Transition from fractal-dendritic to compact islands for the 2D-ferroelectric SnSe on graphene/Ir(111)

Epitaxial growth is a versatile method to prepare two-dimensional van der Waals ferroelectrics like group IV monochalcogenides which have potential for novel electronic devices and sensors. We systematically study SnSe monolayer islands grown by molecular beam epitaxy, especially the effect of annealing temperature on shape and morphology of the edges. Characterization of the samples by scanning tunneling microscopy reveals that the shape of the islands changes from fractal-dendritic after deposition at room temperature to a compact rhombic shape through annealing, but ripening processes are absent up to the desorption temperature. A two-step growth process leads to large, epitaxially aligned rhombic islands bounded by well-defined110-edges (armchair-like), which we claim to be the equilibrium shape of the stoichiometric SnSe monolayer islands. The relaxation of the energetically favorable edges is detected in atomically resolved STM images. The experimental findings are supported by the results of our first-principles calculations, which provide insights into the energetics of the edges, their reconstructions, and yields the equilibrium shapes of the islands which are in good agreement with the experiment.

Autologous corneal graft for the treatment of deep corneal defects in dogs: 15 cases (2014-2017)

OBJECTIVES

To describe the use of corneal autografts for repair of deep corneal defects in dogs.

MATERIALS AND METHODS

Retrospective analysis of clinical records of dogs that received autologous corneal grafts.

RESULTS

Fifteen dogs (16 eyes) of different breed, age and gender were included. Brachycephalic breeds were overrepresented (10/15 dogs). Defects were unilateral in 14 dogs and bilateral in one dog, extended to at least 80% of the stromal thickness in all eyes, with descemetoceles in four eyes and corneal perforations in five eyes. Most ulcers (13/16 eyes) were located centrally. Corneal autografts were harvested from healthy peripheral cornea of the ipsilateral eye. The thickness of the autograft was limited to a set depth of 0.3 mm. The autograft was sutured into a previously debrided ulcer bed with a continuous or simple interrupted suture pattern using absorbable or non-absorbable suture material. Additional interventions included a partial temporary tarsorrhaphy and bandage contact lenses. Postoperatively patients received topical antibiotics and systemic anti-inflammatory drugs, and 12/15 dogs also received systemic antibiotics. Mean follow-up time was 54 days (2 to 462). In all eyes the donor site healed uneventfully with mild, persistent corneal fibrosis. Postoperative complications included autograft keratomalacia, graft dehiscence and corneal pigmentation. No patient required additional surgery. Good structural and functional outcome was accomplished in 14 of 16 eyes.

CLINICAL SIGNIFICANCE

Autologous corneal grafts provide tectonic support and result in good corneal transparency in selected cases of dogs with deep to perforated corneal ulcerations.

An environment for sustainable research software in Germany and beyond: current state, open challenges, and call for action

Research software has become a central asset in academic research. It optimizes existing and enables new research methods, implements and embeds research knowledge, and constitutes an essential research product in itself. Research software must be sustainable in order to understand, replicate, reproduce, and build upon existing research or conduct new research effectively. In other words, software must be available, discoverable, usable, and adaptable to new needs, both now and in the future. Research software therefore requires an environment that supports sustainability. Hence, a change is needed in the way research software development and maintenance are currently motivated, incentivized, funded, structurally and infrastructurally supported, and legally treated. Failing to do so will threaten the quality and validity of research. In this paper, we identify challenges for research software sustainability in Germany and beyond, in terms of motivation, selection, research software engineering personnel, funding, infrastructure, and legal aspects. Besides researchers, we specifically address political and academic decision-makers to increase awareness of the importance and needs of sustainable research software practices. In particular, we recommend strategies and measures to create an environment for sustainable research software, with the ultimate goal to ensure that software-driven research is valid, reproducible and sustainable, and that software is recognized as a first class citizen in research. This paper is the outcome of two workshops run in Germany in 2019, at deRSE19 - the first International Conference of Research Software Engineers in Germany - and a dedicated DFG-supported follow-up workshop in Berlin.

An environment for sustainable research software in Germany and beyond: current state, open challenges, and call for action

Research software has become a central asset in academic research. It optimizes existing and enables new research methods, implements and embeds research knowledge, and constitutes an essential research product in itself. Research software must be sustainable in order to understand, replicate, reproduce, and build upon existing research or conduct new research effectively. In other words, software must be available, discoverable, usable, and adaptable to new needs, both now and in the future. Research software therefore requires an environment that supports sustainability. Hence, a change is needed in the way research software development and maintenance are currently motivated, incentivized, funded, structurally and infrastructurally supported, and legally treated. Failing to do so will threaten the quality and validity of research. In this paper, we identify challenges for research software sustainability in Germany and beyond, in terms of motivation, selection, research software engineering personnel, funding, infrastructure, and legal aspects. Besides researchers, we specifically address political and academic decision-makers to increase awareness of the importance and needs of sustainable research software practices. In particular, we recommend strategies and measures to create an environment for sustainable research software, with the ultimate goal to ensure that software-driven research is valid, reproducible and sustainable, and that software is recognized as a first class citizen in research. This paper is the outcome of two workshops run in Germany in 2019, at deRSE19 - the first International Conference of Research Software Engineers in Germany - and a dedicated DFG-supported follow-up workshop in Berlin.

Managerial perceptions of energy in logistics

Purpose

Because of the major contribution of logistics to the greenhouse gas effect, logistics research has begun to address the topic of energy, but it has not yet targeted the role of energy within logistical decision-making processes. To facilitate such endeavors, the purpose of this paper is to explore the perceptions of energy which managers in logistics organizations portray.

Design/methodology/approach

This investigation is based on interviews with 17 managers. The findings are embedded in the theory of planned behavior (TPB) and stakeholder theory (SHT).

Findings

The study depicts initial insights on which energy-related perceptions exist, how they can be categorized into attitudes, subjective norms, and perceived behavioral controls (PBCs), and how different stakeholders seem to affect them.

Research limitations/implications

This research suggests a tentative comprehensive conceptual framework that describes the role of energy in logistical decision-making processes. The findings on attitudes and subjective norms appear to be unspecific to the logistics domain, whereas some of the PBCs are presumably unique to the logistics context. Future logistics research should hence focus its efforts on the PBCs. Generalizability and completeness of the managerial perceptions must be validated by future research.

Practical implications

The findings help logistics organizations in scrutinizing managerial perspectives on energy and in developing awareness-raising measures.

Originality/value

The behavioral perspective applied in this study can complement extant, more technically oriented views. The conceptual framework that integrates the TPB and SHT may also be useful for organizational research beyond the logistics domain.

Extending the supply chain visibility boundary

Purpose

The purpose of this paper is to investigate how buying firms facing low supply chain visibility can utilize their stakeholder network to identify salient supply chain sustainability risks (SCSR).

Design/methodology/approach

The study employs a design science approach to develop a procedural model for identifying SCSR as a new artifact. A small-scale field-testing study in a food supply chain of a Swiss retail firm demonstrates its applicability and pragmatic validity.

Findings

When stakeholder knowledge external to the supply chain is regarded as a valuable resource, a generic understanding of a buying firm’s supply chain suffices to identify SCSR hotspots without creating complexity for the SCSR management.

Research limitations/implications

The paper contributes to the study of SCSR by identifying mechanisms buying firms can employ to identify SCSR hotspots and fostering the nascent understanding of responsibility attribution by stakeholders. Moreover, the emerging theory of the supply chain is enriched by paving a way to extend the supply chain visibility boundary. The procedural model is presumably most useful in contexts of elevated stakeholder pressure and low supply chain visibility. Future research should seek to validate and improve the effectiveness of the newly designed artifact.

Practical implications

The procedural model is directly applicable in corporate practice to the identification of SCSR. Moreover, its application fosters the understanding of a firm’s supply chain and its stakeholder network.

Originality/value

SCSR is an increasingly important phenomenon in corporate practice that has received only scarce research attention. The design science approach represents a valuable means for generating theoretical insights and emergent solutions to the real-world problem of SCSR identification.

The dark side of global sourcing: a systematic literature review and research agenda

Purpose

The purpose of this paper is to present a systematic review of the literature concerning the negative aspects of global sourcing (GS). It complements prior research on the positive aspects of GS, advances theoretical understanding of the phenomenon, and suggests an agenda for future research.

Design/methodology/approach

The sourcing, international business and supply chain management literature is systematically reviewed and findings from 83 previous studies are investigated.

Findings

Research on the downsides of GS has intensified over the last decade, but the related knowledge has been very fragmented and oftentimes latent. This literature review extracts knowledge around 28 antecedents to GS downsides from the literature and illustrates their potential harmful effects along operational and financial performance dimensions. Findings suggest that future research should focus more on the effects of decision-making biases and the effects of firm-internal barriers. The dynamic and hidden costs of GS should also be scrutinized in more depth.

Originality/value

This study is the first systematic literature review of the downsides of GS. It facilitates a more balanced and nuanced picture of GS to help managers make better-informed GS decisions. The review also offers a holistic research framework that opens up avenues for much-needed research into the “dark side” of GS.

Supplier development for sustainability: contextual barriers in global supply chains

Purpose

– The purpose of this paper is to explore contextual barriers to supplier development for sustainability (SDS) in global supply chains and managerial remedies to mitigate such barriers.

Design/methodology/approach

– A dyadic case study design was adopted with a Western European buyer and six of its Chinese suppliers. The database consists of 41 interviews and 81 documents.

Findings

– Contextual barriers to SDS in global supply chains derive from complexities in the sustainability concept, socio-economic differences, spatial and linguistic distance, as well as cultural differences between buyers and suppliers. Partial remedies include effective joint communications, an open organizational culture, and the fostering of cross-contextual understanding.

Research limitations/implications

– The findings contribute to theory development at the intersection of sustainable and global supply chain management research. They help to explain why scarce sustainability-related progress in global supply chains has occurred in recent years.

Practical implications

– The identified barriers facilitate managerial decision making that will expedite SDS progress in global contexts.

Social implications

– By diffusing knowledge regarding available remedies, the study contributes to improving SDS effectiveness, thereby fostering sustainability capabilities and performance of suppliers.

Originality/value

– This research highlights the criticality of contextual barriers to SDS. The barrier effects that stem from differing real-world conceptions of sustainability may inform future sustainable supply chain management research within and beyond SDS.

Boundary Conditions

Boundary conditions (BC) have long been discussed as an important element in theory development, referring to the “who, where, when” aspects of a theory. However, it still remains somewhat vague as to what exactly BC are, how they can or even should be explored, and why their understanding matters. This research tackles these important questions by means of an in-depth theoretical-methodological analysis. The study contributes fourfold to organizational research methods: First, it develops a more accurate and explicit conceptualization of BC. Second, it widens the understanding of how BC can be explored by suggesting and juxtaposing new tools and approaches. It also illustrates BC-exploring processes, drawing on two empirical case examples. Third, it analyzes the reasons for exploring BC, concluding that BC exploration fosters theory development, strengthens research validity, and mitigates the research-practice gap. Fourth, it synthesizes the analyses into 12 tentative suggestions for how scholars should subsequently approach the issues surrounding BC. The authors hope that the study contributes to consensus shifting with respect to BC and draws more attention to BC.

Oxygen orders differently under graphene: new superstructures on Ir(111)

Using scanning tunneling microscopy, the oxygen adsorbate superstructures on bare Ir(111) are identified and compared to the ones formed by intercalation in between graphene and the Ir(111) substrate. For bare Ir(111) we observe O-(2 × 2) and O-(2 × 1) structures, thereby clarifying a persistent uncertainty about the existence of these structures and the role of defects for their stability. For the case of graphene-covered Ir(111), oxygen intercalation superstructures can be imaged through the graphene monolayer by choosing proper tunneling conditions. Depending on the pressure, temperature and duration of O2 exposure as well as on the graphene morphology, O-(2 × 2), O-(√3×√3)-R30°, O-(2 × 1) and O-(2√3 × 2√3)-R30° superstructures with respect to Ir(111) are observed under the graphene cover. Two of these structures, the O-(√3 × √3)-R30° and the (2√3 × 2√3)-R30° structure are only observed when the graphene layer is on top. Phase coexistence and formation conditions of the intercalation structures between graphene and Ir(111) are analyzed. The experimental results are compared to density functional theory calculations including dispersive forces. The existence of these phases under graphene and their absence on bare Ir(111) are discussed in terms of possible changes in the adsorbate-substrate interaction due to the presence of the graphene cover.

The ABC for Studying the Too-Much-of-a-Good-Thing Effect

The too-much-of-a-good-thing (TMGT) effect occurs when an initially positive relation between an antecedent and a desirable outcome variable turns negative when the underlying ordinarily beneficial antecedent is taken too far, such that the overall relation becomes nonmonotonic. The presence of the TMGT effect incites serious concerns about the validity of linearly specified empirical models. Recent research posited that the TMGT effect is omnipresent, due to an overarching meta-theoretical principle. Drawing on the competitive mediation approach, the authors of the present study suggest an antecedent-benefit-cost (ABC) framework that explains the TMGT effect as a frequent but not omnipresent issue in empirical research and integrates a variety of linear and nonlinear relationships. The ABC framework clarifies important conceptual and empirical issues surrounding the TMGT effect and facilitates the choice between linear and curvilinear models. To avoid serious methodological pitfalls, future studies with desirable outcome variables such as, for example, task performance, job performance, firm performance, satisfaction, team innovation, leadership effectiveness, or individual creativity should consider the ABC framework.

The mechanism of caesium intercalation of graphene

Properties of many layered materials, including copper- and iron-based superconductors, topological insulators, graphite and epitaxial graphene, can be manipulated by the inclusion of different atomic and molecular species between the layers via a process known as intercalation. For example, intercalation in graphite can lead to superconductivity and is crucial in the working cycle of modern batteries and supercapacitors. Intercalation involves complex diffusion processes along and across the layers; however, the microscopic mechanisms and dynamics of these processes are not well understood. Here we report on a novel mechanism for intercalation and entrapment of alkali atoms under epitaxial graphene. We find that the intercalation is adjusted by the van der Waals interaction, with the dynamics governed by defects anchored to graphene wrinkles. Our findings are relevant for the future design and application of graphene-based nano-structures. Similar mechanisms can also have a role for intercalation of layered materials.

Atomic structure and crystalline order of graphene-supported ir nanoparticle lattices

We present the atomic structure of Ir nanoparticles with 1.5 nm diameter at half height and three layers average height grown on graphene/Ir(111). Using surface x-ray diffraction, we demonstrate that Ir nanoparticles on graphene/Ir(111) form a crystallographic superlattice with high perfection. The superlattice arrangement allows us to obtain detailed information on the atomic structure of the nanoparticles themselves, such as size, shape, internal layer stacking and strain. Our experiments disclose that the nanoparticles reside epitaxially on top of the graphene moiré structure on Ir(111), resulting in significant lateral compressive intraparticle strain. Normal incidence x-ray standing wave experiments deliver additional information on the particle formation induced restructuring of the graphene layer.

Wave-function mapping of graphene quantum dots with soft confinement

Using low-temperature scanning tunneling spectroscopy, we map the local density of states of graphene quantum dots supported on Ir(111). Because of a band gap in the projected Ir band structure around the graphene K point, the electronic properties of the QDs are dominantly graphenelike. Indeed, we compare the results favorably with tight binding calculations on the honeycomb lattice based on parameters derived from density functional theory. We find that the interaction with the substrate near the edge of the island gradually opens a gap in the Dirac cone, which implies soft-wall confinement. Interestingly, this confinement results in highly symmetric wave functions. Further influences of the substrate are given by the known moiré potential and a 10% penetration of an Ir surface resonance into the graphene layer.

Dirac cones and minigaps for graphene on Ir(111)

Epitaxial graphene on Ir(111) prepared in excellent structural quality is investigated by angle-resolved photoelectron spectroscopy. It clearly displays a Dirac cone with the Dirac point shifted only slightly above the Fermi level. The moiré resulting from the overlaid graphene and Ir(111) surface lattices imposes a superperiodic potential giving rise to Dirac cone replicas and the opening of minigaps in the band structure.

Electrochemically deposited Pd islands on an organic surface: the presence of Coulomb blockade in STM I(V) curves at room temperature

Palladium islands with a thickness of a few monolayers were deposited on top of a self-assembled monolayer (SAM) fabricated from 4-mercaptopyridine. In the I(V) curves obtained using the scanning tunneling microscope (STM) clearly the signature of Coulomb blockade is observed, explicitly demonstrating that these islands are coupled to the underlying gold substrate only via a tunneling barrier; this spectroscopic feature also allows to distinguish the palladium islands from similar morphological features present on the gold substrate prior to palladium deposition.

The IPM Wheat Model--results of a three-year study in North Rhine-Westphalia, Lower Saxony and Schleswig-Holstein

Under the primary utilisation of phytosanitary production factors such as selection of variety, crop rotation and N fertilisation according to plant requirements, the IPM Wheat Model comprises the elements diagnosis (qualitative = type of pathogen, quantitative = disease severity), scientifically grounded treatment thresholds which, as critical values in pathogen development, can be applied to define the optimum time of fungicide application, and pathogen-specific effective fungicides and application amounts. This leads to the location and year-specific optimised control of the pathogen and of the associated yield performance. After several years of development in Bavaria (from 1985 on) and Schleswig-Holstein (1993-1999), the model was tested as part of a project involving the Universities of Bonn and Kiel and the plant protection services of the German states of Lower Saxony, North Rhine-Westphalia and Schleswig-Holstein in a three-year study (1999-2001) in interregional locations (usually nine per state) with the winter wheat variety Ritmo (interregional indicator variety) and a further variety of regional importance in different variations (untreated control, three to four times growth stage-oriented variants for the determination of the absolute damage potential, IPM-variant). In exact records (approx. 12 dates per vegetation period), the disease epidemics were recorded weekly. With the genetically uniform indicator variety Ritmo, the results documented substantially differing year- and location-specific disease and yield patterns. Interregionally, a broad wheat pathogen spectrum (Puccinia striiformis, P. recondita, Septoria tritici, Stagonospora (syn. Septoria) nodorum, Blumeria (syn. Erysiphe) graminis, Pseudocercosporella herpotrichoides, Drechslera tritici-repentis) in differing composition, disease severity and damage effect was demonstrated. The heterogeneity of the infection and damage patterns was increased in the case of the second variety, in association with the genetic variability. The epidemiologically-orientated indications (average two, reduced application amounts) according to the IPM Wheat Model in association with time-diverging progressions led, on an interregional basis, with minimum input and in association with the diverging dynamics, to a biologically and economically optimised fungicide application. In the context of economic and ecological performance, the comprehensive results of the project demonstrated the valuable functionality of the IPM Wheat Model.

Reduced stress-induced hyperthermia in mGluR5 knockout mice

It hs been suggested that metabotropic glutamate receptor subtype 5 (mGluR5) play a role in the expression of anxiety, based on anxiolytic-like effects of the selective mGluR5 antagonist MPEP (2-methyl-6-(phenylethynyl)pyridine) in rodent models of anxiety, including stress-induced hyperthermia (SIH). To examine the suggested role of mGlu5 receptors in the expression of anxiety, we examined the stress response in mice lacking mGluR5 in several variations of the SIH procedure. In this paradigm, stress causes a mild increase in body temperature that can be blocked by known anxiolytic agents. Three procedures were employed: classical SIH using rectal-probe measurement of body temperature, and radiotelemetric measurement of body temperature in response to either saline injection or to the introduction of an intruder into the home cage. In all three procedures the mGluR5-knockout mice displayed a significant attenuation of the hyperthermic response to stress compared to littermate wild-type control mice. To confirm that our observations were likely to be due to the absence of mGluR5 in the knockout mice we also tested the effect of the recently described selective mGluR5 antagonist MTEP (3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine) in both the wild-type and mGluR5 knockout mice. Administration of MTEP in the wild-type mice, but not the mGluR5 knockout mice, attenuated SIH. That the mGluR5 knockout mice displayed an anxiolytic-like phenotype and that the mGluR5 antagonist, MTEP, showed a anxiolytic-like effect only in mice possessing mGluR5 further supports the suggestion that mGluR5 antagonists may be useful in the treatment of anxiety.

INK4a-ARF alterations in liver cell adenoma

BACKGROUND

The INK4a-ARF (CDKN2A) locus on chromosome 9p21 encodes two tumour suppressor proteins, p16(INK4a) and p14(ARF), whose functions are inactivated in many human cancers.

AIMS

To evaluate p14(ARF) and p16(INK4a) alterations in liver cell adenoma.

METHODS

After microdissection, DNA from 25 liver cell adenomas and corresponding normal liver tissue were analysed for INK4-ARF inactivation by DNA sequence analysis, methylation specific polymerase chain reaction, restriction enzyme related-polymerase chain reaction (RE-PCR), mRNA expression, microsatellite analysis, and immunohistochemistry. In addition, microdeletion of p14(ARF) and p16(INK4a) were assessed by differential PCR.

RESULTS

Methylation of p14(ARF) was found in 3/25 cases (12%) and alterations in p16(INK4a) occurred in 6/25 liver cell adenomas (24%) which correlated with loss of mRNA transcription. We failed to detect microdeletions or specific mutations of both exons. p16(INK4a) methylation appeared in the context of an unmethylated p14(ARF) promoter in six cases. In normal liver tissue, p14(ARF) or p16(INK4a) alterations were not observed.

CONCLUSIONS

Our data suggest that p14(ARF) methylation occurs independently of p16(INK4a) alterations in liver cell adenomas. Furthermore, methylation of p14(ARF) and p16(INK4a) may be a result of cell cycle deregulation and does not seem to be a prerequisite of malignancy.

INK4a-ARF alterations and p53 mutations in hepatocellular carcinomas

The INK4a-ARF (CDKN2A)- locus on chromosome 9p21 encodes for two tumour suppressor proteins, p16(INK4a) and p14(ARF), that act as upstream regulators of the Rb-CDK4 and p53 pathways. To study the contribution of each pathway in tumorigenesis of hepatocellular carcinoma (HCC), we analysed the alterations of p14(ARF), p16(INC4a) and p53. After microdissection, DNA of 71 hepatocellular carcinomas was analysed for INK4-ARF inactivation and p53 mutation by DNA sequence analysis, methylation-specific PCR (MSP), restriction-enzyme related polymerase chain reaction (RE-PCR), mRNA expression and immunohistochemistry. In addition, microdeletion of p14(ARF) and p16(INC4a) were assessed by differential PCR. Inactivation of p14(ARF) was found in 11/71 cases (15%), alterations of p16(INK4a) occurred in 47/71 carcinomas (66%), which correlated with loss of mRNA transcription. Five tumours (7%) had homozygous deletions of the INK4a-ARF locus. We failed to detect specific mutations of both exons. P16(INK4a) methylation with an unmethylated p14(ARF) promotor appeared in 39 cases. Mutations of p53 were found in 30 of 71 HCC (42%), and only one of them harboured p14(ARF) inactivation. We failed to establish alterations of the INK4a-ARF locus or p53 status as independent prognostic factor in these tumours. Our data indicate, that p14(ARF) methylation occurs independently of p16(INK4a) alterations in a subset of HCC together with wild type p53. The INK4a-ARF-/p53-pathway was disrupted in 86% of HCC, either by p53 mutations or by INK4a-ARF inactivation, and may have co-operative effects in hepatocarcinogenesis.

Atomic layer growth on Al(111) by ion bombardment

Instead of the expected erosion morphology composed of craters, rare gas ion bombardment of the Al(111) surface is found to cause initial surface growth of several atomic layers. This phenomenon is observed for Ne+, Ar+, and Xe+ at all temperatures at which bombardment induces morphological surface changes and for ion energies down to a few hundred eV. The effect is interpreted on the basis of a thermal spike induced separation of damage into subsurface vacancy clusters and surface adatom clusters.

[The principal physician in emergency medicine]

The implementation of an experienced pre-hospital care emergency physician as an on the-scene medical command officer (MCO) within the emergency medical service (EMS) is an essential prerequisite to guarantee qualified medical supervision during mass-casuality incidents (MCI). The MCO has four basic functions. Within the administration of the EMS system, he is responsible for the medical aspects of strategic planning for the MCI response. During the MCI the MCO is responsible for the overall assessment of the situation, triage, and supervision of medical treatment by physician and non-physician providers. Aside from extensive personal experience in pre-hospital care, the MCO needs special training to be qualified for this position. State EMS laws provide the legal basis for the MCO within the EMS system.