Speciation of metals in agricultural lime and contaminated soil

Die Verwendung von Metallen zur Entwicklung der heutigen fortschrittlichen technologischenrnGesellschaft lässt auf eine lange Geschichte zurück blicken. Im Zuge des letzten Jahrhundertsrnwurde realisiert, dass die chemischen und radioaktiven Eigenschaften von Metallen einernernsthafte Bedrohung für die Menschheit darstellen können. In der modernen Geochemie ist esrnallgemein akzeptiert, dass die spezifischen physikochemische Formen entscheidender sind, alsrndas Verhalten der gesamten Konzentration der Spurenmetalle in der Umwelt. Die Definition derrnArtbildung kann grob als die Identifizierung und Quantifizierung der verschiedenen Formen oderrnPhasen für ein Element zugeordnet werden. Die chemische Extraktion ist eine gemeinsamernSpeziierungstechnik bei der die Fraktionierung des Gesamtmetallgehaltes zur Analyse der Quellernanthropogener Metallkontamination und zur Vorhersage der Bioverfügbarkeit von verschiedenenrnMetallformen dient. Die Philosophie der partiellen und sequenziellen Extraktionsmethodernbesteht darin, dass insbesondere das Extraktionsmittel phasenspezifisch unter chemischemrnAngriff unterschiedlicher Mischungsformen steht. Die Speziation von Metall ist wichtig bei derrnBestimmung der Toxizität, Mobilität, Bioverfügbarkeit des Metalls und damit ihr Schicksal inrnder Umwelt und biologischem System. Die Artenbildungsanalyse kann für das Verständnis derrnAuswirkung auf die menschliche Gesundheit und bei ökologischen Risiken durch diernQuantifizierung von Metallspezies bei einem Untersuchungs-standort angewendet werden undrnanschließend können Sanierungsstrategien für den Standort umgesetzt werden. Mit Hilfe derrnSpezifizierung wurden Arsen und Kupfer in landwirtschaftlichem Kalkdünger und Thallium inrnkontaminierten Böden untersucht und in den folgenden Abschnitten im Einzelnen dargestellt.There is a long history of human using metals in developing an advanced technological society.rnIt has only been realized until the past century that metal’s chemical and radioactive propertiesrncan pose serious threat to mankind. In modern day geochemistry it is widely accepted that thernspecific physiochemical forms rather than the total concentration decides the ultimate trace metalrnbehavior in an environment. The definition of speciation can be broadly classified as thernidentification and quantification of the different forms or phases for an element. Chemicalrnextraction is a common speciation technique in which fractionating total metal content forrnanalyzing the source of anthropogenic metal contamination and also to predict bioavailability ofrnvarious metal forms. The philosophy of the partial and sequential extraction method is to assumernthat particular extractant is phase specific under chemical attack on a mixture of forms.rnSpeciation of metal is important in determining metal’s toxicity, mobility, bioavailability andrnhence their fate in environment and biological systems. Speciation analysis can be applied inrnunderstanding the impact on human health and ecological risks by quantifying the metal speciesrnat a sampling site and subsequently suitable remediation strategies can be implemented for thernlocation. Speciation of arsenic and copper in agricultural lime and thallium in contaminated soilsrnwere investigated and revealed in the following sections.268 S

Robust eigenstructure assignment under regional pole constraints

This paper provides a computational procedure for a type of robust regional pole assignment problem. It allows the closed-loop poles to be settled at certain perturbation insensitive locations within some prespecified regions in the complex plane. The novelty of our approach lies in the versatility of the proposed algorithm which provides a rich set of constrained regions for the assignment of individual or subsets of closed-loop poles in contrast to other conventional regional pole assignment methods. The algorithm is based on a gradient flow formulation on a potential function which provides a minimizing solution for the Frobenius condition number of the closed-loop state matrix.published_or_final_versio

Programmable control of CRISPR-Cas9 systems by engineering sgRNA as toehold- switchable riboregulators

Robust control over gene expression is necessary for diverse applications in molecular biology, synthetic biology, and biotechnology. One of the most promising strategies to exert these types of control is the recently developed CRISPR interference (CRISPRi) and activation (CRISPRa) approach, which provides simple and highly effective RNA-based methods for targeted silencing and upregulation of transcription in bacterial and eukaryotic cells. While these current methods are capable of sequence-specific targeting Please click Additional Files below to see the full abstract

An index of syntactic development for Cantonese-Chinese preschool children

This research study aimed to develop an index of syntactic development for Cantonese-speaking children. Language samples taken from 14 normal children aged from 4;1 to 5;0, 16 normal children aged from 5;1 to 6;5 and 15 SLI children aged from 5;1 to 6;4 were analyzed and credited according to the framework developed. Normal children aged from 4;1 to 5;0 performed poorer on the index than those aged from 5;1 to 6;5 with the same clinical status. Children with language difficulty performed poorer than their normal age peers on the index as well. The index was validated against MLU and the two indices moderately correlated with each other. A linear combination of age, D and the index was entered into discriminant analysis, yielding a classification accuracy of 86.7% of all the children. The index was found to be a potentially useful clinical marker of SLI yet replication is needed to confirm the findings. Further modification of the index was discussed. The age and language growth sensitivity of MLU was discussed as well.published_or_final_versionSpeech and Hearing SciencesBachelorBachelor of Science in Speech and Hearing Science

Dusty Radiative Transfer Modeling of the Ultraviolet to Infrared Spectral Energy Distributions of Nearby Galaxies

In normal star forming galaxies without active galactic nuclei, stars and dust dominate the energy output in the ultraviolet (UV), optical and infrared (IR). Knowledge of stellar populations and dust is crucial to understanding the evolution of galaxies in the universe. The problems of dust and stars are tightly related because dust absorbs stellar radiation in the UV and optical, and re-radiates it in the IR. To study the properties of interstellar dust and stellar populations, we fit the global spectral energy distributions (SEDs) of nearby galaxies using radiative transfer models. Thanks to various space missions in the last few decades, the data required to construct the full UV to IR SEDs of nearby galaxies is available. To date, systematic studies on interstellar dust and stellar populations rely on simplified connections between the UV and IR such as energy conservation. Based on dust grain physics, radiative transfer models physically couple the UV and IR for consistent radiation fields and dust emission spectra, but is computationally challenging. With the use of supercomputer facilities, we compute a large grid of radiative transfer models spanning the physical range of dust and stellar parameters. Fitting SEDs with the grid is one step towards a better understanding of interstellar dust and stellar populations. By fitting the SEDs of a group of nearby galaxies observed by the SINGS survey, we study the relative importance of young and old stellar populations in heating the dust, derive the ensemble properties of dust, estimate the total mass of dust, and test the robustness of the various star formation rate indicators in the literature

Anomalous Light Scattering by Topological PT{\mathcal{PT}}-symmetric Particle Arrays

Robust topological edge modes may evolve into complex-frequency modes when a physical system becomes non-Hermitian. We show that, while having negligible forward optical extinction cross section, a conjugate pair of such complex topological edge modes in a non-Hermitian $\mathcal{PT}$-symmetric system can give rise to an anomalous sideway scattering when they are simultaneously excited by a plane wave. We propose a realization of such scattering state in a linear array of subwavelength resonators coated with gain media. The prediction is based on an analytical two-band model and verified by rigorous numerical simulation using multiple-multipole scattering theory. The result suggests an extreme situation where leakage of classical information is unnoticeable to the transmitter and the receiver when such a $\mathcal{PT}$-symmetric unit is inserted into the communication channel.Comment: 16 pages, 8 figure

Accelerating wavepacket propagation with machine learning

In this work, we discuss the use of a recently introduced machine learning (ML) technique known as Fourier neural operators (FNO) as an efficient alternative to the traditional solution of the time‐dependent Schrödinger equation (TDSE). FNOs are ML models which are employed in the approximated solution of partial differential equations. For a wavepacket propagating in an anharmonic potential and for a tunneling system, we show that the FNO approach can accurately and faithfully model wavepacket propagation via the density. Additionally, we demonstrate that FNOs can be a suitable replacement for traditional TDSE solvers in cases where the results of the quantum dynamical simulation are required repeatedly such as in the case of parameter optimization problems (e.g., control). The speed‐up from the FNO method allows for its combination with the Markov‐chain Monte Carlo approach in applications that involve solving inverse problems such as optimal and coherent laser control of the outcome of dynamical processes