Scaling in the Lattice Gas Model

A good quality scaling of the cluster size distributions is obtained for the Lattice Gas Model using the Fisher's ansatz for the scaling function. This scaling identifies a pseudo-critical line in the phase diagram of the model that spans the whole (subcritical to supercritical) density range. The independent cluster hypothesis of the Fisher approach is shown to describe correctly the thermodynamics of the lattice only far away from the critical point.Comment: 4 pages, 3 figure

Alkaline pretreatment of walnut shells increases pore surface hydrophilicity of derived biochars

The surface chemistry and morphology of biochars produced by pyrolysis of walnut shells affects their utility for adsorption applications. Yet, little is known about surface interactions in the pores of these materials, mostly due to the challenging nature of accessing information at this length scale in a non-destructive manner. Here, for the first time, the relative adsorption strengths of solvents comprising different functional groups to internal (pore) surfaces of walnut shells and derived biochars were investigated using low-field nuclear magnetic resonance (NMR) relaxation time measurements to non-destructively probe interactions of fluids with pore surfaces. Carbon bonding state compositions of these materials with respect to distance from the particle surface were determined using X-ray photoelectron spectroscopy coupled with ion beam etching. Alkaline pretreatment was found to increase the hydrophilicity of both walnut shells and derived biochars. It was found to increase surface interactions with hydroxyl groups, and to decrease those with methyl groups. Results were contextualised by thermogravimetric analysis, scanning electron microscopy, and previous in-situ X-ray imaging results. Taken together, results showed that alkaline pretreatment may be used to modulate responses to pyrolysis temperature of several factors that affect adsorption properties including surface hydrophilicity, particle size, porosity, pore accessibility, and surface texture

Comparison of Italian and Hungarian Black Spot Ranking

AbstractBlack spot ranking is an important tool for finding the sites with potential safety improvement on the road network. The EU Directive on Road Infrastructure Safety Management also demands the ranking of high accident concentration sites. This paper gives an introduction to localizing high accident concentration sites and the indicators used by Italy and Hungary. Accident and traffic volume data are gathered for motorway sections from both countries. Safety ranking is made using two conventional indicators, absolute number of accidents and accident rate. A more sophisticated ranking using the Empirical Bayes method is applied. Expected average crash frequency with Empirical Bayes adjustment is calculated. Based on the estimation of the crash frequency, the Critical Crash Rate (CCR) was added to identify and rank black spots. This additional performance measure is able to take into account traffic volume as required by the EU Directive. Results of the Empirical Bayes method are compared with the conventional procedures. It is concluded that the results are not comparable; inasmuch as there are modifications in the order of black spots. Based on the comparison of results recommendations are given to change the practice in both countries

Isotopic composition of fragments in multifragmentation of very large nuclear systems: effects of the chemical equilibrium

Studies on the isospin of fragments resulting from the disassembly of highly excited large thermal-like nuclear emitting sources, formed in the ^{197}Au + ^{197}Au reaction at 35 MeV/nucleon beam energy, are presented. Two different decay systems (the quasiprojectile formed in midperipheral reactions and the unique source coming from the incomplete fusion of projectile and target in the most central collisions) were considered; these emitting sources have the same initial N/Z ratio and excitation energy (E^* ~= 5--6 MeV/nucleon), but different size. Their charge yields and isotopic content of the fragments show different distributions. It is observed that the neutron content of intermediate mass fragments increases with the size of the source. These evidences are consistent with chemical equilibrium reached in the systems. This fact is confirmed by the analysis with the statistical multifragmentation model.Comment: 9 pages, 4 ps figure

Effects of surface modifications on molecular diffusion in mesoporous catalytic materials

In this work, we use pulsed-field gradient (PFG) NMR to probe molecular diffusion of liquids inside mesoporous structures and assess the influence of surface modifications, namely, deposition of palladium (Pd) nanoparticles over alumina (Al2O3) surfaces and passivation of titania (TiO2) surfaces with alkyl chains, on the diffusion pattern

Statistical evolution of isotope composition of nuclear fragments

Calculations within the statistical multifragmentation model show that the neutron content of intermediate mass fragments can increase in the region of liquid-gas phase transition in finite nuclei. The model predicts also inhomogeneous distributions of fragments and their isospin in the freeze-out volume caused by an angular momentum and external long-range Coulomb field. These effects can take place in peripheral nucleus-nucleus collisions at intermediate energies and lead to neutron-rich isotopes produced in the midrapidity kinematic region.Comment: 14 pages with 4 figures. GSI preprint, Darmstadt, 200

Sensors for the monitoring of analytes in the sweat

In the last decade, can be found an exceptional growth in research activity relating to the development of wearable devices, capable of continuously monitoring the health conditions of the wearer by analyzing body fluids such as blood, urine, saliva, tears and sweat. Among the body fluids available, sweat is a biofluid of particular interest, as it allows a non-invasive, continuous and comfortable collection. Human sweat contains useful information on the health of an individual and therefore is an excellent biofluid for the detection of specific analytes. The most abundant ions in the sweat are Na+ and Cl- (10 - 100 mM), and their monitoring is useful in patients with cystic fibrosis. Other constituents are Ca2+, K+, ascorbic acid, glucose (0.1-10 µM) related to osteoporosis, hypoaldosteronism, scurvy and diabetes disease. The sweat pH is in the range 3 to 8 [1] [2] and indicates the level of metabolism and homeostasis of the body. Wearable sensor needs to be flexible, compact and easily applicable. It must also offer a stable response, with high sensitivity and selectivity towards specific analytes [3]. Over the years, many wearable sensors for sweat monitoring have been developed, combining different form factors, substrates and sensing mechanism. In this work, electrochemical sensors based on polyaniline (PANi), which is pH sensitive, were studied. First, the best conditions of electrochemical deposition of PANi were studied [4], using as flexible substrate polyethylene terephthalate coated with indium-tin oxide (ITO-PET). In order to improve the sensor performance electrodes were also modified by electrochemical deposition of reduced graphene oxide (rGO). All samples were characterized by XRD, SEM and EDS analysis in order to study morphology and evaluate the crystalline phases of the deposited PANi. The electrodes were tested as pH sensors using different buffer solutions, from 2 to 8, by Open Circuit Potential (OCP) technique. The ITO-PET/rGO/PANi electrodes show good behavior in terms of sensitivity (62.3 mV/pH), very close to Nernstian response of 59 mV/pH and reproducibility of 3.8%. Flexibility and mechanical stability tests were carried out on the sensor to evaluate both the wearability and mechanical resistance. In addition, interference tests, in the presence of competing ions such as Na+, Cl-, K+, NH4+, aimed to verify the selectivity were also performed