“In situ” investigations to define the degradation of phenols in groundwater

Phenols are especially suitable for defining the mechanism of their degradation in groundwater. Phenols, for the most part, do not sorb on clastic aquifer material. This allows for a comparison of their relative concentrations in groundwater to the concentrations of a tracer, and leads to conclusions which can be drawn about the kinetics of phenol degradation. We have had an opportunity to monitor, in detail, the degradation of phenols at three locations. All three cases involved gravelly and sandy aquifers and aerobic conditions. A summary of the analytical methods applied, and basic results obtained is presented. This paper represents a short overview of the flow and results of the monitoring and five tests which were conducted at the three locations over several years. We believe that the results are representative of the behavior of phenols in aerobic intergranular aquifers.

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Predicting the denitrification capacity of sandy aquifers from in situ measurements using push–pull <sup>15</sup>N tracer tests

Biogeosciences ◽

10.5194/bg-12-2327-2015 ◽

2015 ◽

Vol 12 (8) ◽

pp. 2327-2346 ◽

Cited By ~ 4

Author(s):

W. Eschenbach ◽

R. Well ◽

W. Walther

Keyword(s):

Microbial Community ◽

Transfer Functions ◽

Tracer Tests ◽

In Situ Measurements ◽

15N Tracer ◽

Data Set ◽

Aquifer Material ◽

Sandy Aquifers ◽

15N Analysis

Abstract. Knowledge about the spatial variability of in situ denitrification rates (Dr(in situ)) and their relation to the denitrification capacity in nitrate-contaminated aquifers is crucial to predict the development of groundwater quality. Therefore, 28 push–pull 15N tracer tests for the measurement of in situ denitrification rates were conducted in two sandy Pleistocene aquifers in northern Germany. The 15N analysis of denitrification-derived 15N-labelled N2 and N2O dissolved in water samples collected during the push–pull 15N tracer tests was performed using isotope ratio mass spectrometry (IRMS) in the lab and additionally for some tracer tests online in the field with a quadrupole membrane inlet mass spectrometer (MIMS) in order to test the feasibility of on-site real-time 15N analysis. Aquifer material from the same locations and depths as the push–pull injection points was incubated, and the initial and cumulative denitrification after 1 year of incubation (Dcum(365)) as well as the stock of reduced compounds (SRC) was compared with in situ measurements of denitrification. This was done to derive transfer functions suitable to predict Dcum(365) and SRC from Dr(in situ). Dr(in situ) ranged from 0 to 51.5 μg N kg−1 d−1. Denitrification rates derived from on-site isotope analysis using MIMS satisfactorily coincided with laboratory analysis by conventional IRMS, thus proving the feasibility of in situ analysis. Dr(in situ) was significantly higher in the sulfidic zone of both aquifers compared to the zone of non-sulfidic aquifer material. Overall, regressions between the Dcum(365) and SRC of the tested aquifer material with Dr(in situ) exhibited only a modest linear correlation for the full data set. However, the predictability of Dcum(365) and SRC from Dr(in situ) data clearly increased for aquifer samples from the zone of NO3−-bearing groundwater. In the NO3−-free aquifer zone, a lag phase of denitrification after NO3− injections was observed, which confounded the relationship between reactive compounds and in situ denitrification activity. This finding was attributed to adaptation processes in the microbial community after NO3− injections. It was also demonstrated that the microbial community in the NO3−-free zone just below the NO3−-bearing zone can be adapted to denitrification by NO3− injections into wells for an extended period. In situ denitrification rates were 30 to 65 times higher after pre-conditioning with NO3−. Results from this study suggest that such pre-conditioning is crucial for the measurement of Dr(in situ) in deeper aquifer material from the NO3−-free groundwater zone and thus for the prediction of Dcum(365) and SRC from Dr(in situ).

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In situ study of electron beam-induced chemical vapor deposition of Au in an environmental TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137653 ◽

1995 ◽

Vol 53 ◽

pp. 256-257

Author(s):

J. Drucker ◽

R. Sharma ◽

J. Kouvetakis ◽

K.H.J. Weiss

Keyword(s):

Electron Beam ◽

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Quantum Effect ◽

Line Drawing ◽

Chemical Vapor ◽

Environmental Cell ◽

Engineering Changes ◽

Kinetics Of

Patterning of metals is a key element in the fabrication of integrated microelectronics. For circuit repair and engineering changes constructive lithography, writing techniques, based on electron, ion or photon beam-induced decomposition of precursor molecule and its deposition on top of a structure have gained wide acceptance Recently, scanning probe techniques have been used for line drawing and wire growth of W on a silicon substrate for quantum effect devices. The kinetics of electron beam induced W deposition from WF6 gas has been studied by adsorbing the gas on SiO2 surface and measuring the growth in a TEM for various exposure times. Our environmental cell allows us to control not only electron exposure time but also the gas pressure flow and the temperature. We have studied the growth kinetics of Au Chemical vapor deposition (CVD), in situ, at different temperatures with/without the electron beam on highly clean Si surfaces in an environmental cell fitted inside a TEM column.

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In situ observation of the martensitic transformation in (Mg,Y)-PSZ

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144036 ◽

1986 ◽

Vol 44 ◽

pp. 500-501

Author(s):

R-R. Lee

Keyword(s):

Martensitic Transformation ◽

High Strength ◽

Nucleation And Growth ◽

In Situ Observation ◽

Considerable Potential ◽

Transmission Electron ◽

Structural Applications ◽

Applied Stresses ◽

Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

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Growth kinetics of Al2Cu in an Al-1.5Cu thin film by in Situ TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151696 ◽

1993 ◽

Vol 51 ◽

pp. 1172-1173

Author(s):

M. Park ◽

S.J. Krause ◽

S.R. Wilson

Keyword(s):

Thin Film ◽

In Situ Tem ◽

Collector Plate ◽

Transmission Electron ◽

Device Processing ◽

Corrosion Susceptibility ◽

Precipitation Phenomena ◽

Semiconductor Chips ◽

Kinetics Of

Cu alloying in Al interconnection lines on semiconductor chips improves their resistance to electromigration and hillock growth. Excess Cu in Al can result in the formation of Cu-rich Al2Cu (θ) precipitates. These precipitates can significantly increase corrosion susceptibility due to the galvanic action between the θ-phase and the adjacent Cu-depleted matrix. The size and distribution of the θ-phase are also closely related to the film susceptibility to electromigration voiding. Thus, an important issue is the precipitation phenomena which occur during thermal device processing steps. In bulk alloys, it was found that the θ precipitates can grow via the grain boundary “collector plate mechanism” at rates far greater than allowed by volume diffusion. In a thin film, however, one might expect that the growth rate of a θ precipitate might be altered by interfacial diffusion. In this work, we report on the growth (lengthening) kinetics of the θ-phase in Al-Cu thin films as examined by in-situ isothermal aging in transmission electron microscopy (TEM).

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In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

10.26434/chemrxiv.9876395.v1 ◽

2019 ◽

Author(s):

Hao Wu ◽

Jeffrey Ting ◽

Siqi Meng ◽

Matthew Tirrell

Keyword(s):

Small Angle ◽

Self Assembly ◽

Electrostatic Interactions ◽

Polyelectrolyte Complex ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Kinetics Of ◽

Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

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Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19802219 ◽

1980 ◽

Vol 45 (8) ◽

pp. 2219-2223 ◽

Cited By ~ 6

Author(s):

Marie Jakoubková ◽

Martin Čapka

Keyword(s):

Catalytic Activity ◽

Nmr Spectroscopy ◽

Ir Spectroscopy ◽

Electron Density ◽

Phosphorus Atom ◽

Proton Acceptor ◽

Trimethylsilyl Group ◽

Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

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Reordering and Crystallization of Silicon Carbide Amorphized by Neutron Irradiation

MRS Proceedings ◽

10.1557/proc-650-r5.1 ◽

2000 ◽

Vol 650 ◽

Author(s):

Lance L. Snead ◽

Martin Balden

Keyword(s):

Thin Film ◽

Silicon Carbide ◽

Crystallization Kinetics ◽

Neutron Irradiation ◽

Onset Temperature ◽

Kinetics Of Crystallization ◽

Crystallization Onset Temperature ◽

Crystallization Onset ◽

Kinetics Of

ABSTRACTDensification and crystallization kinetics of bulk SiC amorphized by neutron irradiation is studied. The temperature of crystallization onset of this highly pure, fully amorphous bulk SiC was found to be between 875-885°C and crystallization is nearly complete by 950°C. In-situ TEM imaging confirms the onset of crystallization, though thin-film effects apparently alter the kinetics of crystallization above this temperature. It requires >1125°C for complete crystallization of the TEM foil. Annealing at temperatures between the irradiation and crystallization onset temperature is seen to cause significant densification attributed to a relaxation, or reordering, of the as-amorphized structure.

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Phosphorylation of GAPVD1 Is Regulated by the PER Complex and Linked to GAPVD1 Degradation

International Journal of Molecular Sciences ◽

10.3390/ijms22073787 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3787

Author(s):

Hussam Ibrahim ◽

Philipp Reus ◽

Anna Katharina Mundorf ◽

Anna-Lena Grothoff ◽

Valerie Rudenko ◽

...

Keyword(s):

Circadian Clock ◽

Transcriptional Repression ◽

Small Gtpase ◽

Main Role ◽

Interacting Proteins ◽

Casein Kinase 1 ◽

Bona Fide ◽

Kinetics Of

Repressor protein period (PER) complexes play a central role in the molecular oscillator mechanism of the mammalian circadian clock. While the main role of nuclear PER complexes is transcriptional repression, much less is known about the functions of cytoplasmic PER complexes. We found with a biochemical screen for PER2-interacting proteins that the small GTPase regulator GTPase-activating protein and VPS9 domain-containing protein 1 (GAPVD1), which has been identified previously as a component of cytoplasmic PER complexes in mice, is also a bona fide component of human PER complexes. We show that in situ GAPVD1 is closely associated with casein kinase 1 delta (CSNK1D), a kinase that regulates PER2 levels through a phosphoswitch mechanism, and that CSNK1D regulates the phosphorylation of GAPVD1. Moreover, phosphorylation determines the kinetics of GAPVD1 degradation and is controlled by PER2 and a C-terminal autoinhibitory domain in CSNK1D, indicating that the regulation of GAPVD1 phosphorylation is a novel function of cytoplasmic PER complexes and might be part of the oscillator mechanism or an output function of the circadian clock.

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In-situ stabilization of silver nanoparticles in polymer hydrogels for enhanced catalytic reduction of macro and micro pollutants

Zeitschrift für Physikalische Chemie ◽

10.1515/zpch-2020-1721 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Luqman Ali Shah ◽

Rida Javed ◽

Mohammad Siddiq ◽

Iram BiBi ◽

Ishrat Jamil ◽

...

Keyword(s):

Catalytic Reduction ◽

Thermo Gravimetric Analysis ◽

Activation Parameters ◽

Reduction Reaction ◽

Gravimetric Analysis ◽

X Ray Diffraction ◽

In Situ Stabilization ◽

Hybrid Hydrogels ◽

Kinetics Of

AbstractThe in-situ stabilization of Ag nanoparticles is carried out by the use of reducing agent and synthesized three different types of hydrogen (anionic, cationic, and neutral) template. The morphology, constitution and thermal stability of the synthesized pure and Ag-entrapped hybrid hydrogels were efficiently confirmed using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). The prepared hybrid hydrogels were used in the decolorization of methylene blue (MB) and azo dyes congo red (CR), methyl Orange (MO), and reduction of 4-nitrophenol (4-NP) and nitrobenzene (NB) by an electron donor NaBH4. The kinetics of the reduction reaction was also assessed to determine the activation parameters. The hybrid hydrogen catalysts were recovered by filtration and used continuously up to six times with 98% conversion of pollutants without substantial loss in catalytic activity. It was observed that these types of hydrogel systems can be used for the conversion of pollutants from waste water into useful products.

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