No abstract

A pumping-power-dependent high-order harmonic mode-locking erbium-doped fiber laser (HML-EDFL) with a single-wall carbon nanotube (SWCNT)-doped polyvinyl alcohol (PVA)-based saturable absorber is investigated. The HML-EDFL systems using either all-physical-contact (PC) or all-angled-physical-contact (APC) connectors examined in this study show stably mode-locked pulse trains; however, the all-PC connector-based system requires a larger pumping power to initiate the mode-locking and generate a broader pulsewidth of 2.9-5.2 ps at same HML order. The all-APC connector-based HML-EDFL system can provide pulsewidth shortening from 3.8 to 1.9 ps associated with a spectral linewidth broadened from 0.7 to 1.36 nm by increasing the HML order from first to sixth. Either the all-PC or the all-APC connector-based EDFLs can deliver a nearly transformlimited pulse with a time-bandwidth product (TBP) of 0.32. The EDFL passively modelocked by SWCNT-doped PVA delivers a pulse train with a signal-to-noise ratio (SNR) remaining higher than 40 dB for different HML orders, whereas the side-mode suppression ratio (SMSR) lower than 32 dB inevitably introduces an unequalized peak amplitude phenomenon for adjacent pulses at higher HML operations. A modified Haus' master equation is derived to explain the inverse proportionality of the passive HML-EDFL pulsewidth to the square root of HML order, which is correlated with the shortened carrier recombination time of the SWCNT saturable absorber at higher pumping power or circulating pulse intensity.

The passive mode-locking of an erbium-doped fiber laser (EDFL) with a medium gain is demonstrated and compared by using three different types of carbon nanotubes (CNTs) doped in polyvinyl alcohol (PVA) films. Nano-scale clay is used to disperse the CNTs doped in the PVA polymer aqueous solution to serve as a fast saturable absorber to initiate passive mode-locking. The three types of CNT based saturable absorbers, namely single-walled (SW), double-walled (DW) and multi-walled (MW), are characterized by Raman scattering and optical absorption spectroscopy. The SW-CNTs with a diameter of 1.26 nm have two absorption peaks located around 1550 ± 70 and 860 ± 50 nm. In contrast, the DW-CNTs with a diameter of 1.33 nm reveal two absorption peaks located at 1580 ± 40 and 920 ± 50 nm. By using the SW-CNT based saturable absorber, the passively mode-locked EDFL exhibits a pulsewidth of 1.28 ps and a spectral linewidth of 1.99 nm. Due to the increased linear absorption of the DW-CNT based saturable absorber, the intra-cavity net gain of the EDFL is significantly attenuated to deliver an incompletely mode-locked pulsewidth of 6.8 ps and a spectral linewidth of 0.62 nm. No distinct pulse-train is produced by using the MW-CNT film as the saturable absorber, which is attributed to the significant insertion loss of the EDFL induced by the large linear absorption of the MW-CNT film.

Tumor-infiltrating lymphocytes are related to positive clinical prognoses in numerous cancer types. Programmed death ligand 1 (PD-L1), a mediator of the PD-1 receptor, plays an inhibitory role in cancer immune responses. PD-L1 upregulation can impede infiltrating T-cell functions in lung adenocarcinoma (LUAD), a lung cancer subtype. However, associations between the expression of PD-L1 and infiltration of B cells (a major immunoregulatory cell) remain unknown. Therefore, we investigated the role of infiltrating B cells in LUAD progression and its correlation with PD-L1 expression. The Cancer Genome Atlas (TCGA) LUAD data set was used to explore associations among B-cell infiltration, PD-L1 expression, clinical outcome, and gene landscape. Gene set enrichment analysis was used to explore putative signaling pathways and candidate genes. The drug enrichment analysis was used to identify candidate genes and the related drugs. We found that high B-cell infiltration was correlated with better prognoses; however, PD-L1 may interfere with the survival advantage in patients with high B-cell infiltration. The gene landscape was characterized comprehensively, with distinct PD-L1 levels in cell populations with high B-cell infiltration. We obtained five upregulated signaling pathways from the gene landscape: apoptosis, tumor necrosis factor (TNF)-α signaling via nuclear factor (NF)-κB, apical surface, interferon-α response, and KRAS signaling. Moreover, four candidate genes and their related target drugs were also identified, namely interleukin-2β receptor (IL2RB), IL-2γ receptor (IL2RG), Toll-like receptor 8 (TLR8), and TNF. These findings suggest that tumor-infiltrating B cells could act as a clinical factor in anti-PD-L1 immunotherapy for LUAD.

In a previous study, we evaluated the effect of baicalin on the expression of SP-A (surfactant protein A), which was developmentally regulated in an alveolar type II cell, H441. SP-A is encoded by two similar genes, SP-A1 and SP-A2, in humans. The maximal induction of SP-A1 gene of H441 occurred at treating 150 nM of baicalin for 48 h. In the present study, cDNA subtraction analysis is performed to examine the differential expression in H441 cell upon baicalin treatment with a view to investigating the regulatory mechanism. The mRNA of H441 cell incubated with 150 nM baicalin for 48 h was compared to that of blank control. Two PCR products were obtained through subtractive cDNA amplification. A product encoding cytochrome c oxidase was demonstrated to be a differential signal by RT-PCR analysis, and the other was a false positive. The induction of cytochrome c oxidase might increase ATP level in cell, and consequently elevates cAMP, which upregulates surfactant synthesis and secretion.