Nonclassical Features of Intra-Cavity and Transmitted Fields in a Coherently-Pumped Correlated-Emission Laser with Injected Thermal Light†

Journal of Russian Laser Research - We discuss effects of phase fluctuations and thermal light on the entanglement, squeezing, and intensity of the two-mode intra-cavity and transmitted fields...     

Probabilistic Inductive Classes of Graphs

A unifying framework—probabilistic inductive classes of graphs (PICGs)—is defined by imposing a probability space on the rules and their left elements from the standard notion of inductive class of graphs. The rules can model the processes creating real-world social networks, such as spread of knowledge, dynamics of acquaintanceships or sexual contacts, and emergence of clusters. We demonstrate the characteristics of PICGs by casting some well-known models of growing networks in this framework. Results regarding expected size and order are derived. For PICG models of connected and 2-connected graphs order, size and asymptotic degree distribution are presented. The approaches used represent analytic alternative to computer simulation, which is mostly used to obtain the properties of evolving graphs.     

Microfluidic synthesis of advanced microparticles for encapsulation and controlled release

We describe droplet microfluidic strategies used to fabricate advanced microparticles that are useful structures for the encapsulation and release of actives; these strategies can be further developed to produce microparticles for advanced drug delivery applications. Microfluidics enables exquisite control in the fabrication of polymer vesicles and thermosensitive microgels from single and higher-order multiple emulsion templates. The strategies used to create the diversity of microparticle structures described in this review, coupled with the scalability of microfluidics, will enable fabrication of large quantities of novel microparticle structures that have potential uses in controlled drug release applications.     

Air-bubble-triggered drop formation in microfluidics

In microfluidic devices, droplets are normally formed using T-junction or flow focus mechanisms. While both afford a high degree of control over drop formation, they are limited in maximum production rate by the jetting transition. Here, we introduce a new drop formation mechanism that is not limited by jetting, allowing much faster drop production.     

Thermal degradation of differently substituted Cyclopentyl Polyhedral Oligomeric Silsesquioxane (CP-POSS) nanoparticles

Seven variously substituted derivatives of polyhedral oligomeric silsesquioxanes (POSSs) with general formula R₇R′₁ (SiO_1.5)₈, where R- and R′- were a cyclopentyl and a substituted phenyl group, respectively, were prepared in this study, and their compositions were checked by elemental analysis, ¹ H NMR and ¹³ C NMR spectroscopy. The compounds obtained were studied by TG and DTA techniques, in both flowing nitrogen and static air atmospheres, to draw useful information about their resistance to thermal degradation. Experiments, performed in the 35–700 °C temperature range, showed different behaviours between the two used atmospheres. The formation of volatile compounds only, with a near-complete mass loss, was observed under nitrogen; by contrast, in oxidative environment, a solid residue (≈50% in every case) was obtained because of the formation of SiO₂ as indicated by the FTIR spectra performed. The results obtained for the various compounds investigated were discussed and compared with each other, and heat resistance classifications in the studied environments were made.     

Steering in computational science: Mesoscale modelling and simulation

This paper outlines the benefits of computational steering for high performance computing applications. Lattice-Boltzmann mesoscale fluid simulations of binary and ternary amphiphilic fluids in two and three dimensions are used to illustrate the substantial improvements which computational steering offers in terms of resource efficiency and time to discover new physics. We discuss details of our current steering implementations and describe their future outlook with the advent of computational grids.     

First integrals and analytical solutions of the nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient

Fin materials can be observed in a variety of engineering applications. They are used to ease the dissipation of heat from a heated wall to the surrounding environment. In this work, we consider a nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient. The equation(s) under study are highly nonlinear. Both the thermal conductivity and the heat transfer coefficient are given as arbitrary functions of temperature. Firstly, we consider the Lie group analysis for different cases of thermal conductivity and the heat transfer coefficients. These classifications are obtained from the Lie group analysis. Then, the first integrals of the nonlinear straight fin problem are constructed by three methods, namely, Noether’s classical method, partial Noether approach and Ibragimov’s nonlocal conservation method. Some exact analytical solutions are also constructed. The obtained result is also compared with the result obtained by other methods.     

Identification of unsaturated N-acylhomoserine lactones in bacterial isolates of Rhodobacter sphaeroides by liquid chromatography coupled to electrospray ionization-hybrid linear ion trap-Fourier transform ion cyclotron resonance mass spectrometry

The identification of two unsaturated N‐acylhomoserine lactones (AHLs) produced by Rhodobacter sphaeroides bacteria, based on liquid chromatography (LC) coupled to a hybrid quadrupole linear ion trap (LTQ)‐Fourier transform ion cyclotron resonance (FTICR) mass spectrometer upon electrospray ionization (ESI), is presented. Besides the confirmation of the signaling molecule already described in the literature, i.e. (Z)‐N‐tetradec‐7‐enoyl‐homoserine lactone (C_14:1‐HSL), we have discovered the occurrence, at low, yet significant levels, of another monounsaturated compound, C_12:1‐HSL, which may extend the number of small diffusible chemical signals known for R. sphaeroides. Both unsaturated AHLs were identified by high‐resolution FTICR mass spectrometry in extracts of bacterial culture media and the occurrence of a C=C bond was assessed upon their conversion into bromohydrins. Collision‐induced dissociation (CID) spectra were then collected on the LTQ mass analyzer. A careful comparison of tandem MS spectra of monounsaturated (i.e., C_12:1‐HSL and C_14:1‐HSL) and saturated AHLs (i.e. C₁₂‐HSL and C₁₄‐HSL) led to the emphasis of two series of product ions, exhibiting 14 Da spaced m/z ratios. Both series were referred to progressive fragmentations at the aliphatic end of the AHL acyl chains, followed by neutral losses of terminal alkenes (i.e. CH₂=CH(CH₂)_nH). In particular, the series located at the higher end of the explored m/z range (>200 Da), observed only for monounsaturated species, enabled the location of the C=C bond between carbons 7 and 8 of the acyl chain. Copyright © 2011 John Wiley & Sons, Ltd.     

Variously substituted phenyl hepta cyclopentyl-polyhedral oligomeric silsesquioxane (ph,hcp-POSS)/polystyrene (PS) nanocomposites

A comparative study concerning the thermal stability of polystyrene (PS) and six POSS/PS nanocomposites of general formula R₇R′(SiO_1.5)₈/PS (where R = cyclopentyl and R′ = phenyl, 4-methoxyphenyl, 4-tolyl, 3,5-xilyl, 4-fluorophenyl, and 2,4-difluorophenyl) was carried out in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Nanocomposites were prepared by in situ polymerization of styrene in the presence of 5 % w/w of POSS, but the actual filler concentration in the obtained nanocomposites, determined by ¹H NMR spectroscopy, was in all cases slightly higher than that in the reactant mixtures. FTIR spectra of nanocomposites evidenced the presence of filler-polymer interactions. Inherent viscosity (η _inh) determinations indicated that the average molar mass of polymer in methylated and fluorinated derivatives was lower than neat PS, and were in agreement with calorimetric glass transition temperature (T _g) measurements. Degradations were performed into a thermobalance, in the scanning mode, at 10 °C min^?1, and the temperatures at 5 % mass loss (T _5 %), of various nanocomposites were determined. The effects of various substituents of the POSS phenyl group on the thermal stability of nanocomposites were evaluated. The results were discussed and interpreted.     

The regression of isothermal thermogravimetric data to evaluate degradation Ea values of polymers: A comparison with literature methods and an evaluation of lifetime predictions reliability. Part II

The kinetics of the isothermal degradation in static air atmosphere of four well known polymers, polyethylene (PE), polystyrene (PS), polycarbonate (PC) and poly(methyl methacrylate) (PMMA) was studied by both a long-term (more than three years) experiment at relatively low temperature (423 K) and a set of short-term experiments at higher temperatures. The activation energy (E_a) values of degradation were determined by both the MacCallum and Wilkinson literature methods, and were compared with those obtained through a new very simple method we set up, based on the direct regression of TG mass loss data. About two years ago we published the results concerning PE and PS because their mass losses during long-term experiments were sufficiently high. The long-term degradation experiments were continued until now and in this second part we report the results concerning PC and PMMA. The degradation E_a values calculated from short-term experimental data through the three different methods were in good agreement with each other for both PC and PMMA, thus confirming the general applicability of our simple method for the determination of E_a. The experimental data at lower temperature of PC were not in agreement with those at higher temperatures, thus confirming the low reliability of the kinetic parameters (and then of lifetime predictions) at low temperature determined by experiments at higher temperatures. Partially disagreeing results were obtained for PMMA, which were discussed and interpreted.