2-(2-methyl-2-nitrovinyl)furan but not furvina interfere with staphylococcus aureus agr quorum-sensing system and potentiate the action of fusidic acid against biofilms

Quorum sensing (QS) plays an essential role in the production of virulence factors, in biofilm formation and antimicrobial resistance. Consequently, inhibiting QS is being consid-ered a promising target for antipathogenic/anti-virulence therapies. This study aims to screen 2-nitrovinylfuran derivatives structurally related to Furvina (a broad-spectrum antibiotic already used for therapeutic purposes) for their effects on QS and in biofilm prevention/control. Furvina and four 2-nitrovinylfuran derivatives (compounds 1–4) were tested to assess the ability to interfere with QS of Staphylococcus aureus using bioreporter strains (S. aureus ALC1742 and ALC1743). The activity of Furvina and the most promising quorum-sensing inhibitor (QSI) was evaluated in biofilm prevention and in biofilm control (combined with fusidic acid). The biofilms were further characterized in terms of biofilm mass, viability and membrane integrity. Compound 2 caused the most significant QS inhibition with reductions between 60% and 80%. Molecular docking simulations indicate that this compound interacts preferentially with the protein hydrophobic cleft in the LytTR domain of AgrA pocket. Metabolic inactivations of 40% for S. aureus ALC1742 and 20% for S. aureus ALC1743 were reached. A 24 h-old biofilm formed in the presence of the QSI increased the metabolic inactivation by fusidic acid to 80%, for both strains. The overall results highlight the effects of compound 2 as well as the potential of combining QSI with in-use antibiotics for the management of skin and soft tissues infections

The Collins-Roscoe mechanism and D-spaces

We prove that if a space X is well ordered $(\alpha A)$, or linearly semi-stratifiable, or elastic then X is a D-space

Interference of overlapping insect vibratory communication signals: an Eushistus heros Model.

Plants limit the range of insect substrate-borne vibratory communication by their architecture and mechanical properties that change transmitted signal time, amplitude and frequency characteristics. Stinkbugs gain higher signal-to-noise ratio and increase communication distance by emitting narrowband low frequency vibratory signals that are tuned with transmission properties of plants. The objective of the present study was to investigate hitherto overlooked consequences of duetting with mutually overlapped narrowband vibratory signals. The overlapped vibrations of the model stinkbug species Eushistus heros , produced naturally or induced artificially on different plants, have been analysed. They represent female and male strategies to preserve information within a complex masked signal. The brown stinkbugs E. heros cmmunicate with species and gender spe- cific vibratory signals that constitute characteristic duets in the calling, courtship and rivalry phases of mating behaviour. The calling female pulse overlaps the male vibratory response when the latency of the latter is shorter than the duration of the female triggering signal or when the male response does not inhibit the following female pulse. Overlapping of signals induces interference that changes their amplitude pattern to a sequence of regularly repeated pulses in which their duration and the difference between frequencies of overlapped vibrations are related inversely. Interference does not occur in overlapped narrow band female calling pulses and broadband male courtship pulse trains. In a duet with overlapped signals females and males change time parameters and increase the frequency dif- ference between signals by changing the frequency level and frequency modulation pattern of their calls

Steady states in a structured epidemic model with Wentzell boundary condition

We introduce a nonlinear structured population model with diffusion in the state space. Individuals are structured with respect to a continuous variable which represents a pathogen load. The class of uninfected individuals constitutes a special compartment that carries mass, hence the model is equipped with generalized Wentzell (or dynamic) boundary conditions. Our model is intended to describe the spread of infection of a vertically transmitted disease, for example Wolbachia in a mosquito population. Therefore the (infinite dimensional) nonlinearity arises in the recruitment term. First we establish global existence of solutions and the Principle of Linearised Stability for our model. Then, in our main result, we formulate simple conditions, which guarantee the existence of non-trivial steady states of the model. Our method utilizes an operator theoretic framework combined with a fixed point approach. Finally, in the last section we establish a sufficient condition for the local asymptotic stability of the positive steady state

Approach combining the Rietveld method and pairs distribution function analysis to study crystalline materials under high-pressure and/or temperature: Application to rhombohedral Bi2Te3 phase

An approach combining the Rietveld method and pairs distribution function analysis to study crystalline materials under high pressure or temperature was early proposed by us, and in this study, it was applied to investigate de effect of high pressure on the rhombohedral Bi2Te3 phase. The refined structural parameters obtained from the Rietveld refinement of the XRD patterns measured for pressures up to 9.1 GPa were used as input data to simulate the partial and total structure factors SBiBi, SBiTe, STeTe, and SBi2Te3. Fourier transformation of the Sij factors permitted to obtain the partial and total pairs distribution functions GBiBi, GBiTe, GTeTe, and GBi2Te3. The first coordination shells of these Gij functions are formed by subshells and, with increasing pressure in the 1.1 to 6.3 GPa range, occur a partial separation of subshells. Also, the increase of pressure in this range promotes a drastic reduction in the values of the intralayer angles TeBiTe, and consequently, in the intralayer distance TeTe. A drastic reduction in the interlayers distance Te-Te was also observed. Several studies are reported in the literature, including one carried out by us, show the presence of an ETT in this pressure range. The obtained results suggest that the ETT is related with the decrease of the intralayer angles TeBiTe, and intra- and interlayer distance TeTe. Experimental results describing the pressure dependence the thermoelectric power, electrical resistivity, and power fator for rhombohedral Bi2Te3 are reported, and an enhancement of the power factor in the 1.1 to 6.3 GPa range is observed. The results obtained in this study give evidence that this enhancement in the power factor is related with the decrease of the intralayer angles TeBiTe, and with the decrease of intralayer- and interlayers homopolar TeTe bonds

Efeito do número de ordenhas diárias sobre o desempenho reprodutivo de vacas mestiças Holandês-Zebu.

Resumo: Avaliou-se a influência do número de ordenhas diárias sobre o desempenho reprodutivo de 63 vacas mestiças (Holandês-Zebu) com boa condição corporal ao parto, distribuídas em três grupos (G) experimentais: GI ? vacas ordenhadas uma vez ao dia; GII ? vacas ordenhadas duas vezes ao dia; GIII ? vacas ordenhadas alternadamente a cada 14 dias, uma ou duas vezes ao dia. O retorno ao estro (84,3 dias; 81,7 dias e 71,2 dias); a taxa de manifestação de estro (80,9%; 80,90% e 80,90%); o período de serviço (99,0 dias; 114,0 dias e 93,1 dias) e a taxa de gestação até 120 dias pós-parto (66,7%; 57,1%; 66,7%) não foram influenciados (P>0,05) pelo aumento do número de ordenhas diárias. [Effect of the number of daily milking on reproductive performance of crossbred (Holtein x Zebu) cows]. Abstract: This study was carried out to evaluate the influence of the number of daily milking on reproductive performance of 63 crossbred (Holstein-Zebu) cows, with good body condition score at calving, allocatted into three groups (G) according the number of daily milking: GI ? cows milked once a day; GII ? cows milked twice a day; GIII - cows milked alternating once or twice a day, every fourteen days. The return to estrous (84.3 days; 81.7 days and 71.2 days); estrous rates (80.9%; 80.90% e 80.90%); service period (99.0 days; 114.0 days and 93.1 days) and pregnant rates until 120 day postpartum (66.7%; 57.1%; 66.7%) were not influenced (P>0.05) by the number of daily milkin