UV-Curing Additive Manufacturing of Bio-Based Thermosets: Effect of Diluent Concentration on Printing and Material Properties of Itaconic Acid-Based Materials

In the quest toward sustainable thermosets, researchhas been conductedon various polymer classes like epoxy, benzoxazines, acryl-/methacrylates,etc. One particular group that can also be utilized as sustainableinks for additive manufacturing is itaconic acid-based unsaturatedpolyester resins. However, due to increased viscosity of the resins,the use of reactive diluents is required to increase their processability.While research has focused on creating different polymeric structuresto expand the possible applications, the required amount of diluenthas not received equal attention. In this work, a group of itaconicacid-based polyesters was synthesized to create a series of formulationswith different reactive diluent contents. The physicochemical propertiesof the prepared formulations, along with their reactivity toward UVlight, were assessed via photo-differential scanning calorimetry (photo-DSC),real-time attenuated total reflectance (RT-ATR), and photorheologymeasurements. The same formulations were then used to fabricate testspecimens via digital light processing (DLP) three-dimensional (3D)printing, which were examined as to their thermomechanical propertiesby means of dynamic mechanical analysis (DMA) and thermogravimetricanalysis (TGA) measurements

Synthesis and Characterization of In-Situ-Prepared Nanocomposites Based on Poly(Propylene 2,5-Furan Dicarboxylate) and Aluminosilicate Clays

Poly(propylene 2,5-furan dicarboxylate) (PPF), or poly(trimethylene 2,5-furan dicarboxylate) (PTF), is a biobased alipharomatic polyester that is expected to replace its fossil-based terephthalate (PPT) and naphthate (PPN) homologues. PPF possesses exceptional gas barrier properties, but its slow crystallization rate might affect its success in specific applications in the future. Therefore, a series of PPF based nanocomposites with the nanoclays Cloisite®-Na (MMT), Cloisite®-20A (MMT 20A), and halloysite nanotubes (HNT) were synthesized via the in situ transterification and polycondensation method. The effect of the nanoclays on the structure, thermal, and crystallization properties of PPF was studied with several methods including infrared spectroscopy (IR), Nuclear Resonance Spectroscopy (1H-NMR), Wide Angle X-ray Diffraction (WAXD), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). The insertion of the nanofillers in the polymer matrix altered the crystallization rates, and TGA results showed good thermal stability, since no significant mass loss occurred up to 300 °C. Finally, the degradation mechanism was studied in depth with Pyrolysis-Gas Chromatography/Mass Spectroscopy, and it was found that β-scission is the dominant degradation mechanism

Thermal Decomposition Kinetics and Mechanism of In-Situ Prepared Bio-Based Poly(propylene 2,5-furan dicarboxylate)/Graphene Nanocomposites

Bio-based polyesters are a new class of materials that are expected to replace their fossil-based homologues in the near future. In this work, poly(propylene 2,5-furandicarboxylate) (PPF) nanocomposites with graphene nanoplatelets were prepared via the in-situ melt polycondensation method. The chemical structure of the resulting polymers was confirmed by 1H-NMR spectroscopy. Thermal stability, decomposition kinetics and the decomposition mechanism of the PPF nanocomposites were studied in detail. According to thermogravimetric analysis results, graphene nanoplatelets did nοt affect the thermal stability of PPF at levels of 0.5, 1.0 and 2.5 wt.%, but caused a slight increase in the activation energy values. Pyrolysis combined with gas chromatography and mass spectroscopy revealed that the decomposition mechanism of the polymer was not altered by the presence of graphene nanoplatelets but the extent of secondary homolytic degradation reactions was increased

Conformal Quivers and Melting Molecules

Quiver quantum mechanics describes the low energy dynamics of a system of wrapped D-branes. It captures several aspects of single and multicentered BPS black hole geometries in four-dimensional $\mathcal{N} = 2$ supergravity such as the presence of bound states and an exponential growth of microstates. The Coulomb branch of an Abelian three node quiver is obtained by integrating out the massive strings connecting the D-particles. It allows for a scaling regime corresponding to a deep AdS$_2$ throat on the gravity side. In this scaling regime, the Coulomb branch is shown to be an $SL(2,\mathbb{R})$ invariant multi-particle superconformal quantum mechanics. Finally, we integrate out the strings at finite temperature---rather than in their ground state---and show how the Coulomb branch `melts' into the Higgs branch at high enough temperatures. For scaling solutions the melting occurs for arbitrarily small temperatures, whereas bound states can be metastable and thus long lived. Throughout the paper, we discuss how far the analogy between the quiver model and the gravity picture, particularly within the AdS$_2$ throat, can be taken.Comment: 49 pages, 16 figure

The Prevalence of Norovirus in returning international travelers with diarrhea

Background: There is a high incidence of diarrhea in traveling populations. Norovirus (NV) infection is a common cause of diarrhea and is associated with 7% of all diarrhea related deaths in the US. However, data on the overall prevalence of NV infection in traveling populations is limited. Furthermore, the prevalence of NV amongst travelers returning to Europe has not been reported. This study determined the prevalence of NV among international travelers returning to Germany from over 50 destinations in and outside Europe. Methods: Stool samples of a total of 104 patients with a recent (< 14days) history of international travel (55 male, mean age 37 yrs.) were tested for the presence of NV genogroup (GG) I and II infection using a sensitive and well established quantitative RT PCR method. 57 patients experienced diarrhea at the time of presentation at the Department of Infectious Diseases & Tropical Medicine. The remaining 47 patients had no experience of diarrhea or other gastrointestinal symptoms for at least 14 days prior to their date of presentation at our institute. Results: In our cohort, NV infection was detected in 15.7% of returning travelers with diarrhea. The closer to the date of return symptoms appeared, the higher the incidence of NV, ranging as high as 21.2% within the first four days after return. Conclusions: In our cohort, NV infection was shown to be frequent among returning travelers especially in those with diarrhea, with over 1/5 of diarrhea patients tested positive for NV within the first four days after their return to Germany. Due to this prevalence, routine testing for NV infection and hygienic precautions may be warranted in this group. This is especially applicable to patients at an increased risk of spreading the disease, such as healthcare workers, teachers or food-handlers

Frequent loss of heterozygosity and altered expression of the candidate tumor suppressor gene 'FAT' in human astrocytic tumors

Background: We had earlier used the comparison of RAPD (Random Amplification of Polymorphic DNA) DNA fingerprinting profiles of tumor and corresponding normal DNA to identify genetic alterations in primary human glial tumors. This has the advantage that DNA fingerprinting identifies the genetic alterations in a manner not biased for locus. Methods: In this study we used RAPD-PCR to identify novel genomic alterations in the astrocytic tumors of WHO grade II (Low Grade Diffuse Astrocytoma) and WHO Grade IV (Glioblastoma Multiforme). Loss of heterozygosity (LOH) of the altered region was studied by microsatellite and Single Nucleotide Polymorphism (SNP) markers. Expression study of the gene identified at the altered locus was done by semi-quantitative reverse-transcriptase-PCR (RT-PCR). Results: Bands consistently altered in the RAPD profile of tumor DNA in a significant proportion of tumors were identified. One such 500 bp band, that was absent in the RAPD profile of 33% (4/12) of the grade II astrocytic tumors, was selected for further study. Its sequence corresponded with a region of FAT, a putative tumor suppressor gene initially identified in Drosophila. Fifty percent of a set of 40 tumors, both grade II and IV, were shown to have Loss of Heterozygosity (LOH) at this locus by microsatellite (intragenic) and by SNP markers. Semi-quantitative RT-PCR showed low FAT mRNA levels in a major subset of tumors. Conclusion: These results point to a role of the FAT in astrocytic tumorigenesis and demonstrate the use of RAPD analysis in identifying specific alterations in astrocytic tumors

CX3CR1 Is Expressed by Human B Lymphocytes and Meditates CX3CL1 Driven Chemotaxis of Tonsil Centrocytes

Background: Fractalkine/CX(3)CL1, a surface chemokine, binds to CX(3)CR1 expressed by different lymphocyte subsets. Since CX(3)CL1 has been detected in the germinal centres of secondary lymphoid tissue, in this study we have investigated CX(3)CR1 expression and function in human naive, germinal centre and memory B cells isolated from tonsil or peripheral blood.Methodology/Principal Findings: We demonstrate unambiguously that highly purified human B cells from tonsil and peripheral blood expressed CX(3)CR1 at mRNA and protein levels as assessed by quantitative PCR, flow cytometry and competition binding assays. In particular, naive, germinal centre and memory B cells expressed CX(3)CR1 but only germinal centre B cells were attracted by soluble CX(3)CL1 in a transwell assay. CX(3)CL1 signalling in germinal centre B cells involved PI3K, Erk1/2, p38, and Src phosphorylation, as assessed by Western blot experiments. CX(3)CR1(+) germinal centre B cells were devoid of centroblasts and enriched for centrocytes that migrated to soluble CX(3)CL1. ELISA assay showed that soluble CX(3)CL1 was secreted constitutively by follicular dendritic cells and T follicular helper cells, two cell populations homing in the germinal centre light zone as centrocytes. At variance with that observed in humans, soluble CX(3)CL1 did not attract spleen B cells from wild type mice. OVA immunized CX(3)CR1-/- or CX(3)CL1-/- mice showed significantly decreased specific IgG production compared to wild type mice.Conclusion/Significance: We propose a model whereby human follicular dendritic cells and T follicular helper cells release in the light zone of germinal centre soluble CX(3)CL1 that attracts centrocytes. The functional implications of these results warrant further investigation

A High Throughput Screen Identifies Chemical Modulators of the Laminin-Induced Clustering of Dystroglycan and Aquaporin-4 in Primary Astrocytes

Background: Aquaporin-4 (AQP4) constitutes the principal water channel in the brain and is clusteredat the perivascular astrocyte endfeet. This specific distribution of AQP4 plays a major role in maintaining water homeostasis in the brain. A growing body of evidence points to a role ofthe dystroglycan complex and its interaction with perivascular laminin in the clusteringof AQP4 atperivascular astrocyte endfeet. Indeed, mice lacking components of this complex or in which laminindystroglycan interaction is disrupted show a delayed onset of brain edema due to a redistribution of AQP4 away from astrocyte endfeet. It is therefore important to identify inhibitory drugs of laminin-dependent AQP4 clustering which may prevent or reduce brain edema. Methodolgy/Principal Findings: In the present study we used primary rat astrocyte cultures toscreen a library of.3,500 chemicals and identified 6 drugs that inhibit the laminin-induced clustering of dystroglycan and AQP4. Detailed analysis of the inhibitory drug, chloranil, revealed that its inhibition of the clustering is due to the metalloproteinase-2-mediated ß-dystroglycan shedding and subsequent loss of laminin interaction with dystroglycan. Furthermore, chemical variants of chloranil induced a similar effect on ß-dystroglycan and this was prevented by the antioxidant N-acetylcysteine. Conclusion/Significance: These findings reveal the mechanism of action of chloranil in preventing the laminin-induced clustering of dystroglycan and AQP4 and validate the use of high-throughput screening as a tool to identify drugs tha

Population genomics of marine zooplankton

Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Bucklin, Ann et al. "Population Genomics of Marine Zooplankton." Population Genomics: Marine Organisms. Ed. Om P. Rajora and Marjorie Oleksiak. Springer, 2018. doi:10.1007/13836_2017_9.The exceptionally large population size and cosmopolitan biogeographic distribution that distinguish many – but not all – marine zooplankton species generate similarly exceptional patterns of population genetic and genomic diversity and structure. The phylogenetic diversity of zooplankton has slowed the application of population genomic approaches, due to lack of genomic resources for closelyrelated species and diversity of genomic architecture, including highly-replicated genomes of many crustaceans. Use of numerous genomic markers, especially single nucleotide polymorphisms (SNPs), is transforming our ability to analyze population genetics and connectivity of marine zooplankton, and providing new understanding and different answers than earlier analyses, which typically used mitochondrial DNA and microsatellite markers. Population genomic approaches have confirmed that, despite high dispersal potential, many zooplankton species exhibit genetic structuring among geographic populations, especially at large ocean-basin scales, and have revealed patterns and pathways of population connectivity that do not always track ocean circulation. Genomic and transcriptomic resources are critically needed to allow further examination of micro-evolution and local adaptation, including identification of genes that show evidence of selection. These new tools will also enable further examination of the significance of small-scale genetic heterogeneity of marine zooplankton, to discriminate genetic “noise” in large and patchy populations from local adaptation to environmental conditions and change.Support was provided by the US National Science Foundation to AB and RJO (PLR-1044982) and to RJO (MCB-1613856); support to IS and MC was provided by Nord University (Norway)