2,260 research outputs found

    Report on Characterization of U-10 wt.% Zr Alloy

    Get PDF
    This report summarizes the chemical and structural characterization results for a U-10 wt.% Zr alloy to be used in an ultra-high burn-up nuclear fuel concept. The as-cast alloy material was received from Texas A and M University. Characterization and an initial heat treatment of the alloy material were conducted at Lawrence Livermore National Laboratory. The as-received ingot was sectioned for X-ray analysis, metallography, SEM, TEM, and heat treatments, as shown in Figure 1

    Ethyl Lactate Production from the Catalytic Depolymerisation of Post‑consumer Poly(lactic acid)

    Get PDF
    Bioplastics such as poly(lactic acid) (PLA), which are derived from renewable sources, promoted as biodegradable and implemented for numerous functions, offer a promising alternative to the enduring synthetic plastics abundant in society. However, the degradation of PLA is slow under natural environmental conditions. A chemical recycling route is thus required to couple mitigation of plastic persistence repercussions with circular economy adherence. In the present work, the production of ethyl lactate by the catalysed transesterification of post-consumer PLA was investigated. The catalyst employed was a propylendiamine Zn(II) complex. The PLA samples investigated consisted of a phone case, an infant’s toy, a film, a cup and 3D printing material. Degradation reactions were studied at 50 °C and 90 °C and the concentrations measured at two different time intervals, 1 h and 3 h. The results revealed that greater activity of the catalyst was observed at 50 °C for two PLA samples (cup, 3D print). PLA film achieved the greatest lactate yield (71%) of all samples after 3 h at 50 °C. It is concluded that the propylenediamine Zn(II) catalyst can be used to produce green solvent ethyl lactate at mild temperatures from post-consumer PLA, even in the presence of unknown additives

    Zinc complexes for PLA formation and chemical recycling

    Get PDF
    A series of Zn II complexes, based on propylenediamine Schiff bases, have been prepared and fully characterized. X-ray crystallography and NMR spectroscopy identified significant differences in the solid and solution state for the Zn II species. All complexes have been applied to the ring-opening polymerization of l-lactide with emphasis on industrial conditions. High conversion and good molecular weight control were generally achievable for Zn(A–D) 2, and high-molecular-weight poly(lactic acid) (PLA) was prepared in 1 min at a 10 000:1:33 [lactide]/[Zn]/[BnOH] loading. The more active Zn II catalysts were also applied to PLA degradation to alkyl lactate under mild conditions. Zn(A–B) 2 demonstrated high activity and selectivity in this process with PLA being consumed within 1 h at 50 °C. Zn(C–D) 2 were shown to be less active, and these observations can be related to the catalysts’ structure and the degradation mechanism. Initial results for the degradation of poly(ethylene terephthalate) and mixed feeds are also presented, highlighting the broader applicability of the systems presented

    Observation of Parity Nonconservation in Møller Scattering

    Get PDF
    We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A_(PV) = [-175 ± 30(stat)± 20(syst)] X 10^(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron’s weak charge at low energy Q^e_W = -0:053 ± 0:011. This is consistent with the standard model expectation at the current level of precision: sin^2θ_W = (M_Z)_(MS) = 0:2293 ± 0:0024(stat) ± 0:0016(syst) ± 0:0006(theory)

    Kinetics of Alkyl Lactate Formation from the Alcoholysis of Poly(Lactic Acid)

    Get PDF
    Alkyl lactates are green solvents that are successfully employed in several industries such as pharmaceutical, food and agricultural. They are considered prospective renewable substitutes for petroleum-derived solvents and the opportunity exists to obtain these valuable chemicals from the chemical recycling of waste poly(lactic acid). Alkyl lactates (ethyl lactate, propyl lactate and butyl lactate) were obtained from the catalysed alcoholysis reaction of poly(lactic acid) with the corresponding linear alcohol. Reactions were catalysed by a Zn complex synthesised from an ethylenediamine Schiff base. The reactions were studied in the 50–130 °C range depending on the alcohol, at autogenous pressure. Arrhenius temperature-dependent parameters (activation energies and pre-exponential factors) were estimated for the formation of the lactates. The activation energies (Ea1, Ea2 and Ea−2) for alcoholysis in ethanol were 62.58, 55.61 and 54.11 kJ/mol, respectively. Alcoholysis proceeded fastest in ethanol in comparison to propanol and butanol and reasonable rates can be achieved in temperatures as low as 50 °C. This is a promising reaction that could be used to recycle end-of-life poly(lactic acid) and could help create a circular production economy

    Non-Markovian effects on non-locality of a qubit-oscillator system

    Get PDF
    Non-Markovian evolutions are responsible for a wide variety of physically interesting effects. Here, we study non-locality of the non-classical state of a system consisting of a qubit and an oscillator exposed to the effects of non-Markovian evolutions. We find that the different facets of non-Markovianity affect non-locality in different and non-obvious ways: ranging from pronounced insensitivity of the Bell function to quite a spectacular evidence of information kick-back.Comment: 7 pages, 3 figures, RevTeX

    Programming Protocol-Independent Packet Processors

    Full text link
    P4 is a high-level language for programming protocol-independent packet processors. P4 works in conjunction with SDN control protocols like OpenFlow. In its current form, OpenFlow explicitly specifies protocol headers on which it operates. This set has grown from 12 to 41 fields in a few years, increasing the complexity of the specification while still not providing the flexibility to add new headers. In this paper we propose P4 as a strawman proposal for how OpenFlow should evolve in the future. We have three goals: (1) Reconfigurability in the field: Programmers should be able to change the way switches process packets once they are deployed. (2) Protocol independence: Switches should not be tied to any specific network protocols. (3) Target independence: Programmers should be able to describe packet-processing functionality independently of the specifics of the underlying hardware. As an example, we describe how to use P4 to configure a switch to add a new hierarchical label

    Unsuitable for ICU: what happens next?

    Get PDF

    Education for collaboration: the influence of the third space on professional boundaries

    Get PDF
    The delivery of integrated care requires the establishment of effective professional relationships that foster collaborative working across health systems. Evidence for how to prepare practitioners to work in those settings is limited. By exploring an innovative postgraduate Programme for Integrated Child Health (PICH) this article highlights the conditions by which effective collaboration can be encouraged. Our qualitative evaluation of PICH involved one-to-one semi-structured interviews with 23 postgraduate general practice and paediatric trainees and their mentors. We analysed the data using the concept of the ‘third space’, where multiple discourses between individuals with diverse professional backgrounds occur, enabling creative exploration of tensions inherent in new ways of working in order to identify enablers and barriers to collaboration. Our analysis identified three themes that enabled collaboration: effective communication, boundary work and educational spaces; and four themes that were barriers: traditional hierarchical professional identities, curriculum design, financial systems and workplace spaces. PICH demonstrated the value of educational spaces and their role in enabling collaborative practice, as participants explored their professional identities and those of other disciplines. Structural factors in the workplace which inhibit collaborative practice were also evident. We conclude by proposing a model for collaborative learning in third spaces based upon the recognition that, while educational programmes alone will not lead to change, they have the potential to inform the development of productive workplace spaces that will be required if collaborative practice in healthcare is to become a reality
    • …
    corecore