Pr3+-doped selenide-based chalcogenide glass mid-infrared fibre amplifier

Mid-infrared (MIR) fibre lasers beyond 4.0 μm with high brightness, high efficiency and good beam quality are in great demand in the fields of biomedical sensing, environmental monitoring and medical diagnostics. Since intense 3.5 - 6.5 μm MIR photoluminescence is shown in Pr3+-doped selenide chalcogenide glass fibre, it is believed that this fibre has potential to be employed as an active fibre for a MIR fibre laser or amplifier. As no laser threshold and fewer MIR optical components are required in an amplifier configuration, the Pr3+-doped selenide chalcogenide glass MIR fibre amplifier is explored in this Project. However, the challenges originating from the high fibre loss and complicated energy levels of Pr3+ ions, hinder the developing a MIR Pr3+-doped fibre amplifier. Hence, this Project is aiming to find an optimum optical design for a Pr3+-doped selenide chalcogenide glass fibre amplifier, which is able to achieve MIR signal amplification beyond 4.0 μm wavelength. The Pr3+-doped Ge-As-Se-Ga fibre was characterised in optical behaviour of the photoluminescence (PL) and PL lifetime (LT), using pump wavelengths at 1.55, 1.94 and 4.15 μm, respectively. PL results showed that different energy transitions are excited using the different pumping wavelengths. Both NIR (near-infrared) PL around 2.5 μm and MIR PL of 3.5 - 6.5μm were observed in Pr3+-doped Ge-As-Se-Ga fibre under each pumping at 1.55, 1.94 and 4.15 μm wavelength, respectively. Whereas, an energy transfer up-conversion at around 2.5 μm and the additional two NIR PL emissions at wavelengths of 1.05 and 1.41 μm, respectively, were found in the fibre using the 1.55 μm pumping. These latter are considered to be disadvantageous for a MIR fibre amplifier. It is suggested that the Pr3+-doped Ge-As-Se-Ga fibre amplifier is more appropriately pumped at 1.94 or 4.15 μm. In addition, the LTs of the 3H5 and (3F2, 3H6) levels of Pr3+ ions were evaluated to be 7.4 ± 0.03 ms and 1.9 ± 0.05 ms using a new method of 4.15 μm resonant pumping proposed in this Project. In particular, the LT of the (3F2, 3H6) level, for the first time, was successfully measured in the 4.15 μm resonantly pumped Pr3+-doped Ge-As-Se-Ga fibre. The 1.94 μm pumped cascaded Pr3+-doped MIR fibre amplifier was then numerically and experimentally investigated. The numerical investigation demonstrated that the pump power at 1.94 μm would be largely transferred to the NIR ASE power around 2.5 μm, rather than to the MIR signal amplification. A tiny signal amplification at 4.5 μm was predicted only in the case of the 1.94 μm co-pumped Pr3+-doped fibre amplifier with length of 0.8 m. Nevertheless, a 1.94 μm co-pumped Pr3+-doped Ge-As-Se-Ga fibre amplifier with 4.15 μm signal laser was experimentally designed, but no signal amplifier at 4.15 μm was observed in the fibre amplifier. These results reveal that a 1.94 μm pumped Pr3+-doped fibre amplifier is impractical for the MIR signal amplification beyond 4.0 μm. To explore further the Pr3+-doped selenide chalcogenide glass MIR fibre amplifier, a 4.15 μm resonantly pumped Pr3+-doped fibre amplifier was studied, which is beneficial from a lowered quantum defect performed in the resonant pumping. The simulation model with the pump excited-state absorption (ESA) and full spectral amplified spontaneous emission (ASE) of 2.0 - 6.0 μm was proposed for this fibre amplifier. The modelling results showed that a 4.15 μm counter-pumping fibre amplifier could achieve a power conversion efficiency (PCE) of over 62.8 % for signal wavelengths ranging from 4.5 to 5.3 μm. This is, to our best knowledge, the highest simulated PCE for a Pr3+-doped chalcogenide glass fibre amplifier yet reported. Furthermore, a maximum gain of 4.6 dB at a signal wavelength of 5.28 μm was experimentally demonstrated in a 4.15 resonantly pumped Pr3+-doped Ge-As-Se-Ga fibre amplifier with a broadband signal OPO (optical parametric oscillator) laser centred on 5.5 μm, as well as a new signal ESA at signal wavelengths around 5.5 μm. However, the signal ESA spoiled any further signal amplification particularly at wavelengths of 5.37, 5.51 and 5.57 μm, which should be suppressed in a resonantly pumped Pr3+-doped fibre amplifier. This work, to our best knowledge, is the first experimental demonstration of gain at MIR wavelengths in a Pr3+-doped chalcogenide glass fibre. Overall, during this Project, significant progress has been made on Pr3+-doped selenide chalcogenide glass MIR fibre amplifiers, and encouragingly a MIR signal amplification beyond 4.0 μm has been initially realised using a 4.15 μm resonantly pumped Pr3+-doped Ge-As-Se-Ga fibre amplifier

Antimicrobial Activity of Quinazolin Derivatives of 1,2-Di(quinazolin-4-yl)diselane against Mycobacteria

Mycobacterium tuberculosis (M. tuberculosis) is one of the leading causes of morbidity and mortality. Currently, the emergence of drug resistance has an urgent need for new drugs. In previous study, we found that 1,2-di(quinazolin-4-yl)diselane (DQYD), a quinazoline derivative, has anticancer activities against many cancers. However, whether DQYD has the activity of antimycobacterium is still little known. Here our results show that DQYD has a similar value of the minimum inhibitory concentration with clinical drugs against mycobacteria and also has the ability of bacteriostatic activity with dose-dependent and time-dependent manner. Furthermore, the activities of DQYD against M. tuberculosis are associated with intracellular ATP homeostasis. Meanwhile, mycobacterium DNA damage level was increased after DQYD treatment. But there was no correlation between survival of mycobacteria in the presence of DQYD and intercellular reactive oxygen species. This study enlightens the possible benefits of quinazoline derivatives as potential antimycobacterium compounds and furtherly suggests a new strategy to develop new methods for searching antituberculosis drugs

Ultrasmall Glutathione-Protected Gold Nanoclusters as Next Generation Radiotherapy Sensitizers with High Tumor Uptake and High Renal Clearance

Radiotherapy is often the most straightforward first line cancer treatment for solid tumors. While it is highly effective against tumors, there is also collateral damage to healthy proximal tissues especially with high doses. The use of radiosensitizers is an effective way to boost the killing efficacy of radiotherapy against the tumor while drastically limiting the received dose and reducing the possible damage to normal tissues. Here, we report the design and application of a good radiosensitizer by using ultrasmall gold nanoclusters with a naturally occurring peptide (e.g., glutathione or GSH) as the protecting shell. The GSH coated gold nanoclusters can escape the RES absorption, leading to a good tumor uptake (8.1% ID/g at 24 h post injection). As a result, the as-designed Au nanoclusters led to a strong enhancement for radiotherapy, as well as a negligible damage to normal tissues. After the treatment, the ultrasmall gold nanoclusters can be efficiently cleared by the kidney, thereby avoiding potential long term side effects caused by the accumulation of gold atoms in the body. Our data suggest that the ultrasmall peptide protected Au nanoclusters are a promising radiosensitizer for cancer radiotherapy.Comment: 15 Pages, 6 Figures, Scientific Reports 5, 201

Utilizing metagenomic next-generation sequencing for diagnosis and lung microbiome probing of pediatric pneumonia through bronchoalveolar lavage fluid in pediatric intensive care unit: results from a large real-world cohort

BackgroundMetagenomic next-generation sequencing (mNGS) is a powerful method for pathogen detection in various infections. In this study, we assessed the value of mNGS in the pathogen diagnosis and microbiome analysis of pneumonia in pediatric intensive care units (PICU) using bronchoalveolar lavage fluid (BALF) samples.MethodsA total of 104 pediatric patients with pneumonia who were admitted into PICU between June 2018 and February 2020 were retrospectively enrolled. Among them, 101 subjects who had intact clinical information were subject to parallel comparison of mNGS and conventional microbiological tests (CMTs) for pathogen detection. The performance was also evaluated and compared between BALF-mNGS and BALF-culture methods. Moreover, the diversity and structure of all 104 patients’ lung BALF microbiomes were explored using the mNGS data.ResultsCombining the findings of mNGS and CMTs, 94.06% (95/101) pneumonia cases showed evidence of causative pathogenic infections, including 79.21% (80/101) mixed and 14.85% (15/101) single infections. Regarding the pathogenesis of pneumonia in the PICU, the fungal detection rates were significantly higher in patients with immunodeficiency (55.56% vs. 25.30%, P =0.025) and comorbidities (40.30% vs. 11.76%, P=0.007). There were no significant differences in the α-diversity either between patients with CAP and HAP or between patients with and without immunodeficiency. Regarding the diagnostic performance, the detection rate of DNA-based BALF-mNGS was slightly higher than that of the BALF-culture although statistically insignificant (81.82% vs.77.92%, P=0.677) and was comparable to CMTs (81.82% vs. 89.61%, P=0.211). The overall sensitivity of DNA-based mNGS was 85.14% (95% confidence interval [CI]: 74.96%-92.34%). The detection rate of RNA-based BALF-mNGS was the same with CMTs (80.00% vs 80.00%, P>0.999) and higher than BALF-culture (80.00% vs 52.00%, P=0.045), with a sensitivity of 90.91% (95%CI: 70.84%-98.88%).ConclusionsmNGS is valuable in the etiological diagnosis of pneumonia, especially in fungal infections, and can reveal pulmonary microecological characteristics. For pneumonia patients in PICU, the mNGS should be implemented early and complementary to CMTs

Experimental observation of gain in a resonantly pumped Pr3+-doped chalcogenide glass mid-infrared fibre amplifier notwithstanding the signal excited-state absorption

We demonstrate a maximum gain of 4.6 dB at a signal wavelength of 5.28 μm in a 4.1 μm resonantly pumped Pr3+- doped selenide-based chalcogenide glass fibre amplifier of length 109 mm, as well as a new signal excited-stated absorption (ESA) at signal wavelengths around 5.5 μm. This work is to the best of our knowledge is the first experimental demonstration of gain at mid-infrared (MIR) wavelengths in a Pr3+-doped chalcogenide fibre amplifier. The signal ESA of Pr3+ ions is attributed to the transition 3H6→(3F4, 3F3) after the pump ESA (3H5→3H6) at a pump wavelength of 4.1 μm, which absorbs the MIR signal at wavelengths of 5.37, 5.51 and 5.57 μm, and so spoils the amplifier’s performance at these wavelengths. Thus, this signal ESA should be suppressed in a resonantly pumped Pr3+-doped chalcogenide fibre amplifier

A study of HIV/AIDS related knowledge, attitude and behaviors among female sex workers in Shanghai China

<p>Abstract</p> <p>Background</p> <p>China is currently facing a rapid and widespread increase in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). The activities of female sex workers (FSWs) have contributed to the mounting epidemic of HIV/AIDS and other sexually transmitted diseases (STDs). Therefore, this study aimed to assess the HIV/AIDS-related knowledge, attitude and risk behaviors among FSWs operating in Shanghai China.</p> <p>Methods</p> <p>A cross-sectional study was conducted in five districts of Shanghai, including three suburbs and two downtown locales. We adopted a cluster randomized sampling method to obtain ten geographic sites which consisted of one or more communities/villages proximal to a location where FSWs were accessible. A total of 324 FSWs from 109 Xitou Fang, massage parlors and hair salons who explicitly provided sexual services were enrolled in the study. Each participant completed a questionnaire survey and interview aimed to collect information on the individual's knowledge, attitude, and behaviors associated with risk for HIV/AIDs.</p> <p>Results</p> <p>The overall correct answer rate of HIV/AIDS-related knowledge was 60.8%, and the knowledge of FSWs from downtown areas was significantly higher than those from suburban areas (<it>P </it>< 0.05). The percentage of FSWs who reported having experiences in commercial sexual services without the use of condoms was 33.6%. Condom slippage or breakage was reported as having occurred at least once by 51.2% of the FSWs. FSWs from suburban areas were found to more often engage in high-risk behaviors, including oral and anal sex, than those from downtown areas (<it>P </it>< 0.001). Many of the FSWs (65.7%) reported having non-client sexual partners (most were identified as boyfriends or husbands); however, condom usage with these partners were lower (34.3%).</p> <p>Conclusions</p> <p>Based on the findings from our survey, we advise that promotion of HIV/AIDS-related knowledge be targeted towards FSWs in Shanghai, especially those operating in the suburbs. HIV prevention efforts, such as urging constant condom usage with both clients and steady partners, should be sustained and reinforced among the female sex workers population.</p

Long-term exposure to air pollution and lung function among children in China: Association and effect modification

BackgroundChildren are vulnerable to the respiratory effects of air pollution, and their lung function has been associated with long-term exposure to low air pollution level in developed countries. However, the impact of contemporary air pollution level in developing countries as a result of recent efforts to improve air quality on children's lung function is less understood.MethodsWe obtained a cross-sectional sample of 617 schoolchildren living in three differently polluted areas in Anhui province, China. 2-year average concentrations of air pollutants at the year of spirometry and the previous year (2017–2018) obtained from district-level air monitoring stations were used to characterize long-term exposure. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and forced expiratory flow between 25 and 75% of FVC (FEF25−75) were determined under strict quality control. Multivariable regression was employed to evaluate the associations between air pollution level and lung function parameters, overall and by demographic characteristics, lifestyle, and vitamin D that was determined by liquid chromatography tandem mass spectrometry.ResultsMean concentration of fine particulate matter was 44.7 μg/m3, which is slightly above the interim target 1 standard of the World Health Organization. After adjusting for confounders, FVC, FEV1, and FEF25−75 showed inverse trends with increasing air pollution levels, with children in high exposure group exhibiting 87.9 [95% confidence interval (CI): 9.5, 166.4] mL decrement in FEV1 and 195.3 (95% CI: 30.5, 360.1) mL/s decrement in FEF25−75 compared with those in low exposure group. Additionally, the above negative associations were more pronounced among those who were younger, girls, not exposed to secondhand smoke, non-overweight, physically inactive, or vitamin D deficient.ConclusionsOur study suggests that long-term exposure to relatively high air pollution was associated with impaired lung function in children. More stringent pollution control measures and intervention strategies accounting for effect modification are needed for vulnerable populations in China and other developing countries