1,002 research outputs found
Evaluating the Wald Entropy from two-derivative terms in quadratic actions
We evaluate the Wald Noether charge entropy for a black hole in generalized
theories of gravity. Expanding the Lagrangian to second order in gravitational
perturbations, we show that contributions to the entropy density originate only
from the coefficients of two-derivative terms. The same considerations are
extended to include matter fields and to show that arbitrary powers of matter
fields and their symmetrized covariant derivatives cannot contribute to the
entropy density. We also explain how to use the linearized gravitational field
equation rather than quadratic actions to obtain the same results. Several
explicit examples are presented that allow us to clarify subtle points in the
derivation and application of our method
Triethylphosphite as a network forming agent enhances in-vitro biocompatibility and corrosion protection of hybrid organic-inorganic sol-gel coatings for Ti6Al4V alloys
The biocompatibility and life of metallic implants can be enhanced through improving the biocompatibility and corrosion protection characteristics of the coatings used with these materials. In this study, triethylphosphite (TEP) was used to introduce phosphorus into organic-inorganic hybrid silica based sol gel coatings prepared using γ-methacryloxypropyltrimethoxysilane and tetramethylorthosilicate. Addition of TEP dramatically increased the rate of intermolecular condensation and resulted in materials showing greater cross linking. Protein (fibrinogen) uptake, osteoblast in vitro biocompatibility and corrosion resistance was enhanced in coatings containing TEP. Although higher concentrations of phosphorus supported the greatest improvement in biocompatibility, a compromise in the phosphorus concentration used would be required if corrosion resistance was most desirable parameter for optimisation. Films prepared by dip coating on Ti6Al4V alloys from these sols offer a promising alternative to wholly metallic prostheses
A record of communal nesting in the barn owl (Tyto alba)
We report a unique case of two female Barn Owls laying eggs and incubating together in a single nest cup in a communal nest. A trio of two females and one male bred in an abandoned water tower in 2013 in Israel. Both females incubated/brooded together in the communal nest, and all three individuals brought food to the communal family. The two females laid 20 eggs, of which 19 hatched and 16 fledged
Hypertrophic pyloric stenosis, an unusual presentation and rare association: case report and literature review
Hypertrophic pyloric stenosis (HPS) is a commonly encountered surgical condition that occurs in infancy, but not in neonates. This report describes a 10-day-old male patient with atypical presentation of HPS, with an incidental diagnosis of eventration of the left diaphragm. The symptoms were present since birth with nonprojectile, nonbilious vomiting and gastric distension. A contrast study showed a gastric outlet obstruction with the possibility of gastric volvulus. Emergency surgery established the diagnosis. To the best of our knowledge, the association of HPS with diaphragmatic defect and gastric volvulus is rare, and few cases have been reported in the literature
Nachtlärminduzierte Schlafstörungen und Herz-Kreislauf-Risiko
Impairment of sleep in the sense of insomnias, i.e. difficulties falling asleep and staying asleep, early morning awakening and chronical unrestful sleep is widespread in the population and are associated with a variety of physical and mental health disorders. The environmental causes of insomnia include a number of factors, with nighttime noise being an important cause. Recent data from the European Environment Agency shows that environmental noise (road traffic, railway, aircraft and industrial noise) causes severe sleep disorders among 6.5 million people in Europe. New epidemiological and mechanistic field studies show that in particular night traffic noise can lead, among other things, to impaired vascular function, thrombo-inflammatory changes, an increase in stress hormones and increased blood pressure, representing significant risk factors for cardiovascular diseases. According to the European Environment Agency, environmental noise causes 48000 additional cases of ischemic heart disease and 12000 premature deaths each year
Optimirana i validirana protočna injekcijska spektrofotometrijska analiza topiramata, piracetama i levetiracetama u farmaceutskim pripravcima
Application of a sensitive and rapid flow injection analysis (FIA) method for determination of topiramate, piracetam, and levetiracetam in pharmaceutical formulations has been investigated. The method is based on the reaction with ortho-phtalaldehyde and 2-mercaptoethanol in a basic buffer and measurement of absorbance at 295 nm under flow conditions. Variables affecting the determination such as sample injection volume, pH, ionic strength, reagent concentrations, flow rate of reagent and other FIA parameters were optimized to produce the most sensitive and reproducible results using a quarter-fraction factorial design, for five factors at two levels. Also, the method has been optimized and fully validated in terms of linearity and range, limit of detection and quantitation, precision, selectivity and accuracy. The method was successfully applied to the analysis of pharmaceutical preparations.Opisana je osjetljiva i brza protočna injekcijska analiza (FIA) za određivanje topiramata, piracetama i levetiracetama u farmaceutskim pripravcima. Metoda se temelji na reakciji ortho-ftalaldehida i 2-merkaptoetanola u bazičnom puferu i mjerenju apsorbancije na 295 nm u protočnim uvjetima. U svrhu povećanja osjetljivosti i dobivanja reproducibilnih rezultata optimirane su varijable koje utječu na određivanje kao što su volumen injektiranog uzorka, pH, ionska jakost, koncentracija reagensa, brzina protoka reagensa i drugi FIA parametri koristeći četvrt-frakcijski faktorijalni dizajn, za pet faktora na dva nivoa. Metoda je optimirana i potpuno validirana (linearnost, područje određivanja, granica detekcije i kvantifikacije, preciznost, selektivnost i točnost). Metoda je uspješno primijenjena za analizu farmaceutskih pripravaka
STABILITY-INDICATING LIQUID CHROMATOGRAPHY METHOD FOR THE DETERMINATION OF PENTOXYVERINE CITRATE AND ITS DEGRADANT
Objectives: The objectives of this research were to develop and validate a HPLC method for determination of Pentoxyverine citrate (PNX) and its degradant (DG).
Methods: Forced degradation studies were performed on bulk sample using alkaline (0.1M sodium hydroxide) and acid (1M hydrochloric acid. The proposed method was based on using a 150 x 4.6 mm (i. d.) (Luna, Phenomenex, Torrance, CA, USA) (5 µm particle size) reversed phase C18 column with mobile phase consisting of a mixture of methanol-10 mM sodium dihydrogen phosphate pH 4 in ratio of (60:40, v/v) and UV detection at 230 nm with flow rate of 1 mL min-1.
Results: The linear calibration range was between 10-40 mg ml-1and 10-40 mg ml-1for PNX and DG respectively. The method was found to be accurate with 100.23% and 100.07% recovery for PNX and DG respectively. The limit of detection (LOD) was found to be 3.79 x10-2μg ml-1 and 4.24 x10-2μg ml-1 for PNX and DG respectively, while the limit of quantification (LOQ) was found to be 12.62 x10-2μg ml-1 and 14.12 x10-2μg ml-1 for PNX and DG respectively. PNX was found to be most stable at a pH of 5.7.
Conclusion: The validation study of the proposed method was successfully carried out and the method was found to be suitable and economic for routine determination of PNX in pharmaceutical syrup, without any interference from the excipients, and in the presence of its acidic and alkaline degradation products
Efectos del fósforo de un efluente cloacal sobre la morfología interna y externa de Eichhornia crassipes (Mart. Solms) en un humedal artificial
Se compararon las variaciones morfológicas que presentó Eichhornia crassipes (Mart. Solms) a la entrada y salida de un humedal construido para tratar un efluente cloacal. Se determinó la concentración de fósforo en el agua y en las plantas. Se midió la altura de las plantas, la longitud de las raíces y la biomasa. Para estudiar la morfología interna de la raíz se calculó el área transversal de la raíz (ATR), de la médula (ATM) y de los vasos metaxilemáticos tardíos (ATV) y el área total del metaxilema (ATVt) por sección. Las diferentes concentraciones de fósforo presentes en el efluente cloacal, a la entrada y salida del humedal, produjeron variaciones en la morfología externa e interna de E. crassipes. La concentración de fósforo en los tejidos mostró una relación directa con la concentración de fósforo en el agua. En las plantas de la entrada se observó una mayor altura, menor longitud y biomasa de las raíces en comparación con las plantas de la salida. En las plantas de la entrada se observó un aumento de los valores de ATM y ATV y ATVt, comparadas con las plantas de la salida. La variación en los parámetros morfológicos internos se debió probablemente al aumento del área transversal de la raíz.The present study compares the morphological variation of Eichhornia crassipes (Mart. Solms) between the inlet and outlet zones of a wetland constructed for the treatment of a sewage effluent. The phosphorus concentration in water and plants was determined. Plant height, root length and dry biomass were measured. The areas of cross-sectional whole root (ATR), stele (ATM), large metaxylematic vessels (ATV) and the total metaxylematic vessels (ATVt) were calculated. The different phosphorus concentrations registered at the inlet and outlet zones of the constructed wetland, induced internal and external morphological changes in E. crassipes. Phosphorus concentration in tissues was positively correlated with phosphorus concentrations in water. The inlet zone plants were taller and they had shorter roots and less proportion of root dry weight in comparison with the outlet zone plants. The inlet zone plants increased the ATM, ATV and ATVt values, in comparison with the outlet zone plants. The variation in the internal morphological parameters was probably due to the increase of the cross-sectional whole root
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