Laser-Induced Bromination of Organic Monolayers

Selbstorganisierende organische Monoschichten (Self-Assembled Monolayers, SAMs) können als Bindeglied zwischen anorganischen Festkörpern und organischen sowie biologischen Materialien dienen. Obwohl diese Schichten eine sehr einfache Nanostruktur darstellen, finden sich hierfür zahlreiche Anwendungen, denn sie erlauben es viele makroskopische Eigenschaften von Oberflächen zu ändern. Zum Aufbau von komplexen Nanostrukturen werden Verfahren zur Herstellung strukturierter SAMs benötigt. Dadurch eröffnen sich neue mögliche Anwendungen für SAMs z.B. in den Bereichen der Analytik, Biochemie und Elektronik. Laserverfahren verwenden fokussierte Laserstrahlen und erlauben eine schnelle und flexible Strukturierung organischer Monoschichten. Bei der photothermischen Laserstrukturierung wird im Gegensatz zu photochemischen Prozessen, bei denen die organischen Moleküle elektronisch angeregt werden, die lokale Temperaturerhöhung des Substrats ausgenutzt, um eine Reaktion, wie die Zersetzung oder Desorption der Moleküle zu erreichen. Aufgrund der nichtlinearen Abhängigkeit der ausgelösten Reaktionen von der Temperatur ist es in vielen Fällen möglich, Strukturen zu erzeugen, die erheblich kleiner sind als der verwendete Laserspot. In dieser Arbeit wird ein konstruktives Verfahren zur lokalen Funktionalisierung eines SAMs entwickelt. Hierbei wird das Laserverfahren auf einer aliphatischen Monoschicht in einem reaktiven Medium, nämlich Bromgas durchgeführt. Die Bromierung erlaubt die bequeme Einführung von vielen verschiedenen funktionellen Gruppen. Auf diese Weise ist eine chemische Strukturierung der SAMs und schließlich der Aufbau von komplexen Strukturen z.B. durch die Anbindung von Nanopartikeln und Biomolekülen möglich.Self-Assembled organic monolayers (SAMs) may serve as a link between inorganic solids and organic or biological materials. Although SAMs represent a very simple nanostructure, they find numerous applications, because they allow for a fine-tuning of macroscopic surface properties. To build up more complex nanostructures techniques are required, which allow for a fabrication of laterally patterned SAMs. This opens up new possibilities for applications of SAMs in the fields of analytics, biochemistry and electronics. Laser direct writing techniques, which are considered in this thesis, use focussed laser beams as a flexible and fast means in order to pattern SAMs under ambient conditions. In contrast to photochemical processes, where reactions are initiated by electronic excitations, photothermal processes rely on a local temperature rise in the substrate to initiate a reaction, e. g. a thermal decomposition or desorption of the SAM. Because of the nonlinear dependence of the reaction rate on the local temperature, structures, which are smaller than the laser spot, can be fabricated. The primary goal of this work was to develop a constructive method, which allows for local functionalization and hence chemical patterning of organic monolayers. In contrast to destructive methods, which rely on a decomposition of the monolayer, chemical patterning opens up an avenue to complex surface patterns such as multifunctional templates. As a prototype photothermal functionalization routine, laser processing of unfunctionalized aliphatic monolayers in a reactive bromine atmosphere is considered. Bromination of alkanes provides a convenient pathway toward a variety of different functional groups. Hence, overall, this approach provides a simple means to build up functional surface architectures, e.g. via attachment of nanoparticles or biomolecules

Characterizing the influence of charge extraction layers on the performance of triple‐cation perovskite solar cells

Selecting suitable charge transport layers and suppressing non-radiative recombination at interfaces with the absorber layer is vital for maximizing the efficiency of halide perovskite solar cells. In this study, high-quality perovskite thin films and devices are fabricated with different fullerene-based electron transport layers and different self-assembled monolayers as hole transport layers. Then, a comparative study of a significant variety of different electrical, optical, and photoemission-based characterization techniques is performed to quantify the properties of the solar cells, individual layers, and, importantly, the interfaces between them. In addition, the limitations and problems of the different measurements, the insights gained by combining different methods, and the different strategies for extracting information from the experimental raw data, are highlighted.Helmholtz AssociationDFGThe Spanish Ministry of Science and EducationAEIFederal Ministry for Economic Affairs and EnergyIsrael Ministry of EnergyEuropean UnionEuropean Research Counci

A universal strategy of perovskite ink‐substrate interaction to overcome the poor wettability of a self‐assembled monolayer for reproducible perovskite solar cells

Perovskite solar cells employing [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) self-assembled monolayer as the hole transport layer have been reported to demonstrate a high device efficiency. However, the poor perovskite wetting on Me-4PACz caused by poor perovskite ink interaction with the underlying Me-4PACz presents significant challenges for fabricating efficient perovskite devices. A triple co-solvent system comprising dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP) is employed to improve the perovskite ink-Me-4PACz coated substrate interaction and obtain a uniform perovskite layer. In comparison to DMF- and DMSO-based inks, the inclusion of NMP shows considerably higher binding energies of the perovskite ink with Me-4PACz as revealed by density-functional theory calculations. With the optimized triple co-solvent ratio, the perovskite devices deliver high power conversion efficiencies of >20%, 19.5%, and ≈18.5% for active areas of 0.16, 0.72, and 1.08 cm2, respectively. Importantly, this perovskite ink-substrate interaction approach is universal and helps in obtaining a uniform layer and high photovoltaic device performance for other perovskite compositions such as MAPbI3, FA1-xMAxPbI3-yBry, and MA-free FA1−xCsxPbI3-yBry.Helmholtz Association http://dx.doi.org/10.13039/501100001656PEROSEEDGerman Research FoundationProperPhotoMileEuropean CommissionEuropean Research Council under the Horizon Europe programHRI Allahabad, and DST‐SERB Fundin

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

Search for stop and higgsino production using diphoton Higgs boson decays

Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass

Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia