127 research outputs found
Acidólisis enzimática de trioleina con los ácidos palmítico y caprílico: Optimización de los parámetros de la reacción mediante la metodología de superficie de respuesta
An acidolysis reaction of triolein with caprylic and palmitic acids was performed using immobilized sn-1,3 specific lipase from Mucor miehei to produce a reduced calorie spreadable structured lipid (SL). Response surface methodology was applied to model and optimize the reaction conditions using a four-factor five-level central composite rotatable design. The selected factors were time (10-24 h), enzyme load (10-25 wt%), substrate mole ratio (Triolein:Caprylic acid:Palmitic acid), (1:1:1-1:2.5:2.5) and temperature (45-60 °C). The produced SLs were compared to fat extracts of commercial margarine in terms of melting profile and solid fat content (SFC). SL with a melting peak of 42 °C and SFC of 40.69% at 0 °C was very similar to soft margarines. The caloric value of this SL was determined as 37.74 kJ/g, theoretically. The optimum reaction conditions were found as reaction time 14 h; substrate mole ratio 1:2.1:2.1; temperature 58 °C; and enzyme load 15 wt%. Under optimum conditions, the product contained 29.68% COC, 25.47% POC, and 3.80% POP.La reacción de acidolísis de la trioleina con los ácidos caprílico y palmítico se realizó utilizando lipasa inmovilizada Mucor miehei, específica de sn-1, 3, para producir una grasa de untar baja en calorías compuesta de lípidos estructurados (SL). La metodología de superficie de respuesta se aplica para modelar y optimizar las condiciones de reacción utilizando un factor-cuatro y nivel-cinco de diseño central compuesto. Los factores seleccionados fueron el tiempo (10-24 h), la carga de enzima (10-25% en peso), la relación molar de sustratos (Trioleína:Ácido Caprílico:Ácido Palmítico), (1:1:1-1:2.5:2.5) y la temperatura (45-60 °C). Los SLs producidos se compararon con extractos de grasa de margarina comercial en términos de perfil de fusión y contenido de grasa sólida (SFC). El SL con un pico de fusión a 42 °C y SFC de 40,69% a 0 °C era muy similar a las margarinas suaves. El valor calórico de este SL se determinó teóricamente siendo 37,74 kJ/g. Las condiciones óptimas de reacción encontradas fueron 14 h de tiempo de reacción; una relación molar de sustratos 1:2.1:2.1; una temperatura de 58 °C, y una carga enzima de 15% en peso. En condiciones óptimas el producto contenía 29,68% de AOC, 25,47% de POC, y 3,80% de POP
Post-outburst X-ray flux and timing evolution of Swift J1822.3-1606
Swift J1822.3-1606 was discovered on 2011 July 14 by the Swift Burst Alert
Telescope following the detection of several bursts. The source was found to
have a period of 8.4377 s and was identified as a magnetar. Here we present a
phase-connected timing analysis and the evolution of the flux and spectral
properties using RXTE, Swift, and Chandra observations. We measure a spin
frequency of 0.1185154343(8) s and a frequency derivative of
at MJD 55761.0, in a timing analysis that include
significant non-zero second and third frequency derivatives that we attribute
to timing noise. This corresponds to an estimated spin-down inferred dipole
magnetic field of G, consistent with previous estimates
though still possibly affected by unmodelled noise. We find that the
post-outburst 1--10 keV flux evolution can be characterized by a
double-exponential decay with decay timescales of and
days. We also fit the light curve with a crustal cooling model which suggests
that the cooling results from heat injection into the outer crust. We find that
the hardness-flux correlation observed in magnetar outbursts also characterizes
the outburst of Swift J1822.3-1606. We compare the properties of Swift
J1822.3-1606 with those of other magnetars and their outbursts.Comment: 12 pages, 8 figures, accepted for publication in Ap
The nature of the X-ray sources in dwarf galaxies in nearby clusters from the KIWICS
We present a deep search for and analysis of X-ray sources in a sample of
dwarf galaxies (M < -15.5 mag) located within twelve galaxy clusters from
the Kapteyn IAC WEAVE INT Cluster Survey (KIWICS) of photometric observations
in the and using the Wide Field Camera (WFC) at the
2.5-m Isaac Newton telescope (INT). We first investigated the optical data,
identified 2720 dwarf galaxies in all fields and determined their
characteristics; namely, their colors, effective radii, and stellar masses. We
then searched the data archive for X-ray counterparts of
optically detected dwarf galaxies. We found a total of 20 X-ray emitting dwarf
galaxies, with X-ray flux ranging from 1.7 to
4.1 erg cm s and X-ray luminosities varying from
2 to 5.4 erg s. Our results indicate that
the X-ray luminosity of the sources in our sample is larger than the Eddington
luminosity limit for a typical neutron star, even at the lowest observed
levels. This leads us to conclude that the sources emitting X-rays in our
sample are likely black holes. Additionally, we have employed a scaling
relation between black hole and stellar mass to estimate the masses of the
black holes in our sample, and have determined a range of black hole masses
from 4.6 to 1.5 M. Finally, we find a trend
between X-ray to optical flux ratio and X-ray flux. We discuss the implications
of our findings and highlight the importance of X-ray observations in studying
the properties of dwarf galaxies.Comment: Accepted for publication in MNRAS, 11 pages, 7 figure
Sedoanalgesia Administration with Propofol and Ketamine for Minor Urologic Interventions
Aim: In this study we aimed to administer sedoanalgesia with propofol and ketamine combination in patients undergoing planned minor urologic interventions with limited anesthesia. By combining these two medications, lower doses may be used, and we aimed to provide sufficient sedation, analgesia and amnesia without disrupting hemodynamic and respiratory stability and to increase patient and surgeon satisfaction. Material-Method: The study included 53 patients with planned minor urologic interventions aged from 19 to 85 years and physical situation ASA I-III. After six hours starvation, patients were taken to the surgery. Patients were monitored for electrocardiography (ECG), oxygen saturation (SPO2 ) and non-invasive blood pressure. For use if necessary a nasal O2 cannula was inserted. A vein in the back of the left hand was opened and 5 ml/min isotonic sodium chloride infusion was begun. Patient heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP) and oxygen saturation (SpO2 ) values were measured and a 5 point sedation scale (Table 1) was used to measure sedation scores. Basal values were recorded (0 min). Later patients were randomly divided into two groups with Group I administered intraurethral lidocaine gel for local anesthesia by the surgeon, while Group II were administered intravenous 0.015 mg/kg midazolam, 0.5 mg/kg 1% ketamine and 0.5 mg/kg 1% propofol by the authors for sedoanalgesia. At five minute intervals the HR, SAP, DAP, MAP, SpO2 values and sedation scores were measured and recorded. Results: Statistical evaluation found a statistically significant increase in SAP, DAP and MAP values measured at the 5th minute in Group I patients compared to preoperative values. In Group I patients, when the heart rate measured in the 1st and 5th minutes are compared with preoperative values there was a statistically significant increase identified. In Group II patients, there was a statistically significant fall in SpO2 values in the 1st and 5th minutes compared with preoperative values. When patient and surgeon satisfaction are compared with Group I, Group II was found to be statistically significantly higher. Though the blood pressure and heart rate increases in Group I patients were statistically significant, they were not at levels that required clinical intervention and/or treatment. Similarly the SpO2 decrease observed in Group II patients did not fall below 90% in any patient in spite of being statistically significant and rose again without clinical intervention and/or treatment. Conclusion: In this study we showed that sedoanalgesia administration with propofol and ketamine may be an alternative method for patients undergoing minor urology interventions that does not disrupt hemodynamic and respiratory stability, does not delay patient discharge, has low side effect incidence and has high patient and surgeon satisfaction
Early X-ray and optical observations of the soft gamma-ray repeater SGR 0418+5729
Emission of two short hard X-ray bursts on 2009 June 5 disclosed the
existence of a new soft gamma-ray repeater, now catalogued as SGR 0418+5729.
After a few days, X-ray pulsations at a period of 9.1 s were discovered in its
persistent emission. SGR 0418+5729 was monitored almost since its discovery
with the Rossi X-ray Timing Explorer (2-10 keV energy range) and observed many
times with Swift (0.2-10 keV). The source persistent X-ray emission faded by a
factor 10 in about 160 days, with a steepening in the decay about 19 days after
the activation. The X-ray spectrum is well described by a simple absorbed
blackbody, with a temperature decreasing in time. A phase-coherent timing
solution over the 160 day time span yielded no evidence for any significant
evolution of the spin period, implying a 3-sigma upper limit of 1.1E-13 s/s on
the period derivative and of 3E+13 G on the surface dipole magnetic field.
Phase-resolved spectroscopy provided evidence for a significant variation of
the spectrum as a function of the stellar rotation, pointing to the presence of
two emitting caps, one of which became hotter during the outburst. Finally, a
deep observation of the field of SGR 0418+5729 with the new Gran Telescopio
Canarias 10.4-m telescope allowed us to set an upper limit on the source
optical flux of i'>25.1 mag, corresponding to an X-ray-to-optical flux ratio
exceeding 10000, consistent with the characteristics of other magnetars.Comment: The paper (10 pages) contains 6 colour figures and 2 tables; accepted
for publication in MNRA
Status of the ROTSE-III telescope network
ROTSE-III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of γ-ray burst (GRB) afterglows as close as possible to the start of γ-ray emission. ROTSE-III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events
Prompt Optical Detection of GRB 050401 with ROTSE-IIIa
The ROTSE-IIIa telescope at Siding Spring Observatory, Australia, detected
prompt optical emission from Swift GRB 050401. In this letter, we present
observations of the early optical afterglow, first detected by the ROTSE-IIIa
telescope 33 s after the start of gamma-ray emission, contemporaneous with the
brightest peak of this emission. This GRB was neither exceptionally long nor
bright. This is the first prompt optical detection of a GRB of typical duration
and luminosity. We find that the early afterglow decay does not deviate
significantly from the power-law decay observable at later times, and is
uncorrelated with the prompt gamma-ray emission. We compare this detection with
the other two GRBs with prompt observations, GRB 990123 and GRB 041219a. All
three bursts exhibit quite different behavior at early times.Comment: 4 pages, 3 figures. Accepted for publication in ApJ Letter
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