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1.
Nat Plants ; 10(5): 743-748, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38600265

RESUMO

NARROW LEAF1 (NAL1) exerts a multifaceted influence on leaf morphology and crop yield. Recent crystal study proposed that histidine 233 (H233) is part of the catalytic triad. Here we report that unlike suggested previously, H234 instead of H233 is a component of the catalytic triad alongside residues D291 and S385 in NAL1. Remarkably, residue 233 unexpectedly plays a pivotal role in regulating NAL1's proteolytic activity. These findings establish a strong foundation for utilizing NAL1 in breeding programs aimed at improving crop yield.


Assuntos
Oryza , Proteínas de Plantas , Oryza/genética , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Folhas de Planta/metabolismo , Folhas de Planta/genética , Histidina/metabolismo
2.
Nucleic Acids Res ; 52(6): 3406-3418, 2024 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-38412313

RESUMO

RNA helicases function as versatile enzymes primarily responsible for remodeling RNA secondary structures and organizing ribonucleoprotein complexes. In our study, we conducted a systematic analysis of the helicase-related activities of Escherichia coli HrpA and presented the structures of both its apo form and its complex bound with both conventional and non-canonical DNAs. Our findings reveal that HrpA exhibits NTP hydrolysis activity and binds to ssDNA and ssRNA in distinct sequence-dependent manners. While the helicase core plays an essential role in unwinding RNA/RNA and RNA/DNA duplexes, the N-terminal extension in HrpA, consisting of three helices referred to as the APHB domain, is crucial for ssDNA binding and RNA/DNA duplex unwinding. Importantly, the APHB domain is implicated in binding to non-canonical DNA structures such as G-quadruplex and i-motif, and this report presents the first solved i-motif-helicase complex. This research not only provides comprehensive insights into the multifaceted roles of HrpA as an RNA helicase but also establishes a foundation for further investigations into the recognition and functional implications of i-motif DNA structures in various biological processes.


Assuntos
DNA Helicases , Proteínas de Escherichia coli , Sequência de Aminoácidos , DNA/química , DNA Helicases/metabolismo , DNA de Cadeia Simples/genética , Escherichia coli/metabolismo , RNA/química , RNA Helicases/genética , Proteínas de Escherichia coli/metabolismo
4.
Materials (Basel) ; 16(21)2023 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-37959481

RESUMO

Extracting iron while minimizing the health and environmental risks associated with arsenic contamination necessitates the removal of arsenic from arsenic-bearing iron ores to ensure a safe and sustainable supply of this metal for industries. The beneficiation of iron minerals and arsenic-bearing minerals from arsenic-bearing iron ores with a calcification-magnetizing roasting and low-intensity magnetic separation (CMR-LMS) process is investigated in this work. The results show that the process is successful in extracting iron minerals and eliminating arsenic-containing minerals. The roasting involves two key steps: calcification and magnetizing, which change hematite and goethite into magnetite and arsenic-bearing minerals into calcium arsenates. The process's separation efficiency of the CMR-LMS is closely linked to the parameters such as roasting temperature, roasting time, coke, alkalinity, and the liberation of gangue minerals from iron minerals. Through grinding and secondary magnetic separation, the iron minerals and gangue components, as well as arsenic, in roasted sand can be further separated. The optimum procedure results in a high-grade iron concentrate with an iron assay of 65.65%, an Fe recovery rate of 80.07%, and an arsenic content of 0.085%, while achieving a 93.29% As removal rate from the original ore that has 45.32% Fe and 0.70% As.

5.
Eur J Med Res ; 28(1): 512, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37964313

RESUMO

OBJECTIVE: The traditional treatment of rheumatoid arthritis (RA) has some side effects. We aimed to explore the effect of metformin treatment on the expression of HMGB1, cytokines, T cell subtypes and the clinical outcomes in RA patients. METHODS: The present prospective cohort study recruited 124 RA patients (metformin group) who were treated with metformin and conventional therapy (methotrexate, hydroxychloroquine sulfate and sulfasalazine) and 98 RA patients (conventional therapy group) who were only treated with conventional therapy. All subjects were admitted from December 2018 to December 2021 and continuous medication for 90 days. The serum high mobility group box 1 (HMGB1), tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-1ß and C-reactive protein (CRP) levels were measured by enzyme-linked immunosorbent assay (ELISA). Flow cytometric were used to analyze the expression of CD4+ and CD8+. Demographic and clinical statistics including age, body mass index (BMI), sex, course of disease, erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), visual analogue score (VAS)and disease activity score (DAS)-28 were collected. RESULTS: The serum levels of HMGB1, CRP, IL-6, CD4+ expression and CD4+/CD8+ ratio were significantly increased in patients with DAS-28 score ≥ 2.6. The serum HMGB1 and cytokines levels of metformin group declined more quickly during the study time. Pearson's analysis supported that a positive correlation existed between the HMGB1 and IL-6, TNF-α, CRP, CD4+, CD4+/CD8+ ratio, and VAS scores. HMGB1 could be a potential diagnostic biomarker for RA patients in active phase. Serum HMGB1 (95% CI 1.133-1.397, P < 0.001) was a factor associated with active RA. CONCLUSION: The serum HMGB1 levels were significantly increased in RA patients in active phase. The serum levels of HMGB1 and inflammatory factors and VAS scores were decreased gradually with metformin treatment. HMGB1 might act as a novel therapeutic target for RA.


Assuntos
Artrite Reumatoide , Proteína HMGB1 , Humanos , Interleucina-6 , Fator de Necrose Tumoral alfa/metabolismo , Estudos Prospectivos , Artrite Reumatoide/tratamento farmacológico , Artrite Reumatoide/metabolismo , Citocinas , Proteína C-Reativa/análise
6.
Sci Adv ; 9(48): eadj4605, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-38019907

RESUMO

Protein degradation in eukaryotic cells is mainly carried out by the 26S proteasome, a macromolecular complex not only present in the cytosol and nucleus but also associated with various membranes. How proteasomes are anchored to the membrane and the biological meaning thereof have been largely unknown in higher organisms. Here, we show that N-myristoylation of the Rpt2 subunit is a general mechanism for proteasome-membrane interaction. Loss of this modification in the Rpt2-G2A mutant cells leads to profound changes in the membrane-associated proteome, perturbs the endomembrane system, and undermines critical cellular processes such as cell adhesion, endoplasmic reticulum-associated degradation and membrane protein trafficking. Rpt2G2A/G2A homozygous mutation is embryonic lethal in mice and is sufficient to abolish tumor growth in a nude mice xenograft model. These findings have defined an evolutionarily conserved mechanism for maintaining membrane protein homeostasis and underscored the significance of compartmentalized protein degradation by myristoyl-anchored proteasomes in health and disease.


Assuntos
Proteínas de Membrana , Complexo de Endopeptidases do Proteassoma , Humanos , Animais , Camundongos , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteostase , Degradação Associada com o Retículo Endoplasmático , Camundongos Nus , Lipídeos
7.
bioRxiv ; 2023 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-37214852

RESUMO

Protein degradation in eukaryotic cells is mainly carried out by the 26S proteasome, a macromolecular complex not only present in the cytosol and nucleus but also associated with various membranes. How proteasomes are anchored to the membrane and the biological meaning thereof have been largely unknown in higher organisms. Here we show that N-myristoylation of the Rpt2 subunit is a general mechanism for proteasome-membrane interaction. Loss of this modification in the Rpt2-G2A mutant cells leads to profound changes in the membrane-associated proteome, perturbs the endomembrane system and undermines critical cellular processes such as cell adhesion, endoplasmic reticulum-associated degradation (ERAD) and membrane protein trafficking. Rpt2 G2A/G2A homozygous mutation is embryonic lethal in mice and is sufficient to abolish tumor growth in a nude mice xenograft model. These findings have defined an evolutionarily conserved mechanism for maintaining membrane protein homeostasis and underscored the significance of compartmentalized protein degradation by m yristoyl- a nchored p roteasomes (MAPs) in health and disease.

9.
Environ Sci Pollut Res Int ; 30(21): 60590-60606, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37036652

RESUMO

Whether environmental regulations are conducive to improving green innovation in water pollution-intensive enterprises (WPIEs) is of guiding significance for China's protection of the water ecosystem environment and sustainable economic development. This study regards the implementation of the "Ten-point Water Plan" (TWP) policy in 2015 as a purely exogenous event for enterprises and employs a quasi-experimental method to fill this gap based on the panel data of Chinese listed companies from 2010 to 2019. The results reveal that TWP policy has significant negative effects on the green innovation of WPIEs, the main mechanism of which is increased compliance costs. In addition, a heterogeneity analysis shows that the negative effect is stronger for green innovation activities with higher costs and for WPIEs subject to stricter environmental regulations. This paper provides new evidence against the weak Porter hypothesis and implies that WPIEs are likely to purchase technologies and equipment to reduce wastewater emissions rather than green innovation, which means incentive-based measures should be taken to foster green innovation in the environmental policymaking process.


Assuntos
Desenvolvimento Econômico , Ecossistema , Política Ambiental , China , Água
10.
Eur Radiol ; 33(5): 3544-3556, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36538072

RESUMO

OBJECTIVES: To evaluate AI biases and errors in estimating bone age (BA) by comparing AI and radiologists' clinical determinations of BA. METHODS: We established three deep learning models from a Chinese private dataset (CHNm), an American public dataset (USAm), and a joint dataset combining the above two datasets (JOIm). The test data CHNt (n = 1246) were labeled by ten senior pediatric radiologists. The effects of data site differences, interpretation bias, and interobserver variability on BA assessment were evaluated. The differences between the AI models' and radiologists' clinical determinations of BA (normal, advanced, and delayed BA groups by using the Brush data) were evaluated by the chi-square test and Kappa values. The heatmaps of CHNm-CHNt were generated by using Grad-CAM. RESULTS: We obtained an MAD value of 0.42 years on CHNm-CHNt; this result indicated an appropriate accuracy for the whole group but did not indicate an accurate estimation of individual BA because with a kappa value of 0.714, the agreement between AI and human clinical determinations of BA was significantly different. The features of the heatmaps were not fully consistent with the human vision on the X-ray films. Variable performance in BA estimation by different AI models and the disagreement between AI and radiologists' clinical determinations of BA may be caused by data biases, including patients' sex and age, institutions, and radiologists. CONCLUSIONS: The deep learning models outperform external validation in predicting BA on both internal and joint datasets. However, the biases and errors in the models' clinical determinations of child development should be carefully considered. KEY POINTS: • With a kappa value of 0.714, clinical determinations of bone age by using AI did not accord well with clinical determinations by radiologists. • Several biases, including patients' sex and age, institutions, and radiologists, may cause variable performance by AI bone age models and disagreement between AI and radiologists' clinical determinations of bone age. • AI heatmaps of bone age were not fully consistent with human vision on X-ray films.


Assuntos
Determinação da Idade pelo Esqueleto , Simulação por Computador , Aprendizado Profundo , Criança , Humanos , Viés , Aprendizado Profundo/normas , Radiologistas/normas , Estados Unidos , Determinação da Idade pelo Esqueleto/métodos , Determinação da Idade pelo Esqueleto/normas , Punho/diagnóstico por imagem , Dedos/diagnóstico por imagem , Masculino , Feminino , Pré-Escolar , Adolescente , Variações Dependentes do Observador , Erros de Diagnóstico , Simulação por Computador/normas
11.
J Formos Med Assoc ; 122(7): 549-556, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36443148

RESUMO

BACKGROUND: Purpose: Anemia affects the life quality of inflammatory bowel disease (IBD) patients, but no report from Asian about anemia screening and its impact previously. We aimed to explore the prevalence and impact of anemia among the IBD patients in Taiwan. METHODS: A retrospective study was conducted from January 2006 to February 2018 at National Taiwan University Hospital. Clinical characteristics and outcomes were analyzed. RESULTS: A total of 1604 IBD patients were enrolled [494 Crohn's disease (CD) and 1110 ulcerative colitis (UC)]. Overall, 95.3% (471/494) of CD and 87.9% (976/1110) of UC patients underwent anemia screening. Anemia screening rate in IBD patients significantly increased from 62.6% (162/259) in 2006 to 77.2% (838/1086) in 2017. The mean time from IBD diagnosis to anemia screening was 122.4 days in CD patients and even longer in UC patients at 216.2 days. Persistent anemia was found in 47.3% (548/1158) of the screened patients. Risk factors of persistent anemia included low body mass index [odds ratio (OR) = 1.96, p < 0.01], steroid [OR = 2.96, p < 0.01], thiopurine [OR = 2.62, p < 0.01], colectomy [OR = 6.3, p < 0.01], and small bowel resection [OR = 3.21, p < 0.05)] after IBD diagnosis. Compared with those without anemia, anemic IBD patients had higher admission (p < 0.01) and mortality rates (p < 0.01). CONCLUSION: The anemia screening rate was acceptable and increased over time in Taiwan. Since anemia is associated with worse outcomes, earlier survey and treatment of anemia in IBD patients is recommended.


Assuntos
Anemia , Colite Ulcerativa , Doença de Crohn , Doenças Inflamatórias Intestinais , Humanos , Estudos Retrospectivos , Doenças Inflamatórias Intestinais/complicações , Colite Ulcerativa/complicações , Colite Ulcerativa/epidemiologia , Doença de Crohn/complicações , Anemia/etiologia , Anemia/complicações
12.
Nat Commun ; 13(1): 6137, 2022 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-36253346

RESUMO

Accurate organ-at-risk (OAR) segmentation is critical to reduce radiotherapy complications. Consensus guidelines recommend delineating over 40 OARs in the head-and-neck (H&N). However, prohibitive labor costs cause most institutions to delineate a substantially smaller subset of OARs, neglecting the dose distributions of other OARs. Here, we present an automated and highly effective stratified OAR segmentation (SOARS) system using deep learning that precisely delineates a comprehensive set of 42 H&N OARs. We train SOARS using 176 patients from an internal institution and independently evaluate it on 1327 external patients across six different institutions. It consistently outperforms other state-of-the-art methods by at least 3-5% in Dice score for each institutional evaluation (up to 36% relative distance error reduction). Crucially, multi-user studies demonstrate that 98% of SOARS predictions need only minor or no revisions to achieve clinical acceptance (reducing workloads by 90%). Moreover, segmentation and dosimetric accuracy are within or smaller than the inter-user variation.


Assuntos
Neoplasias de Cabeça e Pescoço , Órgãos em Risco , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Processamento de Imagem Assistida por Computador/métodos , Pescoço , Radiometria
13.
Oncologist ; 27(12): 1008-1015, 2022 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-36215276

RESUMO

BACKGROUND: Pseudocirrhosis is an imaging finding of malignancies with liver metastasis with or without clinical liver cirrhosis-related portal hypertension (pHTN). This study defined evident pHTN by the presence of esophageal or gastric varices and compared patients' outcomes of metastatic breast cancer with imaging-diagnosed pseudocirrhosis with or without varices. METHODS: The medical records from patients with metastatic breast cancer and pseudocirrhosis between 2005 and 2017 were retrospectively analyzed. Survival outcomes were compared based on endoscopic evidence of esophageal or gastric varices. RESULTS: Among 106 patients with pseudocirrhosis, 33 (31%) had de novo stage IV disease, and 66 (62%) had hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Eighty-one (76%) had initial metastases in both hepatic lobes, and 32 (30%) had esophageal or gastric varices. The median overall survival (OS) was 5 and 13 months in patients with and without varices (P = .002). The median OS in patients with HER2-positive, HR-positive/HER2-negative, and triple-negative subtype was 16, 9, and 2 months, respectively (P = .001). Patients with varices usually had cirrhotic complications, including gastrointestinal bleeding, hyperbilirubinemia, hyperammonemia, and coagulopathy. Despite their challenging clinical conditions, 7 patients with varices had OS exceeding 1 year. In multivariate analysis, evident varices (P = .007) and triple-negative subtype (P = .013) were associated with poor OS. CONCLUSIONS: Patients with pseudocirrhosis and evident varices had a significantly shorter median OS, and were usually associated with clinical cirrhosis-related complications. To maximize OS, early identification and meticulous supportive care are warranted.


Assuntos
Neoplasias da Mama , Varizes Esofágicas e Gástricas , Humanos , Feminino , Neoplasias da Mama/complicações , Varizes Esofágicas e Gástricas/diagnóstico por imagem , Varizes Esofágicas e Gástricas/etiologia , Estudos Retrospectivos
14.
ACS Appl Mater Interfaces ; 14(41): 47025-47035, 2022 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-36214770

RESUMO

The vast majority of traditional vulcanized rubber products are insoluble and infusible, which is difficult to reprocess and biodegrade, resulting in black pollution. In addition, although most rubber materials based on covalent adaptive networks (CANs) can achieve structural reconstruction, the lack of traditional vulcanization system leads to a decline in strength. In this study, biobased vanillin derivatives (PV) were synthesized to cross-link the commercially available 1,2-polybutadiene rubber precursor to construct imine-based CANs, thereby fabricating a resource-renewable, recyclable, and degradable high-performance rubber material. Due to the rigid tripod structure of the PV, the tensile strength of the material can achieve as high as 16.24 MPa, ranking among the best in the field of recyclable polybutadiene-based materials. Benefiting from the dynamic imine unit, the "dynamic covalent bridge" can be re-established to repair the damaged network and endow the material with excellent weldability. And, shape memory faculty of the material was proved and depicted. Moreover, this material displayed excellent antibacterial property originates from the introduced Schiff-base structure. By mixing with graphene, the application of action sensors can also be achieved.


Assuntos
Grafite , Soldagem , Borracha/química , Antibacterianos/farmacologia , Iminas
15.
Emerg Med Int ; 2022: 8064011, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35912391

RESUMO

Background: Frequent emergency department (ED) users place a huge influence and burden on healthcare systems and medical costs. In Taiwan, citizens have very easy access to medical services and the national health insurance (NHI) puts very few restrictions on the frequency and facilities which the patients go to. However, there is still a certain percentage of frequent ED users in Taiwan, and yet, there are few research studies investigating the features of such users and their impact on the healthcare system. We conducted this study to investigate the prevalence and characteristics of the repeated ED users in a tertiary care medical center with more than 80000 emergency visits in a year and hypothesized that frequent ED users have unique medical and social characteristics and results in increased medical expense. Methods: We searched the integrated medical database of an urban tertiary medical center in 2017. We compared frequent ED users (≧4 visits/year) with nonfrequent users (<4 visits/year) with regards to the medical history, distance from home to the hospital, main visiting purposes, whether patients had used outpatient care or other medical resources at the same time, and the charge to the patients for each visit. Results: In 2017, 2191 patients (3.37%) were listed as frequent users and accounted for 12166 visits (14.20%). Most of the frequent users were over 65 years old (53.1%) and more than half of them had suffered from cancer (55.1%). The most significant features of frequent ED users were male, educational attainment below university, low-income households, drug or food allergies, terminal stage of illness, possession of IC Cards for Severe Illness, hospitalization in the past year, multiple outpatient visits in same year, and with certain medical history including anemia, cerebrovascular accident, congestive heart failure, peptic ulcer disease, ileus, cirrhosis, chronic obstructive pulmonary disease, and psychiatric disease. There were significant differences between frequent and nonfrequent users in disposition and median charge per visit (US$137 vs. $117, p < 0.001). Conclusions: Frequent users of ED are a heterogeneous group who usually suffer from multiple chronic diseases. There were higher rates of hospital admission and medical costs among frequent ED users compared to nonfrequent users. In addition to emergency services, frequent users also utilized outpatient resources heavily.

16.
Chin Med Sci J ; 37(2): 167-170, 2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35796342

RESUMO

Maturity-onset diabetes of the young 3 (MODY3) is an autosomal dominant monogenic diabetes mellitus characterized by defective ß-cell function and non-insulin-dependent early-onset diabetes mellitus. The facts that patients with MODY3 are often misdiagnosed as type 1 and type 2 diabetes mellitus and genetic diagnosis is expensive, make its diagnosis very challenging. In this study, we reported a case of MODY3, which was verified to be caused by a mutation in hepatocyte nuclear factor 1α gene (c.598C>T, p.Arg200Trp). In addition, the patient had a neuroendocrine tumor simultaneously, and a KMT2D gene mutation (c.5587C>G, p.Pro1863Ala) might be associated with this leson.


Assuntos
Diabetes Mellitus Tipo 2 , Neoplasias Intestinais , Tumores Neuroendócrinos , Diabetes Mellitus Tipo 2/genética , Humanos , Neoplasias Intestinais/complicações , Tumores Neuroendócrinos/complicações , Tumores Neuroendócrinos/diagnóstico , Tumores Neuroendócrinos/genética , Neoplasias Pancreáticas , Neoplasias Gástricas
17.
Sci Rep ; 12(1): 7665, 2022 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-35538186

RESUMO

Smoking influences the risks of inflammatory bowel disease (IBD). A hospital-based cohort was conducted to evaluate the effect of smoking on the development and outcomes of IBD, with age, sex and comorbidities matched non-IBD controls from the National Health Interview Survey database of Taiwan. 700 IBD patients (360 ulcerative colitis (UC), 340 Crohn's disease (CD)) were analyzed for outcomes; and 575 patients (297 UC, 278 CD) were analyzed for prevalence. Smoking prevalence was significantly lower in UC patients than controls (20.9% vs. 30.4%, p < 0.01), but no difference between CD patients and controls (19.8% vs. 22.1%, p = 0.60). UC smokers had fewer admissions (1.6 vs. 2.5, p < 0.05) but higher rates of new cancer development (16% vs. 6.7%, p < 0.05) and mortality (16% vs. 4.9%, p < 0.01) than nonsmokers. CD smokers tended to have higher rates of stricturing and penetrating diseases (p < 0.05), and higher surgery risk (60.3% vs. 38.3%, p < 0.01) than nonsmokers. Smoking prevents UC occurrence and is associated with fewer hospitalization but increases risks of cancer and mortality. By contrast, smoking does not affect CD occurrence but is related to more aggressive behavior which results in a higher surgical rate.


Assuntos
Colite Ulcerativa , Doença de Crohn , Doenças Inflamatórias Intestinais , Neoplasias , Doença Crônica , Estudos de Coortes , Colite Ulcerativa/epidemiologia , Colite Ulcerativa/etiologia , Doença de Crohn/epidemiologia , Doença de Crohn/etiologia , Hospitais , Humanos , Doenças Inflamatórias Intestinais/epidemiologia , Doenças Inflamatórias Intestinais/etiologia , Fatores de Risco , Fumar/efeitos adversos , Fumar/epidemiologia , Taiwan/epidemiologia
18.
ACS Appl Mater Interfaces ; 14(2): 3344-3355, 2022 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-34989225

RESUMO

A covalent adaptable network can endow rubber materials with recyclability and reprocessability and is expected to alleviate black pollution caused by end-of-life rubber. However, the loss of traditional vulcanization systems severely sacrifices their strength, and the tensile strength in the current study rarely exceeds 10 MPa unless fillers are added. In this work, we proposed a self-strengthening process based on dual-dynamic units (imine and disulfide), briefly, under heating, phenylsulfur radicals generated from aromatic disulfide bonds can react with double bonds (mostly vinyl) and/or couple with allyl sites, thus reforming a stronger cross-linked network. The neighboring imine unit is not affected and provides excellent thermal reprocessability and chemical recyclability. The result shows that the tensile strength can reach 19.27 MPa via self-strengthening without adding fillers or any other additives, and this ultra-high-strength is much higher than those of all known recyclable polybutadiene-based rubber materials. In addition, the material also has malleability, shape memory, and self-welding properties. By doping carbon nanotubes, a recyclable conductive composite can also be achieved. In general, we envision that this enhanced strategy has great potential to be generalized for all elastomers containing double bonds (such as styrene-butadiene rubber, nitrile rubber, isoprene rubber, and their derivatives). The reprocessability and self-welding are practical for on-site assembly or repair of composite parts and extend the service life of materials.

19.
Environ Sci Pollut Res Int ; 29(21): 32246-32260, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35013959

RESUMO

Existing researches verify Porter hypothesis mainly through one of its core establishment paths, innovation compensation, but ignore the other one, first-mover advantages. This paper considers both these paths and further distinguishes environmental R&D and non-environmental R&D in empirical study. Based on the smooth transition principle of "charge to tax" in China, this paper, taking Chinese A-share listed companies that have disclosed environmental R&D from 2008 to 2017 as sample and predicting environmental tax by pollution charge, analyzes the relationship between environmental tax and firm performance and its transmission mechanism. First, our results show that environmental tax can improve firm performance, and this influence remains in long term. After introducing instrument variable (IV) to deal with endogeneity and conducting a series of robustness tests, we then find that the relationship between environmental tax and firm performance is a robust causality. Eventually, we apply mediating effect model to further confirm the two core paths of Porter hypothesis by manifesting that environmental tax can affect firm performance through both innovation compensation and first-mover advantages. Our contributions are revealing the micro mechanism of environmental tax on firm performance, providing evidence from China to support strong Porter hypothesis, and offering some key points regarding environmental tax reform and corporate green strategy.


Assuntos
Poluição Ambiental , Organizações , Povo Asiático , China , Pesquisa Empírica , Humanos
20.
Dalton Trans ; 50(44): 16067-16075, 2021 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-34633403

RESUMO

In this work, a series of oxovanadium complexes bearing the ligands (S,E)-(+)-2, 6-dialkyl-N-(2-((2-(4-isopropyl-4,5-dihydrooxazole-2-yl)phenyl)amino)benzylidene)aniline (dialkyl = dimethyl (V1), diethyl (V2), and isopropyl (V3)) have been synthesized and characterized by FTIR spectroscopy and elemental analysis. Moreover, the molecular structures of complexes V2 and V3 were defined by X-ray diffraction. On activation with ethylaluminium sesquichloride (Al2Et3Cl3), these complexes exhibited high activity towards ethylene polymerization (up to 1.39 × 107 g molv-1 h-1) and showed excellent thermal stability (up to 60 °C). The obtained polyethylene had a moderate molecular weight (21.9 × 104 to 66.4 × 104 g mol-1) and exhibited narrow distribution (1.91 to 2.86) and unimodal features. The effect of the substituents on the ligands was also investigated in detail. The compound bearing the diisopropyl group showed the highest activity toward ethylene polymerization as the bimolecular deactivation of the catalyst can be effectively inhibited by the steric hindrance of the ortho-substituent on aniline. The complex V2 with moderate steric hindrance was also evaluated as a catalyst for the copolymerization of ethylene with norbornene and showed moderate to high activity.

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