GeolCarp_Vol53_No2_133

GEOLOGICA CARPATHICA, 53, 2, BRATISLAVA, APRIL 2002

133 — 136

CLAY SCIENCE FROM THE PUBLICATION AND CITATION

ANALYSIS PERSPECTIVE

KAROL JESENÁK, UBOMÍR KUCHTA and VLADIMÍR HLAVATÝ

Department of Inorganic Chemistry, Faculty of Science, Comenius University,

842 15 Bratislava, Slovak Republic; jesenak@fns.uniba.sk

(Manuscript received October 4, 2001; accepted in revised form December 13, 2001)

Abstract:  The  publication  production  of  clay  minerals  is  analysed  on  the  basis  of  the  works  registered  in  the  SCI
database  in  1980—2001.  A  continuous  increase  of  the  annual  number  of  works  in  this  period  is  registered  while  the
proportion of the number of works devoted to individual clay minerals remains almost unchanged throughout the whole
period. The subject of publication production is substantially  dependent on the type of mineral followed; material re-
search oriented papers, catalysis and organo/clay interactions research prevail among the papers with a chemical charac-
ter. The average citation response to the set of analysed papers is about 10—15 citations/paper and uncited papers repre-
sent 9—35 % of the total number of papers. The most cited papers (in individual years) are cited on average 109-times
annually and half-time of the citations count per paper exceeds 20 years. The average time between appearing and the
greatest citation response can be estimated at 5 years.

Key words: citation analysis, publication production, clay minerals.

Introduction

Clay  minerals  research  covers,  due  to  its  interdisciplinary
character, the scientific fields of geology, pedology, chemistry,
environmental sciences and even astronomy. The use of clay
minerals is wide and includes not only basic research method-
ologies, but also a large spectrum of industrial and technical
applications. Subject diversity of papers and the wide variety
of journals in which the papers are published show the hetero-
geneity  of  clay  research.  Though  this  character  of  clay  re-
search  is  well  known  there  are  no  reliable  statistical  data  to
prove this statement. One possible way to tackle this problem
is evaluation of the number of journals where works on clays
appear. Such an attempt was made in 1998 (Jesenák & Kuchta
1998).  The  results  show  that  chemical  works  dealing  with
clays appear in approximately 800 scientific journals. This fact
can  be  quite  surprising  for  a  major  part  of  the  community
working  in  this  scientific  field.  It  is  mainly  due  to  the  great
popularity of periodicals selecting only a small part of the total
publication production in this field. A detailed description of
the situation in the clay science publication activity was pub-
lished  in  (Jesenák  &  Kuchta  1998;  Jesenák  &  Kuchta  1993)
aiming not only at quantification of the known facts about the
character of scientific production, but also at documentation of
long term trends in this field. However, some of the data were
outdated  already  at  the  time  of  appearance  of  the  work  (Je-
senák & Kuchta 1998).

The objective of this work is to provide an up-to-date survey

of publication production in clay science. A pronounced dif-
ference between papers mentioned above and the present work
is that the present survey is not limited to the works of chemi-
cal character, but involves all fields of natural sciences.

Methods

An electronic database of the SCI periodical, which was

freely available on the Internet (web page of Institute for Sci-
entific Information, Philadelphia, USA) in May 2001, was
used for analysis. Concerning the philosophy of the SCI data-
base architecture, the analysed set comprises quite narrow, but
important groups of works from all scientific fields.

The analysed set included bibliographic data from all works

registered in the SCI in 1980—2001 where the name of any
clay mineral was found as a key word. A program associated
with the SCI database was applied for selection of relevant
data; some MS DOS programs were created by the authors and
applied for special tasks.

Results and discussion

The trend in the number of the papers with the key word

“montmorillonite”  in  the  last  20 years  is  shown  in  Fig.  1.  A
stabilized  situation  in  1980—1990  is  followed  by  a  period  of
continuous  growth.  Considering  the  trend  in  1930—1997
worked  out  from  the  Chemical  Abstracts  (CA)  database  (Je-
senák & Kuchta 1998), which shows an almost stabilized situ-
ation since the late 1980s, the increase of registered publica-
tion count in the early 1990s can be explained by a change of
the SCI database processing conception and possibly by some
changes in the organizational system and technical equipment
rather than by a real growth of the published papers. This opin-
ion is supported by the fact that the turning point goes back to
the  period  of  revolutionary  changes  of  technical  equipment
and information services. It is assumed that ascendant charac-

MECC ‘01

134 JESENÁK, KUCHTA and HLAVATÝ

organic

compounds

inorganic

compounds

radionuclides

Fig. 1. Number of works (y-axis) with the key word “montmorillo-
nite”, registered in the SCI in 1980—2000.

100

150

200

250

300

350

400

450

500

1980

1985

1990

1995

2000

lin

cti

Illit

lit

logopi

apom

nni

200

400

600

800

1000

1200

1400

1600

1800

material

science

environmental

science

soil &

agriculture

others

sorption

catalysis

pillared clays

nanomaterials

others

ter  of  the  curve  for  the  late  1990s  is  an  expression  of  a  real
trend  in  the  development  of  publication  activity.  Fig. 1  sug-
gests that the SCI database could hardly be considered a reli-
able basis for literature review in clay science until the end of
1980s.  But  the  situation  improved  dramatically  in  the  early
1990s  and  currently  the  annual  number  of  registered  papers
approaches the number of papers registered in CA. It should
be  emphasised  that  in  spite  of  the  large  overlap  of  both  sets
(SCI—CA), these sets are not identical.

Fig. 2 shows the subject orientation of the publication pro-

duction  in  1998—2000.  Compared  with  a  similar  histogram
from  CA  for  almost  70  years  (1931—1997)  no  significant
changes  are  found,  but  exchange  of  neighbouring  positions.
Montmorillonite can be evaluated as the long term most cited
clay mineral. From the subject point of view, sets of papers on
individual clay minerals differ significantly. A special position
belongs to the papers on montmorillonite due to their high de-
gree of heterogeneity (Fig. 3). In the papers on montmorillo-
nite a chemical character prevails in contrast to the predomi-
nantly geological orientation of papers dealing with other clay
minerals. Besides the classical montmorillonite topics “sorp-
tion” and “catalysis”, a great part of the papers can be classi-
fied as material science. The proportion of papers on montmo-
rillonite-organic  interaction  is  higher  than  that  on  montmo-
rillonite-inorganic interaction. However, considering the vast
prevalence of numbers of existing organic over inorganic com-
pounds,  montmorillonite-inorganic  interactions  appear  of

Fig. 3. Subject orientation of current publication production on
montmorillonite and mutual proportion of works in group “sorp-
tion” (works registered in the SCI in 1998—2000).

greater  importance.  The  proportion  of  papers  dealing  with
sorption  of  radionuclides  is  currently  much  lower  than  20
years  ago.  Papers  with  the  subject  “vermiculite”  represent  a
certain transition between papers on montmorillonite and oth-
er  clay  minerals,  with  a  rather  high  proportion  of  chemical
works.

The evaluation of scientific importance of publication activ-

ity is often derived from the citation response. Though this
work should not be looked at as a support for this opinion, it
provides necessary data for such considerations. For this pur-
pose, only papers with the key word “montmorillonite” pub-
lished in 1980—2000 were used since the number of hits in the
whole analysed set is too large and processing would be un-
comfortable. If citations from 1998—2000 are not taken into ac-
count (they represent only a small proportion of the total num-

Fig. 2. Number of papers dealing with individual clay minerals
registered in the SCI in period from 1980 to 2000.

CLAY SCIENCE FROM THE PUBLICATION AND CITATION PERSPECTIVE 135

Fig. 4. Citation counts in individual years (y-axis) registered in
the SCI for the 6 most cited papers on montmorillonite.

100

150

200

250

300

350

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

C. C.

Paper

293

Corma 1997: From microporous to mesoporous molecular sieve materials and their use in catalysis. Chemical Reviews

218

Lvov et al. 1995: Assembly of multycomponent protein films by means of electrostatic layer-by-layer adsorption. Journal

of American Chemical Society

157

Occelli & Tindwa 1983: Physicochemical properties of montmorillonite interlayered with cationic oxyaluminum pillars.

Clays and Clay Minerals

146

Sterte 1986: Synthesis and properties of titanium-oxide cross-linked montmorillonite. Clays and Clay Minerals

129

Usuki et al. 1993: Synthesis of nylon 6-clay hybrid. Journal of Materials Research

115

Gu et al. 1994: Adsorption and desorption of natural organic-matter on iron-oxide — mechanisms and models.

Environmental Science & Technology

105

Clark et al. 1989: Montmorillonite supported transition-metal salts as Friedel-Crafts alkylation catalysts. Journal of

Chemical Society – Chemical communications

Ege et al. 1985: Clay modified electrodes. 3. Electrochemical and electron-spin resonance studies of montmorillonite

layers. Journal of American Chemical Society

Xing et al. 1996: Competitive sorption between atrazine and other organic compounds in soils and model sorbents.

Environmental Science & Technology

Aranda & Ruizhitzky 1992: Poly(ethylen oxide)-silicate intercalation materials. Chemistry of Materials

Yamanaka et al. 1984: High surface-area solids obtained by intercalation of iron-oxide pillars in montmorillonite.

Materials Research Bulletin

Koide 1991: Nutrient supply, nutrient demand and plant-response to mycorrhizal infection. New Phytologist

White & Bard 1986: Clay modified electrodes. 4. The electrochemistry and electron-spin-resonance of methyl viologen

incorporated into montmorillonite films. Journal of Electroanalytical Chemistry

Oster et al. 1980: Flocculation value and gel structure of sodium-calcium montmorillonite and illite suspensions. Soil

Science Society of America Journal

Plenchette et al. 1982: Effects of different endomycorrhizal fungi on 5 host plants grown on calcined montmorillonite clay.

Journal of the American Society for Horticultural Science

Clark & Macquarrie 1998: Catalysis of liquid phase organic reactions using chemically modified mesoporous inorganic

solids. Chemical Communications

Johnson et al. 1999: Ordered mesoporous polymers of tunable pore size from colloidal silica templates. Science

Keren et al. 1981: pH-dependent boron adsorption by Na-montmorillonite. Soil Science Society of America Journal

Kawai et al.1988: New application of solid acid to carbon-carbon bond formation reactios — clay montmorillonite-

catalyzed aldol reactions of silyl enol ethers with aldehydes and acetals. Bulletin of the Chemical Society of Japan

Barloy et al. 1990: Manganese porphyrins supported on montmorillonite as hydrocarbon monooxygenation catalysts –

particular efficiency for linear alkane hydroxylation. Journal of Chemical Society – Chemical communications

Table 1: 20 papers with highest citation index registered in the SCI database in 1980—2001 (C. C. – citation counts).

ber of citations), citation counts per one paper in this set varies
in a narrow range from 21 to 56 citations with an average of 36
citations/paper.  It  is  quite  interesting  that  almost  exclusively
the two most cited works are responsible for the extent of the
range (minimum and maximum citations) while the values for
other papers are near the average. The average value for the 10
most cited works within the whole set is 109 citations/hit. The
subject orientation of a given set of papers with the greatest ci-
tation response represents approximately the whole publication
production in this research field (Table 1). Fig. 5 shows the av-
erage citation count per work of the 10 most significant works
published in the year 1980. Provided that we ignore an initial
part of the curve (1980), the average citation count/paper var-
ies around 18 citations/paper. The half-time of citation count/
paper  in  this  group  of  papers  far  exceeds  20  years  which  is
considered a very high value in natural sciences. If the whole
group of all published papers is considered, the average time
between appearance of a paper in a journal and its citation “re-
action”  is  approximately  5  years.  Fig.  4  shows  the  citation
counts for the 6 most cited papers in a given year.

An average number of citations per paper in the whole anal-

ysed set varies in a narrow range of 10 to 15 citations/paper.
Uncited publications comprise some 10 to 35 % of the total

number of published works. We assume that the average cita-
tion counts/paper of the whole publication production in clay
research would be significantly lower. This situation is partly
caused by lasting difficulties with finding relevant informa-
tion – these troubles are obviously of a general character and
not confined to clay research. This situation is, of course, in-
consistent with present possibilities of information services. It
could be explained by unattainable prices for complete infor-

136 JESENÁK, KUCHTA and HLAVATÝ

mation, at least in Central and Eastern European countries. In
this respect, the high degree of diversification of journals on
clays plays an important role, which has a very negative effect,
particularly on compilation of retrospective literature reviews.
It is just this fact, which is crucial in the unnatural outdating of
information. It is questionable whether the present major ori-
entation to review periodicals, such as Current Contents (and
also SCI) is, from the statistical point of view, an inevitable
consequence of present possibilities or a manifestation of a
free research philosophy.

Conclusion

The analysis of publication production in clay science field

offers possibilities for its objective evaluation and comparison
with production in other scientific fields. It is well known that
such evaluation is often used as a reason for justification of the
meaningfulness of research programs as well as their back-
ward evaluation. Opening of discussion about the philosophy,
strategy and organization of research information services at
academic workplaces in Slovakia can be considered as a by-
product of this analysis.

Acknowledgments: The authors would like to thank the com-
pany I.T.S. Slovakia, the Ministry of Education of the Slovak
Republic and ISI, Philadelphia for enabling us to access the
SCI database and for an inspiring example how to approach
problems in information services of academic workplaces.

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