Theoretical Study of Copper Squarate as a Promising Adsorbent for Small Gases Pollutants.

Copper squarate is a metal-organic framework with an oxo-carbonic anion organic linker and a doubly charged metal mode. Its structure features large channels that facilitate the adsorption of relatively small molecules. This study focuses on exploring the potential of adsorbing small pollutants, primarily greenhouse gases, with additional investigations conducted on larger pollutants. The objective is to comprehend the efficacy of this new material in single and multiple molecular adsorption processes using theoretical methods based on density functional theory. Furthermore, we find that the molecular adsorption energies range from 3.4 KJ∙mol-1 to 63.32 KJ∙mol-1 depending on the size and number of adsorbed molecules. An exception is noted with an unfavorable adsorption energy value of 47.94 KJ∙mol-1 for 4-nitrophenol. More importantly, we demonstrate that water exerts an inhibitory effect on the adsorption of these pollutants, distinguishing copper squarate as a rare MOF with hydrophilic properties. The Connolly surface was estimated to give a more accurate idea of the volume and surface accessibility of copper squarate. Finally, using Monte Carlo simulations, we present a study of adsorption isotherms for individual molecules and molecules mixed with water. Our results point out that copper squarate is an efficient adsorbent for small molecular pollutants and greenhouse gases.

Negative linear compressibility in nanoporous metal-organic frameworks rationalized by the empty channel structural mechanism.

Zinc squarate tetrahydrate (ZnC4O4·4H2O) and titanium oxalate trioxide dihydrate (Ti2(C2O4)O3·2H2O) are nanoporous metal-organic frameworks possessing empty channels in their crystal structures. The crystal structures and mechanical properties of these materials are studied using first principles solid-state methods based on Density Functional Theory. The results show that they exhibit the negative linear compressibility (NLC) and negative Poisson's ratio (NPR) phenomena. The absolute value of the negative compressibilities are significant and the range of pressure for which NLC effects are shown is very wide. The detailed study of the deformation of the crystal structures under pressure reveals that the NLC effect in these compounds can be rationalized using the empty channel structural mechanism. Under isotropic compression, the channels are elongated along the direction of minimum compressibiity, leading to NLC. Furthermore, under compression along the direction of minimum compressibity, the unit-cell volume increases leading to negative volumetric compressibilty. The effect of hydration on the NLC effect in titanium oxalate trioxide dihydrate is investigated by studying the parent compound titanium oxalate trioxide trihydrate (Ti2(C2O4)O3·3H2O). The NLC effect in this material is reduced due to the reinforcement of the walls of the structural channels.

Impact of Culinary Procedures on Nutritional and Technological Properties of Reduced-Fat Longanizas Formulated with Chia (Salvia hispanica L.) or Oat (Avena sativa L.) Emulsion Gel.

This paper evaluates how grilling, a traditional culinary procedure for fresh meat products, affects the composition and technological properties of healthy longanizas formulated with chia (Salvia hispanica L.) (C-RF) and oat (Avena sativa L.) (O-RF) emulsion gels (EGs) as animal fat replacers. The use of EGs, regardless of whether they contain chia or oat, improved longaniza performance during cooking as they lost less (p < 0.05) water and fat. The composition of cooked sausages was affected by their formulation, particularly those with chia EG (C-RF) which featured the highest polyunsaturated fatty acid content, mainly due to the higher level of α-linolenic fatty acid (1.09 g/100 g of product). Chia and oat EGs in C-RF and O-RF allow longanizas to be labeled with nutritional and health claims under European law. In general, this culinary procedure increases (p < 0.05) the lightness, lipid oxidation and texture parameters of all samples.

Crystal Structure, Infrared Spectrum and Elastic Anomalies in Tuperssuatsiaite.

The full crystal structure of the phyllosilicate mineral tuperssuatsiaite, including the positions of the hydrogen atoms in its unit cell, is determined for the first time by using first-principles solid-state methods. From the optimized structure, its infrared spectrum and elastic properties are determined. The computed infrared spectrum is in excellent agreement with the experimental spectrum recorded from a natural sample from Ilímaussaq alkaline complex (Greenland, Denmark). The elastic behavior of tuperssuatsiaite is found to be extremely anomalous and significant negative compressibilities are found. Tuperssuatsiaite exhibits the important negative linear compressibility phenomenon under small anisotropic pressures applied in a wide range of orientations of the applied strain and the very infrequent negative area compressibility phenomenon under external isotropic pressures in the range from 1.9 to 2.4 GPa. The anisotropic negative linear compressibility effect in tuperssuatsiaite is related to the increase of the unit cell along the direction perpendicular to the layers charactering its crystal structure. The isotropic negative area compressibility effect, however, is related to the increase of the unit cell dimensions along the directions parallel to the layers.

The magnesium uranyl tricarbonate octadecahydrate mineral, bayleyite: Periodic DFT study of its crystal structure, hydrogen bonding, mechanical properties and infrared spectrum.

Bayleyite is a highly hydrated uranyl tricarbonate mineral containing eighteen water molecules per formula unit. Due to this large water content, the correct description of its crystal structure is a great challenge for the first principles solid state methodology. In this work, the crystal structure, hydrogen bonding, mechanical properties and infrared spectrum of bayleyite, Mg2[UO2(CO3)3] · 18 H2O, have been investigated by means of Periodic Density Functional Theory methods using plane wave basis sets and pseudopotentials. The computed unit-cell parameters, interatomic distances, hydrogen bonding network geometry and the X-ray powder diffraction pattern of bayleyite reproduce successfully the experimental data, thus confirming the crystal structure determined from X-ray diffraction data. From the energy-optimized structure, the elastic properties and infrared spectrum have been determined using theoretical methods. The calculated elastic properties include the bulk modulus and its pressure derivatives, the Young and shear moduli, the Poisson ratio and the ductility, hardness and anisotropy indices. Bayleyite is shown to be a very isotropic ductile mineral possessing a bulk modulus of B ~28 GPa. The infrared spectrum of bayleyite is obtained experimentally from a natural mineral sample from the Jáchymov ore district, Czech Republic, and determined employing density functional perturbation theory. Since both spectra show a high degree of consistence, the bands in the observed spectrum are assigned using the theoretical methodology. The atomic vibrational motions localized in the uranyl tricarbonate units are described in detail, using appropriate normal coordinate analyses based on accurate vibrational computations, since the vibrational normal modes have not been hitherto studied for any uranyl tricarbonate mineral.

Full crystal structure, hydrogen bonding and spectroscopic, mechanical and thermodynamic properties of mineral uranopilite.

The determination of the full crystal structure of the uranyl sulfate mineral uranopilite, (UO2)6(SO4)O2(OH)6·14H2O, including the positions of the hydrogen atoms within the corresponding unit cell, has not been feasible to date due to the poor quality of its X-ray diffraction pattern. In this paper, the complete crystal structure of uranopilite is established for the first time by means of first principles solid-state calculations based in density functional theory employing a large plane wave basis set and pseudopotential functions. The computed unit-cell parameters and structural data for the non-hydrogen atoms are in excellent agreement with the available experimental data. The computed X-ray diffraction pattern is also in satisfactory agreement with the experimental pattern. The infrared spectrum of uranopilite is collected from a natural crystal specimen originating in Jáchymov (Czech Republic) and computed employing density functional perturbation theory. The theoretical and experimental vibrational spectra are highly consistent. Therefore, a full assignment of the bands in the experimental infrared spectrum is performed using a normal mode analysis of the first principles vibrational results. One overtone and six combination bands are recognized in the infrared spectrum. The elasticity tensor and phonon spectra of uranopilite are computed from the optimized crystal structure and used to analyze its mechanical stability, to obtain a rich set of elastic properties and to derive its fundamental thermodynamic properties as a function of temperature. Uranopilite is shown to have a large mechanical anisotropy and to exhibit the negative Poisson's ratio and negative linear compressibility phenomena. The calculated specific heat and entropy at 298.15 K are 179.6 and 209.0 J K-1 mol-1, respectively. The computed fundamental thermodynamic functions of uranopilite are employed to obtain its thermodynamic functions of formation in terms of the elements and the thermodynamic properties of a set of chemical reactions relating uranopilite with a representative group of secondary phases of spent nuclear fuel. From the reaction thermodynamic data, the relative stability of uranopilite with respect to these secondary phases is evaluated as a function of temperature and under different hydrogen peroxide concentrations. From the results, it follows that uranopilite has a very large thermodynamic stability in the presence of hydrogen peroxide. The high stability of uranopilite under this condition justify its early crystallization in the paragenetic sequence of secondary phases occurring when uranium dioxide is exposed to sulfur-rich solutions.

The layered uranyl silicate mineral uranophane-ß: crystal structure, mechanical properties, Raman spectrum and comparison with the α-polymorph.

The crystal structure, elastic properties and the Raman spectrum of the layered calcium uranyl silicate pentahydrate mineral uranophane-ß, Ca(UO2)2Si2O6(OH)2·5H2O, are studied by means of first-principles solid-state methods and compared with the corresponding information for the α polymorph. The availability of the energy optimized full crystal structure of uranophane-ß, including the positions of the hydrogen atoms, made possible the computation of its elastic properties and the Raman spectrum by using the theoretical methodology. An extended set of relevant mechanical data is reported. Uranophane-ß is shown to be a weak and ductile mineral and, consequenty, is mechanically very different from the α polymorph which is a hard and brittle material. Uranophane-ß exhibits the important negative Poisson's ratio (NPR) and negative linear compressibility (NLC) phenomena. The experimental Raman spectrum of uranophane-ß obtained from a natural mineral sample from pegmatite Perus, São Paulo, Brazil, is compared with the spectrum determined theoretically. Since both spectra are in very good agreement, the theoretical methods are employed to assign the Raman spectrum. Three weak bands of the experimental spectrum of this mineral, located at the wavenumbers 2302, 2128 and 2042 cm-1, are identified as combination bands. The Raman spectrum of uranophane-ß is also compared with that of the α polymorph. While they are rather similar, a detailed analysis reveals a significant number of differences. Finally, the relative thermodynamic stability of the α and ß polymorphs is evaluated. The α polymorph is more stable than the ß polymorph at zero pressure and temperature by -12.0 kJ mol-1.

Effect of different strategies of Lactobacillus plantarum incorporation in chorizo sausages.

BACKGROUND: Chorizo is a high-value Spanish-type dry fermented sausage, highly appreciated by consumers. In this kind of product, Lactobacillus plantarum plays an important role in the fermentation process and can also be considered as a probiotic. The impact of different strategies for incorporating probiotic L. plantarum into the physico-chemical, microbiological, and sensorial characteristics of chorizo sausages was studied. These strategies were: free cells (Cfc); alginate beads (Calg); water-in-oil emulsion (Cwo), and water-in-oil-in-water emulsion (Cwow). Proximate composition, weight loss, pH, aw , color, and microbiological behavior were evaluated during the ripening (20 days) of chorizo. RESULTS: The strategy of incorporating L. plantarum significantly affected the proximate composition, pH, and aw of sausages. However, the traditional red color of chorizo was maintained for all formulations. The incorporation of probiotics as free cells or encapsulated in alginate beads resulted in higher counts of lactic acid bacteria and L. plantarum, lower counts of Enterobacteriaceae, and in acceptable sensory scores. CONCLUSION: Overall, the quality of chorizo sausages was conditioned by the incorporation strategy, and the addition of probiotics in alginate beads (Calg) was the most effective strategy. © 2019 Society of Chemical Industry.

Chia (Salvia hispanica L.) a Promising Alternative for Conventional and Gelled Emulsions: Technological and Lipid Structural Characteristics.

Chia (Salvia hispanica L.) is an oilseed plant which contains proteins of high biological value and other healthy components with interesting technological properties. For these reasons, chia could be a promising option for the formation and stabilization of oil-in-water emulsions. The aim of this study is to evaluate the potential of chia protein (from chia flour) in the formation of emulsions. To that end, composition and technological and structural properties determined by infrared spectroscopy were investigated in conventional (EC) and gelled (EGC) emulsions with chia and compared with their corresponding soy protein emulsions with the same protein content [conventional (ES) or gelled (EGS)] used as reference. All emulsions containing chia had better fat and water binding properties than those elaborated with soy protein isolate (SPI). The color of the emulsions varied significantly depending on whether the emulsions were made with chia or SPI. EGS and EGC exhibited the greatest (p < 0.05) penetration force values, being EGC the firmest (p < 0.05). Depending on the type of emulsion, Attenuated Total Reflectance (ATR)-FTIR Spectroscopy revealed differences in their lipid structure and interaction in terms of lipid acyl chain mobility (order/disorder) and emulsion droplet size. These structural characteristics could be related to the textural behavior of emulsions.

Thermodynamic, Raman Spectroscopic, and UV-Visible Optical Characterization of the Deltic, Squaric, and Croconic Cyclic Oxocarbon Acids.

A precise and complete thermodynamic, Raman spectroscopic, and ultraviolet-visible (UV-vis) optical characterization of the deltic, squaric, and croconic cyclic oxocarbon acids is obtained using theoretical solid-state methods employing very demanding calculation parameters. The computed fundamental thermodynamic properties include the isobaric specific heat, the entropy, the enthalpy, and the Gibbs free energy as a function of temperature. The calculated specific heats at 298.15 K of the deltic, squaric, and croconic acids are 89.7, 111.2, and 133.2 J mol-1 K-1, respectively, and the corresponding entropies are 98.3, 117.3, and 136.5 J mol-1 K-1. The only value of these properties known from experimental measurements is the specific heat of the squaric acid, which differs from the computed value at 315 K by about 4.9%. The calculated values of the thermodynamic properties are then used to determine the thermodynamic properties of formation of these materials in terms of the elements. As an application of the calculated thermodynamic properties of formation, the Gibbs free energies of reaction and associated reaction constants are evaluated for the reactions of thermal decomposition and complete combustion of the squaric and croconic acids and the reaction of interconversion between them. The only available experimental values of these properties, namely, the enthalpies of combustion of squaric and croconic acids at room temperature, are reproduced theoretically with high accuracy. The Raman spectra of these materials are also computed using density functional perturbation theory. The analysis of the theoretical Raman spectra of these materials points out to significant differences with respect to their usual empirical assignment. Therefore, the Raman spectra of these materials are fully reassigned. Finally, the ultraviolet-visible (UV-vis) optical properties of the deltic, squaric, and croconic acids are computed. The UV-vis absorption spectrum of the croconic acid in the spectral region 225-425 nm and the UV absorption spectrum of the squaric acid in the region 200-350 nm, which had previously been measured experimentally, are well reproduced. The corresponding spectrum for the deltic acid and the reflectivity, optical conductivity, dielectric, refractive index, and loss optical functions of the three materials, which had never been published as far as we know, are reported as a function of the wavelength of incident radiation in the range 200-750 nm. The origin of the peaks in the absorption spectra, which had not been analyzed so far, is unveiled here by examining the interband electronic transitions in these materials.

Negative linear compressibility in uranyl squarate monohydrate.

The mechanical properties of the uranyl squarate monohydrate material, [Formula: see text], were studied using theoretical solid-state methods based in density functional theory employing plane waves and pseudopotentials. Very demanding calculation parameters were utilized in order to obtain a realistic description of the mechanical behavior of this material. Since the determination of the positions of the hydrogen atoms in the unit cell of uranyl squarate monohydrate was not possible from x-ray diffraction data by structure refinement, they were fully optimized theoretically. The computed lattice parameters, bond distances, angles, and x-ray powder diffraction patterns of this material were in very good agreement with the experimental data. This material was found to be mechanically and dynamically stable since the corresponding stability conditions were satisfied. The values of the bulk modulus and its pressure derivatives, shear and Young moduli, Poisson ratio, ductility, hardness, and mechanical anisotropy indices of this material were reported. Furthermore, this study showed that this material exhibits the important negative Poisson ratio (NPR) and negative linear compressibility (NLC) phenomena. Uranyl squarate monohydrate is a very anisotropic brittle material characterized by a bulk modulus of ~33 GPa, which shows a minimum value of the NPR of the order of -0.5. Besides, this material displays NLC values for a limited range of positive pressures, from 0.025 GPa to 0.094 GPa, applied along the direction of minimum negative Poisson ratio. The analysis of the crystal structure as a function of pressure demonstrates that the mechanism of NLC of this material is associated to the change in shape of the uranyl pentagonal bipyramids and unrelated to the wine-rack structural mechanism commonly used to rationalize this phenomenon.

Coagulation, Thrombogenesis, and Insulin Resistance Markers in Increased-Cardiovascular-Risk Subjects Consuming Improved-Fat Meat Products.

OBJECTIVES: Cardiovascular disease (CVD) risk is prevalent in high-meat-product consumers. The effect of consuming lipid-improved pâtés/frankfurters on plasma low-density lipoprotein (LDL)-cholesterol, thromboxane A2 (as TXB2), prostacyclin I2 (as 6-keto-PGF1α), activated partial thromboplastin time, fibrinogen, antithrombin, and insulin-resistance/sensitivity markers in volunteers at high CVD risk was studied. SUBJECTS/METHODS: Eighteen male volunteers enrolled in a blind crossover-controlled study consumed improved products during three 4-week periods: reduced fat (RF), n-3-enriched-RF (n-3RF), and normal fat (NF), separated by 4-week washouts. RESULTS: Fibrinogen and 6-keto-PG1α decreased (p < 0.05) following the RF period; LDL-cholesterol, TXB2, and 6-keto-PGF1α decreased (p < 0.05) after the n-3RF-period, while LDL-cholesterol, fibrinogen, TXB2, insulin, and Homostatic Model Assessment-insulin resistance (HOMA-IR) increased (at least p < 0.05) and QUICKI (Quantitative Insulin Sensitivity Check Index) decreased (p < 0.05) during the NF period. The rates of changes of fibrinogen, TXB2, 6-keto-PGF1α, and HOMA-IR differ between groups (repeated-measures test p < 0.05). Fibrinogen, insulin, and HOMA-IR differed significantly (p < 0.05) between RF and n-3RF period versus NF period, while that of TXB2 and 6-keto-PGF1α differed between n-3RF and NF periods (p < 0.05). CONCLUSIONS: The consumption of n-3RF meat products, followed by RF ones, partially reduced thrombogenesis, coagulation, and insulin-resistance markers. Thus, the inclusion of lipid-improved pâtés/frankfurters might be recommended into dietary strategies in at-CVD-risk volunteers.

Mechanical properties of anhydrous oxalic acid and oxalic acid dihydrate.

The mechanical properties of oxalic acid dihydrate and anhydrous oxalic acid (α and ß polymorphic forms) were obtained by using rigorous theoretical solid-state methods based on density functional theory using plane waves and pseudopotentials. The calculated crystal structures and X-ray powder diffraction patterns of these materials were found to be in excellent agreement with the experimental information. Since the calculated elasticity matrices fullfilled the Born stability conditions, the corresponding crystal structures were found to be mechanically stable. A large number of relevant mechanical properties including the values of the bulk moduli and their pressure derivatives, shear and Young moduli, Poisson ratios, ductility and hardness indices, and mechanical anisotropy values of these materials were reported. The three forms of oxalic acid are highly anisotropic ductile materials having low hardness and bulk moduli. The three materials are shown to display small negative Poisson ratios (NPR) and to exhibit the phenomenon of negative linear compressibility (NLC) for applied pressures along the direction of the minimum Poisson ratio. In addition, they undergo pressure induced phase transitions for relatively small applied pressures. The analysis of the crystal structures of these materials as a function of pressure demonstrates that the mechanism of NLC of these materials is unrelated to the wine-rack structural mechanism commonly used to rationalize this phenomenon. The three forms of oxalic acid considered in this work are molecular crystals whose structures are characterized by structural elements which are not directly bonded but held together by weak van der Waals forces. The weak bonding between these elements is able to accommodate the structural variations originating from the application of pressure, but the resulting structural deformations appear to be counterintuitive and lead to the anomalous mechanical behavior of these materials.

Crystal structure, hydrogen bonding, mechanical properties and Raman spectrum of the lead uranyl silicate monohydrate mineral kasolite.

The crystal structure, hydrogen bonding, mechanical properties and Raman spectrum of the lead uranyl silicate monohydrate mineral kasolite, Pb(UO2)(SiO4)·H2O, are investigated by means of first-principles solid-state methods based on density functional theory using plane waves and pseudopotentials. The computed unit cell parameters, bond lengths and angles and X-ray powder pattern of kasolite are found to be in very good agreement with their experimental counterparts. The calculated hydrogen atom positions and associated hydrogen bond structure in the unit cell of kasolite confirmed the hydrogen bond scheme previously determined from X-ray diffraction data. The kasolite crystal structure is formed from uranyl silicate layers having the uranophane sheet anion-topology. The lead ions and water molecules are located in the interlayer space. Water molecules belong to the coordination structure of lead interlayer ions and reinforce the structure by hydrogen bonding between the uranyl silicate sheets. The hydrogen bonding in kasolite is strong and dual, that is, the water molecules are distributed in pairs, held together by two symmetrically related hydrogen bonds, one being directed from the first water molecule to the second one and the other from the second water molecule to the first one. As a result of the full structure determination of kasolite, the determination of its mechanical properties and Raman spectrum becomes possible using theoretical methods. The mechanical properties and mechanical stability of the structure of kasolite are studied using the finite deformation technique. The bulk modulus and its pressure derivatives, the Young and shear moduli, the Poisson ratio and the ductility, hardness and anisotropy indices are reported. Kasolite is a hard and brittle mineral possessing a large bulk modulus of the order of B ∼ 71 GPa. The structure is mechanically stable and very isotropic. The large mechanical isotropy of the structure is unexpected since layered structures are commonly very anisotropic and results from the strong dual hydrogen bonding among the uranyl silicate sheets. The experimental Raman spectrum of kasolite is recorded from a natural mineral sample from the Jánská vein, Príbram base metal ore district, Czech Republic, and determined by using density functional perturbation theory. The agreement is excellent and, therefore, the theoretical calculations are employed to assign the experimental spectrum. Besides, the theoretical results are used to guide the resolution into single components of the bands from the experimental spectrum. A large number of kasolite Raman bands are reassigned. Three bands of the experimental spectrum located at the wavenumbers 1015, 977 and 813 cm-1, are identified as combination bands.

Structural, mechanical, spectroscopic and thermodynamic characterization of the copper-uranyl tetrahydroxide mineral vandenbrandeite.

The full crystal structure of the copper-uranyl tetrahydroxide mineral (vandenbrandeite), including the positions of the hydrogen atoms, is established by the first time from X-ray diffraction data taken from a natural crystal sample from the Musonoi Mine, Katanga Province, Democratic Republic of Congo. The structure is verified using first-principles solid-state methods. From the optimized structure, the mechanical and dynamical stability of vandenbrandeite is studied and a rich set of mechanical properties are determined. The Raman spectrum is recorded from the natural sample and determined theoretically. Since both spectra have a high-degree of consistence, all spectral bands are rigorously assigned using a theoretical normal-coordinate analysis. Two bands in the Raman spectra, located at 2327 and 1604 cm-1, are recognized as overtones and a band at 1554 cm-1 is identified as a combination band. The fundamental thermodynamic functions of vandenbrandeite are computed as a function of temperature using phonon calculations. These properties, unknown so far, are key-parameters for the performance-assessment of geological repositories for storage of radioactive nuclear waste and for understanding the paragenetic sequence of minerals arising from the corrosion of uranium deposits. The thermodynamic functions are used here to determine the thermodynamic properties of formation of vandenbrandeite in terms of the elements and the Gibbs free-energies and reaction constants for a series of reactions involving vandenbrandeite and a representative subset of the most important secondary phases of spent nuclear fuel. Finally, from the thermodynamic data of these reactions, the relative stability of vandenbrandeite with respect to these phases as a function of temperature and in the presence of hydrogen peroxide is evaluated. Vandenbrandeite is shown to be highly stable under the simultaneous presence of water and hydrogen peroxide.

Emulsion gels containing n-3 fatty acids and condensed tannins designed as functional fat replacers.

The purpose of this study was to ascertain the potential of several food-grade emulsion (O/W) gels (GEs) for use as healthier fat replacers. The emulsions, formulated with a lipid phase rich in n-3 fatty acids and different emulsifiers (sodium caseinate, SC; whey protein isolate, WPI and isolated soy protein, ISP), were cold gelled after adding a natural extract rich in condensed tannins (CT). The GEs were characterized and their oxidative stability evaluated during storage (4 °C). All GEs formulated presented a solid-like structure showing generally excellent emulsion stability, which improved in GEs with the addition of CT. Non-extractable proanthocyanidins (NEPA) were the main source of polyphenol in samples enriched with CTs. The antioxidant activity of the systems was not affected by the use of different proteins as emulsifiers, but it was improved in GEs containing CT. The oxidation values recorded in the GE systems can generally be regarded as low even considering their enrichment with unsaturated fatty acids, which thus assures their suitability for use as fat replacers.

Quality Assessment of Fresh Meat from Several Species Based on Free Amino Acid and Biogenic Amine Contents during Chilled Storage.

This paper studies the changes that occur in free amino acid and biogenic amine contents of raw meats (beef, pork, lamb, chicken and turkey) during storage (2 °C, 10 days). The meat cuts samples were harvested from a retail outlet (without getting information on the animals involved) as the following: Beef leg (four muscles), pork leg (five muscles), lamb leg (seven muscles), turkey leg (four muscles), and chicken breast (one muscle). Meat composition varied according to meat types. In general, pH, microbiology counts, biogenic amine (BA), and free amino acid (FAA) contents were also affected by meat types and storage time (p < 0.05). Chicken and turkey presented the highest levels (p < 0.05) of FAAs. Total free amino acids (TFAA) were higher (p < 0.05) in white meats than in red ones. The behavior pattern, of the total free amino acids precursors (TFAAP) of Bas, was saw-toothed, mainly in chicken and turkey meat during storage, which limits their use as quality indexes. Spermidine and spermine contents were initially different among the meats. Putrescine was the most prevalent BA (p < 0.05) irrespective of species. In general, chicken and turkey contained the highest (p < 0.05) levels of BAs, and TFAAP of BAs. In terms of the biogenic amine index (BAI), the quality of chicken was the worst while beef meat was the only sample whose quality remained acceptable through the study. This BAI seems to be more suitable as a quality index for white meat freshness than for red meat, especially for beef.

Periodic Density Functional Theory Study of the Structure, Raman Spectrum, and Mechanical Properties of Schoepite Mineral.

The structure and Raman spectrum of schoepite mineral, [(UO2)8O2(OH)12]·12H2O, was studied by means of theoretical calculations. The computations were carried out by using density functional theory with plane waves and pseudopotentials. A norm-conserving pseudopotential specific for the U atom developed in a previous work was employed. Because it was not possible to locate H atoms directly from X-ray diffraction (XRD) data by structure refinement in previous experimental studies, all of the positions of the H atoms in the full unit cell were determined theoretically. The structural results, including the lattice parameters, bond lengths, bond angles, and powder XRD pattern, were found to be in good agreement with their experimental counterparts. However, the calculations performed using the unit cell designed by Ostanin and Zeller in 2007, involving half of the atoms of the full unit cell, led to significant errors in the computed powder XRD pattern. Furthermore, Ostanin and Zeller's unit cell contains hydronium ions, H3O+, which are incompatible with the experimental information. Therefore, while the use of this schoepite model may be a very useful approximation requiring a much smaller amount of computational effort, the full unit cell should be used to study this mineral accurately. The Raman spectrum was also computed by means of density functional perturbation theory and compared with the experimental spectrum. The results were also in agreement with the experimental data. A normal-mode analysis of the theoretical spectra was performed to assign the main bands of the Raman spectrum. This assignment significantly improved the current empirical assignment of the bands of the Raman spectrum of schoepite mineral. In addition, the equation of state and elastic properties of this mineral were determined. The crystal structure of schoepite was found to be stable mechanically and dynamically. Schoepite can be described as a brittle material exhibiting small anisotropy and large compressibility in the direction perpendicular to the layers, which characterize its structure. The calculated bulk modulus, B, was ∼35 GPa.

Becquerelite mineral phase: crystal structure and thermodynamic and mechanical stability by using periodic DFT.

The structure, thermodynamic and mechanical properties of becquerelite mineral, Ca(UO2)6O4(OH)6·8H2O, were studied by means of theoretical solid-state calculations based on density functional theory using plane waves and pseudopotentials. The positions of the hydrogen atoms in the unit cell of becquerelite mineral were optimized theoretically since it was not possible to determine them from X-ray diffraction data by structure refinement. The structural results, including the lattice parameters, bond lengths and X-ray powder pattern, were found to be in excellent agreement with their experimental counterparts. The fundamental thermodynamic properties of becquerelite mineral, including specific heat, entropy, enthalpy and Gibbs free energy, were then computed by performing phonon calculations at the computed optimized structure. Since the experimental values of these properties are unknown, their values were predicted. The values obtained for the isobaric specific heat and entropy of becquerelite at the temperature of 298.15 K were 148.4 and 172.3 J K-1 mol-1, respectively. The computed thermodynamic properties were combined with those of the corresponding elements in order to obtain the enthalpy and Gibbs free energy of formation as a function of temperature. The availability of these thermodynamic properties of formation allowed to determine the enthalpies and free energies and associated reaction constants of a series of reactions involving becquerelite and other uranyl containing materials. Futhermore, knowledge of these properties permitted the study of the thermodynamic stability of becquerelite with respect to a rich set of secondary phases of spent nuclear fuel, including dehydrated schoepite, schoepite, metaschoepite, studtite, metastudtite, rutherfordine and soddyite under different conditions of temperature. Becquerelite is shown to be highly stable in the presence of hydrogen peroxide. It is the second most stable phase under intermediate hydrogen peroxide concentrations (after schoepite), and the fourth most stable phase under high hydrogen peroxide concentrations (after studtite, schoepite and metaschoepite). Finally, the equation of state and elastic properties of this mineral, unknown to date, were determined. The crystal structure of becquerelite was found to be stable mechanically and dynamically. Becquerelite can be described as a brittle material exhibiting large anisotropy and large compressibility in the direction perpendicular to the sheets characterizing the structure of this layered uranyl containing material. The dependence of the elastic properties of becquerelite with respect to the strain orientation is shown to be analogous to that of schoepite mineral. The calculated bulk modulus is also very similar to that of schoepite, B ∼ 31 GPa.

Implications of domestic food practices for the presence of bioactive components in meats with special reference to meat-based functional foods.

Although an essential component of the diet, the consumption of meat is in question. Meat is a major source of beneficial compounds but it also contains other substances with negative health implications. Functional foods, which are leading trends in the food industry, constitute an excellent opportunity for the meat sector to improve healthier meat options. Most studies on meat-based functional foods have focused mainly on the application of different strategies (animal production practices and meat transformation systems) to improve (increase/reduce) the presence of bioactive (healthy/unhealthy) compounds; these have led to the development of numerous products, many of them by the meat industry. However, like other foods, after purchase meats undergo certain processes before they are consumed, and these affect their composition. Although domestic handling practices can significantly alter the make-up of the marketed product in terms of healthy/unhealthy compounds, there are very few studies on their consequences. This article provides an overview of the influence of different domestic practices (from shopping to eating) habitually followed by consumers on the presence of, and consequently on the levels of exposure to, (healthy and unhealthy) food components associated with the consumption of meats, with special reference to meat-based functional foods.