Polymorphism and structural disorder in melt-crystallized and fiber samples of syndiotactic copolymers of propane with 1-butene

The structural characterization of melt-crystallized samples and oriented fibers of syndiotactic copolymers between propene and 1-butene is reported. Melt-crystallized samples of copolymers are crystallized in the form I of syndiotactic polypropylene (s-PP) up to a Content of 1-butene of 60-70 mol %, although disorder in the alternation of right- and left-handed helical chains along both axes of the unit cell is present. More ordered modifications, close to the limit ordered, fully antichiral, form I of s-PP are obtained by crystallization at high temperatures only for samples containing small contents of 1-butene (1-2 mol %). The presence of 1-butene prevents that the order in the alternation of right- and left-handed helical chains develops at high crystallization temperatures. Samples with contents of 1-butene higher than 70 mol % crystallize in structures similar to that of form I of syndiotactic poly(1-butene). Fiber samples of copolymers with small content of 1-butene (1-2 mol %) present the same behavior of syndiotactic polypropylene. Stretched fibers are in the trans planar form III of s-PP,which transforms into the isochiral helical form II of s-PP upon the release of the tension. Mixtures of crystals in forms I and II of s-PP are obtained by annealing. With increasing the 1-butene content only the antichiral helical form I of s-PP is observed in the stretched fibers of the copolymers, as well as upon the release of the tension. The presence of 1-butene units, for contents higher than 4 mol %, prevents the formation of the trans planar form III of s-PP by stretching. For these samples the formation of form I of s-PP, instead of the isochiral form II, either in the stretched fibers or upon the release of the tension, is a further evidence that the isochiral helical form II of s-PP can be obtained only from fibers initially in the trans planar form III, through a cooperative conformational transformation which induce the formation of helical chains having the same chirality

INDICADORES METABÓLICOS SANGUÍNEOS DE GENOTIPOS LECHEROS EN PASTOREO DE LA PROVINCIA DE NAPO-ECUADOR

El objetivo de este trabajo fue evaluar el metabolismo energético/proteico en sangre de vacas lecheras de cuatro genotipos de primera lactancia en condiciones de pastoreo en el cantón Arosemena Tola, Napo, Ecuador. Se evaluaron 36 vacas lecheras de primer parto cruzas de los genotipos: Bos Indicus x Gir (GIR), Bos Indicus x Brown Swiss (BS), Bos Indicus x Jersey (J) y Bos Indicus x Sahiwal (S). Se tomaron muestras de sangre de la vena coccígea los días 60 y 21 antes del parto, al momento del parto y a los 30, 60 y 90 días después del parto. Se determinaron los valores en plasma de, glucosa, urea, creatinina y proteínas totales. Ninguna de las variables presentó diferencias significativas (p0,05) entre razas y los valores obtenidos para todos se encontraron por debajo de los valores normales para las vacas lecheras. La glucosa no mostró diferencias significativas (p0,05) en el tiempo. En cambio, para Urea, Creatinina y Proteínas Totales existieron diferencias significativas (p0,001) a través del tiempo. Utilizando una regresión local con parámetro de suavizado igual a 0,8 para estudiar cómo era la trayectoria de la variable en el tiempo. Luego, se ajustó un modelo lineal mixto para cada variable, considerando un nodo en los casos para los cuales se observaba un cambio en la trayectoria en algún tiempo en particular (según lo observado en el gráfico 1, 2 y 3 de la regresión local). Se concluye que para los cuatro genotipos lecheros estudiados no se encontró diferencias en la concentración de los indicadores metabólicos

ANÁLISES GENÉTICAS EM POPULAÇÕES DE SOJA RESISTENTES AO CANCRO DA HASTE E DESTINADAS PARA ÁREAS CANAVIEIRAS

O presente trabalho objetivou estimar alguns parâmetros genotípicos e fenotípicos de onze caracteres agronômicos em cinco populações de soja nas gerações F5 e F6, assim como recomendar o critério de seleção mais promissor. As populações foram conduzidas no esquema experimental de linhas segregantes intercaladas com cultivares-padrão nos anos agrícolas 2003/04 e 2004/05, em áreas de reforma de canavial, em Jaboticabal, SP. Os resultados obtidos evidenciaram que as médias das populações foram superiores ou muito próximas das médias dos cultivares-padrão. Para número de dias para maturação, a seleção para precocidade e a ocorrência da ferrugem asiática nos genótipos F5 mais tardios foram possíveis agentes responsáveis pela redução do ciclo. Quanto aos demais caracteres foram obtidos valores adequados com as exigências para o cultivo em rotação com a cana-de-açúcar. As estimativas de herdabilidade no sentido amplo e restrito foram próximas, indicando que a maior parte da variância genética é de natureza aditiva, principalmente para os caracteres secundários da produção. Recomenda-se a seleção entre famílias preferencialmente, segundo análise dos componentes de variâncias, sendo constatada que a capacidade produtiva das populações pode ainda ser melhorada, mediante imposição de processo seletivo, com eliminação das famílias medíocres

Honey bees and climate explain viral prevalence in wild bee communities on a continental scale

Viruses are omnipresent, yet the knowledge on drivers of viral prevalence in wild host populations is often limited. Biotic factors, such as sympatric managed host species, as well as abiotic factors, such as climatic variables, are likely to impact viral prevalence. Managed and wild bees, which harbor several multi-host viruses with a mostly fecal-oral between-species transmission route, provide an excellent system with which to test for the impact of biotic and abiotic factors on viral prevalence in wild host populations. Here we show on a continental scale that the prevalence of three broad host viruses: the AKI-complex (Acute bee paralysis virus, Kashmir bee virus and Israeli acute paralysis virus), Deformed wing virus, and Slow bee paralysis virus in wild bee populations (bumble bees and solitary bees) is positively related to viral prevalence of sympatric honey bees as well as being impacted by climatic variables. The former highlights the need for good beekeeping practices, including Varroa destructor management to reduce honey bee viral infection and hive placement. Furthermore, we found that viral prevalence in wild bees is at its lowest at the extreme ends of both temperature and precipitation ranges. Under predicted climate change, the frequency of extremes in precipitation and temperature will continue to increase and may hence impact viral prevalence in wild bee communities

Preparation, Characterization, and Biological Evaluation of a Hydrophilic Peptide Loaded on PEG-PLGA Nanoparticles

The encapsulation of peptides and proteins in nanosystems has been extensively investigated for masking unfavorable biopharmaceutical properties, including short half-life and poor permeation through biological membranes. Therefore, the aim of this work was to encapsulate a small antimicrobial hydrophilic peptide (H-Ser-Pro-Trp-Thr-NH2, FS10) in PEG-PLGA (polyethylene glycol-poly lactic acid-co-glycolic acid) nanoparticles (Nps) and thereby overcome the common limitations of hydrophilic drugs, which because they facilitate water absorption suffer from rapid degradation. FS10 is structurally related to the well-known RNAIII inhibiting peptide (RIP) and inhibits S. aureus biofilm formation. Various parameters, including different method (double emulsion and nanoprecipitation), pH of the aqueous phase and polymeric composition, were investigated to load FS10 into PEG-PLGA nanoparticles. The combination of different strategies resulted in an encapsulation efficiency of around 25% for both the double emulsion and the nanoprecipitation method. It was found that the most influential parameters were the pH—which tailors the peptides charge—and the polymeric composition. FS10-PEG-PLGA nanoparticles, obtained under optimized parameters, showed size lower than 180 nm with zeta potential values ranging from −11 to −21 mV. In vitro release studies showed that the Nps had an initial burst release of 48–63%, followed by a continuous drug release up to 21 h, probably caused by the porous character of the Nps. Furthermore, transmission electron microscopy (TEM) analysis revealed particles with a spherical morphology and size of around 100 nm. Antimicrobial assay showed that the minimum inhibitory concentration (MIC) of the FS10-loaded Nps, against S. aureus strains, was lower (>128 µg/mL) than that of the free FS10 (>256 µg/mL). The main goal of this work was to develop polymeric drug delivery systems aiming at protecting the peptide from a fast degradation, thus improving its accumulation in the target site and increasing the drug-bacterial membrane interactions

Honey bees and climate explain viral prevalence in wild bee communities on a continental scale

Viruses are omnipresent, yet the knowledge on drivers of viral prevalence in wild host populations is often limited. Biotic factors, such as sympatric managed host species, as well as abiotic factors, such as climatic variables, are likely to impact viral prevalence. Managed and wild bees, which harbor several multi-host viruses with a mostly fecal–oral between-species transmission route, provide an excellent system with which to test for the impact of biotic and abiotic factors on viral prevalence in wild host populations. Here we show on a continental scale that the prevalence of three broad host viruses: the AKI-complex (Acute bee paralysis virus, Kashmir bee virus and Israeli acute paralysis virus), Deformed wing virus, and Slow bee paralysis virus in wild bee populations (bumble bees and solitary bees) is positively related to viral prevalence of sympatric honey bees as well as being impacted by climatic variables. The former highlights the need for good beekeeping practices, including Varroa destructor management to reduce honey bee viral infection and hive placement. Furthermore, we found that viral prevalence in wild bees is at its lowest at the extreme ends of both temperature and precipitation ranges. Under predicted climate change, the frequency of extremes in precipitation and temperature will continue to increase and may hence impact viral prevalence in wild bee communities.https://www.nature.com/srepdm2022Zoology and Entomolog

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements