Influence of carbon nanoparticles/epoxy matrix interaction on mechanical, electrical and transport properties of structural advanced materials.

The focus of this study is to design new nano-modified epoxy formulations using carbon nanofillers, such as carbon nanotubes, carbon nanofibers and graphene-based nanoparticles (CpEG), that reduce the moisture content and provide additional functional performance. The chemical structure of epoxy mixture, using a non-stoichiometric amount of hardener, exhibits unique properties in regard to the water sorption for which the equilibrium concentration of water (C eq) is reduced up to a maximum of 30%. This result, which is very relevant for several industrial applications (aeronautical, shipbuilding industries, wind turbine blades, etc), is due to a strong reduction of the polar groups and/or sites responsible to bond water molecules. All nanofillers are responsible of a second phase at lower glass transition temperature (Tg). Compared with other carbon nanofillers, functionalized graphene-based nanoparticles exhibit the best performance in the multifunctionality. The lowest moisture content, the high performance in the mechanical properties, the low electrical percolation threshold (EPT) have been all ascribed to particular arrangements of the functionalized graphene sheets embedded in the polymeric matrix. Exfoliation degree and edge carboxylated groups are responsible of self-assembled architectures which entrap part of the resin fraction hindering the interaction of water molecules with the polar sites of the resin, also favouring the EPT paths and the attractive/covalent interactions with the matrix.

Elucidating the molecular physiology of lantibiotic NAI-107 production in Microbispora ATCC-PTA-5024.

BACKGROUND: The filamentous actinomycete Microbispora ATCC-PTA-5024 produces the lantibiotic NAI-107, which is an antibiotic peptide effective against multidrug-resistant Gram-positive bacteria. In actinomycetes, antibiotic production is often associated with a physiological differentiation program controlled by a complex regulatory and metabolic network that may be elucidated by the integration of genomic, proteomic and bioinformatic tools. Accordingly, an extensive evaluation of the proteomic changes associated with NAI-107 production was performed on Microbispora ATCC-PTA-5024 by combining two-dimensional difference in gel electrophoresis, mass spectrometry and gene ontology approaches. RESULTS: Microbispora ATCC-PTA-5024 cultivations in a complex medium were characterized by stages of biomass accumulation (A) followed by biomass yield decline (D). NAI-107 production started at 90 h (A stage), reached a maximum at 140 h (D stage) and decreased thereafter. To reveal patterns of differentially represented proteins associated with NAI-107 production onset and maintenance, differential proteomic analyses were carried-out on biomass samples collected: i) before (66 h) and during (90 h) NAI-107 production at A stage; ii) during three time-points (117, 140, and 162 h) at D stage characterized by different profiles of NAI-107 yield accumulation (117 and 140 h) and decrement (162 h). Regulatory, metabolic and unknown-function proteins, were identified and functionally clustered, revealing that nutritional signals, regulatory cascades and primary metabolism shift-down trigger the accumulation of protein components involved in nitrogen and phosphate metabolism, cell wall biosynthesis/maturation, lipid metabolism, osmotic stress response, multi-drug resistance, and NAI-107 transport. The stimulating role on physiological differentiation of a TetR-like regulator, originally identified in this study, was confirmed by the construction of an over-expressing strain. Finally, the possible role of cellular response to membrane stability alterations and of multi-drug resistance ABC transporters as additional self-resistance mechanisms toward the lantibiotic was confirmed by proteomic and confocal microscopy experiments on a Microbispora ATCC-PTA-5024 lantibiotic-null producer strain which was exposed to an externally-added amount of NAI-107 during growth. CONCLUSION: This study provides a net contribution to the elucidation of the regulatory, metabolic and molecular patterns controlling physiological differentiation in Microbispora ATCC-PTA-5024, supporting the relevance of proteomics in revealing protein players of antibiotic biosynthesis in actinomycetes.

The Compass-like locus, exclusive to the Ambulacrarians, encodes a chromatin insulator binding protein in the sea urchin embryo.

Chromatin insulators are eukaryotic genome elements that upon binding of specific proteins display barrier and/or enhancer-blocking activity. Although several insulators have been described throughout various metazoans, much less is known about proteins that mediate their functions. This article deals with the identification and functional characterization in Paracentrotus lividus of COMPASS-like (CMPl), a novel echinoderm insulator binding protein. Phylogenetic analysis shows that the CMPl factor, encoded by the alternative spliced Cmp/Cmpl transcript, is the founder of a novel ambulacrarian-specific family of Homeodomain proteins containing the Compass domain. Specific association of CMPl with the boxB cis-element of the sns5 chromatin insulator is demonstrated by using a yeast one-hybrid system, and further corroborated by ChIP-qPCR and trans-activation assays in developing sea urchin embryos. The sns5 insulator lies within the early histone gene cluster, basically between the H2A enhancer and H1 promoter. To assess the functional role of CMPl within this locus, we challenged the activity of CMPl by two distinct experimental strategies. First we expressed in the developing embryo a chimeric protein, containing the DNA-binding domain of CMPl, which efficiently compete with the endogenous CMPl for the binding to the boxB sequence. Second, to titrate the embryonic CMPl protein, we microinjected an affinity-purified CMPl antibody. In both the experimental assays we congruently observed the loss of the enhancer-blocking function of sns5, as indicated by the specific increase of the H1 expression level. Furthermore, microinjection of the CMPl antiserum in combination with a synthetic mRNA encoding a forced repressor of the H2A enhancer-bound MBF1 factor restores the normal H1 mRNA abundance. Altogether, these results strongly support the conclusion that the recruitment of CMPl on sns5 is required for buffering the H1 promoter from the H2A enhancer activity, and this, in turn, accounts for the different level of accumulation of early linker and nucleosomal transcripts.

Specific expression of a TRIM-containing factor in ectoderm cells affects the skeletal morphogenetic program of the sea urchin embryo.

In the indirect developing sea urchin embryo, the primary mesenchyme cells (PMCs) acquire most of the positional and temporal information from the overlying ectoderm for skeletal initiation and growth. In this study, we characterize the function of the novel gene strim1, which encodes a tripartite motif-containing (TRIM) protein, that adds to the list of genes constituting the epithelial-mesenchymal signaling network. We report that strim1 is expressed in ectoderm regions adjacent to the bilateral clusters of PMCs and that its misexpression leads to severe skeletal abnormalities. Reciprocally, knock down of strim1 function abrogates PMC positioning and blocks skeletogenesis. Blastomere transplantation experiments establish that the defects in PMC patterning, number and skeletal growth depend upon strim1 misexpression in ectoderm cells. Furthermore, clonal expression of strim1 into knocked down embryos locally restores skeletogenesis. We also provide evidence that the Otp and Pax2/5/8 regulators, as well as FGFA, but not VEGF, ligand act downstream to strim1 in ectoderm cells, and that strim1 triggers the expression of the PMC marker sm30, an ectoderm-signaling dependent gene. We conclude that the strim1 function elicits specific gene expression both in ectoderm cells and PMCs to guide the skeletal biomineralization during morphogenesis.

Thermo-Mechanical and Thermo-Electric Properties of a Carbon-Based Epoxy Resin: An Experimental, Statistical, and Numerical Investigation.

Due to their remarkable intrinsic physical properties, carbon nanotubes (CNTs) can enhance mechanical properties and confer electrical and thermal conductivity to polymers currently being investigated for use in advanced applications based on thermal management. An epoxy resin filled with varying concentrations of CNTs (up to 3 wt%) was produced and experimentally characterized. The electrical percolation curve identified the following two critical filler concentrations: 0.5 wt%, which is near the electrical percolation threshold (EPT) and suitable for exploring mechanical and piezoresistive properties, and 3 wt% for investigating thermo-electric properties due to the Joule effect with applied voltages ranging from 70 V to 200 V. Near the electrical percolation threshold (EPT), the CNT concentration in epoxy composites forms a sparse, sensitive network ideal for deformation sensing due to significant changes in electrical resistance under strain. Above the EPT, a denser CNT network enhances electrical and thermal conductivity, making it suitable for Joule heating applications. Numerical models were developed using multiphysics simulation software. Once the models have been validated with experimental data, as a perfect agreement is found between numerical and experimental results, a simulation study is performed to investigate additional physical properties of the composites. Furthermore, a statistical approach based on the design of experiments (DoE) was employed to examine the influence of certain thermal parameters on the final performance of the materials. The purpose of this research is to promote the use of contemporary statistical and computational techniques alongside experimental methods to enhance understanding of materials science. New materials can be identified through these integrated approaches, or existing ones can be more thoroughly examined.

Nanoindentation Response of Structural Self-Healing Epoxy Resin: A Hybrid Experimental-Simulation Approach.

In recent years, self-healing polymers have emerged as a topic of considerable interest owing to their capability to partially restore material properties and thereby extend the product's lifespan. The main purpose of this study is to investigate the nanoindentation response in terms of hardness, reduced modulus, contact depth, and coefficient of friction of a self-healing resin developed for use in aeronautical and aerospace contexts. To achieve this, the bifunctional epoxy precursor underwent tailored functionalization to improve its toughness, facilitating effective compatibilization with a rubber phase dispersed within the host epoxy resin. This approach aimed to highlight the significant impact of the quantity and distribution of rubber domains within the resin on enhancing its mechanical properties. The main results are that pure resin (EP sample) exhibits a higher hardness (about 36.7% more) and reduced modulus (about 7% more), consequently leading to a lower contact depth and coefficient of friction (11.4% less) compared to other formulations that, conversely, are well-suited for preserving damage from mechanical stresses due to their capabilities in absorbing mechanical energy. Furthermore, finite element method (FEM) simulations of the nanoindentation process were conducted. The numerical results were meticulously compared with experimental data, demonstrating good agreement. The simulation study confirms that the EP sample with higher hardness and reduced modulus shows less penetration depth under the same applied load with respect to the other analyzed samples. Values of 877 nm (close to the experimental result of 876.1 nm) and 1010 nm (close to the experimental result of 1008.8 nm) were calculated for EP and the toughened self-healing sample (EP-R-160-T), respectively. The numerical results of the hardness provide a value of 0.42 GPa and 0.32 GPa for EP and EP-R-160-T, respectively, which match the experimental data of 0.41 GPa and 0.30 GPa. This validation of the FEM model underscores its efficacy in predicting the mechanical behavior of nanocomposite materials under nanoindentation. The proposed investigation aims to contribute knowledge and optimization tips about self-healing resins.

The role of carbon nanofiber defects on the electrical and mechanical properties of CNF-based resins.

Heat treatment of carbon nanofibers has proven to be an effective method in removing defects from carbon nanofibers, causing a strong increase in their structural perfection and thermal stability. It affects the bonding states of carbon atoms in the nanofiber structure and causes a significant transformation in the hybridization state of the bonded carbon atoms.Nanofilled resins made of heat-treated CNF show significant increases in their electrical conductivity even at low concentrations. This confirms that enhancement in the perfection of the fiber structure with consequent change in the morphological features plays a prominent role in affecting the electrical properties. Indeed heat-treated CNFs display a stiff structure and a smooth surface which tends to lower the thickness of the unavoidable insulating epoxy layer formed around the CNF which, in turn, plays a fundamental role in the electrical transport properties along the conducting clusters. This might be very beneficial in terms of electrical conductivity but might have negligible effect on the mechanical properties.

Special Issue: Thermo-Electric and Mechanical Properties of Carbon-Based Polymer.

Although on the one hand polymers are arousing increasing interest due to their remarkable properties in terms of lightness, cost-effectiveness, easy processing, and mechanical resistance, on the other hand, they still present several restrictions in practical applications [...].

Experimental, Theoretical and Numerical Studies on Thermal Properties of Lightweight 3D Printed Graphene-Based Discs with Designed Ad Hoc Air Cavities.

The current state of the art on material science emphasizes recent research efforts aimed at designing novel materials characterized by low-density and advanced properties. The present article reports the experimental, theoretical and simulation results on the thermal behavior of 3D printed discs. Filaments of pure poly (lactic acid) PLA and filled with 6 wt% of graphene nanoplatelets (GNPs) are used as feedstocks. Experiments indicate that the introduction of graphene enhances the thermal properties of the resulting materials since the conductivity passes from the value of 0.167 [W/mK] for unfilled PLA to 0.335 [W/mK] for reinforced PLA, which corresponds to a significantly improvement of 101%. Exploiting the potential of 3D printing, different air cavities have been intentionally designed to develop new lightweight and more cost-effective materials without compromising their thermal performances. Furthermore, some cavities are equal in volume but different in the geometry; it is necessary to investigate how this last characteristic and its possible orientations affect the overall thermal behavior compared to that of an air-free specimen. The influence of air volume is also investigated. Experimental results are supported by theoretical analysis and simulation studies based on the finite element method. The results aim to be a valuable reference resource in the field of design and optimization of lightweight advanced materials.

Conductivity in Thin Films of Transition Metal Coordination Complexes.

Two coordination complexes have been made by combining the dithiolene complexes [M(mnt)2]2- (mnt = maleonitriledithiolate; M = Ni2+ or Cu2+) as anion, with the copper(II) coordination complex [Cu(Stetra)] (Stetra = 6,6'-bis(4,5-dihydrothiazol-2-yl)-2,2'-bipyri-dine) as cation. The variation of the metal centers leads to a dramatic change in the conductivity of the materials, with the M = Cu2+ variant (Cu-Cu) displaying semiconductor behavior with a conductivity of approximately 2.5 × 10-8 S cm-1, while the M = Ni2+ variant (Ni-Cu) displayed no observable conductivity. Computational studies found Cu-Cu enables a minimization of reorganization energy losses and, as a result, a lower barrier to the charge transfer process, resulting in the reported higher conductivity.

Role of MWCNTs Loading in Designing Self-Sensing and Self-Heating Structural Elements.

This work proposes nanocomposites with carbon nanotubes characterized by self-sensing and self-heating properties. Recently, a growing interest in these two properties has been found in many industrial sectors, especially in the aerospace and automotive fields. While the self-sensing function allows diagnosing the presence of micro-damage in the material thanks to the detection of residual resistance, the self-heating function is exploited to properly tune the heating performance in terms of the heating rate and final temperature values. An electrical percolation value of around 0.5% by weight of carbon nanotubes was found by electrical characterization. The AC conductivity of the nanocomposites, in the range of 100 Hz to 1 MHz, evidences that beyond a CNTs amount of 0.5% wt/wt, they are characterized by a purely resistive behavior. The self-sensing analysis displayed a gauge factor value of 4.1. The solid thermal stability up to 300 °C makes the material suitable as a heating element at high temperatures. SEM investigations and temperature maps evidence a good dispersion of the conductive filler in the epoxy matrix and, consequently, good isotropy in heat distribution. As regards the trend of electrical resistance by varying the temperature, the electro-thermal investigation has shown the presence of both Positive Temperature Coefficient (PTC) and Negative Temperature Coefficient (NTC) behaviors with a predominance of NTC as soon as the temperature becomes closer to the glass transition temperature of the epoxy resin.

Advanced Nanomechanical Characterization of Biopolymer Films Containing GNPs and MWCNTs in Hybrid Composite Structure.

Nanomechanical definition of the properties of composite specimens based on polylactic acid (PLA) was made in the present study. Research activities with accent on biodegradable polymer nanocomposites have fundamental significance originated from the worldwide plastic waste pollution. To receive hybrid nanocomposites with high level of homogeneity, the low cost and environmentally friendly melt extrusion method has been applied. The role of graphene nanoplatelets (GNPs) and multiwall carbon nanotubes (MWCNTs) as reinforcing nanoparticles dispersed in the polymer matrix was thoroughly investigated. Quasi-static nanoindentation analysis was enriched by performance of accelerated property mapping and nanodynamic mechanical testing in order to fully describe the nanoscale surface homogeneity and stress relaxation behavior of the nanocomposite specimens. That novelty of the research approach had a well-marked contribution over the detection of the new samples' nanomechanical features as a function of the type of carbon nanofiller. Refined nanoscratch experiments uncovered the resistance of the materials against notches by means of measurement of the coefficient of friction and accurate estimation of the residual penetration depth.

Experimental and Simulation Studies of Temperature Effect on Thermophysical Properties of Graphene-Based Polylactic Acid.

Overheating effect is a crucial issue in different fields. Thermally conductive polymer-based heat sinks, with lightweight and moldability features as well as high-performance and reliability, are promising candidates in solving such inconvenience. The present work deals with the experimental evaluation of the temperature effect on the thermophysical properties of nanocomposites made with polylactic acid (PLA) reinforced with two different weight percentages (3 and 6 wt%) of graphene nanoplatelets (GNPs). Thermal conductivity and diffusivity, as well as specific heat capacity, are measured in the temperature range between 298.15 and 373.15 K. At the lowest temperature (298.15 K), an improvement of 171% is observed for the thermal conductivity compared to the unfilled matrix due to the addition of 6 wt% of GNPs, whereas at the highest temperature (372.15 K) such enhancement is about of 155%. Some of the most important mechanical properties, mainly hardness and Young's modulus, maximum flexural stress, and tangent modulus of elasticity, are also evaluated as a function of the GNPs content. Moreover, thermal simulations based on the finite element method (FEM) have been carried out to predict the thermal performance of the investigated nanocomposites in view of their practical use in thermal applications. Results seem quite suitable in this regard.

Promoter activity of the sea urchin (Paracentrotus lividus) nucleosomal H3 and H2A and linker H1 {alpha}-histone genes is modulated by enhancer and chromatin insulator.

Core promoters and chromatin insulators are key regulatory elements that may direct a transcriptional enhancer to prefer a specific promoter in complex genetic loci. Enhancer and insulator flank the sea urchin (Paracentrotus lividus) alpha-histone H2A transcription unit in a tandem repeated cluster containing the five histone genes. This article deals with the specificity of interaction between the H2A enhancer-bound MBF-1 activator and histone gene promoters, and with the mechanism that leads the H1 transcripts to peak at about one-third of the value for nucleosomal H3 and H2A mRNAs. To this end, in vivo competition assays of enhancer and insulator functions were performed. Our evidence suggests that the MBF-1 transcription factor participates also in the expression of the H3 gene and that the sns5 insulator buffers the downstream H1 promoter from the H2A enhancer. Altogether, these results provide a clear demonstration of the enhancer-blocking function of a chromatin insulator in a natural gene context. In addition, they suggest that both the H2A enhancer and the sns5 insulator may account for the diverse accumulation of the linker H1 versus the core nucleosomal histones during early development of the sea urchin embryo.

Clinical effectiveness of a highly standardized and bioavailable mixture of flavonoids and triterpenes in the management of acute hemorroidal crisis.

BACKGROUND AND AIM OF THE WORK: Patients with acute haemorrhoidal crisis often need of an immediate and effective pharmacological approach to alleviate their pain, bleeding and swelling or have to be referred by the general practitioner to the surgeon for a definitive treatment. Effective and not invasive treatment control of the acute crisis could be of practical use in order to avoid or to delay invasive procedures to a time more convenient for the patient and/or for the surgeon. METHODS: After enrolling, according to the group treatment, every patient starts taking 1 tablet every 8 hours for 7 days of Emospid or 2 tablets every 8 hours for 7 days of MMDH tablets. According to a simplified PATE 2000 classification, the following parameters were evaluated: haemorrhoidal grade, internal and external haemorrhoids, internal and external oedema, internal and external thrombosis, bleeding, bleeding intensity, pain, itching, defecation problems and urgency, tenesm, mucus in stools and sphinterial tone. RESULTS: In the Emospid group, within the considered period, 35 patients out 40 shift downwards of 1 grade of the haemorrhoidal scale (from III to II and from II to I); 22 out of 29 stop bleeding; bleeding intensity drops by about 90%; pain ceased in 33 out of38; pain intensity drops by about 75%; itching ceased in 25 out 35; tenesm ceased in 32 out of 33; sphinterial tone reduced from hypertonic to normal in 19 out 24; mucus in the stools was found in 3 out of 12; 12 out 35 still presented defecation disorders; defecation urgency was found in 2 out of 14; need to defecate in 2 times was found in 1 out of 17; acute events (external and/or internal oedema, external and/or internal thrombosis) was found in 10 out of 36. In the MDHH group results were, in terms of global evaluation, inferior of about 25-50% according to the considered parameter when compared with the one got by the Emospid treatment. CONCLUSIONS: Patients with acute haemorrhoidal crisis may be successfully treated with Emospid in order to avoid or to delay, if acute crisis relapsed, invasive procedures. Moreover, the treatment with Emospid shows to be more effective, if compared with MMDH, in counteracting acute haemorrhoidal crisis. (www.actabiomedica.it)

Experimental, Theoretical and Simulation Studies on the Thermal Behavior of PLA-Based Nanocomposites Reinforced with Different Carbonaceous Fillers.

Many research efforts have been directed towards enhancing the thermal properties of polymers, since they are classically regarded as thermal insulators. To this end, the present study focuses on the thermal investigation of poly(lactic acid) (PLA) filled with two types of carbon nanotubes (trade names: TNIMH4 and N7000), two type of graphene nanoplatelets (trade names: TNIGNP and TNGNP), or their appropriate combination. A significant increase in the thermal conductivity by 254% with respect to that of unfilled polymer was achieved in the best case by using 9 wt% TNIGNP, resulting from its favorable arrangement and the lower thermal boundary resistance between the two phases, matrix and filler. To theoretically assist the design of such advanced nanocomposites, Design of Experiments (DoE) and Response Surface Method (RSM) were employed, respectively, to obtain information on the conditioning effect of each filler loading on the thermal conductivity and to find an analytical relationship between them. The numerical results were compared with the experimental data in order to confirm the reliability of the prediction. Finally, a simulation study was carried out with Comsol Multiphysics® for a comparative study between two heat sinks based on pure PLA, and to determine the best thermally performing nanocomposite with a view towards potential use in heat transfer applications.

The sea urchin sns5 insulator protects retroviral vectors from chromosomal position effects by maintaining active chromatin structure.

Silencing and position-effect (PE) variegation (PEV), which is due to integration of viral vectors in heterochromatin regions, are considered significant obstacles to obtaining a consistent level of transgene expression in gene therapy. The inclusion of chromatin insulators into vectors has been proposed to counteract this position-dependent variegation of transgene expression. Here, we show that the sea urchin chromatin insulator, sns5, protects a recombinant gamma-retroviral vector from the negative influence of chromatin in erythroid milieu. This element increases the probability of vector expression at different chromosomal integration sites, which reduces both silencing and PEV. By chromatin immunoprecipitation (ChIP) analysis, we demonstrated the specific binding of GATA1 and OCT1 transcription factors and the enrichment of hyperacetylated nucleosomes to sns5 sequences. The results suggest that this new insulator is able to maintain a euchromatin state inside the provirus locus with mechanisms that are common to other characterized insulators. On the basis of its ability to function as barrier element in erythroid milieu and to bind the erythroid specific factor GATA1, the inclusion of sns5 insulator in viral vectors may be of practical benefit in gene transfer applications and, in particular, for gene therapy of erythroid disorders.

Damage Monitoring of Structural Resins Loaded with Carbon Fillers: Experimental and Theoretical Study.

In the present study, nanocomposite materials for structural applications with self-sensing properties are proposed. In particular, suitable processing of epoxy resins filled with carbon nanotubes and expanded graphite characterized by very different aspect ratio leads to nanocomposite systems with high glass transition temperatures and remarkable values of the gauge factor. In particular, this notable property ranges between four, for composites filled with one-dimensional nanofiller, and 39 for composites with two-dimensional (2D) graphite derivatives. The greater sensitivity of the 2D system against permanent deformations is interpreted on the basis of an empirical mathematical model and morphological descriptions. The larger inter-contact area among the graphite layers determines a larger contact resistance change than that occurring among carbon nanotubes. The proposed systems turn out to be very advantageous in strain-sensor applications where damage detection is a key requirement to guarantee the reliability of the structures and the safety of the end-users.

Dielectric Spectroscopy and Thermal Properties of Poly(lactic) Acid Reinforced with Carbon-Based Particles: Experimental Study and Design Theory.

In the present study, polylactic acid (PLA) enriched with carbonaceous particles like multi-walled carbon nanotubes (MWCNTs), graphene nanoplates (GNPs) or a combination of both up 12 wt % of loading are used for producing 3D-printed specimens with fused deposition modeling (FDM) technology which are then experimentally and theoretically investigated. The goal is to propose a non-conventional filaments indicated for additive manufacturing process with improved dielectric and thermal properties, compared to the performances exhibited by the unfilled polymer. In the light of the above, a wide dielectric spectroscopy and a thermal analysis, supported by a morphological investigation, are performed. The results highlight that the introduction of 1-dimensional filler (MWCNTs) are more suitable for improving the dielectric properties of the resulting materials, due to the enhancement of the interfacial polarization and the presence of functionalized groups, whereas 2-dimensional nanoparticles (GNPs) better favor the thermal conduction mechanisms thanks to the lower thermal boundary resistance between the two phases, polymer/filler. In particular, with a loading of 12 wt % of MWCNTs the relative permittivity reaches the value of 5.35 × 103 much greater than that of 3.7 measured for unfilled PLA while for the thermal conductivity the enhancement with 12 wt % of GNPs is about 261% respect the thermal behavior of the neat polymer. The experimental results are correlated to theoretical findings, whereas a design of experiment (DoE) approach is adopted for investigating how the different fillers influence the dielectric and thermal performances of the 3D-printed parts, thus assisting the design of such innovative materials that appear promising for development and applications in the electromagnetic (EM) field and heat transfer.

Composition and geographic variation of the bacterial microbiota associated with the coelomic fluid of the sea urchin Paracentrotus lividus.

In the present work, culture-based and culture-independent investigations were performed to determine the microbiota structure of the coelomic fluid of Mediterranean sea urchin Paracentrotus lividus individuals collected from two distinct geographical sites neighboring a high-density population bay and a nature reserve, respectively. Next Generation Sequencing analysis of 16S rRNA gene (rDNA) showed that members of the Proteobacteria, Bacteroidetes and Fusobacteria phyla, which have been previously reported to be commonly retrieved from marine invertebrates, dominate the overall population of microorganisms colonizing this liquid tissue, with minority bacterial genera exhibiting remarkable differences among individuals. Our results showed that there is a correlation between microbiota structure and geographical location of the echinoderm collection site, highlighting over-representation of metagenomic functions related to amino acid and bioactive peptides metabolism in specimens inhabiting the nature reserve. Finally, we also described the developmental delay and aberrations exhibited by sea urchin embryos exposed to distinct bacterial isolates, and showed that these defects rely upon hydrophilic compound(s) synthesized by the bacterial strains assayed. Altogether, our findings lay the groundwork to decipher the relationships of bacteria with sea urchins in their aquatic environment, also providing an additional layer of information to understand the biological roles of the coelomic fluid.