Biosynthesis and properties of medium-chain-length polyhydroxyalkanoates with enriched content of the dominant monomer.

When grown in a nonanoic acid-limited chemostat at a dilution rate of 0.25 h(-1), Pseudomonas putida KT2440 produced poly(3-hydroxynonanoate-co-3-hydroxyheptanoate) containing 68 mol % 3-hydroxynonanoate (C9) and 32 mol % 3-hydroxyheptanoate (C7). Under the same conditions, but in the presence of acrylic acid, a fatty acid β-oxidation inhibitor, the C9 monomer content increased to 88 mol %.

An advanced rehabilitation robotic system for augmenting healthcare.

Emerging technologies such as rehabilitation robots (RehaBot) for retraining upper and lower limb functions have shown to carry tremendous potential to improve rehabilitation outcomes. Hstar Technologies is developing a revolutionary rehabilitation robot system enhancing healthcare quality for patients with neurological and muscular injuries or functional impairments. The design of RehaBot is a safe and robust system that can be run at a rehabilitation hospital under the direct monitoring and interactive supervision control and at a remote site via telepresence operation control.

Microbial medium chainlength poly[(R)-3-hydroxyalkanoate] shows liquid crystal behaviour.

Medium chainlength (mcl) polyhydroxyalkanoates (PHAs) are a class of polymers receiving attention because of their potential as renewable, biodegradable and high tech properties. Unlike most short chain PHAs, mcl-PHAs are low crystallinity and elastomeric in character. In this paper we wish to point out that in their broad properties mcl-PHAs might be classified as thermotropic liquid crystals with dynamic conformational disorder and long range orientational order.

Application of polyhydroxyalkanoate granules for sizing of paper.

Polyhydroxyalkanoates (PHAs) are characterized by the chemistry of the biodegradable inclusions inside the microbial membrane. They are produced by a wide variety of bacteria, where they function as energy and carbon storage materials. This intracellular Bioplastic forms a stable latex suitable for surface treatments of paper such as sizing and coating.

Polyester-based micelles and nanoparticles for the parenteral delivery of taxanes.

Taxanes are potent antimitotic agents that have demonstrated efficacy in a wide range of malignancies. Due to their poor water-solubility, these cytostatic drugs were first formulated with low molecular weight surfactants, e.g.

Membrane formation and drug loading effects in high amylose starch tablets studied by NMR imaging.

Cross-linked high amylose starch is used as an excipient in the preparation of pharmaceutical tablets for the sustained release of drugs. NMR imaging with contrast enhanced by proton density and by self-diffusion coefficient was used to follow the water uptake and swelling, two critical parameters controlling the drug release of the cross-linked starch tablets containing 10 wt % of ciprofloxacin and of acetaminophen, respectively. The drug-loaded tablets were studied in a H2O/D2O mixture at 37 degrees C in comparison to the tablets without any drug loading.

Human perception based video preprocessing for telesurgery.

Video transmission plays a critical role in robotic telesurgery because of the required high bandwidth and quality requirement. We propose an adaptive video preprocessing technique to accelerate the transmission of telesurgical video. Using this technique, the bandwidth can be reallocated adaptively from non-essential surrounding regions to the region of interest when preprocessed image sequences are passed to the video encoder, ensuring excellent image quality of critical regions (e.

Study of hydration of cross-linked high amylose starch by solid state 13C NMR spectroscopy.

Starch is subjected to chemical treatments such as cross-linking or hydroxypropylation to meet the material requirements for food uses or controlled release in the pharmaceutical industries. In this work, two types of cross-linking formulations have been employed for the preparation of high amylose starch for use as an excipient for sustained drug release. The structural differences and chain dynamics of the modified starches in the dry and hydrated states have been compared by the use of variable contact time cross polarization-magic angle spinning solid state (13)C NMR spectroscopy.

Design of the next-generation medical implants with communication energy and ports.

In this work, we provide an effective solution to the communication and power supply problems in miniature medical devices implanted within the human body. The volume conduction property of the human tissue is utilized as a natural cable for the delivery of both information and energy. A practical design is presented consisting of a small, simple, and convenient external device called an energy pad.

The future of military medicine has not arrived yet, but we can see it from here.

Throughout history, military medical personnel have provided care for their comrades in arms, often at the expense of their own lives. For many centuries, these medical personnel have applied the highest available level of knowledge and technology to the care of their patients. This paper discusses the current state of the technological art for the care of combat casualties, and discusses some of the newest technology solutions currently being developed for the provision of field medical care.

Imaging of high-amylose starch tablets. 3. Initial diffusion and temperature effects.

The penetration of water into cross-linked high amylose starch tablets was studied at different temperatures by nuclear magnetic resonance (NMR) imaging, which follows the changes occurring at the surface and inside the starch tablets during swelling. It was found that the swelling was anisotropic, whereas water diffusion was almost isotropic. The water proton image profiles at the initial stage of water penetration were used to calculate the initial diffusion coefficient.

Graft copolymers of methyl methacrylate and poly([R]-3-hydroxybutyrate) macromonomers as candidates for inclusion in acrylic bone cement formulations: Compression testing.

Graft copolymers of methyl methacrylate and biodegradable, biocompatible bacterial poly([R]-3-hydroxybutyrate) (PHB) blocks were synthesized and evaluated as possible constituents in acrylic bone cements for use in orthopaedic applications. The copolymers were produced by conventional free radical copolymerization and incorporated in one commercially available acrylic bone cement brand, Antibiotic Simplex (AKZ). Cements with formulations containing 6.

Self-assembly of precursors in single-crystal growth of biopolymers.

Self-assembly of precursors in dilute solution single-crystal growth of poly[(R)-3-hydroxyvalerate] (PHV) and the fungal polysaccharide mycodextran were studied by transmission electron microscopy, especially at the early stages of crystallization. Precursors for PHV, such as small primary nuclei and tiny square tiles, consolidate to a large square crystal composed of orthogonally arranged tiles. By contrast, the precursors of mycodextran were lath-shaped, which suggests that the crystal growth is mainly in the longitudinal direction.

Bacterial polyesters: biosynthesis, biodegradable plastics and biotechnology.

The discovery and chemical identification, in the 1920s, of the aliphatic polyester: poly(3-hydroxybutyrate), PHB, as a granular component in bacterial cells proceeded without any of the controversies which marked the recognition of macromolecules by Staudinger. Some thirty years after its discovery, PHB was recognized as the prototypical biodegradable thermoplastic to solve the waste disposal challenge. The development effort led by Imperial Chemical Industries Ltd.

Synthesis and properties of graft copolymers based on poly(3-hydroxybutyrate) macromonomers.

Graft copolymers of poly(methyl methacrylate) with poly(3-hydroxybutyrate), PHB, segments as long side chains were prepared by the macromonomer method. PHB macromonomers were prepared from the esterification of oligomers with 2-hydroxyethyl methacrylate at their carboxylic acid end. Esterification products displayed low polydispersity indices (ca.

Polyhydroxyalkanoate (PHA) granule formation in Ralstonia eutropha cells: a computer simulation.

Computer simulation of polyhydroxyalkanoate (PHA) granule formation in vivo could help to design strategies to optimize the fermentation process and achieve higher yields of PHA. It could also suggest biotechnological approaches to control the granule size and molecular weight of the polymer. A computer program simulating the formation of PHA granules inside a Ralstonia eutropha cell was developed, based on published experimental data.

Physical properties of microbial polythioesters: characterization of poly(3-mercaptoalkanoates) synthesized by engineered Escherichia coli.

Physical properties of chiral poly(thioesters), PTEs, prepared by engineered Escherichia coli, were examined by GPC, 13C CP/MAS solid-state NMR, X-ray diffraction, and thermal analysis. Microbial homopolymers of PTEs, poly(3-mercaptopropionate), PMP, and poly(3-mercaptovalerate), PMV, showed different solubility characteristics compared to poly(hydroxyalkanoates), PHAs. Generally, PTEs required higher temperatures for dissolution.

Cocrystallization model for synthetic biodegradable poly(butylene adipate-co-butylene terephthalate).

Synthetic biodegradable poly(butylene adipate-co-butylene terephthalate), P(BA-co-BT), with 56 mol % butylene adipate, BA, was characterized by solid-state NMR spectroscopy, thermal analysis, X-ray diffraction, computer modeling, and polarization microscopy. The NMR study showed the presence of BA and butylene terephthalate, BT. T(1C) NMR measurements proved that some BA and BT units were in crystalline regions.

Biosynthesis of novel thermoplastic polythioesters by engineered Escherichia coli.

The development of non-petrochemical sources for the plastics industry continues to progress as large multinationals focus on renewable resources to replace fossil carbon. Many bacteria are known to accumulate polyoxoesters as water-insoluble granules in the cytoplasm. The thermoplastic and/or elastomeric behaviour of these biodegradable polymers holds promise for the development of various technological applications.

NMR imaging of high-amylose starch tablets. 2. Effect of tablet size.

Carbohydrate polymers are widely used for pharmaceutical applications such as the controlled release of drugs. The swelling and water mobility in high-amylose starch tablets are important parameters to be determined for these applications. They have been studied at different time intervals by nuclear magnetic resonance imaging (NMRI) after the immersion of the samples in water.

One-step synthesis of amphiphilic diblock copolymers from bacterial poly([R]-3-hydroxybutyric acid).

Catalyzed transesterification in the melt is used to produce diblock copolymers of poly([R]-3-hydroxybutyric acid), PHB, and monomethoxy poly(ethylene glycol), mPEG, in a one-step process. Bacterial PHB of high molecular weight is depolymerized by consecutive and partly simultaneous reactions: pyrolysis and transesterification. The formation of diblocks is accomplished by the nucleophilic attack from the hydroxyl end-group of the mPEG catalyzed by bis(2-ethylhexanoate) tin.

The role of phasins in the morphogenesis of poly(3-hydroxybutyrate) granules.

Recent developments in the understanding of the structure of polyhydroxyalkanoate, PHA, granules in bacteria are documented in the literature and point to the role of structural proteins, phasins, in granule formation and stabilization. We have previously conceived a computer program which successfully simulates granule formation in vitro, in the absence of phasins. Now we are extending the computer model to a more complex system, including phasins, to quantify their anticipated effect on the granule properties.

Characterization of polyacrylamide-stabilized Pfl phage liquid crystals for protein NMR spectroscopy.

A new polymer-stabilized nematic liquid crystal has been characterized for the measurement of biomolecular residual dipolar couplings. Filamentous Pf1 phage were embedded in a polyacrylamide matrix that fixes the orientation of the particles. The alignment was characterized by the quadrupolar splitting of the 2H NMR water signal and by the measurement of 1H-15N residual dipolar couplings (RDC) in the archeal translation elongation factor 1beta.

Thermal degradation of poly(3-hydroxyalkanoates): preparation of well-defined oligomers.

The thermal degradation of the biodegradable bacterial polyesters poly(3-hydroxybutyrate), PHB, poly(3-hydroxyvalerate), PHV, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), 0-21 mol % of hydroxyvalerate, was studied. At moderately low temperatures (170-200 degrees C), the main product is a well-defined oligomer, especially a 500-10,000 g/mol macromolecule, which contains one unsaturated end group, predominantly a trans-alkenyl end group, as well as a carboxylic end group. The process was studied regarding the effect of the copolymer composition and reaction time at 190 degrees C.