Ising Critical Behavior of Inhomogeneous Curie-Weiss Models and Annealed Random Graphs

We study the critical behavior for inhomogeneous versions of the Curie-Weiss model, where the coupling constant \({J_{ij}(\beta)}\) for the edge \({ij}\) on the complete graph is given by \({J_{ij}(\beta)=\beta w_iw_j/( {\sum_{k\in[N]}w_k})}\). We call the product form of these couplings the rank-1 inhomogeneous Curie-Weiss model. This model also arises [with inverse temperature \({\beta}\) replaced by \({\sinh(\beta)}\) ] from the annealed Ising model on the generalized random graph. We assume that the vertex weights \({(w_i)_{i\in[N]}}\) are regular, in the sense that their empirical distribution converges and the second moment converges as well. We identify the critical temperatures and exponents for these models, as well as a non-classical limit theorem for the total spin at the critical point. These depend sensitively on the number of finite moments of the weight distribution. When the fourth moment of the weight distribution converges, then the critical behavior is the same as on the (homogeneous) Curie-Weiss model, so that the inhomogeneity is weak. When the fourth moment of the weights converges to infinity, and the weights satisfy an asymptotic power law with exponent \({\tau}\) with \({\tau\in(3,5)}\), then the critical exponents depend sensitively on \({\tau}\). In addition, at criticality, the total spin \({S_N}\) satisfies that \({S_N/N^{(\tau-2)/(\tau-1)}}\) converges in law to some limiting random variable whose distribution we explicitly characterize.     

Tetra-2,3-pyrazinoporphyrazines with externally appended pyridine rings. 5. Synthesis, physicochemical and theoretical studies of a novel pentanuclear palladium(II) complex and related mononuclear species

New palladium(II) complexes of the free-base tetrakis[2,3-(5,6-di-2-pyridylpyrazino)porphyrazine], [Py 8TPyzPzH 2], have been prepared and their physicochemical properties examined. The investigated compounds are the pentanuclear species [(PdCl 2) 4Py 8TPyzPzPd], the monopalladated complex [Py 8TPyzPzPd], and its corresponding octaiodide salt [(2-Mepy) 8TPyzPzPd](I) 8. All three Pd (II) complexes have a common central pyrazinoporphyrazine core and differ only at the periphery of the macrocycle, where the simple dipyridinopyrazine fragments present in [Py 8TPyzPzPd] bear four PdCl 2 units coordinated at the pyridine N atoms in the pentanuclear complex, [(PdCl 2) 4Py 8TPyzPzPd], or carry pyridine-N(CH 3) (+) moieties in the iodide of the octacation [(2-Mepy) 8TPyzPzPd] (8+). The structural features of the pentanuclear complex [(PdCl 2) 4Py 8TPyzPzPd], partly supported by X-ray data and solution (1)H NMR spectra of the [(CN) 2Py 2PyzPdCl 2] precursor, were elucidated through one- and two-dimensional (1)H NMR spectra in solution and density functional theory (DFT) calculations. Structural information on the monopalladated complex [Py 8TPyzPzPd] was also obtained from DFT calculations. It was found that in the complex [(PdCl 2) 4Py 8TPyzPzPd] the peripheral PdCl 2 units adopt a py-py coordination mode and the generated N 2PdCl 2 moieties are directed nearly perpendicular to the plane of the pyrazinoporphyrazine ring, strictly recalling the arrangement found for the palladated precursor [(CN) 2Py 2PyzPdCl 2]. NMR and DFT results consistently indicate that of the four structural isomers predictable for [(PdCl 2) 4Py 8TPyzPzPd], one having all four N 2PdCl 2 moieties pointing on the same side of the macrocyclic framework (i.e., isomer 4:0, plus the 3:1 and the 2:2-cis and 2:2-trans isomers), the 4:0 isomer ( C 4 v symmetry) is the predominant form present. According to cyclic voltammetry and spectroelectrochemical results in pyridine, dimethyl sulfoxide (DMSO), and dimethylformamide (DMF), the monopalladated complex [Py 8TPyzPzPd] undergoes four reversible or quasi-reversible one-electron ligand-centered reductions, similar to the behavior also observed for the pentanuclear complex [(PdCl 2) 4Py 8TPyzPzPd], which shows an additional reduction peak attributable to the presence of PdCl 2. Owing to the electron-withdrawing properties of the PdCl 2 units, the pentanuclear complex is easier to reduce than the mononuclear complex [Py 8TPyzPzPd], some related [Py 8TPyzPzM] complexes, and their porphyrin or porphyrazine analogues, so much so that the corresponding monoanion radical is generated at potentials close to 0.0 V vs SCE in DMSO or DMF. In turn, the monoanion of [(2-Mepy) 8TPyzPzPd](I) 8 is also extremely easy to generate electrochemically. Indeed, because of the eight positively charged N-CH 3 (+) groups in this complex the first reduction occurs at potentials close to +0.10 V in DMSO or DMF. The redox behavior of the mono- and pentapalladated complexes has been rationalized on the basis of a detailed DFT analysis of their ground-state electronic structure.     

Tuning emission properties of iridium and ruthenium metallosurfactants in micellar systems

Ruthenium metallosurfactant forms micelles that show efficient electronic energy-transfer processes in the presence of an analogous iridium complex. Modulation of the process is achieved upon incorporation of these amphiphiles into cetyltrimethylammonium bromide micelles, allowing a tuning of the two emissions.     

Insights into the Electronic Structure of a U(IV) Amido and U(V) Imido Complex

Reaction of the N-heterocylic carbene ligand ⁱPrIm (L¹) and lithium bis(trimethylsilyl)amide (TMSA) as a base with UCl₄ resulted in U(IV) and U(V) complexes. Uranium's +V oxidation state in (HL¹)₂[U(V)(TMSI)Cl₅] (TMSI=trimethylsilylimido) ( 2 ) was confirmed by HERFD-XANES measurements. Solid state characterization by SC-XRD and geometry optimisation of [U(IV)(L¹)₂(TMSA)Cl₃] ( 1 ) indicated a silylamido ligand mediated inverse trans influence (ITI). The ITI was examined regarding different metal oxidation states and was compared to transition metal analogues by theoretical calculations.     

How 5 f Electron Polarisability Drives Covalency and Selectivity in Actinide N-Donor Complexes

We report a series of isostructural tetravalent actinide (Th, U−Pu) complexes with the N-donor ligand N,N’-ethylene-bis((pyrrole-2-yl)methanimine) (H₂ L , H₂pyren). Structural data from SC-XRD analysis reveal [An(pyren)₂] complexes with different An−N_imine versus An−N_pyrrolide bond lengths. Quantum chemical calculations elucidated the bonding situation, including differences in the covalent character of the coordinative bonds. A comparison to the intensely studied analogous N,N′-ethylene-bis(salicylideneimine) (H₂salen)-based complexes [An(salen)₂] displays, on average, almost equal electron sharing of pyren or salen with the An^IV, pointing to a potential ligand-cage-driven complex stabilisation. This is shown in the fixed ligand arrangement of pyren and salen in the respective An^IV complexes. The overall bond strength of the pure N-donor ligand pyren to An^IV (An=Th, U, Np, Pu) is slightly weaker than to salen, with the exception of the Pa^IV complex, which exhibits extraordinarily high electron sharing of pyren with Pa^IV. Such an altered ligand preference within the early An^IV series points to a specificity of the 5f¹ configuration, which can be explained by polarisation effects of the 5 f electrons, allowing the strongest f electron backbonding from Pa^IV (5f¹) to the N donors of pyren.     

Improvement of Phase Change Materials (PCM) Used for Solar Process Heat Applications

The high intermittency of solar energy is still a challenge yet to be overcome. The use of thermal storage has proven to be a good option, with phase change materials (PCM) as very promising candidates. Nevertheless, PCM compounds have typically poor thermal conductivity, reducing their attractiveness for commercial uses. This paper demonstrates the viability of increasing the PCM effective thermal conductivity to industrial required values (around 4 W/m·K) by using metal wool infiltrated into the resin under vacuum conditions. To achieve this result, the authors used an inert resin, decoupling the specific PCM material selection from the enhancement effect of the metal wools. To ensure proper behavior of the metal wool under standard industrial environments at a broad range of temperatures, a set of analyses were performed at high temperatures and an inert atmosphere, presenting a thorough analysis of the obtained results.     

Modified Nucleosides,Nucleotides and Nucleic Acids via Click Azide-Alkyne Cycloaddition for Pharmacological Applications

The click azide = alkyne 1,3-dipolar cycloaddition (click chemistry) has become the approach of choice for bioconjugations in medicinal chemistry, providing facile reaction conditions amenable to both small and biological molecules. Many nucleoside analogs are known for their marked impact in cancer therapy and for the treatment of virus diseases and new targeted oligonucleotides have been developed for different purposes. The click chemistry allowing the tolerated union between units with a wide diversity of functional groups represents a robust means of designing new hybrid compounds with an extraordinary diversity of applications. This review provides an overview of the most recent works related to the use of click chemistry methodology in the field of nucleosides, nucleotides and nucleic acids for pharmacological applications.     

A nanoparticulate drug-delivery system for rivastigmine: physico-chemical and in vitro biological characterization

The preparation and characterization of surface-PEGylated polymeric nanoparticles are described. These systems were obtained by UV irradiation of PHM and PHM-PEG(2000) as an inverse microemulsion, using an aqueous solution of the PHM/PHM-PEG(2000) copolymer mixture as the internal phase and triacetin saturated with water as the external phase, and characterized by dimensional analysis, zeta-potential measurements and XPS. in vitro biological tests demonstrated their cell compatibility and their ability to escape from phagocytosis. Rivastigmine was encapsulated into the nanoparticle structure and drug-release profiles from loaded samples were investigated in PBS at pH = 7.4 and human plasma.     

Time of flight versus ion trap MS coupled to CE to analyse intact proteins

In this work, two different CE-MS instruments, namely, CE-ESI-IT-MS and CE-ESI-TOF-MS, applied to analyse intact proteins from complex samples are investigated. The aim of this work was to compare both instruments in terms of LOD, number of proteins detected, and precision and repeatability in the determination of the protein relative molecular mass. Results show that although CE-ESI-IT-MS provides cleaner MS spectra of intact proteins, CE-ESI-TOF-MS allows the identification of a higher number of proteins from complex matrices in an easier way. Performance in terms of peak area reproducibility, LOD and precision in the determination of the molecular mass were similar for both instruments. The usefulness of the optimised CE-ESI-IT-MS and CE-ESI-TOF-MS conditions was demonstrated by studying the zein-proteins composition of three natural maize lines and their corresponding transgenic lines, showing no significant differences.