bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain growth in nanocomposite Ti–B–N films during deposition: The effect of amorphous phase precipitation
Authors: Liu Z-J. , Lu Y.H. , Shen Y.G.
Published: January 2006

Experimental investigations by high-resolution transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction show that during sputter-deposition of Ti–B–N films amorphous materials, e.g., TiB2 and BN, are found to precipitate at the grain boundaries, resulting in a decrease in grain size when the boron concentration or the amount of amorphous phase increases. To understand these experimental observations, we have used Monte Carlo simulations to investigate the effect of the amorphous phase precipitation on grain growth during film deposition. Our simulations demonstrate that the precipitation of amorphous phase at the grain boundaries can lower the grain growth exponent and thus leads to a low grain growth rate, particularly in the case of large amounts of amorphous phase. As a result, an exponential decay in grain size with the amount of amorphous phase can be observed in our simulations, which is in reasonably good agreement with the experimental results.
Ion beam assisted deposition of textured magnesium oxide templates on un-buffered glass and silicon substrates
Authors: Vallejo Ronald N. , Wu Judy Z.
Published: January 2006

Biaxially textured magnesium oxide (MgO) templates of 10-nm thickness were successfully fabricated on glass and silicon substrates without any buffer layers using Ar+ ion beam assisted e-beam evaporation. With an additional layer of 100 nm homoepi MgO on top, the in-plane misorientation of ∼6.5° and out-of-plane misorientation of ∼2.0° have been obtained. Prior to growth, the substrates were bombarded with the same Ar+ ion beam for a certain period ranging from 5 to 35 min to provide initial substrate conditions for textured MgO formation. The ion beam induced modification of the substrate surface morphology was characterized using atomic force microscopy. Reduced surface roughness Ra from 2 to 3 nm on the original glass substrates to below 1.0 nm after 5 min ion beam bombardment was found to be an important condition for the textured MgO formation. The nearly unchanged Ra ≤ 1 nm of the silicon substrate after the ion beam bombardment, however, suggests that additional surface modification is required for the textured MgO to form.
Study of copper-refractory metal interfaces via solid-state wetting for emerging nanoscale interconnect applications
Authors: van der Straten Oscar , Zhu Yu , Rullan Jonathan , Dunn Kathleen , Kaloyeros Alain E.
Published: January 2006

Solid-state wetting experiments were carried out to derive the work of adhesion (adhesion energy) of pertinent Cu/liner interfaces via the Young–Dupré equation using contact-angle measurements of the Cu equilibrium crystal shape on Ta and TaNx liners. Four types of liner surfaces were examined: untreated sputtered Ta (uSp-Ta), untreated sputtered TaNx (uSp-TaN), untreated atomic layer deposited (ALD) TaNx (uALD-TaN), and indium surfactant-treated ALD TaNx (tALD-TaN). All Cu-liner stacks were subsequently annealed at 600 °C for 48 h in a forming gas (95% Ar/5% H2) ambient. For Cu/uSp-Ta, the work of adhesion was found to be 2170 mJ/m2, corresponding to an average contact angle of 74°, while for Cu/uSp-TaN, the work of adhesion amounted to 1850 mJ/m2 for an average contact angle of 85°. Alternatively, the work of adhesion for Cu/uALD-TaN was determined to be 1850 mJ/m2, corresponding to an average contact angle of 85°, while for Cu/tALD-TaN, the work of adhesion was 2280 mJ/m2, at an average contact angle of 70°. These findings indicate that the highest degree of surface wetting occurs for the indium surfactant-treated ALD TaNx. It is thus suggested that surfactant treatment causes a reduction in the energy barrier to Cu nucleation, resulting in an enhancement in Cu wetting characteristics and a more uniform concentration of Cu nucleation sites. A critical potential outcome is the formation of atomically smooth Cu-liner interfaces with enhanced adhesion characteristics.
An Evaluation of the Effect of Treatments for Pond Water Reuse on Zooplankton Populations
Authors: Frimpong Emmanuel A , Lochmann Steve E
Published: January 2006

Reuse of pond water is becoming more common in the culture of baitfish and hybrid striped bass (female white bass Morone chrysops × male striped bass M. saxatilis). Water conservation is important because of declining aquifer levels and increasing demand for groundwater. One challenge to this practice is the presence of predaceous copepods in pond water held from previous production operations (old water), which results in variable larval fish survival and fingerling production. This study evaluated methods of restarting zooplankton succession in old water. The concentrations of cladocerans, adult copepods, copepod nauplii, and rotifers from untreated old water, chemically treated old water (0.25 mg of the active ingredient Dylox per liter), mechanically treated old water (i.e., water filtered through a 60-μm screen with a drum filter), and ponds filled with new well water were compared. All ponds were fertilized twice a week with cottonseed meal and inorganic liquid fertilizer (10:30 [N:P]). Ponds with chemically treated old water had significantly more copepods than those subjected to the other three treatments. Ponds with mechanically treated old water had the highest bloom concentration of copepod nauplii. Ponds with chemically treated old water and mechanically treated old water had more rotifers than ponds with new well water or ponds with untreated old water. Mechanical filtration improved old water most in terms of both increased rotifer concentrations and reduced adult copepod concentrations within the first 2 weeks of pond treatment. Treating with mechanical filtration should be considered as an alternative to treatment with Dylox.
Cryopreservation of Semen from Lake Sturgeon
Authors: Ciereszko Andrzej , Dabrowski Konrad , Froschauer Julia , Wolfe Tobie D.
Published: January 2006

Lake sturgeon Acipenser fulvescens, once abundant and the only species of sturgeon endemic to the North American Great Lakes, is now rare and threatened with extinction as a result of overfishing and habitat destruction. Sperm cryopreservation can be useful for preserving the genetic variability of local populations of lake sturgeon. In this study, we show the conditions of extended storage of unfertilized gametes and successful cryopreservation of lake sturgeon semen using methanol as a cryoprotectant. We demonstrate that unfertilized eggs can be transported for 8–12 h, provided that their initial quality is good. Our results indicate that cryopreservation of lake sturgeon milt caused increased damage to sperm DNA (measured by comet assay); however, some spermatozoa maintained their fertilizing ability. Fertilization with cryopreserved semen caused an 87% reduction in postthaw fertilization rates of prehatched larvae compared with control fertilizations with fresh semen.
Regulation of the vascular endothelial growth factor (VEGF) receptor Flk-1/KDR by estradiol through VEGF in uterus
Authors: Hervé M A J , Meduri G , Petit F G , Domet T S , Lazennec G , Mourah S , Perrot-Applanat M
Published: January 2006

The induction of vascular endothelial growth factor (VEGF) expression by 17β-estradiol (E2) in many target cells, including epithelial cells, fibroblasts and smooth muscle cells, suggests a role for this hormone in the modulation of angiogenesis and vascular permeability. We have already described a cyclic increase in Flk-1/KDR-expressing capillaries in the human endometrium during the proliferative and mid-secretory phases, strongly suggestive of an E2 effect on Flk-1/KDR expression in the endometrial capillaries. However, it is unclear whether these processes are due to a direct effect of E2 on endothelial cells. Using immunohistochemistry, we report an increase in Flk-1/KDR expression in endometrial capillaries of ovariectomized mice treated with E2, or both E2 and progesterone. This process is mediated through estrogen receptor (ER) activation. In vitro experiments using quantitative RT-PCR analysis demonstrate that Flk-1/KDR expression was not regulated by E2 in human endothelial cells from the microcirculation (HMEC-1) or macrocirculation (HUVEC), even in endothelial cells overexpressing ERα or ERβ after ER-mediated adenovirus infection. In contrast, Flk-1/KDR expression was up-regulated by VEGF itself, in a time- and dose-dependent manner, with the maximal response at 10 ng/ml. Thus, we suggest that E2 up-regulates Flk-1/KDR expression in vivo in endothelial cells mainly through the modulation of VEGF by a paracrine mechanism. It is currently unknown whether or not the endothelial origin might account for differences in the E2-modulation of VEGF receptor expression, particularly in relation to the vascular bed of sex steroid-responsive tissues.
Impaired cardiac contractile function in ventricular myocytes from leptin-deficient ob/ob obese mice
Authors: Dong F , Zhang X , Yang X , Esberg L B , Yang H , Zhang Z , Culver B , Ren J
Published: January 2006

The level of the obese gene product leptin is often positively correlated with body weight, supporting the notion that hyperleptinemia contributes to obesity-associated cardiac dysfunction. However, a link between leptin levels and cardiac function has not been elucidated. This study was designed to examine the role of leptin deficiency (resulting from a point mutation of the leptin gene) in cardiomyocyte contractile function. Mechanical properties and intracellular Ca2 + transients were evaluated in ventricular myocytes from lean control and leptin-deficient ob/ob obese mice at 12 weeks of age. Cardiac ultrastructure was evaluated using transmission electron microscopy. ob/ob mice were overtly obese, hyperinsulinemic, hypertriglycemic, hypoleptinemic and euglycemic. Ultrastructural examination revealed swelling and disorganization of cristae in mitochondria from ob/ob mouse ventricular tissues. Cardiomyocytes from ob/ob mice displayed reduced expression of the leptin receptor Ob-R, larger cross-sectional area, decreased peak shortening and maximal velocity of shortening/relengthening, and prolonged relengthening but not shortening duration compared with lean counterparts. Consistent with mechanical characteristics, myocytes from ob/ob mice displayed reduced intracellular Ca2 + release upon electrical stimulus associated with a slowed intracellular Ca2 + decay rate. Interestingly, the contractile aberrations seen in ob/ob myocytes were significantly improved by in vitro leptin incubation. Contractile dysfunction was not seen in age- and gender-matched high fat-induced obese mice. These results suggested that leptin deficiency contributes to cardiac contractile dysfunction characterized by both systolic and diastolic dysfunction, impaired intracellular Ca2 + hemostasis and ultrastructural derangement in ventricular myocytes.
Skin secretions of Rana saharica frogs reveal antimicrobial peptides esculentins-1 and -1B and brevinins-1E and -2EC with novel insulin releasing activity
Authors: Marenah L , Flatt P R , Orr D F , Shaw C , Abdel-Wahab Y H A
Published: January 2006

Skin secretions of Rana saharica were evaluated for the isolation and characterisation of novel insulinotropic peptides. Crude secretions obtained from young adult frogs by mild electrical stimulation of the dorsal skin surface were purified by reverse phase HPLC yielding 80 fractions. In acute 20-min incubations with glucose responsive BRIN-BD11 cells, fractions 36–43, 46–54 and 57–63 significantly stimulated insulin release by 2- to 8-fold compared with 5.6 mM glucose alone. Pooled fractions in the latter two bands were rechromatographed to reveal 9 homogenous peaks, which elicited significant 1.3- to 3.5-fold increases in insulin release (P < 0.05). Structural analysis of the most potent non-toxic peptides was performed by mass spectrometry and automated Edman degradation. This revealed four major insulin-releasing peaks with molecular masses of 2676.9 Da, 3519.3 Da, 4920.4 Da and 4801.2 Da respectively. These peptides were found to be identical to brevinin-1E, brevinin-2EC, esculentin-1 and esculentin-1B, which belong to the group of antimicrobial peptides isolated from skin secretions of various Rana frog species. Preliminary studies on the mechanism underlying the insulinotropic actions of esculentins-1 and -1B suggested possible involvement of both cyclic AMP–protein kinase A and –C-dependent G-protein sensitive pathways. These data indicate that the skin secretions of Rana saharica frogs contain bioactive molecules with significant insulin-releasing activity. Relatives of the brevinin/esculentin peptide family merit further investigation as novel insulin secretagogues.
Inhibition of glycogen synthesis by increased lipid availability is associated with subcellular redistribution of glycogen synthase
Authors: Taylor A J , Ye J-M , Schmitz-Peiffer C
Published: January 2006

Increased lipid availability is associated with diminished insulin-stimulated glucose uptake and glycogen synthesis in muscle, but it is not clear whether alterations in glycogen synthase activity itself play a direct role. Because intracellular localization of this enzyme is involved in its regulation, we investigated whether fat oversupply causes an inhibitory redistribution. We examined the recovery of glycogen synthase in subcellular fractions from muscle of insulin-resistant, fat-fed rats and chow-fed controls, either maintained in the basal state or after a euglycaemic-hyperinsulinaemic clamp. Although glycogen synthase protein and activity were mostly recovered in an insoluble fraction, insulin caused translocation of activity from the smaller soluble pool to the insoluble fraction. Fat-feeding, which led to a reduction in glycogen synthesis during the clamp, was associated with a depletion in the soluble pool, consistent with an important role for this component. A similar depletion was also observed in cytosolic fractions of muscles from obese db/db mice, another model of lipid-induced insulin resistance. To investigate this in more detail, we employed lipid-pretreated L6 myotubes, which exhibited a reduction in insulin-stimulated glycogen synthesis independently of alterations in glucose flux or insulin signalling through protein kinase B. In control cells, insulin caused redistribution of a minor cytosolic pool of glycogen synthase to an insoluble fraction, which was again forestalled by lipid pretreatment. Glycogen synthase recovered in the insoluble fraction from pre-treated cells exhibited a low fractional velocity that was not increased in response to insulin. Our results suggest that the initial localization of glycogen synthase in a soluble pool plays an important role in glycogen synthesis, and that its sequestration in an insulin-resistant insoluble pool may explain in part the reduced glycogen synthesis caused by lipid oversupply.
Implication of Gβγ proteins and c-SRC tyrosine kinase in parathyroid hormone-induced signal transduction in rat enterocytes
Authors: Gentili Claudia , Boland Ricardo , de Boland Ana Russo
Published: January 2006

Parathyroid hormone (PTH) interacts in target tissues with a G protein-coupled receptor (GPCR) localized in the plasma membrane. Although activation of GPCR can elicit rapid stimulation of cellular protein tyrosine phosphorylation, the mechanism by which G proteins activate protein-tyrosine kinases is not completely understood. In the present work, we demonstrate that PTH rapidly increases the activity of non-receptor tyrosine kinase c-Src in rat intestinal cells (enterocytes). The response is biphasic, the early phase is fast and transient, peaking at 30 s (+120%), while the second phase progressively increases up to 5 min (+220%). The hormone activates c-Src in intestinal cells through fast changes in tyrosine phosphorylation of the enzyme. The first event in the activation of c-Src is the dephosphorylation of Tyr527 (which happens after a few seconds of PTH treatment), followed by a second event of activation with phosphorylation at Tyr416 (+twofold, 5 min). Removal of external Ca2+ (EGTA, 0.5 mM) and chelation of intracellular Ca2+ with 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetracetic acid acetoxymethyl ester (BAPTA) (5 μM) suppressed Tyr527 dephosphorylation and Tyr416 phosphorylation, indicating that Ca2+ is an upstream activator of c-Src in enterocytes stimulated with PTH. The G protein subunits, Gαs and Gβ, are associated with c-Src in basal conditions and this association increases two- to threefold in cells treated with PTH. Blocking of Gβ subunits by preincubation of cells with a Gβ antibody abolished hormone-dependent c-Src Tyr416 phosphorylation and ERK1/ERK2 activation. The results of this work indicate that PTH activates c-Src in intestinal cells through conformational changes via G proteins and calcium-dependent modulation of tyrosine phosphorylation of the enzyme, and that PTH receptor activation leads via Gβγ–c-Src to the phosphorylation of the MAP kinases, ERK1 and ERK2.
Ghrelin and unacylated ghrelin stimulate human osteoblast growth via mitogen-activated protein kinase (MAPK)/phosphoinositide 3-kinase (PI3K) pathways in the absence of GHS-R1a
Authors: Delhanty P J D , van der Eerden B C J , van der Velde M , Gauna C , Pols H A P , Jahr H , Chiba H , van der Lely A J , van Leeuwen J P T M
Published: January 2006

Recent studies demonstrate widespread expression of ghrelin among tissues and have uncovered its pleiotropic nature. We have examined gene expression of ghrelin and its two receptor splice variants, growth hormone secretagogue receptors (GHS-R) 1a and 1b, in human bone biopsies and in the human pre-osteoblastic SV-HFO cell line during differentiation. Additionally, we examined proliferative effects of ghrelin and unacylated ghrelin (UAG) in differentiating and non-differentiating cells. We detected GHS-R1b mRNA in human bone and osteoblasts but not ghrelin’s cognate receptor GHS-R1a, using two different real-time PCR assays and both total RNA and mRNA. In osteoblasts GHS-R1b mRNA expression remained low during the first 14 days of culture, but increased 300% in differentiating cells by day 21. Both human bone biopsies and osteoblasts expressed ghrelin mRNA, and osteoblasts were found to secrete ghrelin. Overall, ghrelin gene expression was greater in differentiating than non-differentiating osteoblasts, but was not increased during culture in either group. Ghrelin and UAG induced thymidine uptake dose-dependently, peaking at 1 and 10 nM respectively, at day 6 of culture in both non-differentiating and differentiating osteoblasts. The proliferative response to ghrelin and UAG declined with culture time and state of differentiation. The proliferative effects of ghrelin and UAG were suppressed by inhibitors of extracellular-signal-regulated kinase (ERK) and phosphoinositide-3 kinase, and both peptides rapidly induced ERK phosphorylation. Overall, our data suggest new roles for ghrelin and UAG in modulating human osteoblast proliferation via a novel signal transduction pathway.
Protein kinase C (PKC)-δ/-ε mediate the PKC/Akt-dependent phosphorylation of extracellular signal-regulated kinases 1 and 2 in MCF-7 cells stimulated by bradykinin
Authors: Greco S , Storelli C , Marsigliante S
Published: January 2006

In this paper the signal transduction pathways evoked by bradykinin (BK) in MCF-7 breast cancer cells were investigated. BK activation of the B2 receptor provoked: (a) the phosphorylation of the extracellular signal-regulated kinases 1 and 2 (ERK1/2); (b) the translocation from the cytosol to the membrane of the conventional protein kinase C-α (PKC-α) and novel PKC-δ and PKC-ε; (c) the phosphorylation of protein kinase B (PKB/ Akt); (d) the proliferation of MCF-7 cells. The BK-induced ERK1/2 phosphorylation was completely blocked by PD98059 (an inhibitor of the mitogen-activated protein kinase kinase (MAPKK or MEK)) and by LY294002 (an inhibitor of phosphoinositide 3-kinase (PI3K)), and was reduced by GF109203X (an inhibitor of both novel and conventional PKCs); Gö6976, a conventional PKCs inhibitor, did not have any effect. The BK-induced phosphorylation of PKB/Akt was blocked by LY294002 but not by PD98059. Furthermore, LY294002 inhibited the BK-provoked translocation of PKC-δ and PKC-ε suggesting that PI3K may be upstream to PKCs. Finally, the proliferative effects of BK were blocked by PD98059, GF109203X and LY294002. These observations demonstrate that BK acts as a proliferative agent in MCF-7 cells activating intracellular pathways involving novel PKC-δ/-ε, PKB/Akt and ERK1/2.
Measurement of circulating salmon IGF binding protein-1: assay development, response to feeding ration and temperature, and relation to growth parameters
Authors: Shimizu Munetaka , Beckman Brian R , Hara Akihiko , Dickhoff Walton W
Published: January 2006

Fish plasma/serum contains multiple IGF binding proteins (IGFBPs), although their identity and physiological regulation are poorly understood. In salmon plasma, at least three IGFBPs with molecular masses of 22, 28 and 41 kDa are detected by Western ligand blotting. The 22 kDa IGFBP has recently been identified as a homolog of mammalian IGFBP-1. In the present study, an RIA for salmon IGFBP-1 was established and regulation of IGFBP-1 by food intake and temperature, and changes in IGFBP-1 during smoltification, were examined. Purified IGFBP-1 from serum was used for as a standard, for tracer preparation and for antiserum production. Cross-linking 125I-labelled IGFBP-1 with salmon IGF-I eliminated interference by IGFs. The RIA had little cross-reactivity with salmon 28 and 41 kDa IGFBPs (< 0·5%) and measured IGFBP-1 levels as low as 0·1 ng/ml. Fasted fish had significantly higher IGFBP-1 levels than fed fish (21·6 ± 4·6 vs 3·0 ± 2·2 ng/ml). Plasma IGFBP-1 was measured in individually tagged 1-year-old coho salmon reared for 10 weeks under four different feeding regimes as follows: high constant (2% body weight/day), medium constant (1% body weight/day), high variable (2% to 0·5% body weight/day) and medium variable (1% to 0·5% body weight/day). Fish fed with the high ration had lower IGFBP-1 levels than those fed with the medium ration. Circulating IGFBP-1 increased following a drop in feeding ration to 0·5% and returned to the basal levels when feeding ration was increased. Another group of coho salmon were reared for 9 weeks under different water temperatures (11 or 7°C) and feeding rations (1·75, 1 or 0·5% body weight/day). Circulating IGFBP-1 levels were separated by temperature during the first 4 weeks; a combined effect of temperature and feeding ration was seen in week 7; only feeding ration influenced IGFBP-1 level thereafter. These results indicate that IGFBP-1 is responsive to moderate nutritional and temperature changes. There was a clear trend that circulating IGFBP-1 levels were negatively correlated with body weight, condition factor (body weight/body length3 × 100), growth rates and circulating 41 kDa IGFBP levels but not IGF-I levels. During parr–smolt transformation of coho salmon, IGFBP-1 levels showed a transient peak in late April, which was opposite to the changes in condition factor. Together, these findings suggest that salmon IGFBP-1 is inhibitory to IGF action. In addition, IGFBP-1 responds to moderate changes in dietary ration and temperature, and shows a significant negative relationship to condition factor.
Soil Cover and Tillage Influenced Metolachlor Mobility and Dissipation in Field Lysimeters
Authors: Weber Jerome B. , Taylor K. Allan , Wilkerson Gail G.
Published: January 2006

Leaching studies using soil column field lysimeters were conducted in 1991 and 1992 to determine the influence of tillage [conventional (CT) and reduced (RT)], soil cover (fallow, soybean, and bermudagrass sod), and water input level on14C metolachlor mobility. Runoff and leachate collectors were installed. Leachate was collected weekly and analyzed for herbicide content. At 128 d after treatment (DAT), the lysimeters were removed, and the soil was analyzed for herbicide concentration as a function of depth. In 1991, 10% greater amounts of14C metolachlor volatilized from CT than from RT (32 vs. 22%). Amounts of metolachlor recovered in surface cover were 2.3% less (2.1 vs. 4.4%), amounts in subsoil were 8% less (47 vs. 55%), and amounts recovered in leachate were 0.7% less (0.7 vs. 1.4%) under CT than RT. In 1992, measured parameters of14C distribution in soil for tillage treatments were similar, except14C recovered in leachate was 3% greater under RT (7 vs. 4%). Amounts of14C metolachlor retained by soil cover were greatest in bermudagrass sod (16%), less in soybean (4%), and least in fallow (1%) and were similar for each treatment both years. Carbon‐14 metolachlor recovered in leachate of all treatments was approximately five times greater in 1992 (5%) than in 1991 (1%) due to the 7% greater water input in 1992, much of which occurred shortly after Day 0. Leachate volume collected in 1992 (8 L) was also twice that of 1991 (4 L). Tillage and soil cover interaction effects occurred both years.
Long‐Term Effects of Tillage on Soil Chemical Properties and Grain Yields of a Dryland Winter Wheat–Sorghum/Corn–Fallow Rotation in the Great Plains
Authors: Tarkalson David D. , Hergert Gary W. , Cassman Kenneth G.
Published: January 2006

Tillage systems and nutrient management influence soil chemical properties that can impact the long‐term sustainability of dryland production systems. This study was conducted to compare the effects of no‐till (NT) and conventional till (CT) on the soil chemical properties and grain yield of a dryland winter wheat (Triticum aestivumL.)–grain sorghum [Sorghum bicolor(L.) Moench]/corn (Zea maysL.)–fallow rotation. The effects of tillage practice over a 27‐yr period (1962–1989) and the effect of the conversion of CT to NT over a 14‐yr period (1989–2003) on selected soil chemical properties [pH, cation exchange capacity (CEC), base saturation (BS), soil organic C (SOC), K, Ca, Mg, and Bray‐P] at different soil depths was determined. The acidification rate of the NT treatment from 1962 to 2003 was also determined. The study was conducted at North Platte, NE on a Holdrege silt loam (fine‐silty, mixed, mesic Typic Argiustolls). In 1989, there were differences in soil chemical properties between CT and NT at some depths after 27 yr. However, in 2003, 14 yr after converting from CT to NT, there were no differences in the soil chemical properties compared with continuous NT. In 1989 and 2003, the soil chemical properties varied with soil depth. The acidification rate from 1962 to 2003 for the NT treatment in the 0‐ to 15‐cm depth was 1.3 kmol H+ha−1yr−1. This rate of acidification represents 38% of the total potential acidity from N fertilizer applications over 41 yr. Acidification was attributed to nitrification of ammonium‐based fertilizers and leaching of NO3−Long‐term winter wheat (1966–1983) and grain sorghum (1964–1988) grain yields were higher for NT (2718 and 4125 kg ha−1) than CT (2421 and 3062 kg ha−1). Retention of soil moisture as a result of increased residue cover under NT likely contributed to higher NT yields. Soil chemical properties in the wheat–sorghum/corn–fallow rotation will likely continue to change as a result of current management practices. Lime additions may become necessary in the future to ensure the sustainability of crop production in this system.
Economic Analysis of Spatial‐Temporal Patterns in Corn and Soybean Response to Nitrogen and Phosphorus
Authors: Lambert D. M. , Lowenberg‐DeBoer J. , Malzer G. L.
Published: January 2006

Interactions among environmental factors, management decisions, and field characteristics cause temporal and spatial variability in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yields. The objectives of this paper are (i) to test whether yield response of corn to N and P and of soybean to P are spatially and temporally stable, and (ii) to evaluate the profitability of a variable rate (VR) N and P fertility management strategy over a 5‐yr, corn–soybean rotation using this response information. A field near Windom, MN, USA, was cropped with corn (1997, 1999, and 2001) and soybean (1998, 2000). Three replications of 13 N and P treatments were established in a split‐plot arrangement of a randomized complete block design. Treatments were applied at constant rates in strips across the entire field. Fertilizer N treatments were 0, 67, 112, 157, and 202 kg ha−1 and P treatments were 0, 56, and 112 kg P2O5 ha−1. The field was partitioned into sub‐blocks for spatial analysis of yield response. Corn and soybean response to these inputs was estimated for each block, each year. Results indicate that spatial variation of crop response to these inputs is significant, and that response of corn and soybean to P is temporally stable in some parts of the field, but not others. Response to N was not temporally stable. Results of an ex post profitability analysis found that average returns over the 5‐yr period from the VR N and P management strategy were $28 ha−1 higher than returns from a uniform application strategy.
A Pneumatic Device for Lifting Containers in Plant Water Use Studies
Authors: Prior S. A. , Runion G. B. , Kornecki T. S. , Rogers H. H.
Published: January 2006

Direct gravimetric determinations of whole‐plant water use in container studies can be time consuming due to the tremendous labor required to physically lift containers for placement on weighing scales. Our objective was to design and construct a container‐weighing system that could be rapidly deployed and required little physical labor. A custom‐made support frame, equipped with a pneumatic lifting cylinder connected to a hanging scale, was constructed to lift large plastic containers (45 L) filled with a coarse sandy medium (>70 kg when saturated with water). Custom lifting arms designed to catch the handles of the plastic containers were constructed for attachment to the scale. The support frame weighing apparatus was positioned over the container, and the pneumatic lifting cylinder was activated only after lifting arms had been attached to the plastic container. As many as 25 large plastic containers could be weighed per hour with this system. The weighing system has been successfully used to follow plant water use patterns over time.
Nitrogen Fertilization and Yield of Cotton in Ultra‐Narrow and Conventional Row Spacings
Authors: Clawson Ernest L. , Cothren J. Tom , Blouin David C.
Published: January 2006

Nitrogen fertilizer requirements of ultra‐narrow row (UNR) cotton (Gossypium hirsutum L.) are not well established, and lint yield of UNR relative to conventional‐row (CR) cotton has been variable. Objectives of this study were to compare UNR and CR N requirements based on lint yield, fiber quality, and plant architecture, and to compare the yield potential of UNR and CR cotton. The location was the Texas Agricultural Experiment Station Farm, Burleson County, TX. Treatments were N fertilizer rates of 0, 50, 101, and 151 kg ha−1 and row spacings of 19, 38 (both UNR), and 76 cm (CR). By design, per‐hectare plant populations were greatest in 19‐ and least in 76‐cm row spacings. Plots were hand harvested. Reductions in row spacing decreased plant height, main stem nodes plant−1, and subset (first position bolls at nodes 6–10) individual boll weight. Greater N increased plant height, main stem nodes plant−1, and both whole‐plant and subset individual boll weight. Lint percentage was increased by reduction in row spacing and not affected by N. Treatment effects on fiber quality were limited. Lint yield did not differ among row spacings. Significant increases in lint yield occurred with each increase in N, suggesting that the optimal N rate was not surpassed. Nitrogen by row spacing interaction on lint yield was not significant, implying a similar response of each row spacing to N over the fertilizer rates tested. The N fertilizer requirements of UNR do not appear to be lower than those of CR cotton.
Effects of Fresh and Composted Dairy Manure Applications on Alfalfa Yield and the Environment in Arizona
Authors: Martin E. C. , Slack D. C. , Tanksley K. A. , Basso B.
Published: January 2006

The Unified Animal Feeding Operation Strategy requires that field application of animal waste, a common fertilization and disposal practice, may not exceed crop nutrient needs. Additional guidelines set forth by the Arizona Department of Environmental Quality state that animal waste applications on agricultural fields in designated Confined Animal Feeding Operations (CAFOs) must be made in a manner such that the total N applied to the field cannot exceed the uptake from the crop grown. Because alfalfa is grown year round and can take up large quantities of N, many operators of CAFOs apply animal waste to their production alfalfa fields as method of waste disposal. In this research, fresh and composted dairy manure was applied to plots in a production alfalfa (Medicago sativaL.) field to determine the impact on alfalfa yield, soil nitrogen (N), phosphorus (P), and electrical conductivity (EC) levels and the potential for nitrate (NO3) and phosphate (PO4) leaching. Unfertilized plots were maintained as controls. Fresh and composted manure was applied to fertilized plots after each harvest at a rate intended to replace N removed from the previous cutting. After 1.5 yr and 13 cuttings, soil analysis down to 150 cm depth showed no significant difference in soil N between treatments. At study end, NO3–N made up 1.1% of total N in the fertilized plots but only 0.6% in control plots. Changes in soil N were not significant. Soil P content increased in fertilized plots but remained stable in control plots. Final soil PO4measurements were 16, 99, and 116 kg ha−1in the control, manure‐treated, and compost‐treated plots, respectively. Leachate from three drainage lysimeters contained no detectable NO3or PO4from any of the treatments. LSD showed no difference in EC between the beginning and the end of study, and alfalfa yield did not vary among treatments.
Effect of Genotype, Nitrogen, Plant Density, and Row Spacing on the Area‐per‐Leaf Profile in Maize
Authors: Valentinuz Oscar R. , Tollenaar Matthijs
Published: January 2006

Accurate estimates of total leaf area and the vertical leaf area profile are important in process‐based crop growth models. The bell‐shaped function that quantifies the area‐per‐leaf profile of a maize (Zea mays L.) plant can be used to estimate the area‐per‐leaf profile. The objectives of this study were to quantify the effects of maize hybrid, soil N, plant density, and row spacing on the coefficients of the bell‐shaped function. The coefficients of the bell‐shaped function that quantify (i) the breadth of the area‐per‐leaf profile, (ii) the skewness of the area‐per‐leaf profile, and (iii) the position of the largest leaf were estimated using nonlinear regression in four datasets. Datasets consisted of the fully expanded leaf areas of all leaves on maize plants grown in studies performed in Ontario, Canada, between 1997 and 2001 that included combinations of maize hybrids, plant densities, N levels, and row spacing. Observations fitted well to the bell‐shaped function (r2 > 0.95). The breadth of the area‐per‐leaf profile decreased under high soil N level and high plant density, and was lower for a newer than an older hybrid, whereas the opposite occurred with the position of the largest leaf. In contrast, the degree of skewness was not significantly altered by any of the factors examined in this study. Because of the relatively small impact of the examined agronomic factors on the coefficients of the bell‐shaped function, a general model using mean coefficient values was validated with independent datasets. Results showed that this general bell‐shaped function is a robust predictor of the area‐per‐leaf profile in maize.
Planting Date Effects on Bt and Non‐Bt Corn in the Mid‐South USA
Authors: Bruns H. Arnold , Abbas H. K.
Published: January 2006

Corn (Zea mays L.) planting dates are regional and vary across the contiguous USA. Improved technologies allow corn to be planted earlier. The objective of this research was to evaluate the effects of planting date on the agronomics of Bt and non‐Bt hybrids grown in the Mid‐South. Twelve hybrids, two Bt [Bacillus thuringiensis (Berliner)], and two non‐Bt for three maturity groups [short‐season (1180–1270 GDU 10's), mid‐season (1445–1470 GDU 10's), and full‐season (1540–1625 GDU 10's)] were evaluated for GDU 10's at silking and physiological maturity, yield, yield components, and mycotoxins in 2002, 2003, and 2004 at Stoneville, MS. Plots were planted in a split‐plot of a randomized complete block replicated four times and furrow irrigated. Whole plots were plantings in early April, late April, or mid‐May, while subplots were hybrids randomly assigned. Experimental units were four 102‐cm rows, 9.1 m long. Lodging and dropped ears were inconsequential. Yields were greater for both April plantings (8.6 and 9.2 Mg ha−1 for early April and late April, respectively) than mid‐May plantings (7.8 Mg ha−1). Short‐season hybrids generally yielded less than mid‐season or full‐season hybrids. The Bt hybrids yielded more than non‐Bt hybrids (9.1 Mg ha−1 vs. 7.9 Mg ha−1, respectively). Yields correlated with GDU 10's at silking [yield = 0.037x − 20.416 (r = 0.77)] but not physiological maturity. Aflatoxin was high in 2002 (224.0 mg Mg−1), and much less (28.8 and 7.4 mg Mg−1) in 2003 and 2004, respectively. The Bt hybrids had less fumonisin contamination than non‐Bt hybrids (5.2 mg kg−1 vs. 8.5 mg kg−1) but less aflatoxin only in 2003 (12.4 mg Mg−1 vs. 45.3 mg Mg−1).
Effect of Long‐Term Application of Biosolids for Land Reclamation on Surface Water Chemistry
Authors: Tian G. , Granato T. C. , Pietz R. I. , Carlson C. R. , Abedin Z.
Published: January 2006

Biosolids are known to have a potential to restore degraded land, but the long‐term impacts of this practice on the environment, including water quality, still need to be evaluated. The surface water chemistry (NO3−, NH4+, and total P, Cd, Cu, and Hg) was monitored for 31 yr from 1972 to 2002 in a 6000‐ha watershed at Fulton County, Illinois, where the Metropolitan Water Reclamation District of Greater Chicago was restoring the productivity of strip‐mined land using biosolids. The mean cumulative loading rates during the past 31 yr were 875 dry Mg ha−1 for 1120‐ha fields in the biosolids‐amended watershed and 4.3 dry Mg ha−1 for the 670‐ha fields in the control watershed. Biosolids were injected into mine spoil fields as liquid fertilizer from 1972 to 1985, and incorporated as dewatered cake from 1980 to 1996 and air‐dried solids from 1987 to 2002. The mean annual loadings of nutrients and trace elements from biosolids in 1 ha were 735 kg N, 530 kg P, 4.5 kg Cd, 30.7 kg Cu, and 0.11 kg Hg in the fields of the biosolids‐amended watershed, and negligible in the fields of the control watershed. Sampling of surface water was conducted monthly in the 1970s, and three times per year in the 1980s and 1990s. The water samples were collected from 12 reservoirs and 2 creeks receiving drainage from the fields in the control watershed, and 8 reservoirs and 4 creeks associated with the fields in the biosolids‐amended watershed for the analysis of NO3−–N (including NO2−–N), NH4+–N, and total P, Cd, Cu, and Hg. Compared to the control (0.18 mg L−1), surface water NO3−–N in the biosolids‐amended watershed (2.23 mg L−1) was consistently higher; however, it was still below the Illinois limit of 10 mg L−1 for public and food‐processing water supplies. Biosolids applications had a significant effect on mean concentrations of ammonium N (0.11 mg L−1 for control and 0.24 mg L−1 for biosolids) and total P (0.10 mg L−1 for control and 0.16 mg L−1 for biosolids) in surface water. Application of biosolids did not increase the concentrations of Cd and Hg in surface water. The elevation of Cu in surface water with biosolids application only occurred in some years of the first decade, when land‐applied sludges contained high concentrations of trace metals, including Cu. In fact, following the promulgation of 40 CFR Part 503, the concentrations of all three metals fell below the method detection level (MDL) in surface water for nearly all samplings. Nitrate in the surface water tends to be higher in spring, and ammonium, total P, and total Hg in summer and fall. Mean nitrate, ammonium, and total phosphorus concentrations were found to be greater in creeks than reservoirs. The results indicate that application of biosolids for land reclamation at high loading rates from 1972 to 2002, with adequate runoff and soil erosion control, had only a minor impact on surface water quality.
Trihalomethane Reactivity of Water‐ and Sodium Hydroxide–Extractable Organic Carbon Fractions from Peat Soils
Authors: Chow Alex T. , Guo Fengmao , Gao Suduan , Breuer Richard S.
Published: January 2006

Certain organic carbon moieties in drinking source waters of the Sacramento–San Joaquin Delta can react with chlorine during disinfection to form potentially carcinogenic and mutagenic trihalomethanes. The properties of reactive organic carbon in Delta waters, particularly those of soil origin, have been poorly understood. This study attempts to characterize trihalomethane reactivity of soil organic carbon from three representative Delta peat soils. Soil organic carbon was extracted from all three soils with either deionized H2O or 0.1 M NaOH and sequentially separated into humic acids, fulvic acids, and nonhumic substances for quantitation of trihalomethane formation potential. Water‐extractable organic carbon represented only 0.4 to 0.7% of total soil organic carbon, whereas NaOH extracted 38 to 51% of total soil organic carbon. The sizes and specific trihalomethane formation potential (STHMFP) of individual organic carbon fractions differed with extractants. Fulvic acids were the largest fraction in H2O‐extractable organic carbon, whereas humic acids were the largest fraction in NaOH‐extractable organic carbon. Among the fractions derived from H2O‐extractable carbon, fulvic acids had the greatest specific ultraviolet absorbance and STHMFP and had the majority of reactive organic carbon. Among the fractions from NaOH‐extractable organic carbon, humic acids and fulvic acids had similar STHMFP and, thus, were equally reactive. Humic acids were associated with the majority of trihalomethane reactivity of NaOH‐extractable organic carbon. The nonhumic substances were less reactive than either humic acids or fulvic acids regardless of extractants. Specific ultraviolet absorbance was not a good predictor of trihalomethane reactivity of organic carbon fractions separated from the soils.
Estrogenic Activity in the Environment: Municipal Wastewater Effluent, River, Ponds, and Wetlands
Authors: Shappell Nancy W.
Published: January 2006

Estrogenic activity of regional water samples was evaluated. Samples obtained from wetlands and ponds involved in various agricultural land uses, from three river sites over four seasons, and from municipal wastewater effluent held in storage lagoons were evaluated. The estrogen‐responsive cell line MCF‐7 BOS was used in the E‐screen assay to determine 17β‐estradiol equivalents (E2 Eq) of water samples extracted by solid‐phase extraction. Estrogenic activity in surrounding wetlands and ponds from different land uses was not different, with 10−12 M E2 Eq (0.3 ppt). Estrogenic activity of Red River samples was within the same range as wetland–pond samples. The highest activity was found downstream from municipal wastewater treatment effluent discharge sites, in winter when river flow was lowest (approximately 6 × 10−13 M E2 Eq). Results showed that 7 of 20 wetland–pond samples and 5 of 12 river samples were below the limits of quantitation (approximately 3 × 10−14 M E2 Eq). Toxicity was found in fall and summer river samples upstream from municipal wastewater release sites. The timing of toxicity did not coincide to the presence of elevated fecal coliforms. Estrogenic activity in wastewater effluent from lagoons decreased over time (approximately 25 to 5 × 10−13 M E2 Eq) with an apparent half‐life of 8 d for one lagoon. The median concentration of detectable estrogenic activity in regional water samples was approximately 50‐fold less than the median 17β‐estradiol concentration of estradiol detected in some U.S. streams in previous studies.
Altered Ecohydrologic Response Drives Native Shrub Loss under Conditions of Elevated Nitrogen Deposition
Authors: Wood Yvonne A. , Meixner Thomas , Shouse Peter J. , Allen Edith B.
Published: January 2006

Many regions of southern California's coastal sage scrub (CSS) are rapidly declining as exotic annual plants replace native shrubs. During this conversion, the subsurface hydrology of the semiarid hillslopes that support CSS may be altered. This could chronically suppress the ability of native shrubland to revegetate the landscape since ecosystem processes of nutrient availability and of seedling establishment rely on spatial patterns of available soil water. In this work, soil water and nutrient N regimes were compared over a 2‐yr period between a southern California site where CSS has declined (approximately 5% shrub cover) with high additions of anthropogenic N, and one where CSS remains dominant (over 50% shrub cover) with predominantly background atmospheric additions of N. These two sites have similar climate, bedrock lithology, soils, and topography, and had the same vegetation type (Riversidean CSS) 30 years ago. We found that the depth and rate of rainwater percolation into wildland hillslope soils in response to early‐season storm events has been greatly reduced after loss of CSS shrubs and vegetation type conversion to invasive grassland. With decreased rainwater redistribution to soil depths of 100 to 150 cm, the predominant zone of soil water has become the upper 25 cm. This shift exacerbates vegetation type conversion by (i) concentrating smog‐produced nitrogenous (N) chemicals in the uppermost soil, where they become readily available, along with high soil water, to shallow‐rooted exotic grasses early in the growing season and (ii) depriving adult and juvenile shrubs of deeper regolith water.
Carbon and Nitrogen Mineralization Rates after Application of Organic Amendments to Soil
Authors: Flavel Tamara C. , Murphy Daniel V.
Published: January 2006

The objective of this study was to quantify C and N mineralization rates from a range of organic amendments that differed in their total C and N contents and C quality, to gain a better understanding of their influence on the soil N cycle. A pelletized poultry manure (PP), two green waste–based composts (GWCa, GWCb), a straw‐based compost (SBC), and a vermi‐cast (VER) were incubated in a coarse‐textured soil at 15°C for 142 d. The C quality of each amendment was determined by chemical analysis and by13C nuclear magnetic resonance (NMR). Carbon dioxide (CO2–C) evolution was determined using alkali traps. Gross N mineralization rates were calculated by15N isotopic pool dilution. The CO2–C evolution rates and gross N mineralization rates were generally higher in amended soils than in the control soil. With the exception of GWCb all amendments released inorganic N at concentrations that would be high enough to warrant a reduction in inorganic N fertilizer application rates. The amount of N released from PP was high indicating that application rates should be reduced, or alternative amendments used, to minimize leaching losses in regions where ground water quality is of concern. There was a highly significant relationship between CO2–C evolution and gross N mineralization (R2= 0.95). Some of the chemically determined C quality parameters had significant relationships (p< 0.05) with both the cumulative amounts of C and N evolved. However, we found no significant relationships between13C NMR spectral groupings, or their ratios, and either the CO2–C evolved or gross N mineralized from the amendments.