Sulfonated polystyrene/montmorillonite nanocomposite (OMMT/PS-SO3H) was prepared and used as a novel, efficient and inexpensive heterogeneous acid catalyst in the one-pot reaction three-component Mannich reaction of ketones, aromatic aldehydes and amines under solvent-free conditions. The catalyst was characterized by XRD, SEM, TG, BET and FT-IR techniques. This method has advantages...

     Cellulose was applied as a reusable and green catalyst for the facile four-component synthesis of 6-amino-4-aryl-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile derivatives using hydrazine monohydrate, ethyl acetoacetate, malononitrile and aryl aldehydes, under solvent-free and thermal conditions. The use of non-toxic and inexpensive catalyst, short reaction time, clean w...

The fluid, dispersed market of e-commerce makes it hard to judge the reliability of participants. While early Internet trust practices merge old practices—acknowledgments, customer surveys, audits—into Web technology, a need exists for better approaches to assurance. Ideally, these trust mechanisms should be inexpensive, scalable, and private. The proposed three-level hierarchy of ever more pow...

Convenient high yielding syntheses of optically pure PNAMs comprising l- or d-serine, l-lysine and l-arginine units linked to thymine or Cbz-cytosine are described. Simple workup and inexpensive reagents are employed and free amino acids are used as coupling components.

Over the last years, technology evolution is leading the way towards autonomous, ubiquitous and widespread interactions among small computing devices. To this aim, communication technologies that support dynamicity and mobility and work on inexpensive small devices have attracted much attention. The Bluetooth specification particularly fits this idea, providing a free, versatile, and flexible w...

buildings with wall or frame-wall systems are more effective against earthquake forces and sustain less damage than buildings which their lateral resistance is solely depends on frames. four reinforced concrete (rc) structural wall specimens were subjected to cyclic loading using finite elements method with abaqus software in order to study influence of diagonal web reinforcement. the research ...

Activity recognition systems using simple and ubiquitous sensors require a large variety of real-world sensor data for not only evaluating their performance but also training the systems for better functioning. However, a tremendous amount of effort is required to setup an environment for collecting such data. For example, expertise and resources are needed to design and install the sensors, co...