Gas injection into second mode instability on a 7 degree cone at Mach 7

The influence of injection gas type on second mode instabilities is researched on a 7 degree half-angle cone at Mach 7. The wind tunnel model of 594.5 mm length with a sharp nosetip is fitted with a porous aluminium patch that spans 60 degree in azimuth and 25 mm in axial length. Four different gases are injected into the boundary layer flow, namely nitrogen, carbon dioxide, helium and argon. Three different tunnel test conditions with different unit Reynolds numbers provide a variety of amplification levels of the second mode instability at the injection location. Frequency data is obtained using PCB sensors and the density boundary layer thickness is inferred from high speed z-type schlieren images. Early analysis of initial data shows a drop in second mode frequency and second mode power behind the injector. If transition is not caused the effect weakens further downstream. Higher blowing ratios caused a stronger decrease in frequency and also reduced the power in the frequency band more. Larger blowing ratios are required at lower unit Reynolds numbers to achieve the same effect. The observed boundary layer thickness, as inferred from schlieren images, followed comparable dynamics. A larger blowing ratio of the same coolant gas lead to more thickening, while Helium had a significantly stronger total effect than carbon dioxide. Preliminary results suggest that helium injection at a moderate rate causes the second mode peak to be disproportionally damped and its bandpower to be significantly reduced. A strongly simplified analytical model suggest that the mechanical increase in boundary layer thickness alone may not be sufficient to explain all observed outcomes

Coprophagous features in carnivorous Nepenthes plants: a task for ureases

Most terrestrial carnivorous plants are specialized on insect prey digestion to obtain additional nutrients. Few species of the genus Nepenthes developed mutualistic relationships with mammals for nitrogen supplementation. Whether dietary changes require certain enzymatic composition to utilize new sources of nutrients has rarely been tested. Here, we investigated the role of urease for Nepenthes hemsleyana that gains nitrogen from the bat Kerivoula hardwickii while it roosts inside the pitchers. We hypothesized that N. hemsleyana is able to use urea from the bats’ excrements. In fact, we demonstrate that 15N-enriched urea provided to Nepenthes pitchers is metabolized and its nitrogen is distributed within the plant. As ureases are necessary to degrade urea, these hydrolytic enzymes should be involved. We proved the presence and enzymatic activity of a urease for Nepenthes plant tissues. The corresponding urease cDNA from N. hemsleyana was isolated and functionally expressed. A comprehensive phylogenetic analysis for eukaryotic ureases, including Nepenthes and five other carnivorous plants’ taxa, identified them as canonical ureases and reflects the plant phylogeny. Hence, this study reveals ureases as an emblematic example for an efficient, low-cost but high adaptive plasticity in plants while developing a further specialized lifestyle from carnivory to coprophagy

Communally breeding bats use physiological and behavioural adjustments to optimise daily energy expenditure

Small endotherms must change roosting and thermoregulatory behaviour in response to changes in ambient conditions if they are to achieve positive energy balance. In social species, for example many bats, energy expenditure is influenced by environmental conditions, such as ambient temperature, and also by social thermoregulation. Direct measurements of daily fluctuations in metabolic rates in response to ambient and behavioural variables in the field have not been technologically feasible until recently. During different reproductive periods, we investigated the relationships between ambient temperature, group size and energy expenditure in wild maternity colonies of Bechstein’s bats (Myotis bechsteinii). Bats used behavioural and physiological adjustments to regulate energy expenditure. Whether bats maintained normothermia or used torpor, the number of bats in the roosts as well changed with reproductive status and ambient temperature. During pregnancy and lactation, bats remained mostly normothermic and daily group sizes were relatively large, presumably to participate in the energetic benefits of social thermoregulation. In contrast, smaller groups were formed on days when bats used torpor, which occurred mostly during the post-lactation period. Thus, we were able to demonstrate on wild animals under natural conditions the significance of behavioural and physiological flexibility for optimal thermoregulatory behaviour in small endotherms

Coprophagous features in carnivorous Nepenthes plants: A task for ureases

Most terrestrial carnivorous plants are specialized on insect prey digestion to obtain additional nutrients. Few species of the genus Nepenthes developed mutualistic relationships with mammals for nitrogen supplementation. Whether dietary changes require certain enzymatic composition to utilize new sources of nutrients has rarely been tested. Here, we investigated the role of urease for Nepenthes hemsleyana that gains nitrogen from the bat Kerivoula hardwickii while it roosts inside the pitchers. We hypothesized that N. hemsleyana is able to use urea from the bats' excrements. In fact, we demonstrate that 15N-enriched urea provided to Nepenthes pitchers is metabolized and its nitrogen is distributed within the plant. As ureases are necessary to degrade urea, these hydrolytic enzymes should be involved. We proved the presence and enzymatic activity of a urease for Nepenthes plant tissues. The corresponding urease cDNA from N. hemsleyana was isolated and functionally expressed. A comprehensive phylogenetic analysis for eukaryotic ureases, including Nepenthes and five other carnivorous plants' taxa, identified them as canonical ureases and reflects the plant phylogeny. Hence, this study reveals ureases as an emblematic example for an efficient, low-cost but high adaptive plasticity in plants while developing a further specialized lifestyle from carnivory to coprophagy

Conservation genetics of the pond bat (Myotis dasycneme) with special focus on the populations in northwestern Germany and in Jutland, Denmark

Conservation genetics is important in the management of endangered species, helping to understand their connectivity and long‐term viability, thus identifying populations of importance for conservation. The pond bat (Myotis dasycneme) is a rare species classified as “Near Threatened” with a wide but patchy Palearctic distribution. A total of 277 samples representing populations in Denmark, Germany, Latvia, Hungary, and Russia were used in the genetic analyses; 224 samples representing Denmark, Germany, and Russia were analyzed at 10 microsatellite loci; 241 samples representing all areas were analyzed using mitochondrial D‐loop and cytochrome B sequences. A Bayesian clustering approach revealed two poorly resolved clusters, one representing the Danish and German groups and the other the Russian group. However, significantly different pairwise FST and DEST estimates were observed between the Danish and German groups and between the Danish and Russian groups suggesting a recent population structure. These conflicting results might be attributed to the effect of migration or low resolution due to the number of microsatellite markers used. After concatenating the two mitochondrial sequences, analysis detected significant genetic differentiation between all populations, probably due to genetic drift combined with a founder event. The phylogenetic tree suggested a closer relationship between the Russian and Northern European populations compared to the Hungarian population, implying that the latter belongs to an older ancestral population. This was supported by the observed haplotype network and higher nucleotide diversity in this population. The genetic structuring observed in the Danish/German pond bat stresses the need for a cross‐border management between the two countries. Further, the pronounced mtDNA structuring, together with the indicated migration between nearby populations suggest philopatric female behavior but male migration, emphasizes the importance of protecting suitable habitat mosaics to maintain a continuum of patches with dense pond bat populations across the species' distribution range

Untargeted Metabolomics for Beef Flavor Beyond Fat in Ground Beef With Different Lean Sources and Different Fat Content From a Common Fat Source

To explore the effects of lean source on the flavor of ground beef patties, beef inside rounds (n=9) were procured from each of the following treatment groups: commodity upper two-thirds choice (HC; USDA modest and higher marbling), heart-healthy-branded (HEART), natural grass-fed (NATURAL), and commodity USDA Select (SELECT) beef. Rounds from each source were ground and supplemented with commercially sourced, pre-ground commodity fat trim to form treatment batches containing10% or 20% total fat. Batches were then fine-ground and formed into 113.5-g patties. Patties were vacuum packaged and frozen until analyzed. Trained sensory panel, fatty acid profile, volatile compound composition, and metabolomic features subsequently were analyzed. Lean source had no impact (P>0.05) on any major trained sensory traits, but patties with 20% fat had higher (P<0.05) fat-like, buttery, and juiciness scores. Patties made with HEART lean had the highest (P<0.05) monounsaturated fatty acids, and those from SELECT lean had the lowest. Those patties made with NATURAL lean and 20% fat tended (0.05<P<0.10) to have higher volatile concentrations of alcohol, aldehyde, ketones, and especially terpenoid compounds. Using discriminate analysis, metabolites (n=64 metabolites) from raw samples were accurately segregated by lean source only, while the cooked patties showed that the 138 metabolites were able to discriminate lean source for HC, HEART, and NATURAL within both 10% and 20% fat treatments. Patties made with SELECT lean clustered by themselves and generally had the opposite reaction to metabolite concentration as the other lean sources. Overall, while lean sources did not impact flavor, patties with different lean sources impacted the fatty acid content, volatile aroma compounds, and metabolite distribution in ground beef patties. Metabolomics may be another valuable tool to help describe meat quality, and it could be used to determine these traits in lean prior to sensory testing

Steak Thickness, Cook Surface Temperature and Quality Grade Affected Top Loin Steak Consumer and Descriptive Sensory Attributes

Beef flavor attributes of USDA Top Choice and Select beef top loin steaks were evaluated that differed in thickness (1.3 or 3.8 cm) and grill surface temperature (177 or 232°C) when cooked on a commercial flat top grill. A trained descriptive attribute panel and consumer sensory panels were used to evaluate steak flavor and texture. As thickness and temperature increased, beef identity and brown/roasted flavor aromatics increased (P < 0.05). Steaks cooked at 232°C and cut 3.8-cm thick had the highest (P < 0.05) levels of burnt flavor and bitter basic tastes. Thicker steaks cooked at 177°C had more intense umami basic taste and beef identity (P < 0.05). Steaks cut 1.3 cm had lower levels of beef identity and brown/roasted flavor aromatics and the thin cut steaks cooked at 177°C had more sour basic taste (P < 0.05). Consumers rated 232°C, 3.8 cm steaks lowest (P < 0.05) for overall, beef flavor, overall flavor, and grilled flavor liking; whereas, the 177°C, 3.8 cm steaks were highest (P < 0.05) in beef flavor liking. Beef identity, brown/roasted, bloody/serumy, fat-like, umami, sweet, salty, overall sweet, overall tenderness, and muscle fiber tenderness were positive attributes, and metallic, bitter, and burnt were negative attributes in predicting consumer overall liking. Thick steaks cooked at low temperatures or thin steaks cooked at high temperatures resulted in more positive sensory panel traits and consumer liking scores