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This paper reports on the photodegradation of organic light-emitting diodes (OLEDs) due to exposure to visible and near-ultraviolet light. Such exposure affects strongly the device performance, e.g., the electroluminescence intensity and the device current decrease considerably, however, the photoluminescence remains unaffected. This photodegradation was investigated on various production-relevant classes of high-quality polymer semiconductors with different energy gaps, i.e., a yellowish-green polyphenylenevinylene derivative, a red polyfluorene derivative, and a blue polyspiro derivative. It will be demonstrated that the action spectrum of the photodegradation is strongly correlated with the fundamental absorption of the polymer itself. The indium-doped tin oxide (ITO) polymer interface was identified as the interface where photodegradation takes place, while the bulk of each layer (ITO or polymer) turned out to be insensitive to irradiation with visible or near-ultraviolet light. Furthermore, it is demonstrated that the photoinduced damage can be suppressed by inserting appropriate interlayer systems. [ABSTRACT FROM AUTHOR]

Trap related properties of the electroluminescent polymers poly(2-methoxy-5-(3',7'dimethyloctyloxy)-1,4-phenylenevinylene (MDMO-PPV, OC[sub 1]C[sub 10]-PPV) and poly[(2-methoxy -5-(3', 7'-dimethyloctyloxy)-1,4-phenylenevinylene]-[(4'-(3',7'-dimethyloctyloxy) phenyl-5)1,4-phenylenevinylene] are investigated in organic light emitting diode (OLED) devices. By means of the thermally stimulated currents (TSC) technique the densities of occupied states, trap polarities and charge transport mechanisms are studied. The fractional TSC technique in combination with optical trap filling reveals broad density-of-occupied-states distributions for both polymers, ranging from 200 to 600 meV located between the highest occupied molecular orbital and lowest unoccupied molecular orbital levels. Conventional TSC experiments in combination with electrical trap filling allow to distinguish between electron and hole traps. In OC[sub 1]C[sub 10]-PPV both trap polarities are detected whereas in the copolymer only hole traps and no electron traps were found. In addition, a TSC study on optical and electrical trap filling in OLED devices strongly suggests the presence of percolation paths. Despite larger charging currents in the electrical trap filling case no or much smaller TSC signals were detected in comparison with the optical trap filling case. [ABSTRACT FROM AUTHOR]

The concept of a blue light emitting diode containing a hole blocking layer (HBL) is generalized to efficiently excite dye molecules introduced in the form of an emission layer on the hole transporting side. The concept allows the excitation of an emitting molecule even if the molecule does not act primarily as a recombination center. On the basis of this concept pure red emitting organic light emitting diodes were produced utilizing tris(dibenzoylmethane)(monophenanthroline)europium(III) [Eu(dbm)[sub 3]phen] as the emitting layer in an Al/LiF/Aluminum tris(8-hydroxyquinoline) (Alq[sub 3])/HBL/Eu(dbm)[sub 3]phen/N,N[sup ′]-di(1-naphthyl)-N,N[sup ′]-diphenylbenzidine (α-NPD)/copper-phthalo- cyanine (CuPc)/indium tin oxide structure. Additionally, the luminance output of such a device was improved by partially adding a hole transport material to the emitting layer in order to increase the penetration of holes into the emission region. A maximum luminance output of 200 cd/m[sup 2] at 15 V was achieved without optimizing the layer thickness. Furthermore, the effect of saturation of the Eu[sup 3+] emission is studied and discussed. The basic device architecture presented here is expected to work with other transport and emitting materials also. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Chemical impurities with known highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital energies were incorporated in organic hole transport materials. The effect of these dopants on quantity and depth of trap levels, transport properties, and luminescence of organic light emitting devices was examined. This was achieved by investigating current-voltage characteristics, luminance-voltage characteristics, and utilizing the method of thermally stimulated current for trap level detection. It was found that 4,4[sup ′],4[sup ″]-tris-[N-(1-naphthyl)-N-(phenylamino)]triphenylamine (1-NaphDATA) doped into N,N[sup ′]-di(1-naphthyl)-N,N[sup ′]-diphenylbenzidine (α-NPD) generates a trap level whose activation energy corresponds to the HOMO energy difference between dopant and matrix molecules. Therefore, the detected electronic states can be assigned to hole traps. The influence of those traps on the charge transport will be reported. For doping α-NPD into 1-NaphDATA no new trap levels could be detected. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The mechanisms of enhanced electron injection into the electron transport layer of Alq[sub 3] [tris(8-hydroxyquinoline)-aluminum] via LiF interlayers are studied by means of I-V characteristics, secondary ion mass spectroscopy (SIMS), and Kelvin probe measurements. Devices for single carrier injection were prepared using aluminum electrodes, Alq[sub 3] electron transport layers, and thin intermediate layers of LiF. It was found that devices deposited in the order Alq[sub 3]-LiF-aluminum have a much higher electron injection capability than structures deposited in the order aluminum-LiF-Alq[sub 3]. SIMS depth profile analysis reveals that the evaporation of Al on LiF leads to a spatial separation of Li and F probably induced by a chemical reaction of Al with LiF. Simple thermodynamic calculations support the energetic feasibility of such a reaction. Titanium cathodes in the same layer sequence also exhibit electron injection enhancement, probably due to their similar chemical reactivity. However, electron injection from Ag electrodes is not significantly improved by the introduction of a LiF interlayer. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Biogeomorphic ecosystems (e.g. rivers, salt marshes, mangroves and coastal dunes) are shaped by feedbacks between geomorphology and engineer plants that occur at various spatiotemporal scales. The classical bivariate and multivariate statistical methods currently used in biogeomorphology do not permit clear identification of reciprocal causality between geomorphic and biological variables. The aim of this article is to present the potential of the cross‐lagged panel model (CLPM) to estimate reciprocal associations (causality) between one geomorphic and one biological variable over time. This tool, which originates from behavioural, social, medical and educational sciences, has clear potential as a novel approach to causal analysis in the context of biogeomorphic ecosystems. We provide a case study of the application of CLPM for analysing biogeomorphic feedbacks between topography and Populus nigra L. physiognomy on a wooded point bar of the Garonne River, France. © 2018 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Climate change and river regulation are negatively impacting riparian vegetation. To evaluate these impacts, process-based models are preferred over data-driven approaches. However, they require extensive knowledge about ecohydrological processes. To facilitate the implementation of such process-based models, the key drivers of riparian woodland successional pathways across three river reaches, in Austria, Portugal, and Spain, were explored, employing two complementary approaches. The principal component analyses highlighted the importance of the physical gradients determining the placement of the succession phases within the riparian and floodplain zones. The generalized additive models revealed that the initial and pioneer succession phases, characteristic of the colonization stage, appeared in areas highly morphodynamic, close in height and distance to the water table, and with coarse substrate, whereas elder phases within the transitional and mature stages showed incremental differences, occupying less dynamic areas with finer substrate. The Austrian site fitted well the current successional theory (elder phases appearing sequentially further up and distant), but at the Portuguese site, the tolerance of the riparian species to drought and flash flood events governed their placement. Finally, at the Spanish site, the patchy distribution of the elder phases was the remnants of formative events that reshaped the river channel. These results highlight the complex relationships between flow regime, channel morphology, and riparian vegetation. The use of succession phases, which rely on the sequential evolution of riparian vegetation as a response to different drivers, may be potentially better reproducible, within numerical process-based models, and transferable to other geographical regions. [ABSTRACT FROM AUTHOR]

Background: Induction treatment with rabbit polyclonal antithymocyte globulins (ATGs) is frequent used in kidney transplant recipients with donorspecific HLA antibodies and shows acceptable outcomes. The two commonly used ATGs, Thymoglobulin and ATG-F have slightly different antigen profile and antibody concentrations. The two compounds have never been directly compared in a prospective trial in immunological high-risk recipients. Therefore we performed a prospective randomized controlled study comparing the two compounds in immunological high-risk kidney recipients in terms of safety and efficacy. Methods: Immunological high-risk kidney recipients, defined as the presence of HLA DSA but negative CDC-B and T-cell crossmatches were randomized 1:1 to receive ATG-F or Thymoglobulin. Maintenance immunosuppressive therapy consisted of tacrolimus, mycophenolate mofetil and steroids. Results: The per-protocol analysis included 35 patients. There was no immediate infusion reaction observed with both compounds. No PTLD or malignancy occurred during the follow-up in both groups. The incidence of viral and bacterial infections was similar in both groups (p = 0.62). The cumulative incidence of clinical and subclinical antibody mediated allograft rejection as well as T-cell mediated allograft rejection during the first year between ATG-F and Thymoglobulin was similar (35% versus 19%; p = 0.30 and 11% versus 18%; 0.54 respectively). The two-year graft function was similar with a median eGFR of 56 ml/min/1.73m2 (range 21–128) (ATG-F-group) and 51 ml/min/1.73m2 (range 22–132) (Thymo-group) (p = 0.69). Conclusion: We found no significant differences between the compared study drugs for induction treatment in immunological high-risk patients regarding safety and efficacy during follow-up with good allograft function at 2 years after transplantation. [ABSTRACT FROM AUTHOR]

A palaeoenvironmental study of a palaeochannel within the lower alluvial floodplain of the Allier River, France, has been carried out at a high temporal resolution. Research was based upon a multi-proxy approach using different sedimentological (magnetic susceptibility, sediment texture and loss on ignition) and palaeoecological (pollen, non-pollen palynomorphs (NPPs), diatoms – indicators). The palaeochannel was dated from six radiocarbon dates and spans from the second to the eleventh century AD. The cultural landscape history of this floodplain and the progressive hydrological disconnection of the palaeochannel between the Antiquity and the early Middle Ages could be reconstructed according to several characteristic environmental phases. Co-inertia analysis linking pollen, NPPs and diatom corroborated the significant co-structure of these proxies and allowed to distinguish functional palaeoecological groups in terms of landscape openness, on-site aquatic and hygrophilous vegetation, riparian woodland, soil moisture and grazing pressure. Results obtained underpin the importance of grazing as a major agent of landscape change in floodplains, especially since the ninth century AD, when the clearance of the riparian woodland is attested. Gallo-Roman and Late-Antiquity land-use systems, on the contrary, allowed for the preservation of riparian fluvial landscapes. [ABSTRACT FROM PUBLISHER]

The article discusses the role of neutrophil extracellular traps (NETs) in Papillon-Lefevre syndrome (PLS), a rare autosomal recessive disease characterized by erythematous palmoplantar hyperkeratosis. It mentions investigation of neutrophils from a clinically diagnosed PLS patient. It further reveals that that neutrophils from a PLS patient are capable of releasing NETs.

Background: Literature review suggests that adherence to immunosuppressive drugs may be lower in recipients of living than of deceased donor kidney grafts, possibly because of profile differences. Objective: To compare the level of immunosuppressive adherence levels between patients with deceased and living (-related; -unrelated) donor grafts in Switzerland. Methods: Using data from two similar cross-sectional studies at two transplant centers in Switzerland, the level of adherence between the two groups was compared. Medication adherence was assessed by self-report or electronic monitoring. Possible explanatory factors included age, beliefs regarding immunosuppressive drugs, depressive symptomatology, pre-emptive transplantation, and the number of transplants received, were also considered. Data were analyzed using logistic regression analysis. Results: Unadjusted non-adherence odds were 2 to 3 times higher in living-related than deceased donor transplantation (ORs: 2.09-3.05; p<0.05). Adjustment for confounders showed that these differences were associated most with the younger age of living-related subjects and the belief that immunosuppressive drugs are less important for living-related donations. Conclusion: There is a lower immunosuppressive adherence in recipients of living-related donor kidneys, possibly owing to differences in patient profile (ie, health beliefs regarding their immunosuppressive needs), knowledge of which may enhance adherence if addressed. [ABSTRACT FROM AUTHOR]

ABSTRACT Patterns of native and exotic plant species richness and cover were examined in relation with ecosystem engineer effects of pioneer vegetation within the Mediterranean gravel bed river Tech, South France. The floristic composition was characterized according to two distinct vegetation types corresponding to two habitats with contrasted conditions: (i) open and exposed alluvial bars dominated by herbaceous communities; and (ii) islands and river margins disconnected from annual hydrogeomorphic disturbances and covered by woody vegetation. A significant positive correlation between exotic and native plant species richness and cover was observed for both vegetation types. However, significant differences in native and exotic species richness and cover were found between these two vegetation types. Higher values of total species richness and Shannon diversity were attained within the herbaceous vegetation type than within the woody type. These differences are most likely related to changes in local exposure to hydrogeomorphic disturbances driven by woody engineer plant species and to vegetation succession. A lower exotic species cover within the woody vegetation type than within the herbaceous type suggested an increase of resistance to invasion by exotic species during the biogeomorphic succession. The engineer effects of woody vegetation through landform construction resulted in a decrease of alpha ( α) diversity at the patch scale but, in parallel, caused an increase in gamma ( γ) diversity at the scale of the studied river segment. Our study corroborates recent investigations that support the theory of biotic acceptance of exotic species by native species at the local scale (generally <10 m2) within heterogeneous and disturbed environments. Furthermore, we suggest that in riparian contexts such as the River Tech exotic species trapp sediment at the same time as native species and thus contribute to the increase in ecosystem resistance during the biogeomorphic succession. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Aim: Reactivation of latent BK virus in kidney-transplanted patients results in severe graft dysfunction. The role of retroviruses infecting also latently target cells is not investigated so far in this setting. We determined the presence or induction of retroviruses in sera of immunosuppressed patients with renal allografts at the timepoint of organ rejection or on going polyomavirus nephropathy. Patients and methods: Sera of patients with acute kidney rejection or polyomavirus nephropathy (n = 25) and controls (n = 8) were tested for re verse transcriptase activity by the ultrasensitive product enhanced reverse transcriptase (PERT) as say. In parallel, kidney biopsies were investigated for histological signs of kidney rejection or polyomavirus nephropathy con firmed by either immunofluorescence or immunohistochemistry. Results: None of the investigated sera, specifically those of patients with on going BK virus nephropathy, indicated reverse transcriptase activity. Conclusion: Our results do not support the idea of the induction of known or unknown retro viruses in patients with kidney transplantation, even under highly immunosuppressive therapies. [ABSTRACT FROM AUTHOR]

Background: C4d deposits in renal transplants are known to be an independent risk factor of graft failure. The current analysis evaluates the impact of C4d deposits on graft function and survival in renal transplants without morphological signs of rejection. Methods: We retrospectively analyzed diagnostic transplant biopsies performed due to allograft dysfunction from June 1994 to June 2001 at the University Hospital in Basel. Study group: Grafts/patients with focal or diffuse positivity of C4d along peritubular capillaries; absence of morphological signs of acute cellular and/or humoral rejection; up to 3 year follow-up analysis post index biopsy. Patients treated with anti-rejection therapy or an increase in maintenance immunosuppression postbiopsy (intervention group = IG) were compared to patients with unaltered immunosuppression (standard group = SG). Results: Study group: 22 biopsies/patients out of 400 biopsies (5%) were included into the study, 17 in the SG and 5 in the IG. Patient survival (1-/3-years): SG: 100/94%, IG: 80/80%; graft survival censored for death (1-/3-years): SG: 82.5/68.8%, IG: 100/100%; serum creatinine (μmol/l) at index biopsy/1-year/3-years: SG: 221 ± 70/231 ± 103/245 ± 124, IG: 217 ± 100/143 ± 28/177 ± 55; acute rejection episodes within 1 year post index biopsy: SG: 4 (4 patients), IG: 1 (1 patient); all differences not significant. Low estserum creatinine with in 4 weeks post index biopsy (IG vs. SG): 108 ± 25 vs. 181 ± 61, p = 0.02. Conclusions: C4d positivity in kidney transplants lacking histological evidence of acute rejection is not associated with rapid functional graft deterioration, even in untreated cases. However, anti-rejection therapy results in the improvement of kidney function. Thus, even in grafts with normal histology, the detection of C4d in diagnostic biopsies can be interpreted as a sign of ‘smoldering’ rejection that benefits from therapy. [ABSTRACT FROM AUTHOR]

The electronic trap distributions of the vapor deposited electron transport material Alq3 [tris(8-(hydroxyquinoline) aluminum] and hole transport material 1-NaphDATA [4,4′,4″-tris(N-(1-naphthyl)-N-phenylamino)-triphenylamine] have been analyzed by the fractional TSC method (thermally stimulated current) and the thermally stimulated luminescence (TL) technique. The obtained trap distributions can be described by a Gaussian distribution in case of Alq3 and two discrete trap levels in case of 1-NaphDATA. In the case of Alq3, a distinction between the trapped charge carrier polarity was possible. A correlation between the I–V curves of electron- and hole-only devices and the respective trap distributions suggests that the trap distribution is responsible for the shape of the observed current–voltage characteristics. It will be shown that the observed trap states cannot be explained by intrinsic tail states of regular HOMO and LUMO levels. [Copyright &y& Elsevier]

This paper investigates vegetational, hydrological and geomorphological influences on sedimentation within the river margin of a 1.7 km, sinuous reach of the River Severn, UK. The empirical study was designed to investigate the impact of the following factors on riparian zone sediment deposition: (i) land use, (ii) channel planform location, (iii) the flood stage at which inundation occurs, (iv) submersion time, (v) flood event timing and ordering. Sedimentation was observed using sediment traps located on 48 sample plots within four sites (one on pasture, one within a poplar plantation and two within mixed riparian woodland) during four flood events. A total of 177 observations of sediment deposition were analysed for total dry weight of sediment, particle size and organic content. All sample plots were located within a 30 m wide ribbon of the riparian zone, immediately above the limit of perennial vegetation (i.e. the edge of the low flow channel). Patterns and rates of sedimentation differed between flood events. Whilst significant differences were found in sedimentation between the four sample sites, these were interpreted to be more a function of planform location than land use. The most marked variations were found in the quantity, particle size and organic content of deposited sediment according to riparian zone cross-sectional morphology and elevation. Highest sedimentation occurred within a 1 m elevation band that correlated with the channel-ward face of a morphological bench. Percentage sand content of deposited sediment exhibited a change from approximately 35% in a band extending from the low flow channel to a 1 m elevation above the morphological bench edge to approximately 10% above this level. Organic matter content was low (less than 5%) in sediment deposited up to a 1 m elevation above the edge of the morphological bench. Above this level, there was a gradual increase in organic matter content. These observations suggest a link between the form of the riparian zone and the sedimentation process. The relative influence of vegetational, hydrological and geomorphological influences on sedimentation characteristics are also discussed. Copyright © 2001 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]