Peter Vinkler

Rose hip (Rosa canina L.) oil obtained from waste hip seeds by different extraction methods

From the rose hip seed, which is generally a waste material, valuable oil can be obtained for medicinal use. Various extraction methods have been compared: traditional solvent extraction with ultrasound-, microwave-, sub- and supercritical fluid extraction (SFE). Unsaturated fatty acid (UFA: oleic-, linoleic- and linolenic acid; 16.25-22.11%, 35.94-54.75%, 20.29-26.48%) and polyunsaturated fatty acid (PUFA:linoleic- and linolenic acid) content were over 90% and 60% in the recovered oils. The oils contained different amounts of metals. The concentration of some metals, particularly iron in microwave oil (27.11 microg g(-1)) is undesirable from the aspect of stability. By traditional solvent extraction, oil was obtained in 4.85 wt/wt%. Subcritical FE appeared to be the best method for the recovery of rose hip oil with highest oil yield (6.68 wt/wt%), carotene- (145.3 microg g(-1)) and linoleic acid content (54.75%). Supercritical FE without organic solvent is suitable for mild recovery of oil. The oil was rich in UFA and PUFA (92.7% and 76.25%) and contained the lowest amount of carotene and pheophytin (36.3 and 45.8 microg g(-1)). Oil yield in most new extraction methods (microwave extraction, super- and subcritical FE) was higher than in the case of traditional Soxhlet extraction. The main benefit of supercritical FE with CO2 is the solvent free oil while in the case of other extractions evaporation of the solvent is needed. Although the content of bioactive compounds in oils was different, all oils may be appropriate for medicinal use.

Evaluation of some methods for the relative assessment of scientific publications

Some bibliometric methods for the assessment of the publication activity of research units are discussed on the basis of impact factors and citations of papers. “Average subfield impact factor” of periodicals representing subfields in chemistry is suggested. This indicator characterizes the average citedness of a paper in a given subfield. Comparing the total sum of impact factors of corresponding periodicals divided by the number of papers published by a research team to the average subfield impact factor a “publication strategy” indicator can be derived. A new bibliometric indicator, “relative subfield impact”, is introduced which compares the number of citations received by papers of a research unit to the average subfield impact factor.

The evaluation of research by scientometric indicators

Introduction Basic categories of scientometrics Classification of the indicators of evaluative scientometrics Publication growth in science Scientific eminence of journals: the Garfield Factor and the Current Contribution Index The ageing of scientific information Scientometric indicators for the assessment of publications Reference strategy: model of manifested communication through publications Frequency of and strength of motives in referencing: the Reference Threshold Model Research contribution and share of credit of individual authors Standards in scientometric assessments Scientometric assessments: application of scientometrics for the purposes of science policy Institutionalisation of Scientific Information: a scientometric model (ISI-S model) Conclusions.

Eminence of scientists in the light of the h-index and other scientometric indicators

Scientometrics cannot offer a simple consistent method for measuring the scientific eminence of individuals. The h-index method introduced by Hirsch was found applicable for evaluating publications of senior scientists with similar publishing features, only. Some simple methods — using the number of citations and journal papers, and the number of citations obtained by the most frequently cited papers — are suggested and tested to demonstrate the advantages and disadvantages of such indexes. The results indicate that calculating scientometric indexes for individuals, self-citations should be excluded and the effect of the different bibliometric features of the field should be taken into account. The correctness of the indexes used for evaluating journal papers of individuals should be investigated also on the individual level.

A quasi-quantitative citation model

On the basis of investigating authors opinion on citing motivations of chemistry papers aquasi-quantitative model for citing is suggested. The model selects professional and nonprofessional motivations of citing and introduces thecitation threshold concept which tries to characterize the effect of citing motivations quantitatively. Possible reasons for missing citations are also treated. Mean ages of real and of self-citations were calculated by subtracting the average of the publication years of cited papers from the publication year of the citing publication. The difference between the mean ages may characterize thesynchronity of the authors research in comparison with those working on similar topics. The paper introduces thecitation strategy indicator which relates impact factors of cited periodicals with the mean impact factor of periodicals in the corresponding research subfield.

Correlation between the structure of scientific research, scientometric indicators and GDP in EU and non-EU countries

Significant discrepancies were found in the ratio and relative impact of the journal papers of several scientific fields of some Central and Eastern European (CEE) countries compared to the European Community member states, the US and Japan (EUJ countries). A new indicator, characterizing the Mean Structural Difference of scientific fields between countries has been introduced and calculated for CEE countries. For EUJ countries correlation between the GDP and number of publications of a given year proved to be non-significant. Longitudinal studies showed, however, significant correlations between the yearly values of GDP and number of papers published. Studying data referring to consecutive time periods revealed that there is no direct relationship between the GDP and information production of countries. It may be assumed that grants for R&D do not actually depend on real needs, but the fact is that rich countries can afford to spend more whilst poor countries only less money on scientific research.

The ź-index

There are several simple and sophisticated scientometric indicators generally applied in the literature (e.g. total number of publications and citations, citations per journal paper, relative citedness indexes, Hirsch index, etc.), which may characterize the publications of scientists both qualitatively and quantitatively. The calculation methods generally use data referring to the total set of papers studied. Scientific progress, however, may be attributed primarily to information in the highly cited publications. Therefore, a new indicator (π-index) is suggested for comparative assessment of scientists active in similar subject fields. The π-index is equal to one hundredth of the number of citations obtained to the top square root of the total number of journal papers (‘elite set of papers’) ranked by the decreasing number of citations. The relation of the π-index to other indexes and its dependence on the field is studied, using data of journal papers of ‘highly cited researchers’.

Relations of relative scientometric impact indicators. The relative publication strategy index

Relations of three relative scientometric indicators (Relative Citation Rate, RCR, Relative Subfield Citedness, RW, and Relative Publication Strategy, RPS) are studied. RW can be calculated by the percentage share of citations divided by that of publications. The findings indicate that publishing in journals with relatively high impact factor is a necessary but not sufficient condition for attaining a high RW index.

Subfield problems in applying the Garfield (impact) factors in practice

The assessment of the publications of research teams working on different subfields raises concerns because of the different scientometric features of the subfields. For equalizing the differences in the Garfield (Impact) Factors of journals, several methods applied in practice have been described. A new indicator – Specific Impact Contribution (SIC) relating the citation share of a respective team (or journal) in the total citations of the teams (or journals) evaluated to its share in publications – was introduced. It has been realized that the normalized Garfield Factors and the normalized SIC values are identical measures within any selected set of journals. Consequently, the Garfield Factor of a journal should be assumed as an indicator characterizing the contribution of the information channel as a whole, appropriately.

Characterization of the impact of sets of scientific papers: the Garfield (impact) factor

The Garfield (Impact) Factor (GF) is one of the most frequently used scientometric indicators. In the present article it is shown that the main factors determining the value of the mean GF representing a set of journals are the number of articles published recently (articles referencing) related to those published in a previous time period (articles to be referenced) and the mean number of references in journal papers referring to the time period selected. It has been proved further that GF corresponds to the mean chance for citedness of journal papers. A new indicator, Specific Impact Contribution (SIC), is introduced, which characterizes the contribution of a subset of articles or a journal to the total impact of the respective articles or journals. The SIC index relates the share of a journal in citations divided by that in publications within a set of papers or journals appropriately selected. It is shown, however, that the normalized GFs of journals and the normalized SIC indicators are identical measures within any set of journals selected. It may be stated therefore that Garfield Factors of journals (calculated correctly) are appropriate scientometric measures for characterizing the relative international eminence of journals within a set of journals appropriately selected. It is demonstrated further that SIC indicators (and so GF indexes) correspond to the (number of citations per paper) indicators generally used, within the same set of papers.