Tidal Disruption of White Dwarfs from Ultra-close Encounters with Intermediate-mass Spinning Black Holes

We present numerical relativity results of tidal disruptions of white dwarfs from ultra-close encounters with a spinning, intermediate-mass black hole (IMBH). These encounters require a full general relativistic treatment of gravity. We show that the disruption process and prompt accretion of the debris strongly depend on the magnitude and orientation of the black hole (BH) spin. However, the late-time accretion onto the BH follows the same decay, Ṁ ∝ t^(-5/3), estimated from Newtonian gravity disruption studies. We compute the spectrum of the disk formed from the fallback material using a slim disk model. The disk spectrum peaks in the soft X-rays and sustains Eddington luminosity for 1-3 yr after the disruption. For arbitrary BH spin orientations, the disrupted material is scattered away from the orbital plane by relativistic frame dragging, which often leads to obscuration of the inner fallback disk by the outflowing debris. The disruption events also yield bursts of gravitational radiation with characteristic frequencies of ~3.2 Hz and strain amplitudes of ~10^(–18) for galactic IMBHs. The optimistic rate of considered ultra-close disruptions is consistent with no sources found in the ROSAT all-sky survey. Future missions like Wide-Field X-ray Telescope could observe dozens of events

In-line monitoring of polymer nanoparticle growth during synthesis in concentrated systems by photon density wave spectroscopy

Photon Density Wave (PDW) spectroscopy [1-4] determines the absolute optical properties of highly turbid liquid dispersions without a need for prior method calibration. As parameters, the absorption coefficient ma and the reduced scattering coefficient ms’ are obtained. Based on Mie theory and theories for dependent light scattering, the reduced scattering coefficient is linked to the particle size of the suspended particles, allowing for dilution-free particle sizing in size regimes of approx. 50 nm to 500 µm. Currently, PDW spectroscopy provides a time resolution of approx. 2 min-1 and can be operated with fiber-optical process probes [5], thus it allows for in-line particle size measurements during polymerization processes. Here, PDW spectroscopy was applied to investigate the growth of polymer nanoparticles in-line during their synthesis. Examples cover polymerization of styrene at 20 wt%, semi-batch polymerization of vinyl acetate up to solid fractions of 50 wt%, and starved feed copolymerization of acrylate-based monomers [6] up to 40 wt%. For example, in the case of the synthesis of polyvinyl acetate, it could be observed in-line that the growth of the polymer nanoparticles only commenced after a significant amount of monomer had been fed into the reactor (approx. 20 wt%), thus indicating that during the first hour after polymerization start mainly particle nucleation occurred. The results obtained with respect to particle size agreed well with off-line dynamic and static light scattering reference experiments, which required sampling and sample dilution. By the use of multiple laser wavelengths for PDW spectroscopy, an estimation of the particle size distribution during synthesis can be obtained as well [2]. In the case of polyvinyl acetate, the findings indicate an increasing particle size distribution width during its synthesis. Based on the estimation of the particle size distribution, particle numbers and particle growth rates can be calculated, thus providing access for an increased process understanding and finally an approach for real-time process control during synthesis of polymer nanoparticles in concentrated dispersions. [1] Bressel L., Hass R., Reich O., Particle sizing in highly turbid dispersions by photon density wave spectroscopy, J. Quant. Spectrosc. Radiat. Transf. 126:122-129 (2013). [2] Hass R., Münzberg M., Bressel L., Reich O., Industrial applications of Photon Density Wave spectroscopy for in-line particle sizing, Appl. Opt. 52:1423-1431 (2013). [3] Fishkin J.B., Fantini S., van de Ven M.J., Gratton E., Gigahertz photon density waves in a turbid medium: Theory and experiments, Phys. Rev. E 53:2307-2319 (1996). [4] Richter S.M., Shinde R.R., Balgi G.V., Sevick-Muraca E.M., Particle sizing using frequency domain photon migration, Part. Part. Syst. Charact. 15:9-15. (1998). [5] Hass R., Munzke D., Vargas Ruiz S., Tippmann J., Reich O., Optical monitoring of chemical processes in turbid biogenic liquid dispersions by photon density wave spectroscopy, Anal. Bioanal. Chem. 407:2791-2802 (2015). [6] Hass R., Reich O., Photon Density Wave spectroscopy for dilution-free sizing of highly concentrated nanoparticles during starved-feed polymerization, ChemPhysChem 12:2572-2575 (2011)

Real-time inline monitoring of zeolite synthesis by Photon Density Wave spectroscopy

The formation process of zeolite A (Linde Type A) was monitored inline at 1.5 L scale by Photon Density Wave (PDW) spectroscopy as novel process analytical technology for highly turbid liquid suspensions. As a result, the reduced scattering coefficient, being a measure for particle number, size, and morphology, provides distinct process information, including the formation of amorphous particles and their transfer into crystalline zeolite structures. The onset and end of the crystallization process can be detected inline and in real-time. Analyses by powder X-ray diffraction and electron microscopy, based on a sampling approach, support the interpretation of the results obtained by PDW spectroscopy. In addition, the influence of the molar water content was investigated, indicating a linear increase of the time needed to reach the end of the zeolite A crystallization with increasing molar water content. Further experiments indicate a strong influence of the silica source on the course of the crystallization. The applicability of PDW spectroscopy under even more demanding chemical and physical conditions was investigated by monitoring the synthesis of zeolite L (Linde Type L)

Integrating Whole Cell Biotransformation of Aroma Compounds into a Novel Biorefinery Concept

The synthesis of aroma compounds that are utilized as precursors of multiple synthesis chains in the pharmaceutical industries and as ingredients in food and fragrance industries can be carried out using chemical processes, enzyme biocatalysis and whole cell biotransformation. Whole cell biotransformation has the potential of being more environmentally benign than chemical synthesis and more cost-effective as compared to enzyme catalysis. In a recently published study by the authors, the aroma compound Ethyl(3)hydroxybutyrate was produced by whole cell biotransformation under aerobic and anaerobic conditions. The yield of the anaerobic processes was similar to that of the aerobic processes, but additionally generated CO2 and ethanol as useful by-products. In this chapter we illustrate how the production process of Ethyl(3)hydroxybutyrate by whole cell biotransformation can be integrated into a novel biorefinery concept, based on the finding that the production of Ethyl(3)hydroxybutyrate under anaerobic conditions is efficient and environmentally friendly. CO2 may be converted to bio-methane together with H2 produced from excess regenerative power. A life cycle assessment confirmed that the anaerobic whole cell biotransformation process embedded into a biorefinery concept including bio-methane production has a lower environmental impact as compared to a concept based on the aerobic whole cell biotransformation

In-Line Monitoring of Polyhydroxyalkanoate (PHA) Production during High-Cell-Density Plant Oil Cultivations Using Photon Density Wave Spectroscopy

Polyhydroxyalkanoates (PHAs) are biodegradable plastic-like materials with versatile properties. Plant oils are excellent carbon sources for a cost-effective PHA production, due to their high carbon content, large availability, and comparatively low prices. Additionally, efficient process development and control is required for competitive PHA production, which can be facilitated by on-line or in-line monitoring devices. To this end, we have evaluated photon density wave (PDW) spectroscopy as a new process analytical technology for Ralstonia eutropha (Cupriavidus necator) H16 plant oil cultivations producing polyhydroxybutyrate (PHB) as an intracellular polymer. PDW spectroscopy was used for in-line recording of the reduced scattering coefficient µs’ and the absorption coefficient µa at 638 nm. A correlation of µs’ with the cell dry weight (CDW) and µa with the residual cell dry weight (RCDW) was observed during growth, PHB accumulation, and PHB degradation phases in batch and pulse feed cultivations. The correlation was used to predict CDW, RCDW, and PHB formation in a high-cell-density fed-batch cultivation with a productivity of 1.65 gPHB·L−1·h−1 and a final biomass of 106 g·L−1 containing 73 wt% PHB. The new method applied in this study allows in-line monitoring of CDW, RCDW, and PHA formation.BMBF, 03Z22AN12, Zentrum für Innovationskompetenz innoFSPEC, Nachwuchsgruppe Angewandte Analytische Photonik (AAP

Human umbilical cord-derived mesenchymal stem cells utilise activin-A to suppress interferon-gamma production by natural killer cells

Following allogeneic hematopoietic stem cell transplantation (HSCT), interferon (IFN)-γ levels in the recipient's body can strongly influence the clinical outcome. Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) are lucrative as biological tolerance inducers in HSCT settings. Hence, we studied the molecular mechanism of how UC-MSCs influence natural killer (NK) cell-mediated IFN-γ production. Allogeneic NK cells were cultured in direct contact with UC-MSCs or cell free supernatants from MSC cultures (MSC conditioned media). We found that soluble factors secreted by UC-MSCs strongly suppressed IL-12/IL-18-induced IFN-γ production by NK cells by reducing phosphorylation of STAT4, NF-κB as well as T-bet activity. UC-MSCs secreted considerable amounts of Activin-A, which could suppress IFN-γ production by NK cells. Neutralisation of Activin-A in MSC conditioned media significantly abrogated their suppressive abilities. Till date, multiple groups have reported that prostaglandin (PG)-E2 produced by MSCs can suppress NK cell functions. Indeed, we found that inhibition of PGE2 production by MSCs could also significantly restore IFN-γ production. However, the effects of Activin-A and PGE2 were not cumulative. To the best of our knowledge, we are first to report the role of Activin-A in MSC mediated suppression of IFN-γ production by NK cells.DFG/SFB738/A5Hannover Biomedical Research School (HBRS)DFG/REBIRTHNiedersächsische Krebsgesellschaf

Role of gamma-secretase in human umbilical-cord derived mesenchymal stem cell mediated suppression of NK cell cytotoxicity

Background: Mesenchymal stem cells (MSCs) are increasingly considered to be used as biological immunosuppressants in hematopoietic stem cell transplantation (HSCT). In the early reconstitution phase following HSCT, natural killer (NK) cells represent the major lymphocyte population in peripheral blood and display graft-vs-leukemia (GvL) effects. The functional interactions between NK cells and MSCs have the potential to influence the leukemia relapse rate after HSCT. Until date, MSC-NK cell interaction studies are largely focussed on bone marrow derived (BM)-MSCs. Umbilical cord derived (UC)-MSCs might be an alternative source of therapeutic MSCs. Thus, we studied the interaction of UC-MSCs with unstimulated allogeneic NK cells.Results: UC-MSCs could potently suppress NK cell cytotoxicity in overnight cultures via soluble factors. The main soluble immunosuppressant was identified as prostaglandin (PG)-E2. Maximal PGE2 release involved IL-1β priming of MSCs after close contact between the NK cells and UC-MSCs. Interestingly, blocking gamma-secretase activation alleviated the immunosuppression by controlling PGE2 production. IL-1 receptor activation and subsequent downstream signalling events were found to require gamma-secretase activity.Conclusion: Although the role of PGE2 in NK cell-MSC has been reported, the requirement of cell-cell contact for PGE2 induced immunosuppression remained unexplained. Our findings shed light on this puzzling observation and identify new players in the NK cell-MSC crosstalk.DFG/SFB738/A5Hannover Biomedical Research School (HBRS)REBIRTH Cluster of ExcellenceNiedersächsische Krebsgesellschaft e.V

Using absorption and reduced scattering coefficients for non-destructive analyses of fruit flesh firmness and soluble solids content in pear (pyrus communis ‘conference’)—an update when using diffusion theory

Quality attributes of fruit determine its acceptability by the retailer and consumer. The objective of this work was to investigate the potential of absorption (μa) and reduced scattering (μs’) coefficients of European pear to analyze its fruit flesh firmness and soluble solids content (SSC). The absolute reference values, μa* (cm−1) and μs’* (cm−1), of pear were invasively measured, employing multi-spectral photon density wave (PDW) spectroscopy at preselected wavelengths of 515, 690, and 940 nm considering two batches of unripe and overripe fruit. On eight measuring dates during fruit development, μa and μs’ were analyzed non-destructively by means of laser light backscattering imaging (LLBI) at similar wavelengths of 532, 660, and 830 nm by means of fitting according to Farrell’s diffusion theory, using fix reference values of either μa* or μs’*. Both, the μa* and the μa as well as μs’* and μs’ showed similar trends. Considering the non-destructively measured data during fruit development, μa at 660 nm decreased 91 till 141 days after full bloom (dafb) from 1.49 cm−1 to 0.74 cm−1 due to chlorophyll degradation. At 830 nm, μa only slightly decreased from 0.41 cm−1 to 0.35 cm−1. The μs’ at all wavelengths revealed a decreasing trend as the fruit developed. The difference measured at 532 nm was most pronounced decreasing from 24 cm−1 to 10 cm−1, while at 660 nm and 830 nm values decreased from 15 cm−1 to 13 cm−1 and from 10 cm−1 to 8 cm−1, respectively. When building calibration models with partial least-squares regression analysis on the optical properties for non-destructive analysis of the fruit SSC, μa at 532 nm and 830 nm resulted in a correlation coefficient of R = 0.66, however, showing high measuring uncertainty. The combination of all three wavelengths gave an enhanced, encouraging R = 0.89 for firmness analysis using μs’ in the freshly picked fruit

Scientific principles for the identification of endocrine-disrupting chemicals: a consensus statement

Endocrine disruption is a specific form of toxicity, where natural and/or anthropogenic chemicals, known as "endocrine disruptors" (EDs), trigger adverse health effects by disrupting the endogenous hormone system. There is need to harmonize guidance on the regulation of EDs, but this has been hampered by what appeared as a lack of consensus among scientists. This publication provides summary information about a consensus reached by a group of world-leading scientists that can serve as the basis for the development of ED criteria in relevant EU legislation. Twenty-three international scientists from different disciplines discussed principles and open questions on ED identification as outlined in a draft consensus paper at an expert meeting hosted by the German Federal Institute for Risk Assessment (BfR) in Berlin, Germany on 11-12 April 2016. Participants reached a consensus regarding scientific principles for the identification of EDs. The paper discusses the consensus reached on background, definition of an ED and related concepts, sources of uncertainty, scientific principles important for ED identification, and research needs. It highlights the difficulty in retrospectively reconstructing ED exposure, insufficient range of validated test systems for EDs, and some issues impacting on the evaluation of the risk from EDs, such as non-monotonic dose-response and thresholds, modes of action, and exposure assessment. This report provides the consensus statement on EDs agreed among all participating scientists. The meeting facilitated a productive debate and reduced a number of differences in views. It is expected that the consensus reached will serve as an important basis for the development of regulatory ED criteria