Solvent Storage Research Articles

The Effects of Sampling and Storage Conditions on the Metabolite Profile of the Marine Sponge Geodia barretti.

Geodia barretti is a deep-sea marine sponge common in the north Atlantic and waters outside of Norway and Sweden. The sampling and subsequent treatment as well as storage of sponges for metabolomics analyses can be performed in different ways, the most commonly used being freezing (directly upon collection or later) or by storage in solvent, commonly ethanol, followed by freeze-drying. In this study we therefore investigated different sampling protocols and their effects on the detected metabolite profiles in liquid chromatography-mass spectrometry (LC-MS) using an untargeted metabolomics approach. Sponges (G. barretti) were collected outside the Swedish west coast and pieces from three sponge specimens were either flash frozen in liquid nitrogen, frozen later after the collection cruise, stored in ethanol or stored in methanol. The storage solvents as well as the actual sponge pieces were analyzed, all samples were analyzed with hydrophilic interaction liquid chromatography as well as reversed phase liquid chromatography with high resolution mass spectrometry using full-scan in positive and negative ionization mode. The data were evaluated using multivariate data analysis. The highest metabolite intensities were found in the frozen samples (flash frozen and frozen after sampling cruise) as well as in the storage solvents (methanol and ethanol). Metabolites extracted from the sponge pieces that had been stored in solvent were found in very low intensity, since the majority of metabolites were extracted to the solvents to a high degree. The exception being larger peptides and some lipids. The lowest variation between replicates were found in the flash frozen samples. In conclusion, the preferred method for sampling of sponges for metabolomics was found to be immediate freezing in liquid nitrogen. However, freezing the sponge samples after some time proved to be a reliable method as well, albeit with higher variation between the replicates. The study highlights the importance of saving ethanol extracts after preservation of specimens for biology studies; these valuable extracts could be further used in studies of natural products, chemosystematics or metabolomics.

Degradation of 1-phenyl-2-propanone during long-term storage: useful information for methamphetamine impurity profiling

1-Phenyl-2-propanone (P2P) is a main precursor of methamphetamine. The authors investigated the formation of P2P degradation products during long-term storage and the factors that affected P2P degradation. Samples of neat P2P, 1 mg/mL P2P in methanol and in ethyl acetate were prepared. These samples were stored at room temperature or 4 °C for 1, 3, and 6 months; then the samples were analyzed by gas chromatography–mass spectrometry. A similar experiment (but stored only for 1 month) was also performed for phenylacetylcarbinol. Neat P2P stored at room temperature gave degradation products after 3-month storage, and the degradation proceeded over the next 3 months. Benzaldehyde, benzoic acid, benzyl acetate, 1-phenyl-1,2-propanedione, phenylacetylcarbinol, 1-acetoxy-1-phenyl-2-propanone, and 1,1-diphenylacetone were identified as degradation products after 6-month storage. The degradation was prevented incompletely by storage at 4 °C and almost completely by storage in the organic solvents. Neat phenylacetylcarbinol stored at room temperature was remarkably decomposed. Benzaldehyde, benzoic acid, 1-phenyl-1,2-propanedione, and 1-acetoxy-1-phenyl-2-propanone were regarded as the degradation products. The degradation was prevented incompletely by storage at 4 °C and almost completely by storage in the organic solvents. These results suggested that P2P and phenylacetylcarbinol were oxidized by oxygen in air and that the organic solvents inhibited the oxidation. P2P was presumed to be initially oxidized to phenylacetylcarbinol, then it was converted to benzaldehyde, benzoic acid, 1-phenyl-1,2-propanedione, and 1-acetoxy-1-phenyl-2-propanone. Production of phenylacetylcarbinol from P2P is useful information for methamphetamine impurity profiling because phenylacetylcarbinol is a precursor of ephedrines, the other methamphetamine precursors.

Explosion Suppression Control Technology of FG Strong Adsorption Material for Leakage / Flowing Fire of Hazardous Chemicals

At present, in the process of production, operation, storage, transportation, use and disposal of petroleum and chemical solvents, major environmental disasters, such as fire, explosion and personal injury caused by leakage, are common. The disasters are often aggravated by the backward emergency disposal technology and improper operation. FG polymer is an inert, strong adsorptive material for hydrophobic substance, and the material is safe itself and non-toxic to aquatic fish and plants. In this study, FG polymer is tested in fire-fighting, explosion suppression and controling flowing fire. The result shows that the FG strong adsorption material can quickly absorb oil spill and leakage of hazardous chemicals on water and land surface, therefore controlling and eliminating the spread of flowing fire, isolating oxygen, extinguishing fire, suppressing explosion, and effectively avoiding environmental pollution. This technology can replace the backward emergency disposal methods such as oil spill dispersant, PP absorbent felt. With this technology being applied in emergence rescue, the disposal cost can be reduced by more than 50%, additionally the abilities of risk prevention, hidden danger elimination, and accident suppression can be enhanced significantly.

Effect of light on degradation of glaucine during storage in organic solvents

Effect of light on degradation of glaucine during storage in organic solvents

Bioenhanced back diffusion and population dynamics of Dehalococcoides mccartyi strains in heterogeneous porous media

Diffusion, sorption-desorption, and biodegradation influence chlorinated solvent storage in, and release (mass flux) from, low-permeability media. Although bioenhanced dissolution of non-aqueous phase liquids has been well-documented, less attention has been directed towards biologically-mediated enhanced diffusion from low-permeability media. This process was investigated using a heterogeneous aquifer cell, packed with 20–30 mesh Ottawa sand and lenses of varying permeability (1.0 × 10−12-1.2 × 10−11 m2) and organic carbon (OC) content (<0.1%–2%), underlain by trichloroethene (TCE)-saturated clay. Initial contaminant loading was attained by flushing with 0.5 mM TCE. Total chlorinated ethenes removal by hydraulic flushing was then compared for abiotic and bioaugmented systems (KB-1® SIREM; Guelph, ON). A numerical model incorporating coupled diffusion and (de)sorption facilitated quantification of bio-enhanced TCE release from low-permeability lenses, which ranged from 6% to 53%. Although Dehalococcoides mccartyi (Dhc) 16S rRNA genes were uniformly distributed throughout the porous media, strain-specific distribution, as indicated by the reductive dehalogenase (RDase) genes vcrA, bvcA, and tceA, was influenced by physical and chemical heterogeneity. Cells harboring the bvcA gene comprised 44% of the total RDase genes in the lower clay layer and media surrounding high OC lenses, but only 2% of RDase genes at other locations. Conversely, cells harboring the vcrA gene comprised 50% of RDase genes in low-permeability media compared with 85% at other locations. These results demonstrate the influence of microbial processes on back diffusion, which was most evident in regions with pronounced contrasts in permeability and OC content. Bioenhanced mass transfer and changes in the relative abundance of Dhc strains are likely to impact bioremediation performance in heterogeneous systems.

Tailored solar field and solvent storage for direct solvent regeneration: A novel approach to solarise carbon capture technology

For effective greenhouse gas (GHG) emission reduction, solvent-based post-combustion carbon capture (PCC) is the most recognized remedy option worldwide. Due to the very high thermal energy demand of this technology and the potential impact on the power production, solar-assisted PCC (SPCC) was proposed to offset part of this energy penalty. However this option is far from commercialization readiness, because of the solar intermittence and the costly thermal energy storage (TES).This paper promotes a dynamic carbon capture using innovative solar collector field (SCF). By eliminating the complex and costly stripper/s from the conventional PCC, we propose regenerating the solvent directly in the SCF and proportionally to the solar thermal energy gain. We also propose an underground solvent storage system instead of TES to buffer in-between the dynamic solvent regeneration via SCF and the steady-state absorption process in the absorber/s. For capturing 1.5 million tonneCO2/y from a 660 MWe coal-fired power plant in three representative locations in Australia, it is found that the equivalent annual cost of desorption is quite reasonable, particularly at higher solar multiples (SM). For SM = 1.5, the levelized cost of desorption is the lowest in Townsville ($ 12.34 per tonneCO2), followed by Sydney ($16.31 per tonneCO2), while Melbourne would need larger SCF (SM = 2.0) to lower the levelized cost of desorption ($ 22.52 per tonneCO2). These costs are calculated irrespective of the credits gained from steam preservation for power production and the resulted positive impact on the overall life cycle analysis. Noting the trajectory trend of GHG reduction cost, this novel approach in solarising carbon capture may bring SPCC to the competitive advantage in short/mid-term.

Accumulation of DNAPL waste in subsurface clayey lenses and layers

Chlorinated solvents like trichloroethylene (TCE) and tetrachloroethylene (PCE) are prevalent groundwater contaminants being detected more than half of the Superfund Sites. They are introduced into the subsurface due to improper disposal of hazardous wastes containing these chlorinated dense non-aqueous phase liquids (DNAPL). DNAPL wastes sink in the subsurface and form pools on clay layers. Further transport into the underlying clay layer is dominated by diffusion due to the low permeability of these soils and results in accumulation of contaminants therein overtime through diffusion. However, field evidence reported that mass storage of solvents in such zones was higher than what can be attributed to simple diffusion. To evaluate this finding, mass storage of TCE in a hypothetical aquitard after 30 years of diffusion was calculated. The diffusion coefficient reported in the field study resulted in mass storage of 137.7 g in this hypothetical aquitard whereas the mass calculated using the measured diffusion coefficient of TCE from pure solvent into water-saturated clayey soil was 25–65% of it (35.0–89.4 g). The calculated mass storage was even lower (8.2 g) if the measured diffusion coefficient of TCE from DNAPL waste into waste-contacted soil was used. So, mass of TCE accumulated through sole diffusion was not able to explain the one observed in the field. This excess mass in the field might be the mass of DNAPL entered into the cracks which were reported to form in clay layers as a result of the direct contact between water saturated clay and DNAPL waste. Mass of TCE in the cracks was calculated using reported average crack size and an assumed crack depth, and it appeared that cracks filled with DNAPL could increase the stored mass up to a minimum of 334 g which could easily account for the enhanced mass storage observed in the field.

Deploying gas power with CCS: The role of operational flexibility, merit order and the future energy system

Combined cycle gas turbine (CCGT) power plants are an important part of many electricity systems. By fitting them with carbon capture their CO2 emissions could be virtually eliminated. We evaluate CCGT plants with different variations of post combustion capture using amine solvents, covering a range of options, including solvent storage, partial capture and shifting the energy penalty in time. The analysis is based on the UK electricity system in 2025. The behaviour of individual CCGT plants is governed by the plant’s place in the merit order and to a lesser extent by CO2 reduction targets for the electricity system. In the UK, CCGT plants built from 2016 onwards will emit ∼90% of the CO2 emissions of the whole CCGT fleet in 2025. The typical ‘base case’ CCGT plant with capture is designed to capture 90% of the CO2 emissions and to operate dynamically with the power plant. Downsizing the capture facility could be attractive for low-merit plants, i.e. plants with high short-run marginal costs. Solvent storage enables electricity generation to be decoupled in time from the energy penalty associated with carbon capture. Beyond a few minutes of solvent storage, substantial tanks would be needed. If solvent storage is to play an important role, it will require definitions of ‘capture ready’ to be expanded to ensure sufficient land is available.

Operating flexibility of natural gas combined cycle power plant integrated with post-combustion capture

Highly flexible, low-carbon electricity generation with gas-fired power stations with CO2 capture addresses the challenges of balancing variable renewable electricity supply in low carbon electricity systems. This detailed technical assessment of flexible CO2 capture plant operation at natural gas combined cycle power stations with post-combustion CO2 capture examines the operating strategies of capture plant by-pass and interim solvent storage. We show that solvent storage allows expanding the operating envelope of gas fired CCS power stations by +/-10%. Further we demonstrate that electricity and CO2 output can be decoupled for up to 3 h with approx. 6000 m3 of additional solvent inventory for the purpose of reducing the CO2 flow variability in downstream transportation and storage systems, mitigating potentially deleterious injection well effects. 1 h of solvent storage operation at full load can be regenerated in as fast as 2.1 h during continuous operation of the CCS power plant by choosing a controlled steam extraction strategy from the combined cycle and thus throttling the low pressure turbine. The electricity output penalty associated with the delayed regeneration of solvent ranges from 420–450 kWh/tCO2 with this strategy, which compares to 380 kWh/tCO2 for immediate regeneration at full load design conditions. By deploying a novel variable speed drive integrally geared compressor model, we find that, unlike previously thought, an uncontrolled steam extraction strategy, referred as a floating steam extraction strategy, can lead to choking of the CO2 compressor during additional solvent regeneration. A pre-compression stage would be necessary under this extraction strategy to restore feasible operation of the main CO2 compressor, and makes this strategy more complex to implement. When decreasing the desorber pressure at part-load care must, therefore, be taken to respect the operating limits of the compressor. To assist with the use of rigorous plant performance data in wider electricity system models, correlations for key performance parameters of NGCC-CCS power plants at varying load, with capture by-pass and additional solvent regeneration are provided.

Hardness and fracture toughness of resin-composite materials with and without fibers

ObjectiveTo investigate the surface micro-hardness (VHN) and fracture toughness (KIC) of resin-composites, with and without incorporated short fibers, after solvent storage. MethodsThree resin-composites incorporating fibers, additional to particle reinforcement, were examined: everX™, NovoPro Fill™ and NovoPro Flow™. Four composites were used as controls, with only particle reinforcement: Filtek bulk Fill™, Filtek bulk one™, Filtek XTE™, and Filtek Flow XTE™. For hardness measurement, materials were cured in 2mm thick molds for 20s by a LED source of average irradiance 1.2W/cm2. Specimens (n=6/group) were stored dry for 1h and then in either water or 75% ethanol/water for 1h, 1 day and 30 days at 37±1°C. Vickers hardness was measured under a load of 300g for 15s. For fracture toughness (KIC) measurements, single-edge-notched specimens (n=6/group) were prepared: (32×6×3mm) for 3-point bending and stored for 1 and 7 days in water at 37°C. Fractured surfaces of fiber-reinforced composite were examined by scanning electron microscopy (SEM). VHN data were analyzed using three-way ANOVA, one-way ANOVA and the Tukey post hoc test (p≤0.05). KIC data were analyzed by two-way ANOVA and one-way ANOVA and the Tukey post hoc test (p≤0.05). An independent t-test was used to detect differences (α=0.05) in KIC between stored groups for each material. ResultsVHN decreased for all composites with storage time in both solvents, but more appreciably in 75% ethanol/water (an average of 20%). KIC ranged from 2.14 (everX Posterior) to 0.96 NovoPro Flow) MPa.m0.5. The longer storage period (7 days) had no significant effect on this property relative to 1 day storage. SignificanceReinforcement with short fibers, and possibly matrix compositional differences, significantly enhanced the fracture toughness of EVX. However, for nano-fiber containing composites, there were no evident beneficial effects upon either their fracture toughness or hardness compared to a range of control composites. Water storage for 7 days of all these resin-composites produced no significant change in their KIC values, relative to 1 day storage.

Comparison of CLR and SS Flexible Systems for Post-Combustion CO2 Removal in a NGCC Power Plant

Carbon dioxide is essential to life on Earth, however its concentration in the atmosphere has significantly increased since pre-industrial era, causing global warming and climate change. To reduce these effects, the Paris Climate Agreement has established greenhouse gas emissions reduction targets, which can be achieved by decarbonizing energy-intensive industries as electricity production. Post-combustion removal of carbon dioxide can be obtained by employing aqueous solutions of amines - in most of the cases MonoEthanolAmine (MEA) is used - which absorb this acid gas from the flue gas streams and are then regenerated and recycled. They are widely employed, though being characterized by several drawbacks, as the high energy requirement at the reboiler of the regeneration section. Therefore, though adding Carbon Capture & Storage (CCS) to a power plant makes the production of electricity more advantageous from an environmental point of view, its operation represents an economic loss for the plant. Possible ways of minimizing the economic disadvantages due to the carbon dioxide removal section include running this section in flexible mode, on the basis of the price of electricity which varies from hour to hour and from day to day. The Capture Level Reduction (CLR) and the Solvent Storage (SS) methods are two possible solutions for flexible operation. This work focuses on the purification of a flue gas stream from a power plant fed with natural gas and performs simulations and techno-economic analyses of the CLR and SS modes, taking into account also the possible application of a carbon tax. By analysing the obtained results a comparison between the two options is carried out, and the best operating mode is determined.

Formation and surface-stabilizing contributions to bare nanoemulsions created with negligible surface charge

The stabilization of nanoemulsions, nanosized oil droplets dispersed in water, is commonly achieved through the addition of surfactants and polymers. However, nanoemulsions in the absence of emulsifiers have been observed to acquire a significant negative charge at their surface, which ultimately contributes to their stability. While the source of this negative charge is disputed to this day, its presence is taken as an inherent property of the aqueous-hydrophobic interface. This report provides a look at the molecular structure and bonding characteristics of bare aqueous-hydrophobic nanoemulsion interfaces. We report the creation of bare nanoemulsions with near zero surface charge, which are marginally stable for several days. The process of creating these low-charge nanoemulsions (LCNEs) required rigorous cleaning procedures and proper solvent storage conditions. Using vibrational sum-frequency scattering spectroscopy, we measure the structure and bonding of the interfacial aqueous and hydrophobic phases. The surfaces of these LCNE samples possess a measurable free OH vibration, not found in previous studies and indicative of a clean interface. Tuning the nanoemulsion charge through addition of anionic surfactants, modeling potential surface-active contaminants, we observe the free OH to disappear and a reorientation of the interfacial hydrophobic molecules at micromolar surfactant concentrations. Notably, the free OH vibration provides evidence for stronger dispersion interactions between water molecules and the hydrophobic phase at the LCNE surface compared with similar planar water-alkane interfaces. We propose the stronger bonding interactions, in addition to an ordered interfacial aqueous layer, contribute to the delayed droplet coalescence and subsequent phase separation.

Operating the CO2 absorption plant in a post-combustion unit in flexible mode for cost reduction

Carbon dioxide greatly contributes to climate change and its emissions must be limited. Combustion of fossil fuels in power plants to produce electricity generates the largest amount of CO2 released into the atmosphere, therefore application of Carbon Capture and Storage (CCS) to this sector would help in reducing the emissions of this acid gas.CO2 absorption with aqueous amines is the most common capture technology for post-combustion CO2 removal and is characterized by high energy requirements, mainly for CO2 release from the solvent and compression of the obtained rich-CO2 stream. For this reason operating the CCS system in a power plant significantly reduces the power output and, consequently, the revenues from selling electricity.In order to deal with this issue while maintaining low carbon dioxide emissions, flexible operation may be applied.In this work, a detailed analysis of the application of the solvent storage mode for flexible operation of the CO2 removal section of a natural gas combined cycle power plant has been performed.Simulations in ASPEN Plus®, properly customized for the description of the system, and a techno-economic model created by the GASP group of Politecnico di Milano have been run to find the best solution. The variation of price of electricity from hour to hour for key days and for the overall year have been considered. Different values of carbon tax to be applied have been also taken into account.

Operating Flexibility of Natural Gas Combined Cycle Power Plant Integrated with Post-Combustion Capture

This study reports key findings from a rigorous technical assessment of the performance of a natural gas fired power station fully integrated with a post-combustion MEA based capture unit. Behaviour at full load and at part load, during solvent storage operation and during regeneration of previously stored rich solvent, is characterised. Two different part load power cycle and capture unit control strategies are assessed during additional regeneration of stored solvent using alternative steam extraction strategies: (1) floating IP/LP crossover pressure; and (2) throttled IP/LP crossover. In practise these strategies could be used in combination. In contrast to previous literature the operating limits are described in detail. Additionally, a variable speed integrally geared centrifugal compressor model is deployed to predict the off design performance and operating limits of the compression unit.

Low-cost and convenient ballpoint tip-protected liquid-phase microextraction for sensitive analysis of organic molecules in water samples

Simplification and miniaturization in analytical procedures are highly preferred by analysts and other researchers. In this study, a low-cost, convenient and efficient liquid-phase microextraction method, termed ballpoint tip-protected liquid-phase microextraction (BT-LPME), was established. The bullet-shaped BT possessed a hollow cavity of several microliters for solvent storage and an opening tail for solute extraction. Magnetic field-induced BT spinning significantly accelerated the extraction process. By virtue of the adhesion between a stainless steel sheath and an organic solvent, along with cave protection, finely stable storage of extractant was achieved even under high spinning speeds (>1000 rpm). The BT-LPME performance was evaluated by extracting five polycyclic aromatic hydrocarbons (PAHs) from aqueous solution, followed by gas chromatography-mass spectrometry (GCMS) analysis. Compared to static single drop microextraction (SDME), the BT-LPME method provided higher enrichments (128–173-fold) for the five PAHs. Good linearities (from 0.01∼0.05 μg L−1 to 50 μg L−1) with a regression coefficient (r2) ≥0.9993, as well as low limits of detection (LODs, 0.002–0.011 μg L−1) and limits of quantification (LOQs, 0.007–0.023 μg L−1), were obtained. Relative recoveries varied from 92.3% to 103.4% at three spiked levels of 0.1, 1 and 10 μg L−1. The BT-LPME technique was also successfully applied to the enrichment of other organic compounds, such as organophosphorus compounds, organochlorines and triazines.

Trade-offs in cost and emission reductions between flexible and normal carbon capture and sequestration under carbon dioxide emission constraints

Relative to “normal” amine-based post-combustion capture carbon and sequestration (CCS), flexible CCS adds a flue gas bypass and/or solvent storage system. Here, we focus on flexible CCS equipped with a solvent storage system. A primary advantage of flexible over normal CCS is increased reserve provision. However, no studies have quantified system-level cost savings from those reserves, which could drive the public benefits and rationale for policy support of flexible over normal CCS. Here, we quantify total power system costs, including generation, reserve, and capital costs, as well as carbon dioxide (CO2) emissions of generator fleets with flexible versus normal CCS. We do so under a moderate and strong CO2 emission limit. Relative to normal CCS, solvent storage-equipped flexible CCS reduces system-wide operational plus annualized CCS capital costs but increases system-wide CO2 emissions under the moderate limit, whereas it reduces system-wide costs and emissions under the strong limit. Under both limits, we find that reductions in reserve costs constitute 40–80% of the reductions in total operational costs with flexible CCS rather than normal CCS. Thus, flexible versus normal CCS deployment decisions pose cost and emissions tradeoffs to policymakers under a moderate emission limit as well as tradeoffs between near- and long-term policy objectives.

Techno-economic Evaluation of Flexible CCS Concepts in a CHP System

In the framework of the Finnish national CCSP R&D program, the possible positive effects of enhanced CO2 capture flexibility to a combined heat and power (CHP) system's net profitability was examined using optimization modelling, technology review and market scenario assessment. A system model was used to (i) compare economic performance of CO2 capture against fuel switch options under high emission allowance prices and (ii) quantify added value of flexible CO2 capture compared to conventional CO2 capture in the case CHP system. The supply side of the studied CHP system consists of coal- (PC and IGCC) and gas-fired (NGCC) CHP plants, a multi-fuel CHP plant with a circulating fluidized bed (CFB) boiler and an oil-fired district heating plant. The cash flow of the system is maximized assuming the optimal use of flexible pre- post- and oxy-combustion as CO2 capture concepts. Fuel-switch to bio-based renewable fuels is included as an alternative emission reduction technology. The market and fiscal environments reflect the current and anticipated situations in Finland. The flexible CO2 capture concepts assumed for the CHP plants include: (i) solvent storage in post-combustion capture (in PC, CFB & NGCC plants); (ii) hydrogen-rich gas storage in pre-combustion capture (in IGCC plants); and (iii) liquid oxygen storage in pre-combustion capture (in IGCC plants) and in oxy-combustion (in PC and CFB plants).

Flexible Operation Strategies for Coal- and gas-CCS Power Stations under the UK and USA Markets

The increased penetration of the intermittent renewable energy has increased the demand for flexible electricity supply. In this work, we evaluate four distinct strategies for flexible operation of CCS power plants: load following, solvent storage, exhaust gas by-pass and variable solvent regeneration (VSR) for coal- and gas-CCS power stations. With the aim to decoupling the power and capture plants in order to maximize profits, a multi-period dynamic optimisation problem was formulated and solved in the context of UK- and US-type markets. It was found that whilst the flexible operation strategies are strongly affected by the different markets, in all cases the variable solvent regeneration strategy was found to be the most profitable.

The Use Of Nigrosin Staining To Increase Brain Slice Contrast For Neuroanatomy Teaching

Although plastic models and electronic resources play an important role in demonstrating concepts in neuroanatomy, the study of human cadaver brain remains important where it is necessary to illustrate detail, spatial relationships, or in clinical teaching. The most difficult structures to visualize in embalmed brains are the deep cerebral and cerebellar nuclei due to the muted contrast after embalming. Many contrast enhancing staining protocols have several drawbacks including vague published protocols, variability of staining, the need for counter‐stains, or the length of the staining process. The purpose of our study was to evaluate several simple stains and protocols that would be effective in increasing grey matter contrast in brain slices.Whole brains were extracted from cadavers fixed with 65% ethanol, 10% propylene glycol, 4% phenol, 4% Dettol and 2% formalin after 10–12 months. Brains were postfixed with 10% formalin for 2–3 weeks before use. Two Plexiglas frames were constructed with horizontal (transverse) or vertical (coronal) slits spaced 1 cm apart to facilitate the cutting of serial sections. Serial transverse or coronal slices of brains were washed in tap water for 1 min prior to staining. Brain slices were stained in various dilutions of aqueous toluidine blue, cresyl violet, or Nigrosin. The contrast between grey and white matter was measured with a standardized camera and image analysis was performed on 8‐bit images using Image‐J. Overstained or understained sections were obtained with all protocols except Nigrosin. The most successful staining was obtained on sections stained with 0.5% aqueous Nigrosin for 15 min followed by clearing in a series of water and ethanol rinses. Sections were stored on a stainless steel tray covered with a moist cloth for various times before quantitative analyses was performed. The depth of staining was evaluated in sections cut tangential to the stained surface. The robustness of the staining was evaluated in sections stored in water, 2% aqueous glycerol, 100% ethanol, or 100% acetone for various times up to 4 wks.We conclude that the staining of brain sections with Nigrosin provides high contrast differentiation of grey and white matter. Interestingly, details of white matter tracts became visible but certain deep brain nuclei were consistently unstained. There was minimal fading of the staining after storage in organic and inorganic solvents indicating that the method may be useful for long term storage as both wet or plastinated specimens. Nigrosin staining of brain slices serves as a simple method to increase the visibility of brain structures for the study of neuroanatomy.Support or Funding InformationEducation Program in Anatomy, McMaster University

Optimisation and evaluation of flexible operation strategies for coal- and gas-CCS power stations with a multi-period design approach

Thermal power plants are increasingly required to balance power grids by compensating for the intermittent electricity supply from renewable energy resources. As CO2 capture and storage is integrated with both coal- and gas-fired power plants, it is vital that the emission mitigation technology does not compromise their ability to provide this high-value service. Therefore, developing optimal process operation strategies is vital to maximise both the value provided by and the profitability of these important assets. In this work, we present models of coal- and gas-fired power plants, integrated with a post-combustion CO2 capture process using a 30wt% monoethanolamine (MEA) solvent. With the aim to decoupling the power and capture plants in order to facilitate profit maximising behaviour, a multi-period dynamic optimisation problem was formulated and solved using these models. Four distinct scenarios were evaluated: load following, solvent storage, exhaust gas by-pass and variable solvent regeneration (VSR). It was found that for both coal- and gas-fired power plants, the VSR strategy is consistently the most profitable option. The performance of the exhaust by-pass scenario is a strong function of the carbon prices and is only selected at very low carbon prices. The viability of the solvent storage strategy was found to be a strong function of the capital cost associated with the solvent storage infrastructure. When the cost of the solvent tanks has been paid off, then the solvent storage scenario is 3.3% and 8% more profitable than the baseline for the pulverised coal and gas-fired power plants, respectively. Sensitivity analyses showed that, for all strategies, the flexibility benefit declined with reduced carbon and fuel prices, while a “peakier” electricity market, characteristic of one with significant quantities of intermittent renewables deployment, more significantly rewarded flexible operation.