Gesundheitszentrum Bitterfeld

Vascular calcifications (VCs) are actively regulated biological processes associated with crystallization of hydroxyapatite in the extracellular matrix and in cells of the media (VCm) or intima (VCi) of the arterial wall. Both patterns of VC often coincide and occur in patients with type II diabetes, chronic kidney disease, and other less frequent disorders; VCs are also typical in senile degeneration. In this article, we review the current state of knowledge about the pathology, molecular biology, and nosology of VCm, expand on potential mechanisms responsible for poor prognosis, and expose some of the directions for future research in this area.

ABSTRACT Grid‐parity is a very important milestone for further photovoltaic (PV) diffusion. A grid‐parity model is presented, which is based on levelized cost of electricity (LCOE) coupled with the experience curve approach. Relevant assumptions for the model are given, and its key driving forces are discussed in detail. Results of the analysis are shown for more than 150 countries and a total of 305 market segments all over the world, representing 98.0% of world population and 99.7% of global gross domestic product. High PV industry growth rates enable a fast reduction of LCOE. Depletion of fossil fuel resources and climate change mitigation forces societies to internalize these effects and pave the way for sustainable energy technologies. First grid‐parity events occur right now. The 2010s are characterized by ongoing grid‐parity events throughout the most regions in the world, reaching an addressable market of about 75–90% of total global electricity market. In consequence, new political frameworks for maximizing social benefits will be required. In parallel, PV industry tackle its next milestone, fuel‐parity. In conclusion, PV is on the pathway to become a highly competitive energy technology. Copyright © 2012 John Wiley & Sons, Ltd.

Abstract In this Letter, we report that both thermal atomic layer deposition (ALD) with H 2 O, and plasma ALD with an O 2 plasma, can be used to deposit Al 2 O 3 for a high level of surface passivation of crystalline silicon (c‐Si). For 3.5 Ω cm n‐type c‐Si, plasma ALD Al 2 O 3 resulted in ultralow surface recombination velocities of S eff < 0.8 cm/s. Thermal ALD Al 2 O 3 also showed an excellent passivation level, with S eff < 2.5 cm/s. In contrast to plasma ALD Al 2 O 3 , thermal ALD Al 2 O 3 provides some surface passivation in the as‐deposited state, although annealing is required to activate it to the full extent. For thermal ALD, the optimal temperature for this anneal was found to be slightly lower, ∼375 °C, than for plasma ALD Al 2 O 3 , ∼425 °C. The minimal Al 2 O 3 thickness without compromising the passivation properties was 5 nm for plasma ALD Al 2 O 3 , whereas for thermal ALD, films >10 nm were required. Thermal stability against a high temperature firing step was demonstrated for ultrathin thermal and plasma ALD Al 2 O 3 films of 5 nm by S eff < 9.2 and < 6.5 cm/s, respectively. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The thermal and ultraviolet (UV) stability of crystalline silicon (c-Si) surface passivation provided by atomic layer deposited Al2O3 was compared with results for thermal SiO2. For Al2O3 and Al2O3/a-SiNx:H stacks on 2 Ω cm n-type c-Si, ultralow surface recombination velocities of Seff<3 cm/s were obtained and the passivation proved sufficiently stable (Seff<14 cm/s) against a high temperature “firing” process (>800 °C) used for screen printed c-Si solar cells. Effusion measurements revealed the loss of hydrogen and oxygen during firing through the detection of H2 and H2O. Al2O3 also demonstrated UV stability with the surface passivation improving during UV irradiation.

Abstract Multicrystalline standard p‐type silicon solar cells, which undergo a potential induced degradation, are investigated by different methods to reveal the cause of the degradation. Microscopic local ohmic shunts are detected by electron‐beam‐induced current measurements, which correlate with the sodium distribution in the nitride layer close to the Si surface imaged by time‐of‐flight secondary ion mass spectroscopy. The results are compatible with a model of the formation of a charge double layer on or in the nitride, which inverts the emitter. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Abstract The cell performance of organic‐inorganic hybrid photovoltaic devices based on CdSe nanocrystals and the semiconducting polymer poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐ 4H ‐cyclopenta[2,1‐ b ;3,4‐ b′ ]‐dithiophene)‐ alt ‐4,7‐(2,1,3‐benzothiadiazole)] (PCPDTBT) is strongly dependent on the applied polymer‐to‐nanocrystal loading ratio and the annealing temperature. It is shown here that higher temperatures for the thermal annealing step have a beneficial impact on the nanocrystal phase by forming extended agglomerates necessary for electron percolation to enhance the short‐circuit current. However, there is a concomitant reduction of the open‐circuit voltage, which arises from energy‐level alterations of the organic and the inorganic component. Based on quantum dots and PCPDTBT, we present an optimized organic–inorganic hybrid system utilizing an annealing temperature of 210 °C, which provides a maximum power conversion efficiency of 2.8%. Further improvement is obtained by blending nanocrystals of two different shapes to compose a favorable n‐type network. The blend of spherical quantum dots and elongated nanorods results in a well‐interconnected pathway for electrons within the p‐type polmer matrix, yielding maximum efficiencies of 3.6% under simulated AM 1.5 illumination.

The standard system architecture of PV installations exposes solar modules to bias voltages of several hundred volts. Recently it became apparent that high bias voltages can have negative effects on the long-term performance of standard screen-printed crystalline silicon solar cells. This paper focuses on the study of this potential induced degradation effect (PID) under laboratory conditions. A corona-discharge assembly was used to polarize mini modules as well as a setup to expose 60-cell modules to high bias under wet conditions. Different encapsulation setups and cell process variations are studied to identify the necessary components leading to PID. I-V measurements, electroluminescence imaging and dark lock-in thermography are employed to obtain detailed characteristics of PID. A correlation between local current loss and shunt conductivity was found. Options to prevent PID on module and cell levels were found and verified experimentally.

A generalized solar cell model for excitonic and classical bipolar solar cells describes the combined transport and interaction of electrons, holes, and excitons in accordance with the principle of detailed balance. Conventional inorganic solar cells, single-phase organic solar cells and bulk heterojunction solar cells, i.e., nanoscale mixtures of two organic materials, are special cases of this model. For high mobilities, the compatibility with the principle of detailed balance ensures that our model reproduces the Shockley-Queisser limit irrespective of how the energy transport is achieved. For less ideal devices distinct differences become visible between devices that are described by linear differential equations and those with nonlinear effects, such as a voltage-dependent collection in bipolar $p\text{\ensuremath{-}}i\text{\ensuremath{-}}n$-type devices. These differences in current-voltage characteristics are also decisive for the validity of the reciprocity theorem between photovoltaic quantum efficiency and electroluminescent emission. Finally, we discuss the effect of band offset at the heterointerface in a bulk heterojunction cell and the effect of the average distances between these heterointerfaces on the performance of a solar cell in order to show how our detailed balance model includes also these empirically important quantities.

Neutral Pt(II) complexes bearing tridentate dianionic 2,6-bis(1H-1,2,4-triazol-5-yl)pyridine and ancillary alkyl-substituted pyridine ligands have been synthesized and characterized. They show bright green emission, reaching 73% photoluminescence quantum yield in deareated chloroform solution, which can be assigned to a predominantly metal-perturbed ligand-centered phosphorescence. We have followed two strategies to preserve the spectral purity of the monomeric species by varying the substituents on the chromophoric or on the ancillary ligands. However, variations in the substitution patterns only modestly affected the radiative and radiationless deactivation rate constants of the monomers. Photophysical and electrochemical properties have been measured for all the complexes and correlated with calculations using time-dependent density functional theory. The electroluminescence spectra of the brightest, nonaggregating derivative showed a better color purity than that of iridium(III) tris(phenylpyridine), thus proving that aggregation was hindered in a running electroluminescent device.

Abstract N‐type back‐contact back‐junction solar cells were processed with the use of industrially relevant structuring technologies such as screen‐printing and laser processing. Application of the low‐cost structuring technologies in the processing of the high‐efficiency back‐contact back‐junction silicon solar cells results in a drastic increase of the pitch on the rear cell side. The pitch in the range of millimetres leads to a significant increase of the lateral base resistance. The application of a phosphorus doped front surface field (FSF) significantly reduces the lateral base resistance losses. This additional function of the phosphorus doped FSF in reducing the lateral resistance losses was investigated experimentally and by two‐dimensional device simulations. Enhanced lateral majority carrier's current transport in the front n + diffused layer is a function of the pitch and the base resistivity. Experimental data show that the application of a FSF reduces the total series resistance of the measured cells with 3.5 mm pitch by 0.1 Ω cm 2 for the 1 Ω cm base resistivity and 1.3 Ω cm 2 for the 8 Ω cm base resistivity. Two‐dimensional simulations of the electron current transport show that the electron current density in the front n + diffused layer is around two orders of magnitude higher than in the base of the solar cell. The best efficiency of 21.3% was obtained for the solar cell with a 1 Ω cm specific base resistivity and a front surface field with sheet resistance of 148 Ω/sq. Copyright © 2008 John Wiley & Sons, Ltd.

OBJECTIVES: Mechanical properties of drug eluting stents (DES) will be measured to provide comparable numerical data to assess deliverability, and thus clinical performance. BACKGROUND: DES are routinely used in coronary interventions to reduce the rates of restenosis and target vessel revascularizations. Current research is primarily concerned with issues related to late stent thrombosis. However, mechanical properties of DES are a critical determinant of deliverability, and consequently the ultimate arbiter of their clinical performance. METHODS: Mechanical properties (pushability, trackability, crossability) were measured under standardized in-vitro conditions. The vessel models were derived from typical vessel anatomy but adapted to the individual tests. Additionally, profile and bending forces of the stent segment of the delivery system were measured. Seven different commercially available balloon-expandable coronary DES systems were included. All stents were 3.0 mm diameter with a stent length from 14 to 18 mm. RESULTS: The pushability expressed as the ratio of distal force at a specific proximal push force (4N) ranged between 38.66 and 18.53%. The trackability as the mean track-forces ranged from 0.551 N to 1.137 N. One stent system could not pass this test. The mean crossing forces at a 1.4 mm stenosis model ranged from 0.038 N up to 0.103 N. The mean crimped stent profiles ranged from 1.055 mm to 1.198 mm and the bending stiffness of the crimped stent was 17.22 to 47.20 Nmm2. CONCLUSION: Better understanding of mechanical properties of DES shall improve tactile skills of the interventionists during PCI and to improve criteria for DES selection in specific clinical settings.

The energy demand of photovoltaic (PV) systems is an important part of energy sustainability of PV systems. PV systems are considered sustainable energy systems when the produced energy is higher than the energy needed for the PV system on a life‐cycle basis. This paper employs financial learning curve concepts to determine the energy demand of major PV module technologies and systems. General PV module and PV system energy learning curves are calculated by weighting energy demand of different PV systems according to their share in PV market. Additionally, the contribution of module efficiency for reducing specific energy demand is considered. We find an energy learning rate of 17% for PV modules and 14% for PV systems on the basis of a market weighted mix of technologies and volumes. Energy payback time (EPBT) and energy return on energy investment (EROI) in 2010 and for the year 2020 are calculated via the energy learning rate and indicates a further significant progress in energetic productivity of PV systems. To the knowledge of the authors this publication shows for the first time that the energy consumption in PV manufacturing follows the log‐linear learning curve law similar to the evolution of production cost. This allows calculating EPBT or EROI for future prognoses. Furthermore, it shows significant evidence of how sustainable PV systems are and justifies their growing share in the energy market. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 914–923, 2016

Very low surface recombination velocities <6 and <11 cm/s were obtained for SiOx/a-SiNx:H stacks synthesized by plasma-enhanced chemical vapor deposition on low resistivity n- and p-type c-Si, respectively. The stacks induced a constant effective lifetime under low illumination, comparable to Al2O3 on p-type Si. Compared to single layer a-SiNx:H, a lower positive fixed charge density was revealed by second-harmonic generation measurements, while field-effect passivation was absent for a reference stack comprising thermally grown SiO2. The results indicate that hydrogenation of interface states played a key role in the passivation and remained effective up to annealing temperatures >800 °C.

Abstract. The oxidation of biogenic and anthropogenic compounds leads to the formation of secondary organic aerosol mass (SOA). The present study aims to investigate α-pinene, limonene, and m-cresol with regards to their SOA formation potential dependent on relative humidity (RH) under night- (NO3 radicals) and daytime conditions (OH radicals) and the resulting chemical composition. It was found that SOA formation potential of limonene with NO3 under dry conditions significantly exceeds that of the OH-radical reaction, with SOA yields of 15–30 % and 10–21 %, respectively. Additionally, the nocturnal SOA yield was found to be very sensitive towards RH, yielding more SOA under dry conditions. In contrast, the SOA formation potential of α-pinene with NO3 slightly exceeds that of the OH-radical reaction, independent from RH. On average, α-pinene yielded SOA with about 6–7 % from NO3 radicals and 3–4 % from OH-radical reaction. Surprisingly, unexpectedly high SOA yields were found for m-cresol oxidation with OH radicals (3–9 %), with the highest yield under elevated RH (9 %), which is most likely attributable to a higher fraction of 3-methyl-6-nitro-catechol (MNC). While α-pinene and m-cresol SOA was found to be mainly composed of water-soluble compounds, 50–68 % of nocturnal SOA and 22–39 % of daytime limonene SOA are water-insoluble. The fraction of SOA-bound peroxides which originated from α-pinene varied between 2 and 80 % as a function of RH. Furthermore, SOA from α-pinene revealed pinonic acid as the most important particle-phase constituent under day- and nighttime conditions with a fraction of 1–4 %. Other compounds detected are norpinonic acid (0.05–1.1 % mass fraction), terpenylic acid (0.1–1.1 % mass fraction), pinic acid (0.1–1.8 % mass fraction), and 3-methyl-1,2,3-tricarboxylic acid (0.05–0.5 % mass fraction). All marker compounds showed higher fractions under dry conditions when formed during daytime and showed almost no RH effect when formed during night.

The local breakdown of commercial silicon solar cells occurring at reverse voltages of only 3–4 V has been investigated by means of current-voltage measurements, dark lock-in thermography, and reverse-biased electroluminescence (ReBEL) with a spatial resolution on the micrometer-scale. It is shown that the origin of the local breakdown (so-called type I) can be traced back to a contamination of the wafer surface with Al particles prior to the phosphorous diffusion step. A model is presented explaining that the spectral maximum of ReBEL is within the visible range.

Abstract. This paper presents a new CAPRAM–GECKO-A protocol for mechanism auto-generation of aqueous-phase organic processes. For the development, kinetic data in the literature were reviewed and a database with 464 aqueous-phase reactions of the hydroxyl radical with organic compounds and 130 nitrate radical reactions with organic compounds has been compiled and evaluated. Five different methods to predict aqueous-phase rate constants have been evaluated with the help of the kinetics database: gas–aqueous phase correlations, homologous series of various compound classes, radical reactivity comparisons, Evans–Polanyi-type correlations, and structure–activity relationships (SARs). The quality of these prediction methods was tested as well as their suitability for automated mechanism construction. Based on this evaluation, SARs form the basis of the new CAPRAM–GECKO-A protocol. Evans–Polanyi-type correlations have been advanced to consider all available H atoms in a molecule besides the H atoms with only the weakest bond dissociation enthalpies (BDEs). The improved Evans–Polanyi-type correlations are used to predict rate constants for aqueous-phase NO3 and organic compounds reactions. Extensive tests have been performed on essential parameters and on highly uncertain parameters with limited experimental data. These sensitivity studies led to further improvements in the new CAPRAM–GECKO-A protocol but also showed current limitations. Biggest uncertainties were observed in uptake processes and the estimation of Henry's law coefficients as well as radical chemistry, in particular the degradation of alkoxy radicals. Previous estimation methods showed several deficits, which impacted particle growth. For further evaluation, a 1,3,5-trimethylbenzene oxidation experiment has been performed in the aerosol chamber “Leipziger Aerosolkammer” (LEAK) at high relative humidity conditions and compared to a multiphase mechanism using the Master Chemical Mechanism (MCMv3.2) in the gas phase and using a methylglyoxal oxidation scheme of about 600 reactions generated with the new CAPRAM–GECKO-A protocol in the aqueous phase. While it was difficult to evaluate single particle constituents due to concentrations close to the detection limits of the instruments applied, the model studies showed the importance of aqueous-phase chemistry in respect to secondary organic aerosol (SOA) formation and particle growth. The new protocol forms the basis for further CAPRAM mechanism development towards a new version 4.0. Moreover, it can be used as a supplementary tool for aerosol chambers to design and analyse experiments of chemical complexity and help to understand them on a molecular level.

Highly p-doped regions in multicrystalline silicon solar cells, such as the back surface field region, are analyzed by means of small angle beveling and micro-Raman spectroscopy. Small angle beveling and subsequent Secco etching are used to enhance the lateral resolution of the micro-Raman spectroscopic measurements and to investigate the microstructure of the back surface field region in detail. The position-dependent analysis of the free carrier concentrations within the back surface field region is based on the Raman specific Fano resonances. The Raman spectroscopic measurement results are compared to results obtained from electrochemical capacitance-voltage measurements, which allows a subsequent calibration of the Raman data for the quantitative analysis of the free carrier concentrations within the highly p-doped regions of silicon solar cells and other devices. Our investigations show that the free carrier as well as the dopant concentration profiles within the back surface field region exhibit a nearly step-functional shape instead of the extended gradient shape which the electrochemical capacitance-voltage measurements suggest. Moreover, we show that the shape of the back surface field is often influenced by grain boundaries and other defects that occur in multicrystalline silicon wafers.

OBJECTIVE: Muscles such as adductor magnus (AM), gluteus maximus (GM), rectus abdominis (RA), and abdominal external and internal oblique muscles are considered to play an important role in the treatment of stress urinary incontinence (SUI), and the relationship between contraction of these muscles and pelvic floor muscles (PFM) has been established in previous studies. Synergistic muscle activation intensifies a woman's ability to contract the PFM. In some cases, even for continent women, it is not possible to fully contract their PFM without involving the synergistic muscles. The primary aim of this study was to assess the surface electromyographic activity of synergistic muscles to PFM (SPFM) during resting and functional PFM activation in postmenopausal women with and without SUI. MATERIALS AND METHODS: This study was a preliminary, prospective, cross-sectional observational study and included volunteers and patients who visited the Department and Clinic of Urology, University Hospital in Wroclaw, Poland. Forty-two patients participated in the study and were screened for eligibility criteria. Thirty participants satisfied the criteria and were categorized into two groups: women with SUI (n=16) and continent women (n=14). The bioelectrical activity of PFM and SPFM (AM, RA, GM) was recorded with a surface electromyographic instrument in a standing position during resting and functional PFM activity. RESULTS: Bioelectrical activity of RA was significantly higher in the incontinent group than in the continent group. These results concern the RA activity during resting and functional PFM activity. The results for other muscles showed no significant difference in bioelectrical activity between groups. CONCLUSION: In women with SUI, during the isolated activation of PFM, an increased synergistic activity of RA muscle was observed; however, this activity was not observed in asymptomatic women. This may indicate the important accessory contribution of these muscles in the mechanism of continence.

Selective emitter cell architectures offer the opportunity of improved cell efficiency over standard cell architectures through improved blue response, reduced saturation current and lower contact resistance. However, few selective emitter cell concepts have been successfully adopted into high volume manufacturing, often due to the associated increase in process complexity and cost. This paper demonstrates that patterned ion implantation provides a roadmap to lower PV module and system $/Wp costs through improved cell efficiency and reduced manufacturing cost. Ion implanted cell efficiency improvements, which can be up to +1% absolute, are a result of not only the selective emitter cell architecture, but also improved emitter quality, oxide passivation and increased light collection area through the elimination of laser edge isolation. Manufacturing cost reductions result from reduced processing steps and improved process uniformity and cell binning.

Abstract Nuclear magnetic resonance (NMR) tracer desorption technique in combination with the traditional pulsed field gradient technique is applied to measure directly intracrystalline and long‐range molecular transport, as well as molecular exchange rates, between the individual crystallites in granulated molecular sieves. It is found that the granulation process leads to the formation of transport resistances on the external surface of the crystallites, which may be dramatically enhanced during their technical application. As an example, for granulated zeolite NaCaA the enhancement of such surface barriers under hydrothermal conditions and under the influence of a hydrocarbon atmosphere is studied. Since both intra‐ and intercrystalline transport are found to remain practically unaffected by this treatment, changes in the overall transport behavior are caused by the enhanced transport resistance on the external surface of the zeolite crystallites.