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High-field 1 H NMR T2 relaxation studies were used to characterize the changes in the physical phases of water, NaCl, and dextrose solutions over a temperature range of -65 to 15°C. The data were analyzed with the inverse Laplace transform and with a linear fit to the logarithm of the time domain signal. Two liquid phases were detected for the NaCl and dextrose solutions at lower temperatures and assigned to low and high concentrated solution domains. The high concentrated solution domain was found to be present between -30 and -5°C in the NaCl solution and between -55 and -5°C in the dextrose solution. Copyright © 2017 John Wiley & Sons, Ltd.

Nuclear Magnetic Resonance (NMR) spectroscopy, can be used for transport studies either directly, by elucidating metabolic pathways, transport into and out of organs and organelles, or indirectly via determination of ATP concentration, intracellular pH, viscosity, flux rates and thermodynamic information. Previously the tool of the chemist, NMR has now found many applications in biology and medicine. This advance has been made possible largely due to technological advances, allowing wider bores and stronger magnetic fields to be achieved. In this chapter I will firstly outline briefly the theory behind NMR so that its advantages and limitations can be appreciated. I will then detail, with examples, the information available from NMR Spectroscopy. This will be followed by discussion of the more biologically useful NMR nuclei. My emphasis throughout will be on in vivo applications and how NMR may be useful for transport studies. This chapter is not a comprehensive review of NMR spectroscopy nor is it written for the expert. I have erred towards being didactic and have not given references to back up every statement made, for which I apologise to all concerned. I hope it shines some light on the technique and that it may even persuade the reader to have a go!

Extraction methods are critical in the production and success of an extra virgin olive oil ready for consumption. The first step of olive oil extraction procedure produces an olive paste, which is subsequently processed by separation of the liquid phases (oil and vegetable water) from the pomace. Profiles of Apulian extra virgin olive oils and the deuterated chloroform extracts of its paste and pomace were studied by 1D and 2D NMR (NMR) spectroscopy without separation and pre‐treatment of samples. In order to study the metabolic profiles variation in the paste and pomace extracts with respect to the corresponding EVOOs, multivariate statistical analyses (PCA and OPLS DA) of the1H NMR data were performed. As expected, a different minor components profile, in particular for the presence of higher content of secoiridoids, lignans and phenolic compounds in olive paste and pomace extracts with respect to the EVOOs, was observed.Practical applications:Amount of extractable oil from olive paste and pomace after the production processes of EVOO was measured by1H NMR spectroscopy. Identification of metabolites in olive paste and pomace was performed by 1D and 2D NMR spectroscopy without separation and pre‐treatment of samples. The chemical composition of major and minor components (in particular secoiridoids, lignans, and phenolic compounds) present in olive paste and pomace chloroform extracts could be used for extraction process trimming purposes as well as in fingerprint analyses for cultivar and/or geographical origin certification of olive oil production. Moreover, determination of the entire metabolic content of different materials of the olive oil production process could be exploited in other applications such as recycling on agricultural land, studies of the health benefits on human nutrition and alternative dietary lipid source in animals. In fact, it is worth noting that the olive paste and pomace extracts could be even healthier than other vegetable oils.The extraction processes are critical in the extra virgin olive oil production. The chemical composition of EVOOs and its paste and pomace extracts have been investigated by Nuclear Magnetic Resonance Spectroscopy (NMR).

A one-step pyrolysis was used to synthesize ginger carbon quantum dots (G-CDs), which were described using XPS, FTIR, XRD, EDX, and TEM to validate the different integrated functions, particle dimension, morphology, component composition, amorphous construction, and bonding types. The dual action of the synthesized G-CDs as corrosion and scale inhibitors was examined. Scale inhibition characteristics of G-CDs for precipitation of BaSO4 were investigated using the conductivity technique. Results indicated that G-CDs have an effective inhibition of 84.9% at 200mg/L. Application of Langmuir and Flory-Huygens isotherms along with the Kinetic-thermodynamic model on the experimental findings demonstrated the suitability and applicability of all of them, yielding a (∆G°ads) precipitation ≃ - 26.7kJ/mole, suggesting that G-CD adsorption on the scale particle surface is cooperative, involving both chemical and physical interactions, with the physical aspect being the dominant mechanism. SEM and XRD studies indicated that the scale particles (BaSO4) were deformed when precipitated in the presence of G-CDs due to their adsorption on the particles' surfaces.On the other hand, the inhibition characteristics for the steel corrosion in NaCl solution (0.5M) were examined using EIS and mass loss method techniques that revealed that G-CDs act as high-efficiency eco-friendly corrosion inhibitor giving 98.3% at 400mg/L. However, the PDP results indicated that the G-CDs act as mixed-type inhibitor. Application of the adsorption isotherms on the experimental corrosion inhibition data revealed that the three models are applicable, giving (∆G°ads) corrosion values equal to - 28.2kJ/mole, which means that the adsorption process of the G-CQDs is cooperative (physical/chemical). XPS, XRD, EDX and TEM analysis of the steel's surface upon submersion in a NaCl solution (0.5M) + 400mg/L G-CDs solution for 1h revealed that the corrosion products completely disappeared, the carbon dots were closely attached to the surface of the steel, and the Cl⁻ ions were displaced from the steel surface, which confirms that the G-CDs function as a superior ecologically friendly inhibitor for mitigating the steel corrosion. A mechanism of the inhibition of corrosion of steel in a NaCl solution (0.5M) by G-CDs was reported, which suggests that in the absence of G-CDs in chloride media, the specific adsorption of the chloride ions on the steel surface and catalyse the charge transfer cathodic and anodic corrosion reactions. However, in the presence of G-CDs in the environment, the strong active absorbable carbon dots surface particles displace the Cl- ions from the steel surface, mitigating the catalytic effect causing inhibition of the corrosion process.

In this work, the effect of Cu addition on the microstructure and corrosion passivation behavior of Sn alloyed ferritic stainless steel in 3.5 wt.% NaCl solution at 30 °C was investigated by optical microscope (OM), scanning electron microscope (SEM), energy-dispersion spectrum (EDS), potentiodynamic polarization curve and x-ray photoelectron spectroscopy (XPS). The results indicate that Cu addition has certain effect on grain refinement of ferritic stainless steel. Meanwhile, Cu addition has little influence on the cathodic corrosion process of ferritic stainless steel in 3.5 wt.% NaCl solution but shows beneficial effect on enhancing both the corrosion resistance of steel substrate and its passivation behavior. It has been found that the deposition of Cu particles at the bottom of corrosion pits is responsible for the better corrosion resistance and passivation behavior of ferritic stainless steel. Moreover, there is synergistic effect between Sn and Cu on enhancing the corrosion resistance of ferric stainless steel matrix and improving its passivation behavior in NaCl solution.

Three-dimensional macroporous carbon materials with hierarchical pore structures (3D MPC) have wide applications, but the scale-up synthesis is limited by the cumbersome procedures of template formation and removal. Herein, we show that NaCl crystallites, which form in situ in a lyophilizing process of a NaCl solution containing a carbon precursor and are removable simply through water washing, can act as templates to grow 3D MPC materials with graphene-like ultrathin and mesoporous walls through pyrolitic carbonization. Further, by use of a nitrogen (N)-rich polymer (polyvinylpyrrolidone, PVP) as the carbon precursor and introduction of Fe salt in the precursor, an MPC catalyst with high Fe/N doping content is achieved due to the NaCl crystallites serving as confining agents to simultaneously prevent the large weight loss and N evaporation, a severe problem in usual pyrolytic syntheses of Fe-N-C catalysts. Benefiting from the mass transport convenience of the macropores as indicated by the impedance spec...

Effect of hydrophobic surface modifying macromolecules on differently produced PVDF membranes for direct contact membrane distillation

Objectives. Biologically active polymeric surfactants are a new promising class of macromolecules that can find application in medicine, cosmetology, and agriculture. In this study, a number of new biologically active amphiphilic polymers based on branched silatrane-containing polyesters and polyethers were obtained, and their surface-active properties were investigated.Methods. The branched polymers were represented by polyethers and polyesters, obtained respectively via the anionic polymerization of 1,2-epoxypropanol or a combination of equilibrium polycondensation and ring opening polymerization. The polymers were modified with 3-isocyanopropylsilatrane and trimethylethoxysilane to obtain the amphiphilic compounds containing silatrane groups bonded to the polymer backbone by the urethane bond. The structure of the synthesized polymer silatranes was confirmed via nuclear magnetic resonance spectroscopy and gel permeation chromatography. The surface active properties of all the copolymers obtained were investigated in connection with their obvious amphiphilicity. In particular, the formation of micelles in aqueous solutions is such a property. The critical micelle concentrations were determined by a method of quenching the fluorescence of the polymers.Results. It was shown that the values of the critical micelle concentrations and the hydrophilic-lipophilic balance values of polymers determined by the Griffin equation correlate well with each other. A linear relationship between the hydrophilic-lipophilic balance and the critical micelle concentrations was established. At the same time, polyether-based polymers generally showed higher critical micelle concentrations than polyester-based polymers, although the hydrophilic-lipophilic balance values for polymers of different series, but with close degrees of substitution, were close. It was found that the use of all synthesized polymers as stabilizers of direct and reverse emulsions leads to an increase in the aggregative stability of both types of emulsions. The stability of emulsions depended both on the degree of substitution of peripheral hydroxyl groups of polymers by silatranes and on the molecular weight and structure of the branched block of polymers. The stability of direct emulsions increased for all polymers, while that of inverse emulsions decreased with an increasing degree of substitution of hydroxyl groups by silatranes. The increase of the branched block molecular weight led to an increase of droplet sizes for both direct and inverse emulsions. The smallest droplet size for direct and inverse emulsions was obtained using polymers with low molecular weight branched polyester blocks as surfactants.Conclusions. The results obtained prove the possibility of creating polymer surfactants containing silatrane groups. By varying the structure of the polymer, its molecular weight and the degree of substitution of peripheral functional groups, it is possible to obtain surfactants with desired surface properties.

An interpenetrating polymer network hydrogel composed of 2‐hydroxypropyltrimethyl ammonium chloride chitosan and poly(vinyl alcohol) was prepared. Its swelling properties and electroresponsive behavior in aqueous NaCl solutions were studied. The results indicated that the water uptake ability of the hydrogel decreased with increasing ionic strength of aqueous NaCl solution. The Young's modulus, elongation at break and tensile strength of the hydrogel swollen in deionized water were 4.29 MPa, 76.5% and 3.26 MPa, respectively. The hydrogel swollen in the NaCl solution bent toward the anode under non‐contact direct current electric fields, and its bending speed and equilibrium strain increased with increasing applied voltage. The electroresponsive behavior of the hydrogel was also affected by the electrolyte concentration of external NaCl solution, and there was a critical ionic strength of 0.10 where the maximum equilibrium strain of the hydrogel occurred. By changing the direction of the applied potential cyclically, the hydrogel exhibited good reversible bending behavior. Copyright © 2011 Society of Chemical Industry

Preparation of porous TiNi intermetallic compound and the corrosion behavior in NaCl solution

This work presents a salt-responsive interpenetrating network (IPN) hydrogel with effective antimicrobial properties and surface regeneration. The hydrogels were engineered using the double network strategy to form loosely cross-linked zwitterionic poly(sulfobetaine vinylimidazole) (pSBVI) networks into the highly cross-linked cationic poly((trimethylamino)ethyl methacrylate chloride) (pTMAEMA) framework via photopolymerization. The pTMAEMA/pSBVI hydrogel has strong mechanical properties, with a fracture stress 120× higher than single network pTMAEMA hydrogel. In addition, there is inverse correlation between elastic modulus and elastic strain of pTMAEMA/pSBVI hydrogels as a function of ionic strength. The cationic pTMAEMA and zwitterionic pSBVI show opposite swelling behaviors in salt solutions due to the polyelectrolyte effect and antipolyelectrolyte effect. Therefore, the pTMAEMA/pSBVI hydrogel elicits a significant interfacial transition in solutions with different ionic strengths. The IPN hydrogels have switchable lubrication and optical transmittance between deionized water and 1.0 M NaCl solution. The protein adsorption tests further confirmed the switchable interface of salt-responsive IPN hydrogels. In addition, bacterial attachment test on pTMAEMA/pSBVI hydrogels with Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli) show bacterial killing rates of the IPN hydrogel over 80% for S. epidermidis and 90% for E. coli after incubating the hydrogels in the bacterial solutions for 24 h. The bacterial release rate from the IPN hydrogel reached 96% after washing with 1.0 M NaCl solution. Furthermore, the excellent reusability of the pTMAEMA/pSBVI hydrogels was demonstrated by the high bacterial killing and bacterial release rates after five kill/release cycles. The work presents a new stimuli-responsive IPN hydrogel with structural modulation, tunable antimicrobial properties, and surface regeneration by ionic strength. Integrating two salt-responsive polymers with mutually independent actions into a single material provides a new direction for smart materials with potential medical and industrial applications.

Gold(III)-DNA interaction in aqueous solution

Proper evaluation of the Gibbs free energy and other properties of seawater and other aqueous solutions is essential in the analysis of desalination systems. Standard seawater has been studied extensively and property data are readily accessible. However, many aqueous solutions requiring desalination have significantly different compositions from seawater and seawater data are generally not accurate for these solutions. Experimental data for a given aqueous solution may be unavailable under the conditions of interest. Therefore, there is a need to model relevant physical properties from chemical thermodynamic principles. In particular, for solutions that are not ideal, the activity and fugacity coefficients must be considered. In this paper, the effect of nonidealities in sodium chloride (NaCl) solutions is considered through a parametric study of the least work of separation for a desalination system. This study is used to determine the conditions under which the ideal solution approximation is valid and also to determine when an NaCl solution is a good approximation to standard seawater. It is found that the ideal solution approximation is reasonable within ranges of salinities and recovery ratios typical of those found in the seawater desalination industry because many of the nonidealities cancel out, but not because the solution behaves ideally. Additionally, it is found that NaCl solutions closely approximate natural seawater only at salinities typically found in seawater and not for salinities found in typical brackish waters.

Poly(2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS)/hyaluronic acid (HA) interpenetrating polymer network (IPN) hydrogels have been prepared by using the sequential‐IPN method. The IPN hydrogels exhibited swelling behavior in solutions at various pHs, in NaCl solutions, and under electrical DC stimulation. The IPN hydrogels were highly swollen in water, but lost much of their water capacity when transferred to solutions having a high ionic strength. The IPN hydrogels showed a significant responsive deswelling in an applied electric field. This behavior indicates the potential application of IPN hydrogels as biomaterials. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1731–1736, 2004

The interaction of a non-steroidal anti-inflammatory drug, niflumic acid (NFA), with human serum albumin (HSA) has been investigated by (19)F nuclear magnetic resonance (NMR) spectroscopy. A (19)F NMR spectrum of NFA in a buffered (pH 7.4) solution of NaCl (0.1 mol L(-1)) contained a single sharp signal of its CF(3) group 14.33 ppm from the internal reference 2,2,2-trifluoroethanol. Addition of 0.6 mmol L(-1) HSA to the NFA buffer solution caused splitting of the CF(3) signal into two broadened signals, shifted to the lower fields of 14.56 and 15.06 ppm, with an approximate intensity ratio of 1:3. Denaturation of HSA by addition of 3.0 mol L(-1) guanidine hydrochloride (GU) restored a single sharp signal of CF(3) at 14.38 ppm, indicating complete liberation of NFA from HSA as a result of its denaturation. These results suggest that the binding is reversible and occurs in at least two HSA regions. Competitive (19)F NMR experiments using warfarin, dansyl-L: -asparagine, and benzocaine (site I ligands), and L: -tryptophan and ibuprofen (site II ligands) revealed that NFA binds to site I at two different regions, Ia and Ib, in the ratio 1:3. By use of (19)F NMR with NFA as an (19)F NMR probe the nonfluorinated site I-binding drugs sulfobromophthalein and iophenoxic acid were also found to bind sites Ia and Ib, respectively. These results illustrate the usefulness and convenience of (19)F NMR for investigation of the HSA binding of both fluorinated and nonfluorinated drugs.