Research opportunities on immunocompetence in space

The most significant of the available data on the effects of space flight on immunocompetences and the potential operational and clinical significance of reported changes are as follows: (1) reduced postflight blastogenic response of peripheral lymphocytes from space crew members; (2) postflight neutrophilia persisting up to 7 days; (3) gingival inflammation of the Skylab astronauts; (4) postflight lymphocytopenia, eosinopenia, and monocytopenia; (5) modifications and shifts in the microflora of space crews and spacecraft; and (6) microbial contamination of cabin air and drinking water. These responses and data disclose numerous gaps in the knowledge that is essential for an adequate understanding of space-related changes in immunocompetence

Synthetic control of a fitness tradeoff in yeast nitrogen metabolism

Background: Microbial communities are involved in many processes relevant to industrial and medical biotechnology, such as the formation of biofilms, lignocellulosic degradation, and hydrogen production. The manipulation of synthetic and natural microbial communities and their underlying ecological parameters, such as fitness, evolvability, and variation, is an increasingly important area of research for synthetic biology. Results: Here, we explored how synthetic control of an endogenous circuit can be used to regulate a tradeoff between fitness in resource abundant and resource limited environments in a population of Saccharomyces cerevisiae. We found that noise in the expression of a key enzyme in ammonia assimilation, Gdh1p, mediated a tradeoff between growth in low nitrogen environments and stress resistance in high ammonia environments. We implemented synthetic control of an endogenous Gdh1p regulatory network to construct an engineered strain in which the fitness of the population was tunable in response to an exogenously-added small molecule across a range of ammonia environments. Conclusion: The ability to tune fitness and biological tradeoffs will be important components of future efforts to engineer microbial communities

Pore-scale analysis of the minimum liquid film thickness around elongated bubbles in confined gas-liquid flows

© 2017 Elsevier Ltd The fluid mechanics of elongated bubbles in confined gas-liquid flows in micro-geometries is important in pore-scale flow processes for enhanced oil recovery and mobilization of colloids in unsaturated soil. The efficiency of such processes is traditionally related to the thickness of the liquid film trapped between the elongated bubble and the pore's wall, which is assumed constant. However, the surface of long bubbles presents undulations in the vicinity of the rear meniscus, which may significantly decrease the local thickness of the liquid film, thus impacting the process of interest. This study presents a systematic analysis of these undulations and the minimum film thickness induced in the range Ca=0.001-0.5 and Re=0.1-2000. Pore-scale Computational Fluid Dynamics (CFD) simulations are performed with a self-improved version of the opensource solver ESI OpenFOAM which is based on a Volume of Fluid method to track the gas-liquid interface. A lubrication model based on the extension of the classical axisymmetric Bretherton theory is utilized to better understand the CFD results. The profiles of the rear meniscus of the bubble obtained with the lubrication model agree fairly well with those extracted from the CFD simulations. This study shows that the Weber number of the flow, We=CaRe, is the parameter that best describes the dynamics of the interfacial waves. When We 0.1, a larger number of wave crests becomes evident on the surface of the rear meniscus of the bubble. The liquid film thickness at the crests of the undulations thins considerably as the Reynolds number is increased, down to less than 60% of the value measured in the flat film region. This may significantly influence important environmental processes, such as the detachment and mobilization of micron-sized pollutants and pathogenic micro-organisms adhering at the pore's wall in unsaturated soil

Design of small molecule-responsive microRNAs based on structural requirements for Drosha processing

MicroRNAs (miRNAs) are prevalent regulatory RNAs that mediate gene silencing and play key roles in diverse cellular processes. While synthetic RNA-based regulatory systems that integrate regulatory and sensing functions have been demonstrated, the lack of detail on miRNA structure–function relationships has limited the development of integrated control systems based on miRNA silencing. Using an elucidated relationship between Drosha processing and the single-stranded nature of the miRNA basal segments, we developed a strategy for designing ligand-responsive miRNAs. We demonstrate that ligand binding to an aptamer integrated into the miRNA basal segments inhibits Drosha processing, resulting in titratable control over gene silencing. The generality of this control strategy was shown for three aptamer–small molecule ligand pairs. The platform can be extended to the design of synthetic miRNAs clusters, cis-acting miRNAs and self-targeting miRNAs that act both in cis and trans, enabling fine-tuning of the regulatory strength and dynamics. The ability of our ligand-responsive miRNA platform to respond to user-defined inputs, undergo regulatory performance tuning and display scalable combinatorial control schemes will help advance applications in biological research and applied medicine

Buckling of orthotropic webs in process machinery

Many webs in web process machinery exhibit out-of-plane deformations, defined as troughs, in free web spans between rollers. In other cases when the troughs become severe the out-of-plane web deformations will begin to transcend rollers. Any out-of-plane web deformations that transcend rollers are defined as wrinkles. Troughs and wrinkles in webs are often undesirable as they can interfere with web processes such as coating, they can result in web breaks and thereby decreased productivity, or these deformations may become permanent and result in quality loss.Many plastic film, paper, tissue and nonwoven webs are highly anisotropic either by design or just as a result of the process by which the web is made. The first objective of this paper is to show how anisotropic web properties affect the buckling and wrinkling tendencies of these webs. Previously algorithms have been developed that show how roller misalignment can induce troughs and wrinkles. The second objective of this paper is to demonstrate how web orthotrophy can affect the allowable roller misalignment in a web span and the web tension required to sustain a wrinkle upon a roller.Mechanical and Aerospace Engineerin

Analysis of trough formation and lateral steering of a web due to a tapered downstream roller

Cylindrical rollers are never perfectly cylindrical. A common defect of a cylindrical roller is radial taper. A roller with a radial taper will induce a lateral shear force into the web. This shear force will cause a steering effect as well as a cross machine direction compressive stress which can lead to the formation of troughs and wrinkles in a web. This publication addresses these topics and presents a model to help determine the specification for taper in "cylindrical" rollers. An analytical model is presented, experiments were performed, and the data was compared to predictions from the proposed model.Mechanical and Aerospace Engineerin

Predicting web wrinkles on rollers

There are two levels of web instability in web lines. The first level of web instability is called web troughs. Web troughs are due to the instability of webs that occur in free web spans. Web troughs have been shown to be predictable using traditional buckling theory. Closed form expressions have been developed and verified in the lab that predict when web troughs will result from roller misalignment and roller taper. Web troughs can be a nuisance in web processes where the web must be planar. The troughs themselves may not damage the web but can be responsible for reductions in web quality after processing that can result in lost profit.The next level of instability is called web wrinkles. Web wrinkles are due to the instability of webs that are transiting rollers. When webs transit rollers they assume the shape of a sector of a cylindrical shell. A cylindrical shell of web is much more stable than the web in free spans. Compressive stresses which are two to three orders of magnitude larger than those required to induce web troughs are necessary to buckle the cylindrical shell. This paper will demonstrate that web wrinkles are a post buckling phenomena that result from web troughs. The source of the high compressive stresses needed to buckle the web into wrinkles on rollers will be shown. We will show how web wrinkles can be predicted and we will show experimental verification for the cases where a misaligned or tapered rollers were the source of the troughs and wrinkles. Web wrinkles can damage the web as a result of inelastic deformation, fold-overs, and in the worst case may cause full separation or failure of the web. When web wrinkles can be predicted, they can also be prevented.Mechanical and Aerospace Engineerin

Methods for analyzing deep sequencing expression data: constructing the human and mouse promoterome with deepCAGE data

A set of methods is presented for normalization, quantification of noise and co-expression analysis for gene expression studies using deep sequencing