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Acid intercalation-exfoliated 2D Bi shows strong nonlinear NIR responses associated with multi-timescale carrier dynamics and is used for mode-locking lasers.

Liquid-phase exfoliated 2D material multilayer MoS 2 is transferred onto a gold mirror and its saturable absorption at the 2 µm wavelength region is experimentally observed. This transferred MoS 2 saturable absorber has a modulation depth of 13.6% and a saturation intensity of 23.1 MW cm −2 . This saturable absorber is integrated into a linear Tm 3+ fiber laser cavity, and stable fundamental-frequency mode-locking operation is realized at 2 µm with pulse energy of 15.5 nJ, pulse width of ~843 ps, and a repetition rate of 9.67 MHz. The laser spectral width is ~17.3 nm with a center wavelength of 1905 nm. This first presence of modelocking with multilayer MoS 2 sheets in the 2 µm wavelength region verifies that multilayer MoS 2 is a good candidate for broadband mode-locking comparable to graphene, as well as a good mode-locker for achieving high pulse energy.

We briefly review the development of gain-switched rare-earth-doped fiber lasers and their applications in wavelength conversion to mid-IR, supercontinuum generation, and medicine in recent years. We illustrate the similarities between gain-switching and Q-switching techniques that will provide tools for the design and optimization of the gain-switched fiber lasers. From the nature of the gain-switched fiber lasers, benefits of this kind of lasers to 2-μm region and in-band-pumped (two-level system) laser systems are obvious. Advantages of in-band-pumped 2-μm lasers are discussed and analyzed with a simple numerical simulation in terms of Tm-doped fiber lasers. We also propose the key factors in the development of the gain-switched fiber lasers and predict the future tendency.

Background To identify specific exosomal microRNAs (miRNAs) as serum biomarkers for prediction of metastasis in patients with colorectal cancer (CRC). Materials and Methods Serum exosomes were isolated from patients with metastatic CRC (n = 34) and non‐metastatic CRC (n = 108) by ultracentrifugation and characterized using transmission electron microscopy, qNano, and Western blot. Differential exosomal miRNAs were screened by sequencing and validated by qPCR in metastatic and non‐metastatic CRC patients. Results After sequence analysis, KEGG analysis showed that differential genes were associated with Rap1 signaling pathway and pathways in cancer, 6 upregulated exosomal miRNAs (miR‐224‐5p, miR‐548d‐5p, miR‐200a‐3p, miR‐320d, miR‐200b‐3p, and miR‐1246), and 3 downregulated exosomal miRNAs (novel_246, novel_301, and miR‐27a‐5p) were screened with fold change >1.5, among which miR‐320d was selected as the best candidate involved in CRC metastasis. Validation analysis revealed exosomal miR‐320d could significantly distinguish metastatic from non‐metastatic CRC patients (P = .019), with AUC of 0.633 for the diagnosis of patients with metastatic CRC. Besides, the combination of miR‐320d and CEA had an area under curve (AUC) of 0.804 for the diagnosis of patients with metastatic CRC. Conclusion Serum exosomal miR‐320d is a promising non‐invasive diagnostic biomarker for distinguishing metastatic from non‐metastatic CRC.

We propose and demonstrate a tunable and switchable dual-wavelength ultra-fast Tm-doped fiber laser. The tunability is based on nonlinear polarization evolution (NPE) technique in a passively mode-locked laser cavity. The NPE effect induces wavelength-dependent loss in the cavity to effectively alleviate mode competition and enables the multiwavelength mode locking. The laser exhibits tunable dual-wavelength mode locking over a wide range from 1852 to 1886 nm. The system has compact structure and both the wavelength tuning and switching capabilities can be realized by controlling the polarization in the fiber ring cavity.

Extensive studies have been performed on random lasers in which multiple-scattering feedback is used to generate coherent emission. Q-switching and mode-locking are well-known routes for achieving high peak power output in conventional lasers. However, in random lasers, the ubiquitous random cavities that are formed by multiple scattering inhibit energy storage, making Q-switching impossible. In this paper, widespread Rayleigh scattering arising from the intrinsic micro-scale refractive-index irregularities of fiber cores is used to form random cavities along the fiber. The Q-factor of the cavity is rapidly increased by stimulated Brillouin scattering just after the spontaneous emission is enhanced by random cavity resonances, resulting in random Q-switched pulses with high brightness and high peak power. This report is the first observation of high-brightness random Q-switched laser emission and is expected to stimulate new areas of scientific research and applications, including encryption, remote three-dimensional random imaging and the simulation of stellar lasing.

Background: Circulating exosomal miRNAs are potential non-invasive biomarkers for colorectal cancer. The present study aimed to validate the novel sensitive and specific exosomal miRNA biomarkers for diagnosing colorectal cancer (CRC).Patients and Methods: Exosomes isolated from the serum of CRC patients and healthy donors by ultracentrifugation were characterized using TEM, qNano, and immunoblotting. The exosomes from 2 healthy donors and 4 CRC patients were subjected to RNA isolation and miRNA sequencing. The differently expressed miRNAs from 165 primary CRC patients and 153 healthy donors were substantiated by RT-qPCR.Results: The RNA-sequence data analysis revealed that 29 exosomal miRNAs (20 downregulated and 9 upregulated) with >1.5-fold difference between CRC patients and healthy donors were selected. The serum exosomal miR-99b-5p and miR-150-5p levels were significantly downregulated in CRC patients as compared to healthy donors (p < 0.0001 and p < 0.0001, respectively) and benign disease (p = 0.009 and p < 0.0001, respectively). The expression levels of exosomal miR-99b-5p and miR-150-5p were significantly decreased in early CRC patients as compared to healthy donors (p < 0.0001 and p < 0.0001, respectively). The expression levels of exosomal miR-99b-5p and miR-150-5p were significantly increased postoperatively (p = 0.0058 and p < 0.0001, respectively).Conclusions: The present study demonstrated that serum exosomal miRNAs are promising, sensitive, specific, and non-invasive diagnostic biomarkers for CRC.Impact: This is the first study to specifically identify exosomal miR-99b-5p and miR-150-5p associated with CRC. This study, therefore, might deepen the understanding of tumor-derived exosomes for CRC diagnosis.