Absorption spectrum of VO2+ in Na2Zn(SO4)2 · 4H2O single crystals

Optical absorption spectrum of VO²⁺ ion in sodium zinc sulphate tetrahydrate single crystal has been reported at room and liquid nitrogen temperatures. From the nature and position of the observed bands, they have been attributed to VO²⁺ ion in C_4v symmetry. The crystal field and molecular orbital coefficients have been evaluated.     

Optical absorption spectra of Nd2(SO4)38H2O complexes in solution

The values of Slater-Condon, spin-orbit, Racah, and Judd-Ofelt intensity parameters are reported. Observed energy levels and spectral intensities have been correlated with theoretically computed values. The nature of bonding in Nd³⁺ complexes is discussed. The oscillator strength of the hypersensitive transition decreases with a decrease of the Judd-Ofelt T₂ parameter.     

Canine Parvovirus Type 2a (CPV-2a)-Induced Apoptosis in MDCK Involves Both Extrinsic and Intrinsic Pathways

The canine parvovirus type 2 (CPV-2) causes an acute disease in dogs. It has been found to induce cell cycle arrest and DNA damage leading to cellular lysis. In this paper, we evaluated the apoptotic potential of the “new CPV-2a” in MDCK cells and elucidated the mechanism of the induction of apoptosis. The exposure of MDCK cells to the virus was found to trigger apoptotic response. Apoptosis was confirmed by phosphatidylserine translocation, DNA fragmentation assays, and cell cycle analysis. Activation of caspases-3, -8, -9, and -12 and decrease in mitochondrial potential in CPV-2a-infected MDCK cells suggested that the CPV-2a-induced apoptosis is caspase dependent involving extrinsic, intrinsic, and endoplasmic reticulum pathways. Increase in p53 and Bax/Bcl2 ratio was also observed in CPV-2a-infected cells.     

Beyond best effort: router architectures for the differentiatedservices of tomorrow's Internet

With the transformation of the Internet into a commercial infrastructure, the ability to provide differentiated services to users with widely varying requirements is rapidly becoming as important as meeting the massive increases in bandwidth demand. Hence, while deploying routers, switches, and transmission systems of ever increasing capacity, Internet service providers would also like to provide customer-specific differentiated services using the same shared network infrastructure. We describe router architectures that can support the two trends of rising bandwidth demand and rising demand for differentiated services. We focus on router mechanisms that can support differentiated services at a level not contemplated in proposals currently under consideration due to concern regarding their implementability at high speeds. We consider the types of differentiated services that service providers may want to offer and then discuss the mechanisms needed in routers to support them. We describe plausible implementations of these mechanisms (the scalability and performance of which have been demonstrated by implementation in a prototype system) and argue that it is technologically possible to considerably raise the level of differentiated services which service providers can offer their customers, and that it is not necessary to restrict differentiated services to rudimentary offerings even in very-high-speed networks     

Source models for VBR broadcast-video traffic

Traffic from video services is expected to be a substantial portion of the traffic carried by emerging broadband integrated networks. For variable bit rate (VBR) coded video, statistical source models are needed to design networks that achieve acceptable picture quality at minimum cost and to design traffic shaping and control mechanisms. For video teleconference traffic Heyman et al. (1992) showed that traffic is sufficiently accurately characterized by a multistate Markov chain model that can be derived from three traffic parameters (mean, correlation, and variance). The present authors describe modeling results for sequences with frequent scene changes (the previously studied video teleconferences have very little scene variation) such as entertainment television, news, and sports broadcasts. The authors analyze 11 long sequences of broadcast video traffic data. Unlike video teleconferences, the different sequences studied have different details regarding distributions of cells per frame. The authors present source models applicable to the different sequences and evaluate their accuracy as predictors of cell losses in asynchronous transfer mode (ATM) networks. The modeling approach is the same for all of the sequences but use of a single model based on a few physically meaningful parameters and applicable to all sequences does not seem to be possible     

A stochastic model for solidification

A 3-dimensional (2-space, 1-time) model relating the diffusion of heat and mass to the kinetic processes at the solid-liquid interface, using a stochastic approach is presented in this paper. This paper is divided in two parts. In the first part the basic set of equations describing solidification alongwith their analysis and solution are given. The process of solidification has a stochastic character and depends on the net probability of transfer of atoms from liquid to the solid phase. This has been modeled by a Markov process in which knowledge of the parameters at the initial time only is needed to evaluate the time evolution of the system. Solidification process is expressed in terms of four coupled equations, namely, the diffusion equations for heat and mass, the equations for concentration of the solid phase and for rate of growth of the solid-liquid interface. The position of the solid-liquid interface is represented with the help of a delta function and it is defined as the surface at which latent heat is evolved. A numerical method is used to solve the equations appearing in the model. In the second part the results i.e. the time evolution of the solid-liquid interface shape and its concentration, rate of growth and temperature are given.     

Optical absorption spectra of praseodymium acetate complexes in solution

Results of analyses of the solution spectra of Pr³⁺ in the acetates of praseodymium, magnesium, calcium and cadmium complexes are presented. Slater-Condon (F₂, F₄ and F₆), configurational interaction (α,β), spin-orbit (ξ_4f), nephelauxetic ($\text{β}$) bonding (δ) and Judd-Ofelt (T₂T₄ and T₆) intensity parameters are evaluated. Judd-Ofel intensity relationship has been used in the calculation of electric dipole line-strengths. Theoretical evaluation of predicted radiative lifetimes (τ_R) of the electronic excited states ³P₁, ³P₀ and ¹D₂ of Pr³⁺ in four diff been carried out.     

Optical absorption spectrum of PrCl3 complexes in solution

Optical spectral studies of Pr³⁺ in PrCl₃ complexes with MgCl₂, CaCl₂, CdCl₂ and NH₄Cl have been carried out, and the second derivative spectra of these five Pr³⁺ complexes are reported. From the observed features of the ³P₂ and ¹D₂ bands, crystal field (A₂₀, A₄₀) parameters were evaluated assuming C_3h symmetry for Pr³⁺ in these complexes. The Slater-Condon(F₂, F₄ and F₆), configuration interaction (α, β) and spin-orbit (ξ_4?), Racah (E¹,E² and E³), nephelauxetic (β), bonding (δ) and Judd-Ofelt (T₂, T₄ and T₆) intensity parameters are evaluated. Theoretical estimates of spectral intensities calculated from Judd-Ofelt and electric (S_ed)-magnetic (S_md) dipole linestrength methods are in good agreement with the observed values. The radiative lifetimes of elctronic excited states ³P₁, ³P₀, and ¹D₂ of Pr³⁺ in these five different hosts have been theoretically estimated.     

Cover Feature: Formation of Eigen or Zundel Features at Protonated Water Cluster–Aromatic Interfaces (ChemPhysChem 16/2023)

Interfacial interactions of protonated water clusters adsorbed at aromatic surfaces play an important role in biology, and in atmospheric, chemical and materials sciences. Here, we investigate the interaction of protonated water clusters ((H⁺H₂O)_n (where n=1–3)) with benzene (Bz), coronene (Cor) and dodecabenzocoronene (Dbc)). To study the structure, stability and spectral features of these complexes, computations are done using DFT-PBE0(+D3) and SAPT0 methods. These interactions are probed by AIM electron density topography and non-covalent interactions index (NCI) analyses. We suggest that the excess proton plays a crucial role in the stability of these model interfaces through strong inductive effects and the formation of Eigen or Zundel features. Also, computations reveal that the extension of the π-aromatic system and the increase of the number of water molecules in the H-bounded water network led to a strengthening of the interactions between the corresponding aromatic compound and protonated water molecules, except when a Zundel ion is formed. The present findings may serve to understand in-depth the role of proton localized at aqueous medium interacting with large aromatic surfaces such as graphene interacting with acidic liquid water. Besides, we give the IR and UV-Vis spectra of these complexes, which may help for their identification in laboratory.