scholarly journals Real time band selective F 1 -decoupled proton NMR for the demixing of overlay spectra of chiral molecules

2016 ◽  
Vol 55 (6) ◽  
pp. 553-558 ◽  
Author(s):  
Nilamoni Nath ◽  
Ajay Verma ◽  
Bikash Baishya ◽  
Chunni Lal Khetrapal
Keyword(s):  
Real Time ◽  
Proton Nmr ◽  
Chiral Molecules ◽  
Time Band

Real-time band structure changes of GaAs during continuous dynamic compression to 5 GPa

2009 ◽  
Vol 95 (15) ◽  
pp. 152108 ◽  
Author(s):  
P. Grivickas ◽  
M. D. McCluskey ◽  
Y. M. Gupta
Keyword(s):  
Band Structure ◽  
Real Time ◽  
Dynamic Compression ◽  
Structure Changes ◽  
Continuous Dynamic ◽  
Time Band

Enantiomeric Excess Determination by Fourier Transform Near-Infrared Vibrational Circular Dichroism Spectroscopy: Simulation of Real-Time Process Monitoring

2005 ◽  
Vol 59 (9) ◽  
pp. 1114-1124 ◽  
Author(s):  
Changning Guo ◽  
Rekha D. Shah ◽  
Rina K. Dukor ◽  
Xiaolin Cao ◽  
Teresa B. Freedman ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Circular Dichroism ◽  
Real Time ◽  
Near Infrared ◽  
Fractional Composition ◽  
Enantiomeric Excess ◽  
Flow Cell ◽  
Vibrational Circular Dichroism ◽  
Chiral Molecules ◽  
Circular Dichroïsm

The first use of near-infrared (NIR) Fourier transform vibrational circular dichroism (FT-VCD) to follow changes in the enantiomeric excess (EE) of chiral sample molecules in time using a flow-cell sampling apparatus is reported. Simultaneous changes in the fractional composition and the EE of a mixture of two different chiral molecules were monitored as a function of time. This simulates the progress of the chemical reaction from a chiral reactant to a chiral product where the mole fractions and EE values of both species may change with time. For the molecules studied, α-pinene, camphor, and borneol, the accuracy of following EE changes for one species alone is approximately 2%, while for simultaneously following EE changes in two species it is approximately 3% for 30 min sampling periods at 16 cm−1 spectral resolution. These findings demonstrate the potential for VCD to be used in the NIR region for real-time monitoring of the composition and %EE of chemical reactions involving the synthesis of chiral molecules.

Usefulness of Real‐Time Band Enhancement in Differential Diagnosis of Colorectal Tumors

1995 ◽  
Vol 7 (4) ◽  
pp. 397-400 ◽  
Author(s):  
Akitada ISO ◽  
Seiji SHIMIZU ◽  
Masahiro TADA ◽  
Keiichi KAWAI
Keyword(s):  
Differential Diagnosis ◽  
Real Time ◽  
Colorectal Tumors ◽  
Time Band

Modulating Band Gap Structure by Parametric Excitations

2018 ◽  
Vol 85 (6) ◽  
Author(s):  
Xiao-Dong Yang ◽  
Qing-Dian Cui ◽  
Ying-Jing Qian ◽  
Wei Zhang ◽  
C. W. Lim
Keyword(s):  
Band Gap ◽  
Real Time ◽  
Periodic Structures ◽  
One Dimensional ◽  
Time Dynamic ◽  
Time Band ◽  
Band Gap Structure ◽  
Band Gap Modulation ◽  
Wave Properties ◽  
Gap Structure

Artificial periodic structures are used to control spatial and spectral properties of acoustic or elastic waves. The ability to exploit band gap structure creatively develops a new route to achieve excellently manipulated wave properties. In this study, we introduce a paradigm for a type of real-time band gap modulation technique based on parametric excitations. The longitudinal wave of one-dimensional (1D) spring-mass systems that undergo transverse periodic vibrations is investigated, in which the high-frequency vibration modes are considered as parametric excitation to provide pseudo-stiffness to the longitudinal elastic wave in the propagating direction. Both analytical and numerical methods are used to elucidate the versatility and efficiency of the proposed real-time dynamic modulating technique.

Some Recent Results in Quiescent Prominence Spectrometry

1979 ◽  
Vol 44 ◽  
pp. 41-47
Author(s):  
Donald A. Landman
Keyword(s):  
Real Time ◽  
Computer System ◽  
Spectral Response ◽  
Absolute Intensity ◽  
Solar Observatory ◽  
Target Size ◽  
Small Target ◽  
Signal Averaging ◽  
Quiescent Prominence

This paper describes some recent results of our quiescent prominence spectrometry program at the Mees Solar Observatory on Haleakala. The observations were made with the 25 cm coronagraph/coudé spectrograph system using a silicon vidicon detector. This detector consists of 500 contiguous channels covering approximately 6 or 80 Å, depending on the grating used. The instrument is interfaced to the Observatory’s PDP 11/45 computer system, and has the important advantages of wide spectral response, linearity and signal-averaging with real-time display. Its principal drawback is the relatively small target size. For the present work, the aperture was about 3″ × 5″. Absolute intensity calibrations were made by measuring quiet regions near sun center.

Video real-time imaging of artificial membranes during freeze-drying by cryo-electron microscopy

1988 ◽  
Vol 46 ◽  
pp. 16-17
Author(s):  
Alan S. Rudolph ◽  
Ronald R. Price
Keyword(s):  
Real Time ◽  
Self Assembly ◽  
Freeze Drying ◽  
Video Capture ◽  
Drying Process ◽  
Artificial Membranes ◽  
The Past ◽  
Cryo Electron Microscopy ◽  
Spherical Structures ◽  
Capture Techniques

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.

An Interactive Minicomputer Program for the Indexing and Simulation of Electron Diffraction Patterns

1976 ◽  
Vol 34 ◽  
pp. 542-543
Author(s):  
R.P. Goehner ◽  
W.T. Hatfield ◽  
Prakash Rao
Keyword(s):  
Electron Diffraction ◽  
Real Time ◽  
Pattern Analysis ◽  
Flow Diagram ◽  
Hard Copy ◽  
Time Analysis ◽  
Real Time Analysis ◽  
Transmission Electron ◽  
One Step ◽  
Diffraction Patterns

Computer programs are now available in various laboratories for the indexing and simulation of transmission electron diffraction patterns. Although these programs address themselves to the solution of various aspects of the indexing and simulation process, the ultimate goal is to perform real time diffraction pattern analysis directly off of the imaging screen of the transmission electron microscope. The program to be described in this paper represents one step prior to real time analysis. It involves the combination of two programs, described in an earlier paper(l), into a single program for use on an interactive basis with a minicomputer. In our case, the minicomputer is an INTERDATA 70 equipped with a Tektronix 4010-1 graphical display terminal and hard copy unit.A simplified flow diagram of the combined program, written in Fortran IV, is shown in Figure 1. It consists of two programs INDEX and TEDP which index and simulate electron diffraction patterns respectively. The user has the option of choosing either the indexing or simulating aspects of the combined program.

Microstructural investigation of surface roughness in MBE-grown AlAs

1995 ◽  
Vol 53 ◽  
pp. 454-455
Author(s):  
R. Rajesh ◽  
R. Droopad ◽  
C. H. Kuo ◽  
R. W. Carpenter ◽  
G. N. Maracas
Keyword(s):  
Thin Film ◽  
Real Time ◽  
Growth Control ◽  
Native Oxide ◽  
Effusion Cell ◽  
Surface Oxide Layer ◽  
Microstructural Investigation ◽  
Mbe Growth ◽  
Film Substrate ◽  
And Control

Knowledge of material pseudodielectric functions at MBE growth temperatures is essential for achieving in-situ, real time growth control. This allows us to accurately monitor and control thicknesses of the layers during growth. Undesired effusion cell temperature fluctuations during growth can thus be compensated for in real-time by spectroscopic ellipsometry. The accuracy in determining pseudodielectric functions is increased if one does not require applying a structure model to correct for the presence of an unknown surface layer such as a native oxide. Performing these measurements in an MBE reactor on as-grown material gives us this advantage. Thus, a simple three phase model (vacuum/thin film/substrate) can be used to obtain thin film data without uncertainties arising from a surface oxide layer of unknown composition and temperature dependence.In this study, we obtain the pseudodielectric functions of MBE-grown AlAs from growth temperature (650°C) to room temperature (30°C). The profile of the wavelength-dependent function from the ellipsometry data indicated a rough surface after growth of 0.5 μm of AlAs at a substrate temperature of 600°C, which is typical for MBE-growth of GaAs.

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