Evaluation of polycaprolactone − poly‐D,L‐lactide copolymer as biomaterial for breast tissue engineering

The potential of the copolymer polycaprolactone‐co‐ poly‐d ,l ‐lactic acid (PCLLA ) as a biomaterial for scaffold‐based therapy for breast tissue engineering applications was assessed. First, the synthesized PCLLA was evaluated for its processability by means of additive manufacturing (AM ). We found that the synthesized PCLLA could be fabricated into scaffolds with an overall gross morphology and porosity similar to that of polycaprolactone. The PCLLA scaffolds possessed a compressive Young's modulus (ca 46 kPa ) similar to that of native breast (0.5 ? 25 kPa ), but lacked thermal stability and underwent thermal degradation during the fabrication process. The PCLLA scaffolds underwent rapid degradation in vitro which was characterized by loss of the scaffolds' mechanical integrity and a drastic decrease in mass‐average molar mass (M _w) and number‐average molar mass (M _n) after 4 weeks of immersion in phosphate buffer solution maintained at 37 °C. The tin‐catalysed PCLLA scaffold was also found to have cytotoxic effects on cells. Although the initial mechanical properties of the PCLLA scaffolds generally showed potential for applications in breast tissue regeneration, the thermal stability of the copolymer for AM processes, biocompatibility towards cells and degradation rate is not satisfactory at this stage. Therefore, we conclude that research efforts should be geared towards fine‐tuning the copolymer synthesizing methods. © 2016 Society of Chemical Industry     

Comprehensive evaluation of a CO2‐capturing high‐efficiency power generation system for utilizing waste heat from factories

It is becoming more important to realize CO₂‐capturing power generation systems (PGSs) for drastically decreasing an amount of CO₂ emission into the atmosphere. However, net power generation efficiency (NPGE) of a CO₂‐capturing system has been considered to be greatly deteriorated, since capturing CO₂ requires extra energy. This paper proposes a new CO₂‐capturing PGS that has a high‐efficient NPGE by utilizing waste heat from factories. As an example of a waste heat, exhaust gas with temperature 200°C from refuse incinerator plants is adopted. In the proposed system, the temperature of saturated steam produced by utilizing the waste heat is raised by combusting fuel with the use of pure oxygen in a combustor, and is used as the main working fluid of a gas turbine PGS. It is estimated that the proposed system has a fuel‐to‐electricity NPGE of 59.3%, when turbine inlet temperature (TIT) is assumed to be 1000°C. The economics of the proposed system is also evaluated and the CO₂ reduction cost is estimated to be small; 4.16 U.S. $ t⁻¹ CO₂ compared with 32.1 U.S. $ t⁻¹ CO₂ for a conventional steam turbine PGS. It is shown that CO₂‐capturing is not cost consuming but becomes to be profitable owing to improved power generation characteristics, when its TIT is increased from 1000 to 1200°C. Copyright © 2009 John Wiley & Sons, Ltd.     

An application of polarized domains in ferroelectric thin films using scanning probe microscope

The feasibility of utilizing PZT films as future data storage media was investigated using a modified AFM. Applying voltages between a conductive AFM tip and the PZT films causes the switching of ferroelectric domains. The domains are observed using an EFM imaging technique. The experimental results and calculations revealed that the electrostatic force generated between the polarized area and the tip is a main contributor for the imaging of the polarized domains. The written features on ferroelectric films were less than 100 nm in diameter, implying the possibility of realizing data storage devices with ultra-high area density. The disappearance of the polarized images without any applied voltage was observed, which is a drawback in this application of PZT thin films.     

XR-C1, a new CHO cell mutant which is defective in DNA-PKcs, is impaired in both V(D)J coding and signal joint formation

DNA-dependent protein kinase (DNA-PK) plays an important role in DNA double-strand break (DSB) repair and V(D)J recombination. We have isolated a new X-ray-sensitive CHO cell line, XR-C1, which is impaired in DSB repair and which was assigned to complementation group 7, the group that is defective in the XRCC7 / SCID ( Prkdc ) gene encoding the catalytic subunit of DNA-PK (DNA-PKcs). Consistent with this complementation analysis, XR-C1 cells lackeddetectable DNA-PKcs protein, did not display DNA-PK catalytic activity and were complemented by the introduction of a single human chromosome 8 (providing the Prkdc gene). The impact of the XR-C1 mutation on V(D)J recombination was quite different from that found in most rodent cells defective in DNA-PKcs, which are preferentially blocked in coding joint formation, whereas XR-C1 cells were defective in forming both coding and signal joints. These results suggest that DNA-PKcs is required for both coding and signal joint formation during V(D)J recombination and that the XR-C1 mutant cell line may prove to be a useful tool in understanding this pathway.     

Somatic antigens of pseudomonads: structure of the O-specific polysaccharide of Pseudomonas fluorescens biovar B, strain IMV 247

The O-specific polysaccharide of Pseudomonas fluorescens biovar B, strain IMV 247, was studied by acid hydrolysis, GLC-MS and 1H and 13C NMR spectroscopy, including 1D and 2D NOE, 2D hybrid TOCSY and ROESY (TORO), and 2D H-detected heteronuclear multiple-bond correlation (HMBC) experiments. The polysaccharide was found to contain L-rhamnose, 3.6-dideoxy-3-[(S)-3-hydroxybutyramido]-D-glucose (D-Qui3NHb), 2-acetamido- 2,4,6-trideoxy-4-[(S)-3-hydroxybutyramido-D-glucose (D-QuiNAc4NHb) and 2-acetamido-2- deoxy-D-galacturonic acid (D-GalNAcA). Partial acid hydrolysis of the polysaccharide resulted in a non-reducing GalNAcA-->QuiNAc4NHb disaccharide with the 3-hydroxybutyryl group glycosylated intramolecularly by the QuiN4N residue. The following structure of the tetrasaccharide repeating unit of the polysaccharide was established:-->4) -alpha-D-GalpNAcA-(1-->3)- alpha-D-QuipNAc4NHb-(1-->2)-beta-D-Quip3NHb-(1-->2)-alpha-L- Rhap(1-->.     

Toxicity of the styrene metabolite, phenylglyoxylic acid, in rats after three months' oral dosing

Male Wistar rats were dosed with 0, 1250, 3750 or 5000 mg/l of phenylglyoxylic acid (PGA) (CAS no. 611-73-4) in the drinking water ad libitum for 3 months. During the entire treatment period, there were no gross signs of toxicity related to PGA. No changes in neurobehavior were found after using a functional observational battery or radial arm maze. An increased relative kidney weight was seen in the highest dose-group (Controls: 0.504 +/- 0.031 g/100 g b.wt.; 5000 mg PGA/l: 0.579 +/- 0.033 g/100 g b.wt.; p<0.01). No other organ weights were affected. Histopathology revealed no change in kidney structure. No changes in clinical biochemistry. In the highest dose-group three animals out of ten showed reduction in peripheral nerve myelin sheath thickness. No such changes were seen in the control group. The study revealed no changes in auditory brain stem response but minor changes in electroretinography. The noradrenaline (NA) concentration decreased in pons and thalamus whereas it increased in medulla oblongata and whole brain. The dopamine (DA) concentration increased in cerebellum, hippocampus, pons, and whole brain. The most marked DA increase was seen in hippocampus (Controls: 0.56 +/- 0.10 nmol/g tissue; 5000 mg/l: 1.04 +/- 0.11 nmol/g tissue; p<0.001). The 5-hydroxytryptamine (5-HT) concentration decreased in cerebellum, cerebral cortex, hippocampus, and medulla oblongata, whereas it increased in thalamus. The yield of synaptosomal protein, synaptosomal NA, DA, and 5-HT concentrations, and DA uptake rate were not affected. When dosed males were mated with naive females, there were no differences between groups in the pregnancy rate, number of corpora luteae, implantations, live or dead fetuses, resorptions, preimplantation loss, or postimplantation loss. It is concluded that a part of the effects on kidney, peripheral nerves, and vision, which have previously been reported after exposure to styrene, might be induced by the styrene metabolite, PGA. If PGA has ototoxic effects in rats, the dosing in the present study is not sufficient to induce the necessary ototoxic concentration in blood. Alternatively, the ototoxicity of styrene, like toluene, may be caused the parent compound itself and not by a metabolite like PGA.