Review Properties of blends and composites based on poly(3-hydroxy)butyrate (PHB) and poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) copolymers

Poly(3-hydroxy)butyrate (PHB) and poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) copolymers are microbial polyesters presenting the advantages of biodegradability and biocompatibility over other thermoplastics with useful mechanical properties. However, their costs and performances must be adjusted by blending with suitable polymers. In this article the miscibility, morphology, mechanical behaviour and other prominent characteristics of a representative number of blends and composites of PHB and PHBV are summarized. In particular, blends with a few polyethers, polyesters, polyvinylacrylates and polysaccharides are illustrated. Furthermore, a brief paragraph deals with PHB/vegetal fiber composites. A wide range of properties emerges by blending with polymers having very different molecular structures and characteristics, such as crystallinity, glass transition and melting temperatures. The microstructure of the blends, resulting from thermodynamic and kinetic factors, is regarded as an important factor in controlling the mechanical and the biodegradation behaviours. Moreover, some considerations upon the nature of the driving force of the miscibility have been made in order to explain miscibility behaviour differences.     

Cave-ins in the Päijänne Tunnel and their repair

Two cave-ins occurred in the Päijänne Tunnel, the repair of both being completed in the spring of 1999. One cave-in occurred near Hämeenkoski and the other near Pulkkila. The Hämeenkoski cave-in was probably caused by the accelerated weathering of a weakness zone, which led to a rather complex cave-in process. The construction of the tunnel in the 1970s changed the groundwater conditions, thus increasing the rate of weathering. The Hämeenkoski cave-in was repaired by a bypass tunnel. The Pulkkila cave-in was caused by a water flow, which flushed out joint fillings, leading to the fall of key-blocks. The Pulkkila cave-in was repaired by penetrating the cave-in.     

Antioxidant and pro-oxidant in vitro evaluation of water-soluble food-related botanical extracts

The total phenol content, antioxidant and pro-oxidant activities of deodourised, water-soluble aniseed, basil, caraway, cardamon, fennel, ginger, juniper, laurel and parsley extracts were estimated using a number of in vitro assays. The laurel and basil extracts contained the highest phenol content of 107.3 ± 1.3 GAE [mg gallic acid equivalents/g (dry wt.) extract] and 98.5 ± 1.4 GAE, respectively, whilst the ginger extract contained the lowest content at 14.9 ± 0.9 GAE. Juniper, laurel and basil extracts were consistently better than the other extracts in terms of iron(III) reducing activity, inhibition of β-carotene-linoleate thermal co-oxidation and N,N-dimethyl-p-phenylenediamine and hydroxyl radical scavenging assays. Potential pro-oxidant activities of the extracts were assessed using both DNA and bovine serum albumin (BSA) as substrates. None of the extracts were capable of stimulating hydroxyl-mediated DNA fragmentation; however, the extracts could be categorised in the protein oxidation assay as extracts with (i) no significant (p > 0.05) effect, (ii) a significant (p < 0.05) protective effect or (iii) a significant (p < 0.05) pro-oxidant effect. The extracts from juniper, laurel and basil had a pro-oxidative effect upon BSA at a dose of 2 mg/ml, as estimated from the degree of carbonylation measured.     

Perceiving action-relevant properties of tools through dynamic touch: Effects of mass distribution, exploration style, and intention.

At issue in the present series of experiments was the ability to prospectively perceive the action-relevant properties of hand-held tools by means of dynamic touch. In Experiment 1, participants judged object move-ability. In Experiment 2, participants judged how difficult an object would be to hold if held horizontally, and in Experiments 3 and 4, participants rated how fast objects could be rotated. In each experiment, the first and second moments of mass distribution of the objects were systematically varied. Manipulations of wielding speed and orientation during restricted exploration revealed perception to be constrained by (a) the moments of mass distribution of the hand-tool system, (b) the qualities of exploratory wielding movements, and (c) the intention to perceive each specific property. The results are considered in the context of the ecological theory of dynamic touch. Implications for accounts of the informational basis of dynamic touch and for the development of a theory of haptically perceiving the affordance properties of tools are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rapid determination of tyramine in fish feed and slaughter offal by HPLC using coulometric detection

Summary Fish feed and slaughter offal products may contain decomposition compounds such as biogenic amines. Owing to their harmful effects on animals fed with such products, there is a need for determing the amine content. In the work a simple and fast HPLC method, based on coulometric detection (EC) measuring only tyramine, was developed for routine quality screening. The samples were extracted with 0.4 mol/L perchloric acid and analysed directly by HPLC using a mobile phase of 0.1 mol/L potassium dihydrogen phosphate in water at pH 3. Tyramine was detected using a coulometric detector consisting of two analytical cells, the first one at 0.4 V and the second at 0.7 V. The calibration was linear over the range 4.52 to 452 ng/ml. The minimum detectable quantity was 10 pg/20111. The reproducibility and the recoveries were high. Comparison of the tyramine content measured by EC or derivatization followed by ultraviolet detection showed that both methods gave similar results. HPLC using EC is a fast and sensitive method for analysing tyramine reliably in fish feed and slaugther offal samples without any time-consuming derivatization steps.

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Schnellbestimmung von Tyramin in Fischfutter und Schlachtabfällen durch HPLC mit coulometrischem Nachweis

Zusammenfassung Fischfutter und Schlachtabfallprodukte können Fäulnisverbindungen wie biogene Amine enthalten. Wegen ihrer schädlichen Wirkung auf Tiere, die damit gefüttert werden, ist es notwendig, auf Amine zu untersuchen. In dieser Arbeit wurde eine einfache und schnelle HPLC-Methode mit coulometrischer Detektion (EC), die nur das Tyrannin mißt, für routinemäßige Qualitätskontrolle entwickelt. Die Muster wurden mit 0,4 mot/L Perchlorsäure extrahiert und unmittelbar durch HPLC analysiert mit einer mobilen Phase von 0,1 mol/L Kaliumdihydrogenphosphat in Wasser bei pH 3. Der coulometrische Detektor besteht aus zwei analytischen Zellen, einer mit 0,4 V und der anderen mit 0,7 V Die Kalibrierung ist linear zwischen 4,52–452 ng/ml. Die geringste feststellbare Menge betrug 10 pg/20 l. Reproduzierbarkeit und Rückgewinnung waren hoch. Der Tyramingehalt, gemessen mit dem coulometrischen Detektor und verglichen mit dem durch Derivatisation nach ultravioletter Detektion erhaltenen, zeigte, daß beide Methoden ähnliche Resultate ergaben. Die entwickelte HPLC-Methode mit ihrer EC-Technik ist eine schnelle und empfindliche Methode zum Analysieren von Tyramin in Fischfutter und Schlachtmustern ohne zeitraubende Stufen der Derivatisation.

     

Flavonol glycosides in wild and cultivated berries of three major subspecies of Hippophaërhamnoides and changes during harvesting period

Flavonol glycosides are an important group of bioactive components of sea buckthorn (Hippophaë rhamnoides). The content and profile of flavonol glycosides of some major subspecies and most cultivars as well as the variation amongst the harvesting years and dates are largely unknown. This study investigated flavonol glycosides in wild berries of two major subspecies H. rhamnoides ssp. rhamnoides and ssp. sinensis and berries of eight cultivars of ssp. rhamnoides and mongolica by reverse phase high performance liquid chromatography combined with diode array detection. The major flavonol glycosides were isorhamnetin-3-O-glucoside-7-O-rhamnoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, isorhamnetin-3-O-sophoroside-7-O-rhamnoside, quercetin-3-O-rutinoside, quercetin-3-O-glucoside and quecertin-3-O-sophoroside-7-O-rhamnoside. The total content of flavonol glycosides fell in the range of 27–130 mg per 100 g fresh berries with considerable variation amongst the origins and the harvesting years. Compared with the berries of ssp. sinensis and ssp. mongolica, the berries of ssp. rhamnoides contained high levels of isorhamnetin-3-O-glucoside-7-O-rhamnoside and isorhamnetin-3-O-glucoside and lower levels of quercetin-3-O-rutinoside and quercetin-3-O-glucoside. In the wild berries of ssp. sinensis, the contents of flavonol glycosides reached maxima around late September to early October and decreased thereafter, whereas a general decreasing trend was seen in the cultivated berries of ssp. rhamnoides from the end of August to the end of October.     

Evolution of anaerobic ciliates from the gastrointestinal tract: phylogenetic analysis of the ribosomal repeat from Nyctotherus ovalis and its relatives

BACKGROUND: Trimeresurus stejnejeri venom plasminogen activator (TSV-PA) is a snake venom serine proteinase that specifically activates plasminogen. Snake venom serine proteinases form a subfamily of trypsin-like proteinases that are characterised by a high substrate specificity and resistance to inhibition. Many of these venom enzymes specifically interfere with haemostatic mechanisms and display a long circulating half-life. For these reasons several of them have commercial applications and are potentially attractive pharmacological tools. RESULTS: The crystal structure of TSV-PA has been determined to 2.5 A resolution and refined to an R factor of 17.8 (R free, 24.4). The enzyme, showing the overall polypeptide fold of trypsin-like serine proteinases, displays unique structural elements such as the presence of a phenylalanine at position 193, a C-terminal tail clamped via a disulphide bridge to the 99-loop, and a structurally conserved Asp97 residue. The presence of a cis proline at position 218 is in agreement with evolutionary relationships to glandular kallikrein. CONCLUSIONS: We postulate that Phe 193 accounts for the high substrate specificity of TSV-PA and renders it incapable of forming a stable complex with bovine pancreatic trypsin inhibitor and other extended substrates and inhibitors. Mutational studies previously showed that Asp97 is crucial for the plasminogenolytic activity of TSV-PA, here we identify the conservation of Asp97 in both types of mammalian plasminogen activator - tissue-type (tPA) and urokinase-type (uPA). It seems likely that Asp97 of tPA and uPA will have a similar role in plasminogen recognition. The C-terminal extension of TSV-PA is conserved among snake venom serine proteinases, although its function is unknown. The three-dimensional structure presented here is the first of a snake venom serine proteinase and provides an excellent template for modelling other homologous family members.     

Optical quality inspection of PLZT ceramics by using CGH-element

Optical quality of surfaces of thin PLZT (Pb_0.9La_0.1(Zr_0.65Ti_0.35)O₃) ceramic plates were investigated with a computer-generated hologram. The surfaces of PLZT samples showed fluctuations in local curvature, and wedgeness for all the cases studied.