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• PY-CH 3 and PY-H act as effective inhibitors for mild steel acidic corrosion. • The adsorption of PY-CH 3 and PY-H followed the Langmuir isotherm model. • Adsorption on the surface is analyzed by AFM, SEM/EDAX, XRD, and FTIR techniques. • Theoretical data provide in-depth understanding of the experimental results. The present paper examines the adsorption of two novel heterocyclic compounds of the pyran derivatives, namely 2-amino-5-oxo-4-(p-tolyl)-4H,5H-pyrano [3,2-c]chromene-3-carbonitrile (PY-CH 3) et 2-amino-5-oxo-4-phenyl-4H,5H-pyrano [3,2-c]chromene-3-carbonitrile (PY-H)against corrosion of mild steel in molar HCl medium. The experimental investigation was carried out using several techniques including Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP). The inhibition efficiencies of PY-CH 3 and PY-H followed the order: 80.0% (PY-CH 3) < 90.0% (PY-H). The adsorption process of PY-CH 3 and PY-H on the mild steel surface follows Langmuir adsorption model. Surface characterization analysis using Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDS), Atomic Force Microscopy (AFM), X-ray diffraction analysis (XRD), and Infrared Spectroscopy (FT-IR) supported the formation of a barrier layer that covers the mild steel surface. WL measurements were also tested using inductively coupled spectroscopy (ICP) and UV-Vis spectrometry (UV-Vis). The interaction mechanism of PYCH 3 and PY-H with mild steel surface and their mode of adsorption were studied using DFT and Monte Carlo (MC) simulations, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical test data indicate the order of inhibition efficiency: Q-1 > Q-2. • Q-1 and Q-2 adsorb on the steel/solution in accordance with the Langmuir model. • PDP plots indicated that the Q-1 and Q-2 compounds are considered mixed-type inhibitors. • Surface characteristics analysis provided strong evidence for the existence of inhibition film on steel surface. • Theoretical modeling provides deep insights into the inhibition performance of Q-1 and Q-2. The present study has investigated the functional effect of modifying a simple function (NH 2) that correspond to a heterocycle (Benzodiazepine), acquired through two similar reactions, on the inhibition of mild steel corrosion (m-steel) in hydrochloric medium (1.0 M HCl). [5-((2-aminobutoxy) methyl)-quinolin-8-ol (Q-2) and 7-chloro-2,2,4-trimethyl-2,3 dihydro-1H benzo[b][1,4]diazepin-1-yl)methyl)quinolin-8-ol (Q-1)] were synthesized by two environmentally friendly reactions and characterized using Proton nuclear magnetic resonance (1H NMR) and Carbon nuclear magnetic resonance (13C NMR) spectroscopy. The inhibitory action of both organic compounds was evaluated by numerous techniques that have been already described in the literature (electrochemical impedance spectroscopy (EIS) and Potentiodynamic Polarization (PDP)).The inhibition efficiency increased with the increasing inhibitor concentration to 92.8% and91.1 % for Q-1 and Q-2 respectively at 10−3 M. The submerged surface of steel has been identified by scanning electron microscopy coupled with Energy Dispersive X-Ray Spectroscopy (SEM/EDS), Infrared spectroscopy (FT-IR), atomic force microscopy (AFM) spectroscopy and Contact angle measurements (θ). The corrosive solutions after corrosion tests have been identified by UV–visible spectrometry (UV–vis) and Inductively Coupled Plasma Emission Spectroscopy analysis (ICP-OES). The experimental studies PDP and EIS were completed by the theoretical studies Density-functional theory (DFT) and Monte Carlo (MC) simulation). Experimental data have shown that the studied additives Q-1 and Q-2 are effective against the corrosion acid of m-steel. In addition, their adsorption onto steel surface follow Langmuir adsorption isotherm. [ABSTRACT FROM AUTHOR]

The impact of key classes of compounds found in wine on protein removal by the ion-exchange resin, Macro-Prep ® High S, was examined by adsorption isotherm experiments. A model wine system, which contained a prototypical protein Bovine Serum Albumin (BSA), was used. We systematically changed concentrations of individual chemical components to generate and compare adsorption isotherm plots and to quantify adsorption affinity or capacity parameters of Macro-Prep ® High S ion-exchange resin. The pH (hydronium ion concentration), ethanol concentration, and prototypical phenolics and polysaccharide compounds are known to impact interactions with proteins and thus could alter the adsorption affinity and capacity of Macro-Prep ® High S ion-exchange resin. At low equilibrium protein concentrations (< ~0.3 (g BSA)/L) and at high equilibrium protein concentrations in model wines at various pH, the adsorption behavior followed the Langmuir isotherm, most likely due to the resin acting as a monolayer adsorbent. The resulting range of BSA capacity was between 0.15-0.18 (g BSA)/(g Macro-Prep ® High S resin). With the addition of ethanol, catechin, caffeic acid, and polysaccharides, the protein adsorption behavior was observed to differ at higher equilibrium protein concentrations (> ~0.3 (g BSA)/L), likely as a result of Macro-Prep ® acting as an unrestricted multilayer adsorbent at these conditions. These data can be used to inform the design and scale-up of ion-exchange columns for removing proteins from wines.

The properties of aerosols are of paramount importance in atmospheric chemistry and human health. The hydrogen bond network of glycerol-water aerosols generated from an aqueous solution with different mixing ratios is probed directly with X-ray photoelectron spectroscopy. The carbon and oxygen X-ray spectra reveal contributions from gas and condensed phase components of the aerosol. It is shown that water suppresses glycerol evaporation up to a critical mixing ratio. A dielectric analysis using terahertz spectroscopy coupled with infrared spectroscopy of the bulk solutions provides a picture of the microscopic heterogeneity prevalent in the hydrogen bond network when combined with the photoelectron spectroscopy analysis. The hydrogen bond network is composed of three intertwined regions. At low concentrations, glycerol molecules are surrounded by water forming a solvated water network. Adding more glycerol leads to a confined water network, maximizing at 22 mol %, beyond which the aerosol resembles bulk glycerol. This microscopic view of hydrogen bonding networks holds promise in probing evaporation, diffusion dynamics, and reactivity in aqueous aerosols.

A novel fluorescence probe based on graphene-aminofluorescein (GAF) for sensing glutamate is prepared by modifying graphene oxide (GO) with 5-aminofluorescein (AF), and shows high sensitivity and selectivity. The strong fluorescence of the GAF probe is quenched in the presence of glutamate, and the quenching exhibits a good linear relationship with the glutamate concentration within the range of 1-45 mg/L. In bovine serum, the accurate quantitation of glutamate is possible within the range of 6 mg/L to 30 mg/L. At the pH of 3.32 (close to the isoelectric point of glutamate), GAF can selectively detect glutamate in preference to other amino acids. The high sensitivity and specificity of this sensor enable a new method for the detection of glutamate in aqueous solutions and serums., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Silver nanowire arrays as surface-enhanced Raman scattering (SERS) substrates were prepared by a solid-state ionics method under the direct current electric field (DCEF) and used to rapidly detect melamine in aqueous solutions. The arrangement density and surface roughness of the prepared silver nanowire arrays are significantly different upon a change in the impressed current intensity. The growth mechanism of silver nanowire arrays was associated with the apical growth advantage and the irregular electrode interface. When the current intensity was 4 μA and 10 μA, the fractal dimension of silver nanowire arrays was 1.66 and 1.49, the diameters of nanowires ranged from 90 to 130 nm and 90 to 170 nm, and many densely arranged and regularly arranged silver nanoparticles lie in the prepared nanowire arrays, respectively. The result shows that there were more silver nanostructures and surface roughness under 4 μA DCEF. The Raman signal intensity of melamine molecule shows that the prepared SERS substrate exhibited a high sensitivity. The proposed method allow us detect melamine with a limit of 10 -15  mol/L and 10 -12  mol/L, which are lower than the safety limit estimated by the US food and Drug Administration. With its facile material synthesis, simple detection procedure and low detection concentration, this silver nanowire arrays with high surface roughness indicates a strong potential detection technique in the field of food safety., (Copyright © 2019 Elsevier B.V. All rights reserved.)

SCN- is one of the most important anions in metabolic processes. However, the investigation of SCN- in living systems is restricted by the lack of stable functional molecular tools. Herein, the first fluorene-based polymer fluorescent probe V1 was synthesized through rational design. Compared with small molecule fluorescent probes, V1 exhibited excellent fluorescence stability in bovine serum albumin (BSA) solution. Furthermore, the V1-based paper sensor was highly selective toward SCN- in aqueous solution. Significantly, these merits of the probe V1 enable the detection of SCN- in different living cell lines and zebrafish.

A magnetic solid-phase extraction method was developed using maghemite as an efficient sorbent for the separation and preconcentration of antimony prior to its determination by ET-AAS. Maghemite was synthesized through a simple method and characterized by XRD, FT-IR and SEM. Various factors affecting maghemite synthesis, separation and preconcentration of antimony such as desorption solvent type, concentration and volume, desorption temperature and time, sample pH, amount of sorbent, and extraction temperature and time were optimized. The effects of interfering ions were also investigated. Under optimized conditions, the method exhibited good linearity (r 2  > 0.9960). The sorption capacity and enrichment factor (EF) of the method were 37.5 mg g -1 and 242, respectively. The limit of detection (LOD) was 0.03 ng mL -1 . The intraday, interday, and batch-to-batch relative standard deviations (%RSDs) were quite reasonable. The proposed method was applied to various real samples and the relative recoveries found were between 95.8 and 104.0 %., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Maintaining a proper balance between specific intermolecular interactions and non-specific solvent interactions is of critical importance in molecular simulations, especially when predicting binding affinities or reaction rates in the condensed phase. The most rigorous metric for characterizing solvent affinity are solvation free energies, which correspond to a transfer from the gas phase into solution. Due to the drastic change of the electrostatic environment during this process, it is also a stringent test of polarization response in the model. Here, we employ both the CHARMM fixed charge and polarizable force fields to predict hydration free energies of twelve simple solutes. The resulting classical ensembles are then reweighted to obtain QM/MM hydration free energies using a variety of QM methods, including MP2, Hartree⁻Fock, density functional methods (BLYP, B3LYP, M06-2X) and semi-empirical methods (OM2 and AM1 ). Our simulations test the compatibility of quantum-mechanical methods with molecular-mechanical water models and solute Lennard⁻Jones parameters. In all cases, the resulting QM/MM hydration free energies were inferior to purely classical results, with the QM/MM Drude force field predictions being only marginally better than the QM/MM fixed charge results. In addition, the QM/MM results for different quantum methods are highly divergent, with almost inverted trends for polarizable and fixed charge water models. While this does not necessarily imply deficiencies in the QM models themselves, it underscores the need to develop consistent and balanced QM/MM interactions. Both the QM and the MM component of a QM/MM simulation have to match, in order to avoid artifacts due to biased solute⁻solvent interactions. Finally, we discuss strategies to improve the convergence and efficiency of multi-scale free energy simulations by automatically adapting the molecular-mechanics force field to the target quantum method.

A new environmentally-friendly, simple, selective and sensitive probe for detecting formaldehyde, based on naturally-occurring compounds, through either colorimetric or fluorescence changes, is described. The probe is able to detect formaldehyde in both solution and the gas phase with limits of detection of 0.24 mM and 0.7 ppm, respectively. The probe has been tested to study formaldehyde emission in contaminated real atmospheres. The supported probe is easy to use and to dispose, and is safe and suitable as an individual chemodosimeter.

Introduction: Homeopathic remedies usually contain a significant amount of ethanol as a co-solvent with water, a pharmaceutical formulation that may raise some concern when remedies are tested in vitro or in laboratory animals, due to the assessed toxicity of ethanol on cell cultures and organisms. The amount of alcohol in a homeopathic remedy is adjusted following the different homeopathic pharmacopoeias but it is rarely below 30% v/v, which is a molar mass established to meet both Hahnemann's traditional heritage and the hypothetical role of ethanol in "imprinting" water, through the formation of nanobubbles, with the homeopathic activity of the remedy., Aims: This article aims at discussing the role of ethanol in homeopathic dilutions and how its chemical nature should affect the experimental approach in homeopathy., Issues Under Debate: While the content of ethanol in a homeopathic remedy should be as low as 20% v/v, which is a molar fraction able to catalyze the formation of nanobubbles in a dynamized alcohol-water dilution, this amount raises concern about ethanol toxicology in the experimental research with laboratory animals or in vitro. Several authors diluted 1:100 ethanol 30% v/v from their tested homeopathic dilutions with distilled water to prevent the cytotoxic effect of the alcohol, but in doing so, they probably reduced the ability of ethanol (now 0.3% v/v) to induce the formation of nanobubbles, thus probably affecting the homeopathic property of the same dilution. This may generate concerns about how to manage an experimental setting, to meet both the "chemical" nature of ethanol and its role in "homeopathy," an issue that is discussed in the article., Conclusion: Any author working with homeopathic dilutions containing a molar fraction of ethanol higher than 20% should take into account the fact that ethanol is cytotoxic and may be a catalyst to the formation of nanobubbles, and so should adjust the experimental approach accordingly., Competing Interests: None declared., (The Faculty of Homeopathy.)

NMR diffusometry is a powerful but challenging method to analyze complex mixture. Each component diffuses differently, from the faster small species to the slower large species, corresponding to different signal attenuation. However, the method is highly sensitive to the quality of the acquired data and the performance of the processing used to resolve multiexponential signals influences. Adapting the signal decay sampling to the mixture composition is one way to improve the precision of the measure. In this work, we propose a prediction tool, based on the calculation of the Cramér-Rao lower bound to minimize the variance of diffusion coefficient estimation in order to determine the optimal number of diffusion gradient steps, the best diffusion gradient sampling (among linear, exponential, quadratic and sigmoidal ones) and the optimal maximum diffusion factor. The tool was validated experimentally on a unimer/micelle solution of sodium dodecyl sulfate and on Caelyx ® , a commercial liposomal preparation containing a mixture of pegylated-liposomes and sucrose., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In this study, a mixture of polyethylenimine (PEI) and polyvinyl chloride (PVC) was reacted at 80 °C for 6 h to synthesize crosslinked PEI/PVC polymer solution, which was injected to produce the PEI/PVC-crosslinked fiber (PEI/PVC-CF). PEI/PVC-CF was investigated as an adsorbent to remove and recover Pd(II) from acidic solutions. In order to examine the adsorption characteristics and usability of PEI/PVC-CF for Pd(II) recycling, several experiments such as isotherm, kinetics, desorption and reuse were conducted. The adsorption isotherms were fitted using the Langmuir and Freundlich models, respectively. The maximum adsorption capacity was estimated as 146.03 mg/g according to the Langmuir model. The kinetic experiments demonstrated that adsorbent reaches adsorption equilibrium within 60 min for initial Pd(II) concentrations of 25-100 mg/L. After adsorption, Pd(II) on PEI/PVC-CF was easily desorbed using acidified thiourea solution, and the desorption efficiency increased with the thiourea concentration. It was also demonstrated that PEI/PVC-CF can be used repeatedly for at least five cycles without reduction in adsorption capacity., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Despite numerous methods for the detection of antibiotic residues, they are usually destructive and require tedious pre-treatment. Terahertz time-domain spectroscopy (THz-TDS) is an emerging technology that has advantages for analyzing chemical and biological compounds since THz waves are very sensitive to the molecular vibrational modes. Here we incorporated attenuated total reflection technique into the THz-TDS and demonstrated that this technology (ATR THz-TDS) allowed to determine the complex refractive indices of tetracycline hydrochloride (TCH) solutions with high accuracy and could be used to predict their concentrations. Our results from the simple linear regression models indicated that the complex refractive index exhibited a monotonic decrease with an increase in the TCH concentration. This study will provide new knowledge about the concentration determination of a liquid sample that couldn't be elucidated with the conventional THz-TDS technologies., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Whey protein isolate (WPI) solutions (12.8%w/w protein) were treated with varying concentrations of H 2 O 2 in the range of 0-0.144 H 2 O 2 to protein ratios (HTPR) by the addition of the required quantity of H 2 O 2 and deionized water. The samples were analyzed for heat stability, rheological properties, denaturation level of β-lactoglobulin (β-LG) and α-lactalbumin (α-LA). The samples treated with H 2 O 2 concentration >0.072 (HTPR) showed significant improvement in the heat stability, and decreased whey protein denaturation and aggregation. The WPI solution treated with H 2 O 2 (>0.072 HTPR) remained in the liquid state after heat treatment at 120°C, whereas the control samples formed gel upon heat treatment. Detailed analysis of these samples suggested that the improvement in the heat stability of H 2 O 2 treated WPI solution was attributed to the significant reduction in the sulfhydryl-disulfide interchange reaction during denaturation of β-LG and α-LA., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Understanding transport in rough fractures from non-Fickian to Fickian regimes and the prediction of non-Fickian transport is critical for the development of new transport theories and many practical applications. Through computational experiments that fall within the macrodispersion regime, we first simulated and analyzed solute transport through synthetic rough fractures with stationary geometrical properties (i.e., fracture roughness σ b /〈b〉 and correlation length λ, where b refers to aperture with its standard deviation σ b and arithmetic mean 〈b〉) across increasing fracture longitudinal transport domain length L, with L/λ ranging from 2.5 to 50. The results were used to determine how solute transport behavior evolves with increasing scale in the longitudinal direction. Moreover, a set of correlated fractures with aperture fields following normal and log-normal distributions was created to further identify and quantify the dependence of non-Fickian transport on roughness. We found that although persistent intermittent velocity structures were present, the breakthrough curves (BTCs) and residence time distributions showed diminishing early arrival and tailing, features of non-Fickian transport, with increasing longitudinal L/λ, ultimately converging to a Fickian transport regime given σ b /〈b〉 remained constant. Inverse analysis of the experimental BTCs with the advection-dispersion equation (ADE) model showed that the dispersion coefficient (D) was non-trivially scale-dependent. Simulation results for rough fractures with varying σ b /〈b〉 and L/λ indicated that the ratio of fluid velocity to transport velocity fitted to the ADE model depends on σ b /〈b〉 and L/λ. The continuous time random walk (CTRW) performed much better across all transport scales, and resulted in scale-independent fitted parameters, i.e., β in the memory function. The fitted β is proportional to σ b /〈b〉but is insensitive to L/λ. Therefore, bulk longitudinal solute transport across the pre-asymptotic and asymptotic regimes can be estimated based on the CTRW model parameterized by measurable fracture physical properties., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Quality control of hospital pharmacy formulations is of the utmost importance to ensure constant quality and to avoid potential mistakes before administration to the patient. In this study we investigated the applicability of refractometry as a fast, inexpensive and easy-to-use quality control measurement. Refractive indices (RI) of a multitude of different hospital formulations with varying concentrations of active compound were measured. The samples consisted of a number of binary aqueous solutions (one compound in water), complex aqueous solutions (multiple compounds in water or in a constant matrix), two suspensions and one emulsion. For all these formulations, linear regression analysis was performed, quality control limits determined and accuracy and repeatability were checked. Subsequently, actual hospital pharmacy samples were analyzed to check whether they were within the specified limits. For both binary and complex aqueous formulations, repeatability was good and a linear correlation for all samples could be observed on condition that the concentration of the active compound was sufficiently high. The refractometer was not sensitive enough for solutions of folic acid and levothyroxine, which had too low a concentration of active compound. Due to lack of homogeneity and light scattering, emulsions and suspensions do not seem suitable for quality control by refractometry. A mathematical equation was generated to predict the refractive index of an aqueous solution containing clonidine HCl as active compound. Values calculated from the equation were compared with measured values and deviations of all samples were found to be lower than 1.3%. In order to use refractometry in a hospital pharmacy for quality control of multicomponent samples, additional intermediate measurements would be required, to overcome the fact that refractometry is not compound specific. In conclusion, we found that refractometry could potentially be useful for daily, fast quality measurements of relatively concentrated binary and more complex aqueous solutions in the hospital pharmacy., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Minimum miscible pressure (MMP) of gas and oil system is a key parameter for the injection system design of CO2 miscible flooding. Some industrial standard approaches such as the experiment using a rising bubble apparatus (RBA), the slim tube tests (STT), the pressure-density diagram (PDD), etc. have been applied for decades to determine the MMP of gas and oil. Some theoretical or experiential calculations of the MMP were also applied to the gas-oil miscible system. In the present work, an improved technique based on our previous research for the estimation of the MMP by using magnetic resonance imaging (MRI) was proposed. This technique was then applied to the CO2 and n-alkane binary and ternary systems to observe the mixing procedure and to study the miscibility. MRI signal intensities, which represent the proton concentration of n-alkane in both the hydrocarbon rich phase and the CO2 rich phase, were plotted as a reference for determining the MMP. The accuracy of the MMP obtained by using this improved technique was enhanced comparing with the data obtained from our previous works. The results also show good agreement with other established techniques (such as the STT) in previous published works. It demonstrates increases of MMPs as the temperature rise from 20 °C to 37.8 °C. The MMPs of CO2 and n-alkane systems are also found to be proportional to the carbon number in the range of C10 to C14., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The ATP:ADP molar ratio is an important physiological factor. However, in previous literatures, ATP and ADP could not be distinguished by Raman spectroscopy due to the high similarity of molecular structure. To challenge this problem, also considering that the γ phosphate group may interact with adenine group and cause a different variation of the Raman spectrum than that of ADP, a highly sensitive, low-cost, environment protecting, flexible and super-hydrophobic Au nanoparticles/cicada wing (Au/CW) substrate with three-dimension structure was fabricated and employed as an active surface-enhanced Raman scattering (SERS) substrate to detect the ATP:ADP molar ratios. The concentration as low as 10(-8)M for ATP and ADP was analyzed to determine the limit of detection. This SERS study on various ATP:ADP molar ratios demonstrates that ATP:ADP could be distinguished and the quantitative determination of ATP content was achieved. Moreover, a principle was speculated based on the molecular structures of ATP and ADP of the Raman peaks centered at ~685 and ~731cm(-1) to explain the linear relationship between the area ratio and the molar ratio. A new method has been developed for quantitative determination of ATP:ADP molar ratio based on Au/CW substrate by the SERS method., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The ever increasing numbers and users of designer drugs means that analytical techniques have to evolve constantly to facilitate their identification and detection. We report that surface enhanced Raman scattering (SERS) offers a relatively fast and inexpensive method for the detection of MDAI at low concentrations. Careful optimisation of the silver sol, and salt concentrations was undertaken to ensure the SERS analysis was both reproducible and sensitive. The optimised system demonstrated acceptable peak variations of less than 15% RSD and resulted in a detection limit of just 8 ppm (5.4 × 10(-5) M).

The use of ammonium fluoride as a mobile phase additive in aqueous normal phase chromatography with silica hydride-based stationary phases and mass spectrometry detection is evaluated. Retention times, peak shape, efficiency and peak intensity are compared to the more standard additives formic acid and ammonium formate. The test solutes were NAD, 3-hydroxyglutaric acid, α-ketoglutaric acid, p-aminohippuric acid, AMP, ATP, aconitic acid, threonine, N-acetyl carnitine, and 3-methyladipic acid. The column parameters are assessed in both the positive and negative ion detection modes. Ammonium fluoride is potentially an aggressive mobile phase additive that could have detrimental effects on column lifetime. Column reproducibility is measured and the effects of switching between different additives are also tested., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Raman sensing and microscopy are among the most specific optical technologies to identify the chemical compounds of unknown samples, and to enable label-free biomedical imaging. Here we present a method for stimulated Raman scattering spectroscopy and imaging with a time-encoded (TICO) Raman concept. We use continuous wave, rapidly wavelength-swept probe lasers and combine them with a short-duty-cycle actively modulated pump laser. Hence, we achieve high stimulated Raman gain signal levels, while still benefitting from the narrow linewidth and low noise of continuous wave operation. Our all-fibre TICO-Raman setup uses a Fourier domain mode-locked laser source to achieve a unique combination of high speed, broad spectral coverage (750-3,150 cm(-1)) and high resolution (0.5 cm(-1)). The Raman information is directly encoded and acquired in time. We demonstrate quantitative chemical analysis of a solvent mixture and hyperspectral Raman microscopy with molecular contrast of plant cells.

Optical resonant cavity sensors are gaining increasing interest as a potential diagnostic method for a range of applications, including medical prognostics and environmental monitoring. However, the majority of detection demonstrations to date have involved identifying a "known" analyte, and the more rigorous double-blind experiment, in which the experimenter must identify unknown solutions, has yet to be performed. This scenario is more representative of a real-world situation. Therefore, before these devices can truly transition, it is necessary to demonstrate this level of robustness. By combining a recently developed surface chemistry with integrated silica optical sensors, we have performed a double-blind experiment to identify four unknown solutions. The four unknown solutions represented a subset or complete set of four known solutions; as such, there were 256 possible combinations. Based on the single molecule detection signal, we correctly identified all solutions. In addition, as part of this work, we developed noise reduction algorithms.

For the first time an easy-to-make receptor 2-chloro-3-(thiazol-2-ylamino)naphthalene-1,4-dione (R1) for highly selective sensing of Hg(ii) ions in aqueous solution and in the solid state through the formation of an Hg-C bond was developed. The Hg(ii) ion sensing properties of R1 were investigated using UV-Vis, fluorescence and (1)H & (13)C NMR spectral studies. The results indicated that the receptor selectively senses Hg(ii) ions via the formation of a 1 : 1 complex of moderate stability (Ka = 3.5 × 10(4) M(-1)). The NMR spectral studies indicated that complexation between R1 and Hg(ii) occurs through the formation of an Hg-C bond (after deprotonation), which was confirmed by a single crystal XRD analysis of the product. When Hg(ii) was added to a solution of R1 in DMF-water (1 : 9 v/v), a dramatic color change from pale brown to blue was observed, while many common cations and anions did not interfere with the recognition process. The detection limit was 0.3 μM, which is much lower than the permissible limit of Hg(ii) in drinking water (0.001 mg L(-1)) as recommended by the WHO. The simple grinding of R1 with Hg(ii) in the solid state also exhibited the same dramatic colour change which is easily detectable visually.

Digital microfluidics (DMF) is a powerful technique for sample preparation and analysis for a broad range of biological and chemical applications. In many cases, it is desirable to carry out DMF on an open surface, such that the matrix surrounding the droplets is ambient air. However, the utility of the air-matrix DMF format has been severely limited by problems with droplet evaporation, especially when the droplet-based biochemical reactions require high temperatures for long periods of time. We present a simple solution for managing evaporation in air-matrix DMF: just-in-time replenishment of the reaction volume using droplets of solvent. We demonstrate that this solution enables DMF-mediated execution of several different biochemical reactions (RNA fragmentation, first-strand cDNA synthesis, and PCR) over a range of temperatures (4-95 °C) and incubation times (up to 1 h or more) without use of oil, humidifying chambers, or off-chip heating modules. Reaction volumes and temperatures were maintained roughly constant over the course of each experiment, such that the reaction kinetics and products generated by the air-matrix DMF device were comparable to those of conventional benchscale reactions. This simple yet effective solution for evaporation management is an important advance in developing air-matrix DMF for a wide variety of new, high-impact applications, particularly in the biomedical sciences.

The phytoextraction capacity of Italian ryegrass (Lolium multiflorum L.) to remove terbuthylazine (TBA) from aqueous solution has been assessed using a plant-based biotest (RHIZOtest). Three TBA concentrations (0.5, 1.0 and 2.0 mg L(-1)) were chosen to evaluate the tolerance capacity of the ryegrass. Even though the treatments negatively affected plants, they were able to remove up to 30-40% of TBA. In addition, some enzymatic activities involved in the response to TBA-induced stress were determined. Glutathione S-transferase (GST) has been activated with a TBA-dose dependent trend; ascorbate peroxidase (APX) activities have been induced within the first hours after the treatments, followed by decreases or disappearance in plants exposed to two higher dosages. In conclusion, this case-study highlights that the combination of ryegrass and RHIZOtest resulted to be effective in the remediation of aqueous solutions polluted by TBA., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Injectable polymer scaffolds are particularly attractive for guided tissue growth and drug/cell delivery with minimally invasive intervention. In the present work, "all-polymeric" gelling systems based on pectins and water-soluble maltose-conjugated chitosans (CM) have been developed. Maltose-conjugated chitosan has been synthesized at three different molar ratios, as evaluated by FITR analysis and fluorimetric titration. A thorough rheological characterization of the blends and their parent solutions has been performed. Macroscopic gelation has been achieved by mixing the high esterification degree pectins with CM at higher maltose grafted to chitosan contents. Gels form in a few minutes and reach their full strength in less than two hours. These features encourage their further development as scaffold for tissue engineering., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

To explore the release of nitrogen oxide gases from reaction solutions, we developed a series of colorimetric sensors based on the cis-nitrogen-donating ligand bis(1-methylimidazol-2-yl)phenylmethoxymethane (BIPhMe). The complexes M(BIPhMe)X2, where M is Fe(2+) or Co(2+) and X is Cl(-), Br(-), or I(-), were prepared and structurally and spectroscopically characterized. The reactivity of these complexes toward NO(g) and NO2(g) in solution was explored. These complexes were then incorporated into test strips and syringes to provide devices that can qualitatively, and in the case of the syringes quantitatively, detect NO(g) and NO2(g) in a reaction headspace without additional equipment.

Distance measurements using double electron-electron resonance (DEER) and Gd(3+) chelates for spin labels (GdSL) have been shown to be an attractive alternative to nitroxide spin labels at W-band (95GHz). The maximal distance that can be accessed by DEER measurements and the sensitivity of such measurements strongly depends on the phase relaxation of Gd(3+) chelates in frozen, glassy solutions. In this work, we explore the phase relaxation of Gd(3+)-DOTA as a representative of GdSL in temperature and concentration ranges typically used for W-band DEER measurements. We observed that in addition to the usual mechanisms of phase relaxation known for nitroxide based spin labels, GdSL are subjected to an additional phase relaxation mechanism that features an increase in the relaxation rate from the center to the periphery of the EPR spectrum. Since the EPR spectrum of GdSL is the sum of subspectra of the individual EPR transitions, we attribute this field dependence to transition dependent phase relaxation. Using simulations of the EPR spectra and its decomposition into the individual transition subspectra, we isolated the phase relaxation of each transition and found that its rate increases with |ms|. We suggest that this mechanism is due to transient zero field splitting (tZFS), where its magnitude and correlation time are scaled down and distributed as compared with similar situations in liquids. This tZFS induced phase relaxation mechanism becomes dominant (or at least significant) when all other well-known phase relaxation mechanisms, such as spectral diffusion caused by nuclear spin diffusion, instantaneous and electron spin spectral diffusion, are significantly suppressed by matrix deuteration and low concentration, and when the temperature is sufficiently low to disable spin lattice interaction as a source of phase relaxation., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Evaporation-induced particle deposition patterns like coffee rings provide easy visual identification that is beneficial for developing inexpensive and simple diagnostic devices for detecting pathogens. In this study, the effect of chemotaxis on such pattern formation has been realized experimentally in drying droplets of bacterial suspensions. We have investigated the velocity field, concentration profile, and deposition pattern in the evaporating droplet of Escherichia coli suspension in the presence and absence of nutrients. Flow visualization experiments using particle image velocimetry (PIV) were carried out with E. coli bacteria as biological tracer particles. Experiments were conducted for suspensions of motile (live) as well as nonmotile (dead) bacteria. In the absence of any nutrient gradient like sugar on the substrate, both types of bacterial suspension showed two symmetric convection cells and a ring like deposition of particles after complete evaporation. Interestingly, the droplet containing live bacterial suspension showed a different velocity field when the sugar was placed at the base of the droplet. This can be attributed to the chemoattractant nature of the sugar, which induced chemotaxis among live bacteria targeted toward the nutrient site. Deposition of the suspended bacteria was also displaced toward the nutrient site as the evaporation proceeded. Our experiments demonstrate that both velocity fields and concentration patterns can be altered by chemotaxis to modify the pattern formation in evaporating droplet containing live bacteria. These results highlight the role of bacterial chemotaxis in modifying coffee ring patterns.

An imatinib intermediate, 6-methyl-N-[4-(pyridin-3-yl)pyrimidin-2-yl]benzene-1,3-diaminepyridopyrimidotoluidine (PPT-1), was developed for the colorimetric sensing of Cu(2+) ions in aqueous solution. With Cu(2+), the receptor PPT-1 showed a highly selective naked-eye detectable color change from colorless to red over the seventy other tested cations. The colorimetric sensing ability of PPT-1 was successfully utilized in the preparation of test strips and supported silica for the real samples analysis to detect Cu(2+) ions from 100% aqueous environment. Moreover, the iodide-sensing ability of receptor PPT-1 was explored among the ten examined anions.

A numerical study was undertaken to investigate the effects of waves on groundwater flow and associated inland-released solute transport based on tracer experiments in a laboratory beach. The MARUN model was used to simulate the density-dependent groundwater flow and subsurface solute transport in the saturated and unsaturated regions of the beach subjected to waves. The Computational Fluid Dynamics (CFD) software, Fluent, was used to simulate waves, which were the seaward boundary condition for MARUN. A no-wave case was also simulated for comparison. Simulation results matched the observed water table and concentration at numerous locations. The results revealed that waves generated seawater-groundwater circulations in the swash and surf zones of the beach, which induced a large seawater-groundwater exchange across the beach face. In comparison to the no-wave case, waves significantly increased the residence time and spreading of inland-applied solutes in the beach. Waves also altered solute pathways and shifted the solute discharge zone further seaward. Residence Time Maps (RTM) revealed that the wave-induced residence time of the inland-applied solutes was largest near the solute exit zone to the sea. Sensitivity analyses suggested that the change in the permeability in the beach altered solute transport properties in a nonlinear way. Due to the slow movement of solutes in the unsaturated zone, the mass of the solute in the unsaturated zone, which reached up to 10% of the total mass in some cases, constituted a continuous slow release of solutes to the saturated zone of the beach. This means of control was not addressed in prior studies., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This paper describes a novel approach utilizing nano-graphite-DNA hybrid and DNase I for the amplified detection of silver(I) ion in aqueous solutions for the first time. Nano-graphite can effectively quench the fluorescence of dye-labeled cytosine-rich single-stranded DNA due to its strong π-π stacking interactions; however, in the presence of Ag(+), C-Ag(+)-C coordination induces the probe to fold into a hairpin structure, which does not adsorb on the surface of nano-graphite and thus retains the dye fluorescence. Meanwhile, the hairpin structure can be cleaved by DNase I, and in such case Ag(+) is delivered from the complex. The released Ag(+) then binds other dye-labeled single-stranded DNA on the nano-graphite surface, and touches off another target recycling, resulting in the successive release of dye-labeled single-stranded DNA from the nano-graphite, which leads to significant amplification of the signal. The present magnification sensing system exhibits high sensitivity toward Ag(+) with a limit of detection of 0.3nM (S/N=3), which is much lower than the standard for Ag(+) in drinking water recommended by the Environmental Protection Agency (EPA). The selectivity of the sensor for Ag(+) against other biologically and environmentally related metal ions is outstanding due to the high specificity of C-Ag(+)-C formation. Moreover, the sensing system is used for the determination of Ag(+) in river water samples with satisfying results. The proposed assay is simple, cost-effective, and might open the door for the development of new assays for other metal ions or biomolecules., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Objective: To evaluate bactericidal efficacy of alcohol solution during actual use and typical storage conditions in community hospital and health centers., Material and Method: The alcohol samples were collected immediately after the first bottle-opening (day 0) and on day 3, 7, 14, 21 and 30 from 10 stations in hospital and community health centers in Pone-na-kaew district, Sakon Nakhon province, Thailand, during May-July 2011. Bactericidal efficacy of these samples against Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae was evaluated. Ethanol concentration was quantified by a gas chromatography method., Results: Bactericidal efficacy of the alcohol samples still remained on day 30 with ethanol concentration range of 60.91-65.99% v/v., Conclusion: This finding should be considered as a cost-benefit model for using alcohol solution in community hospital and health centers.

The major objection to homeopathic medicine is that the doses of medicine prescribed in some cases are too dilute for any active ingredient to be present. The medicines would hence be rendered inactive, necessitating novel explanations for the action. A further examination of dilution in the light of the Langmuir equation shows that homeopathic medicines may not be as dilute as a simplistic application of Avogadro's Principle suggests, due to surface effects., (Copyright © 2013 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.)

The extractive separation of tellurium (IV) from hydrochloric acid media with tri-n-butyl phosphate (TBP) in kerosene was investigated. The dependence on the extraction of tellurium species, concentrations of tellurium and TBP, extraction time and stage, organic/aqueous ratio, and interferences from coexist metallic ions were examined and are discussed. Besides, the stripping agent and stripping time were also studied. It was found that the extraction reaction corresponds to the neutral complex formation mechanism and the extracted species is TeCl4 · 3TBP and that the extraction process is exothermic. The thermodynamic parameters of enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) of the extraction process were evaluated at -26.2 kJ · mol(-1), -65.6 J · mol(-1) · K(-1), and -7.0 kJ · mol(-1), respectively at 293 K.

The relative performance figure of merits was investigated for the two most common analytical methods employed for carbonyl compounds (CC), for example, between high performance liquid chromatography (HPLC)-UV detector (with 2,4-dinitrophenylhydrazine (DNPH) derivatization) and thermal desorption (TD)-gas chromatography (GC)-mass spectrometry (MS) (without derivatization). To this end, the suitability of each method is assessed by computing the relative recovery (RR) between the gas- and liquid-phase standards containing a suite of CC such as formaldehyde (FA), acetaldehyde (AA), propionaldehyde (PA), butyraldehyde (BA), isovaleraldehyde (IA), and valeraldehyde (VA) along with benzene (B) as a recovery reference for the GC method. The results confirm that a TD-GC-MS is advantageous to attain the maximum recovery for the heavier CCs (i.e., with molecular weights (MW) above BA-MW ≥ 74). On the other hand, the HPLC-UV is favorable for the lighter CCs (like FA and AA) with the least bias. Such compound-specific responses for each platform are validated by relative ordering of CCs as a function of response factor (RF), method detection limit (MDL), and recovery pattern. It is thus desirable to understand the advantages and limitations of each method to attain the CC data with the least experimental bias.

We demonstrate a new technique for analyzing surface tension of liquids. This is done upon examining the interference signals reflected from a remnant drop pending at the cleaved end of a single mode optical fiber. The resulting interference patterns are fitted to a multimirror Fabry-Perot model yielding information of the drop size. We show that the wetting process of the fiber plays an important role in drop formation; in particular, the drop size can be correlated to the surface tension of the liquid sample. The proposed configuration may render useful for liquids analysis using small sample volume.

Large-scale three-dimensional fluorescence imaging is essential for comprehensive and quantitative understanding of neuronal circuitry. We describe a water-based optical clearing agent, SeeDB, which clears fixed brain samples in a few days leaving many types of fluorescent dyes unquenched, including fluorescent proteins and lipophilic neuronal tracers. This method maintains a constant sample volume during the clearing procedure, an important factor to keep cellular morphology intact. After optical clearing with SeeDB, we can reach a depth of >1000 µm with confocal microscopy. When combined with two-photon microscopy, SeeDB allows us to image fixed mouse brains at millimeter-scale level., (Copyright © 2014 John Wiley & Sons, Inc.)

We present femtosecond time-resolved X-ray absorption spectroscopy of aqueous solution using a hard x-ray free electron laser (SACLA) and a synchronized Ti:sapphire laser. The instrumental response time is 200 fs, and the repetition rate of measurement is 10 Hz. A cylindrical liquid beam 100 μm in diameter of aqueous ammonium iron(III) oxalate solution is photoexcited at 400 nm, and the transient X-ray absorption spectra are measured in the K-edge region of iron, 7.10 - 7.26 keV, using a dual X-ray beam dispersive detection method. Each of the dual beams has the pulse energy of 1.4 μJ, and pump-induced absorbance change on the order of 10(-3) is successfully detected. The photoexcited iron complex exhibits a red shifted iron K-edge with the appearance time constant of 260 fs. The X-ray absorption difference spectra, with and without the pump pulses, are independent of time delay after 1.5 ps up to 100 ps, indicating that the photoexcited species is long-lived.

In situ synthesis of bare gold nanoparticles mediated by stainless steel as reducing agent was monitored via infrared attenuated total reflection (IR-ATR) spectroscopy. Gold nanoparticles were directly synthesized within the liquid cell of the ATR unit taking immediate advantage of the stainless steel walls of the ATR cell. As nanoparticles were formed, a layer of particles was deposited at the SiO2 ATR waveguide surface. Incidentally, the absorption bands of water increased resulting from surface-enhanced infrared absorption (SEIRA) effects arising from the presence of the gold nanoparticles within the evanescent field. Next to the influence of the Au(III) precursor concentration and the temperature, the suitability of IR-ATR spectroscopy as an innovative tool for investigating changes of nanoparticles in solution, including their aggregation promoted by an increase of the ionic strength or via a pH decrease, and for detailing the sedimentation process of gold nanoparticles was confirmed.

Amplitude modulated multiplexed flow analysis (AMMFA) has been improved by introducing air segmentation and software-based phase recognition. Sample solutions, the flow rates of which are respectively varied at different frequencies, are merged. Air is introduced to the merged liquid stream in order to limit the dispersion of analytes within each liquid segment separated by air bubbles. The stream is led to a detector with no physical deaeration. Air signals are distinguished from liquid signals through the analysis of detector output signals, and are suppressed down to the level of liquid signals. Resulting signals are smoothed based on moving average computation. Thus processed signals are analyzed by fast Fourier transform. The analytes in the samples are respectively determined from the amplitudes of the corresponding wave components obtained. The developed system has been applied to the simultaneous determinations of phosphate ions in water samples by a Malachite Green method. The linearity of the analytical curve (0.0-31.0 μmol dm(-3)) is good (r(2)>0.999) and the detection limit (3.3 σ) at the modulation period of 30s is 0.52 μmol dm(-3). Good recoveries around 100% have been obtained for phosphate ions spiked into real water samples., (© 2013 Elsevier B.V. All rights reserved.)

The present study describes the conductometric and spectroscopic study of the interaction of reactive anionic dyes, namely, reactive red 223 and reactive orange 122 with the cationic surfactant cetyltrimethyl ammonium bromide (CTAB). In a systematic investigation, the electrical conductivity data was used to calculate various thermodynamic parameters such as free energy (ΔG), enthalpy (ΔH), and the entropy (ΔS) of solubilization. The trend of change in these thermodynamic quantities indicates toward the entropy driven solubilization process. Moreover, the results from spectroscopic data reveal high degree of solubilization, with strong interactions observed in the cases of both dyes and the CTAB. The spontaneous nature of solubilization and binding was evident from the observed negative values of free energies (ΔG p and ΔG b).

A new kind of surface plasmon resonance (SPR) sensor based on silver-coated hollow fiber (HF) structure for the detection of liquids with high refractive index (RI) is presented. Liquid sensed medium with high RI is filled in the hollow core of the HF and its RI can be detected by measuring the transmission spectra of the HF SPR sensor. The designed sensors with different silver thicknesses are fabricated and the transmission spectra for filled liquids with different RI are measured to investigate the performances of the sensors. Theoretical analysis is also carried out to evaluate the performance. The simulation results agree well with the experimental results. Factors that might affect sensitivity and detection accuracy of the sensor are discussed. The highest sensitivity achieved is 6,607 nm/RIU, which is comparable to the sensitivities of the other reported fiber SPR sensors.

The study on biochar derived from plant biomass for environmental applications is attracting more and more attention. Twelve sets of biochar were obtained by treating four phytoremediation plants, Salix rosthornii Seemen, Thalia dealbata, Vetiveria zizanioides, and Phragmites sp., sequentially through pyrolysis at 500 °C in a N2 environment, and under different temperatures (500, 600, and 700 °C) in a CO2 environment. The cation exchange capacity and specific surface area of biochar varied with both plant species and pyrolysis temperature. The magnesium (Mg) content of biochar derived from T. dealbata (TC) was obviously higher than that of the other plant biochars. This biochar also had the highest sorption capacity for phosphate and ammonium. In terms of biomass yields, adsorption capacity, and energy cost, T. dealbata biochar produced at 600 °C (TC600) is the most promising sorbent for removing contaminants (N and P) from aqueous solution. Therefore, T. dealbata appears to be the best candidate for phytoremediation application as its biomass can make a good biochar for environmental cleaning.

Continuous time random walk (CTRW) has been successfully applied in the description of anomalous transport in porous media in recent years. We simulate solute transport in randomly packed spheres with the same diameter and use CTRW to analyze the simulated results. From analysis, we find that there exists weak anomalous transport in the approximately homogeneous porous media. The anomaly becomes more apparent with the increase of Pe. This conclusion consists with previous simulations in two-dimensional homogeneous media and experimental data. We also calculate the trapping probabilities of solute particles in stagnant regions, which could give a physically based explanation for this non-Gaussian behavior., (© 2013.)

Nanoelectrospray ionization (nanoESI) with a very fine emitter and nanoliter solution flow rate is known to be suitable for aqueous solutions. However, under atmospheric pressure, its stability with aqueous solutions is not always guaranteed particularly in the negative ion mode where corona and arc discharge tend to occur more easily. Electrical discharge can be quenched to a certain extent by adding electron scavenging gases like SF6 or CO2 to the ion source. The onset potential that is required to induce the discharge also increases with an increase of gas pressure. Recently, we have reported on a series of high pressure electrospray ion sources that were stable in both positive and negative ion modes using air or N2 as the working gas. In this paper, we compare the performance of nanoelectrospray under atmospheric pressure and super-atmospheric pressure for the analysis of samples in aqueous solution. The comparative study was performed using the same ion source chamber that could be pressurized up to 6 bar. The pressure in the first pumping stage of the mass spectrometer was kept constant when the ion source pressure was changed by using an additional pump with variable pumping speed. High pressure nanoESI optimized at 2-3 bar demonstrated a 3-5 times improvement in ion signal intensity compared to atmospheric pressure nanoESI, and the signal stability was significantly improved particularly in the negative mode.

In this study, to improve the problem of waiting for the growth of (90)Y for Cerenkov counting and save the time of (90)Sr analysis, an organic cocktail sample was counted by a liquid scintillation counting system immediately after the purification of (90)Sr without waiting for the growth of (90)Y. The chemical separation and the measurement procedures for (90)Sr radioactivity analysis can be completed in 24h. In order to verify the performance of the improved method, the activity of (90)Sr in six environmental reference samples was determined after radiochemical purification with a crown-ether resin column, and subsequent measurement by both the Cerenkov and the organic cocktail liquid scintillation counting methods. The results revealed that the organic cocktail liquid scintillation counting was quicker and had higher efficiency and lower minimum detectable activity (MDA) than the Cerenkov counting., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A novel BINOL-based ratiometric fluorescent sensor (R2) is presented, which can selectively respond to Zn(2+) over Cd(2+) and other metal ions with fluorescence enhancement in aqueous solution. The R2 was successfully applied in the imaging of Zn(2+) in living cells. Additionally, the in situ generated R2-Zn(II) ensemble could further serve as a probe to distinguish histidine from other amino acids via a displacement mode.