An acoustic metamaterial lens for acoustic point-to-point communication in air

Acoustic metamaterials have become a novel and effective way to control sound waves and design acoustic devices. In this study, we design a 3D acoustic metamaterial lens (AML) to achieve point-to-point acoustic communication in air: any acoustic source (i.e. a speaker) in air enclosed by such an AML can produce an acoustic image where the acoustic wave is focused (i.e. the field intensity is at a maximum, and the listener can receive the information), while the acoustic field at other spatial positions is low enough that listeners can hear almost nothing. Unlike a conventional elliptical reflective mirror, the acoustic source can be moved around inside our proposed AML. Numerical simulations are given to verify the performance of the proposed AML

In Vitro Selection of mRNA Display Libraries Containing an Unnatural Amino Acid

The incorporation of unnatural amino acid into selectable, amplifiable peptide and protein libraries expands the chemical diversity of such libraries, thus considerably facilitating the process of obtaining ligands with improved properties (affinity, specificity, and function), particularly against therapeutically interesting targets. Here, we report that biocytin, a biotin derivative of lysine, can be inserted into an mRNA−protein fusion molecule through amber stop codon suppression. We also demonstrate that templates containing the codon corresponding to the biocytin tRNA (a UAG stop codon) can be enriched by iterative cycles of selection against a streptavidin agarose matrix

Synaptic Behavior in Metal Oxide-Based Memristors

With the end of Moore’s law in sight, new computing paradigms are needed to fulfill the increasing demands on data and processing potentials. Inspired by the operation of the human brain, from the dimensionality, energy and underlying functionalities, neuromorphic computing systems that are building upon circuit elements to mimic the neurobiological activities are good concepts to meet the challenge. As an important factor in a neuromorphic computer, electronic synapse has been intensively studied. The utilization of transistors, atomic switches and memristors has been proposed to perform synaptic functions. Memristors, with several unique properties, are exceptional candidates for emulating artificial synapses and thus for building artificial neural networks. In this paper, metal oxide-based memristor synapses are reviewed, from materials, properties, mechanisms, to architecture. The synaptic plasticity and learning rules are described. The electrical switching characteristics of a variety of metal oxide-based memristors are discussed, with a focus on their application as biological synapses

Network-guided genome-wide studies reveal a complex genetic architecture of warfarin resistance in the Norway rat (Rattus norvegicus)

A fundamental challenge in evolutionary biology and medical genetic research is to connect the phenotype (a disease in humans or an adaptive trait in animals or plants) with the genotype. Using a classical example of an adaptive trait with a strong Mendelian genetic basis - warfarin resistance in the Norway rat (Rattus norvegicus), my dissertation tests the main hypothesis that speculated ‘simple’ adaptive trait has a more complex genetic architecture. Warfarin is an anticoagulant rodenticide used since the 1950s, and also is a widely prescribed blood-thinning drug in human. As a rodenticide, warfarin has initially been very effective. However, resistant rodents have evolved quickly and Vkorc1 (vitamin K epoxide reductase complex subunit 1) is the known resistance gene. As a popular drug, warfarin has a narrow therapeutic window with several genes VKORC1, CYP2C9, CYP4F2 established as biomarkers predicting warfarin dose in humans, suggesting a complex genetic architecture of warfarin resistance in rodents. In my thesis I performed network-guided genomic association studies (NetGWAS) and gene expression analysis to identify candidate genes involved in warfarin resistance based on a sample of ~600 wild rats from 19 populations in Germany. My thesis work revealed that the resistance mutation in Vkorc1 likely is under balancing selection and was recently introduced to the rat population in our study area. A key innovation of my thesis is adopting a NetGWAS approach to prioritize true associations and conducting co-expression network analysis to detect expression changes related to warfarin. My work shows that additional candidate genes are connected to the vitamin K pathway of which Vkorc1 is an essential component. While the validation of identified genes remains a challenge, the value of my thesis for future investigation is shown: one candidate gene Calu (Calumenin) is associated with warfarin resistance in multiple populations and is an essential part of the vitamin K cycle. Finally, my thesis briefly examines the genetics underlying a newly postulated cost of resistance, arterial calcification. This dissertation provides us an innovative framework in which we learned the genetic architecture of an adaptive trait in multiple dimensions: nucleotide or expression variation, genomic distribution and gene-gene interactions

Utjecaj dodatka ekstrakta maslačka, saharoze i starter kulture na viskoznost, sposobnost zadržavanja vode i pH jogurta

Dandelion extract is a traditional Chinese medicine and contains significant nutritional value. The aim of this study was to research the optimum fermentation conditions for dandelion addition to plain yogurt using a single factor experiments and orthogonal experiment. The results of the present study demonstrated that the addition of dandelion extract affected the viscosity, water-holding capacity and pH of yogurt. Optimized conditions for dandelion addition to plain yogurt based on viscosity, incubation time, pH and sensory score were 10 % sucrose, 0.3 % of the starter cultures, incubation time of 6.5 hours and 3 % dandelion extract. A new kind of dandelion yogurt with high viscosity, good water-holding capacity and good taste was prepared in this study.Ekstrakt maslačka je tradicionalni kineski lijek, a također ima i značajnu nutritivnu vrijednost. Cilj ovog istraživanja bio je ispitati optimalne uvjete fermentacije za dodavanje maslačka u jogurt korištenjem pojedinih faktorskih eksperimenata i ortogonalnog eksperimenta. Rezultati ove studije pokazali su da dodavanje ekstrakta maslačaka utječe na viskoznost, sposobnost zadržavanja vode i pH jogurta. Optimalni uvjeti za dodavanje maslačka u jogurt na temelju viskoznosti, vremena inkubacije, pH i senzorskog rezultata bili su 10 % saharoze, 0,3 % starter kulture, vrijeme inkubacije od 6,5 sati i dodatak 3 % ekstrakta maslačka. U ovoj studiji pripremljena je nova vrsta jogurta s dodatkom maslačka karakteriziranog visokom viskoznošću, dobrom sposobnošću zadržavanja vode i dobrim okusom

Functional and evolutionary correlates of gene constellations in the Drosophila melanogaster genome that deviate from the stereotypical gene architecture

<p>Abstract</p> <p>Background</p> <p>The biological dimensions of genes are manifold. These include genomic properties, (e.g., X/autosomal linkage, recombination) and functional properties (e.g., expression level, tissue specificity). Multiple properties, each generally of subtle influence individually, may affect the evolution of genes or merely be (auto-)correlates. Results of multidimensional analyses may reveal the relative importance of these properties on the evolution of genes, and therefore help evaluate whether these properties should be considered during analyses. While numerous properties are now considered during studies, most work still assumes the stereotypical solitary gene as commonly depicted in textbooks. Here, we investigate the <it>Drosophila melanogaster </it>genome to determine whether deviations from the stereotypical gene architecture correlate with other properties of genes.</p> <p>Results</p> <p>Deviations from the stereotypical gene architecture were classified as the following gene constellations: Overlapping genes were defined as those that overlap in the 5-prime, exonic, or intronic regions. Chromatin co-clustering genes were defined as genes that co-clustered within 20 kb of transcriptional territories. If this scheme is applied the stereotypical gene emerges as a rare occurrence (7.5%), slightly varied schemes yielded between ~1%-50%. Moreover, when following our scheme, paired-overlapping genes and chromatin co-clustering genes accounted for 50.1 and 42.4% of the genes analyzed, respectively. Gene constellation was a correlate of a number of functional and evolutionary properties of genes, but its statistical effect was ~1-2 orders of magnitude lower than the effects of recombination, chromosome linkage and protein function. Analysis of datasets on male reproductive proteins showed these were biased in their representation of gene constellations and evolutionary rate Ka/Ks estimates, but these biases did not overwhelm the biologically meaningful observation of high evolutionary rates of male reproductive genes.</p> <p>Conclusion</p> <p>Given the rarity of the solitary stereotypical gene, and the abundance of gene constellations that deviate from it, the presence of gene constellations, while once thought to be exceptional in large Eukaryote genomes, might have broader relevance to the understanding and study of the genome. However, according to our definition, while gene constellations can be significant correlates of functional properties of genes, they generally are weak correlates of the evolution of genes. Thus, the need for their consideration would depend on the context of studies.</p

On the hydraulic fracturing in naturally-layered porous media using the phase field method

In the hydraulic fracturing of natural rocks, understanding and predicting crack penetrations into the neighboring layers is crucial and relevant in terms of cost-efficiency in engineering and environmental protection. This study constitutes a phase field framework to examine hydraulic fracture propagation in naturally-layered porous media. Biot's poroelasticity theory is used to couple the displacement and flow field, while a phase field method helps characterize fracture growth behavior. Additional fracture criteria are not required and fracture propagation is governed by the equation of phase field evolution. Thus, penetration criteria are not required when hydraulic fractures reach the material interfaces. The phase field method is implemented within a staggered scheme that sequentially solves the displacement, phase field, and fluid pressure. We consider the soft-to-stiff and the stiff-to-soft configurations, where the layer interface exhibits different inclination angles $\theta$. Penetration, singly-deflected, and doubly-deflected fracture scenarios can be predicted by our simulations. In the soft-to-stiff configuration, $\theta=0^\circ$ exhibits penetration or symmetrical doubly-deflected scenarios, and $\theta=15^\circ$ exhibits singly-deflected or asymmetric doubly-deflected scenarios. Only the singly-deflected scenario is obtained for $\theta=30^\circ$. In the stiff-to-soft configuration, only the penetration scenario is obtained with widening fractures when hydraulic fractures penetrate into the soft layer