360 research outputs found

    National Scientific Facilities and Their Science Impact on Non-Biomedical Research

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    H-index, proposed by Hirsch is a good indicator of the impact of a scientist's research. When evaluating departments, institutions or labs, the importance of h-index can be further enhanced when properly calibrated for size. Particularly acute is the issue of federally funded facilities whose number of actively publishing scientists frequently dwarfs that of academic departments. Recently Molinari and Molinari developed a methodology that shows the h-index has a universal growth rate for large numbers of papers, allowing for meaningful comparisons between institutions. An additional challenge when comparing large institutions is that fields have distinct internal cultures, with different typical rates of publication and citation; biology is more highly cited than physics, which is more highly cited than engineering. For this reason, this study has focused on the physical sciences, engineering, and technology, and has excluded bio-medical research. Comparisons between individual disciplines are reported here to provide contextual framework. Generally, it was found that the universal growth rate of Molinari and Molinari holds well across all the categories considered, testifying to the robustness of both their growth law and our results. The overall goal here is to set the highest standard of comparison for federal investment in science; comparisons are made with the nations preeminent private and public institutions. We find that many among the national facilities compare favorably in research impact with the nations leading universities.Comment: 22 pages, 7 figure

    Extraction of wood compounds by use of subcritical fluids

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    A study of the extraction of oak wood compounds with subcritical water-ethanol mixtures as extractant, with an ethanol content between 0-60%, is reported. Identification and characterisation of the extracted compounds have been made by spectrophotometry and gas chromatography with either flame ionisation or mass detectors. Extraction was performed statically manner by use of a single cycle or repeated cycles. All variables affecting the extraction process were studied and optimised. Extraction time and temperature are 60 min and 200ºC, respectively. Comparison of the extract thus obtained with commercial extracts showed the former to be rich in compounds characteristic of the commercial extracts. The method enables manipulation of the extract composition by changing the temperature and water/ethanol ratio used. It is faster than the traditional procedures for obtaining wood extracts

    Use of superheated liquids for the extraction of non-volatile compounds from wood: HPLC studies

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    A study of the extraction of oak wood compounds using superheated water-ethanol mixtures ranging from 10 to 60% ethanol is reported. Identification and characterization of the extracted compounds have been made by high performance liquid chromatography. The extraction has been performed using the static mode by single or repetitive cycles. The variables affecting the extraction process have been studied and their optimum values established (extraction time: 50 min; pressure: 40 atm; extraction temperature: 180º C). The study allows to compare the non-volatile polyphenol fractions obtained in this way with those present in commercial samples with fully agreement between them. In addition, the method allows manipulation of the extract composition by changing the working pressure, temperature and water-ethanol ratio

    Universality of citation distributions revisited

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    Radicchi, Fortunato, and Castellano [arXiv:0806.0974, PNAS 105(45), 17268] claim that, apart from a scaling factor, all fields of science are characterized by the same citation distribution. We present a large-scale validation study of this universality-of-citation-distributions claim. Our analysis shows that claiming citation distributions to be universal for all fields of science is not warranted. Although many fields indeed seem to have fairly similar citation distributions, there are quite some exceptions as well. We also briefly discuss the consequences of our findings for the measurement of scientific impact using citation-based bibliometric indicators

    The Journal of Computer-Aided Molecular Design: a bibliometric note

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    Summarizes the articles in, and the citations to, volumes 2-24 of the Journal of Computer-Aided Molecular Design. The citations to the journal come from almost 2000 different sources that span a very wide range of academic subjects, with the most heavily cited articles being descriptions of software systems and of computational methods

    Superheated liquids for the extraction of solid residues from winemaking processes

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    Solid residues from winemaking process have been subjected to extraction with superheated water-ethanol mixtures. Identification and characterisation of the extracted compounds have been made by spectrophotometry, gas chromatography with either flame ionisation or mass detectors and high performance liquid chromatography with UV detection. The extraction has been performed in a static manner by single or repetitive cycles. All variables affecting the extraction process have been studied and optimised. The extraction time and temperature are 65 min and 210ºC, respectively. Two phases constitute the extract: an aqueous phase, which is rich in phenol compounds and an oily phase, mainly formed by fatty acids. The method allows manipulation of the extract composition by changing the applied pressure, temperature, water-ethanol ratio and pH. The method is faster than the traditional extraction procedures for obtaining valuable compounds from these residues

    The skewness of science in 219 sub-fields and a number of aggregates

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    This paper studies evidence from Thomson Scientific about the citation process of 3.7 million articles published in the period 1998-2002 in 219 Web of Science categories, or sub-fields. Reference and citation distributions have very different characteristics across sub-fields. However, when analyzed with the Characteristic Scores and Scales technique, which is replication and scale invariant, the shape of these distributions over three broad categories of articles appears strikingly similar. Reference distributions are mildly skewed, but citation distributions with a five-year citation window are highly skewed: the mean is twenty points above the median, while 9-10% of all articles in the upper tail account for about 44% of all citations. The aggregation of sub-fields into disciplines and fields according to several aggregation schemes preserve this feature of citation distributions. It should be noted that when we look into subsets of articles within the lower and upper tails of citation distributions the universality partially breaks down. On the other hand, for 140 of the 219 sub-fields the existence of a power law cannot be rejected. However, contrary to what is generally believed, at the sub-field level the scaling parameter is above 3.5 most of the time, and power laws are relatively small: on average, they represent 2% of all articles and account for 13.5% of all citations. The results of the aggregation into disciplines and fields reveal that power law algebra is a subtle phenomenon.

    The skewness of science in 219 sub-fields and a number of aggregates

    Get PDF
    This paper studies evidence from Thomson Scientific about the citation process of 3.7 million articles published in the period 1998-2002 in 219 Web of Science categories, or sub-fields. Reference and citation distributions have very different characteristics across sub-fields. However, when analyzed with the Characteristic Scores and Scales technique, which is size and scale independent, the shape of these distributions appear extraordinarily similar. Reference distributions are mildly skewed, but citation distributions with a five-year citation window are highly skewed: the mean is twenty points above the median, while 9-10% of all articles in the upper tail account for about 44% of all citations. The aggregation of sub-fields into disciplines and fields according to several aggregation schemes preserve this feature of citation distributions. On the other hand, for 140 of the 219 sub-fields the existence of a power law cannot be rejected. However, contrary to what is generally believed, at the sub-field level the scaling parameter is above 3.5 most of the time, and power laws are relatively small: on average, they represent 2% of all articles and account for 13.5% of all citations. The results of the aggregation into disciplines and fields reveal that power law algebra is a subtle phenomenon.

    Sequential Spectrophotometric determination of methanol and iron in vinegar by a flow injection-pervaporation method

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    An easily automatable sequential flow-injection-pervaporation method is proposed for the photometric determination of methanol and iron in vinegar. The method is based on separation of the methanol from the sample matrix by pervaporation followed by its oxidation to formaldehyde with permanganate, decolouration of the latter with S2O5-2 and subsequent reaction of formaldehyde with p-rosaniline to yield a violet reaction product with maximum absorption at 567 nm. Iron is determined by an existing method based on reaction with thiocyanate in acidic medium and monitoring at 508 nm. After optimisation by either the univariate or multivariate approaches, as required, the linear range was established for methanol (4-1000 mg L-1) and iron (0.18-20 mg L-1); The proposed method was then compared with reference methods for methanol and iron in terms of repeatability (2.452 mg L-1 and 0.245 mg L-1, respectively), reproducibility (4.435 mg L-1 and 0.356 mg L-1, respectively), detection limit (LOD=82 and 0.234 mg L-1, respectively) and traceability. The throughput was nine samples per hour
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