Chaetopterus variopedatus Bioluminescence: A Review of Light Emission within a Species Complex

Chaetopterus variopedatus has been studied for over a century in terms of its physiology, ecology and life history. One focus of research is on its intrinsic bioluminescent emissions, which can be observed as a blue light emitted from the extremities of individual body segments, or as a secreted mucus. Even though research shows that C. variopedatus is a species complex miscategorized as a single species, all of the variants of this polychaete produce light, which has been investigated in terms of both physiology and biochemistry. Despite decades of study, there are still many questions about the luminescence reaction, and, as of yet, no clear function for light emission exists. This review summarizes the current knowledge on C. variopedatus luminescence in addition to briefly describing its morphology, life cycle and ecology. Possible functions for luminescence were discussed using observations of specimens found in Brazil, along with a comparison of previous studies of other luminescent organisms. Further study will provide a better understanding of how and why C. variopedatus produces luminescence, and purifying the protein and luciferin involved could lead to new bioanalytical applications, as this reaction is unique among all known luminescent systems.     

Synthesis of ferrocenyl-1,2-diketones and related compounds: Crystal and molecular structures of 1,2-diferrocenylethanedione and 1-ferrocenyl-2-(4-biphenylyl) ethanedione

Ferrocenyl-1,2-diketones FcCOCOR, 3, [Fc = (C₅H₅)Fe(C₅H₄)] can be prepared by oxidation of acylferrocenes FcCOCH₂R or, more efficiently, by oxidation of the isomeric ketones FcCH₂COR, 2. The ketones 2 are in turn readily synthesized from the salt (FcCH₂PPh₃)⁺I⁻ via the acylated salts [FcCH(COR)PPh₃]⁺I⁻. The haloacylferocenes FcCOCCl_x H_3−x (x = 1, 2, 3, of which the x = 2 example is synthetically equivalent to a diketone) are synthesized by Friedel—Crafts acylation of ferrocene using CCl_xH_3−xCOCl/AlCl₃, but the reaction proceeds via two parallel pathways, one giving the normal acyl derivatives FcCOCCl_xH_3−x and the other giving the reduced products FcCOCCl_x−1H_4−x. Two diketones FcCOCOFc 3b and FcCOCOC₆H₄Ph 3c have been structurally characterised by single-crystal X-ray diffraction.     

In Vivo Endoscopic Tissue Identification by Rapid Evaporative Ionization Mass Spectrometry (REIMS)

Gastrointestinal cancers are a leading cause of mortality, accounting for 23 % of cancer‐related deaths worldwide. In order to improve outcomes from these cancers, novel tissue characterization methods are needed to facilitate accurate diagnosis. Rapid evaporative ionization mass spectrometry (REIMS) is a technique developed for the in vivo classification of human tissue through mass spectrometric analysis of aerosols released during electrosurgical dissection. This ionization technique was further developed by utilizing surface induced dissociation and was integrated with an endoscopic polypectomy snare to allow in vivo analysis of the gastrointestinal tract. We tested the classification performance of this novel endoscopic REIMS method in vivo. It was shown to be capable of differentiating between healthy layers of the intestinal wall, cancer, and adenomatous polyps based on the REIMS fingerprint of each tissue type in vivo.     

Comparison of phantom materials for use in quality assurance of microbeam radiation therapy

Microbeam radiation therapy (MRT) is a promising radiotherapy modality that uses arrays of spatially fractionated micrometre‐sized beams of synchrotron radiation to irradiate tumours. Routine dosimetry quality assurance (QA) prior to treatment is necessary to identify any changes in beam condition from the treatment plan, and is undertaken using solid homogeneous phantoms. Solid phantoms are designed for, and routinely used in, megavoltage X‐ray beam radiation therapy. These solid phantoms are not necessarily designed to be water‐equivalent at low X‐ray energies, and therefore may not be suitable for MRT QA. This work quantitatively determines the most appropriate solid phantom to use in dosimetric MRT QA. Simulated dose profiles of various phantom materials were compared with those calculated in water under the same conditions. The phantoms under consideration were RMI457 Solid Water (Gammex‐RMI, Middleton, WI, USA), Plastic Water (CIRS, Norfolk, VA, USA), Plastic Water DT (CIRS, Norfolk, VA, USA), PAGAT (CIRS, Norfolk, VA, USA), RW3 Solid Phantom (PTW Freiburg, Freiburg, Germany), PMMA, Virtual Water (Med‐Cal, Verona, WI, USA) and Perspex. RMI457 Solid Water and Virtual Water were found to be the best approximations for water in MRT dosimetry (within ±3% deviation in peak and 6% in valley). RW3 and Plastic Water DT approximate the relative dose distribution in water (within ±3% deviation in the peak and 5% in the valley). PAGAT, PMMA, Perspex and Plastic Water are not recommended to be used as phantoms for MRT QA, due to dosimetric discrepancies greater than 5%.     

Adsorption and diffusion of argon in disordered nanoporous carbons

Application-specific optimization of disordered nanoporous carbons remains a formidable challenge due to the difficulty in accurately characterizing their microstructures with current empirical methods. Using molecular simulation techniques, we investigated the adsorptive and diffusive behavior of argon in three models of disordered nanoporous carbons. We found that the structural and morphological differences between these models gave rise to distinct phenomenological properties. The adsorptive behavior of argon in both the low and high pressure regimes was enhanced dramatically in the models with more crystalline microstructures. As for dynamic properties, we found that the adsorbent’s structure and energetic topology significantly alters the rates of diffusion as well as the characteristics of the underlying diffusion mechanisms.     

Studies toward the total synthesis of eletefine: an efficient construction of the AB ring system

Synthetic studies toward eletefine, a novel stephaoxocane alkaloid, were undertaken in an attempt to provide a general methodology to aid in the synthesis of other novel stephaoxocanes. An efficient construction of the AB ring system with increased functionality is described which presents a flexible approach to synthesizing the C and D rings of eletefine.