Tin diselenide (SnSe2) nanosheets as novel 2D layered materials have excellent optical properties with many promising application prospects, such as photoelectric detectors, nonlinear optics, ...infrared photoelectric devices, and ultrafast photonics. Among them, ultrafast photonics has attracted much attention due to its enormous advantages; for instance, extremely fast pulse, strong peak power, and narrow bandwidth. In this work, SnSe2 nanosheets are fabricated by using solvothermal treatment, and the characteristics of SnSe2 are systemically investigated. In addition, the solution of SnSe2 nanosheets is successfully prepared as a fiber‐based saturable absorber by utilizing the evanescent field effect, which can bear a high pump power. 31st‐order subpicosecond harmonic mode locking is generated in an Er‐doped fiber laser, corresponding to the maximum repetition rate of 257.3 MHz and pulse duration of 887 fs. The results show that SnSe2 can be used as an excellent nonlinear photonic device in many fields, such as frequency comb, lasers, photodetectors, etc.
Tin diselenide (SnSe2) nanosheets as novel 2D layered materials have excellent optical properties. SnSe2 nanosheets fabricated by using solvothermal treatment are successfully prepared as fiber‐based saturable absorbers by utilizing the evanescent field effect, which can bear a high pump power. 31st‐order subpicosecond harmonic mode‐locking is generated, corresponding to 257.3 MHz repetition rate.
Abstract
Covalent organic frameworks (COFs) with structural designability and tunability of photophysical properties enable them to be a promising class of organic luminescent materials by ...incorporating well‐designed fluorescent units directly into the periodic skeletons. The photophysical properties of COFs are mainly affected by the structural features, which determine the conjugation degree, charge delocalization ability, and exciton dynamics of COFs. To understand the relationship between COF structures and their photophysical properties, two COFs with the same pyrene chromophore units but different linkages (imine or vinylene) were designed and synthesized. Interestingly, different linkages endow COFs with huge differences in solid‐state photoluminescence quantum yield (PLQY) for imine‐ and vinylene‐linked pyrene‐based COFs, which possess PLQY values of 0.34 % and 15.43 %, respectively. The femtosecond‐transient absorption spectra and time‐dependent density functional theory reveal the different charge‐transfer pathways in imine‐ and vinylene‐linked COFs, which influence the exciton relaxation way and fluorescence intensity. In addition, an effective white‐light device was obtained by coating the vinylene‐linked COF on a light‐emitting diode strip.
Constructing a powerful photocatalytic system that can achieve the carbon dioxide (CO2) reduction half‐reaction and the water (H2O) oxidation half‐reaction simultaneously is a very challenging but ...meaningful task. Herein, a porous material with a crystalline topological network, named viCOF‐bpy‐Re, was rationally synthesized by incorporating rhenium complexes as reductive sites and triazine ring structures as oxidative sites via robust −C=C− bond linkages. The charge‐separation ability of viCOF‐bpy‐Re is promoted by low polarized π‐bridges between rhenium complexes and triazine ring units, and the efficient charge‐separation enables the photogenerated electron–hole pairs, followed by an intramolecular charge‐transfer process, to form photogenerated electrons involved in CO2 reduction and photogenerated holes that participate in H2O oxidation simultaneously. The viCOF‐bpy‐Re shows the highest catalytic photocatalytic carbon monoxide (CO) production rate (190.6 μmol g−1 h−1 with about 100 % selectivity) and oxygen (O2) evolution (90.2 μmol g−1 h−1) among all the porous catalysts in CO2 reduction with H2O as sacrificial agents. Therefore, a powerful photocatalytic system was successfully achieved, and this catalytic system exhibited excellent stability in the catalysis process for 50 hours. The structure–function relationship was confirmed by femtosecond transient absorption spectroscopy and density functional theory calculations.
A crystalline network is constructed by incorporating rhenium complexes and triazine ring structures as catalytic sites via robust −C=C− bonding. Appreciable charge‐separation and transfer efficiency drive both the photocatalytic oxidative and reductive reactions in the conversion of CO2 to CO with H2O, and without any additional sacrificial agents or photosensitizers.
Stem cell transplantation therapy has emerged as a potential treatment for ischemic stroke and other neurodegenerative diseases. Effective delivery of exogenous cells and homing of these cells to the ...lesion region, however, have been challenging issues that hinder the efficacy and efficiency of cell-based therapy. In the present investigation, we tested a delayed treatment of noninvasive and brain-targeted intranasal delivery of bone marrow mesenchymal stem cells (BMSCs) in a mouse focal cerebral ischemia model. The investigation tested the feasibility and effectiveness of intranasal delivery of BMSCs to the ischemic cortex. Hypoxia preconditioning (HP) of BMSCs was performed before transplantation in order to promote their survival, migration, and homing to the ischemic brain region after intranasal transplantation. Hoechst dye-labeled normoxic- or hypoxic-pretreated BMSCs (1 × 106 cells/animal) were delivered intranasally 24 h after stroke. Cells reached the ischemic cortex and deposited outside of vasculatures as early as 1.5 h after administration. HP-treated BMSCs (HP-BMSCs) showed a higher level of expression of proteins associated with migration, including CXC chemokine receptor type 4 (CXCR4), matrix metalloproteinase 2 (MMP-2), and MMP-9. HP-BMSCs exhibited enhanced migratory capacities in vitro and dramatically enhanced homing efficiency to the infarct cortex when compared with normoxic cultured BMSCs (N-BMSCs). Three days after transplantation and 4 days after stroke, both N-BMSCs and HP-BMSCs decreased cell death in the peri-infarct region; significant neuroprotection of reduced infarct volume was seen in mice that received HP-BMSCs. In adhesive removal test of sensorimotor functional assay performed 3 days after transplantation, HP-BMSC-treated mice performed significantly better than N-BMSC- and vehicle-treated animals. These data suggest that delayed intranasal administration of stem cells is feasible in the treatment of stroke and hypoxic preconditioning of transplanted cells, significantly enhances cell's homing to the ischemic region, and optimizes the therapeutic efficacy.
Abstract
Chronic pain causes both physical suffering and comorbid mental symptoms such as anhedonia. However, the neural circuits and molecular mechanisms underlying these maladaptive behaviors ...remain elusive. Here using a mouse model, we report a pathway from vesicular glutamate transporter 3 neurons in the dorsal raphe nucleus to dopamine neurons in the ventral tegmental area (VGluT3
DRN
→
DA
VTA
) wherein population-level activity in response to innocuous mechanical stimuli and sucrose consumption is inhibited by chronic neuropathic pain. Mechanistically, neuropathic pain dampens VGluT3
DRN
→ DA
VTA
glutamatergic transmission and DA
VTA
neural excitability. VGluT3
DRN
→ DA
VTA
activation alleviates neuropathic pain and comorbid anhedonia-like behavior (CAB) by releasing glutamate, which subsequently promotes DA release in the nucleus accumbens medial shell (NAcMed) and produces analgesic and anti-anhedonia effects via D2 and D1 receptors, respectively. In addition, VGluT3
DRN
→ DA
VTA
inhibition produces pain-like reflexive hypersensitivity and anhedonia-like behavior in intact mice. These findings reveal a crucial role for VGluT3
DRN
→ DA
VTA
→ D2/D1
NAcMed
pathway in establishing and modulating chronic pain and CAB.
Malignant astrocytoma (MA) is the most common and severe type of brain tumor. A greater understanding of the underlying mechanisms responsible for the development of MA would be beneficial for the ...development of targeted molecular therapies. In the present study, the upregulated differentially expressed genes (DEGs) in MA were obtained from the Gene Expression Omnibus database using R/Bioconductor software. DEGs in different World Health Organization classifications were compared using the Venny tool and 15 genes, including collagen type I α1 chain (COL1A1) and laminin subunit γ1 (LAMC1), were revealed to be involved in the malignant progression of MA. In addition, the upregulated DEGs in MA were evaluated using functional annotations of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes with the Database for Annotation, Visualization, and Integrated Discovery tool. The results indicated that invasion‑associated enrichment was observed in 'extracellular matrix' (ECM), 'cell adhesion' and 'phosphoinositide 3‑kinase‑protein kinase B signaling pathway'. Subsequently, the analysis of the protein‑protein interactions was performed using STRING and Cytoscape software, which revealed that the ECM component was the invasion‑associated module and its corresponding genes included COL1A1, LAMC1 and fibronectin 1. Finally, survival Kaplan‑Meier estimate was conducted using cBioportal online, which demonstrated that COL1A1 expression affected the survival of and recurrence in patients with MA. Moreover, the results of in vitro Transwell assay and western blot analysis revealed that the depleted levels of COL1A1 also decreased the expression of several proteins associated with cell invasion, including phosphorylated‑signal transducer and activator of transcription 3, matrix metalloproteinase (MMP)‑2, MMP‑9 and nuclear factor‑κB. On the whole, the present study identified the invasion‑related target genes and the associated potential pathways in MA. The results indicated that COL1A1 may be a candidate biomarker for the prognosis and treatment of MA.
Chronic stress and chronic pain are two major predisposing factors to trigger depression. Enhanced excitatory input to the lateral habenula (LHb) has been implicated in the pathophysiology of ...depression. However, the contribution of inhibitory transmission remains unclear. Here, we dissect an inhibitory projection from the sensory thalamic reticular nucleus (sTRN) to the LHb, which is activated by acute aversive stimuli. However, chronic restraint stress (CRS) weakens sTRN-LHb synaptic strength, and this synaptic attenuation is indispensable for CRS-induced LHb neural hyperactivity and depression onset. Moreover, artificially inhibiting the sTRN-LHb circuit induces depressive-like behaviors in healthy mice, while enhancing this circuit relieves depression induced by both chronic stress and chronic pain. Intriguingly, neither neuropathic pain nor comorbid mechanical hypersensitivity in chronic stress is affected by this pathway. Altogether, our study demonstrates an sTRN-LHb circuit in establishing and modulating depression, thus shedding light on potential therapeutic targets for preventing or managing depression.
Display omitted
•The sensory TRN (sTRN) directly projects to the LHb•Chronic stress attenuates synaptic strength of the sTRN-LHb circuit•LHb-projecting sTRN neural activation prevents depression onset under chronic stress•sTRN-LHb circuit activation restores depressive symptoms in chronic stress or pain
Wang et al. dissected an inhibitory input to the lateral habenula (LHb) that regulates depressive-like behaviors. They demonstrate that chronic stress dampens the synaptic strength of the sensory thalamic reticular nucleus (sTRN)-LHb circuit that underlies depression onset. sTRN-LHb pathway activation produces antidepressant effects in both chronic stress and chronic pain.
Abstract
Background
To investigate the diagnostic performance of parameters derived from monoexponential, biexponential, and stretched-exponential diffusion-weighted imaging models in differentiating ...tumour progression from pseudoprogression in glioblastoma patients.
Methods
Forty patients with pathologically confirmed glioblastoma exhibiting enhancing lesions after completion of chemoradiation therapy were enrolled in the study, which were then classified as tumour progression and pseudoprogression. All patients underwent conventional and multi-b diffusion-weighted MRI. The apparent diffusion coefficient (ADC) from a monoexponential model, the true diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) from a biexponential model, and the distributed diffusion coefficient (DDC) and intravoxel heterogeneity index (α) from a stretched-exponential model were compared between tumour progression and pseudoprogression groups. Receiver operating characteristic curves (ROC) analysis was used to investigate the diagnostic performance of different DWI parameters. Interclass correlation coefficient (ICC) was used to evaluate the consistency of measurements.
Results
The values of ADC, D, DDC, and α values were lower in tumour progression patients than that in pseudoprogression patients (
p
< 0.05). The values of D* and f were higher in tumour progression patients than that in pseudoprogression patients (
p
< 0.05). Diagnostic accuracy for differentiating tumour progression from pseudoprogression was highest for α(AUC = 0.94) than that for ADC (AUC = 0.91), D (AUC = 0.92), D* (AUC = 0.81), f (AUC = 0.75), and DDC (AUC = 0.88).
Conclusions
Multi-b DWI is a promising method for differentiating tumour progression from pseudoprogression with high diagnostic accuracy. In addition, the α derived from stretched-exponential model is the most promising DWI parameter for the prediction of tumour progression in glioblastoma patients.
Gliomas are the most common malignant tumors of the brain and are characteristic of severe migration and invasion. Glial cell line-derived neurotrophic factor (GDNF) promotes glioma development ...process. However, the regulatory mechanisms of promoting occurrence and development of glioma have not yet been clearly elucidated. In the present study, the mechanism by which GDNF promotes glioma cell migration and invasion through regulating the dispersion and location of the Golgi apparatus (GA) is described. Following GDNF treatment, a change in the volume and position of GA was observed. The stack area of the GA was enlarged and it was more concentrated near the nucleus. Golgin-160 and Golgi microtubule-associated protein 210 (GMAP210) were identified as target molecules regulating GA positioning. In the absence of either golgin-160 or GMAP210 using lentivirus, the migration and invasion of U251 cells were decreased, while it was increased following GDNF. It was also found that the GA was decreased in size and dispersed following golgin-160 or GMAP210 knockdown, as determined by GA green fluorescence assay. Once GDNF was added, the above phenomenon would be twisted, and the concentrated location and volume of the GA was restored. In combination, the present data suggested that the regulation of the position and size of the GA by golgin-160 and GMAP210 play an important role in U251 cell migration and invasion.
Accurate keyhole status prediction is critical for realizing the closed-loop control of the keyhole plasma arc welding (K-PAW) processes for acquiring full-penetration weld joints with high ...efficiency. Visually captured weld pool images from topside provide sufficient information of the liquid metal as well as keyhole behaviors. Weld pool, plasma arc, and keyhole entrance could be clearly recognized reflecting the different features during different keyholing stages. It was proposed to extract the image features automatically based on a deep learning algorithm rather than manually selecting characteristic parameters. Since directly training the deep CNN (convolutional neural network) model using the acquired data led to convergence failure, a well-trained generalized model was employed and fine-tuned accordingly to more easily extract the K-PAW image features. Model training was conducted using obtained dataset, which took weld pool images as input and penetration/keyhole status (partial penetration with a blind keyhole or full penetration with a through keyhole) as output. Underlying correlations between the penetration/keyhole status and topside weld pool images were established. For further verifying the effectiveness and reliability of the trained model, experiments were designed acquiring typical slow keyholing under constant welding current and rapid keyhole switching under pulse welding current. Based on the given data, the verified 90% accuracy was achieved for correctly predicting the keyhole/penetration status. Finally, the visualization of the convolutional layers was carried out, and displayed the features clearly, which is of great significance for understanding the internal mechanism of the neural network.
PDF
