Non-equilibrium behavior of sticky colloidal particles: beads,clusters and gels

To understand the non-equilibrium behavior of colloidal particles with short-range attraction, we studied salt-induced aggregation of lysozyme. Optical microscopy revealed four regimes: bicontinuous texture, beads, large aggregates, and transient gelation. The interaction of a metastable liquid-liquid binodal and an ergodic to non-ergodic transition boundary inside the equilibrium crystallization region can explain our findings.     

Adaptive connection admission control for differentiated services access networks

In our earlier work, we have proposed some modifications for the bandwidth broker framework. With our modifications, it is possible to use measurement-based admission control in addition to the more traditional parameter-based admission control. Moreover, we have presented a new flexible admission control scheme that has proven to be very efficient in terms of bottleneck link utilization. Two problems, however, have arisen: the use of scheduling weights in admission control and bursty connection arrivals. In this paper, we present that the former one can be dealt with the use of adaptive scheduling weights, while the latter one can be fought with adaptive reservation limits. The proposed new algorithms are validated through simulations and their performance is compared against the nonadaptive basic scheme.     

Utilising thermoporometry to obtain new insights into nanostructured materials

Thermoporometry is a relatively new method of characterising porous properties of nanostructured materials based on observation of solid–liquid phase transitions of materials confined in pores. It provides several advantages over the conventional characterisation methods, mercury porosimetry and gas sorption. The advantages include possibility of using short measurement times, non-toxic chemicals and wet samples. In addition, complicated sample preparation and specialised instruments are not required. Therefore, it has a great potential of becoming a widely utilised characterisation method, although its potential has not yet been widely realised. In recent years, there has been a significant increase in research activities regarding the method. In the first part of the review, we introduce thermoporometry and review related results of the confinement effects on materials and their solid–liquid phase transition.     

Electrochemical wettability control on conductive TiO2 nanotube surfaces modified with a ferrocene redox system

This work reports on an electrochemical system which allows the control of surface wettability properties by voltage induced changes in contact angle (Θ) of ΔΘ  50°. For this we used conductive TiO₂ nanotubular layers that were modified with ferrocene coupled to the TiO₂ surface via triethoxysilane. To enhance the hydrophobic character of the nanotubular TiO₂ surface, also mixed organic monolayers namely perfluorotriethoxysilane, were explored. Formation of the ferrocene and mixed organic monolayer was confirmed by X-ray-photoelectron-spectroscopy (XPS). Contact angle combined with electrochemical measurements show that ferrocene in these monolayers can successfully be switched from Fe²⁺ to Fe³⁺ and that this change in the redox state considerably alters the wetting properties. Using a conductive nanotube substrate allows us to amplify this change by a factor of more than 10, and thus this surface can be used to trigger significant wetting alterations.     

Prediction model for the diurnal behavior of the troposphericscintillation variance

Tropospheric scintillation is caused by variations of the refractive index due to turbulence. The only meteorological input parameter for two common current scintillation models by Karasawa et al. (1988) and by the ITU-R is the monthly average of the wet part of the refractivity N_wet at ground level, which is not directly associated with turbulence. The diurnal correlation between N_wet and scintillation variance is very weak. Because clouds and cloud formation are closely associated with the turbulence, quantitative cloud parameters were looked for. Cloud type information based on edited synoptic cloud reports are available from the common database of CDIAC and NCAR. Both diurnal and seasonal variations between scintillation variance and average amount of Cumulus type clouds are well correlated. Using this cloud information together with N_wet, a new method for tropospheric scintillation variance predicting also the diurnal variations is introduced. This model is derived and tested using scintillation measurements at four sites in different climates in Finland, United Kingdom, Japan, and Texas     

Raman and ATR FTIR spectroscopy in reactive crystallization: Simultaneous monitoring of solute concentration and polymorphic state of the crystals

Batch-reactive crystallization of the two polymorphs of l-glutamic acid was studied using in-line Raman and ATR FTIR spectroscopy. It was observed that the barrier to the nucleation of the stable β-form was higher, and thus the occurrence of β-form nucleation requires a higher supersaturation level. The local supersaturation level inside the reactive crystallizer is significantly affected by the feeding manner of the reactant. When the reactant was fed to a poorly mixed zone, such as the surface of the liquid, a high local supersaturation level was generated near the feeding point. This high local supersaturation level drastically increased with the increase in the concentrations of the reactants. As a consequence, the fraction of the β-form increased with the increase in reactants concentrations. On the other hand, feeding the reactant to a well-mixed zone near the impeller can avoid the occurrence of high local supersaturation, and therefore the dependence of the polymorphic composition of the final product on the concentration of the reactants can be reduced. The information obtained from the spectroscopy leads to improved understanding of the precipitation process and offers great potential for process optimization and control of crystalline quality.     

Bulky Phosphinines: From a Molecular Design to an Application in Homogeneous Catalysis

The design and preparation of an asymmetrically substituted and bulky phosphinine was achieved by introducing sterically demanding substituents into specific positions of a rigid phosphorus‐heterocyclic framework. Compound 5 shows, at the same time, axial chirality and a sufficiently high energy barrier for internal rotation to prevent enantiomerization. Both enantiomers of 5 were isolated by means of chiral analytical HPLC, and their absolute configurations could be assigned by combining experimental data and DFT calculations. Despite its substitution pattern, 5 can still coordinate to transition‐metal centers through the lone pair of electrons on the phosphorus atom. Rapid C? H activation on the adjacent aryl substituent at the 2‐position of the phosphorus heterocycle was achieved by using [{Cp*IrCl₂}₂] (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) as a metal precursor. A racemic mixture of 5 was applied as a π‐accepting low‐coordinate phosphorus ligand in the Rh‐catalyzed hydroformylation of trans‐2‐octene, which showed a clear preference for the formation of 2‐methyloctanal.     

Predictions of radiowave attenuations due to a melting layer ofprecipitation

A melting layer model related to the physical constants and meteorological parameters is employed in this investigation. The specific phase shift, together with the specific attenuation, is computed at 1-100 GHz by using the Mie theory. The additional zenith attenuation, which is the difference between zenith attenuation due to the melting layer and attenuation due to the same thickness of the resulting rain, is comprehensively studied. The ratio of the difference to rain zenith attenuation may be over 1 at 1-5 GHz although the difference is much less than 1 dB. The difference can be over 1 dB at frequencies above 20 GHz. A minimum of the ratio is below 0.05 at frequencies about 40-60 GHz but the ratio can become a value of about 0.1 at 100 GHz. The additional attenuation should be taken into account in satellite-Earth communications and radar remote sensing. The power law parameters of the average specific attenuation of the melting layer and rain specific attenuation are tabulated for three raindrop size distributions at rain rates of below 25 mm/h. The power law method could be utilized in the additional attenuation calculation. It is a good approximation of the Mie theory results at 1-50 GHz and a useful estimate at 50-100 GHz     

Utilising thermoporometry to obtain new insights into nanostructured materials

Thermoporometry is a relatively new method of characterising porous properties of nanostructured materials based on observation of solid–liquid phase transitions of materials confined in pores. It provides several advantages over the conventional characterisation methods, mercury porosimetry and gas sorption. The advantages include possibility of using short measurement times, non-toxic chemicals and wet samples. In addition, complicated sample preparation and specialised instruments are not required. Therefore, it has a great potential of becoming a widely utilised characterisation method, although its potential has not yet been widely realised. In recent years, there has been a significant increase in research activities regarding the method. In the second part of the review, results and conclusions of the recent studies about thermoporometry are surveyed and discussed focusing on the application of thermoporometry in extracting various structural information from the porous materials.