An apparatus for immersing trapped ions into an ultracold gas of neutral atoms

We describe a hybrid vacuum system in which a single ion or a well-defined small number of trapped ions (in our case Ba(+) or Rb(+)) can be immersed into a cloud of ultracold neutral atoms (in our case Rb). This apparatus allows for the study of collisions and interactions between atoms and ions in the ultracold regime. Our setup is a combination of a Bose-Einstein condensation apparatus and a linear Paul trap. The main design feature of the apparatus is to first separate the production locations for the ion and the ultracold atoms and then to bring the two species together. This scheme has advantages in terms of stability and available access to the region where the atom-ion collision experiments are carried out. The ion and the atoms are brought together using a moving one-dimensional optical lattice transport which vertically lifts the atomic sample over a distance of 30 cm from its production chamber into the center of the Paul trap in another chamber. We present techniques to detect and control the relative position between the ion and the atom cloud.     

Combining spectroscopic and potentiometric approaches to characterize competitive binding to humic substances

In an area that contains high concentrations of natural organic matter, it is expected that it plays an important role on the behavior of rare earth elements (REE), like europium, and of trivalent actinides. Competitive interactions with H+, inorganic species, major cations, e.g. Ca(II) or Mg(II), could influence these metals transport and bioavailability. Competitive experiments between cations, which can bind differently to humic substances and Eu3+, will bring an improved understanding of the competitive mechanisms. The aim of this study is to acquire data for Eu(III)/Cu(II) and Eu(III)/Ca(II) competitive binding to a sedimentary originated humic acid (Gorleben, Germany). The NICA-Donnan parameters for Ca2+, Cu2+, and Eu3+ obtained from competitive binding experiments using Ca2+ or Cu2+ ion selective electrodes were used to model time-resolved laser fluorescence spectroscopy (TRLFS) measurements. Eu3+ and CU2+ are in direct competition for the same type of sites, whereas Ca2+ has an indirect influence through electrostatic binding.     

False fame prevented: Avoiding fluency effects without judgmental correction.

Three studies show a way to prevent fluency effects independently of judgmental correction strategies by identifying and procedurally blocking the sources of fluency variations, which are assumed to be embodied in nature. For verbal stimuli, covert pronunciations are assumed to be the crucial source of fluency gains. As a consequence, blocking such pronunciation simulations through a secondary oral motor task decreased the false-fame effect for repeatedly presented names of actors (Experiment 1) as well as prevented increases in trust due to repetition for brand names and names of shares in the stock market (Experiment 2). Extending this evidence beyond repeated exposure, we demonstrated that blocking oral motor simulations also prevented fluency effects of word pronunciation on judgments of hazardousness (Experiment 3). Concerning the realm of judgment correction, this procedural blocking of (biasing) associative processes is a decontamination method not considered before in the literature, because it is independent of exposure control, mood, motivation, and post hoc correction strategies. The present results also have implications for applied issues, such as advertising and investment decisions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Uptake of the cyanobacterial toxin cylindrospermopsin in Brassica vegetables

Toxin-producing cyanobacterial species are increasingly being found in freshwater systems. However, literature on the impact of many cyanobacterial toxins on plants is scarce. Cylindrospermosin (CYN), a secondary metabolite of cyanobacteria such as Cylindrospermopsis and Aphanizomenon species, is a potent hepatotoxin and protein synthesis inhibitor. Worryingly, CYN is increasingly found in surface and drinking water worldwide causing human and animal intoxications. Further, exposure of crop plants to CYN by irrigation with contaminated water has already been shown. Therefore, in this study, horticulturally important and highly consumed Brassica species were investigated to determine the level of CYN in the leaves after exposure of the roots to the toxin. Treatment of Brassica oleracea var. sabellica, Brassica juncea, and Sinapis alba under varying experimental conditions showed significant CYN uptake, with CYN levels ranging from 10% to 21% in the leaves compared to the CYN concentration applied to the roots (18–35 μg/l). In seedlings, CYN concentrations of up to 49 μg/g fresh weight were observed. Thus, crop plants irrigated with CYN-containing water may represent a significant source of this toxin within the food chain.     

Rapid synthesis of pentagonal silver nanowires with diameter-dependent tensile yield strength

We synthesize silver nanowires (NWs) with pentagonal cross sections via a facile and rapid microwave-assisted polyol method in the presence of polyvinylpyrrolidone (PVP) and sodium sulfide (Na₂S). The synthesis does not use templates and needs only 2.5 min, which is 570 times faster than solvothermal preparation at 100 °C. The pentagonal Ag NWs grow along the <110> direction and reach lengths between 10 and 30 μm. Adjusting Na₂S concentration controls the wire diameters in a wide range from 60 to 480 nm. PVP and microwave irradiation both ensure the cross sections' pentagonal shape even at large diameters. We use different microwave irradiation times to investigate the morphology's evolution and to support the discussion of growth mechanisms. The electrical conductivity was measured in situ inside a transmission electron microscope. Their resistivity is diameter dependent and comparable to that of Ag NWs with round cross sections. Ultrasound fracturing analysis determined the NWs' tensile yield strengths, which is also diameter dependent and maximal around 220 nm.     

Characterization of coating systems by scanning acoustic microscopy: Debonding,blistering and surface topology

Scanning acoustic microscopy (SAM) has been applied to different commercial coating systems on steel substrates in order to evaluate the potential of the method for fast non-destructive testing during material development: the focus was on defect detection after and during accelerated weathering and corrosion tests. The possibility of detecting hidden defects (e.g., blisters) in an early stage of weathering or corrosion tests has been evaluated for different commercial coating systems. Using different scanning modes 2K polyurethane systems (solvent- and water-borne) have been examined by SAM. Debonding at the polymer/substrate interface and the interface between base coat and top coat has been studied in samples after simulated weathering. The time dependence of “blister nucleation and growth” has been studied during a salt spray test. Furthermore, the surface topography has been investigated for UV-cured acrylic systems with and without antioxidants after simulated weathering.     

Cutting thin sheet metal with a water jet guided laser using various cutting distances, feed speeds and angles of incidence

This research deals with the cutting of thin sheet metals at various distances, feed speeds and angles of incidence using a water jet guided laser. In the water jet guided laser process a laser beam is focused into a jet of water, which transmits the beam to the workpiece. This eliminates the need for any focus control. Nevertheless, most of its applications are in planar cutting where this advantage is not utilized. For the laser parameters, jet pressure and diameter in question, the value of 50 mm was found to be a fairly reliable upper limit to the cutting distance for both normal and inclined surfaces. In addition to the laser beam being absorbed partially by the water jet, the jet was found to be susceptible to disturbances. Specimen vibration caused by the water jet also impeded cutting a continuous kerf.     

Ruminal biohydrogenation and abomasal flow of fatty acids in lactating cows fed diets supplemented with soybean oil,whole soybeans,or calcium salts of fatty acids

Ruminants have a unique metabolism and digestion of unsaturated fatty acids (UFA). Unlike monogastric animals, the fatty acid (FA) profile ingested by ruminants is not the same as that reaching the small intestine. The objective of this study was to evaluate whole raw soybeans (WS) in diets as a replacer for calcium salts of fatty acids (CSFA) in terms of UFA profile in the abomasal digesta of early- to mid-lactation cows. Eight Holstein cows (80 ± 20 d in milk, 22.9 ± 0.69 kg/d of milk yield, and 580 ± 20 kg of body weight; mean ± standard deviation) with ruminal and abomasal cannulas were used in a 4 × 4 Latin square experiment with 22-d periods. The experiment evaluated different fat sources rich in linoleic acid on ruminal kinetics, ruminal fermentation, FA abomasal flow, and milk FA profile of cows assigned to treatment sequences containing a control (CON), with no fat source; soybean oil, added at 2.68% of diet dry matter (DM); WS, addition of WS at 14.3% of diet DM; and CSFA, addition of CSFA at 2.68% of diet DM. Dietary fat supplementation had no effect on nutrient intake and digestibility, with the exception of ether extract. Cows fed fat sources tended to have lower milk fat concentration than those fed CON. In general, diets containing fat sources tended to decrease ruminal neutral detergent fiber digestibility in relation to CON. Cows fed WS had lower ruminal digestibility of DM and higher abomasal flow of DM in comparison to cows fed CSFA. As expected, diets containing fat supplements increased FA abomasal flow of C18:0 and total FA. Cows fed WS tended to present a higher concentration of UFA in milk when compared with those fed CSFA. This study suggests that under some circumstances, abomasal flow of UFA in early lactation cows can be increased by supplementing their diet with fat supplements rich in linoleic acid, regardless of rumen protection, with small effects on ruminal DM digestibility.     

Polymer:Fullerene Bimolecular Crystals for Near‐Infrared Spectroscopic Photodetectors

Spectroscopic photodetection is a powerful tool in disciplines such as medical diagnosis, industrial process monitoring, or agriculture. However, its application in novel fields, including wearable and biointegrated electronics, is hampered by the use of bulky dispersive optics. Here, solution‐processed organic donor–acceptor blends are employed in a resonant optical cavity device architecture for wavelength‐tunable photodetection. While conventional photodetectors respond to above‐gap excitation, the cavity device exploits weak subgap absorption of intermolecular charge‐transfer states of the intercalating poly[2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene] (PBTTT):[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) bimolecular crystal. This enables a highly wavelength selective, near‐infrared photoresponse with a spectral resolution down to 14 nm, as well as dark currents and detectivities comparable with commercial inorganic photodetectors. Based on this concept, a miniaturized spectrophotometer, comprising an array of narrowband cavity photodetectors, is fabricated by using a blade‐coated PBTTT:PCBM thin film with a thickness gradient. As an application example, a measurement of the transmittance spectrum of water by this device is demonstrated.     

Electropolymerization of PANI coating in nitric acid for corrosion protection of 430 SS

A smooth and adherent polyaniline (PANI) coating was electropolymerized in HNO₃ solution by cyclic voltammetry in order to protect the ferritic and economic 430 stainless steel (SS) from corrosion. The corrosion resistance was evaluated in 3.5 wt.% NaCl solution by anodic polarization, potentiodynamic polarization, and electrochemical impedance spectroscopy. The PANI coating shifts the corrosion potential of SS to the passive region and provides a strong and steady corrosion resistance. A low growth rate leads to a compact PANI coating that acts as a good physical barrier. However, the strong corrosion inhibition is mainly attributed to the dense oxide layers formed by the catalytic effect of PANI at the polymer/metal interface. The composition of the oxide layers was analyzed via depth profiling using X-ray photoelectron spectroscopy alternating with sputtering. Compared with layers formed on uncoated SS, the iron and chromium oxide layers under the PANI are thinner and denser, absorbing less oxygen, and providing a stronger corrosion inhibition.