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1.
Int J Med Microbiol ; 311(4): 151512, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33971542

RESUMO

Streptococcus mutans (S. mutans) are cariogenic microorganisms. Sortase A (SrtA) is a transpeptidase that attaches Pac to the cell surface. The biofilm formation of S. mutans is promoted by SrtA regulated Pac. Myricetin (Myr) has a variety of pharmacological properties, including inhibiting SrtA activity of Staphylococcus aureus. The purpose of this research was to investigate the inhibitory effect of Myr on SrtA of S. mutans and its subsequent influence on the biofilm formation. Here, Myr was discovered as a potent inhibitor of S. mutans SrtA, with an IC50 of 48.66 ± 1.48 µM, which was lower than the minimum inhibitory concentration (MIC) of 512 ug/mL. Additionally, immunoblot and biofilm assays demonstrated that Myr at a sub-MIC level could reduce adhesion and biofilm formation of S. mutans. The reduction of biofilm was possibly caused by the decreased amount of Pac on the cells' surface by releasing Pac into the medium via inhibiting SrtA activity. Molecular dynamics simulations and mutagenesis assays suggested that Met123, Ile191, and Arg213 of SrtA were pivotal for the interaction of SrtA and Myr. Our findings indicate that Myr is a promising candidate for the control of dental caries by modulating Pac-involved adhesive mechanisms without developing drug resistance to S.mutans.

2.
PLoS One ; 16(4): e0249774, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33857187

RESUMO

OBJECTIVES: Emotional manipulation is an important strategy in social interaction. The English version of MEOS-SF has been developed to make the measurement of such manipulation ability more efficient. The purpose of the current study was to assess the psychometric properties of the Chinese version of MEOS-SF. METHODS: Explore factor analysis and Confirmatory factor analysis were adopted to examine the Chinese version of the MEOS-SF factor structure in 645 Chinese participants (mean age = 24.68 ± 6.01 years) recruited online. RESULTS: Factor analysis supported a new three-factor model that included Conceal, Prosocial, and Non-prosocial, different from the original English MEOS-SF. Enhance and Divert merged to Prosocial factor while Worsen and Inauthentic merged to Non-prosocial factor because both prosocial and non-prosocial pairs had similar objectives, which would be perceived as the same thing by people in Eastern culture. As expected, MEOS-SF factors were found to be correlated with the Big Five, psychopathy, narcissism, Machiavellianism, and trait EI. CONCLUSIONS: Our results suggested that the Chinese version of MEOS-SF had acceptable psychometric properties and could be used to assess emotional manipulation.

3.
BMC Musculoskelet Disord ; 22(1): 355, 2021 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-33853573

RESUMO

A recently published article by Lai et al. in BMC Musculoskeletal Disorders trying to show that patients with pelvic fractures undergoing non-selective internal iliac artery embolization may lead to a higher rate of surgical site infection. The authors also noted that only a small percentage of patients with contrast extravasation detected by emergency contrast-enhanced CT were subsequently confirmed by angiography, thus, considered that the value of enhanced CT in predicting arterial injury was limited. The authors also believe that embolization of the main stem may cause incomplete hemostasis due to the abundant collateral circulations in the pelvic cavity. Although the author's findings are mentioned in other studies, the article's data and pictures only partially supported its inferences, and the conclusions cannot be drawn directly. In this Correspondence, we tried to reinterpret the additional findings in the article from our perspective. Through this discussion, we hope that more colleagues can re-understand the safety and effectiveness of non-selective internal iliac artery embolization in treating hemodynamically unstable pelvic fractures during the early resuscitation stage.

4.
Artigo em Inglês | MEDLINE | ID: mdl-33852805

RESUMO

BACKGROUND: Sepsis often leads to systemic multiple organ dysfunction, with the majority of deaths attributable to acute myocardial injury (AMI). In this study, we aimed to explore the functional role of miR-365a-3p in sepsis induced AMI. MATERIALS AND METHODS: The sepsis myocardial injury model was constructed using lipopolysaccharide (LPS) both in vitro and in vivo with selective regulation of miR-365a-3p expression. RT-PCR or western blot was employed to detect the expressions of miR-365a-3p, inflammatory cytokines (TNF-α, IL6, IL-1ß), and inflammation-related proteins (NF-κB, I-κB, MyD88) in myocardial tissues and cells. Also, cell counting kit-8 (CCK8) and flow cytometry assays were used measuring cardiomyocyte proliferation and apoptosis, respectively. Furthermore, the targeting relationship between miR-365a-3p and MyD88 was verified with the dual luciferase activity assay. RESULTS: MiR-365a-3p was down-regulated in LPS-induced myocardial injury model. MiR-365a-3p overexpression attenuated cardiomyocyte apoptosis, and suppressed the expressions of inflammatory cytokines and proteins. Inhibiting miR-365a-3p, however, produced the opposite effects. Mechanistically, miR-365a-3p targeted the 3'-untranslated region (3'UTR) of MyD88, thereby inactivating MyD88 mediated NF-κB pathway. CONCLUSION: MiR-365a-3p overexpression mitigated sepsis-mediated myocardial injury by inhibiting MyD88-mediated NF-κB activation.

5.
Mol Imaging Biol ; 2021 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-33876336

RESUMO

PURPOSE: This study aimed to evaluate the potential value of 2-[18F]fluoropropionic acid ([18F]FPA) for PET imaging of prostate cancer (PCa) and to explore the relationship between [18F]FPA accumulation and fatty acid synthase (FASN) levels in PCa models. The results of the first [18F]FPA PET study of a PCa patient are reported. PROCEDURES: The LNCaP, PC-3 cell lines with high FASN expression, and DU145 cell lines with low FASN expression were selected for cell culture. A PET imaging comparison of [18F]FDG and [18F]FPA was performed in LNCaP, PC-3, and DU145 tumors. Additionally, in vivo inhibition experiments in those models were conducted with orlistat. In a human PET study, a patient with PCa before surgery was examined with [18F]FPA PET and [18F]FDG PET. RESULTS: The uptake of [18F]FPA in the LNCaP and PC-3 tumors was higher than that of [18F]FDG (P<0.05 and P<0.05), but was lower in DU145 tumors (P<0.05). The accumulation (% ID/g) of [18F]FPA in the LNCaP, PC-3, and DU145 tumors decreased by 27.6, 40.5, and 11.7 %, respectively, after treatment with orlistat. The [18F]FPA showed higher radioactive uptake than [18F]FDG in the first PCa patient. CONCLUSIONS: The [18F]FPA uptake in PCa models may be varies with fatty acid synthase activity and could be reduced after administration of a single FASN inhibitor, albeit the activity that is not measured directly. The [18F]FPA seems to be a potential broad-spectrum PET imaging agent and may serve as a valuable tool in the diagnosis of PCa in humans.

6.
Food Funct ; 12(8): 3405-3419, 2021 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33900307

RESUMO

This study aimed to determine the effects of an early-life lactoferrin (LF) intervention on liver metabolism in suckling piglets. Sixty newborn piglets with an average initial body weight (BW) of 1.51 ± 0.05 kg were assigned to a control (CON) group and an LF group. At age 1 to 7 days, the piglets in the LF group were orally administered LF solution (0.5 g per kg BW daily), whereas the piglets in the CON group were orally administered the same dose of physiological saline. Plasma, jejunum and liver samples were collected on days 8 and 21. The LF piglets showed a decreased plasma urea nitrogen level on day 8 and an increased plasma albumin level on day 21. Pathway analysis of the metabolomic profiles showed that the LF treatment affected amino acid metabolism in the liver. In addition, the LF treatment upregulated the gene expression levels of proteolytic enzymes and amino acid transporters (APA, APN, EAAC1, Pept1, CAT1, B0AT1 and ASCT2) in the jejunum, and it enhanced the phosphorylation levels of mTOR and p70S6K in the liver. The LF treatment also upregulated the expression of a ß-oxidation-related gene (CPT1) and affected the tricarboxylic acid cycle in the liver on day 21. Furthermore, the LF piglets showed a decreased level of malondialdehyde and increased levels of GSH, GSH-Px and GCLC in the liver mitochondria. Overall, the early-life LF intervention affected the protein synthesis, energy production and antioxidative capacity in the liver of the neonatal piglets.

7.
Adv Mater ; : e2008065, 2021 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-33797131

RESUMO

The innate immune system plays a key role in protecting the human body from tumors, which, unfortunately, is largely counteracted by their immune-suppression function. Such an immune suppression has been reported to be induced by the immunosuppressive microenvironment, including the exhausted cytotoxic T lymphocytes (CTLs) and tumor-promoting M2-polarized macrophages. Here, a novel tumor-immunotherapeutic modality based on the nanocatalytic innate immunity activation by tumor-specific mitochondrial DNA (mtDNA) oxidative damage is proposed. In detail, a nanocatalytic medicine, Fe2+ -Ru2+ -loaded mesoporous silica nanoparticle named as MSN-Ru2+ /Fe2+ (MRF), is constructed to induce oxidative damage in the mtDNA of tumor cells. Such an oxidative mtDNA is able to escape from the tumor cells and acts as an immunogenic damage-associated molecular pattern to M1-polarize tumor-associated macrophages (TAMs), resulting in the reactivated immunoresponse of macrophages against cancer cells, and the subsequent inflammatory response of innate immunity. Most importantly, the treatment strategy based on regulating the innate immune response of TAMs not only stops the primary tumor progression, but also almost completely inhibits the growth of distant tumors in the periods of treatments.

8.
J Am Chem Soc ; 2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33928777

RESUMO

Magnetic hyperthermia therapy (MHT) is noninvasive and features excellent tissue penetration for deep-seated tumors, but unfortunately, it suffers the low therapeutic efficacy due to the limited magneto-thermal efficiency and insufficient intratumor accumulation of conventional intravenous-injected magnetic nanoparticles, which are actually mostly sequestered by the mononuclear phagocyte system, especially the liver. Such a disadvantageous characteristic of preferential liver uptake is here exploited, for the first time as far as we know, to treat orthotopic liver cancer by mild MHT using specially designed composite magnetic nanoparticles. A kind of core-shell-structured and Zn2+-doped Zn-CoFe2O4@Zn-MnFe2O4 superparamagnetic nanoparticles (ZCMF) has been synthesized which exhibits excellent and highly controllable magnetic hyperthermia performance owing to an exchange-coupled magnetism between the core and shell, and Zn2+ doping. The controllable mild MHT at 43-44 °C based on ZCMF demonstrates almost complete inhibition of liver cancer cell proliferation and tumor growth, which is associated with the suppression of heat shock protein 70 (HSP70) expression. More importantly, the mild MHT-treated liver cancer cells are capable of activating natural killer (NK) cells by dramatically upregulating the expression of UL16-binding proteins (ULBPs), ligands of natural killer group 2 member D (NKG2D). As a result, the growth of both xenograft tumors and orthotopic liver tumors were almost completely suppressed under mild MHT via induced NK-cell-related antitumor immunity in vivo. This work not only evidences the great potential of mild MHT but also reveals the underlying immunity activation mechanism in liver cancer treatment by mild MHT.

9.
Sci Rep ; 11(1): 4847, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33649465

RESUMO

An influenza vaccination might reduce the risk of incident peripheral arterial occlusive disease (PAOD) in patients with chronic kidney disease (CKD), but supporting evidence is limited. This case-crossover study analyzed data from Taiwan's real-world National Health Insurance Research Database. This study included elderly (≥ 67 years old) patients with CKD having incident PAOD from January 1, 2006, to June 30, 2015. We defined 1 year before PAOD onset as the index date for the self-control group. A conditional logistic regression model was used to investigate exposure to an influenza vaccination for estimating the risk for incident PAOD following vaccination. In total, this study included 46,782 elderly patients with CKD having incident PAOD. The odds ratios for incident PAOD were 0.85 (95% confidence interval 0.77-0.94), 0.85 (0.79-0.92), 0.84 (0.79-0.90), and 0.85 (0.81-0.90) at 1, 2, 3, and 4 months after an influenza vaccination, respectively. We observed consistent results for the subgroups of patients with CKD and concomitant diabetes. However, we did not observe any beneficial effects of influenza vaccination in patients with advanced CKD or end-stage renal disease. This study demonstrated that influenza vaccination may be associated with a reduced risk of incident PAOD among patients with early-stage CKD.

10.
Nutr J ; 20(1): 20, 2021 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-33658024

RESUMO

BACKGROUND: The dietary nutritional status of the lactating mothers is related to maternal health and has a significant impact on the growth and development of infants through the secretion of breast milk. The food frequency questionnaire (FFQ) is the most cost-effective dietary assessment method that can help obtain information on the usual dietary pattern of participants. Until now, the FFQs have been used for different populations in China, but there are few FFQs available for the lactating mothers. We aimed to develop a semi-quantitative, 156-item FFQ for the Chinese lactating mothers, and evaluate its reproducibility and relative validity. METHODS: A total of 112 lactating mothers completed two FFQs and one 3-d dietary record (3DR). The first FFQ (FFQ1) was conducted during postpartum at 60-65 days and the second FFQ (FFQ2) during subsequent follow-up at 5 weeks. The 3DR was completed with portion sizes assessed using photographs taken by the respondent before and after eating (instant photography) 1 week after FFQ1. RESULTS: For reproducibility, the Spearman's correlation coefficients for food ranged from 0.34 to 0.68, and for nutrients from 0.25 to 0.61. Meanwhile, the intra-class correlation coefficients for food ranged from 0.48 to 0.87, and for nutrients from 0.27 to 0.70. For relative validity, the Spearman's correlation coefficients for food ranged from 0.32 to 0.56, and for nutrients from 0.23 to 0.72. The energy-adjusted coefficients for food ranged from 0.26 to 0.55, and for nutrients from 0.22 to 0.47. Moreover, the de-attenuation coefficients for food ranged from 0.34 to 0.67, and for nutrients from 0.28 to 0.77. The Bland-Altman plots also showed reasonably acceptable agreement between the two methods. CONCLUSIONS: This FFQ is a reasonably reproducible and a relative valid tool for assessing dietary intake of the Chinese lactating mothers.

11.
Chem Asian J ; 2021 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-33704900

RESUMO

Mesomorphous butterfly-like shape molecules based on benzodithiophene, benzodithiophene-4,8-dione and cyclopentadithiophen-4-one core moieties were efficiently synthesized by the Suzuki-Miyaura coupling and Scholl oxidative cyclo-dehydrogenation reactions' tandem. Most of the butterfly molecules spontaneously self-organize into columnar hexagonal mesophase. The electron-deficient systems possess strong solvent-gelling ability but are not luminescent, whereas the electron-rich terms do not form gels but strongly emit light between 400 and 600 nm. The charge carrier mobility was also measured by time-of-flight transient photocurrent technique in the mesophases for some of the compounds. They display hole-transport performances with positive charge mobility in the 10-3  cm-2 V-1 s-1 range, consistent with the high degree of ordering and stability of the columnar superstructures. In particular, the mesogen with a benzodithiophen-4,8-dione core shows ambipolar charge carrier transport with both high electron (µe =6.6×10-3  cm-2 V-1 s-1 ) and hole (µh =4.5×10-3  cm-2 V-1 s-1 ) mobility values.

12.
Atherosclerosis ; 323: 20-29, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33773161

RESUMO

BACKGROUND AND AIMS: Systemic immune-inflammation index (SII) has been recently investigated as a novel inflammatory and prognostic marker. SII may be used as an indicator reflecting the progressive inflammatory process in atherosclerosis, although its link to incident cardiovascular disease (CVD) has not been examined in previous studies. This study aims to prospectively assess the association of SII with incident CVD and its main subtypes in Chinese adults. METHODS: Using data from the Dongfeng-Tongji cohort study, 13,929 middle-aged and older adults with a mean age of 62.56 years (range 35-91 years), who were free of CVD and cancer, were included for analysis. The baseline study was conducted in Shiyan city, Hubei province from 2008 to 2009. The SII was calculated as platelet count (/L) × neutrophil count (/L)/lymphocyte count (/L). Cox regression models were used to examine the associations of SII with incident CVD, including stroke and coronary heart disease (CHD). RESULTS: Over a median 8.28 years (maximum 8.98 years) of follow-up, 3386 total CVD cases, including 801 stroke cases and 2585 total CHD cases, were identified. In multivariable Cox regression analyses, higher levels of log-transformed SII were significantly associated with total stroke (HR 1.224, 95% CI 1.065-1.407) and ischemic stroke (HR 1.234, 95% CI 1.055-1.442). For those participants with the highest quartiles of SII versus the lowest quartiles of SII, the HRs were 1.358 (95% CI 1.112-1.658) for total stroke, 1.302 (95% CI 1.041-1.629) for ischemic stroke, and 1.600 (95% CI 1.029-2.490) for hemorrhagic stroke. CONCLUSIONS: SII may serve as a useful marker to elucidate the role of the interaction of thrombocytosis, inflammation, and immunity in the development of cerebrovascular diseases in the middle-aged and elderly population.

13.
Dis Markers ; 2021: 8819934, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33763157

RESUMO

Non-small-cell lung cancer (NSCLC) is one of the most common types of cancer worldwide. Accumulating evidence has suggested that aberrant expression of microRNAs (miRNAs) is involved in the carcinogenesis and progression of NSCLC. The current study is aimed at investigating the clinical significance of serum miR-629 in NSCLC. The expression levels of serum miR-629 in patients with NSCLC, patients with nonmalignant lung diseases, and healthy controls were assessed by real-time quantitative polymerase chain reaction. Our results showed that serum miR-629 levels were significantly upregulated in NSCLC patients compared to the controls. Serum miR-629 exhibited better performance for discriminating NSCLC patients from healthy controls, compared to the traditional biomarkers CYFRA 21-1 and CEA. In addition, a high serum miR-629 level was positively correlated with adverse clinicopathological parameters including lymph node metastasis, differentiation, and clinical stage. Serum miR-629 was dramatically reduced in the NSCLC cases receiving surgical treatment. Moreover, the patients in the high serum miR-629 group suffered poorer overall survival and disease-free survival than those in the low serum miR-629 group. In conclusion, serum miR-629 might serve as a potential prognostic biomarker for NSCLC.

14.
Small ; 17(17): e2007739, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33739614

RESUMO

2D organic crystals exhibit efficient charge transport and field-effect characteristics, making them promising candidates for high-performance nanoelectronics. However, the strong Fermi level pinning (FLP) effect and large Schottky barrier between organic semiconductors and metals largely limit device performance. Herein, by carrying out temperature-dependent transport and Kelvin probe force microscopy measurements, it is demonstrated that the introducing of 2D metallic 1T-TaSe2 with matched band-alignment as electrodes for F16 CuPc nanoflake filed-effect transistors leads to enhanced field-effect characteristics, especially lowered Schottky barrier height and contact resistance at the contact and highly efficient charge transport within the channel, which are attributed to the significantly suppressed FLP effect and appropriate band alignment at the nonbonding van der Waals (vdW) hetero-interface. Moreover, by taking advantage of the improved contact behavior with 1T-TaSe2 contact, the optoelectronic performance of F16 CuPc nanoflake-based phototransistor is drastically improved, with a maximum photoresponsivity of 387 A W-1 and detectivity of 3.7 × 1014 Jones at quite a low Vds of 1 V, which is more competitive than those of the reported organic photodetectors and phototransistors. The work provides an avenue to improve the electrical and optoelectronic properties of 2D organic devices by introducing 2D metals with appropriate work function for vdW contacts.

15.
J Dig Dis ; 2021 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-33742780

RESUMO

OBJECTIVE: To discern the symptomatic features of coronavirus disease 2019 (COVID-19) and to evaluate the severity and prognosis of the disease. METHODS: In this retrospective cohort study, 932 hospitalized patients with COVID-19 in Wuhan were enrolled, including 52 severe and 880 non-severe cases. All patients were followed up for 3 months after discharge. The symptomatic features and follow-up data of the patients in both groups were analyzed and compared. RESULTS: Of the 932 patients, fever (60.0%), cough (50.8%) and fatigue (36.4%) were the most common symptoms. In total, 32.7% of the severe cases presented with gastrointestinal symptoms at disease onset, including anorexia, nausea, vomiting or diarrhea, which was significantly higher than that of the non-severe group (P = 0.0015). The incidence of olfactory disturbance and dysgeusia was only 3.1% and 6.2%, respectively. After adjusting for age and sex, multivariate regression analysis showed that fever lasting for over 5 days (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.00-3.62, P = 0.0498), anorexia at onset (OR 2.61, 95% CI 1.26-5.40, P = 0.0096), and modified Medical Research Council level above grade 2 when dyspnea occurred (OR 14.19, 95% CI 7.01-28.71, P < 0.0001) were symptomatic risk factors for severe COVID-19. During the follow-up, cough (6.2%), dyspnea (7.2%), fatigue (1.8%), olfactory disturbance and dysgeusia (1.5%) were the significant remaining symptoms. CONCLUSIONS: COVID-19 causes clusters of symptoms with multiple systems involved. Certain symptomatic characteristics have predictive value for severe COVID-19. Short-term follow-up data reveal that most patients have a good prognosis.

16.
Radiology ; 299(2): 362-370, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33687285

RESUMO

Background Multiparametric MRI is used for depiction of prostate cancer (PCa) but without consideration of the mechanical alteration of prostatic tissue by cancer. Purpose To investigate the diagnostic performance of stiffness and fluidity quantified with tomoelastography, a multifrequency MR elastography technique, for depiction of PCa compared with multiparametric MRI with Prostate Imaging Reporting and Data System (PI-RADS) version 2.1. Materials and Methods Prospective participants suspected to have PCa and healthy controls (HCs) underwent multiparametric MRI and tomoelastography between March 2019 and July 2020. Tomoelastography maps of shear-wave speed (c) and loss angle (φ) quantified stiffness and fluidity, respectively, for PCa and benign prostatic disease and for the peripheral and transition zones in HCs. Differences between entities and regions were analyzed by using analysis of variance or Kruskal-Wallis test. Diagnostic performance was assessed with area under the receiver operating characteristic curve (AUC) analysis. Results There were 73 participants with PCa (mean age, 72 years ± 7 [standard deviation]), 82 with benign prostatic disease (66 years ± 7), and 53 HCs (41 years ± 14). Mean ± standard deviation of c and φ were higher in PCa (3.4 m/sec ± 0.6 and 1.3 radian ± 0.2, respectively) than in benign prostatic disease (2.6 m/sec ± 0.3 and 1.0 radian ± 0.2, respectively; P < .001) and age-matched HCs (2.2 m/sec ± 0.1 and 0.8 radian ± 0.1, respectively; P < .001). Incorporating c and φ (AUC, 0.95; 95% CI: 0.92, 0.98) improved the diagnostic performance of PI-RADS version 2.1 (AUC, 0.85; 95% CI: 0.80, 0.91; P < .001). Multiparametric MRI combined with c and φ enabled detection of PCa with 95% (78 of 82 non-PCa) specificity, which was significantly higher than with use of multiparametric MRI alone (77% [63 of 82 non-PCa]; P < .001). In regional analysis, c combined with φ enabled differentiation of transition zone PCa from benign prostatic hyperplasia (AUC, 0.91; 95% CI: 0.83, 0.98) and peripheral zone PCa from chronic prostatitis (AUC, 0.94; 95% CI: 0.88, 1.00). Conclusion Use of tomoelastography-quantified stiffness and fluidity improved the diagnostic performance of multiparametric MRI with Prostate Imaging Reporting and Data System version 2.1 in detecting cancer in both the peripheral and transition zones. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Hectors and Lewis in this issue. An earlier incorrect version of this article appeared online. This article was corrected on March 24, 2021.

17.
Materials (Basel) ; 14(4)2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33669893

RESUMO

Many urgently needed inconel superalloy parts with complex internal cavity geometry and high surface precision are difficult to prepare by traditional subtractive manufacturing methods because of its poor machinability. The additive manufacturing technology that has emerged in recent years became a research hotspot in the manufacture of refractory and difficult-to-process metals. In the present study, selective laser melting (SLM), a typical additive manufacture technology, was used to prepare Inconel 718 samples. The influences of input laser energy density ((E, J/mm3) on densification behavior, phases composition, microstructures, microhardness, and wear performance of the SLM as-built Inconel 718 samples were explored in detail. X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to examine the phase composition and microstructure evolutions. The results show that the formablity, microstructures and mechanical properties of the printed samples were all improved with the increase of E within the parameter setting range of this study. At a lower E, the poor surface morphology and balling effect occurred, the density, hardness, and wear resistance were all at a relatively lower level. When an E value of 190 J/mm was properly set, the surface open-pores and balling effect disappeared, the laser scanning tracks became smooth and continuous, the near-full dense (99.15%) and specimens with good metallurgical bonding and no critical defect were obtained, in which the average microhardness value reached 348 HV0.2 and wear rate was 5.67 × 10-4 mm3/N·m. The homogeneity of the superalloy Inconel 718 was also explored.

18.
Polymers (Basel) ; 13(5)2021 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-33673625

RESUMO

3D printing technology is a versatile technology. The waste of 3D printed plastic products is a matter of concern because of its impact on the circular economy. In this paper, we discuss the current status and problems of 3D printing, different methods of 3D printing, and applications of 3D printing. This paper focuses on the recycling and degradation of different 3D printing materials. The degradation, although it can be done without pollution, has restrictions on the type of material and time. Degradation using ionic liquids can yield pure monomers but is only applicable to esters. The reprocessing recycling methods can re-utilize the excellent properties of 3D printed materials many times but are limited by the number of repetitions of 3D printed materials. Although each has its drawbacks, the great potential of the recycling of 3D printed waste plastics is successfully demonstrated with examples. Various recycling approaches provide the additional possibility of utilizing 3D printing waste to achieve more efficient circular application.

19.
Planta ; 253(3): 69, 2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33599839

RESUMO

MAIN CONCLUSION: A total of 6763 proteins were identified in the developing pear flesh, which were further screened for differentially expressed proteins related to fruit quality and ATP-binding cassette transporters. To obtain further details on changes in protein levels during fruit ripening and to identify and evaluate changes in various metabolic pathways that affect fruit quality, a proteomic method using tandem mass tags was implemented at three developmental stages in Pyrus pyrifolia cv. "Hosui" that identified 6763 proteins. Subcellular localization and Gene Ontology enrichment analysis revealed major functions of all identified proteins. Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that all metabolic processes are reflected in the up- and downregulation of differentially expressed proteins during fruit development, which play predominant roles in cell division, cell expansion, and fruit ripening. Among the examined differentially expressed proteins, 160 related to fruit quality, and 14 ATP-binding cassette transporters related to fruit development were identified and analyzed. The quantitative data were validated by parallel reaction monitoring, which confirmed the reliability of the experimental results.

20.
Chem Soc Rev ; 2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33595008

RESUMO

Alkanes are the major constituents of natural gas and crude oil, the feedstocks for the chemical industry. The efficient and selective activation of C-H bonds can convert abundant and low-cost hydrocarbon feedstocks into value-added products. Due to the increasing global demand for light alkenes and their corresponding polymers as well as synthesis gas and hydrogen production, C-H bond activation of light alkanes has attracted widespread attention. A theoretical understanding of C-H bond activation in light hydrocarbons via density functional theory (DFT) and microkinetic modeling provides a feasible approach to gain insight into the process and guidelines for designing more efficient catalysts to promote light alkane transformation. This review describes the recent progress in computational catalysis that has addressed the C-H bond activation of light alkanes. We start with direct and oxidative C-H bond activation of methane, with emphasis placed on kinetic and mechanistic insights obtained from DFT assisted microkinetic analysis into steam and dry reforming, and the partial oxidation dependence on metal/oxide surfaces and nanoparticle size. Direct and oxidative activation of the C-H bond of ethane and propane on various metal and oxide surfaces are subsequently reviewed, including the elucidation of active sites, intriguing mechanisms, microkinetic modeling, and electronic features of the ethane and propane conversion processes with a focus on suppressing the side reaction and coke formation. The main target of this review is to give fundamental insight into C-H bond activation of light alkanes, which can provide useful guidance for the optimization of catalysts in future research.

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