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3 kW passive-gain-enabled metalized Raman fiber amplifier based on passive gain

Raman fiber lasers (RFLs) are currently promising and versatile light sources for a variety of applications. So far, operations of high power and brightness-enhanced RFLs have absorbed enormous interests along with rapid progress. Nevertheless, the stable Raman lasing at high power levels remains challenged by the thermal effects. In an effort to realize more effective thermal management in high power RFLs, here we demonstrate, for the first time, an all-fiberized RFA employing metal-coated passive fiber enabling high power lasing. By employing aluminum to the cladding of graded-index (GRIN) passive fiber, the thermal abstraction of the laser devices is more sufficient to support low-temperature operation. The maximum output power reaches 3.083 kW at 1130 nm with a conversion efficiency of 78.7%. To the best of our knowledge, this is the first Raman laser generation based on metal-coated passive fiber. Meanwhile, it is also the highest power attained in the fields of all kinds of Raman lasers based on merely nonlinear gain

Pure passive fiber enabled highly efficient Raman fiber amplifier with record kilowatt power

Kilowatt-level high efficiency all-fiberized Raman fiber amplifier based on pure passive fiber is proposed for the first time in this paper. The laser system is established on master oscillator power amplification configuration while a piece of graded-index passive fiber is utilized as stokes shifting as well as gain medium, which is entirely irrelevant to rare-earth-doped gain mechanism. When the pump power is 1368.8 W, we obtained 1002.3 W continuous-wave laser power at 1060 nm with the corresponding optical-to-optical efficiency of 84%. The beam parameter M2 improves from 9.17 of the pump laser to 5.11 of the signal laser through the amplification process, and the brightness enhancement is about 2.57 at maximum output power as a consequence of the beam clean-up process in the graded-index fiber. To the best of our knowledge, we have demonstrated the first kilowatt-level high efficiency Raman fiber amplifier based on pure passive fiber with brightness enhancement

Hygroscopic Properties of 11 Pollen Species in China

Pollen, one of the most abundant types of primary biological aerosol particles, has significant impacts on human health, climate, and ecosystems. However, the hygroscopicity of pollen species in China remains to be unknown. In this work, we explored for the first time hygroscopic properties of pollen species widely found in China. Six anemophilous and five entomophilous pollen species (11 in total) were studied, and measurements were conducted as a function of relative humidity (RH, up to 95%) at two temperatures (25 and 37 °C). All 11 pollen species examined were found to show moderate hygroscopicity; the sample mass at 90% RH, normalized to that under dry conditions, was found to range from 1.33 to 1.43 at 25 °C, and the single hygroscopicity parameter (κ) was derived to be 0.036–0.048. No significant difference in hygroscopicity between anemophilous and entomophilous pollen species was observed, and the effect of the temperature (25 versus 37 °C) on pollen hygroscopicity was found to be small

Table_1_Effect of Nebulized Amphotericin B in Critically ill Patients With Respiratory Candida spp. De-colonization: A Retrospective Analysis.DOCX

The potential relationship among airway Candida spp. de-colonization, nebulized amphotericin B (NAB), and occurrence of ventilator-associated pneumonia (VAP) in patients who are critically ill has not been fully investigated, especially concerning effects on survival. In this observational, retrospective, cohort study in a 22-bed central intensive care unit, we included patients aged >18 years who required mechanical ventilation (MV) for >48 h, with at least two consecutive positive Candida spp. test results. Patients were categorized into NAB and no NAB (control) groups. Propensity matching at 1:1 was performed according to strict standards, and multiple Cox proportional hazard model and multivariate analyses were performed to evaluate the effects of NAB treatment. Throughout an 8-year study period, 526 patients had received MV and had positive respiratory tract Candida spp. cultures. Of these, we included 275 patients and excluded 251 patients. In total, we successfully matched 110 patients from the two groups (each group, n = 55; total population median age, 64 years; Acute Physiology and Chronic Health Evaluation II [APACHE II] score, 25.5; sequential organ failure assessment score, 9). The Candida spp. de-colonization rate was 69.1% in patients treated with NAB. VAP incidence did not differ significantly between the NAB (10.91%) and control (16.36%) groups (P = 0.405). Pseudomonas aeruginosa-related VAP rates differed significantly between the NAB (10.91%) and control (25.45%) groups (P = 0.048). Five (9.1%) patients in the NAB group died during hospitalization compared with 17 (30.9%) controls (P = 0.014). At 28 days, 9 (16.4%) and 16 (29.1%) deaths occurred in the NAB and control groups, respectively, (P = 0.088). The cumulative 90-day mortality rate differed significantly between the two groups (23.6 vs. 43.6%, P = 0.015). Multivariate logistic regression analyses indicated a decreased 90-day mortality in the NAB group (adjusted odds ratio 0.413; 95% confidence interval 0.210–0.812; P = 0.01). In subgroup analyses, the NAB-associated decreased risk of death at 90 days was consistent across subgroups of patients with a Candida score of 2, younger age (2 days. NAB may be an alternative treatment option for critically ill patients with VAP.</p