Fluidized and vibrofluidized shallow beds of fresh leaves

The fluid dynamics behavior of shallow fluidized and vibrofluidized beds operating with fresh leaves was investigated with the aim of exploring drying applications in a modified conveyor belt (MCB) system,which may be operated in a fixedor fluidized-bed mode.Leaves of the specimens Duranta repens,Schinus molle,Coleus barbatus,Buxus sempervirens,and Bougainvillea spectabilis were tested with a range of sphericities from 0.063 to 0.213,bulk densities from 0.038 to 0.251 g/cm 3,apparent densities from 0.52 to ...     

Probability on Graphs: Random Processes on Graphs and Lattices,by G. Grimmett

The 12 member states of the European high energy physics laboratory CERN are considering the construction of a huge new accelerator. This article outlines our understanding of the fundamental forces of nature and the subnuclear structure of matter, and describes the accelerator that will enable some of their mysteries to be explained.     

Is diffusion anisotropy an accurate monitor of myelination?: Correlation of multicomponent T2 relaxation and diffusion tensor anisotropy in human brain

We compare T2-relaxation and diffusion tensor data from normal human brain. The relationships between myelin-water fraction (MWF) and various diffusion tensor measures [e.g., fractional anisotropy (FA), perpendicular diffusivity (ADC perpendicular) and mean diffusivity ] in white matter (WM) and gray matter (GM) structures in the brain were examined in 16 normal volunteers at 1.5 T and 6 normal subjects at 3.0 T and mean diffusivity. We found some degree of linear correlation between these measurements, but by using region of interest (ROI)-based analysis, we also observed several structures which seemed to deviate significantly from a linear relationship. From all investigated relationships between various diffusion tensor measures and myelin-water content, FA and ADC perpendicular yielded the highest correlation coefficients with MWF. However, diffusion anisotropy was also significantly influenced by factors other than myelin-water content. The less operator-dependent voxel-based analysis (VBA) between myelin-water and diffusional anisotropy measures is proposed as an innovative alternative to ROI-based analysis. We confirmed that WM structures, in general, have higher diffusional anisotropy than GM structures and also have higher myelin-water content. However, our findings suggest that in the highly organized fibre arrangement of compact WM structures such as the genu of the corpus callosum, elevated degrees of diffusional anisotropies are measured, which do not necessarily correspond to an elevated myelin content but more likely reflect the highly organized directionality of fibre bundles in these areas (low microscopic and macroscopic tortuosity) as well as strongly restricted diffusion in the interstitial space between the myelinated axons. Conversely, in structures with disorganized fibre bundles and multiple fibre crossings, such as the minor and major forceps, low FA values were measured, which does not necessarily reflect a decrease myelin-water content.     

Kinetic resolution of allylic alcohols using a chiral phosphine catalyst

[reaction: see text] The kinetic resolution of racemic allylic alcohols 3, 6, and 12--17 has been explored using the PBO catalyst 7 for activation of isobutyric anhydride. Trisubstituted allylic alcohols (12--15; 17) are the best substrates and react with an enantioselectivity of s = 32--82 at -40 degrees C.     

Method of predicting Leq created by urban traffic

The time-averaged overall mean-square sound pressure created by statistically stationary traffic travelling a finite, straight road segment is determined explicitly. This result is extended to a system of roads by using digital simulation. Theoretical predictions for a typical urban conurbation show encouraging agreement with measured values. Therefore the technique appears to offer a practical means of evaluating community plans before the introduction of road systems and changes in trunk routes and traffic controls, etc., are realized.     

Preparation of nanocrystalline metal hydrides by ball milling

The diffusion of hydrogen into metals during ball milling has been investigated. A system is described that enables the milling to be done under approximately constant hydrogen pressure and allows for the continuous measurement of the quantity of hydrogen absorbed. This method has been used to prepare nanocrystalline hydrides of a variety of early transition metals and alloys. X-ray diffraction studies are used to identify phases present before and after milling and the width of diffraction peaks is used to estimate average grain size. Changes in the microstructure of Fe-containing samples during hydrogen absorption have been investigated by Mössbauer effect. Studies of the influence of milling conditions and the effect of milling time are also presented.     

Synthetic,Structural, and RNA Binding Studies on 2-Aminopyridine-Modified Triplex-Forming Peptide Nucleic Acids

The development of new RNA-binding ligands is attracting increasing interest in fundamental science and the pharmaceutical industry. The goal of this study was to improve the RNA binding properties of triplex-forming peptide nucleic acids (PNAs) by further increasing the pK_a of 2-aminopyridine ( M ). Protonation of M was the key for enabling triplex formation at physiological pH in earlier studies. Substitution on M by an electron-donating 4-methoxy substituent resulted in slight destabilization of the PNA–dsRNA triplex, contrary to the expected stabilization due to more favorable protonation. To explain this unexpected result, the first NMR structural studies were performed on an M -modified PNA–dsRNA triplex which, combined with computational modeling identified unfavorable steric and electrostatic repulsion between the 4-methoxy group of M and the oxygen of the carbonyl group connecting the adjacent nucleobase to PNA backbone. The structural studies also provided insights into hydrogen-bonding interactions that might be responsible for the high affinity and unusual RNA-binding preference of PNAs.     

Sustainable energy storage – with hot air,or cold air or liquid air

In memory of Sir David John Cameron MacKay FRS FInstP FICE (22 April 1967 – 14 April 2016). David was passionate about sustainable energy. One key element for sustainable energy is energy storage. As a small tribute, this article presents a review from a physics perspective of the thermodynamics of compressed air energy storage. Firstly, I treat adiabatic compressed air energy storage, where the heat of compression of the air is kept in the compressed air. Then I discuss improvements that can be made by combining compressed air energy storage with external heat stores. Next, I address isothermal compressed air energy storage, where the temperature is allowed to equilibrate with the environment. In each case, I consider two scenarios: underground caverns and underwater airbags. Finally, I address the case where the air is compressed and cooled so much that it liquifies. Throughout, I explain that the real point is to store available work, called exergy in the engineering community, rather than energy. Although my treatment is mostly from the ideal point of view of quasistatic processes, I give some pointers to technological implementations of the various methods and to some references on their thermodynamic efficiencies.