Effect of chloride salt concentration on unconfined compression strength of cement-treated Lianyungang soft marine clay

This study aims to quantify the influence of the amount of cement and chloride salt on the unconfined compression strength （UCS） of Lianyungang marine clay. The clays with various sodium chloride salt concentrations were prepared artificially and stabilized by ordinary Portland cement with various contents. A series of UCS tests of cement stabilized clay specimen after 28 d curing were carried out. The results indicate that the increase of salt concentration results in the decrease in the UCS of cement-treated soil. The negative effect of salt concentration on the strength of cement stabilized clay directly relates to the cement content and salt concentration. The porosity-salt concentration/cement content ratio is a fundamental parameter for assessing the UCS of cement-treated salt-rich clay. An empirical prediction model of UCS is also proposed to take into account the effect of salt concentration. The findings of this study can be referenced for the stabilization improvement of chloride slat- rich soft clay.

Decondensation behavior of DNA chains induced by multivalent cations at high salt concentrations:Molecular dynamics simulations and experiments

Using molecular dynamics simulations and atomic force microscopy （AFM）, we study the decondensation process of DNA chains induced by multivalent cations at high salt concentrations in the presence of short cationic chains in solutions. The typical simulation conformations of DNA chains with varying salt concentrations for multivalent cations imply that the concentration of salt cations and the valence of multivalent cations have a strong influence on the process of DNA decondensation. The DNA chains are condensed in the absence of salt or at low salt concentrations, and the compacted conformations of DNA chains become loose when a number of cations and anions are added into the solution. It is explicitly demonstrated that cations can overcompensate the bare charge of the DNA chains and weaken the attraction interactions between the DNA chains and short cationic chains at high salt concentrations. The condensation-decondensation transi- tions of DNA are also experimentally observed in mixing spermidine with X-phage DNA at different concentrations of NaCl/MgCl2 solutions.

Tuning hybrid liquid/solid electrolytes by lowering Li salt concentration for lithium batteries

Hybrid liquid/solid electrolytes（HLSEs） consisting of conventional organic liquid electrolyte（LE）, polyacrylonitrile（PAN）, and ceramic lithium ion conductor Li（1.5）Al（0.5）Ge（1.5）（PO4）3（LAGP） are proposed and investigated. The HLSE has a high ionic conductivity of over 2.25 × 10^（-3） S/cm at 25？C, and an extended electrochemical window of up to 4.8 V versus Li/Li＋. The Li｜HLSE｜Li symmetric cells and Li｜HLSE｜Li FePO4 cells exhibit small interfacial area specific resistances（ASRs） comparable to that of LE while much smaller than that of ceramic LAGP electrolyte, and excellent performance at room temperature. Bis（trifluoromethane sulfonimide） salt in HLSE significantly affects the properties and electrochemical behaviors. Side reactions can be effectively suppressed by lowering the concentration of Li salt. It is a feasible strategy for pursuing the high energy density batteries with higher safety.

Folding of EK peptide and its dependence on salt concentration and pH: A computational study

In this study, we apply both palrwise AMBER03 force field and the recently developed polarized force field to study the folding process of EK peptide under various ion strength and pH conditions. The polarized force field is based on our newly proposed adaptive hydrogen bond-specific charge （AHBC） scheme. These two force fields differ only by the atomic charges. Solvent effect is described with generalized Born models （IGB5 in AMBER 10 package）. The result shows that although when applying AMBER03 charge, the helical structure is preferred, its dependence on salt concentration and pH is qualitatively wrong. While using AHBC the peptide finds its native structure within 10 ns, and then fluctuates around this folded state. Under high salt concentration or extreme pH conditions the calculated helical structure probability drops, which is in qualitative agreement with the experiment. Analysis of the atomic charges and the interaction between the donor-acceptor pair in main hydrogen bonds shows that the helical structure is stabilized when polarization effect is counted. It again shows that polarization effect is a very important improvement over traditional force field and is essential for protein folding. We also prove that the salt bridge interaction between 4-residue apart GLU and LYS residues is not critical to the stability of helical structure of EK peptide, but is merely an auxiliary factor, also in agreement with the experiment.

Thermodynamic Insights of Base Flipping in TNA Duplex: Force Fields, Salt Concentrations, and Free-Energy Simulation Methods

Threofuranosyl nucleic acid(TNA)is an analogue of DNA with a shift in the internucleotide linkages from the wild-type 5’-to-3’direction to 3’-to-2.’This alteration leads to higher chemical stability,less reactive groups,and lower conformational flexibility.Experimental observations indicate that these characteristic changes are attributable to a minimal perturbation of the interaction network,but the thermodynamic stability of the duplex remains unaltered in the TNA mutation.We applied the equilibrium and nonequilibrium free-energy simulations employing three popular assisted model building with energy refinement(AMBER)force fields for nucleotides to investigate this mutation-dependent behavior in the base flipping from T(DNA)residue to the T-to-TFT mutation(TNA)computationally.The force fields were performed similarly,as described in the base-paired state.However,after exploring the high-energy regions with free-energy simulations,we observed that these three force fields behaved differently.Previous reports conclude that the net-neutral and excess-salt simulations provided similar results.Nonetheless,our free-energy simulation indicated that the presence of excess salt affected the thermodynamic stability.The free-energy barrier along the base-flipping pathway was generally elevated upon the addition of excess salts,but the relative height of the free-energy barriers in DNA and TNA duplexes did not change significantly.This phenomenon emphasizes the importance of adding sufficient salts in the simulation scheme to reproduce the experimental condition.

Theoretical Study on Effects of Salt and Temperature on Denaturation Transition of Double-stranded DNA

We investigate the statistical mechanics properties of a nonlinear dynamics model of the denaturation of the DNA double-helix and study the effects of salt concentration and temperature on denaturation transition of DNA. The specific heat, entropy, and denaturation temperature of the system versus salt concentration are obtained. These results show that the denaturation of DNA not only depends on the temperature but also is influenced by the salt concentration in the solution of DNA, which are in agreement with experimental measurement.

Influence of particle size and salinity on adsorption of basic dyes by agricultural waste: dried Seagrape (Caulerpa lentillifera)

Green macroalga Caulerpa lentillifera was found to have reasonable adsorption capacity for basic dyes, Astrazon Blue FGRL （AB）, Astrazon Red GTLN （AR）, and Astrazon Golden Yellow GL-E （AY）. The initial dye concentration was in the range of 100-1,800 mg/L. The dried algal sorbent was ground and sieved into 3 sizes： S （0.1-0.84 mm）, M （0.84-2.0 mm）, and L sizes （larger than 2.0 mm）. For all conditions examined in this work （at 25℃ in batch systems）, the adsorption reached equilibrium within the first hour. The kinetic data corresponded well with the pseudo second order kinetic model where the rate constant, k2, decreased as the sorbent size increased for all dyes. The adsorption isotherms followed both Langmuir and Freundlich models. Among three sorbent sizes, S size gave the highest adsorption capacity followed by M and L sizes. A reduction of sorbent size increased the specific surface area for mass transfer, and also increased the total pore volume, thus providing more active sites for adsorption. The adsorption of AB was adversely influenced by the protonation of algal surface at low pH. On the other hand, the adsorption of AR and AY could be due to weak electrostatic interaction, which was not significantly affected by pH. Increasing salinity of the system caused a decrease in adsorption capacity possibly due to the competition between Na^＋ and the dye cations for the binding sites on algal surface. Moreover, an increase in salinity generated a compressed electrical double layer on the algal surface which exerted repulsive force, retarding the adsorption of positive charged molecules such as the basic dyes.

Combined Effects of Water Quality and Furrow Gradient on Runoff and Soil Erosion in North China

Irrigation-induced soil erosion seriously affects the sustainability of irrigated agriculture. The effects of irrigation water quality and furrow gradient on runoff and soil loss were studied under simulated furrow irrigation in laboratory using a soil collected from an experimental station of China Agricultural University, North China. The experimental treatments were different combinations of irrigation water salt concentrations of 5, 10, 20, and 30 mmol c L-1 , sodium adsorption ratios (SAR) of 0.5, 5.0, and 10.0 (mmol c L-1 ) 0.5 , and furrow gradients of 1%, 3%, and 5%, with distilled water for irrigation at 3 furrow gradients as controls. The experimental data indicated that total runoff amount, sediment concentration in runoff, and total soil loss amount generally decreased with increasing salt concentration in irrigation water but increased with its sodicity and furrow gradient. The effects of water quality and furrow gradient on soil loss were greater than those on runoff, and the increase of furrow gradient decreased the influence of water quality on soil loss. When the salt concentration increased from 5 to 30 mmol c L-1 at SAR of 10.0 (mmol c L-1 ) 0.5 , total runoff amount, sediment concentration, and total soil loss amount decreased by 3.89%, 52.1%, and 53.92%, and 10.57%, 38.86%, and 42.03% at the furrow gradients of 1% and 5%, respectively. However, they respectively increased by 3.37%, 45.34%, and 55.36%, and 3.86%, 10.77%, and 13.91% when SAR increased from 0.5 to 10.0 (mmol c L-1 ) 0.5 at the salt concentration of 5 mmol c L-1 . Irrigation water quality and furrow gradient should be comprehensively considered in the planning and management of furrow irrigation practices to decrease soil loss and improve water utilization efficiency.

Research on the Critical Conditions for Clay Particle Release During Saline Aquifer Freshening Process

Water sensitivity phenomenon occurs during saline aquifer freshening process in seawater intrusion area, and clay particles released in the phenomenon can damage the infiltration capacity of the aquifer. In order to find out the factors and mechanisms for clay particle release, laboratory column infiltration experiments simulating saline aquifer freshening process were designed to measure the critical conditions(critical flow velocity, critical salt concentration and critical ionic strength) and force analysis for clay particle according to DLVO electric double layer theory was employed to illustrate the mechanisms for particle release. The research results showed that critical flow velocity for clay particle release is influenced by salt concentration of injecting solution. When salt concentration of injecting solution is very high, clay particles are not released, indicating that there does not exist a critical flow velocity in this situation. As salt concentration of injecting solution decreases, particles start to be released. The critical salt concentration for clay particle release is 0.052 mol L-1 in our work, which was determined by a constant-flux experiment for stepwise displacement of high concentration Na Cl solution. The critical ionic strength for clay particle release decreases as Ca2+ molar content percentage of the mixed solution of Na Cl and Ca Cl2 increases following the first-order exponential decay equation y = 0.0391e-0.266 x + 0.0015.

Surface nanobubbles on the hydrophobic surface and their implication to flotation

Nanobubbles play a potential role in the application of the flotation of fine particles.In this work,the identification of nanoentities was performed with a contact mode atomic force microscope(AFM).Moreover,the influences of setpoint ratio and amplitude of the cantilever and the responses of the formed surface nanobubbles to the fluctuation of pH,salt concentration,and surfactant concentration in the slurry were respectively studied.Nanobubbles were reported on the highly oriented pyrolytic graphite(HOPG)surface as the HOPG was immersed in de-ionized water under ambient temperature.The coalescence of nanobubbles occurred under contact mode,which provides strong evidence of the gaseous nature of these nanostructures on HOPG.The measuring height of the surface nanobubbles decreased with the setpoint ratio.The changes in the pH and concentration of methyl isobutyl carbinol(MIBC)show a negligible influence on the lateral size and height of the preex-isting surface nanobubbles.The addition of LiCl results in a negligible change of the lateral size;however,an obvious change is noticed in the height of surface nanobubbles.The results are expected to provide a valuable reference in understanding the properties of surface nanobubbles and in the design of nanobubble-assisted flotation processes.

Investigation of salinity impacts on germination and growth of two forest tree species at seedling stage

Soil salinity is becoming an increasingly serious constraint to plant growth in many parts of the world; this is particularly common in semi-arid and arid zones. This study was conducted to evaluate the effect of different concentrations of salt on seed germination and seedling growth of Acacia albida and A. salicina. Collected seeds were treated with H2SO4 98% for 35 min then left to germinate in a controlled growth chamber. Seeds were grown at salinity levels of 0.1, 0.2 and 0.3 mol.L1 of NaH2PO4.H20. Germination parameters and seedling growth indices were measured after 35 days. The mean of total length ofA. salicina in all salinity concentrations was more than that of ：4. albida. The fresh weight of stem and root of ：4, albida was more than that of ：4. salicina. Growth of control seedlings was higher than for other treatments and the fresh weight of stems of two species at salt concentrations of 0.2 and 0,3 mol.Ll decreased with increasing concentration of salt. Most Control seeds germinated at salinity of 0.1 mol.Ll and germination index, final germination and seeds stamina was greater at low levels of salinity.

Effect of salt reduction on nutritional,functional and sensory aspects of Anhui‑style doubanjiang,a traditional Chinese broad bean paste

This study aimed to reveal the effect of salt reduction on the nutritional,functional and sensory aspects of doubanjiang through preparing three sets of doubanjiang fermentation(Sample H,Sample M and Sample L)with different salt concentrations.The results showed that fermentation with lower salt concentration led to significantly higher amino acids concentrations in doubanjiang,while the organic acids concentrations were also slightly increased.For biologically active compounds,the concentrations of total flavonoids,total phenols and five monomer isoflavones in Sample L were all significantly higher than those in Sample M and Sample H.Moreover,better anti-oxidant ability was observed in doubanjiang samples fermented with lower salt concentration.Bacillus and Millerozyma genus were found to be closely related to the formation of amino acids and biologically active compounds in doubanjiang,while organic acids were highly correlated with Cronobacter,Erwinia,Trabulsiella,Enterobacter and Millerozyma genus.Through sensory evaluation and electric tongue,unsatisfactory sensory characteristics,such as lighter color,strong acid taste and off-flavor,were found in lower salt fermented doubanjiang samples.This indicated that lower salt concentration favored the nutrition and function of doubanjiang while negatively influenced doubanjiang flavor.This study deepened our understanding of the roles of salt concentration on doubanjiang fermentation and provided guidance for the further development of low-salt doubanjiang.

Brownian Dynamics Simulations of Rigid Polyelectrolyte Chains Grafting to Spherical Colloid

Brownian dynamics simulations are employed to explore the effects of chain stiffness and trivalent salt concentration on the conformational behavior of spherical polyelectrolyte brush. The rigid brush adopts bundle-like morphology at a wide range of trivalent salt concentration. The number variation of bundles pinned on the colloid surface shows a non-monotonic profile as a function of the chain stiffness. The radial distributions of monomers and ions and the charge ratio between condensed ions and monomers are calculated. The charge inversion is observed for the high salt concentration regardless of chain rigidity. Furthermore, the pair correlation functions of monomer-monomer and monomer-salt cation are used to elucidate the aggregated mechanism of the bundle-like structure.

Fabrication and performance of PET mesh enhanced cellulose acetate membranes for forward osmosis

Polyethylene terephthalate mesh（PET） enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis（FO） mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2 μm. The performance of the optimal FO membrane was tested using 0.2 mol/L Na Cl as the feed solution and 1.5 mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47 L/（m2·hr） and salt rejection of95.48% in FO mode. While in pressure retarded osmosis（PRO） mode, the water flux was4.74 L/（m2·hr） and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes.

Apropos:critical analysis of molluscicide application in schistosomiasis control programs in Brazil

Schistosomiasis is a snail-transmitted infectious disease affecting over 200 million people worldwide.Snail control has been recognized as an effective approach to interrupt the transmission of schistosomiasis,since the geographic distribution of this neglected tropical disease is determined by the presence of the intermediate host snails.In a recent Scoping Review published in Infectious Diseases of Poverty,Coelho and Caldeira performed a critical review of using molluscicides in the national schistosomiasis control programs in Brazil.They also described some chemical and plant-derived molluscicides used in China.In addition to the molluscicides described by Coelho and Caldeira,a large number of chemicals,plant extracts and microorganisms have been screened and tested for molluscicidal actions against Oncomelania hupensis,the intermediate host of Schistosoma japonicum in China.Here,we presented the currently commercial molluscicides available in China,including 26%suspension concentrate of metaldehyde and niclosamide(MNSC),25%suspension concentrate of niclosamide ethanolamine salt(SCNE),50%niclosamide ethanolamine salt wettable powder(WPN),4%niclosamide ethanolamine salt dustable powder(NESP),5%niclosamide ethanolamine salt granule(NESG)and the plant-derived molluscicide“Luowei”.These molluscicides have been proved to be active against O.hupensis in both laboratory and endemic fields,playing an important role in the national schistosomiasis control program of China.Currently,China is transferring its successful experiences on schistosomiasis control to African countries.The introduction of Chinese commercial molluscicides to Africa,with adaptation to local conditions,may facilitate the progress towards the elimination of schisosomiasis in Africa.