Search results for "LIMIT"
showing 10 items of 2826 documents
Uncertainty-Based Internal Quality Control. Harmonization Considerations
2006
Three main quality aspects for analytical laboratories are internal method validation, internal quality control (IQC), and sample result uncertainty. Unfortunately, in the past they have been used in a nonharmonized way. The most universal IQC tool is the mean chart, but some criteria used to fix their control limits do not fit the real nature of analytical results. A new approach for fixing these limits is proposed (the u-approach). The key is the combined uncertainty, u, obtained from the method validation information, also used for estimating the sample result uncertainty. A comparative study on "in-control" simulated, bibliographic, and real laboratory data suggests that the u-approach …
Perturbations of symmetric elliptic Hamiltonians of degree four
2006
AbstractIn this paper four-parameter unfoldings Xλ of symmetric elliptic Hamiltonians of degree four are studied. We prove that in a compact region of the period annulus of X0 the displacement function of Xλ is sign equivalent to its principal part, which is given by a family induced by a Chebychev system; and we describe the bifurcation diagram of Xλ in a full neighborhood of the origin in the parameter space, where at most two limit cycles can exist for the corresponding systems.
Virtual Orbital Many-Body Expansions: A Possible Route towards the Full Configuration Interaction Limit
2017
In the present letter, it is demonstrated how full configuration interaction (FCI) results in extended basis sets may be obtained to within sub-kJ/mol accuracy by decomposing the energy in terms of many-body expansions in the virtual orbitals of the molecular system at hand. This extension of the FCI application range lends itself to two unique features of the current approach, namely that the total energy calculation can be performed entirely within considerably reduced orbital subspaces and may be so by means of embarrassingly parallel programming. Facilitated by a rigorous and methodical screening protocol and further aided by expansion points different from the Hartree-Fock solution, al…
Kinetische untersuchungen zur strahleninduzierten festkörperpolymerisation von trioxan und tetroxan IV. Mitt. der Reihe “kinetische und morphologisch…
1971
Die strahlungsinduzierte Polymerisation von kristallinem Tetroxan und Trioxan wurde untersucht und der Einflus von Strahlendosis, Reaktionszeit und -temperatur auf den Umsatz und das Molekulargewicht der entstehenden POM, insbesondere bei der Nachpolymerisation, studiert. Die Zeit-Umsatz-Kurven fur die Nachpolymerisation laufen bei beiden Monomeren asymptotisch gegen einem Grenzwert des Umsatzes, der mit steigender Reaktionstemperatur ansteigt. Die Aktivierungsenergie der Nachpolymerisation wurde zu 24 ± 2 kcal/Mol fur Tetroxan und zu 36–38 kcal/Mol fur Trioxan bestimmt. Die Zeit(t)-Umsatz(x)-Kurven fur Tetroxan lassen sich durch die empirische Gleichung: beschreiben, wobei k1 und k2 Konsta…
FI-chemiluminometric study of thiazides by on-line photochemical reaction
2004
The present manuscript deals with a simple and sensitive flow-injection method for the chemiluminescent determination of thiazides. The method is based on the on-line photodegradation and chemiluminescent determination of the resulting photo-fragments. The on-line photodegradation is performed in basic medium by using a photoreactor consisting of a 550 cm long x 0.8 mm ID piece of PTFE tubing helically coiled around an 8 W low-pressure mercury lamp. The determination of the photo-irradiated thiazides is performed by a chemiluminescent oxidative reaction with Ce(IV) in sulphuric acid medium. A heterogeneous group of thiazides (indapamide, metolazone, hydroflumethiazide, chlorthalidone and be…
Mechanistic and kinetic insight into spontaneous cocrystallisation of isoniazid and benzoic acid
2015
Solid-state cocrystallisation is of contemporary interest, because it offers an easy and efficient way to produce cocrystals, which are recognized as prospective pharmaceutical materials. Research explaining solid-state cocrystallisation mechanisms is important, but still too scarce to give a broad understanding of factors governing and limiting these reactions. Here we report an investigation of the mechanism and kinetics of isoniazid cocrystallisation with benzoic acid. This reaction is spontaneous; however its rate is greatly influenced by environmental conditions (humidity and temperature) and pre-treatment (milling) of the sample. The acceleration of cocrystallisation in the presence o…
Activity mediated phase separation: Can we understand phase behavior of the nonequilibrium problem from an equilibrium approach?
2016
We present results for structure and dynamics of mixtures of active and passive particles, from molecular dynamics (MD) simulations and integral equation theory (IET) calculations, for a physically motivated model. The perfectly passive limit of the model corresponds to the phase-separating Asakura-Oosawa model for colloid-polymer mixtures in which, for the present study, the colloids are made self-propelling by introducing activity in accordance with the well known Vicsek model. Such activity facilitates phase separation further, as confirmed by our MD simulations and IET calculations. Depending upon the composition of active and passive particles, the diffusive motion of the active specie…
Spatially limited diffusion coupled with ohmic potential drop and/or slow interfacial exchange: a new method to determine the diffusion time constant…
2004
Abstract We have analyzed chronoamperometric curves, I ( t ), after small-amplitude potential steps Δ E (PITT technique) for the model of linear diffusion of a species inside an electroactive film, taking into account ohmic effects in the external media (solution and electrode) as well as a finite rate of the interfacial exchange. For its short-time interval, t ≪ τ d ( τ d is the diffusion time constant, corresponding to unlimited diffusion from the interface), three approximate analytical expressions have been proposed. One of these represents an interpolation formula between the value of the current at the start of the diffusion process, I (0)=Δ E / R ext (after the end of the EDL chargin…
Vorschlag zur Unterscheidung der 2 Größen: „Grenzviskositätszahl” u. „konventionelle Viskositätszahl”
1954
Fur viskosimetrische Molekulargewichtsbestimmungen ist es nicht notig, die Viskositatszahl auf den Geschwindigkeitsgradienten 0 zu extrapolieren. Es wird empfohlen, die Viskositatszahl derart zu normieren, das zur Messung bestimmte Kapillarenradien verwendet werden. Dadurch wird jedem Losungsmittel ein bestimmter Gradient (i. A. zwischen 0,5 und 1,5.103 sec−1 zugeordnet, und damit ist auch fur jedes in diesem Losungsmittel gemessene Polymere die „konventionelle Viskositatszahl” eindeutig und reproduzierbar festgelegt. Eichkurven zur viskosimetrischen Molekulargewichtsbestimmung sollten auf die konventionelle Viskositatszahl bezogen werden. Diese weicht nur bei hohen Polymeren von der Grenzv…
Rate-limiting reaction of C 3 S hydration - A reply to the discussion “A new view on the kinetics of tricalcium silicate hydration” by E. Gartner
2018
Abstract In the case of coupled solids-solution reactions, any mean accelerating or decelerating one of the reaction, will also change the other reaction(s) in the same way, through the coupling mediated by the solution. The observation of any kinetic change by one of these means should not lead to too rapid conclusion on the limitation of kinetics and it must be done with great caution. Contrary to what Gartner mentioned, the acceleration of C3S hydration by the addition of calcium silicate hydrate seeds, is not a trivial evidence suggesting that hydration kinetics “has to be” limited by the C-S-H precipitation and that the C3S dissolution can be neglected. In our paper, efforts have been …