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Silk-based nerve guidance conduits with macroscopic holes modulate the vascularization of regenerating rat sciatic nerve

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Neural Regeneration Research 2025年第6期20卷 1789-1800页

作者： Carina Hromada Patrick Heimel Markus Kerbl LászlóGál Sylvia Nürnberger Barbara Schaedl James Ferguson Nicole Swiadek xavier Monforte Johannes C.Heinzel Antal Nógrádi Andreas H.Teuschl-Woller David Hercher Department Life Science Engineering University of Applied Sciences Technikum WienViennaAustria Austrian Cluster for Tissue Regeneration ViennaAustria Ludwig Boltzmann Institute for Traumatology The Research Center in Cooperation with AUVAViennaAustria University Clinic of Dentistry Medical University of ViennaViennaAustria Department of Plastic Reconstructive and Aesthetic SurgeryLandesklinikum Wiener Neustadt2700 Wiener NeustadtAustria Department of Anatomy Histology and EmbryologyAlbert Szent-Györgyi Medical SchoolUniversity of SzegedSzegedHungary Medical University of Vienna Department of Orthopedics and Trauma SurgeryDevision of Trauma SurgeryViennaAustria Department of Hand- PlasticReconstructive and Burn SurgeryBG Unfallklinik TuebingenUniversity of TuebingenTuebingenGermany

Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). However, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimizatio

关键词： axon regeneration blood vessel functional recovery macroporous nerve lesion peripheral nerve repair sciatic nerve silk-based nerve guidance conduit vascularization

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Influence of surface modified mixed metal oxide nanoparticles on the electrochemical and mechanical properties of polyurethane matrix

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Frontiers of Chemical Science and Engineering 2023年第1期17卷 1-14页

作者： Joseph Raj xavier Department of Chemistry Saveetha School of EngineeringSaveetha Institute of Medical and Technical SciencesChennai-602105India

Newly synthesized functional nanoparticles,3-amino-1,2,4-triazole(ATA)/SiO_(2)—TiO_(2)were introduced to the polyurethane(PU)*** techniques were used to investigate the barrier properties of the synthesized PU—ATA/SiO_(2)—TiO_(2)nanocomposite coated steel *** natural seawater,electrochemical impedance spectroscopy experiments indicated outstanding protective behaviour for the PU—ATA/SiO_(2)—TiO_(2)coated *** coating resistance(Rcoat)of PU—ATA/SiO_(2)—TiO_(2)was determined to be 2956.90 kΩ·cm^(−2).The Rcoat of the PU—ATA/SiO_(2)—TiO_(2)nanocomposite coating was found to be over 50%higher than the PU *** current measured along the scratched surface of the PU—ATA/SiO_(2)—TiO_(2)coating was found to be very low(1.65 nA).The enhanced ATA/SiO_(2)—TiO_(2)nanoparticles inhibited the entry of electrolytes into the coating interface,as revealed by scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray diffraction analysis of the degradation *** contact angle testing validated the hydrophobic nature of the PU—ATA/SiO_(2)—TiO_(2)coating(θ=115.4°).When the concentration of ATA/SiO_(2)—TiO_(2)nanoparticles was 2 wt%,dynamic mechanical analysis revealed better mechanical ***,the newly synthesised PU—ATA/SiO_(2)—TiO_(2)nanocomposite provided excellent barrier and mechanical properties due to the addition of ATA/SiO_(2)—TiO_(2)nanoparticles to the polyurethane,which inhibited material degradation and aided in the prolongation of the coated steel’s life.

关键词： SiO_(2)/TiO_(2)nanoparticle nanocomposite coatings dynamic mechanical analysis electrochemical techniques corrosion colloids and interfaces

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Heterogeneous tunable Ⅲ-Ⅴ-on-silicon-nitride mode-locked laser emitting wide optical spectra

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Photonics Research 2024年第3期12卷 I0021-I0027页

作者： MAXIMILIEN BILLET STIJN CUYVERS STIJN POELMAN ARTUR HERMANS SANDEEP SEEMA SASEENDRA TASUKU NAKAMURA SHINYA OKAMOTO YASUHISA INADA KAZUYA HISADA TAKU HIRASAWA JOAN RAMIREZ DELPHINE NÉEL NICOLAS VAISSIÈRE JEAN DECOBERT PHILIPPE SOUSSAN xavier ROTTENBERG GUNTHER ROELKENS JONØ.KJELLMAN BART KUYKEN Photonics Research Group Department of Information TechnologyGhent University-imec9052 GhentBelgium imec 3001 LeuvenBelgium Technology Division Panasonic Holdings CorporationMoriguchi-CityOsakaJapan Ⅲ-Ⅴ Lab F91767 PalaiseauFrance

We demonstrate a Ⅲ-Ⅴ-on-silicon-nitride mode-locked laser through the heterogeneous integration of a semiconductor optical amplifier on a passive silicon-nitride cavity using the technique of micro-transfer printing. In the initial phase of our study, we focus on optimizing the lasing wavelength to be centered at 1550 nm. This optimization is achieved by conducting experiments with 27 mode-locked lasers, each incorporating optical amplifiers featuring distinct multiple-quantum-well photoluminescence values. Subsequently we present a comprehensive study investigating the behavior of the mode-locking regime when the electrical driving parameters are varied. Specifically, we explore the impact of the gain voltage and saturable absorber current on the locking stability of a tunable mode-locked laser. By manipulating these parameters, we demonstrate the precise control of the optical spectrum across a wide range of wavelengths spanning from 1530 to 1580 nm. Furthermore, we implement an optimization approach based on a Monte Carlo analysis aimed at enhancing the mode overlap within the gain region. This adjustment enables the achievement of a laser emitting a 23-nm-wide spectrum while maintaining a defined 10 dB bandwidth for a pulse repetition rate of 3 GHz.

关键词： tunable amplifier mode

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Determining indoor air quality and identifying the origin of odour episodes in indoor environments

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Journal of Environmental Sciences 2009年第3期21卷 333-339页

作者： Eva Gallego xavier Roca Jose Francisco Perales xavier Guardino Environmental Centre Laboratory Polytechnic University of Catalonia (LCMA-UPC) Avda Diagonal 647 E 08028 Barcelona Spain National Centre of Work Conditions (INSHT) Dulcet 2-10 E 08034 Barcelona Spain

A methodology for identifying volatile organic compounds （VOCs） and determining air quality of indoor air has been developed. The air samples are collected using pump samplers by the inhabitants when they perceive odorous and/or discomfort episodes. Glass multi-sorbent tubes are connected to the pump samplers for the retention of VOC. The analysis is performed by automatic thermal desorption （ATD） coupled with gas chromatography-mass spectrometry （GC/MS）. This methodology can be applied in cases of sick building syndrome （SBS） evaluation, in which building occupants experience a series of varied symptoms that appear to be linked to time spent in the building. Chemical pollutants concentrations （e.g., VOC） have been described to contribute to SBS. To exemplify the methodology, a qualitative determination and an evaluation of existing VOC were performed in a dwelling where the occupants experienced the SBS symptoms. Higher total VOC （TVOC） levels were detected during episodes in indoor air （1.33 ±1.53 mg/m^3） compared to outdoor air （0.71± 0.46 mg/m^3）. The concentrations of individual VOCs, such as ethanol, acetone, isopropanol, 1-butanol, acetic acid, acetonitrile and 1-methoxy-2-propanol, were also higher than the expected for a standard dwelling. The external source of VOC was found to be an undeclared activity of storage and manipulation of solvents located at the bottom of a contiguous building.

关键词： indoor air thermal desorption TVOC VOC sick building syndrome

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Isoperimetric,Sobolev,and Eigenvalue Inequalities via the Alexandroff-Bakelman-Pucci Method:A Survey

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Chinese Annals of Mathematics,Series B 2017年第1期38卷 201-214页

作者： xavier CABRe Universitat Politecnica de Catalunya Departament de MatemktiquesDiagonal 64708028 BarcelonaSpain ICREA Pg.Lluis Companys 2308010 BarcelonaSpain.

This paper presents the proof of several inequalities by using the technique introduced by Alexandroff, Bakelman, and Pucci to establish their ABP estimate. First,the author gives a new and simple proof of a lower bound of Berestycki, Nirenberg, and Varadhan concerning the principal eigenvalue of an elliptic operator with bounded measurable coefficients. The rest of the paper is a survey on the proofs of several isoperimetric and Sobolev inequalities using the ABP technique. This includes new proofs of the classical isoperimetric inequality, the Wulff isoperimetric inequality, and the Lions-Pacella isoperimetric inequality in convex cones. For this last inequality, the new proof was recently found by the author, xavier Ros-Oton, and Joaquim Serra in a work where new Sobolev inequalities with weights came up by studying an open question raised by Haim Brezis.

关键词： Isoperimetric inequalities Principal eigenvalue Wulff shapes ABP estimate

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Performance Back-deduction from a Loading to Flow Coefficient Map:Application to Radial Turbine

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Journal of Thermal Science 2012年第6期21卷 509-517页

作者： xavier CARBONNEAU Nicolas BINDER Université de Toulouse Institut Supérieur de l'Aéronautique et de l'Espace(ISAE)10avenue Edouard Belin BP 54032 31400 ToulouseFrance

Radial turbine stages are often used for applications requiring off-design operation,as turbocharging for *** off-design ability of such stages is commonly analyzed through the traditional turbine map,plotting the reduced mass-flow against the pressure-ratio,for reduced-speed ***,some alternatives are possible,such as the flow-coefficient(Ψ)to loading-coefficient(φ)diagram where the pressure-ratio lines are actually straight lines,very convenient property to perform prediction.A robust method re-creating this map from a predicted Ψ-φ diagram is *** work has shown that this back-deduction quality,without the use of any loss models,depends on the knowledge of an intermediate pressure-ratio.A modelization of this parameter is then *** comparison with both experimental and CFD results is presented,with quite good agreement for mass flow rate and rotational speed,and for the intermediate pressure *** last part of the paper is dedicated to the application of the intermediate pressure-ratio knowledge to the improvement of the deduction of the pressure ratio lines in the Ψ-φ *** this improvement,the back-deduction method of the classical map is structured,applied and evaluated.

关键词： Radial turbine off-design flow coefficient load coefficient performance

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WTR:A Reputation Metric for Distributed Hash Tables Based on a Risk and Credibility Factor

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Journal of Computer Science & Technology 2009年第5期24卷 844-854页

作者： xavier Bonnaire Erika Rosas Departamento de Informatica Universidad Tecnica Federico Santa MariaValparaisoChile Laboratoire d'Informatique de Paris 6 Universite Pierre et Marie CurieCNRS UMR 7606 INRIA REGALParisFrance

The growing number of popular peer to peer applications during the last five years has implied for researchers to focus on how to build trust in such very large scale distributed systems. Reputation systems have shown to be a very good solution to build trust in presence of malicious nodes. We propose in this paper a new metric for reputation systems on top of a Distributed Hash Table that uses a notion of risk to make the applications aware of certain behaviours of malicious nodes. We show that our metric is able to significantly reduce the number of malicious transactions, and that it also provides very strong resistance to several traditional attacks of reputations systems. We also show that our solution can easily scale, and can be adapted to various Distributed Hash Tables.

关键词： peer to peer reputation system risk evaluation

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Natural enemies depend on remnant habitat size in agricultural landscapes

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Journal of Forestry Research 2015年第2期26卷 469-477页

作者： Mainara xavier Jordani erica Hasui Vinicius xavier da Silva Laboratorio de Ecologia Animal Departamento de Zoologia e BotanicaUniversidade Estadual Paulista-UNESPRua Cristovao Colombo2265Jardim NazarethSao Jose Do Rio PretoSP CEP 15054-000Brazil Laboratorio de Ecologia de Fragmentos do Sul de Minas Gerais-ECOFRAG Instituto Ciencias da NaturezaUniversidade Federal de Alfenas-UNIFAL–MGRua Gabriel Monteiro da Silva700CentroAlfenasMG CEP 37130-000Brazil

In recent decades,the consequences of habitat fragmentation have been of growing concern,because it is particularly important to understand how fragmentation may affect biodiversity,an ecological *** tested two hypotheses：（1） that natural fragment size in agricultural landscapes indirectly affects the herbivore through effects on natural predator populations;and（2） predator activity into the crop reduces along the distance from the natural fragment *** 2008 and 2009,we conducted our study in seven forest remnants and in surrounding coffee plantations（fragments ranged from 6 to 105 ha,mean 49.28 ± 36.60 ha） in Southern Minas Gerais,*** were sampled by point counts,and insect predation was evaluated by using an artificial insect model（Koh and Menge 2006）.Our results suggest that although there were many potential predators（e.g.,wasps,ants,birds,and mammals）,birds were the most important taxon *** covariance analysis supported the hypothesis that patch size affected the number of larvae predation by overall taxi,but there was no support for a distance *** findings suggest that natural enemies’ ecological service（mainly from birds） declined with remnant reduction,which has implications not only for human welfare,but also in strengthening the economic justifications for conserving the remaining natural habitats and biodiversity in agricultural landscapes.

关键词： Ecosystem service Fragmentation Isolation Insectivore Predation

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The application of extended modified Lambert Beer model for measurement of blood carboxyhemoglobin and oxyhemoglobin saturation

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Journal of Innovative Optical Health Sciences 2014年第3期7卷 108-114页

作者： Audrey Huong xavier Ngu Department.of Electronic Engineering Faculty of Electrical and Electronic Engineering Uiniversity Tun Hussein Onn Malaysia Batu Pahat 86400 JohorMalaysia Department of Communication Engineering Faculty of Electrical and Electronic Engineering University Tun Hussein Onn Malaysia Batu Pahat 86400 JohorMalaysia

This work presents the use of extended Modified Lambert Beer(MLB)model for accurate andcontinuous monitoring of percent blood carboxyhemoglobin(COHb)(SCO)and oxyhemoglobin(OxyHb)saturation(SO,)via a fitting *** quantification technique is based on theabsorption characteristics of hemoglobin derivatives in the wavelength range of 520-600 nm togive the best estimates of the required parameters.A comparison of the performance of the developed model and MILB law is made using attenuation data from Monte Carlo simulations for a two-layered skin *** results revealed a lower mean absolute error of 0.4%in the valuesestimated by the developed model as compared to 10%that is given by the MILB *** studyshowed that the discussed approach is able to provide consistent and accurate measurement ofblood SO,and SCO across diferent skin pigmen tations suggesting that it may potentially be usedas an alternative means for clinical diagnosis of carbon monoxide(CO)poisoning.

关键词： Blood carboxyhemoglobin saturation carbon monoxide poisoning blood oxyhemoglobin saturation modified Lambert Beer law

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Experimental investigation of flow field in a laboratory-scale compressor

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Chinese Journal of Aeronautics 2017年第1期30卷 31-46页

作者： Ma Hongwei Wei Wei xavier Ottavy Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power Engineering Beihang University Beijing 100083 China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100083 China China Academy of Aerospace Aerodynamics (CAAA) Yungangxi Rd. Fengtai Dist. Beijing 100074 China Laboratoire de Mecanique des Fluides et d'Acoustique (LMFA) Groupe TurbomachinesEcole Centrale de Lyon 36 av. Guy de Collongue 69134 Ecully cedex France

The inner flow environment of turbomachinery presents strong three-dimensional, rotational, and unsteady characteristics. Consequently, a deep understanding of these flow phenomena will be the prerequisite to establish a state-of-the-art design system of turbomachinery. Currently the development of more accurate turbulence models and CFD tools is in urgent need for a high-quality database for validation, especially the advanced CFD tools, such as large eddy simulation（LES）. Under this circumstance, this paper presents a detailed experimental investigation on the 3D unsteady flow field inside a laboratory-scale isolated-rotor with multiple advanced measurement techniques, including traditional aerodynamic probes, hotwire probes, unsteady endwall static pressure measurement, and stereo particle image velocimetry（SPIV）. The inlet boundary layer profile is measured with both hotwire probe and aerodynamic probe. The steady and unsteady flow fields at the outlet of the rotor are measured with a mini five-hole probe and a single-slanted hotwire probe. The instantaneous flow field in the rotor tip region inside the passage is captured with SPIV,and then a statistical analysis of the spatial distribution of the instantaneous tip leakage vortex/flow is performed to understand its dynamic characteristics. Besides these, the uncertainty analysis of each measurement technique is described. This database is quite sufficient to validate the advanced numerical simulation with LES. The identification process of the tip leakage vortex core in the instantaneous frames obtained from SPIV is performed deliberately. It is concluded that the ensemble-averaged flow field could not represent the tip leakage vortex strength and the trajectory trace. The development of the tip leakage vortex could be clearly cataloged into three phasesaccording to their statistical spatial distribution. The streamwise velocity loss induced by the tip leakage flow increases until the splitting process is weak

关键词： Database Laboratory-scale compres-sor SPIV Tip leakage flow Tip leakage vortex

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