Wavelet based approach to signal activity detection and phase picking: Application to acoustic emission

© 2015 Elsevier B.V. All rights reserved. Locating the sources of elastic waves during rapid local stress relaxation in solids under load is a central element in acoustic emission non-destructive testing, seismology, etc. The location problem relies heavily on the accuracy of arrival time detection. To increase the reliability of real time signal detection and to ensure precise phase picking of transient waveforms of a low amplitude, we propose a novel Wavelet transform-based algorithm. Benefiting strongly from the neighboring concepts in the wavelet theory, the shortcomings of conventional amplitude threshold-based and Short Term Average/Long Term Average methods are addressed. The proposed method was validated in a variety of acoustic emission tests, demonstrating the excellent temporal localization of the picked phases even for the signals with very low signal-to-noise ratio

Molecular Techniques Reveal Wide Phyletic Diversity of Heterotrophic Microbes Associated with Discodermia spp. (Porifera: Demospongiae)

Sponges are well known to harbor large numbers of heterotrophic microbes within their mesohyl. Studies to determine the diversity of these associated microbes have been attempted for only a few shallow water species. We cultured various microorganisms from several species of Discodermia collected from deep water using the \u27Johnson-Sea-Link\u27 manned submersibles, and characterised them by standard microbiological identification methods. Characterisation of a small proportion (ca. 10%) of the total and potential eubacterial isolate collection with molecular systematics techniques revealed a wide diversity of microbes. Phylogenetic analyses of 32 small subunit (SSU) 16S-like rRNA gene sequences from different micorbes indicated high levels of taxonomic diversity assoiated with this genus of sponge. For example, bacteria from at least five cubacterial subdivisions - gamma, alpha, beta, Cytophaga and Gram positive - were isolated from the mesohyl of Discodermia. Several strains were unidentifiable from current sequence databases. No overlap was found between sequences of 24 isolates and 8 sequences obtained by PCR and cloning directly from sponge samples. The abundance and diversity of microbes associated with sponges such as Discodermia suggest that they may play important roles in marine microbial ecology, dispersal and evolution

Breakthrough in marine invertebrate cell culture : Sponge cells divide rapidly in improved nutrient medium

Sponges (Phylum Porifera) are among the oldest Metazoa and considered critical to understanding animal evolution and development. They are also the most prolific source of marine-derived chemicals with pharmaceutical relevance. Cell lines are important tools for research in many disciplines, and have been established for many organisms, including freshwater and terrestrial invertebrates. Despite many efforts over multiple decades, there are still no cell lines for marine invertebrates. In this study, we report a breakthrough: we demonstrate that an amino acid-optimized nutrient medium stimulates rapid cell division in 9 sponge species. The fastest dividing cells doubled in less than 1 hour. Cultures of 3 species were subcultured from 3 to 5 times, with an average of 5.99 population doublings after subculturing, and a lifespan from 21 to 35 days. Our results form the basis for developing marine invertebrate cell models to better understand early animal evolution, determine the role of secondary metabolites, and predict the impact of climate change to coral reef community ecology. Furthermore, sponge cell lines can be used to scale-up production of sponge-derived chemicals for clinical trials and develop new drugs to combat cancer and other diseases.publishedVersio

Evolution of Group I Introns in Porifera: New Evidence for Intron Mobility and Implications for DNA Barcoding

BackgroundMitochondrial introns intermit coding regions of genes and feature characteristic secondary structures and splicing mechanisms. In metazoans, mitochondrial introns have only been detected in sponges, cnidarians, placozoans and one annelid species. Within demosponges, group I and group II introns are present in six families. Based on different insertion sites within the cox1 gene and secondary structures, four types of group I and two types of group II introns are known, which can harbor up to three encoding homing endonuclease genes (HEG) of the LAGLIDADG family (group I) and/or reverse transcriptase (group II). However, only little is known about sponge intron mobility, transmission, and origin due to the lack of a comprehensive dataset. We analyzed the largest dataset on sponge mitochondrial group I introns to date: 95 specimens, from 11 different sponge genera which provided novel insights into the evolution of group I introns. ResultsFor the first time group I introns were detected in four genera of the sponge family Scleritodermidae (Scleritoderma, Microscleroderma, Aciculites, Setidium). We demonstrated that group I introns in sponges aggregate in the most conserved regions of cox1. We showed that co-occurrence of two introns in cox1 is unique among metazoans, but not uncommon in sponges. However, this combination always associates an active intron with a degenerating one. Earlier hypotheses of HGT were confirmed and for the first time VGT and secondary losses of introns conclusively demonstrated. ConclusionThis study validates the subclass Spirophorina (Tetractinellida) as an intron hotspot in sponges. Our analyses confirm that most sponge group I introns probably originated from fungi. DNA barcoding is discussed and the application of alternative primers suggested

CRISPR/Cas12a-mediated gene editing in Geodia barretti sponge cell culture

Sponges and their associated microorganisms are the most prolific source of marine natural products, and many attempts have been made at creating a marine sponge cell line to produce these products efficiently. However, limited knowledge on the nutrients sponge cells require to grow and poor genetic accessibility have hampered progress toward this goal. Recently, a new sponge-specific nutrient medium M1 has been shown to stimulate sponge cells in vitro to divide rapidly. In this study, we demonstrate for the first time that sponge cells growing in M1 can be genetically modified using a CRISPR/Cas12a gene editing system. A short sequence of scrambled DNA was inserted using a single-stranded oligodeoxynucleotide donor template to disrupt the 2′,5′-oligoadenylate synthetase gene of cells from the boreal deep-sea sponge Geodia barretti. A blue fluorescent marker gene appeared to be inserted in an intron of the same gene and expressed by a small number of G. barretti cells. Our results represent an important step toward developing an optimized continuous sponge cell line to produce bioactive compounds.publishedVersio

Life cycle energy and carbon assessment of double skin façades for office refurbishments

In countries like the UK, the upkeep of existing buildings is where the greatest opportunities for achieving carbon reduction targets lie. Façades are the physical barriers between outdoors and indoors, and their upgrade can arguably be amongst the most effective interventions to improve the existing stock. Double Skin Façades (DSFs) represent a possible solution for low-carbon refurbishment due to their capability to reduce energy consumption, and the related carbon emissions, of the building they are applied to. Although much research exists on maximising the operational energy savings of DSFs, little is known about their life cycle performance. This article addresses such a knowledge gap through a comparative life cycle assessment between DSF refurbishments and an up-to-standard, single-skin alternative. This study adopts a parametric approach where 128 DSF configurations have been analysed through primary data. Energy and carbon (both operational and embodied) are the units assessed in this research. Results show that DSFs are more energy-efficient than single-skin in 98% of the cases, and more carbon-efficient in 85% of the cases. Not only does this study represent the first broad parametric approach to evaluating life cycle energy and carbon of DSFs within its given context, but it also informs environmentally-aware design and application of DSFs

The Deformation of Expanded Clay Syntactic Foams during Compression Characterized by Acoustic Emission

The deformation and failure mechanisms in syntactic foams with different metal matrices were investigated in this study. The syntactic foams were produced by the infiltration method using lightweight expanded clay particles (LECA) as a space holder and commercially pure Al or eutectic Al-12%Si alloy for the matrices. The samples were compressed at room temperature; simultaneously, the acoustic emission (AE) response and the surface deformation were monitored and collated with the deformation curves. In the case of the Al foam, ductile behavior with long plateau stress was observed. During this plateau regime, multiple active shear bands were detected. In contrast, the AlSi12 foam exhibited more brittle deformation behavior. At the end of the quasi-linear stage, the localization of the strain started within one large shear band, accompanied by a significant stress drop. The AE analysis revealed that the deformation was mostly governed by the fracture of LECA particles and the plastic deformation of the matrix material for both types of foams. After strain localization, in the case of the AlSi12 foam, the fracture of the matrix became significant, causing the deterioration of the sample. As for the Al foam, besides the fracture of the LECA particles, the plastic deformation of the matrix played an important role in preventing the foam from falling apart