Cyanobacteria Biorefinery - Production of poly(3-hydroxybutyrate) with Synechocystis salina and utilisation of residual biomass.

This study evaluates a biorefinery concept for producing poly(3-hydroxybutyrate) (PHB) with the cyanobacterial strain Synechocystis salina. Due to this reason, pigment extraction and cell disruption were investigated as pre-treatment steps for the harvested cyanobacterial biomass. The results demonstrated that at least pigment removal was necessary to obtain PHB with processable quality (weight average molecular weight: 569-988kgmol-1, melting temperature: 177-182°C), which was comparable to heterotrophically produced PHB. The removed pigments could be utilised as additional by-products (chlorophylls 0.27-1.98mgg-1 TS, carotenoids 0.21-1.51mgg-1 TS, phycocyanin 0-127mgg-1 TS), whose concentration depended on the used nutrient source. Since the residual biomass still contained proteins (242mgg-1 TS), carbohydrates (6.1mgg-1 TS) and lipids (14mgg-1 TS), it could be used as animal feed or converted to biomethane (348 mn3 t-1VS) and fertiliser. The obtained results indicate that the combination of photoautotrophic PHB production with pigment extraction and utilisation of residual biomass offer the highest potential, since it contributes to decrease the environmental footprint of the process and because biomass could be used in a cascading way and the nutrient cycle could be closed.

Multi-methodological investigation of the variability of the microstructure of HPMC hard capsules.

The objective of this study was to analyze differences in the subtle microstructure of three different grades of HMPC hard capsule shells using mechanical, spectroscopic, microscopic and tomographic approaches. Dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), vibrational spectroscopic, X-Ray scattering techniques as well as environmental scanning electron microscopy (ESEM) and optical coherence tomography (OCT) were used. Two HPMC capsules manufactured via chemical gelling, one capsule shell manufactured via thermal gelling and one thermally gelled transparent capsule were included. Characteristic micro-structural alterations (associated manufacturing processes) such as mechanical and physical properties relevant to capsule performance and processability were thoroughly elucidated with the integration of data obtained from multi-methodological investigations. The physico-chemical and physico-mechanical data obtained from a gamut of techniques implied that thermally gelled HPMC hard capsule shells could offer an advantage in terms of machinability during capsule filling, owing to their superior micro- and macroscopic structure as well as specifically the mechanical stability under dry or humid conditions.

Poly(hydroxy alkanoate)s in Medical Applications.

This review summarizes the state-of-the-art knowledge of the usage of poly(hydroxy alkanoate)s in medical and sanitary applications. Depending on the monomers incorporated into the polymers and copolymers, this class of polymers exhibits a broad range of (thermo-)plastic properties, enabling their processing by, e.g., solution casting or melt extrusion. In this review, strategies for the polymer analogous modification of these materials and their surfaces are highlighted and correlated with the potential applications of the corresponding materials and blends. While the commercial availability of purified PHAs is addressed in brief, special focus is put on the (bio-)degradability of these polymers and ways to influence the degradation mechanism and/or the duration of degradation.

Magnetic-field-induced changes of the isotropic-nematic phase transition in side-chain polymer liquid crystals.

The isotropic-nematic (I-N) phase transition of side-chain polymer liquid crystals is intrinsically a weak first-order transition with a biphasic region spread over a wide temperature interval. In the presence of high magnetic fields we find the I-N transition to become a strong first order. The I-N biphasic region shrinks its temperature window as larger magnetic fields are applied, until it completely disappears and the transition completes at a fixed temperature. We interpret this behavior as a consequence of the nonlinear coupling of the magnetic field to the system free energy, via the suppression of the order fluctuations in the nematic mesophase at the I-N transition crossing.

Mesogene-polymer backbone coupling in side-chain polymer liquid crystals, studied by high magnetic-field-induced alignment.

We show that cooling side chain polymer liquid crystals in a magnetic field, from the isotropic to nematic and subsequently to the glass phase, results in a macroscopically ordered, transparent, and strongly birefringent material. The aligned samples retain their properties after the field is removed and can be dealigned only by heating them to the isotropic phase. To induce alignment, a threshold field B(th) is necessary, which strongly depends on the chemical structure details. B(th) reflects the strength of mesogene-polymer backbone coupling, and we will show that this interaction is responsible for the stability of the induced alignment at zero field.

Platinum-catalyzed cycloisomerization reactions of enynes.

PtCl(2) constitutes an efficient and practical catalyst for a set of different atom economical rearrangement reactions of enynes. This includes (i) a formal enyne metathesis reaction delivering 1,3-dienes, (ii) the formation of polycyclic vinylcyclopropane derivatives, and (iii) an unprecedented O-->C allyl shift reaction if unsaturated ethers are employed. Although these transformations produce significantly different structural motifs, they share a common mechanism comprising a cationic manifold triggered by the pi-complexation of Pt(II) onto the alkyne unit of the substrates. Strong experimental support for the proposed mechanism comes from deuterium-labeling studies, a careful analysis of the product distribution pattern, and the fact that in some cases PtCl(2) can be replaced by simple Lewis or Brønsted acids as the catalysts.

Comparative investigation of ruthenium-based metathesis catalysts bearing N-heterocyclic carbene (NHC) ligands.

Exchange of one PCy3 unit of the classical Grubbs catalyst 1 by N-heterocyclic carbene (NHC) ligands leads to "second-generation" metathesis catalysts of superior reactivity and increased stability. Several complexes of this type have been prepared and fully characterized, six of them by X-ray crystallography. These include the unique chelate complexes 13 and 14 in which the NHC- and the Ru-CR entities are tethered to form a metallacycle. A particularly favorable design feature is that the reactivity of such catalysts can be easily adjusted by changing the electronic and steric properties of the NHC ligands. The catalytic activity also strongly depends on the solvent used; NMR investigations provide a tentative explanation of this effect. Applications of the "second-generation" catalysts to ring closing alkene metathesis and intramolecular enyne cycloisomerization reactions provide insights into their catalytic performance. From these comparative studies it is deduced that no single catalyst is optimal for different types of applications. The search for the most reactive catalyst for a specific transformation is facilitated by IR thermography allowing a rapid and semi-quantitative ranking among a given set of catalysts.

Physical aspects of dexibuprofen and racemic ibuprofen.

This article presents a comparative study of ibuprofen materials in their solid state. Ibuprofen crystallizes into two different structures for the S(+) enantiomer (dexibuprofen) and racemic ibuprofen. The crystal structure of ibuprofen, its optical absorption and photoluminescence, and the thermodynamic results (melting point and heat of fusion) are discussed. From these physicochemical properties, the authors conclude that dexibuprofen, which is the most active species pharmaceutically, and racemic ibuprofen are inherently different solid-state materials.

[Disorder of the superior cortical function and vascular malformation: case report]. / Distúrbio da função cortical superior e malformação vascular. Relato de caso.

Learning disorders are commonly seen among neurologic outpatients. We present the case of a young male patient showing learning disabilities and headache of recent onset. His diagnostic evaluation performance in cortical function was poor, and tomographic and arteriographic changes of cerebrovascular malformation were found. The authors discuss the association of learning disorders and cerebral vascular malformations.

Abnormal gallbladder emptying in patients with gallstones.

In this study, gallbladder and gastric emptying were compared in 15 normal subjects and 15 patients with gallstones. A noninvasive technique which used two gamma-emitting radiopharmaceutical agents to image the gallbladder and stomach simultaneously was employed. Technetium-99m-HIDA was used as a gamma-emitting marker for the gallbladder and indium-111-DTPA was mixed with a standard liquid meal in order to stimulate gallbladder emptying and to measure gastric emptying. In patients with gallstones, gallbladder emptying was diminished significantly compared to normal subjects. In contrast, emptying of the stomach was normal. The gallbladder emptying responses to octapeptide of cholecystokinin, administered either as bolus or infusion doses, were similar in normal subjects and patients with gallstones. These studies suggest that gallbladder emptying may be abnormal in patients with gallstones. The explanation for this abnormality and its relationship to the development of gallstones has not been determined.

Cholinergic effects on esophageal transit and clearance.

Modern manometric and scintigraphic techniques were employed in an effort to determine the relationships between esophageal contractions and esophageal transit and clearance. The effects of direct cholinergic stimulation with bethanechol and blockade with atropine were evaluated in a total of 20 normal subjects and 13 patients with symptomatic gastroesophageal reflux. Bethanechol increased the amplitudes of deglutition-induced and distention-induced esophageal contractions, but diminished their propagation velocities. Both esophageal transit and clearance were decreased in patients with reflux, but both were improved after bethanechol. Atropine sulfate decreased the amplitudes of contractions, accelerated their propagation velocities, and delayed esophageal transit and clearance. Both transit and clearance were diminished significantly when reflux patients were compared with normal subjects. The amplitudes of esophageal contraction were significantly lower in patients with reflux than in normal subjects. Neither bethanechol nor atropine affected the incidence of deglutition-induced esophageal contractions. These studies suggest that the efficiency of esophageal emptying may be determined by the amplitudes of esophageal contractions.

Enterogastric reflux in normal subjects and patients with Bilroth II gastroenterostomy. Measurement of enterogastric reflux.

Initially, scintigraphy was established as a valid method for detecting and quantitating enterogastric reflux. A new, tubeless technique for the measurement of enterogastric reflux was developed. 99mTc bound to [(2,6 dimethylphenylcarbamoylmethyl) iminodiacetic acid] (5 mCi) was administered intravenously to visualize the liver and biliary tract. One hour later, a standard liquid meal labeled with 111In bound to diethylene-triamine penta-acetic acid (250 microCi) was given. The 99mTc and 111In activities were recorded simultaneously for 1-min periods at 15-min intervals for 2 hr over liver, gallbladder, and gastric areas of interest. Enterogastric reflux indices were determined. Ten normal subjects and 13 patients with vagotomy, hemigastrectomy, and Bilroth II gastrojejunostomy were evaluated. The enterogastric reflux index in asymptomatic postsurgical patients was increased significantly to 24.6 +/- 4.7 compared with 8.2 +/- 6.0 (P less than 0.01) in normal subjects. In postsurgical patients with the syndrome of alkaline gastritis, the enterogastric reflux index was increased significantly to 86.3 +/- 7.1 (P less than 0.01) compared with asymptomatic postsurgical patients.