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Abstract Passively harmonic mode-locking has been experimentally demonstrated in an erbium-doped fiber laser with large normal dispersion using single-multi-single mode structure as artificial saturable absorber. By increasing the pump power under the same polarization setting, the mode-locking operation can switch from fundamental mode-locked to 5th order harmonic mode-locked. Highest repetition rate of 4.26 MHz (5th order harmonic) is observed, with pulse width and pulse energy ascertained at 290 fs and 3.0 nJ, respectively. Excellent signal-to-noise ratio (SNR) of above 50 dB is observed for all harmonic orders. The findings validated that SMS structure can be used to generate stable and switchable high order of harmonic mode-locked. The low-cost SMS fiber for harmonic mode-locked generation technique could lay the groundwork for future sustainable industrial growth.

In this work, we proposed and experimentally demonstrated a combination of single mode fibre (SMF) with graded indexed multimode fibre (GIMF) to form an artificial saturable absorber. A SMF-GIMF-SMF structure is incorporated into Erbium-doped fibre laser (EDFL) system to induce mode-locking operation with very low threshold pump power of 41.6 mW. The highest pulse energy obtained is 406.65 pJ at pump power of 84.7 mW. With a relatively short GIMF used as artificial saturable absorber, high fundamental repetition rate with low threshold power is achieved. The proposed artificial saturable absorber is potentially to contribute to the development of sustainable industry, innovation, and infrastructure.

Abstract In this work, all‐optical polarisation state modulation using a tungsten disulfide (WS2) coated side‐polished fibre (SPF) as modulator is experimentally demonstrated. A bulk layer WS2 is exfoliated into a few‐layer WS2 thin film using liquid phase exfoliation technique. The few‐layer WS2 film is then coated onto a SPF to serve as an optical polarisation state modulator based on the thermo‐optic effect. The rotation of the polarised signal light is controlled using a pump laser. Throughout the pump power range of 514.5 mW, the polarisation state of the polarised signal light has rotated ∼70°, with a minor ellipticity fluctuation of

Bifacial photovoltaics is a type of solar photovoltaics technology that is fast growing in popularity owing to the several advantages it offers. In this study, the inclusion of fluorinated ethylene propylene polymer as one of the constituent materials in bifacial photovoltaic modules under various configurations and its effect on the module’s optical performance was investigated and compared with a commercial bifacial module. Monte Carlo ray tracing was used to conduct the study and the system was analyzed under both non tracking and uniaxial tracking conditions for varying surface albedo values corresponding to an ideal scattering surface, white concrete and sand. The analyses performed under normal incidence condition revelated that the net irradiance on the PV layers varied by as much as 96.0314 W m ^−2 between the best and worst performing bifacial configurations. Under uniaxial tracking, the top and rear surfaces of the PV modules could cumulatively be subjected to 21.799 kWh of solar irradiation flux per day over a generation window of eleven hours. The proposed changes could offer cost savings of USD 0.0118 per panel per day and up to an additional 5.802 kg of CO _2 equivalent offsets per panel per year.

Abstract In this work, polarization modulator utilizing MXene material, namely Nb2C is demonstrated. S band signal is injected into Nb2C thin film and is modulated by 1400 nm laser diode. A total of 39.81° of polarization rotation is attained when the pump power is increased to 223 mW. The rotation of light is due to thermo-optic effect. The efficiency of polarization modulator is calculated at 0.1974°/mW.

Abstract In this work, an all‐fibre phase shifter using tapered fibre coated with molybdenum tungsten disulfide ‐ reduced graphene oxide (MoWS2‐rGO) is demonstrated. The large evanescent field of tapered fibre allows MoWS2‐rGO to absorb injected light from a 1400‐nm pump. It subsequently modifies the refractive index of both an MoWS2‐rGO solution and tapered fibre because of the thermo‐optic effect. A maximum wavelength shift of 2.489 nm is observed and the equivalent phase shift is 0.91π. The efficiency of the phase shifter is calculated at 0.0175 nm/mW. The proposed phase shifter is beneficial for a variety of applications, specifically for future optical beam‐forming networks and all optical signal processing devices.

Microbottle resonators (MBR) are bottle-like structures fabricated by varying the radius of an optical fiber. MBRs can support whispering gallery modes (WGM) by the total internal reflection of the light coupled into the MBRs. MBRs have a significant advantage in sensing and other advanced optical applications due to their light confinement abilities in a relatively small mode volume and having high Q factors. This review starts with an introduction to MBRs’ optical properties, coupling methods, and sensing mechanisms. The sensing principle and sensing parameters of MBRs are discussed here as well. Then, practical MBRs fabrication methods and sensing applications are presented.

Dark pulse mode-locked Erbium doped fiber laser (EDFL) was demonstrated in this work by employing side polished fiber (SPF) coated with Ti _3 AlC _2 solution using drop casting method. The modulation depth of fabricated SPF coated with Ti _3 AlC _2 solution was characterized at 2.2%. This SPF coated structure allowed the formation of dark mode-locked pulse with improved the birefringence and nonlinearity in EDFL. The dark pulse generated was cubic-quintic nonlinear Schrödinger equation (CQNLSE) dark pulse with center wavelength at 1558.935 nm, repetition rate 1.839 MHz and pulse width 170.2 ns. Pulse stability was examined, revealing a high signal to noise ratio (SNR) of 65.86 dB. This work could serve as a foundation for the development of sustainable industry, innovation and infrastructure.

Fiber lasers have long remained relevant for various applications worldwide in many industries. This paper presents a mode-locked ytterbium-doped fiber laser (YDFL) using our home-made topological insulator Bi2Se3 nanosheets (TI Bi2Se3) as the saturable absorber. The fabricated TI Bi2Se3 is transported to the end of the fiber ferrule using an optical deposition process, which is a key ingredient for initiating a pulsed fiber laser. With a pump power of 211.1 mW, the captured repetition rate and pulse width are 8.3 MHz and 6.2 ns, respectively. The length of the setup configuration is approximately 20 m, which corresponds to an output power measurement of 12.4 mW with a calculated pulse energy of 1.5 nJ. There are no significant Kelly sidebands, but the strong stability of the pulsed laser is defined by a high signal-to-noise ratio (SNR) of around 60.35 dB.

In the advancement of photonics technologies, all-optical systems are highly demanded in ultrafast photonics, signal processing, optical sensing and optical communication systems. All-optical devices are the core elements to realize the next generation of photonics integration system and optical interconnection. Thus, the exploration of new optoelectronics materials that exhibit different optical properties is a highlighted research direction. The emerging two-dimensional (2D) materials such as graphene, black phosphorus (BP), transition metal dichalcogenides (TMDs) and MXene have proved great potential in the evolution of photonics technologies. The optical properties of 2D materials comprising the energy bandgap, third-order nonlinearity, nonlinear absorption and thermo-optics coefficient can be tailored for different optical applications. Over the past decade, the explorations of 2D materials in photonics applications have extended to all-optical modulators, all-optical switches, an all-optical wavelength converter, covering the visible, near-infrared and Terahertz wavelength range. Herein, we review different types of 2D materials, their fabrication processes and optical properties. In addition, we also summarize the recent advances of all-optical modulation based on 2D materials. Finally, we conclude on the perspectives on and challenges of the future development of the 2D material-based all-optical devices.

Background: The frontotemporal lobar degeneration-specific clinical dementia rating (FTLD-CDR), which was recently developed to measure frontotemporal dementia (FTD) severity, includes 2 items that assess language and behavior in addition to the 6 items of the conventional CDR. Methods: To investigate which of the 3 ratings, i.e. the global score of the CDR (GCDR), the behavioral domain score of the FTLD-CDR (BCDR), or the language domain score of the FTLD-CDR (LCDR), is most suitable for monitoring the progression of semantic dementia (SD), the number of hypometabolic voxels was calculated by comparing 28 SD patients in each stage of the 3 ratings with 63 age/sex-matched controls using voxel-based statistical parametric mapping. Results: The hypometabolic areas increased as a function of the LCDR score in SD patients. However, hypometabolic areas associated with the GCDR did not increase gradually as the stage increased. Furthermore, those associated with the BCDR showed the reverse pattern. Conclusion: Our findings suggest that the severity and patterning of glucose hypometabolism measured by the LCDR correspond well with the natural course of SD reported in previous clinical and neuroimaging studies, whereas the BCDR and GCDR did not reflect disease progression in SD. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

ZnO nanosponge was synthesized for the first time via a green method using Musa acuminata peel extract. The X-ray diffraction, Raman, energy dispersive X-ray and fourier-transform infrared analyses demonstrated that the synthesized sample was well crystallized and possessed hexagonal wurtzite pure ZnO. The field-emission scanning electron microscopy observation revealed that the ZnO nanosponge was assembled by aggregated spherical particles with sizes of 30-128 nm. Under simulated solar light irradiation, the ZnO nanosponge acted as an excellent photocatalyst for methylene blue and rhodamine B mixtures degradation compared to commercially available TiO2-P25. The enhanced photocatalytic activities of ZnO sample can be attributed to the high generation of hydroxyl radicals as a result of its unique sponge-like porous structure with large surface area. Furthermore, the ZnO nanosponge can be used effectively on the photodegradation of real textile dye wastewater. These characteristics showed that the biosynthesized ZnO nanosponge can be employed as a photocatalyst for environmental remediation.

An effective PFC constructed from ZnO/Zn photoanode and carbon cloth cathode has been proposed to oxidatively degrade organics and reductively treat Cu (II) in the semiconductor wastewater accompanied with electricity production. The cell electrical performance with open circuit voltage of 835 V, maximum power density of 0.003623 mW cm-2 and short circuit current density of 0.0506 mA cm-2 can be obtained using optimized catalyst loading of 1.0 g L-1 and semiconductor wastewater concentration of 10 mg L-1. Under the optimal test, more photogenerated electrons will be facilitated for charge carrier separation in the photoanode, accelerating the organics degradation on anode, and subsequently the electron migrating to cathode for Cu (II) reduction. A complete mineralization with 10 mg L-1 COD and more than 70% Cu (II) removal efficiency can be attained within 180 min. A good reproducibility test has been also witnessed because of the stable photoanode and cathode materials. This work may pave an effective and sustainable approach to concurrently eliminate two kinds of contaminants with energy recuperation in a single chamber.

Flower-like ZnO micro/nanostructures were synthesized via a simple reflux route without addition of surfactant. The characterization of as-synthesized ZnO sample was performed using X-ray diffraction, field-emission scanning electron microscopy and photoluminescence spectroscopy. The activity of the as-synthesized photocatalyst was evaluated using colony counting method under UV irradiation. The results showed that the as-synthesized ZnO sample exhibited excellent photocatalytic disinfection towards Escherichia coli. A possible disinfection mechanism was also postulated based on the findings from microscopic images and radical scavenging experiments.

The generation of nanosecond square pulse and microsecond harmonic pulse in a passively mode-locked fibre ring laser is demonstrated by inserting a 20 km long single mode fibre in the cavity. The laser operates in anomalous region based on the non-linear polarisation rotation process. The square pulse generation is because of the dissipative soliton resonance effect, which clamps the peak intensity of the laser and broadens the pulse width. The pulse width can be tuned from 28.2 to 167.7 ns. It was found that the square pulse can deliver higher pulse energy compared with the harmonic pulse. The highest recorded pulse energy is 249.8 nJ under the maximum available pump power of 125 mW without pulse breaking.

Melanomas exhibit the highest rate of heterogeneity among cancer cell types. In this study, we tested the two types of B16 melanoma cells (B16-S0-1 and B16-S1-1) showing resistance to antitumor immunity. These cells expressed Trp2 protein. Contrary to B16 and B16-S0-1 cells, B16-S1-1 cells failed to stimulate IFN-γ responses in Trp2-specific CD8+ T cells, suggesting that B16-S1-1 cells may have lost the ability to present antigen to Ag-specific CTLs in the context of MHC class I molecules. However, B16-S0-1 cells exhibited active Stat3 and decreased Bcl-2 expression, which were found to be not associated with immune escape. B16-S0-1 cells were more resistant to granzyme B-mediated caspase activation and apoptosis than B16 cells. Thus, these data show that B16 cells escape antitumor immune responses through the loss of epitope presentation to CTLs and the acquisition of tumor cell resistance to granzyme B-mediated caspase activation., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Anti-programmed death ligand 1 (PD-L1) therapy has been beneficial in treating patients with certain cancers. Here, we tested whether anti-PD-L1 therapy is effective for controlling different types of tumors using animal models of TC-1, MC38 and B16. We found that, despite PD-L1 expression, anti-PD-L1 therapy showed little and some antitumor activity in the TC-1 and MC38 models. However, anti-PD-L1 therapy exhibited a more dramatic antitumor effect in the B16 model. This difference in antitumor responses was likely associated with the CD8 + T cell infiltration status of tumor tissues. In the B16 model, CD8 + T cells and to a lesser degree NK cells were found to be responsible for the antitumor response of anti-PD-L1 therapy, as determined by immune cell subset depletion. In particular, CD8 + T cells from B16-bearing mice produced an IFN-γ in response to B16 cells and citrate phosphate buffer-treated B16 cell peptide elutes but not to an immunodominant class I epitope, Trp2 180-188 , suggesting that CD8 + T cells that recognize neoantigens were induced in B16 tumor-bearing mice and then reactivated by anti-PD-L1 for tumor control. When B16 tumor-bearing mice were treated with anti-PD-L1 in combination with Trp2 180-188 peptide vaccines, they displayed significantly more tumor control than either single therapy. Taken together, these studies show that B16 melanomas are more effectively controlled through reactivation of tumor-infiltrating lymphocytes by anti-PD-L1 therapy. Moreover, combined therapy using anti-PD-L1 and Trp2 peptide vaccines is more beneficial for controlling B16 melanomas through reactivation of neoantigen-specific CD8 + T cells and induction of Trp2-specific CD8 + T cells.

Legionella pneumophila , an intracellular bacterium, may cause life-threatening pneumonia in immunocompromised individuals. Mononuclear cells and antibodies have been reported to be associated with the host defense response against L. pneumophila. This study is to determine whether Legionella peptidoglycan-associated lipoprotein (PAL)-specific CD8 + T cells are directly associated with protection against L. pneumophila , with a focus on potential epitopes. Synthetic peptides derived from PAL of L. pneumophila were obtained and tested through in vitro and in vivo cytotoxic T lymphocyte (CTL) assays for immunogenicity. PAL DNA vaccines or a peptide epitope with or without CpG-oligodeoxynucleotides (ODN) was evaluated for protection against L. pneumophila infection in animal models. When mice were immunized with DNA vaccines expressing the PAL of L. pneumophila , they were significantly protected against a lethal challenge with L. pneumophila through induction of antigen-specific CD8 + CTLs. Of the 13 PAL peptides tested, PAL 92-100 (EYLKTHPGA) was the most immunogenic and induced the strongest CTL responses. When mice were immunized with the PAL 92-100 peptide plus CpG-ODN, they were protected against the lethal challenge, while control mice died within 3-6 days after the challenge. Consistent with lung tissue histological data, bacterial counts in the lungs of immunized mice were significantly lower than those in control mice. Also, the amino acid sequence of PAL 92-100 peptides is conserved among various Legionella species. To our knowledge, this study is the first to demonstrate that PAL 92-100 -specific CD8 + T cells play a central role in the host defense response against L. pneumophila ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Kim, Sin and Kim.)

Tumor cells tend to behave differently in response to immune selective conditions. Contrary to those in therapeutic antitumor conditions, tumor cells in prophylactic antitumor conditions lose antigen expression for antitumor immune escape. Here, using a CT26/HER2 tumor model, we investigate the underlying mechanism(s). We selected tumor cell variants (CT26/HER2-A1 and -A2) displaying resistance to antitumor protective immunity and loss of HER2 antigen expression. These immune-resistant cells failed to induce Ag-specific IgG and IFN-γ responses while forming tumors at the same rate as CT26/HER2 cells. RT-PCR, qRT-PCR, PCR, Western blot and DNA sequencing analyses demonstrated that HER2 expression was inhibited at the post-transcriptional level in these immune-resistant cells, suggesting that tumor cells may escape antitumor immunity through the post-transcriptional regulation of antigen gene expression. The proteasome and lysosomal protein degradation pathways were not responsible for antigen loss, as determined by an inhibitor assay. Finally, HER2 mRNA was found to be not present in the monosomes and polysomes of CT26/HER2-A2 cells, as opposed to CT26/HER2 cells, suggesting that the translation activity of HER2 mRNAs may be suppressed in these immune-resistant cells. Taken together, our results report a new mechanism by which tumor cells respond to antitumor protective immunity for antitumor immune evasion.

The role of chemotherapeutic agents in tumor immunotherapy is still controversial. In this study, we test using a TC-1 tumor model whether gemcitabine plus E7 peptide vaccine regimens (E7 peptides+CpG-ODN+anti-4-1BB Abs) may result in tumor cure in mice with large established tumors, with a focus on their effects on Ag-specific cytotoxic T lymphocyte (CTL) and myeloid-derived suppressor cell levels. Gemcitabine inhibited tumor growth by its direct cytotoxicity to tumor cells in vivo. E7 peptide vaccine regimens enhanced Ag-specific CTL lytic and antitumor therapeutic activity. Initial combination therapy using gemcitabine and E7 peptide vaccine regimens resulted in tumor regression with tumor relapse in animals with large established tumors, which appeared to result from the suppression of Ag-specific CTL activity by gemcitabine treatment. However, optimization of gemcitabine therapy by reducing its dose and frequency led to complete tumor regression without any recurring tumors in all tested mice even after discontinuation of therapy, possibly due to Ag-specific CTL responses. Thus, this study shows that the optimal dose and therapy frequency of gemcitabine are critical for achieving tumor cure in tumor-bearing animals undergoing E7 peptide vaccine regimen therapy, mainly by preventing CTL suppression. These findings may have implications for designing peptide-based therapeutic vaccines in cancer patients undergoing chemotherapy.