A fuzzy stochastic model for telecommunications bandwidth brokers under probabilistic QoS measures

In this paper, we model and solve profit maximization problem of a telecommunications Bandwidth Broker (BB) under uncertain market and network infrastructure conditions. The BB may lease network capacity from a set of Backbone Providers (BPs) or from other BBs in order to gain profit by leasing already purchased capacity to end-users. BB’s problem becomes harder to deal with when bandwidth requests of end-users, profit and cost margins are not known in advance. The novelty of the proposed work is the development of a mechanism via combining fuzzy and stochastic programming methodologies for solving complex BP selection and bandwidth demand allocation problem in communication networks, based on the fact that information needed for making these decisions is not available prior to leasing capacity. In addition, suggested model aims to maximize BB’s decision maker’s satisfaction ratio rather than just profit. As a solution strategy, the resulting fuzzy stochastic programming model is transformed into deterministic crisp equivalent form and then solved to optimality. Finally, the numerical experiments show that on the average, proposed approach provides 14.30% more profit and 69.50% more satisfaction ratio compared to deterministic approaches in which randomness and vagueness in the market and infrastructure are ignored.     

Anchor Effect on Pedal Motion Observed in Crystal Phase of an Azobenzene Derivative

Abstract  

Some molecules having a molecular skeleton similar to that of stilbenes and azobenzenes show orientational disorder in the crystals due to pedal motion. Heretofore, the orientational disorder through pedal motion has been observed for the compounds containing only two aromatic rings in the absence of bulky substituent groups. Here we report that the pedal motion can be detected even in the presence of a bulky substituent group to which orientational disorder becomes invisible as a result of anchor effect arising from phenoxyphtalonitrile group. X-ray crystallographic analysis of the compound, C₂₃H₁₈N₄O, reveals the existence of partially overlapped two pedal conformers. The compound crystallizes in the monoclinic space group P2₁/c with a = 12.9429(11) Å, b = 8.5075(5) Å, c = 21.063(2) Å and β = 123.155(6)°. Major pedal conformer is stabilized by weak C–H···O type hydrogen bond and C–H···π type edge-to-face interactions in solid state. Quantum chemical calculations at B3LYP/6-311G+(d,p) level suggest that the stabilization of the compound decreases with increasing deviation from the planar geometry of trans-azobenzene fragment.     

Role of the n+1 amino acid residue on the deamidation of asparagine in pentapeptides

Deamidation plays an important role in biochemical phenomena such as aging. The role of the n + 1 residue on the deamidation of asparagine (asparagine being the nth residue) in three pentapeptide chains (GGNGG, GGNMG and GGNIG) has been analysed with hybrid computational tools. Potentials of mean force at 300 K were calculated from the MD/replica exchange simulations using weighted histogram analysis (WHAM) in explicit water. The snapshots were clustered taking into account the requirements of the plausible deamidation mechanisms, as such the tautomerisation of the asparagine side chain as initial step has been confirmed, based on the proximity of water to the deamidation site. The ultimate goal being to gain an insight on the peptide backbone N-H acidity, quantum mechanical calculations have been carried out. For this purpose, the distribution of Φ/Ψ, Φ₂/Ψ and end-to-end distances deduced from the WHAM diagrams have been considered and a total of 110 structures have been sampled. These neutral pentapeptides as well as their corresponding anions have been optimised (B3LYP/6-31++G(d,p)) in implicit water in order to gain an insight on the peptide backbone N-H acidity. In this study, we have shown that the open conformations of the neutrals and the anions, which display a β sheet like structure are well populated and their pK_as rank in the same order as the deamidating half-lives, that is the peptides that deaminate fastest can more readily access conformations that are more acidic.     

Electrochemical behavior of anthraquinone in aqueous solution in presence of a non-ionic surfactant

Cyclic voltammetric behavior of anthraquinone in aqueous medium has been studied in presence of a non-ionic surfactant, Triton X-100 (TX-100) using sodium salt of anthraquinone-2-sulphonic acid (AQS) as the electro-active species. When cathodic potential is applied, the anthraquinone (AQ) group of AQS is reduced to its dianion. In the reverse scan, the oxidation of AQ²⁻ gives AQ. The electrochemical behavior shows a profound influence from the dissolved state of TX-100 in aqueous media. Spectrophotometric results indicate interaction between AQ and TX-100. A CEC (chemical–electrochemical–chemical) mechanism with the electrochemical reaction coupled with preceding interaction of AQS with TX-100 and following protonation reaction of reduced AQ has been proposed.     

Synthesis and solution properties of a pH‐responsive cyclopolymer of zwitterionic ethyl 3‐(N,N‐diallylammonio)propanephosphonate

The zwitterionic monomer, ethyl 3‐(N,N‐diallylammonio)propanephosphonate, was cyclopolymerized in aqueous solutions using t‐butylhydroperoxide or ammonium persulfate as initiators to afford a polyphosphonobetaine (PPB). The protonation of P(?O)OEtO^– and deprotonation of ? NH⁺ groups in PPB by HCl and NaOH, gave the corresponding cationic polyphosphononic acid (CPP) and anionic polyphosphonate (APP). The presence of two pH‐responsive functionalities in APP has led to establish the equilibria: APP ? PPB ? CPP, the position of which very much dictates the viscosity behavior of its aqueous solution. The PPB demonstrated “antipolyelectrolyte” viscosity behavior; however, in contrast to many polycarbo‐ and polysulfo‐betaines, it was found to be soluble in salt‐free water as well as in salt‐added solutions. Basicity constant (K₁) of the amine group in APP, as determined by potentiometric technique, were found to be “apparent,” and as such followed the modified Henderson‐Hasselbalch equation. The study demonstrated a correlation between the basicity constants and viscosity values. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis,microwave‐promoted catalytic activity in Suzuki–Miyaura cross‐coupling reactions and antimicrobial properties of novel benzimidazole salts bearing trimethylsilyl group

A mixture of benzimidazole salts (2–7), Pd(OAc)₂ and K₂CO₃ in DMF–H₂O catalyzes the Suzuki–Miyaura cross‐coupling reactions promoted by microwave irradiation resulting in high yield within a short time. In particular, the yield of the Suzuki–Miyaura reactions with aryl bromides was found to be nearly quantitative. The synthesized benzimidazole salts (2–7) were identified by ¹H‐¹³C, NMR, IR spectroscopic methods and microanalysis. The molecular structure of 1 was determined by X‐ray crystallography. The antibacterial and antifungal activities of the novel benzimidazole derivatives (1–7) were also tested against standard strains. Copyright © 2011 John Wiley & Sons, Ltd.     

Comment on “Isobaric (vapour + liquid) equilibria for the (1-propanol + 1-butanol) binary mixture at (53.3 and 91.3) kPa”

The (vapor + liquid) equilibrium values reported by Mohsen-Nia and Memarzadeh appear to be flawed. In particular, neither the reported experimental activity coefficients are consistent with the reported composition data nor the reported model parameters can be used to adequately represent their experimental data.     

Effect of artificial mucus properties on the characteristics of airborne bioaerosol droplets generated during simulated coughing

The effect of viscoelastic properties and surface tension of artificial mucus simulant samples on the size distribution and volume concentration of bioaerosol droplets generated during simulated coughing was investigated through in vitro experiments. The mucus simulant samples had viscoelastic properties in a similar range as those of real human airway mucus. The mucus simulant gels were prepared by mixing various proportions of 0.5–1.7% locust bean gum solution and 0.1 M sodium tetraborate (XLB) solution. Surface tension of one set of samples was varied by adding different amounts of SDS (sodium dodecyl sulfate) surfactant while the measurement of surface tension was performed using ADSA (axisymmetric drop shape analysis) method. The viscoelastic properties of the samples were measured using a Bohlin Gemini 200 HR (Malvern, UK) nano-rheometer with peltier plate assembly. An artificial cough machine was used to simulate human cough, generating aerosol droplets in a model trachea attached to the front of the cough machine. The size distribution and volume concentration of the droplets generated through simulated cough were measured using a laser diffraction particle sizer (SprayTec, Malvern, USA). The surface tension was found to have negligible effect on the characteristic of generated droplets within the range of this investigation. The experimental results showed a decrease in particle size as the samples changed from a viscous fluid type to a viscoelastic to an elastic solid type sample. The volume concentration also changed significantly as the viscoelasticity of the samples was varied.     

The system of generalized vector equilibrium problems with applications

In this paper, we introduce the system of generalized vector equilibrium problems which includes as special cases the system of generalized implicit vector variational inequality problems, the system of generalized vector variational and variational-like inequality problems and the system of vector equilibrium problems. By using a maximal element theorem, we establish existence results for a solution of these systems. As an application, we derive existence results for a solution of a more general Nash equilibrium problem for vector-valued functions.