EPA ANALYSIS CALLED FAULTY
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NEWS OF THE WEEK AIR POLLUTION EPA ANALYSIS CALLED FAULTY Congressional researchers say agency's methods skewed toward Bush emission plan Ε PAS RECENT ANALYSIS OF legislation to cut utilities' air pollution is improperly tilted in favor of President George W. Bush's Clear Skies initiative, accord- DIBLOCK Copolymer consists of pH-sensitive methacrylate block (right) and block with biomimetic phosphorylcholine motif (left). ^SV^fe ing to the nonpartisan Congressio- nal Research Service (CRS). Three competing legislative plans in the Senate would trim sulfur dioxide, nitrogen oxide, and mercury emissions from utility smokestacks. Bush's Clear Skies involves the smallest reductions. Legislation sponsored by Sen. Thomas R. Carper (D-DeL) would make deeper cuts than the Bush plan, while a bill by Sen. James M. Jeffords (I-Vt.) proposes the most stringent emission controls. The Carper andJeffords bills also would curb carbon dioxide releases. EPA's analysis was faulty for a number of reasons, CRS says in a Nov. 23 report. One is that the agency assumed that only congres- sional passage of legislation would cut utility emissions, the report says. This ignores the effects of two rules EPA issued earlier this year—one to reduce sulfur diox- ide and nitrogen oxides, the other to control mercury from power plants (C&EN, March 21, page 11). Together, the EPA rules offer emission reductions similar to the Clear Skies plan. The CRS report took the two EPA rules into account and found that Clear Skies would cost little to implement and would offer small benefits. '"TheJeffords and Carper bills, however, set more stringent standards than the promulgat- ed rules," the CRS report says. It finds that the benefits of each of those bills far outweigh the additional costs they would im- pose.—CHERYL HOGUE POLYMER CHEMISTRY BIOCOMPATIBLE POLYMER VESICLES "0 —P=0 | I — N— A NEW CLASS OF PH-SENSITIVE polymer vesicles formed from diblock copolymers could potentially be used as nanosized B r drue- and protein-de- 120-160 ι. ι Λ ι 0 liveryvehicles, accord- Q ing to the researchers in England who syn- thesized the materi- als (J. Am. Chem. Soc., published online Dec. 1, dx.doi.org/10.1021/ ja0565141). "Unlike many lit- erature examples of block copolymer ves- icles, our diblock co- polymers can be read- 'N + Cr ily synthesized in high yields from commercially available monomers by atom transfer radical polymer- ization in methanol at room tem- perature without using protecting group chemistry," says University of Sheffield chemistry professor Steven P. Armes. He carried out the work with Andrew L. Lewis, research & technology director of Biocompatibles, based in Farnham, U.K., and coworkers. The vesicles are composed of an AB diblock copolymer in which the A block is based on a highly biocompatible zwitterionic mono- mer that contains the biomimetic phosphorylcholine motif. The Β block is based on a pH-responsive tertiary amine methacrylate mono- mer. The copolymer dissolves in aqueous acidic solution and self-as- sembles into well-defined vesicles above pH 7. The vesicles dissociate completely below pH 6. "The phosphorylcholine mo- tif makes the polymers the most authentic polymeric analogs of conventional liposomes reported to date," Armes notes. The team also showed that the water-soluble anticancer drug doxorubicin can be encapsulated in the vesicles and released slowly over a period of several hours. "This cleverly designed system is readily prepared through the powerful technique of copper-cata- lyzed, controlled radical polymer- ization," comments Ian Manners, chemistry professor at the Univer- sity ofToronto. "The results on the anticancer drug release demon- strate proof of concept, and, bear- ing in mind the ease of synthesis, the materials look very promising with respect to further develop- ment for controlled-release applica- tions."—MICHAEL FREEMANTLE 8 C&EN / DECEMBER 12, 2005 WWW.CEN-0NLINE.ORG
Transcript of EPA ANALYSIS CALLED FAULTY
NEWS OF THE WEEK
A I R P O L L U T I O N
EPA ANALYSIS CALLED FAULTY Congressional researchers say agency's methods skewed toward Bush emission plan
Ε PAS RECENT ANALYSIS OF legislation to cut utilities' air pollution is improperly tilted
in favor of President George W. Bush's Clear Skies initiative, accord-
DIBLOCK Copolymer consists of pH-sensitive methacrylate block (right) and block with biomimetic phosphorylcholine motif (left).
^SV^fe
ing to the nonpartisan Congressional Research Service (CRS).
Three competing legislative plans in the Senate would trim sulfur dioxide, nitrogen oxide, and mercury emissions from utility smokestacks. Bush's Clear Skies involves the smallest reductions. Legislat ion sponsored by Sen. Thomas R. Carper (D-DeL) would make deeper cuts than the Bush plan, while a bill by Sen. James M. Jeffords (I-Vt.) proposes the most stringent emission controls. The Carper and Jeffords bills also would curb carbon dioxide releases.
EPA's analysis was faulty for a number of reasons, CRS says in a Nov. 23 report. One is that the agency assumed that only congressional passage of legislation would cut utility emissions, the report says. This ignores the effects of two rules EPA issued earlier this year—one to reduce sulfur dioxide and nitrogen oxides, the other to control mercury from power plants (C&EN, March 21, page 11). Together, the EPA rules offer emission reductions similar to the Clear Skies plan.
The CRS report took the two EPA rules into account and found that Clear Skies would cost little to implement and would offer small benefits. '"TheJeffords and Carper bills, however, set more stringent standards than the promulgated rules," the CRS report says. It finds that the benefits of each of those bills far outweigh the additional costs they would impose.—CHERYL HOGUE
P O L Y M E R C H E M I S T R Y
BIOCOMPATIBLE POLYMER VESICLES
"0 —P=0 | I
— N—
A NEW CLASS OF PH-SENSITIVE polymer vesicles formed from diblock copolymers
could potentially be used as nanosized
B r drue- and protein-de-120-160 ι . ι Λ ι
0 livery vehicles, accord-Q ing to the researchers
in England who synthesized the materials (J. Am. Chem. Soc., published online Dec. 1, dx.doi.org/10.1021/ ja0565141).
"Unlike many literature examples of block copolymer vesicles, our diblock copolymers can be read-
'N + Cr
ily synthesized in high yields from commercially available monomers by atom transfer radical polymerization in methanol at room temperature without using protecting group chemistry," says University of Sheffield chemistry professor Steven P. Armes. H e carried out the work with Andrew L. Lewis, research & technology director of Biocompatibles, based in Farnham, U.K., and coworkers.
The vesicles are composed of an A B diblock copolymer in which the A block is based on a highly biocompatible zwitterionic monomer that contains the biomimetic phosphorylcholine motif. The Β block is based on a pH-responsive
tertiary amine methacrylate monomer. The copolymer dissolves in aqueous acidic solution and self-assembles into well-defined vesicles above pH 7. The vesicles dissociate completely below p H 6.
"The phosphorylcholine motif makes the polymers the most authentic polymeric analogs of conventional liposomes reported to date," Armes notes.
T h e t eam also showed that the water-soluble anticancer drug doxorubicin can be encapsulated in the vesicles and released slowly over a period of several hours.
"This cleverly designed system is readily prepared through the powerful technique of copper-catalyzed, controlled radical polymerization," comments Ian Manners, chemistry professor at the University of Toronto. "The results on the anticancer drug release demonstrate proof of concept, and, bearing in mind the ease of synthesis, the materials look very promising with respect to further development for controlled-release applications."—MICHAEL FREEMANTLE
8 C & E N / D E C E M B E R 1 2 , 2 0 0 5 W W W . C E N - 0 N L I N E . O R G
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