Search

Topological materials exhibit protected edge modes that have been proposed for applications in, for example, spintronics and quantum computation. Although a number of such systems exist, it would be desirable to be able to test theoretical proposals in an artificial system that allows precise control over the key parameters of the model. The essential physics of several topological systems can be captured by tight-binding models, which can also be implemented in artificial lattices. Here, we show that this method can be realized in a vacancy lattice in a chlorine monolayer on a Cu(100) surface. We use low-temperature scanning tunnelling microscopy (STM) to fabricate such lattices with atomic precision and probe the resulting local density of states (LDOS) with scanning tunnelling spectroscopy (STS). We create analogues of two tight-binding models of fundamental importance: the polyacetylene (dimer) chain with topological domain-wall states, and the Lieb lattice with a flat electron band. These results provide an important step forward in the ongoing effort to realize designer quantum materials with tailored properties.

π-conjugated organic molecules tend to adsorb in a planar configuration on graphene irrespective of their charge state. In contrast, here we demonstrate charging-induced strong structural relaxation of tetrafluorotetracyanoquinodimethane (F4TCNQ) on epitaxial graphene on Ir(111) (G/Ir(111)). The work function modulation over the graphene moiré unit cell causes site-selective charging of F4TCNQ. Upon charging, the molecule anchors to the face-centered cubic sites of the G/Ir(111) moiré through one or two cyano groups. The reaction is reversible and can be triggered on a single molecule by moving it between different adsorption sites. We introduce a model taking into account the trade-off between tilt-induced charging and reduced van der Waals interactions, which provides a general framework for understanding charging-induced structural relaxation on weakly interacting substrates. In addition, we argue that the partial sp3rehybridization of the underlying graphene and the possible bonding mechanism between the cyano groups and the graphene substrate are also relevant for the complete understanding of the experiments. These results provide insight into molecular charging on graphene, and they are directly relevant for potential device applications where the use of molecules has been suggested for doping and band structure engineering.

On-surface synthesis with molecular precursors has emerged as the de facto route to atomically well-defined graphene nanoribbons (GNRs) with controlled zigzag and armchair edges. On Au(111) and Ag(111) surfaces, the prototypical precursor 10,10′-dibromo-9,9′-bianthryl (DBBA) polymerizes through an Ullmann reaction to form straight GNRs with armchair edges. However, on Cu(111), irrespective of the bianthryl precursor (dibromo-, dichloro-, or halogen-free bianthryl), the Ullmann route is inactive, and instead, identical chiral GNRs are formed. Using atomically resolved noncontact atomic force microscopy (nc-AFM), we studied the growth mechanism in detail. In contrast to the nonplanar BA-derived precursors, planar dibromoperylene (DBP) molecules do form armchair GNRs by Ullmann coupling on Cu(111), as they do on Au(111). These results highlight the role of the substrate, precursor shape, and molecule–molecule interactions as decisive factors in determining the reaction pathway. Our findings establish a new design paradigm for molecular precursors and opens a route to the realization of previously unattainable covalently bonded nanostructures.

We report on molecular self-assembly employing a host–guest architecture to pattern the growth of molecules on graphene model surface. Under suitable conditions, the 1,3,5-benzenetribenzoic acid (BTB) self-assembles into an extended honeycomb mesh on graphene on Ir(111), with the molecules in the network being stabilized by linear hydrogen bonds between the carboxylic groups. The nanopores of the mesh are used to host and govern the assembly of cobalt phthalocyanine (CoPC) guest molecules. We characterize the assembled structures structurally and electronically using low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. At a coverage higher than one CoPc per pore, the flexible hydrogen bonds of the host network undergo stretching to accommodate two CoPCs in a single pore. When the pores are uniformly doubly occupied, the guest molecules arrange into a herringbone pattern. This minimizes the energy cost associated with the stretching and twisting of the hydrogen bonds between the BTB molecules. The phenomenon observed here can be used to tailor molecular assemblies on graphene to controllably modify its properties. In addition, it allows the formation of guest monomers and dimers stabilized mechanically on the surface of graphene, an archetypical weakly interacting substrate.

Field-emission resonances (FERs) can be used to map the work function of a conducting surface with a high spatial resolution. While FERs have been measured on different graphene systems, measurements on graphene transferred on insulating substrates have not been carried out previously. Here we have measured FERs on graphene transferred on hexagonal boron nitride (h-BN) and silicon dioxide (SiO2) substrates. We have also developed a simple 1D model that can be used to directly interpret the constant current spectroscopy experiments. On both surfaces, FERs can be used to map the local work function changes.

Metal phthalocyanines (MPc) form a tunable class of molecules, where both the central metal ion and the organic macrocycle can be modified. This allows the electronic properties and self-assembly of these molecules to be tuned over a broad range. We focus on cobalt phthalocyanine (CoPc), copper phthalocyanine (CuPc), and fully fluorinated cobalt phthalocyanine (F16CoPc) and study their self-assembly on epitaxial graphene. We investigate the energetic positions and symmetries of the frontier molecular orbitals by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) experiments and density functional theory (DFT) calculations. Our results shed light on the molecular ordering and the energies of molecular orbitals with respect to the graphene Dirac point for the different MPcs. This information will be crucial for using molecular overlayers to modify the electronic properties of graphene.

Frequency modulation atomic force microscopy (AFM) allows the chemical structure of planar molecules to be determined with atomic resolution. Typically, these measurements are carried out in constant-height mode using carbon monoxide (CO) terminated tips. Such tips exhibit considerable flexibility, i.e., the CO molecule can bend laterally due to the tip–sample interaction. Using epitaxial graphene as a model system, we demonstrate experimentally that the apparent atomic positions measured by AFM depend on the sample corrugation. Using molecular mechanics simulations, we explain these observations by the interplay of the CO bending and the nonlinear background signal arising from the neighboring atoms. These effects depend nontrivially on the tip–sample distance and limit the achievable accuracy on the bond length determination based on AFM experiments.

Using low-temperature scanning tunneling microscopy, we show that monolayer hexagonal boron nitride (h-BN) on Ir(111) acts as ultrathin insulating layer for organic molecules, while simultaneously templating their self-assembly. Tunneling spectroscopy experiments on cobalt phthalocyanine (CoPC) reveal narrow molecular resonances and indicate that the charge state of CoPC is periodically modulated by the h-BN moiré superstructure. Molecules in the second layer show site-selective adsorption behavior, allowing the synthesis of molecular dimers that are spatially ordered and inaccessible by usual chemical means.

The phylogeographical evolution and the consequent changing distribution and diversity of rhynchonelliform brachiopods through the Ordovician are linked to the dynamic palaeogeography of the period. The Early Ordovician (Tremadocian and Floian) is characterized by globally low-diversity faunas with local biodiversity epicentres, notably on the South China Palaeoplate; low-latitude porambonitoid-dominated faunas with early plectambonitoid and clitambonitoid representatives, as well as high-latitude assemblages mostly dominated by orthoids, can be recognized, but many taxa are rooted in Late Cambrian stocks. The Early Ordovician displays a steady increase in rhynchonelliformean biodiversity, which was mostly driven by the increasing success of the Porambonitoidea and Orthoidea, but the billingsellids and early plectambonitoids also contributed to this expansion. During the Early to Mid Ordovician (Dapingian–Darriwilian), marine life experienced an unprecedented hike in diversity at the species, genus and family levels that firmly installed the suspension-feeding benthos as the main component of the Palaeozoic fauna. However, this may have occurred in response to an early Darriwilian annihilation of existing clades, some of which had been most successful during the Early Ordovician. New clades rapidly expanded. The continents were widely dispersed together with a large number of microcontinents and volcanic arcs related to intense magmatic and tectonic activity. Climates were warm and sea-levels were high. Pivotal to the entire diversification is the role of gamma (inter-provincial) diversity and by implication the spread of the continents and frequency of island arcs and microcontinents. The phylogeographical analysis demonstrates that this new palaeogeographical configuration was particularly well explored and utilized by the strophomenides, especially the Plectambonitoidea, which radiated rapidly during this interval. The porambonitoids, on the other hand, were still in recovery following the early Darriwilian extinctions. Orthides remained dominant, particularly at high latitudes. Biodiversity epicentres were located on most of the larger palaeoplates, as well as within the Iapetus Ocean. Provincial patterns were disrupted during the Sandbian and early Katian with the migration of many elements of the benthos into deeper-water regimes, enjoying a more cosmopolitan distribution. Later Katian faunas exhibit a partition between carbonate and clastic environments. During the latest Katian, biogeographical patterns were disrupted by polewards migrations of warm-water taxa in response to the changing climate; possibly as a consequence of low-latitude cradles being developed in, for instance, carbonate reef settings. Many clades were well established with especially the strophomenides beginning to outnumber the previously successful orthides, although this process had already begun, regionally, in the mid to late Darriwilian. At the same time, atrypoid and pentameroid clades also began to radiate in low-latitude faunas, anticipating their dominance in Silurian faunas. The Hirnantian was marked by severe extinctions particularly across orthide-strophomenide clades within the context of few, but well-defined, climatically controlled provincial belts.Supplementary material:The individual localities and a reference list for the data sources are provided at: http://www.geolsoc.org.uk/SUP18667

Atomic force microscopy (AFM) images of graphene and graphite show contrast with atomic periodicity. However, the contrast patterns vary depending on the atomic termination of the AFM tip apex and the tip–sample distance, hampering the identification of the atomic positions. Here, we report quantitative AFM imaging of epitaxial graphene using inert (carbon-monoxide-terminated) and reactive (iridium-terminated) tips. The atomic image contrast is markedly different with these tip terminations. With a reactive tip, we observe an inversion from attractive to repulsive atomic contrast with decreasing tip–sample distance, while a nonreactive tip only yields repulsive atomic contrast. We are able to identify the atoms with both tips at any tip–sample distance. This is a prerequisite for future structural and chemical analysis of adatoms, defects, and the edges of graphene nanostructures, crucial for understanding nanoscale graphene devices.

We have studied the adsorption and self-assembly of cobalt phthalocyanine (CoPc) on epitaxial graphene grown on iridium (111) by scanning tunneling microscopy (STM), Auger electron spectroscopy, and low-energy electron diffraction (LEED). CoPc deposited on graphene/Ir(111) at room-temperature self-assembles into large, well-ordered domains with a nearly square unit cell. On the basis of the observed LEED pattern and STM images, a detailed structure for the overlayer is proposed. Despite the corrugation of the moiré pattern of graphene on Ir(111), its hexagonal symmetry is not translated to the CoPc layer. This is in contrast to systems with stronger graphene–metal interaction that makes graphene on Ir(111) a convenient, clean, and well-defined model system for studying molecular doping of graphene.

Phytophthora is the most devastating pathogen of dicot plants. There is a need for resistance sources with different modes of action to counteract the fast evolution of this pathogen. In order to better understand mechanisms of defense against P. infestans, we analyzed several clones of potato. Two of the genotypes tested, Sarpo Mira and SW93-1015, exhibited strong resistance against P. infestansin field trials, whole plant assays and detached leaf assays. The resistant genotypes developed different sizes of hypersensitive response (HR)-related lesions. HR lesions in SW93-1015 were restricted to very small areas, whereas those in Sarpo Mira were similar to those in Solanum demissum, the main source of classical resistance genes. SW93-1015 can be characterized as a cpr(constitutive expressor of PR genes) genotype without spontaneous microscopic or macroscopic HR lesions. This is indicated by constitutive hydrogen peroxide (H2O2) production and PR1 (pathogenesis-related protein 1) secretion. SW93-1015 is one of the first plants identified as having classical protein-based induced defense expressed constitutively without any obvious metabolic costs or spontaneous cell death lesions.

This article reports on the charging behavior of thin films of alkanethiol protected gold nanoparticles, so-called monolayer protected clusters (MPCs), immersed in aqueous solution. We demonstrate that the oxidation of the MPCs is controlled by the transfer of counter-ions across the aqueous/MPC film interface. A model is developed to describe this and its predictions compared with experiment. Langmuir-Schaefer MPC thin films were transferred to a glassy carbon electrode and film charging behavior investigated in a series of aqueous solutions comprised of different base electrolyte anions. The dependence of peak current on film thickness and peak position on anion lipophilicity for MPC oxidative charging can all be accounted for with the ion-transfer limited model. The impact of ion partitioning into the film at equilibrium is also discussed and the effect of the aqueous phase cation is theoretically considered. In addition, the effect of co-transported water with hydrophilic ions transferring into the film on film charging is rationalized.

Most systems exhibiting topological superconductivity are artificial structures that require precise engineering. Now, a layered material shows tantalizing signs of the phenomenon.

Wheat (Triticum aestivumL.)‐Rye (Secale cerealeL.) T2BS.2RL translocations were shown to increase grain yield, resistance to biotic and abiotic stresses, and had minor effects on baking quality. The objective of this study was to test agronomic performance and resistance of a new wheat‐rye translocation (T2BS.2RL, SLU) to powdery mildew (Blumeria graminisf. sp. tritici(DC.) E. O. Speer), leaf rust (Puccinia triticinaEriks.), stem rust (Puccinia graminisf. sp. triticiEriks. & Henn.), stripe rust (Puccinia striiformisf. sp. triticiWestend.) and Hessian fly [Mayetiola destructor(Say)]. F2derived F4–F6T2BS.2RL lines, non‐translocation lines, and the wheat cultivar Holme were compared using intact seedlings or leaf segments. T2BS.2RL conferred seedling resistance to 17 powdery mildew isolates, 14 leaf rust and one stem rust pathotype. The T2BS.2RL lines were susceptible to 3 stripe rust pathotypes as seedlings, while showing adult plant resistance under natural conditions. Agronomic characters were compared in a 2‐yr hill‐plot field trial in Sweden. T2BS.2RL lines flowered 2 to 3 d later and had an increased number of spikelets per spike. The T2BS.2RL had no significant effect on yield, straw length, lodging, volume weight, 1000‐kernel weight, fertility, α‐amylase activity, or starch or protein content. The multiple disease resistance and the minor negative effects on agronomic performance of the T2BS.2RL, SLU translocation encourage its use in wheat breeding.

Single-component and mixed self-assembled monolayers (SAMs) of one- and three-ring semirigid tetrahydro-4H-thiopyran end-capped oligo(cyclohexylidenes)&sbd;that is, thiopyran (1), 4-(4-cyclohexylidene-cyclohexylidene)tetrahydro-4H-thiopyran (2), and 4-(tetrahydro-4H-thiopyran-4-cyclohexylidene-4‘-ylidene)tetrahydro-4H-thiopyran (3)&sbd;on Au(111) substrates have been prepared and studied by cyclic voltammetry (CV), atomic force microscopy (AFM), and scanning tunneling microscopy (STM). It was found that the shortest adsorbate 1 more readily forms a SAM than 2 or 3. Notwithstanding, the SAMs of 2 or 3 are thermodynamically more stable due to favorable intermolecular attractions. Holes were made with the AFM tip establishing tilt angles of 30−50° with respect to the surface normal for all SAMs. STM imaging showed well-ordered, line-shaped packing patterns with molecular resolution for the SAM of 2. Similar patterned structures were not observed for 1 and 3. Mixed SAMs were prepared by exposing a SAM of 1 to ethanol solutions of either 2 or 3. STM imaging revealed that domains of molecules of 2 or 3 amidst a monolayer of 1 are formed in both cases. Whereas in the mixed SAM of 1 and 2 the domains are irregularly shaped, circular islands of uniform size are found in the mixed SAM of 1 and 3.

We review the optical and electrical properties of solids that are composed of semiconductor nanocrystals. Crystals, with dimensions in the nanometre range, of II–VI, IV–VI and III–V compound semiconductors, can be prepared by wet-chemical methods with a remarkable control of their size and shape, and surface chemistry. In the uncharged ground state, such nanocrystals are insulators. Electrons can be added, one by one, to the conduction orbitals, forming artificial atoms strongly confined in the nanocrystal. Semiconductor nanocrystals form the building blocks for larger architectures, which self-assemble due to van der Waals interactions. The electronic structure of the quantum dot solids prepared in such a way is determined by the orbital set of the nanocrystal building blocks and the electronic coupling between them. The opto-electronic properties are dramatically altered by electron injection into the orbitals. We discuss the optical and electrical properties of quantum dot solids in which the electron occupation of the orbitals is controlled by the electrochemical potential.

The heterogeneous oxidation of the fullerene monoanion by aqueous-phase molecular oxygen is reported. Scanning electrochemical microscopy (SECM) is used to investigate the electron transfer (ET) kinetics at an externally biased water−chlorobenzene (CB) interface. The kinetic parameters obtained indicate that ET is fast and can be controlled by the applied interfacial potential difference. A novel means of applying SECM to an electrified liquid−liquid interface is introduced. Provided the size of the liquid−liquid interface is sufficiently small such that the current flow is in the nanoampere range, a conventional bipotentiostatic arrangement can be used to externally control both the interfacial potential difference (%@mt;sys@%Δ%@sx@%o%@be@%w%@sxx@%%@mx@% φ) at the liquid−liquid interface and the SECM tip potential. This arrangement provides a simple and fast means of studying ET reactions at a range of %@mt;sys@%Δ%@sx@%o%@be@%w%@sxx@%%@mx@% φ without the need to vary either the base electrolyte ions or their concentrations. The potential dependence of both the forward and the backward rate constants for the model ET reaction between 7,7,8,8-tetracyanoquinodimethane and hexacyanoferrate was initially investigated at the water−1,2-dichloroethane interface to demonstrate the applicability of the present technique.

We present quantitative measurements of the adsorption of drug ions at Langmuir monolayers, which are considered as a model for biological membranes. The technique we have employed is based on scanning electrochemical microscopy using a capillary probe filled with organic electrolyte solution and operated in an inverted submarine arrangement in a Langmuir trough. In this experimental arrangement, we have made potential step chronoamperometric measurements, with the probe adjacent to the Langmuir monolayer deposited at the air/water interface, to extract information on the adsorption process. We have measured the adsorption of a cationic β-blocker drug, propranolol, at a Langmuir monolayer of stearic acid. By developing a theoretical simulation that assumes that the equilibrium at the interface is controlled by the competition between the acid/base equilibrium of the stearic acid molecules at the surface and the electrostatically induced adsorption of the positively charged propranolol ion, we have been able to extract from our data a drug adsorption constant of (5 ± 1) × 10^-5 mol dm^-3 at the monolayer surface pressure of 10 mN m^-1.

The deposition of polyelectrolyte multilayers at an aqueous solution−organic gel interface by layer by layer deposition of anionic poly(sodium 4-styrenesulfonate) and cationic poly(allylamine hydrochloride) is described. With suitable electrolytes and electrodes in both phases, alternating current voltammetry is employed to measure the capacitance of the polyelectrolyte multilayer as a function of the number and type of layers deposited. The charge distribution across the interface is investigated by analyzing the capacitance measurements based on a theoretical model that describes the potential profile across the multilayer at the interface between the two electrolyte solutions. Subsequently, cyclic voltammetry is used to probe the transfer of cationic tetraethylammonium and the cationic Alzheimer drug 9-amino-1,2,3,4-tetrahydroacridine (tacrine) across the polyelectrolyte multilayer. The effective transfer rate constant is reduced by the presence of the multilayer film, and the lower rate observed for a polycation- compared with a polyanion-terminated multilayer is interpreted in terms of the theoretical model.

The use of a differential pressure transducer provides an accurate and rapid measurement of interfacial tension at an electrified liquid−liquid interface, by application of the Laplace equation to the continuously measured pressure of an aqueous droplet in the organic phase. This new method can measure the dynamics of response of interfacial tension both to changes of interfacial potential difference (e.g., during cyclic voltammetry) and to changes of area. It has been applied to the study of an electrified water/1,2-dichloroethane interface in the absence and presence of distearoylphosphatidylcholine (DSPC), to deduce the potential-dependent kinetics of lipid adsorption and desorption. Two modes of operation were used:  variable interfacial potential difference at stationary drops and constant potential at expanding droplets. Because of the adsorption of DSPC, the interfacial tension decreased at negative interfacial potential differences (the aqueous wrt the organic phase). However, at positive potentials, the interfacial tension approached the values at a bare interface. At low scan rates, the interfacial tension superimposed on forward and reverse scans, while at scan rates above 2 mV/s increasing hysteresis was observed. Using a theory based on Langmuirian adsorption isotherm and kinetics, the dynamic interfacial tension at expanding droplets was interpreted to yield values of the potential-dependent adsorption equilibrium constant and the rate constant of the adsorption process as a function of the potential difference between the phases. The adsorption kinetics were found to be fast with a forward rate constant larger than 0.1 cm/s irrespective of the potential difference.

The influence of surfactants on nucleation at liquid|liquid interfaces was studied by cyclic voltammetry and chronoamperometry. The surface activity of a nanoparticle was considered within classical thermodynamics. These considerations indicated that while large particles preferentially reside in the interfacial region, small particles are not surface active. This results in a second critical radius in nucleation experiments. The experiments where the interfacial tension was changed by addition of a surfactant were in line with theoretical predictions.

The drug partitioning between membrane and solution has traditionally been approached with bulk thermodynamic models, such as the octanol−water partitioning system. This neglects the orientational and compositional order in biological membranes. In the present study, electrochemistry at a Langmuir−Blodgett phospholipid monolayer-modified liquid−liquid interface has been employed to study the specific interactions between ionized drugs and phosphatidylcholine layers. To this end, AC voltammetric experiments and theoretical modeling accounting for the adsorption of the electroactive species have been carried out. The results point to a mechanism of charge transfer involving an adsorption step. This highlights the fact that in predicting biological activity of drugs, dynamic aspects and chemical interactions need to be considered.

A growing body of evidence points out the potential role of inflammatory mechanisms in the pathophysiology of brain damage in dementia. In previous studies, we have demonstrated intrathecal production of the proinflammatory cytokine tumor necrosis factor (TNF)α in patients with Alzheimer’s disease (AD). The aim of the present study was to investigate the downstream products of TNF-α expression including interleukin (IL)1β and its naturally occurring antagonist IL-1 receptor agonist (ra) in patients with AD. The cytokine levels were related to neuronal damage, as measured by intrathecal τ and β-amyloid concentration and certain clinical features of the disease. Fifty-two patients with AD and 25 healthy controls were analyzed with respect to cerebrospinal fluid (CSF) levels of IL-1β and IL-1ra. CSF IL-1β was neither detectable in CSF of AD nor in control CSF. In contrast, a significantly lower (p < 0.01) number of patients (24 of 49) than of controls (20 of 24) showed detectable levels of IL-1ra in the CSF. The intrathecal levels of IL-1ra were significantly lower in patients with AD than in the controls. Our study demonstrates a decreased production of the anti-inflammatory compound IL-1ra, suggesting a propensity towards inflammation in patients with AD.

One of enduring problems of phospholipid adsorption at the interface between two immiscible electrolyte solutions (ITIES) has been the inability to determine and control the exact nature of the adsorbed monomolecular layer. In the present study, this problem has been overcome by the use of the well-known Langmuir−Blodgett technique. It has been shown that reproducible layers of known surface pressure can be deposited at the interface and that the deposition surface pressure has a great influence on the behavior of the layer. Interfacial capacitance data has been extracted and electrocapillary curves have been drawn. The noted shift in the electrocapillary minimum and the lowered interfacial capacitance have been explained by use of a simple electrostatic model. Probe ion transfer studies show no change in the interfacial kinetics or in the Gibbs free energy of transfer.

To analyze the extent of tumor necrosis factor- (TNF) and TNF gene polymorphism in patients with AD and to relate it to intrathecal levels of these cytokines.

The search for artificial topological superconductivity has been limited by the stringent conditions required for its emergence. As exemplified by the recent discoveries of various correlated electronic states in twisted van der Waals materials, moiré patterns can act as a powerful knob to create artificial electronic structures. Here, we demonstrate that a moiré pattern between a van der Waals superconductor and a monolayer ferromagnet creates a periodic potential modulation that enables the realization of a topological superconducting state that would not be accessible in the absence of the moiré. The magnetic moiré pattern gives rise to Yu–Shiba–Rusinov minibands and periodic modulation of the Majorana edge modes that we detect using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Moiré patterns and, more broadly, periodic potential modulations are powerful tools to overcome the conventional constraints for realizing and controlling topological superconductivity.

Six years after application of ammonium nitrate and urea to a podzolic soil, samples from the humus layer (A01/A02) were extracted with ethanol or diethyl ether, and the extracts were pyrolysed. The pyrograms were statistically analysed with a pattern recognition computer program (SIMCA). Pyrolysis of ethanol extracts resulted in pyrograms that allowed separation between control soil and ammonium nitrate-treated soil. Pyrograms of ether extracts allowed separation between urea-treated and control soil. The results indicate that the methodology can be used for separating closely related soils.

Understanding the dynamics of the human proteome is crucial for developing biomarkers to be used as measurable indicators for disease severity and progression, patient stratification, and drug development. The Proximity Extension Assay (PEA) is a technology that translates protein information into actionable knowledge by linking protein-specific antibodies to DNA-encoded tags. In this report we demonstrate how we have combined the unique PEA technology with an innovative and automated sample preparation and high-throughput sequencing readout enabling parallel measurement of nearly 1500 proteins in 96 samples generating close to 150,000 data points per run. This advancement will have a major impact on the discovery of new biomarkers for disease prediction and prognosis and contribute to the development of the rapidly evolving fields of wellness monitoring and precision medicine.

The combination of two-dimensional (2D) materials into vertical heterostructures has emerged as a promising path to designer quantum materials with exotic properties. Here, we extend this concept from inorganic 2D materials to 2D metal–organic frameworks (MOFs) that offer additional flexibility in realizing designer heterostructures. We successfully fabricate a monolayer 2D Cu-dicyanoanthracene MOF on a 2D van der Waals NbSe2superconducting substrate. The structural and electronic properties of two different phases of the 2D MOF are characterized by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS), complemented by density-functional theory (DFT) calculations. These experiments allow us to follow the formation of the kagome band structure from Star of David-shaped building blocks. This work extends the synthesis and electronic tunability of 2D MOFs beyond the electronically less relevant metal and semiconducting surfaces to superconducting substrates, which are needed for the development of emerging quantum materials such as topological superconductors.

The advent of on-surface chemistry under vacuum has vastly increased our capabilities to synthesize carbon nanomaterials with atomic precision. Among the types of target structures that have been synthesized by these means, graphene nanoribbons (GNRs) have probably attracted the most attention. In this context, the vast majority of GNRs have been synthesized from the same chemical reaction: Ullmann coupling followed by cyclodehydrogenation. Here, we provide a detailed study of the growth process of five-atom-wide armchair GNRs starting from dibromoperylene. Combining scanning probe microscopy with temperature-dependent XPS measurements and theoretical calculations, we show that the GNR growth departs from the conventional reaction scenario. Instead, precursor molecules couple by means of a concerted mechanism whereby two covalent bonds are formed simultaneously, along with a concomitant dehydrogenation. Indeed, this alternative reaction path is responsible for the straight GNR growth in spite of the initial mixture of reactant isomers with irregular metal–organic intermediates that we find. The provided insight will not only help understanding the reaction mechanisms of other reactants but also serve as a guide for the design of other precursor molecules.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.