ABSTRACT
The interaction of crystalline and amorphous amylopectin with the plasticisers glycerol and ethylene glycol in the absence of water was studied with differential scanning calorimetry (DSC) and solid state NMR. At room temperature glycerol interacts mainly with the amorphous regions, while for ethylene glycol the amylopectin crystallinity does not effect the interaction. After heating the mixtures, an additional immobilisation of the plasticiser occurs.
Subject(s)
Amylopectin/chemistry , Ethylene Glycol/chemistry , Glycerol/chemistry , Magnetic Resonance Spectroscopy/methods , Plasticizers/chemistry , Calorimetry, Differential Scanning/methodsABSTRACT
The interaction of crystalline and amorphous amylopectin with the plasticisers glycerol and ethylene glycol in the absence of water was studied with differential scanning calorimetry (DSC) and solid state NMR. At room temperature glycerol interacts mainly with the amorphous regions, while for ethylene glycol the amylopectin crystallinity does not effect the interaction. After heating the mixtures, an additional immobilisation of the plasticiser occurs.
ABSTRACT
The processing of starches with biodegradable additives has made biodegradable plastics suitable for a number of applications. Starch plastics are partially crystalline as a result of residual crystallinity and the recrystallization of amylose and amylopectin. Such crystallinity is a key determinant of the product's properties. This article describes the influence of processing and storage conditions on starch crystallinity and offers possible explanations for the various properties of starch plastics, in particular for the problems associated with ageing, in terms of the different crystalline structures.
Subject(s)
Biotechnology/trends , Plastics/chemistry , Starch/chemistry , Biodegradation, Environmental , CrystallizationABSTRACT
Diffuse sclerosing osteomyelitis of the mandible is a disease that is characterized by a protracted course of recurrent pain, swelling of the cheek, and trismus. The cause of the lesion has been obscure for a long period of time. Recent research, however, pointed out that this disease is likely to be caused by overuse of the jaw musculature (chronic tendoperiostitis) and can be treated accordingly. The protracted course of the disease and the difficulty of treatment with an eventual positive outcome are illustrated by a case report of a 65-year-old man with an 11-year history of diffuse sclerosing osteomyelitis (chronic tendoperiostitis) of the mandible.
Subject(s)
Mandibular Diseases/etiology , Masticatory Muscles/physiopathology , Osteomyelitis/etiology , Periostitis/etiology , Tendinopathy/etiology , Aged , Chronic Disease , Follow-Up Studies , Humans , Male , Mandibular Diseases/physiopathology , Mandibular Diseases/therapy , Muscle Contraction , Osteomyelitis/physiopathology , Osteomyelitis/therapy , Periostitis/physiopathology , Periostitis/therapy , Relaxation Therapy , Tendinopathy/physiopathology , Tendinopathy/therapyABSTRACT
Cyclobutane-type photodimers of dinucleoside monophosphates dCpdT, dTpdC and dTpdT were prepared by ultraviolet irradiation in the presence of acetophenone as photosensitizer. The cytosine-containing derivatives were found to deaminate forming uracil products. Using one- and two-dimensional NMR, the photoproducts were characterized as cis-syn and trans-syn cyclobutane photodimers. On the basis of NOE data the structures of the cis-syn and trans-syn products of dUpdT were determined using distance-geometry and restrained-energy-minimization methods. The cis-syn structures showed (high-ANTI/SYN)/high-ANTI glycosidic linkages while the trans-syn structures were in the SYN-ANTI region. The backbone conformations of both structures were in fair agreement with the coupling-constant-data. The trans-syn structures were found to be very rigid and similar in all three products. For the three cis-syn structures more conformational freedom and more variation among the three structures was observed.
