High Solute Flux Research Articles

Universal growth of perovskite thin monocrystals from high solute flux for sensitive self-driven X-ray detection

Metal-halide perovskite thin monocrystals featuring efficient carrier collection and transport capabilities are well suited for radiation detectors, yet their growth in a generic, well-controlled manner remains challenging. Here, we reveal that mass transfer is one major limiting factor during solution growth of perovskite thin monocrystals. A general approach is developed to overcome synthetic limitation by using a high solute flux system, in which mass diffusion coefficient is improved from 1.7×10–10 to 5.4×10–10 m2 s–1 by suppressing monomer aggregation. The generality of this approach is validated by the synthesis of 29 types of perovskite thin monocrystals at 40–90 °C with the growth velocity up to 27.2 μm min–1. The as-grown perovskite monocrystals deliver a high X-ray sensitivity of 1.74×105 µC Gy−1 cm−2 without applied bias. The findings regarding limited mass transfer and high-flux crystallization are crucial towards advancing the preparation and application of perovskite thin monocrystals.

Copper-catalyzed FeOOH templated method for accelerated fabrication of ultraporous membranes used in microalgae dewatering

Porous materials including polymeric and inorganic membranes are important and widely used in various industries. Controlling the pore size and pore distribution in porous materials is the major focus in this field. In this study, a novel copper-catalyzed template dissolution approach using ferric oxyhydroxide (FeOOH) as nano-templates was introduced for the preparation of ultraporous polymeric membrane. Compared to typically used acid dissolution method, this approach accelerated the removal of FeOOH by 30 folds. The reduction of ferric by copper into ferrous weakened the Fe-O bonds in FeOOH hence leading to fast dissolution of the nanomaterials. The effectiveness of copper-catalyzed FeOOH dissolution was affected by the concentration of acid and copper ions as well as the type of anions present in the dissolution solution. Membranes fabricated via FeOOH-templating approach were evaluated for microalgae dewatering application and showed 8–21 % higher solution flux than their corresponded nanocomposite membrane. The enhancement was attributed to the elevation of membrane porosity by 1–4 % and the creation of more interconnected pore system. The best membrane, M1.0 exhibited the highest porosity of 94 % and achieved the best microalgae solution flux of 57.7 L·m−2·h−1. The outcomes of this study confirmed the viability of copper-catalyzed approached in accelerating the formation of ultraporous materials and demonstrated the potential of such materials in microalgae dewatering application.

Enhancement of polysulfone membrane with integrated ZnO nanoparticles for the clarification of sweetwater

Clarification is one of the main steps in producing glycerin from glycerin–rich solution (namely sweetwater) in oleo-chemical industry. In this study, ZnO nanoparticles (9–12 nm in diameter) were incorporated into polysulfone (PSf) membranes to improve the membrane antifouling properties toward the fatty acids in sweetwater. The hybrid membranes were fabricated through wet phase inversion method. The modified membranes exhibited better water permeability, membrane surface hydrophilicity (improvement from 82° to 62.1°) and resistance toward fouling by fatty acids. In this study, the best membrane was obtained in the presence of 3% of ZnO nanoparticles, which showed good fouling resistance, high solution flux and a very high rejection of fatty acids (≥80%) in comparison with the pure PSf membranes, at the same experimental conditions. The enhanced membrane performances during the clarification of sweetwater were attributed to the unique properties of ZnO nanoparticles that were uniformly dispersed in the PSf structures.

Mass transfer dynamics during the acidic marination of turkey meat

The mass transfers of water, acid and NaCl in turkey meat cubes (initial volume 1cm3 during marination were evaluated at various molalities of acetic acid (0.0–1.0) and NaCl (0.0–1.5). An experimental design was drawn up, associated with an estimate of the velocities of each component by means of kinetic monitoring. High mass yields (mass gain >0.3kgkg−1), obtained for the marinades most dilute in acid, were found only in the absence of NaCl. The presence of NaCl had a negative effect on mass yield, counterbalanced by the positive effect of acetic acid. In the case of acidic marinades with low salt concentration, high solute flux densities were observed upon the start of immersion, as well as solute transfer velocities greater than those in water. This phenomenon may be explained by the superimposition of material diffusion and transport phenomena caused by a fall in internal filtration pressure due to expansion of the protein matrix. The fall in the buffering capacity of the meat in the course of soaking, related to the leakage of proteins, dipeptides and lactates, may explain the low pH values obtained during immersion in comparison with theoretical data.

Crustal solute fluxes and transient carbon dioxide drawdown in the Scottbreen Basin, Svalbard in 2002

Summary Solute fluxes and transient carbon dioxide drawdown in a small glacierized basin investigated on Svalbard in 2002 are presented. It was a sample year within a period of significant climate warming in the Arctic. Discharge was recorded in the Scottbreen Basin (10.1 km 2 ), Bellsund Fjord, between July 8 and September 10, 2002. Specific runoff for this period was 0.784 m, 22% more than the mean for 1986–2001. The runoff for all of 2002 (i.e. the hydrologic year) was estimated by comparison with Bayelva, the only glacial river with longer records on Svalbard. The specific runoff for 2002 was ∼1.228 m, yielding crustal solute fluxes of 69.4 t km −2 yr −1 (25.8 m 3 km −2 yr −1 ). This rate is the highest chemical denudation rate reported from glacierized basins on Svalbard, and it may be underestimated because higher solute fluxes at the beginning of the melt season were not taken into account. Crustal fluxes in the fall may also have been higher because it is probable that crustal ion concentrations were increasing after recording stopped in September. The cation denudation rate was 1213 ∑ meq + m −2 yr −1 and the mean annual crustal ion concentration derived from it amounted to 981 μeq L −1 . Transient CO 2 drawdown in 2002 was 5242 kg C km −2 yr −1 . Most of the carbon dioxide was removed in the summer ablation waters, estimated CO 2 drawdown in the fall being only 13% of the total. Comparison with crustal solute fluxes (CSF) computed from specific conductivity in the 1980s and 1990s suggests that earlier fluxes may have been overestimated by around 19%. Comparing earlier data with the 2002 rates may confirm the influence of climate warming on increasing chemical denudation rates. It was also found that a globally derived equation relating specific conductivity to concentrations of dissolved limestone in water gave estimates of the crustal solute fluxes that were only 1.1% less than those obtained via comprehensive chemical analyses of waters and ion partitioning procedures.

Solute geochemical mass-balances and mineral weathering rates in small watersheds: Methodology, recent advances, and future directions

Solute-based geochemical mass balance methods are commonly used in small-watershed studies to estimate rates of a variety of geochemical processes at the Earth’s surface, including primary-mineral weathering and soil formation, and the quantitative contribution of these elemental transfer processes to cation budgets, nutrient cycling, and landscape susceptibility to acid deposition. Weathering rates of individual minerals in watershed mass-balance studies are determined by solving a system of simultaneous linear geochemical mass-balance equations with constant (stoichiometric) coefficients. These equations relate the measured net fluxes to the (known) stoichiometries and (unknown) rates of weathering reactions for multiple minerals in the weathering profiles. Solving the system of equations requires petrologic, mineralogic, hydrologic, botanical, and aqueous geochemical data. The number of mineral-weathering rates that can be determined is limited by the number of elements for which solute mass-balance equations can be written. In addition to calculating mineral weathering rates, elemental transfer into or out of the biomass may also be calculated. Elemental uptake by aggrading forest vegetation can act as an intrawatershed sink for at least some mineral-derived cations, producing mineral weathering rates higher than would be estimated from solute fluxes alone; similarly, element release from decaying forest biomass can result in higher solute fluxes than are produced by weathering alone. The mathematics of, significant contributions from, role of biomass in, and recent advances in, watershed geochemical mass-balance methods are discussed using examples from the Appalachian headwaters watersheds of the Coweeta Hydrologic Laboratory in the southern Blue Ridge Physiographic Province of North Carolina, USA.

Solute flux in meltwaters draining from a glacierized basin in the Karakoram mountains

Electrical conductivity of meltwaters in the Batura river which drains from the portal of Batura glacier in the Karakoram mountains was recorded continuously, together with stage, throughout an ablation season with the aim of estimating the annual total solute flux from the 56% glacier-covered basin. Through-time variations of meltwater cationic concentration were obtained from the electrical conductivity record using a rating curve established between sums of cations determined in periodically-collected samples of meltwater and electrical conductivity measured at the times of sampling. Hourly average cationic flux was then obtained as the product of cationic concentration and discharge, error arising as a result of inaccuracy in river gauging and use of the rating relationship. Electrical conductivity varied diurnally inversely with discharge, overall level decreasing as discharge increased in spring, continuing subdued through July and August irrespective of episodic discharge fluctuations. In contrast, solute flux mimicked discharge variation, low solute concentrations being offset by the volume of water flowing. Total annual cationic flux from Batura basin was 1.03 Meq ± ∼ 15%. Assuming almost all of the flux was derived subglacially, the solute flux from beneath Batura glacier was 2.64 ± 0.40 eq m -2 a -1 . These rates of cationic denudation, substantially higher than the continental average, are at the top end of the global range of reasonably-reliable estimates for other smaller glacierized basins. Carbonate lithology, high annual runoff, high sediment concentration in meltwaters, and long subglacial pathways account for the high solute flux from Batura glacier. Through longer residence times of meltwater in transit under ice and higher discharges, dissolution kinetics and flow couple to enhance solute fluxes from larger glaciers. Although subglacial chemical denudation in the Karakoram mountains is significant in carbon cycling at the continental scale, such carbonate dissolution probably contributes little to net consumption of carbon dioxide from the atmosphere.

Amino acid losses during hemodialysis: effects of high-solute flux and parenteral nutrition in acute renal failure.

During standard hemodialysis, amino acid losses are substantial, amounting to 6 to 9 g per treatment. When these nutritional supplements are infused during dialysis, losses are increased, but a net positive balance can be achieved if the infusion rate is high enough. High-flux dialyzers, used with increasing frequency in modern dialysis centers because of their more permeable synthetic membranes, should cause further amino acid losses; however, the increase has not been measured, and the effect on plasma levels has not been examined. Assessment of net balance requires measurement of blood concentrations as well as of clearance. To quantitate the effect of high-flux dialysis on amino acid balance, we measured clearances, plasma levels, and losses of individual amino acids during hemodialysis in patients with acute renal failure who required daily parenteral nutrition. Nearly all predialysis amino acid levels in plasma were within the normal range, probably because of control of uremia with prior dialyses and from continuous infusion. In paired studies, clearances were higher (150 +/- 15 mL/min vs 107 +/- 11 mL/min, p < .01), and levels fell more at mid-dialysis with high-flux membranes (28% +/- 5%) than with conventional cellulosic membranes (4 +/- 5%, p < .05). Mean losses of amino acid were 5.2 +/- 0.6 g per conventional dialysis, representing 60% of the total infused, and 7.3 +/- 1.8 g per high-flux dialysis, or 80% of the simultaneous infusion. Fractional losses decreased at higher infusion rates, but losses of individual amino acids varied from one fourth to more than 10 times the amount infused. Compared with other small solutes, plasma levels were relatively well maintained even during high-flux dialysis, a factor that enhanced removal by the dialyzer. Total balance depended more on the infusion rate than on the dialysis membrane. These studies show that positive balance can be achieved with concurrent infusion during dialysis, especially at higher amino acid delivery rates. High-flux dialysis causes a greater disturbance of amino acid equilibrium than conventional dialysis does, but 24-hour gains far exceeded losses in the dialysate for most of the amino acids.

Plasmatubules – real modifications of the plasmalemma

Plasmatubules are specific (approximately 20 nm diameter) evaginations of the plasmalemma, found at sites where high solute flux from apoplast to symplast is known, or inferred, to occur for short periods. First described in the distal, endosperm, end of barley scutellar epithelial cells, their structure has subsequently been confirmed using a range of both aqueous and non‐aqueous fixation techniques. Plasmatubules have now been described in a range of tissues and species, and examination of published micrographs indicates that this range could be extended further.

Plasmatubules in transfer cells of pea (Pisum sativum L.)

Plasmatubules are tubular evaginations of the plasmalemma. They have previously been found at sites where high solute flux between apoplast and symplast occurs for a short period and where wall proliferations of the transfer cell type have not been developed (Harris et al. 1982, Planta 156, 461-465). In this paper we describe the distribution of plasmatubules in transfer cells of the leaf minor veins of Pisum sativum L. Transfer cells are found in these veins associated both with phloem sieve elements and with xylem vessels. Plasmatubules were found, in both types of transfer cell and it is suggested that the specific distribution of the plasmatubules may reflect further membrane amplification within the transfer cell for uptake of solute from apoplast into symplast.

Plasmatubules: fact or artefact?

Plasmatubules are tubular evaginations of the plasmalemma associated with sites where high solute flux occurs between apoplast and symplast. Plasmatubules of the scutellar epithelial cells of germinating barley (Hordeum vulgare L.) have been examined following a variety of fixation methods. Of the aqueous fixations, primary aldehyde fixation with osmium post-fixation and osmium as the primary fixative gave comparable images, whilst potassium permanganate resulted in some distortion of the tissue in general including dilation of the tubular evaginations of the plasmalemma. Freeze-fixation and substitution with acetone and acetone-osmium gave images of the plasmalemma comparable to those obtained by the aqueous aldehyde and osmium methods. The similarity of structure with aldehyde or osmium and freezing as the primary fixation is taken to indicate that plasmatubules are real and not artefacts resulting from the fixation procedure.