Microdroplet size prediction in microfluidic systems via artificial neural network modeling for water-in-oil emulsion formulation

In this paper, an experimental study and modeling by artificial neural networks were carried out to predict the generated microdroplet dimensionless size in a microfluidic system in order to formulate a water-in-oil emulsion. The various parameters that affect the size of microdroplets (flow rates, viscosities, surface tensions of both the two phases and the diameter of the microchannel) are studied and further grouped into dimensionless numbers; we used these numbers as input to the neural network and the dimensionless length as output. The better neural network architecture has 10 neurons in the hidden layer with a mean square error of 1.4 10^?6 and a determination’s coefficient near 1 value. The relative importance of inputs on the size of the microdroplets has been determined using the Garson algorithm and the results are in good agreement with other works.     

Fast and Efficient Nitration of Salicylic Acid and Some Other Aromatic Compounds over H_3PO_4/TiO_2-ZrO_2 Using Nitric Acid

TiO₂‐ZrO₂ (1/1)‐surf with Ti and Zr molar ratio of 1/1 was prepared with surfactant through a sol‐gel method. The optimum experimental condition was investigated for nitration of salicylic acid. Then, a number of nitration reactions were carried out with a variety of aromatic compounds in the optimum condition. The 25 wt% H₃PO₄/TiO₂‐ZrO₂ (1/1)‐surf catalyst showed good selectivity and yield in a short time for the nitration of salicylic acid and some other aromatic compounds.     

Synthesis,structural characterization and alcohol oxidation activity of a new mononuclear manganese(II) complex

A manganese(II) complex of 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) has been synthesized and characterized by single-crystal X-ray diffraction, elemental analyses, IR, and UV–Vis spectroscopic techniques. Oxidation of alcohols to their corresponding aldehydes and ketones was conducted by this catalyst using oxone (2KHSO₅·KHSO₄·K₂SO₄) as an oxidant under biphasic reaction conditions (CH₂Cl₂/H₂O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature. Easy preparation, mild reaction conditions, high yields of the products, short reaction times, no further oxidation to the corresponding carboxylic acids, high selectivity and inexpensive reagents make this catalytic system a useful oxidation method for aliphatic and benzylic alcohols.     

New coumarin-hemiterpene ether glucosides and a structurally related phenylpropanoic acid derivative from Artemisia armeniaca

Two new coumarin-hemiterpene ether glucosides, 4'-O-(beta-D-glucopyranosyl) desoxylacarol (1), and 5-O-(beta-D-glucopyranosyl) lacarol (2), were isolated from the methanolic extract of the aerial parts of Artemisia armeniaca Lam. Their structures were established by means of spectroscopic analysis including 1H- and 2D-NMR, HRESIMS, and acid hydrolysis. In addition, a structurally related phenylpropanoic acid derivative (3) was obtained in small amounts, and its structure tentatively assigned as 3-(4-hydroxy-3-methylbutoxy)-4-methoxy melilotic acid.     

Surface-induced phase transformations: multiple scale and mechanics effects and morphological transitions

Strong, surprising, and multifaceted effects of the width of the external surface layer Δ(ξ) and internal stresses on surface-induced pretransformation and phase transformations (PTs) are revealed. Using our further developed phase-field approach, we found that above some critical Δ(ξ)(*), a morphological transition from fully transformed layer to lack of surface pretransformation occurs for any transformation strain ε(t). It corresponds to a sharp transition to the universal (independent of ε(t)), strongly increasing the master relationship of the critical thermodynamic driving force for PT X(c) on Δ(ξ). For large ε(t), with increasing Δ(ξ), X(c) unexpectedly decreases, oscillates, and then becomes independent of ε(t). Oscillations are caused by morphological transitions of fully transformed surface nanostructure. A similar approach can be developed for internal surfaces (grain boundaries) and for various types of PTs and chemical reactions.     

Polynomial integrability of the Hamiltonian systems with homogeneous potential of degree − 3

In this paper, we study the polynomial integrability of natural Hamiltonian systems with two degrees of freedom having a homogeneous potential of degree k given either by a polynomial, or by an inverse of a polynomial. For k=−2,−1,…,3,4, their polynomial integrability has been characterized. Here, we have two main results. First, we characterize the polynomial integrability of those Hamiltonian systems with homogeneous potential of degree −3. Second, we extend a relation between the nontrivial eigenvalues of the Hessian of the potential calculated at a Darboux point to a family of Hamiltonian systems with potentials given by an inverse of a homogeneous polynomial. This relation was known for such Hamiltonian systems with homogeneous polynomial potentials. Finally, we present three open problems related with the polynomial integrability of Hamiltonian systems with a rational potential.     

Preparation of polybutylene terephthalate/silica nanocomposites by melt compounding: Evaluation of surface properties

Influence of nanosilica on surface properties of poly(butylene terephthalate) was investigated by the use of Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurement (CAM), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). FTIR results indicated that surface groups of silica have some interfacial interactions and bonding with carboxyl or hydroxyl end groups of PBT chains. AFM and SEM figures of the resultant nanocomposites illustrated increased surface roughness compared to pure PBT. Optical properties of nanocomposite films were finally determined by the aid of reflectance spectrophotometer.     

An experimental study towards micro-mechanical modeling of fiber-reinforced aerogels

Fiber-reinforced aerogels are a class of reinforced aerogels characterized by very low thermal conductivity, hydrophobicity and most importantly load bearing capability. In this work, an experimental study describing the damage in these fiber-reinforced aerogels through various uniaxial compression tests is presented. While understanding the damage evolution at the micro-scale, we come across three probable sources contributing towards the damage evolution. They are: (a) matrix cracks, (b) debonding of particles due to fiber sliding, and (c) breakage of fibers. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Linearization-based algorithms for mixed-integer nonlinear programs with convex continuous relaxation

We present two linearization-based algorithms for mixed-integer nonlinear programs (MINLPs) having a convex continuous relaxation. The key feature of these algorithms is that, in contrast to most existing linearization-based algorithms for convex MINLPs, they do not require the continuous relaxation to be defined by convex nonlinear functions. For example, these algorithms can solve to global optimality MINLPs with constraints defined by quasiconvex functions. The first algorithm is a slightly modified version of the LP/NLP-based branch-and-bouund \((\text{ LP/NLP-BB })\) algorithm of Quesada and Grossmann, and is closely related to an algorithm recently proposed by Bonami et al. (Math Program 119:331–352, 2009). The second algorithm is a hybrid between this algorithm and nonlinear programming based branch-and-bound. Computational experiments indicate that the modified LP/NLP-BB method has comparable performance to LP/NLP-BB on instances defined by convex functions. Thus, this algorithm has the potential to solve a wider class of MINLP instances without sacrificing performance.