The NMRPipe system is a UNIX software environment of processing, graphics, and analysis tools designed to meet current routine and research-oriented multidimensional processing requirements, and to anticipate and accommodate future demands and developments. The system is based on UNIX pipes, which allow programs running simultaneously to exchange streams of data under user control. In an NMRPipe processing scheme, a stream of spectral data flows through a pipeline of processing programs, each of which performs one component of the overall scheme, such as Fourier transformation or linear prediction. Complete multidimensional processing schemes are constructed as simple UNIX shell scripts. The processing modules themselves maintain and exploit accurate records of data sizes, detection modes, and calibration information in all dimensions, so that schemes can be constructed without the need to explicitly define or anticipate data sizes or storage details of real and imaginary channels during processing. The asynchronous pipeline scheme provides other substantial advantages, including high flexibility, favorable processing speeds, choice of both all-in-memory and disk-bound processing, easy adaptation to different data formats, simpler software development and maintenance, and the ability to distribute processing tasks on multi-CPU computers and computer networks.

NMRPipe: a multidimensional spectral processing system based on UNIX pipes

The detection and measurement of gas concentrations using the characteristic optical absorption of the gas species is important for both understanding and monitoring a variety of phenomena from industrial processes to environmental change. This study reviews the field, covering several individual gas detection techniques including non-dispersive infrared, spectrophotometry, tunable diode laser spectroscopy and photoacoustic spectroscopy. We present the basis for each technique, recent developments in methods and performance limitations. The technology available to support this field, in terms of key components such as light sources and gas cells, has advanced rapidly in recent years and we discuss these new developments. Finally, we present a performance comparison of different techniques, taking data reported over the preceding decade, and draw conclusions from this benchmarking.

/pdf/optical-gas-sensing-a-review-4uaf589xiq.pdf

Optical gas sensing: a review

A global network of ground-based Fourier transform spectrometers has been founded to remotely measure column abundances of CO_2, CO, CH_4, N_(2)O and other molecules that absorb in the near-infrared. These measurements are directly comparable with the near-infrared total column measurements from space-based instruments. With stringent requirements on the instrumentation, acquisition procedures, data processing and calibration, the Total Carbon Column Observing Network (TCCON) achieves an
accuracy and precision in total column measurements that is unprecedented for remotesensing observations (better than 0.25% for CO_2). This has enabled carbon-cycle science
investigations using the TCCON dataset, and allows the TCCON to provide a link between satellite measurements and the extensive ground-based in situ network.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2010.0240

The Total Carbon Column Observing Network

Introductory Fourier transform spectroscopy

Along more than a decade, R&D on supercritical fluid extraction (SFE) of vegetable matrices has been increasingly reported in the literature. Aiming at portraying the current state of this field and its evolution in terms of raw materials, products, modes of operation, optimization, modeling techniques, and closeness to industrial application, a large compilation of almost 600 essays from 2000 to 2013 has been deeply analyzed in order to unveil those indicators and their trends. Furthermore, strengths and weaknesses are identified, and some remarks that may drive upcoming research are provided. Globally, more than 300 species are reported in the literature, with prevalence of the extraction of seeds (28% of works) and leaves (17%). The main families of extracted compounds, cosolvents and operating conditions adopted are critically examined, being possible to conclude that researchers investigate many times working regions far from the optimum due to practical limitations or absence of experimental optimization. Current phenomenological, statistical and semi-empirical approaches are reviewed, along with scale-up studies, and economic analysis. In the whole, the most comprehensive picture over SFE of vegetable matrices is provided in this review, highlighting pertinent aspects and opportunities that may further consolidate the convincing route of this technology for the next years.

Supercritical fluid extraction of vegetable matrices: Applications, trends and future perspectives of a convincing green technology

High sensitivity in gas analysis with photoacoustic detection

I MATHEMATICAL FUNDAMENTALS: Basic Definitions General Properties of Fourier Transforms Discrete Fourier Transforms Fast Fourier Transforms Laplace and Other Integral Transforms II SPECTRAL APPLICATIONS: Fourier Transform Spectroscopy Fourier Transform Nuclear Magnetic Resonance (NMR) Spectrometry FT Ion Cyclotron Resonance Mass Spectrometry Diffraction and Fourier Transform Uncertainty Principle Signal Processing Fourier Self-Deconvolution Linear Prediction.

Fourier Transforms in Spectroscopy

Progress in cantilever enhanced photoacoustic spectroscopy

Theoretical considerations and a simple but realistic model of the function of the cantilever‐based photoacoustic trace gas system are presented. The essential features of the cantilever dynamics, thermal characteristics, and noise models are derived. Some other related constructions are shown with the practical implementations of the real system.

/pdf/photoacoustic-gas-analysis-using-interferometric-cantilever-3jenr0vmv8.pdf

Photoacoustic Gas Analysis Using Interferometric Cantilever Microphone

Recently introduced cantilever enhanced photoacoustic sensing has been applied to the tunable diode laser-based trace gas detection. The pressure variations due to the photoacoustic signal are detected with a miniature silicon cantilever, whose displacement is measured with a compact Michelson type laser interferometer. The system has been used to detect carbon dioxide (CO2) at 1572 nm with a distributed feedback diode laser. With a new photoacoustic cell, that was optimized for the laser sources, a normalized noise equivalent sensitivity of 1.7×10-10 cm-1W/\(\sqrt{Hz}\) at atmospheric pressure was realized. The result obtained in the non-resonant operation mode is at least 10 times better than in previous reports. The future improvements of the technique are also discussed.

Jyrki Kauppinen

Papers

High sensitivity in gas analysis with photoacoustic detection

Fourier Transforms in Spectroscopy

Progress in cantilever enhanced photoacoustic spectroscopy

Photoacoustic Gas Analysis Using Interferometric Cantilever Microphone

Cantilever enhanced photoacoustic detection of carbon dioxide using a tunable diode laser source