Essential oils, chemical composition, and biological activities of Eucalyptus oleosa F. Muell. : A review

Many Eucalyptus species are growing in the border of oasis areas. Eucalyptus sp. are generally known for their richness in essential oils and their virtues and economic interests. However, the great taxonomic diversity affects the quantity and quality of these oils. This study is designed to summarize the chemical composition of Eucalyptus oleosa and their biological activities. The yield of essential oils in the leaves of this species varies from 0.45% to 6.7%. These oils contain many chemical compounds of which 1,8-cineole is the main component (15.31% – 89.4%) followed by α-pinene (1%– 24.7%).  Eucalyptus oleosa essential oils exhibited antioxidant, antibacterial, anti-fungal and insecticidal activities with high variability. This variability is associated to many factors such as subspecific diversity, geographical location, part of plant and essential oil’s extraction method

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

UV-Patterning of Ion Conducting Negative Tone Photoresists Using Azide-Functionalized Poly(Ionic Liquid)s

International audienceThe patterning of solid electrolytes that builds upon traditional fabrication of semiconductors is described. An azide-, functionalized poly(1,2,3-triazolium ionic liquid) is used as an ion conducting negative tone photoresist. After UV-irradiation through an optical mask, micron-scaled, patterned, solid polyelectrolyte layers with controlled sizes and shapes are obtained. Furthermore, alkylation of poly(1,2,3-triazole)s can be generalized to the synthesis of poly(ionic liquid)s with a tunable amount of pendant functionalities

Photoresponsive Polyamides Containing Pentamethylated Norbornadiene Moieties: Synthesis and Photochemical Properties under Sunlight Irradiation

International audiencePhotoresponsive polyamides containing main-chain pentamethylated norbornadiene (NBD) moieties are obtained in quantitative yields via the Yamazaki-Higashi reaction between a pentamethylated NBD dicarboxylic acid and a series of aromatic diamines. Chemical structures are confirmed by H-1 and C-13 NMR and weight average molar masses measured by SEC are in the range of 21,500-28,600 g mol(-1) with chain dispersities close to 2. Physical properties are investigated by FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis, and viscosimetry. All obtained polyamides are amorphous with glass transition temperatures ranging from 68 to 124 degrees C. They are soluble at room temperature in common organic solvents and exhibit good thermal stabilities with T-d10 values ranging from 175 to 276 degrees C. The photochemical isomerization of the NBD moiety into quadricyclane (QC) is studied by UV/vis spectroscopy after sunlight irradiation of polymer films. For all polyamides, a first-order kinetic rate is observed for the conversion of NBD to QC. The thermal release of the stored energy associated to the reverse transformation of QC groups into NBD ones is about 90-95 kJ mol(-1) as measured by DSC of the irradiated polymer films

Screening and Molecular Identification of New Microbial Strains for Production of Enzymes of Biotechnological Interest

ABSTRACT: This research focused on isolation, identification and characterization of new strains of fungi and bacteria, which were able to produce extracellular xylanase, mannanase, pectinase and α-amylase. Fungi isolates were identified on the basis of analyses of 18S gene sequencing and internal transcribed spacer region. The closest phylogenetic neighbors according to 18S gene sequence and ITS region data for the two isolates M1 and SE were Aspergillus fumigatus and Aspergillus sydowii, respectively. I4 was identified as Bacillus mojavensis on the basis of the 16S rRNA gene sequencing and biochemical properties. The enzyme production was evaluated by cultivating the isolated microorganisms in liquid-state bioprocess using wheat bran as carbon source. Two fungi (M1, and SE) and one bacterium (I4) strains were found to be xylanase producer, and several were proven to be outstanding producers of microbial xylanase. The strains producing xylanase secreted variable amounts of starch-debranching enzymes and produced low level β-mannan-degrading enzyme systems. The bacterium strain was found to be capable of producing pectinolytic enzymes on wheat bran at high level. Some of the strains have good potential for use as sources of important industrial enzymes

Synthesis and proton conductive properties of novel sulfonated (sulfone-triazoles) copolymers

International audienceA new bisphenol containing 1,2,3-triazole ring (BPT) was synthetized using the click reaction and copolymerized with diammonium salt of 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid (DFPSS) and 4,4'-difluorodiphenylsulfone (DFPS) to prepare new copper free sulfonated sulfone-(1,2,3-triazole) copolymers (SSTP) for use as a proton exchange membrane fuel cells. Four copolymers with different ion exchange capacity (IEC) in the range of 1 to 1.6 meqH+/g were obtained by varying the molar ratio of the 3 monomers. The structure of SSTP was confirmed by NMR. They are soluble in polar aprotic solvents such as NMP, DMF and DMSO and show good thermal properties. Membranes from three of these SSTPs were prepared using the solution casting method and characterized in order to determine their water uptake (WU) and their ionic conductivity at 80°C

Trans-N-alkylation Covalent Exchanges on 1,3,4-Trisubstituted 1,2,3-Triazolium Iodides

International audience1,3,4-Trisubstituted 1,2,3-triazolium salts having either aliphatic or benzylic substituents at the N-1 and N-3 positions were synthesized in two steps involving: i) copper(I) catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC), and ii) N-alkylation of the 1,2,3-triazole intermediates. Trans-N-alkylation reactions in bulk and in the presence of excess methyl iodide were monitored by 1H NMR spectroscopy for each 1,2,3-triazolium molecular model. By assigning the different formed species and their respective evolution with time, it was possible to conclude that trans-N-alkylation exchange reactions are significantly faster for benzylic substituents than for aliphatic ones. Furthermore, the exchange reactions are noticeably faster at the N-3 position than at the N-1 position most likely due to the steric hindrance induced by the neighboring C-4 substituent. The kinetics of trans-N-alkylation reactions are thus influenced by both the chemical nature of the N-1 and N-3 substituents and the regiochemistry of the 1,2,3-triazolium group. This provides important structural design rules to improve the properties of thermosetting covalent adaptable networks involving trans-N-alkylation of 1,2,3-triazolium salts

The bean rhizosphere Pseudomonas aeruginosa strain RZ9 strongly reduces Fusarium culmorum growth and infectiveness of plant roots

A faba bean rhizospheric Pseudomonas aeruginosa isolate RZ9 was used for studying its antifungal activity and protecting effects of faba bean and common bean against the root pathogen Fusarium culmorum strain MZB47. The dual culture tests showed that RZ9 inhibits MZB47 in vitro growth by 56%. When mixing RZ9 cell suspension with MZB47 macroconidia at equal proportion, the macroconidia viability was reduced with 70%. Pathogenicity tests conducted in sterile conditions showed that MZB47 caused an intense root rotting in faba bean ‘Aquadulce’ plantlets and a slight level in common bean ‘Coco blanc’. This was associated to significant decreases in plant growth only in ‘Aquadulce’, reducing shoot dry weight (DW) by 82% and root DW by 70%. In soil samples, MZB47 caused severe root rotting and induced significant decreases in shoot DW (up to 51%) and root DW (up to 60%) for both beans. It was associated to a decrease in nodule number by 73% and 52% for faba bean and common bean, respectively. Biocontrol assays revealed that the inoculation of RZ9 to MZB47-treated plantlets enhanced shoot DWs (25% and 110%) and root DWs (29% and 67%), in faba bean and common bean, respectively. Moreover, root rotting levels decreased and nodule number increased in treated compared to untreated plantlets. Collected data highlighted the disease severity of F. culmorum and demonstrated the potential of using RZ9 in controlling Fusaria root diseases in beans. Thereby, the current study represents the first report on the biocontrol effectiveness of P. aeruginosa against F. culmorum in beans