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High power all-fiberized and narrow-bandwidth MOPA system by tandem pumping strategy for thermally induced mode instability suppression

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High Power Laser Science and Engineering 2018年第4期6卷 53-59页

作者： Pengfei Ma Hu Xiao Daren Meng Wei Liu Rumao Tao Jinyong Leng Yanxing Ma Rongtao Su Pu Zhou Zejin Liu College of advanced Interdisciplinary studies National University of Defense Technology Hunan Provincial Collaborative Innovation Center of High Power Fiber Laser National University of Defense Technology

An all-fiberized and narrow-bandwidth master oscillator power amplification(MOPA) system with record output power of 4 kW level and slope efficiency of 78% is demonstrated. Tandem pumping strategy is tentatively introduced into the narrow-bandwidth MOPA system for thermally induced mode instability(TMI) suppression. The stimulated Brillouin scattering(SBS) effect is balanced by simply using one-stage phase modulation technique. With different phase modulation signals, SBS limited output powers of 336 W, 1.2 kW and 3.94 kW are respectively achieved with spectral bandwidths accounting for 90% power of ～0.025, 0.17 and ～0.89 nm. Compared with our previous 976 nm pumping system, TMI threshold is overall boosted to be >5 times in which tandem pumping increases the TMI threshold of >3times. The beam quality(M～2　factor) of the output laser is well within 1.5 below the TMI threshold while it is ultimately saturated to be 1.86 with the influence of TMI at maximal output power. Except for SBS and TMI, stimulated Raman scattering(srs) effect will be another challenge for further power scaling. In such a high power MOPA system, multidetrimental effects(SBS, srs and TMI) will coexist and may be mutual-coupled, which could provide a well platform for further comprehensively investigating and optimizing the high power, narrow-bandwidth fiber amplifiers.

关键词： advanced laser technology and applications design fiber laser and applications high power laser laser amplifiers laser systems modeling narrow linewidth optimization

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Air pollution and inhalation exposure to particulate matter of different sizes in rural households using improved stoves in central China

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Journal of Environmental Sciences 2018年第1期30卷 87-95页

作者： Weijian Liu Guofeng Shen Yuanchen Chen Huizhong Shen Ye Huang Tongchao Li Yilong Wang Xiaofang Fu Shu Tao Wenxin Liu Yibo Huang-Fu Weihao Zhang Chunyu Xue Guangqing Liu Fuyong Wu Minghung Wong MOE Key Laboratory of Earth Surface Processes College of Urban and Environmental SciencesPeking UniversityBeijing 100871China Beijing University of Chemical Technology Beijin9 100029China Croucher Institute of Environmental Sciences and Biology Department Hong Kong Baptist UniversityHong KongChina consortium on Health EnvironmentEducation and Research(CHEER)Department of Science and Environmental StudiesHong Kong Institute of EducationTai PoHong KongChina

Household air pollution is considered to be among the top environmental risks in *** examine the performance of improved stoves for reduction of indoor particulate matter（PM） emission and exposure in rural households, individual inhalation exposure to size-resolved PM was investigated using personal portable samplers carried by residents using wood gasifier stoves or improved coal stoves in a rural county in Central *** of PM with different sizes in stationary indoor and outdoor air were also monitored at paired sites. The stationary concentrations of size-resolved PM in indoor air were greater than those in outdoor air, especially finer particles PM0.25. The daily averaged exposure concentrations of PM0.25, PM1.0, PM2.5 and total suspended particle for all the surveyed residents were 74.4 ± 41.1, 159.3 ± 74.3, 176.7 ± 78.1 and 217.9 ± 78.1 μg/m3,respectively. Even using the improved stoves, the individual exposure to indoor PM far exceeded the air quality guideline by WHO at 25 μg/m3. Submicron particles PM1.0 were the dominant PM fraction for personal exposure and indoor and outdoor air. Personal exposure exhibited a closer correlation with indoor PM concentrations than that for outdoor concentrations. Both inhalation exposure and indoor air PM concentrations in the rural households with gasifier firewood stoves were evidently lower than the reported results using traditional firewood stoves. However, local governments in the studied rural areas should exercise caution when widely and hastily promoting gasifier firewood stoves in place of improved coal stoves, due to the higher PM levels in indoor and outdoor air and personal inhaled exposure.

关键词： Particulate matter Daily average exposure Size distribution Improved stoves Rural households in Central China

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Novel constant-cladding tapered-core ytterbium-doped fiber for high-power fiber laser oscillator

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High Power Laser Science and Engineering 2021年第2期9卷 142-148页

作者： Yun Ye Xianfeng Lin Xiaoming Xi Chen Shi Baolai Yang Hanwei Zhang Xiaolin Wang Jinyan Li Xiaojun Xu College of advanced Interdisciplinary studies National University of Defense TechnologyChangsha 410073China Wuhan National Laboratory for Optoelectronics(WNLO) Huazhong University of Science and TechnologyWuhan 430074China

Power scaling based on traditional ytterbium-doped fibers(YDFs)is limited by optical nonlinear effects and transverse mode instability(TMI)in high-power fiber ***,we propose a novel long tapered fiber with a constant cladding and tapered core(CCTC)along its axis *** tapered-core region of the fiber is designed to enhance the stimulated Raman scattering(srs)threshold and suppress higher-order mode resonance in the laser *** CCTC YDF was fabricated successfully with a modified chemical vapor deposition(MCVD)method combined with solution doping technology,which has a cladding diameter of 400µm and a varying core with a diameter of~24μm at both ends and~31μm in the *** test the performance of the CCTC fiber during high-power operation,an all-fiber laser oscillator based on a CCTC YDF was investigated *** a result,a maximum output power of 3.42 kW was achieved with an optical-to-optical efficiency of 55.2%,although the TMI effect was observed at an output power of~3.12 *** measured beam quality(M^(2)factor)was~1.7,and no sign of the Raman component was observed in the *** believe that CCTC YDF has great potential to simultaneously mitigate the srs and TMI effects,and further power scaling is promising by optimizing the structure of the YDF.

关键词： fiber design high power stimulated Raman scattering transverse mode instability ytterbium-doped fiber

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Effectiveness of Music-Based Therapeutic Intervention on People with Dementia: A Rapid Review

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Advances in Alzheimer's Disease 2024年第2期13卷 35-47页

作者： Shreejeet Shrestha Samikshya Karmacharya Yadav Prasad Joshi Prasa Shrestha Department of Public Health Asian College for Advance Studies Lalitpur Nepal Department of Operation Theatre Gosford Hospital New South Wales Health Gosford Australia Faculty of Science Health and Technology Nepal Open University Lalitpur Nepal Manmohan Memorial Institute of Health Sciences Kathmandu Nepal Department of General Practice and Emergency Medicine Chitwan Medical College Bharatpur Nepal

Background: Dementia is a condition with progressive cognitive dysfunction and manifestation of both behavioral and psychosocial symptoms. Non-pharmacological measures such as music therapy are gaining importance since efficacy and safety of people with dementia have been questionable for pharmacological measures. Patient’s response to music is persistent even in the later stage of dementia. Aim: This rapid review aims to identify, analyze, evaluate, and summarize the best available evidence on the effectiveness of music-based therapeutic interventions among people with dementia. Method: CINAHL Cochrane Library, internet websites of rapid review producers, and reference lists were searched to identify articles for inclusion. Two reviewers independently screened the literature search results. Effectiveness, music-based therapeutic intervention, dementia, Alzheimer’s disease, systematic review and systematic review with meta-analysis terms were used to abstract data from included studies. Main Findings: 11 srs and srs with meta-analysis were reviewed which revealed positive effect of music therapy on five major outcomes with 9 studies effect on behavioral outcome, 6 studies with positive effect on psychosocial outcome reducing anxiety, 6 with improved cognition, 1 study revealed with improved quality of life and 1 study revealed effect on physiological outcomes. Conclusion: Music therapy has positive effect on treatment of dementia but further studies with larger sample size and specified to single intervention should be conducted to provide generalisable and precise results on this topic.

关键词： Dementia Rapid Review Music Therapy Behavioral Cognitive Quality of Life

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Ecological and toxicological assessments of anthropogenic contaminants based on environmental metabolomics

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Environmental Science and Ecotechnology 2021年第1期5卷 49-62页

作者： Li-Juan Zhang Lu Qian Ling-Yun Ding Lei Wang Ming Hung Wong Hu-Chun Tao Key Laboratory for Heavy Metal Pollution Control and Reutilization School of Environment and EnergyPeking University Shenzhen Graduate SchoolShenzhenGuangdong518055China Laboratory for Earth Surface Processes College of Urban and Environmental SciencesPeking UniversityBeijing100871China consortium on Health EnvironmentEducation and Research(CHEER)Department of Science and Environmental StudiesThe Education University of Hong KongTai PoHong KongChina

There has long been a great concern with growing anthropogenic contaminants and their ecological and toxicological effects on living organisms and the surrounding environment for ***,a functional readout of cellular activity,can capture organismal responses to various contaminant-related stressors,acquiring direct signatures to illustrate the environmental behaviours of anthropogenic contaminants *** review entails the application of metabolomics to profile metabolic responses of environmental organisms,***(rodents,fish,crustacean and earthworms)and microorganisms(bacteria,yeast and microalgae)to different anthropogenic contaminants,including heavy metals,nanomaterials,pesticides,pharmaceutical and personal products,persistent organic pollutants,and assesses their ecotoxicological impacts with regard to literature published in the recent five ***-induced metabolism alteration and up/down-regulation of metabolic pathways are revealed in typical *** obtained insights of variations in global metabolism provide a distinct understanding of how anthropogenic contaminants exert influences on specific metabolic pathways on living *** with a novel ecotechnique of environmental metabolomics,risk assessments of anthropogenic contaminants are profoundly demonstrated.

关键词： Anthropogenic contaminants Environmental organisms Metabolomics

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Effective suppression of stimulated Raman scattering in half 10 kW tandem pumping fiber lasers using chirped and tilted fiber Bragg gratings

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Photonics Research 2019年第2期7卷 167-171页

作者： MENG WANG ZEFENG WANG LE LIU QIHAO HU HU XIAO XIAOJUN XU College of advanced Interdisciplinary studies National University of Defense Technology State Key Laboratory of Pulsed Power Laser Technology Hunan Provincial Key Laboratory of High Energy Laser Technology

The average power of fiber lasers has been scaled deeply into the kW regime in the past years. However, stimulated Raman scattering(srs) is still a major factor limiting further power scaling. Here, we have demonstrated for the first time, to the best of our knowledge, the suppression of srs in a half 10 kW tandem pumping fiber amplifier using chirped and tilted fiber Bragg gratings(CTFBGs). With specially self-designed and manufactured CTFBGs inserted between the seed laser and the amplifier stage, a maximum srs suppression ratio of >15 dB in spectrum is observed with no reduction in laser efficiency. With one CTFBG, the effective output power is improved to3.9 kW with a beam quality M2 factor of ～1.7 from 2; with two CTFBGs, the effective laser power reaches 4.2 kW with an increasing ratio of 20% and an M2 factor of ～1.8, and further power improvement is limited by the power and performance of the 1018 nm pump sources. This work provides an effective srs suppression method for high-power all-fiber lasers, which is useful for further power scaling of these systems.

关键词： Effective stimulated Raman 10 kW

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GaAs/AlGaAs heterostructure nanowires studied by cathodoluminescence

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Nano Research 2014年第4期7卷 473-490页

作者： Jessica Bolinsson Martin Ek Johanna Tragardh Kilian Mergenthaler Daniel Jacobsson Mats-Erik Pistol Lars Samuelson Anders Gustafsson Solid State Physics and the Nanometer Structure consortium Lund University Box 118 SE-221 00 Lund Sweden Polymer and Materials Chemistry Lund University Box 124 SE-221 00 Lund Sweden

In this report we explore the structural and optical properties of GaAs/A1GaAs heterostructure nanowires grown by metalorganic vapour phase epitaxy using gold seed-particles. The optical studies were done by low-temperature cathodo- luminescence （CL） in a scanning electron microscope （SEM）. We perform a systematic investigation of how the nanowire growth-temperature affects the total photon emission, and variations in the emission energy and intensity along the length of the nanowires. The morphology and crystal structures of the nanowires were investigated using SEM and transmission electron microscopy （TEM）. In order to correlate specific photon emission characteristics with variations in the nanowire crystal structure directly, TEM and spatially resolved CL measurements were performed on the same individual nanowires. We found that the main emission energy was located at around 1.48 eV, and that the emission intensity was greatly enhanced when increasing the GaAs nanowire core growth temperature. The data strongly suggests that this emission energy is related to rotational twins in the GaAs nanowire core. Our measurements also show that radial overgrowth by GaAs on the GaAs nanowire core can have a deteriorating effect on the optical quality of the nanowires. Finally, we conclude that an in situ pre-growth annealing step at a sufficiently high temperature significantly improves the optical quality of the nanowires.

关键词： GaAs/AlGaAs core shellnanowires metalorganic vapourphase epitaxy (MOVPE) cathodoluminescence twin defects transmission electronmicroscopy

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Arbuscular mycorrhizal fungi reduced the ratios of inorganic/organic arsenic in rice grains

Arbuscular mycorrhizal fungi reduced the ratios of inorganic...

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第八次全国土壤生物与生物化学学术研讨会暨第三次全国土壤健康学术研讨会

作者： Hui Li Xun Wen Chen Yu Bon Man Chuan Wu Ming Hung Wong School of Environment Jinan University consortium on Environment HealthEducation and Research(CHEER)and Department of Science and Environmental StudiesHong Kong Institute of Education

Rice is the staple food for three billion people,most of who reside predominantly in *** has been reported that rice grown in severely As contaminated areas can accumulate up to 0.48 mg kginorganic As in grains,which substantially exceeds the maximum contaminant level for arsenic in rice grains(0.15 mg kg inorganic As,GB2762-2005).The strategy of development for growing rice safely in the presence of As contamination may help to counteract the detrimental effects of *** this study,arbuscular mycorrhizal fungi(AMF)- Rhizophagus intraradices was inoculated to rice to investigate its effects on arsenic(As) uptake,grain As speciation,and rhizospheric As concentration of six rice cultivars grown in As-amended soil(60 mg As kg soil).The AMF inoculation induced either positive,neutral or negative responses in rice grown in As contaminated soil,suggesting that functional diversity may exist in AMF symbiosis when As is taken up and ***,both AMF and rice cultivars had significant effects(P < 0.05) on the following:grain yield;straw and root biomass;concentrations of As(Ⅲ),As(Ⅴ),DMA and total As,and the ratios of inorganic/organic As concentrations in rice grains;and As concentrations in the soil solution of rhizosphere on day 90 and 150;and of non-rhizosphere on day 90,120 and 150 in 60 mg As kg *** ratios of inorganic/organic As concentrations in rice grains of all cultivars were significantly reduced by AMF,that involved the transformation of inorganic As into less toxic organic form dimethylarsinic acid(DMA) in *** decreased significantly total As and inorganic As concentrations in rice grains of Handao *** correlations between As in the rhizospheric soil solution and As in rice grain at different periods were *** inferred that the As survey of soil solution can be an effective measure for evaluating As in grains.

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The p53/miR-34 axis in development and disease

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Journal of Molecular Cell Biology 2014年第3期8卷 214-230页

作者： Matjaz Rokavec Huihui Li Longchang Jiang and Heiko Hermeking Experimental and Molecular Pathology Institute of Pathology Ludwig-Maximilians-Universitat MLinchen 80337 Munich Germany German Cancer consortium (DKTK) 69120 Heidelberg Germany German Cancer Research Center (DKFZ) 69120 Heidelberg Germany

The tumor suppressor p53 is one of the most frequently mutated genes in human cancers. MicroRNAs （miRNAs） are small non-protein coding RNAs that regulate gene expression on the post-transcriptional level. Recently, it was shown that p53 regulates the expression of several miRNAs, thereby representing an important mechanism of p53 signaling. Several independent studies identified the members of the miR-34 family as the most prevalent p53-induced miRNAs, miR-34s are frequently silenced in variety of tumor entities, suggesting that they are important tumor suppressors. Indeed, ectopic expression of miR-34s inhibits proliferation, epithelial to mes- enchymat transition, migration, invasion, and metastasis of various cancer celt entities. Moreover, delivery or re-expression of miR-34 leads to notable repression of tumor growth and metastasis in cancer mouse models, and may therefore represent an efficient strategy for future cancer therapeutics. Besides their crucial functions in cancer, members of the miR-34 family also play important roles in spermatogenesis, stem cell differentiation, neuronal development, aging, and cardiovascular functions. Consequently, miR-34 has also been implicated in various non-cancerous diseases, such as brain disorders, osteoporosis, and cardiovascular complications.

关键词： p53 miR-34 miR-34a miR-34b/c cancer metastasis tumor suppression

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Perspective on the q-bio Summer School anc Conference： 2007- 2014 and beyond

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Frontiers of Electrical and Electronic Engineering in China 2014年第1期9卷 54-58页

作者： Orna Resnekov Brian Munsky William S. Hlavacek Molecular Sciences Institute Berkeley CA 94704 USA Department of Chemical and Biological Engineering Colorado State University Fort Collins CO 80523 USA New Mexico consortium Los Alamos NM87544 US-A Theoretical Division and Center for Nonlinear studies Los Alamos National Laboratory Los Alamos NM 87545 USA

INTRODUCTIONThe q-bio Conference and the associated q-bio Summer School were started in 2007 by a prescient group of researchers based at Los Alamos National Laboratory （LANL） and the University of New Mexico （J. Edwards, J. Faeder, W. Hlavacek, Y. Jiang, I. Nemenman and M. Wall） who envisioned a systems biology community focused on modeling,

关键词： Summer School Quantitative Biology Program Committee Member Synthetic Circuit Advisory Committee Member

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