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Geometrical quasi-ballistic effects on thermal transport in nanostructured devices

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Nano Research 2021年第4期14卷 945-952页

作者： Sami Alajlouni Albert Beardo Lluc Sendra Amirkoushyar Ziabari Javier Bafaluy Juan Camacho Yi Xuan F.xavier alvarez Ali Shakouri Birck Nanotechnology Center Purdue UniversityWest LafayetteIndiana 47907USA Department of electrical and computer engineering Purdue UniversityWest LafayetteIndiana 47907USA Department of physics Universitat Autonoma de BarcelonaBellaterra 08193CataloniaSpain Oak Ridge National Laboratory Oak RidgeTennessee 37831USA R&D Staff Scientist ImagingSignals and Machine LearningTennessee 37831USA

We employ thermoreflectance thermal imaging to directly measure the steady-state two-dimensional(2D)temperature field generated by nanostructured heat sources deposited on silicon substrate with different geometrical configurations and characteristic sizes down to *** analysis of the results using Fourier's law not only breaks down as size scales down,but it alsofails to capture the impact of the geometry of the heat *** substrate effective Fourier thermal conductivities fitted to wire-shaped and circular-shaped structures with identical characteristic lengths are found to display up to 40%***,a hydrcxjynamic heat transport model reproduces the observed temperature fields for all device sizes and shapes using just intrinsic Si parameters,i.e.,a geometry and size-independent thermal conductivity and nonlocal length *** hydrodynamic model provides insight into the observed thermal response and of the contradictory Fourier *** discuss the substantial Silicon hydrodynamic behavior at room temperature and contrast it to InGaAs,which shows less hydrodynamic effects due to dominant phonon-impurity scattering.

关键词： phonon hydrodynamics nanoscale heat transfer quasi-ballistic transport silicon

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

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

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

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

Response of the Thermal Conductivity as a Function of Water Content of a Burnt Mediterranean Loam Soil

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Open Journal of Soil Science 2012年第1期2卷 1-6页

作者： Carles M. Rubio xavier Ubeda francesc Ferrer Department Agri-Food Engineering and Biotechnology Polytechnic University of Catalonia Barcelona Spain Department Environmental Biophysics and Soils Lab-Ferrer Soils and Environmental Consulting Cervera Spain Department Physical Geography University of Barcelona Barcelona Spain

The purpose of this research is to explore the variability on the soil thermal conductivity -?- after a prescribe fire, and to assess the effects of the ashes on the heat transfer once it’s were incorporated into the soil matrix. Sampling plot was located in the Montgrí Massif (NE of Spain). A set of 42 soil samples between surface and 5 cm depth was collected before and after the fire. To characterize the soil chemical and physical variables were analyzed. To determine the variability on the soil λ a dry-out curve per scenario (before and after fire) was determined. SoilRho ? method based on ASTM D-5334-08 which was validated by LabFerrer was used. Soil thermal conductivity has shown changes in their values. Indeed, in all moisture scenarios the values of soil λ decreased after soil was burnt. The critical point in the relationshipθ(λ) for the soil after fire which always was stronger than soil before to be burnt. Soil with “white” ashes showed a high thermal conductivity. An X-Ray diffractometry analysis allowed to clarify and to verify these results. To sum up, we could say that thermal conductivity presents changes when the scenario changes, i.e. before and after to be burnt. On the other hand, the volume of ashes incorporated on the soil increased the differences between no burnt and burnt soil, showing even some improvements on the heat transfer when water content started to govern the process.

关键词： Thermal Properties Soil Moisture Prescribed Fire Ashes SoilRHO

Genomic patterns of homozygosity and inbreeding depression in MurcianoGranadina goats

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Journal of Animal Science and Biotechnology 2022年第3期13卷 721-734页

作者： María Gracia Luigi-Sierra Almudena Fernández Amparo Martínez Dailu Guan Juan Vicente Delgado Javier FernándezÁlvarez Vincenzo Landi francesc xavier Such Jordi Jordana María Saura Marcel Amills Centre for Research in Agricultural Genomics(CRAG) CSIC-IRTA-UAB-UBUniversitat Autònoma de Barcelona08193 BellaterraSpain Departamento de Mejora Genética Animal INIACarretera de la Coruña km 7528040 MadridSpain Departamento de Genética Universidad de Córdoba14071 CórdobaSpain Department of Veterinary Medicine University of Bari“Aldo Moro”62 per Casamassima km.370010 ValenzanoSPItaly Group of Research in Ruminants(G2R) Department of Animal and Food ScienceUniversitat Autònoma de Barcelona(UAB)BellaterraBarcelonaSpain Departament de Ciència Animal i dels Aliments Facultat de VeterinàriaUniversitat Autònoma de Barcelona08193 BellaterraSpain

Background:Inbreeding depression can adversely affect traits related to fitness,reproduction and productive *** current research suggests that inbreeding levels are generally low in most goat breeds,the impact of inbreeding depression on phenotypes of economic interest has only been investigated in a few studies based on genealogical ***:We genotyped 1040 goats with the Goat SNP50 *** information was used to estimate different molecular inbreeding coefficients and characterise runs of homozygosity and homozygosity *** detected38 genomic regions with increased homozygosity as well as 8 ROH hotspots mapping to chromosomes 1,2,4,6,14,16 and *** hundred seventeen goats with available records for dairy traits were analysed to evaluate the potential consequences of inbreeding depression on milk *** regions on chromosomes 8 and 25were significantly associated with inbreeding depression for the natural logarithm of the somatic cell ***,these regions contain several genes related with immunity,such as SYK,IL27,CCL19 and ***,one region on chromosome 2 was significantly associated with inbreeding depression for milk ***:Although genomic inbreeding levels are low in Murciano-Granadina goats,significant evidence of inbreeding depression for the logarithm of the somatic cell count,a phenotype closely associated with udder health and milk yield,have been detected in this *** inbreeding would be expected to augment economic gain by increasing milk yield and reducing the incidence of mastitis,which is one of the main causes of dairy goat culling.

关键词： Goat Inbreeding Milk yield Murciano-Granadina Somatic cell score

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

An Eulerian-Lagrangian Modeling of Fluidized Bed

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An Eulerian-Lagrangian Modeling of Fluidized Bed