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See detailCryopreservation of chicken primordial germ cells by vitrification and slow-freezing: a comparative study
Tonus, Céline ULg; Connan, Delphine ULg; Waroux, Olivier ULg et al

in Theriogenology (2017), 88

In the present study, we compare a classical slow freezing method and an aseptic vitrification technique to cryopreserve a stable Primordial Gem Cells (PGCs) line issued from the Ardennaise chicken breed ... [more ▼]

In the present study, we compare a classical slow freezing method and an aseptic vitrification technique to cryopreserve a stable Primordial Gem Cells (PGCs) line issued from the Ardennaise chicken breed. Viability immediately after warming was close to 80% and did not differ between the two cryopreservation methods. Proliferation tended to be slower for both cryopreservation methods compared to controls, but the difference was significant only for vitrification. No difference was found between the two methods after flow cytometry analysis of SSEA-1 expression and RT-PCR on several factors related to PGCs phenotype. After one week in culture, all cryopreserved cells reached controls main morphological and expanding (viability/proliferation) features. However, slow freezing generated more unwanted cells clusters than vitrification. After injection of the PGCs into recipient embryos, vitrified PGCs showed a clear, yet not significant, tendency to colonize the gonad at a higher rate than slow frozen PGCs. Slow freezing in cryovials remains simple, inexpensive and less technically demanding than vitrification. Nevertheless, the intrinsic advantages of our aseptic vitrification method and the present study suggest that this should be considered as safer than classical slow freezing for cryopreserving chicken PGCs. [less ▲]

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See detailMicrobiological load of edible insects found in Belgium
Caparros Megido, Rudy ULg; Desmedt, Sandrine; Blecker, Christophe ULg et al

in Insects (2017)

Edible insects are gaining more and more attention as a sustainable source of animal protein for food and feed in the future. In Belgium, some insect products can be found on the market, and consumers are ... [more ▼]

Edible insects are gaining more and more attention as a sustainable source of animal protein for food and feed in the future. In Belgium, some insect products can be found on the market, and consumers are sourcing fresh insects from fishing stores or towards traditional markets to find exotic insects that are illegal and not sanitarily controlled. From this perspective, this study aims to characterize the microbial load of edible insects found in Belgium (i.e., fresh mealworms and house crickets from European farms and smoked termites and caterpillars from a traditional Congolese market) and to evaluate the efficiency of different processing methods (blanching for all species and freeze-drying and sterilization for European species) in reducing microorganism counts. All untreated insect samples had a total aerobic count higher than the limit for fresh minced meat (6.7 log cfu/g). Nevertheless, a species-dependent blanching step has led to a reduction of the total aerobic count under this limit, except for one caterpillar species. Freeze-drying and sterilization treatments on European species were also effective in reducing the total aerobic count. Yeast and mold counts for untreated insects were above the Good Manufacturing Practice limits for raw meat, but all treatments attained a reduction of these microorganisms under this limit. These results confirmed that fresh insects, but also smoked insects from non-European trades, need a cooking step (at least composed of a first blanching step) before consumption. Therefore, blanching timing for each studied insect species is proposed and discussed. [less ▲]

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See detailLandscape ecological consequences of the (sub)urbanization process in an African city: Lubumbashi (Democratic Republic of Congo)
Andre, Marie ULg

Doctoral thesis (2017)

If anthropogenic effect is a general term accounting for the influence of human activities on environment, it may also designate specific influences that may be inter- and intralinked. Thus, urbanization ... [more ▼]

If anthropogenic effect is a general term accounting for the influence of human activities on environment, it may also designate specific influences that may be inter- and intralinked. Thus, urbanization and suburbanization are anthropogenic processes contributing to the broad anthropogenic effect. They hide in turn other subprocesses of land transformation that will be called here the secondary spatial impacts. However, although the growing influence of the latter processes, they are still not defined consensually nor exist a comprehensive and applied-oriented methodology to delimit them. The general objective of this thesis is to develop a spatially explicit methodology to evaluate the landscape ecological consequences of the urbanization and suburbanization processes, taking a representative city of Sub-Saharan Africa as a case study: Lubumbashi (Democratic Republic of Congo), and the last decade as the period of study. That general objective is addressed through two themes, to which correspond specific objectives. The first theme concerns the evaluation of the anthropogenic land use and land cover dynamics and the second one proposes a methodology to evaluate the expansion of urban and suburban areas, in relation with consistent definitions of the areas in the urban-rural gradient. For both themes, the propositions are based on remote sensing techniques and landscape ecology metrics. Results show that the region of Lubumbashi underwent a global anthropisation increase mostly constituted of minor rises of anthropisation levels but impacting mainly the most natural landscape classes. Urban and suburban areas were located through the use of the proportion of built-up metric, the secondary spatial impact area through the use of adjacencies of the less natural landscape patches. The growth shape of the urban and suburban areas is concentric, except in the south-western part of the city where an affluent of the river Kafubu and its adjacent wetlands slow the urban expansion. The secondary spatial impact area dynamics seems determined, in the north-west, by the relief and, in the north-east, by a transportation axis. It is the latter dynamics that is dominant for the period. It corresponds to the so-called savanisation process, probably due to wood fuel and charcoal production. The methodologies developed here could be improved by taking connectedness into account, by using an additional configuration metric for the definition of urban areas or by taking advantage of spatially explicit socio-economic data. They could also be tested on mining sites, other cities and/or using images of different spatial resolution. [less ▲]

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See detailIron, zinc and manganese interaction within the frd3 Arabidopsis mutant
Scheepers, Maxime ULg; Spielmann, Julien ULg; Goormaghtigh, Erik et al

Poster (2017, January 12)

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See detailWhat is the use of shaping a tang? Tool use and hafting of tanged tools in the Aterian of Northern Africa
Tomasso, Sonja ULg; Rots, Veerle ULg

in Archaeological and Anthropological sciences (2017)

We present the results of detailed microscopic examination of tanged tools from the site of Ifri n'Ammar. The rock shelter has a particularly rich and well-preserved stratigraphy that has yielded a large ... [more ▼]

We present the results of detailed microscopic examination of tanged tools from the site of Ifri n'Ammar. The rock shelter has a particularly rich and well-preserved stratigraphy that has yielded a large variety of tanged tools, thus offering a possibility to test hypotheses on the possible links between tangs and hafting. Earlier methodological work has demonstrated that patterned wear forms on the non-active part of the tool as the result of hafted tool use, and that the characteristics of the wear traces depend on the exact hafting arrangement used. In the present study, wear analyses were combined with further experiments that involved the hafting of tanged tools with various materials and arrangements and aimed at understanding the development of this important morphological innovation. We suggest that functional data are needed to understand the relevance of the "Aterian tang" for hafting (or use), and whether this innovation was triggered by functional, cultural or environmental factors. [less ▲]

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See detailFermi-LAT kills dark matter interpretations of AMS-02 data. Or not?
Belotsky, Konstantin; Budaev, Ruslan; Kirillov, Alexander et al

in Journal of Cosmology and Astroparticle Physics (2017)

A number of papers attempt to explain the positron anomaly in cosmic rays, observed by PAMELA and AMS-02, in terms of dark matter (DM) decays or annihilations. However, the recent progress in cosmic gamma ... [more ▼]

A number of papers attempt to explain the positron anomaly in cosmic rays, observed by PAMELA and AMS-02, in terms of dark matter (DM) decays or annihilations. However, the recent progress in cosmic gamma-ray studies challenges these attempts. Indeed, as we show, any rational DM model explaining the positron anomaly abundantly produces final state radiation and Inverse Compton gamma rays, which inevitably leads to a contradiction with Fermi-LAT isotropic diffuse gamma-ray background measurements. Furthermore, the Fermi-LAT observation of Milky Way dwarf satellites, supposed to be rich in DM, revealed no significant signal in gamma rays. We propose a generic approach in which the major contribution to cosmic rays comes from the dark matter disc and prove that the tension between the DM origin of the positron anomaly and the cosmic gamma-ray observations can be relieved. We consider both a simple model, in which DM decay/annihilate into charged leptons, and a model-independent minimal case of particle production, and we estimate the optimal thickness of DM disk. Possible mechanisms of formation and its properties are briefly discussed. [less ▲]

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See detailLa transformation de la pensée politique dans les Pays-Bas entre xve et xvie siècles
Dumont, Jonathan ULg

Scientific conference (2017, January 11)

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See detailSimultaneous anionic ring-opening and condensation reactions for the synthesis of aliphatic–N-alkyl aromatic copolyamides
Bakkali-Hassani, Camille; Tunc, Deniz; Roos, Kevin et al

in Macromolecules (2017), 50(1), 175-181

The copolymerization of ε-caprolactam with ethyl 4-(butylamino)benzoate was shown to occur in the presence of sodium salts and an acyllactam as activator in a one-step bulk reaction. The mechanism is ... [more ▼]

The copolymerization of ε-caprolactam with ethyl 4-(butylamino)benzoate was shown to occur in the presence of sodium salts and an acyllactam as activator in a one-step bulk reaction. The mechanism is based on the deprotonation of the two monomers yielding activated species able to attack an acyllactam or an ester group at the polymer chain ends. Novel copolyamides with different percentages of aromatic/aliphatic units were synthesized in a one-step bulk copolymerization within a few minutes at 140 °C and characterized by NMR spectroscopy, size exclusion chromatography, and thermal analysis (DSC). This methodology, combining simultaneous anionic ring-opening and condensation reactions, affords a new synthetic pathway to introduce an aromatic unit in an aliphatic polyamide backbone, and more specifically a polyamide 6 containing about 20 mol % of N-alkyl aromatic amides was prepared. [less ▲]

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See detailRe-emergence of the Schmallenberg virus associated triad hydranencephaly-micromyelia-arthrogryposis in a newborn calf in Belgium, 2016
Bayrou, Calixte ULg; Garigliany, Mutien-Marie ULg; Cassart, Dominique ULg et al

in Veterinary Record Case Reports (2017), 4(1), 000342

Schmallenberg virus (SBV) emerged in Germany in 2011, then spread rapidly across Europe, causing an epizootic outbreak of abortion, stillbirth and birth at term of lambs, kids and calves with neurological ... [more ▼]

Schmallenberg virus (SBV) emerged in Germany in 2011, then spread rapidly across Europe, causing an epizootic outbreak of abortion, stillbirth and birth at term of lambs, kids and calves with neurological signs and/or musculo-skeletal malformations. SBV-associated disease in newborns disappeared in Belgium in 2013. Here, we describe a SBV genomic RNA-positive malformed calf born in May 2016. It reveals the return of SBV circulation during the fall 2015 in the said area. [less ▲]

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See detailFirst scattered-light images of the gas-rich debris disk around 49 Ceti
Choquet, É.; Milli, J.; Wahhaj, Z. et al

in Astrophysical Journal Letters (2017), 834(2), 12

We present the first scattered-light images of the debris disk around 49 ceti, a ~40 Myr A1 main sequence star at 59 pc, famous for hosting two massive dust belts as well as large quantities of atomic and ... [more ▼]

We present the first scattered-light images of the debris disk around 49 ceti, a ~40 Myr A1 main sequence star at 59 pc, famous for hosting two massive dust belts as well as large quantities of atomic and molecular gas. The outer disk is revealed in reprocessed archival Hubble Space Telescope NICMOS F110W images, as well as new coronagraphic H band images from the Very Large Telescope SPHERE instrument. The disk extends from 1.1" (65 AU) to 4.6" (250 AU), and is seen at an inclination of 73degr, which refines previous measurements at lower angular resolution. We also report no companion detection larger than 3 M_Jup at projected separations beyond 20 AU from the star (0.34"). Comparison between the F110W and H-band images is consistent with a grey color of 49 ceti's dust, indicating grains larger than >2microns. Our photometric measurements indicate a scattering efficiency / infrared excess ratio of 0.2-0.4, relatively low compared to other characterized debris disks. We find that 49 ceti presents morphological and scattering properties very similar to the gas-rich HD 131835 system. From our constraint on the disk inclination we find that the atomic gas previously detected in absorption must extend to the inner disk, and that the latter must be depleted of CO gas. Building on previous studies, we propose a schematic view of the system describing the dust and gas structure around 49 ceti and hypothetic scenarios for the gas nature and origin. [less ▲]

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See detailGeneralized Pascal triangles for binomial coefficients of words: a short introduction
Stipulanti, Manon ULg

Conference (2017, January 09)

We introduce a generalization of Pascal triangle based on binomial coefficients of finite words. These coefficients count the number of times a finite word appears as a subsequence of another finite word ... [more ▼]

We introduce a generalization of Pascal triangle based on binomial coefficients of finite words. These coefficients count the number of times a finite word appears as a subsequence of another finite word. Similarly to the Sierpiński gasket that can be built as the limit set, for the Hausdorff distance, of a convergent sequence of normalized compact blocks extracted from Pascal triangle modulo 2, we describe and study the first properties of the subset of [0, 1] × [0, 1] associated with this extended Pascal triangle modulo a prime p. [less ▲]

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See detailMacroevolutionary patterns in sea breams, emperors and allies (Sparoidea, Acanthomorpha)
Santini, Francesco; Olivier, Damien ULg; Frederich, Bruno ULg

Poster (2017, January 07)

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See detailPollen nutrients better explain bumblebee colony development than pollen diversity
Moerman, Romain; Vanderplanck, Maryse ULg; Fournier, Denis et al

in Insect Conservation and Diversity (2017)

1. Bumblebees are valuable pollinators of numerous wild and cultivated plants. They can forage on variable pollen resources. As some pollen species lack particular nutrients or have global low nutritional ... [more ▼]

1. Bumblebees are valuable pollinators of numerous wild and cultivated plants. They can forage on variable pollen resources. As some pollen species lack particular nutrients or have global low nutritional quality, it has been suggested that bumblebees mix their pollen incomes to ensure a global balanced diet. The hypothesis that a mixed pollen diet better supports bumblebee colony development than a single pollen diet has been poorly explored. 2. We compared the impact of mono-, di- and trifloral diets on microcolony development of Bombus terrestris using three pollen resources with different nutrient contents (Cytisus scoparius, Erica sp. and Sorbus aucuparia) as well as their mixes. Nine parameters (e.g. pollen efficacy: total weight of larvae/total weight of pollen collection) were used to compare the microcolony performances. Moreover, we measured the influence of the pollen diversity and nutritional composition on relevant parameters. 3. We showed that microcolonies can potentially better develop on mixed pollen diets, but single pollen diet can also be as good as mixed pollen diet. Moreover, the sterol concentration appeared as a key factor to establish the impact of a pollen diet on the bumblebee colony development. 4. This study reveals that diverse pollen diet does not necessary equate with good colony development and supports the importance of selecting floral resources by considering their nutrient contents for bee conservation management. [less ▲]

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See detailFlow boiling heat transfer and pressure drop characteristics of R134a, R1234yf and R1234ze in a plate heat exchanger for organic Rankine cycle units
Zhang, Ji; Desideri, Adriano ULg; Ryhl Kaern, Martin et al

in International Journal of Heat & Mass Transfer (2017), 108

The optimal design of the evaporator is one of the key issues to improve the efficiency and economics of organic Rankine cycle units. The first step in studying the evaporator design is to understand the ... [more ▼]

The optimal design of the evaporator is one of the key issues to improve the efficiency and economics of organic Rankine cycle units. The first step in studying the evaporator design is to understand the thermal- hydraulic performance of the working fluid in the evaporator of organic Rankine cycles. This paper is aimed at obtaining flow boiling heat transfer and pressure drop characteristics in a plate heat exchanger under the working conditions prevailing in the evaporator of organic Rankine cycle units. Two hydroflu- oroolefins R1234yf and R1234ze, and one hydrofluorocarbon R134a, were selected as the working fluids. The heat transfer coefficients and pressure drops of the three working fluids were measured with varying saturation temperatures, mass fluxes, heat fluxes and outlet vapour qualities, which range from 60 C to 80 C, 86 kg/m2 s to 137 kg/m2 s, 9.8 kW/m2 to 36.8 kW/m2 and 0.5 to 1, respectively. The working con- ditions covered relatively high saturation temperatures (corresponding reduced pressures of 0.35–0.74), which are prevailing in organic Rankine cycles yet absent in the open literature. The experimental data were compared with existing correlations, and new correlations were developed that are more suitable for evaporation in organic Rankine cycles. The experimental results indicate that heat transfer coefficients are strongly dependent upon the heat flux and saturation temperature. Moreover, the results suggest bet- ter thermal-hydraulic performance for R1234yf than the other two working fluids at the same saturation temperatures. With the new heat transfer and pressure drop correlations, agreements within ±25% were obtained for experimental data in similar experiments with high saturation temperatures. [less ▲]

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