Comparative Analysis of In situ Fibronectin Using ToF-SIMS, SPI-MS, and dropDESI-MS in a Microfluidic Reactor

Fibronectin is an important biomolecule due to its role in cell differentiation, growth, kinesis, and adhesion. Such biological responses are mediated through membrane recognition and signaling; where fibronectin is found. Studying the outer molecular surface of fibronectin allows deeper insight into the microbiological reactions that occur during these processes. In situ mass spectrometry analysis in aqueous solution accurately represents fibronectin’s chemical components, made possible by a vacuum compatible microfluidic reactor, SALVI (System for Analysis at the Liquid Vacuum Interface). SALVI was paired with the analytical tools: time-of-flight secondary ion mass spectrometer (ToF-SIMS), single photon ionization mass spectrometer (SPI-MS) and drop desorption electrospray ionization mass spectrometer (dropDESI-MS). ToF-SIMS employed a bismuth liquid metal ion beam. Positive and negative ion spectral plots were constructed and analyzed. The advanced light source (ALS) SPI-MS), using a synchrotron vacuum ultraviolet (VUV) light, elicited data depending on varying photoionization efficiencies (PIE). PIE plots were examined for the initial detection of photons of a mass to charge ratio (m/z), resulting in the determination of the ionization efficiency (IE) of a corresponding compound. Both ToF-SIMS and SPI-MS are surface tools, with ion beam impact no further than the second monolayer. DropDESI-MS, analyzed under ambient conditions, utilized a capillary connecting the electrode spray to the mass spectrometer. Charged microdroplets were used to introduce samples to the mass analyzer. Central masses (m/z) from all three apparatuses were identified to their most possible compounds or constituents, demonstrating complementary results. Mass identifications were based on literature survey and results from peer reviewed articles. Our results suggest the need for further research of organic compounds, like fibronectin, to understand their surface compositions in aqueous solution

Enhancing the Chemical Mixture Methodology: Incorporating 20 Health Code Numbers

The Chemical Mixture Methodology (CMM) is used by the Department of Energy (DOE), its contractors, and other private and public organizations for emergency response planning. CMM assesses the potential health impacts on individuals that would result from exposure to an airborne mixture of hazardous chemicals. Health Code Numbers (HCNs) are assigned to each chemical based on the human organs targeted by exposure. In the current CMM, only the top 10 HCNs ranked by severity are included in each CMM analysis. This project focuses on assessing what happens when doubling the potential number of HCNs for each chemical that could be used in each CMM analysis. A total of 361 chemicals were used in our testing (the entire CMM database contains over 3000 chemicals). A set of 127 representative mixtures were prepared for our analysis. Three different concentration distributions (called “ideal”, “realistic”, and “same”) were used for each test mixture, providing us with a total of 381 test cases. CMM results were compared for all 381 test cases using both the 10-HCN approach and the 20-HCN approach. Only a slight difference was observed between the 10- and 20-HCN approaches. This slight difference suggests that the top 10-HCNs give good representation of the potential toxic health effects. This also indicates that it is impractical to incorporate the 20-HCN approach in a future version of the CMM. Therefore, effort should be directed to other aspects of the CMM development such as refining the nervous system effects or respiratory irritant effects in the near future

Chemical Mixture Methodology (CMM): Using 15 Health Code Numbers

The Chemical Mixture Methodology (CMM) is used for an emergency response and safety planning for chemical mixtures that cause irreversible or serious health effects. There are three major components of the CMM: Health Code Numbers (HCNs), the Hazard Index, and the Protective Action Criteria values. The HCNs are akin to medical diagnostic codes; they categorize the adverse health outcome that could be induced by exposure to an individual hazardous chemical. Currently, 60 HCNs are used in the CMM to characterize potential health effects for over 3,000 chemicals. Chemicals may have one or more HCNs; however, a maximum of 10 HCNs may be listed in the CMM dataset for each chemical. The HCNs for each chemical are ranked based on their seriousness and the impact of the health effect on a person’s ability to take protective action, with the most serious being included in the CMM. Many chemicals in the CMM dataset have 10 HCNs. This study explored how CMM results would vary if an additional five HCNs were allowed, if needed, for each chemical. A total of 361 common chemicals from the CMM dataset were updated to include up to five additional HCNs. To evaluate the 15-HCN approach, we used 127 test mixtures and each mixture was assessed using three different concentration distributions. This provided a total of 381 test cases in our assessment. Comparing results using the 15-HCN approach to those using the 10-HCN approach, showed no substantial difference in CMM results. This suggests that it may not be necessary to include more HCNs in the CMM dataset. The CMM team continues to update the CMM to support its many users in the United States and around the world. For further information on the CMM, visit http://orise.orau.gov/emi/scapa/chem-mixture-methodolgy/default.htm

Comparison Analysis of Dust-Depressor Using Microbial Induced Carbonate Precipitation with Urease Reagent

The dust-depressors have been developed utilizing a method of microbial induced carbonate precipitation. This microbial dust-depressor has the characteristics of high efficiency for dust suppression and environmental protection. Optimal compositions of urease dust-depressor and microbial dust-depressor have been studied. In addition, pure water, CaCl2 and super absorbent polymer are chosen to compare with new dust-depressors on the performances. The results showed that the microbial dust-depressor had 3.13 mm/min of seepage velocity and 79.1% of dust suppression efficiency, which were superior to other dust-depressors on the performance of seepage velocity and dust suppression efficiency

Using In Situ Liquid Single Photon Ionization Mass Spectrometry (SPI-MS) to Probe Lithium Polysulfide Electrolyte in Motion

The solid-liquid (s-l) interface is the most common interface encountered in electrochemical systems. The s-l interface has wide applications in energy storage, catalysis, and material sciences. In situ studies of chemical reactions taking place on the s-l interfaces can further our understanding of electron transfer and link to real-world device functions under challenging conditions. Direct probing of the solid electrode and liquid electrolyte interface has been realized using a vacuum compatible electrochemical microfluidic reactor, system for analysis at the liquid vacuum interface (SALVI) with time-of-flight secondary ion mass spectrometry (ToF-SIMS). Most recently, the electrochemical version of SALVI was integrated to the synchrotron based single photon ionization mass spectrometry (SPI-MS). SPI-MS has proven to be a versatile technique for analysis of organic species in the solid or gas phase due to its nature of soft ionization. As a practical example, three different lithium polysulfide electrolytes, Li2S4, Li2S6, and Li2S8, were studied under dynamic conditions with various applied voltages. It was found that despite some PDMS interference peaks such as 369 m/z, unique peaks of interest signifying the electron transfer of the LixSy electrolytes can be identified according to the SPI-MS mass spectra. The observation of in situ compositional changes as a result of electrochemical reaction that take place at the s-l interface in a three electrode system allowed us to piece all the fragments together and identify the compound present in the sample at different stages of photoionization energy (PIE) values. Moreover, we demonstrate that liquid SPI-MS technique has been enabled to study dynamic electron transfer of LixSy electrolytes using real-time molecular imaging

Local Active Galactic Nuclei with Large Broad-H{\alpha} Variability Reside in Red Galaxies

Inspired by our serendipitous discovery of six AGNs with varying broad-Halpha fluxes over years out of our searching for intermediate-mass black holes (IMBHs), we conduct a systematic investigation of changing-look (CL) and large-variability AGNs. We collect all the CL AGNs at z<0.15 and the reverberation mapped AGNs with strongly variable broad Halpha, and perform careful decomposition fittings to both their images and spectra. We find two observational facts: (1) The host galaxies of local CL and large-variability AGNs, mainly being Seyferts, are in the red (gas-poor) tail of the general Seyfert galaxy population. (2) In contrast, there is a significant trend that their more luminous counterparts namely CL and extremely variable quasars (CLQs and EVQs) are different: CLQs are generally in blue galaxies; in terms of the diagram of SFR and M* local CL Seyfert galaxies are located in the green valley, whereas CLQ hosts are in the star-forming main sequence. We propose explanations for those strongly variable Seyferts and quasars, respectively, under the thought that accretion disks broadly depend on nuclear fueling modes. Local large-variability and CL Seyferts are in nuclear famine mode, where cold-gas clumps can be formed stochastically in the fueling flow, and their episodic infall produces sharp peaks in the accretion-rate curve. CLQs and EVQs are in feast fueling mode, which may account for both their preference to blue galaxies and their variability pattern (high-amplitude tail of the continuous distribution). Lastly, we propose a new thinking: to search for IMBHs by optical variability in red galaxies.Comment: 37 pages(incl. Appendix), 10 figures, and 5 tables. Published in ApJ. (v2)Text changed to match the published versio

Release of Bioactive Adeno-Associated Virus from Fibrin Scaffolds: Effects of Fibrin Glue Concentrations

Fibrin glue (FG) is used in a variety of clinical applications and in the laboratory for localized and sustained release of factors potentially important for tissue engineering. However, the effect of different fibrinogen concentrations on FG scaffold delivery of bioactive adeno-associated viruses (AAVs) has not been established. This study was performed to test the hypothesis that FG concentration alters AAV release profiles, which affect AAV bioavailability. Gene transfer efficiency of AAV-GFP released from FG was measured using HEK-293 cells. Bioactivity of AAV transforming growth factor-beta1 (TGF-β1) released from FG was assessed using the mink lung cell assay, and by measuring induction of cartilage-specific gene expression in human mesenchymal stem cells (hMSCs). Nondiluted FG had longer clotting times, smaller pore sizes, thicker fibers, and slower dissolution rate, resulting in reduced release of AAV. AAV release and gene transfer efficiency was higher with 25% and 50% FG than with the 75% and 100% FG. AAV-TGF-β1 released from dilute-FG transduced hMSCs, resulting in higher concentrations of bioactive TGF-β1 and greater upregulation of cartilage-specific gene expression compared with hMSC from undiluted FG. This study, showing improved release, transduction efficiency, and chondrogenic effect on hMSC of bioactive AAV-TGF-β1 released from diluted FG, provides information important to optimization of this clinically available scaffold for therapeutic gene delivery, both in cartilage regeneration and for other tissue engineering applications