Search

The incorporation of a material-based or artificial saturable absorber into a fiber laser cavity imposes a limitation on energy enhancement owing to its low damage threshold and high environmental sensitivity. To address this issue, one promising alternative approach is the utilization of the self-mode-locking technique. Here, we present a robust self-mode-locked Tm-doped fiber laser with high pulse energy emission. A simple and compact fiber laser structure is realized by utilizing a section of a Tm-doped fiber, serving both as a gain medium and a saturable absorber. Thus, the operational stability is enhanced, especially under high-energy conditions. Furthermore, the realization of high-energy pulses is accomplished through the integration of dispersion management technique. Experimental results reveal that the maximum single-pulse energy increases from 34.8 pJ to 120.2 nJ as the round-trip group delay dispersion decreases from −0.43 to −12.40 ps2. The proposed self-mode-locked Tm-doped fiber laser under high-energy operation exhibits remarkable performance. Our results provide a simple approach to obtaining a mid-infrared laser source with high pulse energy and hold significant potential for advancing high-energy laser systems. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) have shown great potential for the treatment of liver injuries, and the therapeutic efficacy greatly depends on their homing to the site of injury. In the present study, we detected significant upregulation of hepatocyte growth factor (HGF) in the serum and liver in mice with acute or chronic liver injury. In vitro study revealed that upregulation of miR-9-5p or miR-221-3p promoted the migration of human MSCs (hMSCs) toward HGF. Moreover, overexpression of miR-9-5p or miR-221-3p promoted hMSC homing to the injured liver and resulted in significantly higher engraftment upon peripheral infusion. hMSCs reduced hepatic necrosis and inflammatory infiltration but showed little effect on extracellular matrix (ECM) deposition. By contrast, hMSCs overexpressing miR-9-5p or miR-221-3p resulted in not only less centrilobular necrosis and venous congestion but also a significant reduction of ECM deposition, leading to obvious improvement of hepatocyte morphology and alleviation of fibrosis around central vein and portal triads. Further studies showed that hMSCs inhibited the activation of hepatic stellate cells (HSCs) but could not decrease the expression of TIMP-1 upon acute injury and the expression of MCP-1 and TIMP-1 upon chronic injury, while hMSCs overexpressing miR-9-5p or miR-221-3p led to further inactivation of HSCs and downregulation of all three fibrogenic and proinflammatory factors TGF-β, MCP-1, and TIMP-1 upon both acute and chronic injuries. Overexpression of miR-9-5p or miR-221-3p significantly downregulated the expression of α-SMA and Col-1α1 in activated human hepatic stellate cell line LX-2, suggesting that miR-9-5p and miR-221-3p may partially contribute to the alleviation of liver injury by preventing HSC activation and collagen expression, shedding light on improving the therapeutic efficacy of hMSCs via microRNA modification. [ABSTRACT FROM AUTHOR]

During the service process of a bearingless motorized spindle (BLMS), its parameters change with both time and external conditions, leading to a decrease in the accuracy of the motorized spindle. Therefore, it is difficult to accurately describe the dynamic performance of a motorized spindle during its actual operation using deterministic parameters. In this paper, the interactions between the thermal deformation and vibration of a motorized spindle are explored. A dynamic model of the motorized spindle based on multibody dynamics and time-varying parameters is established, and a solution method for the dynamic model with uncertain parameters is investigated. Firstly, the reasons for the vibration in the BLMS are analyzed, and the influences of thermal deformation on the thermal eccentricity and inhomogeneous air gap of the BLMS are studied. A vibration model of the BLMS is established and solved to acquire the radial vibration displacement. Secondly, a discrete multibody dynamics model of the BLMS is built, and the center trajectory of the motorized spindle is attained by solving the multibody dynamics model. A prototype experimental platform of the BLMS is designed, and vibration tests are carried out. The experimental results show that the vibration amplitude of the BLMS increases with the running time and the maximum displacement exhibits a large deviation from the simulation results using the determined parameters, while there is a small deviation from the simulation results using uncertain parameters; this indicates that the solution of the multibody dynamics model of the BLMS described by uncertain parameters is closer to the experimental data. These research findings can provide a reference for the optimized design of BLMSs. [ABSTRACT FROM AUTHOR]

Accumulating evidence suggests that cancer-associated fibroblast (CAF) macroautophagy/autophagy is crucial in tumor development and may be a therapeutic target for pancreatic ductal adenocarcinoma (PDAC). However, the role of CAF autophagy during immune surveillance and cancer immunotherapy is unclear. The present study revealed that the inhibition of CAF autophagy suppresses in vivo tumor development in immune-deficient xenografts. This deletion compromises anti-tumor immunity and anti-tumor efficacy both in vitro and in vivo by upregulating CD274/PDL1 levels in an immune-competent mouse model. A block in CAF autophagy reduced the production of IL6 (interleukin 6), disrupting high desmoplastic TME and decreasing USP14 expression at the transcription level in pancreatic cancer cells. We further identify USP14 as the post-translational factor responsible for downregulating CD274 expression by removing K63 linked-ubiquitination at the K280 residue. Finally, chloroquine diphosphate-loaded mesenchymal stem cell (MSC)-liposomes, by accurately targeting CAFs, inhibited CAF autophagy, improving the efficacy of immunochemotherapy to combat pancreatic cancer. Abbreviation: AIR: adaptive immune resistance; ATRA: all-trans-retinoicacid; CAF: cancer-associated fibroblast; CD274/PDL1: CD274 molecule; CM: conditioned medium; CQ: chloroquine diphosphate; CyTOF: Mass cytometry; FGF2/bFGF: fibroblast growth factor 2; ICB: immune checkpoint blockade; IF: immunofluorescence; IHC: immunohistochemistry; IP: immunoprecipitation; MS: mass spectrometer; MSC: mesenchymal stem cell; PDAC: pancreatic ductal adenocarcinoma; TEM: transmission electron microscopy; TILs: tumor infiltrating lymphocytes; TME: tumor microenvironment; USP14: ubiquitin specific peptidase 14. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are typical contaminants in soil, and the high‐molecular‐weight (HMW) PAHs are especially recalcitrant to remove. Microbial degradation as a promising approach has been used in PAH‐polluted soil remediation; however, the removal of HMW PAHs still needs to be further explored. In order to isolate more HMW‐PAH‐degrading strains and improve the removal of HMW PAHs in long‐term contaminated soil. Benzo[a]pyrene (BaP), as a representative HMW PAH was selected to explore the removal of HMW PAHs from soil. A BaP‐degrading strain named Achromobacter xylosoxidans B‐2 was isolated, and its degradation ability was explored in mineral salt medium (MSM) and PAH‐contaminated soil. Cosubstrates were added to enhance the removal of PAHs in soil. The results showed that A. xylosoxidans B‐2 could remove 87% of BaP at a concentration of 1 mg/L within 15 days in MSM. The average removal efficiency of HMW PAHs in soil was 19.92% after 30‐day bioremediation by A. xylosoxidans B‐2. Salicylic acid as cosubstrate increased the removal efficiency by 11.32%–14.66% for five‐ring PAHs and 9.72%–13.02% for six‐ring PAHs, respectively. The addition of cosubstrate not only improved the soil properties but also stimulated the soil microbial activity to enhance the removal of HMW PAHs. This study may provide new insights into bioremediation for HMW‐PAH‐contaminated soil. [ABSTRACT FROM AUTHOR]

Lipid metabolism plays an important role in the repair of skin wounds. Studies have shown that acupuncture is very effective in skin wound repair. However, there is little knowledge about the mechanism of electroacupuncture. Thirty‐six SD rats were divided into three groups: sham‐operated group, model group and electroacupuncture group, with six rats in each group. After the intervention, orbital venous blood was collected for lipid metabolomics analysis, wound perfusion was detected and finally the effect of electroacupuncture on skin wound repair was comprehensively evaluated by combining wound healing rate and histology. Lipid metabolomics analysis revealed 11 differential metabolites in the model versus sham‐operated group. There were 115 differential metabolites in the model versus electro‐acupuncture group. 117 differential metabolites in the electro‐acupuncture versus sham‐operated group. There were two differential metabolites common to all three groups. Mainly cholesteryl esters and sphingolipids were elevated after electroacupuncture and triglycerides were largely decreased after electroacupuncture. The electroacupuncture group recovered faster than the model group in terms of blood perfusion and wound healing (p < 0.05). Electroacupuncture may promote rat skin wound repair by improving lipid metabolism and improving local perfusion. [ABSTRACT FROM AUTHOR]

The road performance and temperature-regulating properties of asphalt binders modified with novel polyethylene glycol (PEG)/porous silica (PS) form-stabilized phase-change materials (PEG/PS-fs-PCMs) were studied. PS and PEG were used as the supporting substance and PCMs. The results showed that PEG/PS-fs-PCMs could maintain a maximum weight percentage of 70% without leakage, at temperatures as high as 90 °C. The PEG/PS-fs-PCMs exhibited stable chemical structures, excellent thermal stability, high heat storage density, and suitable phase-change temperature. Based on conventional physical tests, the addition of PEG/PS-fs-PCMs can increase the viscosity and the degree of hardness of asphalt binders; thus, achieving an excellent comprehensive performance of the modified asphalt binder depends on determining the optimal dosage of PEG/PS-fs-PCMs. Additionally, incorporating PEG/PS-fs-PCM particles into the asphalt binder can enhance its ability to withstand permanent deformation at elevated temperatures, while PEG/PS-fs-PCMs mainly act as a filler, weakening the cohesive force of the asphalt molecules, and preventing the ductility of asphalt from expansion, according to DSR and BBR tests. Moreover, the use of PEG/PS-fs-PCMs can enhance the heat transfer properties of the asphalt binders, resulting in an improved temperature regulation performance. However, the accumulation of PEG/PS-fs-PCM particles on asphalt binders can negatively impact the storage stability of the modified asphalt binders, because of the difference in density between the two materials. [ABSTRACT FROM AUTHOR]

Aiming at some stress-induced failure phenomena in surrounding rock that occur during the construction of super-long and deep-buried tunnels, a method for estimating the in situ stress in the tunnels based on multivariate information integration is proposed, which uses a small amount of in situ stress measurement, stereographic projection technology, and a numerical simulation method. Firstly, by conducting a macroscopic analysis of the regional geological structure, topography, and pre-excavated small tunnels (such as exploration of adits and pilot tunnels), the strength of the tectonic stress field and the orientation of the principal stresses in the tunnel sections are preliminarily determined. Secondly, the reliability of the in situ stress measurement data were analyzed using full-space stereographic projection and the plane stress projection method. Then, some representative measurement points that reflected the distribution characteristics of in situ stress in the project area, on the whole, were determined. Thirdly, the finite difference (FDM) and multiple regression analysis (MRA) methods were used to inverse the in situ stress field in the project area. The proposed method was applied to a super-long and deep-buried tunnel project in Qinling, and the in situ stress distribution characteristics of the tunnel sections at different mileages were obtained. The results show that both the calculated principal stress values and the azimuth angle of the maximum horizontal principal stress are in good agreement with the measured ones, indicating that the method used in this study is reasonable. Finally, the typical surrounding rock failure phenomena encountered during the excavation of the project were investigated, and targeted treatment measures were proposed. The research results can provide references for support design and disaster management of surrounding rock in deep-buried long tunnels. [ABSTRACT FROM AUTHOR]

Background: Continuous exposure to stressors can lead to vulnerability and, in some cases, resilience. This study examined the variation in its psychological impact across the first four waves of COVID-19 in Hong Kong. Methods: Transcripts from Open Up, an online text-based counseling service, between January 2019 and January 2021 were analyzed (N = 60 775). We identified COVID-19 mentioned sessions using keywords and further categorized them into those that also mentioned symptoms of common mental disorders (CMDs) and those that did not. Autoregressive integrated moving average models were used to analyze the associations between the severity of the outbreak and the mention of COVID-19 and CMDs. Results: Results revealed that the pandemic led to increased psychological distress. Compared to prior to its advent, more people sought help in the initial months of the outbreak. Furthermore, associations were found between the severity of the outbreak and the number of help-seeker mentioning the pandemic, as well as between the outbreak severity and the number of help-seekers disclosing psychological distress. However, these relationships were not uniform across the four waves of outbreaks; a dissociation between outbreak severity and help-seekers' concern was found in the fourth wave. Conclusion: As the pandemic waxes and wanes, people may become habituated to its psychological toll. This may be interpreted as a form of resilience. Instead of worsening with time, the psychological impact of COVID-19 may reduce with repeated exposure. [ABSTRACT FROM AUTHOR]

Waterborne epoxy resin (WER) emulsified asphalt (WEREA) has the advantages of high viscosity and strength of epoxy asphalt, as well as a simple construction process, so it is used widely in asphalt pavement maintenance and repair projects. This paper investigated the comprehensive properties, the microstructure, the modification mechanism, and the strength formation mechanism of WEREA. The results of bond strength tests, adhesion tests between emulsified asphalt and coarse aggregate, conventional performance tests, and multistress creep recovery (MSCR) tests showed that with the increase of WER content, the adhesive properties and creep recovery properties at high temperature of the WEREA gradually improved, and gradually became the properties of brittle materials. When the WER content was 15%, the irrecoverable creep compliance of the WEREA stabilized and it met heavy traffic demand. In addition, fluorescence microscopy (FM) and scanning electron microscopy (SEM) showed that WER changed from having an island structure to having an epoxy skeleton structure in the WEREA. The results of Fourier-transform infrared (FTIR) testing showed that during the modification of the emulsified asphalt by the WER, no new substances were generated, which indicated that the sample possessed the mechanism of intermolecular physical blending. The test results were used to analyze the strength formation process of WEREA, which provides theoretical guidance for other researchers to study WEREA. [ABSTRACT FROM AUTHOR]