Communication in Chemical Emergencies

In the case of chemical emergencies, public information must be given high priority in both planning and management. The public information requirement concerning major accident hazards has been incorporated into Community legislation since 1982 as a relevant component of the control of major accident hazards. During an emergency, communication is to be recognised as the most critical factor that determines the success of the response. However, during an emergency, while the dynamics of events and processes may be partially obscure, people must still be warned of impending danger. The management of ‘in the event’ information is quite diverse from that of ‘prior’ information.     

Coexistence of Negative and Positive Photoconductivity in Few-Layer PtSe2 Field-Effect Transistors

Platinum diselenide (PtSe₂) field-effect transistors with ultrathin channel regions exhibit p-type electrical conductivity that is sensitive to temperature and environmental pressure. Exposure to a supercontinuum white light source reveals that positive and negative photoconductivity coexists in the same device. The dominance of one type of photoconductivity over the other is controlled by environmental pressure. Indeed, positive photoconductivity observed in high vacuum converts to negative photoconductivity when the pressure is raised. Density functional theory calculations confirm that physisorbed oxygen molecules on the PtSe₂ surface act as acceptors. The desorption of oxygen molecules from the surface, caused by light irradiation, leads to decreased carrier concentration in the channel conductivity. The understanding of the charge transfer occurring between the physisorbed oxygen molecules and the PtSe₂ film provides an effective route for modulating the density of carriers and the optical properties of the material.     

K maximum probability attack paths generation algorithm for target nodes in networked systems

International Journal of Information Security - As known, security system administrators need to be aware of the security risks and abnormal behaviors in a network system. Given the exploitation...     

Heparin conjugated silica nanoparticle synthesis

We report on a facile method towards a synthesis of novel hybrid heparin silica nanoparticles involving a modification of the Stober method. Tetrapropyl orthosilicate (TPOS) was used instead of the traditional TEOS or TMOS; by this way we could overcome the solubility problems of heparin in ethanol and exploit the good solubility of heparin in proper isopropanol–water mixtures. Aminopropyl triethoxysilane (APTS) was also used to have a good link of heparin to silica particles. SEM, DLS, FTIR and NMR proved that we did find conditions in which heparin conjugated silica particles were produced.Thermogravimetry allowed to evaluate the heparin/silica weight ratio to be 0.61. The efficiency of heparin binding to the particles was appreciated to be 35 wt.%.     

Tailoring the Structure of Cell Penetrating DNA and RNA Binding Nucleopeptides

Synthetic nucleic acid interactors represent an exciting research field due to their biotechnological and potential therapeutic applications. The translation of these molecules into drugs is a long and difficult process that justifies the continuous research of new chemotypes endowed with favorable binding, pharmacokinetic and pharmacodynamic properties. In this scenario, we describe the synthesis of two sets of homo-thymine nucleopeptides, in which nucleobases are inserted in a peptide structure, to investigate the role of the underivatized amino acid residue and the distance of the nucleobase from the peptide backbone on the nucleic acid recognition process. It is worth noting that the CD spectroscopy investigation showed that two of the reported nucleopeptides, consisting of alternation of thymine functionalized L-Orn and L-Dab and L-Arg as underivatized amino acids, were able to efficiently bind DNA and RNA targets and cross both cell and nuclear membranes.     

Influence of ageing on the cold crystallization of glassy poly(ethyleneterephthalate)

The thermal crystallization from the glassy state of different samples of Poly(ethyleneterephthalate) (PET) was investigated with different techniques, such as infrared and x-ray analysis and polarized optical microscopy. The different samples of PET were obtained by ageing the glassy PET films at room temperature and at 60 °C; the behaviour of these films was compared with that of the fresh sample, put at the crystallization temperature as soon as prepared. The temperature of crystallization was 120 °C. All the techniques, investigated to follow the crystallization phenomenon, show that the fresh sample crystallizes with longer times than the others. This result was correlated with the initial structural organization of the glassy amorphous films. Received: 13 February 1997/Accepted: 10 March 1997     

Numerical/Experimental Correlation of a Plasma Wind Tunnel Test on a UHTC-Made Nose Cap of a Reentry Vehicle

The nose cap demonstrator named Nose_2 has been tested for the second time in the plasma wind tunnel (PWT) facility which is part of the sharp hot structure (SHS) technology project, focused on the assessment of the applicability of ultrahigh temperature ceramics (UHTC) to the fabrication of high performance vehicles and SHS for reusable launch vehicles. In this paper the FEM based thermal analyses, carried out for the rebuilding of this PWT test, are presented. Experimental data measured in the PWT have been compared with numerical ones in order to validate the FEM model and to help in interpreting the experimental test itself. The knowledge on the physical phenomenon under investigation has been greatly improved, thanks to the synergy between numerical and experimental activities. In particular, a qualitative study of the modeling of the tip-dome interface has been performed in order to estimate the thermal contact resistance that heat flux encounters in passing through the demonstrator. The correlation between numerical and experimental temperature curves has been found to be satisfactory for both internal and surface temperature distribution, and the FEM model was found reliable in reproducing the thermal behavior of the nose cap.     

A Global/Local Finite Element Approach for Predicting Interlaminar and Intralaminar Damage Evolution in Composite Stiffened Panels Under Compressive Load

This paper addresses the prediction of intralaminar and interlaminar damage onset and evolution in composite structures through the use of a finite element based procedure. This procedure joins methodologies whose credibility has been already assessed in literature such as the Virtual Crack Closure Technique (for delamination) and the ply discount approach (for matrix/fiber failures). In order to establish the reliability of the procedure developed, comparisons with literature experimental results on a stiffened panel with an embedded delamination are illustrated. The methodology proposed, implemented in ANSYS © as post-processing routines, is combined with a finite element model of the panel, built by adopting both shell and solid elements within the frame of an embedded global/local approach to connect differently modelled substructures.     

Giant coupling effect between metal nanoparticle chain and optical waveguide

We demonstrate that the optical energy carried by a TE dielectric waveguide mode can be totally transferred into a transverse plasmon mode of a coupled metal nanoparticle chain. Experiments are performed at 1.5 μm. Mode coupling occurs through the evanescent field of the dielectric waveguide mode. Giant coupling effects are evidenced from record coupling lengths as short as ~560 nm. This result opens the way to nanometer scale devices based on localized plasmons in photonic integrated circuits.     

The Effect of Geological Heterogeneity and Groundwater Table Depth on the Hydraulic Performance of Stormwater Infiltration Facilities

Urbanization has led to a substantial change in the hydrological cycle of urban catchments. Increased runoff and urban flooding, decreased direct subsurface infiltration and groundwater recharge, deterioration of water quality are among the major effects of this alteration. To alleviate these effects, Low Impact Development (LID) practices have been frequently adopted for stormwater management. Among LID infrastructures, infiltration facilities are particularly challenging to design and model due to the considerable amount of uncertainties related to the hydrogeological configuration of installation sites. To date, analysis on how soil heterogeneity, groundwater table depth, and thickness of the unsaturated zone affect the hydraulic performance of infiltration facilities are lacking. To address this knowledge gap, a series of numerical experiments under transient variably water saturated conditions were performed for a hypothetical infiltration facility. Numerical simulations showed that i) infiltration rates increase considerably as the initial depth of the groundwater table increases, ii) the contribution of the bottom of the facility to the infiltration of water is generally higher than the sides, iii) the presence of a less conducting soil layer at a short depth from the bottom of the facility reduces infiltration rates dramatically, iv) the complete clogging of the bottom of the facility has a dramatic impact on the hydraulic performance, v) the stochastic heterogeneity of the soil controls the overall stormwater infiltration process through the facility, and the hydraulic performance may largely deviate from the case when heterogeneity is absent.