Leg morphology is an important outcome of evolution. A remarkable morphological leg feature is the existence of biarticular muscles that span adjacent joints. Diverse studies from different fields of ...research suggest a less coherent understanding of the muscles' functionality in cyclic, sagittal plane locomotion. We structured this review of biarticular muscle function by reflecting biomechanical template models, human experiments and robotic system designs. Within these approaches, we surveyed the contribution of biarticular muscles to the locomotor subfunctions (
,
and
). While mono- and biarticular muscles do not show physiological differences, the reviewed studies provide evidence for complementary and locomotor subfunction-specific contributions of mono- and biarticular muscles. In
, biarticular muscles coordinate joint movements, improve economy (e.g. by transferring energy) and secure the zig-zag configuration of the leg against joint overextension. These commonly known functions are extended by an explicit role of biarticular muscles in controlling the angular momentum for
and
. Human-like leg arrangement and intrinsic (compliant) properties of biarticular structures improve the controllability and energy efficiency of legged robots and assistive devices. Future interdisciplinary research on biarticular muscles should address their role for sensing and control as well as non-cyclic and/or non-sagittal motions, and non-static moment arms.
The electronic properties of bilayer graphene strongly depend on relative orientation of the two atomic lattices. Whereas Bernal-stacked graphene is most commonly studied, a rotational mismatch ...between layers opens up a whole new field of rich physics, especially at small interlayer twist. Here we report on magnetotransport measurements on twisted graphene bilayers, prepared by folding of single layers. These reveal a strong dependence on the twist angle, which can be estimated by means of sample geometry. At small rotation, superlattices with a wavelength in the order of 10 nm arise and are observed by friction atomic force microscopy. Magnetotransport measurements in this small-angle regime show the formation of satellite Landau fans. These are attributed to additional Dirac singularities in the band structure and discussed with respect to the wide range of interlayer coupling models.
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Several metal supported catalysts were prepared and evaluated for 5-(hydroxymethyl)furfural (5-HMF) hydrogenolysis to 2,5-dimethylfuran (2,5-DMF) which is a renewable potential fuel ...additive. Among the prepared catalysts, 3%Pd/C showed excellent performance in terms of complete conversion of 5-HMF along with the highest selectivity of 99% to 2,5-DMF. Detailed physico-chemical characterisation was done in order to understand structure-activity correlation. Uniformly dispersed Pd nanoparticles on activated carbon provided the adsorption surface to enhance the hydrogenation of 5-HMF. Reaction was well optimised and established by extensive study of different reaction parameters like temperature, pressure, reaction time, stirring effect, substrate loading and metal loading.
Higher shares of intermittent renewable energy in energy systems have raised the issue of the need for different energy storage solutions. The utilization of existing thermal building mass for ...storage is a cost-efficient solution. In order to investigate its potential, a detailed building simulation model was coupled with a linear optimization model of the energy system. Different building archetypes were modelled in detail, and their potential preheating and subsequent heat supply cut-off periods were assessed. Energy system optimization focused on the impact of thermal mass for storage on the energy supply of district heating. Results showed that longer preheating time increased the possible duration of cut-off events. System optimization showed that the thermal mass for storage was used as intra-day storage. Flexible load accounted for 5.5%–7.7% of the total district heating demand. Furthermore, thermal mass for storage enabled more solar thermal heating energy to be effectively utilized in the system. One of the sensitivity analyses showed that the large-scale pit thermal energy storage and thermal mass for storage are complimentary. The cut-off duration potential, which did not compromise thermal comfort, was longer in the newer, better insulated buildings, reaching 6 h among different building archetypes.
•The potential of utilizing building thermal mass for storage was investigated.•A dynamic building model was coupled with a linear optimization energy model.•Houses built after the 1980s had the highest potential for thermal mass utilization.•Thermal mass for storage enabled more solar thermal heating energy effectively utilized.•Large-scale pit thermal energy storage and thermal mass for storage were complimentary.
One pot catalytic transfer hydrogenation (CTH) of furfural to furfuryl alcohol (FAL) by using hydrogen producing alcohols and simultaneous aldolization of carbonyl compounds produced during CTH, with ...furfural was achieved over non-noble metal oxides with bifunctional sites. Basic sites of MgO responsible for abstraction of proton showed complete conversion of furfural to give FAL and C8 monomer in a ratio of 3:1, respectively, the later altered to 1:1 by incorporating Al into MgO. Catalyst stability was established by its four cycles study.
Graphical Abstract
Correction for 'Cascade dehydrative amination of glycerol to oxazoline' by R. Pandya
et al.
,
Catal. Sci. Technol.
, 2018,
8
, 2954-2965, DOI:
10.1039/C8CY00185E
.
Previous research on the effects of workgroup diversity and workgroup functioning and outcomes has produced mixed results. We address these inconsistencies by proposing a model that considers the ...effects of both transformational leadership and workgroup climate on one workgroup outcome believed particularly relevant to diversity: employee creativity. Multilevel analyses of 172 individuals working in 31 teams found that innovation workgroup climate level mediated the relationship between transformational leadership and employee creativity. Furthermore, results indicated that diverse groups had higher innovation climate strength when transformational leadership was high, and that innovation climate level was more strongly related to employee creativity when innovation climate strength was high. Overall, these results suggest that transformational leadership may lessen the negative effects associated with workgroup diversity. Implications for both theory and practice are discussed.
Transformation of biomass into valuable nitrogen-containing compounds is highly desired, yet less explored. Here, we report a simple and efficient method for the direct conversion of bioglycerol to ...oxazoline involving glycerol dehydration to acetol followed by its amination using an aqueous solution of ammonia. For the two-step strategy a non-noble metal Cu–Zr catalyst was developed, giving a glycerol to acetol conversion of 78% followed by amination separately with 95% selectivity to oxazoline. Moreover, we have demonstrated a single-pot oxazoline synthesis using Ru/C as the most stable catalyst to achieve 95% selectivity to oxazoline without any leaching. XPS studies revealed the co-existence of multivalent Ru species in different percentages depending on the nature and structure of the support. These multivalent species (RuO 2 and RuO 3 ) have a synergistic effect on the activation of the carbonyl group, whereas Ru 0 is an active site for ammonia dissociation. NH 3 -TPD and Py-IR spectroscopy results also suggest that the presence of relatively moderate acid sites and a higher Brønsted/Lewis acid ratio in the catalyst promote the selective production of oxazoline. The reaction pathway involves first glycerol dehydration to acetol. In the subsequent step, NH 3 is dissociatively adsorbed on the catalyst surface and the imine thus formed is condensed with a second molecule of acetol to obtain oxazoline. The studied catalyst could be recycled successfully without any significant loss of catalytic activity.
Several supported noble metal catalysts were screened for the hydrogenation of methyl levulinate to γ-valerolactone (GVL). Among these catalysts 5 % Ru/C showed the highest conversion of 95 % of ...methyl levulinate with 91 % selectivity to GVL. A detailed characterization was carried out using TPR, XRD, XPS and BET techniques. XPS studies revealed that higher extent of Ru
0
species in case of carbon supported Ru was responsible for its higher hydrogenation activity as compared to Ru on other supports. Effect of process parameters such as temperature, H
2
pressure, catalyst and substrate concentration and metal loading on methyl LA conversion and selectivity to GVL also has been studied. 5 % Ru/C catalyst was found to be stable up to five reuses.
Graphical Abstract
A sustainable process of catalytic transfer hydrogenation (CTH) of levulinic acid (LA) to γ-valerolactone (GVL) was investigated over Ni on various supports (Al 2 O 3 , ZnO, MMT and SiO 2 ) in the ...presence of isopropanol (IPA) as the H-donor. Among these, the montmorillonite (MMT) supported Ni catalyst showed almost complete LA conversion (>99%) and selectivity (>99%) to GVL within 1 h. XRD and XPS results showed that the concentration of the metallic species significantly enhanced (two to four times) in the recovered sample as compared to the freshly prepared Ni/MMT. This was due to the in situ reduction of Ni 2+ species present on the catalyst surface, through liberated H 2 under the reaction conditions. The strong acid strength of MMT, evidenced by NH 3 -TPD and py-IR, facilitated the esterification of LA as well as cyclization to GVL. The conversion–selectivity pattern was found to decrease in the IPA–water mixture while, it remained unchanged in the IPA–acetone mixture. Our catalyst could be efficiently recycled up to five times with consistent CTH activity and selectivity to GVL. The plausible mechanism of LA to GVL conversion involves the formation of a levulinate ester with IPA that favours its simultaneous hydrogenation and cyclization in a spontaneous manner to give GVL and regenerating IPA for sustainability.
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