Multivariate process trajectories for molecular description of MF thermal curing and correlation with hydrolytic stability

During curing of thermosetting resins the technologically relevant properties of binders and coatings develop. However, curing is difficult to monitor due to the multitude of chemical and physical processes taking place. Precise prediction of specific technological properties based on molecular properties is very difficult. In this study, the potential of principal component analysis (PCA) and principal component regression (PCR) in the analysis of Fourier transform infrared (FTIR) spectra is demonstrated using the example of melamine-formaldehyde (MF) resin curing in solid state. FTIR/PCA-based reaction trajectories are used to visualize the influence of temperature on isothermal cure. An FTIR/PCR model for predicting the hydrolysis resistance of cured MF resin from their spectral fingerprints is presented which illustrates the advantages of FTIR/PCR compared to the combination differential scanning calorimetry/isoconversional kinetic analysis. The presented methodology is transferable to the curing reactions of any thermosetting resin and can be applied to model other technologically relevant final properties as well.     

Fourier transform ion cyclotron resonance mass spectrometry at the true cyclotron frequency

Ion cyclotron resonance (ICR) cells provide stability and coherence of ion oscillations in crossed electric and magnetic fields over extended periods of time. Using the Fourier transform enables precise measurements of ion oscillation frequencies. These precisely measured frequencies are converted into highly accurate mass-to-charge ratios of the analyte ions by calibration procedures. In terms of resolution and mass accuracy, Fourier transform ICR mass spectrometry (FT-ICR MS) offers the highest performance of any MS technology. This is reflected in its wide range of applications. However, in the most challenging MS application, for example, imaging, enhancements in the mass accuracy of fluctuating ion fluxes are required to continue advancing the field. One approach is to shift the ion signal power into the peak corresponding to the true cyclotron frequency instead of the reduced cyclotron frequency peak. The benefits of measuring the true cyclotron frequency include increased tolerance to electric fields within the ICR cell, which enhances frequency measurement precision. As a result, many attempts to implement this mode of FT-ICR MS operation have occurred. Examples of true cyclotron frequency measurements include detection of magnetron inter-harmonics of the reduced cyclotron frequency (i.e., the sidebands), trapping field-free (i.e., screened) ICR cells, and hyperbolic ICR cells with quadrupolar ion detection. More recently, ICR cells with spatially distributed ion clouds have demonstrated attractive performance characteristics for true cyclotron frequency ion detection. Here, we review the corresponding developments in FT-ICR MS over the past 40 years.     

Toluene degradation by a water/silicone oil mixture for the design of two phase partitioning bioreactors

Toluene degradation performances were studied in a 10 L Two-Phase Partitioning Bioreactor (TPPB).The liquid phase consisted of a mixture of water and PDMS 50 (PolyDiMethylSiloxane,i.e.silicone oil,viscosity of 46 maa·s) in the volume ratio of 75％/25％.Two series of experiments were carried out:in the first,the reactor was sequentially supplied with toluene whereas in the second,toluene was continuously supplied.Activated sludge from the wastewater treatment plant of Beaurade (Rennes,France) was used at an initial concentration of 0.5 dry mass g· (mixture L)-1.The elimination capacity (EC) was investigated as well as the change in biomass concentration over time.Toluene biodegradation was very efficient (removal efficiency,RE =100％) for toluene flows ranging from 0.2 to 1.2 ml· h-1,corresponding to elimination capacities of up to 104 g· m-3· h-1.For a toluene flow of 1.2 ml·h-1,the biomass concentration measured at the end of the experiment was 4.7 dry mass g.(mixture L)-1.The oxygen concentration in the liquid phase was clearly not a limiting factor in these operating conditions.Based on these results,an extrapolation leading to the design of a large-scale pilot TPPB can now be considered to study toluene degradation performances in industrial conditions.     

Improved biocomposite development of poly(vinyl alcohol) and hydroxyapatite for tissue engineering scaffold fabrication using selective laser sintering

In scaffold guided tissue engineering (TE), temporary three-dimensional scaffolds are essential to guide and support cell proliferation. Selective Laser Sintering (SLS) is studied for the development of such scaffolds by eliminating pore spatial control problems faced in conventional scaffolds fabrication methods. SLS offers good user control over the scaffold’s microstructures by adjusting its main processing parameters, namely the laser power, scan speed and part bed temperature. This research focuses on the improvements in the fabrication of TE scaffolds using SLS with powder biomaterials, namely hydroxyapatite (HA) and poly(vinyl alcohol) (PVA). Grinding of as-received PVA powder to varying particle sizes and two methods of mixing are investigated as the preparation process to determine a better mixing method that would enhance the mixture homogeneity. Suitable sintering conditions for the improved biocomposite are then achieved by varying the important process parameters such as laser power, scan speed and part bed temperature. SLS fabricated samples are characterized using Fourier Transform Infrared Spectrometer (FTIR) and Scanning Electron Microscope (SEM). FTIR results show that the grinding and sintering processes neither compromise the chemical composition of the PVA nor cause undue degradation. Visual analysis of the grinding, powder mixing and sintering effect are carried out with SEM. The SEM observations show improvements in the sintering effects. The favorable outcome ascertains PVA/HA biocomposite as a suitable material to be processed by SLS for TE scaffolds.     

Betontechnologie und Dauerhaftigkeit von glasfaserbewehrten Bauteilen

Concrete Technology and Durability of Glass Fibre Reinforced Structures The durability of glass fibre reinforced concrete structures is significantly determined by matrix composition, the type of glass and its surface quality including necessary coatings. In the paper an experimental overview is given concerning special material influences and their interaction in the composite.     

Salt-Sensitive Hypertension in GR+/− Rats Is Accompanied with Dysregulation in Adrenal Soluble Epoxide Hydrolase and Polyunsaturated Fatty Acid Pathways

Mutations within the glucocorticoid receptor (GR) gene locus lead to glucocorticoid resistance which is characterized by several clinical symptoms such as adrenal gland hyperplasia and salt-sensitive hypertension, although the underlying mechanisms are still unknown. We studied GR haploinsufficient (GR^+/−) Sprague Dawley rats which, on a standard diet, showed significantly increased plasma aldosterone and corticosterone levels and an adrenocortex hyperplasia accompanied by a normal systolic blood pressure. Following a high salt diet, these rats developed salt-sensitive hypertension and maintained elevated enzyme-soluble epoxide hydrolase (sEH) in adrenal glands, while sEH was significantly decreased in wild-type rats. Furthermore, GR^+/− rats showed dysregulation of the equilibrated linoleic and arachidonic acid pathways, with a significant increase of less active metabolites such as 8,9-DiHETrE. In Sprague Dawley rats, GR haploinsufficiency induced steroid disturbances, which provoked hypertension only in combination with high salt intake, which was accompanied by disturbances in sEH and fatty acid metabolism. Our results suggest that sEH inhibition could be a potential target to treat hypertension in patients with GR haploinsufficiency.     

Numerical analysis of moisture vapor diffusion in asphalt mixtures using digital images

The presence of moisture in asphalt mixtures is detrimental to their performance, e.g., softening the asphalt binder and weakening the aggregate-binder bond. One of the mechanisms of moisture transport, and the focus of this study, is molecular diffusion. Moisture diffusion occurs in response to a concentration gradient. The objective of this study was to estimate the diffusion coefficient of moisture vapor in asphalt mixtures by using finite element (FE) and finite difference (FD) numerical algorithms that employ digital images to discretize the composite. X-ray computed tomography was used to characterize the microstructure of laboratory-prepared specimens and provide the required three-dimensional digital images, which were segmented into three phases: air voids, a mixture of asphalt binder and the fine aggregate fraction, and coarse aggregates. Individual diffusion coefficients were assigned to each phase and the effective diffusion coefficient for the composite was computed using the numerical algorithms. The outcome was compared against experimental values. The effective diffusion coefficient for the asphalt mixtures obtained using the FD method showed closer agreement with the experimental data, while the FE results overestimated the experimental measurements in all cases.     

Pasta with Unripe Banana Flour: Physical, Texture, and Preference Study

ABSTRACT:  Banana is a starchy food that contains a high proportion of undigestible compounds such as resistant starch and nonstarch polysaccharides. Products with low glycemic response such as pasta are considered favorable to health. The objective of this study was to use unripe banana flour to make spaghetti with low-carbohydrates digestibility and evaluate its physical and texture characteristics, as well as consumer preference. Formulations with 100% durum wheat semolina (control) and formulations with 3 semolina: banana flour ratios (85: 15, 70: 30, and 55: 45) were prepared for spaghetti processing. The use of banana flour decreased the lightness and diameter of cooked spaghetti, and increased the water absorption of the product. Hardness and elasticity of spaghetti were not affected by banana flour, but adhesiveness and chewiness increased as the banana flour level in the blend rose. Spaghettis prepared in the laboratory (control and those with banana flour) did not show differences in preference by consumers. In general, the preference of spaghettis with different banana flour level was similar. The addition of a source of undigestible carbohydrates (banana flour) to spaghetti is possible without affecting the consumer preference.     

Discovering a junction tree behind a Markov network by a greedy algorithm

In our paper (Annals of Operations Research, 193:71–90, 2012) we introduced a special kind of k?1-width junction tree, called k-th order cherry tree in order to approximate a joint probability distribution. The approximation is the best if the Kullback–Leibler divergence between the true joint probability distribution and the approximating one is minimal. Finding the best approximating k?1-width junction tree probability distribution is NP-complete if 2<k<d?1, where d is the dimension of the joint probability distribution (see Karger and Srebro in 12th ACM-SIAM Symposium on Discrete Algorithms (SODA), 2001, Malvestuto in Kybernetika 48:825–844, 2012). In Broad Research in Artificial Intelligence and Neuroscience (BRAIN), special issue on complexity in sciences and artificial intelligence, pp. 40–45, 2010 we also proved that the best approximating k?1-width junction tree probability distribution can be embedded into a k-th order cherry tree probability distribution. We introduce here a greedy algorithm resulting very good approximations in reasonable computing time. We prove then that if the Markov network which encodes the conditional independences of the multivariate probability distribution fulfills some requirements then our greedy algorithm is able to find the true probability distribution. Our algorithm uses just the k-th order marginal probability distributions as input. We compare the results of the greedy algorithm proposed in this paper with the greedy algorithm proposed by Malvestuto (IEEE Trans. Syst. Man Cybern. 21:1287–1294, 1991).