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Photonic properties of novel Yb3＋ doped germanium-lead oxyfluoride glass-ceramics for laser cooling applications

Frontiers of Optoelectronics 2018年第2期11卷 189-198页

作者： Lauro J. Q. MAIA Jyothis THOMAS Yannick LEDEMI Kummara V. KRISHNAIAH Denis SELETSKIY Younes MESSADDEQ raman kashyap Instituto de Fisica Universidade Federal de Goias Av. Esperanga 1533 Campus Samambaia Goiania GO 74690-900 Brazil Department of Electrical Engineering Ecole Polytechnique de Montrral P.O. Box 6079 Station Centre-ville Montreal QC H3C 3A7 Canada Department of Engineering Physics Ecole Polytechnique de Montrral P.O. Box 6079 Station Centre-ville Montreal QC H3C 3A7 Canada Centre d'Optique Photonique et Laser 2375 Rue de la Terrasse Universite Laval Qurbec QC G1V 0A6 Canada

Abstract In recent years, our research group has developed and studied new rare-earth doped materials for the promising technology of solid-state laser cooling, which is based on anti-stokes fluorescence. To the best of our knowledge, our group is the only one in Canada leading the research into the properties of nanoparticles, glasses and glass-ceramics for optical refrigeration appli- cations. In the present work, optical properties of 50GeO2- 30PbF2-18PbO-2YbF3 glass-ceramics for laser cooling are presented and discussed as a function of crystallization temperature. Spectroscopic results show that samples have near infrared photoluminescence emission due to the 2F5/2 - 2F7/2 Yb3＋ transition, centered at -1016 nm with an excitation wavelength of 920 nm or 1011 nm, and the highest photoluminescence emission efficiency occurs for heat-treatment for 5 h at 350℃. The internal photolumi- nescence quantum yield varies between 99% and 80%, depending on the temperature of heat-treatment, being the most efficient under 1011 nm excitation. The 2F5/2 lifetime increases from 1.472 to 1.970 ms for heat treatments at 330℃ to 350℃, respectively, due to energy trapping and the low phonon energy of the nanocrystals. The sample temperature dependence was measured with a fiber Bragg grating sensor, as a function of input pump laser wavelength and processing temperature. These measure- ments show that the heating process approaches near zero for an excitation wavelength between 1020 and 1030 nm, which is an indication that phonons are removed effectivelly from the glass-ceramic materials, and they can be used for optical laser cooling applications. On theother hand, the temperature increase as a function of input laser power into samples remains constant between 920 and 980 nm wavelength excitation, a temperature variation of 36 K/W （temperature of 58℃/W） was attained under excitation at 950 nm, showing a possible use for biomedical applications to be explored.

关键词： optical refrigeration oxyfluoride glass-cera-mics Yb3+ doping quantum yield infrared emission lifetime

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Critical care practice in India:Results of the intensive care unit need assessment survey(ININ2018)

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World Journal of Critical Care Medicine 2020年第2期9卷 31-42页

作者： Rahul kashyap Kirtivardhan Vashistha Chetan Saini Taru Dutt Dileep raman Vikas Bansal Harpreet Singh Geeta Bhandari Nagarajan Ramakrishnan Harshit Seth Divya Sharma Premkumar Seshadri Mradul Kumar Daga Mohan Gurjar Yash Javeri Salim Surani Joseph Varon 无 Department of Anesthesiology and Perioperative Medicine Mayo ClinicRochesterMN 55905United States Department of Infectious Disease Mayo ClinicRochesterMN 55905United States Department of Internal Medicine Allegheny General HospitalPittsburghPA 15212United States Department of Radiology Mayo ClinicRochesterMN 55905United States Department of Medicine Jacobi Medical Center/Albert Einstein College of MedicineBronxNY 14061United States Department of Neurology Mayo ClinicRochesterMN 55905United States and Department of PsychiatryHennepin County Medical CenterMinneapolisMN 55415United States Department of Medicine Cloud Physician HealthcareBangalore 560038India Department of Critical Care Medicine Mayo ClinicRochesterMN 55905United States Department of Internal Medicine Maulana Azad Medical College&Associated HospitalsNew DelhiDelhi 110002India Department of Anesthesiology Government Medical CollegeHaldwaniNainital 263129India Department of Critical Care Medicine Apollo HospitalsChennai 600006India Department of Hospitalist Medicine Allegany ClinicAllegany Health NetworkPittsburghPA 15222United States Premkumar Seshadri Department of MedicineMAAGF HealthcareChennai 600024India Department of Internal Medicine and Center for Occupational and Environment Health Maulana Azad Medical CollegeNew DelhiDelhi 110002India Department of Critical Care Medicine Sanjay Gandhi Postgraduate Institute of Medical SciencesLucknow 226014India Department of Critical Care Medicine Regency Super Speciality HospitalLucknow 208005India Nayati Healthcare New DelhiDelhi 110065India Department of Pulmonary and Critical Care Medicine Texas A&M UniversityCollege StationTX 77843United States Department of Critical Care United Memorial Medical CenterHoustonTX 77091United States ININ-2018 Investigators Team

BACKGROUND A diverse country like India may have variable intensive care units(ICUs)practices at state and city *** To gain insight into clinical services and processes of care in ICUs in India,this would help plan for potential educational and quality improvement *** The Indian ICU needs assessment research group of diverse-skilled individuals was formed.A pan-India survey"Indian National ICU Needs"assessment(ININ 2018-I)was designed on google forms and deployed from July 23rd-August 25th,*** survey was sent to select distribution lists of ICU providers from all 29 states and 7 union territories(UTs).In addition to emails and phone calls,social medial applications-WhatsApp™,Facebook™and LinkedIn™were used to remind and motivate *** completing and submitting the survey,providers gave their consent for research *** study was deemed eligible for category-2 Institutional Review Board exempt *** There were total 134 adult/adult-pediatrics ICU responses from 24(83%out of 29)states,and two(28%out of 7)UTs in 61 *** had median(IQR)16(10-25)beds and most,were mixed medical-surgical,111(83%),with 108(81%)being adult-only *** responders were young,median(IQR),38(32-44)years age and majority,n=108(81%)were *** consultants were,n=101(75%).A total of 77(57%)reported to have 24 h in-house intensivist.A total of 68(51%)ICUs reported to have either 2:1 or 2≥:1 patient:nurse *** than 80%of the ICUs were open,and mixed *** followed regularly by the ICUs included sepsis care,ventilator-associated pneumonia(83%each);nutrition(82%),deep vein thrombosis prophylaxis(87%),stress ulcer prophylaxis(88%)and glycemic control(92%).Digital infrastructure was found to be poor,with only 46%of the ICUs reporting high-speed internet *** In this large,national,semi-structured,need-assessment survey,the need for improved manpower including;in-house intensivists,and decreasing

关键词： Intensive care unit Critical care India Survey Intensive care unit survey Intensive care unit needs

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