Starch sulfate as an efficient and biodegradable polymer catalyst for one‐pot,four‐component reaction of 2H‐indazolo[2,1‐b]phthalazine‐triones

A practical and green method for the synthesis of 2H‐indazolo[2,1‐b]phthalazine‐1,6,11(13H)‐trione derivatives using starch sulfate as a solid acid catalyst for the four‐component condensation reaction from hydrazinium hydroxide, phthalic anhydride, dimedone, and aromatic aldehydes under thermal solvent‐free conditions is described for the first time. Starch sulfate, a recyclable and easily handled catalyst has been demonstrated as a new catalyst for the synthesis of these classes of compounds.     

Characteristic intervals in suspension polymerisation reactors: An experimental and modelling study

Suspension polymerisation of methyl methacrylate was carried out as a model to elaborate on the evolution of particle size average and distribution in the course of polymerisation. Four characteristic intervals in the evolution of particle size were identified as: transition, quasi-steady-state, growth, and identification stages. The effects of stabiliser and initiator concentrations, monomer hold up, reaction temperature, and agitation speed on the characteristic intervals, as well as the kinetics of polymerisation, were examined. The transition stage, which has been totally ignored in the literature, was found to have significant effect on the evolution of particle size. The transition stage is shortened by increasing the rate of polymerisation in the drops (either by increasing initiator concentration or using a higher reaction temperature). Increasing the impeller speed and stabiliser concentration will also lead to a shorter transition period. However, the delayed adsorption of the stabiliser on the surface of drops will prolong the transition stage. It is shown that the occurrence of the quasi-steady state depends on the polymerisation conditions. The quasi-steady state occurs only if the balance between drop break up and coalescence can be maintained. This requires a high rate of drop break up within a period of time during polymerisation (i.e., a low rate of polymerisation in the drops by using a low initiator concentration and reaction temperature, a high agitation speed and a high stabiliser concentration). The mechanisms underlying the growth stage are explained in terms of the overall rates of drop break up and coalescence in the course of polymerisation reactions. It is also shown that the onset of growth stage cannot be defined in terms of a critical conversation or viscosity, and it depends on the polymerisation conditions including mixing. The growth stage occurs if drops are not sufficiently stable against both break up and coalescence. The onset of the growth stage is advanced with a decrease in the rate of drop break up (e.g., decreasing agitation speed and stabiliser concentration). The growth stage can be totally eliminated from a polymerisation process if dispersions with a static steady state can be formed. That requires a high concentration of stabiliser, or a low concentration of monomer, to be used. A population balance model, which included the transition stage and the delayed adsorption of the stabiliser, was developed that is capable of predicting the evolution of drop size in the suspension polymerisation.     

Convenient synthesis of benzoate esters mediated by polymer supported benzoyl chloride

Use of polymeric reagents simplifies routine acylation of alcohols because it eliminates traditional purification. We describe the use of readily available crosslinked poly(N‐benzoyl‐4‐vinylpyridinium)chloride, [P₄VP] COPh, in the solution phase synthesis of esters from alcohols or phenols in the presence of K₂CO₃ in high yields and purity. The products can be obtained by filtration and evaporation of the solvent and the polymeric reagent can be regenerated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A biological multiplexer,designs, and simulations

Biological circuits can be used in synthetic biology to perform logical functions similar to those observed in electronic circuits. These circuits are applied as a method to define cellular functions in useful ways. The purpose of this field of research is to design and simulate systems which can combine VLSI technology and biological circuits. In this regard, five different architectures (AND–OR, AND–NOR–OR–AND Full-NAND, and Full-NOR) of a new biomultiplexer have been designed and simulated. The results of these architectures are compared in terms of delay as well as the number of promoters and genes. The two-level architectures AND–OR, AND–NOR, and OR–AND, in addition to the greater number of genes and promoters, have also a longer execution time than the designs with two universal NAND or NOR gates. In Full-NAND design, the execution time is reduced by lowering the number of genes and the number of promoters. Finally, Full-NOR design offers the shortest execution time of 0.612 s, while reducing promoters by 64% and the number of genes by 50%, compared to other proposed architectures.

     

K-DBSCAN: An improved DBSCAN algorithm for big data

The Journal of Supercomputing - Big data storage and processing are among the most important challenges now. Among data mining algorithms, DBSCAN is a common clustering method. One of the most...     

Investigation of Rainfall Forecast System Characteristics in Real-Time Optimal Operation of Urban Drainage Systems

This study investigates the role of rainfall forecast system characteristics in predictive real-time optimal operation (PRTOP) of urban drainage systems (UDSs). A simulation-optimization model is proposed integrating the stormwater management rainfall-runoff simulator, the harmony search optimization algorithm, and a rainfall forecasting module. This module generates different rainfall forecast scenarios depending on the forecast (time) horizon (FH) and the forecast type (perfect or imperfect). Five adaptive PRTOP models are compared to evaluate the relationships between the FH, forecast type, and the system’s relative regulating capacity (SRRC). The models are tested in a part of UDS of Tehran, capital of Iran. Results indicate that for the studied system, perfect knowledge of future rainfall is more beneficial for a specific range of the SRRC, equal to 80–90% of its upper bound. Besides, the performance of the PRTOP model improves with increasing the FH up to a certain point, and then having no further positive effect. Finally, the PRTOP model equipped with a hypothetical forecasting model where the forecast error is a nonlinear function of the forecast lead time still performs better than both a zero-FH reactive RTOP model and short forecast horizon PRTOP models.

     

Salient object detection method using random graph

In this paper, a bottom-up salient object detection method is proposed by modeling image as a random graph. The proposed method starts with portioning input image into superpixels and extracting color and spatial features for each superpixel. Then, a complete graph is constructed by employing superpixels as nodes. A high edge weight is assigned into a pair of superpixels if they have high similarity. Next, a random walk prior on nodes is assumed to generate the probability distribution on edges. On the other hand, a complete directed graph is created that each edge weight represents the probability for transmitting random walker from current node to next node. By considering a threshold and eliminating edges with higher probability than the threshold, a random graph is created to model input image. The inbound degree vector of a random graph is computed to determine the most salient nodes (regions). Finally, a propagation technique is used to form saliency map. Experimental results on two challenging datasets: MSRA10K and SED2 demonstrate the efficiency of the proposed unsupervised RG method in comparison with the state-of-the-art unsupervised methods.     

Spaceborne and airborne sensors in water quality assessment

Remotely sensed data can increase the ability of water resources researchers and decision-makers to monitor waterbodies more effectively. In recent decades, remote-sensing techniques have been widely used to measure the qualitative parameters of waterbodies (i.e. suspended sediments, coloured dissolved organic matter (CDOM), chlorophyll-a, and pollutants). A large number of different sensors on board various satellites and other platforms, such as aeroplanes, are currently used to measure the amount of radiation at various wavelengths reflected from the water’s surface. In this review article, the more commonly employed spaceborne and airborne sensors used in water quality investigations are introduced and their utility in the quantitative assessment of the quality parameters of waterbodies is discussed. Various properties (spectral, spatial and temporal, etc.) of spaceborne and airborne sensors are tabulated to be used as a sensor selection guide. These tables are helpful when designing water quality assessment studies, and can be used for the selection of appropriate sensors among many other available sensors in the market. Finally, based on the literature survey, a compilation of sensors used to measure various water quality parameters is presented.     

Model checking mobile ad hoc networks

Modeling arbitrary connectivity changes within mobile ad hoc networks (MANETs) makes application of automated formal verification challenging. We use constrained labeled transition systems as a semantic model to represent mobility. To model check MANET protocols with respect to the underlying topology and connectivity changes, we introduce a branching-time temporal logic. The path quantifiers are parameterized by multi-hop constraints over topologies, to discriminate the paths over which the temporal behavior should be investigated; the paths that violate the multi-hop constraints are not considered. A model checking algorithm is presented to verify MANETs that allow arbitrary mobility, under the assumption of reliable communication. It is applied to analyze a leader election protocol.