Saturated Phase Research Articles

Phosphorus recovery from municipal wastewater through struvite biomineralization using model gram-negative and gram-positive bacterial strains

The present study investigated struvite biomineralization potential of model gram-negative (Enterobacter cloacae) and gram-positive (Bacillus pumilus) bacterial strains in synthetic municipal wastewater. Both micro-organisms were able to precipitate struvite crystals and the growth pattern, change in pH, ammonium and phosphate ion concentration for both the cultures were comparable. The pH of the medium increased from 6.4 to 8.8 after 3 days of incubation when the cultures attained the saturation phase. The ammonium concentration increased from initial concentration of 40 mg/L to nearly 200 mg/L after 3 days of incubation for both the bacterial strains, whereas phosphate concentration decreased from initial 20 mg/L to 3.4 mg/L and 0.8 mg/L for Bacillus pumilus and Enterobacter cloacae respectively. The mechanism involved in struvite biomineralization was also explained in detail for Enterobacter cloacae and Bacillus pumilus. The precipitation of struvite by Enterobacter cloacae is due to biologically controlled mineralization while Bacillus pumilus mineralized struvite crystals through biologically induced mineralization mechanism. Results were further validated in real influent collected from a sequencing batch reactor of an influent treatment plant. Results demonstrated that Bacillus pumilus was able to precipitate crystals in real influent whereas no precipitation was observed by Enterobacter cloacae in real influent. This study gives an insight into bacterial biomineralization in wastewater to enable recovery of nutrients (phosphorus and nitrogen) and circularity in treatment plants. Further utilization of the recovered product as fertilizer can play a key role in contributing towards meeting global food security.

Toward efficient runs of nonlinear gyrokinetic simulations assisted by a convolutional neural network model recognizing wavenumber-space images

A neural-network based innovative model recognizing the wavenumber space images has been developed to accurately forecast when the saturation of turbulent heat fluxes commences, i.e., the saturation time, in nonlinear gyrokinetic simulations. The wavenumber space images of the perturbed distribution function are focused on, which better represent the characteristics of turbulence. The model exploiting the state-of-the-art convolutional neural network model is capable of detecting minuscule differences between the images. Once the wavenumber space image is fed into the developed model, it can quickly and almost perfectly classify which phase of the turbulence evolution in nonlinear gyrokinetic simulations the image is in: the linearly and nonlinearly growing phases and the saturation phase. It can also predict the simulation time at which the image was processed with significantly high accuracy. The model enables us to forecast the saturation time of the gyrokinetic simulation in question by feeding an image at an early stage of the simulation and receiving the degree of progress toward the saturation. The ability of the model makes it possible to easily search out a desirable initial condition that rapidly conducts the simulation to a saturation phase. Such a pre-prediction model is important for running long time simulations on a large scale supercomputer like Fugaku in view of the efficient use of computational resources. In order to improve the predictive capability for the simulation that is going to be performed, several prediction models are trained by data with different major instabilities. The best predictor is selected to be in use based on the result of the pre-performed linear stability calculation with low computational cost.

NMR T1-T2 Logging in Unconventional Reservoirs: Pore-Size Distribution, Permeability, and Reservoir Quality

The rock-pore textural properties in unconventional fine-grained reservoirs are much more complicated than in conventional reservoirs. In fine-grained rocks, this complexity derives from very small component grain assemblages (clay and silt fractions) and very small pores (nano- to microsizes) overprinted by diagenesis. It is further compounded by the pores being developed in intergranular, grain dissolution, and organic-associated-intragranular voids. Additionally, because locally sourced hydrocarbons in unconventional reservoirs, in contrast to migrated hydrocarbons that are present in conventional reservoirs, exist within similar pore sizes as the original saturating water phase, they create geometrically complex fluid distributions. These imply that, in the context of nuclear magnetic resonance (NMR) logging and petrophysical interpretation of tight oil unconventional reservoirs, pore size can no longer be considered a proxy for fluid type and vice versa. This means using T2 or T1 cutoffs may give inaccurate predictions. Current industry applications of NMR T1-T2 logging have demonstrated reliable interpretation of fluid types and water saturation. However, because petrophysical controls of advanced relaxation effects (such as surface and bulk fluid relaxation properties, pore-size distribution, and wettability) are not properly understood, these applications have been limited to estimating fluid saturations and have not been applied to estimating pore sizes. We extend the application of NMR T1-T2 measurements in tight oil unconventional reservoirs to model pore-size distributions by using apparent surface relaxivities and bulk relaxation times that have been jointly estimated from poro-fluid relaxations. To test these predictions, modeled pore-size distributions are compared to rock-pore textural properties from petrographic images of core samples. Such comparison allows us to derive insights into controls of mudstone reservoir quality (RQ) in conjunction with the impact of rock fabric endmembers (e.g., matrix-supported clays, grain-supported framework, diagenetic cements, and solid organic matter) on pore-size distributions. With these assumptions in mind, it follows, based on the Kozeny-Carman formulation, that unconventional rock permeability is reliably predicted from the NMR-based pore-size distributions. Furthermore, we deduce the impact of mineral assemblages in the Herron permeability model to infer influence on rock textural properties and ultimately predict permeability in limited data environments. This paper introduces a novel approach to estimate pore-size distributions per fluid type (water and hydrocarbons) from NMR T1-T2 measurements in unconventional reservoirs. Additionally, petrophysical controls of RQ, storage, and transport properties are derived from NMR-based pore-size distributions and mineral assemblages. This enables more reliable RQ and permeability assessment than typical T2- or T1-cutoff methods.

H2O saturated phase change threshold under molecular free path scale

The distribution of droplet and crystal is a key point in space engine plume flow research. Plume flow in vacuum may have great gas molecular free path, thus resulting in non-continuum and LTE (local thermal equilibrium). To obtain understanding on more general H2O phase change threshold, this article establishes a Gibbs phase calculation method. Internal pressure is proposed as a new concept to be distinguished from static pressure. The effect of vapor transitional temperature Tg−tran, vapor rotational temperature Tg−rot, phase change surface temperature Tneu and space characteristic length L on H2O phase change threshold is investigated. According to the results, phase change is more hard for non-continuum vapor than continuum one. Under TE (thermal equilibrium), the saturated phase change boundary line for H2O deflect toward low temperature side when the vapor number density is low. Under LTE, vapor can transform to water under the vapor number density below three phase point in LTE circumstances, which is impossible under TE situation. Tg−tran, Tg−rot and Tov shows different influence degree on the H2O phase change threshold, whose degree order from large to low is: vapor thermodynamics temperature Tg−ov, vapor transitional temperature Tg−tran and vapor rotational temperature Tg−rot.

Vapor-Liquid equilibria of the systems 1-octanol/nitrogen and 1-octanol/oxygen at pressures from 3 to 9 MPa and temperatures up to 613 K – Measured in a microcapillary with Raman spectroscopy

Vapor-liquid equilibria (VLE) of the binary systems 1-octanol/nitrogen and 1-octanol/oxygen were investigated at engine-relevant temperatures (T=303to613K for 1-octanol/nitrogen; T=303to493K for 1-octanol/oxygen) and pressures (p=3to9MPa). In order to acquire vapor–liquid equilibrium data, the pressurized fuel (1-octanol) and gas (nitrogen or oxygen) are mixed in a T-junction, where a Taylor flow of alternating liquid-phase and vapor-phase segments is formed. This segmented flow passes into a microcapillary that is inserted in a steal heating block, in which the equilibrium compositions of both phases are measured by in situ Raman spectroscopy. The measured Raman signal ratios are correlated to mole fractions by a calibration, performed in the unsaturated vapor and liquid phase regimes. The obtained VLE data agree well with the few available literature data points. The VLE compositions calculated by the Peng-Robinson equation of state (PR-EoS) and perturbed-chain statistical associating fluid theory (PC-SAFT) were furthermore compared to the here obtained experimental data. Both models show good agreement as indicated by the absolute average deviations (AAD), that are at maximum 9.5 % for the saturated vapor phase and 4.2 % for the saturated liquid phase.

Micro‐Scale Plasma Instabilities in the Interaction Region of the Solar Wind and the Martian Upper Atmosphere

AbstractWe present results, obtained by several instruments onboard NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, that show that the interaction region of the solar wind and the Martian upper atmosphere coincides with intense plasma wave activity. The turbulence region features nonlinear structures, identified as ion phase‐space holes and double layers, that emerge in the saturation phase of instabilities in the ion‐acoustic frequency range. One‐dimensional particle‐in‐cell simulations suggest that the waves and the nonlinear structures are very effective in coupling the flowing solar wind and the Martian plasma. Specifically, the simulations show that the magnetic field‐aligned component of the solar wind protons decelerates by about 20% in temporal and spatial scales of the orders of ∼100 ms and several kilometers, respectively. The results thus suggest that the waves may play an important role in the interaction region.

Forecasting internet diffusion in Italy based on the “.it” domain names metrics

Purpose The aim of this study is to examine the trend over time of the demand for .it domain names.This study first assesses whether there is a phase of growth and expansion or at a point of saturation. Second, this research can be useful also to compare researches that have considered other internet metrics and other models. Design/methodology/approach This paper describes the forecasting methods used to analyze the internet diffusion in Italy. The domain names under the country code top-level domain “.it” have used as metrics. To predict domain names .it the seasonal auto regressive integrated moving average (SARIMA) model and the Holt-Winters (H-W) methods have been used. Findings The results show that, to predict domain names .it the SARIMA model is better than the H-W methods. According to the findings, notwithstanding the forecast of a growth in domain names, the increase is however limited (about 3%), tending to reach a phase of saturation of the market of domain names .it. Originality/value In general many authors have studied internet diffusion applying statistical models that follow an S-shaped behavior. On the other hand, the more used diffusion models that follow an S-shape not always provide an adequate description of the Internet growth pattern. To achieve this goal, this paper demonstrates how the time series models, in particular SARIMA model and H-W models, fit well in explaining the spread of the internet.

Prototype commercial evapoporometer instrument

Determining the pore size is important for assessing the performance of porous materials such as membranes. Evapoporometry is a relatively new characterization method based on the Kelvin equation that predicts the vapor-pressure reduction of a volatile wetting liquid in the pores. Evapoporometry employs a test cell that maintains a saturated gas phase above the porous sample so that evaporation progresses from the largest to the smallest pores. Continuously weighing the evaporated mass permits determining the pore-size distribution. Implementing evapoporometry requires considerable expertise; hence, it has been used as a research tool but not for routine characterization. Dedicated instruments are available for competitive pore-size-characterization methods such as liquid-displacement and gas-adsorption/desorption porometry. In this paper the development of a dedicated evapoporometer instrument is described that requires no user intervention once the porous sample is placed in the test cell. Moreover, the software also gives the flow-average and molecular-weight-cutoff metrics not reported in prior studies and corrects for the adsorbed t-layer mass on the pore walls that has been ignored or accounted for incorrectly in prior studies. The t-layer mass ranged from 8% to 72% for the three commercial PVDF membranes in this study; hence, ignoring it will seriously distort the pore-size distribution.

Solid-liquid phase equilibrium of SOV-I2 in various pure and binary mixed solvents: Solubility determination, solvent effect, preferential solvation and model correlation

The solubility knowledge is important in the field of separation and purification of chemicals as well as quality control of drugs. In this work, the saturated phase equilibrium of SOV-I2 in ethanol, 1-butanol, acetone, methanol, 1-propanol, acetonitrile, toluene, 2-propanol, ethyl acetate, water, ethanol + water and acetone + water at a series of temperature of 278.15 K-318.15 K was constructed and the solubility data was measured by using isothermal saturation methods. The solvent effect evaluation, preferential solvation discussion and model correlation were used to explore the solubility behavior of SOV-I2. The solubility of SOV-I2 in mole fraction increased with the increasing of temperature. The experimental solubility data of SOV-I2 in mole fraction showed a subsequence in acetone > ethyl acetate > toluene > acetonitrile > methanol > ethanol > 1-propanol > 2-propanol > 1-butanol > water. For SOV-I2 + aqueous mixtures systems, the solubility data raised with the adding of co-solvents and no co-solvency phenomenon appeared in the dissolution process of SOV-I2 in two aqueous mixtures. The solvent effect was analyzed by KAT-LSER model which suggested that interaction of nonspecific dipolarity/polarizability played a dominant role in SOV-I2 dissolution. The solute–solvent interactions, accounted for>60%, were very important in dissolution of SOV-I2. Furthermore, the preferential solvation mechanism of SOV-I2 in two aqueous mixtures was discussed by IKBI method. The negative preferential solvation parameter (δx1,3) exhibited in the region of < x1 < 0.24 for ethanol (1) + water (2) mixtures and 0 < x1 < 0.21 for acetone (1) + water (2) mixtures. It suggested that SOV-I2 (3) was dissolved by water (2) preferentially in water-rich region. However, in other regions, the δx1,3 values were positive which indicated that SOV-I2 (3) was dissolved by co-solvents (1, ethanol or acetone) preferentially. In addition, the classical Apelblat, λh, Jouyban-Acree and Apelblat-Jouyban-Acree models were used to correlate the solubility data of SOV-I2. The correlation results showed that the greatest values of RAD and RMSD were 0.94% and 0.68 × 10-4 for pure solvent systems, and 2.10% and 2.14 × 10-4 for two aqueous mixtures systems, respectively. The evaluation indexes were quite small. In brief, these models showed a good applicability to experimental solubility data of SOV-I2.

Mechanism analysis of unbalanced three-phase inrush current of Y0D transformer

During the energization of transformer with high-impedance (HT), the zero-sequence overcurrent protection (ZSOCP) often malfunction with the inrush current of primary winding (iP-inrush) shows a large unbalance. In order to clarify the cause of the misoperation and prepare for a solution, the imbalance characteristic is studied in this paper. The imbalance is visually displayed by dynamic phasor diagram. Through the method of numerical simulation, it can be obtained that the peak value of the zero-sequence current always appears near characteristic opening and switching angles (COSAs). At this time, the two phases are deep saturated and one phase is not saturated. The iP-inrush of the saturated phase is large, and that of the unsaturated phase is numerically the same as the circulating current (iD). According to the parameters characteristics of HT, the iD is small, so iP presents a large imbalance. The research conclusions provide a theoretical basis for zero-mode inrush current suppression.

Spatially-explicit prediction of low-density peri-urban development: comparison between urban and rural scenarios in the Moreton Bay Region in South East Queensland, Australia

Mainstream urban modelling literature focuses on urban expansion featured by a relatively fast urbanisation process, but relatively less research is available to understand and model the slow-paced urban and rural land development in the low-density peri-urban context. This study aims to address this knowledge gap by simulating the urban and rural land development in the Moreton Bay Region in South East Queensland (SEQ), Australia using two cellular automata (CA) models that are coupled with a generalised simulated annealing (GSA) algorithm. With the total land available for development estimated using a Markov Chain model, the GSA-CA urban and rural models were developed, respectively, to simulate urban and rural land development from 1991 to 2011, and then to predict their future development to 2041 following vigorous model calibrations. The modelling results illustrate three snapshots of the predicted spatial patterns of urban and rural development in 2021, 2031 and 2041, with moderate growth in both the urban and rural areas over time, but with urban development occurring in a more compact form than rural development. The GSA-CA modelling approach is capable of optimising the CA transition rules and has the potential to be applied to other geographical contexts to support regional planning, decision-making and scenario designation for future land development in cities that have entered the saturation phase of urbanisation.

Continuous Be mineralization from two-mica granite to pegmatite: Critical element enrichment processes in a Himalayan leucogranite pluton

AbstractBeryllium is a critical metal typically concentrated in highly fractionated granitic rocks such as the leucogranites in the Himalaya. Here, we report beryl mineralization that was continuous from the earlier and less-evolved two-mica granite to the highly evolved albite granite and pegmatite in a typical leucogranite pluton at Pusila in the central of Himalaya. Textural and mineral chemical evidence support a magmatic origin for beryl, and the trends of beryl crystal chemistry indicate magma differentiation. Despite low to moderate fractionation of the biotite granite and two-mica granite in the Pusila leucogranite pluton, the Be contents (~7 µg/g, beryl-free and ~22 µg/g, beryl-bearing, respectively) of these granites are much higher than the average for biotite- and two-mica granites worldwide (~3–4 and 5–10 µg/g, respectively), indicating that the initial magma had a relatively high-Be concentration. The gneisses of Greater Himalayan System, considered the protolith, also show a higher Be abundance (~4–6 µg/g) than the mean value of pelitic rocks worldwide (~2–3 µg/g), which could be the source reservoir of Be. The source contributed the initial Be to the melt, and fractionation resulted in the onset of beryl crystallization from the interstitial residual melt in the two-mica granite. The ubiquity of beryl in two-mica granite to pegmatite stages of the Pusila pluton is explained by a continuous crystallization model, although there was a delay in the onset of beryl crystallization in the two-mica granite. Modeling based on Rayleigh fractionation indicates that Be becomes compatible once saturation is attained because of the beryl crystallization. Our findings indicate that the enrichment of critical elements (e.g., Be) is controlled not only by fractional crystallization but also by the buffering action of a saturating phase (e.g., beryl) on the concentration of the critical element in the melt.

Forecasting quantities of critical raw materials in obsolete feature and smart phones in Greece: A path to circular economy

Mobile phones represent an ever-increasing waste stream due to the increasing ownership and short lifetime. In particular, smartphones are among the most valuable e-waste because of their extremely high content of numerous key metals, specifically in the printed circuit board and magnets. As feature and smart phones contain different key metals at different concentrations, it is important to distinguish between the two phone types to make reliable estimations. This study presents estimations of obsolete mobile phones quantities, generated in Greece in 1995–2035 and the Critical Raw Materials (CRMs) and Precious Metals (PMs) embedded in them, making a differentiation between feature and smart phones. The dynamic material flow analysis is adopted, the lifespan is evaluated by the Weibull distribution and future sales are predicted by the logistic model incorporating phases of growth, saturation and decline. Then, the future wastes are predicted by the Market Supply A model. According to the results, the generation of obsolete smartphones is constantly increasing, while the waste flows of feature phones are declining. Efficient recycling of obsolete phones (1995–2020) can cover the demand for key metals (Au, Pd, Co) in the new smartphones for more than a decade in Greece, while the demand for Ag, Sb, Si, Zn, Be, Ti will be covered for more than 15 years. In 2020–2035 the accumulated amounts of CRMs and PMs, only from the smartphone waste, will be 1292.02 and 14.11 tonnes, respectively. The findings can contribute to the management of a valuable e-waste category closing the loop between resources-products-wastes.

Solubility behavior of CO2 and H2S in 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid

The solubility of CO2 and H2S in 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bzmim][Tf2N]) ionic liquid has been measured at temperatures from (303.15 to 343.15) K and pressures of up to about 3.1 and 1.6 MPa, respectively. The molar volume of the gas saturated liquid phase has also been measured. It was found that the solubility of H2S in [Bzmim][Tf2N] is>2 times that of CO2. Henry’s constants, partial molar volumes and partial molar thermodynamic functions at infinite dilution for dissolution of CO2 and H2S in [Bzmim][Tf2N] were evaluated from the experimental data. The experimental data was correlated using the extended Henry's law combined with a simplified Pitzer's model. The experimental data was further correlated by a generic Redlich-Kwong equation of state (GRK EoS). Both models show quite good correlative accuracy for CO2/H2S + [Bzmim][Tf2N] mixtures. However, the former model was superior to that of the GRK EoS for H2S + [Bzmim][Tf2N].

Situation of COVID-19 in Brazil in August 2020: An Analysis via Growth Models as Implemented in the ModInterv System for Monitoring the Pandemic

In this work we introduce a novel methodology to classify the dynamical stages of an epidemic, based on the different acceleration regimes of the corresponding growth curve. Our classification scheme is implemented by fitting the empirical data with a general class of mathematical growth models, from which we compute not only the growth acceleration but also its jerk and jounce (i.e., the first and second derivatives of the acceleration, respectively), thus allowing for a finer distinction of the epidemic stages. Using this methodology, we analyze the cumulative curves of deaths attributed to COVID-19 in the 26 Brazilian States and the Federal District, up until August 21, 2020. The online application ModInterv COVID-19, which automatically implements the classification scheme and which can be accessed via an internet browser or a mobile app, was used to investigate the epidemic stages in each of the Brazilian federal units. The analysis revealed that almost all states in the Northern and Northeastern regions were already in the saturation phase, meaning that the epidemic was relatively under control, whereas in all Southern states and in most states in the Midwest the epidemic was still accelerating or showed only a slight deceleration. The Southeastern region presented a great diversity of epidemic stages, with each state being found at a different stage, ranging from acceleration to saturation. It is argued that understanding this heterogeneous geographical distribution of the epidemic is relevant for public health authorities, as it may help in devising more effective strategies against the COVID-19 pandemic in a continental country like Brazil.

Fuzzy MCDM for Improving the Performance of Agricultural Supply Chain

Fertilizer industry in Vietnam and globally have entered the saturation phase. With the growth rate slowing down, this poses challenges for the development impetus of the fertilizer industry in the next period. In fact, over the past few decades, Vietnam’s crop industry has abused excessive investment in chemical fertilizers, with organic fertilizers are rarely used or not at all, limiting crop productivity, increasing pests and diseases. To develop sustainable agriculture, Vietnam’s crop industry must limit the use of chemical fertilizers, increase the use of environmentally friendly organic and natural mineral fertilizers to produce clean agricultural products which is safe. Therefore, it is necessary to consider and choose the right supplier to ensure the goal of sustainable development. Spherical Fuzzy Analytic Hierarchy Process (SF-AHP), and the combinative distance-based assessment (CODAS) are new Multicriteria Decision Making (MCDM) method which can be used to solve supplier selection problem. This paper uses an effective solution based on a combined the concept of triple bottom line (TBL), SF-AHP and CODAS approach to help agriculture companies that need to select the best fertilizer supplier. This research can support supply chain managers to achieve supply chain systems that reduce not only sourcing costs, but also develop sustainable agriculture.

Ground State, Magnetization Process and Bipartite Quantum Entanglement of a Spin-1/2 Ising-Heisenberg Model on Planar Lattices of Interconnected Trigonal Bipyramids.

The ground state, magnetization scenario and the local bipartite quantum entanglement of a mixed spin- Ising–Heisenberg model in a magnetic field on planar lattices formed by identical corner-sharing bipyramidal plaquettes is examined by combining the exact analytical concept of generalized decoration-iteration mapping transformations with Monte Carlo simulations utilizing the Metropolis algorithm. The ground-state phase diagram of the model involves six different phases, namely, the standard ferrimagnetic phase, fully saturated phase, two unique quantum ferrimagnetic phases, and two macroscopically degenerate quantum ferrimagnetic phases with two chiral degrees of freedom of the Heisenberg triangular clusters. The diversity of ground-state spin arrangement is manifested themselves in seven different magnetization scenarios with one, two or three fractional plateaus whose values are determined by the number of corner-sharing plaquettes. The low-temperature values of the concurrence demonstrate that the bipartite quantum entanglement of the Heisenberg spins in quantum ferrimagnetic phases is field independent, but twice as strong if the Heisenberg spin arrangement is unique as it is two-fold degenerate.

Stable phase equilibria in the quinary system LiCl–NaCl–KCl–SrCl2–H2O at 288 K

Sichuan Basin is rich in underground brines, which are important liquid mineral resources. In order to realize the exploitation and utilization of the brine resources, in this work, we used the isothermal dissolution equilibria method to study the phase equilibria of related subsystem for the underground brines. Consequently, the phase equilibria of the quinary system LiCl–NaCl–KCl–SrCl2–H2O at 288 K are studied in detail. The solubilities of salts in saturated liquid phase of the quinary system were measured by chemical analysis, and the equilibrium solid phases of the quinary system were identified by chemical analysis and X-ray powder diffraction. The phase diagrams of the quinary system LiCl–NaCl–KCl–SrCl2–H2O at 288 K were also given, and simplified dry base salt diagram, water content diagram and saturated salt content diagram of each salt saturation surface were presented respectively. The results show that the quinary system is a hydrate type. When LiCl, NaCl, KCl and SrCl2 are saturated respectively, the dry salt phase diagrams have different crystalline regions. When LiCl·2H2O is saturated, the crystalline regions are SrCl2·2H2O, NaCl and KCl; When NaCl is saturated, the crystalline regions are KCl, SrCl2·6H2O, SrCl2·2H2O and LiCl·2H2O; When KCl is saturated, the crystalline regions are NaCl, SrCl2·6H2O, SrCl2·2H2O and LiCl·2H2O; When SrCl2·6H2O is saturated, the crystalline regions are KCl, NaCl and SrCl2·2H2O.

Using Salivary Biomarkers for Stress Assessment in Offshore Saturation Diving: A Pilot Study.

Health monitoring during offshore saturation diving is complicated due to restricted access to the divers, the desire to keep invasive procedures to a minimum, and limited opportunity for laboratory work onboard dive support vessels (DSV). In this pilot study, we examined whether measuring salivary biomarkrers in samples collected by the divers themselves might be a feasible approach to environmental stress assessment. Nine saturation divers were trained in the passive drool method for saliva collection and proceeded to collect samples at nine time points before, during, and after an offshore commercial saturation diving campaign. Samples collected within the hyperbaric living chambers were decompressed and stored frozen at −20°C onboard the DSV until they were shipped to land for analysis. Passive drool samples were collected without loss and assayed for a selection of salivary biomarkers: secretory immunoglobulin A (SIgA), C-reactive protein (CRP), tumor necrosis factor (TNF)-α, interleukins IL-6, IL-8, IL-1β, as well as cortisol and alpha-amylase. During the bottom phase of the hyperbaric saturation, SIgA, CRP, TNF-α, IL-8 and IL-1β increased significantly, whereas IL-6, cortisol and alpha-amylase were unchanged. All markers returned to pre-dive levels after the divers were decompressed back to surface pressure. We conclude that salivary biomarker analysis may be a feasible approach to stress assessment in offshore saturation diving. The results of our pilot test are consonant with an activation of the sympathetic nervous system related to systemic inflammation during hyperbaric and hyperoxic saturation.

Recycling of residual valuable metals in cyanide-leached gold wastewater using the N263-TBP system

In this study, the synergistic extraction system of trioctylmethyl ammonium chloride (N263)-tributyl phosphate (TBP)-n-octanol-sulfonated kerosene was used to enrich and recover valuable metals from cyanide gold extraction of wastewater. The effects of the proportion of N263 and TBP, contact time, initial pH of water phase, temperature, and phase ratio (O/A) on the extraction percentage of metal cyanide complex ions and the synergistic extraction reaction mechanism were mainly investigated. Results showed that the single-stage extraction percentages of Cu, Zn, and Fe ions in wastewater were 99.87%, 99.8%, and 96.2%, respectively, and the saturated extraction capacity was 4356.4 mg/L under the conditions of N263 (20 vol%)-TBP (20 vol%)-n-octanol (10 vol%)-sulfonated kerosene system at 25 °C, O/A of 1:1, pH of 10, and contact time of 5 min. Fourier transform infrared spectroscopy (FT-IR) and electrospray ionization mass spectrometry (ESI-MS) analyses showed that metals entered the organic phase in the form of metal cyanide complex ions during extraction. Metal cyanide complex ions preferentially combined with TBP to lose hydrophilicity and then reacted with N263 cations to enter the organic phase. The saturated organic phase was stripped by NaOH and NaSCN mixed solution, and the total concentration of metal ions in the stripping solution reached 11,996.6 mg/L.