Inertia effects as a possible missing link between micro and macro second-order work in granular media

This paper is concerned with a theoretical question as to the definition of instabilities in a granular assembly and its proper formulation at the microscopic level. Recently, this question has taken up much prominence with the emergence of intriguing failure modes such as diffuse failure associated to unstable plasticity of granular materials and microstructural instabilities. An analysis of the second-order work as a general and necessary criterion to detect instabilities is conducted both at the macroscopic and microscopic levels including large deformations. On the basis of a micromechanical analysis of a body consisting of arbitrary interacting particles in a representative element volume (REV), a general formula is derived to quantify the microscopic second-order work involving local variables on the grain scale. The latter emerges as a sum of a configurational term that involves contact forces between neighboring grains, plus a kinetic part consisting of the mechanical unbalance of intergranular forces under dynamics at incipient failure. The present analysis is thought to serve as a clarification of the question of failure in geomaterials typified by a transition from static to a dynamic regime with release of kinetic energy originating from microstructural interactions.     

Design,synthesis and anticoagulant activity of new flexible calix[8]arene sulfonic acids

Four new calix[8]arene sulfonic acids (2a-b, 3a-b) were synthesized. The anticoagulant activity and POM virtual screening of these flexible calixarenes have been established.     

Static hybrid amplify and forward (AF) and decode and forward (DF) relaying for cooperative systems

In this paper, we propose a static hybrid amplify and forward (AF) and decode and forward (DF) relaying protocol for cooperative systems. In such a scheme, relays close to the source amplify the received signal whereas the remaining relays transmit only if they decode correctly. We consider two subclasses of the proposed hybrid AF–DF relaying protocol. In the first one, all AF relays and DF relays that have decoded correctly transmit using orthogonal channels. The second protocol, called opportunistic hybrid AF–DF relaying, consists in activating only the relay offering the highest instantaneous signal to noise ratio (SNR) among AF relays and the relays that have decoded correctly. The outage SNR probability, and the exact and asymptotic bit error probability (BEP) values of both all-participating and opportunistic hybrid AF–DF relaying protocols are derived and compared to conventional AF and DF relaying. The proposed protocol offers better performance than AF relaying and similar performance to DF relaying with a lower computational complexity. Simulation results are also provided to verify the tightness of the derived results.     

Study of dynamic structure and heat and mass transfer of a vertical ceramic tiles dryer using CFD simulations

In this study, we developed a two-dimensional Computational Fluid Dynamics (CFD) model to simulate dynamic structure and heat and mass transfer of a vertical ceramic tiles dryer (EVA 702). The carrier’s motion imposed the choice of a dynamic mesh based on two methods: “spring based smoothing” and “local remeshing”. The dryer airflow is considered as turbulent (Re = 1.09 × 10⁵ at the dryer inlet), therefore the Re-Normalization Group $k - \in$ model with Enhanced Wall Treatment was used as a turbulence model. The resolution of the governing equation was performed with Fluent 6.3 whose capacities do not allow the direct resolution of drying problems. Thus, a user defined scalar equation was inserted in the CFD code to model moisture content diffusion into tiles. User-defined functions were implemented to define carriers’ motion, thermo-physical properties… etc. We adopted also a “two-step” simulation method: in the first step, we follow the heat transfer coefficient evolution (H_c). In the second step, we determine the mass transfer coefficient (H_m) and the features fields of drying air and ceramic tiles. The found results in mixed convection mode (Fr = 5.39 at the dryer inlet) were used to describe dynamic and thermal fields of airflow and heat and mass transfer close to the ceramic tiles. The response of ceramic tiles to heat and mass transfer was studied based on Biot numbers. The evolutions of averages temperature and moisture content of ceramic tiles were analyzed. Lastly, comparison between experimental and numerical results showed a good agreement.     

State space approach to unsteady magnetohydrodynamics natural convection heat and mass transfer through a porous medium saturated with a viscoelastic fluid

A technique of the state space approach and the inversion of the Laplace transform method are applied to dimensionless equations of an unsteady one-dimensional boundary-layer flow due to heat and mass transfer through a porous medium saturated with a viscoelastic fluid bounded by an infinite vertical plate in the presence of a uniform magnetic field is described. Complete analytical solutions for the temperature, concentration, velocity, and induced magnetic and electric fields are presented. The inversion of the Laplace transforms is carried out by using a numerical approach. The proposed method is used to solve two problems: boundary-layer flow in a viscoelastic fluid near a vertical wall subjected to the initial conditions of a stepwise temperature and concentration and viscoelastic fluid flow between two vertical walls. The solutions are found to be dependent on the governing parameters including the Prandtl number, the Schmidt number, the Grashof number, reaction rate coefficient, viscoelastic parameter, and permeability of the porous medium. Effects of these major parameters on the transport behavior are investigated methodically, and typical results are illustrated to reveal the tendency of the solutions. Representative results are presented for the velocity, temperature, concentration, and induced magnetic and electric field distributions, as well as the local skin-friction coefficient and the local Nusselt and Sherwood numbers.     

Studies on the Reactivity of Amino‐1‐(6‐phenyl‐pyridazin‐3‐yl)‐1H‐pyrazole‐4‐carboxylic Acid Hydrazide Towards Some Reagents for Biological Evaluation

Novel 5‐amino‐1‐(6‐phenyl‐pyridazin‐3‐yl)‐1H‐pyrazole‐4‐carboxylic acid ethyl ester ( 2 ) was formed using (6‐phenyl‐pyridazin‐3‐yl)‐hydrazine ( 1 ) and ethyl(ethoxymethylene)cyanoacetate. The β‐enaminoester derivative 2 was in turn used as precursor for the preparation of 1‐(6‐phenyl‐pyridazin‐3‐yl)‐pyrazoles ( 3 , 4 , 7 , 8 , 9 , 10 , 11 , 12 , 15 , 16 ), 1‐(6‐phenyl‐pyridazin‐3‐yl)‐pyrazolo[3,4‐d]pyrimidines ( 5 , 6 , 14 ) and 1‐(6‐phenyl‐pyridazin‐3‐yl)‐pyrazolo[3,4‐d][1,2,3]triazine ( 13 ). The in vitro antimicrobial activity of the synthesized compounds was evaluated by measuring the inhibition zone diameters where some of them showed potent antimicrobial activity in compared with well‐known drugs (standards).     

The Two-stage Assembly Flow Shop Scheduling with an Availability Constraint: Worst Case Analysis

In this paper, we are interested in handling the limited availability of machines in the two-stage assembly flow shop scheduling problems. Emphasis is put on the semiresumable case with respect to the minimization of the makespan. We provide, when possible, heuristics with a tight worst-case ratio bound of 2.     

Theoretical Calculations and Experimental Verification of the Antibacterial Potential of Some Monocyclic β-Lactams Containing Two Synergetic Buried Antibacterial Pharmacophore Sites

A new series of N-thiazole, 3-phenyl, 4-substituted phenyl azetidine-2-ones 4(a–h) have been synthesized in good yields starting from 2-aminothiazole 1. In the first step, then Schiff's bases 3(a–h) are prepared by the condensation of 2-aminothiazole 1 with different aryl aldehydes 2(a–h). Finally, monocyclic β-lactams, i.e. substituted azetidinones 4(a–h), were the products formed using three different methods by the dehydrative cyclocondensation of 3(a–h) with phenyl acetyl chloride in dioxane, phenyl acetic acid–thionyl chloride in dichloromethane and phenyl acetic acid–phosphorus oxychloride in dichloromethane in the presence of triethylamine. We found that latter method is the best as compared with the former two methods. The synthesized molecules 4(a–h) were screened for their antibacterial activity against four microorganisms: Staphylococcus aureus (Gram positive), Pseudomonas vulgaris (Gram positive), Pseudomonas aeruginosa (Gram negative), and Escherichia coli (Gram negative). Their antibacterial activities are reported, and on the basis of the screening data available, attempt is also made to elucidate the structure–activity relationship.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Photochemical isomerization of norbornadiene‐containing polytriazoles obtained by click chemistry polyaddition

Polyesters and polyethers containing norbornadiene (NBD) and 1,2,3‐triazole units in the main chain are prepared by step growth polymerization of diester or diether NBD‐based dialkynes with different aromatic diazides using copper‐catalyzed azide–alkyne cycloaddition. The solubility and the physical properties of the resulting polytriazoles are investigated by differential scanning calorimetry, thermogravimetric analysis, size exclusion chromatography, and ¹H NMR spectroscopy, and are discussed taking into account of the chemical structures of the monomers. All of them are amorphous with glass transition temperatures ranging from 51 to 117 °C, number average molecular weight (M_n) values from 16 to 43 kDa and thermal degradation (T_d10) values from 175 to 292 °C. The photochemical valence isomerization (PVI) of the NBD units into quadricyclanes (QC) is investigated using UV–vis spectroscopy of polymer films spin‐coated onto quartz substrates. For the first time the PVI of NBD into QC is demonstrated by ¹H NMR spectroscopy. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 223–231     

Astroparticle physics: Working group report

The astroparticle physics working group witnessed intense discussion and activity covering a broad range of topics ranging from supergravity and baryogenesis to compact stars and the large scale structure of the Universe. A summary of some of the subject areas in which collaborations were initiated during WHEPP-5 is presented below.