The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AIM: The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery. METHODS: This was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin. RESULTS: Overall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P < 0.001). After adjustment, delay was not associated with a lower rate of complete resection (OR 1.18, 95% CI 0.90-1.55, P = 0.224), which was consistent in elective patients only (OR 0.94, 95% CI 0.69-1.27, P = 0.672). Longer delays were not associated with poorer outcomes. CONCLUSION: One in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

Carbon isotopes of graphite: Implications on fluid history

Stable carbon isotope geochemistry provides important information for the recognition of fundamental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elaboration of models for the global carbon cycle. Carbon isotope ratios in fluid-deposited graphite are powerful tools for unravelling the ultimate origin of carbon (organic matter, mantle, or carbonates) and help to constrain the fluid history and the mechanisms involved in graphite deposition. Graphite precipitation in fluid-deposited occurrences results from CO2- and/or CH4-bearing aqueous fluids. Fluid flow can be considered as both a closed (without replenishment of the fluid) or an open system (with renewal of the fluid by successive fluid batches). In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipitation and/or by changes in temperature affecting the fractionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13C or 12C enrichment (depending upon the dominant carbon phase in the fluid, CO2 or CH4, respectively). In open systems, in which carbon is episodically introduced along the fracture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of δ13C values when mixing of fluids or changes in the composition of the fluids are the mechanisms responsible for graphite precipitation

Vein graphite deposits: geological settings, origin, and economic significance

Graphite deposits result from the metamorphism of sedimentary rocks rich in carbonaceous matter or from precipitation from carbon-bearing fluids (or melts). The latter process forms vein deposits which are structurally controlled and usually occur in granulites or igneous rocks. The origin of carbon, the mechanisms of transport, and the factors controlling graphite deposition are discussed in relation to their geological settings. Carbon in granulite-hosted graphite veins derives from sublithospheric sources or from decarbonation reactions of carbonate-bearing lithologies, and it is transported mainly in CO2-rich fluids from which it can precipitate. Graphite precipitation can occur by cooling, water removal by retrograde hydration reactions, or reduction when the CO2-rich fluid passes through relatively low-fO2 rocks. In igneous settings, carbon is derived from assimilation of crustal materials rich in organic matter, which causes immiscibility and the formation of carbon-rich fluids or melts. Carbon in these igneous-hosted deposits is transported as CO2 and/or CH4 and eventually precipitates as graphite by cooling and/or by hydration reactions affecting the host rock. Independently of the geological setting, vein graphite is characterized by its high purity and crystallinity, which are required for applications in advanced technologies. In addition, recent discovery of highly crystalline graphite precipitation from carbon-bearing fluids at moderate temperatures in vein deposits might provide an alternative method for the manufacture of synthetic graphite suitable for these new applications

The Villalbeto de la Peña Meteorite: Raman Spectroscopy and Cathodoluminescence of Feldspar

This paper mainly focuses on the spatial distribution of plagioclase phases observed by Raman and spectra cathodoluminescence (CL) emission of in the Villalbeto de la Peña meteorite. Initially, we collected fragments countryside to determine the strewn field area and to perform spot chemical analyses by electron microprobe for the classification of the specimens (L6 Chondrite). Furthermore, the hyperspectral Raman mapping allow us identify amorphous Maskelynite feldspar in plagioclase micro-fissures since it is a molecular technique. The spectra CL emission bands observed at circa 290, 340, 390, 440, 510, 640 and 780 nm are characteristic in aluminosilicate lattices providing additional data on H+, OH- and H2O and Na+ self-diffusion along interfaces (290 nm), on strained Si—O bonds (340 and 650 nm), on [AlO4]° centers (380-390 nm and 420-440 nm), on O-—Si…M+ centers (510 nm) and on substitutional Fe3+ in aluminum positions (740—800 nm broad band). The CL and hyperspectral Raman techniques coupling demonstrates that the Villalbeto meteorite was shock-metamorphosed from the amorphous Maskelynite presence in Plagioclase fissures and from the strained Si—O bonds at room temperature

Spectrally-resolved luminescence of moganite from Mogan (Gran Canaria)

Moganite mineral (SiO2) was initially found in a near pure form in the locality-type of Mogan (Gran Canaria), it was accepted as a polymorph of silica at 1999 (IMA Nº 99-035). The moganite intergrowth within microcrystalline silica phases exhibits a wide-spread distribution at the Earth's surface. This silica polimorph contains as much as 4.5 wt.% H2O, and 0.5 wt.% CO2. Raman spectroscopy technique provides a measure of the moganite content in sample and its spatial variation. Luminescence techniques are increasingly employed on natural silica, hence, it is essential to examinate luminescence spectra emissions of silica aliquots, at different temperatures under different excitation agents, i.e.., here, protons for ion beam luminescence (IBL), X-irradiation for radioluminescence (RL) and heating for thermoluminescence (TL), to link defects and spectra luminescence emissions. We study well-characterized moganite-type specimens collected from fissures of rhyolitic ignimbrite flows in Mogan (Gran Canaria). Moganite rich aliquots were selected by hyperspectral Raman using a new ThermoFischer Raman Microscope with one micron spatial resolution and a laser source at 532 nm. Raman plots facilitates the selection of moganite-rich zones for further TL, RL and IBL analyses. Two spectra taken from an hyperspectral plot, straight-line belongs to a mixed zone in where quartz (465 cm-1) is more intense than moganite (502 cm-1) and dotted-line is moganite richer, as the case of previous spectra CL of Mogan moganite specimens. The TL glow curve at wavelength 320¿480 nm of a selected fresh moganite aliquot exhibits emis-sion centres compatible with volatile losses, i.e., water, hydroxyl groups, CO2 and CO gases, occurred as a two steps process, with high loss rates first between 323 and 453 K and then between 553 and 823 K, previous-ly reported in thermochemistry papers on moganite-type. In addition, the reversible phase transition from space group 12/a to Imab at approximately 570 K is located in the maximum of TL light emission. The spectra 3DRL plots of moganite-type recorded, from RT to 40K, in the high sensitivity spectrometer of the Sussex University exhibit a spectral RL broad band, moganite seems include many of the emission-defects catalogued for SiO2, e.g., 470-500nm [AlO4]º centers, 580nm Oxygen vacancy, 620-650nm Non-bridging oxygen ions; 700nm Substitutional Fe3+. During the RL measurements the lattice cryogenic stress enlarges pro-gressively the RL emission pointing to structural de-fects linked with bond-breakings, and probably, with a continuous reduction in the b axis and the concomi-tant rotation of tetrahedra about [100]. IBL profiles of moganite from RT to 80 K with spectra positions at circa 400nm, 500nm and 700nm. In this case, the pro-gressive cryogenic stress of the lattice enlarges also the ionoluminescence emission with a similar behaviour. The IBL profiles at RT were performed using H+ ions and a final profile after a sequential series of twenty IBL profiles at RT. This final profile shifts clearly to-wards the red/orange region during implantation since the dose dependence of the red/infrared emission as a function of integral dose. This peak shift can be ex-plained in terms of changes to the coordination sphere of the activator Fe3+ ion caused by the ion bombard-ment.Peer Reviewe