The Calculation of Coefficients of Coulomb and Exchange Integrals in Matrix Elements Involving Polar Singlet Structures

Starting from Pauling's rules for calculating matrix elements for covalent structures, it is shown how to extend the valence‐bond treatment to polar structures. Attention is called to the new types of integrals which are involved and simple procedures for evaluating their coefficients are described

Networks of SLGOs: from systems interoperability to organizational cooperability

E-Government doesn’t concern only technological innovation in Public Administration, but most of all organizational innovation through the adoption of organizational models enabled by the use of ICTs. One model of this kind, that in countries characterized by a high number of Small Local Government Organizations (SLGOs) can be adopted also to reduce the administrative fragmentation, is inter-organizational cooperation among SLGOs. This is the model the Italian National Center for Information Technology in Public Administration (CNIPA) adopted in the action plan to promote E-Government in Local Public Administration in Italy. However, inter-organizational cooperation requires the partners to interoperate, at least in the areas which are the object of the cooperation. One possibility which guarantees interoperability of different organizations consists in the adoption of a shared cooperative environment. Depending on how binding are the conditions which define it, the cooperative environment can determine different levels of interoperability, up to organizational interoperability (cooperability). In the case of cooperation among organizations which can be heterogeneous, one of the conditions defining the cooperative environment is the sharing of an “enterprise model” for the cooperation. In the paper we describe some of the conditions that define a cooperative environment and introduce a system for the description and the classification of different forms of intercommunal cooperation for services provision

A Theoretical Study of the Influence of Surface Structure on Chemisorption of Nitrogen on Iron Single-Crystal Faces

An Extended Ruckel (E. H.) calculation was performed for the energy of Fex clusters (with x = 9, 10, 13, 15, 18) that are used to model the 111, 100, 110 surface planes of an iron single-crystal. Interaction energies of atomic and molecular nitrogen with each cluster were calculated for different geometrical configurations of the system. From this data thermodynamic and kinetic considerations allowed the following order of reactivity of the different surfaces, in ammonia synthesis, to be estabilished: 111 > 100 > 110. Comparison with experimental results is more than satisfactory

Bond Orbitals and Bond Energy in Elementary Phosphorus

A discussion of the relative stability of the P4 molecule and black phosphorus is carried out, with use of hybrid spd bond orbitals. The amount of strain in the P4 molecule, in which the bond angles are 60°, is calculated to be 22.8 kcal mole^–1. This value is shown to be compatible with thermochemical data; it corresponds to the value 51.3 kcal mole^–1 for the bond energy of the normal P-P bond. A structure is proposed for red phosphorus and other allotropic forms of the element, and some of their properties are discussed in relation to their structure

How we treat bleeding associated with direct oral anticoagulants

Direct oral anticoagulants are at least as effective as vitamin K antagonists for the prevention and treatment of thromboembolism. Unfortunately, differently from vitamin K antagonists, they have the great drawback of lacking specific antidotes in the case of bleeding or emergency situations such as trauma, stroke requiring thrombolysis, and urgent surgery. The progressive development of antidotes for these new drugs, which, it is hoped, will become available in the near future, will allow better and safer management of the rapid reversal of their anticoagulant effect

Aggregation Mechanism of an IgG2 and two IgG1 Monoclonal Antibodies at low pH: From Oligomers to Larger Aggregates

Purpose: To identify the aggregation mechanism and the stability characteristics of three different monoclonal antibodies under acidic conditions. Methods: The aggregation kinetics is analyzed by a combination of light scattering, size exclusion chromatography and fluorescence techniques and the aggregation data are correlated to protein structure, hydrophobicity, charge and antibody subclass. Results: In the investigated conditions, the antibody aggregation follows a mechanism consisting of two-steps: reversible monomer oligomerization followed by irreversible cluster-cluster aggregation. The kinetics of the two steps is differently affected by the operating conditions: mild destabilizing conditions induce formation of oligomers which are stable within weeks, while stronger denaturing conditions promote aggregation of oligomers to larger aggregates which eventually precipitate. For different antibodies significant differences in both oligomerization and growth rates are found, even for antibodies belonging to the same subclass. For all antibodies the aggregate formation is accompanied by a structure re-organization with an increase in the ordered β-sheet structures. At low pH the aggregation propensity of the investigated antibodies does not correlate with antibody subclass, surface net charge and hydrophobicity of the non-native state. Conclusions: The aggregation mechanism of three antibodies in acidic conditions as well as differences and analogies in their stability behavior has been characterize

The management of a blood donor bitten by a snake

The worldwide burden of snakebite is high and venomous snakes are found in many regions of the world and are a threat to public health. In Italy, for instance, viper bites are an infrequent but not negligible event. Although people who have been bitten by a snake rarely wish to donate blood within a "short" time, it is however important to evaluate their eligibility to donate blood or blood components as their donation could be a problem for donor management, especially if a specific policy is not in place. The aim of this manuscript is to summarise the worldwide existing donor deferral policy for snakebites and to provide some indications in order to facilitate decision-making and to guarantee maximum safety for the donors as well as for the recipients

The Role of ABO Blood Type in Thrombosis Scoring Systems

In addition to their major role in transfusion medicine, there is increasing evidence that ABO blood group antigens (complex carbohydrate molecules widely expressed on the surface of red blood cells and several other cell types) are implicated in the development of a wide array of pathologic conditions. In particular, intense research has been dedicated over the last 50 years to the study of the association between non-O blood type and the risk of developing cardiovascular disorders. Several pathways have been hypothesized to explain this relationship, the most reasonable implying the influence of the ABO blood group on circulating plasma levels of von Willebrand factor, factor VIII, and several inflammatory cytokines. This narrative review summarizes the current knowledge on the role of ABO antigens in both venous and arterial thromboses, focusing on their association with clinical scoring systems evaluating thrombotic risk

Fibrinogen concentrate in surgery

Fibrinogen is a plasma glycoprotein synthesised by the liver which plays a critical role in haemostasis by acting as an endogenous substrate for fibrin formation and by inducing clot formation and platelet aggregation