Patterns driven by combined AC and DC electric fields in nematic liquid crystals

The effect of superimposed ac and dc electric fields on the formation of electroconvection and flexoelectric patterns in nematic liquid crystals was studied. For selected ac frequencies an extended standard model of the electro-hydrodynamic instabilities was used to characterize the onset of pattern formation in the two-dimensional parameter space of the magnitudes of the ac and dc electric field components. Numerical as well as approximate analytical calculations demonstrate that depending on the type of patterns and on the ac frequency, the combined action of ac and dc fields may either enhance or suppress the formation of patterns. The theoretical predictions are qualitatively confirmed by experiments in most cases. Some discrepancies, however, seem to indicate the need to extend the theoretical description

A dieta corante interfere no resultado do clareamento dental? Uma revisão sistemática

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências da Saúde. Odontologia.Background: Evaluate, through a systematic review, the influence of staining food and beverages at the final outcome of the bleaching treatment in both techniques, In-home and In-office. Types of Studies Reviewes: This systematic review included in vivo, in situ and in vitro studies that evaluate the staining during or after tooth bleaching. The authors developed personalized search strategies at PubMed, LILACS, Web of Science, Scopus, EMBASE, Cochrane, in addition to the grey literature. The methodological quality was also evaluated with different tools. Results: Of the 480 articles, only 12 were included in the review. Two of them were in vivo, one in situ and nine in vitro. Most of them used the In-home technique, although three used the In-office technique. The staining solution used were tea, coffee, extract of acai, grape juice, red wine, cola based soft drink and melted chocolate. Conclusions and Practical Implications: Although more primary studies are needed, taking into account the included studies and the limitations of this study, we can recommend that staining food must be avoided at the In-office bleaching end, at the In-home, it is dispensable

Evaluation of Herbage Intake Estimation Methods for Dairy Cattle Grazing on Semi-Extensive Pastures

Available empirical and mechanistic models to estimate total dry matter intake (DMI) and pasture dry matter intake (PDMI) of grazing lactating dairy cows have mainly been developed under intensive grazing conditions. The objective was to evaluate the adequacy of such existent models for use under semi-extensive grazing conditions, characterised by semi-natural grassland and less intensive resource use. Feed intake of lactating cows was measured on three commercial organic dairy farms in South Germany during one or two 6-d-periods/farm in 2019. Each period, DMI was determined in 10 or 20 cows per farm from their daily faecal output measured using titanium dioxide as marker and the apparent total tract digestibility of ingested organic matter derived from faecal crude protein concentration. PDMI was then calculated by subtracting weighed DMI of supplement feeds from total DMI. Further, individual milk yield and body weight were recorded, and samples of milk, pasture forage, supplement feed, and faeces were taken. For further analysis, means of observed values per farm and period (n = 7) were used, resulting in a diverse dataset of grazing systems differing in supplement feeding, daily pasture allocation, cow breed, and PDMI. Two semi-mechanistic PDMI models and six empirical and two semi-mechanistic models to predict total DMI were evaluated by their Mean Squared Error of Prediction, Relative Prediction Error (RPE) and Concordance Correlation Coefficient. One PDMI model produced acceptable (RPE \u3c 20% of mean observed PDMI), and four total DMI models yielded satisfactory (RPE \u3c 10%) prediction accuracy, however yet at a moderate precision (greatest Pearson correlation coefficient = 0.73). To further specify the grazing conditions under which the models reach both, satisfactory precision and accuracy, and due to the low number of observations, data of the present study will be complemented with data gathered on more farms in Southwest Germany in 2020

Seasonality and Grazing Management Effect on Growth and Nutritional Composition of Herbage on Semi-Natural Grasslands Grazed by Dairy Cows in Southwest Germany

Natural and semi-natural grasslands represent an attractive forage source for cows in organic dairy farming. Throughout the grazing season, however, diverse factors such as climatic conditions, botanical composition, as well as grazing and herd management, can influence growth and nutritive value of forage on grasslands. We aimed at investigating the influence of seasonality and grazing management in forage growth and nutritional quality in seven commercial organic dairy cattle farms during the grazing season 2019 in South Germany. Therefore, forty exclusion cages (1 m2) were installed on pastures, which were under three different grazing systems: rotational, short-grass, and continuous grazing. Pasture herbage within and outside the cages was harvested every 4-6 weeks. The botanical composition of the pasture vegetation was estimated by visual observation, its sward height measured by a rising plate meter, and the aboveground biomass accumulation determined gravimetrically. Besides, air temperature and relative humidity were monitored by climate logger. Pasture samples inside and outside the cages were measured for dry matter (DM) according to the Association of German Agricultural Analytic and Research Institutes (VDLUFA) methods. Crude protein (CP), neutral-detergent (NDF), and acid-detergent (ADF) fibre of the samples were determined by near-infrared spectroscopy (NIRS). The forage biomass yield reached the growth peak in the second sampling (30.4 dt DM/ha) after 52 days. The CP concentrations outside the cages were greatest in late summer (166 g/ kg DM). While the ADF content outside the cages were greatest at the beginning of the grazing season (274 g/ kg DM). Besides, the CP content of the pastures was greatest under the short-grass system (193 g/kg DM) compared to the others systems. In conclusion, the seasonality influences the nutritional characteristics of the herbage, as well as the grazing management. However, the grazing management is influenced by other factors that are difficult to statistically measure

Associated bacteria affect sexual reproduction by altering gene expression and metabolic processes in a biofilm inhabiting diatom

Diatoms are unicellular algae with a fundamental role in global biogeochemical cycles as major primary producers at the base of aquatic food webs. In recent years, chemical communication between diatoms and associated bacteria has emerged as a key factor in diatom ecology, spurred by conceptual and technological advancements to study the mechanisms underlying these interactions. Here, we use a combination of physiological, transcriptomic, and metabolomic approaches to study the influence of naturally coexisting bacteria, Maribacter sp. and Roseovarius sp., on the sexual reproduction of the biofilm inhabiting marine pennate diatom Seminavis robusta. While Maribacter sp. severely reduces the reproductive success of S. robusta cultures, Roseovarius sp. slightly enhances it. Contrary to our expectation, we demonstrate that the effect of the bacterial exudates is not caused by altered cell-cycle regulation prior to the switch to meiosis. Instead, Maribacter sp. exudates cause a reduced production of diproline, the sexual attraction pheromone of S. robusta. Transcriptomic analyses show that this is likely an indirect consequence of altered intracellular metabolic fluxes in the diatom, especially those related to amino acid biosynthesis, oxidative stress response, and biosynthesis of defense molecules. This study provides the first insights into the influence of bacteria on diatom sexual reproduction and adds a new dimension to the complexity of a still understudied phenomenon in natural diatom populations

Sensoren-basiertes Entscheidungsunterstützungssystem für die bedarfsgerechte Zufütterung bei weidenden Milchkühen

Im Beitrag wird ein Entscheidungsunterstützungssystem für die Optimierung der Zufütterungsstrategien durch die Integration von sensoren-basierten Daten präsentiert. Dazu wurde eine bestehende Rationsgestaltungssoftware überarbeitet und durch zeitnah erfasste Weideparameterdaten ergänzt

Stickstoffnutzung weidender, laktierender Milchkühe auf ökologischen Milchviehbetrieben

Eine Herausforderung weidebasierter Milchproduktion ist eine variablere und generell geringere Stickstoffnutzungeffizienz. Daher wurde die Stickstoffnutzung von 323 Milchkühen für neun kommerzielle Bio-Milchviehbetriebe ausgewertet. Ihre mittlere Stickstoffnutzungseffizienz lag bei (24,7 ± 5,91 %)

„Abends wie ein Bettler“ gilt nicht für Kühe

Forscherinnen und Forscher haben sich gefragt: Wann und wie lange sollten Kühe auf der Weide sein, damit der Aufwuchs optimal ausgenutzt wird. Kauschlagsensoren und GPS-Daten lieferten erste Antworten: Vor allem abends fressen die Tiere besonders viel und lange

Initial Evaluation of AF78: a Rationally Designed Fluorine-18-Labelled PET Radiotracer Targeting Norepinephrine Transporter

Purpose Taking full advantage of positron emission tomography (PET) technology, fluorine-18-labelled radiotracers targeting norepinephrine transporter (NET) have potential applications in the diagnosis and assessment of cardiac sympathetic nerve conditions as well as the delineation of neuroendocrine tumours. However, to date, none have been used clinically. Drawbacks of currently reported radiotracers include suboptimal kinetics and challenging radiolabelling procedures. Procedures We developed a novel fluorine-18-labelled radiotracer targeting NET, AF78, with efficient one-step radiolabelling based on the phenethylguanidine structure. Radiosynthesis of AF78 was undertaken, followed by validation in cell uptake studies, autoradiography, and in vivo imaging in rats. Results [18F]AF78 was successfully synthesized with 27.9 ± 3.1 % radiochemical yield, > 97 % radiochemical purity and > 53.8 GBq/mmol molar activity. Cell uptake studies demonstrated essentially identical affinity for NET as norepinephrine and meta-iodobenzylgaunidine. Both ex vivo autoradiography and in vivo imaging in rats showed homogeneous and specific cardiac uptake. Conclusions The new PET radiotracer [18F]AF78 demonstrated high affinity for NET and favourable biodistribution in rats. A structure-activity relationship between radiotracer structures and affinity for NET was revealed, which may serve as the basis for the further design of NET targeting radiotracers with favourable features

Molecular imaging-derived biomarker of cardiac nerve integrity — introducing high NET affinity PET probe 18F-AF78

Background: Radiolabeled agents that are substrates for the norepinephrine transporter (NET) can be used to quantify cardiac sympathetic nervous conditions and have been demonstrated to identify high-risk congestive heart failure (HF) patients prone to arrhythmic events. We aimed to fully characterize the kinetic profile of the novel (18)F-labeled NET probe AF78 for PET imaging of the cardiac sympathetic nervous system (SNS) among various species. Methods: (18)F-AF78 was compared to norepinephrine (NE) and established SNS radiotracers by employing in vitro cell assays, followed by an in vivo PET imaging approach with healthy rats, rabbits and nonhuman primates (NHPs). Additionally, chase protocols were performed in NHPs with NET inhibitor desipramine (DMI) and the NE releasing stimulator tyramine (TYR) to investigate retention kinetics in cardiac SNS. Results: Relative to other SNS radiotracers, (18)F-AF78 showed higher transport affinity via NET in a cell-based competitive uptake assay (IC(50) 0.42 ± 0.14 µM), almost identical to that of NE (IC(50), 0.50 ± 0.16 µM, n.s.). In rabbits and NHPs, initial cardiac uptake was significantly reduced by NET inhibition. Furthermore, cardiac tracer retention was not affected by a DMI chase protocol but was markedly reduced by intermittent TYR chase, thereby suggesting that (18)F-AF78 is stored and can be released via the synaptic vesicular turnover process. Computational modeling hypothesized the formation of a T-shaped π-π stacking at the binding site, suggesting a rationale for the high affinity of (18)F-AF78. Conclusion: (18)F-AF78 demonstrated high in vitro NET affinity and advantageous in vivo radiotracer kinetics across various species, indicating that (18)F-AF78 is an SNS imaging agent with strong potential to guide specific interventions in cardiovascular medicine