Decoupling of optoelectronic properties from morphological changes in sodium treated kesterite thin film solar cells

Sodium is typically used during the synthesis of kesterite thin films to enhance the performance of solar cells. As sodium tends to affect grain growth and morphology, it is difficult to analyse solely the electronic effects of sodium as dopant. To decouple the structural and electronic effects from each other, two processes were designed in this work to successfully incorporate sodium into a vacuum-processed Cu2ZnSnSe4absorber without changing the morphology. A thin layer of NaF is deposited before precursor deposition (Pre-NaF) or after absorber synthesis to undergo a post deposition treatment (NaF-PDT). While composition and distribution of matrix elements remain unchanged, the sodium concentration is increased upon sodium treatment up to 140 ppm as measured by inductively coupled plasma mass spectrometry. X-ray photoelectron spectroscopy showed that the surface composition was not altered. Within its detection limit, sodium was not present at the absorber surface. For a Pre-NaF sample measured with atom probe tomography a sodium concentration of 30 ppm was measured in a grain, suggesting that sodium might segregate at grain boundaries. The additional sodium content in the film leads to an increased acceptor concentration, which results in improved open-circuit voltage and fill factor.Financial support from the Swiss National Science Foundation (SNF) in the network of the Indo-Swiss Joint Research Programme (ISJRP) [IZLIZ2_157140/1] is gratefully acknowledged. T. Schwarz is grateful for the support of the German Research Foundation (DFG) [Contract GA 2450/1-1]. R. Caballero acknowledges financial support from Spanish MINECO within the Ramón y Cajal program [RYC-2011-08521], MINECO project WINCOST [ENE2016-80788-C5-2-R] and from Spanish Ministry of Education, Culture and Sport within the José Castillejo program [CAS 15/00070

Multiscale Analysis of Metal Oxide Nanoparticles in Tissue: Insights into Biodistribution and Biotransformation

Metal oxide nanoparticles have emerged as exceptionally potent biomedical sensors and actuators due to their unique physicochemical features. Despite fascinating achievements, the current limited understanding of the molecular interplay between nanoparticles and the surrounding tissue remains a major obstacle in the rationalized development of nanomedicines, which is reflected in their poor clinical approval rate. This work reports on the nanoscopic characterization of inorganic nanoparticles in tissue by the example of complex metal oxide nanoparticle hybrids consisting of crystalline cerium oxide and the biodegradable ceramic bioglass. A validated analytical method based on semiquantitative X‐ray fluorescence and inductively coupled plasma spectrometry is used to assess nanoparticle biodistribution following intravenous and topical application. Then, a correlative multiscale analytical cascade based on a combination of microscopy and spectroscopy techniques shows that the topically applied hybrid nanoparticles remain at the initial site and are preferentially taken up into macrophages, form apatite on their surface, and lead to increased accumulation of lipids in their surroundings. Taken together, this work displays how modern analytical techniques can be harnessed to gain unprecedented insights into the biodistribution and biotransformation of complex inorganic nanoparticles. Such nanoscopic characterization is imperative for the rationalized engineering of safe and efficacious nanoparticle‐based systems

Diquat Derivatives: Highly Active, Two-Dimensional Nonlinear Optical Chromophores with Potential Redox Switchability

In this article, we present a detailed study of structure−activity relationships in diquaternized 2,2′-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, π-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF_6^− salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense π → π^* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities β have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities β_0. The directly and indirectly derived β values are large and increase with the extent of π-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E_(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based β_0 responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by ‘off-diagonal’ β_(zyy) components. The most significant findings of these studies are: (i) β_0 values as much as 6 times that of the chromophore in the technologically important material (E)-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior

Modifizierte Dysenterie-Teilsanierung in einem Kernzuchtschweinebetrieb

In einem Brachyspira (B.) hyodysenteriae positiven Schweizer Kernzuchtbetrieb mit 170 Muttersauen und 600 Jungsauenaufzucht-/Mastplätzen wurde 2011 eine rollende Dysenteriesanierung über die Dauer von 12 Wochen durchgeführt. Neben einer vierwöchigen oralen Medikation (8.1 mg Tiamulin pro kg Körpergewicht) der auf dem Betrieb verbleibenden Schweine wurden sämtliche Stallungen gründlich gereinigt sowie die Restgülle mit Alzogur® (3 l/m3) und die Stalloberflächen mit Venno Vet 1 Super® (1.5 %) behandelt. Gleichzeitig wurde die Schadnager- und Fliegenbekämpfung intensiviert. Nach der Sanierung wurde der Betrieb während 6 Monaten mittels Untersuchung von Kottupfern von Durchfalltieren überwacht. In sämtlichen Kotproben konnten nach der Sanierung keine B. hyodysenteriae nachgewiesen werden. Die Sanierungskosten beliefen sich auf etwa CHF 104'500.–. Die Sanierung führte zu signifikant höheren Lebendtageszunahmen (+ 23.8 g, ± 10.1 g, P < 0.0001). Diese Leistungsverbesserung erbrachte einen jährlichen Mehrgewinn von CHF 18'500.–. On a Swiss nucleus sow breeding farm with 170 sows and 600 gilts/fatteners, an eradication of swine dysentery as modified partial depopulation was conducted in stages over a period of 12 weeks in 2011 after Brachyspira (B.) hyodysenteriae was detected in the herd. In addition to administering oral medication (8.1 mg tiamulin per kg body weight) for 4 weeks to the pigs remaining on the farm, all stables were cleaned thoroughly and the residual slurry was disinfected with Alzogur® (3 l/m3) while the surfaces were disinfected with Venno Vet 1 Super® (1.5 %). At the same time rodent and fly control was intensified. Upon completion of the eradication programme, the farm was monitored for 6 months by carrying out fecal swab analyses of pigs with diarrhea. All fecal samples were negative for B. hyodysenteriae. The costs of the eradication amounted to approximately CHF 104'500. The eradication yielded significantly higher live daily weight gain (+ 23.8 g, ± 10.1 g, P < 0.0001). This improved performance resulted in an additional economic benefit of CHF 18,500 per year

Untersuchung von Tiergesundheit, Tierwohl und Biosicherheit während 101 Transporten von Mastferkeln in der Schweiz

The transfer of piglets is associated with stress for the transported animals. In addition, animal transports are a risk factor for the spread of pathogenic and antibiotic-resistant bacteria and for the introduction of diseases into the herd. In the present study, 101 randomly selected transports of piglets were accompanied from the breeding facility to the pig farm. Parameters related to animal health, animal welfare and biosecurity were assessed. Transported piglets showed signs of abscesses, hernias or cannibalism in 30% and diarrhea or cough in 15% of the cases. The proportion of animals with injuries from conflicts were higher after (15%) than before transport (8%). Suboptimal conditions in regard to density, temperature and lighting were found in 19%, 55% and 36% of the transports. Vehicles were cleaned and disinfected only in 55% of transports before arriving at the breeding facility. Thirty percent of the vehicles were soiled and 20% had already loaded piglets when arriving at the sending facility. Vehicles were neither cleaned nor disinfected in 83% between two piglet transports. Overall, there was a great potential for improvement in animal loading and risk of disease transmission in the investigated piglet transports

Quantitative analysis of heavy metals in automotive brake linings: A comparison between wet-chemistry based analysis and in-situ screening with a handheld X-ray fluorescence spectrometer

Two extraction procedures for ecologically relevant elements present in automotive brake linings (Sb, Bi, Pb, Cd, Cr (total), Co, Cu, Mo, Ni, Sr. V, Zn, Sn) were developed and validated, applying a high pressure asher (HPA-S) and microwave extraction, respectively. Both of these methods allowed for the quantitative analysis of the extracted elements by inductively coupled plasma optical emission spectrometry (ICP-OES). The results were compared to measurements using a handheld energy-dispersive X-ray fluorescence spectrometer (ED-XRF), being in discussion by regulating agencies as in-situ screening tool for brake pads. The comparison indicates that the handheld ED-XRF analysis is basically an efficient screening tool for a reliable assessment of trace metal contents in automotive brake pads with respect to legal standards. While a quantitative determination of elements like Cd, Co, Cr, Mn. Mo, Ni, Pb and Sb was achievable, other elements (V, Cu, Bi, Zn, Sn and Sr) could only be determined qualitatively due to the special matrix characteristics of brake pads