Structure and mobility of a series of poly(alkyl L-glutamate)s studied by VT C-13 CPMAS NMR spectroscopy

VT CPMAS NMR measurements were carried out for a series of poly(alkyl L-glutamate)s (PALG) which have n-alkyl side chains with carbon numbers ranging from 2 to 12 in order to investigate the structure and mobility of the main and the side chains. From the temperature dependencies of the peak intensities for the PALGs, the relative mobilities of the main and side chains are discussed. For PG-2 and PG-4, the molecular motions of both the main and side chains are not very fast. From the amount ratio between the main and side chains, the main chain dominates the entire mobility of the polymer. As the side chain length increases, the side chain motion is drastically activated by a temperature change. In addition, the main chain motion is induced by the side chain motion. For PALGs with long alkyl side chains, the mobilities of the polymers are governed by the structure and mobility of the side chain

Molecular motion of the main chain for a series of poly(alkyl L-glutamate)s as studied by H-2 NMR

H-2 NMR measurements were carried out for a series of poly(alkyl L-glutamate)s (PALG) in which the H-1 of the amide group in the main chain is replaced by H-2 in order to investigate the mobility and motional mode of the main chain. At low temperature, the H-2 spectra were typical powder patterns, which have three principal values. The temperature dependencies for the H-2 NMR spectra varied with the side chain length. For PALG with a short side chain length, Deltanu(1), Deltanu(2), and Deltanu(3) are almost constant in all temperature ranges. As the side chain length increases, the difference between the peaks and shoulders decreased with temperature. For PG-12-N-D, the peaks and shoulders are fused at high temperature in a liquid crystalline state. The mobility and molecular motion of the main chain is discussed based on the obtained H-2 NMR spectra

Morphology of drawn syndiotactic polypropylene films

Morphological studies were conducted to investigate the drawability of melt-quenched (MQ) and slowly cooled (MSC) films of syndiotactic polypropylene (sPP) with a high syndiotactic pentad fraction. Transmission electron microscopy (TEM) using the ruthenium tetraoxide staining and ultrathin sectioning method revealed that amorphous chains as the matrix of MQ film played a role in drawability of the film by their alignment to machine direction (MD) and partial crystallizations into nanofibrils. On the other hand, the initial strain induced, rotations of clusters of long lamellar crystals as the major entity of MSC film accompanying breaks of long lamellae and formation of crazes and microvoids at the cluster boundary. Compared with a homogeneous thinning of MQ film by drawing, ca. 100 nm-thick layer slips along MD and parallel to the film surface took place in MSC film. This gave rise to the formation of V-shaped bent lamellar morphology and their further break into a smaller cluster of stacked lamellae which were aligned oblique by ca. 35 from MD. With elongation, some nanofibrils formed from chains generated by the partial breaks of lamellae are aligned perpendicular to the remained oblique lamellae and others parallel to MD in region where lamellar morphology almost disappeared. No chain slips in the nanofibrils can be related to a low elongation at break, i.e. a low ductility of sPP films. The lower elongation at break for MSC film than for MQ one can be interpreted by microvoids initially formed in the neck region and later moved to the fully drawn part, the microvoids initiating the break of the drawn film

Synthesis and properties of radiopaque polymer hydrogels: polyion complexes of copolymers of acrylamide derivatives having triiodophenyl and carboxyl groups and p-styrene sulfonate and polyallylamine

In order to pursue a possibility of application of radiopaque polymer hydrogels to vascular embolization, studies were done on synthesis of iodine-containing copolyanions and properties of their hydrogels with polycation via formation of polyion complexes. Acrylamide derivatives having triiodophenyl and carboxyl groups were synthesized and copolymerized with sodium styrene sulfonate at various molar ratios of initiator to monomer and temperatures. Hydrogels were prepared by mixing aqueous solutions of the obtained radiopaque copolyanions and polyallylamine. Embolization was examined by injection of these hydrogels into vein of a removed porcine kidney as a preliminary test for transcatheter arterial embolization (TAE) for hepatocellular carcinoma. It was found that the hydrogels prepared from the copolycation obtained under particular conditions give high X-ray contrasts of the vein and remained there, though copolycations with low molecular weights had a tendency to drain through the capillaries to the peripheral tissues. It is therefore concluded that the hydrogels examined in the present study are promising for vascular embolization

Single particle effects in precompound decay reactions

Precompound decay models generally rely on use of a partial state density (PSD) formula which is generated using an assumed equidistantly spaced set of single particle levels. This is a reasonable assumption for mid-shell nuclei; however it has been demonstrated that quite large errors may be introduced by making the equidistant spacing assumption for nuclei which have neutron or proton numbers near or at major shell closures. This work reviews the simple qualitative considerations of those deviations expected for near closed shell nuclei, these expectations are compared with experimental results, and steps are taken to implement use of partial state densities calculated with more realistic sets of single particle levels in precompound decay calculations. This is done for the case of Zr targets. 13 refs., 14 figs

A manufacturing framework for capability-based product-service systems design

Manufacturers aim to design product-service systems (PSS) which integrate services with products to attain sustained competitive advantage from a life cycle perspective. PSS design should be customer-adjusted solutions which are aligned to integrated stakeholders' capabilities, a subject which the extant literature has not sufficiently addressed. This paper proposes a systematic framework for the PSS solution provider to address this aim and operationalizes this through software developed for PSS design which models stakeholders' individual activities and simulates their occurrences depending on their relations. The framework stresses that integrated stakeholders' capabilities define continuing ability to generate a desired operational outcome for the customers. The paper reports a PSS design case for a laser system manufacturer and then applies the framework to it. The industrial experts' views on this framework reveal that it helps to develop PSS design from a holistic systems approach which facilitates a change in the designer's mindset from product-centric to systems-centric. The level of trust and transparency required for this framework is argued to be absent in most industrial sectors, being one of the foremost limitations for implementation of PSS