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Understanding and tuning blue-to-near-infrared photon cutting by the tm^(3+)/Yb^(3+) couple

Light(Science & Applications) 2020年第1期9卷 992-1000页

作者： Dechao Yu ting Yu Arnoldus Jvan Bunningen Qinyuan Zhang Andries Meijerink freddy t.rabouw Debye Institute for Nanomaterials Science Utrecht UniversityPrincetonplein 13584 CC UtrechtThe Netherlands State Key Laboratory of Luminescence Materials and Devices Institute of Optical Communication MaterialsSouth China University of TechnologyGuangzhou 510641China

Lanthanide-based photon-cutting phosphors absorb high-energy photons and‘cut’them into multiple smaller excitation *** quanta are subsequently emitted,resulting in photon-conversion efficiencies exceeding *** photon-cutting process relies on energy transfer between optically active lanthanide ions doped in the ***,it is not always easy to determine,let alone predict,which energy-transfer mechanisms are operative in a particular *** makes the identification and design of new promising photon-cutting phosphors *** we unravel the possibility of using the tm^(3+)/Yb^(3+) lanthanide couple for photon *** compare the performance of this couple in four different host *** energy transfer from tm^(3+)to Yb^(3+) would enable blue-to-near-infrared conversion with 200% ***,we identify phonon-assisted cross-relaxation as the dominant tm^(3+)-to-Yb^(3+) energy-transfer mechanism in YBO_(3),YAG,and Y_(2)O_(3).In NaYF_(4),in contrast,the low maximum phonon energy renders phonon-assisted cross-relaxation impossible,making the desired cooperative mechanism the dominant energy-transfer *** work demonstrates that previous claims of high photon-cutting efficiencies obtained with the tm^(3+)/Yb^(3+) couple must be interpreted with ***,the tm^(3+)/Yb^(3+) couple is potentially promising,but the host material-more specifically,its maximum phonon energy-has a critical effect on the energy-transfer mechanisms and thereby on the photon-cutting performance.

关键词： couple phonon lanthanide

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Multi-photon quantum cutting in Gd_(2)O_(2)S:tm^(3+) to enhance the photo-response of solar cells

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Light(Science & Applications) 2015年第1期4卷 144-151页

作者： De-Chao Yu Rosa Martin-Rodriguez Qin-Yuan Zhang Andries Meijerink freddy t rabouw State Key Laboratory of Luminescence Materials and Devices and Institute of Optical Communication Materials South China University of TechnologyGuangzhou 510641China Debye Institute for Nanomaterials Science Utrecht UniversityP.O.Box 800003508 TA Utrechtthe Netherlands

Conventional photoluminescence(PL)yields at most one emitted photon for each absorption ***(or quantum cutting)materials can yield more than one photon by virtue of energy transfer processes between luminescent *** this work,we introduce Gd2O2S:tm^(3+) as a multi-photon quantum *** can convert near-infrared,visible,or ultraviolet photons into two,three,or four infrared photons of,1800 nm,*** cross-relaxation steps between tm^(3+) ions that lead to quantum cutting are identified from(time-resolved)PL as a function of the tm^(3+) concentration in the crystal.A model is presented that reproduces the way in which the tm^(3+) concentration affects both the relative intensities of the various emission lines and the excited state dynamics and providing insight in the quantum cutting ***,we discuss the potential application of Gd2O2S:tm^(3+) for spectral conversion to improve the efficiency of next-generation photovoltaics.

关键词： downconversion infrared emission quantum cutting solar cells spectral conversions

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Extending the dynamic temperature range of Boltzmann thermometers

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Light(Science & Applications) 2022年第12期11卷 3069-3079页

作者： thomas Pieter van Swieten Jesse Merlijin Steenhoff Auke Vlasblom Ravi de Berg Sam Pieter Mattern freddy teunis rabouw Markus Suta Andries Meijerink Debye Institute for Nanomaterials Science Utrecht UniversityPrincetonplein 13584 CC UtrechtThe Netherlands Inorganic Photoactive Materials Heinrich Heine University DüsseldorfUniversitätsstraBe 140225 DüsseldorfGermany

Lanthanide-doped(nano)crystals are an important class of materials in luminescence *** working mechanism of these thermometers is diverse but most often relies on variation of the ratio of emission intensities from two thermally coupled excited states with *** low temperatures,nonradiative coupling between the states can be slow compared to radiative decay,but,at higher temperatures,the two states reach thermal equilibrium due to faster nonradiative *** thermal equilibrium,the intensity ratio follows Boltzmann statistics,which gives a convenient model to calibrate the ***,we investigate multiple strategies to shift the onset of thermal equilibrium to lower temperatures,which enables Boltzmann thermometry in a wider dynamic *** use Eu^(3+)-doped microcrystals as a model system and find that the nonradiative coupling rates increase for host lattices with higher vibrational energies and shorter lanthanide-ligand distances,which reduces the onset temperature of thermal equilibrium by more than 400 *** additionally reveal that thermometers with excited states coupled by electricdipole transitions have lower onset temperatures than those with magnetic-dipole-coupled states due to selection *** insights provide essential guidelines for the optimization of Boltzmann thermometers to operate in an extended temperature range.

关键词： equilibrium excited dynamic

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Correlating the electronic structure of perovskite La_(1-x)SrxCoO_(3) with activity for the oxygen evolution reaction:the critical role of Co 3d hole state

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Journal of Energy Chemistry 2022年第2期31卷 637-645页

作者： Zechao Shen Mei Qu Jueli Shi freddy E.Oropeza Victor A.de la Peña O’Shea Giulio Gorni C.M.tian Jan P.Hofmann Jun Cheng Jun Li Kelvin H.L.Zhang State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Photoactivated Processes Unit IMDEA Energy InstituteParque Tecnológico de MóstolesAvda.Ramón de la Sagra 328935 MóstolesMadridSpain CELLS-ALBA Synchrotron Carrer de la Llum 2-2608290 Cerdanyola del VallèsSpain Surface Science Laboratory Department of Materials and Earth SciencesTechnical University of Darmstadt Otto-Berndt-Strasse 364287 DarmstadtGermany

Perovskite LaCoO_(3) is being increasingly explored as an effective low-cost electrocatalyst for the oxygen evolution reaction(OER).Sr doping in LaCoO_(3)(La1-xSrxCoO_(3))has been found to substantially increase its catalytic *** this work,we report a detailed study on the evolution of the electronic structure of La1-xSrxCoO_(3) with 0≤x≤1 and its correlation with electrocatalytic activity for the OER.A combination of X-ray photoemission spectroscopy(XPS)and X-ray absorption spectroscopy(XAS)was used to unravel the electronic density of states(DOS)near the Fermi level(EF),which provide insights into the key electronic structure features for the enhanced OER catalytic *** analysis on the Co L-edge XAS suggest that LaCoO_(3) has a low spin state with t_(2g)^(6) e_(g)^(0) configuration at room *** implies that the high OER catalytic activity of LaCoO_(3) should not be rationalized by the occupancy of eg=1 *** Sr^(2+) for La^(3+) in LaCoO_(3) induces Co4+oxidation states and effectively dopes hole states into the top of valence band.A semiconductor-to-metal transition is observed for x>0.2,due to the holeinduced electronic DOS at the EF and increased hybridization between Co 3 d and O 2 *** an electronic modulation enhances the surface adsorption of the*OH intermediate and reduces the energy barrier for interfacial charge transfer,thus improving the OER catalytic activity in La_(1-x)Sr_(x)CoO_(3).In addition,we found that the La_(1-x)Sr_(x)CoO_(3) surface undergoes amorphization after certain period of OER measurement,leading to a partial deactivation of the *** Sr doping levels accelerated the amorphization process.

关键词： Perovskite oxide Oxygen evolution Cobalt Electronic structure

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运动技术典范福特St的前世今生

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航空港 2013年第4期 40-41页

作者： freddy Ford

2002年,第一代福克斯St车型一一福克斯St搭载了代表当时福特先进发动机的代表2.0升自然吸气Duratec发动机,最大动力输出为170马力(约125千瓦),因此该车型也被称为福克斯S t170。2012年,作为福特旗下首款全球高性能车型,全新福克斯St搭... 详细信息

2002年,第一代福克斯St车型一一福克斯St搭载了代表当时福特先进发动机的代表2.0升自然吸气Duratec发动机,最大动力输出为170马力(约125千瓦),因此该车型也被称为福克斯S t170。2012年,作为福特旗下首款全球高性能车型,全新福克斯St搭载了福特广受赞誉的2.0升EcoBoost发动机,输出动力比之前提升近50%,达到184千瓦。

关键词：驾驶性能蒙迪欧操控性能运动技术 St 驾驶体验前轮驱动两厢车动感时尚赛车运动

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Epidemiological and Clinical Pattern of Open Fractures of Long Bones of the Lower Limbs in the South-West Region of Cameroon: A 5-Year Review

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Open Journal of Orthopedics 2021年第9期11卷 278-287页

作者： Chunteng t. Nana Fokam Pius Mokake N. Martin Morane Mbongnu Sam D. Movuh freddy Mertens Bombah Ndasi Henry Palle J. Ngunde A. Chichom-Mefire Department of Surgery Faculty of Health Sciences University of Buea Buea Cameroon Departement of surgery Faculty of Medicine and Pharmaceutical Sciences University of Douala Douala Cameroon

Background: An open fracture is an injury in which the fracture site and/or hematoma communicates with the external environment. It is associated with significant morbidity and disability and is a challenge to the surgical team. The lower extremities are the most often exposed to traumatic injuries compared to other anatomical parts of the body. Patterns of open fractures differ with different mechanisms of injury and the segment of the long bone affected. The correct and timely management of open fractures is beneficial to the patients and leads to a more favorable outcome. This study aimed at describing the pattern of open fractures of long bones of the lower limb treated in 3 major hospitals of the south west region, Cameroon. Methodology: This was a hospital-based retrospective review of files of patients with open fractures of long bones of the lower limb managed at the surgical units of three secondary health facilities in the South-West region of Cameroon from the 1st of January 2015 to the 31st of December 2019. The socio-demographic characteristics, clinical presentation, treatment modalities, and outcomes were recorded. The data was stored and analyzed using Epi info version 7.0 and SPSS version 23.0 respectively. Results: A total of 195 files of patients aged 8 to 80 years were studied. The main age group affected was between 20 tyle

关键词： Open Fractures Long Bones Lower Limb

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Clinical Characteristics and Difficulties in the Management of Cancer of the Penis

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Open Journal of Urology 2021年第11期11卷 436-442页

作者： Kimassoum Rimtebaye Mahamat Ali Mahamat freddy Rimtebaye Kimassoum Frederic Meurde Nemia Antoinette Djekoundade Valentin Andjeffa Valentin Vadandi Koldjimadje Mingue Urology Department University Hospital of National Reference N’Djamena Chad Anatomopathology Department University Hospital of National Reference N’Djamena Chad Dermatology Department University Hospital of National Reference N’Djamena Chad traumatology-Orthopedics Department University Hospital of National Reference N’Djamena Chad University Hospital Center Abéché Chad

Introduction: Penile cancer is a rare primary malignancy that occurs in patients in their 60s and 70s. the aim of the study was to describe the anatomical aspects of penile cancer and to report the difficulties of its... 详细信息

trong>Introduction:trong> Penile cancer is a rare primary malignancy that occurs in patients in their 60s and 70s. the aim of the study was to describe the anatomical aspects of penile cancer and to report the difficulties of its management. trong>Materials and Methods:trong> this was a retrospective descriptive study of patients with penile tumors from January 2007 to December 2019. Patients of sexual age with an ulcerated lesion of the penis, who came to our department and whose clinical and paraclinical workup led to the diagnosis of penile cancer, were included. the variables studied were clinical, paraclinical and therapeutic. trong>Results:trong> In 12 years, we diagnosed and managed 8 patients with penile cancer, an incidence of 0.7 per year. the reason for consultation was the chronic ulcerating wound of the penis with a “cauliflower” aspect. the first medical consultation was late (n = 8) after a long latency period lost to traditional healers. the lesion was located in the glans penis (n = 6) and/or in the corpus cavernosum (n = 2). Histological analysis of the cores concluded to a squamous cell carcinoma. Patients were classified as t2N+M+ (n = 3) and t2N0M0 (n = 5). One patient had accepted partial amputation of the penis. trong>Conclusion:trong> Penile cancer is a rare tumor. Partial amputation of the penis is the only alternative in our practice context, an alternative often refuted.

关键词： Glans Penis Ulcerating Penis Squamous Cell Carcinoma Metastasis Brachytherapy

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Surgical Complications of Kidney transplantation in a Resource Limited Country: Retrospective Study of the First Five Years

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Open Journal of Urology 2023年第9期13卷 371-375页

作者： Coulibaly Noël Yao Evrard Kouamé Adebayo tawakaltu Bolasade tuo Legnima Sekou Michel Yeo Donafologo Daouda Dah freddy Service d’urologie CHU Treichville Abidjan C&#244te d’Ivoire Département de Chirurgie et Spécialités Chirurgicales Université Felix Houphou&#235t Boigny UFRSMA Cocody Abidjan C&#244te d’Ivoire

Background: Kidney transplantation is the most efficient treatment for renal failure but may be ruined by complications. Objective: to report the surgical complications of renal transplantation and the therapeutic means applied. Method: It was a retrospective study including 42 files of kidney transplantation in Côte d’Ivoire. We report 11 cases of surgical complications of the recipient’s intervention during the first five years. Results: the mean age was 42.64 years (±15.04). In 90.9% of the cases, there was a comorbidity factor. Lymphocele and stenosis of the uretero vesical anastomosis were the most frequent complications. One death was observed. Conclusion: Kidney transplantation is an effective way of managing chronic renal failure. Postoperative complications are polymorphic and unpredictable.

关键词： Renal transplantation Post Operative Complication Ureterovesical Stenosis Lymphocele

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Rationale of a Cross-Sectional Descriptive Study on temporal Evolution of Frequency, Risk Factors and Complications of Preeclampsia in the University Clinics of Kinshasa, DR Congo

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Open Journal of Obstetrics and Gynecology 2023年第9期13卷 1469-1477页

作者： Muela Andy Mbangama Otem Christian Ndesanzim Ambis Joëlle Lumaya Nkongolo freddy Muamba Mubalamata Eugène-Patrick Lukusa Nkashama Bienvenu Kazadi Ndombasi Nelda Lemba Banza Jésual Lotoy Feruzi Michel Mangala Department of Gynecology and Obstetrics University Clinics of Kinshasa The Democratic Republic of the Congo

Background: Knowledge of temporal evolution of preeclampsia (PE) in its various aspects is essential in strategies to reduce maternal and perinatal morbidity and mortality. Preeclampsia is a public health problem due to maternal mortality associated with it worldwide (5.6%). Improving quality of its management is a major challenge in low-income countries where, despite progress made in this field, PE remains a major factor in maternal morbidity and mortality. Objective: to evaluate temporal evolution of frequency, risk factors and complications of PE at the University clinics of Kinshasa (UCK). Methods: Descriptive and cross-sectional study concerning minimum simple size of 119 pregnant women who consulted for antenatal care at the University clinics of Kinshasa from January 2012 to December 2022. Results will be reported as percentage proportion, mean and standard deviation. Comparison of proportion and means between groups will be made using Student’s t-test and Pearson’s chi-square test, respectively. the test will be statistically significant for a p value ≤ less than 0.05. Data will be collected and analysed anonymously and confidentially. Conclusion: this study will allow us to evaluate the effectiveness of different prevention and treatment modalities used over time in management of preeclampsia in our setting.

关键词： temporal Evolution Preeclampsia Frequency Risk Factors Complications

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Rationale of Longitudinal Cohort Study on Obstetrical Outcomes of trichomonas vaginalis Infection in Kinshasa, DR Congo

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Open Journal of Obstetrics and Gynecology 2023年第9期13卷 1460-1468页

作者： Muela Andy Mbangama Banza Jésual Lotoy Ambis Joëlle Lumaya Nkongolo freddy Muamba Mubalamata Eugène-Patrick Lukusa Nkashama Bienvenu Kazadi Ndombasi Nelda Lemba Otem Christian Ndesanzim Feruzi Michel Mangala Department of Gynecology and Obstetrics University Clinics of Kinshasa Kinshasa The Democratic Republic of the Congo

Background: trichomoniasis is the most common non-viral sexually transmitted infection (StI) in the world, and the occurrence of this infection during pregnancy is responsible for adverse obstetrical outcomes like premature labor, premature rupture of membranes (PROM) and low birth weight (birth weight the association with a number of factors (maternal age, low level of education, low socio-economic status and multiple sexual partners, etc.) that can be found in our environment suggest its probably high prevalence amongst vaginal infections that are responsible for adverse obstetrical outcomes, but up-to-date estimates are lacking. Objective: to assess the obstetrical risk associated with trichomonas vaginalis (t. vaginalis) infection in our environment. Methods: We designed a protocol for a prospective cohort study which will take place in four medical facilities in the city of Kinshasa, where all pregnant women with a pregnancy of at least 20 weeks and who will give written consent will be included. Vaginal swab specimens will be collected for t. vaginalis research by direct microscopy wet mount. Follow-up will consist of recording the process of the pregnancy and obstetrical outcomes. Conclusion: Results from this study will allow to enhance management and also bring updated estimates on t. vaginalis prevalence and its obstetrical outcomes for infected pregnant woman in our environment.

关键词： trichomonas vaginalis Infection Obstetrical Outcomes Kinshasa

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