Polymer derived silicon oxycarbide ceramic monoliths: Microstructure development and associated materials properties

Polymer derived SiOC and SiCN ceramics (PDCs) are interesting candidates for additive manufacturing techniques to develop micro sized ceramics with the highest precision. PDCs are obtained by the pyrolysis of crosslinked polymer precursors at elevated temperatures. Within this work, we are investigating PDC SiOC ceramic monoliths synthesized from liquid polysiloxane precursor crosslinked with divinylbenzene for fabrication of conductive electromechanical devices. Microstructure of the final ceramics was found to be greatly influenced by the pyrolysis temperature. Crystallization in SiOC ceramics starts above 1200?°C due to the onset of carbothermal reduction leading to the formation of SiC and SiO₂ rich phases. Microstructural characterisation using ex-situ X-ray diffraction, FTIR, Raman spectra and microscopy imaging confirms the formation of nano crystalline SiC ceramics at 1400?°C. The electrical and mechanical properties of the ceramics are found to be significantly influenced by the phase separation with samples becoming more electrically conducting but with reduced strength at 1400?°C. A maximum electrical conductivity of 10¹ S?cm^?1 is observed for the 1400?°C samples due to enhancement in the ordering of the free carbon network. Mechanical testing using the ball on 3 balls (B3B) method revealed a characteristic flexural strength of 922?MPa for 1000?°C amorphous samples and at a higher pyrolysis temperature, materials become weaker with reduced strength.     

Dipalmitoyl-Phosphatidylcholine Biosynthesis is Induced by Non-Injurious Mechanical Stretch in a Model of Alveolar Type II Cells

Dipalmitoylphosphatidylcholine, (DP-PtdCho), the major phospholipid component of lung surfactant is biosynthesized via a de novo pathway, the last step of which is catalyzed by CDP-choline:cholinephosphotransferase (CPT) and two remodeling steps: a deacylation and a reacylation one, catalyzed by an acidic, Ca²⁺-independent phospholipase A₂ (aiPLA₂) and a lyso-phosphatidylcholine acyltransferase (LPCAT), respectively. The aim of our study was to investigate whether a low magnitude, non-injurious static mode of mechanical stretch can induce phosphatidylcholine (PtdCho) biosynthesis and its remodeling to DP-PtdCho in the A549 cell-line, a model of alveolar type II cells. The deformation of A549 cells did not cause any release of lactate dehydrogenase, or phospholipids into the cell culture supernatants. An increase in PtdCho levels was observed after 1 h of static stretching, especially among the DP-PtdCho molecular species, as indicated by targeted lipidomics approach and site-directed fatty acyl-chain analysis. Moreover, although sphingomyelin (CerPCho) levels were unaffected, the DP-PtdCho/CerPCho ratio increased. Induction was observed in CPT, LPCAT and aiPLA₂ enzymatic activities and gene expression. Finally, incubation of the cells with MJ33 suppressed aiPLA₂ activity and DP-PtdCho production. Our data suggest that mild static mechanical stretch can promote the biosynthesis of PtdCho and its remodeling to DP-PtdCho in lung epithelial cells. Thus, low magnitude stretch could contribute to protective mechanisms rather than to injurious ones.     

Effect of ball milling on the mechanical properties and crystallization of graphene nanoplatelets reinforced short chain branched-polyethylene

Short-chain-branched-polyethylene (SCB-PE) is extensively used in domestic hot and cold piping systems. SCB-PE nanocomposites using graphene nanoplatelets (GNPs) as a filler, were prepared in this work. The effect of ball-milling as a premixing technique prior to melt-mixing, on the crystallization and the nanomechanical properties of the composites has been studied. Two sets of SCB-PE/GNPs nanocomposites with various filler loadings were prepared; one with and one without the ball-milling step. The dispersion of the filler was evaluated by optical microscopy while the crystallization process was studied using differential scanning calorimetry. The nonisothermal crystallization's experimental data were analyzed using various methods. The materials' nanomechanical behavior was investigated by conducting nanoindentation tests. A finite element analysis process was developed to extract the composites' stress–strain behavior. The composites prepared with ball-milling presented improved dispersion of GNPs in the SCB-PE matrix, which affected the crystallization, while nanoindentation tests showed significantly enhanced mechanical properties.     

The 2017 fipronil egg contamination incident: The case of Greece

In 2017, an outbreak regarding the release to the market of contaminated eggs with fipronil, alerted all EU authorities as to monitor and take relevant measures. In Greece, a total of 40 samples of poultry fat and eggs taken from the primary production (poultry farms) were analyzed, as to investigate the occurrence of fipronil residues. For the analysis of the samples, a simple and cost effective sample preparation procedure using freezing as the cleanup step was used, in conjunction with liquid chromatography with electrospray ionization-tandem mass spectrometry, to identify and quantify fipronil and its sulfone metabolite in poultry fat and eggs. Mean recoveries in the range 69.3–120.3% with all relative standard deviations <18.8% were obtained for both analytes and both matrices. The limit of quantification of the method was set at 0.0025 mg/kg⁻¹. The matrix effect was evaluated and the quantification of the analytes was conducted using matrix matched calibration standards.     

Worldwide market screening of saffron volatile composition

BACKGROUND: Saffron (Crocus sativus L.) is one of the most valuable spices and nowadays its main use is as a foodstuff. Numerous papers have been published on saffron aroma and its volatile content, but nothing has been written about the aroma quality of samples available on the market to consumers. The aim of this study was to analyse and compare 418 commercial samples of saffron belonging to different ISO categories. Ultrasound‐assisted extraction (USAE) with an organic solvent and dynamic headspace desorption (DHD) followed by gas chromatography/mass spectrometry were used to screen for saffron volatile composition. RESULTS: For both methods the saffron aromatic profile was characterised by spicy aromatic notes due to safranal, the most abundant volatile component, by a floral contribution attributable to isophorone and 2,2,6‐trimethyl‐1,4‐cyclohexanedione, together with citrus and spicy notes from 4‐ketoisophorone and 2‐hydroxy‐4,4,6‐trimethyl‐2,5‐cyclohexadien‐1‐one respectively. CONCLUSION: USAE allowed the detection of a greater number of compounds, whereas DHD was faster and a smaller amount of saffron was required. Compared with the USAE method, the DHD method defined the samples as having a spicier and more floral aromatic contribution, thus corroborating that the extraction method considerably changes the aromatic fingerprint of saffron samples. Copyright © 2009 Society of Chemical Industry     

Risk assessment of biological hazards in the European Union

International, community and national food safety law and any subsequent decision-making practices aim to be based on risk analysis--a process consisting of risk assessment, risk management and risk communication. With the appointment of the European Food Safety Authority as an independent scientific point of reference in risk assessment, there is a clear functional separation between risk assessment and risk management in the European Union food safety context. When a food safety question on microbiological hazards is to be answered--which is under the remit of the EFSA's Scientific Panel on Biological Hazards (BIOHAZ)--extensive dialogue and interactions covering the clarity of the question, the acceptability of the deadline and the availability of all necessary information take place with both the risk managers who ask the question and the stakeholders. During the first mandate of the BIOHAZ Panel (2003-2006), the scientific opinions were mainly based on qualitative and in some cases semi-quantitative microbiological risk assessment. In the second mandate of the BIOHAZ Panel, and as a first step towards developing a European approach on Quantitative Microbiological Risk Assessment (QMRA), EFSA is preparing to carry out a QMRA on Salmonella in pigs, at European level through a consortium of European institutes.     

A mathematical model of subpopulation kinetics for the deconvolution of leukaemia heterogeneity

Acute myeloid leukaemia is characterized by marked inter- and intra-patient heterogeneity, the identification of which is critical for the design of personalized treatments. Heterogeneity of leukaemic cells is determined by mutations which ultimately affect the cell cycle. We have developed and validated a biologically relevant, mathematical model of the cell cycle based on unique cell-cycle signatures, defined by duration of cell-cycle phases and cyclin profiles as determined by flow cytometry, for three leukaemia cell lines. The model was discretized for the different phases in their respective progress variables (cyclins and DNA), resulting in a set of time-dependent ordinary differential equations. Cell-cycle phase distribution and cyclin concentration profiles were validated against population chase experiments. Heterogeneity was simulated in culture by combining the three cell lines in a blinded experimental set-up. Based on individual kinetics, the model was capable of identifying and quantifying cellular heterogeneity. When supplying the initial conditions only, the model predicted future cell population dynamics and estimated the previous heterogeneous composition of cells. Identification of heterogeneous leukaemia clones at diagnosis and post-treatment using such a mathematical platform has the potential to predict multiple future outcomes in response to induction and consolidation chemotherapy as well as relapse kinetics.     

The role of the Hellenic Food Safety Authority in Greece—Implementation strategies

During the last 15 years, a series of food scares and crises (BSE, dioxin, foot and mouth disease) have seriously undermined public confidence in food producers and operators and their capacity to produce safe food. As a result, food safety has become a top priority of the European legislative authorities and systems of national food control have been tightened up and have included the establishment of the European Food Safety Authority. In Greece a law creating the Hellenic Food Safety Authority has been approved. The main objectives of this Authority are to promote the food security to consumers and inform them of any changes or any development in the food and health sector.

The paper reviews the general structure of the current food control system in Greece. It describes the structure and the mission of the Hellenic Food Safety Authority and explains the strategy to carry out inspections and the analysis of the preliminary results of such inspections. Details are also given of the personnel training and certification and accreditation standards to be met by the Authority by the end of 2004.