Thin films of the superconductor YBa2Cu3O7−δ (YBCO) were modified by low-energy light-ion irradiation employing collimated or focused He+ beams, and the long-term stability of irradiation-induced defects was investigated. For films irradiated with collimated beams, the resistance was measured in situ during and after irradiation and analyzed using a phenomenological model. The formation and stability of irradiation-induced defects are highly influenced by temperature. Thermal annealing experiments conducted in an Ar atmosphere at various temperatures demonstrated a decrease in resistivity and allowed us to determine diffusion coefficients and the activation energy ΔE=(0.31±0.03) eV for diffusive oxygen rearrangement within the YBCO unit cell basal plane. Additionally, thin YBCO films, nanostructured by focused He+-beam irradiation into vortex pinning arrays, displayed significant commensurability effects in magnetic fields. Despite the strong modulation of defect densities in these pinning arrays, oxygen diffusion during room-temperature annealing over almost six years did not compromise the signatures of vortex matching, which remained precisely at their magnetic fields predicted by the pattern geometry. Moreover, the critical current increased substantially within the entire magnetic field range after long-term storage in dry air. These findings underscore the potential of ion irradiation in tailoring the superconducting properties of thin YBCO films.

We report on nanopatterned YBa2Cu3O7-δ (YBCO) direct current superconducting quantum interference devices (SQUIDs) based on grain boundary Josephson junctions. The nanoSQUIDs are fabricated by epitaxial growth of 120 nm-thick films of the high-transition temperature cuprate superconductor YBCO via pulsed laser deposition on MgO bicrystal substrates with 24° misorientation angle, followed by sputtering of dAu = 65 nm thick Au. Nanopatterning is performed by Ga focused ion beam (FIB) milling. The SQUID performance is comparable to devices on SrTiO3 (STO), as demonstrated by electric transport and noise measurements at 4.2 K. MgO has orders of magnitude smaller dielectric permittivity than STO; i.e., one may avoid Au as a resistively shunting layer to reduce the intrinsic thermal flux noise of the nanoSQUIDs. However, we find that the Au layer is important for avoiding degradation during FIB milling. Hence, we compare devices with different dAu produced by thinning the Au layer via Ar ion milling after FIB patterning. We find that the reduction of dAu yields an increase in junction resistance, however at the expense of a reduction of the critical current and increase in SQUID inductance. This results in an estimated thermal flux noise that is almost independent of dAu. However, for two devices on MgO with 65 nm-thick Au, we find an order of magnitude lower low-frequency excess noise as compared to nanoSQUIDs on STO or those on MgO with reduced dAu. For one of those devices we obtain with bias-reversal readout ultra-low flux noise of ∼175 nΦ0 Hz-1/2 down to ∼10 Hz.

Post-translational modification of proteins by small ubiquitin-like modifier (SUMO) plays essential roles in a large variety of cellular and developmental processes. While SUMO conjugation to target proteins has been reported in numerous studies in animals and human, and partly also in the model plant Arabidopsis, little is known about the specific roles of SUMO in crop plants. Here, we report about the maize SUMO family and show that the highly conserved core isoform SUMO1 predominately locates to the nucleus where it marks euchromatin rather than heterochromatin. Moreover, SUMO1 is especially present in nuclei of small dividing cells. Strong overexpression of SUMO1 caused a severe dwarf phenotype and abnormalities in floral organ structures. Defects in anther development and female gametogenesis occurred similar to null-mutant phenotypes reported in Arabidopsis. Taken together, these studies imply that precise and fine-tuned conjugation of the highly conserved plant SUMO1 isoform to target proteins is required for vegetative and reproductive development. Mis-regulation by overexpression or knock-out is deleterious, strongly affecting fertility in both dicots and monocots, including the crop plant maize.

In modern thermoplastic injection molding, the overmolding of inserts allows a high level of functional integration. An important quality criterion for the manufacturing of those technical thermoplastic parts is the detailed and comprehensive understanding of the factors that influence shrinkage. Often, local shrinkage differences result in loads on the inserts or cause dimensional tolerance inaccuracies. This study investigates the effect of different insert part geometries and positions along the flow path on the shrinkage of the overmolded part. A mold was designed to overmold square- and cylindrically shaped metal inserts at six different mold positions. Overmold materials were polypropylene (PP), polybutyleneterephthalate (PBT), and polyamide (PA). The results of simulation and experimental measurements indicated significantly lower shrinkage of the overmold with inserts parallel and normal to the flow direction. Square-shaped inserts in most cases induced greater impact on shrinkage behavior compared to the cylindrical inserts. The insert position caused reduced shrinkage with inserts placed at the end of the flow path compared to positions near the feeding point. Additionally, normal to flow shrinkage decreased between central and lateral insert positions. Asymmetrical insert positions especially caused a partial shrinkage onto or rather off of the insert resulting in mechanical load, critical for e.g. sensitive insert parts like RFID transponders. Overall, these findings contribute to a more precise estimation of the achievable dimensional part accuracy to improve overmolding processes in injection molding.

Magnetic fields penetrate a type II superconductor as magnetic flux quanta, called vortices. In a clean superconductor they arrange in a hexagonal lattice, while by addition of periodic artificial pinning centers many other arrangements can be realized. Using the focused beam of a helium ion microscope, we have fabricated periodic patterns of dense pinning centers with spacings as small as 70 nm in thin films of the cuprate superconductor YBa2Cu3O7-delta. In these ultradense kagome-like patterns, the voids lead to magnetic caging of vortices, resulting in unconventional commensurability effects that manifest themselves as peaks in the critical current and minima in the resistance versus applied magnetic field up to similar to 0.4 T. The various vortex patterns at different magnetic fields are analyzed by molecular dynamics simulations of vortex motion, and the magnetic field dependence of the critical current is confirmed. These findings open the way for a controlled manipulation of vortices in cuprate superconductors by artificial sub-100 nm pinning landscapes.

Resumen del trabajo presentado al 2nd ELECMI International Workshop, celebrado en Zaragoza (Espana) del 11 al 13 de junio de 2018.

Embryogenesis in flowering plants is initiated by an asymmetric zygote division, generating two daughter cells that are the precursors of different cell lineages. Little is known about the molecular players regulating activation and progression of zygote development, establishment of asymmetry, and the plant-specific process of cell-plate formation. Here, we report the function of the ubiquitin-like modifier DiSUMO-LIKE (DSUL) for early embryo development in maize. Introducing a DSUL-RNAi construct by sperm cells affects cytokinesis generating non-separated zygotic daughter nuclei or multinucleate embryonic cells lacking cell plates. DSUL accumulates in the cytoplasm partly in granules, in the nucleus, as well as in the cell division zone. The enzymatic DSULyation cascade involves maturation and the same enzymatic machinery for activation and conjugation as was previously shown for SUMO1. Identification of DSUL targets suggests predominant roles of DSULylation in regulation of cytoplasmic RNA metabolism as well as in cell-cycle progression and cell-plate formation. A comparison of DSUL and SUMO1 localization during the cell cycle and of their substrates indicates strong functional diversification between these two SUMO family modifiers.

Plants encode a unique group of papain-type cysteine endopeptidases (CysEP) characterized by a C-terminal KDEL endoplasmic reticulum retention signal (KDEL-CysEP) and an unusually broad substrate specificity. The three Arabidopsis KDEL-CysEPs (AtCEP1, AtCEP2, and AtCEP3) are differentially expressed in vegetative and generative tissues undergoing programmed cell death (PCD). While KDEL-CysEPs have been shown to be implicated in the collapse of tissues during PCD, roles of these peptidases in processes other than PCD are unknown. Using mCherry-AtCEP2 and EGFP-AtCEP1 reporter proteins in wild type versus atcep2 or atcep1 mutant plants, we explored the participation of AtCEP in young root development. Loss of AtCEP2, but not AtCEP1 resulted in shorter primary roots due to a decrease in cell length in the lateral root (LR) cap, and impairs extension of primary root epidermis cells such as trichoblasts in the elongation zone. AtCEP2 was localized to root cap corpses adherent to epidermal cells in the rapid elongation zone. AtCEP1 and AtCEP2 are expressed in root epidermis cells that are separated for LR emergence. Loss of AtCEP1 or AtCEP2 caused delayed emergence of LR primordia. KDEL-CysEPs might be involved in developmental tissue remodeling by supporting cell wall elongation and cell separation.

Key message Pathways for assimilates. Abstract During their life cycle, plants alternate between a haploid stage, the gametophyte, and a diploid stage, the sporophyte. In higher plants, meiosis generates the gametophyte deeply embedded in the maternal tissue of the flower. The megaspore mother cell undergoes meiosis, and then, the surviving megaspore of the four megaspores produced undergoes mitotic divisions and finally gives rise to the female gametophyte, consisting of the egg cell, two synergids, the central cell, which due to the fusion of two nuclei is diploid (double haploid) in Arabidopsis and most angiosperms and the antipods, whose number is not fixed and varies significantly between species (Yadegari and Drews in Plant Cell 16(Suppl):S133–S141, 2004 ). The maternal tissues that harbor the female gametophyte and the female gametophyte are referred to as the ovule (Fig. 1 ). Double fertilization of the egg cell and the central cell by the two generative nuclei of the pollen leads to the diploid embryo and the endosperm, respectively (Hamamura et al. in Curr Opin Plant Biol 15:70–77, 2012 ). Upon fertilization, the ovule is referred to as the seed. Seeds combine two purposes: to harbor storage compounds for use by the embryo upon germination and to protect the embryo until the correct conditions for germination are encountered. As a consequence, seeds are the plant tissue that is of highest nutritional value and the human diet, by a considerable amount, consists of seeds or seed-derived products. Amino acids are of special interest, because plants serve as the main source for the so-called essential amino acids, that animals cannot synthesize de novo and are therefore often a limiting factor for human growth and development (WHO in Protein and amino acid requirements in human nutrition. WHO technical report series, WHO, Geneva, 2007 ). The plant embryo needs amino acids for general protein synthesis, and additionally they are used to synthesize storage proteins in the seeds of certain plants, e.g., legumes as a resource to support the growth of the seedling after germination. The support of the embryo depends on transport processes that occur between the mother plant and the seed tissues including the embryo. In this review, we will focus on the processes of unloading amino acids from the phloem and their post-phloem transport. We will further highlight similarities between amino acid transport and the transport of the main assimilate and osmolyte, sucrose. Finally, we will discuss similarities and differences between different plant species in terms of structural aspects but for the molecular aspects we are almost exclusively focusing on Arabidopsis . Fig. 1 Vascularization of the Arabidopsis ovule and seed. Plants expressing ER-localized mCherry under control of the companion cell-specific SUC2 promoter and ER-localized GFP under control of the sieve element marker PD1 as described (Müller et al. 2015 ) are shown to visualize the phloem in the funiculus and the chalazal regions. a Overview over an ovule. FG: female gametophyte. b A magnification of the region marked by a square in panel a . c Overview over a seed. ES: endosperm; E: embryo. d A magnification of the region marked by a square in panel c . The arrows in b and d point to the terminal companion cell and arrowheads to terminal sieve elements

We report on direct, real-space imaging of the stray magnetic field above a micro-scale disc of a thin film of the high-temperature superconductor YBa2Cu3O7−δ (YBCO) using scanning single spin magnetometry. Our experiments yield a direct measurement of the sample’s London penetration depth and allow for a quantitative reconstruction of the supercurrents flowing in the sample as a result of Meissner screening. These results show the potential of scanning single spin magnetometry for studies of the nanoscale magnetic properties of thin-film superconductors, which could be readily extended to elevated temperatures or magnetic fields.

In the near future 10 billion people will live on our planet. To support the world’s population yield has to increase dramatically. This goal can only be achieved by an enhancement in productivity and minimization of yield loss by pathogens. Amino acids are of special interest for human nutrition, because essential amino acids cannot be synthesized de novo by animals. Roots and fruits often represent the edible part of plants. These tissues depend on the supply from the green parts of the plant and therefore represent sink tissues. An example for an endogenous sink tissue is the developing seed including the embryo. Furthermore, also biotrophic pathogens force the plant to establish sink tissues. The supply of sink tissues is facilitated by a range of transporters. In this work the plasma membrane-localized UmamiT amino acid facilitators were characterized in detail. They showed overlapping expression in the vascular tissue of roots, hypocotyl, leaves and stems, where they colocalized with phloem sieve elements. According to their position in the vascular parenchyma they are discussed to play a role in the amino acid cycling and in long distance transport. In the seed, UmamiTs displayed a spatio-temporally distinct expression pattern in symplasmically isolated tissues: the unloading zone, the outer and inner integument and the endosperm. From a physiological point of view, UmamiTs are located in strategically important domains for the transfer of amino acids within the sink tissue. It could be shown that a loss of function of UmamiTs resulted in elevated levels of free amino acids in seeds and a reduction of seed size. These findings indicate that the function of UmamiTs is directly linked with yield, which makes them interesting in the case of enhancement of productivity of crop plants in agriculture in the future. In roots, UmamiTs were found to be differentially expressed in the xylem parenchyma and phloem. Also here, a colocalization with sieve elements was observed. Phenotypical analysis of mutants showed a reduction of root length in young seedlings and an altered organization of the root meristem, resulting in a unusual differentiation of columella stem cells or an additional layer of undifferentiated columella cells. Additionally, it was found that the cell cycle was also affected and the number of dividing cells in the root tip was significantly reduced. Higher order mutants of clade I UmamiTs investigated here showed a strong phenotype due to a complete loss of the root meristem. Double mutation of UmamiT14 and UmamiT29 led to a reduction of the mRNA of PLT1 in the stem cells. Overexpression of UmamiTs revealed a polar distribution of the fusion protein in anticlinal direction and an expression in stem cells and in differentiating protophloem, which suggests a role of UmamiTs in the directed long distance transport of amino acids along the vasculature and the supply of the root stem cells with amino acids. During pathogen interaction with root knot nematodes, UmamiTs were specifically expressed in the feeding site, which is a tumor like sink tissue. Expression was detected in small parenchyma cells located close to the symplasmically isolated giant cells. UmamiT-positive cells were characterized as juvenile phloem: they were nucleated and APL-positive, colocalized with the sieve element specific epitope RS6 and showed a remarkable expression of SCR. The findings presented in this thesis suggest that UmamiT-positive cells in the unloading zone of the seed and the feeding site of root knot nematodes function as unique cells with transfer function to supply symplasmically isolated sink tissues in plants.

We present the design, realization, and performance of a three-axis vector nano superconducting quantum interference device (nanoSQUID). It consists of three mutually orthogonal SQUID nanoloops that allow distinguishing the three components of the vector magnetic moment of individual nanoparticles placed at a specific position. The device is based on Nb/HfTi/Nb Josephson junctions and exhibits line widths of ∼250 nm and inner loop areas of 600 × 90 and 500 × 500 nm(2). Operation at temperature T = 4.2 K under external magnetic fields perpendicular to the substrate plane up to ∼50 mT is demonstrated. The experimental flux noise below [Formula: see text] in the white noise limit and the reduced dimensions lead to a total calculated spin sensitivity of [Formula: see text] and [Formula: see text] for the in-plane and out-of-plane components of the vector magnetic moment, respectively. The potential of the device for studying three-dimensional properties of individual nanomagnets is discussed.

Key message CEP cell death markers. Abstract Programmed cell death (PCD) is essential for proper plant growth and development. Plant-specific papain-type KDEL-tailed cysteine endopeptidases (KDEL-CysEPs or CEPs) have been shown to be involved in PCD during vegetative development as executors for the last step in the process. The Arabidopsis genome encodes three KDEL-CysEPs: AtCEP1 , AtCEP2 and AtCEP3 . With the help of fluorescent fusion reporter lines, we report here a detailed expression analysis of KDEL-CysEP (pro)proteins during reproductive processes, including flower organ and germline development, fertilization and seed development. AtCEP1 is highly expressed in different reproductive tissues including nucellus cells of mature ovule and the connecting edge of anther and filament. After fertilization, AtCEP1 marks integument cell layers of the seeds coat as well as suspensor and columella cells of the developing embryo. Promoter activity of AtCEP2 is detected in the style of immature and mature pistils, in other floral organs including anther, sepal and petal. AtCEP2 mainly localizes to parenchyma cells next to xylem vessels. Although there is no experimental evidence to demonstrate that KDEL-CysEPs are involved in PCD during fertilization, the expression pattern of AtCEPs, which were previously shown to represent cell death markers during vegetative development, opens up new avenues to investigate PCD in plant reproduction.

Microscopic studies of superconductors and their vortices play a pivotal role in our understanding of the mechanisms underlying superconductivity. Local measurements of penetration depths or magnetic stray-fields enable access to fundamental aspects of superconductors such as nanoscale variations of superfluid densities or the symmetry of their order parameter. However, experimental tools, which offer quantitative, nanoscale magnetometry and operate over the large range of temperature and magnetic fields relevant to address many outstanding questions in superconductivity, are still missing. Here, we demonstrate quantitative, nanoscale magnetic imaging of Pearl vortices in the cuprate superconductor YBCO, using a scanning quantum sensor in form of a single Nitrogen-Vacancy (NV) electronic spin in diamond. The sensor-to-sample distance of ~10nm we achieve allows us to observe striking deviations from the prevalent monopole approximation in our vortex stray-field images, while we find excellent quantitative agreement with Pearl's analytic model. Our experiments yield a non-invasive and unambiguous determination of the system's local London penetration depth, and are readily extended to higher temperatures and magnetic fields. These results demonstrate the potential of quantitative quantum sensors in benchmarking microscopic models of complex electronic systems and open the door for further exploration of strongly correlated electron physics using scanning NV magnetometry.

Essential amino acids cannot be synthesized by humans and animals. They often are limiting in plant-derived foods and determine the nutritional value of a given diet. Seeds and fruits often represent the harvestable portion of plants. In order to improve the amino acid composition of these tissues, it is indispensable to understand how these substrates are transported within the plant. Amino acids result from nitrogen assimilation, which often occurs in leaves, the source tissue. They are transported via the vasculature, the xylem, and the phloem into the seeds, the so-called sink tissue, where they are stored or consumed. In seeds, several tissues are symplasmically isolated, i.e., not connected by plasmodesmata, channels in the cell walls that enable a cytoplasmic continuum in plants. Consequently, amino acids must be exported from cells into the apoplast and re-imported many times to support seed development. Several amino acid importers are known, but exporters remained elusive. Here, we characterize four members of the plant-specific UmamiT transporter family from Arabidopsis, related to the amino acid facilitator SIAR1 and the vacuolar auxin transporter WAT1. We show that the proteins transport amino acids along their (electro)chemical potential across the plasma membrane. In seeds, they are found in tissues from which amino acids are exported. Loss-of-function mutants accumulate high levels of free amino acids in fruits and produce smaller seeds. Our results strongly suggest a crucial role for the UmamiTs in amino acid export and possibly a means to improve yield quality.

In this paper we provide insight into the cryptic diversity and biogeographic patterns of a widely distributed Mediterranean ant species, Temnothorax lichtensteini (Bondroit Annales de la Société Entomologique de France 87:1–174, 1918), based on evidence from multiple data sources. An exploratory analysis of morphometric data, combined with sequencing of a 652 bp fragment of the mitochondrial gene for the cytochrome c oxidase subunit I (CO I), indicates the existence of three distinct lineages. Divergence of two recognised genetic lineages, Western and Eastern Mediterranean clusters, is not reliably supported by confirmatory analysis of morphological data. We hypothesise that this reflects incomplete speciation in separate glacial refugia and therefore discuss only biogeographic aspects of these two parapatric populations. However, the third, Peloponnese, lineage is divergent in both morphology and CO I sequences and its separation from the other two lineages is convincingly confirmed. For this lineage we assume a completed speciation and describe the taxon formally as Temnothorax laconicus sp.n., the sister species of T. lichtensteini.

The role of root hairs in intraspecific competition for Phosporus (P) is well examined, but their importance during interaction with other plant species is unknown, as is the differential meaning for competitive effect and response. This study aims to fill this gap of knowledge.

Root-root interactions are much more sophisticated than previously thought, yet the mechanisms of belowground neighbor perception remain largely obscure. Genome-wide transcriptome analyses allow detailed insight into plant reactions to environmental cues. A root interaction trial was set up to explore both morphological and whole genome transcriptional responses in roots of Arabidopsis thaliana in the presence or absence of an inferior competitor, Hieracium pilosella. Neighbor perception was indicated by Arabidopsis roots predominantly growing away from the neighbor (segregation), while solitary plants placed more roots toward the middle of the pot. Total biomass remained unaffected. Database comparisons in transcriptome analysis revealed considerable similarity between Arabidopsis root reactions to neighbors and reactions to pathogens. Detailed analyses of the functional category "biotic stress" using MapMan tools found the sub-category "pathogenesis-related proteins" highly significantly induced. A comparison to a study on intraspecific competition brought forward a core of genes consistently involved in reactions to neighbor roots. We conclude that beyond resource depletion roots perceive neighboring roots or their associated microorganisms by a relatively uniform mechanism that involves the strong induction of pathogenesis-related proteins. In an ecological context the findings reveal that belowground neighbor detection may occur independently of resource depletion, allowing for a time advantage for the root to prepare for potential interactions.