Dynamic range and mass accuracy of wide-scan direct infusion nanoelectrospray fourier transform ion cyclotron resonance mass spectrometry-based metabolomics increased by the spectral stitching method

Direct infusion nanoelectrospray Fourier transform ion cyclotron resonance mass spectrometry (DI nESI FT-ICR MS)offers high mass accuracy and resolution for analyzing complex metabolite mixtures. High dynamic range across a wide mass range, however, can only be achieved at the expense of mass accuracy, since the large numbers of ions entering the ICR detector induce adverse spacecharge effects. Here we report an optimized strategy for wide-scan DI nESI FT-ICR MS that increases dynamic range but maintains high mass accuracy. It comprises the collection if multiple adjacent selected ion monitoring (SIM) windows that are stitched together using novel algorithms. The final SIM-stitching method, derived from several optimization experiments, comprises 21 adjoining SIM windows each of width m/z 30 (from m/z 70 to 500; adjacent windows overlap by m/z 10) with an automated gain control (AGC) target of 1 105 charges. SIMstitching and wide-scan range (WSR; Thermo Electron)were compared using a defined standard to assess mass accuracy and a liver extract to assess peak count and dynamic range. SIM-stitching decreased the maximum mass error by 1.3- and 4.3-fold, and increased the peak count by 5.3- and 1.8-fold, versus WSR (AGC targets of 1 x 105 and 5 x 105, respectively). SIM-stitching achieved an rms mass error of 0.18 ppm and detected over 3000 peaks in liver extract. This novel approach increases metabolome coverage, has very high mass accuracy, and at 5.5 min/sample is conducive for high- throughput metabolomics

Calcium-phosphorus interactions at a nano-structured silicate surface

Nano-structured calcium silicate (NCS), a highly porous material synthesized by controlledprecipitation from geothermal fluids or sodium silicate solution, was developed as filler for use inpaper manufacture. NCS has been shown to chemisorb orthophosphate from an aqueous solutionprobably obeying a Freundlich isotherm with high selectivity compared to other commonenvironmental anions. Microanalysis of the products of chemisorption indicated there wassignificant change from the porous and nano-structured morphology of pristine NCS to fibrous andcrystalline morphologies and non-porous detritus. X-ray diffraction analysis of the crystallineproducts showed it to be brushite, CaHPO4?2H2O, while the largely x-ray amorphous componentwas a mixture of calcium phosphates. A two-step mechanism was proposed for the chemisorption ofphosphate from an aqueous solution by NCS. The first step, which was highly dependent on pH, wasthought to be desorption of hydroxide ions from the NCS surface. This was kinetically favoured atlower initial pH, where the predominant form of phosphate present was H2PO4-, and led to decreasedphosphorus uptake with increasing pH. The second step was thought to be a continuingchemisorption process after stabilization of the pH-value. The formation of brushite as the primarychemisorption product was found to be consistent with the proposed mechanism

Carbon Sequestration in Biogenic Magnesite and Other Magnesium Carbonate Minerals

The stability and longevity of carbonate minerals make them an ideal sink for surplus atmospheric carbon dioxide. Biogenic magnesium carbonate mineral precipitation from the magnesium-rich tailings generated by many mining operations could offset net mining greenhouse gas emissions, while simultaneously giving value to mine waste products. In this investigation, cyanobacteria in a wetland bioreactor enabled the precipitation of magnesite (MgCO3), hydromagnesite [Mg5(CO3)4(OH)2·4H2O], and dypingite [Mg5(CO3)4(OH)2·5H2O] from a synthetic wastewater comparable in chemistry to what is produced by acid leaching of ultramafic mine tailings. These precipitates occurred as micrometer-scale mineral grains and microcrystalline carbonate coatings that entombed filamentous cyanobacteria. This provides the first laboratory demonstration of low temperature, biogenic magnesite precipitation for carbon sequestration purposes. These findings demonstrate the importance of extracellular polymeric substances in microbially enabled carbonate mineral nucleation. Fluid composition was monitored to determine carbon sequestration rates. The results demonstrate that up to 238 t of CO2 could be stored per hectare of wetland/year if this method of carbon dioxide sequestration was implemented at an ultramafic mine tailing storage facility. The abundance of tailings available for carbonation and the anticipated global implementation of carbon pricing make this method of mineral carbonation worth further investigation

Advanced biofilm staining techniques for TEM and SEM in geomicrobiology: Implications for visualizing EPS architecture, mineral nucleation, and microfossil generation

Microbial biofilms and mats have long been studied for their role in mineral precipitation reactions in natural environments. Scanning electron microscopy (SEM) is often used to characterize biofilms and their associated precipitates, however, conventional SEM sample preparation methods do not typically preserve the structure of the extracellular polymeric substances (EPS), which account for a large portion of biofilm material and play crucial roles in biofilm function and mineral nucleation. In the present investigation, EPS preservation and visualization using transmission electron microscopy (TEM) was explored using three biofilm fixation and staining protocols. Although aspects of these protocols were developed for preserving complex eukaryotic tissue samples, the heterogeneous, three-dimensional nature of biofilms make them suitable candidates for these sample processing techniques. The results suggest that cryofixation provides the best preservation of cyanobacteria-dominated biofilm structures. A staining protocol including six different pre-embedding stains allowed for TEM visualization of the EPS matrix that encompasses biofilm cells and precipitates. Of the stains used, uranyl acetate appears to be important in avoiding biofilm deformation during sample processing. Using these staining protocols, cell-EPS-mineral relationships were observed, including the precipitation of hydromagnesite [Mg₅(CO₃)₄(OH)₂·4H₂O] on the EPS adjacent to the exterior of cyanobacteria filaments. Beachrock-associated biofilms were characterized using both TEM of ultrathin sections, as well as SEM of resin embedded osmium stained biofilms prepared as petrographic thin sections. Combining these two approaches enabled characterization of both the micrometer-scale cell-carbonate mineral contacts, as well as the larger scale microbial colony-mineral cement relationships. These results suggest that sample preparation techniques developed for rapid preservation of eukaryotic tissue samples can be used to preserve and characterize biofilm architecture. These findings have applications to understanding mineral nucleation in biofilms, and the preservation of biofilms as microfossils in the rock record

"Hero Imagery" - Are there performance advantages associated with imagining yourself as your favourite athlete?

Objectives: This study examined whether there are performance advantages associated with a single bout of imagery when imagining yourself ‘as your favourite athlete’, or imagining yourself performing a strength-based task. Design: A blind 2 (Imagery ability: high, low) x 3 (imagery condition: self, “hero”, control) mixed factorial design was used. Methods: Participants (n = 17 male; Mage = 19.7 ± 2.7) completed the Sport Imagery Ability Questionnaire then viewed a standardised video demonstrating the grip strength (GS) task. Three baseline trials separated by one minute were then executed. Three imagery scripts (control, self, hero) were then presented to participants via an MP3 player in a counterbalanced order (an interval of 1-minute was provided between each condition). The conclusion of each imagery script prompted participants to perform the GS task. Performance in each condition was conceptualised as delta change scores (Imagery condition – baseline average). Results: No main effects were present but there was a group x condition interaction (F(2,28) = 4.27, p = .02. ƞ_p^2= .23. The interaction suggests that for individuals with high imagery ability, simply “doing the imagery that they already do” is preferable compared to a scripted self- or hero-imagery condition. For individuals with a low imagery ability, a simple script whether that is self- or hero- based may enhance strength performance, compared to “what they already do”. Conclusion: Imagery ability may influence the effectiveness of a brief imagery intervention. Further examination of processes and outcomes associated with “hero-imagery” is recommended

Offsetting of CO₂ emissions by air capture in mine tailings at the Mount Keith Nickel Mine, Western Australia: Rates, controls and prospects for carbon neutral mining

The hydrated Mg-carbonate mineral, hydromagnesite [Mg₅(CO₃)₄(OH)₂•4H₂O], precipitates within mine tailings at the Mount Keith Nickel Mine, Western Australia as a direct result of mining operations. We have used quantitative mineralogical data and δ¹³C, δ¹⁸O and F¹⁴C isotopic data to quantify the amount of CO₂fixation and identify carbon sources. Our radiocarbon results indicate that at least 80% of carbon stored in hydromagnesite has been captured from the modern atmosphere. Stable isotopic results indicate that dissolution of atmospheric CO₂ into mine tailings water is kinetically limited, which suggests that the current rate of carbon mineralization could be accelerated. Reactive transport modeling is used to describe the observed variation in tailings mineralogy and to estimate rates of CO₂ fixation. Based on our assessment, approximately 39,800 t/yr of atmospheric CO₂ are being trapped and stored in tailings at Mount Keith. This represents an offsetting of approximately 11% of the mine's annual greenhouse gas emissions. Thus, passive sequestration via enhanced weathering of mineral waste can capture and store a significant amount of CO₂. Recommendations are made for changes to tailings management and ore processing practices that have potential to accelerate carbonation of tailings and further reduce or completely offset the net greenhouse gas emissions at Mount Keith and many other mines