Abstract: A multiscale modeling and simulation approach, including first-principles calculations, ab initio molecular dynamics simulations, and a tight binding approach, is employed to study band flattening of the electronic band structure of oxidized monolayer graphene. The width offlat bands can be tuned by strain, the external electric field, and the density of functional groups and their distribution. A transition to a conducting state is found for monolayer graphene with impurities when it is subjected to an electric field of similar to 1.0 V/angstrom. Several parallel impurity-induced flat bands appear in the low-energy spectrum of monolayer graphene when the number of epoxy groups is changed. The width of the flat band decreases with an increase in tensile strain but is independent of the electric field strength. Here an alternative and easy route for obtaining band flattening in thermodynamically stable functionalized monolayer graphene is introduced. Our work discloses a new avenue for research on band flattening in monolayer graphene.

Abstract: This article describes the development of an electrochemical screening strategy for 3,4-methylenedioxymethamphetamine (MDMA), the regular psychoactive compound in ecstasy (XTC) pills. We have investigated the specific electrochemical profile of MDMA and its electro-oxidation mechanisms at disposable graphite screen-printed electrodes. We have proved that the formation of a radical cation and subsequent reactions are indeed responsible for the electrode surface passivation, as evidenced by using electron paramagnetic resonance spectroscopy and electrochemistry. Thereafter, pure cutting agents and MDMA as well as simulated binary mixtures of compounds with MDMA were subjected to square wave voltammetry at pH 7 to understand the characteristic electrochemical profile. An additional measurement at pH 12 was able to resolve false positives and negatives occurring at pH 7. Finally, validation of the screening strategy was done by measuring a set of ecstasy street samples. Overall, our proposed electrochemical screening strategy has been demonstrated for the rapid, sensitive, and selective detection of MDMA, resolving most of the false positives and negatives given by the traditional Marquis color tests, thus exhibiting remarkable promises for the on-site screening of MDMA.

Abstract: The structural and magnetic properties of LaMnO₃/LaFeO₃(LMO/LFO) heterostructures are characterized using a combination of scanning transmission electron microscopy, electron energy-loss spectroscopy, bulk magnetometry, and resonant x-ray reflectivity. Unlike the relatively abrupt interface when LMO is deposited on top of LFO, the interface with reversed growth order shows significant cation intermixing of Mn³⁺and Fe³⁺, spreading ∼8 unit cells across the interface. The asymmetric interfacial chemical profiles result in distinct magnetic properties. The bilayer with abrupt interface shows a single magnetic hysteresis loop with strongly enhanced coercivity, as compared to the LMO plain film. However, the bilayer with intermixed interface shows a step-like hysteresis loop, associated with the separate switching of the “clean” and intermixed LMO sublayers. Our study illustrates the key role of interfacial chemical profile in determining the functional properties of oxide heterostructures.

Abstract: Upgrading ethane with CO2 as a soft oxidant represents a desirable means of obtaining oxygenated hydrocarbons. This reaction is not thermodynamically feasible under mild conditions and has not been previously achieved as a one-step process. Nonthermal plasma was implemented as an alternative means of supplying energy to overcome activation barriers, leading to the production of alcohols, aldehydes, and acids as well as C1−C5+ hydrocarbons under ambient pressure, with a maximum total oxygenate selectivity of 12%. A plasma chemical kinetic computational model was developed and found to be in good agreement with the experimental trends. Results from this study illustrate the potential to use plasma for the direct synthesis of value-added alcohols, acids, and aldehydes from ethane and CO2 under mild conditions.

Abstract: The interface-dependent electronic, vibrational, piezoelectric, and optical properties of van der Waals heterobilayers, formed by buckled GeO (b-GeO) and Janus MoSO structures, are investigated by means of first-principles calculations. The electronic band dispersions show that O/Ge and S/O interface formations result in a type-II band alignment with direct and indirect band gaps, respectively. In contrast, O/O and S/Ge interfaces give rise to the formation of a type-I band alignment with an indirect band gap. By considering the Bethe-Salpeter equation (BSE) on top of G(0)W(0) approximation, it is shown that different interfaces can be distinguished from each other by means of the optical absorption spectra as a consequence of the band alignments. Additionally, the low- and high-frequency regimes of the Raman spectra are also different for each interface type. The alignment of the individual dipoles, which is interface-dependent, either weakens or strengthens the net dipole of the heterobilayers and results in tunable piezoelectric coefficients. The results indicate that the possible heterobilayers of b-GeO/MoSO asymmetric structures possess various electronic, optical, and piezoelectric properties arising from the different interface formations and can be distinguished by means of various spectroscopic techniques.

Abstract: Heterostructures composed of two-dimensional (2D) materials are already opening many new possibilities in such fields of technology as electronics and magnonics, but far more could be achieved if the number and diversity of 2D materials is increased. So far, only a few dozen 2D crystals have been extracted from materials that exhibit a layered phase in ambient conditions, omitting entirely the large number of layered materials that may exist in other temperatures and pressures. Here, we demonstrate how these structures can be stabilized in 2D van der Waals stacks under room temperature via growing them directly in graphene encapsulation by using graphene oxide as the template material. Specifically, we produce an ambient stable 2D structure of copper and iodine, a material that normally only occurs in layered form at elevated temperatures between 645 and 675 K. Our results establish a simple route to the production of more exotic phases of materials that would otherwise be difficult or impossible to stabilize for experiments in ambient.

Abstract: The differentiation between missing linker defects
and missing cluster defects in MOFs is difficult, thereby limiting the
ability to correlate materials properties to a specific type of defects.
Herein, we present a novel and easy synthesis strategy for the
creation of solely “missing cluster defects” by preparing mixed-metal
(Zn, Zr)-UiO-66 followed by a gentle acid wash to remove the Zn
nodes. The resulting material has the reo UiO-66 structure, typical
for well-defined missing cluster defects. The missing clusters are
thoroughly characterized, including low-pressure Ar-sorption, iDPCSTEM
at a low dose (1.5 pA), and XANES/EXAFS analysis. We
show that the missing cluster UiO-66 has a negligible number of missing linkers. We show the performance of the missing cluster
UiO-66 in CO2 sorption and heterogeneous catalysis.

Abstract: 3D characterization of assemblies of nanoparticles is of great importance to determine their structure-property connection. Such investigations become increasingly more challenging when the assemblies become larger and more compact. In this paper, we propose an optimized approach for electron tomography to minimize artefacts related to beam broadening in High Angle Annular Dark-Field Scanning Transmission Electron Microscopy mode. These artefacts are typically present at one side of the reconstructed 3D data set for thick nanoparticle assemblies. To overcome this problem, we propose a procedure in which two tomographic tilt series of the same sample are acquired. After acquiring the first series, the sample is flipped over 180o, and a second tilt series is acquired. By merging the two reconstructions, blurring in the reconstructed volume is minimized. Next, this approach is combined with an advanced three-dimensional reconstruction algorithm yielding quantitative structural information. Here, the approach is applied to a thick and compact assembly of spherical Au nanoparticles, but the methodology can we used to investigate a broad range of samples.

Abstract: Immune checkpoint blockade involves targeting immune
regulatory molecules with antibodies. Preclinically, complex multiantibody
regimes of both inhibitory and stimulatory targets are a promising
candidate for the next generation of immunotherapy. However, in this
setting, the antibody platform may be limited due to excessive toxicity
caused by off target effects as a result of systemic administration. RNA
can be used as an alternate to antibodies as it can both downregulate
immunosuppressive checkpoints (siRNA) or induce expression of
immunostimulatory checkpoints (mRNA). In this study, we demonstrate
that the combination of both siRNA and mRNA in a single
formulation can simultaneously knockdown and induce expression of
immune checkpoint targets, thereby reprogramming the tumor
microenvironment from immunosuppressive to immunostimulatory
phenotype. To achieve this, RNA constructs were synthesized and
formulated into stable nucleic acid lipid nanoparticles (SNALPs); the SNALPs produced were 140−150 nm in size with >80%
loading efficiency. SNALPs could transfect macrophages and B16F10 cells in vitro resulting in 75% knockdown of inhibitory
checkpoint (PDL1) expression and simultaneously express high levels of stimulatory checkpoint (OX40L) with minimal
toxicity. Intratumoral treatment with the proposed formulation resulted in statistically reduced tumor growth, a greater
density of CD4+ and CD8+ infiltrates in the tumor, and immune activation within tumor-draining lymph nodes. These data
suggest that a single RNA-based formulation can successfully reprogram multiple immune checkpoint interactions on a
cellular level. Such a candidate may be able to replace future immune checkpoint therapeutic regimes composed of both
stimulatory- and inhibitory-receptor-targeting antibodies.

Abstract: Cholesterol plays a crucial role in major cardiovascular and neurodegenerative diseases, including Alzheimer’s disease and rare genetic disorders showing altered cholesterol metabolism. Cyclodextrins (CDs) have shown promising therapeutic efficacy based on their capacity to sequester and mobilise cholesterol. However, the administration of monomeric CDs suffers from several drawbacks due to their lack of specificity and poor pharmacokinetics. We present core-shell superparamagnetic iron oxide nanoparticles (SPIONs) functionalised with CDs appended to poly (2-methyl-2-oxazoline) polymers grafted in a dense brush to the iron oxide core. The CD-decorated nanoparticles (CySPIONs) are designed so that the macrocycle is specifically cleaved off the nanoparticle’s shell at a slightly acidic pH. In the intended use, free monomeric CDs will then mobilise cholesterol out of the lysosome to the cytosol and beyond through the formation of an inclusion complex. Hence, its suitability as a therapeutic platform to remove cholesterol in the lysosomal compartment. Synthesis and full characterization of the polymer as well as of the core-shell SPION are presented. Cholesterol-binding activity is shown through an enzymatic assay.

Abstract: Dirac plasmons in a two-dimensional (2D) crystal are strongly affected by the dielectric properties of the environment, due to interaction of their electric field lines with the surrounding medium. Using graphene as a 2D reservoir of free carriers, one can engineer a material configuration that provides an anisotropic environment to the plasmons. In this work, we discuss the physical properties of Dirac plasmons in graphene surrounded by an arbitrary anisotropic dielectric and exemplify how h-BN-based heterostructures can be designed to bear the required anisotropic characteristics. We calculate how dielec-tric anisotropy impacts the spatial propagation of the plasmons and find that an anisotropy-induced plasmon mode emerges, together with a damping pathway, that stem from the out-of-plane off-diagonal elements in the dielectric tensor. Furthermore, we find that one can create hyperbolic plasmons by inher-iting the dielectric hyperbolicity of the designed material environment. Strong control over plasmon propagation patterns can be realized in a similar manner. Finally, we show that in this way one can also control the polarization of the light-matter excitations that constitute the plasmon. Taken together, our results promote the design of the dielectric environment as an effective path to tailor the plasmonic response of graphene on the nanoscopic level.

Abstract: Determining the three-dimensional (3D) atomic structure of nanoparticles (NPs) is critical to understand their structure-dependent properties. It is hereby important to perform such analyses under conditions relevant for the envisioned application. Here, we investigate the 3D structure of supported Au NPs at high temperature, which is of importance to understand their behavior during catalytic reactions. To overcome limitations related to conventional high-resolution electron tomography at high temperature, 3D characterization of NPs with atomic resolution has been performed by applying atom-counting using atomic resolution annular darkfield scanning transmission electron microscopy (ADF STEM) images followed by structural relaxation. However, at high temperatures, thermal displacements, which affect the ADF STEM intensities, should be taken into account. Moreover, it is very likely that the structure of a NP investigated at elevated temperature deviates from a ground state configuration, which is difficult to determine using purely computational energy minimization approaches. In this paper, we therefore propose an optimized approach using an iterative local minima search algorithm followed by molecular dynamics (MD) structural relaxation of candidate structures associated with each local minimum. In this manner, it becomes possible to investigate the 3D atomic structure of supported NPs, which may deviate from their ground state configuration.

Abstract: Dirac plasmons in graphene hybridize with phonons of transition metal dichalcogenides (TMDs) when the materials are combined in so-called van der Waals heterostructures (vdWh), thus forming surface plasmon-phonon polaritons (SPPPs). The extend to which these modes are coupled depends on the TMD composition and structure, but also on the plasmons' properties. By performing realistic simulations that account for the contribution of each layer of the vdWh separately, we calculate how the strength of plasmon-phonon coupling depends on the number and composition of TMD layers, on the graphene Fermi energy and the specific phonon mode. From this, we present a semiclassical theory that is capable of capturing all relevant characteristics of the SPPPs. We find that it is possible to realize both strong and ultra-strong coupling regimes by tuning graphene's Fermi energy and changing TMD layer number.

Abstract: Nitrogen oxides (NOx) and particulate matter (PM) currently are the main pollutants emitted by diesel engines. While there is a start in using hybrid and electric cars, ships will still be fueled by mineral oil products. In the quest to achieve zero-pollution and carbon-free shipping, alternative forms of energy carriers must be found to replace the commonly used mineral oil products. One of the possible alternative fuels is biodiesel. This paper explores the optimization of the composition of biodiesel in order to reduce the concentration of particulate matter and NOx in exhaust gases of a one-cylinder diesel generator.