On biconservative hypersurfaces in ‐dimensional Riemannian space forms

In this paper, we study biconservative hypersurfaces in and . Further, we obtain complete explicit classifications of biconservative hypersurfaces in 4‐dimensional Riemannian space forms with exactly three distinct principal curvatures.     

MoCl5/EtAlCl2-catalysed nonmetathesis polymerization of norbornadiene

Norbornadiene was polymerized, in moderate yield by MoCl₅ or EtAlCl₂. By using both components together, an increase in reaction rates and in polymer yields were observed. By the optimization of the reaction conditions, 100% of polymer yield was achieved. For comparison, the polymerization of the NBD was also accomplished by using initiators such as AlCl₃, Et₃Al, AZBN, and n-butyl lithium. All the obtained polymers gave similar IR and NMR spectra indicating the presence of the polynortricyclene structures. Though they show different molecular weight distribution, the solubilities of the polymers (obtained using MoCl₅, AlCl₃, EtAlCl₂, and MoCl₅/EtAlCl₂) are very similar. DTA analyses show that the polymers (obtained by using MoCl₅/EtAlCl₂ pair or n-butyl lithium or Et₃Al) have high thermal stabilities whereas all the other polymers are unstable in air. © 1996 John Wiley & Sons, Inc.     

Microgel,nanogel and hydrogel–hydrogel semi-IPN composites for biomedical applications: synthesis and characterization

Quaternary ammonium salt hydrogels from a cationic monomer, (3-acrylamidopropyl)-trimethylammonium chloride (APTMACl), in a variety sizes such as bulk, micro- and nano- has been prepared. The synthesis of micro- and nanogels were carried out in the microenvironment of water-in-oil microemulsions using two types of surfactants, namely, L-α- phosphatidylcholine (lecithin) and dioctyl sulfosuccinate sodium salt (AOT). Additionally, hydrogel–hydrogel composite semi-interpenetrating polymer networks (semi-IPN) was synthesized by dispersing previously prepared micro/nanogel into neutral monomers such as acrylamide (AAm) or 2-hydroxylethyl methcarylate (HEMA) before network formation. Hydrogel swelling and pH response behaviors have been investigated for bulk gels. Morphology, structure, and size of nano-, micro- and bulk materials were explored utilizing transmission electron microcopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was confirmed with gel electrophoresis that completely charged nanogel form a strong complex with DNA.     

A new synthetic approach for pyrazolo[1,5-a]pyrazine-4(5H)-one derivatives and their antiproliferative effects on lung adenocarcinoma cell line

Molecular Diversity - Starting from the 3,5-dimethyl pyrazole ring and acetophenone derivatives, five different N-propargylated C-3 substituted pyrazoles were obtained. These derivatives were...     

Graphene oxide embedded P(AAm)/PANI cryogel polymer composites for sensor application against pesticide,nitro compound,and organic dyes

Abstract

Graphene oxide (GO) embedded superporous poly(acrylamide) (P(AAm)) cryogel composites (P(AAm)-GO) were prepared and used as conductive sensor materials. For this goal, the GOs flakes within superporous P(AAm) cryogels were reduced in-situ employing hydriodic acid (HI), hydrazine (N₂H₄), and sodium borohydride (NaBH₄) as reducing agents. Amongst all reduced agents\the highest conductivity was observed for HI reduced P(AAm)-GO (P(AAm)-rGO) with 1.7?×?10^?6±9.7?×?10^?8 S.cm^?1. Then again, this P(AAm)-rGO was used for in-situ synthesis of conductive polymers, poly(aniline) (PANI), and poly(pyrrole) (PPy) by using oxidative polymerization technique. The SEM, FT-IR, TGA and conductivity measurements were done for the characterization of prepared cryogel composites. It was found that the conductivity of P(AAm)-rGO increased 70- and 1400-fold with the presence of PANI and PPy, respectively. Furthermore, potential sensor application of P(AAm)-rGO/conductive polymers were tested against herbicides such as paraquat, glyphosphate (G), and a phenolic compound, 4-nitrophenol (4-NP), and some dyes such as methylene blue (MB), methyl orange (MO). Conductivity of P(AAm)-rGO/PANI decreased 5.3 -fold upon reacting with 10?mL 50?ppm G solution. The sensitivity and effect of G amounts were also tested for P(AAm)-rGO/PANI cryogel composite.     

Colloidal nanocomposite hydrogel particles

Quaternary ammonium salt, (3-acrylamidopropyl)-trimethylammonium chloride was used to synthesize nanohydrogel and composite particles such as inorganic–organic hybrid composites and hydrogel nanoparticles with magnetic properties utilizing a water-in-oil microemulsion system. The positively charged cationic monomer was chosen to promote silica hydrolysis and condensation to prepare silica-hydrogel nanocomposite particles with interesting morphologies. It was shown that highly monodisperse, completely charged nanohydrogel can be used to encapsulate ferrite particles. Furthermore, it was also confirmed that cationic nanohydrogel particles with variant morphology can be prepared by employing suitable silica precursor. Morphology, structure, properties, and size of nanocomposite materials were explored utilizing transmission electron microscopy, atomic force microscopy, and vibrating sample magnetometer.     

Synthesis and characterization of soft polymeric nanoparticles and composites with tunable properties

Polymeric particles comprising acrylonitrile (AN)‐based core and acrylamide derivative–based shell in the submicron range with positive and negative charges were synthesized via microemulsion polymerization. 2‐Acrylamido‐2‐methylpropane sulfonic acid (AMPS) and 3‐(acrylamidopropyl)‐trimethyl ammonium chloride (APTMACl) were used as shell‐forming charged monomers onto AN core for the synthesis of p(AN‐co‐AMPS) and p(AN‐co‐APTMACl), respectively, using an oil‐in‐water emulsion system. To tune the characteristics of the core–shell particles, AN moieties in the core were amidoximated to change the nature of the core from hydrophobic (nitrile) to hydrophilic (amidoxime) nature. Additionally, colloidal magnetite particles (Fe₃O₄) produced by chemical coprecipitation technique under alkaline and inert conditions were also included inside p(AN‐co‐AMPS) and p(AN‐co‐APTMACl) particles as dual‐responsive nanocomposites against pH and magnetic field. With the magnetic properties, AN‐based core with modifiable characteristics and acrylamide‐based polyelectrolyte shells with variable charges and sizes were further used as drug carriers. For potential targeted drug delivery application of the synthesized soft particles and their composites Naproxen and Trimethoprim were used as model drugs, and he release studies were carried in phosphate buffer saline (pH = 7.4) at ambient temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Utilization of smart hydrogel-metal composites as catalysis media

Various metal nanoparticles such as, Cu, Co, Ni, and Fe were prepared inside poly(1-vinyl imidazole) p(VI) hydrogel by the absorption of the corresponding metal ions from aqueous solutions and the reduction with suitable reducing agents such as NaBH(4) and/or NaOH. TGA and ICP-AES were used to determine the metal particle content of p(VI)-M (M: Cu, Co, and Ni) composites. The prepared hydrogel-metal nanoparticle composites were proven to be resourceful as reaction container for the catalysis of various organic reactions. It was illustrated that p(VI)-M hydrogel-metal composites can be successfully used in the hydrolysis of NaBH(4) for the generation hydrogen form NaBH(4) and NH(3)BH(3). Additionally, p(VI)-M composites were also illustrated in the catalysis of different organic reactions; e.g., these hydrogel-M are very effective in the reduction nitro aromatic compounds such 2-nitrophenol (2-NP) and 4-nitrophenol (4-NP) to their corresponding amine forms in the presence of aqueous NaBH(4). Various parameters in the catalysis of hydrogen production and 4-NP reduction were determined.