The influence of random changes in the adsorbing potential on phase transitions in a Lennard-Jones fluid confined to energetically heterogeneous slit-like pores

A density functional approach is used to study the adsorption and phase behaviour of a Lennard-Jones (LJ) fluid in slit-like pores with energetically heterogeneous walls, investigating how the randomly varying part of the fluid-solid potential imposed on a periodic ‘back-ground’ potential modifies the phase behaviour of the confined fluid. Non-local density functional theory is employed to describe the system. To study the system with a random external field, the method used is based on investigations of several replicas of the system and on averaging the final thermodynamic results over the replicas.     

Superposition model in electron magnetic resonance spectroscopy – a primer for experimentalists with illustrative applications and literature database

We review applications of the superposition model (SPM) in EMR area, which enables semi-empirical modeling of zero-field splitting (ZFS) parameters (ZFSPs) for transition ions in crystals by separation of geometrical and physical information. Nomenclature used for ZFS and crystal field (CF) Hamiltonians is presented to expose common framework underlying two independent implementations: SPM/ZFS and SPM/CF, which require distinct model parameters. SPM/ZFSP applications in EMR area for S-state 3d⁵ (4f⁷) ions and 3d^N ions with orbital singlet ground state are reviewed. SPM/ZFS methodology for ML_n complexes [central metal (M) ion surrounded by n ligands (L)] with specific symmetry is presented. SPM-related computer packages combined with other methods, role of axis systems in SPM analysis, and structural models for several ion-host systems, are discussed. Extensive survey of SPM/ZFS applications is provided to elucidate usefulness of SPM modeling for interpretation of ZFSPs. This review is geared for EMR practitioners interested in practical utilization of SPM/ZFS (or SPM/CFP) analysis. Database of SPM/ZFS references is compiled for studies of single molecule magnets and single ion magnets based on transition ions. Due to its comprehensiveness, suitable sets of model parameters required for practical utilization SPM/ZFS may be easily located using source references as pointers.     

Effect of high pressures on the enzymatic activity of commercial milk protein coagulants

This study was aimed at determining the effect of high pressures in the range of 100–1000 MPa/15 min, applied in 100 MPa increments, on the coagulating and proteolytic activity of commercial coagulants produced with genetic engineering methods: Maxiren, Chymogen, Chymax and of a natural rennin preparation, Hala. The coagulating activity of Hala preparation differed compared with the other preparations, due to greater resistance to high pressures, especially in the range of 500–600 MPa. The preparations produced with genetic engineering methods lost their capability for milk protein coagulation by 500 MPa. Pressurization at 200 MPa contributed to their reduced capability for casein macroproteolysis. In contrast, an increase in Chymax, Chymogen, Maxiren and Hala preparations’ hydrolytic capability for the macroproteolysis of isoelectric casein was observed upon pressure treatment at 100 and 400 MPa and for microproteolysis after pressure treatment at 200 MPa. Storage (48 h/5°C) of the pressurized preparations had an insignificant effect on their coagulating and proteolytic activities.     

Mathematical modelling of immune reaction against gliomas: Sensitivity analysis and influence of delays

In the paper we considered a model of immune reaction against malignant glioma. The model proposed by Kronik et al. (Cancer Immunol. Immunother., 2008) describes simplified interactions between tumour cells and five components of the immune system. We studied the effects of uncertainties of the parameters values to the system behaviour. We showed that the tumour growth rate is one of the most important parameters only in case of fast growing tumours, that is for GBM in our case.On the basis of the performed sensitivity analysis we proposed a reduced model in which the role of time delays in loops appearing in the described interactions is considered. The proposed model includes only two main components of the reaction, that is tumour cells and cytotoxic T-lymphocytes. It occurs that although the reduced system is described by several non-linear terms with three time delays, its dynamics is simple and time delays have hardly any influence on it.Both considered models confirmed that the non-linearities present in interactions between tumour cells and CTLs play a major role in the system dynamics, while other components or delays can be taken into account as supplementary elements only.     

On the exact discretization of the classical harmonic oscillator equation

We discuss the exact discretization of the classical harmonic oscillator equation (including the inhomogeneous case and multidimensional generalizations) with a special stress on the energy integral. We present and suggest some numerical applications.     

Asymmetric organocatalytic formal [2 + 2]-cycloadditions via bifunctional H-bond directing dienamine catalysis

A new concept in organocatalysis allowing for the construction of cyclobutanes with four contiguous stereocenters with complete diastereo- and enantiomeric control by a formal [2 + 2]-cycloaddition is presented. The concept is based on simultaneous dual activation of α,β-unsaturated aldehydes and nitroolefins by amino- and hydrogen-bonding catalysis, respectively. A new bifunctional squaramide-based aminocatalyst has been designed and synthesized in order to enable such an activation strategy. The potential and scope of the reaction are demonstrated, and computational studies which account for the stereochemical outcome are presented.     

Mesoscopic approach to minority games in herd regime

We study minority games in efficient regime. By incorporating the utility function and aggregating agents with similar strategies we develop an effective mesoscale notion of the state of the game. Using this approach, the game can be represented as a Markov process with substantially reduced number of states with explicitly computable probabilities. For any payoff, the finiteness of the number of states is proved. Interesting features of an extensive random variable, called aggregated demand, viz. its strong inhomogeneity and presence of patterns in time, can be easily interpreted. Using Markov theory and quenched disorder approach, we can explain important macroscopic characteristics of the game: behavior of variance per capita and predictability of the aggregated demand. We prove that in the case of linear payoff many attractors in the state space are possible.     

Topographically controlled growth of silver nanoparticle clusters

We present a straightforward method to form regular arrays of chemically synthesized Ag nanoparticle clusters, which are preferentially nucleated and developed inside pre‐patterned Si nanowells. The sizes and shapes of the clusters follow the dimensions of the lithographically defined Si nanowells, which here have a depth of 100 nm and form a square array with a pitch of 300 nm. Potential use of the array of Ag nanoparticle clusters as a surface‐enhanced Raman scattering (SERS) based sensing platform is demonstrated by the calculation of locally enhanced electromagnetic fields and by confocal microscopic measurements of increased Raman signals from organic molecules adsorbed on the Ag nanoparticle clusters. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)