Phase transitions in ultraoriented polyethylene fibers under moderate pressures: A synchrotron X-ray study

The effect of pressure on phase transformations of ultradrawn ultra-high-molecular-weight polyethylene (UHMWPE) fibers was examined by in situ X-ray diffraction measurements with synchrotron radiation. The mesomorphic hexagonal phase was metastable even at a relatively low pressure of about 100 bar. The effect of pressure on the melting transitions was larger than in chain-folded structures. The existence and metastability of the hexagonal phase is the basis of compaction technology of UHMWPE fibers in composite materials. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 53–59, 2004     

Synthesis,Characterization, Cytotoxicity,and Hydrolytic Behavior of C2‐ and C1‐Symmetrical TiIV Complexes of Tetradentate Diamine Bis(Phenolato) Ligands: A New Class of Antitumor Agents

Carefully design your ligand! A new family of highly cytotoxic Ti^IV complexes demonstrates strong dependence of activity on the particular ligand employed, in which small structural modifications dramatically affect both hydrolytic behavior and biological activity (see picture). Different structure‐dependence patterns are observed for hydrolysis and cytotoxicity, which are, nonetheless, strongly related.

     

The newsvendor problem with unknown distribution

Newsvendor theory assumes that the decision-maker faces a knowndistribution. But in real-life situations, demand distribution is not alwaysknown. In the experimental study which this paper presents, half of theparticipants assuming the newsvendor role were unaware of the underlying demanddistribution, while the other half knew the demand distribution. Participantshad to decide how many papers to order each day (for 100 days). The experimentalfindings indicate that subjects who know the demand distribution behavedifferently to those who do not. However, interestingly enough, knowing thedemand distribution does not necessarily lead the subject closer to the optimalsolution or improve profits. It was found that supply surplus at a certainperiod strongly affects the order quantity towards the following period, despitethe knowledge of the demand distribution.     

Kinetics and mechanism of acrylonitrile polymerization by p-toluenesulfinic acid. II. Polymerization mechanism

The retardation of acrylonitrile (AN) polymerization by p-toluenesulfinic acid (TSA) in the presence of relatively strong acids has been further investigated. Conductance measurements supported the hypothesis that an ionic complex, presumably RSO₂H₂⁺, is obtained by a reaction of the sulfinic acid with a proton. It is postulated that this complex is a chain transfer agent for the observed retardation. On the basis of this assumption, a kinetic scheme was developed involving additional termination steps by the complex. The scheme accounts for the maximum in initial rate observed on increasing the concentration of added sulfonic acid at a constant TSA concentration. It also provides an explanation for the elimination of the autoacceleration in the bulk polymerization of AN when strong acids are added. The orders derived from the kinetic equations are in good agreement with the orders evaluated from the kinetic experiments.