On the Synergy Effect in MoO3–Fe2(MoO4)3 Catalysts for Methanol Oxidation to Formaldehyde

Methanol oxidation to formaldehyde was studied over a series of Fe–Mo–O catalysts with various Mo/Fe atomic ratio and the end compositions Fe₂O₃ and MoO₃. The activity data show that the specific activity passes through a maximum with increase of the Mo content and is the highest for Fe₂(MoO₄)₃. The selectivity to formaldehyde, on the other hand, increases with the Mo content in the catalyst. A synergy effect is observed in that a catalyst with the Mo/Fe ratio 2.2 is almost as active as Fe₂(MoO₄)₃ and as selective as MoO₃. Imaging of a MoO₃/Fe₂(MoO₄)₃ catalyst by SEM and TEM shows that the two phases form separate crystals, and HRTEM reveals the presence of an amorphous overlayer on the Fe₂(MoO₄)₃ crystals. EDS line-scan analysis in STEM mode demonstrates that the Mo/Fe ratio in the amorphous layer is ~2.1 in the fresh catalyst and ~1.7 in the aged catalyst. The enrichment of Mo at the catalyst surface is confirmed by XPS data. Raman spectra give evidence for the Mo in the amorphous material being in octahedral coordination, which is in contrast to the crystalline Fe₂(MoO₄)₃ bulk structure where Mo has tetrahedral coordination. X-ray diffraction (XRD) analysis gives no support for the formation of a defective molybdate bulk structure. The results presented give strong support for the Mo rich amorphous structure being observed on the Fe₂(MoO₄)₃ crystal surfaces being the active phase for methanol oxidation to formaldehyde.     

Iron antimony oxide selective oxidation catalysts – an inelastic neutron scattering study

The inelastic neutron scattering spectra of allyl iodide (3-iodopropene, CH₂=CHCH₂I) and allylpalladium chloride, and allyl iodide dosed onto activated iron(III) oxide and iron antimonate catalysts at room temperature have been determined to characterise the adsorbed allyl species. The spectra are energy loss vibrational spectra in the range 16–4000 cm⁻¹. Allyl iodide is not decomposed on the surface and interacts through the localised C = C bond, more strongly with iron antimonate than with iron(III) oxide. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dicing with Deception: People with Disabilities'' Strategies for Managing Safety and Identity Online

In the global struggle over discourse and knowledge after 9/11, the voices of otherwise silenced women in Afghanistan were significantly amplified on the Internet. RAWA.org demonstrates how a Web site contended with discourses of fundamentalism and war while envisioning democracy and constructing new leadership identities for women.     

Shedding light on catalytic ignition: coverage changes during CO oxidation on Pd(110)

Catalytic ignition or ‘light-off’ has been studied for a reaction of importance in automobile exhaust emissions, namely, CO oxidation over Pd, a metal which has become an important component of car catalysts. We present kinetic and spectroscopic studies to show that light-off is associated with a step change in surface composition of reactants as the surface is heated. Fast XPS using synchrotron radiation of high brightness reveals that the surface is dominated by CO at low temperature and the coverage suddenly switches during light-off to an oxygen-atom-dominated situation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Modeling Distributed Knowledge Processes in Next Generation Multidisciplinary Alliances*

Current research on distributed knowledge processes suggests a critical conflict between knowledge processes in groups and the technologies built to support them. The conflict centers on observations that authentic and efficient knowledge creation and sharing is deeply embedded in an interpersonal face to face context, but that technologies to support distributed knowledge processes rely on the assumption that knowledge can be made mobile outside these specific contexts. This conflict is of growing national importance as work patterns change from same site to separate site collaboration, and millions of government and industrial dollars are invested in establishing academic-industry alliances and building infrastructures to support distributed collaboration and knowledge. In this paper we describe our multi-method approach for studying the tension between embedded and mobile knowledge in a project funded by the National Science Foundation's program on Knowledge and Distributed Intelligence. This project examines knowledge processes and technology in distributed, multidisciplinary scientific teams in the National Computational Science Alliance (Alliance), a prototypical next generation enterprise. First we review evidence for the tension between embedded and mobile knowledge in several research literatures. Then we present our three-factor conceptualization that considers how the interrelationships among characteristics of the knowledge shared, group context, and communications technology contribute to the tension between embedded and mobile knowledge. Based on this conceptualization we suggest that this dichotomy does not fully explain distributed multidisciplinary knowledge processes. Therefore we propose some alternate models of how knowledge is shared. We briefly introduce the setting in which we are studying distributed knowledge processes and finally, we describe the data collection methods and the current status of the project.     

Understanding barriers to online experience for people with physical and sensory disabilities using discursive social psychology

Using social psychology, this study discursively explores barriers limiting the online experiences of people with disabilities. Twenty-one people in New Zealand with physical and sensory disabilities volunteered to participate in an online interview. Data demonstrated a disabling differentials repertoire (pattern), comprising four linguistic resources: negative reactions (when disability was disclosed), exclusion, gatekeeping, and disability costs. In addition to the technology alone, human values embedded in the construction of online technology, and participants’ cultural competency, as well as stereotyped attitudes and economic factors prevalent offline, define and restrain people with disabilities’ online experience. The social identity model of deindividuation is discussed.     

Effect of rapid thawing on the meat quality attributes of USDA select beef strip loin steaks

The objective was to determine the meat quality effects of rapidly thawing beef steaks in a water bath. Frozen beef strip loins (n = 24) were cut into steaks sequentially from the rib end and identified by anatomical location (anterior, middle, posterior) within the loin. Within location, steaks were randomly assigned to conventional (C; 18 to 20 h, 4 °C) or rapid thawing methods. Rapid thawing methods, fast (20 min, 20 °C) or very fast (11 min, 39 °C), were conducted in a circulating water bath. The physical, thawing, cooking, color, and texture characteristics of each steak were recorded. Data were analyzed as a randomized complete block design with a 3 thawing treatments × 3 locations factorial analysis with loin as a block. No location by thawing method interaction was detected (P > 0.05) for the measured variables. Compared to C steaks, rapidly thawed steaks exhibited lower thaw drip loss (P < 0.001) and higher a* values (P < 0.001). Thawing treatment did not influence L*, b*, cook yield, or shear force. Steaks from the posterior end had higher (P < 0.001) surface to volume ratios that may have contributed to the higher thaw loss (P < 0.01), longer cooking time (P < 0.001), lower cooking yield (P < 0.001), and higher shear force (P < 0.02) compared to steaks from the anterior and middle portions of the loins. These data indicate that beef steaks taken from the entire length of the loin can be rapidly thawed in a water bath following food safety guidelines with minimal impact on meat quality. Practical Application: Freezing rate and frozen storage effects on meat quality have been well documented; however, there is comparatively little information on the meat quality effects of rapid thawing within food safety guidelines. This study demonstrates that beef strip loin steaks can be rapidly thawed in as few as 11 min without affecting texture or cooking yield, while reducing thaw drip loss. Thus, rapid thawing may enhance the apparent juiciness of steaks for consumers and provide an effective method for maintaining consistent control of experimental conditions for researchers.