Irrigation, fertilization and initial substrate quality effects on decomposing Loblolly pine litter chemistry

Little is known about fine root decomposition during the freeze–thaw season. To characterize fine root decomposition during this time (from October 2006 to April 2007), a field experiment was conducted to examine the decomposition of fine roots (diameters of 0–1 and 1–2 mm) of Minjiang fir ( Abies faxoniana Rehd. & E.H. Wilson) and Asian white birch ( Betula platyphylla Sukaczev) using buried litterbags in their respective habitats in western Sichuan, China. Over one freeze–thaw season, 14%–20% of mass was lost and 12%–31% of C, 6%–36% of N, 15%–25% of P, and 37%–43% of K were released. These losses accounted for about 40%–55% of mass lost and 23%–54% of C, 23%–89% of N, 25%–42% of P, and 48%–58% of K released within the first year of fine root decomposition. The amount of mass loss and bioelements release during the freeze–thaw season correlated closely with initial substrate quality and bioelement traits. Compared with birch fine root, fir fine root decomposition could be influenced more by decomposition processes during the freeze–thaw season. Results suggest that fine root decomposition during the freeze–thaw season can strongly contribute to ecosystem C and nutrient cycling.

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Effects of substrate quality and annealing on defect structures at GaAs/Si interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126494 ◽

1987 ◽

Vol 45 ◽

pp. 340-341

Author(s):

H. L. Tsai ◽

J. W. Lee

Keyword(s):

Growth Process ◽

Molecular Beam ◽

Substrate Surface ◽

Lattice Misfit ◽

Device Fabrication ◽

Silicon Substrates ◽

Defect Structures ◽

Gaas Film ◽

Substrate Quality ◽

Gaas On Si

Growth of GaAs on Si using epitaxial techniques has been receiving considerable attention for its potential application in device fabrication. However, because of the 4% lattice misfit between GaAs and Si, defect generation at the GaAs/Si interface and its propagation to the top portion of the GaAs film occur during the growth process. The performance of a device fabricated in the GaAs-on-Si film can be degraded because of the presence of these defects. This paper describes a HREM study of the effects of both the substrate surface quality and postannealing on the defect propagation and elimination.The silicon substrates used for this work were 3-4 degrees off [100] orientation. GaAs was grown on the silicon substrate by molecular beam epitaxy (MBE).

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Polysulfide-borohydride modification of southern pine alkaline pulping integrated with hydrothermal pre-extraction of hemicelluloses

TAPPI Journal ◽

10.32964/tj10.7.9 ◽

2011 ◽

Vol 10 (7) ◽

pp. 9-16

Author(s):

SUNG-HOON YOON ◽

HARRY CULLINAN ◽

GOPAL A. KRISHNAGOPALAN

Keyword(s):

Loblolly Pine ◽

Sodium Borohydride ◽

Kraft Pulping ◽

Hot Water ◽

Pulp Yield ◽

Paper Strength ◽

Southern Pine ◽

Two Stage ◽

Simultaneous Treatment ◽

Process Modification

We studied three process modifications to investigate their effects on the property and yield recovery capabilities of kraft pulping integrated with hemicellulose pre-extraction of southern pine. Loblolly pine chips were pre-extracted with hot water until the sugar extraction yield reached the targeted value of 10% and then subjected to conventional and modified kraft pulping. Modification included polysulfide pretreatment; polysulfide-sodium borohydride dual pretreatment, and polysulfide followed by polysulfide-sodium borohydride dual pretreatment two-stage pretreatments prior to kraft pulping. In the first modification, about 5% of the lost pulp yield (total 7%) caused by hemicellulose pre-extraction could be recovered with 15%-20% polysulfide pretreatment. Complete recovery (7%) was achieved with simultaneous pretreatment using 15% polysulfide and 0.5% sodium borohydride with 0.1% anthraquinone in polysulfide-sodium borohydride dual pretreatment. Two-stage pretreatment using recycled 15% polysulfide followed by simultaneous treatment of 6% polysulfide and 0.4%–0.5% sodium borohydride with 0.1% anthraquinone also achieved 100% yield recovery. Continuous recycling of 15% polysulfide employed in the two-stage process modification maintained its yield protection efficiency in a repeated recycling cycle. No significant changes in paper strength were found in handsheets prepared from the three process modifications, except for a minor reduction in tear strength.

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