Effect Of Various Salts Research Articles

Experimental investigation of wettability alteration, IFT reduction, and injection schemes during surfactant/smart water flooding for EOR application

In recent years, the application of smart water and surfactant in order to improve oil recovery has attracted special attention in carbonate reservoirs. In this research, the effects of various salts in smart water and two surfactants of Cetyl Trimethyl Ammonium Bromide (CTAB) and Sodium Dodecyl Sulfate (SDS) on the wettability alteration of carbonate rock and IFT were studied. Besides, along with micromodel flooding, core flooding tests were conducted to assess the amount of oil recovery at reservoir conditions as an injection scheme was used. In this regard, the results illustrated that the presence of CTAB or SDS in seawater (SW) can act better in contact angle reduction compared to smart water. Also, a four times increase in the concentration of SO42− and removing Na+ from SW reduced the contact angle to 68° and 71°, respectively, being the best possible options to alter the carbonate surface wettability to more water-wet states. Moreover, in the second-order process in which the rock section was first placed in SW, and then was put in the smart solution (with or without surfactant), CTAB had a great effect on the wettability alteration. In the case of IFT reduction, although SW4Mg2+, compared to other ions, better decreased the IFT to 17.83 mN/m, SW + SDS and SW + CTAB further declined the IFT to 0.67 and 0.33 mN/m, respectively. Concerning different ions, divalent cations (Mg2+ and Ca2+) show better results in improving oil recovery factor. However, the combination of SW and surfactants has a more positive effect on boosting oil recovery, as compared to smart water flooding. It should be mentioned that the first-order injection is better than the second-order one since SW is flooded at first, and then, after the breakthrough, smart water is injected into the micromodel. In addition, the core flooding tests showed that SW + CTAB and SW + SDS in tertiary injection increased the oil recovery to about 59 and 57%, respectively, indicating that the presence of CTAB could be more effective than that of SDS.

Stimuli-Responsive Properties of Supramolecular Gels Based on Pyridyl-N-oxide Amides

The nature of functional groups and their relative position and orientation play an important role in tuning the gelation properties of stimuli-responsive supramolecular gels. In this work, we synthesized and characterized mono-/bis-pyridyl-N-oxide compounds of N-(4-pyridyl)nicotinamide (L1-L3). The gelation properties of these N-oxide compounds were compared with the reported isomeric counterpart mono-/bis-pyridyl-N-oxide compounds of N-(4-pyridyl)isonicotinamide. Hydrogels obtained with L1 and L3 were thermally and mechanically more stable than the corresponding isomeric counterparts. The surface morphology of the xerogels of di-N-oxides (L3 and diNO) obtained from the water was studied using scanning electron microscopy (SEM), which revealed that the relative position of N-oxide moieties did not have a prominent effect on the gel morphology. The solid-state structural analysis was performed using single-crystal X-ray diffraction to understand the key mechanism in gel formation. The versatile nature of N-oxide moieties makes these gels highly responsive toward an external stimulus, and the stimuli-responsive behavior of the gels in water and aqueous mixtures was studied in the presence of various salts. We studied the effect of various salts on the gelation behavior of the hydrogels, and the results indicated that the salts could induce gelation in L1 and L3 below the minimum gelator concentration of the gelators. The mechanical properties were evaluated by rheological experiments, indicating that the modified compounds displayed enhanced gel strength in most cases. Interestingly, cadmium chloride formed supergelator at a very low concentration (0.7 wt% of L3), and robust hydrogels were obtained at higher concentrations of L3. These results show that the relative position of N-oxide moieties is crucial for the effective interaction of the gelator with salts/ions resulting in LMWGs with tunable properties.

An inhibitory mechanism for suppressing high salt intake in Drosophila.

High concentrations of dietary salt are harmful to health. Like most animals, Drosophila melanogaster are attracted to foods that have low concentrations of salt, but show strong taste avoidance of high salt foods. Salt in known on multiple classes of taste neurons, activating Gr64f sweet-sensing neurons that drive food acceptance and 2 others (Gr66a bitter and Ppk23 high salt) that drive food rejection. Here we find that NaCl elicits a bimodal dose-dependent response in Gr64f taste neurons, which show high activity with low salt and depressed activity with high salt. High salt also inhibits the sugar response of Gr64f neurons, and this action is independent of the neuron's taste response to salt. Consistent with the electrophysiological analysis, feeding suppression in the presence of salt correlates with inhibition of Gr64f neuron activity, and remains if high salt taste neurons are genetically silenced. Other salts such as Na2SO4, KCl, MgSO4, CaCl2, and FeCl3 act on sugar response and feeding behavior in the same way. A comparison of the effects of various salts suggests that inhibition is dictated by the cationic moiety rather than the anionic component of the salt. Notably, high salt-dependent inhibition is not observed in Gr66a neurons-response to a canonical bitter tastant, denatonium, is not altered by high salt. Overall, this study characterizes a mechanism in appetitive Gr64f neurons that can deter ingestion of potentially harmful salts.

Type of Anion Largely Determines Salinity Tolerance in Four Rumex Species.

The aim of the present study was to compare the effect of various salts composed of different cations (Na+, K+) and anions (chloride, nitrate, nitrite) on growth, development and ion accumulation in three Rumex species with accessions from sea coast habitats (Rumex hydrolapathum, Rumex longifolius and Rumex maritimus) and Rumex confertus from an inland habitat. Plants were cultivated in soil in an experimental automated greenhouse during the autumn-winter season. Nitrite salts strongly inhibited growth of all Rumex species, but R. maritimus was the least sensitive. Negative effects of chloride salts were rather little-pronounced, but nitrates resulted in significant growth stimulation, plant growth and development. Effects of Na+ and K+ at the morphological level were relatively similar, but treatment with K+ salts resulted in both higher tissue electrolyte levels and proportion of senescent leaves, especially for chloride salts. Increases in tissue water content in leaves were associated with anion type, and were most pronounced in nitrate-treated plants, resulting in dilution of electrolyte concentration. At the morphological level, salinity responses of R. confertus and R. hydrolapathum were similar, but at the developmental and physiological level, R. hydrolapathum and R. maritimus showed more similar salinity effects. In conclusion, the salinity tolerance of all coastal Rumex species was high, but the inland species R. confertus was the least tolerant to salinity. Similarity in effects between Na+ and K+ could be related to the fact that surplus Na+ and K+ has similar fate (including mechanisms of uptake, translocation and compartmentation) in relatively salt-tolerant species. However, differences between various anions are most likely related to differences in physiological functions and metabolic fate of particular ions.

Effect of Various Salts on the Vertical Migration of 90Sr in Gray Forest Soil

Effect of Various Salts on the Vertical Migration of 90Sr in Gray Forest Soil

Influence of pH, Humic Acids, and Salts on the Dissipation of Amoxicillin and Azithromycin Under Simulated Sunlight

This work is focused on the study of the dissipation of the antibiotics amoxicillin (AMX) (an amino penicillin) and azithromycin (AZT) (belonging to the macrolide group), performed at a laboratory scale, under simulated sunlight and in the dark, at pH values 4.0, 5.5, and 7.2, and in the presence of humic acids and different inorganic salts. The results indicate that AMX is more affected than AZT by simulated sunlight, with half-lives ranging 7.7–9.9 h for AMX and 250–456 h for AZT. The lowest half-life values were obtained at pH 7.2 for AMX (7.7 h) and at pH 4.0 for AZT (250 h). Regarding the effect of various salts, the presence of NaNO3 causes that C/C0 decreases from 0.6 to 0 under simulated sunlight, having no effect on the dissipation of AMX in the dark. However, in the presence of FeCl3 at concentrations of 500 mg L−1, AMX suffered total dissipation, both under simulated sunlight and in the dark. For AZT the influence was lower, and the salts that caused a higher increase in its dissipation were NaCl (with C/C0 decreasing from 0.5 to 0.2) and CaCl2 (C/C0 decreasing from 0.5 to 0.3). The presence of humic acids caused a slight increase in the dissipation of AMX, both under simulated sunlight and in the dark, a fact that was attributed to the adsorption of the antibiotic onto these organic substances, which, however, caused a more marked increase in the dissipation of AZT (reaching 68%) under simulated sunlight. The overall results of this research can be considered clearly relevant, mainly to determine the fate of AMX and AZT when these antibiotics reach the environment as pollutants, either as regards their exposure to natural sunlight, or in relation to the use of inactivation/photo-degradation systems in decontamination procedures focused on environmental compartments.

Investigation of the effects of salinity on the amount of asphaltene formed from emulsions Water–Oil

Asphaltene deposition is a very serious issue that in addition to clogging the pores, changes wettability, reduces permeability, and, as a result, reduces production and increases process costs. Recent research has shown that water formation can affect asphaltene deposition. In this regard, the effect of various salts including NaCl, KCl, CaCl2, and Na2SO4 in concentrations of 5000, 10000, 20000, 50000, and 100000 ppm on the amount of asphaltene formed from water–oil emulsions was investigated. The ratio of oil to saline water used in this experiment is 1 to 4 and also the amount of asphaltene in the oil used is 5.725%. These experiments were performed by the standard IP-143 test. It was observed that with the increasing concentration of NaCl and KCl, the amount of asphaltene in the oil phase decreases that is due to the presence of monovalent ions. In CaCl2 and Na2SO4 salts due to the presence of ions, multi-capacitance increases. Asphaltene has an aromatic structure with N-, S-, and O- atoms. These functional groups in crude oil with sometimes acidic media can be protonated to form states of organic salts. Moreover, some parts of asphaltene have more electromagnetic properties, which create an oscillating peak.

Non-diaphragm electrodeposition of antimony: Effect of process parameters and precipitating agents

Metallic antimony production from antimony-bearing materials is a research hotspot. The conventional electrowinning technology of antimony is a challenging problem due to the sulfur compounds that come from both the ore itself and the leaching solution in the electrolysis system. The electro-production of antimony in modified non-diaphragm cells is of interest because of the high price and maintenance issues associated with diaphragm cells. A sulfur-based problem in non-diaphragm cells was the focus of this study, which investigated the effects of various salts on this problem and also optimized antimony production conditions. Various salts (i.e., BaCl2, CaCl2, Ba(OH)2, Ca(OH)2) were used as a precipitating agent for the formation of insoluble salts (BaSO4/CaSO4 and BaSO3/CaSO3). Sb concentration, amount of NaOH and Na2S in the bath, electrowinning time, and temperature were investigated to optimize reaction parameters. The Taguchi experimental design was used to determine the effect of each factor on the Sb deposition. The phases and structures formed during electroproduction were identified with the help of various measurement techniques. This study found that in the presence of 96 mM BaCl2, 45 g/L of Sb concentration, 100 g/L of NaOH, and 60 g/L of Na2S were the most suitable factors. It was found that 40 oC was the optimal electrowinning temperature. This result also demonstrated that increasing concentrations of BaCl2 reduced specific energy consumption.

Computer Simulation of the Surface of Aqueous Ionic and Surfactant Solutions.

The surface of aqueous solutions of simple salts was not the main focus of scientific attention for a long while. Considerable interest in studying such systems has only emerged in the past two decades, following the pioneering finding that large halide ions, such as I-, exhibit considerable surface affinity. Since then, a number of issues have been clarified; however, there are still several unresolved points (e.g., the effect of various salts on lateral water diffusion at the surface) in this respect. Computer simulation studies of the field have largely benefited from the appearance of intrinsic surface analysis methods, by which the particles staying right at the boundary of the two phases can be unambiguously identified. Considering complex ions instead of simple ones opens a number of interesting questions, both from the theoretical point of view and from that of the applications. Besides reviewing the state-of-the-art of intrinsic surface analysis methods as well as the most important advances and open questions concerning the surface of simple ionic solutions, we focus on two such systems in this Perspective, namely, the surface of aqueous mixtures of room temperature ionic liquids and that of ionic surfactants. In the case of the former systems, for which computer simulation studies have still scarcely been reported, we summarize the theoretical advances that could trigger such investigations, which might well be of importance also from the point of view of industrial applications. Computer simulation methods are, on the other hand, widely used in studies of the surface of surfactant solutions. Here we review the most important theoretical advances and issues to be addressed and discuss two areas of applications, namely, the inclusion of information gathered from such simulations in large scale atmospheric models and the better understanding of the airborne transmission of viruses, such as SARS-CoV-2.

The extraction of hexamethylenediamine from aqueous solution by pH control and salt addition: The extraction of HMD from aqueous solution by NaOH and salt

This paper details an investigation into the separation of Hexamethylenediamine (HMD) from dilute aqueous solutions by exploiting phase separation. HMD is a monomer used in the production of Nylon-6,6 and as such this separation is potentially useful in extracting purifying HMD produced from biological sources or reclaimed from waste made by the production of nylon. An investigation was undertaken into the effect of using sodium hydroxide (NaOH) to promote the phase separation, and a model was derived to predict this behaviour. Furthermore, the effect of various salts on this phase separation was investigated, and it was found that sodium sulphate and sodium carbonate promote the phase separation, but are unable to cause phase separation without the presence of sodium hydroxide.

Effect of Sodium Nitrite, Sodium Chloride and Concentrated Seawater on Physicochemical Properties of Meat Emulsion System.

The objective of this study was to compare the effects of various salts on the physicochemical properties of pork emulsion sausages. Pork sausages were prepared using two different salts, sodium nitrite (SN) and sodium chloride (SC), and concentrated seawater (CSW). The CIE L*, CIE a*, and CIE b*, and chroma values of cooked and uncooked sausages with added CSW were significantly higher than those of the sausages with added SC (p<0.05). However, uncooked and cooked sausages with added SN and CSW had similar CIE a* values (p>0.05). The residual NO2− content of sausages with added CSW was significantly lower than that of sausages with added SN. Addition of CSW to sausages resulted in a higher cooking yield compared to the other treatments (p<0.05). Addition of SC resulted in significantly higher volatile basic nitrogen (VBN) and thiobarbituric acid (TBA) values compared to the other treatments. Furthermore, addition of CSW enhanced important physicochemical properties, including CIE a*, CIE b*, residual nitrite content, cooking yield, VBN, TBA, textural properties, and cross-sectional area.

The Hofmeister effect on protein hydrogels with stranded and particulate microstructures

The infiltration of ions into hydrogel matrix could significantly affect the microstructure and macroscopic mechanics of the gels. Here, the Hofmeister effect of various salts on the whey protein isolate hydrogels with fine-stranded and particulate microstructures is investigated by soaking the preformed hydrogels in the sodium salts of different anions. The infiltration of kosmotropic anions yield stiffer hydrogels, whereas the chaotropic anions soften the hydrogels. The hydrogels with fine-stranded microstructures are more sensitive to the salts comparing to the particulate ones due to the microscopic phase transitions and enhanced hydrophobic interactions between polymer chains occurred in fine-stranded hydrogels. Besides, despite the significant difference in water binding ability of different salts, the water holding capacity of the salt-treated hydrogels was mainly determined by the gel stiffness instead of the salt types. Similar mechanical responses of BSA and egg white protein hydrogels to the Hofmeister series was also demonstrated, suggesting that the results shown here could potentially be generalized for other globular protein hydrogels.

Clathrate hydrate based approach for concentration of sugar aqueous solution, orange juice, and tomato juice: Phase equilibrium modeling using a thermodynamic framework

Utilization of hydrate formation appears to be an efficient technology to facilitate concentration process of various juices in the food industry. This research work examines a thermodynamic approach to simulate the concentration operation of sugar solutions in terms of process feasibility and effectiveness. To attain this objective, the previously presented semi-theoretical framework for exploring the inhibition effects of various salts and alcohols (thermodynamic inhibitors) on the equilibrium stability conditions of methane hydrates was extended to forecast the methane/carbon dioxide hydrate dissociation temperature in the presence of sugar aqueous solutions, orange juice, and tomato juice. The experimental liquid-hydrate-vapor (L-H-V) three-phase equilibrium data of CH4+xylose/xylitol + water and CO2+sucrose/fructose + water systems were gathered from the literature. A new empirical correlation capable of estimating the incipient stability curve of the carbon dioxide hydrate in pure water was developed using the real data reported in the time interval of 1946–2017. Furthermore, the phase equilibria conditions of CO2 hydrate in orange juice and tomato juice were modelled. For all the studied methane and carbon dioxide hydrate systems, the proposed approach reproduces the experimental data with absolute deviations around 0.3 and 0.2 K, respectively, within the temperature, pressure, and solution concentration ranges of the collected data. For CO2+orange and tomato juice hydrate systems, the absolute errors were found to be 0.17 and 0.06, respectively. This research work has potentials to design and operate an efficient-energy strategy for concentrating different types of sugar solutions in the food industry.

Polymerization of aniline in different salt solutions and the structure-dependent electrical properties of the products.

<p indent="0mm">In this study, the polymerization of aniline at room temperature with H₂O₂/HCl as an oxidizing agent was studied in different salt media. The effects of various salts (NaCl, CuCl₂, NiCl₂, FeSO₄, CuSO₄) on the polymerization rates of aniline, the productivities and the structure-dependent electrical properties of polyaniline were addressed as well. The results showed that NaCl could be used as a catalyst to promote the polymerization of aniline, and the transition metals, like Ni²⁺, Cu²⁺ and Fe²⁺ increased the polymerization rate of aniline more significantly. The addition of CuCl₂ made the yield of polyaniline over 95%. In the salt media, the morphology of polyaniline changed from nanofibers to complicated nanostructure, such as short rod, coral and sphere particles. Apart from Fe²⁺ salt, Na⁺, Ni²⁺, and Cu²⁺ are all benefit to the doping of polyaniline, thereby increasing the electrical conductivity. Polyaniline prepared in Fe²⁺ medium was amorphous and non-conductive because the synthesized polyaniline was in reduced form and the Fenton reaction between Fe²⁺ and H₂O₂ reduced the doping degree of the products.

Salinity driven stress to enhance lipid production in Scenedesmus vacuolatus: A biodiesel trigger?

The main aim of the present study is to understand algae behaviour and enhancement of the intracellular neutral lipid content of freshwater green microalgae, Scenedesmus vacuolatus, under salt exposure. Effects of various salts (sodium chloride, magnesium chloride and calcium chloride) on this species were analysed by measuring parameters such as growth rate, chlorophyll content, neutral lipid intensity and conducting FAME profiling. When under stress, microalgae divert their metabolic pathways towards lipid synthesis, and this is evidenced in the current study. Compared to controlled and unmodified media cultivation, sodium chloride and magnesium chloride exposure promoted 383% and 340% higher fluorescence intensities, respectively, and there was a significant increase in the FAME content, particularly of saturated fatty acids (such as palmitic and stearic acid) at a magnesium chloride concentration of 50 mM and calcium chloride exposure of 70 mM, with percentage increases of 109% and 253%, respectively, compared to the control. Algal cells were found to be more tolerant towards NaCl than other salts, and this was confirmed through the biomass accumulation profile. Biomass productivity was highest at exposure to 100 mM sodium chloride (33 mgL−1d−1) followed by calcium chloride (19.5 mgL−1d−1) and magnesium chloride (12.6 mgL−1d−1). Confocal imaging further supported the results, and scanning electron microscopy revealed changes in algal surface morphology. This study provides further information about stress-driven lipid biosynthesis and analyses changes in cellular morphology and physiology. However, further exploration and systematically studies are required to determine exact mechanism involved in neutral lipid enhancement inside cells and associated metabolomics.

Effect of various salts on the growth and development of Geotrichum candidum, the causal agent of carrot sour rot

AbstractThis study evaluated the efficacy of ammonium, calcium, potassium and sodium salts as possible alternatives to synthetic fungicides in the control of Geotrichum candidum, the causal agent of sour rot on carrots. In vitro mycelial growth of G. candidum was completely halted by ammonium bicarbonate and carbonate; calcium oxide; potassium benzoate, carbonate and sorbate; sodium benzoate, carbonate and fluoride (2% w/v). Potassium and sodium bicarbonate also reduced mycelial growth by 77.78% and 90.60%, respectively, and the difference between the effects of sodium bicarbonate and the first group of salts was not statistically significant (p &lt; 0.05). With the exception of potassium and sodium bicarbonate, the above‐mentioned salts also halted or strongly reduced arthrospore germination. Potassium bicarbonate, and sodium bicarbonate, acetate and propionate significantly increased conidiation (p &lt; 0.05). Of all the salts tested in vitro, only ammonium bicarbonate and carbonate, calcium oxide and sodium fluoride were toxic to G. candidum. In in vivo studies, all the calcium salts tested (acetate, chloride, citrate, formate, lactate, oxide, propionate and silicate), several of the sodium salts (acetate, bicarbonate, chloride and fluoride) and potassium bicarbonate exhibited both protective and curative activity against G. candidum, significantly reducing the severity of sour rot in comparison to pathogen‐inoculated controls (p &lt; 0.05). Although no curative was observed with ammonium bicarbonate, ammonium carbonate, potassium carbonate, potassium chloride, sodium carbonate or sodium citrate, these salts also demonstrated significant protective activity against sour rot when compared to controls (p &lt; 0.05). In sum, the study findings show that all of the selected salts may be used to control carrot sour rot, except for sodium fluoride, which exhibited phytotoxicity to carrots.

Impedometric investigation of salt effects on electromembrane extraction: Practical hints for pH adjustment

In the current work, an impedance system is developed to investigate the time variation of solution resistance, membrane resistance, and double layer capacitance during electromembrane extraction from salty solutions. For this purpose, the adverse effects of various salts such as NaCl, NaF, NaNO3, KNO3, KCl, LiCl, CH3COONa, Na2SO4, Na3PO4, MgCl2, LiClO4 and K2CO3 are studied. Two different model analytes are used including Naproxen and Verapamil as an acidic and basic drugs, respectively. In order to obtain a quantitative measure of the adverse effect of various salts, the recoveries were calculated along with those for the extraction from salt free donor phases. The decline of the recovery (called suppression throughout this work), due to the presence of the salt was taken as the quantitative measure of the adverse effect. In the case of the acidic drug, the percent suppression values had a wide range from 26.95 to 85.23%, except in the presence of LiClO4 which gave a suppression of 100%. The presence of salts during the extraction of the basic model analyte resulted in two different patterns. While NaNO3 and CH3COONa caused complete (100%) suppression, the rest of salts gave lower suppression values in the range of 16.99–38.32%. The impedance analysis results show that the free energy of transfer of accompanying ions has a significant effect on the time dependence of solution resistance and double layer capacitance. It is also shown that the suppression of recovery is significantly correlated with the rate and timescale of depletion of ionic species from the donor solution as well as the propagation of the double layer. In summary, it can be concluded that, when working with simple acids/bases for pH adjustment in EME, smaller counter ions are preferred.

Anti-ageing skin effects of Korean bamboo salt on SKH1 hairless mice.

Bamboo salt is generated by baking bamboo and sea salt and is used as a traditional food or medicine. The aim of this study was to investigate the anti-ageing skin effects of Korean bamboo salt and to compare the antioxidant, anti-ageing and anti-inflammatory effects of various salts, including purified salt, solar salt, bath solar salt, Masada solar salt, 1-time baked bamboo salt (1× bamboo salt), and 9-times baked bamboo salt (9× bamboo salt). Based on the content of mineral elements, pH, OH groups and redox potential amperometric analysis, the 9× bamboo salt showed the most antioxidant components and characteristics compared to the other salts. The in vitro results showed that the 9× bamboo salt could inhibit oxidative damage by hydrogen peroxide (H2O2) treatment in HaCaT keratinocytes, and its effect was better than that of the other salts. In an in vivo experiment, SHK-1 hairless mice were treated with UV (ultraviolet) radiation to induce ageing. The epidermal thickness and epidermal structures were then assessed by phenotypic and histological analyses. The 0.2% 9× bamboo salt- and 1× bamboo salt-treated mice had a thinner epidermis than the control mice, and the sebaceous glands were almost intact with a regular arrangement that was similar to those in the normal group. Compared with the UV-treated group (control group) and other salt-treated groups, the 9× bamboo salt- and 1× bamboo salt-treated groups had higher dermal collagen and elastic fibre content. Fewer mast cells were observed in the 9× bamboo salt- and 1× bamboo salt-treated groups than in the control group. The activities of the skin antioxidant-related enzymes superoxide dismutase (SOD) and catalase (CAT) in the 9× bamboo salt- and 1× bamboo salt-treated groups were higher than those in other groups and similar to those in the normal group, but lipid peroxide (LPO) activity and carbonylated protein levels showed the opposite trends. Furthermore, the 9× bamboo salt- and 1× bamboo salt-treated groups had protein contents similar to those of the normal group. In addition, the 9× bamboo salt and 1× bamboo salt effectively down-regulated the expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) and up-regulated the expression of tissue inhibitor expression of matrix metalloproteinase-1 (TIMP-1), matrix metalloproteinase-2 (TIMP-2), SOD and CAT compared to the other salts at a concentration of 0.2% (p < 0.05). These results suggest that at appropriate concentrations, bamboo salt could prevent skin ageing induced by ultraviolet radiation b (UVB) photodamage.

Deciphering the effect of salts on Bilirubin Oxidases activity

Bilirubin Oxidases (BODs) and laccases belong to the Blue Multicopper Oxidases family (MCOs). Both enzymes couple the oxidation of substrates to the reduction of O2 to H2O. In contrast to laccases, BODs display high activity and stability at neutral pH and are more tolerant to chloride [1]. These unique features make BODs useful in a large number of biotechnological applications such as biosensors for jaundice detection, dyes degradation, and as a cathodic enzyme in enzymatic biofuel cells [2]. Glucose/oxygen enzymatic biofuel cells use the energy of redox reactions catalyzed by enzymes to produce electrical energy. Glucose oxidizing enzymes such as Glucose Oxidase (GOX) and oxygen reducing enzymes such as BODs are used at the anode and at the cathode respectively. Such biofuel cells are good candidates to be implanted in the human body of diabetic people and would be the only in vivo power source able to power glucose sensors. To be implanted, cathodic and anodic enzymes have to be enough stable and resistant to physiological salts to be efficient several weeks or months in biological fluids.Here, I will focus my presentation on the enzymatic cathodic part. BODs and laccases are well known to be sensitive to high salt concentrations [3] and their stability on the electrode needs to be improved. Efforts in this direction allowed our team to identify the BOD from Bacillus pumilus with interesting features as a cathodic enzyme [4]. By using a sequence analysis approach, a new BOD was identified with very interesting features compared to other BODs which makes it of great interest to be used as a cathodic enzyme in biofuel cells.Particularly, in contrast to most BODs described, this new BOD is not inhibited but activated by several salts (up to 1,7 times). This characteristic makes this BOD very interesting considering the fact that all biological fluids contain relatively high levels of salts (such as 140mM NaCl in the blood for example). For this reason, we have compared the effect of various salts and their mechanisms on the enzymatic activity of BOD from Bacillus pumilus and the new BOD in solution and immobilized on electrode. Molecular modeling studies were also performed on both enzymes to decipher the mechanisms of activation/inhibition of different salts and more precisely the sodium chloride effects at the atomic level.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Tuning the collapse transition of weakly charged polymers by ion-specific screening and adsorption.

The experimentally observed swelling and collapse response of weakly charged polymers to the addition of specific salts displays quite convoluted behavior that is not easy to categorize. Here we use a minimalistic implicit-solvent/explicit-salt simulation model with a focus on ion-specific interactions between ions and a single weakly charged polyelectrolyte to qualitatively explain the observed effects. In particular, we demonstrate ion-specific screening and bridging effects cause collapse at low salt concentrations whereas the same strong ion-specific direct interactions drive re-entrant swelling at high concentrations. Consistently with experiments, a distinct salt concentration at which the salting-out power of anions inverts from the reverse to direct Hofmeister series is observed. At this so called isospheric point, the ion-specific effects vanish. Furthermore, with additional simplifying assumptions, an ion-specific mean-field model is developed for the collapse transition which quantitatively agrees with the simulations. Our work demonstrates the sensitivity of the structural behavior of charged polymers to the addition of specific salt beyond simple screening and shall be useful for further guidance of experiments.