412 research outputs found
Enantiomeric separation and quantitative determination of propranolol enantiomers in pharmaceutical preparations by chiral liquid chromatography
Neste trabalho é descrito um método validado empregando a cromatografia líquida de alta eficiência com fase estacionária quiral para a separação e determinação quantitativa dos enantiômeros do propranolol em formulações farmacêuticas. A separação foi obtida em meio orgânico polar empregando a coluna ±-Burke 2® como fase estacionária quiral (250 x 4,6 mm, 5 µm) e fase móvel constituída por diclorometano: metanol (90:10 v/v) juntamente com 12 mM de acetato de amônio e vazão de 0,9 mL/min. A detecção foi efetuada por absorção no ultravioleta a 280 nm. Em todos casos o tempo de corrida foi menor do que 10 min. O coeficiente de correlação obtido pelo método de regressão linear foi de 0,9995 para o R-prop e de 0,9998 para o S-prop. A precisão intra-dia, expressa como desvio padrão relativo, foi menor do que 2%. A exatidão, determinada pela recuperação média de R- e S-prop nas amostras foi de 97,3% e 100,1% para a amostra comercial e de 99,5% e 100,4% para a amostra simulada, respectivamente. Excelentes níveis para os limites de detecção (1,34 ng) e de quantificação (4,47 ng), além do tempo rápido de eluição dos enantiômeros do propranolol, confirmam a aplicabilidade do método no controle de qualidade de preparações farmacêuticas contendo este fármaco.This paper describes validated direct liquid chromatographic chiral methods for enantiomeric separation and quantitative determination of clinically significant ²-blocking agent, propranolol. A liquid chromatographic method was validated and applied for enantiomeric determination of propranolol enantiomers in pharmaceutical formulations. Separation were obtained in polar organic mode on a ±-Burke 2® chiral stationary phase (250 x 4.6 mm, 5µm) with mobile phase composed of dichloromethane:methanol (90:10 v/v), along with 12 mM of ammonium acetate, at a flow rate of 0.9 mL/min. Detection was made by ultraviolet absorption at 280 nm. In all cases the run time was less than 10 min. The correlation coefficient for linear regression curves of R-propranolol and S-propranolol were 0.9995 and 0.9998 respectively. The intra-day precision, expressed as RSD was less than 2%. The accuracy determined by average recovery of R-propranolol and S-propranolol from sample matrices were 97.3% and 100.1% in commercial sample and 99.5% and 100.4% in simulated samples, respectively. Excellent levels of limit of detection (mean value = 1.34 ng) and limit of quantitation (mean value = 4.47 ng), along with rapid elution time of both enantiomers, makes the method useful for routine enantiomeric quality control applications
Particle motion in the field of a five-dimensional charged black hole
In this paper, we have investigated the geodesics of neutral particles near a
five-dimensional charged black hole using a comparative approach. The effective
potential method is used to determine the location of the horizons and to study
radial and circular trajectories. This also helps us to analyze the stability
of radial and circular orbits. The radius of the innermost stable circular
orbits have also been determined. Contrary to the case of massive particles for
which, the circular orbits may have up to eight possible values of specific
radius, we find that the photons will only have two distinct values for the
specific radii of circular trajectories. Finally we have used the dynamical
systems analysis to determine the critical points and the nature of the
trajectories for the timelike and null geodesics.Comment: 15 pages, accepted for publication in Astrophysics and Space Scienc
Nucleonic resonance excitations with linearly polarized photon in
In this work, an improved quark model approach to the meson
photo-production with an effective Lagrangian is presented. The {\it t}-channel
{\it natural}-parity exchange is taken into account through the Pomeron
exchange, while the {\it unnatural}-parity exchange is described by the
exchange. With a very limited number of parameters, the available experimental
data in the low energy regime can be consistently accounted for. We find that
the beam polarization observables show sensitivities to some {\it s}-channel
individual resonances in the quark model symmetry limit.
Especially, the two resonances and , which belong
to the representation , have dominant contributions
over other excited states. Concerning the essential motivation of searching for
"missing resonances" in meson photo-production, this approach provides a
feasible framework, on which systematic investigations can be done.Comment: 16 pages, Revtex, 9 eps figures, to appear in PR
Pathway to the Square Kilometre Array - The German White Paper -
The Square Kilometre Array (SKA) is the most ambitious radio telescope ever
planned. With a collecting area of about a square kilometre, the SKA will be
far superior in sensitivity and observing speed to all current radio
facilities. The scientific capability promised by the SKA and its technological
challenges provide an ideal base for interdisciplinary research, technology
transfer, and collaboration between universities, research centres and
industry. The SKA in the radio regime and the European Extreme Large Telescope
(E-ELT) in the optical band are on the roadmap of the European Strategy Forum
for Research Infrastructures (ESFRI) and have been recognised as the essential
facilities for European research in astronomy.
This "White Paper" outlines the German science and R&D interests in the SKA
project and will provide the basis for future funding applications to secure
German involvement in the Square Kilometre Array.Comment: Editors: H. R. Kl\"ockner, M. Kramer, H. Falcke, D.J. Schwarz, A.
Eckart, G. Kauffmann, A. Zensus; 150 pages (low resolution- and colour-scale
images), published in July 2012, language English (including a foreword and
an executive summary in German), the original file is available via the MPIfR
homepag
Simultaneous determination of Choline citrate and acetylmethionine in injectable solutions by high performance liquid chromatography
Choline citrate (CC) and acetylmethionine (AM) are lipotropic drugs used in several pharmaceutical formulations. The objective of this research was to develop and validate a high performance liquid
chromatographic (HPLC) method for simultaneous determination of CC and AM in injectable solutions,
aiming its application in routine analysis for quality control of these pharmaceutical formulations. The
method was validated using a Shim-Pack® C18 (250 x 4.6 mm, 5 µm) column. The mobile phase was constituted of 25 mM potassium phosphate buffer solution, pH 5.7, adjusted with 10 % orthophosphoric acid,
acetonitrile and methanol (88:10:2, v/v/v). The flow rate was 1.1 mL.min-1
and the UV detection was made
at 210 nm. The analyses were made at room temperature (25 ± 1 ºC). The method is precise, selective, accurate and robust, and was successfully applied for simultaneous quantitative determination of CC and
AM in injectables.Colegio de Farmacéuticos de la Provincia de Buenos Aire
Magnetized Particle Capture Cross Section for Braneworld Black Hole
Capture cross section of magnetized particle (with nonzero magnetic moment)
by braneworld black hole in uniform magnetic field is considered. The magnetic
moment of particle was chosen as it was done by \citet{rs99} and for the
simplicity particle with zero electric charge is chosen. It is shown that the
spin of particle as well as the brane parameter are to sustain the stability of
particles circularly orbiting around the black hole in braneworld i.e. spin of
particles and brane parameter try to prevent the capture by black hole.Comment: 7 pages, 4 figures, Accepted for publication in Astrophysics & Space
Scienc
Expanding the clinical spectrum associated with defects in CNTNAP2 and NRXN1
RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.Abstract Background Heterozygous copy-number and missense variants in CNTNAP2 and NRXN1 have repeatedly been associated with a wide spectrum of neuropsychiatric disorders such as developmental language and autism spectrum disorders, epilepsy and schizophrenia. Recently, homozygous or compound heterozygous defects in either gene were reported as causative for severe intellectual disability. Methods 99 patients with severe intellectual disability and resemblance to Pitt-Hopkins syndrome and/or suspected recessive inheritance were screened for mutations in CNTNAP2 and NRXN1. Molecular karyotyping was performed in 45 patients. In 8 further patients with variable intellectual disability and heterozygous deletions in either CNTNAP2 or NRXN1, the remaining allele was sequenced. Results By molecular karyotyping and mutational screening of CNTNAP2 and NRXN1 in a group of severely intellectually disabled patients we identified a heterozygous deletion in NRXN1 in one patient and heterozygous splice-site, frameshift and stop mutations in CNTNAP2 in four patients, respectively. Neither in these patients nor in eight further patients with heterozygous deletions within NRXN1 or CNTNAP2 we could identify a defect on the second allele. One deletion in NRXN1 and one deletion in CNTNAP2 occurred de novo, in another family the deletion was also identified in the mother who had learning difficulties, and in all other tested families one parent was shown to be healthy carrier of the respective deletion or mutation. Conclusions We report on patients with heterozygous defects in CNTNAP2 or NRXN1 associated with severe intellectual disability, which has only been reported for recessive defects before. These results expand the spectrum of phenotypic severity in patients with heterozygous defects in either gene. The large variability between severely affected patients and mildly affected or asymptomatic carrier parents might suggest the presence of a second hit, not necessarily located in the same gene.Peer Reviewe
Quantitative determination of gemifloxacin mesylate in tablets by capillary zone electrophoresis and high performance liquid chromatography
The aim of this study was to develop and validate selective and sensitive methods for quantitative determination of an antibacterial agent, gemifloxacin, in tablets by high performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE). The HPLC method was carried out on a LiChrospher® 100 RP-8e, 5 μm (125 x 4 mm) column with a mobile phase composed of tetrahydrofuranwater (25:75, v/v) with 0.5 % of triethylamine and pH adjusted to 3.0 with orthophosphoric acid. The CZE method was performed using 50 mM sodium tetraborate buffer (pH 8.6). Samples were injected hydrodynamicaly (0.5 psi, 5 s) and the electrophoretic system was operated under normal polarity, at +20 kV and capillary temperature of 18 ºC. A fused-silica capillary 40.2 cm (30 cm effective length) x 75 μm i.d. was used. Both, HPLC and CZE could be interesting and efficient techniques to be applied for quality control in pharmaceutical industries.Colegio de Farmacéuticos de la Provincia de Buenos Aire
Relating Differently to Intrusive Images: The Impact of Mindfulness Based Cognitive Therapy (MBCT) on Intrusive Images in Patients With Severe Health Anxiety (Hypochondriasis).
Recurrent distressing intrusive images are a common experience in hypochondriasis. The aim of the current study was to assess the impact of Mindfulness-Based Cognitive Therapy (MBCT) for hypochondriasis on the occurrence and nature of distressing intrusive imagery in hypochondriasis. A semi-structured interview was used to assess intrusive imagery, and an adapted version of the Southampton Mindfulness Questionnaire (SMQ) was used to assess participants’ relationship with their intrusive images. A consecutive series of participants (N = 20) who were receiving MBCT for hypochondriasis as part of an ongoing research program were assessed prior to participating in an 8-week MBCT intervention, immediately following the intervention, and at three month follow-up. As compared to the baseline assessment, the frequency of intrusive images, the distress associated with them, and the intrusiveness of the images were all significantly reduced at the post-MBCT assessment. Participants’ adapted SMQ scores were significantly increased following the MBCT intervention, suggesting that participants’ relationship with their intrusive images had changed in that they had developed a more ‘mindful’ and compassionate response to the images when they did occur. Effect sizes from pre- to post-intervention were medium to large (Cohen’s d = 0.75 - 1.50). All treatment gains were maintained at 3 month follow-up. Results suggest that MBCT may be an effective intervention for addressing intrusive imagery in hypochondriasis
The Pioneer Anomaly
Radio-metric Doppler tracking data received from the Pioneer 10 and 11
spacecraft from heliocentric distances of 20-70 AU has consistently indicated
the presence of a small, anomalous, blue-shifted frequency drift uniformly
changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was
interpreted as a constant sunward deceleration of each particular spacecraft at
the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of
the Newton's gravitational inverse-square law has become known as the Pioneer
anomaly; the nature of this anomaly remains unexplained. In this review, we
summarize the current knowledge of the physical properties of the anomaly and
the conditions that led to its detection and characterization. We review
various mechanisms proposed to explain the anomaly and discuss the current
state of efforts to determine its nature. A comprehensive new investigation of
the anomalous behavior of the two Pioneers has begun recently. The new efforts
rely on the much-extended set of radio-metric Doppler data for both spacecraft
in conjunction with the newly available complete record of their telemetry
files and a large archive of original project documentation. As the new study
is yet to report its findings, this review provides the necessary background
for the new results to appear in the near future. In particular, we provide a
significant amount of information on the design, operations and behavior of the
two Pioneers during their entire missions, including descriptions of various
data formats and techniques used for their navigation and radio-science data
analysis. As most of this information was recovered relatively recently, it was
not used in the previous studies of the Pioneer anomaly, but it is critical for
the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living
Reviews in Relativit
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