  SEQ CHAPTER \h \r 1 Bibliometric Analysis

for the U.S. Environmental Protection Agency/Office of Research and
Development’s Science and Technology for Sustainability (STS) Research
Program

This is a bibliometric analysis of the papers prepared by intramural and
extramural researchers of the U.S. Environmental Protection Agency (EPA)
of the Science and Technology for Sustainability (STS) Research Program.
 For this analysis, 794 journal papers and 71 non-journal publications,
published from 1998 to 2008, were reviewed.  The 794 journal papers were
cited 18,684 times and the 71 non-journal publications were cited 1,637
times in the journals covered by Thomson Reuter’s Web of Science1 and
Scopus.  Of the 794 journal papers, 723 (91.1%) have been cited at least
once in a journal. Of the 71 non-journal publications, 34 (47.9%) have
been cited at least once in a journal.

Searches of Thomson Reuter’s Web of Science and Scopus were conducted
to obtain times cited data for the STS journal publications.  The
analysis was completed using Thomson Reuter’s Essential Science
Indicators (ESI) and Journal Citation Reports (JCR) as benchmarks. ESI
provides access to a unique and comprehensive compilation of essential
science performance statistics and science trends data derived from
Thomson Reuter’s databases. For this analysis, the ESI highly cited
papers thresholds as well as the hot papers thresholds were used to
assess the influence and impact of the STS papers. JCR is a recognized
authority for evaluating journals.  It presents quantifiable statistical
data that provide a systematic, objective way to evaluate the world’s
leading journals and their impact and influence in the global research
community. The two key measures used in this analysis to assess the
journals in which the EPA STS papers are published are the Impact Factor
and Immediacy Index. The Impact Factor is a measure of the frequency
with which the “average article” in a journal has been cited in a
particular year.  The Impact Factor helps evaluate a journal’s
relative importance, especially when compared to other journals in the
same field.  The Immediacy Index is a measure of how quickly the
“average article” in a journal is cited.  This index indicates how
often articles published in a journal are cited within the same year and
it is useful in comparing how quickly journals are cited.  

The report includes a summary of the results of the analysis, an
analysis of the 794 STS journal papers analyzed by ESI field (e.g.,
chemistry, environment/ecology, materials science), an analysis of the
journals in which the 794 STS papers were published, a table of the
highly cited researchers in the STS Research Program, an analysis of the
non-journal publications, and a list of the patents and patent
applications resulting from the program.

 

Highly Cited STS Publications

All of the journals covered by ESI are assigned a field, and to
compensate for varying citation rates across scientific fields,
different thresholds are applied to each field.  Thresholds are set to
select highly cited papers to be listed in ESI.  Different thresholds
are set for both field and year of publication. Setting different
thresholds for each year allows comparable representation for older and
younger papers for each field. 

The 794 STS journal papers reviewed for this analysis were published in
journals that were assigned to 19 of the 22 ESI fields.  The
distribution of the papers among these 19 fields and the number of
citations by field are presented in Table 1.

Table 1.  STS Papers by ESI Fields

ESI Field	No. of Citations 	No. of EPA STS Papers	Average Cites/Paper

Agricultural Sciences	26   	2     	13.0     

Biology & Biochemistry	836   	43     	19.4     

Chemistry	13,714   	434     	31.6     

Clinical Medicine	61   	2    	30.5     

Computer Science	125   	7     	  17.8   

Economics & Business	32	1	32.0

Engineering	1,488   	119     	12.5     

Environment/Ecology	684   	77     	8.9     

Geosciences	68   	6     	11.3     

Immunology	22	5	4.4

Materials Science	503	52	9.7

Microbiology	224   	13     	17.2     

Molecular Biology & Genetics	84	3	28.0

Multidisciplinary	533   	3     	 177.7    

Pharmacology & Toxicology	48   	4     	12.0     

Physics 	120   	12	10.0

Plant & Animal Science	62   	3	20.7     

Psychiatry/Psychology	7	1	7.0

Social Sciences, General	47	7	6.7

	Total = 18,684	  Total = 794	23.5



There are 225 (28.3% of the papers analyzed) highly cited EPA STS papers
in 13 of the 17 fields—Biology & Biochemistry, Chemistry, Clinical
Medicine, Computer Science, Economics & Business, Engineering,
Environment/Ecology, Materials Science, Microbiology, Multidisciplinary,
Pharmacology & Toxicology, Physics, and Plant & Animal Science—when
using the ESI criteria for the top 10% of papers. The number of highly
cited papers is nearly 3 times the number expected to meet this
threshold.  Table 2 shows the number of STS papers in those 13 fields
that meet the top 10% threshold in ESI.  

Table 2.  Number of Highly Cited STS Papers by Field (top 10%)

ESI Field	Citations	No. of Papers	Average Cites/Paper	% of EPA Papers in
Field

Biology & Biochemistry	394	5	78.8	11.6%

Chemistry	10,411	153   	68.0        	35.2%    

Clinical Medicine	57	1	57.0	50.0%

Computer Science	122	6	20.3	85.7%

Economics & Business	32	1	32.0	100.0%

Engineering	1,126	32   	35.2    	26.9%     

Environment/Ecology	298	5	59.6    	6.5%     

Materials Science	354	15	23.6	28.8%

Microbiology	68	1	68.0	7.7%

Multidisciplinary	533	3   	533.0        	100.0%     

Pharmacology & Toxicology	13	1	13.0	25.0%

Physics	32	1	32.0	8.3%

Plant & Animal Science	62	1   	62.0    	33.3%     

	Total =  13,502	Total = 225  	60.0	28.3%



Thirty-five (4.4%) of the papers analyzed qualify as highly cited when
using the ESI criteria for the top 1% of papers, which is more than 4
times higher than the expected number to meet this threshold.  These
papers cover six fields—Chemistry, Engineering, Multidisciplinary,
Environment/Ecology, Materials Science, and Plant & Animal Science. 
Table 3 shows the 32 papers by field that meet the top 1% threshold in
ESI.  The citations for these 32 papers are provided in Tables 4 through
9.  There were 7 (0.9%) very highly cited STS papers in the fields of
Chemistry, Engineering, and Multidisciplinary (see Table 10), which is 9
times the number expected to meet this threshold.  These papers, which
meet the top 0.1% threshold in ESI, are listed in Tables 11 through 13. 
One of the STS papers actually meets the top 0.01% threshold in ESI,
which represents 0.1% of the papers (see Table 14). This is 10 times the
number expected to meet this threshold.  The citation for this paper is
provided in Table 15.

Table 3.  Number of Highly Cited STS Papers by Field (top 1%)

ESI Field	Citations	No. of Papers	Average Cites/Paper	% of EPA Papers in
Field

Chemistry	3,482   	25	139.3   	5.8%     

Engineering	498   	5	99.6    	4.2%     

Environment/Ecology 	185   	2	92.5   	2.6%     

Materials Science	57	1	57.0	1.9%

Multidisciplinary	486   	1	486.0    	33.3%     

Plant & Animal Science	62	1	62.0	33.3%

	Total = 6,180	Total = 35 	176.6	4.4%



Table 4.  Highly Cited STS Papers in the Field of Chemistry (top 1%)

No. of Cites	First Author	Paper

138	Mesiano AJ	Supercritical biocatalysis. Chemical Reviews
1999;99(2):623-633.

200	Hudlicky T	Enzymatic dihydroxylation of aromatics in
enantioselective synthesis: Expanding asymmetric methodology. 
Aldrichimica Acta 1999;32(2):35-62.

219	Matyjaszewski K	Transition metal catalysis in controlled radical
polymerization: atom transfer radical polymerization.  Chemistry-A
European Journal 1999;5(11):3095-3102.

291	Patten TE	Copper(I)-catalyzed atom transfer radical polymerization.
Accounts of Chemical Research 1999;32(10):895-903.

446	Li CJ	Organic syntheses using indium-mediated and catalyzed
reactions in aqueous media.  Tetrahedron 1999;55(37):11149-11176.

743	Varma RS	Solvent-free organic syntheses - using supported reagents
and microwave irradiation.  Green Chemistry 1999;1(1):43-55.

158	Matyjaszewski K	Gradient copolymers by atom transfer radical
copolymerization.  Journal of Physical Organic Chemistry
2000;13(12):775-786.

168	Varma RS	Solvent-free accelerated organic syntheses using
microwaves.  Pure and Applied Chemistry 2001;73(1):193-198.

234	Blanchard LA	High-pressure phase behavior of ionic liquid/CO2
systems.  Journal of Physical Chemistry B 2001;105(12):2437-2444.

830	Huddleston JG	Characterization and comparison of hydrophilic and
hydrophobic room temperature ionic liquids incorporating the imidazolium
cation.  Green Chemistry 2001;3(4):156-164.

152	Holbrey JD	Efficient, halide free synthesis of new, low cost ionic
liquids: 1,3-dialkylimidazolium salts containing methyl- and
ethyl-sulfate anions.  Green Chemistry 2002;4(5):407-413.

154	Wei CM	Enantioselective direct-addition of terminal alkynes to
imines catalyzed by copper(I)pybox complex in water and in toluene.
Journal of the American Chemical Society 2002;124(20):5638-5639.

184	Varma RS	Clay and clay-supported reagents in organic synthesis. 
Tetrahedron 2002;58(7):1235-1255.

90	Holbrey JD	Liquid clathrate formation in ionic liquid-aromatic
mixtures.  Chemical Communications 2003;(4):476-477.

99	Gutowski KE	Controlling the aqueous miscibility of ionic liquids: 
aqueous biphasic systems of water-miscible ionic liquids and
water-structuring salts for recycle, metathesis, and separations. 
Journal of the American Chemical Society 2003;125(22):6632-6633.

129	Holbrey JD	Crystal polymorphism in 1-butyl-3-methylimidazolium
halides: supporting ionic liquid formation by inhibition of
crystallization.  Chemical Communications 2003;14:1636-1637.

140	Kaar JL	Impact of ionic liquid physical properties on lipase
activity and stability.  Journal of the American Chemical Society
2003;125(14):4125-4131.

218	Swatloski RP	Ionic liquids are not always green: hydrolysis of
1-butyl-3-methylimidazolium hexafluorophosphate.  Green Chemistry
2003;5(4):361-363.

34	Kim JH	Ultra-deep desulfurization and denitrogenation of diesel fuel
by selective adsorption over three different adsorbents:  a study on
adsorptive selectivity and mechanism.  Catalysis Today
2006;111(1-2):74-83.

37	Remsing RC	Mechanism of cellulose dissolution in the ionic liquid
1-n-butyl-3-methylimidazolium chloride: a C-13 and Cl-35/37 NMR
relaxation study on model systems.  Chemical Communications
2006;(12):1271-1273.

153	Li CJ	Organic chemistry in water.  Chemical Society Reviews
2006;35(1):68-82.

18	Polshettiwar V	Tandem bis-aldol reaction of ketones:  a facile
one-pot synthesis of 1,3-dioxanes in aqueous medium.  Journal of Organic
Chemistry 2007;72(19):7420-7422.

32	Zhang YH	Gold(III)-catalyzed double hydroamination of
o-alkynylaniline with terminal alkynes leading to N-vinylindoles. 
Organic Letters 2007;9(4):627-630.

10	Polshettiwar V	Greener and rapid access to bio-active heterocycles:
room temperature synthesis of pyrazoles and diazepines in aqueous
medium.  Tetrahedron Letters 2008;49(2):397-400.

15	Polshettiwar V	Microwave-assisted organic synthesis and
transformations using benign reaction media.  Accounts of Chemical
Research 2008;41(5):629-639.



Table 5.  Highly Cited STS Papers in the Field of Engineering (top 1%)

No. of Cites	First Author	Paper

66	Clancy JL	UV light inactivation of Cryptosporidium oocysts.  Journal
of the American Water Works Association 1998;90(9):92-102.

84	Bukhari Z	Medium-pressure UV for oocyst inactivation.  Journal of the
American Water Works Association 1999;91(3):86-94.

254	Blanchard LA	Recovery of organic products from ionic liquids using
supercritical carbon dioxide.  Industrial & Engineering Chemistry
Research 2001;40(1):287-292.

77	Abraham MH	Some novel liquid partitioning systems: water-ionic
liquids and aqueous biphasic systems.  Industrial & Engineering
Chemistry Research 2003;42(3):413-418.

17	von Blottnitz H	A review of assessments conducted on bio-ethanol as a
transportation fuel from a net energy, greenhouse gas, and environmental
life cycle perspective.  Journal of Cleaner Production
2007;15(7):607-619.



Table 6.  Highly Cited STS Papers in the Field of Environment/Ecology
(top 1%)

No. of Cites	First Author	Paper

117	Visser AE	Task-specific ionic liquids incorporating novel cations
for the coordination and extraction of Hg2+ and Cd2+:  synthesis,
characterization, and extraction studies.  Environmental Science &
Technology 2002;36(11):2523-2529.

68	Suh S	System boundary selection in life-cycle inventories using
hybrid approaches.  Environmental Science & Technology
2004;38(3):657-664.



Table 7.  Highly Cited STS Paper in the Field of Materials Science (top
1%)

No. of Cites	First Author	Paper

57	Li Y	Recent advances of conductive adhesives as a lead-free
alternative in electronic packaging:  materials, processing, reliability
and applications.  Materials Science & Engineering: R:  Reports
2006;51(1-3):1-35.



Table 8.  Highly Cited STS Paper in the Field of Multidisciplinary (top
1%)

No. of Cites	First Author	Paper

486	Blanchard LA	Green processing using ionic liquids and CO2.  Nature
1999;399(6731):28-29.



Table 9.  Highly Cited STS Paper in the Field of Plant & Animal Science
(top 1%)

No. of Cites	First Author	Paper

62	Walsh CJ	The urban stream syndrome: current knowledge and the search
for a cure.  Journal of the North American Benthological Society
2005;24(3):706-723. 



Table 10.  Number of Very Highly Cited STS Papers by Field (top 0.1%)

ESI Field	Citations	No. of Papers	Average Cites/Paper	% of EPA Papers in
Field

Chemistry	2,187   	5	437.4   	1.1%     

Engineering	254   	1	254.0    	0.8%     

Multidisciplinary	486   	1	486.0    	33.3%     

	Total = 2,927	Total = 7 	418.1	1.0%



Table 11.  Very Highly Cited STS Papers in the Field of Chemistry (top
0.1%)

No. of Cites	First Author	Paper

446	Li CJ	Organic syntheses using indium-mediated and catalyzed
reactions in aqueous media.  Tetrahedron 1999;55(37):11149-11176.

743	Varma RS	Solvent-free organic syntheses—using supported reagents
and microwave irradiation.  Green Chemistry 1999;1(1):43-55.

830	Huddleston JG	Characterization and comparison of hydrophilic and
hydrophobic room temperature ionic liquids incorporating the imidazolium
cation.  Green Chemistry 2001;3(4):156-164.

153	Li CJ	Organic chemistry in water.  Chemical Society Reviews
2006;35(1):68-82.

15	Polshettiwar V	Microwave-assisted organic synthesis and
transformations using benign reaction media.  Accounts of Chemical
Research 2008;41(5):629-639.



Table 12.  Very Highly Cited STS Papers in the Field of Engineering (top
0.1%)

No. of Cites	First Author	Paper

254	Blanchard LA	Recovery of organic products from ionic liquids using
supercritical carbon dioxide.  Industrial & Engineering Chemistry
Research 2001;40(1):287-292.



Table 13.  Very Highly Cited STS Paper (top 0.1%)

ESI Field	No. of Cites	First Author	Paper

Multidisciplinary 	486	Blanchard LA	Green processing using ionic liquids
and CO2.  Nature 1999;399(6731):28-29.



Table 14.  Number of Extremely Highly Cited STS Papers by Field (top
0.01%)

ESI Field	Citations	No. of Papers	Average Cites/Paper	% of EPA Papers in
Field

Multidisciplinary	486   	1	486.0    	33.3%     

	Total = 486	Total = 1 	486.0	0.1%



Table 15.  Extremely Highly Cited STS Papers (top 0.01%)

ESI Field	No. of Cites	First Author	Paper

Multidisciplinary 	486	Blanchard LA	Green processing using ionic liquids
and CO2.  Nature 1999;399(6731):28-29.



Ratio of Actual Cites to Expected Citation Rates

The expected citation rate is the average number of cites that a paper
published in the same journal in the same year and of the same document
type (article, review, editorial, etc.) has received from the year of
publication to the present.  Using the ESI average citation rates for
papers published by field as the benchmark, in 13 of the 19 fields in
which the EPA STS papers were published, the ratio of actual to expected
cites is greater than 1, indicating that the STS papers are more highly
cited than the average papers in those fields (see Table 16).  For all
19 fields combined, the ratio of total number of cites to the total
number of expected cites (18,684 to 8,029.2) is 2.3, indicating that the
STS papers are more highly cited than the average paper. 

Table 16.  Ratio of Actual Cites to Expected Cites for STS Papers by
Field

ESI Field	Total Cites	Expected Cite Rate	Ratio

Agricultural Sciences	26	17.3	1.5

Biology & Biochemistry	836	749.0	1.1

Chemistry	13,714	4,944.5	2.8

Clinical Medicine	61	39.4	1.5

Computer Science	125	30.3	4.1

Economics & Business	32	10.2	3.1

Engineering	1,488	569.8	2.6

Environment/Ecology	684	616.1	1.1

Geosciences	68	76.6	0.9

Immunology	22	110.4	0.2

Materials Science	503	303.0	1.7

Microbiology	224	226.8	<1.0

Molecular Biology & Genetics	84	106.6	0.8

Multidisciplinary	533	13.1	40.7

Pharmacology & Toxicology 	48	35.9	1.3

Physics	120	122.7	<1.0

Plant & Animal Science	62   	10.2	6.1

Psychiatry/Psychology	7	16.3	0.4

Social Sciences, General	47	31.0	1.5

TOTAL	18,684	8,029.2	2.3



JCR Benchmarks

Impact Factor.  The JCR Impact Factor is a well known metric in citation
analysis.  It is a measure of the frequency with which the “average
article” in a journal has been cited in a particular year.  The Impact
Factor helps evaluate a journal’s relative importance, especially when
compared to others in the same field.  The Impact Factor is calculated
by dividing the number of citations in the current year to articles
published in the 2 previous years by the total number of articles
published in the 2 previous years.  

Table 17 indicates the number of STS papers published in the top 10% of
journals, based on the JCR Impact Factor.  Two hundred eighty-one (281)
of 794 papers were published in the top 10% of journals, representing
35.4% of EPA’s STS journal papers. This indicates that more than
one-third of the STS papers are published in the highest quality
journals as determined by the JCR Impact Factor, which is 3.5 times
higher than the expected percentage.

Table 17.  STS Papers in Top 10% of Journals by JCR Impact Factor

EPA STS Papers in that Journal	Journal	Impact Factor

(IF)	JCR IF Rank

1	Nature 	28.751	10

2	Science	26.372	14

1	Chemical Reviews	22.757	24

3	Accounts of Chemical Research	16.214	43

1	Materials Science & Engineering:  R:  Reports	14.400	59

1	Chemical Society Reviews	13.082	69

1	Aldrichimica Acta	11.929	78

3	Angewandte Chemie-International Edition	10.031	105

16	Journal of the American Chemical Society	7.885	156

2	Advanced Functional Materials	7.496	175

2	Chemistry-A European Journal	5.330	307

1	Analytical Chemistry	5.287	309

1	Biotechnology Advances	5.236	321

26	Chemical Communications	5.141	331

1	Advanced Synthesis & Catalysis	4.977	348

1	Environmental Microbiology	4.929	354

1	Journal of Medicinal Chemistry	4.895	359

6	Chemistry of Materials	4.883	361

32	Green Chemistry	4.836	367

1	Ecology	4.822	370

11	Organic Letters	4.802	375

4	Journal of Catalysis	4.737	386

5	Applied Catalysis B-Environmental	4.651	402

31	Macromolecules	4.411	454

30	Environmental Science & Technology	4.363	465

6	Journal of Materials Chemistry	4.339	470

1	Frontiers in Ecology and the Environment	4.269	493

6	Biomacromolecules	4.169	519

1	Inorganic Chemistry	4.123	532

7	Journal of Physical Chemistry B	4.086	542

1	Bioscience	4.083	543

1	Journal of Urology	4.053	549

5	Crystal Growth & Design	4.046	551

3	Journal of Bacteriology	4.013	566

5	Langmuir	4.009	567

2	Applied and Environmental Microbiology	4.004	571

4	Current Organic Chemistry	3.961	584

19	Journal of Organic Chemistry	3.959	586

3	Organometallics	3.833	618

2	Journal of Macromolecular Science-Pure and Applied Chemistry	3.769	640

1	Current Opinion in Drug Discovery & Development	3.760	647

1	Geology	3.754	650

3	Applied Physics Letters	3.596	713

13	Journal of Polymer Science Part A-Polymer Chemistry	3.529	740

1	Chemical Research in Toxicology	3.508	745

2	Metabolic Engineering	3.444	772

4	Water Research	3.427	777

4	Macromolecular Rapid Communications	3.383	794

1	Advances in Biochemical Engineering/Biotechnology	3.253	851

1	Dalton Transactions	3.212	867

Total = 281		





Immediacy Index.  The JCR Immediacy Index is a measure of how quickly
the average article in a journal is cited.  It indicates how often
articles published in a journal are cited within the year they are
published.  The Immediacy Index is calculated by dividing the number of
citations to articles published in a given year by the number of
articles published in that year.

Table 18 indicates the number of STS papers published in the top 10% of
journals, based on the JCR Immediacy Index.  Two hundred seventy-five
(275) of the 794 papers appear in the top 10% of journals, representing
34.6% of the STS papers. This indicates that more than one-third of the
STS papers are published in the highest quality journals as determined
by the JCR Immediacy Index, which is 3.5 times higher than the expected
percentage.

Table 18.  STS Papers in Top 10% of Journals by JCR Immediacy Index

EPA STS Papers in that Journal	Journal	Immediacy Index

(II)	JCR II Rank

1	Nature 	7.385	9

2	Science	6.387	15

1	Aldrichimica Acta	4.625	29

1	Chemical Society Reviews	3.406	44

1	Chemical Reviews	3.274	48

3	Angewandte Chemie-International Edition	2.271	98

3	Accounts of Chemical Research	1.736	133

16	Journal of the American Chemical Society	1.397	212

3	Environmental Science & Policy	1.298	241

26	Chemical Communications	1.297	242

2	Metabolic Engineering	1.146	297

11	Organic Letters	1.133	302

2	Chemistry-A European Journal	1.033	355

1	Environmental Modelling & Software	0.976	410

32	Green Chemistry	0.955	428

1	Analytical Chemistry	0.911	471

1	Frontiers in Ecology and the Environment	0.907	476

1	Environmental Microbiology	0.900	483

3	Journal of Bacteriology	0.893	492

19	Journal of Organic Chemistry	0.886	498

3	Organometallics	0.876	504

7	Journal of Industrial Ecology	0.868	514

1	Biometals	0.859	526

1	Advanced Synthesis & Catalysis	0.852	536

4	Journal of Catalysis	0.800	576

6	Journal of Materials Chemistry	0.799	580

1	Journal of Medicinal Chemistry	0.789	594

1	Ecology and Society	0.789	594

4	Macromolecular Rapid Communications	0.787	597

1	Journal of Soil and Water Conservation	0.778	608

1	AMBIO	0.777	610

1	Bioscience	0.761	626

1	Dalton Transactions	0.758	633

31	Macromolecules	0.755	637

1	Inorganic Chemistry	0.747	650

9	International Journal of Life Cycle Assessment	0.712	694

1	Journal of Urology	0.688	733

2	New Journal of Chemistry	0.687	738

2	Advanced Functional Materials	0.683	745

1	European Journal of Organic Chemistry	0.669	772

5	Applied Catalysis B-Environmental	0.666	779

1	Geology	0.660	789

5	Langmuir	0.657	796

9	Tetrahedron	0.637	835

6	Chemistry of Materials	0.632	845

7	Journal of Physical Chemistry B	0.629	851

3	Applied Physics Letters	0.627	856

30	Environmental Science & Technology	0.615	876

Total = 275



	

Hot Papers

ESI establishes citation thresholds for hot papers, which are selected
from the highly cited papers in different fields, but the time frame for
citing and cited papers is much shorter—papers must be cited within 2
years of publication and the citations must occur in a 2-month time
period.  Papers are assigned to 2-month periods and thresholds are set
for each period and field to select 0.1% of papers.  

Using the hot paper thresholds established by ESI as a benchmark, 11 hot
papers, representing 1.4% of the STS papers, were identified in the
fields of Chemistry, Engineering, and Plant & Animal Science.  The
number of STS hot papers is 14 times higher than expected. The hot
papers are listed in Table 19. 

Table 19.  Hot Papers Identified Using ESI Thresholds

Field	ESI Hot Papers Threshold	No. of Cites in 2-Month Period	Paper

Chemistry	9	10 cites in September-October 2000	Li C-J, Chan T-H. 
Organic syntheses using indium-mediated and catalyzed reactions in
aqueous media.  Tetrahedron 1999;55(37):11149-11176.

	12	12 cites in December 2000-January 2001	Varma RS.  Solvent-free
organic syntheses - using supported reagents and microwave irradiation. 
Green Chemistry 1999;1(1):43-55.

	11	16 cites in April-May 2003	Huddleston JG, Visser AE, Reichert WM, et
al.  Characterization and comparison of hydrophilic and hydrophobic room
temperature ionic liquids incorporating the imadazolium cation.  Green
Chemistry 2001;3(4):156-164.

	9	9 cites in July-August 2004	Swatloski RP, et al.  Ionic liquids are
not always green: hydrolysis of 1-butyl-3-methylimidazolium
hexafluorophosphate.  Green Chemistry 2003;5(4):361-363.

	9	11 in November-December 2006	Li CJ, Chen L. Organic chemistry in
water. Chemical Society Reviews 2006;35(1):68-82.

	4	4 in November-December 2007	Polshettiwar V, Varma RS.  Biginelli
reaction in aqueous medium: a greener and sustainable approach to
substituted 3,4-dihydropyrimidin-2(1H)-ones.  Tetrahedron Letters
2007;48(41):7343-7346.

	4	4 in November-December 2007	Polshettiwar V, Varma RS.  Tandem
bis-aldol reaction of ketones: a facile one-pot synthesis of
1,3-dioxanes in aqueous medium.  Journal of Organic Chemistry
2007;72(19):7420-7422.  

	7	11 in November-December 2008	Polshettiwar V, Varma RS. 
Microwave-assisted organic synthesis and transformations using benign
reaction media.  Accounts of Chemical Research 2008;41(5):629-639.

Engineering	6	6 in July-August 2000	Clancy JL, et al.  UV light
inactivation of Cryptosporidium oocysts.  Journal of the American Water
Works Association 1998;90(9):92-102.

	4	5 in January-February 2008	von Blottnitz H, Curran MA.  A review of
assessments conducted on bio-ethanol as a transportation fuel from a net
energy, greenhouse gas, and environmental life cycle perspective. 
Journal of Cleaner Production 2007;15(7):607-619.

Plant & Animal Science	5	7 in September 2005	Walsh CJ, et al.  The urban
stream syndrome: current knowledge and the search for a cure.  Journal
of the North American Benthological Society 2005;24(3):706-723.



Author Self-Citation

Self-citations are journal article references to articles from that same
author (i.e., the first author).  Because higher author self-citation
rates can inflate the number of citations, the author self-citation rate
was calculated for the STS papers.  Of the 18,684 total cites, 658 are
author self-cites—a 3.5% author self-citation rate.  Garfield and Sher
found that authors working in research-based disciplines tend to cite
themselves on the average of 20% of the time.  MacRoberts and MacRoberts
claim that approximately 10% to 30% of all the citations listed fall
into the category of author self-citation. Kovacic and Misak recently
reported a 20% author self-citation rate for medical literature. 
Therefore, the 3.5% self-cite rate for the STS papers is well below the
range for author self-citation.

Highly Cited Researchers

A search of Thomson Reuter’s ISIHighlyCited.com revealed that 13
(1.2%) of the 1,097 authors of the STS papers are highly cited
researchers.  ISIHighlyCited.com is a database of the world’s most
influential researchers who have made key contributions to science and
technology during the period from 1981 to 1999. The highly cited
researchers identified during this analysis of the STS publications are
presented in Table 20.

Table 20.  Highly Cited Researchers Authoring STS Publications

Highly Cited Researcher	Affiliation	ESI Field

Abraham, Michael H.	University College London	Chemistry

Calabrese, Joe C.	E.I. Dupont de Nemours Co.	Chemistry

Cordell, Geoffrey A.	University of Illinois-Chicago	Agricultural
Sciences

Groffman, Peter Mark	Institute of Ecosystem Studies	Environment/Ecology

Haddon, Robert C.	University of California–Riverside	Physics

Katritzky, Alan R.	University of Florida	Chemistry

Komarneni, Sridhar	Pennsylvania State University	Materials Science

Matyjaszewski, Krzysztof	Carnegie Mellon University	Chemistry

Paquette, Leo Armand	Ohio State University	Chemistry

Paul, Donald R.	University of Texas-Austin	Materials Science

Chemistry

Pielke Sr., Roger A.	University of Colorado-Boulder	Geosciences

Suidan, Makram T.	University of Cincinnati	Environment/Ecology

Wang, Yue J.	Virginia Polytechnic Institute and State University
Engineering

Total = 13





Nonjournal Publications (Books, Book Chapters, Reports, and Proceedings)

Seventy-one nonjournal publications (books, book chapters, reports, and
proceedings) produced by the program from 1998 to 2008 were included in
the analysis. Of these 71 nonjournal publications, 34 (47.9%) have been
cited at least once in a journal. The 71 publications were cited 1,637
times in the journals covered by Thomson Reuter’s ISI Web of Science.
The authors of the nonjournal publications cited themselves 17 times, a
1.0% self citation rate, which is well below the 10-30% range report in
the literature for author self-citation. Application of the ESI fields
and highly cited benchmarks used for journal papers to the nonjournal
publications, indicated that 6 (8.4%) of the nonjournal publications
were highly cited when using the ESI criteria for the top 10% of highly
cited publications. This number is slightly less than the 7 publications
expected to meet this threshold. Three of the nonjournal publications
(4.2%) met the ESI criteria for the top 1%, and one (1.4%) of the
nonjournal publications met the ESI criteria for the top 0.1%.  These
numbers are 4 and 14 times higher than the numbers expected.  None of
the nonjournal publications met the ESI criteria for the top 0.01%,
which is not surprising, given that the number expected to meet this
threshold is 0.7.  

Patents

There were 29 U.S. patents and 1 international patent issued to and 3
patent applications filed by investigators from 1998 to 2008 for
research that was conducted under EPA’s STS research program.
Seventeen (58.6%) of the 29 U.S. patents have been referenced 115 times
by other U.S. patents.  These patents and patent applications, along
with the patents that reference them, are listed in Table 21.

Table 21.  Patents and Patent Applications from the 

STS Research Program (1996-2006) 

Patent No. or Applica-tion No.	Inventor(s)	Title	Issue Date or
Applica-tion Date	No. of Patents that Referenced This Patent

5,907,075	Subramanian B, Clark MC	Solid acid supercritical alkylation
reactions using carbon dioxide and/or other co-solvents	5/25/99
Referenced by 10 patents:

(1) 7,090,830 Drug condensation aerosols and kits 

(2) 6,924,407 Pressure-tuned solid catalyzed heterogeneous chemical
reactions 

(3) 6,914,105 Continuous process for making polymers in carbon dioxide 

(4) 6,887,813 Method for reactivating solid catalysts used in alkylation
reactions 

 (5) 6,806,332 Continuous method and apparatus for separating polymer
from a high pressure carbon dioxide fluid stream 

(6) 6,579,821 Method for reactivating solid catalysts used in alkylation
reactions 

(7) 6,103,948 Solid catalyzed isoparaffin alkylation at supercritical
fluid and near-supercritical fluid conditions

(8) 7,458,374 Method and apparatus for vaporizing a compound

(9) 7,410,620 Apparatus for continuous production of polymers in carbon
dioxide

(10) 7,407,905 Method for reactivating catalysts and a method for
recycling supercritical fluids used to reactivate the catalysts

6,013,774	Meister JJ, Chen MJ	Biodegradable plastics and composites from
wood	1/11/00	Referenced by 1 patent: 

(1) 6,488,997 Degradable composite material, its disposable products and
processing method thereof

6,039,878	Sikdar S, Vane L	Recovery of volatile organic compounds in
water by pervaporation	3/21/00	Referenced by 3 patents:

(1) 6,858,145 Method of removing organic impurities from water 

(2) 6,335,202 Method and apparatus for on-line measurement of the
permeation characteristics of a permeant through dense nonporous
membrane 

(3) 6,264,726 Method of filtering a target compound from a first solvent
that is above its critical density

6,103,121	Bhattacharyya D, Bachas LG, Cullen L, Hestekin JA, Sikdar S
Membrane-based sorbent for heavy metal sequestration	8/15/00	Referenced
by 3 patents:

(1) 6,544,419 Method of preparing a composite polymer and silica-based
membrane 

(2) 6,544,418 Preparing and regenerating a composite polymer and
silica-based membrane 

(3) 6,533,938 Polymer enhanced diafiltration: filtration using PGA

6,117,328	Sikdar SK, Ji W, Wang S-t	Adsorbent-filled membranes for
pervaporation	9/12/00	Referenced by 5 patents:

(1) 7,014,681 Flexible and porous membranes and adsorbents, and method
for the production thereof 

(2) 6,779,529 Cigarette filter 

(3) 6,740,143 Mixed matrix nanoporous carbon membranes 

(4) 6,706,531 Device for conditioning a polluted soil-sample-method of
analysis by pyrolysis 

(5) 6,500,233 Purification of p-xylene using composite mixed matrix
membranes

6,138,456	Garris CA	Pressure exchanging ejector and methods of use
10/31/00	Referenced by 9 patents:

(1) 7,334,427 Ejector with tapered nozzle and tapered needle

(2) 7,143,602 Ejector-type depressurizer for vapor compression
refrigeration system 

(3) 7,137,243 Constant volume combustor 

(4) 6,966,199 Ejector with throttle controllable nozzle and ejector
cycle using the same 

(5) 6,904,769 Ejector-type depressurizer for vapor compression
refrigeration system 

(6) 6,729,158 Ejector decompression device with throttle controllable
nozzle 

(7) 6,550,265 Ejector cycle system 

(8) 6,471,489 Supersonic 4-way self-compensating fluid entrainment
device 

(9) 6,434,943 Pressure exchanging compressor-expander and methods of use

6,139,742	Bhattacharyya D, Bachas LG, Cullen L, Hestekin JA, Sikdar SK
Membrane-based sorbent for heavy metal sequestration	10/31/00	Referenced
by 5 patents:

(1) 7,049,366 Acrylic acid composition and its production process, and
process for producing water-absorbent resin using this acrylic acid
composition, and water-absorbent resin 

(2) 7,009,010 Water-absorbent resin and production process therefor 

(3) 6,544,419 Method of preparing a composite polymer and silica-based
membrane 

(4) 6,544,418 Preparing and regenerating a composite polymer and
silica-based membrane 

(5) 6,306,301 Silica-based membrane sorbent for heavy metal
sequestration

6,306,301	Bhattacharyya D, Ritchie SM, Bachas LG, Hestekin JA, Sikdar SK
Silica-based membrane sorbent for heavy metal sequestration	10/23/01
Referenced by 2 patents:

(1) 6,544,419 Method of preparing a composite polymer and silica-based
membrane 

(2) 6,544,418 Preparing and regenerating a composite polymer and
silica-based membrane

6,434,943	Garris CA	Pressure exchanging compressor-expander and methods
of use	8/20/02	Referenced by 6 patents:

(1) 7,137,243 Constant volume combustor 

(2) 7,104,068 Turbine component with enhanced stagnation prevention and
corner heat distribution 

(3) RE39,217 Centrifugal pump having oil misting system with pivoting
blades 

(4) 6,663,991 Fuel cell pressurization system 

(5) 6,608,418 Permanent magnet turbo-generator having magnetic bearings 

(6) 6,551,055 Centrifugal pump having oil misting system with pivoting
blades

6,512,060	Matyjaszewski K, Gaynor SG, Coco S	Atom or group transfer
radical polymerization	1/28/03	Referenced by 15 patents:

(1) 7,422,836 Dissolution rate modifiers for photoresist compositions

(2) 7,332,550 Stabilization of transition metal complexes for catalysis
in diverse environments

(3) 7,244,788 Polymer and process for producing polymers

(4) 7,199,177 Pigment composition containing ATRP polymers

(5) 7,157,530 Catalyst system for controlled polymerization  

(6) 7,125,938 Atom or group transfer radical polymerization 

(7) 7,064,166 Process for monomer sequence control in polymerizations 

(8) 7,056,455 Process for the preparation of nanostructured materials 

(9) 7,049,373 Process for preparation of graft polymers 

(10) 7,019,082 Polymers, supersoft elastomers and methods for preparing
the same 

(11) 6,887,962 Processes based on atom (or group) transfer radical
polymerization and novel (co)polymers having useful structures and
properties 

(12) 6,790,919 Catalyst system for controlled polymerization 

(13) 6,759,491 Simultaneous reverse and normal initiation of ATRP 

(14) 6,720,395 Method for producing a stellar polymer 

(15) 6,627,314 Preparation of nanocomposite structures by controlled
polymerization

6,521,198	Yan YS, Cheng XL, Wang ZB	Metal surfaces coated with molecular
sieve for corrosion resistance	2/18/03	Referenced by 1 patent:

(1) 7,179,547 High aluminum zeolite coatings on corrodible metal
surfaces

6,538,091	Matyjaszewski K, Gaynor SG, Coco S	Atom or group transfer
radical polymerization	3/25/03	Referenced by 12 patents:

(1) 7,332,550 Stabilization of transition metal complexes for catalysis
in diverse environments

(2) 7,157,530 Catalyst system for controlled polymerization 

(3) 7,125,938 Atom or group transfer radical polymerization 

(4) 7,064,166 Process for monomer sequence control in polymerizations 

(5) 7,056,455 Process for the preparation of nanostructured materials 

(6) 7,049,373 Process for preparation of graft polymers 

(7) 7,034,065 Ink jet ink composition 

(8) 7,019,082 Polymers, supersoft elastomers and methods for preparing
the same 

(9) 6,887,962 Processes based on atom (or group) transfer radical
polymerization and novel (co)polymers having useful structures and
properties 

(10) 6,790,919 Catalyst system for controlled polymerization

(11) 6,759,491 Simultaneous reverse and normal initiation of ATRP 

(12) 6,713,530 Ink jet ink composition

6,541,580	Matyjaszewski K, Gaynor SG, Coco S	Atom or group transfer
radical polymerization	4/1/03	Referenced by 9 patents:

(1) 7,332,550 Stabilization of transition metal complexes for catalysis
in diverse environments

(2) 7,125,938 Atom or group transfer radical polymerization 

(3) 7,064,166 Process for monomer sequence control in polymerizations 

(4) 7,056,455 Process for the preparation of nanostructured materials 

(5) 7,049,373 Process for preparation of graft polymers 

(6) 6,887,962 Processes based on atom (or group) transfer radical
polymerization and novel (co)polymers having useful structures and
properties 

(7) 6,884,748 Process for producing fluorinated catalysts 

(8) 6,790,919 Catalyst system for controlled polymerization 

(9) 6,759,491 Simultaneous reverse and normal initiation of ATRP

6,544,418	Bhattacharyya D, Ritchie SM, Bachas LG, Hestekin JA, Sikdar SK
Preparing and regenerating a composite polymer and silica-based membrane
4/8/03	Referenced by 0 patents

6,544,419	Bhattacharyya D, Ritchie SM, Bachas LG, Hestekin JA, Sikdar SK
Method of preparing a composite polymer and silica-based membrane	4/8/03
Referenced by 0 patents

6,562,605	Beckman EJ, Ghenciu EJ, Becker NT, Steele LM	Extraction of
water soluble biomaterials from fluids using a carbon dioxide/surfactant
mixture	5/13/03	Referenced by 0 patents

6,624,262	Matyjaszewski K, Tsarevsky N	Polymerization process for ionic
monomers	9/23/03	Referenced by 11 patents:

(1) 7,332,550 Stabilization of transition metal complexes for catalysis
in divers environments

(2) 7,300,991 Cationic conductor, its intermediate, and lithium
secondary battery using the conductor

(3) 7,157,530 Catalyst system for controlled polymerization 

(4) 7,125,938 Atom or group transfer radical polymerization 

(5) 7,064,166 Process for monomer sequence control in polymerizations 

(6) 7,056,455 Process for the preparation of nanostructured materials 

(7) 7,049,373 Process for preparation of graft polymers 

(8) 7,019,082 Polymers, supersoft elastomers and methods for preparing
the same 

(9) 6,887,962 Processes based on atom (or group) transfer radical
polymerization and novel (co)polymers having useful structures and
properties 

(10) 6,790,919 Catalyst system for controlled polymerization 

(11) 6,759,491 Simultaneous reverse and normal initiation of ATRP

6,624,263	Matyjaszewski K, Wang JS	(Co) polymers and a novel
polymerization process based on atom (or group) transfer radical
polymerization	9/23/03	Referenced by 9 patents:

(1) 7,157,530 Catalyst system for controlled polymerization

(2) 7,125,938 Atom or group transfer radical polymerization 

(3) 7,064,166 Process for monomer sequence control in polymerizations 

(4) 7,056,455 Process for the preparation of nanostructured materials 

(5) 7,049,373 Process for preparation of graft polymers 

(6) 7,019,082 Polymers, supersoft elastomers and methods for preparing
the same 

(7) 6,887,962 Processes based on atom (or group) transfer radical
polymerization and novel (co)polymers having useful structures and
properties 

(8) 6,790,919 Catalyst system for controlled polymerization 

(9) 6,759,491 Simultaneous reverse and normal initiation of ATRP

6,627,314	Matyjaszewski K, Pyun J	Preparation of nanocomposite
structures by controlled polymerization	9/30/03	Referenced by 13
patents:

(1) 7,332,550 Stabilization of transition metal complexes for catalysis
in diverse environments

(2) 7,217,457 Composite particles, derived conjugates, preparation
method and applications

(3) 7,157,530 Catalyst system for controlled polymerization 

(4) 7,125,938 Atom or group transfer radical polymerization 

(5) 7,064,166 Process for monomer sequence control in polymerizations 

(6) 7,056,455 Process for the preparation of nanostructured materials 

(7) 7,049,373 Process for preparation of graft polymers 

(8) 7,019,082 Polymers, supersoft elastomers and methods for preparing
the same 

(9) 6,887,962 Processes based on atom (or group) transfer radical
polymerization and novel (co)polymers having useful structures and
properties 

(10) 6,858,372 Resist composition with enhanced X-ray and electron
sensitivity 

(11) 6,797,380 Nanoparticle having an inorganic core 

(12) 6,790,919 Catalyst system for controlled polymerization 

(13) 6,759,491 Simultaneous reverse and normal initiation of ATRP

6,663,991	Garris CA	Fuel cell pressurization system	12/16/03	Referenced
by 0 patents

6,755,975	Vane LM, Mairal AP, Ng A, Alvarez FR, Baker RW	Separation
process using pervaporation and dephlegmation	6/29/04	Referenced by 1
patent:

(1) 6,899,743 Separation of organic mixtures using gas separation or
pervaporation and dephlegmation

6,759,491	Matyjaszewski K, Gromada J, Li M	Simultaneous reverse and
normal initiation of ATRP	7/6/04	Referenced by 0 patents

6,777,374	Sahle-Demessie E, Biswas P, Gonzalez MA, Wang Z-M, Sikdar SK
Process for photo-induced selective oxidation of organic chemicals to
alcohols, ketones and aldehydes using flame deposited nano-structured
photocatalyst	8/17/04	Referenced by 0 patents

6,881,364	Vane LM, Ponangi RP	Hydrophilic mixed matrix materials having
reversible water absorbing properties	4/19/05	Referenced by 0 patents

6,900,261	Wool RP, Lu J, Khot SN	Sheet molding compound 

resins from plant oils	5/31/05	Referenced by 0 patents

7,019,082	Matyjaszewski K, Pakula T	Polymers, supersoft elastomers and
methods for preparing the same	3/28/06	Referenced by 0 patents

7,179,547	Yan YS, Beving D	High aluminum zeolite coatings on corrodible
metal surfaces	2/20/07	Reference by 0 patents

7,332,500	Matyjaszewski K, Tsarevsky N	Stabilization of transition metal
complexes for catalysis in diverse environments	2/19/08	Referenced by 0
patents

7,442,352	Lu X-C, Wu X	Flue gas purification process using a sorbent
polymer composite material	10/28/08	Referenced by 0 patents

WO 2007/109300 A2	Dilek C, Gulari E, Manke CW, Marentis RT	Recyclable
binders for metal casting molds and for injection molding of metal and
ceramic parts	9/27/07	Referenced by 0 patents

Application No. 20040044152	Matyjaszewski K, Tsarevsky N	Polymerization
processes for ionic monomers	3/4/04	Not applicable

Application No.: 2005090632	Matyjaszewski K, Wang JS	Novel (co)polymers
and a novel polymerization process based on atom (or group) transfer
radical polymerization	4/28/05	Not applicable

Application No.: 20070056911	Zhao DY, An B	Selective removal of toxic
compounds like arsenic from drinking water	3/15/07	Not applicable



	1	Thomson Reuter’s Web of Science provides access to current and
retrospective multidisciplinary information from approximately 8,830 of
the most prestigious, high impact research journals in the world. Web of
Science also provides cited reference searching. 

 	Scopus is a large abstract and citation database of research
literature and quality Web sources designed to support the literature
research process. Scopus offers access to 15,000 titles from 4,000
different publishers, more than 12,850 academic journals (including
coverage of 535 Open Access journals, 750 conference proceedings, and
600 trade publications), 27 million abstracts, 245 million references,
200 million scientific Web pages, and 13 million patent records.  

 	Garfield E, Sher IH.  New factors in the evaluation of scientific
literature through citation indexing.  American Documentation
1963;18(July):195-210.

 	MacRoberts MH, MacRoberts BR.  Problems of citation analysis: a
critical review.  Journal of the American Society of Information Science
1989;40(5):342-349.

 	Kavaci N, Misak A.  Author self-citation in medical literature. 
Canadian Medical Association Journal 2004;170(13):1929-1930.

Bibliometric Analysis of STS Research Program Journal
Articles—February 2009

  PAGE  2 

February 2009

  PAGE  1 

Bibliometric Analysis of STS Research Program Journal
Articles—February 2009

Summary of Results

More than one-quarter of the STS publications are highly cited papers. 
A review of the citations indicates that 225 (28.3%) of the STS papers
qualify as highly cited when using the ESI criteria for the top 10% of
highly cited publications.  This is 2.8 times the number expected. 
Thirty-five (4.4%) of the STS papers qualify as highly cited when using
the ESI criteria for the top 1%, which is 4.4 times the number expected.
 Seven (1.0%) of these papers qualify as very highly cited when using
the criteria for the top 0.1%, which is 10 times the number anticipated.
 One paper (0.1%) actually meets the 0.01% threshold for the most highly
cited papers, which is more than 10 times the 0.08 number expected.

The STS papers are more highly cited than the average paper.  Using the
ESI average citation rates for papers published by field as the
benchmark, in 13 of the 19 fields in which the EPA STS papers were
published, the ratio of actual to expected cites is greater than 1,
indicating that the STS papers are more highly cited than the average
papers in those fields. For all 19 fields combined, the ratio of total
number of cites to the total number of expected cites (18,684 to 8,029)
is 2.3, indicating that the STS papers are more highly cited than the
average paper. 

More than one-third of the STS papers are published in high impact
journals.  Two hundred eight-one (281) of the 794 papers were published
in the top 10% of journals ranked by JCR Impact Factor, representing
35.4% of EPA’s STS papers. This number is 3.5 times higher than
expected. Two hundred seventy-five (275) of the 794 papers appear in the
top 10% of journals ranked by JCR Immediacy Index, representing 34.6% of
EPA’s STS papers. This number is 3.5 times higher than expected.

Eleven of the STS papers qualify as hot papers.  Using the hot paper
thresholds established by ESI as a benchmark, 11 hot papers,
representing 1.4% of the STS papers, were identified in the analysis. 
Hot papers are papers that were highly cited shortly after they were
published. The number of STS hot papers is 14 times higher than the 0.8
hot papers expected.

The authors of the STS papers cite themselves much less than the average
author.  Six hundred fifty-eight (658) of the 18,684 cites are author
self-cites. This 3.5% author self-citation rate is well below the
accepted range of 10-30% author self-citation rate.

Thirteen of the authors of the STS papers are included in
ISIHighlyCited.com, which is a database of the world’s most
influential researchers who have made key contributions to science and
technology during the period from 1981 to 1999.

The 71 nonjournal publications were cited 1,637 times in journals.  34
(47.9%) were cited at least once in a journal and the authors cited
themselves 17 times (1.0% self-citation rate), which is much less than
the literature-reported 10-30% range for author self-citation.  6 (8.4%)
of the nonjournal publications were highly cited when using the ESI
criteria for the top 10% of highly cited publications. Three (4.2%) of
the nonjournal publications met the ESI threshold for the top 1%, and 1
(1.4%) publication met the ESI threshold for the top 0.1%.  These
numbers are 4 and 14 times higher than expected.  None of the nonjournal
publications met the ESI threshold for the top 0.01%.

8.	There were 30 patents (29 U.S. and 1 international) issued and 3
patent applications filed by investigators from 1998 to 2008 for
research that was conducted under EPA’s STS research program.
Seventeen (59%) of the 29 U.S. patents have been referenced 115 times by
other patents.  

This bibliometric analysis was prepared by

Beverly Campbell of The Scientific Consulting Group, Inc.

in Gaithersburg, Maryland

 under EPA Contract No.   SEQ CHAPTER \h \r 1 EP-C-05-015

