Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

Gold nanoparticles covered with a mixture of ligands of which one type contains solubilizing triethylene glycol residues and the other peripheral zinc(II)–dipicolylamine (DPA) complexes allowed the optical detection of hydrogenphosphate, diphosphate, and triphosphate anions in water/methanol 1:2 (v/v). These anions caused the bright red solutions of the nanoparticles to change their color because of nanoparticle aggregation followed by precipitation, whereas halides or oxoanions such as sulfate, nitrate, or carbonate produced no effect. The sensitivity of phosphate sensing depended on the nature of the anion, with diphosphate and triphosphate inducing visual changes at significantly lower concentrations than hydrogenphosphate. In addition, the sensing sensitivity was also affected by the ratio of the ligands on the nanoparticle surface, decreasing as the number of immobilized zinc(II)–dipicolylamine groups increased. A nanoparticle containing a 9:1 ratio of the solubilizing and the anion-binding ligand showed a color change at diphosphate and triphosphate concentrations as low as 10 μmol/L, for example, and precipitated at slightly higher concentrations. Hydrogenphosphate induced a nanoparticle precipitation only at a concentration of ca. 400 μmol/L, at which the precipitates formed in the presence of diphosphates and triphosphates redissolved. A nanoparticle containing fewer binding sites was more sensitive, while increasing the relative number of zinc(II)–dipicolylamine complexes beyond 25% had a negative impact on the limit of detection and the optical response. Transmission electron microscopy provided evidence that the changes of the nanoparticle properties observed in the presence of the phosphates were due to a nanoparticle crosslinking, consistent with the preferred binding mode of zinc(II)–dipicolylamine complexes with phosphate anions which involves binding of the anion between two metal centers. This work thus provided information on how the behavior of mixed monolayer-protected gold nanoparticles is affected by multivalent interactions, at the same time introducing a method to assess whether certain biologically relevant anions are present in an aqueous solution within a specific concentration range

Session B4: Ethohydraulics in Turbulence: Fish Behaviour in Turning Pools

Abstract: Space restrictions often necessitate the incorporation of turning pools in the design of fishways. Several biological studies have identified potential problems fish have with turning pools, varying from disproportionate residence times, flow negotiating difficulties and even fish leaping out of the turning pool. Likewise, our research on fish passage times of a vertical slot fishway on the river Mosel in Germany, detected significant time lags in turning pools. A number of potential explanations have been stated in the literature including confusion associated with large vortices, turbulence and complex flows, flow characteristics exceeding the swimming abilities of the fish, or fish could be using such basins to rest. The actual activity within these turning basins remains unknown and represents an important knowledge gap. This paper presents the results of an HDX and sonar monitoring campaign, registering behaviour in a turning pool in a vertical slot fishway on the river Mosel in Germany, where increased passage times were recorded for several fish species in turning pools. Behavioural patterns like residence times, acc- and deceleration, resting and swimming tracks for both up- and downward migration are related to flow direction patterns described in a 3D hydraulic model. The results offer insights in the behavioural characteristics of migrating fish in turbulent basins, with direct implications on technical design features like rounded basins and additional baffle walls

Nitrite induced transcription of p450nor during denitrification by Fusarium oxysporum correlates with the production of N2O with a high 15N site preference

The greenhouse gas nitrous oxide (N2O) is produced in soil as a consequence of complex co-occurring processes conducted by diverse microbial species, including fungi. The fungal p450nor gene encodes a nitric oxide reductase associated with fungal denitrification. We thus hypothesized that p450nor gene expression is a marker for ongoing fungal denitrification. Specific PCR primers and quantitative PCR (qPCR) assays were developed targeting p450nor genes and transcripts. The novel PCR primers successfully amplified p450nor from pure cultures, and were used in an mRNA targeted qPCR to quantify p450nor gene transcription (i.e., gene expression) during denitrification activity in cultures of the fungal model denitrifier Fusarium oxysporum. Gene expression was induced by high (5 mM) and low (0.25 mM) nitrite concentrations. Nitrite stimulated N2O production rates by F. oxysporum, which correlated well with an up to 70-fold increase in p450nor gene expression during the first 12–24 h of anoxic incubation. The relative p450nor gene peak expression and peak N2O production rates declined 20- and 2-fold on average, respectively, towards the later phase of incubation (48–120 h). The 15N site preference of N2O (SP(N2O)) was high for F. oxysporum and independent of reaction progress, confirming the fungal origin of N2O produced. In conclusion, the developed fungal p450nor gene expression assay together with the analysis of SP(N2O) values provide a basis to improve current tools for the identification of fungal denitrification and/or N2O production in natural systems like soils

Investigation of ro-vibrational spectra of small hydrocarbons at elevated temperatures using infrared degenerate four-wave mixing

The ro-vibrational spectra around 3 µm of four small hydrocarbons (C2H2, CH4, C2H6 and C2H4) at 296, 550 and 820 K have been investigated using infrared degenerate four-wave mixing (IR-DFWM). The spectra were recorded in gas flows of nitrogen with small admixtures of the hydrocarbons. A fused silica glass tube surrounded by an electric heating wire was used to heat the gas flows. The recorded IR-DFWM spectra are compared with simulations using the spectral information available in the HITRAN database, in order to identify spectral lines. The measurements demonstrate good signal to noise ratio and good sensitivity even at elevated temperatures. Several weak hot lines were detected that are not included in the current database. This paper demonstrates the potential of IR-DFWM for purposes of investigating spectral lines at elevated temperatures, which is often a challenging task with conventional absorption spectroscopy techniques. The possibility of applying IR-DFWM for combustion diagnostics of small hydrocarbons is discussed from the detection limits of the measurements and the potential water line interference. Because of the non-linear nature of the DFWM technique, it provides much higher contrast for strong lines of small molecules over backgrounds of high-density weak lines, which commonly exist in hot gas flows of thermochemical reactions

Mid-infrared pumped laser-induced thermal grating spectroscopy for detection of acetylene in the visible spectral range

We present mid-infrared laser-induced thermal grating spectroscopy (IR-LITGS) using excitation radiation around 3 μm generated by a simple broadband optical parametric oscillator (OPO). Acetylene as a typical small hydrocarbon molecule is used as an example target species. A mid-infrared broadband OPO pumped by the fundamental output of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to generate the pump beams, with pulse energies of 6-10 mJ depending on the wavelength. The line width of the OPO idler beam was ∼5 cm-1, which is large enough to cover up to six adjacent acetylene lines. The probe beam was the radiation of a 532 nm cw solid state laser with 190 mW output power. Signals were generated in atmospheric pressure gas flows of N2, air, CO2 and Ar with small admixtures of C2H2. A detection limit of less than 300 ppm was found for a point measurement of C2H2 diluted in N2. As expected, the oscillation frequency of the IR-LITGS signal was found to have a large dependency on the buffer gas, which allows determination of the speed of sound. Moreover, the results reveal a very strong collisional energy exchange between C2H2 and CO2 compared to the other gases. This manifests as significant local heating. In summary, the MIR-LITGS technique enables spectroscopy of fundamental vibrational transitions in the infrared via detection in the visible spectral range

Investigation of laser-induced grating spectroscopy of O2 for accurate temperature measurements towards applications in harsh environments

We present an in-depth investigation of laser-induced grating spectroscopy (LIGS) for temperature measurements in practical applications using a narrow-band dye laser with 760 nm wavelength and a pulse duration of 8 ns as the source for the pump beams creating the laser-induced grating. The pump laser wavelength was set to be either resonant with the (Formula presented.) transition from the (Formula presented.) band of O2 for generation of thermal LIGS or nonresonant for generation of purely electrostrictive LIGS. Signals were generated in ambient air as well as in high-pressure or high-temperature dry air mixtures. Pump laser irradiances up to 11 GW/cm2 were used, which resulted in strong electrostrictive contribution to the overall LIGS signals at atmospheric pressure, with a low thermal contribution due to the weak absorption by the singlet O2 (Formula presented.). The advantage and disadvantage of thermal or electrostrictive LIGS for temperature measurements are discussed, as well as potential applications in high-pressure environments. Furthermore, the precision of the temperature measurement is discussed by comparing different analysis methods

BMI and mortality in patients with new-onset type 2 diabetes: a comparison with age- and sex-matched control subjects from the general population

Objective: Type 2 diabetes is strongly associated with obesity, but the mortality risk related to elevated body weight in people with type 2 diabetes compared with people without diabetes has not been established. Research Design and Methods: We prospectively assessed short- and long-term mortality in people with type 2 diabetes with a recorded diabetes duration ≤5 years identified from the Swedish National Diabetes Registry between 1998 and 2012 and five age- and sex-matched control subjects per study participant from the general population. Results: Over a median follow-up of 5.5 years, there were 17,546 deaths among 149,345 patients with type 2 diabetes (mean age 59.6 years [40% women]) and 68,429 deaths among 743,907 matched control subjects. Short-term all-cause mortality risk (≤5 years) displayed a U-shaped relationship with BMI, with hazard ratios (HRs) ranging from 0.81 (95% CI 0.75-0.88) among patients with diabetes and BMI 30 to <35 kg/m2 to 1.37 (95% CI 1.11-1.71) with BMI ≥40 kg/m2 compared with control subjects after multiple adjustments. Long-term, all weight categories showed increased mortality, with a nadir at BMI 25 to <30 kg/m2 and a stepwise increase up to HR 2.00 (95% CI 1.58-2.54) among patients with BMI ≥40 kg/m2, that was more pronounced in patients <65 years old. Conclusions: Our findings suggest that the apparent paradoxical findings in other studies in this area may have been affected by reverse causality. Long-term, overweight (BMI 25 to <30 kg/m2) patients with type 2 diabetes had low excess mortality risk compared with control subjects, whereas risk in those with BMI ≥40 kg/m2 was substantially increased

Wertigkeit der Kernspintomographie bei kindlichen Knieverletzungen

Einleitung: Die Diagnostik kindlicher Knieverletzungen wird heutzutage häufig durch die Kernspintomographie ergänzt, um relevante Kniebinnenschäden zu erkennen. Der klinische Nutzen dieser Zusatzuntersuchung wird in Abhängigkeit vom Beschwerdebild des Patienten und in Relation zum apparativen und wirtschaftlichen Aufwand unterschiedlich bewertet. Ziel dieser Studie war es, die Bedeutung der Kernspintomographie in Abhängigkeit von der klinischen Verdachtsdiagnose und dem arthroskopischen Befund zu bewerten. Material und Methoden: Es wurden insgesamt 195 Patienten im Alter von 3 bis 17 Jahren in diese Studie aufgenommen. 83 dieser Patienten wurden aufgrund der klinischen Diagnose unmittelbar der Kernspintomographie zugeführt. 165 der Patienten wurden, entweder aufgrund der klinischen Untersuchung, oder aufgrund des Befunds der Kernspintomographie, arthroskopiert. Ergebnisse: Die klinische Verdachtsdiagnose wurde bei 117 der 165 Patienten (71%), bei denen eine Arthroskopie durchgeführt wurde, bestätigt. Die größten Übereinstimmungen der Diagnosen in den unterschiedlichen Verfahren gab es dabei bei der Verdachtsdiagnose Patellaluxation (87%) und bei der Verdachtsdiagnose ligamentäre Verletzung (74%). Die Verdachtsdiagnose einer Meniskusläsion brachte eine Übereinstimmung von 48%.Von den 83 Patienten, bei denen eine kernspintomographische Untersuchung durchgeführt wurde, wurden daraufhin 53 Patienten arthroskopiert und 30 Patienten konservativ behandelt. Der MRT Befund wurde in der durchgeführten Arthroskopie bei 42 Patienten (81%) bestätigt. Die MRT Diagnose Patellaluxation wurde hierbei in allen Fällen (100%) in der Arthroskopie bestätigt. Die Übereinstimmungen der Kernspindiagnose einer ligamentären Läsion lag bei 83% und die Übereinstimmung bei der Meniskusverletzung bei 56%.Bei den 30 Patienten, die ausschließlich die Kernspintomographie erhielten und daraufhin konservativ behandelt wurden, wurden hauptsächlich Band- und Meniskuseinblutungen (37%) und extraartikuläre Veränderungen wie Bone Bruise, Fibrom oder Exostose (13%) im MRT diagnostiziert. Letztlich konnte durch den Einsatz der Kernspintomographie der Anteil der rein diagnostischen Arthroskopien von 22% auf 13% reduziert werden. Schlussfolgerung: Bei klinischem Verdacht auf eine Meniskus- oder Bandverletzung ist die Kernspintomographie ein wertvolles Hilfsmittel zur Überprüfung der Diagnose, da häufig klinisch keine sichere Beurteilung möglich ist. Bei der klinischen Verdachtsdiagnose einer Patellaluxation ist die Kernspintomographie zur Diagnosesicherung selten erforderlich, kann jedoch zur Beurteilung von Begleitverletzungen (z.B. Flake Frakturen) wertvolle Zusatzinformationen liefern. Bei klinisch unklarem Befund kann die Anzahl rein diagnostischer Arthroskopien deutlich gesenkt werden

Mid-infrared laser-induced thermal grating spectroscopy in flames

For the first time, laser-induced thermal grating spectroscopy (LITGS) in the spectral range around 3. μm is demonstrated as a versatile diagnostic tool. This spectral region is of particular interest in combustion diagnostics as many relevant species such as hydrocarbons and water exhibit fundamental vibrational modes and hence can be probed with high sensitivity. Another benefit of the IR-LITGS is that it allows performing spectroscopy in the infrared combined with signal detection in the visible. Hence, the strong thermal radiation inherent in flames does not represent an interference. As the first step, we present the application of IR-LITGS to cold gas flows, where traces of ethylene and water vapor are detected. The time-resolved LITGS signals, which can be acquired in a single laser shot, are rich in information and allow deriving temperature and to some extend chemical composition. In the second step, the IR-LITGS technique is applied to ethylene/air flames stabilized on a flat flame burner. A proof-of-concept study is carried out, in which the temperature is determined in the burned region of flames with systematically varied equivalence ratio (0.72 < Φ <. 2.57). Moreover, in a highly sooty flame, LITGS signals were recorded as a function of height above the burner and allowed the determination of the temperature profile. The proposed IR-LITGS method has the potential for enabling single-shot measurements of several parameters at a time. Its applicability to sooty flame environments opens up new opportunities to study the complex formation of carbonaceous particles in flames