Anti-babesial compounds from Curcuma xanthorrhiza

Anti-babesial ingredients, (12R)- and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizols, were isolated from Curcuma xanthorrhiza. The structures were established by the extensive NMR techniques. The assignments of (1)H NMR data of (12R)-12,13-dihydro-12,13-dihydroxyxanthorrhizol was revised, and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizol was isolated as a pure form for the first time. The IC(50) of the active compounds were compared with that of commercial drug, diminazene aceturate (Ganaseg). IC(50) values of Ganaseg, (12R)-, and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizols were 0.6 microg mL(-1), 8.3 microg mL(-1) and 11.6 microg mL(-1), respectively.     

Synthesis,characterization, and application of [1-methylpyrrolidin-2-one-SO3H]Cl as an efficient catalyst for the preparation of α-aminophosphonate and docking simulation of ligand bond complexes of cyclin-dependent kinase 2

A sulfonic acid functionalized ionic liquid was designed, synthesized and successfully used as a Brønsted acid catalyst for the one-pot synthesis of α-aminophosphonates containing benzothiazole at room temperature under solvent-free conditions in excellent yields. The advantages of this method are the reusability of the catalyst, high conversion, short reaction time, and simple experimental procedure. A computer modeling and docking simulation of ligand bond complexes of cyclin-dependent kinase 2 are presented. The results indicate that diethyl ((4-(dimethylamino) phenyl) ((6-nitrobenzo[d]thiazol-2-yl) amino)methyl)phosphonate was found to be the best selective inhibitor of cyclin-dependent kinase 2.     

Copper-immobilized ionic liquid as an alternative to organic solvents in the one-pot synthesis of bioactive dihydropyrano[2,3-c]pyrazole derivatives

In this study, a novel Cu-immobilized ionic liquid (IL)was designed, characterized, and employed as both promoter and solvent in the synthesis of some dihydropyrano[2,3-c]pyrazoles. The synthesized ionic liquid was characterized by ¹H NMR, ¹³C NMR, FTIR, ICP and EDX analysis and showed high catalytic activity to proceed the synthesis of bioactive dihydropyrano[2,3-c]pyrazole derivatives. This method has the advantage of using the IL as a green medium for the synthesize of the products in high to excellent yields within short reaction times.     

Efficient privacy-preserving group-nearest-neighbor queries with the presence of active adversaries

Location-based services (LBSs) allow users to ask location-dependent queries and receive information based on their location. A group of users can send a group-nearest-neighbor (GNN) query in order to receive a Point Of Interest (POI). This POI in turn shows a point which is the minimum distance from all members of the group. To benefit from these services, it is important to preserve the location privacy of each group user from others in the group (Intragroup location privacy) as well as from anyone outside of the group, including the LBS, (Intergroup location privacy). It may also be necessary to protect the location privacy of the resulting POI from the LBS and other possible attackers. In this paper, we propose two different privacy-preserving protocols for finding the exact answer to a GNN query among a set of returned POIs. The first protocol assumes a semi-honest model while the second one works in a malicious model. The proposed protocols are based on the Anonymous Veto network and Burmester–Desmedt key establishment protocols. The security analysis shows that the proposed protocols provide both Intragroup and Intergroup location privacy; they also protect the location privacy of the resulting POI and are resistant to collusion and multi-point aggregate distance attacks. The performed analyses indicate that they incur a constant computation cost per user and are efficient in terms of computation and communication costs.

     

A Novel Ionic Liquid Based on Imidazolium Cation as an Efficient and Reusable Catalyst for the One‐pot Synthesis of Benzoxazoles,Benzthiazoles, Benzimidazoles and 2‐Arylsubstituted Benzimidazoles

A novel dicationic ionic liquid based on imidazolium cation is designed, synthesized and successfully used as catalyst for the one‐pot synthesis of benzoxazoles, benzthiazoles, benzimidazoles and 2‐arylsubstituted benzimidazoles. The remarkable feature of this new catalyst is its ethyleneoxy bridge which participates in dissolving organic compound in ionic liquid. The application of this ionic liquid is studied in a new one‐pot method for synthesis of heterocyclic compounds under solvent‐free conditions. Simple and convenient procedure, high conversion, reusability of catalyst, easy purification and shorter reaction time are the advantageous features of this method.     

On the diversity analysis of symbol remapping in cooperative BICM–OFDM scheme for frequency selective Rayleigh fading channels

In this paper, diversity analysis of a symbol remapping scheme in cooperative systems is considered. We employ Bit Interleaved Coded Modulation and Orthogonal Frequency Division Multiplexing, which are widely used at wireless networks. In this paper, at the cooperative scheme, relays operate in DF mode and the effect of their erroneous detection will be considered. We present a closed form of the asymptotic worst-case pairwise error probability at the destination for our proposed scheme. It will be shown that this scheme exploits full spatial and frequency diversities. After that, we work on designing a new precoder matrix. Moreover, we propose two new subcarrier allocations for the proposed scheme. All new methods have been suggested to achieve the available diversities with a better performance than current state of the art. Finally, the simulation results reveal the analytical derivations and confirm the obtained diversity gain of the proposed systems.     

Preparation and characterization of flexible polyurethane foam nanocomposites reinforced by magnetic core-shell Fe3O4@APTS nanoparticles

Novel magnetic polyurethane flexible foam nanocomposites were synthesized by incorporation of aminopropyltriethoxysilane (APTS) functionalized magnetite nanoparticles (MNPs) via one-shot method. The functionalized MNPs (Fe₃O₄@APTS) were synthesized by co-precipitation of the Fe²⁺ and Fe³⁺ with NH₄OH and further functionalization with APTS onto the surface of MNPs by sol–gel method. The magnetic core-shell NPs were used up to 3.0 % in the foam formulation and the magnetic nanocomposites prepared successfully. The results of thermogravimetric analysis (TGA) showed an increasing in thermal stability of polyurethane nanocomposite foam at initial, 5 and 10 %, and maximum thermal decomposition temperatures by incorporation of Fe₃O₄@APTS. In addition SEM images revealed the uniformity of the foam structures and decreasing in pore sizes. Furthermore, VSM result showed super paramagnetic behavior for Fe₃O₄@APTS-PU nanocomposites.