Selective Growth Conditions Research Articles

Enrichment of mixed methanotrophic cultures producing polyhydroxyalkanoates (PHAs) from various environmental sources

Methanotrophic bacteria can use atmospheric methane (CH4) as a sole carbon source for the growth and production of polyhydroxyalkanoates (PHA). The development of CH4 bioconversion processes relies heavily on the selection of an efficient methanotrophic culture. This research assessed the effect of selected growth conditions, such as nitrogen sources on the enrichment of methanotrophic cultures from various environments for PHA accumulation. Nitrate-based medium favoured the culture growth and selection for PHA-producing methanotrophic cultures with Methylocystis sp. as a major genus and accumulation of up to 27 % polyhydroxybutyrate (PHB) in the biomass. Three PHB-producing cultures: enriched from waste activated sludge (AS), peat bog soil (PB) and landfill biocover soil (LB) were then tested for their ability to produce PHA copolymer at different CH4:O2 ratios. All enriched cultures were able to utilise valeric acid as a cosubstrate for the accumulation of PHA with a 3-hydroxyvaleric (3HV) fraction of 21–41 mol% depending on the inoculum source and CH4 concentration. The process performance of selected cultures was evaluated and compared to the culture of reference strain Methylocystis hirsuta DSM 18500. All mixed cultures irrespective of their inoculum source had similar levels of 3HV fraction in the PHA (38 ± 2 mol%). The highest poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) production was observed for AS culture at 10 % CH4 with an accumulation of 27 ± 3 % of dry cell weight (DCW), 3HV fraction of 39 ± 2 mol% and yield of 0.42 ± 0.02 g-PHA/g-substrate.

The role of native point defects and donor impurities in the electrical properties of ZnSb2O4: a hybrid density-functional study.

The ceramic material zinc antimony oxide ZnSb2O4 has promising electrical and magnetic properties, making it suitable for various applications such as electrochemical and energy storage. However, the effects of point defects and impurities on its electrical properties have never been revealed. Here, we employ hybrid density-functional calculations to investigate the energetics and electronic properties of native point defects and donor impurities in ZnSb2O4. The energetically favorable configurations of native point defects under selected growth conditions (O-rich and O-poor) are identified based on the calculated formation energies. The study finds no shallow donor and shallow acceptor defects with low formation energies. Still, the oxygen vacancy (VO) has the lowest formation energy among the donor-type defects under O-rich and O-poor conditions. However, it acts as a very deep acceptor, making it unlikely to provide free electron carriers to the conduction band. Moreover, electron carriers are likely to be compensated by the formation of zinc vacancies (VZn) and the zinc substituted for antimony (ZnSb), which behave as dominant acceptors. Our analysis of the charge neutrality conditions estimates that the Fermi level of undoped ZnSb2O4 would be pinned in a range that is 2.60 eV to 3.12 eV above the VBM for O-rich to O-poor growth conditions, respectively, suggesting that this material is semi-insulating. The possibility of enhancing free electron carriers by doping with Al, Ga, In, and F impurities is also investigated. Our results, however, indicate that high n-type conductivity is hindered by self-compensation in which the impurities additionally act as electron killers. Our results suggest that other impurity candidates and approaches may need to be considered to efficiently dope this material into n-type. Overall, this work paves the way for point defect engineering in this class of ternary oxides.

Influent carbon to phosphorus ratio drives the selection of PHA-storing organisms in a single CSTR

Enriching a biomass with a high fraction of polyhydroxyalkanoate-storing organisms (PHA-storers) represents an essential step in the production of PHAs (bioplastics) from municipal wastewater using mixed microbial cultures. A major challenge is however to create selective growth conditions that are favourable to PHA-storers. Our study thus investigates to what extent the influent COD to phosphorus (COD:P) ratio can be used as a tool for the robust selection of PHA-storers in a single continuous-flow stirred-tank reactor (CSTR). Therefore, we operated five CSTRs in parallel, fed with synthetic wastewater (50% acetate - 50% propionate) with different COD:P ratios (200−1000 gCOD gP−1), and performed a detailed analysis of the microbial communities over long-term (30−70 solid retention times). Our study demonstrates that efficient and robust selection of PHA-storers can be achieved in a single CSTR at high influent COD:P ratios. The selective advantage for PHA-storers increases with the influent COD:P ratio, but only if growth conditions remain limited by both C-substrate and P. In contrast, selection performance deteriorates when COD:P ratios are too high and growth conditions are limited by P only. At an optimal COD:P ratio of 800 gCOD gP−1, a stable microbial community consisting of >90% PHA-storers and dominated by Pannonibacter sp. was selected in the long-term. Finally, our results suggest that high COD:P ratios provide a selective advantage to microorganisms with low cellular P requirements, explaining why different PHA-storers (i.e., Xanthobacter sp. vs. Pannonibacter sp.) were selected depending on the influent COD:P ratio (i.e., 200 vs. 800 gCOD gP−1). Overall, our results provide relevant insights for the development of a new approach for selecting PHA-storers, based on the use of a single CSTR and control of the influent COD:P ratio.

MALDI-TOF MS insight into the biodiversity of Staka, the artisanal Cretan soured cream

Staka is a naturally fermented cream produced from sheep or mixtures of sheep and goat milk in the island of Crete, Greece. This work is the first report on Staka cream microbiota. Initially, counts of various bacterial groups were enumerated using selective media and growth conditions. All isolates (101) were subjected to matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) analysis; the spectra obtained were compared with those of an in-house reference database. While 70 isolates were considered identified at the species level, the remaining 31 were not, probably due to a lack of, or an insufficient number of, reference spectra in the MALDI-TOF MS database. Strains representative of the observed diversity among the unidentified MALDI-TOF MS spectra were therefore subjected to pheS and 16S rRNA gene sequencing analysis for further identification. The identification results revealed the presence of Lactobacillus spp., Enterococcus spp., Streptococcus thermophilus and Aerococcus viridans.

Molecular alignment on graphene surface determines transport properties of graphene/organic semiconductor transistors

Graphene field-effect transistor structures were used to investigate the role of molecular alignment on charge transport properties of heterostructures comprising a single-layer graphene and variable thickness of N,N′-bis(n-octyl)-(1,7&1,6)-dicyanoperylene-3,4:9,10-bisdicarboximide (PDI8-CN2) - an n-type organic semiconductor. Our atomic force microscopy data show that under selected growth conditions PDI8-CN2 grows in a layer-by-layer fashion up to a second monolayer. The first layer comprises flat-lying molecules, whereas the molecules in the second layer orient themselves in an upright orientation. Transconductance measurements show that the flat-lying molecules have little effect on the position of the Fermi level in graphene. Upright oriented molecules in the second layer instead, have a strong effect as to neutralize native p -type doping of graphene and cause a shift of charge-neutrality level towards the Dirac point. We interpret such behavior in terms of different orientation of the surface dipole on layers with different molecular orientations. At the same time the overall mobility of the charge carriers reaches values exceeding 3000 cm 2 /Vs. • PDI8-CN2 grows in a layer-by-layer mode up to a second mono-layer on graphene. • Molecules in the first layer lie flat in the second are upright on the surface. • Flat-lying molecules have little effect on the position of the Fermi level in graphene. • Upright oriented molecules cause a shift of charge-neutrality level towards the Dirac point.

The development of species-specific antisense peptide nucleic acid method for the treatment and detection of viable Salmonella

Genotypic based detection methods using specific target sites in the pathogen genome can complement phenotypic identification. We report the development of species-specific antisense peptide nucleic acid (PNA) combined with selective and differential enrichment growth conditions for Salmonella treatment and detection. An antisense PNA oligomer targeting the Salmonella ftsZ gene and conjugated with a cell-penetrating peptide ((KFF)3K) was exploited to probe bacteria cultured in three different growth media (Muller Hinton broth (MHB), Rappaport-Vassiliadis Soya Peptone Broth (RVS, Oxoid), and in-house modified Rappaport-Vassiliadis Soya Peptone Broths (mRVSs). Also, water and milk artificially contaminated with bacteria were probed. Antisense PNA provided detectable changes in Salmonella growth and morphology in all media and artificially contaminated matrices except RVS. Salmonella was detected as elongated cells. On the contrary, treated Escherichia coli did not elongate, providing evidence of differentiation and selectivity for Salmonella. Similarly, Salmonella probed with mismatched PNAs did not elongate. Antisense oligomers targeted ftsZ mRNA in combination with selective growth conditions can provide a detection strategy for viable Salmonella in a single reaction, and act as a potential tool for bacteria detection in real food and environmental samples.

P0041CHARACTERISTICS OF URINE-DERIVED RENAL EPITHELIAL CELLS (UREC) FROM CHILDREN WITH POLYCYSTIC KIDNEY DISEASE (PKD)

Abstract Background and Aims In hereditary PKD, epithelial cell defects are mostly caused by mutation of proteins of the cilia-centrosome complex. Use of primary cells from patients allows to study specific cell characteristics and altered activation of signal pathways in epithelial cell function-related culture models. In this ex vivo approach, comparison of cell properties is based on defined genetic origin and can be related to kidney function at the time of UREC collection, revealing consequences of genetic disposition and kidney-stress related changes on cell function. Method The study considers patients with genetically confirmed causes of PKD, autosomal recessive polycystic kidney disease (ARPKD), nephronophtisis (NPH), Bardet-Biedl syndrome (BBS), and age-matched controls with normal kidney function. UREC are grown from cellular urine sediment using selective growth conditions. Primary cells are cultured up-to 21 days (passages 2 & 3) and tested with respect to their proliferation, tubular origin and epithelial properties in 2D/3D culture conditions. To allow pathway analysis and improve control conditions, immortalized UREC lines are also included. Results UREC preparations of cohorts from ARPKD, NPH, and BBS patients, and controls were studied quantitatively to determine specific epithelial cell properties. Considering basic characteristics of each primary culture including cell morphology, expression of epithelial markers, and formation of cell-cell adhesions, the potential of UREC cells to polarize and generate liquid-filled epithelial spheroids was measured. The capacity of lumen formation in 3D culture strongly varies among individual cell preparations and appears to reflect the genetic origin of UREC cells, whereas no correlation to (remaining) kidney function (eGFR) is observed. Conclusion Determining specific, quantitative UREC cell properties related to genetics and kidney function, we expect to gain a better mechanistic understanding of cellular and renal epithelial defects in PKD patients. Ex vivo analysis based on UREC cells may provide options for testing of personalized pharmaceutical intervention.

Ballistic InSb Nanowires and Networks via Metal-Sown Selective Area Growth.

Selective area growth is a promising technique to realize semiconductor-superconductor hybrid nanowire networks, potentially hosting topologically protected Majorana-based qubits. In some cases, however, such as the molecular beam epitaxy of InSb on InP or GaAs substrates, nucleation and selective growth conditions do not necessarily overlap. To overcome this challenge, we propose a metal-sown selective area growth (MS SAG) technique, which allows decoupling selective deposition and nucleation growth conditions by temporarily isolating these stages. It consists of three steps: (i) selective deposition of In droplets only inside the mask openings at relatively high temperatures favoring selectivity, (ii) nucleation of InSb under Sb flux from In droplets, which act as a reservoir of group III adatoms, done at relatively low temperatures, favoring nucleation of InSb, and (iii) homoepitaxy of InSb on top of the formed nucleation layer under a simultaneous supply of In and Sb fluxes at conditions favoring selectivity and high crystal quality. We demonstrate that complex InSb nanowire networks of high crystal and electrical quality can be achieved this way. We extract mobility values of 10 000-25 000 cm2 V-1 s-1 consistently from field-effect and Hall mobility measurements across single nanowire segments as well as wires with junctions. Moreover, we demonstrate ballistic transport in a 440 nm long channel in a single nanowire under a magnetic field below 1 T. We also extract a phase-coherent length of ∼8 μm at 50 mK in mesoscopic rings.

Aluminum Interdiffusion into LiCoO2 Using Atomic Layer Deposition for High Rate Lithium Ion Batteries

Here, as with previous work, atomic layer deposition (ALD) has been used to deposit Al2O3 on positive electrode active materials, LiCoO2, to create a protective barrier layer, suppress the high potential phase transition, and thus reduce the subsequent Co dissolution. However, in this study it was found that it also resulted in the reduction of the charge transfer resistance at the positive electrode–electrolyte interface, thus enhancing the performance of the battery. Energy-dispersive X-ray spectroscopy, in conjunction with transmission electron microscopy, shows that a discrete Al2O3 shell was not formed under the selected growth conditions and that the Al diffused into the bulk LiCoO2. The resulting active oxide material, which was significantly thicker than the nominally ALD growth rate would predict, is proposed to be of the form LiCoO2:Al with amorphous and crystalline regions depending on the Al content. The cells consisting of the modified electrodes were found to have good cycling stability and ...

Abstract P6-05-01: Low BRCA2 levels cause epigenetic activation of growth adaptive pathways without inducing recurrent genomic mutations

Abstract The development of therapeutics to prevent cancer onset is hindered by a lack of robust cell systems to study the earliest steps of malignant transformation. Significant barriers to studying cancer-initiating events include intrinsic cellular pathways to prevent cell proliferation in the setting of activating oncogenes or genomic instability. To circumvent this limitation, we studied in vitro transient depletion of breast cancer tumor suppressor genes followed by selective growth conditions to enrich for de novo mutations or stable epigenetic alterations that can confer a growth advantage to non-transformed breast epithelial cells. We report that transient BRCA2 depletion, but not depletion of other breast cancer genes, leads to a selective growth advantage in EGF-free media. This is due to a failure of BRCA2 inactivated cells to enact a mesenchymal-to-epithelial transition upon withdrawal of EGF. Genomic profiling and biochemical approaches indicate that transient loss of BRCA2 induces chromatin remodeling in concert with NF-κB signaling and histone H2B deacetylation to repress genes associated with the epithelial state. Notably, this process did not appear to require recurrent driver mutations, nor DNA methylation changes, but was dependent on ATR signaling. Overall, our work suggests that transiently low BRCA2 levels are sufficient to induce aberrant cell proliferation under certain conditions and that targeting epigenetic modifiers may be an approach to prevent BRCA2-induced malignancy. Citation Format: Gruber JJ, Snyder M. Low BRCA2 levels cause epigenetic activation of growth adaptive pathways without inducing recurrent genomic mutations [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-05-01.

Broth versus Surface-Grown Cells: Differential Regulation of RsmY/Z Small RNAs in Pseudomonas aeruginosa by the Gac/HptB System.

Two-component systems are capable of profoundly affecting genetic regulation in bacteria by detecting environmental stimuli, allowing them to quickly adapt. In Pseudomonas aeruginosa, the small RNAs (sRNAs) RsmY and RsmZ are under the control of the GacS/A system. They have been described as ones of the major key players in the control of planktonic and surface-associated behaviors. Genetic regulation by these sRNAs is achieved by the titration of the negative post-transcriptional regulator RsmA which affects the expression of over 500 genes. There is increasing evidence pinpointing the importance of RsmY and RsmZ in the planktonic-sessile P. aeruginosa lifestyles switch control. Using swarming motility as a model, we show here that these sRNA are differentially regulated depending on the selected growth conditions (i.e., planktonic versus surface grown-cells). Also, we report that opposite to planktonically grown cells, rsmZ regulation does not implicate the response regulator GacA in swarming cells. Furthermore, we present data indicating that RsmY/Z expression influence swarming motility via the protein HptB which acts as a negative regulator of these sRNAs and that they do not strictly converge to RsmA as previously reported.

(Invited) Fabrication of Ge Waveguides by Epitaxial Lateral Overgrowth toward Monolithic Integration of Light Sources

Ge waveguides (WGs) were fabricated on an SiO2 layer by combining epitaxial lateral overgrowth, chemical mechanical polishing (CMP), and reactive ion etching (RIE) of a Ge layer selectively grown on SiO2 patterns using low pressure chemical vapor deposition. Selectivity was promoted by increasing growth temperature; length of the epitaxial lateral overgrown Ge layer reached 5 μm on the SiO2 layer under conditions of optimal selective growth at a temperature of 750°C. The Ge layers were planarized by using CMP down to a thickness of 1 μm, and then Ge WGs as active regions for light emitting devices were formed by using RIE on the planarized Ge layers. After defective regions around the Ge/Si interface were removed, four-times-higher photoluminescence was obtained from the Ge WGs compared with one that contained the Ge/Si interface. These results indicate that this combined technique efficiently improved the performance of Ge light-emitting devices.

Transcriptomic Profiling Discloses Molecular and Cellular Events Related to Neuronal Differentiation in SH-SY5Y Neuroblastoma Cells.

Human SH-SY5Y neuroblastoma cells are widely utilized in in vitro studies to dissect out pathogenetic mechanisms of neurodegenerative disorders. These cells are considered as neuronal precursors and differentiate into more mature neuronal phenotypes under selected growth conditions. In this study, in order to decipher the pathways and cellular processes underlying neuroblastoma cell differentiation in vitro, we performed systematic transcriptomic (RNA-seq) and bioinformatic analysis of SH-SY5Y cells differentiated according to a two-step paradigm: retinoic acid treatment followed by enriched neurobasal medium. Categorization of 1989 differentially expressed genes (DEGs) identified in differentiated cells functionally linked them to changes in cell morphology including remodelling of plasma membrane and cytoskeleton, and neuritogenesis. Seventy-three DEGs were assigned to axonal guidance signalling pathway, and the expression of selected gene products such as neurotrophin receptors, the functionally related SLITRK6, and semaphorins, was validated by immunoblotting. Along with these findings, the differentiated cells exhibited an ability to elongate longer axonal process as assessed by the neuronal cytoskeletal markers biochemical characterization and morphometric evaluation. Recognition of molecular events occurring in differentiated SH-SY5Y cells is critical to accurately interpret the cellular responses to specific stimuli in studies on disease pathogenesis.

Crystallinity improvements of Ge waveguides fabricated by epitaxial lateral overgrowth

Ge waveguides (WGs) were successfully fabricated on an SiO2 layer by combining epitaxial lateral overgrowth, chemical mechanical polishing (CMP), and reactive ion etching (RIE) of a Ge layer selectively grown on SiO2 patterns using low-pressure chemical vapor deposition. Selectivity was promoted by increasing the growth temperature; the length of the epitaxial lateral overgrown Ge layer reached 5 µm on the SiO2 layer under conditions of optimal selective growth at a temperature of 750 °C. The Ge layers were planarized using CMP down to a thickness of 1 µm, and then Ge WGs as active regions for light emitting devices were formed by using RIE on the planarized Ge layers. After defective regions around the Ge/Si interface were removed, 4-times-higher photoluminescence was obtained from the Ge WGs compared with one that contained the Ge/Si interface. These results indicate that this combined technique efficiently improved the performance of Ge light-emitting devices.

Influence of oxide buffer layers on the growth of carbon nanotube arrays on carbon substrates

Controllable growth of carbon nanotube (CNT) arrays on carbon substrates requires an oxide buffer layer material such as Al2O3 and SiO2. This research analyzes the influence of these buffer layers on a model carbon substrate composed of pyrolyzed carbon film on flat silicon. Electron microscopy was used to analyze nanocatalyst morphology, particle density, CNT nucleation rate, and CNT morphology for selected growth conditions. It was observed that nanotubes grown on Al2O3 buffer layers had the fastest CNT nucleation rates and more uniform tube diameters, with residual nanocatalyst particles having elongated shapes. In contrast, CNTs formed on SiO2 buffer layers nucleated slower and had more variation in tube diameters, while the nanocatalyst particles remained spherical. Comparisons among SiO2 buffer layers deposited using three different techniques—atomic layer deposition, microwave plasma enhanced chemical vapor deposition and thermal oxidation—indicated that surface roughness plays an important role. Silica layers with the highest roughness had the highest catalytic particle density and tallest carpet height for identical growth conditions. These results provide new insight into the importance of buffer layer chemistry and morphology on growth and controllability of CNT arrays.

Epitaxial growth of (111)-oriented ZrxTi1−xN thin films on c-plane Al2O3 substrates

A systematic study is presented on the effects of process parameters of S-gun configured DC magnetron sputtered ZrN thin films on c-plane Al2O3 substrates. Using a quartz crystal microbalance the deposition rate of ZrN is investigated as a function of Ar and N2 flow rates, target power, chamber pressure and gas injection position in the chamber. Selected growth conditions for ZrN show the interrelation of growth parameters on film orientation and crystallinity. (111) oriented ZrN thin films exhibit X-ray diffraction rocking curve FWHM as low as 0.36°. Additionally, (111) oriented ternary ZrxTi1−xN thin films (0≤x≤1) are also deposited on c-plane Al2O3 substrates. High resolution X-ray diffraction characterization shows that ZrxTi1−xN (x=0, 0.64, 0.80, 0.93, 1) layers exhibit rocking curve FWHM values of 0.0045–0.006° for the (111) reflection, indicating highly crystalline thin films. Atomic force microscopy characterizations show ZrxTi1−xN thin films with a surface roughness between 1.2nm and 2.9nm.

A Robust Genetic System for Producing Heterodimeric Native and Mutant Cytochrome bc1

The ubihydroquinone:cytochrome c oxidoreductase, or cytochrome bc1, is central to the production of ATP by oxidative phosphorylation and photophosphorylation in many organisms. Its three-dimensional structure depicts it as a homodimer with each monomer composed of the Fe-S protein, cytochrome b, and cytochrome c1 subunits. Recent genetic approaches successfully produced heterodimeric variants of this enzyme, providing insights into its mechanism of function. However, these experimental setups are inherently prone to genetic rearrangements as they carry repeated copies of cytochrome bc1 structural genes. Duplications present on a single replicon (one-plasmid system) or a double replicon (two-plasmid system) could yield heterogeneous populations via homologous recombination or other genetic events at different frequencies, especially under selective growth conditions. In this work, we assessed the origins and frequencies of genetic variations encountered in these systems and describe an improved variant of the two-plasmid system. We found that use of a recombination-deficient background (recA) minimizes spontaneous formation of co-integrant plasmids and renders the homologous recombination within the cytochrome b gene copies inconsequential. On the basis of the data, we conclude that both the newly improved RecA-deficient and the previously used RecA-proficient two-plasmid systems reliably produce native and mutant heterodimeric cytochrome bc1 variants. The two-plasmid system developed here might contribute to the study of "mitochondrial heteroplasmy"-like heterogeneous states in model bacteria (e.g., Rhodobacter species) suitable for bioenergetics studies. In the following paper (DOI 10.1021/bi400561e), we describe the use of the two-plasmid system to produce and characterize, in membranes and in purified states, an active heterodimeric cytochrome bc1 variant with unusual intermonomer electron transfer properties.

A look inside epitaxial cobalt-on-fluorite nanoparticles with three-dimensional reciprocal space mapping using GIXD, RHEED and GISAXS

In this work epitaxial growth of cobalt on CaF2(111), (110) and (001) surfaces has been extensively studied. It has been shown by atomic force microscopy that at selected growth conditions stand-alone faceted Co nanoparticles are formed on a fluorite surface. Grazing-incidence X-ray diffraction (GIXD) and reflection high-energy electron diffraction (RHEED) studies have revealed that the particles crystallize in the face-centered cubic lattice structure otherwise non-achievable in bulk cobalt under normal conditions. The particles were found to inherit lattice orientation from the underlying CaF2 layer. Three-dimensional reciprocal space mapping carried out using X-ray and electron diffraction has revealed that there exist long bright 〈111〉 streaks passing through the cobalt Bragg reflections. These streaks are attributed to stacking faults formed in the crystal lattice of larger islands upon coalescence of independently nucleated smaller islands. Distinguished from the stacking fault streaks, crystal truncation rods perpendicular to the {111} and {001} particle facets have been observed. Finally, grazing-incidence small-angle X-ray scattering (GISAXS) has been applied to decouple the shape-related scattering from that induced by the crystal lattice defects. Particle faceting has been verified by modeling the GISAXS patterns. The work demonstrates the importance of three-dimensional reciprocal space mapping in the study of epitaxial nanoparticles.

Direct-Write Atomic Layer Deposition of High-Quality Pt Nanostructures: Selective Growth Conditions and Seed Layer Requirements

Electron beam-induced deposition (EBID) enables the direct-write patterning of metallic structures with sub-10 nm lateral resolution without the use of resist films or etching/lift-off steps but generally leads to material of poor quality and suffers from a low throughput. These shortcomings were mitigated in recent work by combining EBID with atomic layer deposition (ALD). This direct-write ALD technique comprises the patterning of a thin seed layer by EBID followed by selective thickening of the pattern by ALD. In this work, the throughput of direct-write ALD was drastically improved based on new insights into how the ALD growth initiates on EBID material, and in addition, the conditions for selective ALD growth were identified. The required electron dose was reduced by 2 orders of magnitude to ∼11 pC/μm2 by exposing the EBID seed layers to O2 in the ALD reactor just before the ALD building step. This improvement of the technique allows for nanopatterning with a throughput comparable to electron beam li...

Self-Assembled Nanostructures as Templates for the Integration of Nanoparticles in Oxide Surfaces

Under properly selected growth conditions, complex oxide thin films might exhibit a tendency towards selforganization allowing obtaining regular arrays of three-dimensional nanostructures. This behavior, together with their rich physics, offers enormous potential for the implementation of new nanodevices. Among complex oxides, manganese perovskites exhibiting colossal magnetoresistance and half-metallic character have emerged as promising candidates for the implementation of new spintronic devices. Manganite thin films are often elastically strained, due to film-substrate lattice mismatch, and this lattice strain can, in some cases, select preferential growth modes leading to the appearance of different self-organized nanostructured morphologies. It is shown that under properly chosen growth conditions long range ordered arrays of nanoobjects, running along the steps direction defined by the miscut angle of the underlying substrate, can be obtained in highly epitaxial La2/3Sr 1/3MnO3 (LSMO) thin films. These results suggest that self-organization process is directly guided by the topological features of the underlying substrate and highlight the relevance of growth kinetic effects. The use of those nanoobjects arrays as nanostencils for fabricating arrays of nanoparticles is also explored.