Crystal detection

A model for crystallization point of the urea melt sprayed into the granulator was developed based on acoustic spectra recorded from sensor position A during a trial period of 24 hours. A flow sheet of the liquid urea feed process can be seen in Figure 9.7. Sensor A is mounted onto an orifice plate inserted in the main supply pipeline of liquid urea (see Figures 9.6 and 9.7). The reference values used to calibrate the model are the crystallization temperature (called the jc point ), as determined by the pilot plant laboratory (heat table visual nucleation/crystallization detection). 

For high-throughput data collection, sample centring via loop detection is currently the method of choice for placing crystals in the X-ray beam. Alternative methods rely on the direct detection of the crystal itself by monitoring the intensity of either X-ray diffraction from the crystal or X-ray fluorescence from an element in the crystal that is not present in the cryoprotectant (Pohl et al., 2004). Both of these approaches have drawbacks. First, some of the limited X-ray lifetime of the crystal (Section 12.6) must be committed to detection instead of data collection. Second, the loop itself has to be placed close to the X-ray beam prior to crystal detection, followed by step-wise translation of the crystal through the beam, thereby increasing the time required to centre the sample. 

PQCD piezoelectric quartz crystal detection/detector... 

J.-M. Kim, S.M. Chang, Y. Suda and H. Muramatsu, Stability study of carbon graphite covered quartz crystal. Sensors and Actuators, A 72 (1999) pp. 140-147. Y.-C. Chao and J.-S. Shih, Adsorption study of organic molecules on fiillerene with piezoelectric crystal detection system. Anal. Chim. Acta, 374 (1998) pp. 39-46. 

Chao, Y.-C. and Shih, J.-S. (1998). Adsorption study of organic molecules on fuUerene with piezoelectric crystal detection system. Anal. Chim. Acta, 374, 39— 46. 

C. S. I. Lai, G. J. Moody, and J. D. R. Thomas, Piezoelectric Quartz Crystal Detection of Ammonia Using Pyridoxine Hydrochloride Supported on a Polyethoxylate Matrix. Analyst, 111 (1986) 511. 

Figure13.1. Energy levels and spectra in ESR spectroscopy. A Energy levels for an unpaired electron in a magnetic field. B ESR absorption peak RF power (P) absorbed vs. magnetic field. C ESR first-derivative presentation—change of power absorbed per unit change in magnetic field vs. magnetic field. AH is the peak-to-peak line width. The first-derivative spectrum is the usual form obtained using ESR spectrometers, since phase-sensitive crystal detection of the microwave power absorbed by the sample is usually employed.

Shishido A, et al. 1997. Rapid optical switching by means of photoinduced change in refractive index of azobenzene liquid crystals detected by reflection mode analysis. J Am Chem Soc 119(33) 7791 7796. 

In conclusion, we describe two phenomena between which there exists a certain relationship. The first phenomenon consists of a high near-surface conduction of ice the near-surface layer, several nanometers in thickness, may possess a conductivity comparable with that of a macroscopic crystal. Detection of this phenomenon necessitates use of special experimental techniques (guard ring) for measuring conductivities and undoubtedly indicates a peculiar state of the protonic system in the near-surface layer" . 

Pak J, Wunderlich B (2002) Reversible Melting of Polyethylene Extended-chain Crystals Detected by Temperature-modulated Calorimetry. J Polymer Sci, Part B Polymer Phys 40 2219-2227. 

As the amount of iron increases in the powders (above 50 at.%), the number of different crystals detected on the agglomerate surfaces also increases. In the powders electrodeposited from the solutions with Ni/Fe = 1/3, a very small amount of agglomerates is covered with spherical crystals, while most of them are characterized with the presence of several different shapes of crystals. These crystals are presented in Fig. 8.24a-f. It is quite difficult to explain the reasons for their appearance, since so many different phases do not exist in the Fe-Ni system and the only reasonable explanations could be that these crystals represent some superstructures formed under massive hydrogen evolution. Their shapes could be defined as follows (a) Christmas tree-like crystals, (b) triangle-like crystals growing layer by layer, (c) propeller-like crystals, (d) plate-like crystals, (e) tetrahedral crystals, and (f) traversed polyhedron. 

The Au NPs-rGO composites material was characterized by powder X-ray diffraction (pXRD) (as shown in Figure 4.6). pXRD is an essential characterizing device to resolve difficulties related to crystal structure of solid, determination of crystallite size, orientation of crystal, detection of unidentified material, etc. In the area of NPs characterization, XRD holds... 

Kurosawa S, Kamo N, Matsui D, Kobatake Y (1990) Gas sorption to plasma-polymerized copper phthalocyanine film formed on a piezoelectric crystal. Anal Chem 62 353-359 Lai CSI, Moody GJ, Thomas JDR (1986) Piezoelectric quartz crystal detection of ammonia using pyridoxine hydrochloride supported on a polyethoxylate matrix. Analyst 111 511-515 LaMn KM (2005) Thin film resonator technology. IEEE Trans Ultrason Ferroelectr 52 707-716 Lang SB (2005) Pyroelectricity from ancient curiosity to modem imaging tool. Phys Today 58 31-36 Lee L-H (1991) Fundamentals of adhesion. Plenum, New York... 

Figure 19. Experimental arrangement for observation of stimulated emission in a a-8T single crystal. All molecules are aligned parallel to each other and make a 24° tilt angle with the (b,c) plane of the crystal. Detection is performed through an optical fiber positioned close to the upper edge of the crystal at an angle of 30°. From ref. [114].

So, not only the bulky M0O3 crystals detected in XRD on the WI samples are responsible for imposing a hmit in the activity of Mo03/Si02-Al203 catalysts. Also the very small (< 5 mn) ciystalhtes left after thermal spreading are inactive in the metathesis reaction. 

Lai C.S.I., Moody G.J., Thomas J.D.R., Mulligan D.C., Stoddart J.F. and Zarzycki R. (1988) Piezoelectric quartz crystal detection of benzene vapour using chemically modified cyclodextrins. J. Chem. Soc. Perkin Trans., 2,319-324. 

---