Search

Contains fulltext : 247360.pdf (Publisher’s version ) (Open Access) Introduction: Individual social status among peers (i.e., acceptance and rejection) has important implications for students' social and academic development. The present study investigates the role of individual problem behavior and classroom norms in the development of acceptance and rejection among students with intellectual disabilities (ID) in special needs schools. Methods: School staff reported on problem behavior and social status of 1125 students with ID (M = 11.26 years, SD = 3.76; 31% female) in special needs schools at the beginning and end of a school year. Results: More individual problem behavior at the beginning of the year predicted students’ lower acceptance and greater rejection at the end of the year, controlling for earlier problem behavior and other variables. The effect of problem behavior was independent of the prevailing classroom norms. Conclusion: Our findings show that behavioral problems pose a risk for social exclusion of students with ID among their peers in special needs settings. 25 p.

We elucidate the underlying cause of a commonly observed increase in the rate of oxygen release of an oxygen carrier with redox cycling (here specifically for the perovskite Sr0.8Ca0.2FeO3−δ) in chemical looping applications.

SUMMARYTranscription factor IIIC (TFIIIC) recruits RNA polymerase (Pol) III to most of its target genes. Recognition of intragenic A- and B-box motifs in tRNA genes by TFIIIC modules τA and τB is the first critical step for tRNA synthesis but is mechanistically poorly understood. Here, we report cryo-EM structures of the human 624 kDa TFIIIC complex unbound and bound to a tRNA gene. The τB module recognizes the B-box via DNA shape and sequence readout through the assembly of multiple winged-helix domains. TFIIIC220 forms an integral part of both τA and τB connecting the two subcomplexes via a ∼550 amino acid residue flexible linker. Our data provide a structural mechanism by which high-affinity B-box recognition anchors TFIIIC to promoter DNA and permits scanning for low-affinity A-boxes and TFIIIB for Pol III activation.

The oxidative dehydrogenation of propane (ODP) proceeds catalytically on a gas-solid interface (heterogeneous reaction) and/or in the gas phase (homogeneous reaction) via a radical chain process. ODP may therefore combine interrelated contributions from the heterogeneous dehydrogenation and gas-phase reactions, which can be initiated by a catalyst. This study demonstrates that relatively high propene and ethene selectivities (ca. 80 % and 10 %) and propane conversions (viz., 10 % at 500 degrees C) can be achieved with an empty quartz reactor, which is comparable to the performances of state-of-the-art ODP catalysts (boron-based or supported VOx). Optimization of the post-catalytic volume of a h-BN catalyst bed tested at 490 degrees C allows to increase the conversion of propane from 9 % to 15 % at a propene selectivity of 77 %, highlighting this parameter as an important variable for improving catalytic ODP performances., ChemCatChem, 15 (9), ISSN:1867-3880, ISSN:1867-3899

Many countries provide multiple school settings for students with special educational needs (SEN), such as inclusive schooling in mainstream school, special classes, and special schools. However, even though school transfers are especially challenging for students with SEN, research on transfers between different school settings (i.e. placements) for students with SEN is scarce. The current study used administrative census data about students in Switzerland to investigate the frequency, direction, and timing of transfers between school settings attended by students with SEN. Results showed a relatively high percentage of transfers between school settings relative to the estimated number of students with SEN. The direction and timing of transfers varied by setting type. For special classes serving students with moderate SEN and special schools, transfers into these settings greatly outnumbered transfers out of the settings. Transfer peaks were observed at normative transition points (e.g. from kindergarten to primary school).

Development of oxygen carriers for a chemical looping water splitting scheme: the Na-β-Al2O3 phase stabilizes Fe2O3–Fe redox cycles by preventing the formation of inactive FeAl2O4 yielding a high and stable H2 production.

A sustainable hybrid aerogel based on β-lactoglobulin amyloid fibril/UiO-66-NH2 is developed for environmental remediation.

In situ Mo K-edge X-ray absorption spectroscopy reveals different carburization pathways for unsupported and supported MoO3 yielding Mo2C and Mo2C/SiO2. Mo2C/SiO2 features higher resistance to oxidation under dry reforming of methane than Mo2C.

In infected cells, Epstein–Barr virus (EBV) alternates between latency and lytic replication. The viral bZIP transcription factor ZEBRA (Zta, BZLF1) regulates this cycle by binding to two classes of ZEBRA response elements (ZREs): CpG-free motifs resembling the consensus AP-1 site recognized by cellular bZIP proteins and CpG-containing motifs that are selectively bound by ZEBRA upon cytosine methylation. We report structural and mutational analysis of ZEBRA bound to a CpG-methylated ZRE (meZRE) from a viral lytic promoter. ZEBRA recognizes the CpG methylation marks through a ZEBRA-specific serine and a methylcytosine-arginine-guanine triad resembling that found in canonical methyl-CpG binding proteins. ZEBRA preferentially binds the meZRE over the AP-1 site but mutating the ZEBRA-specific serine to alanine inverts this selectivity and abrogates viral replication. Our findings elucidate a DNA methylation-dependent switch in ZEBRA’s transactivation function that enables ZEBRA to bind AP-1 sites and promote viral latency early during infection and subsequently, under appropriate conditions, to trigger EBV lytic replication by binding meZREs.

Alkali metal salt promoters, such as K2CO3 investigated in this work, are known to affect the cyclic performance of CaO-based sorbents – sometimes positively, sometimes negatively. Thus far, the influence of K2CO3 (and other salt-based promoters) is poorly understood, and detailed investigations on the interaction of K2CO3 with CaO are missing. We find that low amounts of K2CO3 in the sorbents improve the cyclic performance of CaO significantly (up to a factor of three), both under mild and harsh CO2 release conditions, while large amounts of K2CO3 (>1 mol.%) reduce the positive effect on the CO2 uptake performance. Aided by in-situ X-ray diffraction measurements, we observe that the gas environment has an important influence on the stability of K-containing phases in the sorbent. At typical carbonation conditions (650 °C, 15 vol% CO2/N2), CaO and K2CO3 readily form K-Ca double carbonates (K2Ca(CO3)2, which reacts further to form K2Ca2(CO3)3). When the calcination reaction is carried out in pure N2, the K-Ca double carbonates decompose above ∼730 °C, forming K2CO3 that becomes partially volatile near its melting point of ∼900 °C, and leads to a reduction of the K content in the samples with cycling. When the calcination reaction is carried out in a CO2-rich environment, the cyclic loss of K2CO3 is reduced substantially, but the sintering of the sorbent is increased. There are indications that very low quantities of K are incorporated into the CaO structure, and the formation of K-Ca double carbonates appears to influence the structural evolution of the CaCO3 phase formed during carbonation. With very low amounts of K2CO3 present in the sorbent, we observe an increase in pore volume for pore diameters between 20 and 80 nm, which ultimately may explain the improved CO2 uptake performance compared to the CaO sorbent without K2CO3. ISSN:0300-9467 ISSN:1385-8947 ISSN:1873-3212 ISSN:0923-0467

MXenes, due to their tailorable chemistry and favourable physical properties, have great promise in electrocatalytic energy conversion reactions. To exploit fully their enormous potential, further advances specific to electrocatalysis revolving around their performance, stability, compositional discovery and synthesis are required. The most recent advances in these aspects are discussed in detail: surface functional and stoichiometric modifications which can improve performance, Pourbaix stability related to their electrocatalytic operating conditions, density functional theory and advances in machine learning for their discovery, and prospects in large scale synthesis and solution processing techniques to produce membrane electrode assemblies and integrated electrodes. This Review provides a perspective that is complemented by new density functional theory calculations which show how these recent advances in MXene material design are paving the way for effective electrocatalysts required for the transition to integrated renewable energy systems., Angewandte Chemie. International Edition, 62 (4), ISSN:1433-7851, ISSN:1521-3773, ISSN:0570-0833

The metabolism of malignant cells differs significantly from that of healthy cells and thus, it is possible to perform metabolic imaging to reveal not only the exact location of a tumor, but also intratumoral areas of high metabolic activity. Herein, we demonstrate the feasibility of metabolic tumor imaging using signal-enhanced 1-13C-pyruvate-d3, which is rapidly enhanced via para-hydrogen, and thus, the signal is amplified by several orders of magnitudes in less than a minute. Using as a model, human melanoma xenografts injected with signal-enhanced 1-13C-pyruvate-d3, we show that the conversion of pyruvate into lactate can be monitored along with its kinetics, which could pave the way for rapidly detecting and monitoring changes in tumor metabolism.

Electrocatalytic transformations of oxygen, i.e., the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), are key processes in renewable energy conversion, defining to a large extent, the efficiency of numerous energy conversion technologies, such as fuel cells, metal-air batteries or water electrolyzers. However, the development of highly effective, stable and inexpensive materials for such conversion processes is a bottleneck. Hence, establishing generic catalyst design principles by identifying structural features of catalysts that influence their performance would constitute a major step towards the rational engineering of advanced electrocatalysts. In this study, by investigating a series of metal-substituted manganese oxide (spinel), Mn3O4:M (M = Sr, Ca, Mg, Zn, Cu), nanoparticles as a model system, we demonstrate experimentally and rationalized the dependence of the activity of Mn3O4:M for ORR and the oxygen binding strength in Mn3O4:M oxides on the properties of the M substituent, viz. the enthalpy of formation of the binary MO oxide and the Lewis acidity of the M2+ substituent. Incorporation of elements M that have a low enthalpy of formation of MO (i.e., highly exothermic oxides featuring relatively strong M‒O bonding) enhances the oxygen binding strength in Mn3O4:M, which increases its activity in ORR due to the established correlation between ORR activity and the binding energy of *O/*OH/*OOH species on the catalyst surface. Our work provides a new perspective on the design of new compositions for oxygen electrocatalysis relying on the substitution by redox-inactive elements affecting the binding energy of oxygen to the surface of the complex metal oxide catalysts (ORR/OER activity descriptor). We speculate that this concept is general and transferrable to a broad selection of materials and processes involving oxygen adsorption and redox, beyond electrocatalysis.

Cryo-electron tomography is a powerful label-free tool for visualizing biomolecules in their native cellular context at molecular resolution. However, the precise localisation of biomolecules of interest in the tomographic volumes is challenging. Here, we present a tagging strategy for intracellular protein localisation based on genetically encoded multimeric particles (GEMs). We show the applicability of drug-controlled GEM labelling of endogenous proteins in cryo-electron tomography and cryo-correlative fluorescence imaging in human cells.

Nanoscale, 14 (45), ISSN:2040-3364, ISSN:2040-3372

Water scarcity is a worldwide concern with various implications, such as widespread pollution with heavy metals and organic pollutants, resulting in global threats to the environment and human health, and calling for innovative remediation strategies. We show here that the capability of protein-based carbon aerogels for removing contaminants from water can be greatly improved by transforming proteins into amyloids before their hydrothermal carbonization. Amyloid fibrils were prepared from whey protein isolate, a by-product of the dairy industry, and upon addition to different carbohydrates, the ensued mixtures were used for carbon aerogels production. Furthermore, the generality of the approach for producing carbon aerogels was demonstrated using vegetable amyloids from soy protein. The carbon aerogels are able to adsorb Au(III), Pt(II), Fe(III), and Ag(I) with excellent removal efficiencies. Moreover, the amyloid whey lactose carbon aerogel has an adsorption capacity of 650.08 mg/g for Au(III), significantly higher than that of a carbon aerogel derived from monomer whey lactose. The reusability of the carbon aerogel is also proven over three continuous adsorption/regeneration cycles, with a stable performance in terms of removal efficiency indicating good long-term use. Taken together, the results demonstrate amyloid carbon aerogels’ capability as an efficient, sustainable, and inexpensive solution for water purification., Chemical Engineering Journal, 449, ISSN:0300-9467, ISSN:1385-8947, ISSN:1873-3212, ISSN:0923-0467

Gallia–alumina (Ga,Al)2O3(x : y) spinel-type solid solution nanoparticle catalysts for propane dehydrogenation (PDH) were prepared with four nominal Ga : Al atomic ratios (1 : 6, 1 : 3, 3 : 1, 1 : 0) using a colloidal synthesis approach. The structure, coordination environment and distribution of Ga and Al sites in these materials were investigated by X-ray diffraction, X-ray absorption spectroscopy (Ga K-edge) as well as 27Al and 71Ga solid state nuclear magnetic resonance. The surface acidity (Lewis or Brønsted) was probed using infrared spectroscopy with pyridine and 2,6-dimethylpyridine probe molecules, complemented by element-specific insights (Ga or Al) from dynamic nuclear polarization surface enhanced cross-polarization magic angle spinning 15N{27Al} and 15N{71Ga} J coupling mediated heteronuclear multiple quantum correlation NMR experiments using 15N-labelled pyridine as a probe molecule. The latter approach provides unique insights into the nature and relative strength of the surface acid sites as it allows to distinguish contributions from Al and Ga sites to the overall surface acidity of mixed (Ga,Al)2O3 oxides. Notably, we demonstrate that (Ga,Al)2O3 catalysts with a high Al content show a greater relative abundance of four-coordinated Ga sites and a greater relative fraction of weak/medium Ga-based surface Lewis acid sites, which correlates with superior propene selectivity, Ga-based activity, and stability in PDH (due to lower coking). In contrast, (Ga,Al)2O3 catalysts with a lower Al content feature a higher fraction of six-coordinated Ga sites, as well as more abundant Ga-based strong surface Lewis acid sites, which deactivate through coking. Overall, the results show that the relative abundance and strength of Ga-based surface Lewis acid sites can be tuned by optimizing the bulk Ga : Al atomic ratio, thus providing an effective measure for a rational control of the catalyst performance., Coordination geometry and Lewis acidity of Ga and Al (bulk and surface) sites in mixed oxide gallia–alumina nanoparticles is correlated with the performance in propane dehydrogenation.

Most compilers have a single core intermediate representation (IR) (e.g., LLVM) sometimes complemented with vaguely defined IR-like data structures. This IR is commonly low-level and close to machine instructions. As a result, optimizations relying on domain-specific information are either not possible or require complex analysis to recover the missing information. In contrast, multi-level rewriting instantiates a hierarchy of dialects (IRs), lowers programs level-by-level, and performs code transformations at the most suitable level. We demonstrate the effectiveness of this approach for the weather and climate domain. In particular, we develop a prototype compiler and design stencil- and GPU-specific dialects based on a set of newly introduced design principles. We find that two domain-specific optimizations (500 lines of code) realized on top of LLVM's extensible MLIR compiler infrastructure suffice to outperform state-of-the-art solutions. In essence, multilevel rewriting promises to herald the age of specialized compilers composed from domain- and target-specific dialects implemented on top of a shared infrastructure. ISSN:1544-3566 ISSN:1544-3973

Particle image velocimetry has been applied to measure particle velocities on the free surface of a bed of particles within a rotating cylinder during avalanching. The particle velocities were used to examine the validity of existing avalanche models and to propose an alternative model. The movement of particles depends on their location on the surface of the bed: Particles located near the center of the bed travel the farthest, while the distance traveled decreases at an increasing rate for particles located farther from the center. The start of an avalanche can be determined to a single initiation point that can be located on the bottom half of the bed; the avalanche quickly propagates through the entire free surface with 90% of the surface in motion within 257 ms (approximately 20% of the total duration of an avalanche). The experimental insight is used to formulate a geometric model, in which three equal-sized sections flow down the bed surface during an avalanch. The predictions of the model are validated by experimental mixing measurements. ISSN:1539-3755 ISSN:1063-651X ISSN:1095-3787 ISSN:1550-2376

The metabolism of malignant cells differs significantly from that of healthy cells and thus, it is possible to perform metabolic imaging to reveal not only the exact location of a tumor, but also intratumoral areas of high metabolic activity. Herein, we demonstrate the feasibility of metabolic tumor imaging using signal-enhanced 1

ZusammenfassungNormen definieren Kriterien für die soziale Akzeptanz und Ablehnung von Kindern in einer Klasse. Welche Normen Grundschulkinder jedoch als relevant für die soziale Akzeptanz bzw. Ablehnung wahrnehmen ist unklar. Dieses Desiderat wurde in einer Interviewstudie (N = 38) und darauf aufbauend in einer Fragebogenstudie (N = 647) adressiert. Die Befunde machen auf die Bedeutung des Sozialverhaltens als wahrgenommene Gruppennorm für die Akzeptanz und Ablehnung aufmerksam, die sich über die Klassenstufen hinweg als stabil erwies. Jahrgangsspezifische Unterschiede fanden sich hingegen für die Bedeutung formeller Normen (z. B. mit Bezug zur Schulleistung), die von Kindern in den höheren Klassenstufen als weniger relevant für den sozialen Status wahrgenommen wurden, als von jenen in den unteren Klassenstufen.

Vibration of gas-solid fluidized beds is often used to enable fluidization of cohesive particles; however, it has also been shown to reduce the minimum fluidization velocity (Umf). Here, we show via experiments that vibration can reduce both Umf and the minimum bubbling velocity (Umb) in Geldart Group B and D particles. We observe that Umf is reduced more than Umb, thereby creating a densely packed, bubble-free fluidization state when the superficial gas velocity is in between Umf and Umb. Umf and Umb decrease with increasing vibration frequency and amplitude and the results for Umf and Umb across a variety of vibration conditions could be plotted along a single curve when plotted versus vibration strength, i.e. the ratio of peak vibration acceleration to gravitational acceleration. Changes in Umf and Umb due to vibration are not affected significantly by changing particle density, but in a non-monotonic way by changing particle diameter.

MgO-based CO

This work explores how H-2 pretreatment at 550 degrees C induces structural transformation of two gallia-based propane dehydrogenation (PDH) catalysts, viz. nanocrystalline gamma/beta-Ga2O3 and amorphous Ga2O3 (GaOx) supported on silica (gamma-Ga2O3/SiO2 and Ga/SiO2, respectively) and how it affects their activity, propene selectivity and stability with time on stream (TOS). Ga/SiO2-H-2 shows poor activity and propene selectivity, no coking and no deactivation with TOS, similar to Ga/SiO2. In contrast, the high initial activity and propene selectivity of gamma-Ga2O3/SiO2-H-2 decline with TOS but to a lesser extent than in calcined gamma-Ga2O3/SiO2. In addition, gamma-Ga2O3/SiO2-H-2 cokes less than gamma-Ga2O3/SiO2. Ga K-edge X-ray absorption spectroscopy suggests an increased disorder of the nanocrystalline gamma/beta-Ga2O3 phases in gamma-Ga2O3/SiO2-H-2 and the emergence of additional tetrahedral Ga sites (Ga-IV). Such Ga-IV sites are strong Lewis acid sites (LAS) according to studies using adsorbed pyridine and CO probe molecules, i.e., the abundance of strong LAS is higher in gamma-Ga2O3/SiO2-H-2 compared to gamma-Ga2O3/SiO2 but lower than in Ga/SiO2 and Ga/SiO2-H-2. Dissociation of H-2 on the Ga-O linkages in gamma-Ga2O3/SiO2-H-2 yields high-frequency Ga-H bands that are observed in Ga/SiO2 and Ga/SiO2-H-2 but not detected in gamma-Ga2O3/SiO2. We attribute the increased amount of Ga-IV sites in gamma-Ga2O3/SiO2-H-2 mostly to an increased disorder in gamma/beta-Ga2O3. X-ray photoelectron spectroscopy detects the formation of Ga+ and Ga-0 species in both Ga/SiO2-H-2 and gamma-Ga2O3/SiO2-H-2. Therefore, it is likely that a minor amount of Ga-IV sites also forms through the interaction of Ga+ (such as Ga2O) and/or Ga-0 with silanol groups of SiO2., Catalysis Science & Technology, 12 (12), ISSN:2044-4753, ISSN:2044-4761

Objective To develop a phantom system which can be integrated with an automated injection system, eliminating the experimental variability that arises with manual injection; for the purposes of pulse sequence testing and metric derivation in hyperpolarised 13C-MR. Methods The custom dynamic phantom was machined from Ultem and filled with a nicotinamide adenine dinucleotide and lactate dehydrogenase mixture dissolved in phosphate buffered saline. Hyperpolarised [1-13C]-pyruvate was then injected into the phantom (n = 8) via an automated syringe pump and the conversion of pyruvate to lactate monitored through a 13C imaging sequence. Results The phantom showed low coefficient of variation for the lactate to pyruvate peak signal heights (11.6%) and dynamic area-under curve ratios (11.0%). The variance for the lactate dehydrogenase enzyme rate constant (kP) was also seen to be low at 15.6%. Conclusion The dynamic phantom demonstrates high reproducibility for quantification of 13C-hyperpolarised MR-derived metrics. Establishing such a phantom is needed to facilitate development of hyperpolarsed 13C-MR pulse sequenced; and moreover, to enable multisite hyperpolarised 13C-MR clinical trials where assessment of metric variability across sites is critical. Advances in knowledge The dynamic phantom developed during the course of this study will be a useful tool in testing new pulse sequences and standardisation in future hyperpolarised work.

This paper focuses on the experimental demonstration of a three-stage GST (gas switching technology) process (fuel, steam/CO2, and air stages) for syngas production from methane in the fuel stage and H2/CO production in the steam/CO2 stage using a lanthanum-based oxygen carrier (La0.85Sr0.15Fe0.95Al0.05O3). Experiments were performed at temperatures between 750–950 °C and pressures up to 5 bar. The results show that the oxygen carrier exhibits high selectivity to oxidizing methane to syngas at the fuel stage with improved process performance with increasing temperature although carbon deposition could not be avoided. Co-feeding CO2 with CH4 at the fuel stage reduced carbon deposition significantly, thus reducing the syngas H2/CO molar ratio from 3.75 to 1 (at CO2/CH4 ratio of 1 at 950 °C and 1 bar). The reduced carbon deposition has maximized the purity of the H2 produced in the consecutive steam stage thus increasing the process attractiveness for the combined production of syngas and pure hydrogen. Interestingly, the cofeeding of CO2 with CH4 at the fuel stage showed a stable syngas production over 12 hours continuously and maintained the H2/CO ratio at almost unity, suggesting that the oxygen carrier was exposed to simultaneous partial oxidation of CH4 with the lattice oxygen which was restored instantly by the incoming CO2. Furthermore, the addition of steam to the fuel stage could tune up the H2/CO ratio beyond 3 without carbon deposition at H2O/CH4 ratio of 1 at 950 °C and 1 bar; making the syngas from gas switching partial oxidation suitable for different downstream processes, for example, gas-to-liquid processes. The process was also demonstrated at higher pressures with over 70% fuel conversion achieved at 5 bar and 950 °C., Industrial & Engineering Chemistry Research, 60 (9), ISSN:1520-5045, ISSN:0888-5885

α-Ga2O3, β-Ga2O3, and γ-Ga2O3 as well as the silica-supported catalysts γ-Ga2O3/SiO2, β-Ga2O3/SiO2, and Ga(NO3)3-derived Ga/SiO2 were prepared, characterized, and evaluated for propane dehydrogenat...