Harmonically mode-locked Yb:CALGO laser pumped by a single-mode 1.2 W laser diode.

We present a SESAM mode locked Yb:CALGO laser with a harmonic repetition rate to the 300th order pumped by a single-mode fiber coupled laser diode. By fine tuning the internal angle between the laser beam and the normal axis through the gain medium, at pump power of 1.2 W, an average output power of 132 mW is achieved with a pulse duration of 777.6 fs and a repetition rate of 22.4 GHz. The amplification effect over several tens of roundtrips induced Fabry-Perot filtering of the anti-reflection (AR) coated gain medium is analyzed. The modulation depth increases and the FWHM of a passband Δυcrystal decreases with increasing roundtrip numbers in the laser crystal. The intra-cavity pulse shaping mechanism with a comb filter caused by the amplified etalon effect of the AR coated laser crystal leads to the overall mode spacing equal to the free spectral range of the gain medium other than the laser cavity and results in the high repetition rate running.

Generation of wavelength- and OAM-tunable vortex beam at low threshold.

Wavelength- and OAM- tunable laser with large tunable range is the key source for the application in large capacity optical communications. In this paper, we demonstrate a wavelength- and OAM-tunable vortex laser in a 1.2 W single mode fiber coupled LD pumped Yb:phosphate laser. A z-type cavity has been used to precisely control the laser mode diameter. A thin film polarizer (TFP) is inserted to finely control the intra-cavity loss and tune the wavelength. Corresponding laser fundamental mode to pump beam ratio has been optimized to decrease the pump threshold for high order HG mode running. A pair of cylindrical lenses has been used to convert the HG mode to vortex output. The vortex beam with OAM-tunable range from 1h to 14 h with wavelength tuning range of ~36.2 nm for LG0,1 vortex beam, and ~14.5 nm for LG0,14 vortex beam at pump power of only 1.2 W have been realized, which is the largest tuning range of both OAM and wavelength at ~1 W pump power range to the best of our knowledge.

Displacement and acoustic vibration sensor based on gold nanobipyramids doped PDMS micro-fiber.

We propose and demonstrate a novel flexible and elastic vibration-displacement fiber sensor with a doped polydimethylsiloxane (PDMS) micro-fiber based on model interference. High resolution three-dimensional displacement measurement is achieved through monitoring the output pattern and variation of power. The sensor with a length of about 200 µm reveals frequency range from 50 Hz to 14 kHz, covering all the human voice frequency, with greatly enhanced high signal to noise ratio (SNR) reaching up to 66 dB. This work suggests a simple structure, small size and low cost fiber-based convenient way to achieve a multifunctional sensing applications including human motion detection.

Direct generation of vortex beams from a double-end polarized pumped Yb:KYW laser.

Double-end polarized pumping scheme combined with off-axis pumping technique has been first introduced to generate vortex beams in a z-type cavity. By employing double-end pumping, two different transverse modes can be excited simultaneously. The phase delay between these two modes can be finely tuned by manipulating the cavity structure. Direct emission of a chirality controllable Laguerre Gaussian LG01 vortex beam with slope efficiency of more than 40% has been realized by a double-end polarized pumped Yb:KYW laser. Other modes, such as dual-LG01 mode, cross-shaped mode, and LG10 mode, have also been demonstrated from our laser setup.

Effects of Alpha-Synuclein on Primary Spinal Cord Neurons Associated with Apoptosis and CNTF Expression.

Spinal cord injury (SCI) often causes neurological deficits with poor recovery; the treatment, however, is far from satisfaction, and the mechanisms remain unclear. Using immunohistochemistry and western blotting analysis, we found α-synuclein (SNCA) was significantly up-regulated in the spinal caudal segment of rats subjected to spinal cord transection at 3 days post-operation. Moreover, the role of SNCA on neuronal growth and apoptosis in vitro was determined by using overexpressing and interfering SNCA recombined plasmid vectors, and the underlying mechanism was detected by QRT-PCR and western blotting. Spinal neurons transfected with SNCA-shRNA lentivirus gave rise to an optimal neuronal survival, while it results in cell apoptosis in SNCA-ORF group. In molecular level, SNCA silence induced the up-regulation of CNTF and down-regulation of Caspase7/9. Together, endogenous SNCA plays a crucial role in spinal neuronal survival, in which the underlying mechanism may be linked to the regulation both apoptotic genes (Caspase7/9) and CNTF. The present findings therefore provide novel insights into the role of SNCA in spinal cord and associated mechanism, which may provide novel cue for the treatment of SCI in future clinic trials.

Generation of double-scale pulses in a LD-pumped Yb:phosphate solid-state laser.

We have demonstrated a generation of double-scale in a laser diode (LD)-pumped Yb:phosphate solid-state laser. The double-scale pulse with a spectrum bandwidth of 4.6 nm is obtained at a central wavelength of 1030 nm with maximum output power of 377 mW and 80 MHz repetition rate. The autocorrelation function of the double-scale pulse contained a 510 fs short peak and 12.51 ps long pedestal. To our best knowledge, this is the first demonstration of a double-scale pulse mode-locked solid-state laser.

Knockdown of α-synuclein in cerebral cortex improves neural behavior associated with apoptotic inhibition and neurotrophin expression in spinal cord transected rats.

Spinal cord injury (SCI) often causes severe functional impairment with poor recovery. The treatment, however, is far from satisfaction, and the mechanisms remain unclear. By using proteomics and western blot, we found spinal cord transection (SCT) resulted in a significant down-regulation of α-synuclein (SNCA) in the motor cortex of SCT rats at 3 days post-operation. In order to detect the role of SNCA, we used SNCA-ORF/shRNA lentivirus to upregulate or knockdown SNCA expression. In vivo, SNCA-shRNA lentivirus injection into the cerebral cortex motor area not only inhibited SNCA expression, but also significantly enhanced neurons' survival, and attenuated neuronal apoptosis, as well as promoted motor and sensory function recovery in hind limbs. While, overexpression SNCA exhibited the opposite effects. In vitro, cortical neurons transfected with SNCA-shRNA lentivirus gave rise to an optimal neuronal survival and neurite outgrowth, while it was accompanied by reverse efficiency in SNCA-ORF group. In molecular level, SNCA silence induced the upregulation of Bcl-2 and the downregulation of Bax, and the expression of NGF, BDNF and NT3 was substantially upregulated in cortical neurons. Together, endogenous SNCA play a crucial role in motor and sensory function regulation, in which, the underlying mechanism may be linked to the regulation of apoptosis associated with apoptotic gene (Bax, Bcl2) and neurotrophic factors expression (NGF, BDNF and NT3). These finds provide novel insights to understand the role of SNCA in cerebral cortex after SCT, and it may be as a novel treatment target for SCI repair in future clinic trials.

Pump polarization insensitive and efficient laser-diode pumped Yb:KYW ultrafast oscillator.

We theoretically and experimentally report and evaluate a novel split laser-diode (LD) double-end pumped Yb:KYW ultrafast oscillator aimed at improving the performance of an ultrafast laser. Compared to a conventional unpolarized single-LD end-pumped ultrafast laser system, we improve the laser performance such as absorption efficiency, slope efficiency, cw mode-locking threshold, and output power by this new structure LD-pumped Yb:KYW ultrafast laser. Experiments were carried out with a 1 W output fiber-coupled LD. Experimental results show that the absorption increases from 38.7% to 48.4%, laser slope efficiency increases from 18.3% to 24.2%, cw mode-locking threshold decreases 12.7% from 630 to 550 mW in cw mode-locking threshold, and maximum output-power increases 28.5% from 158.4 to 221.5 mW when we switch the pump scheme from an unpolarized single-end pumping structure to a split LD double-end pumping structure.

[Study on the Mechanism of Laser Paint Removal Based on Emission Spectrum and Composition Analysis].

The mechanism of laser paint removal is studied based on emission spectrum and composition analysis by using laser induced breakdown spectroscopy and X-ray energy spectrum technology. The electron density and electron temperature of the plasma was calculated with the LIBS spectrums with different laser parameters. The morphologies of ablated paint surface were analyzed with a scanning electron microscopy while the changes of paint composition before and after ablation were measured with an X-ray spectrometer. The results show that, the plasma electron density, temperature and ablation area gradually increase with the increasing of incident laser energy. The carbon (C) content in paint decreases from 78.25% to 67.07% after the laser irradiation, indicating the occurrence of the ablation in the process of laser paint removal. By comparing the content of titanium (Ti) elements, C element and aluminum (Al), we found that the paint ablation will be more severe at higher laser energy. This paper is important to in-depth study of laser paint removal mechanism.

High-efficiency microchip laser with self-injection seeding.

In this paper, we use a small bandwidth 808 nm cw Ti:sapphire laser as a pump source to pump a picosecond microchip laser. Different focal length pump focus lenses have been tested to improve laser efficiency. A maximum slope efficiency of around 20% is obtained by a 30 mm focal length lens. The pump threshold is only 13 mW. In order to reduce the timing jitter, we explored the self-injection seeding method by adding a seeding cavity to the microchip laser. A reduction factor in the timing jitter of up to a factor of 23 relative to the unseeded laser is obtained. From the experiments, we also found that higher seeding pulse energy will help to reduce the jitter more.

[Characterization of Nd Doped Films Prepared by Femtosecond Pulsed Laser Deposition].

Thin films of Nd:YAG and Nd:Glass were prepared on Si(100) substrate by pulsed laser deposition technology. The morphology of film surface and cross section, composition, absorption spectrum and photoluminescence (PL) spectra of films were investigated by scanning electron microscope (SEM), energy disperse spectroscopy (EDS), Fourier transform infrared spectrometer (FTIR), optical parametric oscillator (OPO) and grating spectrometer. The results show that both Nd:YAG films and Nd:Glass films grown on the substrates at room temperature are amorphous. Nd:YAG films grown by PLD contain Nd element with 0.15 at. % stoichiometric proportion. The absorption spectrum of bulk Nd:YAG target rather than deposited films exhibit two absorption peaks at 750 and 808 nm. There are no evident peaks in the photoluminescence spectra curve of Nd:YAG films. However, the photoluminescence spectra of Nd:Glass films with two sharp peaks at the wavelength of 877 and 1064 nm are observed. It indicates that Nd is doped into glass host as optically active Nd(3+) ions when Nd:Glass films grow at room temperature. But for Nd:YAG films, Nd don't incorporate into YAG host as Nd(3+) ions.

Relationships Among Serological Indicators and In Vitro High-Throughput Drug Sensitivity Screening Results in Patients with Hepatocellular Carcinoma.

AIM: The purpose of this study was to analyze the relationship between serum indicators and high-throughput drug screening (HDS) results, aiming to achieve specific therapy for hepatocellular carcinoma (HCC). METHODS: This study recruited patients with HCC who underwent surgical resection at the Hepatobiliary Surgery Center of the First Affiliated Hospital of Chongqing Medical University from December 2019 to December 2021. HCC tissues were obtained from patients during surgery and subjected to in vitro cell culture, and then HDS testing was performed on the cultured tissue samples. We used Spearman's correlation analysis to examine the relationships between drug sensitivity results for anti-hepatocellular carcinoma drugs, other antitumor drugs, and serological indicators, the Neutrophil Lymphocyte Ratio (NLR), Platelet Lymphocyte Ratio (PLR), Systemic Immune Inflammatory Index (SII), Systemic Inflammatory Response Index (SIRI), Prognostic Nutritional Index (PNI), and Lymphocyte Monocyte Ratio (LMR). A significant correlation was considered when P<0.05 and |r|>0.40. Furthermore, linear regression analysis was conducted to elucidate the relationship between serological indicators and drug susceptibility, with significant results indicated by P<0.05 and R²≥0.50. RESULTS: In this study, 82 patients with HCC who had undergone hepatectomy and completed in vitro cell culture and HDS testing were evaluated. Using Spearman's correlation with a significance threshold of P<0.05 and |r|>0.40, we identified significant associations between serological indicators and specific drug regimens: NLR correlated with 5-Fluorouracil, 5- Fluorouracil+Calcium folinate (FOLFOX4), and Capecitabine + Cisplatin (XP); PLR with FOLFOX4; SII with XP, FOLFOX4, Doxorubicin + Oxaliplatin (ADM+L-OHP); and SIRI with XP and FOLFOX4. No correlations were found between PNI or LMR and any drug inhibition rates. A comprehensive evaluation using linear regression analysis-which included variables such as sex, age, hepatitis B virus and liver cirrhosis status, size and number of lesions, alphafetoprotein, total bilirubin, albumin, alanine aminotransferase, aspartate aminotransferase, and prothrombin time, alongside NLR, PLR, SII, and SIRI was conducted in relation to drug regimens. This analysis revealed that NLR, SII, and SIRI are significant predictors of FOLFOX4 inhibition rate, while NLR predicts the inhibition rate of XP effectively. However, no significant links were established between molecular targeted drugs, other antitumor drugs, and serological indicators. CONCLUSIONS: NLR, SII, and SIRI were correlated with FOLFOX4, and the higher the values of NLR, SII, and SIRI, the higher the in vitro inhibition of FOLFOX. Also, NLR was correlated with XP, and the higher the value of NLR, the higher the in vitro inhibition of XP.

Benefits of Hypothermic Oxygenated Perfusion Versus Static Cold Storage in Liver Transplant: A Comprehensive Systematic Review and Meta-analysis.

Background: The magnitude of potential benefits that hypothermic oxygenated perfusion (HOPE) may provide for liver transplantation (LT) patients compared to static cold storage (SCS) remains uncertain. In this systematic review and meta-analysis, we aimed to investigate the therapeutic effect that HOPE can offer LT recipients relative to SCS by synthesizing available evidence. Methods: A literature search was conducted in Embase, Medline, Web of Science, and the Cochrane database up to 1 June, 2023. The included studies were pooled for meta-analysis to synthesize their findings. Subgroup analysis was performed to investigate potential differences between HOPE and SCS for specific subgroups. Results: A total of 11 studies comprising 1765 patients were included. Compared with SCS, HOPE was associated with a significant reduction in the incidence of early allograft dysfunction (EAD) (OR: 0.36, 95% CI: 0.26-0.50), as well as a noteworthy decrease in graft loss rate within one year (OR: 0.57, 95% CI: 0.33-0.97) and a lower occurrence of Clavien-Dindo grade IIIa or higher complications (OR: 0.62, 95% CI: 0.43-0.89). Subgroup analysis revealed that HOPE significantly reduced the one-year mortality rate, any biliary complications incidence, and acute rejection of transplanted liver rate in patients who received organs from donation after cardiac death (DCD). Conclusions: HOPE has demonstrated efficacy in reducing the incidence of EAD after LT and shows some potential in diminishing postoperative complications such as biliary complications and acute rejection. This ultimately leads to improved patient prognosis, particularly among those receiving DCD grafts.

[The deposition of elements in the process of laser ablation of silicon].

Laser processing in the semiconductor industry (especially silicon material) has broad application prospects. The interaction between the laser and silicon is complex, and the present paper mainly studied the silicon morphology in UV laser ablation and the influence law of ambient gas. Studies have shown that the laser plasma ionization effect of silicon in the UV laser ablation has a decisive impact: the removal of the material becomes possible because of generating gasification and ionization, laser plasma shock wave can make phase transition material discharge effectively, and laser plasma spectroscopy ionization effect can make the oxygen elements in the air ionize and deposit effectively.

[The mechanism of laser induced damage to film by metal impurity particle].

The film can be easily damaged by impurity particles, and the damage characteristics of HfO2 film produced by metal particles and the corresponding thermodynamic process were studied. The strong absorption of laser light by metal particles can make film melt, gasified and ionized, and by this way, the film can be peeled and form tround pits point; The metal particle size is closely related to the processes of laser absorption, thermal diffusivity and thermal expansion closely related effects, etc. Under the same irritation energy, the temperature rise is determined by particle size, which can make different size of film damage pits. There is a certain size of metal particle which cause the highest temperature rise and make the film damage easily. Based on the analysis of irradiation ionization effects of laser plasma emission spectrum of the metal particles, the radiation spectrum is mainly focused on the ultraviolet part and photon energy is higher than the incident laser, which has stronger ionization effects, exacerbating the film removal.

Serum response factor promotes axon regeneration following spinal cord transection injury.

Studies have shown that serum response factor is beneficial for axonal regeneration of peripheral nerves. However, its role after central nervous system injury remains unclear. In this study, we established a rat model of T9-T10 spinal cord transection injury. We found that the expression of serum response factor in injured spinal cord gray matter neurons gradually increased with time, reached its peak on the 7th day, and then gradually decreased. To investigate the role of serum response factor, we used lentivirus vectors to overexpress and silence serum response factor in spinal cord tissue. We found that overexpression of serum response factor promoted motor function recovery in rats with spinal cord injury. Qualitative observation of biotinylated dextran amine anterograde tracing showed that overexpression of serum response factor increased nerve fibers in the injured spinal cord. Additionally, transmission electron microscopy showed that axon and myelin sheath morphology was restored. Silencing serum response factor had the opposite effects of overexpression. These findings suggest that serum response factor plays a role in the recovery of motor function after spinal cord injury. The underlying mechanism may be related to the regulation of axonal regeneration.

Comparison of different adjuvant therapy regimen efficacies in patients with high risk of recurrence after radical resection of hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) has a high recurrence rate even after radical surgery. Postoperative adjuvant transhepatic arterial chemoembolization (PA-TACE), postoperative adjuvant hepatic arterial infusion chemotherapy (PA-HAIC), postoperative adjuvant radiotherapy (PA-RT), and postoperative adjuvant molecular targeted therapy have been demonstrated to be effective in reducing the postoperative recurrence rate. The present network meta-analysis was conducted to compare the effects of PA-TACE, PA-HAIC, PA-RT and postoperative adjuvant molecular targeted therapy on the overall survival (OS) and disease-free survival (DFS) in HCC patients after radical resection and to determine the optimal treatment strategy. METHODS: Network meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Embase, Cochrane Library, and Web of Science were used to collect eligible studies up to December 25, 2022. Studies related to PA-TACE, PA-HAIC, and postoperative adjuvant molecular targeted therapy after radical HCC resection was included. The endpoints were OS and DFS, and the effect size was determined using hazard ratio with a 95% confidence interval. R software and "gemtc" package were employed to analyze the results. RESULTS: A total of 38 studies involving 7079 patients with HCC after radical resection were ultimately enrolled to be analyzed. Four postoperative adjuvant therapy measures and two oncology indicators were evaluated. In this study, OS-related investigations validated that PA-Sorafenib and PA-RT markedly enhanced the OS rates in patients after radical resection when compared to PA-TACE and PA-HAIC. However, statistical analysis revealed no significant difference between PA-Sorafenib and PA-RT, as well as PA-TACE and PA-HAIC. In the DFS-related investigations, PA-RT demonstrated superior efficacy over PA-Sorafenib, PA-TACE, and PA-HAIC. Additionally, PA-Sorafenib displayed better efficacy than PA-TACE. Nevertheless, there was no statistical significance between PA-Sorafenib and PA-HAIC, as well as PA-TACE and PA-HAIC. We also performed a subgroup analysis of studies focusing on HCC complicated by microvascular invasion after radical resection. In terms of OS, both PA-RT and PA-Sorafenib demonstrated a noteworthy improvement over PA-TACE, whereas no statistical significance was detected between PA-RT and PA-Sorafenib. Likewise, for DFS, both PA-Sorafenib and PA-RT exhibited superior efficacy compared to PA-TACE. CONCLUSION: In patients with HCC after radical resection and a high risk of recurrence, both PA-Sorafenib and PA-RT significantly improved OS and DFS when compared to PA-TACE and PA-HAIC. Notably, PA-RT exhibited superior efficacy over PA-Sorafenib, PA-TACE, and PA-HAIC in terms of DFS. Similarly, PA-Sorafenib appeared to be more effective than PA-TACE for DFS.

Evolution of time delay signature of chaos generated in a mutually delay-coupled semiconductor lasers system.

In this paper, evolution of time delay (TD) signature of chaos generated in a mutual delay-coupled semiconductor lasers (MDC-SLs) system is investigated experimentally and theoretically. Two statistical methods, including self-correlation function (SF) and permutation entropy (PE), are used to estimate the TD signature of chaotic time series. Through extracting the characteristic peak from the SF curve, a series of TD signature evolution maps are firstly obtained in the parameter space of coupled strength and frequency detuning. Meantime, the influences of injection current on the evolution maps of TD signature have been discussed, and the optimum scope of TD signature suppression is also specified. An overall qualitative agreement between our theoretical and experimental results is obtained.

[Double cladding ytterbium doped superfluorescence fiber source with 3 dB bandwidth reaching up to 80 nm].

The present paper reports a double pass forward superfluorescent fiber source (SFS), which uses a length of large mode area double cladding ytterbium doped fiber as gain medium. The maximum output power of this SFS is 341 mW. With the output power between 201 and 341 mW, the 3dB bandwidth of this SFS was more than 80 nm. This is the widest 3 dB bandwidth obtained from ytterbium doped SFS. The output power of the SFS linearly increased with the increment of the pump source injected current. It's output power is not very high, but under normal circumstances, it could meet the needs of the SFS. From the energy level structure of ytterbium ions and the absorption cross-section/emission cross section of ytterbium ions in quartz substrate, the physical mechanisms responsible for superfluorescence were analyzed. This double-cladding ytterbium-doped superfluorescent fiber laser benefits from the superfluorescence radiation near 1 025 and 1 075 nm, so the superfluorescence with 3 dB bandwidth reaching up to 80 nm could be obtained.

[Spatial localized distribution of modes in two-dimension random medium].

Based on the time dependent theory, FDTD algorithm was used to numerically solve Maxwell's equations and rate equations. By dividing the two-dimension random medium, the emission spectra of different region under different pumping intensities were obtained. The calculated results show that the emission spectra of different region are different, the energy of emission is mainly distributed in some certain region, and the pumping efficiency is different. Also spatial extent overlap of modes is reproduced. With this method, the dependence of random distribution on lasing can be analyzed and it should be useful for the preparation of pseudo-random medium.