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1.
PLoS One ; 16(1): e0244606, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33406090

RESUMO

The assessment and prediction of regional water quality are fundamental inputs to environmental planning and watershed ecological management. This paper explored spatiotemporal changes in the correlation of water quality parameters (WQPs) and land-use types (LUTs) in a reticular river network area. Water samples of 44 sampling sites were collected every quarter from 2016 to 2018 and evaluated for dissolved oxygen (DO), total phosphorus (TP), ammonia nitrogen (NH3-N), and permanganate index (CODMn). A redundancy analysis (RDA) and stepwise multiple linear regression (SMLR) were applied to analyze the land-use type impacts on seasonal WQPs at five buffer scales (100, 200, 500, 800, and 1000 m). The Kruskal-Wallis test results revealed significant seasonal differences in NH3-N, TP, CODMn, and DO. The area percentages of farmland, water area and built-up land in the study area were 38.96%, 22.75% and16.20%, respectively, for a combined total area percentage of nearly 80%. Our study showed that orchard land had an especially favorable influence on WQPs. Land-use type impacts on WQPs were more significant during the dry season than the wet season. The total variation explained by LUTs regarding WQPs at the 1 km buffer scale was slightly stronger than at smaller buffer scales. Built-up land had a negative effect on WQPs, but orchard and forest-grassland had a positive effect on WQPs. The effects of water area and farmland on WQPs were complex on different buffer scales. These findings are helpful for improving regional water resource management and environmental planning.

2.
J Phys Chem Lett ; : 711-716, 2021 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-33400536

RESUMO

Electric-field-driven ion emission from the free surface of a planar room-temperature ionic liquid (RTIL) film was studied by using molecular dynamics simulations. We calculated ion emission rate (je) as a function of the electric field normal to the RTIL/vacuum surface (En) and found that the logarithm of je over the charge density on the surface (σ) is proportional to En1/2, in agreement with classical ion evaporation theories. The composition of emitted ions includes monomers and dimers. It was found that the monomer has to move across two barriers before emission. The fraction of dimers was found to depend on the external field and ion-ion interactions. We further performed replica exchange molecular dynamics simulations and identified different metastable states of the emitting ion near the liquid film. Our results showed that En and molecular details of ion/surface determine the rate and composition of ion emission from RTIL/vacuum surfaces. Fundamental insights revealed in this study form the basis to improve ion evaporation theories and performance of electrospray applications ranging from space propulsion to nanomanufacturing.

3.
Pediatr Surg Int ; 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-33423101

RESUMO

PURPOSE: To assess the long-term results after Rex bypass (RB) shunt and Rex transposition (RT) shunt and determine the optimal approach. METHODS: Between 2010 and 2019, traditional RB shunt was performed in 24 patients, and modified RT shunt was performed in 23 children with extrahepatic portal hypertension (pHTN). A retrospective study was conducted based on comparative symptoms, platelet counts, color Doppler ultrasonography and computed tomographic portography of the portal system, and gastroscopic gastroesophageal varices postoperatively. The portal venous pressure was evaluated intraoperatively. RESULTS: The operation in the RB group was notably more time-consuming than that in the RT group (P < 0.05). Compared to RT shunt, the reduction in gastroesophageal varix grading, the increases in platelets, and the caliber of the bypass were greater in the RB group (P < 0.05). Although not statistically significant, higher morbidity of surgical complications was found after RT shunt (17.4%) compared with RB shunt (8.3%) with patency rates of 82.6 and 91.7%, respectively. Additionally, patients exhibited a lower rate of rebleeding under the RB procedure (12.5%) than under the RT procedure (21.7%). CONCLUSIONS: The RT procedure is an alternative option for the treatment of pediatric extrahepatic pHTN, and RB shunt is the preferred procedure in our center.

4.
J Cell Biochem ; 122(2): 222-234, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32918333

RESUMO

Oxidative stresss in the microenvironment surrounding lesions induces apoptosis of transplanted bone-marrow-derived mesenchymal stem cells (BMSCs). Hence, there is an urgent need for improving antioxidative-stress processes of transplanted BMSCs to further promote their survival. The present study reports the role and mechanism of Parkinson's disease protein 7 (PARK7) in enhancing antioxidative activity in BMSCs. We used a PARK7 lentivirus to transfect BMSCs to up- or downregulate PARK7, and then used H2 O2 to simulate oxidative stress in BMSCs in vitro. Overexpression of PARK7 effectively reduced reactive oxygen species and malondialdehyde, protected mitochondrial membrane potential, and resisted oxidative-stress-induced apoptosis of BMSCs, but the expression of PARK7 was downregulated, these results were reversed. At the same time, we also found that overexpression of PARK7 increased extracellular-regulated protein kinase 1/2 (ERK1/2) phosphorylation and nuclear translocation, as well as upregulated Elk1 phosphorylation and superoxide dismutase (SOD) expression. In contrast, when U0126 was used to block the ERK1/2 pathway, ERK1/2 and Elk1 phosphorylation levels were downregulated, ERK1/2 nuclear translocation and SOD content were significantly reduced, and PARK7-overexperssion-induced antioxidative activity was completely blocked. Collectively, our results suggest that PARK7 overexpression increased antioxidative-stress processes and survival of BMSCs subjected to H2 O2 via activating the ERK1/2 signaling pathway. Our findings may guide the development of a PARK7-specific strategy for improving the transplantation efficacy of BMSCs.

5.
J Mech Behav Biomed Mater ; 115: 104268, 2020 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-33338964

RESUMO

The objective of this study was to assess the influence of alumina sandblasting on the flexural strength of the latest generation of highly translucent yttria partially stabilized dental zirconia (Y-PSZ). Fully-sintered zirconia disk-shaped specimens (14.5-mm diameter; 1.2-mm thickness) of four Y-PSZ zirconia grades (KATANA HT, KATANA STML, KATANA UTML, all Kuraray Noritake; and Zpex Smile, Tosoh) were sandblasted at 0.2 MPa with 50-µm alumina (Al2O3) sand (Kulzer) or left as-sintered (control). For each zirconia grade, the yttria (Y2O3) content was determined using X-ray fluorescence (XRF). Surface roughness was assessed using 3D confocal laser microscopy. Micro-Raman spectroscopy (µ-Raman) and X-ray diffraction (XRD) were used to assess potentially induced residual stresses. Biaxial flexural strength (n = 20) was statistically compared by Weibull analysis. Focused ion beam - scanning electron microscopy (FIB/SEM) was used to observe the subsurface microstructure. Fracture surfaces after biaxial flexural strength testing were observed by SEM. KATANA UTML had the highest Y2O3 content (6 mol%), followed by KATANA STML and Zpex Smile (5 mol%), and KATANA HT (4 mol%). Al2O3-sandblasting significantly increased surface roughness of KATANA UTML and Zpex Smile. µRaman and XRD revealed the presence of residual compressive stress on all Al2O3-sandblasted surfaces. FIB/SEM revealed several sub-surface microcracks in the sandblasted specimens. Weibull analysis revealed that Al2O3-sandblasting increased the characteristic strength of KATANA HT, KATANA STML, whereas it decreased the strength of KATANA UTML. The strength enhancement after Al2O3-sandblasting of KATANA HT was the highest, followed by KATANA STML. For Zpex Smile, the influence was statistically insignificant. The impact of Al2O3-sandblasting on the Weibull modulus was controversial. The strength of zirconia after Al2O3-sandblasting is determined by the balance between microcrack formation (decreased strength) and surface compressive stress build-up (increased strength).

6.
J Exp Clin Cancer Res ; 39(1): 263, 2020 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-33243299

RESUMO

An amendment to this paper has been published and can be accessed via the original article.

7.
Nat Chem ; 2020 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-33235323

RESUMO

A Correction to this paper has been published: https://doi.org/10.1038/s41557-020-0539-8.

8.
Cardiovasc Diagn Ther ; 10(5): 1184-1191, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33224742

RESUMO

Background: Left ventricular remodeling is the basic pathological mechanism of heart failure following acute myocardial infarction (AMI). Determining sensitive indexes for the early prediction of ventricular remodeling is important for the prevention of heart failure. This study aims to investigate the value of serum TIMP-3, CA125, and NT-proBNP in predicting ventricular remodeling in patients with heart failure following AMI. Methods: From May 2017 to May 2018, 93 patients with heart failure following AMI were enrolled in the study. The participants were divided into two groups: the ventricular remodeling group (n=51) and the non-ventricular remodeling group (n=42). In addition, 47 healthy subjects who underwent physical examinations in the same period were enrolled as controls. Serum TIMP-3, CA125, and NT-proBNP were measured, in addition to the left ventricular wall thickness (LVWT) and left ventricular mass index (LVMI). The correlation of serum TIMP-3, CA125, and NT-proBNP with the LVWT and LVMI was analyzed, and its value in predicting ventricular remodeling was evaluated. Results: Serum TIMP-3 level was lower (P<0.05) and CA125 and NT-proBNP levels were higher (P<0.05) in both the ventricular remodeling and non-ventricular remodeling groups compared with the control group. Furthermore, the serum TIMP-3 level was lower in the ventricular remodeling group compared with the non-ventricular remodeling group (P<0.05), while the levels of CA125 and NT-proBNP were higher in the ventricular remodeling group compared with the non-ventricular remodeling group (P<0.05). The serum TIMP-3 level was negatively correlated with the LVWT and LVMI, while serum CA125 and NT-proBNP levels were positively correlated with the LVWT and LVMI, respectively. The area under the receiver operating characteristic curve of the combination of serum TIMP-3, CA125, and NT-proBNP levels in predicting ventricular remodeling was 0.850, and the prediction sensitivity and specificity were 74.51% and 87.71%, respectively. Conclusions: The combination of serum TIMP-3, CA125, and NT-proBNP can improve the sensitivity and specificity of predicting ventricular remodeling and can aid in the early prevention and treatment of heart failure.

9.
Adv Mater ; : e2001367, 2020 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-33225543

RESUMO

White light-emitting diodes (WLEDs) are promising next-generation solid-state light sources. However, the commercialization route for WLED production suffers from challenges in terms of insufficient color-rendering index (CRI), color instability, and incorporation of rare-earth elements. Herein, a new two-component strategy is developed by assembling two broadband emissive materials with self-trapped excitons (STEs) for high CRI and stable WLEDs. The strategy addresses effectively the challenging issues facing current WLEDs. Based on first-principles thermodynamic calculations, copper-based ternary halides composites, CsCu2 I3 @Cs3 Cu2 I5 , are synthesized by a facile one-step solution approach. The composites exhibit an ideal white-light emission with a cold/warm white-light tuning and a robust stability against heat, ultraviolet light, and environmental oxygen/moisture. A series of cold/warm tunable WLEDs is demonstrated with a maximum luminance of 145 cd m-2 and an external quantum efficiency of 0.15%, and a record high CRI of 91.6 is achieved, which is the highest value for lead-free WLEDs. Importantly, the fabricated device demonstrates an excellent operation stability in a continuous current mode, exhibiting a long half-lifetime of 238.5 min. The results promise the use of the hybrids of STEs-derived broadband emissive materials for high-performance WLEDs.

10.
Materials (Basel) ; 13(21)2020 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-33182466

RESUMO

To identify the most accurate approach for constructing of the dynamic modulus master curves for warm mix crumb rubber modified asphalt mixtures and assess the feasibility of predicting the phase angle master curves from the dynamic modulus ones. The SM (Sigmoidal model) and GSM (generalized sigmoidal model) were utilized to construct the dynamic modulus master curve, respectively. Subsequently, the master curve of phase angle could be predicted from the master curve of dynamic modulus in term of the K-K (Kramers-Kronig) relations. The results show that both SM and GSM can predict the dynamic modulus very well, except that the GSM shows a slightly higher correlation coefficient than SM. Therefore, it is recommended to construct the dynamic modulus master curve using GSM and obtain the corresponding phase angle master curve in term of the K-K relations. The Black space diagram and Wicket diagram were utilized to verify the predictions were consistent with the LVE (linear viscoelastic) theory. Then the master curve of storage modulus and loss modulus were also obtained. Finally, the creep compliance and relaxation modulus can be used to represent the creep and relaxation properties of warm-mix crumb rubber-modified asphalt mixtures.

11.
Sensors (Basel) ; 20(22)2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33182666

RESUMO

With the development of ocean exploration technology and the rapid growth in the amount of marine science observation data, people are faced with a great challenge to identify valuable data from the massive ocean observation data. A recommendation system is an effective method to improve retrieval capabilities to help users obtain valuable data. The two most popular recommendation algorithms are collaborative filtering algorithms and content-based filtering algorithms, which may not work well for marine science observation data given the complexity of data attributes and lack of user information. In this study, an approach was proposed based on data similarity and data correlation. Data similarity was calculated by analyzing the subject, source, spatial, and temporal attributes to obtain the recommendation list. Then, data correlation was calculated based on the literature on marine science data and ranking of the recommendation list to obtain the re-rank recommendation list. The approach was tested by simulated datasets collected from multiple marine data sharing websites, and the result suggested that the proposed method exhibits better effectiveness.

12.
Plant Physiol Biochem ; 157: 256-263, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33152644

RESUMO

TOPLESS (TPL)/TOPLESS-related (TPR) corepressors are important regulators of plant growth and development, but their functions in chrysanthemum (Chrysanthemum morifolium) are currently unclear. In this study, a chrysanthemum TPL/TPR family gene, designated CmTPL1-1, was characterized. This gene encodes an 1135-amino-acid polypeptide harboring a conserved N-terminal domain and two C-terminal WD40 domains. CmTPL1-1 showed no transcriptional activity in yeast, and a localization experiment indicated that it localized to the nuclei in onion epidermal cells. Transcript profiling established that the gene was most highly expressed in the stem apex. The heterologous expression of CmTPL1-1 in Arabidopsis thaliana produced a pleiotropic phenotype, including smaller leaves, shorter siliques, increased meristem number, asymmetrical petal distribution and reduced stamen number. In transgenic plants, four AtARFs were downregulated, while six AtIAAs and two AtGH3s were upregulated at the transcript level; moreover, the expression of three key class I KNOTTED-like homeobox (KNOX) genes was upregulated. In addition, by yeast two-hybrid screening of a chrysanthemum cDNA library, we found that CmTPL1-1 could interact with CmWOX4, CmLBD38 and CmLBD36, and these interactions were confirmed by bimolecular fluorescence complementation (BiFC) assays. Overall, we speculated that heterologous expression of CmTPL1-1 regulates plant growth and development by interacting with auxin signaling in Arabidopsis.

13.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi ; 34(10): 1238-1242, 2020 Oct 15.
Artigo em Chinês | MEDLINE | ID: mdl-33063486

RESUMO

Objective: To investigate the effectiveness of arthroscopic all-inside combined with outside-in "suture loop" repair for meniscus bucket-handle tear (BHT). Methods: Between August 2016 and May 2019, 44 case of meniscus BHT were treated with arthroscopic all-inside combined outside-in "suture loop". There were 29 males and 15 females with an average age of 26.6 years (range, 18-42 years). The causes of injury included sports injury in 31 cases, falling injury in 7 cases, and sprain in 6 cases. There were 32 cases of medial meniscus posterior horn tears and 12 cases of lateral meniscus posterior horn tears. The disease duration ranged from 6 weeks to 3 months. Thirty-three cases were complicated with anterior cruciate ligament rupture. All patients had normal lower limb alignment. The preoperative Lysholm score was 42.1±9.1. According to the evaluation criteria of MRI and Barrett et al., the healing of meniscus was evaluated, and the effectiveness was evaluated by Lysholm score. Results: All the 44 patients were followed up 8-36 months with an average of 16.8 months. At last follow-up, according to the evaluation criteria of Barrett et al., 39 cases were clinically healed, 5 cases were not healed, the clinical healing rate was 88.6%; according to MRI evaluation, 32 cases were completely healed, 7 cases were partially healed, and 5 cases were not healed, the total healing rate was 88.6%, and the complete healing rate was 72.7%. Lysholm score was 87.8±4.8, which was significantly different from that before operation ( t=31.060, P=0.000). Conclusion: Arthroscopic all-inside combined with outside-in "suture loop" repair is a reliable and effective method for the meniscus BHT, which can obtain good joint function.


Assuntos
Traumatismos do Joelho , Lesões do Menisco Tibial , Adolescente , Adulto , Artroscopia , Feminino , Humanos , Masculino , Suturas , Lesões do Menisco Tibial/cirurgia , Resultado do Tratamento , Adulto Jovem
14.
J Mater Chem B ; 8(41): 9533-9543, 2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33000854

RESUMO

Organic light-emitting materials with aggregation-induced emission (AIE) character have experienced a rapid development in imaging, visualization and sensing. In this paper, by installing rotors to an aggregation-caused quenching (ACQ) compound, we constructed an AIE luminogen (AIEgens) system (A2-A4, B1-B3) with wide emission tunability, which covers almost all regions of visible light (400-780 nm). The calculated energy gap of the compounds is consistent with the value of the absorption transition. In the biological experiments, B3 showed excellent lipid droplet (LD) targeting ability in PC12 cells, and higher photostability compared with the commercial LDs bioprobe. Moreover, as a hydrophobic compound, B3 can distinguish blood from a hyperlipidemia patient and normal people. Thus, this study provides a strategy to construct red/NIR fluorescent materials with AIE character, and further apply it to identify the blood of people with hyperlipidemia.

15.
Genes Genomics ; 42(12): 1431-1441, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33057899

RESUMO

BACKGROUND: Myocardial ischemia and reperfusion injury (MI/RI) is a complex pathophysiological process, which can lead to severe myocardial injury. The long noncoding RNA alpha-2-macroglobulin antisense RNA 1 (A2M-AS1) has been revealed to be abnormally expressed in MI, However, its function in MI and the potential mechanism are still unclear. OBJECTIVE: To evaluate the functional role of A2M-AS1 in hypoxia/reoxygenation (H/R)-induced neonatal cardiomyocytes and its potential molecular mechanism. METHODS: Dataset GSE66360 was obtained from GEO database for analyzing the RNA expression of A2M-AS1 and interleukin 1 receptor type 2 (IL1R2). KEGG pathway enrichment analysis of the genes that co-expressed with A2M-AS1 was performed. Human neonatal cardiomyocytes were subjected to H/R to construct in vitro models. QRT-PCR and Western blot were adopted to test the levels of mRNA and protein. The viability and apoptosis of cardiomyocytes were tested by CCK-8 and flow cytometry assays, respectively. RESULTS: The expression of A2M-AS1 was notably downregulated in H/R-treated cardiomyocytes. Overexpression of A2M-AS1 can notably enhance the cell viability of H/R-damaged cardiomyocytes, whereas knockdown of A2M-AS1 showed the opposite outcomes. Besides, a negative correlation was showed between A2M-AS1 and IL1R2 expression. In H/R-treated cardiomyocytes, overexpression of IL1R2 weakened the promoting proliferation and anti-apoptosis effects caused by overexpressing A2M-AS1, however, IL1R2-knockdown abolished the anti-proliferation and pro-apoptosis effects caused by silencing A2M-AS1. CONCLUSION: This study demonstrates the potential regulatory role of A2M-AS1/ IL1R2 axis in cardiomyocytes suffered from H/R, and provides insight into the protection of MI/RI.

16.
Dis Markers ; 2020: 2032056, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33101541

RESUMO

Substantial advance supports that CMTM2 serve as an important performer in physiological and pathological processes. However, very little is clear about the relationship between CMTM2 and HBV-related disorders. Here, for the first time, we explore that whether or not serum CMTM2 is involved in HBV-related diseases. We found that CMTM2 values were significantly lower in patients compared to healthy control (p <0.001), using ELISA assay. Furthermore, serum CMTM2 levels were negatively correlated with HBV DNA levels in CHB patients but not correlated with the serum levels of ALT and AST. Serum CMTM2 concentrations were not correlated with the serum levels of ALT, AST and HBV DNA load in HBLC and HCC patients. In addition, analysis of the ROC curve indicated that CMTM2 levels were significantly associated with the diagnostic value of HBV-related disorders. Finally, downregulation of CMTM2 was observed in HBV-infected cell model. CMTM2 degradation could be attributed to HBx-activated Lys48 (K48)-linked polyubiquitination, which was abolished by treatment with the proteasome inhibitor MG132. HBV infection suppresses CMTM2 expression by activating ubiquitin-proteasome system. Serum CMTM2 levels can be adopted as an effective indicator of the pathogenesis of HBV-related disorders.

17.
Int J Mol Sci ; 21(20)2020 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-33081060

RESUMO

Soil salinization, which is primarily due to excessive Na+ levels, is a major abiotic stress adversely affecting plant growth and development. The Na+/H+ antiporter (NHX) is a transmembrane protein mediating the transport of Na+ or K+ and H+ across the membrane to modulate the ionic balance of plants in response to salt stress. Research regarding NHXs has mainly focused on the vacuolar-type NHX family members. However, the biological functions of the endosomal-type NHXs remain relatively uncharacterized. In this study, 22 NHX family members were identified in Gossypium hirsutum. A phylogenetic analysis divided the GhNHX genes into two categories, with 18 and 4 in the vacuolar and endosomal groups, respectively. The chromosomal distribution of the NHX genes revealed the significant impact of genome-wide duplication during the polyploidization process on the number of GhNHX genes. Analyses of gene structures and conserved motifs indicated that GhNHX genes in the same phylogenetic cluster are conserved. Additionally, the salt-induced expression patterns confirmed that the expression levels of most of the GhNHX genes are affected by salinity. Specifically, in the endosomal group, GhNHX4A expression was substantially up-regulated by salt stress. A yeast functional complementation test proved that GhNHX4A can partially restore the salt tolerance of the salt-sensitive yeast mutant AXT3. Silencing GhNHX4A expression decreased the resistance of cotton to salt stress because of an increase in the accumulation of Na+ in stems and a decrease in the accumulation of K+ in roots. The results of this study may provide the basis for an in-depth characterization of the regulatory functions of NHX genes related to cotton salt tolerance, especially the endosomal-type GhNHX4A. Furthermore, the presented data may be useful for selecting appropriate candidate genes for the breeding of new salt-tolerant cotton varieties.

18.
Int J Mol Sci ; 21(20)2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-33081382

RESUMO

High temperature is a major environmental factor that adversely affects plant growth and production. SlBRI1 is a critical receptor in brassinosteroid signalling, and its phosphorylation sites have differential functions in plant growth and development. However, the roles of the phosphorylation sites of SIBRI1 in stress tolerance are unknown. In this study, we investigated the biological functions of the phosphorylation site serine 1040 (Ser-1040) of SlBRI1 in tomato. Phenotype analysis indicated that transgenic tomato harbouring SlBRI1 dephosphorylated at Ser-1040 showed increased tolerance to heat stress, exhibiting better plant growth and plant yield under high temperature than transgenic lines expressing SlBRI1 or SlBRI1 phosphorylated at Ser-1040. Biochemical and physiological analyses further showed that antioxidant activity, cell membrane integrity, osmo-protectant accumulation, photosynthesis and transcript levels of heat stress defence genes were all elevated in tomato plants harbouring SlBRI1 dephosphorylated at Ser-1040, and the autophosphorylation level of SlBRI1 was inhibited when SlBRI1 dephosphorylated at Ser-1040. Taken together, our results demonstrate that the phosphorylation site Ser-1040 of SlBRI1 affects heat tolerance, leading to improved plant growth and yield under high-temperature conditions. Our results also indicate the promise of phosphorylation site modification as an approach for protecting crop yields from high-temperature stress.

19.
Biotechnol Bioeng ; 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33124683

RESUMO

The regulation of cell density is an important segment in microfluidic cell culture, particularly in the repeated assays. Traditionally, consistent cell density is difficult to achieve, owing to the inaccurate regulation of cell density with manual feedback. A novel cell culture method with automatic feedback is proposed for real-time regulation of cell density based on microfluidic chip in this paper. Here, an integrated microfluidic system combining cell culture, density detection, and control of proliferation rate was developed. Interdigital electrode structures were sputtered on the microchannel automatically to provide the real-time feedback information of impedance. The most sensitive frequency was studied to improve the detection resolution of the sensing chip. Cells were cultured on the chip surface and cell density was detected by monitoring the alternation of the impedance. The feedback controller was established by the least squares support vector machines. Then, the cell proliferation rate was automatically controlled using the feedback controller to achieve the desired cell density in the repeated assays. The results show that the standard error of this method is 2.8% indicating that the method can keep a consistency of cell density in the repeated assays. This study provides a basis for improving the accuracy and repeatability in the further assays of finding the optimal drug concentration.

20.
ACS Appl Mater Interfaces ; 12(42): 47667-47676, 2020 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-33030892

RESUMO

Development of bifunctional catalysts with low platinum (Pt) content for the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) is highly desirable, yet challenging. Herein, we present structural engineering of a series of two-dimensional/three-dimensional (2D/3D) hierarchical N-doped graphene-supported nanosized Pt3Co alloys and Co clusters (PtCo@N-GNSs) via a hydrolysis-pyrolysis route. For the ORR, the optimal PtCo@N-GNS exhibits a high mass activity of 3.01 A mgPt-1, which is comparable to the best Pt-based catalyst obtained through sophisticated synthesis. It also possesses excellent stability with minor decay after 50 000 cyclic voltammograms (CV) cycles in acidic medium. For the EOR, PtCo@N-GNS achieves the highest mass-specific and area-specific activities of 1.96 A mgPt-1 and 5.75 mA cm-2, respectively, among all of the reported EOR catalysts to date. The unique 2D/3D hierarchy, high Pt utilization, and valid encapsulation of nanosized Pt3Co/Co synergistically contribute to the robust ORR and EOR activities of the present PtCo@N-GNS. A direct ethanol fuel cell based on PtCo@N-GNS delivers a high open-circuit potential of 0.9 V, a stable power density of 10.5 mW cm-2, and an excellent rate performance, implying the feasibility of the bifunctional PtCo@N-GNS. This work offers a new strategy for designing an ultralow Pt loading yet highly active and durable catalyst for ethanol fuel cell application.

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