% (59/76). According to puncture and pathological findings after operation, the standard of the molecular subtypes of breast cancer, triple negative account for 13.6% (8/59), non-triple negative account for 86.4% (51/59). The value of mean Ktrans and Kep were lower in benign than malignant lesions (P ≤ .001). The AUC of the 3 indicators are significantly improved after adjusting for age (AUC = 0.858 for Ktrans, AUC = 0.926 for Kep, and AUC = 0.827 for Ve). Moreover, the Ve index showed better discrimination performance than other indicators in identifying patients with triple-negative subtypes. Similarly, the identification ability came to the highest when combing Kep and Ve.Perfusion parameters on dynamic enhanced magnetic resonance imaging are statistically significant in distinguishing benign from malignant breast lesion, and may potentially be used as biomarkers in discriminating patients with triple-negative molecular subtypes of breast cancer.

11.
Mater Horiz ; 8(12): 3457-3467, 2021 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-34755162

RESUMO

The production of reactive oxygen species (ROS) to elicit lethal cellular oxidative damage is an attractive pathway to kill cancer cells, but it is still hindered by the low ROS production efficiency of the current methods. Herein, we design a one-dimensional (1D) π-π conjugated ferriporphyrin covalent organic framework on carbon nanotubes (COF-CNT) for activating nanocatalytic and photodynamic cancer therapy. The COF-CNT can catalyze the generation of ROS and O2 in the tumor microenvironment (TME), and realize a self-oxygen-supplying PDT under near-infrared (NIR) light irradiation, simultaneously. With the full electron delocalization at the atomically dispersed active center, the catalytic activity of COF-CNT with extended π-conjugation is 6.8 times higher than that without the π-conjugated structure. The formation of the COF structure with π-π conjugation also changes the density of states (DOS) profile of its functional building block for improving PDT. Through one single treatment, it successfully achieves complete tumor regression of 4T1 breast carcinoma in mice with immunoregulation.

12.
J Org Chem ; 86(21): 15276-15283, 2021 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-34605241

RESUMO

A computational study was performed to explore the possible mechanisms of ß-isocinchonine-catalyzed asymmetric C(sp2)-H allylation of trisubstituted allenoates using Morita-Baylis-Hillman (MBH) carbonates for synthesis of axially chiral tetrasubstituted allenoates. The calculated results indicate that the most energetically favorable pathway includes (1) nucleophilic attack on MBH carbonate by ß-isocinchonine, (2) BocO- dissociation, (3) stereoselective formation of the C-C bond, and (4) regeneration of the catalyst. By tracking the orbital overlap/interaction changes, the half shoulder-to-head orbital overlap mode can be smoothly switched to a head-to-head orbital overlap mode for the key C-C σ bond formation, which is also identified as the stereoselectivity-determining process. Further distortion/interaction, noncovalent interaction (NCI), and atom-in-molecule (AIM) analyses demonstrate that C-H···O and C-H···π interactions should be key for controlling the axial and central chirality. This work would be useful for rational design of organocatalytic allylic alkylation reactions for synthesis of axially chiral compounds in the future.

13.
Neurosurg Rev ; 2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34643829

RESUMO

Hematoma growth (HG) affects the prognosis of patients with spontaneous intracranial hematoma (ICH), but there is still a lack of evidence about the effects of aspirin (acetylsalicylic acid, ASA) on HG in patients with severe ICH. This study retrospectively analyzed patients with severe ICH who met the inclusion and exclusion criteria in Beijing Tiantan Hospital, Capital Medical University, between January 1, 2015, and July 31, 2019. Severe ICH patients were divided into ASA group and nASA groups according to ASA usage, and the incidence of HG between the groups was compared. Univariate analysis was performed by the Mann-Whitney U test, chi-square test, or Fisher exact test. Multivariate logistic regression analysis was used to analyze the impact of ASA on HG and to screen for risk factors of HG. In total, 221 patients with severe ICH were consecutively enrolled in this study. There were 72 (32.6%) patients in the ASA group and 149 patients in the nASA group. Although the incidence of HG in the nASA group was higher than that in the ASA group (34.9% VS 22.2%, p = 0.056), ASA did not significantly affect the occurrence of HG (p = 0.285) after adjusting for initial hematoma volume, high blood pressure at admission, coronary heart disease, and GCS at admission. In addition, we found that high blood pressure at admission was a risk factor for HG. Prior ASA does not increase the incidence of HG in severe ICH patients, and high blood pressure at admission is a risk factor for HG.

14.
Mol Biol Rep ; 48(11): 7633-7635, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34643928

RESUMO

Malignancies are caused by genetic or environmental factors. Esophageal carcinoma can be triggered by consumption of hot food and beverages. Here we propose that high temperature is one of the culprits and it leads to DNA denaturation. Subsequently the exposed hydrogen bonding acceptors in single stranded DNA attract protons which enhance the formation of mutagenic and carcinogenic strong acids such as HCl. Faster mutation of single-stranded DNA viruses than that of double-stranded DNA viruses lends support to this theory.

15.
Front Hum Neurosci ; 15: 706270, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34658814

RESUMO

Accurate detection of driving fatigue is helpful in significantly reducing the rate of road traffic accidents. Electroencephalogram (EEG) based methods are proven to be efficient to evaluate mental fatigue. Due to its high non-linearity, as well as significant individual differences, how to perform EEG fatigue mental state evaluation across different subjects still keeps challenging. In this study, we propose a Label-based Alignment Multi-Source Domain Adaptation (LA-MSDA) for cross-subject EEG fatigue mental state evaluation. Specifically, LA-MSDA considers the local feature distributions of relevant labels between different domains, which efficiently eliminates the negative impact of significant individual differences by aligning label-based feature distributions. In addition, the strategy of global optimization is introduced to address the classifier confusion decision boundary issues and improve the generalization ability of LA-MSDA. Experimental results show LA-MSDA can achieve remarkable results on EEG-based fatigue mental state evaluation across subjects, which is expected to have wide application prospects in practical brain-computer interaction (BCI), such as online monitoring of driver fatigue, or assisting in the development of on-board safety systems.

16.
J Biosci Bioeng ; 2021 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-34690061

RESUMO

The objectives of this study were to investigate the medicinal mushroom Inonotus obliquus on the production of polysaccharides and changes of extracellular lignocellulolytic enzymes during submerged fermentation using alkali-treated birch sawdust as substrate. Meanwhile, in order to explore the degradation mode of lignocellulose in alkali-treated birch sawdust, degradation analysis of three components of lignocellulose was carried out. The fungus process in alkali-treated birch sawdust medium resulted in a higher degradation rate of cellulose, hemicellulose, and lignin of 39.24%, 51.00% and 31.3% after 11 days of submerged fermentation by the mycelium of I. obliquus, respectively. Maximal polysaccharide production and α-glucosidase inhibition rate determined in the alkali-treated birch sawdust medium were 6.93 mg/mL and 55.80%, while they were 4.98 mg/mL and 27.89% in the control. Moreover, high activities of laccase (51.95 IU/mL), CMCase (1.35 IU/mL), filter paper activity (0.50 IU/mL) and ß-glucosidase (0.55 IU/mL) were observed in alkali-treated birch sawdust medium, respectively. The results demonstrated that the addition of alkali-treated birch sawdust could promote the yield and α-glucosidase inhibition activity of polysaccharides and induce the production of cellulase and xylanase, indicating that alkali pretreatment was conducive to utilization of birch sawdust by I. obliquus.

17.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 38(5): 919-931, 2021 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-34713660

RESUMO

This paper analyzed literatures on the specificity study of electroencephalogram (EEG) in the diagnosis of depression since 2010 to 2020, summarized the recent research directions in this field and prospected the future research hotspots at home and abroad. Based on databases of China National Knowledge Infrastructure (CNKI) and the core collection of Web of Science (WOS), CiteSpace software was used to analyze the relevant literatures in this research field. The number of relevant literatures, countries, authors, research institutions, key words, cited literatures and periodicals related to this research were analyzed, respectively, to explore research hotspots and development trends in this field. A total of 2 155 articles were included in the WOS database. The most published institution was the University of Toronto, the most published country was the United States, China occupied the third place, and the hot keywords were anxiety, disorder, brain and so on. A total of 529 literatures were included and analyzed in CNKI database. The institution with the most publications was the Mental Health Center of West China Hospital of Sichuan University, and the hot keywords were EEG signal, event-related potential, convolutional neural network, schizophrenia, etc . This study finds that EEG study of depression is developing rapidly at home and abroad. Research directions in the world mainly focus on exploring the characteristics of spontaneous EEG rhythm and nonlinear dynamic parameters during sleep in depressed patients. In addition, synchronous transcranial magnetic stimulation (TMS) and EEG technologies also attract much attention abroad, and the future research hotspot will be on the mechanism of EEG on patients with major depression. Domestic research directions mainly focus on the classification of resting EEG and the control study of resting EEG power spectrum entropy in patients with schizophrenia and depression, and future research hotspot is the basic and clinical EEG study of depressed patients complicated with anxiety.


Assuntos
Depressão , Publicações , Bases de Dados Factuais , Depressão/diagnóstico , Eletroencefalografia , Humanos , Software , Estados Unidos
18.
Neurosurg Rev ; 2021 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-34714418

RESUMO

The 30-day mortality rate of spontaneous cerebral hemorrhage (ICH) is approximately 30-50%. Surgery may improve the prognosis of patients with severe ICH. However, ICH survivors after surgery still face the risks of postoperative intracranial rebleeding (PIB), and clinical tools that accurately predict the risk of PIB occurrence are not available. Therefore, a retrospective study was performed. The population was divided into two groups according to the occurrence of PIB. Univariate and multivariate logistic regression analyses were performed to screen risk factors for PIB. Next, an early PIB risk nomogram prediction model was constructed. In addition, the impact of PIB on the prognosis of ICH was evaluated. In total, 150 ICH patients were continuously enrolled in this study; 21 patients suffered from PIB, and the overall incidence of PIB was 14.0% (21/150). Coronary heart disease history, a lower GCS score, and subarachnoid hemorrhage absence were screened as risk factors for early PIB. The early PIB risk nomogram showed good calibration and discrimination with a concordance index of 0.807 (95% confidence interval (CI), 0.715-0.899), which was confirmed to be 0.788 through bootstrapping validation. In addition, a significant difference in discharged GOS scores (P = 0.043) was observed between the PIB group and the n-PIB group. These results showed that a history of coronary heart disease, a lower GCS score, and absence of subarachnoid hemorrhage were risk factors for early PIB. In addition, the early PIB risk nomogram prediction model exhibits good discrimination and calibration. The occurrence of PIB could reduce the prognosis of ICH patients.

19.
Neural Netw ; 144: 279-296, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34543854

RESUMO

Tobit models (also called as "censored regression models" or classified as "sample selection models" in microeconometrics) have been widely applied to microeconometric problems with censored outcomes. However, due to their linear parametric settings and restrictive normality assumptions, the traditional Tobit models fail to capture the pervading nonlinearities and thus may be inadequate for microeconometric analysis with large-scale datasets. This paper proposes two novel deep neural networks for Tobit problems and explores machine learning approaches in the context of microeconometric modeling. We connect the censored outputs in Tobit models with some deep learning techniques, which are thought to be unrelated to microeconometrics, and use the rectified linear unit activation and a particularly designed network structure to implement the censored output mechanisms and realize the underlying econometric conceptions. The benchmark Tobit-I and Tobit-II models are then reformulated as two carefully designed deep feedforward neural networks named deep Tobit-I network and deep Tobit-II network, respectively. A novel significance testing method is developed based on the proposed networks. Compared with the traditional models, our networks with deep structures can effectively describe the underlying highly nonlinear relationships and achieve considerable improvements in fitting and prediction. With the novel testing method, the proposed networks enable highly accurate and sophisticated econometric analysis with minimal random assumptions. The encouraging numerical experiments on synthetic and realistic datasets demonstrate the utility and advantages of the proposed method.


Assuntos
Aprendizado de Máquina , Redes Neurais de Computação
20.
Materials (Basel) ; 14(17)2021 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-34500875

RESUMO

To solve the problem of poor corrosion and wear resistance of Mg-Li alloys, Fe-based amorphous coatings were prepared by high velocity oxygen-fuel spraying technology (HVOF) on the LA141 magnesium alloy substrate with a Ni60 intermediate layer. The microstructure and performance of Fe-based amorphous coatings with different oxygen flow and kerosene flow were characterized and analyzed. The results demonstrate that there is an optimal oxygen/kerosene ratio where the porosity of Fe-based amorphous coating is the lowest. Moreover, the amorphous content increases with the decrease in the oxygen/kerosene ratio. In particular, when the oxygen flow is 53.8 m3/h and the kerosene flow is 26.5 L/h, the Fe-based amorphous coating possesses the lowest porosity (0.87%), the highest hardness (801 HV0.1), the highest bonding strength (56.9 MPa), and an excellent corrosion and wear resistance. Additionally, it can be seen that the Fe-based amorphous coating is composed of amorphous splats and amorphous oxides, but the Ni60 intermediate layer exhibits an amorphous and crystalline multi-phase structure. The high bonding strength of the coating is attributed to the low porosity of Fe-based amorphous coating and the localized metallurgical bonding between different layers. Finally, the mechanisms on corrosion and wear of Fe-based amorphous coatings are also discussed.

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