Shape discrimination

The morphology of particles is an important characteristic that can seriously affect powder handling and end-use properties. Off-line techniques are often not suitable for monitoring industrial processes since extracting the particles from the process can alter their shape, e.g. particles taken from a crystallizer may fracture or aggregate. 

To resolve the problem an in-line camera, capable of imaging crystals produced in a commercial crystallizer, was developed [331]. The instrument is based on a borescope and video camera that fits inside the housing of a laser backscatter probe, which installs in a standard ball valve. A strobe light is used to freeze crystal motion. Crystal features seen directly include shape, surface roughness, inclusions and transparency. 

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Rutherford, W. M., Evans, J., Currie, L. A., The Application of Isotopic Enrichment and Pulse Shape Discrimination to the Measurement of Atmospheric 37Ar, Anal. Chem., 48, 607 (1976). 

The alkaloid adsorbed on the platinum surface could form a tridimensional space within which the hydrogenation reaction can preferentially occur, due to a close interaction with QN. This space was called chiral pocket in analogy to biological systems that show high differentiation ability due to shape discrimination (Figure 14.11). 

Cinchonidine promotes the enantioselective hydrogenation of ethyl pymvate even when the hydroxy group is O-methylated. This behavior supports the shape discrimination rather than the participation of a guiding group that is able to produce a second interaction. Nevertheless, it is also... 

Sander, L.C., Parris, R.M., Wise, S.A., and Garrigues, R, Shape discrimination in liquid chromatography using charge transfer phases, Anal Chem., 63, 2589, 1991. 

Since the fast centrifuge system SISAK is equipped with liquid scintillation counting LSC [12,58], it is in principle capable of investigating short-lived a-decaying nuclides of the transactinides, p/y pulses and a pulses are distinguished by pulse-shape discrimination PSD and pile-up pulses are rejected by a pile-up rejection system PUR. This analog electronics proved to result in insufficient background suppression. Thus, two new approaches... 

Quantification of aroma compounds using GC and internal reference has long been a problematic issue.81 Detection response factor, peak shape, discrimination phenomenon at the injector port, and, of course, disproportion during sample preparation were more or less unavoidable. Stable isotopes used as internal standards combined with an MS detector have realized reproducible and far more accurate quantification. The major drawback of this method is the tedious process of preparing the isotope-labeled standards. 

Transmission electron microscopy imaging of a thin section of FeZSM-5 particles reveals that they are aggregates of smaller FeZSM-5 crystallites. Unstirred gels produce aggregates with small crystals in the center surrounded by larger crystals, while the agglomerates from stirred gels are formed without size or shape discrimination. 

If the last extractant is also a scintillator such as ETRAC s STRONEX, the equilibrated organic phase can be counted directly in a beta-liquid-scintillation counter or in a PERALS spectrometer. The carboxylic acid is not colored and does not quench. The PERALS spectrometer provides better beta-energy resolution and has only slightly lower counting efficiency for betas and thus may offer some advantage if both Sr and Sr are required in the same sample. The PERALS spectrometer will provide better separation of the 0.546 MeV Sr, the 1.48 MeV Sr, and the 2.28 MeV Y. In addition, if radium is present, the pulse shape discrimination feature of the PERALS spectrometer can be used to reject the contribution from radium alphas. 

The term timing refers to the determination of the time of arrival of a pulse. Timing experiments are used in measurement of the time development of an event (e.g., measurement of the decay of a radioactive species), measurement of true coincident events out of a large group of events, and discrimination of different types of particles based on the different time characteristics of their pulse (pulse-shape discrimination). 

Pulse-shape discrimination (PSD) is the name given to a process that differentiates pulses produced by different types of particles in the same detector. Although PSD has found many applications, its most common use is to discriminate between pulses generated by neutrons and gammas in organic scintillators (see also Chap. 14), and it is this type of PSD that will be discussed. 

Chiussi R (2003) Orientation and shape discrimination in juveniles and adults of the mangrove crab Aratus pisonii (H. Milne Edwards, 1837) effect of predator and chemical cues. Mar Freshw Behav Phy 36 41-50... 

Since the signal separation from the prime and rear detector primarily depends on the pulse shape discrimination and the expected event rate in the shield detector is much larger both due to large area and the higher detection efficiency, an ultra-fast RTD system is essential for a very low dead-time. We have developed... 

Bertrand GHV, Hamel M, Normand S, Sguerra F (2015) Pulse shape discrimination between (fast or thermal) neutrons and gamma rays with plastic scintillators state of the art. Nucl Instmm Methods Phys Res Sect A Accelerators Spectrometers Detectors Assoc Equip 776 114-128... 

Kawakami et al. (1996) thermally cured aromatic PI membranes at 150°C, 200°C, and 250°C to study the gas transport properties of the modified membranes. The gas permeability of CO2, O2, N2, and CH4 for the modified membranes was measured at 35°C and at pressure up to 10 bar. The gas selectivities for the PI membranes cured at 250°C were enhanced due to an increase in the diffusivity selectivities. Formation of CTCs observed in the PI increased the packing density of the polymer chain and decreased the free volume, thereby leading to an increase in diffusivity selectivities. Thus, it is considered that the suppression of chain mobility by the CTCs provides high size and shape discrimination between the gas molecules. 

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