Van der Waals density functional calculations of binding in molecular crystals

A recent paper [J. Chem. Phys. 132 (2010) 134705] illustrated the potential of the van der Waals density functional (vdW-DF) method [Phys. Rev. Lett. 92 (2004) 246401] for efficient first-principle accounts of structure and cohesion in molecular crystals. Since then, modifications of the original vdW-DF version (identified as vdW-DF1) have been proposed, and there is also a new version called vdW-DF2 [Phys. Rev. B 82 (2010) 081101(R)], within the vdW-DF framework. Here we investigate the performance and nature of the modifications and the new version for the binding of a set of simple molecular crystals: hexamine, dodecahedrane, C60, and graphite. These extended systems provide benchmarks for computational methods dealing with sparse matter. We show that a previously documented enhancement of non-local correlations of vdW-DF1 over an asymptotic atom-based account close to and a few Å beyond binding separation persists in vdW-DF2. The calculation and analysis of the binding in molecular crystals require appropriate computational tools. In this paper, we also present details on our real-space parallel implementation of the vdW-DF correlation and on the method used to generate asymptotic atom-based pair potentials based on vdW-DF.     

Assessment of the N-nitrosopiperidine formation risk from piperine and piperidine contained in spices used as meat product additives

The N-nitrosopiperidine (NPIP) formation in blends of spices and nitrite curing salt was investigated in relation with the piperine and piperidine contents in spices. Firstly, two analytical methods were developed. Piperine was extracted with dichloromethane by means of accelerated solvent extraction (ASE) and determined by high-performance liquid chromatography (HPLC)–diode array detector (λ = 343 nm). A selective hydroextraction of piperidine using ASE and its quantification by HPLC–ELSD was applied. Both methods were sufficiently sensitive and accurate (limit of detection, limit of quantification, and recovery: 0.28, 0.84 μg, and 98.9 ± 2.6 % for piperine, and 5.76, 17.45 μg, and 95.9 ± 2.9 % for piperidine, respectively). Secondly, both compounds were quantified in commercial samples (black and white pepper, paprika, chili pepper, allspice, and nutmeg). The maximum amount of piperine (21.12 mg g^?1) was found in pepper, while the other spices contained only traces. Piperidine was detected mainly in the pepper samples, whereby the highest concentration was found in the white pepper extract (11.42 mg g^?1). Thirdly, during the storage of spices blended with nitrite curing salt, the NPIP content was determined, using a gas chromatograph coupled with a thermal energy analyzer. Against our expectations, no NPIP formation was observed in the curing mixture which contained white pepper extract. This result remains in contrast with the white pepper mixture, in which the NPIP content significantly increased from not detected to 9.80 ± 0.41 ng g^?1 after the 2 months storage period. In conclusion, high amounts of piperine or piperidine in spices do not systematically result in the formation of NPIP, when blended with nitrite curing salt .     

Zur Synthese von Octahydrochinazolinonen und deren Reaktion mit Persäure

The Synthesis of Octahydroquinazolinones and their Reaction with Peracid By reaction of cyclohexanone-2-carboxamide with ammonia and aldehydes, octahydroquinazolinones 2a–f , and with Schiff bases octahydroquinazolinones 3a–c are formed. 2-Hydroxycyclohexanone-2-carboxamide forms with ammonia and butyraldehyde the hydroxyocta-hydroquinazolinone 4 . Compound 2e reacts with monoperoxiphthalic acid to the hydroxyoxaziridine 5e which reacts with alkali hydroxide to compound 6. 8 yields with peroxy acid the hydroperoxy epoxide 9 .     

Hysteretic moisture behavior of concrete: Modeling and analysis

Durability of reinforced concrete is crucial for civil and building infrastructures. Deterioration related to corrosion of the reinforcement can be caused by chloride diffusion or carbonation due to atmospheric CO₂ ingress. Chlorides and CO₂ transport coefficients are dependent on the saturation degree of the porous material. Thus, the durability of concrete elements submitted to cyclic atmospheric conditions could depend on the hysteretic moisture behavior of concrete. To assess this influence, an analytical model has been developed describing hysteretic moisture behavior based on the independent domain theory. This model is incorporated in a finite element code for coupled heat and mass transfer, allowing to calculate the concrete response to changing temperature and relative humidity conditions. A comparison is made between simulations using the hysteresis model and using either the main ad- or desorption curve. The results show that durability risks may be underestimated when omitting moisture hysteresis in the outer concrete layer.     

In Vitro Zinc Protoporphyrin IX Formation in Different Meat Sources Related to Potentially Important Intrinsic Parameters

For several years, researchers have studied the formation of zinc protoporphyrin IX in meat, as it is considered to be an important natural colouring agent in dry cured or fermented meat products in the absence of nitrite and/ or nitrate. Until now, however, mainly pork meat is used for these investigations. The goal of this research was to relate in vitro zinc protoporphyrin IX and protoporphyrin IX formation in eight meat sources (chicken, turkey, pork, lamb, beef, veal, horse and porcine liver) to eight intrinsic parameters using partial least squares regression (PLS) analysis. Significant differences in pH, initial metmyoglobin formation, metmyoglobin reduction ability, total heme, zinc chelatase activity, and total iron and zinc concentration between meat sources were found. Water activity, however, was not significantly different between meat sources. Liver tissue and horse meat showed the best ability to form zinc protoporphyrin IX. Formation of protoporphyrin IX was limited in all meat sources. PLS analysis revealed that mainly zinc chelatase activity, followed by total heme, total iron and zinc content, were predominant intrinsic parameters to explain variations in zinc protoporphyrin IX formation. These findings could be important for meat industry in order to establish the production of red coloured nitrite-free meat products.     

A high-repetition rate scheme for synchrotron-based picosecond laser pump/x-ray probe experiments on chemical and biological systems in solution

We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of the storage ring allows exploitation of up to two orders of magnitude more x-ray photons than in previous schemes based on the use of kHz lasers. Consequently, we demonstrate an order of magnitude increase in the signal-to-noise of time-resolved XAS of molecular systems in solution. This makes it possible to investigate highly dilute samples at concentrations approaching physiological conditions for biological systems. The simplicity and compactness of the scheme allows for straightforward implementation at any synchrotron beamline and for a wide range of x-ray probe techniques, such as time-resolved diffraction or x-ray emission studies.     

Hydrogen storage in amine boranes: Ionic liquid supported thermal dehydrogenation of ethylene diamine bisborane

A variety of ionic liquids has been tested for its catalytic effect on the dehydrogenation of ethylene diamine bisborane (EDB). The catalytic activity of ionic liquids, such as 1-butyl-2,3-dimethylimidazolium chloride ([BMMIM]Cl), 1-butyl-2,3-dimethylimidazolium acetate ([BMMIM][OAc]), 1-butyl-3-methylimidazolium acetate ([BMIM][OAc]) and 1-butyl-3-methylimidazolium methylsulfonate ([BMIM][OMs]) is compared and the mixture [BMMIM]Cl/EDB was investigated. This system is able to deliver about 6.5 wt% of hydrogen at 140 °C competing with conventional hydrogen storage pressure tanks. The correlation between polarity of the ILs and hydrogen yield was investigated and the suitability for hydrogen storage systems is evaluated and discussed.     

Gut Microbiome Analysis for Personalized Nutrition: The State of Science

Whereas most concepts of personalized nutrition (PN) in the past, included genotyping, recent years have brought new approaches that include microbiome analysis to optimize recommendations for diet and lifestyle changes. The new approach, offered by companies, that microbiome analysis provides a real benefit to either more concise recommendations or for increased compliance to PN, is largely lacking scientific validation. Although the microbiome field shows enormous proliferation, it has some major flaws that make its use in the public health domain currently critical. Starting with the quality and representative character of the stool samples, its processing and analysis as well as assembly of metagenome data and the interpretation. Moreover, there is still no consensus of what constitutes a “normal/healthy” microbiome, nor what features characterize a dysbiotic microbiome. And, based on hundreds of individual parameters and environmental factors, the intestinal microbiome shows a huge variability and consequently changing one factor—such as food intake—is likely to have a limited impact in achieving optimized health. The present review intends to summarize the state of consolidated knowledge on human gut microbiome in the context of diet and disease, its key features, and its influencing factors as well as its “add-on” quality for PN offers.