The Direct Sandwich Composite Molding (D-SCM) Process: Sandwich Manufacturing and Characterization

Sandwich structures benefit from the geometrical stiffening effect due to their high cross-sectional area moment of inertia. Transferred to carbon fiber-reinforced plastic (CFRP) components, the needed amount of carbon fiber (CF) material can be reduced and with it the CO$_{2}$ footprint. The combination of a light foam core with continuous fiber-reinforced face sheets is a suitable material combination for lightweight design. Traditionally, CFRP sandwich structures with a foam core are manufactured in a two-step process by combining a prefabricated foam core with fiber-reinforced face sheets. However, in addition to the reduction in the used CFRP material, manufacturing processes with a high efficiency are needed. The objective of this paper is the sandwich manufacturing and characterization by using the Direct Sandwich Composite Molding (D-SCM) process for the one-step production of CFRP sandwich structures. The D-SCM process utilizes the resulting foaming pressure during the reactive polyurethane (PUR) foam system expansion for the impregnation of the CF-reinforced face sheets. The results of this work show that the production of sandwich structures with the novel D-SCM process strategy is feasible in one single manufacturing step and achieves good impregnation qualities. The foam density and morphology significantly influence the core shear properties and thus the component behavior under a bending load

Study of pressure effect on the magnetic penetration depth in MgB2_2

A study of the pressure effect on the magnetic penetration depth $\lambda$ in polycrystalline MgB$_{2}$ was performed by measuring the temperature dependence of the magnetization under an applied pressure of 0.15 and 1.13 GPa. We found that $\lambda^{-2}$ at low temperature is only slightly affected by pressure [$\frac{\Delta \lambda^{-2}}{\lambda^{-2}} = 1.5(9)$], in contrast to cuprate superconductors, where, in the same range of pressure, a very large effect on $\lambda^{-2}$ was found. Theoretical estimates indicate that most of the pressure effect on $\lambda^{-2}$ in MgB$_2$ arises from the electron-phonon interaction.Comment: 5 pages, 2 figure

Finite-size and pressure effects in YBa_2Cu_4O_8 probed by magnetic field penetration depth measurements

We explore the combined pressure and finite-size effects on the in-plane penetration depth \lambda_{ab} in YBa_2Cu_4O_8. Even though this cuprate is stoichiometric the finite-size scaling analysis of \lambda_{ab}^{-2}(T) uncovers the granular nature and reveals domains with nanoscale size L_{c} along the c-axis. L_{c} ranges from 33.2 Angstrom to 28.9 Angstrom at pressures from 0.5 to 11.5 kbar. These observations raise serious doubts on the existence of a phase coherent macroscopic superconducting state in cuprate superconductors.Comment: 7 pages, 6 figure

High-altitude glacier archives lost due to climate change-related melting.

Global warming has caused widespread surface lowering of mountain glaciers. By comparing two firn cores collected in 2018 and 2020 from Corbassière glacier in Switzerland, we demonstrate how vulnerable these precious archives of past environmental conditions have become. Within two years, the soluble impurity records were destroyed by melting. The glacier is now irrevocably lost as an archive for reconstructing major atmospheric aerosol components

Pressure effects on the transition temperature and the magnetic field penetration depth in the pyrochlore superconductor RbOs_2O_6

We report magnetization measurements under high hydrostatic pressure in the newly discovered pyrochlore superconductor RbOs_2O_6 (T_c\simeq6.3K at p=0). A pronounced and {\it positive} pressure effect (PE) on T_c with dT_c/dp =0.090(1)K/kbar was observed, whereas no PE on the magnetic penetration depth \lambda was detected. The relative pressure shift of T_c [ dlnT_c/dp \simeq 1.5%/kbar] is comparable with the highest values obtained for highly underdoped high-temperature cuprate superconductors. Our results suggest that RbOs_2O_6 is an adiabatic BCS-type superconductor.Comment: 11 pages, 4 figure

Are isomeric alkenes used in species recognition among neo-tropical stingless bees (Melipona spp)

The majority of our understanding of the role of cuticular hydrocarbons (CHC) in recognition is based largely on temperate ant species and honey bees. The stingless bees remain relatively poorly studied, despite being the largest group of eusocial bees, comprising more than 400 species in some 60 genera. The Meliponini and Apini diverged between 80-130 Myr B.P. so the evolutionary trajectories that shaped the chemical communication systems in ants, honeybees and stingless bees may be very different. Therefore, the main aim of this study was to study if a unique species CHC signal existed in Neotropical stingless bees, as shown for many temperate species, and if so what compounds are involved. This was achieved by collecting CHC data from 24 colonies belonging to six species of Melipona from North-eastern Brazil and comparing this new data with all previously published CHC studies on Melipona. We found that each of the eleven Melipona species studied so far each produced a unique species CHC signal based around their alkene isomer production. A remarkable number of alkene isomers, up to 25 in M. asilvai, indicated the diversification of alkene positional isomers among the stingless bees. The only other group to have really diversified in alkene isomer production are the primitively eusocial Bumblebees (Bombus spp), which are the sister group of the stingless bees. Furthermore, among the eleven Neotropical Melipona species we could detect no effect of the environment on the proportion of alkane production as has been suggested for some other species

Introduction: exploring and explaining the Asia-Pacific Partnership on Clean Development and Climate

This introduction lays the groundwork for this Special Issue by providing an overview of the Asia-Pacific Partnership on Clean Development and Climate (APP), and by introducing three main analytical themes. The first theme concerns the emergence and continuation of the APP. The contributions show that the emergence of the APP can be attributed to international factors, including the United States' rejection of the Kyoto Protocol, and its search for an alternative arena for global climate governance, and other countries' wish to maintain good relations with the US; as well as domestic factors, such as the presence of bureaucratic actors in favour of the Partnership, alignment with domestic priorities, and the potential for reaping economic benefits through participation. The second theme examines the nature of the Partnership, concluding that it falls on the very soft side of the hard-soft law continuum and that while being branded as a public-private partnership, governments remain in charge. Under the third theme, the influence which the APP exerts on the post-2012 United Nations (UN) climate change negotiations is scrutinised. The contributions show that at the very least, the APP is exerting some cognitive influence on the UN discussions through its promotion of a sectoral approach. The introduction concludes with outlining areas for future research. © Springer Science+Business Media B.V. 2009

Industrial Roller Milling Process Characterisation for Targeted Bread Quality Optimization

Out of all satisfying and palatable foods, wheat and other cereals play an essential role in human nutrition. In recent years, customers demand for functionalized flours with engineered properties contributing to well-being. This fuels the need for deeper understanding of the milling process and establishment of relationships between flour properties and product characteristics. To address this shortcoming, structural and functional aspects of starch and protein were investigated in all 33 flour passages obtained during the standard roller milling process of the most widely produced bread flour. Starch and protein alterations were examined on flour, dough and bread levels. Repeated milling cycles and higher impact towards tail-end passages result in compositional differences and increase in damaged starch. This creates weakened gluten networks exhibiting reduced elasticity and extensibility. Decreased viscoelasticity and hence gas-holding capacity result in low loaf volume. With multiple multivariate linear regression, a model could be established allowing for a 95% precise prediction of the loaf volume of the passages and composite flour produced with the same mill settings. This quality prediction of bread quality based on easily measurable parameters on flour levels offers a straightforward approach for a targeted optimization of the milling process.ISSN:1935-5130ISSN:1935-514

Chia seed mucilage - A vegan thickener: Isolation, tailoring viscoelasticity and rehydration

Chia seeds and their mucilage gels provide a nutritionally and functionally promising ingredient for thefood and pharmaceutical industry. Application and utilization of the gel remain limited due to the tightlyadhesion of the mucilage to the seeds, which affects the organoleptic properties, control of concen-tration and structuring possibilities. To exploit the full potential of chia mucilage gels as a functional ingre-dient calls for separation and purification of the gel. Herein, the gel was extracted by centrifugation andcharacterized rheologically and microscopically to link the viscoelastic properties to the structural pro-perties. Subsequently, the gel was dried employing three different methods for facilitated storage andprolonged shelf life. The dried gels were readily soluble and its viscoelastic properties were fully regener-ated upon rehydration demonstrating its potential to envisage industrial applications. The viscoelastic chiamucilage demonstrated shear-thinning behavior with complete relaxation upon stress removal. The gel’selasticity was enhanced with increasing mucilage concentration resulting in a highly tunable system. Theextractable and rehydratable functional chia gel is a viable candidate as additive for the development ofproducts requiring specific viscoelastic properties. Addition of the gel enhances the nutritional profilewithout interfering with the organoleptic properties.ISSN:2042-6496ISSN:2042-650