University of Antananarivo

About: University of Antananarivo is a education organization based out in Antananarivo, Madagascar. It is known for research contribution in the topics: Population & Lemur. The organization has 1561 authors who have published 1703 publications receiving 30922 citations. The organization is also known as: Tananarive University & Antananarivo University.

Influence of chamber volume in single-walled carbon nanotube synthesis by an electric arc

Abstract: Single-walled carbon nanotubes (SWCNTs) were produced by an electric arc process in a low-pressure chamber with vertical electrodes using heterogeneous graphite anodes containing nickel and yttrium catalysts The influence of the chamber volume (18, 25 and 60 L) and graphite grain size (1 and 100 µm) of the anode on the resulting products was analysed This was correlated with the physical properties of the plasma as studied by optical emission spectroscopy and with the temperature of the gaseous atmosphere surrounding the plasma as measured using thermocouples Nanotube yield and purity were evaluated from high-resolution transmission electron microscopy Results showed a strong influence of the heterogeneous anode grain size It was found that the optimal synthesis conditions correspond to an arc chamber volume of 25 L and a graphite grain size of 1 µm In that case the plasma temperature and the carbon over nickel concentration ratio in the plasma differ notably from those observed under the other synthesis conditions It was also found that a slower temperature rise of the gaseous atmosphere surrounding the plasma and a higher anode erosion rate are associated with a higher SWCNT yield These results were interpreted considering the vapour–liquid–solid nanotube formation model

Characterization of 22 microsatellite marker loci in the Madagascar rousette ( Rousettus madagascariensis )

Abstract: Twenty-two nuclear microsatellite loci were isolated from a genomic DNA library derived from Madagascar’s Rousettus madagascariensis. Marker characteristics were determined from a single population (37 individuals) from Fort Dauphin (southeastern Madagascar). Sixteen of the 22 loci were within Hardy–Weinberg expectations. These loci are highly informative with polymorphic information content values ranging between 0.757 and 0.916. These loci will provide valuable information for the study of population genetics and gene flow within this species of bats. Due to the dramatic reduction and alteration of their habitat, data generated utilizing this marker suite will potentially provide additional information for the effective long-term management of this near-threatened bat species.

Pediatric thiamine deficiency disorders in high-income countries between 2000 and 2020: a clinical reappraisal.

Abstract: Often thought to be a nutritional issue limited to low- and middle-income countries (LMICs), pediatric thiamine deficiency (PTD) is perceived as being eradicated or anecdotal in high-income countries (HICs). In HICs, classic beriberi cases in breastfed infants by thiamine-deficient mothers living in disadvantaged socioeconomic conditions are thought to be rare. This study aims to assess PTD in HICs in the 21st century. Literature searches were conducted to identify case reports of PTD observed in HICs and published between 2000 and 2020. The analyzed variables were age, country, underlying conditions, clinical manifestations of PTD, and response to thiamine supplementation. One hundred and ten articles were identified, totaling 389 PTD cases that were classified into four age groups: neonates, infants, children, and adolescents. Eleven categories of PTD-predisposing factors were identified, including genetic causes, lifestyle (diabetes, obesity, and excessive consumption of sweetened beverages), eating disorders, cancer, gastrointestinal disorders/surgeries, critical illness, and artificial nutrition. TD-associated hyperlactatemia and Wernicke encephalopathy were the most frequent clinical manifestations. The circumstances surrounding PTD in HICs differ from classic PTD observed in LMICs and this study delineates its mutiple predisposing factors. Further studies are required to estimate its magnitude. Awareness is of utmost importance in clinical practice.

The semifossorial function of the forelimb in the common rice tenrec (Oryzorictes hova) and the streaked tenrec (Hemicentetes hemispinosus).

Abstract: The forelimb muscles of the two semifossorial species of Tenrecidae (Oryzoryctinae: common rice tenrec; and Tenrecinae: streaked tenrec) were compared macroscopically with those of the unspecialized terrestrial-arboreal species, the Talazac long-tailed tenrec. The structure of the hand was also observed using three-dimensional reconstructed images from computed tomography data. The two semifossorial species had similar muscle weight ratios in the lateral and long heads of M. triceps brachii and M. teres major. A similar hand skeleton structure (in which the second, third and fourth metacarpals and phalanges act as a digging apparatus) was observed in both species. Our observations confirm that both these species have muscular-skeletal adaptations supporting fossorial locomotion. As each species belongs to a monophyletic subfamily within the Tenrecidae isolated in Madagascar, such semifossorial adaptations are assumed to have evolved convergently.

Metal-Support Cooperative Effects in Au/VPO for the Aerobic Oxidation of Benzyl Alcohol to Benzyl Benzoate.

Abstract: This paper studies the cooperative effect of Au nanoparticles deposited on vanadyl pyrophosphate oxide (VPO) in the liquid phase oxidation of benzyl alcohol. VPO was prepared using the classical method by thermally treating VOHPO4·0.5H2O precursor in reacting atmosphere at 420 °C for a period of 72 h. Au nanoparticles were deposited by incipient wetness method. The catalysts were characterized by means of XRD, TEM, XPS and Raman. The bulk VPO catalyst contains vanadyl pyrophosphate phase ((VO)2P2O7), and a small amount of VOPO4. The catalytic system exhibits a high activity in the base-free liquid phase oxidation of alcohols compared to Au on activated carbon, classic catalyst used for this type of reaction. Au/VPO showed a high peculiar selectivity to benzyl benzoate (76%), an important product used in the pharmaceutical and perfume industries. This behavior might be ascribed to the presence of strong acid sites of VPO, as determined by liquid phase titration. Stability tests performed on Au/VPO showed a deactivation of 10% after the first run, but a constant conversion along the following five cycles. This phenomenon can be attributed to the increase of mean Au particle size (from 19.1 to 23.4 nm) after recycling tests as well as the partial leaching of Au and V in the reaction media. Moreover, XRD evidenced a modification in the VPO structure with the partial formation of VOHPO4·0.5H2O phase.