147 research outputs found
Absorption line series and autoionization resonance structure analysis in the ultraviolet spectrum of Sr I
Photoelectric spectrometer to measure absorption line series and autoionization resonance in ultraviolet spectrum of strontium vapo
High spatial resolution restoration of IRAS images
A general technique to improve the spatial resolution of the IRAS AO data was developed at The Aerospace Corporation using the Maximum Entropy algorithm of Skilling and Gull. The technique has been applied to a variety of fields and several individual AO MACROS. With this general technique, resolutions of 15 arcsec were achieved in 12 and 25 micron images and 30 arcsec in 60 and 100 micron images. Results on galactic plane fields show that both photometric and positional accuracy achieved in the general IRAS survey are also achieved in the reconstructed images
Evaluation of gellan gum fluid gels as modified release oral liquids
Oral liquids are often preferred for drug administration to patients for whom swallowing is difficult, however formulating modified release versions can be challenging. A potential route to achieve modified release in oral liquids is by using fluid (sheared) gels formed by introducing a shear field during gelation in gel-forming biopolymers. These fluid gels can act as pourable viscoelastic fluids but retain true gel micro/nano structure. Here, we have demonstrated that fluid gels have potential as paediatric oral liquids preventing release of ibuprofen in simulated gastric fluid. Subsequent release at pH 7.4 was affected by the duration of exposure and magnitude of acid pH with a linear relationship between onset of release and the preceding acidic exposure duration. Delayed release was a result of increasing gel stiffness, a consequence of the acidity of the initial release media and exposure time. A much faster release rate was measured when exposure time in acid was 10 min compared with 60 min. This study highlights the potential to design fluid gels that are tuned to have a specified stiffness at a particular pH and exposure time. This could enable the preparation oral liquids with modified release behaviour
[12CII] and [13CII] 158 mum emission from NGC 2024: Large column densities of ionized carbon
Context: We analyze the NGC 2024 HII region and molecular cloud interface
using [12CII] and [13CII] observations. Aims: We attempt to gain insight into
the physical structure of the interface layer between the molecular cloud and
the HII region. Methods. Observations of [12CII] and [13CII] emission at 158
{\mu}m with high spatial and spectral resolution allow us to study the detailed
structure of the ionization front and estimate the column densities and
temperatures of the ionized carbon layer in the PDR. Results: The [12CII]
emission closely follows the distribution of the 8 mum continuum. Across most
of the source, the spectral lines have two velocity peaks similar to lines of
rare CO isotopes. The [13CII] emission is detected near the edge-on ionization
front. It has only a single velocity component, which implies that the [12CII]
line shape is caused by self-absorption. An anomalous hyperfine line-intensity
ratio observed in [13CII] cannot yet be explained. Conclusions: Our analysis of
the two isotopes results in a total column density of N(H)~1.6\times10^23 cm^-2
in the gas emitting the [CII] line. A large fraction of this gas has to be at a
temperature of several hundred K. The self-absorption is caused by a cooler
(T<=100 K) foreground component containing a column density of N(H)~10^22
cm^-2
A new spectroscopic and interferometric study of the young stellar object V645 Cyg
We present the results of high-resolution optical spectroscopy,
low-resolution near-IR spectroscopy and near-infrared speckle interferometry of
the massive young stellar object candidate V645 Cyg, acquired to refine its
fundamental parameters and the properties of its circumstellar envelope.
Speckle interferometry in the - and -bands and an optical spectrum in the
range 5200--6680 \AA with a spectral resolving power of = 60 000 were
obtained at the 6-m telescope of the Russian Academy of Sciences. Another
optical spectrum in the range 4300--10500 \AA with = 79 000 was obtained at
the 3.6-m CFHT. Low-resolution spectra in the ranges 0.46--1.4 m and
1.4--2.5 m with 800 and 700, respectively, were obtained
at the 3-m Shane telescope of the Lick Observatory. Using a novel kinematical
method based on the non-linear modeling of the neutral hydrogen density profile
in the direction toward the object, we propose a distance of 0.2
kpc. We also suggest a revised estimate of the star's effective temperature,
T25 000 K. We resolved the object in both - and -bands.
We conclude that V645 Cyg is a young, massive, main-sequence star, which
recently emerged from its cocoon and has already experienced its protostellar
accretion stage. The presence of accretion is not necessary to account for the
high observed luminosity of (2--6) M yr. The
receding part of a strong, mostly uniform outflow with a terminal velocity of
800 km s is only blocked from view far from the star, where
forbidden lines form.Comment: 14 pages, 10 figure
Priprava i in vitro karakterizacija plutajuÄih zrnaca acetohidroksamske kiseline za iskorjenjivanje H. pylori
Gellan based floating beads of acetohydroxamic acid (AHA) were prepared by the ionotropic gellation method to achieve controlled and sustained drug release for treatment of Helicobacter pylori infection. The prepared beads were evaluated for diameter, surface morphology and encapsulation efficiency. Formulation parameters like concentrations of gellan, chitosan, calcium carbonate and the drug influenced the in vitro drug release characteristics of beads. Drug and polymer interaction studies were carried out using differential scanning calorimetry. Chitosan coating increased encapsulation efficiency of the beads and reduced the initial burst release of the drug from the beads. Kinetic treatment of the drug release data revealed a matrix diffusion mechanism. Prepared floating beads showed good antimicrobial activity (in vitro H. pylori culture) as potent urease inhibitors. In conclusion, an oral dosage form of floating gellan beads containing AHA may form a useful stomach site specific drug delivery system for the treatment of H. pylori infection.Metodom ionotropskog ĆŸeliranja pripravljena su plutajuÄa zrnca acetohidroksamske kiseline (AHA) na bazi gelana za kontrolirano i usporeno oslobaÄanje ljekovite tvari, namijenjena za lijeÄenje infekcija uzrokovanih Helicobacter pylori. Pripravljenim zrncima prouÄavani su dijametar, povrĆĄinska morfologija i sposobnost inkapsuliranja. Koncentracija gelana, kitozana, kalcijeva karbonata i ljekovite tvari utjecala je na oslobaÄanje in vitro. Interakcija izmeÄu ljekovite tvari i polimera praÄena je diferencijalnom pretraĆŸnom kalorimetrijom. Oblaganje zrnaca kitozanom poveÄalo je uÄinkovitost inkapsuliranja i smanjilo poÄetno naglo oslobaÄanje. OslobaÄanje ljekovite tvari slijedilo je mehanizam difuzije matriksa. PlutajuÄa zrnca s AHA pokazala su antimikrobno djelovanje in vitro na kulturi H. pylori kao snaĆŸni inhibitori ureaze. MoĆŸe se zakljuÄiti da su plutajuÄa zrnca s AHA na bazi gelana pogodna za specifiÄnu isporuku u ĆŸelucu te korisna u terapiji infekcija uzrokovanih H. pylori
Multi-line detection of O2 toward rho Oph A
Models of pure gas-phase chemistry in well-shielded regions of molecular
clouds predict relatively high levels of molecular oxygen, O2, and water, H2O.
Contrary to expectation, the space missions SWAS and Odin found only very small
amounts of water vapour and essentially no O2 in the dense star-forming
interstellar medium. Only toward rho Oph A did Odin detect a weak line of O2 at
119 GHz in a beam size of 10 arcmin. A larger telescope aperture such as that
of the Herschel Space Observatory is required to resolve the O2 emission and to
pinpoint its origin. We use the Heterodyne Instrument for the Far Infrared
aboard Herschel to obtain high resolution O2 spectra toward selected positions
in rho Oph A. These data are analysed using standard techniques for O2
excitation and compared to recent PDR-like chemical cloud models. The 487.2GHz
line was clearly detected toward all three observed positions in rho Oph A. In
addition, an oversampled map of the 773.8GHz transition revealed the detection
of the line in only half of the observed area. Based on their ratios, the
temperature of the O2 emitting gas appears to vary quite substantially, with
warm gas (> 50 K) adjacent to a much colder region, where temperatures are
below 30 K. The exploited models predict O2 column densities to be sensitive to
the prevailing dust temperatures, but rather insensitive to the temperatures of
the gas. In agreement with these model, the observationally determined O2
column densities seem not to depend strongly on the derived gas temperatures,
but fall into the range N(O2) = (3 to >6)e15/cm^2. Beam averaged O2 abundances
are about 5e-8 relative to H2. Combining the HIFI data with earlier Odin
observations yields a source size at 119 GHz of about 4 - 5 arcmin,
encompassing the entire rho Oph A core.Comment: 10 pages, 8 figures intended for publication in A&
- âŠ