Synthesis of hyperbranched P poly(glycerol-diacid) oligomers

Novel oligomeric prepolymers were synthesized by acid-catalyzed condensation of glycerol with iminodiacetic, azelaic, or succinic acid. The prepolymers were obtained, on average, in 62% yield and were characterized by ¹³C NMR, ¹H NMR, matrix-assisted laser desorption ionization-time of flight-mass spectrometry, and gel permeation chromatography. The synthesized oligomers had an average M.W. of 1543 Daltons (average polydispersity (PD)=1.34, average degree of polymerization (DOP)=5.5). Hyperbranching was evident in the oligomers produced when using azelaic acid and succinic acid as co-monomers with glycerol, whereas the reaction between iminodiacetic acid and glycerol resulted in linear products bearing cyclic urethane structures.     

Electrosteric stabilization of concentrated cement suspensions imparted by a strong anionic polyelectrolyte and a non-ionic polymer

Strong polyelectrolytes, known as superplasticizers, improve the initial fluidity of concentrated cement suspensions through electrostatic stabilization. These polyelectrolytes do not maintain the initial fluidity, however, primarily due to an increase in the ionic strength of the cementitious suspension. Consequently, non-ionic polymers are often used in conjunction with polyelectrolytes to provide steric stabilization and hence to sustain the desired fluidity over a longer time, and this has lead to the development of copolymers with both electrostatic and steric (electrosteric) functionalities. To design such polymers, it is necessary to optimize the balance between electrostatic and steric stabilization to maximize suspension fluidity. We have quantified the effects of a strong anionic polyelectrolyte, melamine formaldehyde sulfonate (MFS), and a non-ionic polymer, hydroxypropylmethylcellulose (HPMC), on the zeta potential of cement particles and the steady shear and low-amplitude rheological properties of concentrated cement suspensions. While the adsorption of MFS onto the cement particle surfaces leads to a sign inversion in the zeta potential, the adsorption of the non-ionic HPMC has no significant effect on the potential. The addition of HPMC to the suspensions substantially reduces the steady shear viscosity and the storage modulus at constant MFS concentration; in addition, there exists an intermediate HPMC concentration that minimizes fluidity. The resulting suspension fluidity is also maintained over a longer time than in the absence of HPMC. This improvement in the stability and fluidity of cement suspensions is attributed to “complementary electrosteric dispersion/stabilization”, and provides insight to the design of polymers with electrosteric functionality.     

Pointillist video stylization based on particle tracing

We present an algorithm that stylizes an input video into a painterly animation without user intervention. In particular, we focus on pointillist animation with stable temporal coherence. Temporal coherence is an important problem in non-photorealistic rendering for videos. To realize pointillist animation, the various characters of pointillism should be considered in painting process to maintain temporal coherence. For this, weused the particle video algorithm which is a new approach to long-range motion estimation in video. Based on this method, we introduce a method to control the density of particles considering the features of frames and importance maps. Finally, the propagation methods of stroke to minimize flickering effects of brush strokes are introduced.     

Quantum correlations at negative absolute temperatures

We study behavior of quantum discord, a kind of quantum correlation, in systems of dipole–dipole interacting spins in an external magnetic field in the whole temperature range ( \(-\infty ). It was shown that negative temperatures, which are introduced to describe inversions in the population in a finite level system, provide more favorable conditions for emergence of quantum correlations including entanglement. We show that at negative temperature, the correlations become more intense and discord exists between remote spins being in separated states.     

The Influence of the Acid Sites on the Methylamines Synthesis with Cu-HZSM-5 Zeolite

There is a high industrial demand for MMA and DMA, however, the production of TMA is favored with the commercial catalysts. This work tested the methanol amination reaction with HZSM-5 and Cu/HZSM-5 zeolites (%Cu = 1.2, 3.7 and 6.0). Regarding the MMA selectivity, light differences were observed among Cu/HZSM-5 catalysts and pure zeolite, although the catalysts containing 3.7% copper was slightly more selective to MMA than the other metallic catalysts studied. From these results it is suggested that the metal loading present in the catalysts leads to a modification in the nature of the acidic sites, in particular, the selectivity depends on ratio Brönsted/Lewis acid sites. This modifications would facilitate the amines desorption during the reaction.     

Effects of a strong polyelectrolyte on the rheological properties of concentrated cementitious suspensions

Strong polyelectrolytes, referred to as superplasticizers, are known to improve the initial fluidity of concentrated cement suspensions. To quantify how the polyelectrolytes affect the fluidity, we have studied the effect of a strong anionic polyelectrolyte, melamine formaldehyde sulfonate (MFS), on the zeta potential of cement particles and on the steady-shear and low-amplitude rheological properties of cement suspensions. Adsorption of low concentrations of MFS onto the cement particles leads to an inversion in the sign of the surface potential, causing the electrostatically flocculated particles to become electrostatically dispersed and giving rise to a corresponding decrease in the steady-shear viscosity and storage modulus. At an intermediate MFS concentration, the steady-shear viscosity and the storage modulus each display a minimum. This concentration corresponds to that at which the zeta potential becomes constant. Larger concentrations of MFS result in an increase in the viscosity and storage modulus, which is attributed to depletion flocculation. These results thus relate the interaction between particles to the suspension fluidity through the analysis on the surface potential of particles and microstructure of suspension.     

Model reduction based on limited‐time interval impulse response Gramians

In this paper, three new Gramians are introduced namely ‐ limited‐time interval impulse response Gramians (LTIRG), generalized limited‐time Gramians (GLTG) and generalized limited‐time impulse response Gramians (GLTIRG). GLTG and GLTIRG are applicable to both unstable systems and also to systems which have eigenvalues of opposite polarities and equal magnitude. The concept of these Gramians is utilized to develop model reduction algorithms for linear time‐invariant continuous‐time single‐input single‐output (SISO) systems. In the cases of GLTIRG and GLTG based model reduction, the standard time‐limited Gramians are generalized to be applied to unstable systems by transforming the original system into a new system which requires the solution of two Riccati equations. Two numerical examples are included to illustrate the proposed methods. The results are also compared with standard techniques.     

Optimization of the in Situ Transesterification of Grain Sorghum (Milo) DDGS to Fatty Acid Methyl Esters and Fatty Acid Ethyl Esters

Distillers grains and solubles generated from the ethanol fermentation of grains contain acylglycerols (AG) that can be successfully converted to fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAEE), commonly known as biodiesel. However, when grain sorghum (milo) DDGS were used as a feedstock for in situ transesterification (IST) under the previously established optimal conditions for other AG-bearing substrates, the yield plateaued at only 32.2% (corrected in this study to 24.2%). Several IST studies have reported significantly higher conversions of AG-bearing substrates to FAME. Therefore, the goal of this IST study was to improve the conversion of the AG in milo DDGS to FAME and FAEE by varying the temperature of reaction, the concentrations of the base (sodium methylate, NaOMe), volume of methanol and ethanol, and the amount of moisture in DDGS. Methyl tert-butyl ester was also evaluated as a co-solvent intended to improve miscibility and reaction rate. Among these variables, the most effective change was an increase in temperature from 40 to 65 °C. The most successful reaction used a AG:NaOMe:MeOH molar ratio of 1.0:2.6:168.9. Those reaction conditions used 4.8 mmol NaOMe dissolved in 12.6 mL MeOH and resulted in a 79.8% conversion of AG to FAME.     

Exploring cell tower data dumps for supervised learning-based point-of-interest prediction (industrial paper)

Exploring massive mobile data for location-based services becomes one of the key challenges in mobile data mining. In this paper, we investigate a problem of finding a correlation between the collective behavior of mobile users and the distribution of points of interest (POIs) in a city. Specifically, we use large-scale cell tower data dumps collected from cell towers and POIs extracted from a popular social network service, Weibo. Our objective is to make use of the data from these two different types of sources to build a model for predicting the POI densities of different regions in the covered area. An application domain that may benefit from our research is a business recommendation application, where a prediction result can be used as a recommendation for opening a new store/branch. The crux of our contribution is the method of representing the collective behavior of mobile users as a histogram of connection counts over a period of time in each region. This representation ultimately enables us to apply a supervised learning algorithm to our problem in order to train a POI prediction model using the POI data set as the ground truth. We studied 12 state-of-the-art classification and regression algorithms; experimental results demonstrate the feasibility and effectiveness of the proposed method.