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Cold acclimation increases Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae) survival during exposure to freezing temperatures

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Insect Science 2022年第2期29卷 531-538页

作者： xavier Martini Kathi Malfa Dara Stockton Monique JRivera Department of Entomology and Nematology North Florida Research and Education CenterQuincyFloridaUSA USDA-ARS U.S.Pacific Basin Agricultural Research CenterHiloHawaiiUSA Department of Entomology University of CaliforniaRiversideCaliforniaUSA

The Asian citrus psyllid,Diaphorina citri,is the vector of the pathogenic bacteria that causes Huanglongbing,the most devasting disease affecting citrus *** cultivation of citrus tends to expand northward,the tolerance of psyllids to freezing temperatures needs to be *** mortality of *** to cold temperature has been previously studied,much less is known regarding the acclimation potential of psyllids to cold *** first evaluated cold resistance of *** depending on color morph and ***,we compared mortality of *** at−4°C for 10 hours between unacclimated psyllids,psyllids that were gradually acclimated to cold over 1 or 2 weeks,and psyllids intermittently acclimated also for 1 or 2 *** did not find major differences in cold resistance between color morphs and *** found that after 1 week of gradual acclimation,the survival of psyllids at−4°C increased to 86%,compared to 20%in the control *** did not increase after the second week of gradual *** intermittent acclimation improved survival compared to the control group,it was less effective than gradual acclimation with a survival at 30%and 70%after 1 and 2 weeks of acclimation,respectively,although this difference with gradual acclimation was not significant at week *** data show that gradual cold acclimation allows *** to survive brief periods below *** may serve as a mechanism responsible for increasing northern establishment of this pest.

关键词： cold acclimation cold hardy citrus cold resistance citrus greening Diaphorina citri overwintering

Effect of an adverse pressure gradient on the streamwise Reynolds stress profile maxima in a turbulent boundary layer

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Acta Mechanica Sinica 2013年第3期29卷 395-398页

作者： Wei Ma xavier Ottavy Li-Peng Lu Francis Leboeuf Laboratoire de Mécanique des Fluides et d'Acoustique Ecole Centrale de Lyon School of Jet Propulsion Beihang University

It is widely accepted that in a turbulent boundary layer （TBL） with adverse pressure gradient （APG） an outer peak usually appears in the profile of streamwise Reynolds stress. However, the effect of APG on this outer peak is not clearly understood. In this paper, the effect of APG is analysed using the numerical and experimental results in the literature. Because the effect of upstream flow is inherent in the TBL, we first analyse this effect in TBLs with zero pressure gradient on flat plates. Under the individual effect of upstream flow, an outer peak already appears in the profile of streamwise Reynolds stress when the TBL continues developing in the streamwise direction. The APG accelerates the appearance of the outer peak, instead of being a trigger.

关键词： Turbulent boundary layer · Pressure gradient · Reynolds stress

Hepatocyte cryopreservation:Is it time to change the strategy?

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World Journal of Gastroenterology 2010年第1期16卷 1-14页

作者： xavier Stéphenne Mustapha Najimi Etienne M Sokal Catholic University of Louvain and St Luc Clinics Paediatric Department(HPED)PEDI unitLaboratory of Paediatric Hepatology and Cell Therapy

Liver cell transplantation presents clinical benefit in patients with inborn errors of metabolism as an alternative,or at least as a bridge,to orthotopic liver *** success of such a therapeutic approach remains limited by the quality of the transplanted *** remains the best option for long-term storage of hepatocytes,providing a permanent and sufficient cell ***, isolated adult hepatocytes are poorly resistant to such a process,with a significant alteration both at the morphological and functional ***,the aim of the current review is to discuss the state of the art regarding widely-used hepatocyte cryopreservation protocols,as well as the assays performed to analyse the post-thawing cell quality both in vitro and in vivo. The majority of studies agree upon the poor quality and efficiency of cryopreserved/thawed hepatocytes as compared to freshly isolated *** ice formation or exposure to hyperosmotic solutionsremains the main phenomenon of cryopreservation process,and its effects on cell quality and cell death induction will be *** increased knowledge and understanding of the cryopreservation process will lead to research strategies to improve the viability and the quality of the cell suspensions after *** strategies,such as vitrification,will be discussed with respect to their potential to significantly improve the quality of cell suspensions dedicated to liver cell-based therapies.

关键词： Hepatocyte Cryopreservation Quality Mitochondria Intracellular ice formation

Phosphine functionalised multiwalled carbon nanotubes:A new adsorbent for the removal of nickel from aqueous solution

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Journal of Environmental Sciences 2012年第6期24卷 1133-1141页

作者： Muleja Anga Adolph Yangkou Mbianda xavier Pillay Kriveshini Krause Rui Department of Chemical Technology University of JohannesburgDoornfontein Campus P.O Box 17011JohannesburgSouth Africa

Synthesised triphenylphosphine-linked multiwalled carbon nanotubes （Tpp-MWCNTs） were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified *** adsorption capacity increased with an increase in pH for all *** adsorption equilibrium was reached in 40 and 30 min for purified MWCNTs and Tpp-MWCNTs,*** Freundlich and Langmuir isotherms used to investigate the adsorption process fitted the experimental data well with the correlation coefficient R 2 close to 1 for all *** the other hand,the experimental data fitted well with a pseudo secondorder *** speciation of nickel also influenced the adsorption on the purified and *** adsorbents used in this study showed superior adsorption capacity when compared to other adsorbents reported in the literature.

关键词： phosphine functionalised multiwalled carbon nanotubes adsorbent XPS remediation nickel

The potential leaching and mobilization of trace elements from FGD-gypsum of a coal-fired power plant under water re-circulation conditions

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Journal of Environmental Sciences 2015年第6期27卷 72-80页

作者： Patricia Córdoba Iria Castro Mercedes Maroto-Valer xavier Querol Centre for Innovation on Carbon Capture and Storage Institute of Mechanical Process and Energy Engineering Heriot-Watt University Institute of Environmental Assessment and Water Research

Experimental and geochemical modelling studies were carried out to identify mineral and solid phases containing major, minor, and trace elements and the mechanism of the retention of these elements in Flue Gas Desulphurisation（FGD）-gypsum samples from a coal-fired power plant under filtered water recirculation to the scrubber and forced oxidation conditions. The role of the p H and related environmental factors on the mobility of Li, Ni, Zn, As, Se, Mo, and U from FGD-gypsums for a comprehensive assessment of element leaching behaviour were also carried out. Results show that the extraction rate of the studied elements generally increases with decreasing the p H value of the FGD-gypsum leachates. The increase of the mobility of elements such as U, Se, and As in the FGD-gypsum entails the modification of their aqueous speciation in the leachates; UO2SO4, H2 Se, and HAs O2 are the aqueous complexes with the highest activities under acidic *** speciation of Zn, Li, and Ni is not affected in spite of p H changes; these elements occur as free cations and associated to SO4 ^2 in the FGD-gypsum leachates. The mobility of Cu and Mo decreases by decreasing the p H of the FGD-gypsum leachates, which might be associated to the precipitation of Cu Se2 and Mo Se2, respectively. Time-of-Flight mass spectrometry of the solid phase combined with geochemical modelling of the aqueous phase has proved useful in understanding the mobility and geochemical behaviour of elements and their partitioning into FGD-gypsum samples.

关键词： Geochemical modelling studies Trace elements Leaching Landfills FGD-gypsum ToF mass spectrometry

A hierarchical optimisation framework for pigmented lesion diagnosis

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CAAI Transactions on Intelligence Technology 2022年第1期7卷 34-45页

作者： Audrey Huong KimGaik Tay KokBeng Gan xavier Ngu Department of Electronic Engineering Universiti Tun Hussein Onn MalaysiaParit RajaMalaysia Department of Electrical Electronic&Systems EngineeringUniversiti Kebangsaan MalaysiaBangiMalaysia Institute of Integrated Engineering Universiti Tun Hussein Onn MalaysiaParit RajaMalaysia

The study of training hyperparameters optimisation problems remains underexplored in skin lesion *** is the first report of using hierarchical optimisation to improve computational effort in a four-dimensional search space for the *** authors explore training parameters selection in optimising the learning process of a model to differentiate pigmented lesions *** the authors'demonstration,pretrained GoogleNet is fine-tuned with a full training set by varying hyperparameters,namely epoch,mini-batch value,initial learning rate,and gradient *** iterative search of the optimal global-local solution is by using the derivative-based *** authors used non-parametric one-way ANOVA to test whether the classification accuracies differed for the variation in the training *** authors identified the mini-batch size and initial learning rate as parameters that significantly influence the model's learning *** authors'results showed that a small fraction of combinations(5%)from constrained global search space,in contrarily to 82%at the local level,can converge with early stopping *** mean(standard deviation,SD)validation accuracies increased from 78.4(4.44)%to 82.9(1.8)%using the authors'*** fine-tuned model's performance measures evaluated on a testing dataset showed classification accuracy,precision,sensitivity,and specificity of 85.3%,75.6%,64.4%,and 97.2%,*** authors'system achieves an overall better diagnosis performance than four state-of-the-art approaches via an improved search of parameters for a good adaptation of the model to the authors'*** extended experiments also showed its superior performance consistency across different deep networks,where the overall classification accuracy increased by 5%with this *** approach reduces the risk of search being trapped in a suboptimal solution,and its use may be expanded to network architecture optimisation for

关键词： hierarchical hyperparameter optimisation pigmented lesion search

Experimental Study of Corner Stall in a Linear Compressor Cascade

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Chinese Journal of Aeronautics 2011年第3期24卷 235-242页

作者： MA Wei OTTAVY xavier LU Lipeng LEBOEUF Francis GAO Feng Laboratoire de Mecanique des Fluides et d'Acoustique Ecole Centrale de Lyon Ecully 69134 France School of Jet Propulsion Beihang University Beijing 100191 China

In order to gain a better knowledge of the mechanisms and to calibrate computational fluid dynamics （CFD） tools including both Reynolds-averaged Navier-Stokes （RANS） and large eddy simulation （LES）, a detailed and accurate experimental study of comer stall in a linear compressor cascade has been carried out. Data are taken at a Reynolds number of 382 000 based on blade chord and inlet velocity. At first, inlet flow boundary layer is surveyed using hot-wire anemometry. Then in order to investigate the effects of incidence, measurements are acquired at five incidences, including static pressures on both blade and endwall sur- faces measured by pressure taps and the total pressure losses of outlet flow measured by a five-hole pressure probe. The maxi- mum losses as well as the extent of losses of the comer stall are presented as a function of the investigated incidences.

关键词： comer separation compressor cascades incidence hot-wire anemometry computational fluid dynamics

A European digital accelerometric database:statistical analysis of engineering parameters of small to moderate magnitude events

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Earthquake Engineering and Engineering Vibration 2014年第4期13卷 583-597页

作者： Carlos S.Oliveira Gerard Gassol xavier Goula Teresa Susagna Instituto Superior Técnico Universidade de Lisboa Institut Cartogràfic i Geològic de Catalunya

During the NERIES Project, an accelerometric database containing European digital information was developed. Besides event and station metadata, ground motion parameters, computed in a homogeneous manner, were assembled： PGA, PGV, AI, TD, CAV, H1 and PSV（f,5%）（19,961 components, 2629 events, 547 stations）. Merging small and moderate magnitude events produced a unique database capable of providing important information such as：（i） Correlations between several ground motion parameters follow analogous trends as in previous worldwide datasets, with slight corrections. （ii） Although PGA attenuations with distance show great uncertainties, four recent GMPEs recommended for Europe fit quite well the central 50% data interval for the distance range 10 〈 R 〈 200 kin; outside these distances, they do not fit. （iii） Soil amplification ratios indicate that weak motion （low magnitudes and larger distances） shows larger amplification than strong motion （short distances and large magnitudes） as represented in UBC97 for the USA, but not in EC8 for Europe. （iv） Average spectral shapes are smaller than in the EC8. （v） Differences in amplification factors for PGA, PGV and HI for EC8 soil classes B and C, and differences in spectral shapes for these soil classes, indicate that EC8, Type 2 S-coefficient should be frequency dependent, as in UBC97.

关键词： NERIES project parametric accelerometric database European region PGA EC8 soil amplification

Measurement of electrical charges carried by airborne bacteria laboratory-generated using a single-pass bubbling aerosolizer

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Particuology 2015年第1期13卷 179-185页

作者： xavier Simon Sébastien Bau Denis Bémer Philippe Duquenne Institut National de Recherche et de Securite(INRS)

Widely used bioaerosol generators like Collison nebulizer probably produce electrostatically charged par- ticles, but the electrical charges carried by laboratory-generated airborne microorganisms using bubbling aerosolizers are poorly understood. In this study, we measured the fraction of neutral particles and num- ber of elementary charges per particle as a function of the aerodynamic diameter of airborne bacteria （Escherichia coli and Enterococcus hirae）. Bioaerosols were produced by a liquid sparging aerosolizer-type bubbling generator, with particle sizes ranging from roughly 0.6 to 2 p^m. The experimental setup included an electrostatic precipitator and real-time devices including an electrometer, aerodynamic particle sizer, and electrical low-pressure impactor. Experimental results obtained for various operating conditions showed that aerosols produced with a higher bubbling airflow contained a larger proportion of neutral particles （from around 30% to 50%） and that bacteria carried a greater average absolute number of elementary charges （from around -10 to -60 elementary units） than those under lower airflow. Under the investigated conditions, a neutralization step is unnecessary because it may have a negative effect on the viability of sensitive microorganisms. Our results suggest that the neutral fraction can be used down- stream of an electrostatic precipitator, and that this setup may have advantages over bipolar neutralizers.

关键词： Bubbling generator Bioaerosol Electrical charge Electrostatic precipitator Escherichia coil Enterococcus hirae