E-beam fluorinated CVD graphene:XPS study on stability and NHadsorption doping effect.

Graphene exhibits promise in gas detection applications despite its limited selectivity. Functionalization with fluorine atoms offers a potential solution to enhance selectivity, particularly towards ammonia (NH+) molecules. This article presents a study on electron-beam fluorinated graphene (FG) and its integration into gas sensor platforms.

Single scan STEM-EMCD in 3-beam orientation using a quadruple aperture.

The need to acquire multiple angle-resolved electron energy loss spectra (EELS) is one of the several critical challenges associated with electron magnetic circular dichroism (EMCD) experiments. If the experiments are performed by scanning a nanometer to atomic-sized electron probe on a specific region of a sample, the precision of the local magnetic information extracted from such data highly depends on the accuracy of the spatial registration between multiple scans. For an EMCD experiment in a 3-beam orientation, this means that the same specimen area must be scanned four times while keeping all the experimental conditions same.

Towards ballistic transport CVD graphene by controlled removal of polymer residues.

Polymer-assisted wet transfer of chemical vapor deposited (CVD) graphene has achieved great success towards the true potential for large-scale electronic applications, while the lack of an efficient polymer removal method has been regarded as a crucial factor for realizing high carrier mobility in graphene devices. Hereby, we report an efficient and facile method to clean polymer residues on graphene surface by merely employing solvent mixture of isopropanol (IPA) and water (HO). Raman spectroscopy shows an intact crystal structure of graphene after treatment, and the x-ray photoelectron spectroscopy indicates a significant decrease in the C-O and C=O bond signals, which is mainly attributed to the removal of polymer residues and further confirmed by subsequent atomic force microscopy analysis.

Fabrication of BP2T functionalized graphene non-covalent π-π stacking interactions for enhanced ammonia detection.

Graphene has stimulated great enthusiasm in a variety of fields, while its chemically inert surface still remains challenging for functionalization towards various applications. Herein, we report an approach to fabricate non-covalently functionalized graphene by employing π-π stacking interactions, which has potentialities for enhanced ammonia detection. 5,5'-Di(4-biphenylyl)-2,2'-bithiophene (BP2T) molecules are used in our work for the non-covalent functionalization through strong π-π interactions of aromatic structures with graphene, and systematic investigations by employing various spectroscopic and microscopic characterization methods confirm the successful non-covalent attachment of the BP2T on the top of graphene.

Analysis of molecular ligand functionalization process in nano-molecular electronic devices containing densely packed nano-particle functionalization shells.

Molecular electronic devices based on few and single-molecules have the advantage that the electronic signature of the device is directly dependent on the electronic structure of the molecules as well as of the electrode-molecule junction. In this work, we use a two-step approach to synthesise functionalized nanomolecular electronic devices (nanoMoED). In first step we apply an organic solvent-based gold nanoparticle (AuNP) synthesis method to form either a 1-dodecanethiol or a mixed 1-dodecanethiol/-tetraphenyl ether substituted 1-dodecanethiol ligand shell.

The Influence of Residuals Combining Temperature and Reaction Time on Calcium Phosphate Transformation in a Precipitation Process.

Precipitation is one of the most common processes to synthesize hydroxyapatite, which is the human body's mineral forming bone and teeth, and the golden bioceramic material for bone repair. Generally, the washing step is important in the precipitation method to remove the residuals in solution and to stabilize the phase transformation. However, the influence of residuals in combination with the reaction temperature and time, on calcium phosphate formation, is not well studied.

Electron-Beam-Induced Fluorination Cycle for Long-Term Preservation of Graphene under Ambient Conditions.

The aging in air inevitably results in the accumulation of airborne hydrocarbon contaminations on a graphene surface, which causes considerable difficulties in the subsequent application of graphene. Herein, we report an electron-beam-activated fluorination/defluorination cycle for achieving a long-term preservation of CVD graphene. After experiencing such cycle, the accumulation of airborne hydrocarbon on the graphene surfaces is strongly reduced, and the initial chemical status of graphene can be restored, which is confirmed by employing atomic force microscopy and X-ray photoelectron microscopy.

Photoluminescent Semiconducting Graphene Nanoribbons via Longitudinally Unzipping Single-Walled Carbon Nanotubes.

The lack of a sizeable band gap has so far prevented graphene from building effective electronic and optoelectronic devices despite its numerous exceptional properties. Intensive theoretical research reveals that a band gap larger than 1 eV can only be achieved in sub-3 nm wide graphene nanoribbons (GNRs), but real fabrication of such ultranarrow GNRs still remains a critical challenge. Herein, we demonstrate an approach for the synthesis of ultranarrow and photoluminescent semiconducting GNRs by longitudinally unzipping single-walled carbon nanotubes.

Mechanistic Insights into the Role of the Bis(trifluoromethanesulfonyl)imide Ion in Coevaporated p-i-n Perovskite Solar Cells.

Hybrid lead halide perovskites have reached comparable efficiencies to state-of-the-art silicon solar cell technologies. However, a remaining key challenge toward commercialization is the resolution of the perovskite device instability. In this work, we identify for the first time the mobile nature of bis(trifluoromethanesulfonyl)imide (TFSI), a typical anion extensively employed in p-type dopants for 2,2'7,7'-tetrakis(,-di--methoxyphenylamine)-9,9'spirofluorene (spiro-OMeTAD).

Biodegradation of graphdiyne oxide in classically activated (M1) macrophages modulates cytokine production.

Graphdiyne oxide (GDYO) is a carbon-based nanomaterial possessing sp and sp-hybridized carbon atoms with many promising applications. However, its biocompatibility and potential biodegradability remain poorly understood. Using human primary monocyte-derived macrophages as a model we show here that GDYO elicited little or no cytotoxicity toward classically activated (M1) and alternatively activated (M2) macrophages.

Tuneable exchange-spring stiffness in amorphous magnetic trilayer structures.

We investigate the magnetic properties of amorphous SmCo/Co(AlZr)/Co(AlZr)exchange-spring magnet trilayers. The magnetically soft Co(AlZr)layer is coupled to the magnetically hard SmColayer through the weakly magnetic low-Co(AlZr)spacer layer. The strength of the coupling can be controlled with temperature and the coupling persists above the intrinsicof the spacer layer due to a long-range magnetic proximity effect.

Influence of the Rear Interface on Composition and Photoluminescence Yield of CZTSSe Absorbers: A Case for an AlO Intermediate Layer.

The rear interface of kesterite absorbers with Mo back contact represents one of the possible sources of nonradiative voltage losses (Δ) because of the reported decomposition reactions, an uncontrolled growth of MoSe, or a nonoptimal electrical contact with high recombination. Several intermediate layers (IL), such as MoO, TiN, and ZnO, have been tested to mitigate these issues, and efficiency improvements have been reported. However, the introduction of IL also triggers other effects such as changes in alkali diffusion, altered morphology, and modifications in the absorber composition, all factors that can also influence Δ.

Simultaneous mapping of EMCD signals and crystal orientations in a transmission electron microscope.

When magnetic properties are analysed in a transmission electron microscope using the technique of electron magnetic circular dichroism (EMCD), one of the critical parameters is the sample orientation. Since small orientation changes can have a strong impact on the measurement of the EMCD signal and such measurements need two separate measurements of conjugate EELS spectra, it is experimentally non-trivial to measure the EMCD signal as a function of sample orientation. Here, we have developed a methodology to simultaneously map the quantitative EMCD signals and the local orientation of the crystal.

The impact of number of repeats N on the interlayer exchange in [Formula: see text](001) superlattices.

The strength of the interlayer exchange coupling in [Fe/MgO][Formula: see text](001) superlattices with 2 ≤ N ≤ 10 depends on the number of bilayer repeats (N). The exchange coupling is antiferromagnetic for all the investigated thicknesses while being nine times larger in a sample with N = 4 as compared to N = 2. The sequence of the magnetic switching in two of the samples (N = 4, N = 8) is determined using polarized neutron reflectometry.

Nitric oxide-dependent biodegradation of graphene oxide reduces inflammation in the gastrointestinal tract.

Understanding the biological fate of graphene-based materials such as graphene oxide (GO) is crucial to assess adverse effects following intentional or inadvertent exposure. Here we provide first evidence of biodegradation of GO in the gastrointestinal tract using zebrafish as a model. Raman mapping was deployed to assess biodegradation.

Tailoring ultra-fast charge transfer in MoS.

Charge transfer dynamics are of importance in functional materials used in devices ranging from transistors to photovoltaics. The understanding of charge transfer in particular of how fast electrons tunnel away from an excited state and where they end up, is necessary to tailor materials used in devices. We have investigated charge transfer dynamics in different forms of the layered two-dimensional material molybdenum disulphide (MoS2, in single crystal, nanocrystalline particles and crystallites in a reduced graphene oxide network) using core-hole clock spectroscopy.

Nanoparticle Bridges for Studying Electrical Properties of Organic Molecules and Gas Sensor Applications.

Molecules have high potential for novel applications as building blocks for electronic devices such as sensors due to the versatility of their electronic properties. Their use in devices offers a great potential for further miniaturization of electronic devices. We describe a method where nanoparticles functionalized with short-chain organic molecules are used to build a molecular electronics device (nanoMoED) sensor for studying electrical properties of organic molecules.

Nanomolecular electronic devices based on AuNP molecule nanoelectrodes using molecular place-exchange process.

The implementation of electronics applications based on molecular electronics devices is hampered by the difficulty of placing a single or a few molecules with application-specific electronic properties in between metallic nanocontacts. Here, we present a novel method to fabricate 20 nm sized nanomolecular electronic devices (nanoMoED) using a molecular place-exchange process of nonconductive short alkyl thiolates with various short chain conductive oligomers. After the successful place-exchange with short-chain conjugated oligomers in the nanoMoED devices, a change in device resistance of up to four orders of magnitude for 4,4'-biphenyldithiol (BPDT), and up to three orders of magnitude for oligo phenylene-ethynylene (OPE), were observed.

Comment on "Quantum interference effects in biphenyl dithiol for gas detection" by J. Prasongkit and A. R. Rocha, , 2016, , 59299-59304.

The paper [Prasongkit , , 2016, , 59299] by Prasongkit and Rocha calculates the binding energy of gas molecules attached to 1-8-biphenyl-dithiol (BPDT) molecules. We find from our calculations, that the binding energies calculated for the NO molecules are too low, most likely due to lacking optimization of the site at which the gas molecule binds to the BPDT. Though not shown explicitly here, the same statement might apply to the other gas molecules used in this paper.

The Effect of Coating Density on Functional Properties of SiN Coated Implants.

Ceramic coatings may be applied onto metallic components of joint replacements for improved wear and corrosion resistance as well as enhanced biocompatibility, especially for metal-sensitive patients. Silicon nitride (SiN) coatings have recently been developed for this purpose. To achieve a high coating density, necessary to secure a long-term performance, is however challenging, especially for sputter deposited SiN coatings, since these coatings are insulating.

Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries.

To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films.

3D analysis of human islet amyloid polypeptide crystalline structures in Drosophila melanogaster.

Expression of the Alzheimer's disease associated polypeptide Aβ42 and the human polypeptide hormon islet amyloid polypeptide (hIAPP) and the prohormone precursor (hproIAPP) in neurons of Drosophila melanogaster leads to the formation of protein aggregates in the fat body tissue surrounding the brain. We determined the structure of these membrane-encircled protein aggregates using transmission electron microscopy (TEM) and observed the dissolution of protein aggregates after starvation. Electron tomography (ET) as an extension of transmission electron microscopy revealed that these aggregates were comprised of granular subunits having a diameter of 20 nm aligned into highly ordered structures in all three dimensions.

A sub 20 nm metal-conjugated molecule junction acting as a nitrogen dioxide sensor.

The interaction of a gas molecule with a sensing material causes the highest change in the electronic structure of the latter, when this material consists of only a few atoms. If the sensing material consists of a short, conductive molecule, the sensing action can be furthermore probed by connecting such molecules to nanoelectrodes. Here, we report that NO2 molecules that adhere to 4,4'-biphenyldithiol (BPDT) bound to Au surfaces lead to a change of the electrical transmission of the BPDT.

Luminescent CeO:Eu nanocrystals for robust in situ HO real-time detection in bacterial cell cultures.

Hydrogen peroxide (HO) quantification in biomedicine is valuable as inflammation biomarker but also in assays employing enzymes that generate or consume HO linked to a specific biomarker. Optical HO detection is typically performed through peroxidase-coupled reactions utilizing organic dyes that suffer, however, from poor stability/reproducibility and also cannot be employed in situ in dynamic complex cell cultures to monitor HO levels in real-time. Here, we utilize enzyme-mimetic CeO nanocrystals that are sensitive to HO and study the effect of HO presence on their electronic and luminescent properties.

MicroRNA detection based on duplex-specific nuclease-assisted target recycling and gold nanoparticle/graphene oxide nanocomposite-mediated electrocatalytic amplification.

DNA technology based bio-responsive nanomaterials have been widely studied as promising tools for biomedical applications. Gold nanoparticles (AuNPs) and graphene oxide (GO) sheets are representative zero- and two-dimensional nanomaterials that have long been combined with DNA technology for point-of-care diagnostics. Herein, a cascade amplification system based on duplex-specific nuclease (DSN)-assisted target recycling and electrocatalytic water-splitting is demonstrated for the detection of microRNA.