Use of biodegradable polyester-based microvessels for micropropagation of mature Eucalyptus microcorys

Background: Micropropagation, an in vitro vegetative propagation technique using small propagules is one of the main applications of plant tissue culture. It can be used to clone specific plants with desired traits and reduce the cost of plant propagation. In this study, we developed a protocol for micropropagation of Eucalyptus microcorys F.Muell using a selected mature tree, in which we tested various combinations of different culture media and evaluated the use of biodegradable polyester-based microvessels during the adventitious rooting and acclimatisation phases. Methods: Epicormic shoots were used as an explant source. After the in vitro explant establishment and multiplication, we tested 8 combinations of BAP, NAA and IBA in the elongation phase. Three types of microvessels were tested in the adventitious rooting phase and acclimatisation of the microcuttings. Results: Epicormic shoots had an establishment percentage of 40.6% and a total of 820 explants were generated by the 11th subculture, with an average of 12 buds per explant. Best shoot elongation results were achieved with BAP (0.05 mg L-1) + NAA (1 mg L-1) and BAP (0.05 mg L-1) + NAA (1 mg L-1) + IBA (1 mg L-1) combinations, whereas microvessel types M2 and M3 provided higher rooting and acclimatisation. According to the results of ISSR markers, at the end of 535 days of in vitro cultivation, cloning was successful between acclimatised micro-plantlets and the parent plant. Conclusions: The micropropagation protocol using microvessels was efficient in producing E. microcorys clonal microplantlets and is recommended for further studies with this species, and for testing in the micropropagation of other species.Peer reviewe

Prevalence of oral mucosal lesions in a brazilian military police population

Background: Data obtained from oral health surveys are very important for identifying disease-susceptible groups and for developing dental care and prevention programs. So, the purpose of the current article was to investigate the prevalence of oral mucosa lesions (OMLs) in a population of Brazilian police. Material and Methods: Interviews and oral cavity examinations were performed on a sample of 395 police officers who were randomly selected by the calibrated researcher. The number of individuals was obtained by a sample calculation using the finite population correction. The diagnostic criteria were based on the WHO (1997) criteria and adapted to Brazilian surveys. Results: In total, 8.61% of the population presented some OML. Traumatic injuries and benign migratory glossitis (BMG) were the most prevalent lesions. Conclusions: The prevalence of potentially malignant disorders was lower than among the Brazilian population. The most prevalent lesion among the police officers was related to trauma. Patients dissatisfied with oral health had a higher risk of presenting OMLs

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

Study of pineapples leafs fibers (Ananas genus) and their use as reinforcements for biodegradable poly(latic acid) (PLA)-based composites

In this work natural fibers from new pineapple varieties were studied aiming at their application as mechanical reinforcement for green polymer composites. Eighteen varieties of pineapple leave fibers (PALFs) were then characterized in terms of their morphology, structural arrangement (cellulose crystallinity index (Ic) and microfibril angle), chemical composition (extractives, lignin, holocellulose, cellulose and hemicellulose contents), mechanical properties (tensile strength, elastic modulus and fracture strain) and thermal stability. The studied PALFs had low microfibril angles and high Ic. Their elastic modulus, tensile strength and degradation temperature onset ranged between 15GPa-86GPa, 212MPa-1309MPa, 240°C 272ºC, respectively. All these parameters enabled to nominate the eighteen PALFs as suitable reinforcements for polymers. Close relationships between cellulose, holocellulose and Ic values, and thermal and mechanical properties of PALFs were found out, what provided guidelines for direct selection and/or to support a genetic improvement program of the Ananas genus. An example of such a methodology was presented in this work. The fiber from the pineapple variety called "Potyra" was selected to produce biodegradable composites with poly(lactic acid) (PLA) through injection molding. The Potyra fibers were before hand treated with alkaline solution in order to improve their interfacial compatibility with PLA. The treated Potyra fibers-reinforced composite exhibited an increased elastic modulus from 1,9 GPa to 3,5GPa, tensile strength from 58,8 to 69,6MPa, and notched impact strength from 2,57kJ/m2 to 4,26kJ/m2 in comparison to the pure PLA matrix. The HDT of the PLA was also incremented by 10% due to the fiber incorporation. These findings confirmed the promising potential of Potyra fibers as reinforcements in green composite technologies.Financiadora de Estudos e ProjetosEste trabalho estudou fibras das folhas de diferentes variedades de abacaxis na utilização como reforço mecânico em compósitos poliméricos. Foram caracterizadas fibras de folhas (PALF) de 18 variedades de abacaxis. As fibras tiveram sua morfologia, arranjo estrutural (índice de cristalinidade da celulose (Ic) e ângulo microfibrilar), constituintes químicos (teores de extrativos, lignina, holocelulose, celulose e hemicelulose), propriedades mecânicas (resistência à tração, módulo elástico e alongamento na ruptura) e propriedades térmicas caracterizados. Os pequenos valores do ângulo microfibrilar e maiores valores de Ic indicam que PALF são promissores como reforço mecânico. Os valores do módulo elástico, resistência à tração e temperatura onset de degradação variam de 15 a 86GPa, 212 a 1309MPa, 240 a 272oC respectivamente, indicando que as dezoito variedades de fibras são aptas para aplicação como reforço mecânico em compósitos poliméricos. Foram observadas correlações diretamente proporcionais entre a celulose, holocelulose e Ic com as propriedades térmicas e mecânicas. Estas correlações fornecem indicadores para seleção direta e/ou programa de melhoramento genético do gênero Ananas, com intuito de se desenvolver plantas para utilização de suas fibras como reforço mecânico em compósitos poliméricos. Foi apresentada metodologia para seleção de fibras vegetais a serem utilizadas como reforço mecânico em compósitos. Foi selecionada a variedade denominada Potyra , para fornecer fibras, a fim de produzir compósitos biodegradáveis moldados por injeção, com uma matriz de poli(ácido lático) (PLA). O tratamento em solução com 1% (m/vol.) de NaOH demonstrou-se ser promissor em adequar as fibras para reforçamento de polímeros. Os resultados obtidos nesses compósitos apresentaram em comparação ao PLA puro, aumento no módulo elástico de 1,9 para 3,5GPa, incremento de 5ºC no HDT, a resistência ao impacto com entalhe aumentou de 2,57 para 4,26kJ/m2, e incremento na resistência a tração de 58,8 para 69,6MPa, confirmando o potencial destas fibras para uso como reforço mecânico em compósitos poliméricos

Weldline strenght in injection mouled composites of polypropylene with talcs and glass fiber.

The presence of weld lines in injection moulded reinforced thermoplastics contributes towards substantial reduction in mechanical properties, due to unfavourable orientation of the reinforcement in the weak plane of the weldline. However, published literature presents controversial data on the influence of glass fiber and lamellar talc on the weldline strength. Therefore, tensile mechanical properties of injection moulded polypropylene copolymer (PPcopol) composites with short glass fiber and three different grades of talc (medium, fine and ultrafine size) were investigated in presence and absence of weldline. PPcopol composites with 10, 20, 30 and 40 wt. % of filler were compounded in a co-rotating twin-screw extruder and tensile test specimens were injection moulded without and with butt weldlines. The DSC measured increase in the degree of percentage crystallinity of the thermoplastic matrix with talc content, contributed to a slight increase in tensile strength of talc-filled composites only in mouldings without weldlines. The tensile properties of mouldings with weldline were superior in talc-filled composites than in glass fiber (GF) reinforced composites, indicating clearly the pronounced debilitating effect of higher GF aspect ratio in comparison to the lower aspect ratio of talc lamellae. The depreciation in tensile modulus and strength of the moulded composites with weldline increases with filler volume fraction and is greater in glass fiberreinforced composites than in talc-filled composites. The particle size differences of the three grades of talc used in this work had minor influence on the weldline tensile properties, probably due to the nearly similar values of aspect ratio of lamellae of these talcs. These results on weldline tensile properties of PP composites were corroborated with scanning electron microscopy analysis of the preferential fiber/talc orientation patterns in the weldline region of moulded tensile specimen with and without weldline.Financiadora de Estudos e ProjetosA presença de linhas de solda em moldados por injeção de termoplásticos reforçados contribui para intensa redução nas propriedades mecânicas, devido a orientação desfavorável do reforço no plano fraco da linha de solda. Entretanto, existe na literatura divulgada uma controvérsia sobre o efeito debilitante da fibra de vidro em relação a carga lamelar de talco na resistência à tração da linha de solda. Portanto, as propriedades mecânicas de tração em moldados por injeção de copolímero de propileno (PPcopol) reforçado com fibra de vidro curta e três talcos de granulometrias diferenciadas (media, fina e ultrafina) foram investigados na presença e ausência de linha de solda. Compósitos de PPcopol com 10, 20, 30 e 40% em peso de reforço foram preparados numa extrusora dupla-rosca corrotacional ZSK-30 e corpos de prova para ensaios de tração foram moldados por injeção sem e com linha de solda de encontro frontal (butt weld). O aumento no grau de cristalinidade da matriz termoplástica, medido por DSC em função da concentração do talco, teve influência perceptível apenas nas propriedades mecânicas dos compósitos moldados por injeção sem linha de solda. As propriedades mecânicas de tração dos moldados com linha de solda apresentaram valores absolutos superiores nos compósitos com talcos fino e ultrafino em relação aos de fibra de vidro (FV), demonstrando a influência da maior razão de aspecto do reforço fibroso em relação ao lamelar. A depreciação no módulo e resistência mecânica dos compósitos moldados com linha de solda aumenta com a fração volumétrica do reforço e é maior para os compósitos com FV do que com talco. A granulometria variada dos três tipos de talco teve influência menor nas propriedades mecânicas dos compósitos com linha de solda, provavelmente devido a pequena variação na razão de aspecto dos talcos utilizados