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Protection of amine groups by amide formation is still among the preferred strategies for multifunctional molecular synthesis despite its waste production, especially the enormous quantities of organic solvents used. In this study, we present a fast, cheap and eco-friendly method for amine group protection involving amide bond formation using choline chloride as a hydrogen bond acceptor and the starting amine as a hydrogen bond donor through the generation of "in situ" amine-based deep eutectic solvents. This novel approach avoids the use of toxic solvents, both during reaction and the work-up phase, thus representing a sustainable alternative to classic amine protection procedures. [ABSTRACT FROM AUTHOR]

The proton NMR spectra of two 13C-labeled isotopomers of styrene dissolved in two liquid crystalline solvents have been obtained and analyzed to yield four sets each of 24 dipolar couplings. These couplings were then used to investigate the structure of the ring and the ene fragments of the molecule, and the position of the maximum, [lowercase_phi_synonym]0, in the ring–ene bond rotational probability distribution. To do this, the effect on the dipolar couplings of small-amplitude vibrational motion was taken into account using vibrational wave functions calculated by molecular orbital and density functional methods. It is concluded that the NMR data are consistent with the ring fragment, averaged over the ring–ene rotation, planar, while the ene fragment is not. The value of [lowercase_phi_synonym]0 is found to be 18.0°±0.2° for the two solutions, compared with a value of 27° calculated by the molecular method MP2/6-31G*. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Several new technologies can be today implemented in buildings in order to achieve the NZEB goal. In this paper a novel computer model for predicting the energy demand of buildings integrating phase change materials, photovoltaic-thermal collectors, adjacent sunspaces and innovative daylighting control is presented. Through this tool, DETECt 2.2, written in MatLab and conceived for research purposes, the overall energy and economic performance of multi-zone NZEBs can be assessed. Both the active and passive effects on the energy demands of all the above mentioned technologies, even if simultaneously utilized, are taken into account by means of an integrated building modelling approach. In addition, parametric and sensitivity analyses, with a single simulation run, can be carried out for design purposes. A novel relevant case study referred to the energy design of a non-residential NZEB for Mediterranean climates is developed. For this building a suitable energy optimization analysis was also carried out. For each use of the indoor space, the optimal value of the pivotal design and operating parameters is calculated. Details about the optimal position of building PCMs and thermal insulation layers, also coupled to BIPV and/or BIPV/T systems, are provided. For the obtained best configuration very low heating and cooling demands are achieved (0.9 and 1.5 kWh/m 3 y, respectively). Results about a simplified economic analysis carried out on the investigated energy saving technologies are also reported. At last, new NZEB definition details and criteria are provided for non-residential buildings located in the southern European zones (Mediterranean climates). [ABSTRACT FROM AUTHOR]

This paper presents an analysis of an innovative renewable energy plant serving an existing indoor/outdoor swimming pool located in Naples. The proposed solar hybrid system is designed in order to balance the remarkable energy demand of the swimming pool facility and to ensure suitable comfort conditions for swimmers. With the aim to accomplish such goals, the dynamic thermal behavior of the swimming pool was analyzed as a function of the thermo-hygrometric conditions of the indoor space and on the meteorological conditions of the pool site. In order to properly design and size the proposed renewable energy system, different thermal pool loss formulations for the calculation of the swimming pool thermal balance, in indoor and outdoor regimes, are adopted. The solar hybrid system consists of a water cooled photovoltaic/thermal collectors plant (PV/T), designed to meet a part of the facility demands of electricity and heat. Electricity is completely utilized by the facility, while the produced thermal energy is primarily used to meet the pool thermal demand and secondarily for sanitary hot water scopes. In order to carry out dynamic simulations and sensitivity analyses, the system performance is designed and dynamically simulated in TRNSYS environment. The developed simulation model enables the calculation of both the indoor and outdoor swimming pool thermal losses and the overall energy and economic system performance. Such results are obtained as a function of the thermo-hygrometric conditions of the environment, of the occupants and the energy production of the renewable energy system. A sensitivity analysis, aiming to analyze the effect of some operation and design parameters on the energy and economic performance, is carried out. Finally, simulation results highlight: (i) the remarkable energy performance of the system due to the full utilization of the energy produced; (ii) need of incentive policies for improving the economic profitable of the proposed system. [ABSTRACT FROM AUTHOR]

A weakly ordering organic-based lyotropic phase and a strongly ordering nematic liquid crystal have been used as NMR media for a parallel study of the conformation and orientational order of the same solute, trans-stilbene. A careful comparison allows to figure out some interesting conclusions on accessibility and precision of the experimental data and reliability and accuracy of the conformational descriptions into these two kinds of mesophases. [ABSTRACT FROM PUBLISHER]

• LXNMR is used to study chirality-dependent conformations and order parameters of a chiral solute. • Two different R and S conformational distributions of a flexible case test molecule have been found. • Different R , S order parameter distributions of flexible chiral case test molecule have been found. The unique power of Liquid Crystal NMR (LXNMR) in obtaining information about the conformational equilibrium of small solutes dissolved in orienting media can be effectively used to study chirality-related phenomena. In this work we have been able, for the first time in our knowledge, to fully resolve the two different conformational distributions for the R and S enantiomers of a case test molecule (the chiral flexible 4FMBOH: 4-F-α-methyl benzyl alcohol), dissolved in a typical chiral non-racemic aligning solvent, made of PBLG (poly- γ -benzyl- L -glutamate, a helical chiral polypeptide) co-dissolved in CDCl 3. The two enantiomers show significant differences in their conformational behaviors, due to the different solute–solvent orientational molecular interactions experienced by the R and S species. In our opinion, fundamental studies of this kind could pave the way for a better understanding of chirality-dependent molecular interactions, often involved in a number of important chemical processes (concerning pharmaceuticals, biochemistry, advanced materials, etc.) [ABSTRACT FROM AUTHOR]

The correct estimation of building energy consumptions is assuming an always increasing importance, and a detailed reproduction of building structures, with all the single components involved, is necessary to achieve this aim. In addition, the current ecological development tries to limit the use of natural raw materials as building components, in favor of alternative (waste) materials, which ensure significant advantages from the economic, energetic and environmental point of views. In this work, dynamic heat and vapor transport in a typical three-dimensional (3D) building structure, involving different types of environmental-friendly concrete mixtures, have been simulated by using finite elements. In particular, the authors propose to substitute part of the aggregates with plastic waste and to use a fly ash based geopolymeric binder for the production of low conductivity concrete, to be employed in eco-efficient buildings. Concrete produced with natural limestone aggregates has been considered as the reference benchmark. The whole characterization of the different types of concrete tested in the present work has been obtained through laboratory experiments. The structure taken into account in the simulations is a 3D thermal bridge, typical of building envelopes. The thermal and hygrometric transient behavior of this structure, employing plastic waste in different percentages and geopolymer concrete, has been analyzed by the authors. [ABSTRACT FROM AUTHOR]

Abstract: The mechanisms conferring to the trans-stilbene derivatives their well known important biological properties are not yet completely clear; then, it is reasonable to suppose that their conformational equilibrium could play some kind of role (as found for many other molecules of pharmacological interest). In this scenario, the 4,4′-dichloro-trans-stilbene (DCS) can be considered as the prototype of a series of stilbenes substituted in 4,4′ positions in order to enhance their properties. Following this starting idea, we decided to study the conformational distribution of DCS in solution by Liquid Crystal NMR Spectroscopy (LXNMR), one of the best techniques to obtain this kind of information in the liquid state of matter. Our results show that the molecule is basically not planar: the most populated conformations we found are (a) the couple of symmetry-related, propeller-like structures, belonging to the C 2 point group and characterized by the phenyl rings disrotated of about 18.7° with respect to the vinyl plane and (b) the couple of symmetry-related Ci structures (where the rings are parallel, like the pedals of a cycle) having this time the two rings conrotated of an angle of ∼18.7° with respect to the vinyl fragment. [Copyright &y& Elsevier]

In the present paper, the peculiar orientational behavior, studied by liquid crystal NMR (LXNMR) spectroscopy, of the D2dsymmetry quasi-spherical molecule of tetramethylallene (TMA) dissolved in the nematic solvent I52 is exploited to attempt a quantitative experimental assessment of the correlation between molecular vibrations and overall rotations in weakly oriented molecules. The analysis of the very small DHHand 1D13C–Hdipolar couplings, available from the natural abundance LXNMR spectra of TMA at different temperatures, allows for a derivation leading (by making a few approximations) to the quantification of the vibration–reorientation (also called nonrigid) contribution affecting the observed direct 1D13C–Hdipolar coupling. The obtained results show that, under the particular conditions of the studied system (very weak orientational ordering of a highly symmetric molecule), this contribution is particularly important, in order to reproduce the whole value of the “observed” dipolar coupling. This issue is discussed and commented on at length in the work, also, by making reference to the analogy with perfectly symmetric molecules (such as methane and analogues) dissolved in liquid crystalline phases. [ABSTRACT FROM AUTHOR]

The origins of asthma might be traced back to events occurring during fetal life. Reduced lung development has been shown to be a risk factor both for viral induced wheeze and allergic asthma. The evidence for a causal relationship between exposure to environmental tobacco smoke, chemical domestic products for cleaning, outdoor pollutants, and reduction in lung function is quite strong. Reduced maternal intake of vitamin E, vitamin D, and zinc, or increased use of paracetamol during pregnancy is associated with increased wheezing outcomes in children. The odds ratio for asthma onset is also increased in infants born from mothers with oligohydramnios, chorioamnionitis, hypertension, preeclampsia, diabetes and exposed to stressful events. The risk of developing allergic asthma is increased if the child is exposed in the first months of life to synthetic bedding and is enhanced by allergen exposure and an inadequate barrier function of the skin. In conclusion, several lines of evidence support the concept of fetal programming and very early life events in the development of the different phenotypes of asthma. Since some environmental triggers can be easily avoided and some protective factors can be easily implemented all efforts should be made to prevent intrauterine insults and early sensitization. [ABSTRACT FROM AUTHOR]

Very accurate bond distances can be derived from dipolar couplings, Dij, obtained by analysis of the NMR spectra of samples dissolved in anisotropic solvents (LXNMR). To do this, however, the couplings must be corrected for the averaging produced by vibrational motion. The vibrational corrections require a knowledge of the force field, which may be obtained by fitting experimental vibrational frequencies or, much more easily, from quantum-mechanical computations. In the present study, the reliability of the methods used to calculate the force field and the effects on the accuracy of the vibrational corrections to the Dij is tested on benzene for which a very accurate structural study is available. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we suggest a new methodological approach to get in a very simple way a crude (but meaningful) conformational analysis of flexible molecules in fluid condensed phases (a very interesting matter where inter- and intra-molecular interactions are deeply involved). The test case we have chosen is the never-studied-before temperature dependence of inter-ring angle of biphenyl in a nematic solution. Undemanding 2H NMR experiments were carried out on perdeuterated biphenyl dissolved in the mesophase at different temperatures, to obtain deuterium quadrupolar splittings. Since the experimental data alone are not sufficient to allow the determination of the inter-ring angle for each temperature, they were supplemented with simulated orientational information: this ‘hybrid’ set of data was enough to obtain the searched conformational distribution versus T. The results, showing a very slight tendency of the inter-ring angle to increase with the temperature, lend themselves to immediate interesting speculations and encourages the accomplishment of more sophisticated and expensive experiments to investigate more in detail the phenomenology. In our opinion the suggested methodology, appealing for its easiness, could be useful, for example, for coarse grained conformational investigations of large flexible systems (as, e.g. biomolecules) in liquid media. [Copyright &y& Elsevier]

The induction of a cholesteric phase by doping an achiral nematic liquid crystal with an enantiopure solute is a phenomenon that, as in all general supramolecular phenomena of chiral amplification, depends in a subtle way on intermolecular interactions. The micrometric helical deformation of the phase director in the cholesteric phase is generated by the interplay of anisotropy and chirality of probe-medium interactions. In the case of a flexible chiral dopant, the solvent can influence the twisting power in two ways, difficult to disentangle: it is responsible for the solute orientational order, an essential ingredient for the emergence of phase chirality; but also it can affect the dopant conformational distribution and then the chirality of the structures present in the solution. In this work we have investigated methyl phenyl sulfoxide, a flexible, chiral molecule that, when dissolved in different nematics, can produce cholesteric phases of opposite handedness. This peculiar, intriguing sensitivity to the environment makes MPS a suitable probe for a thorough investigation of the effects of solute-solvent interactions on chiral induction in liquid crystals. NMR experiments in various nematic solvents have been performed in addition to twisting power measurements. From the analysis of partially averaged ¹H-¹H and 13C-¹H dipolar couplings, the effects of solvent on solute conformation and orientational order are disentangled, and this information is combined with the modeling of the chirality of intermolecular interactions, within a molecular field theory. The integration of different techniques allows an unprecedented insight into the role of solvent in mediating the chirality transfer from molecule to phase. [ABSTRACT FROM AUTHOR]

The differences between experimental and calculated order parameters of polar solutes dissolved in zero electric field gradient nematic liquid crystal mixtures (magic mixtures) could be interpreted, in the context of a recently proposed model [1,2], as an evidence of small but detectable effects of solute polarity in the orientational mechanisms. [ABSTRACT FROM AUTHOR]

The non-polar rigid molecules 1,4-difluorobenzene and p-benzoquinone dissolved in ZLI1132 and EBBA nematic solvents show a bizarre ‘double face’ rod-like or disk-like orientational behaviour, depending on the used solvent. In the present Letter it is shown that the observed effect, unpredictable on the basis of solely short-range orientating mechanisms, can be qualitatively accounted when also electrostatic long-range interactions are taken into account (in particular, the coupling between the solute quadrupole moment and the solvent electric field gradient). The obtained result confirms the non-negligible role played by electrostatic interactions, even in the case of non-polar molecules. [Copyright &y& Elsevier]

In this paper, a chirality-sensitive effective orientational potential is, for the first time, proposed. It describes, within the Molecular Field approximation, different solute-solvent ordering interactions, according to the P (clockwise) or M (counterclockwise) nature of helical particles dissolved in uniaxial anisotropic solvents composed, in their turn, of helical P or M particles. By making use of Monte Carlo-simulated order parameters, it is shown that the model is, in principle, able to lead to the absolute enantiorecognition of the unknown chirality of the helical solute particles. This makes it a possible interesting tool for exploiting NMR anisotropic observables in order to achieve the absolute enantiomer assignment of chiral helical solutes. Unlabelled Image • Helical solutes orientationally ordered in organized helical solvents are studied. • A mean torque potential sensitive to P (clockwise) and M (counterclockwise) chirality is formulated. • The effectiveness and reliability of the proposed model is tested on Monte Carlo simulated order parameters. • The model proved to be, in principle, a useful tool for absolute enantiorecognition of the solutes. [ABSTRACT FROM AUTHOR]

Forecasting user flows on transportation networks is a fundamental task for Intelligent Transport Systems (ITSs). Indeed, most control and management strategies on transportation systems are based on the knowledge of user flows. For implementing ITS strategies, the forecast of user flows on some network links obtained as a function of user flows on other links (for instance, where data are available in real time with sensors) may provide a significant contribution. In this paper, we propose the use of Artificial Neural Networks (ANNs) for forecasting metro onboard passenger flows as a function of passenger counts at station turnstiles. We assume that metro station turnstiles record the number of passengers entering by means of an automatic counting system and that these data are available every few minutes (temporal aggregation); the objective is to estimate onboard passengers on each track section of the line (i.e., between two successive stations) as a function of turnstile data collected in the previous periods. The choice of the period length may depend on service schedules. Artificial Neural Networks are trained by using simulation data obtained with a dynamic loading procedure of the rail line. The proposed approach is tested on a real-scale case: Line 1 of the Naples metro system (Italy). Numerical results show that the proposed approach is able to forecast the flows on metro sections with satisfactory precision. [ABSTRACT FROM AUTHOR]

Polymer-Dispersed Liquid Crystal, PDLC, are composite materials formed by liquid crystal droplets embedded in a polymer matrix. They allow to simultaneously exploit the electro-optical properties of liquid crystals and the mechanical properties of polymers, giving rise to interesting electro-optical devices such as smart windows. In this work monomer/LC mixtures in different weight ratios were polymerised in the presence of an external magnetic field to obtain PDLCs, whose director was aligned along the field direction. The time behaviour of LC order parameter was followed by 2H-NMR and the final morphology of PDLCs was investigated by SEM. Then, the electro-optical properties of PDLCs prepared in the absence of any magnetic field were investigated and correlated to the order parameter measurements, confirming the strong correlation between large order parameters and optimal electro-optical properties. [ABSTRACT FROM AUTHOR]

This paper proposes a method for estimating traffic flows on some links of a road network knowing the data on other links that are monitored with sensors. In this way, it is possible to obtain more information on traffic conditions without increasing the number of monitored links. The proposed method is based on artificial neural networks (ANNs), wherein the input data are the traffic flows on some monitored road links and the output data are the traffic flows on some unmonitored links. We have implemented and tested several single-layer feed-forward ANNs that differ in the number of neurons and the method of generating datasets for training. The proposed ANNs were trained with a supervised learning approach where input and output example datasets were generated through traffic simulation techniques. The proposed method was tested on a real-scale network and gave very good results if the travel demand patterns were known and used for generating example datasets, and promising results if the demand patterns were not considered in the procedure. Numerical results have underlined that the ANNs with few neurons were more effective than the ones with many neurons in this specific problem. [ABSTRACT FROM AUTHOR]

In liquid crystals, while the second and fourth rank orientational order parameters characterizing a nematic phase can be experimentally determined via several techniques, there is no straightforward experiment rendering the positional order parameters characterizing a smectic A phase. This work illustrates a novel method to estimate the positional order parameters of a smectogenic liquid crystal solvent from knowledge of the orientational order parameters of a number of solutes dissolved therein. The latter order parameters can be experimentally determined via liquid crystal NMR spectroscopy. These data can be then analyzed with a statistical-thermodynamic density functional theory, whose basic ingredient is a model for solute-solvent intermolecular interactions. Its parametrization and the subsequent fitting procedure eventually permit one to obtain the positional order parameters of the solvent besides the positional-orientational distribution function of the solutes. The method is applied to the smectogen 4,4′-di-n-heptyl-azoxybenzene, in which the solutes 1,4-dichlorobenzene and naphthalene have been dissolved. With the help of this exploratory practical example, pros and cons of the method are pointed out and further developments prospected. [ABSTRACT FROM AUTHOR]

In recent years, the food industry has become increasingly involved in researching vegetable fats and oils with appropriate mechanical properties (ease of transport, processing, and storage) and a specific lipidic composition to ensure healthy products for consumers. The chemical–physical behavior of these matrices depends on their composition in terms of single fatty acids (FA). However, as we demonstrate in this work, these properties, as well as the absorption, digestion and uptake in humans of specific FAs, are also largely determined by their regiosomerism within the TriAcylGlycerols (TAG) moieties (sn-1,2,3 positions). The goal of this work is to study for the first time vegetable fats obtained directly from a sample of natural cocoa butter (CB) through a process that manipulates the distribution of FAs but not their nature. Even if the initial percentage of each FA in the mixture remains the same, CB derivatives seem to show improved chemical–physical features. In order to understand which factors account for their physical and chemical characteristics, and to check whether or not the obtained new matrices could be considered as valid alternatives to other vegetable fats (e.g., palm oil (PO)), we carried out an experimental investigation at both the macroscopic and molecular level including: (i) Differential Scanning Calorimetry (DSC) analyses to examine thermal features; (ii) rheological testing to explore mechanical properties; (iii) powder X-ray diffraction (PXRD) to evaluate the solid-state phases of the obtained fats; and (iv) 1H and 13C Nuclear Magnetic Resonance (NMR, 1D and 2D) spectroscopy to rapidly analyze fatty acid composition including regioisomeric distribution on the glycerol backbone. These last results open up the possibility of using NMR spectroscopy as an alternative to the chromatographic techniques routinely employed for the investigation of similar matrices. [ABSTRACT FROM AUTHOR]

The ionic liquid crystal 1-dodecyl-3-methylimidazolium tetrafluoroborate slightly doped with water is presented as a promising NMR alignment medium for the measurement of residual dipolar couplings for polar molecules dissolved therein. [ABSTRACT FROM AUTHOR]

Cannabis sativa is a herbaceous multiple-use species commonly employed to produce fiber, oil, and medicine. It is now becoming popular for the high nutritional properties of its seed oil and for the pharmacological activity of its cannabinoid fraction in inflorescences. The present study aims to apply nuclear magnetic resonance (NMR) spectroscopy to provide useful qualitative and quantitative information on the chemical composition of seed and flower Cannabis extracts obtained by ultra-sound-assisted extraction, and to evaluate NMR as an alternative to the official procedure for the quantification of cannabinoids. The estimation of the optimal ω-6/ω-3 ratio from the 1H NMR spectrum for the seed extracts of the Futura 75 variety and the quantitative results from the 1H and 13C NMR spectra for the inflorescence extracts of the Tiborszallasi and Kompolti varieties demonstrate that NMR technology represents a good alternative to classical chromatography, supplying sufficiently precise, sensitive, rapid, and informative data without any sample pre-treatment. In addition, different extraction procedures were tested and evaluated to compare the elaboration of spectral data with the principal component analysis (PCA) statistical method and the quantitative NMR results: the extracts obtained with higher polarity solvents (acetone or ethanol) were poor in psychotropic agents (THC < LOD) but had an appreciable percentage of both cannabinoids and triacylgliceroles (TAGs). These bioactive-rich extracts could be used in the food and pharmaceutical industries, opening new pathways for the production of functional foods and supplements. [ABSTRACT FROM AUTHOR]

Highlights: [•] We synthesise 3,4-DHPEA-EDA starting from natural demethyloleuropein. [•] Our biomimetic route exploited a low toxic Lewis acid hydrolysis followed by thermal decarboxylation. [•] The stereochemistry of decarboxylation step was evaluated by NMR analysis of the deuterated analogue. [•] We evaluated and compared the antioxidant capacity of 3,4-DHPEA-EDA to the others 3,4-DHPEA derivatives of VOO. [Copyright &y& Elsevier]

In this work, a sample of pure and certified bergamot essential oil (BEO) was extensively studied for the first time directly by NMR spectroscopy with the aim of investigating its metabolic composition, quantifying the main components of this complex natural matrix and simultaneously assessing whether the NMR technique is able to highlight possible frauds to which this high-cost product may be subjected. Eleven low molecular weight compounds have been identified by using 1D 1H and 13C-{1H} NMR experiments, 2D homo- and heteronuclear correlation NMR spectra, and 2D 1H DOSY experiments; the most abundant of them, i.e., about 90% of the sample analyzed, has been quantified by employing benzoic acid as an internal standard by 1H NMR spectrum. Moreover, since the commercial fraud of this precious oil is often due to the addition of less expensive oils, we have simulated a possible adulteration through the preparation of BEO samples to which different percentages of orange essential oil (OEO) were added. The results, obtained by combining the 1H NMR spectra collected on the adulterated samples and on pure BEO, with chemometric analysis, principal component analysis (PCA), indicate that it is possible to distinguish the sample of pure BEO from the adulterated ones and also, among them, to differentiate between the degrees of adulteration. [ABSTRACT FROM AUTHOR]

The first example of spontaneous self‐assembly of ionic octahedral Ir(III) complexes containing carboxylates counterions into luminescent ordered aqueous gel phases is reported. The gel phases formed at 2.5% w/w (“Ir‐Ci”:H20) are investigated by POM, 1H and 2H NMR and UV–vis spectroscopies, whereas a detailed structural analysis by WAXS, SAXS, and SANS experiments is performed for the acetate complex, in both anisotropic gel and isotropic phases. This comprehensive investigation shows that the complex with the shortest carboxylate self‐assembles into double string polyelectrolyte‐type supramolecular columns surrounded by the counterions, at low concentrations in the isotropic solution (1.0% w/w). Upon increasing concentration, these supramolecular columns grow one‐dimensionally, and eventually gelation occurs and birefringent textures begin to be observed by POM, resembling the textures developed by chromonic systems. The gelation occurs with the close packing of the supramolecular columns sheathed in their solvation shell into a 2D rectangular lattice. Furthermore, a significant enhancement of the luminescence quantum yield is observed for all the complexes in the gel phases with respect to the isolated molecule. [ABSTRACT FROM AUTHOR]

In the present work, Calabrian apple juices belonging to four different cultivars, Royal Gala, Pink Lady, Golden Delicious, and Fuji, were studied. One of the objectives of this work was the characterization of metabolites present in the food matrix and at the same time the possibility of using innovative methodologies based on membrane operations, such as ultrafiltration (UF) and nanofiltration (NF), to obtain from the squeezed apple juice, extracts rich in antioxidants. To improve the overall quality of the study and enhance the coverage of the metabolome two analytical tools were used: NMR and HPLC–UV-ESI–MS/MS. One- and two-dimensional multinuclear NMR spectra combined with chemometric analysis (PCA) were used to identify the metabolic profile of different juice varieties and variations in metabolic composition. On the basis of its higher content of phenolic compounds, the Golden Delicious variety was selected to carry out membrane filtration tests. Specifically, the fresh juice was clarified by UF and then concentrated by NF up to a volume reduction factor (VRF) of 3.3. Permeate and retentate fractions of both processes were analyzed by HPLC–UV and NMR in order to evaluate the membrane selectivity of the selected membranes towards target compounds. [ABSTRACT FROM AUTHOR]

Biphenylene and pyrene were dissolved in the nematic and smectic-A phases of the liquid crystal 4,4'-di-n-heptyl-azoxybenzene and the orientational order parameters of both solutes and solvent measured via proton and deuteron nuclear-magnetic-resonance spectroscopy. This new data set was then merged with the one previously obtained, formed by 4,4'-di-chloro-benzene and naphthalene as solutes in the same solvent, and the resulting overall data set analyzed with a statistical thermodynamic density-functional theory to provide positional-orientational distribution functions of the various solutes along with the smectic solvent's positional order parameters. [ABSTRACT FROM AUTHOR]

A comparison is made between the information which can be derived on structure, conformation and orientational order of the molecules in a nematic liquid crystal 4-pentyl-4'-cyanobiphenyl (5CB) from the NMR spectra of the deuterium atoms at natural abundance (NAD NMR), and the two-dimensional proton-detected 13C local field experiment (PDLF). The nine residual quadrupolar splittings, Δν k , obtained experimentally have been compared with quadrupolar tensors and a geometry and conformational potentials calculated by the DFT method B3LYP/6-311G**. The PDLF experiment yielded 42 scaled 13C-1H residual dipolar couplings, kD CiHj . The scaling factor, k, is determined experimentally by comparing unscaled and scaled residual dipolar couplings in a sample of fluorobenzene dissolved in a nematic liquid crystalline solvent. The corrected residual dipolar couplings, D CiHj , are used to investigate the structure and rotational potentials about each bond in the molecule. [ABSTRACT FROM AUTHOR]

Abstract: The present paper discusses the tendency of solution-cast Hyflon® AD membranes to retain unexpectedly high amounts of solvent, the possible reasons of this phenomenon and its effect on the membrane performance. Dense membranes, prepared by solution-casting and subsequent evaporation, showed large differences in their thermal, mechanical and transport properties, depending on the residual solvent content. Complete solvent removal required heating under vacuum up to well above the glass transition temperature. Analysis of the permeability, diffusion and solubility coefficients of six permanent gases showed that plasticization by the residual solvent reduces the permselectivity and increases the permeability. Data of solution-cast membranes after complete solvent removal compare well with those of a melt-pressed sample. Experimental gas transport parameters were confronted with simulated data, obtained by the Gusev–Suter Transition-State Theory (TST) method and by molecular dynamics (MD) simulations. 1H High Resolution Magic Angle Spinning Nuclear Magnetic Resonance spectroscopic analysis of the residual solvent in the polymer matrix did not reveal a particular interaction between polymer and solvent, suggesting that the solvent retention is mainly diffusion controlled. [Copyright &y& Elsevier]

For spin systems with N[sup I] and N[sup S] interacting nuclei of magnetogyric ratio γ[sub I] and γ[sub S] respectively, it is possible to obtain multiple quantum spectra characterized by changes in the magnetic numbers mX by N[sup I], (N[sup I]—1)…, 0 with X = I, S. The use of such heteronuclear MQ spectra as an aid in the automatic analysis of NMR spectra of both rigid and flexible molecules dissolved in liquid crystalline phases, is discussed. It has been found that when I = [sup 1]H and S = [sup 19]F, the decoupling efficiency of the standard multipulse sequences, developed and optimized for heteronuclear decoupling in isotropic liquids, depends on the spin system and also on the overall orientation of the molecule when orienting mesophases are involved. These facts impose limitations on the applicability of a procedure which, when the decoupled heteronuclear MQ spectrum is obtained, significantly reduces the computing requirements of the automated spectral analysis. [ABSTRACT FROM AUTHOR]

The use of NMR spectroscopy combined with chemometric analysis is proposed in this work as an alternative methodology to the traditional techniques of the agro-food industry to investigate the metabolic profile of Calabrian citrus juices and to evaluate changes on the composition and metabolic profile of the juices during the thermal concentration process. First, 23 low molecular weight compounds, present in freshly squeezed orange juice, were identified using 1D 1H and 13C-{1H} NMR experiments and 2D homo and heteronuclear NMR spectra. Later, the 1H NMR spectra of collected samples during the concentration processes were used, coupled with PCA, in order to follow the variations in the metabolic composition of the juices subjected to the thermal process. The study focused on three industrial processes, two concerning the thermal concentration of orange juices while the third concerning the mixed orange and clementine juice concentration. The results indicate that PCA analysis is able to discriminate among the samples coming from the three industrial processes according to the nature of initial fruit batches. Moreover, for each process, the metabolic profile remains unchanged, i.e. there is no degradation or appearance of new compounds, but the PCA data indicate a decrease in the concentration of volatile compounds during the thermal process. • 23 compounds were identified, in freshly orange juice, using 1D and 2D NMR spectra. • NMR and PCA combination allow quality control in juice thermal concentration process. • Samples successfully discriminated based on different initial batches fruits. • No degradation or appearance of new metabolites during industrial process. • PCA shows a decrease of the concentration of volatile compounds in concentrated juice. [ABSTRACT FROM AUTHOR]

Introduction: Renal dysfunction is a frequent complication in patients suffering from β-thalassemia major (β-TM). The aim of this study was to analyze the renal function and urine metabolomic profile of β-TM patients undergoing transfusions and deferasirox (DFX) therapy, in order to better characterize and shed light on the pathogenesis of renal disease in this setting. Methods and Subjects: 40 patients affected by β-TM treated with DFX and 35 age- and gender-matched healthy controls were enrolled in the study. Renal function was assessed. Glomerular filtration rate (GFR) was estimated with CKD-EPI and Schwartz formula for adults and children, respectively. Renal tubular function and maximal urine concentration ability were tested. Urine specimens were analyzed by nuclear magnetic resonance spectroscopy to identify the urinary metabolite profiles. Results: The study of renal function in β-TM patients revealed normal estimated (e)GFR mean values and the albumin-to-creatinine ratio was <30 mg/g. The analysis of tubular function showed normal basal plasma electrolyte levels; 60% of patients presented hypercalciuria and many subjects showed defective urine concentration. Several amino acids, N-methyl compounds, and organic acids were overexcreted in the urine of thalassemic patients compared with controls. Discussion: The major finding of this work is that β-TM patients and controls exhibit different concentrations of some metabolites in the urine. Early recognition of urinary abnormalities may be useful to detect and prevent kidney damage. [ABSTRACT FROM AUTHOR]

The photochromic compound 2,6-bis(2-hydroxybenzilidene)cyclohexanone (PC) has been dissolved in some selected liquid amphiphiles: dibutyl, tributyl, bis-2-ethylhexyl, tris-2-ethylhexyl phosphate and bis-2-ethylhexyl amine. The aim was to explore its photophysical properties when embedded in the novel chemical environment provided by the amphiphilic solvents. UV-Vis spectra revealed different features depending on the solvent thus highlighting specific solvent-solute interactions and different chemical environments. All the alkylphosphate-based systems were found to be unstable; slow (days) changes in the absorption features due to the slow change in populations of the various species present in solution. Interestingly, the dissolution of PC into bis-2-ethylhexyl amine leads to stable solutions most probably due to the basic character of the solvent stabilising as major specie chalcone forms. Fluorescence spectra suggested the equilibrium between two species with different absorption and fluorescence properties. [ABSTRACT FROM AUTHOR]

The three-dimensional structure and conformational equilibrium of flexible bioactive molecules in solution are of considerable importance in clarifying their role in chemical and biological activity, since their action takes place in a liquid medium. The use of residual dipolar couplings (RDCs) recently emerged as a promising and effective method to address this kind of investigation. In this brief review, the conformational analysis of several flexible non-steroidal anti-inflammatory drugs, belonging to the class of salicylates and a-arylpropionic acids (profens), is described using the RDCs measured in weakly aligning poly-γ-benzyl-L-glutamate solutions. By combining these experimental parameters, extracted by using different mono- and bi-dimensional nuclear magnetic resonance experiments, with the theoretical additive potential-direct probability description approach, accurate descriptions of the probability distributions have been obtained for all the drug molecules selected. [ABSTRACT FROM AUTHOR]

Two requirements of a porous filler for Mixed Matrix Membranes [MMMs] are a good adhesion to the polymer and the openness of its pores. The surface of SAPO-34 has been grafted with moieties containing amino groups, aromatic rings, and fluorinated chains, for a good adhesion to glassy polyimides, aromatic polymers and perfluoropolymers. The controlled excess of the modification agent – preferably trichlorosilanes – in hydrophobic solvents and the strict control of moisture in the reaction environment prevent the growth of thick layers of grafts around the crystals. XPS confirms the success of the derivatizations and indicates a homogeneous and thin coverage of the surface. The negligible reduction of the surface area suggests that the modification of the surface does not plug the micropores. The counter-intuitive faster adsorption of n -heptane in silicalite-1 after modification with bulky fluorinated grafts indicates the openness of the pores even for large molecules, and the reduction of the resistance to the transport of mass across the surface of the molecular sieves, thanks to the reduced amount of water adsorbed on the hydrophobic outer surface of the crystals. [ABSTRACT FROM AUTHOR]

Despite the potential versatility of Vitamin C as a ligand, only for few metal complexes does full characterization exist. Vitamin C metal complexes, indeed, are difficult to study experimentally because the ligand has multiple protonation and oxidation states, and the metal-ligand complexes are in general not as tight as one might expect and frequently resistant to crystallographic characterization. In most cases, coordination via one of the hypothesized modes is invoked, characterized by monodentate or bidentate coordination via the most acidic oxygen atoms, with the ligand singly or doubly deprotonated. In this study the ability of l-ascorbic acid to form complexes with Al3+ and Ni2+ ions under physiological conditions was investigated by using a combination of potentiometric measurements, ¹H NMR spectroscopy, and DFT computations in order to recognize the structural properties of the resulting complexes in aqueous solution. The comparison between the values of the free energies of complexation obtained by using DFT quantum chemical calculations and estimated from experimental stability constants according to the mass action law and by considering the involved equilibria allows to select structure and preferred coordination modes of formed complexes. The protonation constant of the free ligand was also determined using potentiometric data and its reproduction by using computational approaches was critically commented. [ABSTRACT FROM AUTHOR]

Detailing the conformational equilibria between global and local minimum energy structures of anti-inflammatory α-arylpropionic acids directly in solution is of the utmost importance for a better understanding of the structure-activity relationships, hence providing valuable clues for rational structure-based drug design studies. Here the conformational preferences of the widely used pharmaceutical ibuprofen were investigated in solution by NMR spectroscopy in weakly ordering phases. A thorough theoretical treatment of the anisotropic interactions that are relevant for NMR spectra led to a conformational model characterized by six pairs of symmetry-related conformers, in particular four couples of gauche structures, with a total probability of 93%, and 2 couples of trans structures, counting for the remaining 7%. [ABSTRACT FROM AUTHOR]

The reaction of [WOF 4 (MeCN)] with the diphosphines, Me 2 PCH 2 CH 2 PMe 2 or o-C 6 H 4 (PMe 2 ) 2 , in anhydrous Et 2 O produced high yields of [WOF 4 (diphosphine)], the X-ray crystal structures of which reveal seven-coordinate pentagonal bipyramidal molecules with axial O/F. In contrast, the reaction of [WOF 4 (MeCN)] and PMe 3 forms the six-coordinate [WOF 4 (PMe 3 )]. These unusual W(VI) complexes have been characterised by microanalysis, IR, 1 H, 19 F{ 1 H} and 31 P{ 1 H} NMR spectroscopy. The second-order 19 F{ 1 H} and 31 P{ 1 H} NMR spectra of the [WOF 4 (diphosphine)] have been analysed. Similar complexes do not form with the other o-phenylene-linked bidentate ligands, o-C 6 H 4 (PPh 2 ) 2 , o-C 6 H 4 (AsMe 2 ) 2 or o-C 6 H 4 (SMe) 2 . [ABSTRACT FROM AUTHOR]

Naproxen and flurbiprofen are among the most popular and widely used drugs for treating pain and inflammation and new different therapeutic uses are still being proposed. Their pharmacological activity comes from the specific binding to target proteins and is evidently driven by the spatial arrangement they adopt at the active sites. A detailed conformational elucidation analysis in solution able to probe equilibria between more possible conformers is then crucial for understanding and rationalizing their biological role and possibly for designing improved analogues. Here we combine NMR data obtained in weakly ordered media and suitable theoretical models to look for the energetically admissible conformers of these two anti-inflammatory drugs in a liquid medium. This approach leads to rather complex probability distributions characterized for both molecules by an equilibrium of different global and local minimum energy structures. [ABSTRACT FROM AUTHOR]

Heterogeneous bifuctional catalysts are multifunctional synthetic catalysts enabling efficient organic transformations by exploiting two opposite functionalities without mutual destruction. In this paper we report the first Er(III)-based metallorganic heterogeneous catalyst, synthesized by post-calcination MW-assisted grafting and modification of the natural aminoacid L-cysteine. The natural acid-base distance between sites was maintained to assure the cooperation. The applicability of this new bifunctional heterogeneous catalyst to C-C bond formation and the supposed mechanisms of action are discussed as well. [ABSTRACT FROM AUTHOR]

A correction related to the article "Publisher's Note: Rigid probe solutes in a smectic-A liquid crystal: An unconventional route to the latter's positional order parameters," that was published in the December 13, 2011 issue is presented.

Solid-state 19F-NMR spectroscopy is frequentlyusedto analyze the structure and dynamics of lipophilic drugs and peptidesembedded in biomembranes. The homonuclear dipolar couplings of trifluoromethyl(CF3) labels can provide valuable parameters such as orientationalconstraints and/or distances. To characterize the complex dipolarpatterns of multiple 19F spin interactions, three differentmodel compounds carrying two CF3groups in meta-position on a phenyl ring were incorporated in macroscopically alignedDMPC bilayers. The dipolar patterns obtained with the CPMG (Carr–Purcell–Meiboom–Gill)multipulse sequence were analyzed to yield simultaneously the intra-CF3and intergroup dipolar coupling values. The fluorine–fluorinedistances were predicted by a density functional calculation, andthe alignment of the labeled molecular segment could be determinedfrom these distances and the dipolar coupling values. The differentcompounds were found to align in the lipid bilayer according to theiramphiphilic properties, though with a weak anisotropic preferencethat is typical of solutes in liquid crystals. The residual dipolarcouplings were used to calculate Saupe order parameters. For the leastcomplex molecule, (CF3)2-BA, an orientationalprobability function for the solute in the lipid matrix could be derived.The overall description of how (CF3)2-BA isembedded in the bilayer was independently assessed by molecular dynamicssimulations, and compared in structural and dynamical terms with theresults of the NMR experiments. [ABSTRACT FROM AUTHOR]

The orientational order parameters of four aromatic solutes in nematic solvents, derived from proton dipolar couplings in NMR spectra, show a correlation with the dielectric anisotropy of the solvents. Explanation of the experimental behaviour is provided by a molecular theory based on the reaction field approximation. [ABSTRACT FROM AUTHOR]

The aim of this work has been to test the reliability of a simple relation connecting the order of probe molecules dissolved in binary nematic mixtures with that exhibited in each nematic component at the same reduced temperatures. In order to do this, a large amount of 1 H-LXNMR experiments at different temperatures has been performed, utilizing as solutes 1 ,4-difluorobenzene, 1,4-dichlorobenzene, 1,4-dibromobenzene and naphthalene in I52, EBBA and I52/EBBA mixtures at variable mixing percentages (50/50, 20/80 and 80/20 mol%). The results confirm that the orientations of the solutes in the mixtures can be predicted in a satisfactory way as a function of the mixing ratios, independently of the solutes and the temperatures. Finally, as a stimulation for future studies, a conjecture about the observed discrepancies is suggested. [ABSTRACT FROM AUTHOR]

Correction for ‘Conformational features of 4-(N)-squalenoyl-gemcitabine in solution: a combined NMR and molecular dynamics investigation’ by Ceruti Maurizio et al., New J. Chem., 2015, 39, 3484–3496. [ABSTRACT FROM AUTHOR]