Harmonic rejection

Figure 12.1 SGX-CAT beamline schematic. The components of the beamline include (1 (not shown), 8) photon shutters (2,4) beam transport tubes (3, 5) collimators and vacuum pumps (6) beam-defining slits (7) monochromator (9,10) focusing and harmonic rejection mirrors and (12) CCD detector, supporting base, and sample robot.

Often the white beam is reflected by a mirror, which can be used for harmonic rejection and focusing on the sample. 

Even when the overall amplitude is incorrect — due to insufficient control of sample thickness or homogeneity, or poor X-ray harmonic rejection —, it is still possible to determine the ratio of successive number of neighbours within 20% error. 

A double crystal monochromator providing a 6kH of 10-4 is followed by a flat platinum coated mirror for harmonic rejection. A Huber five-circle diffractometer is mounted to allow the 30x30 cm2 two-dimen-... 

The use of a reactor in series with the ctipacitors w ill reduce the harmonic effects in a power network, as well as their effect on other circuits in the vicinity, such as a telecommunication network (see also Section 23.1 1 and Example 23.4). The choice of reactance should be such that it W ill provide the required detuning by resonating below the required harmonic, to provide a least impedance path for that harmonic and filter it out from the circuit. The basic idea of a filter circuit is to make it respond to the current of one frequency and reject all other frequency components. At power frequency, the circuit should act as a capacitive load and improve the p.f. of the system. For the fifth harmonic, for instance, it should resonate below X 50 Hz for a 50 Hz system, say at around 200-220 Hz, to avoid excessive charging voltages w hich may lead to... 

A pharmacopeial general chapter or other pharmacopeial document is harmonized when a pharmaceutical substance or product tested by the document s harmonized procedure yields the same results, and the same accept/reject decision is reached. ... 

When using a fully harmonized pharmacopeial monograph or general chapter, an analyst will perform the same procedures and reach the same accept/reject decisions irrespective of which PDG pharmacopeia is referenced. This approach is called interchangeability, and each pharmacopeia will identify, in an appropriate manner, such a monograph or general chapter. 

The long-term stability of an oral liquid formulation can also be affected by a number of unexpected reasons. Contamination by solvents used during the tank cleaning or even in the manufacture of excipients or API can be a source of instability of an oral solution. Uncontrolled levels of Class I, II, or III solvents could lead to the rejection of a batch or an excipient vendor. Class III solvents have a permitted daily exposure of 50 mg or less per day. (See the International Conferences on Harmonization, Impurities Guidelines for Residual Solvents. Q3C, Federal Register 1997 62(247) 67377 and also http //www.fda.gov/cvm/Guidance/guidelOO.PDF). 

The EU drug approval system is moving toward harmonization. A system that permits individual states to reject the centralized body s recommendation is a significant obstacle to this goal, however. One author has written... 

It is recognized that harmonized formats for data submissions are beneficial. Detailed guidance in this area wiU lead to a lower submission rejection rate by regulatory jurisdictions, will facilitate electronic submission, and will result in efficiency gains. There are several initiatives underway in this area. 

Inclusion or exclusion of outliers can significantly influence exposure assessments, and harmonized outlier rejection criteria are needed. The suitability of existing approaches (e.g. anything beyond three standard deviations is an outlier) to occupational exposure data sets, as well as the role of field study observations, needs to be considered. 

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