1M NaCl Research Articles

Novel cellulose ester substrates for high performance flat-sheet thin-film composite (TFC) forward osmosis (FO) membranes

A novel hydrophilic cellulose ester with a high intrinsic water permeability and a water partition coefficient was discovered to construct membrane supports for flat-sheet thin film composite (TFC) forward osmosis (FO) membranes for water reuse and seawater desalination with high performance. The performance of TFC-FO membranes prepared from the hydrophilic cellulose ester containing a high degree of OH and a moderate degree of Pr substitutions clearly surpasses those prepared from cellulose esters and other polymers with moderate hydrophilicity. Post-treatments of TFC-FO membranes using sodium dodecyl sulfate (SDS) and glycerol followed by heat treatment further enhance the water flux without compromising the selectivity. Positron annihilation lifetime analyses have confirmed that the SDS/glycerol post-treatment increases the free volume size and fractional free volume of the polyamide selective layer. The newly developed post-treated TFC-FO membranes exhibit a remarkably high water flux up to 90 LMH when the selective layer is oriented towards the draw solution (i.e., PRO mode) using 1M NaCl as the draw solution and DI water as the feed. For seawater desalination, the membranes display a high water flux up to 35 LMH using a 2M NaCl draw solution. These water fluxes exceeded the water fluxes achieved by other types of FO membranes reported in literatures.

Characterization of a novel alkali-stable and salt-tolerant α-amylase from marine bacterium Zunongwangia profunda

A novel gene (amyZ2) encoding an alkali-stable and salt-tolerant α-amylase from marine bacterium Zunongwangia profunda (MCCC 1A01486) was cloned and expressed in Escherichia coli. The gene (1446bp) encodes a polypeptide with a predicted N-terminal signal peptide consisting of 24 amino acids and a mature α-amylase of 457 amino acids (AmyZ2). The estimated molecular mass of AmyZ2 was 50kDa by SDS-PAGE. AmyZ2 belongs to glycoside hydrolase family 13 and shares the highest identity (45%) with the characterized α-amylase from Pyrocoocus woesei (PDB id: 1MWO). The purified enzyme showed the maximum activity at 50°C, pH 7.0, and retained approximately 143 and 126% initial activity after 5 days of incubation (25°C) at pH 10.0 and 11.0, respectively, indicating its alkali stability. In addition, it had a salinity-tolerance range of 0–5M NaCl with a salt optimum at 2M (138% initial activity), retaining more than 130% initial activity at 0.5–2.5M and about 100% activity at 3.5M NaCl. AmyZ2 was relatively stable in 0–4M NaCl and its thermostability was significantly improved by the pre-incubation of enzyme solution with 2M NaCl at 50°C for 3h, which led to a 53.6-fold increase in the residual activity. The Km and kcat values of AmyZ2 were 11.71mgml−1 and 1449.43s−1, and the catalytic efficiency (kcat/Km) was 123.78mlmg−1s−1. AmyZ2 exhibited a specific activity of 1662.4U/mg toward soluble starch. The salt-tolerance and extreme alkali-stability of AmyZ2 suggests its potential applications in harsh industrial processes.

Carbon dots functionalized by organosilane with double-sided anchoring for nanomolar Hg2+ detection

Surface functional groups on carbon dots (CDs) play a critical role in defining their photoluminescence properties and functionalities. A new kind of organosilane-functionalized CDs (OS-CDs) were formed by a low temperature (150°C) solvothermal synthesis of citric acid in N-(β-aminoethyl)-γ-aminopropylmethyl-dimethoxysilane (AEAPMS). Uniquely, the as-synthesized OS-CDs have dual long chain functional groups with both NH2 and Si(OCH3)3 as terminal moieties. Double sided anchoring of AEAPMS on CDs occurs, facilitated by the water produced (and confined at the interface between CDs and solvent) when citric acid condenses into the carbon core. The resultant OS-CDs are multi-solvent dispersible, and more significantly, they exhibit excellent selectivity and sensitivity to Hg2+ with a linear detection range of 0–50nM and detection limit of 1.35nM. The sensitivity and selectivity to Hg2+ is preserved in highly complex fluids with a detection limit of 1.7nM in spiked 1M NaCl solution and a detection limit of 50nM in municipal wastewater effluent. The results show that the OS-CDs synthesised by the solvothermal method in AEAPMS may be used as an effective Hg2+ sensor in practical situations.

A coarse-grained model with implicit salt for RNAs: predicting 3D structure, stability and salt effect.

To bridge the gap between the sequences and 3-dimensional (3D) structures of RNAs, some computational models have been proposed for predicting RNA 3D structures. However, the existed models seldom consider the conditions departing from the room/body temperature and high salt (1M NaCl), and thus generally hardly predict the thermodynamics and salt effect. In this study, we propose a coarse-grained model with implicit salt for RNAs to predict 3D structures, stability, and salt effect. Combined with Monte Carlo simulated annealing algorithm and a coarse-grained force field, the model folds 46 tested RNAs (≤45 nt) including pseudoknots into their native-like structures from their sequences, with an overall mean RMSD of 3.5 Å and an overall minimum RMSD of 1.9 Å from the experimental structures. For 30 RNA hairpins, the present model also gives the reliable predictions for the stability and salt effect with the mean deviation ∼ 1.0 °C of melting temperatures, as compared with the extensive experimental data. In addition, the model could provide the ensemble of possible 3D structures for a short RNA at a given temperature/salt condition.

Abstract 034: Transient Receptor Potential Vanilloid-1 (TRPV1) Channels Mediate the Sympathoexcitatory and Pressor Responses to Central NaCl Stimulation

Accumulating evidence indicates a high salt diet increases cerebrospinal fluid sodium concentration to elevate sympathetic nerve activity (SNA) and arterial blood pressure (ABP) in salt-sensitive hypertension. Recent evidence suggests TRPV1 channels underlie the ability of the brain to sense changes in osmotic pressure. The present study investigated whether the sympathoexcitatory response to intracerebroventricular (ICV) infusion of hypertonic NaCl was mediated by central TRPV1 channels. In Inactin-anesthetized Sprague-Dawley rats, ICV infusion of 1M NaCl (n=8) significantly increased lumbar SNA (140±12%), heart rate (20±7bpm), and mean ABP (9±1mmHg). ICV pretreatment with the broad-spectrum TRPV channel blocker ruthenium red (5mM, 2uL, n=8) eliminated the sympathoexcitatory response to ICV 1M NaCl: lumbar SNA (106±5%), heart rate (-6±7bpm), and mean ABP (1±2mmHg). Similarly, ICV pretreatment with the selective TRPV1 channel antagonist SB366791 (3mM, 2uL, n=8) prevented any change in lumbar SNA (106±3%), heart rate (4±6), and mean ABP (1±1mmHg). ICV injection of ruthenium red or SB366791 alone did not alter any variable. Surprisingly, ICV infusion of 1M NaCl (1μL) produced similar pressor responses in wild-type versus TRPV1-/- mice (12±2 vs 11±2 mmHg, n>4). Pretreatment with SB366791 attenuated the pressor response in wild-type but not TRPV1-/- mice. In vitro patch clamp recordings of neurons in the ventral lamina terminalis reveal that increases in bath osmolality produced dose-dependent membrane depolarization (5 mOsm: 5.0±0.63 mV, 10 mOsm: 6.1±1.24 mV, 15 mOsm: 12.4±2.1; n=5, P<0.05) and increase discharge frequency (5 mOsm: 208±32%, 10 mOsm: 246±55%, 15 mOsm: 274±101%, 20 mOsm: 496±53%; n=5, P<0.05). These responses were attenuated by bath application of the broad spectrum TRPV blocker ruthenium red. Collectively, these observations suggest that central TRPV channels mediate changes in neuronal excitability and cardiovascular responses to central osmotic stimulation.

Thermodynamics of a Ca2+-dependent highly thermostable alkaline protease from a haloalkliphilic actinomycete

An alkaline protease from salt-tolerant alkaliphilic actinomycetes, Nocardiopsis alba OK-5 was purified by a single-step hydrophobic interaction chromatography and characterized. The purified protease with an estimated molecular mass of 20kDa was optimally active at 70°C in 0–3M NaCl and 0–100mM Ca2+ displaying significant stability at 50–80°C. The enzyme was stable at 80°C in 100mM Ca2+ with Kd of 17×10−3 and t1/2 of 32min. The activation energy (Ea), enthalpy (ΔH*), and entropy (ΔS*) for the protease deactivation calculated in the presence of 200mM Ca2+ were 38.15kJ/mol, 35.49kJ/mol and 183.48J/mol, respectively. The change in free energy (ΔG*) for protease deactivation at 60°C in 200mM Ca2+ was 95.88kJ/mol. Decrease in ΔH* reflected reduced cooperativity of deactivation and unfolding. The enzyme was intrinsically stable that counteracted heat denaturation by a weak cooperativity during the unfolding. Further, the enzyme was highly stable in the presence of various cations, surfactants, H2O2, β-mercaptoethanol, and commercial detergents. The compatibility of the enzyme with various cations, surfactants, and detergent matrices suggests its suitability as an additive in the detergents and peptide synthesis.

Characterization of Fe-smectites and their alteration potential in relation to engineered barriers for HLW repositories: The Nui Nua clay, Thanh Hoa Province, Vietnam

The stability of smectite-rich clay minerals is of interest because they could be candidates for engineered barriers for high-level radioactive waste repositories. This research characterized the chemical and mineralogical properties of the Nui Nua clay which forms from the weathering of the Nui Nua serpentinized ultramafic–mafic massif (Thanh Hoa Province, Viet Nam) using several methods (including Fourier transform infrared spectrometry and transmission electron microscopy). The Nui Nua clay, taken from Co Dinh and My Cai valleys, is composed of Fe-smectites as the main phase with minor phases of normal smectite, quartz, talc, chlorite, kaolinite, amphibole, antigorite, feldspars and magnetite. The Fe-smectites were characterized as mixed-layer minerals (including Fe-montmorillonitic as an end-member) composed of illitic or dioctahedral vermiculitic layers and Fe-rich smectitic layers. The proportion of the smectitic layer is approximately 80%; the interlayer sheet is dominated by Ca and Mg, while the octahedral sheet is dominated by Fe3+ (not Al). The stability of the Nui Nua smectites was also investigated by a simulation in saturation of 1M NaCl and deionized water under kinetic impaction. The average tetrahedral-Si content of the smectites increased or decreased depending on the “dynamic solution” or hydraulic regime. By chemical identification, the alteration of Fe-smectites is mainly increased by the smectitization process. This research suggests that the Nui Nua clay is a potential candidate for an engineered barrier because during the alteration process, neo-formation of a montmorillonitic layer occurs.

Micropatterning of Transparent, Flexible Graphene Films By Oxygen Plasma

Graphene, a single-atom-thick and two-dimensional sp2 carbon networking materials, has attracted a great deal of interest owing to its remarkable electrical, mechanical, and thermal properties. These excellent properties make it more suitable for use in transparent and flexible electrodes. The successful implementation of graphene films for various applications requires high quality and high resolution patterning at defined positions, with large-scale control of location and orientation. The plasma etching technique is one of the patterning techniques, which has been used widely for the surface activation of various materials, as well as for removal of carbon-based organic material from substrate surfaces [1]. This method has several advantages over other patterning techniques: (1) it can be scaled-up to produce large quantities for commercial use; (2) it results in high feature resolutions and sharp pattern edges; (3) the processing time is short; and (4) it offers good reproducibility and reliability. Herein, we report a simple patterning method for the production of graphene films on flexible, transparent plastic substrates such as poly(ethylene terephthalate) PET using an O2-plasma technique in a CCP system [2]. For the preparation of graphene, graphene oxide suspension was reduced at 85°C for 24h by employing L-ascorbic acid as a reducing agent. L-ascorbic acid is non-toxic, so this method is eco-friendly compared to other reducing agents [3]. To apply the homogeneous graphene films in a large area, flexible and transparent graphene films were fabricated by vacuum filtration method and then patterned by conventional photolithography and subsequent O2-plasma treatment. Figure 1 (a) The effect of O2-plasma treatment on the resistivity and transparency of graphene films. Graphene films were treated with O2-plasma under a power ranging from 200 to 500 W between 1 and 5 min. (b) The changes of resistivity and transparency according to plasma treatment time at a power of 200 W. Figure 1 shows the effect of O2-plasma treatment on the resistivity and transparency of graphene films. The resistivity increased as the plasma power increased. When graphene films were treated at 100 W for 5 min and at 200 W over 3 min, it was impossible to measure resistivity as it was above the measurement range of the instrument (~100 MΩ). In addition, the transparency of graphene films increased as the power increased. As the results, an applied power of 200 W for 5 min was optimal for the patterning of graphene films. Figure 2Optimal images of the patterned graphene films under 200 W for 5 min. The scale bar represent 1 mm. The optical microscope images of the patterned graphene films on the PET flexible substrate are shown in Figure 2. The area patterned by O2-plasma treatment is more transparent than the area protected with the photoresist polymer. The clear patterns demonstrated the effectiveness of graphene patterning by this method. For a more detailed characterization, the morphological change of graphene films was investigated by scanning electronmicroscope (SEM) and atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used for the investingation of chemical property changes of graphene films. An electrochemiluminescence (ECL) reaction was carried out the patterned graphene films to confirm that it could function as a transparent electrode. For the ECL reaction, three electrode configuration was employed, consisting of the patterned graphene film serving as a working electrode, Ag/AgCl (3M NaCl) (a reference electrode), and platinum wire (a counter electrode). Red light is emitted on the graphene electrode surface without leakage, as shown in the line-scan of the chemiluminescent signal in Figure 3. This experiment indicates that the O2-plasma treatment can be successfully applied to pattern a graphene transparent electrode. We expect that this simple and versatile patterning technique will facilitate the fabrication of graphene film-based electronic of optoelectronic devices. Figure 3 (a) Luminescence image of the patterned graphene electrodes after the ECL reaction. The scale represents 300µm. (b) ECL line scan at the location indicated by the white line. References Tingting Feng et al., Materials Letters, 72 (2012) 187-189Kwi Nam Han et al., Langmuir, 26 (2009) 598-602Juali Zhang et al., ChemComm, 46 (2010) 1112-1114

Investigating the Role of Electrolyte Composition and Oxide Structure in Galvanic Corrosion Susceptibility Under Atmospheric Electrolytes

The goal of this study is to develop a better mechanistic understanding of how electrolyte composition and surface oxides can influence corrosion kinetics in the electrolytes formed from atmospheric processes. It has been observed that galvanic couples between aluminum alloys and titanium or stainless steel fasteners exposed to electrolytes formed from atmospheric processes lead to very different corrosion rates (Z. Feng, G. Frankel, Corrosion, 70(2014) pgs 95-106). In order to collect the data necessary to accomplish this goal, sixteen 2”x2” panels of AA2024, AA7075, CRES 13-8, CRES 17-4, Ti-6Al-4V, and Custom 465 were cut from panel or bar stock and polished to 600 grit SiC. The samples were then mounted in 300 mL Gamry Paracells and exposed for 18 hours to the following electrolytes: 0.6M NaCl at ambient aeration, 6M NaCl at ambient aeration, deoxygenated 0.6M NaCl saturated with nitrogen,0.6M NaCl + 0.01M HCl, 0.6M NaCl + 0.01M H2SO4, and 0.6M NaCl + 0.005M HNO3 + 0.005M H2SO4. The aluminum alloys were then anodically polarized at 0.167 mV/sec from -0.02V below EOC to + 1.5VSCE. The other alloys were polarized cathodically at 0.167 mV/sec from +0.02V above EOC to -1.4VSCE. Results for the cathodic polarization scans of the CRES 13-8PH stainless steel and the Ti-6Al-4V titanium alloy are shown in Figure 1. The differences in cathodic current capacity for materials exposed to the same electrolyte at the same aeration level reinforces the fact that oxide microstructure plays a significant role in catalyzing reduction reactions, though the kinetics of the reaction rates may not be predicted from a simple galvanic series. Of more interest are the changes in reaction rates from acidification of the electrolyte. This suggests that the electrolyte is changing the the oxide microstructure or that new reduction reactions are supported. This is significant because overlays of the anodic polarizations of the aluminum alloys indicate that material loss rates can be orders of magnitude higher for acidified atmospheric electrolytes. These effects are being investigated using microelectrode experiments on droplets of the various electrolytes along with supporting experiments using Scanning Kelvin Probe techniques. Acknowledgements The authors gratefully acknowledge the financial support of the Office of Naval Research Figure 1: Cathodic polarization curves for the titanium alloy Ti-6Al-4V and the stainless steel CRES 13-8PH in 0.6M NaCl and 0.6M NaCl + 0.005M H2SO4 + 0.005M HNO3, showing that materials with different surface oxides and in near-neutral to low-pH electrolytes can support very different cathodic reaction rates with potentially very deleterious consequences for galvanic couples with more active materials.

Influence of an Artificial Ageing on the Corrosion Behavior of AA2024

The aluminum alloys of the 2xxx series, such as the 2024 alloy, are widely used in the aircraft industry for the skin and wings of the aircrafts. However, the 2024 alloy can be affected by localized corrosion such as pitting corrosion, intergranular corrosion, exfoliation and stress corrosion cracking in chloride-containing environments (1-2). Most of the works performed concerning the corrosion behavior of the 2024 alloy correspond to continuous immersion tests. However, in service-life, airplane structures can be subjected to complex thermal and environmental cycling with exposure to an aqueous environment at room temperature, e.g. on the tarmac, followed by exposure to very low temperatures without aqueous environment, e.g. during the flight. In a previous work, the influence of cyclic exposure to chloride solutions on corrosion damage morphology developed on the 2024 alloy was studied (3). The results showed significant differences in corrosion morphology between continuous immersion tests and cyclic corrosion tests with cyclic corrosion tests leading to enhanced corrosion damage compared to continuous immersion tests. Furthermore, in service-life, airplane structures can be exposed to heat fluxes depending on their location on the airplane; this might lead to microstructural ageing of the material and consequently to an evolution of its corrosion behavior. The present work focuses on the influence of ageing on the corrosion behavior of the 2024 alloy.The corrosion behavior of the 2024 aluminum alloy was studied in a 1M NaCl for samples in the as received T351 metallurgical state and also for samples aged at 150°C for duration time between 0 h and 177 h. Open circuit potential measurements (OCP) showed a strong effect of the ageing treatment on the corrosion behavior of the 2024 alloy with OCP values decreasing when the ageing time increased. An ageing time of 55h was identified as a critical value on the OCP vs ageing time curve. This critical ageing time was also identified on the curves showing the mechanical properties (elongation to rupture, maximal strength) vs ageing time and correlated to a significant evolution of the microstructure by transmission electron microscopy. All the samples, i.e. T351 and aged samples, were submitted to both continuous immersion tests (CI tests) and cyclic corrosion tests (CF tests). A CF test consisted of three cycles of 24 hrs; each cycle was composed of an 8-hr immersion in the electrolyte followed by a 16 hrs air exposure period at -20°C. CI tests, called CI 24 h and CI 72 h, for duration of 24 h and 72 h respectively, were carried out as reference tests. Observations of the samples after the corrosion tests showed that, after CI tests, there was a transition of the corrosion morphology from intergranular to quite transgranular when the ageing time increased: for ageing time longer than 55h, transgranular corrosion was predominant. For all the samples, the corrosion defects morphology was strongly affected by the exposure conditions with CF tests promoting the intergranular corrosion and the branching of the intergranular corrosion defects.1. C. Augustin, E. Andrieu, C. Blanc, G. Mankowski, and J. Delfosse, J. Electrochem.Soc., 154, C637 (2007).2. W. Zhang and G. S. Frankel, J. Electrochem. Soc., 149, B510 (2002).3. C. Larignon, J. Alexis, E. Andrieu, C. Blanc, G. Odemer and J.-C. Salabura. J. Electrochem. Soc., 158, 1 (2011).

Comparative study of stress corrosion cracking susceptibility of Fe18Cr10Mn- and Fe18Cr10Mn1Ni-based high nitrogen stainless steels

The stress corrosion cracking (SCC) behavior of Fe18Cr10Mn1Ni(0.3–0.8)N alloys was investigated in aqueous NaCl environment by using slow strain rate test method, and the results were compared to those of Ni-free counterparts. The addition of N tended to improve the SCC resistance of Fe18Cr10Mn- and Fe18Cr10Mn1Ni-based alloys. The alloying Ni magnified the beneficial effect of N on the SCC susceptibility and, eventually, the Fe18Cr10Mn0.8N alloy was immune to SCC in 2M NaCl solution at 50°C. The SCC behavior of the present alloys was found to be closely related to the repassivation tendency and the resistance to pitting corrosion.

Identification and characterization of a new acid-stable endoglucanase from a metagenomic library

A new endoglucanase gene cel124 was cloned from a metagenomic library and expressed in Escherichia coli. Catalytic triad analysis showed that the catalytic triad sites were different from the known endoglucanases. Cel124, a 34kDa protein, exhibited a specific activity (29.08Umg−1) toward 1% of sodium carboxymethyl cellulose and was stable at 50°C for 30min. The optimal temperature and pH for its catalytic activity were 50°C and pH 5.5 respectively. Cel124 could hydrolyze soluble cellulose, but not insoluble cellulose or other polysaccharides. The kinetic parameters (5.63mgml−1 for Km and 0.0397mmolmin−1mg−1 for Vmax) were measured. 3M NaCl in the system could increase its activity by 2 fold. Site-directed mutation and circular dichroism spectra test suggested that the residue (Glu41) was essential for its activity, might be a potential active site. Based on our data, we proposed that Cel124 might represent a new type of endoglucanase.

Subcellular distribution and chemical forms of cadmium in the edible seaweed, Porphyra yezoensis

The subcellular distribution and chemical forms of Cd were investigated in the edible seaweed, Porphyra yezoensis. The seaweed was exposed to different Cd concentrations (0.01, 0.05, 0.1, 0.5, 1.0 and 5.0mgl−1) for up to 96h. In both the controls (no Cd added) and treatment groups, 41.2–79.2% of Cd was localised in the cell wall, and the proportion of Cd in the cell wall increased with increasing concentrations of Cd and exposure time. In the control groups, 74.8% of Cd was extracted by 1M NaCl, followed by 2% acetic acid, HAC (18.9%). In the treatment groups, most Cd was extracted by 2% HAC. The proportion of Cd extracted by 2% HAC increased with exposure to increasing concentrations of Cd and over time. Cell wall deposition and forming of precipitates with phosphate may be a key strategy to reduce Cd toxicity in P. yezoensis.

Pressure retarded osmosis dual-layer hollow fiber membranes developed by co-casting method and ammonium persulfate (APS) treatment

Delamination and low water permeability are two issues limiting the applications of dual-layer hollow fiber membranes in the pressure retarded osmosis (PRO) process. In this work, we first developed a universal co-casting method that is able to co-cast highly viscous dope solutions to form homogeneous dual-layer flat sheet membranes. By employing this method prior to the tedious dual-layer hollow fiber spinning process, both time and material consumptions are significantly saved. The addition of polyvinylpyrrolidone (PVP) is found to eliminate delamination at the sacrifice of water flux. A new post-treatment method that involves flowing ammonium persulfate (APS) solution and DI water counter-currently is potentially to remove the PVP molecules entrapped in the substrate while keeps the integrity of the interface. As the APS concentration increases, the water flux in the PRO process is increased while the salt leakage is slightly decreased. With the optimized APS concentration of 5wt%, the post-treated membrane shows a maximum power density of 5.10W/m2 at a hydraulic pressure of 15.0bar when 1M NaCl and 10mM NaCl were used as the draw and feed solutions, respectively. To the extent of our knowledge, this is the best phase inversion dual-layer hollow fiber membrane with an outer selective layer for osmotic power generation.

Direct current electrodeposition of Zn and Zn–SiC nanocomposite coatings

Pure Zn and Zn matrix composite coatings containing nano-sized SiC particles with an average size of 50 nm were prepared from the zinc sulphate bath. The effect of the particle concentration and current density on the amount of particles embedded was examined. Electron microscopic studies revealed that the coating morphology was modified by the presence of SiC nanoparticles. Corrosion resistance properties of the coatings were studied using a potentiodynamic polarisation technique in 1M NaCl solution. It was established that agglomeration of nanoparticles worsens corrosion resistance properties of Zn–SiC coatings. However, the presence of well dispersed nanoparticles significantly improves the corrosion resistance of the zinc. Incorporation of SiC nanoparticles also improves the microhardness of the zinc matrix.

Application of Two Different Methods for Determination of Water and Chloride Transport Parameters of Building Stones

The transport of 1M NaCl water solution in three different types of sandstones is studied For basic characterization of studied materials, their chemical composition, porosity, bulk density and matrix density are accessed. The chloride transport is analyzed using two different methods. In the first one, the chloride absorption coefficient is measured on the basis of a modified sorptivity concept. The second method consists in carrying out an inverse analysis of experimentally measured moisture and chloride concentration profiles, leading to the determination of chloride diffusion coefficient as a function of chloride concentration, and moisture diffusivity as a function of moisture content. The chloride transport properties obtained for the particular studied materials are compared and the observed differences are discussed.

Quantitative analysis of histamine- and agmatine–DNA interactions using surface plasmon resonance

To exploit the binding affinity for efficient plasmid purification, agmatine and histamine were immobilized on carboxymethylated dextran surface. Their binding strength is evaluated with oligonucleotides and pUC19 (2.69kbp), pVAX1-LacZ (6.05kbp) and pcDNA3-myc-FLNa S2152A (14kbp) isoforms by measuring the KD using SPR-biosensor. The oligonucleotides and plasmid isoforms bind more strongly to histamine than to agmatine. Concerning the oligonucleotides, the highest affinities are found for poly 30, and polyT and polyG series showed lowest affinity with both ligands. These results are corroborating with the hetero-oligonucleotides since the lowest binding affinity is found for GGGTTT, indicating that thymidine and guanosine together decrease the binding strength. The largest plasmid has the highest binding, while pUC19 shows the weaker binding. The linear isoform exhibit the highest binding affinity to both amino acid-derivatives.Decreasing the pH above 6, the interaction strength of linear isoform increases possibly due to positively charged of the surface, which enhances electrostatic interactions. However, no binding response is detected with high salt concentrations (1M NaCl) and for different buffers. The affinity information accessible with the biosensor offers new insight into nucleic acids–ligand interactions, as well as, new criteria leading the optimization of the novel ligands for preparative plasmid purification.

New insights into the effectiveness of alpha-amylase enzyme presentation on the Bacillus subtilis spore surface by adsorption and covalent immobilization

Most of the studies in the field of enzyme immobilization have sought to develop a simple, efficient and cost-effective immobilization system. In this study, probiotic Bacillus spores were used as a matrix for enzyme immobilization, because of their inherent resistance to extreme temperatures, UV irradiation, solvents and drying. Above all, their preparation is cost-effective. The alpha-amylase enzyme was immobilized on the spore surface by the covalent and adsorption methods. For the covalent method, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N hydroxysulfosuccinimide (NHS) were used. The maximum concentration of the alpha-amylase immobilized by the two methods onto the spore surface was 360μg/1.2×1011 spore. However, maximum activity was achieved at an enzyme concentration of approximately 60μg/.4×1010, corresponding to an estimated activity of 8×103IUmg−1/1.2×1011 spore for covalent immobilization and 8.53×103 for the adsorption method. After washing the enzyme with 1M NaCl and 0.5% Triton X-100, the enzyme immobilization yield was estimated to be 77% and 20.07% for the covalent and adsorption methods, respectively. The alpha-amylase immobilized by both methods, displayed improved activity in the basic pH range. The optimum pH for the free enzyme was 5 while it shifted to 8 for the immobilized enzyme. The optimum temperatures for the free and immobilized enzymes were 60°C and 80°C, respectively. The covalently-immobilized alpha-amylase retained 65% of its initial activity, even after 10 times of recycling. The Km and Vmax values were determined by the GraphPad Prism software, which showed that the Vmax value decreased moderately after immobilization. This is the first study which reports the covalent immobilization of an enzyme on the spore surface.

Development of three-dimensional site-site Smoluchowski-Vlasov equation and application to electrolyte solutions

Site-site Smoluchowski-Vlasov (SSSV) equation enables us to directly calculate van Hove time correlation function, which describes diffusion process in molecular liquids. Recently, the theory had been extended to treat solute-solvent system by Iida and Sato [J. Chem. Phys. 137, 034506 (2012)]. Because the original framework of SSSV equation is based on conventional pair correlation function, time evolution of system is expressed in terms of one-dimensional solvation structure. Here, we propose a new SSSV equation to calculate time evolution of solvation structure in three-dimensional space. The proposed theory was applied to analyze diffusion processes in 1M NaCl aqueous solution and in lithium ion battery electrolyte solution. The results demonstrate that these processes are properly described with the theory, and the computed van Hove functions are in good agreement with those in previous works.

High Performance Metal Surface Coating Using Ta<sub>2</sub>O<sub>5 </sub>Thin Film Prepared by D.C. Magnetron Sputtering

Tantalum oxide (Ta2O5) thin films were deposited as the protective layers for the metal surface finishing by the DC reactive magnetron sputtering system. The effect of the Ta2O5 film thickness, ranging from 25 nm to 200 nm, on the physical properties and the anti-corrosive performance were investigated. The grazing-incidence X-ray diffraction (GIXRD) and the atomic force microscopy (AFM) were used to examine the crystal structures and the surface topologies of the prepared films, respectively. The XRD results showed that the Ta2O5 thin films were all amorphous. The AFM micrographs demonstrated the film morphology with quite smooth surface features. The surface roughness tended to be rough when the film thickness was increased. To examine the protective performance of the films, the poteniostat and galvanometer was utilized to examine the electrochemical activities with the 1M NaCl as the corrosive electrolyte. The results from the I-V polarization curves (Tafel slope) indicated that, with the Ta2O5 thin film, the current density was significantly reduced by 3 orders of magnitude when compared with the blank sample. Such results were observed because of fully encapsulated surface of the samples were covered with the sputtered Ta2O5 thin films. The study also showed that the Ta2O5 thin film deposited at 50 nm yielded the most extreme protective performance. The Ta2O5 thin films therefore could be optimized for the smallest film thickness for highly potential role in the protective performance of the metal surface finishing products.