Q-switched ytterbium-doped fiber laser using graphene oxide as passive saturable absorber

A Q-switched ytterbium-doped fiber laser (YDFL) was demonstrated using Graphene Oxide (GO) as a saturable absorber (SA). Without SA, the ring cavity operates in a continuous wave laser at 1038 nm which is shifted to 1030 nm with the implementation of SA. The laser has a threshold pump power of 175 mW, a maximum repetition rate of 141 kHz and the shortest pulse width of 1.94?s. The highest pulse energy of 5.65 nJ is achieved at the pump power of 175mW. A stable Q-switched ytterbium doped fibre laser was successfully achieved in this experiment as the pulses measured SNR of 56.52 dB

Determination of Optimal Electrospinning Distance and Applied Voltage for Polyacrylonitrile Electrospun Fibre Production

Electrospinning process is highly dictated by electric field strength. Thus, two key parameters i.e., electrospinning distance and applied voltage, determine the quality of electrospun fibres. Incorrect selection of these parameters will result in poor fibre qualities. There ought to be an optimal combination of electrospinning distance and applied voltage to produce best quality fibres from a given material. In this study, the optimal combination of electrospinning distance and applied voltage was assessed based on consistency of electrospinning process, amount of fibre, fibre morphology, and average fibre diameter. Polyacrylonitrile (PAN) electrospun fibre samples were prepared at different combinations of electrospinning distance and applied voltage. Scanning electron microscopy and image analysis were conducted to assess the quality and average diameter of the fibres. The results indicate that for electrospinning of PAN, the distance should be between 10 and 20 cm with a 15 to 20 kV of applied voltages. Findings from this study is crucial for producing optimal fibre quality in PAN electrospun nanofibre synthesis

RNAi-mediated COPS3 gene silencing inhibits metastasis of osteogenic sarcoma cells

Metastatic disease is the primary cause of mortality among patients with osteogenic sarcoma (OGS). In this study, we aimed to identify the relationship of COPS3 gene expression to metastasis. Immunohistochemical staining for COPS3 was performed on 65 OGS samples (37 without and 28 with metastatic disease); 18.9% (7/37) of specimens from patients with no metastasis and 57.1% (16/28) of specimens from patients with metastasis showed intense staining of COPS3. Comparison of COPS3 expression between a poorly metastatic osteosarcoma cell line (SAOS-2) and highly metastatic osteosarcoma cell line (HOS) showed stronger expression of COPS3 in HOS cells. Inhibiting COPS3 function by siRNA resulted in reduced proliferation and migration of HOS cells. Inhibition of COPS3 gene downregulated expression of the MAPK signaling pathway, which has an important role in metastasis of OGS. Our results suggested that overexpression of the COPS3 gene might have important roles in metastasis of osteosarcoma cells

Microsecond pulse erbium-doped fiber laser using WS2 deposited on D-shaped fiber fabricated by polishing wheel technique

We demonstrate a stable Q-switching pulse train output centered at 1561 nm by implementing D-shaped fiber deposited tungsten disulphide (WS2) as a saturable absorber in erbium-doped fiber laser. D-shaped fiber was fabricated using a polishing wheel technique with two stages polishing. Proposed Q-switched EDFL generates a maximum repetition rate of 47.28 kHz at a pulse duration of 5.4 us. Under pump power of 104.6 mW, the laser consumed pulse energy of 99.4 nJ with an output power of 4.7 mW. This WS2-D-shaped SA is excellence for the production of Q-switched laser source

Microsecond pulse generation using bismuth salenide as saturable absorber in 1.5 um region

A Q-switched Erbium-doped fiber laser (EDFL) was demonstrated utilizing Bismuth Salenide as a saturable absorber. The saturable absorber (SA) is fabricated by mixing directly the Bismuth Salenide into polyvinyl alcohol (PVA) aqueous solution to form a thin film. The SA is integrated into EDFL cavity to achieve a stable Q-switched at center wavelength of 1559.8 nm. The peak power is a steady increasing pattern from 2.52 mW to 3.21 mW as the pump power is increased from 86.1 mW to 116.6 mW. The highest pulse energy obtained was 36.9 nJ at the pump power of 116.6 mW

Volatolomics analysis using FTIR spectroscopy for breast cancer identification in vitro

Volatolomic's analysis is the technique to analysis the volatile organic compounds (VOCs) from the metabolites. VOCs are released by cancerous cells can be one of the bio-diagnostics techniques to diagnose the cancer. FTIR spectroscopy with White gas cell absorption techniques can analyse and detect the key species from VOCs released. Small amount of VOCs samples can be detected by vacuuming the White gas cell and a low concentration gas also can be detected by employing a long effective optical path-length gas chamber. In this preliminary study, methanol was detected from the VOCs released by breast cancer cells

Q-switched dual-wavelength erbium-doped fiber laser using graphene as a saturable absorber

We proposed stable Q-switched dual-wavelength initiated by graphene as saturable absorber inside erbium-doped fiber laser cavity. Continuous-wave and pulse spectrum of erbium-doped fiber laser (EDFL) was successfully demonstrated and analysed where the lasing starts at a pump power of 50.4 mW. Threshold pump power generates continuous-wave at 1560 nm which is then shifted to 1558.7 nm as the SA is inserted. Q-switched EDFL generates a maximum repetition rate of 115.9 kHz which corresponds to a pulse width of 41 μs. The generation of dual-wavelength at two different wavelengths are also demonstrated in these works

High-frequency dielectric analysis of carbon nanofibers from pan precursor at different pyrolysis temperatures

Carbon nanofibers (CNF) produced from pyrolysis of electrospun polyacrylonitrile (PAN) precursor has received a great amount of attention due to their promising potentials. However, there are limited studies on the electrical properties of the CNF, especially at high-frequency range. In this study, CNF from PAN precursor were produced by electrospinning technique. Characterizations of the nanofibers were carried out in terms of physical, dielectric, and chemical properties. The stabilization of nanofibers took place at 240°C whilst carbonization process took place at temperatures of 800°C, 1000°C, and 1200°C, respectively. In terms of physical properties, the color of the nanofiber webs changed from white to brown and black, after stabilization and carbonization process accompanied by significant reduction in average fiber diameter. Dielectric analysis of the nanofibers was obtained by measuring the wave propagation characteristics at frequency range of 1 GHz to 10 GHz. Higher dielectric constants of the material were observed for fibers processed at higher carbonization temperatures. Good conductivity was also observed with loss tangent value that is higher than 1. The results were correlated with FTIR transmittance results, indicating greater amount of carbon are present in the nanofiber material. From the findings, the unique behavior of the nanofibers makes it practically potential for sensor applications. Explorations of future research in this area are to be sought

Determination of optimal electrospinning distance and applied voltage for polyacrylonitrile electrospun fibre production

Electrospinning process is highly dictated by electric field strength. Thus, two key parameters i.e., electrospinning distance and applied voltage, determine the quality of electrospun fibres. Incorrect selection of these parameters will result in poor fibre qualities. There ought to be an optimal combination of electrospinning distance and applied voltage to produce best quality fibres from a given material. In this study, the optimal combination of electrospinning distance and applied voltage was assessed based on consistency of electrospinning process, amount of fibre, fibre morphology, and average fibre diameter. Polyacrylonitrile (PAN) electrospun fibre samples were prepared at different combinations of electrospinning distance and applied voltage. Scanning electron microscopy and image analysis were conducted to assess the quality and average diameter of the fibres. The results indicate that for electrospinning of PAN, the distance should be between 10 and 20 cm with a 15 to 20 kV of applied voltages. Findings from this study is crucial for producing optimal fibre quality in PAN electrospun nanofibre synthesis