13 research outputs found
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The principles underlying the use of powder diffraction data in solving pharmaceutical crystal structures
Solving pharmaceutical crystal structures from powder diffraction data is discussed in terms of the methodologies that have been applied and the complexity of the structures that have been solved. The principles underlying these methodologies are summarized and representative examples of polymorph, solvate, salt and cocrystal structure solutions are provided, together with examples of some particularly challenging structure determinations
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Salt and ionic cocrystalline forms of amides: protonation of carbamazepine in aqueous media
The products of reactions of the pharmaceutical amide carbamazepine (CBZ) with strong acids under aqueous conditions were investigated by both powder and single crystal X-ray diffraction. Despite previous claims to the contrary, it was found that salt forms with CBZ protonated at the amide O atom could be isolated from reactions with both HCl and HBr. These forms include the newly identified hydrate phase [CBZ(H)][Cl]·H O. Reactions with other mineral acids (HI and HBF ) gave ionic cocrystalline (ICC) forms (CBZ· [acridinium][I ]·2.5I and CBZ·[H O ] [BF ] ·H O) as well as the salt form CBZ·[CBZ(H)][BF ]·0.5H O. Reaction 2 4 3 2 5 2 0.25 4 0.25 2 4 2 of CBZ with a series of sulfonic acids also gave salt forms, namely, [CBZ(H)][O SC H ], [CBZ(H)][O SC H (OH)]· 3 6 5 3 6 4 0.5H O, [CBZ(H)] [O SCH CH SO ], and [CBZ(H)][O SC H (OH) (COOH)]·H O. CBZ and protonated CBZ(H) 2 2 3 2 2 3 3 6 3 2 moieties can be differentiated in the solid state both by changes to molecular geometry and by differing packing preference
Planck pre-launch status: calibration of the Low Frequency Instrument flight model radiometers
The Low Frequency Instrument (LFI) on-board the ESA Planck satellite carries
eleven radiometer subsystems, called Radiometer Chain Assemblies (RCAs), each
composed of a pair of pseudo-correlation receivers. We describe the on-ground
calibration campaign performed to qualify the flight model RCAs and to measure
their pre-launch performances. Each RCA was calibrated in a dedicated
flight-like cryogenic environment with the radiometer front-end cooled to 20K
and the back-end at 300K, and with an external input load cooled to 4K. A
matched load simulating a blackbody at different temperatures was placed in
front of the sky horn to derive basic radiometer properties such as noise
temperature, gain, and noise performance, e.g. 1/f noise. The spectral response
of each detector was measured as was their susceptibility to thermal variation.
All eleven LFI RCAs were calibrated. Instrumental parameters measured in these
tests, such as noise temperature, bandwidth, radiometer isolation, and
linearity, provide essential inputs to the Planck-LFI data analysis.Comment: 15 pages, 18 figures. Accepted for publication in Astronomy and
Astrophysic
Planck pre-launch status: Low Frequency Instrument calibration and expected scientific performance
We give the calibration and scientific performance parameters of the Planck
Low Frequency Instrument (LFI) measured during the ground cryogenic test
campaign. These parameters characterise the instrument response and constitute
our best pre-launch knowledge of the LFI scientific performance. The LFI shows
excellent stability and rejection of instrumental systematic effects;
measured noise performance shows that LFI is the most sensitive instrument of
its kind. The set of measured calibration parameters will be updated during
flight operations through the end of the mission.Comment: Accepted for publications in Astronomy and Astrophysics. Astronomy &
Astrophysics, 2010 (acceptance date: 12 Jan 2010
N-(2-Carboxyethyl)-2,5-dideoxy-2,5-imino-D-mannonic acid [(3R,4R,5R)-1-(2-carboxyethyl)-3,4-dihydroxy-5-hydroxymethyl-L-proline]
The absolute stereochemistry of the title compound, C9H 15NO7, was determined from the use of D-glucuronolac-tone as the starting material. The compound crystallizes as the zwitterion. The five-membered ring adopts an envelope conformation with the -CH 2OH-substituted C atom forming the flap. An intramolecular N - H···O hydrogen-bond occurs. In the crystal, the compound exists as a three-dimensional O - H···O intermolecular hydrogen-bonded network with each molecule acting as a donor and acceptor for four hydrogen bonds
Authority of Law
Law transforms our lives in the most important way: it changes how we act and because of this it gives rise to fundamental questions. One such question concerns legal authority and individual autonomy and asks; if we are autonomous agents how do legislators, judges and officials have legitimate authority to change our actions and indirectly change how we conduct our lives? We conceive ourselves as active agents who determine how and when to act, and we conceive ourselves as the planners of our own lives and the creators of change. Law asks us, however, to perform actions that range from the trivial to the complex. But how is it possible for me to do, in full awareness, as the law asks and, at the same time, be in control of my own destiny? How is my free will affected by the law
Scaling laws for the spatial distributions of the plasma parameters in the positive column of a dc oxygen discharge
Planck pre-launch status: Calibration of the Low Frequency Instrument flight model radiometers
The Social Effects and Institutional Structure of Immigration in New Zealand in the 1980s
Planck-LFI: Instrument Design and Ground Calibration Strategy
The ESA Planck satellite is designed to achieve precision imaging of the Cosmic Microwave Background with an unprecedented combination of angular resolution, sensitivity, spectral range and sky coverage. The Low Frequency Instrument is one of two complementary instruments, and covers 30, 44, and 70 GHz with an array of wideband pseudo-correlation, cryogenic radiometers. Advanced qualification models of the radiometer chains and of the instrument electronics have been manufactured, tested and integrated into the LFI Qualification Model. The main radiometer calibration, RF tuning and performance characterization is carried out at a single radiometer chain level, and then verified at instrument integrated level in dedicated cryofacilities. Here we describe the main requirements and instrument design, and we summarize the radiometer calibration strategy optimised during the qualification activity in view of the LFI Flight Model campaign