Proceedings of the California Academy of Sciences.

ser. 1 v. 2 (1858-1862)

Occasional papers of the California Academy of Sciences.

no. 106 (1973)

Occasional papers of the California Academy of Sciences.

no. 109 (1974)

Internationalising the Curriculum of International Relations

Peer reviewed

Structural Alterations of Lignins in Transgenic Poplars with Depressed Cinnamyl Alcohol Dehydrogenase or Caffeic Acid O-Methyltransferase Activity Have an Opposite Impact on the Efficiency of Industrial Kraft Pulping1

We evaluated lignin profiles and pulping performances of 2-year-old transgenic poplar (Populus tremula × Populus alba) lines severely altered in the expression of caffeic acid/5-hydroxyferulic acid O-methyltransferase (COMT) or cinnamyl alcohol dehydrogenase (CAD). Transgenic poplars with CAD or COMT antisense constructs showed growth similar to control trees. CAD down-regulated poplars displayed a red coloration mainly in the outer xylem. A 90% lower COMT activity did not change lignin content but dramatically increased the frequency of guaiacyl units and resistant biphenyl linkages in lignin. This alteration severely lowered the efficiency of kraft pulping. The Klason lignin level of CAD-transformed poplars was slightly lower than that of the control. Whereas CAD down-regulation did not change the frequency of labile ether bonds or guaiacyl units in lignin, it increased the proportion of syringaldehyde and diarylpropane structures and, more importantly with regard to kraft pulping, of free phenolic groups in lignin. In the most depressed line, ASCAD21, a substantially higher content in free phenolic units facilitated lignin solubilization and fragmentation during kraft pulping. These results point the way to genetic modification of lignin structure to improve wood quality for the pulp industry.

Blending of industrial waste from different sources as partial substitution of Portland cement in pastes and mortars

Binary and ternary combinations of sewage sludge ash (SSA) with marble dust (MD), fly ash (FA) and rice husk ash (RHA) as replacement in Portland cement pastes, were assessed. Several tests were carried out at different curing ages: thermogravimetry, density, water absorption, ultrasonic pulse velocity and mechanical strengths. Pozzolanic effects of the mineral admixtures, densities similar to control sample and improved absorptions when combining waste materials were identified. In general, the compressive strength reaches or exceeds the cement strength class, and blending SSA, FA and RHA (30% cement replacement) increase of strength by 9%, compared to the control sample, was achieved.

Bulletin of the Southern California Academy of Sciences.

v.12-15 (1913-1916)

Bulletin of the Southern California Academy of Sciences.

v.8-11 (1909-1912)

Occasional papers of the California Academy of Sciences.

no. 111 (1974)

Proceedings of the California Academy of Sciences.

2

Coffee / by B. E. Dahlgren, Chief Curator, Dept. of Botany.

no.22(1938)

Common trees / by J. Francis Macbride, Asst. Curator, Taxonomy, Dept. of Botany.

no.11(1936)

A classification of the Conularida / G. Winston Sinclair, Dept. of Geology, University of Michigan.

v.10:no.13(1952)

An early archaeological example of tattooing from northwestern Alaska / James W. VanStone, Curator, North American Archaeology and Ethnology, Field Museum of Natural History, and Charles V. Lucier, Alaska Dept. of Fish and Game.

v.66:no.1(1974)

A forest of the coal age / by B. E. Dahlgren, Acting Curator, Dept. of Botany.

no.14(1933)