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1.
BMC Musculoskelet Disord ; 21(1): 102, 2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-32059654

RESUMO

BACKGROUND: The incidence of insufficiency fracture (IF) at femoral neck is low, accounting for about 5% of all insufficiency fractures, and IF at bilateral femoral neck is less common with more occurrence in athlete or serviceman. With the aging of populations, more cases of bilateral femoral neck IF have occurred recently, while the standard clinical treatment still remains lacking due to the complexity of these patients. CASE PRESENTATION: A 55-year-old male patient complained pain in his bilateral hip, with no history of trauma, glucocorticoid hormone consumption or radiotherapy, and imaging examination revealed fracture nonunion and shortening in his left femoral neck, and double fracture line on the right femoral neck. The patient received a cementless THA for the left femoral neck fracture and conservative treatment for the right side, followed by Elcatonin injection and oral administration of Carbonate D3 Granules. After 4 months of fellow-up, the patient presented improved functional scorings in bilateral hip joints, with no signs of prothesis infection or loosening. CONCLUSION: We present a rare case of bilateral femoral neck IF in a middle-aged male and the treatment is successful. The timely CT and MRI examinations of bilateral hip joints for patients was necessary for orthopedists to select proper therapeutic regimen. In addition, the choice for therapeutic regimen of bilateral femoral IF should not only be based on the professional judgement of orthopedists, but also on the wishes of patients.

2.
Colloids Surf B Biointerfaces ; 189: 110813, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-32018139

RESUMO

Hydroxyapatite (HA) coatings have been of important as biocompatible coatings for dental and bone tissue engineering application. However, the poor antibacterial performance and weak biological activity of HA coatings limited their clinical applications. As a strategy to improve the antibacterial performance and biological activity of HA, Zinc and bismuth ions were incorporated into HA lattice by substituting Ca2+ ions, respectively, and thus zinc substituted hydroxyapatite/bismuth substituted hydroxyapatite (Zn-HA/Bi-HA) biphasic coatings on titanium plates with various ratios were fabricated via sol-gel and dip-coating processes. The purity of the Zn-HA and Bi-HA phase was confirmed by X-ray diffraction (XRD) test. The biphasic coatings showed slower dissolution rate than pure HA coating. Furthermore, the Zn-HA/Bi-HA coatings reveal good biomineralization activity in simulated body fluid (SBF) by forming regular spherical apatite agglomerates. Moreover, the biphasic Zn-HA/Bi-HA coatings exhibited that improved antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as compared to pure HA coatings. The CCK-8 assays demonstrate Zn-HA/Bi-HA coatings showed no toxicity to MG63 cells, and the Zn-HA/Bi-HA2 (Zn-HA:Bi-HA=64:1) coating is more effective to enhance the proliferation of MG63 cells compared to other coatings. This finding suggests Zn-HA/Bi-HA biphasic coatings are promising candidates for biomedical applications.

3.
J Cell Biochem ; 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31961017

RESUMO

The pluripotent mouse embryonal carcinoma cell line P19 is widely used as a model for research on all-trans-retinoid acid (RA)-induced neuronal differentiation; however, the signaling pathways involved in this process remain unclear. This study aimed to reveal the molecular mechanism underlying the RA-induced neuronal differentiation of P19 cells. Real-time quantitative polymerase chain reaction and Western blot analysis were used to determine the expression of neuronal-specific markers, whereas flow cytometry was used to analyze cell cycle and cell apoptosis. The expression profiles of messenger RNAs (mRNAs) in RA-induced neuronal differentiation of P19 cells were analyzed using high-throughput sequencing, and the functions of differentially expressed mRNAs (DEMs) were determined by bioinformatics analysis. RA induced an increase in both class III ß-tubulin (TUBB3) and neurofilament medium (NEFM) mRNA expression, indicating that RA successfully induces neuronal differentiation of P19 cells. Cell apoptosis was not affected; however, cell proliferation decreased. We found 4117 DEMs, which were enriched in the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway, Wnt signaling pathway, and cell cycle. Particularly, a few DEMs could be identified in the PI3K/Akt signaling pathway networks, such as PI3K, Akt, glycogen synthase kinase-3ß (GSK3ß), cyclin-dependent kinase 4 (CDK4), P21, and Bax. RA significantly increased the protein expression of PI3K, Akt, phosphorylated Akt, GSK3ß, phosphorylated GSK3ß, CDK4, and P21, but it reduced Bax protein expression. The Akt inhibitor affected the increase of TUBB3 and NEFM mRNA expression in RA-induced P19 cells. The molecular mechanism underlying the RA-induced neuronal differentiation of P19 cells is potentially involved in the PI3K/Akt/GSK3ß signaling pathway. The decreased cell proliferation ability of neuronally differentiated P19 cells could be associated with the expression of cell cycle proteins.

4.
Cancer Gene Ther ; 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31988476

RESUMO

Epidermal growth factor receptor (EGFR) gene amplification and mutation occurs most frequently in glioblastoma (GBM). However, EGFR-tyrosine kinase inhibitors (TKIs), including gefitinib, have not yet shown clear clinical benefit and the underlying mechanisms remain largely unexplored. We previously demonstrated that LRIG2 plays a protumorigenic role and functions as a modulator of multiple oncogenic receptor tyrosine kinases (RTKs) in GBM. We therefore hypothesized that LRIG2 might mediate the resistance to EGFR inhibitor through modulating other RTK signaling. In this study, we report that LRIG2 is induced by EGFR inhibitor in gefitinib-treated GBM xenografts or cell lines and promotes resistance to EGFR inhibition by driving cell cycle progression and inhibiting apoptosis in GBM cells. Mechanistically, LRIG2 increases the secretion of growth-arrest specific 6 (GAS6) and stabilizes AXL by preventing its proteasome-mediated degradation, leading to enhancement of the gefitinib-induced activation of AXL and then reactivation of the gefitinib-inhibited SRC. Targeting LRIG2 significantly sensitizes the GBM cells to gefitinib, and inhibition of the downstream GAS6/AXL/SRC signaling abrogates LRIG2-mediated gefitinib resistance in vitro and in vivo. Collectively, our findings uncover a novel mechanism in resistance to EGFR inhibition and provide a potential therapeutic strategy to overcome resistance to EGFR inhibition in GBM.

5.
BMC Cancer ; 20(1): 56, 2020 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-31987030

RESUMO

BACKGROUND: Lung adenocarcinoma (LUAD) is one of the most common cancer types, threatening the human health around the world. However, the high heterogeneity and complexity of LUAD limit the benefits of targeted therapies. This study aimed to identify the key prognosis impacting genes and relevant subtypes for LUAD. METHODS: We recognized significant mutations and prognosis-relevant genes based on the omics data of 515 LUAD samples from The Cancer Genome Atlas. Mutation significance was estimated by MutSigCV. Prognosis analysis was based on the cox proportional hazards regression (Coxph) model. Specifically, the Coxph model was combined with a causal regulatory network to help reveal which genes play master roles among numerous prognosis impacting genes. Based on expressional profiles of the master genes, LUAD patients were clustered into different sub-types by a consensus clustering method and the importance of master genes were further evaluated by random forest. RESULTS: Significant mutations did not influence the prognosis directly. However, a collection of prognosis relevant genes were recognized, where 75 genes like GAPDH and GGA2 which are involved in mTOR signaling, lysosome or other key pathways are further identified as the master ones. Interestingly, the master gene expressions help separate LUAD patients into two sub-types displaying remarkable differences in expressional profiles, prognostic outcomes and genomic mutations in certain genes, like SMARCA4 and COL11A1. Meanwhile, the subtypes were re-discovered from two additional LUAD cohorts based on the top-10 important master genes. CONCLUSIONS: This study can promote precision treatment of LUAD by providing a comprehensive description on the key prognosis-relevant genes and an alternative way to classify LUAD subtypes.

6.
ACS Chem Neurosci ; 11(2): 133-145, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31815422

RESUMO

Metabotropic glutamate receptors of class C GPCRs exist as constitutive dimers, which play important roles in activating excitatory synapses of the central nervous system. However, the activation mechanism induced by agonists has not been clarified in experiments. To address the problem, we used microsecond all-atom molecular dynamics (MD) simulation couple with protein structure network (PSN) to explore the glutamate-induced activation for the mGluR1 homodimer. The results indicate that glutamate binding stabilizes not only the closure of Venus flytrap domains but also the polar interaction of LB2-LB2, in turn keeping the extracelluar domain in the active state. The activation of the extracelluar domain drives transmembrane domains (TMDs) of the two protomers closer and induces asymmetric activation for the TMD domains of the two protomers. One protomer with lower binding affinity to the agonist is activated, while the other protomer with higher binding energy is still in the inactive state. The PSN analysis identifies the allosteric regulation pathway from the ligand-binding pocket in the extracellular domain to the G-protein binding site in the intracellular TMD region and further reveals that the asymmetric activation is attributed to a combination of trans-pathway and cis-pathway regulations from two glumatates, rather than a single activation pathway. These observations could provide valuable molecular information for understanding of the structure and the implications in drug efficacy for the class C GPCR dimers.

7.
Colloids Surf B Biointerfaces ; 186: 110720, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31855688

RESUMO

Porous CaCO3 microspheres are nowadays extensively used as a drug delivery system due to their excellent biocompatibility and degradability. However, the stability of vaterite CaCO3 microspheres is a major problem as a drug carrier. In this work, porous calcite CaCO3 microspheres are fabricated by calcination of gelatin-CaCO3 composite microspheres at 550 °C in air. The size and morphology of CaCO3 microspheres could be well regulated by the addition of gelatin. The structure of the as-prepared porous calcite CaCO3 microspheres is characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Compared with vaterite CaCO3 microspheres, porous calcite CaCO3 microspheres are more stable and exhibit good drug-loading and drug release properties for doxorubicin (DOX), an effective anticancer agent. This study provides an easy and novel approach to prepare stable porous calcite CaCO3 microspheres, which show promising potential as a carrier for DOX.

8.
J Colloid Interface Sci ; 560: 321-329, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31671353

RESUMO

In this work, water-stable Al-MIL-101 analogues were successfully synthesized by adjusting the Fe/Al ratio to obtain excellent phosphorus removal efficiencies. The introduction of Fe3+ into the precursor solution allowed the final structure of aluminum metal-organic frameworks (Al-MOFs) to be tuned without introducing Fe into the final structure. The formation of Al-MIL-101 analogues with different morphologies and surface areas was accomplished by adjusting the Fe/Al molar ratio in the precursor solution. Compared with pure Fe-MIL-101 or Al-MIL-101, Al-MIL-101 analogues exhibited ultra-fast phosphorous adsorption kinetics and high phosphorous adsorption capacities. Al-MIL-101, produced with an Fe/Al feed molar ratio of 0.5, achieved a maximum phosphorus uptake capacity of 90 mg P/g, which is much higher than the phosphorus absorption reported in most literatures. More importantly, the Al-MIL-101 analogue obtained using an Fe/Al molar ratio of 0.5 exhibited an excellent phosphorus removal efficiency, even after multiple adsorption/desorption cycles. These results indicate that Al-MOFs produced by adjusting the Fe amount in the precursor solution are promising candidates for the removal of phosphate from water.

9.
Methods Mol Biol ; 2069: 125-138, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31523771

RESUMO

Transcriptomics enables us to elucidate comprehensive gene expression profiles in given experimental conditions. Global regulators, which include transcriptional regulators and two-component regulatory systems, have evolved in a variety of bacterial systems. They play important roles in bacterial fitness and pathogenesis by regulating target gene expression. Advanced next-generation RNA sequencing technology (RNA-seq) provides a powerful and effective tool to analyze the transcriptome of bacterial cells. In this chapter, we provide a detailed procedure for the investigation of gene expression profiles and identification of target genes, regulons, and/or pathways that are mediated by a regulator. This procedure is done using RNA-seq analysis, which involves RNA purification, mRNA enrichment, decontamination, RNA-seq data analysis, and quantitative real-time reverse transcription PCR.

10.
Methods Mol Biol ; 2069: 177-186, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31523774

RESUMO

Metabolomics is becoming increasingly important in bioscience research as it provides a comprehensive analytical platform for a better understanding of the metabolic functions of cells and organisms. Recently, microbial metabolomics has been utilized in diverse research areas, including detection and diagnosis of pathogens, metabolic engineering, and drug discovery. An efficient and reproducible method to measure the intracellular metabolites of a specific microbial organism is a key prerequisite for utilizing metabolome analysis in microbiological research. In this chapter, we describe a workflow focusing on the extraction and quantification of intracellular metabolites of Staphylococcus aureus. Fast quenching with chilled methanol is applied to minimize metabolite leakage, while solvent extraction is used to obtain both polar and nonpolar fractions, which are then analyzed by respective liquid chromatography-mass spectrometry (LC-MS) methods for characterizing and quantifying the intracellular metabolites of S. aureus. This protocol is demonstrated to be an efficient method for analyzing polar and nonpolar intracellular metabolites of S. aureus.

11.
Onco Targets Ther ; 12: 9367-9376, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31807017

RESUMO

Objective: To uncover the specific function of linc00511 in the progression of liver hepatocellular carcinoma (LIHC) and the underlying mechanism. Patients and methods: GEPIA dataset containing 9736 LIHC samples and 857 normal samples were downloaded from TCGA. Expression pattern and prognostic potential of linc00511 in LIHC were analyzed. Subsequently, expression level of linc00511 in LIHC tissues collected in our hospital and cell lines were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Differential expressions of linc00511 in LIHC with different tumor grades and metastatic status were compared. After transfection of si-linc00511, proliferative and migratory changes in Huh7 and Hep3B cells were assessed by cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU) and Transwell assay. Lastly, Pearson correlation analysis and qRT-PCR were conducted to investigate the interaction between linc00511 and miR-29c. Results: Linc00511 was upregulated in LIHC tissues and cell lines. Its level was positively correlated to TNM staging, lymphatic metastasis and poor prognosis in LIHC patients. Knockdown of linc00511 attenuated proliferative and migratory abilities in Huh7 and Hep3B cells. In addition, miR-29c was downregulated in LIHC and negatively linked to linc00511 level. A negative interaction between linc00511 and miR-29c could be a regulatory feedback influencing the progression of LIHC. Conclusion: Linc00511 accelerates the proliferation and migration in LIHC, thus aggravating tumor progression. Meanwhile, linc00511 could be utilized as a hallmark predicting poor prognosis in LIHC patients.

12.
Respir Res ; 20(1): 272, 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31796027

RESUMO

BACKGROUND: Lower respiratory tract (LRT) microbiome has been reported to associate with pulmonary diseases. Unregulated inflammation is an underlying cause of variable lung diseases. The lung microbiome may play an important role in the smoking-induced inflammatory lung diseases. What's more, the function of microbiome may be more important for understanding how microbes interact with host. Our study aims to explore the effects of smoking on the lower respiratory tract microbiome, the association between variation of lower respiratory tract microbiome and inflammation and whether smoking exposure changes the function of lower respiratory tract microbime. METHODS: Forty male mice were randomly divided into smoking group and non-smoking group, and the smoking group was exposed to cigarette smoke for 2 h per day for 90 days. After experiment, the blood samples were collected to measure the concentration of interleukin-6 (IL-6) and C reactive protein (CRP) by ELISA. Lung tissue samples were used to detect the community and diversity of lower respiratory tract microbiome through 16S rRNA gene quantification and sequencing technology. ANOSIM and STAMP were performed to analyze the differences of the microbial community structure between smoking group and non-smoking group. SPSS 24.0 software was used to analyze the correlations between microbiome and inflammation mediators through scatter plots and Spearman correlation coefficient. Microbial metabolic function was predicted by PICRUSt based on the 16 s rRNA gene quantification and sequencing results. PATRIC database was searched for the potential pathogenic bacteria in lower respiratory tract. RESULTS: Our results suggested that smoking had markedly effects on the microbiota structure of lower respiratory tract based on Bray-Curtis distance (R2 = 0.084, p = 0.005) and on unweighted uniFrac distance (R2 = 0.131, p = 0.002). Smoking mainly affected the abundance of microbiome which belong to Proteobacteria phyla and Firmicutes phyla. Moreover, our results also found that smoking increased the abundance of Acinetobacter, Bacillus and Staphylococcus, which were defined as pathogenic bacteria. Inflammatory mediators were observed to associate with certain microbiome at every level. Most of microbiome which were associated with inflammation belonged to Proteobacteria phyla or Firmicutes phyla. Moreover, we found that the decreased microbiome in smoking group, including Oceanospirillales, Desulfuromonadales, Nesterenkonia, and Lactobacillaceae, all were negatively correlated with IL-6 or CRP. Based on the level of inflammation, the abundance of microbiome differs. At genus level, Lactobacillus, Pelagibacterium, Geobacter and Zoogloea were significantly higher in smoking group with lower IL-6 concentration. The abundance of microbiome was not observed any statistical difference in subgroups with different weight. Three dominant genus, defined as pathogen, were found higher in the smoking group. The microbial functional prediction analysis revealed that ABC-type transport systems, transcription factors, amino acide transport and metabolism, arginine and proline metabolism et al. were distinctively decreased in smoking group, while the proportions of replication, recombination and repair, ribosome, DNA repair and recombination proteins were increased in smoking group (q < 0.05). CONCLUSIONS: Members of Proteobacteria phyla and Firmicutes phyla played an important role in the microbial community composition and keeping a relatively balanced homeostasis. Microbiome dysbiosis might break the balance of immune system to drive lung inflammation. There might exist potential probiotics in lower respiratory tract, such as Lactobacillaceae. The altered function of Lower respiratory tract microbiome under smoking exposure may affect the physiological homeostasis of host.

13.
Hum Brain Mapp ; 2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31849148

RESUMO

Previous neuroimaging studies have mainly focused on alterations of static and dynamic functional connectivity in patients with generalized anxiety disorder (GAD). However, the characteristics of local brain activity over time in GAD are poorly understood. This study aimed to investigate the abnormal time-varying local brain activity of GAD by using the amplitude of low-frequency fluctuation (ALFF) method combined with sliding-window approach. Group comparison results showed that compared with healthy controls (HCs), patients with GAD exhibited increased dynamic ALFF (dALFF) variability in widespread regions, including the bilateral dorsomedial prefrontal cortex, hippocampus, thalamus, striatum; and left orbital frontal gyrus, inferior parietal lobule, temporal pole, inferior temporal gyrus, and fusiform gyrus. The abnormal dALFF could be used to distinguish between patients with GAD and HCs. Increased dALFF variability values in the striatum were positively correlated with GAD symptom severity. These findings suggest that GAD patients are associated with abnormal temporal variability of local brain activity in regions implicated in executive, emotional, and social function. This study provides insight into the brain dysfunction of GAD from the perspective of dynamic local brain activity, highlighting the important role of dALFF variability in understanding neurophysiological mechanisms and potentially informing the diagnosis of GAD.

14.
Curr Med Sci ; 39(6): 984-989, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31845231

RESUMO

Parenchymal neurocysticercosis is the most common form of neurocysticercosis in the central nervous system (CNS), which mainly causes epilepsy and usually responses well to routine medications. However, there are appreciable cases of relapses refractory to medical treatment. We investigated microsurgical treatment of epilepsy with parenchymal neurocysticercosis. Nine cases of epilepsy caused by parenchymal neurocysticercosis from 2002 to 2018 were analyzed retrospectively. Cysts in 7 cases were completely removed. No case died of operation and no new dysfunction of the nervous system was observed after surgery. Among the other 9 cases, 8 cases became seizure-free or controlled by medicine according to the postoperative follow-up for 6 months to 9 years. One case was lost for follow-up. It was suggested that epilepsy with parenchymal neurocysticercosis can usually be controlled after routine medications. However, surgery is still indicated in some cases and careful microsurgery is associated with satisfactory clinical outcomes in appropriately selected cases.

15.
Nan Fang Yi Ke Da Xue Xue Bao ; 39(11): 1381-1386, 2019 Nov 30.
Artigo em Chinês | MEDLINE | ID: mdl-31852637

RESUMO

The CRISPR/Cas9 technology has developed rapidly in recent years with fast, simple and accurate editing functions to allow gene knockout, knock in, activation and interference. It has become a powerful genetic screening tool and been widely used in various models including cell lines, mice and zebrafish. The application of CRISPR system in constructing genome library for high-throughput screening is the main strategy for target gene research of diseases, especially neoplasms. Here we summarize the rationales and recent development of CRISPR/Cas9 library screening technology, the strategies for improving the off-target effects, the basic workflow of library screening and the application of this technology in tumor research.


Assuntos
Sistemas CRISPR-Cas , Animais , Detecção Precoce de Câncer , Técnicas de Inativação de Genes , Biblioteca Gênica , Camundongos
16.
Colloids Surf B Biointerfaces ; : 110714, 2019 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-31870518

RESUMO

Biomaterials composed of polymers and bioceramics have great prospects to repair large and complicated bone defects. Here, we developed a composite film consisting of poly(ε-caprolactone) (PCL) and silicon-substituted hydroxyapatite (Si-HA) nanoparticles to enhance the osteogenic effects of the scaffold for bone tissue engineering applications. The results showed that the Si-HA nanoparticles obtained an even distribution in the PCL matrix, resulting in a homogeneous composite film. Compared to HA-incorporated PCL film, the addition of silicon did not cause hydrophilic alterations to the film surface. With the seeding of mouse calvarial preosteoblasts (MC3T3-E1), the cells exhibited the good behaviors of adhesion and growth on the PCL/Si-HA film. Compared to the PCL/HA films, incorporation of Si-HA nanoparticles in PCL/Si-HA films showed the increased production of alkaline phosphatase (ALP) and calcium content by MC3T3-E1 cells. These results suggested the suitability of the PCL/Si-HA composite film to elicit cellular growth and functional differentiation with the potential for bone tissue engineering applications.

17.
Nanoscale Res Lett ; 14(1): 352, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31781982

RESUMO

Magnetic nanomaterials were functionalized with dopamine hydrochloride as the functional reagent to afford a core-shell-type Fe3O4 modified with polydopamine (Fe3O4@PDA) composite, which was used for the adsorption of cadmium ions from an aqueous solution. In addition, the effects of environmental factors on the adsorption capacity were investigated. Furthermore, the adsorption kinetics, isotherm, and thermodynamics of the adsorbents were discussed. Results revealed that the adsorption of cadmium by Fe3O4@PDA reaches equilibrium within 120 min, and kinetic fitting data are consistent with the pseudo-second-order kinetics (R2 > 0.999). The adsorption isotherm of Cd2+ on Fe3O4@PDA was in agreement with the Freundlich model, with the maximum adsorption capacity of 21.58 mg/g. The thermodynamic parameters revealed that adsorption is inherently endothermic and spontaneous. Results obtained from the adsorption-desorption cycles revealed that Fe3O4@PDA exhibits ultra-high adsorption stability and reusability. Furthermore, the adsorbents were easily separated from water under an enhanced external magnetic field after adsorption due to the introduction of an iron-based core. Hence, this study demonstrates a promising magnetic nano-adsorbent for the effective removal of cadmium from cadmium-containing wastewater.

18.
J Am Chem Soc ; 141(51): 20215-20221, 2019 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-31774667

RESUMO

n-Doped conjugated polymers usually show low electrical conductivities and low thermoelectric power factors, limiting their applications in n-type organic thermoelectrics. Here, we report the synthesis of a new diketopyrrolopyrrole (DPP) derivative, pyrazine-flanked DPP (PzDPP), with the deepest LUMO level in all the reported DPP derivatives. Based on PzDPP, a donor-acceptor copolymer, P(PzDPP-CT2), is synthesized. The polymer displays a deep LUMO energy level and strong interchain interaction with a short π-π stacking distance of 3.38 Å. When doped with n-dopant N-DMBI, P(PzDPP-CT2) exhibits high n-type electrical conductivities of up to 8.4 S cm-1 and power factors of up to 57.3 µW m-1 K-2. These values are much higher than previously reported n-doped DPP polymers, and the power factor also ranks the highest in solution-processable n-doped conjugated polymers. These results suggest that PzDPP is a promising high-performance building block for n-type organic thermoelectrics and also highlight that, without sacrificing polymer interchain interactions, efficient n-doping can be realized in conjugated polymers with careful molecular engineering.

19.
Front Neurosci ; 13: 1063, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31680808

RESUMO

Regarding the determination of the biomechanical parameters in a reliable in vitro cell model for diffuse axonal injury (DAI), our study aimed to demonstrate connections between those parameters and secondary axotomy through examination of morphological alterations under a variety of traumatic conditions. An in vitro cell model for DAI was established in primary cultured mouse neurons by uniaxial mechanical stretching of non-myelinated axons under various traumatic conditions: strain (ε) = 5, 10, 20, and 50%; strain time (t) = 500, 100, and 20 ms; strain rate ranging between 0.1 and 25 s-1. Axonal real strains (strainaxon) were measured as 4.53 ± 0.27, 9.02 ± 0.91, 17.75 ± 1.65, and 41.8 ± 4.4%. Axonal real strain rates (SRaxon) ranged between 0.096 ± 0.0054 and 20.9 ± 2.2 s-1. Results showed there was no obvious abnormality of axons with a lower strain condition (strainaxon < 17.75 ± 1.65%) during the acute phase within 30 min after injury. In contrast, acute axonal degeneration (AAD) was observed in the axons following injury with a higher strain condition (SRaxon > 17.75 ± 1.65%). In addition, the incidence and degree of AAD were closely correlated with strain rate. Specifically, AAD occurred to all axons that were examined, when ε = 50% (strainaxon = 41.8 ± 4.4%) for 20 ms, while no spontaneous rupture was observed in those axons. Besides, the concentration of Ca2+ within the axonal process was significantly increased under such traumatic conditions. Moreover, the continuity of axon cytoskeleton was interrupted, eventually resulting in neuronal death during subacute stage following injury. In this study, we found that there is a minimum strain threshold for the occurrence of AAD in non-myelinated axons of primary cultured mouse neurons, which ranges between 9.02 ± 0.91 and 17.75 ± 1.65%. Basically, the severity of axonal secondary axotomy post DAI is strain rate dependent under a higher strain above the threshold. Hence, a reliable and reproducible in vitro cell model for DAI was established, when ε = 50% (strainaxon = 41.8 ± 4.4%) for 20 ms.

20.
Opt Lett ; 44(21): 5186-5189, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31674963

RESUMO

An optical diffractive neural network (DNN) can be implemented with a cascaded phase mask architecture. Like an optical computer, the system can perform machine learning tasks such as number digit recognition in an all-optical manner. However, the system can work only under coherent light illumination, and the precision requirement in practical experiments is quite high. This Letter proposes an optical machine learning framework based on single-pixel imaging (MLSPI). The MLSPI system can perform the same linear pattern recognition task as DNN. Furthermore, it can work under incoherent lighting conditions, has lower experimental complexity, and can be easily programmable.

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