Contemporary Undergraduate Qualitative Analysis: Use of CCD‐Based Raman,Atomic Emission,and Reflectance Spectrometers

The classic undergraduate qualitative analysis is upgraded using a new generation of user‐friendly, low‐cost spectral instruments: (1) atomic emission spectrometer for identification of alkali and alkaline earth metals; (2) Raman spectrometer for identification of polyatomic ions; and (3) reflectance UV‐Vis spectrometer for enhancement of color spot tests on metal ions. Qualitative analysis of various inorganic samples using both traditional and modern spectral methods is described.     

Absorption-Amplification Response with or Without Spontaneously Generated Coherence in a Coherent Four-Level Atomic Medium

We discuss and analyze the absorption-amplification properties of a weak probe field in a typical fourlevel atomic system in the presence of an additional coherence term, the spontaneously generated coherence term. The influences of the spontaneously generated coherence and a coherent pump field on the probe absorption (amplification) are investigated in detail. We show that the absorption of such a weak probe field can be dramatically enhanced due to the presence of the spontaneously generated coherence. At the same time, the probe-absorption profile exhibits the double-peak structure and the probe-absorption peak gradually decreases as the pump intensity increases. On the contrary, the amplification of such a weak probe field near the line center of the probe transition can be achieved by adiusting the coherent Dump field intensity in the absence of the spontaneously generated coherence.     

An Overview of the Use of Yttrium for Internal Standardization in Inductively Coupled Plasma–Atomic Emission Spectrometry

Abstract

Internal standardization is a widely used method for compensating nonspectral interference in inductively coupled plasma (ICP) spectrometry. Emphasis is given on the choice of the suitable element and its specific spectral line as an efficient internal standard. This choice is the result of multi-variable evaluations and analytical applications. In inductively coupled plasma–atomic emission spectrometry (ICP-AES) and other spectrometric techniques several spectral lines of the same or different elements have been evaluated as potential internal standards. Yttrium spectral lines fulfill certain prerequisites and they are favored by a large number of researchers. In our discussed review, we present several reports of ICP-AES techniques that employ yttrium as the internal standard. These reports are classified according to specific sample origin and aim of the research.     

Determination of Trace Amounts of Zinc in Welding Fumes by Flow‐Injection Flame Atomic Absorption Spectrometry

A flow‐injection flame atomic absorption spectrometric method for the determination of zinc in welding fumes has been developed. The method is based on the continuous ultrasound‐assisted dissolution of the zinc oxide collected on the air filter. Variables such as sonication time, nature and concentration of the acid solution used as dissolving solution, dissolution temperature, flow rate of the continuous manifold, and dissolving solution volume were simultaneously studied by applying a Plackett–Burman design. Results showed that only the concentration of nitric acid solution used as dissolving solution was a statistically significant variable (confidence interval of 95%). Factors such as dissolution temperature and sonication time were finally optimized by using a central composite design. The detection limit was 1.1 µg/m³ and the repeatability of the overall method is 1.6% (n=11) for a zinc concentration of 75.4 µg/m³. The proposed method was applied to the determination of zinc in welders' workplace environments.     

Use and Evaluation of Newly Synthesized Fluorescence Probes to Detect Generated OH• Radicals in Fibroblast Cells

Reactive oxygen species (ROS) are pro-oxidant molecules synthesized in body with various functions and are essential for life. Increasing in reactive oxygen species or decreasing in antioxidants level cause oxidative stress which is very harmful. OH? radical is one of ROS’s, with tendency to bind to lipids, DNA and proteins which cause irreversible damage in cells. The most devastating consequences related to excess OH? radicals occur via direct binding to nucleic acids and proteins. Quantification of this high reactive radical with short life time is difficult. Electron Spin Resonance, Fluorescence, and Luminescence Spectroscopy are commonly used to determine the level of ROS. Fluorescence Probes have higher specificity and sensitivity with their excellent sensors to detect ROS’s compare to the other methods. Also, there are different probes specifically designed for each radical. The purpose of this study was to identify the probe better suiting for detection of OH? radical levels. The two most recommended fluorescence probes, 2-[6-(4 V-Hydroxy) phenoxy-3H-xanthen-3-on-9-yl]benzoic acid (HPF) and coumarin-3-carboxylic acid (3-CCA) to determine OH? radical levels were compared. Following the formation of OH? radical with Fenton reaction, HPF and 3-CCA probes were added to cells and spectrofluorometric measurements were performed in their respective wavelengths. The mean amplitude of fluorescence for HPF was 32.72?±?2.37 F.I (n?=?40) and for 3-CCA was 52.11?±?0.5 F.I (n?=?40). This difference was statistically significant. 3-CCA also demonstrated more stable measurements at different days compered to HPF.     

The Use of Solid‐Phase Supports for Derivatization in Chromatography and Spectroscopy

Abstract

Derivatization, or chemical modification of analytes, is often required for species that are only weakly detectable by common spectroscopic methods. Derivatization is most commonly performed in homogeneous solution or using phase‐transfer catalyzed reactions. However, the use of solid phase supports for performing the same reactions has a number of advantages. The sample can be “cleaned up” on the same phase, eliminating interfering matrix components or excess reagent. The process naturally concentrates the analyte, providing higher sensitivity, but also, under favorable circumstances, provides for more efficient reactions relative to solutions of the same original concentration. This review explores the uses to which such supports have been put, primarily in fluorescence derivatization for chromatographic applications. Some of the considerations in applying these techniques are described, and they are shown to be an extremely useful format for derivatization.     

Effects of Atomic Centre-of-mass Motion in T-C Model

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Thermoelastic Behavior of Polyurethanes Reinforced with the In situ‐Generated Sodium Silica‐Polyphosphate Nanophase

Segmented polyurethane‐based nanocomposites prepared by reaction between the organic precursor (macrodiisocyanate, MDIC) and the inorganic precursor (sodium silica‐polyphosphate, SSP) were characterized by differential calorimetry, wide‐angle and small‐angle X‐ray diffraction, and stretching calorimetry techniques.

Steric restrictions on the mobility of soft MDIC chain segments by a spatial network of self‐associated stiff segments were assumed responsible for the overshoot of experimental values of the glass transition temperature above that expected for completely miscible components. The initial spatial network of self‐associated stiff segments of the MDIC was destroyed by the randomly distributed SSP particles, giving rise to their own fractal‐like structure. Low reinforcement efficiency of the SSP nanophase was tentatively attributed to the relatively large size of its spatial aggregates. The scale of particle displacements within an infinite cluster during stretching is likely to be negligibly small.     

Use of wavelet in specifying optics

Using power spectral density (PSD) function to specify large aperture optical components' quality of laser system is universal. But it cannot provide effective guidance to eliminate certain frequency segment error. In order to solve this problem, two-dimensional discrete wavelet transform (2D-DWT) is used to separate frequency segment error and detect the corresponding region of certain frequency segment error, which is used as feedback to a machining process. The experimental results show that the corresponding region of certain frequency segment can be found and machining can be guided effectively by using wavelet.     

Determination of Iron in Abandoned Mine Drainage by UV‐Vis Spectrophotometry and Flame Atomic Absorption Spectrophotometry

This paper describes and compares the results obtained from determination of total iron in abandoned mine drainage (AMD) from selected sites in western Pennsylvania by UV‐visible spectrophotometry (UV‐Vis) and flame atomic absorption spectrophotometry (FAAS). As our laboratory possesses both methods, the accuracy and precision of iron results by UV‐Vis, using iron (II) chelator 2,4,6‐tripyridyl‐1,3,5‐triazine (TPTZ), and FAAS are of interest in the event of instrument problems with either method. Calibration curves show excellent linearity (R ²≥0.990). The results show good accuracy (complete recovery of spiked iron) and precision (0.5–3.4% RSD by UV‐Vis, 1.5–7.7% RSD by FAAS), indicating both methods are suitable for determination of iron in AMD. This comparison study is presented as a potential approach to teaching students about UV‐Vis and FAAS and their advantages and disadvantages.     

A Class of Representations of the ∗-Algebra of the Canonical Commutation Relations over a Hilbert Space and Instability of Embedded Eigenvalues in Quantum Field Models

Abstract

In models of a quantum harmonic oscillator coupled to a quantum field with a quadratic interaction, embedded eigenvalues of the unperturbed system may be unstable under the perturbation given by the interaction of the oscillator with the quantum field. A general mathematical structure underlying this phenomenon is clarified in terms of a class of Fock space representations of the ?-algebra of the canonical commutation relations over a Hilbert space. It is also shown that each of the representations is given as a composition of a proper Bogolyubov (canonical) transformation and a partial isometry on the Fock space of the representation.     

Infrared Spectroscopic Study of N,N‐Dimethylthioformamide Complexes of the Hofmann Type

Four new Hofmanntype complexes, M(DMTF)₂Ni(CN)₄, (where DMTF is dimethylthioformamide, M=Mn, Cd, Co, or Ni) were synthesized and their structure was determined by an elemental analysis and infrared spectroscopy. The IR spectra of DMTF and its nickel tetracyanine complexes with Mn(II), Cd(II), Co(II), and Ni(II) have been investigated within the range 4000–400 cm^–1. The frequency shifts in the metal complexes agree with the assignment of the CS and CN frequencies. The complexes consist of infinite planar polymer layers of |MNi(CN)₄|. Ndimethylthioformamide is coordinated to this layer from above and below; it is a monodentate ligand and is Sbonded through the metal atom in these complexes.     

Storage of a Light Pulse in an Atomic Medium

We perform a full numerical simulation to the electromagnetically induced transparency model in which the control beam is changed adiabatically.The numerical results show the whole process of storage and recovery for the signal pulse.This verifies a recent experiment and the approximate theoretical analysis.     

Recent Advances in Microwave Induced Plasma Atomic Emission Spectrometry with Okamoto‐Cavity

Abstract

Microwave induced plasmas with an Okamoto‐cavity (Okamoto‐cavity MIP) are noted as a new excitation source in atomic emission spectrometry. The Okamoto‐cavity MIP can be sustained with various plasma gases, and can produce each stable plasma with a high robustness against loading of various types of samples. For example, the oxygen‐containing MIP becomes an effective atomization and excitation source for direct injection of organic solvents analysis because they are completely burned in the plasma. In this review, the fundamental structure of the microwave cavity, the spectrochemical characteristics, and the analytical applications are summarized from reference papers.     

Sequential Injection/Mid-Infrared Spectroscopic Analysis of an Acetone‐Butanol‐Ethanol Fermentation: Analyte Cross‐Correlation Effects

Mid‐infrared spectroscopy together with sequential injection analysis (SIA) and partial least squares (PLS) regression analysis was used to monitor acetone‐butanol‐ethanol (ABE) fermentations under different fermentation conditions. Five analytes were simultaneously predicted (acetone, acetate, butyrate, n‐butanol, and glucose). In order to compare the overall model prediction ability, a relative average of the root mean square error of prediction (RMSEP) across all five analytes was employed. To form a PLS model devoid of any cross‐correlations between analytes, a synthetic calibration data set was created by the SIA system. As a test of their robustness, PLS models from synthetic samples and those from real fermentation samples were compared and used to predict samples from the opposite data set and from independent “acid‐crash” fermentations. The PLS model developed from the synthetic samples proved to be far more robust and accurate and used fewer factors than PLS models from the real fermentations, which were found to contain analyte cross‐correlations. The use of synthetic data enabled more accurate selection of factors and showed the importance of investigating spectral regression coefficients plots to aid and confirm appropriate factor selection. In addition, an alternative method of factor selection was proposed, using a “similarity measure” between the regression coefficient plots of factors for certain analytes and their standard spectra. Predictions using this method of factor selection over the common “minimum from an error vs. factor” plot proved to be more accurate and used far fewer factors.     

Measurement of the Stark Broadening of Atomic Emission Lines in Non–Optically Thin Plasmas by Laser‐Induced Breakdown Spectroscopy

We propose a new method for determining the Stark broadening of atomic emission lines using laser‐induced breakdown spectroscopy. The method allows the determination of the Stark broadening in non–optically thin plasmas, through the introduction of a correction for self‐absorption. Couples of lines of the same species are considered. If one of the Stark broadenings is known, the determination of the other does not require the measurement of the electron density of the plasma. Examples are given for the application of the proposed method to the measurement of the Stark broadening of several aluminum emission lines (Al I at 308.2 nm, Al I at 394.4 nm, and Al I at 396.2 nm).     

Transmission Probability of an Ultracold Atom in the Presence of Atomic Coherence

We investigate the transmission probability of an ultracold V-type three-level atom passing through a micromaser cavity,in the presence of atomic coherence which is established by a coherent driving field.We show that the transmissibility of this micromaser system with the atomic coherence is better than that of the ordinary micromaser system without atomic coherence.When the driving field is strong enough,for any cavity length the ultracold atom can pass through the micromaser cavity freely.     

Atomic mechanism of vitrification process in simple monatomic nanoparticles *

Glass formation in simple monatomic nanoparticles has been studied by molecular dynamics simulations in spherical model with a free surface. Models have been obtained by cooling from the melt toward glassy state. Atomic mechanism of glass formation was monitored via spatio-temporal arrangement of solid-like and liquid-like atoms in nanoparticles. We use Lindemann freezing-like criterion for identification of solid-like atoms which occur randomly in supercooled region. Their number grows intensively with decreasing temperature and they form clusters. Subsequently, single percolation solid-like cluster occurs at temperature above the glass transition. Glass transition occurs when atoms aggregated into this single percolation cluster are in majority in the system to form relatively rigid glassy state. Solid-like domain is forming in the center of nanoparticles and grows outward to the surface. We found temperature dependence of potential energy, mean-squared displacement (MSD) of atoms, diffusion constant, incoherent intermediate scattering function, radial distribution function (RDF), local bond-pair orders detected by Honeycutt-Andersen analysis, radial density profile and radial atomic displacement distributions in nanoparticles. We found that liquid-like atoms in models obtained below glass transition have a tendency to concentrate in the surface layer of nanoparticles. However, they do not form a purely liquid-like surface layer coated nanoparticles.     

Determination of Arsenic and Mercury in Chinese Medicinal Herbs by Atomic Fluorescence Spectrometry with Closed‐Vessel Microwave Digestion

Abstract

A simple method was developed for the determination of trace arsenic and mercury in Chinese medicinal herbs. The samples were digested in closed‐Teflon vessels in a microwave oven, and followed with hydride generation atomic fluorescence spectrometric measurements. The experimental conditions for the digestion were carefully optimized using an orthogonal design. The accuracy of the method was validated by recovery experiments, and the analytical results for arsenic in seven medicinal herbs (Codonopsis pilosula, Radix angelicae sinensis, Aconitum carmichaeli debx, crude aconite root, giant typhonium rhizome, Rhizoma typhonii, and Radix aconiti lateralis preparata) were found to agree well with those by inductively coupled plasma atomic emission spectrometry (ICP‐AES). The linear dynamic range of the calibration curve was in the range of 0.1–400 ng/mL for arsenic, and the correlation coefficient was better than 0.999. The limit of detection was 0.1 ng/mL for arsenic. For mercury, the determination was accomplished through mercury cold vapor generation in the same instrumental system. The linear dynamic range was 0.03–250 ng/mL, with a limit of detection of 0.03 ng/mL for mercury. This was a rapid, convenient, precise, and cost‐effective method.     

Incomplete Erasure of Which-Way Information Encoded in Atomic Hyperfine States

We propose an experimental scheme to investigate incomplete erasure of which-way information encoded in atomichy perfine states. Due to the incomplete erasure of the which-way information, it is shown that the interference patterns of the atomic wave packets initially confined in a spin-dependent optical lattice are destroyed to a certain extent, which provides a new straight way to test further the validity of the theoretical model developed in our recent work. The remarkable merit of the proposal is that it is simple and can be implemented easily.