Development of a spectroscopic technique that enables the saliva based detection of COVID-19 at safe distances

The activated carbon of Eucalyptus globulus was tested for their effectiveness in removing hexavalent chromium from aqueous solution using column experiments. Result revealed that adsorption of chromium(VI) on eucalyptus bark carbon was endothermic in nature. Thermodynamic parameters such as the entropy change, enthalpy change and Gibbs free energy change were found to be 1.39 kJ mol−1 K−1, 1.08 kJ mol−1 and −3.85 kJ mol−1, respectively. Different chromium concentrations were used for the fixed bed adsorption studies. The pre- and post-treated adsorbents were characterized using a FTIR spectroscopic technique. It was concluded that Eucalyptus bark carbon column could be used effectively for removal of hexavalent chromium from aqueous solution at optimal column conditions. This study showed that this biological material is potential adsorbent of Cr(VI) from water.

Download Full-text

From Semiconductor to Metal in a Flash: Observing Ultrafast Laser-Induced Phase Transformations

MRS Proceedings ◽

10.1557/proc-481-395 ◽

1997 ◽

Vol 481 ◽

Cited By ~ 3

Author(s):

J. P. Callan ◽

A. M.-T. Kim ◽

L. Huangt ◽

E. N. Glezer ◽

E. Mazur

Keyword(s):

Phase Transformations ◽

Dielectric Function ◽

Spectral Range ◽

Laser Excitation ◽

Spectroscopic Technique ◽

Ultrafast Laser ◽

Lattice Heating ◽

Fs Laser

ABSTRACTWe use a new broadband spectroscopic technique to measure ultrafast changes in the dielectric function of a material over the spectral range 1.5–3.5 eV following intense 70-fs laser excitation. The results reveal the nature of the phase transformations which occur in the material following excitation. We studied the response of GaAs and Si. For GaAs, there are three distinct regimes of behavior as the pump fluence is increased — lattice heating, lattice disordering, and a semiconductor-to-metal transition.

Download Full-text

Monitoring microbial growth on a microfluidic lab-on-chip with electrochemical impedance spectroscopic technique

Biomedical Microdevices ◽

10.1007/s10544-021-00564-1 ◽

2021 ◽

Vol 23 (2) ◽

Author(s):

Subhan Shaik ◽

Aarthi Saminathan ◽

Deepak Sharma ◽

Jagdish A Krishnaswamy ◽

D Roy Mahapatra

Keyword(s):

Microbial Growth ◽

Electrochemical Impedance ◽

Spectroscopic Technique ◽

Lab On Chip ◽

On Chip ◽

Electrochemical Impedance Spectroscopic

Download Full-text

Bichromatic Photoassociation Spectroscopy for the Determination of Rotational Constants of Cs2 0 u + Long-Range State below the 6S1/2 + 6P1/2 Asymptote

Molecules ◽

10.3390/molecules25173963 ◽

2020 ◽

Vol 25 (17) ◽

pp. 3963

Author(s):

Jizhou Wu ◽

Jie Ma ◽

Yuqing Li ◽

Wenliang Liu ◽

Peng Li ◽

...

Keyword(s):

Long Range ◽

Spectroscopic Technique ◽

Rigid Rotor ◽

Simple Analysis ◽

Rotational Constants ◽

Vibrational Levels ◽

Photoassociation Spectroscopy ◽

Rotor Model ◽

Good Agreement

This article demonstrates new observation of the high-resolution ro-vibrational bichromatic photoassociation spectra (BPAS) of Cs2 in the 0u+ long-range state below the asymptotes 6S1/2 + 6P1/2. By combining with a modulation spectroscopic technique, precise references of the frequency differences have been engineered through the BPAS, with which the rotational constants of low-lying vibrational levels of the Cs20u+ long-range state have been accurately determined by fitting the frequency differences to the non-rigid-rotor model. The rotational constants for the newly observed seven ro-vibrational levels are summarized and disagreement for the level ῦ = 498 is clarified. The rotational constants of different vibrational levels demonstrate strong perturbations of the related energy structures. A simple analysis is performed and shows good agreement with experimental results.

Download Full-text

Variety Identification of Orchids Using Fourier Transform Infrared Spectroscopy Combined with Stacked Sparse Auto-Encoder

Molecules ◽

10.3390/molecules24132506 ◽

2019 ◽

Vol 24 (13) ◽

pp. 2506 ◽

Cited By ~ 1

Author(s):

Yunfeng Chen ◽

Yue Chen ◽

Xuping Feng ◽

Xufeng Yang ◽

Jinnuo Zhang ◽

...

Keyword(s):

Fourier Transform ◽

Principal Component ◽

Fourier Transform Infrared ◽

Spectroscopic Technique ◽

Variety Identification ◽

Support Vector ◽

K Nearest Neighbors ◽

Discriminant Models ◽

The Fourier Transform ◽

Better Than

The feasibility of using the fourier transform infrared (FTIR) spectroscopic technique with a stacked sparse auto-encoder (SSAE) to identify orchid varieties was studied. Spectral data of 13 orchids varieties covering the spectral range of 4000–550 cm−1 were acquired to establish discriminant models and to select optimal spectral variables. K nearest neighbors (KNN), support vector machine (SVM), and SSAE models were built using full spectra. The SSAE model performed better than the KNN and SVM models and obtained a classification accuracy 99.4% in the calibration set and 97.9% in the prediction set. Then, three algorithms, principal component analysis loading (PCA-loading), competitive adaptive reweighted sampling (CARS), and stacked sparse auto-encoder guided backward (SSAE-GB), were used to select 39, 300, and 38 optimal wavenumbers, respectively. The KNN and SVM models were built based on optimal wavenumbers. Most of the optimal wavenumbers-based models performed slightly better than the all wavenumbers-based models. The performance of the SSAE-GB was better than the other two from the perspective of the accuracy of the discriminant models and the number of optimal wavenumbers. The results of this study showed that the FTIR spectroscopic technique combined with the SSAE algorithm could be adopted in the identification of the orchid varieties.

Download Full-text

A Purely Spectroscopic Technique for Determining Energy Band Offsets in Quantum Wells

MRS Proceedings ◽

10.1557/proc-240-99 ◽

1991 ◽

Vol 240 ◽

Cited By ~ 1

Author(s):

Emil S. Koteies

Keyword(s):

Quantum Wells ◽

Valence Band ◽

Accurate Determination ◽

Energy Difference ◽

Spectroscopic Technique ◽

Band Offsets ◽

Band Energy ◽

Semiconductor Quantum Wells ◽

Sensitive Function

ABSTRACTWe have developed a novel experimental technique for accurately determining band offsets in semiconductor quantum wells (QW). It is based on the fact that the ground state heavy- hole (HH) band energy is more sensitive to the depth of the valence band well than the light-hole (LH) band energy. Further, it is well known that as a function of the well width, Lz, the energy difference between the LH and HH excitons in a lattice matched, unstrained QW system experiences a maximum. Calculations show that the position, and more importantly, the magnitude of this maximum is a sensitive function of the valence band offset, Qy, which determines the depth of the valence band well. By fitting experimentally measured LH-HH splittings as a function of Lz, an accurate determination of band offsets can be derived. We further reduce the experimental uncertainty by plotting LH-HH as a function of HH energy (which is a function of Lz ) rather than Lz itself, since then all of the relevant parameters can be precisely determined from absorption spectroscopy alone. Using this technique, we have derived the conduction band offsets for several material systems and, where a consensus has developed, have obtained values in good agreement with other determinations.

Download Full-text

Terahertz Spectroscopy of Novel Superconductors

Advances in Condensed Matter Physics ◽

10.1155/2011/816906 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 5

Author(s):

Stefano Lupi

Keyword(s):

Synchrotron Radiation ◽

Fermi Energy ◽

Terahertz Spectroscopy ◽

Signal To Noise Ratio ◽

Spectroscopic Technique ◽

Signal To Noise ◽

Boron Doped Diamond ◽

Boron Doped ◽

Reflectivity Spectra ◽

Michelson Interferometry

Through the coupling of Synchrotron Radiation and Michelson interferometry, one may obtain in the terahertz (THz) range transmittance and reflectivity spectra with a signal-to-noise ratio (S/N) up to 103. In this paper we review the application of this spectroscopic technique to novel superconductors with an increasing degree of complexity: the single-gap boron-doped diamond; the isotropic multiband V3Si, where superconductivity opens two gaps at the Fermi energy; the CaAlSi superconductor, isostructural to MgB2, with a single gap in the hexagonal ab plane and two gaps along the orthogonalcaxis.

Download Full-text

ANALYSIS OF COPPER COINS BY EDXRF TECHNIQUE

International Journal of PIXE ◽

10.1142/s0129083504000197 ◽

2004 ◽

Vol 14 (03n04) ◽

pp. 133-139 ◽

Cited By ~ 4

Author(s):

T. R. RAUTRAY ◽

V. VIJAYAN ◽

P. K. NAYAK ◽

S. JENA

Keyword(s):

Trace Elements ◽

Major And Trace Elements ◽

Spectroscopic Technique ◽

Energy Dispersive ◽

Historical Events ◽

Trade Routes ◽

X Ray ◽

Edxrf Technique ◽

Non Destructive ◽

Archaeological Objects

Coins are important archaeological objects that can provide useful information regarding preparation methodology and provenance. Their classification plays a fundamental role in dating historical events, in constructing trade routes and in establishing the welfare of population. Several Indian copper coins of different periods have been studied using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopic technique. The method is rapid, efficient, multi elemental and non-destructive in nature. Concentrations of the major and trace elements like Ca , Ti , V , Cr , Mn , Fe , Co , Ni , Cu , Zn , As and Pb have been estimated in these copper coins. In the present investigation, an attempt has been made to characterize some Indian copper coins of different periods using EDXRF technique.

Download Full-text