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Boron nitride nanotubes (BNNTs) are an emerging class of molecular container offering new functionalities and possibilities for studying molecules at the nanoscale. Herein, BNNTs are demonstrated as highly effective nanocontainers for polyoxometalate (POM) molecules. The encapsulation of POMs within BNNTs occurs spontaneously at room temperature from an aqueous solution, leading to the self-assembly of a POM@BNNT host-guest system. Analysis of the interactions between the host-nanotube and guest-molecule indicate that Lewis acid-base interactions between W═O groups of the POM (base) and B-atoms of the BNNT lattice (acid) likely play a major role in driving POM encapsulation, with photoactivated electron transfer from BNNTs to POMs in solution also contributing to the process. The transparent nature of the BNNT nanocontainer allows extensive investigation of the guest-molecules by photoluminescence, Raman, UV-vis absorption, and EPR spectroscopies. These studies revealed considerable energy and electron transfer processes between BNNTs and POMs, likely mediated via defect energy states of the BNNTs and resulting in the quenching of BNNT photoluminescence at room temperature, the emergence of new photoluminescence emissions at cryogenic temperatures (100 K), a photochromic response, and paramagnetic signals from guest-POMs. These phenomena offer a fresh perspective on host-guest interactions at the nanoscale and open pathways for harvesting the functional properties of these hybrid systems.

The paradigmatic shift from traditional flood defense toward integrated flood risk management has widened the sectors and policies affected and has spurred a growing interest of scholars to understand cross-sectoral flood policy integration. In this paper we argue that the cross-sectoral goal relationship—ranging from complementary to conflictual policy goals—is a useful conceptual framework to understand (1) the policy integration challenge at hands and (2) in particular the unfolding policy integration from a processual perspective. For our empirical analysis we identify three policy subsystems that are highly important for sectoral interplay in flood risk management: agriculture, hydropower generation, and spatial planning. Using Austria as a case study we illustrate the goal relationships and sectoral policy integration challenges in each of these fields of interaction. Based on 45 expert interviews in the selected policy sectors we provide useful insights into the current processes of flood policy integration. The empirical findings from our case studies show that sectoral goal relationships and the nature of the policy integration challenge drive flood policy integration. More pronounced land use conflicts are more strongly reflected in different actor interests, policy frames, policy goals, and the choice of policy instruments. Sectoral goal relationships are an important factor to explain the unfolding policy integration process. Complementary policy goals result in rather informal, harmonious integrative negotiations on strengthening synergies by using soft policy instruments. On the contrary, conflictual policy goals lead to more formal negotiations among the affected sectors relying on hard, regulative instruments.

Density functional theory is the workhorse of materials simulations. Unfortunately, the quality of results often varies depending on the specific choice of the exchange-correlation functional, and this significantly limits the predictive power of this approach. Coupled cluster theory, including single, double and perturbative triple particle-hole excitation operators, is widely considered as the `gold standard` of quantum chemistry as it can achieve chemical accuracy for non-strongly correlated applications. Because of the high computational cost, the application of coupled cluster theory in materials simulations is rare, and this is particularly true if finite-temperature properties are of interest for which molecular dynamics simulations have to be performed. By combining recent progress in machine learning models with low data requirements for energy surfaces and in the implementation of coupled cluster theory for periodic materials, we show that chemically accurate simulations of materials are practical and could soon become significantly widespread. As an example of this numerical approach, we consider the calculation of the enthalpy of adsorption of CO2 in a porous material.

Background and aims: High lipoprotein(a) [Lp(a)] concentrations are associated with increased coronary artery disease (CAD) risk. Lp(a) is regulated mainly genetically by the LPA gene but involved genetic variants have not been fully elucidated. Improved understanding of the entanglements of genetic Lp(a) regulation may enhance genetic prediction of Lp(a) and CAD risk. We investigated an interaction between the well-known LPA missense SNP rs41272110 (known as Thr3888Pro) and the frequent LPA splicing mutation KIV-2 4925G>A. Methods: Effects on Lp(a) concentrations were investigated by multiple quantile regression in the German Chronic Kidney Disease (GCKD) study, KORA-F3 and KORA-F4 (ntotal = 10,405) as well as in the UK Biobank (UKB) 200k exome dataset (n = 173,878). The impact of the interaction on CAD risk was assessed by survival analysis in UKB. Results: We observed a significant SNP-SNP interaction in all studies (p = 1.26e-05 to 3.03e-04). In quantile regression analysis, rs41272110 as a predictor shows no impact on Lp(a) (β = −0.06 [-0.79; 0.68], p = 0.879), but in a joint model including both SNPs as predictors, rs41272110 is associated with markedly higher Lp(a) (β = +9.40 mg/dL [6.45; 12.34], p = 4.07e-10). Similarly, rs41272110 shows no effect on CAD in UKB (HR = 1.01 [0.97; 1.04], p = 0.731), while rs41272110 carriers not carrying 4925G>A show an increased CAD risk (HR = 1.10 [1.04; 1.16], p = 6.9e-04). This group corresponds to 4% of the population. Adjustment for apolipoprotein(a) isoforms further modified the effect estimates markedly. Conclusions: This work emphasizes the complexity of the genetic regulation of Lp(a) and the importance to account for genetic subgroups in Lp(a) association studies and when interpreting genetic cardiovascular risk profiles.

We present a study of the self-interstitial point defect formation energies in silicon using a range of quantum chemical theories including the coupled cluster (CC) method within a periodic supercell approach. We study the formation energies of the X, T, H and C3V self-interstitials and the vacancy V. Our results are compared to findings obtained using different ab initio methods published in the literature and partly to experimental data. In order to achieve computational results that are converged with respect to system size and basis set, we employ the recently proposed finite size error corrections and basis set incompleteness error corrections. Our CCSD(T) calculations yield an order of stability of the X, H and T self-interstitials, which agrees both with quantum Monte Carlo results and with predictions obtained using the random-phase approximation as well as using screened hybrid functionals. Compared to quantum Monte Carlo results with backflow corrections, the CCSD(T) formation energies of X and H are only slightly larger by about 100 meV. However, in the case of the T self-interstitial, we find significant disagreement with all other theoretical predictions. Compared to quantum Monte Carlo calculations, CCSD(T) overestimates the formation energy of the T self-interstitial by 1.2 eV. Although this can partly be attributed to strong correlation effects, more accurate electronic structure theories are needed to understand these findings.

Computationally efficient and accurate quantum mechanical approximations to solve the many-electron Schrödinger equation are crucial for computational materials science. Methods such as coupled cluster theory show potential for widespread adoption if computational cost bottlenecks can be removed. For example, extremely dense k-point grids are required to model long-range electronic correlation effects, particularly for metals. Although these grids can be made more effective by averaging calculations over an offset (or twist angle), the resultant cost in time for coupled cluster theory is prohibitive. We show here that a single special twist angle can be found using the transition structure factor, which provides the same benefit as twist averaging with one or two orders of magnitude reduction in computational time. We demonstrate that this not only works for metal systems but also is applicable to a broader range of materials, including insulators and semiconductors.

Patterns formed in monolayer graphene (Gr) and hexagonal boron nitride (h-BN) upon ion irradiation in the temperature range from 950 to 1530 K using 500 eV He+ at normal or 500 eV Xe+ at grazing incidence and fluences up to 2.5×1019 ions/m2 are investigated by room-temperature scanning tunneling microscopy. Subnanometer pores are created and are distributed with the periodicity of the moiré which results from the interaction of the monolayers with their Ir(111) substrate. The moiŕe contains trapping sites for vacancies within each moiré unit cell as is investigated in detail for the case of h-BN with the help of ab initio calculations. The density of the nanopores is extremely high in the order of 1017 pores/m2 and their size distribution is limited by the size of the vacancy traps causing excess vacancies to be expelled from the array and to anneal at preexistent defects. Successful delamination of a perforated Gr monolayer from the substrate is demonstrated and makes the material accessible for membrane research.

A magnetic field modifies optical properties and provides valley splitting in a molybdenum disulfide (MoS

Background: Lp(a) (lipoprotein [a]) is a highly atherogenic lipoprotein strongly associated with coronary artery disease (CAD). Lp(a) concentrations are chiefly determined genetically. Investigation of large pedigrees with extreme Lp(a) using modern whole-genome approaches may unravel the genetic determinants underpinning this pathological phenotype. Methods: A large family characterized by high Lp(a) and increased CAD incidence was recruited by cascade screening. Plasma lipids, lipoproteins, and apolipoproteins concentrations, as well as the size of apo(a) isoforms, were determined enzymatically by high-resolution mass spectrometry and Western blot, respectively. Whole-exome sequencing was performed to search for rare defects in modifier genes. Genetic risk scores (GRS) for Lp(a) and CAD were calculated and their discriminative power was assessed. Results: Seventeen individuals displayed extreme Lp(a) levels including 6 with CAD. Whole-exome sequencing showed no hint for genetic defects outside the LPA locus. The extreme Lp(a) phenotype segregated with the presence of a short apo(a) isoform containing 21 Kringle IV domains. This allele was characterized by the presence of three rare strongly Lp(a) increasing single nucleotide polymorphisms and a significantly increased load of oxidized phospholipids per Lp(a) particle. An Lp(a) GRS consisting of 48 single nucleotide polymorphisms that represent 2001 genome-wide significant LPA single nucleotide polymorphisms, efficiently captured the hyper-Lp(a) phenotype and discriminated affected and nonaffected individuals with great accuracy. The genome-wide GRS for CAD, encompassing 6.6 million single nucleotide polymorphisms, was very high for most family members (>97.5 percentile of the reference population), but this observation was no longer valid when the contribution of the LPA locus was omitted. Conclusions: High-Lp(a) phenotypes can be successfully captured using the Lp(a) GRS even among closely related family members. In hyper-Lp(a) individuals, LPA can be a major locus driving a very high CAD GRS. This underpins the large contribution of the LPA locus to the cardiovascular genetic risk in families.

Das Ziel dieser Arbeit ist, aufzuzeigen, ob die entwickelten Themenboxen einen Beitrag dazu leisten, dass Größen im Mathematikunterricht nachhaltig geübt werden können. Dazu wurde folgende Forschungsfrage gestellt: Wie gut sind Themenboxen für nachhaltiges Üben von Größen im Mathematikunterricht geeignet? Um die Forschungsfrage zu beantworten, wurde eine Erprobung im Unterricht durchgeführt. Dazu wurden zwei Lernstandserhebungen durchgeführt in jeweils einer Treatmentklasse und einer Kontrollklasse einer 5. und 8. Schulstufe, eine vor dem Einsatz der Themenboxen und eine nach dem Einsatz. Um Auskunft darüber zu bekommen, wie ihnen die Arbeit mit den Boxen gefallen hat, wurde von den Lernenden der Treatmentklasse zusätzlich ein Fragebogen ausgefüllt. Der Vergleich der Lernstandserhebungen hat gezeigt, dass die Themenboxen einen Beitrag dazu leisten, dass sich die Leistungen der Schülerinnen und Schüler verbessern. Die Auswertung des Fragebogens hat gezeigt, dass den Lernenden vor allem das regelmäßige Arbeiten an einem Thema, die selbstständige Auswahl der Aufgaben und die Abwechslung zum herkömmlichen Unterricht gut gefallen. Viele Lernenden sind bereits der Meinung, dass sie die Inhalte nun besser können als vorher und sie sich diese nun langfristiger merken können. Auf dieser Grundlage ist es empfehlenswert, Themenboxen gelegentlich im Unterricht einzusetzen, um Themen nachhaltig zu sichern. eingereicht von Carola Grüneis, BEd Angefertigt an der Privaten Pädagogischen Hochschule der Diözese Linz Masterarbeit Universität Linz 2022 Arbeit auf den öffentlichen PCs in den Bibliotheken der JKU+Medizin abrufbar

We present a basis set correction scheme for the coupled-cluster singles and doubles (CCSD) method. The scheme is based on employing frozen natural orbitals (FNOs) and diagrammatically decomposed contributions to the electronic correlation energy, which dominate the basis set incompleteness error (BSIE). As recently discussed in the work of Irmler et al. [Phys. Rev. Lett. 123, 156401 (2019)], the BSIE of the CCSD correlation energy is dominated by the second-order Moller–Plesset (MP2) perturbation energy and the particle–particle ladder term. Here, we derive a simple approximation to the BSIE of the particle–particle ladder term that effectively corresponds to a rescaled pair-specific MP2 BSIE, where the scaling factor depends on the spatially averaged correlation hole depth of the coupled-cluster and first-order pair wavefunctions. The evaluation of the derived expressions is simple to implement in any existing code. We demonstrate the effectiveness of the method for the uniform electron gas. Furthermore, we apply the method to coupled-cluster theory calculations of atoms and molecules using FNOs. Employing the proposed correction and an increasing number of FNOs per occupied orbital, we demonstrate for a test set that rapidly convergent closed and open-shell reaction energies, atomization energies, electron affinities, and ionization potentials can be obtained. Moreover, we show that a similarly excellent trade-off between required virtual orbital basis set size and remaining BSIEs can be achieved for the perturbative triples contribution to the CCSD(T) energy employing FNOs and the (T*) approximation.

The electronic defect states resulting from doping $^{229}\mathrm{Th}$ in ${\mathrm{CaF}}_{2}$ offer a unique opportunity to excite the nuclear isomeric state $^{229\mathrm{m}}\mathrm{Th}$ at approximately 8 eV via electronic bridge mechanisms. We consider bridge schemes involving stimulated emission and absorption using an optical laser. The role of different multipole contributions, both for the emitted or absorbed photon and nuclear transition, to the total bridge rates are investigated theoretically. We show that the electric dipole component is dominant for the electronic bridge photon. In contradistinction, the electric quadrupole channel of the $^{229}\mathrm{Th}$ isomeric transition plays the dominant role for the bridge processes presented. The driven bridge rates are discussed in the context of background signals in the crystal environment and of implementation methods. We show that inverse electronic bridge processes quenching the isomeric state population can improve the performance of a solid-state nuclear clock based on $^{229\mathrm{m}}\mathrm{Th}$.

Lateral heterojunctions of atomically precise graphene nanoribbons (GNRs) hold promise for applications in nanotechnology, yet their charge transport and most of the spectroscopic properties have not been investigated. Here, we synthesize a monolayer of multiple aligned heterojunctions consisting of quasi-metallic and wide-bandgap GNRs, and report characterization by scanning tunneling microscopy, angle-resolved photoemission, Raman spectroscopy, and charge transport. Comprehensive transport measurements as a function of bias and gate voltages, channel length, and temperature reveal that charge transport is dictated by tunneling through the potential barriers formed by wide-bandgap GNR segments. The current-voltage characteristics are in agreement with calculations of tunneling conductance through asymmetric barriers. We fabricate a GNR heterojunctions based sensor and demonstrate greatly improved sensitivity to adsorbates compared to graphene based sensors. This is achieved via modulation of the GNR heterojunction tunneling barriers by adsorbates., Here, the authors characterize the spectroscopic and transport properties of heterojunctions composed of quasi-metallic and semiconducting graphene nanoribbons (GNRs) with different widths, showing a predominant quantum tunnelling mechanism. The GNR heterojunctions can also be used to realize adsorbate sensors with high sensitivity.

Background: Lipoprotein(a) (Lp(a)) concentrations are a major independent risk factor for coronary artery disease (CAD) and are mainly determined by variation in LPA. Up to 70% of the LPA coding sequence is located in the hypervariable kringle IV type 2 (KIV-2) region. It is hardly accessible by conventional technologies, but may contain functional variants. Objectives: This study sought to investigate the new, very frequent splicing variant KIV-2 4733G>A on Lp(a) and CAD. Methods: We genotyped 4733G>A in the GCKD (German Chronic Kidney Disease) study (n = 4,673) by allele-specific polymerase chain reaction, performed minigene assays, identified proxy single nucleotide polymorphisms and used them to characterize its effect on CAD by survival analysis in UK Biobank (n = 440,234). Frequencies in ethnic groups were assessed in the 1000 Genomes Project. Results: The 4733G>A variant (38.2% carrier frequency) was found in most isoform sizes. It reduces allelic expression without abolishing protein production, lowers Lp(a) by 13.6 mg/dL (95% CI: 12.5-14.7; P < 0.0001) and is the strongest variance-explaining factor after the smaller isoform. Splicing of minigenes was modified. Compound heterozygosity (4.6% of the population) for 4733G>A and 4925G>A, another KIV-2 splicing mutation, reduces Lp(a) by 31.8 mg/dL and most importantly narrows the interquartile range by 9-fold (from 42.1 to 4.6 mg/dL) when compared to the wild type. In UK Biobank 4733G>A alone and compound heterozygosity with 4925G>A reduced HR for CAD by 9% (95% CI: 7%-11%) and 12% (95% CI: 7%-16%) (both P < 0.001). Frequencies in ethnicities differ notably. Conclusions: Functional variants in the previously inaccessible LPA KIV-2 region cooperate in determining Lp(a) variance and CAD risk. Even a moderate but lifelong genetic Lp(a) reduction translates to a noticeable CAD risk reduction.

Single quantum dots and other materials exhibit irregular switching between on and off states; these on-off states follow power-law statistics giving rise to 1/f noise. We transfer this phenomenon (also referred to as on-off intermittency) to the generation and recombination (g-r) process in semiconductor materials. In addition to g-r noise we obtain 1/f noise that can be provided in the form of the Hooge relation. The predicted Hooge coefficient depends on the parameters of the g-r noise and on the parameters of the intermittency. Due to the power-law distribution of the on-times, the coefficient for intermittency shows a smooth dependence on time t. We also suggest an alternative form of the 1/f noise formula by Hooge relating the 1/f noise to the number of centers (such as donor or trap atoms) rather than to the number of charge carriers as defined by Hooge., Comment: 17 pages, 9 figures

Coupled cluster (CC) theory is often considered the gold standard of quantum-chemistry. For solids, however, the available software is scarce. We present CC-aims, which can interface ab initio codes with localized atomic orbitals and the CC for solids (CC4S) code by the group of A. Gr\"uneis. CC4S features a continuously growing selection of wave function-based methods including perturbation and CC theory. The CC-aims interface was developed for the FHI-aims code (https://fhi-aims.org) but is implemented such that other codes may use it as a starting point for corresponding interfaces. As CC4S offers treatment of both molecular and periodic systems, the CC-aims interface is a valuable tool, where DFT is either too inaccurate or too unreliable, in theoretical chemistry and materials science alike., Comment: Currently reviewed for publication in the JOSS journal (review process: https://github.com/openjournals/joss-reviews/issues/4040 ). The conciseness of the paper is due to the required word count of less than 1000 words by the journal (see https://joss.readthedocs.io/en/latest/submitting.html#what-should-my-paper-contain ). This manuscript is complete and introduces a new piece of software

Impacts of climate change have become more and more evident and can be observed in ecosystems, societies and economies worldwide. Mountain agriculture is especially vulnerable to climate change, and adaptation seems crucial. Thus, certain adaptation activities, such as installing irrigation technology, switching to drought-resistant crop varieties or shifting planting dates, can already be observed. Despite these efforts, the barriers for climate change adaptation are still manifold and lead to adaptation gaps. One problem is that many approaches ignore non-climatic drivers, such as economic conditions or cultural aspects, which have a strong influence on farmers´ decisions. In the literature, the focus is mostly on planned, “top-down” induced adaptations, where climate change is considered the most important driver. Within this study, we focus on local, “bottom-up” adaptation actions in Tyrolean mountain agriculture that may be triggered by climatic as well as by non-climatic drivers. We identify 27 adaptation practices and cluster them into six types of climate change adaptation: ´Resilience-raising products and production´, ´Hidden actions by farmer organizations´, ´CC motivated agronomic actions´, ´CCA scientific knowledge production´, ´Risk-driven adaptations´ and ´Hidden governmental actions´. These types are helpful to show the broad range of local practices contributing to climate change adaptation. Several adaptation actions from practice are not motivated by climate change and thus are termed “hidden” adaptations, as they do not fit into common adaptation concepts. Hidden climate change adaptation practices, although not considered to date in official CCA policy documents, constitute “low-hanging fruit” for decision makers as they have already proved their feasibility and gained legitimacy by actors on the ground. We argue that additional support for such hidden adaptation practices can help to overcome present adaptation barriers and adaptation gaps.

Dirac line node (DLN) materials are topological semimetals wherein a set of symmetry protected crossing points forms a one-dimensional (1D) line in reciprocal space. Not only are the linearly dispersing bands expected to give rise to exceptional electronic properties, but the weak screening of the Coulomb interaction near the line node may enhance electronic correlations, produce new many-body ground states, or influence the quasiparticle lifetime. We investigate the quasiparticle dynamics in the DLN material ZrSiS via spectroscopic imaging scanning tunneling microscopy (SI-STM). By studying the spatial decay of quasiparticle interference patterns (QPI) from point scatterers, we were able to directly and selectively extract the phase coherence length $l_{\textrm{QPI}}$ and lifetime $\tau_{\textrm{QPI}}$ for the bulk DLN excitations, which are dominated by inelastic electron-electron scattering. We find that the experimental $\tau_{\textrm{QPI}}(E)$ values below $-$40 meV are very short, likely due to the stronger Coulomb interactions, and lie at the Planckian limit $\hbar/|E|$. Our results corroborate a growing body of experimental reports demonstrating unusual electronic correlation effects near a DLN.

A first-principles study of the adsorption of a single water molecule on a layer of graphitic carbon nitride employing an embedding approach is presented. The embedding approach involves an algorithm to obtain localized Wannier orbitals of various types expanded in a plane-wave basis and intrinsic atomic orbital projectors. The localized occupied orbitals are employed in combination with unoccupied natural orbitals to perform many-electron perturbation theory calculations of local fragments. The fragments are comprised of a set of localized orbitals close to the adsorbed water molecule. Although the surface model contains more than 100 atoms in the simulation cell, the employed fragments are small enough to allow for calculations using high-level theories up to the coupled cluster ansatz with single, double and perturbative triple particle-hole excitation operators (CCSD(T)). To correct for the missing long-range correlation energy contributions to the adsorption energy, we embed CCSD(T) theory into the direct random phase approximation, yielding rapidly convergent adsorption energies with respect to the fragment size. Convergence of computed binding energies with respect to the virtual orbital basis set is achieved employing a number of recently developed techniques. Moreover, we discuss fragment size convergence for a range of approximate many-electron perturbation theories. The obtained benchmark results are compared to a number of density functional calculations., 12 pages, 7 figures

We present a study of the two dimensional circular quantum dot model Hamiltonian using a range of quantum chemical ab initio methods. Ground and excited state energies are computed on different levels of perturbation theories including the coupled cluster method. We outline a scheme to compute the required Coulomb integrals in real space and utilize a semi-analytic solution to the integral over the Coulomb kernel in the vicinity of the singularity. Furthermore, we show that the remaining basis set incompleteness error for two dimensional quantum dots scales with the inverse number of virtual orbitals, allowing us to extrapolate to the complete basis set limit energy. By varying the harmonic potential parameter we tune the correlation strength and investigate the predicted ground and excited state energies.

The authors show the shortcomings of density functional theory to produce a coherent description of theground state properties of ZrO${}_{2}$ polymorphs and show an alternative scheme using high-level many-electron methods.

Improving market access and opportunities for value addition for small-scale food producers and family farms and properly functioning food commodity markets are among the objectives of the Sustainable Development Goals. Market structure and market concentration are important aspects that could make this goal attainable. In a case study, we explore the current conditions of pork and beef farmers in Austrian meat markets by combining a quantitative approach with qualitative inquiries. The quantitative analysis shows that the concentration of meat markets has been increasing in recent years. The rates of change differ in various segments of the value chain and across the types of markets. These results are the starting point for a qualitative analysis of the competitive situation in the observed markets. One finding is that in each market prices are set in idiosyncratic ways. Another one is that producer organizations are an appropriate means for small-scale and family-run farms to strengthen their position in the value chain. We conclude that policy initiatives to improve market access and value addition for farmers need to be complemented by targeted dissemination activities and that competition analyses should apply multi-method approaches similar to the one used in this analysis.

We present laser-induced photothermal synthesis of atomically precise graphene nanoribbons (GNRs). The kinetics of photothermal bottom-up GNR growth are unravelled by in situ Raman spectroscopy carried out in ultrahigh vacuum. We photothermally drive the reaction steps by short periods of laser irradiation and subsequently analyze the Raman spectra of the reactants in the irradiated area. Growth kinetics of chevron GNRs (CGNRs) and seven atoms wide armchair GNRs (7-AGNRs) is investigated. The reaction rate constants for polymerization, cyclodehydrogenation, and interribbon fusion are experimentally determined. We find that the limiting rate constants for CGNR growth are several hundred times smaller than for 7-AGNR growth and that interribbon fusion is an important elementary reaction occurring during 7-AGNR growth. Our work highlights that photothermal synthesis and in situ Raman spectroscopy are a powerful tandem for the investigation of on-surface reactions.

The photoluminescence from aligned 7-atom wide armchair-edge graphene nanoribbons coupled to plasmonic nanoantennas was recently observed to display blinking. Photoluminescence blinking is a hallmark of emission from single quantum emitters. Here we explore the origin of the blinking. We study the influence of the local field enhancement in the vicinity of nanoantennas on the photoluminescence blinking. We observe a clear correlation between the blinking amplitudes and the plasmonic enhancement. For non-resonant metal nanostructures the blinking vanishes almost completely. Our results allow us to conclude that the blinking is an intrinsic feature of the emission from the graphene nanoribbons. This is in contrast to the case of single-molecule surface-enhanced Raman scattering, where it is known that ballistic charge transfer between plasmonic nanoparticles and the molecule under study critically contributes to the blinking.

ObjectiveElevated Lp(a) plasma concentrations are determined mainly genetically by theLPAgene locus, but up to 70% of the coding sequence is located in the so-called “kringle IV type 2” (KIV-2) copy number variation. This region is not resolved by common genotyping technologies and large epidemiological studies on this region are therefore missing. The Arg21Ter variant (R21X, variant frequency ≈2%) is a functional variant in this region, but it has never been analyzed in large cohorts and is it unknown whether it is captured by genome-wide association studies.Approach and ResultsWe developed a highly sensitive allele-specific qPCR assay and genotyped R21X in 10,910 individuals from three populations (GCKD, KORA F3, KORA F4). R21X carriers showed significantly lower mean Lp(a) concentrations (−11.7 mg/dL [−15.5;−7.82], p=3.39e-32). Of particular note, virtually all R21X carriers also carried the splice mutation rs41272114 (D’=0.957, R2=0.275), as confirmed by pulsed-field gel electrophoresis and long-range haplotyping. This proposes that the R21X mutation arose on the background of the rs41272114 splice variant.ConclusionsWe performed the largest epidemiological study on anLPAKIV-2 variant so far. Interestingly, R21X is located on the same haplotype as the splice mutation rs41272114, creating “double-null”LPAalleles that are inactivated by two independent mutations. The effect of the R21X nonsense mutation can thus not be discerned from the effect of rs41272114 splice site mutation. This emphasizes the importance of assessing the complex LD structure withinLPAeven for functional variants.

The master-equation approach provides generation-recombination (g-r) noise in bulk semiconductors in terms of parameters of conduction electrons. It is shown that the g-r bulk noise can also be described by the random succession of elementary g-r pulses. This enables g-r bulk noise to be interpreted in terms of the numbers of traps. The transition from g-r bulk noise to discrete switching in small-area semiconductors is found by reducing the number of traps to just one single active trap. The resulting g-r noise spectrum is shown to be equivalent to Machlups noise spectrum. The probability of an overlap of succeeding g-r pulses is calculated. Such an overlap is attributed to the occupation of an empty single trap by an electron transferred from a neighboring trap. Simulating a g-r pulse train we find a large variety of patterns similar to those observed in MOSFETs. Excluding overlapping g-r pulses, the up and down distribution of succeeding g-r pulses is estimated., 13 pages, 9 figures and addendum

For quasi-freestanding 2H-TaS

The progress of lipid oxidation in foods is evaluated by measuring the peroxides and their scission products. However, hydrogen abstraction-independent pathways are not considered by commonly applied methods despite the known reactivity of epoxides toward biomolecules. Herein, a novel liquid chromatography tandem-mass spectrometry method was developed to detect hydroperoxidized and epoxidized triacylglycerols (TAGs) without derivatization or hydrolyzation of food samples. Epoxidized TAGs could be detected in refined canola oil at concentrations of 96.8 ± 2.08 μM, while only 5.77 ± 0.04 μM hydroperoxidized TAGs could be determined. In contrast to canola oil, margarine was more resistant to lipid oxidation since generation of epoxidized TAGs could only be marginally enhanced from 21.7 ± 0.48 to 28.8 ± 0.64 μM in margarine after treatment at 180 °C for 60 min, as also reflected by a peroxide value of 0.80 ± 0.00 mequiv O2/kg, which remained unchanged. The new method allows the assessment of food safety by the simultaneous measurement of hydroperoxidized and epoxidized TAGs without hydrolysis and laborious sample preparation.

Armchair graphene nanoribbons (AGNRs) with tunable band gap are a promising material for optoelectronic devices. We have earlier investigated the optical properties of seven atom wide AGNRs (7-AGNRs) and shown how photoluminescence emission at 1.8 eV is boosted via formation of defects in the atomic lattice of the ribbons by hydrogenation or by a photochemical process [1]. Here we probe the origin of this modification by measuring the extinction spectrum of a layer of AGNRs and demonstrate photodetection using AGNRs.

The random phase approximation (RPA) systematically overestimates the magnitude of the correlation energy and generally underestimates cohesive energies. This originates in part from the complete lack of exchange terms that would otherwise cancel Pauli exclusion principle violating (EPV) contributions. The uncanceled EPV contributions also manifest themselves in form of an unphysical negative pair density of spin-parallel electrons close to electron-electron coalescence. We follow considerations of many-body perturbation theory to propose an exchange correction that corrects the largest set of EPV contributions, while having the lowest possible computational complexity. The proposed method exchanges adjacent particle/hole pairs in the RPA diagrams, considerably improving the pair density of spin-parallel electrons close to coalescence in the uniform electron gas (UEG). The accuracy of the correlation energy is comparable to other variants of second-order screened exchange (SOSEX) corrections although it is slightly more accurate for the spin-polarized UEG. Its computational complexity scales as [Formula: see text] or [Formula: see text] in orbital space or real space, respectively. Its memory requirement scales as [Formula: see text].

We investigate the basis-set convergence of electronic correlation energies calculated using coupled cluster theory and a recently proposed finite basis-set correction technique. The correction is applied to atomic and molecular systems and is based on a diagrammatically decomposed coupled cluster singles and doubles correlation energy. Only the second-order energy and the particle-particle ladder term are corrected for their basis-set incompleteness error. We present absolute correlation energies and results for a large benchmark set. Our findings indicate that basis set reductions by two cardinal numbers are possible for atomization energies, ionization potentials and electron affinities without compromising accuracy when compared to conventional CCSD calculations. In the case of reaction energies we find that reductions by one cardinal number are possible compared to conventional CCSD calculations. The employed technique can readily be applied to other many-electron theories without the need for three- or four-electron integrals., Comment: 9 pages, 3 figures, 6 tables

We apply scanning tunneling spectroscopy to determine the bandgaps of mono-, bi- and trilayer MoS$_2$ grown on a graphene single crystal on Ir(111). Besides the typical scanning tunneling spectroscopy at constant height, we employ two additional spectroscopic methods giving extra sensitivity and qualitative insight into the $k$-vector of the tunneling electrons. Employing this comprehensive set of spectroscopic methods in tandem, we deduce a bandgap of $2.53\pm0.08$ eV for the monolayer. This is close to the predicted values for freestanding MoS$_2$ and larger than is measured for MoS$_2$ on other substrates. Through precise analysis of the `comprehensive' tunneling spectroscopy we also identify critical point energies in the mono- and bilayer MoS$_2$ band structures. These compare well with their calculated freestanding equivalents, evidencing the graphene/Ir(111) substrate as an excellent environment upon which to study the many feted electronic phenomena of monolayer MoS$_2$ and similar materials. Additionally, this investigation serves to expand the fledgling field of the comprehensive tunneling spectroscopy technique itself., Comment: 8 pages, 5 figures, accepted

We present a diagrammatic decomposition of the transition pair correlation function for the uniform electron gas. We demonstrate explicitly that ring and ladder diagrams are dual counterparts that capture significant long- and short-ranged interelectronic correlation effects, respectively. Our findings help to guide the further development of approximate many-electron theories and reveal that the contribution of the ladder diagrams to the electronic correlation energy can be approximated in an effective manner using second-order perturbation theory. We employ the latter approximation to reduce the computational cost of coupled cluster theory calculations for insulators and semiconductors by two orders of magnitude without compromising accuracy., 6 pages, 2 figures, 1 table

We measure the absolute absorbance of a single layer of seven atom wide armchair graphene nanoribbons and study the influence of laser-induced defects on the absorption spectrum of the ribbons. We find that the absorption spectrum shows a broad peak at approximately 2.4 eV that is attributed to excitonic transitions and a smaller peak at 1.77 eV. The low-energy peak is diminished when we induce defects in the material. Simultaneously the photoluminescence is significantly enhanced. We thus attribute the 1.77 eV spectral feature in the absorption spectrum to a quenching state, which energetically coincides with the emission. Our results clearly demonstrate the significance of this state in photoluminescence processes in the ribbons. We additionally measure the dependence of the generation of defects on the energy of the incident photons and the photoluminescence excitation spectrum. The photoluminescence excitation efficiency peaks at a higher photon energy than the maximum absorption, hinting at an efficient decay from higher energetic states to the emissive state.

Scanning tunneling microscopy and spectroscopy are used to image the charge density wave at the surface of cleaved ${\mathrm{VSe}}_{2}$ and to probe its local density of states at 5 K. The main features in the spectrum are linked to the contributions of the $p$-like and $d$-like bands of ${\mathrm{VSe}}_{2}$ found in angle-resolved photoemission spectroscopy and tight-binding calculations. Different from previous tunneling spectroscopy work, we find a narrow partial gap at the Fermi level that we associate with the charge density wave phase. The energy scale of the gap found in the experiment is in good agreement with the charge density wave transition temperature of ${\mathrm{VSe}}_{2}$, under the assumption of weak electron-phonon coupling, consistent with the Peierls model of Fermi surface nesting. The role of defects is investigated, which reveals that the partial gap in the density of states and hence the charge density wave itself is extremely stable, though the order, phase, and amplitude of the charge density waves on the surface are strongly perturbed by defects.

We present an implementation of the equation of motion coupled-cluster singles and doubles (EOM-CCSD) theory using periodic boundary conditions and a plane wave basis set. Our implementation of EOM-CCSD theory is applied to study F-centers in alkaline earth oxides employing a periodic supercell approach. The convergence of the calculated electronic excitation energies for neutral color centers in MgO, CaO, and SrO crystals with respect to the orbital basis set and system size is explored. We discuss extrapolation techniques that approximate excitation energies in the complete basis set limit and reduce finite size errors. Our findings demonstrate that EOM-CCSD theory can predict optical absorption energies of F-centers in good agreement with experiment. Furthermore, we discuss calculated emission energies corresponding to the decay from triplet to singlet states responsible for the photoluminescence properties. Our findings are compared to experimental and theoretical results available in the literature.

We present an embedding approach to treat local electron correlation effects in periodic environments. In a single, consistent framework, our plane-wave based scheme embeds a local high-level correlation calculation (here Coupled Cluster Theory, CC), employing localized orbitals, into a low-level correlation calculation (here the direct Random Phase Approximation, RPA). This choice allows for an accurate and effcient treatment of long-range dispersion effects. Accelerated convergence with respect to the local fragment size can be observed if the low-level and high-level long-range dispersion are quantitatively similar, as is the case for CC in RPA. To demonstrate the capabilities of the introduced embedding approach, we calculate adsorption energies of molecules on a surface and in a chabazite crystal cage, as well as the formation energy of a lattice impurity in a solid at the level of highly accurate many-electron perturbation theories. The absorption energy of a methane molecule in a zeolite chabazite, for instance, is converged with an error well below 20 meV at the CC level. As our largest periodic benchmark system, we apply our scheme to the adsorption of a water molecule on titania in a supercell containing more than 1000 electrons., 6 pages, 2 figures

A setup for the preparation of oriented Au(111)/mica thin films of ∼100 nm thickness as an active substrate for graphene nanoribbon growth is shown. Low-energy electron diffraction shows that the Au(111) thin films have a single crystallographic orientation over the whole surface area. Graphene nanoribbons are synthesized by the bottom-up approach via surface polymerization of precursor molecules that are evaporated onto the catalytically active Au(111)/mica substrate. The graphene nanoribbons are investigated by a combination of resonance Raman, X-ray photoemission spectroscopy, and near-edge X-ray absorption fine structure spectroscopy confirming a nanoribbon quality equal to nanoribbons grown on commercially available single-crystal Au(111) substrates. The present work, therefore, establishes the insitu preparation of Au(111)/mica as an inexpensive and simple method to prepare substrates of desired shape and thickness for surface polymerization reactions which are of interest to a growing community of researchers working on graphene nanoribbons.