Composition and characterization of in situ usable light cured dental drug delivery hydrogel system

Biodegradable polymers are compatible, permeable and nontoxic, thus they can provide a useful tool for drug delivery or tissue engineering. These polymers can form hydrogels, which are suitable vehicles for different types of materials e.g. drugs, bioactive molecules or cells. In the case of dentistry, photopolymerization is an obvious method to obtain in situ useable devices which can provide a more efficient way of tailoring drug release. A hydrogel system was developed based on poly-gamma-glutamic acid that was modified with methacryloyl groups to achieve this purpose. The resulting new reactive structure was proved by NMR spectroscopy. The swelling ratio of this type of hydrogel has been found remarkable, over 300 % after 24 h, and it can release 5 ng/mm² metronidazole. The prepared hydrogels were nontoxic as viability, cytotoxicity tests and cell morphology investigations proved it. These results render this model system an excellent candidate for use as an in situ curing local drug delivery device. The new photoactive system can be utilized in the treatment of periodontal diseases or raising the effectiveness of drugs used only in the minimal effective dose.     

Improved absorption characteristics of thermally modified beech veneer produced by plasma treatment

In this study the effect of an atmospheric pressure plasma treatment by a dielectric barrier discharge (DBD) on the wettability and absorption characteristics of thermally modified beech veneer is investigated. A common immersion test using water and melamine solution has been conducted and showed improved wettability and liquid uptake after plasma treatment. Determination of the weight percent gain (WPG) confirmed increased melamine content after plasma treatment.     

"Nanoarmoured" droplets of different shapes formed by interfacial self-assembly and crosslinking of metal nanoparticles

Films comprising metal nanoparticles are assembled on the surfaces of liquid droplets of different shapes and macroscopic dimensions. These films are reinforced by dithiol crosslinks and are mechanically rugged yet permeable to the diffusion of small molecules.     

Preparation, Characterisation and Some Reactions of Organocatalysts Immobilised Between the Layers of a CaFe-Layered Double Hydroxide

Five- and six-membered cyclic ??-amino acid anions with secondary nitrogen in the ring (l-prolinate and dl-pipecolinate) were immobilised in Ca₃Fe-L(ayered)D(ouble)H(ydroxide) by the dehydration-rehydration method. The resulting organic?Cinorganic hybrids were characterised by various instrumental methods (powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray fluorescence with elemental mapping, and analytical techniques for determining the iron as well as the organic contents) and molecular modelling. The immobilised organocatalysts were tested in the cross-aldol dimerization-condensation reaction between benzaldehyde and acetone and found to be active and enantioselectivity in the dimerization was also observed.     

Hydrodechlorination Reactions of CCl4 Over HZSM-5- and HY-Supported Pt and Pd Catalysts

The hydrodechlorination reactions of CCl₄ have been studied over Pt/HZSM-5, Pt/HY, Pd/HZSM-5 and Pd/HY under hydrogen atmosphere in the 393?C673?K temperature range in a pulse microreactor. The catalysts were prepared by impregnation and were characterised by various physico-chemical means. It has been found that all catalysts were active in the partial to full dechlorination reactions. Typically, over the Pt-containing catalysts methane was the major dechlorinated product, while it was ethane over the Pd-containing catalysts. This latter product predominated over the Pd/HZSM-5 and the quantities of the di- and trichlorinated products were minimal and the monochlorinated one was not formed at all. Phosgene formed was the indication of the partial destruction of the support being more serious for the HY-supported ones.     

Integration of Homogeneous and Heterogeneous Catalytic Processes for a Multi-step Conversion of Biomass: From Sucrose to Levulinic Acid, γ-Valerolactone, 1,4-Pentanediol, 2-Methyl-tetrahydrofuran, and Alkanes

The multi-step conversion of sucrose to various C₅-oxygenates and alkanes was achieved by integrating various homogeneous and heterogeneous catalytic systems. We have confirmed that the dehydration of sucrose to levulinic and formic acids is currently limited to about 30–40% in the presence of H₂SO₄, HCl, or Nafion NR50 in water. Performing the dehydration in the presence of a P(m-C₆H₄SO₃Na)₃ modified ruthenium catalyst under hydrogen resulted in the in situ conversion of levulinic acid to γ-valerolactone (GVL). Levulinic acid can be hydrogenated to GVL quantitatively by using P(m-C₆H₄SO₃Na)₃ modified ruthenium catalyst in water or Ru(acac)₃/PBu₃/NH₄PF₆ catalyst in neat levulinic acid. Formic acid can be used for the transfer hydrogenation of levulinic acid in water in the presence of [(η⁶-C₆Me₆)Ru(bpy)(H₂O)][SO₄] resulting in GVL and 1,4-pentanediol. The hydrogenation of levulinic acid or GVL can be performed to yield 1,4-pentanediol and/or 2-methyl-tetrahydrofuran (2-Me-THF). The hydrogenolysis of 2-Me-THF in the presence of Pt(acac)₂ in CF₃SO₃H resulted in a mixture of alkanes. We have thus demonstrated that the conversion of carbohydrates to various C₅-oxygenates and even to alkanes can be achieved by selecting the proper catalysts and conditions, which could provide a renewable platform for the chemical industry.     

Synthesis and characterization of novel well-defined stars consisting of eight polyisobutylene arms emanating from an octa(dimethylsiloxy)octasilsesquioxane core

The synthesis and characterization of novel stars, octa(polyisobutylenedimethylsiloxy)octasilesquioxane (T₈ ^DPIB), consisting of eight polyisobutylene arms emanating from an octa(dimethylsiloxy)octasilsesquioxane (T₈ ^D) core are described. The synthesis involves: 1) The synthesis of allyl-terminated polyisobutylene (PIB^█01█) prearms, 2) The synthesis of octa(hydrodimethylsiloxy)octasilsesquioxane (T₈ ^DH) precore and 3) Star formation by hydrosilation of PIB^█01█ with T₈ ^DH. Conditions for the precision synthesis and characterization of well-defined octa-arm stars are described. Received: 13 September 1996/Accepted: 14 October 1996     

Alkylation of Benzene with Cyclic Ethers in Superacidic Media

Superacidic trifluoromethanesulfonic acid (triflic acid, TFSA) catalyzes the alkylation of benzene with various cyclic ethers. The characteristic products formed in the reaction of highly reactive oxiranes (methyloxirane, styrene oxide, and cyclohexene oxide) are phenyl-substituted compounds formed as a result of Friedel–Crafts-type mono- and dialkylation. Oxetanes (2-isopropyloxetane) and oxolanes (tetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2,2,5,5-tetramethyltetrahydrofuran), in turn, undergo electrophilic cyclialkylative ring closure (cyclialkylation) to form mainly bicyclic compounds (tetralin, dihydronaphthalene, and naphthalene derivatives). In the majority of cases, alkylated products can be isolated in good to reasonable yields. Reactivity of cyclic ethers, product formation and product distributions are interpreted by taking into account ring strain, acidity of reaction mixtures and stability of carbocationic intermediates.     

Green synthesis and characterization of phosphorus flame retardant crosslinking agents for epoxy resins

The flame‐retardant efficacy of phosphorus‐containing reactive amine hardeners for epoxy resins is well‐known; however their synthesis often applies hazardous, objectionable reagents. The aim of this work is to develop an effective synthesis method for the preparation of P‐containing amines, which can act as flame‐retardant crosslinking agent in epoxy resins. The syntheses and testing of an aliphatic and two aromatic amines are described: curing properties, glass transition temperature, thermal stability, and flame‐retardant performance of the amines are studied. On the basis of these results, the scaling‐up and the optimization of the synthesis of the phosphorus‐containing aliphatic amine hardener in ReactIR? in situ FTIR apparatus is discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40105.