Changes In Salt Concentration Research Articles

The influence of various factors on the droplet desorption

Experimental data on sessile droplet desorption of aqueous salt solution of LiBr on a heated wall were implemented. High-temperature desorption of water-salt solutions in air atmosphere leads to significant difficulties at modeling heat and mass transfer. In this case, the evaporation rate multiply decreases with time and the diffusion coefficient, the desorption heat and the salt concentration change significantly. With the growth of salt concentration in solution from 10 % to 65 %, the steam partial pressure at the interface falls by dozens of times. In this study, we performed experiments in a wide range of salt concentrations and proposed a simple estimated method for calculating the mass flow. The resulting technique can predict the droplet solution behavior with a significant change in the partial vapor pressure on the droplet interphase with time.

Induced Mesocrystal-Formation, Hydrothermal Growth and Magnetic Properties of α-Fe2O3 Nanoparticles in Salt-Rich Aqueous Solutions

Iron oxide nanoparticles are widely prevalent in our aqueous environment (e.g., streams, seawater, hydrothermal vents). Their aggregation and crystal growth depend on their chemical surroundings, for instance just a change in pH or salt concentration can greatly affect this. In turn this influences their properties, mobility, fate, and environmental impact. We studied the growth of α-Fe2O3 (hematite), starting from 8 nm hematite particles in weakly acidic (HNO3) aqueous suspension with different states of particle aggregation, using salt (NaCl and NaH2PO4) to control their initial aggregation state. The samples were then subject to hydrothermal treatment at 100–140 °C. We followed the development in aggregation state and particle size by dynamic light scattering, X-ray diffraction, small angle neutron scattering and transmission electron microscopy, and the magnetic properties by Mössbauer spectroscopy. The addition of NaCl and NaH2PO4 both led to aggregation, but NaCl led to linear chains of hematite nanoparticles (oriented parallel to their hexagonal c-axis), such that the crystalline lattice planes of neighboring hematite particles were aligned. However, despite this oriented alignment, the particles did not merge and coalesce. Rather they remained stable as mesocrystals until heat-treated. In turn, the addition of NaCl significantly increases the rate of growth during hydrothermal treatment, probably because the nanoparticles, due to the chain formation, are already aligned and in close proximity. With hydrothermal treatment, the magnetic properties of the particles transform from those characteristic of small (aggregated) hematite nanoparticles to those of particles with more bulk-like properties such as Morin transition and suppression of superparamagnetic relaxation, in correspondence with the growth of particle size.

Microbial Survey on Industrial Bioleaching Heap by High-Throughput 16S Sequencing and Metagenomics Analysis

Bioleaching processes are usually open systems where introduced and native microorganisms survive to changes in pH, temperature, salt and metal concentration, among others. Spatial and temporal description of the microbial community could be relevant for better comprehension of copper extraction process and help in the development of operative procedures to improve the metal extraction. We performed metagenomics and high-throughput sequencing of 16S rRNA genes analyses on samples from Escondida mine bioleaching heap and laboratory columns tests. Archaeal community structure in samples was assessed using three pairs of Archaea-specific primers, and results were highly depending on the primers pairs used. Similarly, three pairs of Bacteria-specific primers were used to assess the bacterial community. Moreover, according to the metagenomics analysis, At. thiooxidans, F. acidarmanus, Leptospirillum spp., Acidiphilium sp. JA12-A1, Acidiphilium spp., At. ferrivorans, and Leptospirillum ferriphilum were the most representative microorganisms. The repercussion of the different methodologies and outputs in the characterization of the bioleaching microbial community is discussed. A better understanding of the microbial community in bioleaching processes could improve the analysis regarding environmental changes in the heap process, its metallurgical performance and, can be used to assist in the decision-making process.

Simple Model of the Effect of Solution Conditions on the Nucleation of Amyloid Fibrils.

It is well known that peptide and protein fibrillation is strongly affected by the solution conditions, but a fundamental understanding of how amyloid fibril nucleation depends on solution pH, salt concentration, and solvent is absent. Here, we use expressions from Debye-Hückel theory to describe the interactions between charged amino acids in combination with our recently developed nonstandard nucleation theory to predict the concentration dependence of the fibril nucleation rate under different solvent conditions. The general rule that emerges from these considerations is that changes in solution pH, salt concentration, and solvent that increase the bonding energy between the fibril building blocks decrease the fibril solubility and promote fibril nucleation, in line with experimental observations. The simple analytical relations among the nucleation rate, fibril solubility, and binding energies provide a tool to controlling and understanding amyloid fibril formation by changing the solution conditions.

Tunable fluorescence quenching near the graphene-aqueous interface

With increased interest in graphene-based sensors for biomolecules and other targets, we investigated the impact of ionic strength on the steady-state emissions from fluorescein labels on proteins adsorbing on pristine CVD (chemical vapor deposited)-graphene on a silica support. Using the model system of fluorescein-tagged fibrinogen we demonstrated that, for fluorescein tags on adsorbed fibrinogen, emission intensity was very sensitive to the salt concentration. This behavior was not seen for fluorescein-tagged fibrinogen in solution. We demonstrated that fluorescein “quenching” in this system was a result of fluorescein’s pH sensitivity: with changes in salt concentration, near-surface fluorescein experiences either the neutral bulk pH or, with a negatively charged surface, an acidic environment. The findings carry the important implication that the aqueous environment near silica-supported graphene is substantially acidic as a result of near-surface negative charge. This further implies, because of the purity of the graphene in this study and its lack of oxidation, that negative charge arises from ion adsorption and/or from the underlying silica support, which may be hydrated and present dissociated surface silanols. That is, the electrostatic potential from silica beneath the graphene may pass through the graphene, much as van der Waals interactions have been proven to do. Results were semi-quantitatively consistent with calculations that employed a Guoy Chapman model of the interface and the established pKa of the fluorescein. While these findings were obtained with adsorbed proteins, similar fluorescence quenching would be expected for any fluorescein-tagged species in the vicinity of silica-supported graphene. Thus, because of the negative charge at the aqueous graphene interface, ionic strength can be exploited as means of creating a molecular ruler of fluorescein emissions, and the emissions can be assessed within different distances, corresponding to the Debye length, from the graphene interface.

A Mutation in the Bacillus subtilis rsbU Gene That Limits RNA Synthesis during Sporulation

Mutants of Bacillis subtilis that are temperature sensitive for RNA synthesis during sporulation were isolated after selection with a 32P suicide agent. Whole-genome sequencing revealed that two of the mutants carried an identical lesion in the rsbU gene, which encodes a phosphatase that indirectly activates SigB, the stress-responsive RNA polymerase sigma factor. The mutation appeared to cause RsbU to be hyperactive, because the mutants were more resistant than the parent strain to ethanol stress. In support of this hypothesis, pseudorevertants that regained wild-type levels of sporulation at high temperature had secondary mutations that prevented expression of the mutant rsbU gene. The properties of these RsbU mutants support the idea that activation of SigB diminishes the bacterium's ability to sporulate.IMPORTANCE Most bacterial species encode multiple RNA polymerase promoter recognition subunits (sigma factors). Each sigma factor directs RNA polymerase to different sets of genes; each gene set typically encodes proteins important for responses to specific environmental conditions, such as changes in temperature, salt concentration, and nutrient availability. A selection for mutants of Bacillus subtilis that are temperature sensitive for RNA synthesis during sporulation unexpectedly yielded strains with a point mutation in rsbU, a gene that encodes a protein that normally activates sigma factor B (SigB) under conditions of salt stress. The mutation appears to cause RsbU, and therefore SigB, to be active inappropriately, thereby inhibiting, directly or indirectly, the ability of the cells to transcribe sporulation genes.

Salt-Induced Swelling and Volume Phase Transition of Polyelectrolyte Gels

A theoretical model of polyelectrolyte gels is presented to study continuous and discontinuous volume phase transitions induced by changing salt concentration in the external solution. Phase diagrams are constructed in terms of the polymer–solvent interaction parameters, external salt concentration, and concentration of fixed charges. Comparisons with previous experiments for an ionized acrylamide gel in mixed water–acetone solvents are made with good quantitative agreement for a monovalent salt (NaCl) but fair qualitative agreement for a divalent salt (MgCl2), using a simple set of parameters for both cases. The effective polymer–solvent interactions vary with the volume fraction of acetone in the mixed solvent, leading to either continuous or discontinuous volume transitions. The presence of divalent ions (Mg2+) in addition to monovalent ions in the external solution reduces the critical salt concentration for the discontinuous transition by several orders of magnitude. Moreover, a secondary continuous transition is predicted between two highly swollen states for the case of a divalent salt. The present model may be further extended to study volume phase transitions of polyelectrolyte gels in response to other stimuli such as temperature, pH and electrical field.

Characterization of a biodegrading bacterium, Bacillus subtilis, isolated from oil-contaminated soil

Crude oil and its derivatives because of different events and accidents may cause pollution to the environment. A biological treatment is a novel technique that uses microorganisms to remove or neutralize pollutants from a contaminated site. Oil-contaminated soils were sampled, after isolating of soil bacteria, using quantitative and qualitative screening, biosurfactant-producing bacteria were identified and environmental factors on the growth of bacteria and biosurfactant were investigated. In this study, the Bacillus subtilis was identified as the best biosurfactant-producing strain which has the ability to grow in environments with high salinity and temperature and pH > 5. The produced biosurfactant from B. subtilis is stable to changes in temperature and salt concentration and pH (in the range of 5–12).The B. subtilis also showed that they are able to biodegrade aliphatic alkanes. The B. subtilis has necessary potential for bioremediation of oil pollution in the environment.

Integrated bicarbonate-form ion exchange treatment and regeneration for DOC removal: Model development and pilot plant study

The application of bicarbonate-form anion exchange resin and sodium bicarbonate salt for resin regeneration was investigated in this research is to reduce chloride ion release during treatment and the disposal burden of sodium chloride regeneration solution when using traditional chloride-form ion exchange (IX). The target contaminant in this research was dissolved organic carbon (DOC). The performance evaluation was conducted in a completely mixed flow reactor (CMFR) IX configuration. A process model that integrated treatment and regeneration was investigated based on the characteristics of configuration. The kinetic and equilibrium experiments were performed to obtain required parameters for the process model. The pilot plant tests were conducted to validate the model as well as provide practical understanding on operation. The DOC concentration predicted by the process model responded to the change of salt concentration in the solution, and showed a good agreement with pilot plant data with less than 10% difference in terms of percentage removal. Both model predictions and pilot plant tests showed over 60% DOC removal by bicarbonate-form resin for treatment and sodium bicarbonate for regeneration, which was comparable to chloride-form resin for treatment and sodium chloride for regeneration. Lastly, the DOC removal was improved by using higher salt concentration for regeneration.

Optimizing the Preparation, Analysis and Formulation of Liposomes for Drug Delivery Applications

Liposomes, and other lipid based carriers, are useful vehicles for drug delivery applications because they are relatively simple to make, are biocompatible and their size, chemical functionality and stability can be modulated to optimize the drug delivery process. Additionally, targeting moieties can be added to the surface of liposomes that enable specific targeting of tumor or other tissues and help to maximize drug delivery to the targeted area and to reduce non-specific delivery and toxicity.However, liposome size, stability and surface chemistry are all susceptible to changes in the surrounding environment including changes in pH, salt concentration, temperature and storage time. Thus it is critically important to optimize liposome preparation, analysis techniques and storage conditions to ensure that the final liposome formulation will be effective in its desired application.Here we discuss liposome preparation, analysis and formulation using light scattering techniques to assess liposome size and zeta potential, under a wide range of environmental conditions, including variations in temperature, salt concentration, lipid/liposome concentration. It is observed that variations in these parameters significantly affect both liposome size and zeta potential outcomes.

Detection and determination of groundwater contamination plume using time-lapse electrical resistivity tomography (ERT) method

Protection of water resources from contamination and detection of the contaminants and their treatments are among the essential issues in the management of water resources. In this work, the time-lapse electrical resistivity tomography (ERT) surveys were conducted along 7 longitudinal lines in the downstream of the Latian dam in Jajrood (Iran), in order to detect the contamination resulting from the direct injection of a saltwater solution in to the saturated zone in the area. To investigate the pollutant quantities affecting the resistivity of this zone, the temperature and electrical conductivity measurement were carried out using a self-recording device during 20 days (before and after the injection). The results obtained from the selfrecording device measurements and ERT surveys indicated that in addition to the salt concentration changes in water, the resistivity changes in the saturated zone were dependent on other factors such as the lithology and absorption of contaminants by the subsurface layers. Furthermore, the expansion of contamination toward the geological trend, sedimentation, and groundwater flow direction of the area were shown.

Induced-Charge Capacitive Deionization: The Electrokinetic Response of a Porous Particle to an External Electric Field.

We demonstrate the phenomenon of induced-charge capacitive deionization that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electric field. The external electric field induces an electric dipole in the porous particle, leading to its capacitive charging by both cations and anions at opposite poles. This regime is characterized by a long charging time, which results in significant changes in salt concentration in the electrically neutral bulk, on the scale of the particle. We qualitatively demonstrate the effect of advection on the spatiotemporal concentration field, which, through diffusiophoresis, may introduce corrections to the electrophoretic mobility of such particles.

PspAG97A: A Halophilic α-Glucoside Hydrolase with Wide Substrate Specificity from Glycoside Hydrolase Family 97.

A novel α-glucoside hydrolase (named PspAG97A) from glycoside hydrolase family 97 (GH97) was cloned from the deep-sea bacterium Pseudoalteromonas sp. K8, which was screened from the sediment of Kongsfjorden. Sequence analysis showed that PspAG97A belonged to GH97, and shared 41% sequence identity with the characterized α-glucosidase BtGH97a. PspAG97A possessed three key catalytically related glutamate residues. Mutation of the glutamate residues indicated that PspAG97A belonged to the inverting subfamily of GH97. PspAG97A showed significant reversibility against changes in salt concentration. It exhibited halophilic ability and improved thermostability in NaCl solution, with maximal activity at 1.0 M NaCl/KCl, and retained more than 80% activity at NaCl concentrations ranging from 0.8 to 2.0 M for over 50 h. Furthermore, PspAG97A hydrolyzed not only α-1,4-glucosidic linkage, but also α-1,6- and α-1,2-glucosidic linkages. Interestingly, PspAG97A possessed high catalytic efficiency for long-chain substrates with α-1,6-linkage. These characteristics are clearly different from other known α-glucoside hydrolases in GH97, implying that PspAG97A is a unique α-glucoside hydrolase of GH97.

A study on optimal schedule of membrane cleaning and replacement for spiral-wound SWRO system

In this work, the optimal schedule of membrane cleaning and replacement of spiral-wound SWRO (seawater reverse osmosis) system was studied and analyzed under different feed conditions. Firstly, the spiral-wound RO process model described by differential and algebraic equations was established with the consideration of membrane fouling. Then the optimization problem was formulated to minimize the daily cost of the SWRO system, and a new method by which the optimization problem was transformed as an NLP problem was proposed to solve the problem effectively and quickly. The method was used for SWRO case study and was compared with the traditional method in the form of MINLP. Computing results demonstrate that the proposed method has the advantages of efficiency and stability. Moreover, it can get schedule of membrane cleaning and replacement with lower operational cost as well as give more detailed information of membrane channel. Lastly, influence of feed temperature and feed concentration of seawater was analyzed with the new method. Computing results show the stability of the new method and lead to new profiles of optimal operational variables and performance when feed temperature and salt concentration change, which are quite different from those in designed conditions.

Frequency Domain Probe Design for High Frequency Sensing of Soil Moisture

Accurate moisture sensing is an important need for many research programs as well as in control of industrial processes. This paper describes the development of a high accuracy frequency domain sensing probe for use in obtaining dielectric measurements of materials suitable for work ranging from 300 MHz to 1 GHz. The probe was developed to accommodate a wide range of permittivity’s ranging from εr = 2.5 to elevated permittivity’s as high as εr = 40. The design provides a well-matched interface between the soil and the interconnecting cables. A key advantage of the frequency domain approach is that a change of salt concentration has a significantly reduced effect on ε′, versus the traditional time-domain reflectometry, TDR, measured apparent permittivity, Ka.

The impact of water-intake for a tributary on the flow and saline intrusion in the lower Han River

The instream flow of the Ara River is to be supplied from the Han River, and so an Environmental Fluid Dynamics Code (EFDC) model was applied to investigate the impact of water-intake to the Ara River on the total river flow and saline water intrusion. Through the numerical simulation of flow and saline water intrusion under different drainage conditions, it was found that the water intake for the Ara River has an impact not only on the hydraulic characteristics (water level and flow rate), but also on the extent of saline water intrusion in the Han River. It was also found that the change of discharge in the Han River, caused by the water supplying to the Ara River, can increase the salt concentration in the vicinity of the Singok Submerged Weir by 0.5 psu. As agricultural productivity can be affected by even this small amount of salt concentration change, much closer attention should be paid to the relation between water-intake condition and its effect on the Han River.

Characterization of duck plague virus stability at extreme conditions of temperature, pH and salt concentration

Duck plaque virus (DPV) belongs to the family Herpesviridae. The live attenuated vaccine is the only way to protect the ducks from DPV infection. The ineffectiveness of vaccine is one of the major causes of DPV outbreaks in the field condition. DPV is not well characterized for its pathogenicity and molecular biology in poultry. In the present study, we discuss briefly about the biology of DPV and its proteins under different conditions of temperature and pH in order to evaluate its infectivity under adverse physical conditions. Our results indicate that the DPV is non-infective above 42 °C and unstable above 65 °C. In addition, change in pH or salt concentrations significantly decreases the stability of the DPV. The study will be useful in estimating an optimum storage condition for DPV vaccines without causing any deterioration in its viability and effectiveness.

Evaluation of Staphylococcus aureus DNA aptamer by enzyme-linked aptamer assay and isothermal titration calorimetry.

To monitor the specificity of Staphylococcus aureus aptamer (SA-31) against its target cell, we used enzyme-linked aptamer assay. In the presence of target cell, horseradish peroxidase-conjugated streptavidin bound to biotin-labeled SA-31 showed specific binding to S aureus among 3 different bacteria with limit of detection of 103 colony-forming unit per milliliter. The apparent Ka was 1.39 μM-1 ±0.3 μM-1 . The binding of SA-31 to membrane proteins extracted from cell surface was characterized using isothermal titration calorimetry, and the effect of changes in binding temperature and salt concentrations of binding buffer was evaluated based on thermodynamic parameters (Ka , ΔH, and ΔG). Since binding of aptamer to its targets solely depends on its 3-dimensional structure under experimental conditions used in selection process, the change in temperature and ion concentration changed the affinity of SA-31 to its target on surface of bacteria. At 4°C, SA-31 did not show an affinity to its target with poor heat change upon injection of membrane fraction to aptamer solution. However, the apparent association constants of SA-31 slightly varied from Ka =1.56 μM-1 ±0.69 μM-1 at 25°C to Ka =1.03 μM-1 ±0.9 μM-1 at 37°C. At spontaneously occurring exothermic binding reactions, affinities of Saureus aptamer to its target were also 9.44 μM-1 ±0.38 μM-1 at 50mM, 1.60 μM-1 ±0.11 μM-1 at 137mM, and 3.28 μM-1 ±0.46 μM-1 at 200 mM of salt concentration. In this study, it was demonstrated that enzyme-linked aptamer assay and isothermal titration calorimetry were useful tools for studying the fundamental binding mechanism between a DNA aptamer and its target on the outer surface of Saureus.

Response of young bearing olive trees to irrigation-induced salinity

Expansion of irrigated olives, combined with prevalence of water containing dissolved salts, leads to irrigation-induced exposure of olive trees to salinity. Root zone salinity can rise either as a function of increasing input irrigation water salinity (ECi) or relative reductions in water for leaching. We investigated five ECi levels from 0.5 to 11.0 dS m−1 with a constant leaching fraction (LF) of 0.29 and five leaching levels from 0.05 to 0.44 (drainage: irrigation ratio) with water of ECi = 5.0 dS m−1 on young bearing Olea europaea cv Barnea olive trees grown in 2.5 m3 weighing-drainage lysimeters over three years. Tree-scale response to increased salinity did not demonstrate any sign of a threshold value and was not differentiated by the cause of salinity, be it changes in input irrigation water salt concentrations or changes in LF. Soil salinity, measured as electrical conductivity of saturated soil paste extract (ECe) and maintained at stable levels over time, decreased tree water consumption and tree size measured as trunk area or above-ground biomass by 40–60 % as it increased from 1.2 to around 3.5–4.0 dS m−1. Further increases in ECe to as high as 7.5 dS m−1 brought these parameters to 20–30 % of the treatment with low salinity. Fruit yield also decreased with increasing salinity, albeit with less drastic relative effects. An analytical model calculating water and salt balance and subsequent evapotranspiration or biomass as a function of irrigation water quantity and salinity successfully predicted the measured results.

Capacitive neutralization deionization with flow electrodes

Capacitive neutralization deionization with flow electrodes (FCND) was proposed by combining neutralization dialysis (ND) and flow-electrode capacitive deionization (FCDI). Its key property is that by employing flow electrodes, capacitive adsorption of salt ions occurs simultaneously during the neutralization dialysis process. To compare the desalination performance between FCND and FCDI, a series of experiments were conducted by changing salt concentration and applied electrical voltage. The hybrid exhibits a promising average salt adsorption rate (ASAR) and salt removal efficiency (SRE) compared to either ND or FCDI process. The ASAR and SRE of FCND are 203.27mmolm−2min−1 and 72.20% in 0.1mM NaCl solution at 1.2V after 120min, whereas the values of FCDI are 120.86mmolm−2min−1 and 42.92%, respectively. In order to facilitate the understanding of the ion transportation in this complex system, a theory was also set up based on simplified Nernst-Planck equation and Donnan equilibrium, which helps to understand the experimental data.