Synthesis and Evaluation of Biocompatible pH‐Sensitive Hydrogels as Colon‐Specific Drug Delivery Systems

Because of the growing importance of pH‐sensitive hydrogels as drug delivery systems, biocompatible copolymeric hydrogels based N‐vinyl‐2‐pyrrolidinone (NVP) and methacrylic acid (MAA) were designed and synthesized. These hydrogels were investigated for oral drug delivery. Radical copolymerizations of N‐vinyl‐2‐pyrrolidinone (NVP) and methacrylic acid (MAA) with the various ratios of cross‐linking agent were carried out at 70 °C. Azabisisobutyronitrile (AIBN) was the free‐radical initiator employed and Cubane‐1,4‐dicarboxylic acid (CDA) linked to two 2‐hydroxyethyl methacrylate (HEMA) group was the crosslinking agent (CA) used for hydrogel preparations. The hydrogels were characterized by differential scanning calorimetry and FT‐IR. Equilibrium swelling studies were carried out in enzyme‐free simulated gastric and intestinal fluids (SGF and SIF, respectively). A model drug, olsalazine [3,3′‐azobis (6‐hydroxy benzoic acid)] (OSZ) as an azo derivative of 5‐aminosalicylic acid (5‐ASA), was entrapped in these gels and the in‐vitro release profiles were established separately in both enzyme‐free SGF and SIF. The drug‐release profiles indicated that the amount of drug released depended on the degree of swelling. The swelling was modulated by the amount of crosslinking of the polymer bonded drug (PBDs) prepared. Based on the great difference in hydrolysis rates at pH 1 and 7.4, these pH‐sensitive hydrogels appear to be good candidates for colon‐specific drug delivery.     

Molybdenum (VI)‐functionalized UiO‐66 provides an efficient heterogeneous nanocatalyst in oxidation reactions

A novel heterogeneous nanocatalyst was established by supporting molybdenum (VI) on Zr₆ nodes in the structure of the well‐known UiO‐66 metal–organic framework (MOF). The structure of the UiO‐66 before and after Mo (VI) immobilization was confirmed with XRD, DR‐FTIR and UV–vis spectroscopy, and the presence and amount of Mo (VI) was identified by X‐ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectroscopy. TEM imaging confirmed the absence of Mo clusters on the MOF surface, while SEM confirmed that the appearance of the MOF has not changed upon immobilizing the Mo (VI) catalyst. BET adsorption measurements were used to confirm the porosity of the catalyst. The catalytic activity of this heterogeneous catalyst was investigated in oxidation of sulfides with H₂O₂ in acetonitrile and oxidative desulfurization of dibenzothiophene. Easy work up, convenient and steady reuse and high activity and selectivity are prominent properties of this new hybrid material.     

A highly sensitive spectrophotometric determination of ultra trace amounts of azide ion in water and biological samples after preconcentration using dispersive liquid-liquid microextraction technique

A simple and highly sensitive method developed for preconcentration and spectrophotometric determination of ultra trace amounts of azide ion (N ₃ ^? ) in water and biological samples using dispersive liquid-liquid microextraction (DLLME) technique. The method is based on ion association formation of azide ion with malachite green and extraction of the ion pairing product using DLLME technique. Some important parameters, such as reaction conditions and the kind and volume of extraction solvent and disperser solvent were studied and optimized. The calibration curve was linear in the range of 0.5–50 μg/L of azide ion. Also, the enrichment factor and extraction recovery obtained were 24.7 and 98.7%, respectively. The method was applied to the determination of azide ion in water and biological samples.     

Parallel generation of quadripartite cluster entanglement in the optical frequency comb

Scalability and coherence are two essential requirements for the experimental implementation of quantum information and quantum computing. Here, we report a breakthrough toward scalability: the simultaneous generation of a record 15 quadripartite entangled cluster states over 60 consecutive cavity modes (Q modes), in the optical frequency comb of a single optical parametric oscillator. The amount of observed entanglement was constant over the 60 Q modes, thereby proving the intrinsic scalability of this system. The number of observable Q modes was restricted by technical limitations, and we conservatively estimate the actual number of similar clusters to be at least 3 times larger. This result paves the way to the realization of large entangled states for scalable quantum information and quantum computing.     

Paillier-based publicly verifiable (non-interactive) secret sharing

A verifiable secret sharing is a secret sharing scheme with an untrusted dealer that allows participants to verify validity of their own shares. A publicly verifiable secret sharing (PVSS) scheme is a verifiable secret sharing scheme that allows a third party to verify correctness of the distributed shares. We propose an efficient non-interactive PVSS scheme using Paillier additively homomorphic encryption system, and analyze its security in a model that we define in line with the classic semantic-security definition and offering stronger security compared to the previous models. We reduce security of our PVSS scheme to the well studied decisional composite residuosity assumption in this model.     

DFT and TD-DFT study of benzene and borazines containing chromophores for DSSC materials

In this investigation, we have designed a series of benzene and borazines containing chromophores for employing in dye-sensitized solar cells (DSSCs). The optimized structures and photo-physical properties of these molecules have been explored by using the density functional theory method (B3LYP/6-311++G(d,p)). These dyes consist of electron-donor (benzene, borazine, fluorinated borazine) and -acceptor/anchoring (tricyanovinyl), connected by the π-conjugated linker as an electron spacer. The Natural Bond Orbital (NBO) analysis has also been employed for studying the origin of charge transfer. The time-dependent density functional theory (TD-DFT) method has also been used to calculate the electronic absorption spectra of these molecules. The maximum absorption wavelengths assign to HOMO → LUMO transition. The electronic coupling constant, electron injection and light harvesting efficiency have been computed by first principle researches. This revealed that the studied molecules would be efficient photosensitizers.     

Environmentally benign and highly regioselective ring opening of epoxides accelerated by ultrasound irradiation

Regioselective ring opening of aliphatic and aromatic epoxides with nitrogen heterocycles such as indoles and imidazoles was accelerated using an ultrasonic technique as a green approach. An optimized procedure with the catalyst of choice, MCM-41, represents a real alternative to the conventional reaction protocols owing to the catalyst recyclability, simplicity, green conditions and time-saving aspects.