Effect of ageing and annealing on the mechanical behaviour and biodegradability of a poly(3‐hydroxybutyrate) and poly(ethylene‐co‐methyl‐acrylate‐co‐glycidyl‐methacrylate)blend

Poly(3‐hydroxybutyrate) (PHB) undergoes an ageing process that contributes to its remarkable fragility. Blending it with an elastomer is a possibility to increase toughness. In this work, the mechanical properties of a 70/30 wt% blend of PHB and poly(ethylene‐co‐methyl‐acrylate‐co‐glycidyl‐methacrylate) were studied over time. The phenomenon of ageing affected the blend, which lost its ductility and became fragile days after its processing. Differential scanning calorimetry and small angle X‐ray scattering analyses showed that this drop in mechanical properties was due to changes in the crystalline structure of the matrix. Annealing reduced fragility, increased toughness and prevented a re‐ageing of the blend. Biodegradation in soil was also more intense for annealed samples. © 2013 Society of Chemical Industry     

吊臂运输车

一种新型超重吨位轮式起重机的伸缩臂如此大。以至于要分成两部分来运输才行．且其中的一段需要特种运输车来运输。     

Phospholipid bilayer coatings for the separation of proteins in capillary electrophoresis

The double-chained, zwitterionic phospholipid 1,2-dilauroyl-sn-phosphatidylcholine (DLPC, C12) was investigated for its use as a wall coating for the prevention of protein adsorption in capillary electrophoresis. DLPC forms a semipermanent coating at the capillary wall, which allows excess phospholipid to be removed from the capillary prior to electrophoretic separation. A DLPC-coated capillary allowed for the separation of both cationic and anionic proteins with efficiencies as high as 1.4 million plates/m. Migration time reproducibility was less than 1.3% RSD from run to run and less than 4.0% RSD from day to day. Protein recovery was as high as 93%. Cationic and anionic proteins could be separated over a pH range of 3-10, all yielding good efficiencies (N up to 1 million plates/m). The chain length of the phospholipid affected the performance of the wall coating. The C10 analogue of DLPC (DDPC) did not form a coating on the capillary wall while the C14 analogue of DLPC (DMPC) formed a stable coating that prevented protein adsorption to the same extent as its C12 counterpart.     

Why Napster matters to writing: Filesharing as a new ethic of digital delivery

This article discusses the Napster phenomenon and its cultural significance, traces some of the threads of the current “copyright crisis,” and connects these cultural and legal dynamics to show how the current filesharing context of digital environments pertains to issues affecting writing teachers. The article (1) urges writing teachers to view the Napster moment—and the writing practice at the center of it, filesharing—in terms of the rhetorical and economic dynamics of digital publishing and in the context of public battles about copyright and intellectual property and (2) argues that digital filesharing forms the basis for an emergent ethic of digital delivery, an ethic that should lead composition teachers to rethink pedagogical approaches and to revise plagiarism policies to recognize the value of filesharing and to acknowledge Fair Use as an ethic for digital composition.     

Discrete Working Time Choice in an Applied General Equilibrium Model

We present a model that integrates the discrete working time choice of heterogenous households into a general equilibrium setting where wages are determined by sectoral bargaining between firms and trade unions. The model is calibrated to German micro and macro data. We then use it to analyse a stylised policy reform designed to stimulate labour supply. JEL Code: D58, J22, J51 An erratum to this article can be found at     

Need for recovery from work: evaluating short-term effects of working hours,patterns and schedules

In this paper working hours, patterns and work schedules of employees were evaluated in terms of need for recovery from work. Self-administered questionnaire data from employees of the Maastricht Cohort Study on Fatigue at Work (n = 12,095) were used. Poisson regression analyses and multivariate logistic regression analyses revealed that higher working hours a day and working hours a week generally went together with more need for recovery from work. Overtime work was particularly associated with higher need for recovery from work in both genders. Both male and female three-shift or irregular shift workers had higher odds of elevated need for recovery compared to day workers. When additionally controlling for work-related factors, need for recovery levels among shift workers substantially lowered. This study clearly showed that working hours and schedules are associated with need for recovery from work, with different associations for men and women. Especially the associations between work schedules and need for recovery from work were very interrelated with other work-related factors. Future studies could further investigate the possibility that shift work might function as a proxy of other work-related factors that explain the different levels in need for recovery from work, or that job demands are perceived higher among shift workers and may therefore lead to more need for recovery from work.     

Resonance and nonresonant laser ionization of sputtered uranium atoms from thin films and single microparticles: evaluation of a combined system for particle trace analysis

The resonance and nonresonant laser ionization of uranium atoms sputtered from thin metal films and individual micrometer-size uranium oxide particles, respectively, was studied to evaluate a new setup for the analysis of actinide-containing micrometer-size particles. Experiments using nonresonant (193-nm) ionization of atoms and molecules sputtered from micrometer-size uranium oxide particles have shown that the uranium detection efficiencies for sputtered neutral atoms are approximately 2 orders of magnitude higher than for secondary ions. In uranium particles of 0.5-microm diameter, 6 x 10(6) atoms of 235U were easily detected and the isotopic ratio of 235U/238U = 0.0048 +/- 4.6% is in excellent agreement with the certified value. The use of two-color, two-step resonance ionization of the sputtered neutral uranium atoms from thin films was investigated. Several excitation schemes were tested, and a significant population of several low-lying metastable states after ion sputtering was observed. Autoionizing states for double-resonant ionization were determined, and the high selectivity of ionization schemes involving these autoionizing states was illustrated by comparing the flight-time distributions of different sputtered species obtained both by resonance and nonresonant multiphoton (355-nm) laser postionization. Ideally, the options for resonance as well as nonresonant ionization would be combined in a single setup, to obtain a large gain in sensitivity and selectivity. Thus, information about the main components as well as specific isotopic information of a trace element could be obtained from the same single particle.