We present a method to control the interfacial tension of a liquid alloy of gallium via electrochemical deposition (or removal) of the oxide layer on its surface. In sharp contrast with conventional ...surfactants, this method provides unprecedented lowering of surface tension (∼500 mJ/m ² to near zero) using very low voltage, and the change is completely reversible. This dramatic change in the interfacial tension enables a variety of electrohydrodynamic phenomena. The ability to manipulate the interfacial properties of the metal promises rich opportunities in shape-reconfigurable metallic components in electronic, electromagnetic, and microfluidic devices without the use of toxic mercury. This work suggests that the wetting properties of surface oxides—which are ubiquitous on most metals and semiconductors—are intrinsic “surfactants.” The inherent asymmetric nature of the surface coupled with the ability to actively manipulate its energetics is expected to have important applications in electrohydrodynamics, composites, and melt processing of oxide-forming materials.
Significance We present a method to control the interfacial energy of a liquid metal via electrochemical deposition (or removal) of an oxide layer on its surface. Unlike conventional surfactants, this approach can tune the interfacial tension of a metal significantly (from ∼7× that of water to near zero), rapidly, and reversibly using only modest voltages. These properties can be harnessed to induce previously unidentified electrohydrodynamic phenomena for manipulating liquid metal alloys based on gallium, which may enable shape-reconfigurable metallic components in electronic, electromagnetic, and microfluidic devices without the use of toxic mercury. The results also suggest that oxides—which are ubiquitous on most metals and semiconductors—may be harnessed to lower interfacial energy between dissimilar materials.
Comparison of Gaussian process modeling software Erickson, Collin B.; Ankenman, Bruce E.; Sanchez, Susan M.
European journal of operational research,
04/2018, Letnik:
266, Številka:
1
Journal Article
Recenzirano
Odprti dostop
•Eight software packages are used to fit Gaussian processes to various functions.•Comparisons are based on root-mean-square error of predictions over the input space.•Prediction error estimates are ...compared with the actual root-mean-square error.•Stark differences arise between packages even when using the same data and model.
Gaussian process fitting, or kriging, is often used to create a model from a set of data. Many available software packages do this, but we show that very different results can be obtained from different packages even when using the same data and model. We describe the parameterization, features, and optimization used by eight different fitting packages that run on four different platforms. We then compare these eight packages using various data functions and data sets, revealing that there are stark differences between the packages. In addition to comparing the prediction accuracy, the predictive variance – which is important for evaluating precision of predictions and is often used in stopping criteria – is also evaluated.
Abstract We provide field evidence that individuals engage in motivated optimism in the face of impending risk. Congruent with a dynamic anticipatory utility model, we demonstrate that belief ...distortions are time and stake dependent. Our study leverages variation in the time span between the survey and the externally imposed date when workers are required to return to their workplaces during the COVID-19 pandemic. We show that, as the work return date approaches, individuals become relatively more optimistic about the increased infection risk associated with going back to the workplace, and about how severely their health may be impacted if they get infected. Belief distortions are larger among those facing potential health complications conditional on infection. Our results are informative about when and for whom interventions will be most effective.
Aims
This experimental study focuses on survival and consistence of Vibrio parahaemolyticus in cold‐water sediments and how increasing temperature and nutritional availability can affect growth.
...Methods and Results
A pathogenic strain of V. parahaemolyticus was inoculated in seawater microcosms containing bottom sediment. Gradually, during 14 days, the temperature was upregulated from 8 to 21°C. Culturable V. parahaemolyticus was only found in the sediment but declined over time and did not recover even after another 2 days at 37°C. Numbers of culturable bacteria matched the amount found by q‐PCR indicating that they did not enter a dormant state, contrary to those in the water layer. After adding decaying phytoplankton as fertilizer to the microcosms of 8 and 21°C for 7 and 14 days, the culturability of the bacteria increased significantly in the sediments at both temperatures and durations of exposure.
Conclusion
The study showed that V. parahaemolyticus can stay viable in cold‐water sediment and growth was stimulated by fertilizers rather than by temperature.
Significance and Impact of the Study
Vibrio parahaemolyticus is a common cause of seafood‐borne gastroenteritis and is today recognized in connection to increasing ocean temperature. The results indicate that this pathogen should be considered a risk in well‐fertilized environments, such as aquacultures, even during cold periods.
Microbiome Assembly in Fermented Foods Louw, Nicolas L; Lele, Kasturi; Ye, Ruby ...
Annual review of microbiology,
09/2023, Letnik:
77, Številka:
1
Journal Article
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For thousands of years, humans have enjoyed the novel flavors, increased shelf-life, and nutritional benefits that microbes provide in fermented foods and beverages. Recent sequencing surveys of ...ferments have mapped patterns of microbial diversity across space, time, and production practices. But a mechanistic understanding of how fermented food microbiomes assemble has only recently begun to emerge. Using three foods as case studies (surface-ripened cheese, sourdough starters, and fermented vegetables), we use an ecological and evolutionary framework to identify how microbial communities assemble in ferments. By combining in situ sequencing surveys with in vitro models, we are beginning to understand how dispersal, selection, diversification, and drift generate the diversity of fermented food communities. Most food producers are unaware of the ecological processes occurring in their production environments, but the theory and models of ecology and evolution can provide new approaches for managing fermented food microbiomes, from farm to ferment.
As a general rule, plants defend against herbivores with multiple traits. The defense synergy hypothesis posits that some traits are more effective when co‐expressed with others compared to their ...independent efficacy. However, this hypothesis has rarely been tested outside of phytochemical mixtures, and seldom under field conditions. We tested for synergies between multiple defense traits of common milkweed (Asclepias syriaca) by assaying the performance of two specialist chewing herbivores on plants in natural populations. We employed regression and a novel application of random forests to identify synergies and antagonisms between defense traits. We found the first direct empirical evidence for two previously hypothesized defense synergies in milkweed (latex by secondary metabolites, latex by trichomes) and identified numerous other potential synergies and antagonisms. Our strongest evidence for a defense synergy was between leaf mass per area and low nitrogen content; given that these “leaf economic” traits typically covary in milkweed, a defense synergy could reinforce their co‐expression. We report that each of the plant defense traits showed context‐dependent effects on herbivores, and increased trait expression could well be beneficial to herbivores for some ranges of observed expression. The novel methods and findings presented here complement more mechanistic approaches to the study of plant defense diversity and provide some of the best evidence to date that multiple classes of plant defense synergize in their impact on insects. Plant defense synergies against highly specialized herbivores, as shown here, are consistent with ongoing reciprocal evolution between these antagonists.
Assay for transposase-accessible chromatin by sequencing (ATAC-seq) is rapidly becoming the assay of choice to investigate chromatin-mediated gene regulation, largely because of low input ...requirements, a fast workflow, and the ability to interrogate the entire genome in an untargeted manner. Many studies using ATAC-seq use mammalian or human-derived tissues, and established protocols work well in these systems. However, ATAC-seq is not yet widely used in Drosophila. Vinegar flies present several advantages over mammalian systems that make them an excellent model for ATAC-seq studies, including abundant genetic tools that allow straightforward targeting, transgene expression, and genetic manipulation that are not available in mammalian models. Because current ATAC-seq protocols are not optimized to use flies, we developed an optimized workflow that accounts for several complicating factors present in Drosophila. We examined parameters affecting nuclei isolation, including input size, freezing time, washing, and possible confounds from retinal pigments. Then, we optimized the enzymatic steps of library construction to account for the smaller Drosophila genome size. Finally, we used our optimized protocol to generate ATAC-seq libraries that meet ENCODE quality metrics. Our optimized protocol enables extensive ATAC-seq experiments in Drosophila, thereby leveraging the advantages of this powerful model system to understand chromatin-mediated gene regulation.
Overcoming Rayleigh–Plateau instabilities Song, Minyung; Kartawira, Karin; Hillaire, Keith D. ...
Proceedings of the National Academy of Sciences - PNAS,
08/2020, Letnik:
117, Številka:
32
Journal Article
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Liquids typically form droplets when exiting a nozzle. Jets—cylindrical streams of fluid—can form transiently at higher fluid velocities, yet interfacial tension rapidly drives jet breakup into ...droplets via the Rayleigh–Plateau instability. Liquid metal is an unlikely candidate to form stable jets since it has enormous interfacial tension and low viscosity. We report that electrochemical anodization significantly lowers the effective tension of a stream of metal, transitioning it from droplets to long (long lifetime and length) wires with 100-μm diameters without the need for high velocities. Whereas surface minimization drives Rayleigh–Plateau instabilities, these streams of metal increase in surface area when laid flat upon a surface due to the low tension. The ability to tune interfacial tension over at least three orders of magnitude using modest potential (<1 V) enables new approaches for production of metallic structures at room temperature, on-demand fluid-in-fluid structuring, and new tools for studying and controlling fluid behavior.
Gene regulation is critical for proper cellular function. Next-generation sequencing technology has revealed the presence of regulatory networks that regulate gene expression and essential cellular ...functions. Studies investigating the epigenome have begun to uncover the complex mechanisms regulating transcription. Assay for transposase-accessible chromatin by sequencing (ATAC-seq) is quickly becoming the assay of choice for many epigenomic investigations. However, whether intervention-mediated changes in accessible chromatin determined by ATAC-seq can be harnessed to generate intervention-inducible reporter constructs has not been systematically assayed.
We used the insulin signaling pathway as a model to investigate chromatin regions and gene expression changes using ATAC- and RNA-seq in insulin-treated Drosophila S2 cells. We found correlations between ATAC- and RNA-seq data, especially when stratifying differentially-accessible chromatin regions by annotated feature type. In particular, our data demonstrated a weak but significant correlation between chromatin regions annotated to enhancers (1-2 kb from the transcription start site) and downstream gene expression. We cloned candidate enhancer regions upstream of luciferase and demonstrate insulin-inducibility of several of these reporters.
Insulin-induced chromatin accessibility determined by ATAC-seq reveals enhancer regions that drive insulin-inducible reporter gene expression.
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