Control of Upconversion Luminescence for Photovoltaics using Photonic Structures

Der Prozess der Hochkonversion ist ein Ansatz zur Effizienz-Steigerung von Solarzellen. Photonen, deren Energie unterhalb der Bandlücke der Solarzelle liegt, können durch die Hochkonversion zur Stromerzeugung in der Solarzelle nutzbar gemacht werden. Bei der Hochkonversion werden mehrere niederenergetische Photonen absorbiert und ein hochenergetisches emittiert. Im Weiteren können photonische Strukturen die Eigenschaften von Lumineszenzphänomenen beeinflussen. Diese Möglichkeit ist insbesondere für nichtlineare Lumineszenzprozesse von Interesse, wie für die Photonen-Hochkonversion, und kann deren Effizienz erhöhen. Die Anpassung des Designs der photonischen Struktur im Hinblick auf eine Maximierung der Hochkonversions-Effizienz-Erhöhung, erfordert eine gezielte Designoptimierung, für welche bisher kein passendes Simulationsmodell in der Literatur zur Verfügung stand. Gegenstand dieser Arbeit ist die Weiterentwicklung eines umfassenden theoretischen Modells zur Analyse der photonischen Effekte auf die Hochkonversionsdynamik, zudem die experimentelle Realisierung von photonischen Hochkonvertern und die Validierung des theoretischen Modells in weit gefassten Parameter-Scans. Zu diesem Zweck wird die Hochkonversionsdynamik in $\beta$-NaYF$_{4}$:Er$^{3+}$ untersucht und die potenzielle Erhöhung der Hochkonversionseffizienz durch die Einbettung des Hochkonverters in eine eindimensionale (1D) photonische Struktur. Diese photonische Struktur besteht aus alternierenden Schichten von Poly(methyl methacrylat) mit eingebetteten Hochkonverter-Nanopartikeln und einer Zwischenschicht mit höherem Brechungsindex. Das Modell beschreibt die photonischen Effekte der lokalen Energiedichteerhöhung und der modifizierten lokalen optischen Zustandsdichte auf die interne Hochkonversionsdynamik in einem Ratengleichungsmodell. Zudem berücksichtigt das Modell Produktionsungenauigkeiten über Monte-Carlo Simulationen. Die Analyse dieser Arbeit zeigt, dass der Effekt der modifizierten lokalen optischen Zustandsdichte in einem optimierten Design die Wahrscheinlichkeit von spontanen Emissionsprozessen derart beeinflussen kann, dass die maximal mögliche Hochkonversionsquantenausbeute (UCQY) signifikant erhöht wird, um 0.8% absolut für einen hochbrechendes Medium innerhalb der Bragg Struktur mit einem Brechungsindex von 1.8, und mehr für einen höheren Brechungsindex Kontrast. Darüber hinaus kann die Struktur angepasst werden, sodass durch die lokale Energiedichteerhöhung die maximale UCQY bereits bei einer deutlich niedrigeren einfallenden Bestrahlungsstärke auftritt. Um eine Validierung des Simulationsmodells durchzuführen, werden Bragg-Strukturen mit eingebetteten Core-Shell Hochkonverter-Nanopartikeln untersucht und in hoher Präzision experimentell hergestellt. Die simulierte Wirkung der lokalen Energiedichteerhöhung und der modifizierten lokalen optischen Zustandsdichte auf die interne Hochkonversionsdynamik ist in allen durchgeführten Parameter-Scans sichtbar. Insgesamt wurden 2480 verschiedene Paramter Kombinationen untersucht, in einem Scan der Bestrahlungsstärke, sowie der Anregungswellenlänge an 40 verschiedenen Proben-Designs. Die gemessene Erhöhung der Hochkonversionsphotolumineszenz (UCPL) beträgt 82$\pm$24% der simulierten Erhöhung, im Mittel der 2480 untersuchten verschiedenen Parameter-Kombinationen. Die Ergebnisse dieser Arbeit lassen Bragg-Strukturen als sinnvoll und vielversprechend für photonische Hochkonverter für eine Anwendung in der Photovoltaik erscheinen, da i) die Menge des Hochkonverter-Materials flexibel angepasst werden kann und somit eine hohe Gesamtabsorption durch den Hochkonverter erreicht werden kann, ii) eine hohe UCPL Erhöhung von über 300-fach bei nur einer Sonne Bestrahlungsstärke erreicht werden kann, mit einer angenommenen Produktionsungenauigkeit von $\sigma$ = 1 nm, iii) Bei jeder Bestrahlungsstärke bis hinunter zu etwa 10 Sonnen, ein Bragg-Struktur-Design gefunden werden kann durch welches annähernd die maximal mögliche UCQY erreicht wird, iv) die spektrale Breite der Erhöhungseffekte angepasst werden kann, sodass der Kernbereich der Absorption des Hochkonverters in den Erhöhungsbereich fällt und v) eine effiziente Licht-Einkopplung bis hin zu hohen Einfallswinkeln von ca 30$^{\circ}$ möglich ist. Die Kernaussagen dieser Arbeit können auf jedes Hochkonvertermaterial mit einer ähnlichen Konfiguration von Energiezuständen angewendet werden. Die Analyse im Rahmen dieser Arbeit bezieht sich auf eine 1D photonische Struktur, kann allerdings auf jede photonische Struktur, auch 2D und 3D Designs angewendet werden. Daher eröffnet das validierte Simulationsmodell nun die Möglichkeit eine präzise Optimierung des Designs von photonischen Strukturen für diverse Hochkonverter-Materialien und Zielanwendungen durchzuführen

Preventive health examinations: protocol for a prospective cross-sectional study of German employees aged 45 to 59 years (Ü45-check)

Objective: Early identification of health-related risk factors is of great importance for maintaining workability. Screening examinations can help to detect diseases at an early stage and provide more needs-based recommendations. This study aims (1) to assess the individual need for prevention or rehabilitation based on preventive health examinations compared to a questionnaire survey, (2) to assess the results of the preventive health examinations compared to the Risk Index – Disability Pension (RI-DP), (3) to assess the results of the questionnaire survey compared to the RI-DP, (4) to assess the general health status of the sample (target population > 1,000) in German employees aged 45–59, (5) to identify the most common medical conditions. A further study question aims, and (6) to investigate the general health status of the specific occupational groups. Methods: Comprehensive diagnostics including medical examination, anamnesis, anthropometric measurements, bioelectrical impedance analysis (BIA), handgrip strength, resting electrocardiogram (ECG), resting blood pressure, pulse wave velocity (PWV), and laboratory blood analyses added by a questionnaire are conducted. The research questions are analyzed in an exploratory manner. Results and conclusion: We expect that the results will allow us to formulate recommendations regarding screening for prevention and rehabilitation needs on a more evidence-based level. Clinical Trial Registration: DRKS ID: DRKS00030982.Peer Reviewe

Wound Healing Process After Thermomechanical Skin Ablation

Background and Objectives: Energy-based devices have been widely applied for skin ablation. A novel ablation technique based on thermomechanical principles (Tixel©) has been recently developed. The aim of this study was to examine the wound-healing process and clinical aspects after thermomechanical skin ablation. Study Design/Materials and Methods: Six female participants were treated with Tixel© on healthy skin of the dorsal side of the right forearm in a single session with a 600 µm protrusion and 12 milliseconds pulse. The treated area was examined with confocal laser scanning microscopy on day 1, 2, 7, and 14 after treatment. Clinical symptoms were evaluated at the same time-points. Results: All patients developed erythema and mild edema on the treated areas, which completely disappeared within 14 days. No post-inflammatory hyperpigmentation or scarring was observed. Thermomechanical skin ablation resulted in the formation of homogeneous micro-ablation zones. Two weeks after ablation, the honeycomb patterns of the epidermis in all examined layers was thoroughly restored. Thus, wound-healing was completed. Conclusions: Wound healing after thermomechanical skin ablation is much faster compared with other fractionated ablation methods. Treatment intervals of 2–4 weeks could be recommended

Role of IL‐17 in atopy—A systematic review

Purpose of Review: Atopy is defined as the genetic predisposition to react with type I allergic diseases such as food-, skin-, and respiratory allergies. Distinct molecular mechanisms have been described, including the known Th2 driven immune response. IL-17A (IL-17) is mainly produced by Th17 cells and belongs to the IL-17 family of cytokines, IL-17A to F. While IL-17 plays a major role in inflammatory and autoimmune disorders, more data was published in recent years elucidating the role of IL-17 in allergic diseases. The present study aimed to elaborate specifically the role of IL-17 in atopy. Methods: A systematic literature search was conducted in MEDLINE, Embase, and Cochrane Central Register of Controlled Trials, regarding IL-17 and atopy/allergic diseases. Results: In total, 31 novel publications could be identified (food allergy n = 3, allergic asthma n = 7, allergic rhinitis [AR] n = 10, atopic dermatitis [AD] n = 11). In all allergic diseases, the IL-17 pathway has been investigated. Serum IL-17 was elevated in all allergic diseases. In AR, serum and nasal IL-17 levels correlated with the severity of the disease. In food allergies, serum IL-17E was also elevated in children. In AD, there is a trend for higher IL-17 values in the serum and skin specimen, while it is more expressed in acute lesions. In allergic asthma, serum IL-17 levels were increased. In two studies, higher serum IL-17 levels were found in severe persistent asthmatic patients than in intermittent asthmatics or healthy controls. Only one therapeutic clinical study exists on allergic diseases (asthma patients) using a monoclonal antibody against the IL-17 receptor A. No clinical efficacy was found in the total study population, except for a subgroup of patients with (post-bronchodilator) high reversibility. Summary: The role of IL 17 in the pathogenesis of allergic diseases is evident, but the involvement of the Th17 cytokine in the pathophysiological pathway is not conclusively defined. IL-17 is most likely relevant and will be a clinical target in subgroups of patients. The current data indicates that IL-17 is elevated more often in acute and severe forms of allergic diseases

Increased plasma colloid osmotic pressure facilitates the uptake of therapeutic macromolecules in a xenograft tumour model

Elevated tumor interstitial fluid pressure (TIFP) is a characteristic of most solid tumors. Clinically, TIFP may hamper the uptake of chemotherapeutic drugs into the tumor tissue reducing their therapeutic efficacy. In this study, a means of modulating TIFP to increase the flux of macromolecules into tumor tissue is presented, which is based on the rationale that elevated plasma colloid osmotic pressure (COP) pulls water from tumor interstitium lowering the TIFP. Concentrated human serum albumin: (20% HSA), used as an agent to enhance COP, reduced the TIFP time-dependently from 8 to 2 mm Hg in human tumor xenograft models bearing A431 epidermoid vulva carcinomas. To evaluate whether this reduction facilitates the uptake of macromolecules, the intratumoral distribution of fluorescently conjugated dextrans (2.5 mg/ml) and cetuximab (2.0 mg/ml) was probed using novel time domain nearinfrared fluorescence imaging. This method permitted discrimination and semiquantification of tumor-accumulated conjugate from background and unspecific probe fluorescence. The coadministration of 20% HSA together with either dextrans or cetuximab was found to lower the TIFP significantly and increase the concentration of the substances within the tumor tissue in comparison to control tumors. Furthermore, combined administration of 20%HSA plus cetuximab reduced the tumor growth significantly in comparison to standard cetuximab treatment. These data demonstrate that increased COP lowers the TIFP within hours and increases the uptake of therapeutic macromolecules into the tumor interstitium leading to reduced tumor growth. This model represents a novel approach to facilitate the delivery of therapeutics into tumor tissue, particularly monoclonal antibodies

Increased plasma colloid osmotic pressure facilitates the uptake of therapeutic macromolecules in a xenograft tumour model

Elevated tumor interstitial fluid pressure (TIFP) is a characteristic of most solid tumors. Clinically, TIFP may hamper the uptake of chemotherapeutic drugs into the tumor tissue reducing their therapeutic efficacy. In this study, a means of modulating TIFP to increase the flux of macromolecules into tumor tissue is presented, which is based on the rationale that elevated plasma colloid osmotic pressure (COP) pulls water from tumor interstitium lowering the TIFP. Concentrated human serum albumin: (20% HSA), used as an agent to enhance COP, reduced the TIFP time-dependently from 8 to 2 mm Hg in human tumor xenograft models bearing A431 epidermoid vulva carcinomas. To evaluate whether this reduction facilitates the uptake of macromolecules, the intratumoral distribution of fluorescently conjugated dextrans (2.5 mg/ml) and cetuximab (2.0 mg/ml) was probed using novel time domain nearinfrared fluorescence imaging. This method permitted discrimination and semiquantification of tumor-accumulated conjugate from background and unspecific probe fluorescence. The coadministration of 20% HSA together with either dextrans or cetuximab was found to lower the TIFP significantly and increase the concentration of the substances within the tumor tissue in comparison to control tumors. Furthermore, combined administration of 20%HSA plus cetuximab reduced the tumor growth significantly in comparison to standard cetuximab treatment. These data demonstrate that increased COP lowers the TIFP within hours and increases the uptake of therapeutic macromolecules into the tumor interstitium leading to reduced tumor growth. This model represents a novel approach to facilitate the delivery of therapeutics into tumor tissue, particularly monoclonal antibodies.publishedVersio

Study protocol for a prospective, non-controlled, multicentre clinical study to evaluate the diagnostic accuracy of a stepwise two-photon excited melanin fluorescence in pigmented lesions suspicious for melanoma (FLIMMA study)

Introduction: Non-invasive, nanosecond, stepwise two-photon laser excitation of skin tissue was shown to induce melanin fluorescence spectra that allow for the differentiation of melanocytic nevi from cutaneous melanoma. Methods and analysis: This prospective, non-controlled, multicentre clinical study is performed to evaluate the diagnostic performance of the stepwise two-photon excited melanin fluorescence in the detection of cutaneous melanoma. The comparator will be the histopathological diagnosis. A total of 620 pigmented skin lesions suspicious for melanoma and intended for excision will be enrolled. Ethics and dissemination: Ethics approval was provided by the local ethics committees of the medical faculties of the University of Tuebingen, Heidelberg and Berlin. Study registration: The FLIMMA study NCT02425475

A practical Java tool for small-molecule compound appraisal

The increased use of small-molecule compound screening by new users from a variety of different academic backgrounds calls for adequate software to administer, appraise, analyse and exchange information obtained from screening experiments. While software and spreadsheet solutions exist, there is a need for software that can be easily deployed and is convenient to use.The Java application cApp addresses this need and aids in the handling and storage of information on small-molecule compounds. The software is intended for the appraisal of compounds with respect to their physico-chemical properties, analysis in relation to adherence to likeness rules as well as recognition of pan-assay interference components and cross-linking with identical entries in the PubChem Compound Database. Results are displayed in a tabular form in a graphical interface, but can also be written in an HTML or PDF format. The output of data in ASCII format allows for further processing of data using other suitable programs. Other features include similarity searches against user-provided compound libraries and the PubChem Compound Database, as well as compound clustering based on a MaxMin algorithm.cApp is a personal database solution for small-molecule compounds which can handle all major chemical formats. Being a standalone software, it has no other dependency than the Java virtual machine and is thus conveniently deployed. It streamlines the analysis of molecules with respect to physico-chemical properties and drug discovery criteria; cApp is distributed under the GNU Affero General Public License version 3 and available from http://www.structuralchemistry.org/pcsb/. To download cApp, users will be asked for their name, institution and email address. A detailed manual can also be downloaded from this site, and online tutorials are available at http://www.structuralchemistry.org/pcsb/capp.php

Completing the view – histologic insights from circular AAA specimen including 3D imaging

Abdominal aortic aneurysm (AAA) is a pathologic enlargement of the infrarenal aorta with an associated risk of rupture. However, the responsible mechanisms are only partially understood. Based on murine and human samples, a heterogeneous distribution of characteristic pathologic features across the aneurysm circumference is expected. Yet, complete histologic workup of the aneurysm sac is scarcely reported. Here, samples from five AAAs covering the complete circumference partially as aortic rings are investigated by histologic means (HE, EvG, immunohistochemistry) and a new method embedding the complete ring. Additionally, two different methods of serial histologic section alignment are applied to create a 3D view. The typical histopathologic features of AAA, elastic fiber degradation, matrix remodeling with collagen deposition, calcification, inflammatory cell infiltration and thrombus coverage were distributed without recognizable pattern across the aneurysm sac in all five patients. Analysis of digitally scanned entire aortic rings facilitates the visualization of these observations. Immunohistochemistry is feasible in such specimen, however, tricky due to tissue disintegration. 3D image stacks were created using open-source and non-generic software correcting for non-rigid warping between consecutive sections. Secondly, 3D image viewers allowed visualization of in-depth changes of the investigated pathologic hallmarks. In conclusion, this exploratory descriptive study demonstrates a heterogeneous histomorphology around the AAA circumference. Warranting an increased sample size, these results might need to be considered in future mechanistic research, especially in reference to intraluminal thrombus coverage. 3D histology of such circular specimen could be a valuable visualization tool for further analysis

Long-term therapy of interferon-alpha induced pulmonary arterial hypertension with different PDE-5 inhibitors: a case report

BACKGROUND: Interferon alpha2 is widely used in hepatitis and high-risk melanoma. Interferon-induced pulmonary arterial hypertension as a side effect is rare. CASE PRESENTATION: We describe a melanoma patient who developed severe pulmonary arterial hypertension 30 months after initiation of adjuvant interferon alpha2b therapy. Discontinuation of interferon did not improve pulmonary arterial hypertension. This patient could be treated successfully with phosphodiesterase-5 inhibitor therapy. CONCLUSION: This is only the 5th case of interferon-induced pulmonary arterial hypertension and the first documented case where pulmonary arterial hypertension was not reversible after termination of interferon alpha2 therapy. If interferon alpha2 treated patients develop respiratory symptoms, pulmonary arterial hypertension should be considered in the differential diagnosis. For these patients phosphodiesterase-5 inhibitors, e.g. sildenafil or vardenafil, could be an effective therapeutic approach