bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sorption Kinetics and Equilibria of Organic Pesticides in Carbonatic Soils from South Florida
Authors: Nkedi‐Kizza P. , Shinde D. , Savabi M. R. , Ouyang Y. , Nieves L. 
Published: January 2006

ABSTRACTA batch reactor was used to determine sorption kinetic parameters (k2, F, and K*) and the equilibrium sorption coefficient (K). The two‐site nonequilibrium (TSNE) batch sorption kinetics model was used to calculate the kinetic parameters. Two probe organic pesticides, atrazine [2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine] and diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea] were studied using three carbonatic soils from South Florida (Chekika, Perrine, and Krome), one noncarbonatic soil from Iowa (Webster), and one organic soil (Lauderhill) from South Florida. Carbonatic soils contained more than 600 g kg−1 CaCO3 Sorption is initially very fast up to 3 h and then slowly reaches equilibrium. All soil–chemical combinations reached sorption equilibrium after about 24 h and all sorption isotherms were linear. The sorption kinetics data were well described by the TSNE model for all soil‐chemical combinations except for the marl soil data (Perrine–Atrazine), which were better described by the one‐site nonequilibrium (OSNE) model. Diuron, with higher K, undergoes slower sorption kinetics than atrazine. The Lauderhill soil containing organic carbon (OC) of 450 g kg−1 exhibited slowest sorption kinetics for both pesticides. An inverse relationship between k2 and K was observed for atrazine and diuron separately in Chekika, Webster, and Lauderhill soils but not in Perrine and Krome soils. The sorption kinetic parameters were used to distinguish the sorption behavior between atrazine and diuron and to identify differences between soils. Normalizing the sorption coefficient (K) to OC showed that atrazine and diuron had Koc values in carbonatic soils that were a third of reported literature values for noncarbonatic soils. Using existing literature Koc values in solute transport models will most likely underestimate the mobility of atrazine, diuron, and other neutral organic chemicals in carbonatic soils.
Effects of Plants on the Removal of Hexavalent Chromium in Wetland Sediments
Authors: Xu Shangping , Jaffé Peter R. 
Published: January 2006

ABSTRACTThe effect of two wetland plants, Typha latifolia L. (cattail) and Phragmites australis (Cav.) Trin. ex Steud (common reed), on the fate of Cr(VI) in wetland sediments was investigated using greenhouse bench‐scale microcosm experiments. The removal of Cr(VI) was monitored based on the vertical profiles of aqueous Cr(VI) in the sediments. The Cr(VI) removal rates were estimated taking into account plant transpiration, which was found to significantly concentrate dissolved species in the sediments. After correcting for evapotranspiration, the actual Cr(VI) removal rates were significantly higher than would be inferred from uncorrected profiles. On average, the Cr(VI) removal rates were 0.005 to 0.017 mg L−1 d−1, 0.0003 to 0.08 mg L−1 d−1, and 0.004 to 0.13 mg L−1 d−1 for the control, T. latifolia, and P. australis microcosms, respectively. The fate of the removed Cr(VI) was examined by determining the quantity and chemical speciation of the Cr in the sediment and plant materials. Chromium(III) was the dominant form of Cr in both the sediment and plants, and precipitation of Cr(III) in the sediment was the major pathway responsible for the disappearance of aqueous Cr(VI) from the pore water. Incubation results showed that abiotic reduction was the primary mechanism underlying Cr(VI) removal in the microcosm sediments. Organic compounds produced by plants, including root exudates and mineralization products of dead roots, are thought to be the factor that is either directly or indirectly responsible for the gap between Cr(VI) removal efficiencies in the sediments of the vegetated and unvegetated microcosms.
Nitrogen and Phosphorus Status of Soils and Trophic State of Lakes Associated with Forage‐Based Beef Cattle Operations in Florida
Authors: Sigua G. C. , Williams M. J. , Coleman S. W. , Starks R. 
Published: January 2006

ABSTRACTForage‐based livestock systems have been implicated as major contributors to deteriorating water quality, particularly for phosphorus (P) from commercial fertilizers and manures affecting surface and ground water quality. Little information exists regarding possible magnitudes of nutrient losses from pastures that are managed for both grazing and hay production and how these might impact adjacent bodies of water. We examined the changes that have occurred in soil fertility levels of rhizoma peanut (Arachis glabrataBenth.)‐based beef cattle pastures (n= 4) in Florida from 1988 to 2002. These pastures were managed for grazing in spring followed by haying in late summer and were fertilized annually with P (39 kg P2O5ha−1) and K (68 kg K2O ha−1). Additionally, we investigated trends in water quality parameters and trophic state index (TSI) of lakes (n= 3) associated with beef cattle operations from 1993 to 2002. Overall, there was no spatial or temporal buildup of soil P and other crop nutrients despite the annual application of fertilizers and daily in‐field loading of animal waste. In fact, soil fertility levels showed a declining trend for crop nutrient levels, especially soil P (y= 146.57 − 8.14 × year;r2= 0.75), even though the fields had a history of P fertilization and the cattle were rotated into the legume fields. Our results indicate that when nutrients are not applied in excess, cow‐calf systems are slight exporters of P, K, Ca, and Mg through removal of cut hay. Water quality in lakes associated with cattle production was “good” (30–46 TSI) based on the Florida Water Quality Standard. These findings indicate that properly managed livestock operations may not be major contributors to excess loads of nutrients (especially P) in surface water.
Leaching of N‐Nitrosodimethylamine (NDMA) in Turfgrass Soils during Wastewater Irrigation
Authors: Gan J. , Bondarenko S. , Ernst F. , Yang W. , Ries S. B. , Sedlak D. L. 
Published: January 2006

ABSTRACTN‐nitrosodimethylamine (NDMA) is a carcinogenic by‐product of chlorination that is frequently found in municipal wastewater effluent. NDMA is miscible in water and negligibly adsorbed to soil, and therefore may pose a threat to ground water when treated wastewater is used for landscape irrigation. A field study was performed in the summer months under arid Southern California weather conditions to evaluate the leaching potential of NDMA in turfgrass soils during wastewater irrigation. Wastewater was used to irrigate multiple turfgrass plots at 110 to 160% evapotranspiration rate for about 4 mo, and leachate was continuously collected and analyzed for NDMA. The treated wastewater contained relatively high levels of NDMA (114–1820 ng L−1; mean 930 ng L−1). NDMA was detected infrequently in the leachate regardless of the soil type or irrigation schedule. At a method detection limit of 2 ng L−1, NDMA was only detected in 9 out of 400 leachate samples and when it was detected, the NDMA concentration was less than 5 ng L−1 NDMA was relatively persistent in the turfgrass soils during laboratory incubation, indicating that mechanisms other than biotransformation, likely volatilization and/or plant uptake, contributed to the rapid dissipation. Under conditions typical of turfgrass irrigation with wastewater effluent it is unlikely that NDMA will contaminate ground water.
Loss Pathways of N‐Nitrosodimethylamine (NDMA) in Turfgrass Soils
Authors: Arienzo M. , Gan J. , Ernst F. , Qin S. , Bondarenko S. , Sedlak D. L. 
Published: January 2006

ABSTRACTN‐nitrosodimethylamine (NDMA) is a potent carcinogen that is often present in municipal wastewater effluents. In a previous field study, it was observed that NDMA did not leach through turfgrass soils following 4 mo of intensive irrigation with NDMA‐containing wastewater effluent. To better understand the loss pathways for NDMA in landscape irrigation systems, a mass balance approach was employed using in situ lysimeters treated with 14C‐NDMA. When the lysimeters were subjected to irrigation and field conditions after NDMA application, very rapid dissipation of NDMA was observed for both types of soil used in the field plots. After only 4 h, total 14C activity in the lysimeters decreased to 19.1 to 26.1% of the applied amount, and less than 1% of the activity was detected below the 20‐cm depth. Analysis of plant materials showed that less than 3% of the applied 14C was incorporated into the plants, suggesting only a minor role for plant uptake in removing NDMA from the vegetated soils. The rapid dissipation and limited downward movement of NDMA in the in situ lysimeters was consistent with the negligible leaching observed in the field study, and suggests volatilization as the only significant loss pathway. This conclusion was further corroborated by rapid NDMA volatilization found from water or a thin layer of soil under laboratory conditions. In a laboratory incubation experiment, prolonged wastewater irrigation did not result in enhanced NDMA degradation in the soil. Therefore, although NDMA may be present at relatively high levels in treated wastewater, gaseous diffusion and volatilization in unsaturated soils may effectively impede significant leaching of NDMA, minimizing the potential for ground water contamination from irrigation with treated wastewater.
An Examination of Spin–Lattice Relaxation Times for Analysis of Soil and Manure Extracts by Liquid State Phosphorus‐31 Nuclear Magnetic Resonance Spectroscopy
Authors: McDowell R. W. , Stewart I. , Cade‐Menun B. J. 
Published: January 2006

ABSTRACTPhosphorous (P)‐31 nuclear magnetic resonance (NMR) spectroscopy is used in the analysis of P forms in extracts of soils and manures for environmental and agronomic purposes. Quantitative spectra require knowledge about spin–lattice relaxation times (T1) to ensure adequate delays between pulses. This paper determined T1 values of P forms in reconstituted (0.2 g in 0.7 mL−1) samples of freeze‐dried 0.25 M NaOH plus 50 mM EDTA extracts of eight diverse soils (Aquept, Dystrochrept × 2, Hapludand, Rendoll, Udand, Haplostoll, and Orthod), three different manures (dairy cattle, deer, and sheep), and one epiphyte moss. Total concentrations in the reconstituted samples ranged from 5 to 175 mg Fe mL−1, 2 to 62 mg Mn mL−1, and 72 to 837 mg P mL−1 Values of T1 for orthophosphate monoesters, orthophosphate diesters, and pyrophosphate varied from 0.42 to 1.69 s in soils and from 0.89 to 2.59 s in manures and the epiphyte. In contrast, T1 for orthophosphate varied from 0.78 to 1.94 s in soils and 1.45 to 5.82 s in manures and the epiphyte. For quantitative 31P NMR, delay times should be three to five times the T1 value, translating to delays of 3 to 5 s for soils and up to 25 s for manures. If the required delay is too long then strategies such as adding paramagnetics could shorten T1, provided this does not increase line‐broadening too much. A regression relationship was obtained between orthophosphate T1 values and the ratio of P concentration to Fe and Mn concentration on a w/v basis (r2 = 0.97, P < 0.001), and between the T1 for all other compound classes and the ratio of P to Fe and Mn (r2 = 0.70, P < 0.01). By combining measurement of Fe, Mn, and P in the reconstituted extract and these relationships, T1 can be estimated and the appropriate delay time used. If T1 is not considered and the delay time is too short, some peaks will be under‐ or over‐represented and the relative distribution of P forms not quantitative.
Hybrid Molecular/Inorganic Semiconductor Transistors in Vertical Architectures
Authors: Meruvia M. S. , Hümmelgen I. A. 
Published: January 2006

AbstractInorganic semiconductor–metal–semiconductor transistors were developed more than 40 years ago. However, despite being potentially attractive for fast switching and sensor applications, they are difficult to produce and usually show low base transport factors, thereby limiting their applicability. Recent developments in hybrid organic/inorganic semiconductor–metal–semiconductor transistors, however, demonstrate that high‐gain transistors can be produced using simple technologies. Additionally, their fabrication is compatible with well‐established silicon electronics technology, which provides an enormous advantage. These devices, built in a vertical architecture, offer attractive new possibilities due to the large variety of available molecular semiconductors, opening the possibility of incorporating new functionalities in silicon‐based devices.
Hydrothermal Growth of Manganese Dioxide into Three‐Dimensional Hierarchical Nanoarchitectures
Authors: Ding Y.‐S. , Shen X.‐F. , Gomez S. , Luo H. , Aindow M. , Suib S. L. 
Published: January 2006

AbstractNovel three‐dimensional (3D) hierarchical nanoarchitectures of ϵ‐MnO2 have been synthesized by a simple chemical route without the addition of any surfactants or organic templates. The self‐organized crystals consist of a major ϵ‐MnO2 dipyramidal single crystal axis and six secondary branches, which are arrays of single‐crystal ϵ‐MnO2 nanobelts. The growth directions of the nanobelts are perpendicular to the central dipyramidal axis, which shows sixfold symmetry. The shape of the ϵ‐MnO2 assembly can be controlled by the reaction temperature. The morphology of ϵ‐MnO2 changes from a six‐branched star‐like shape to a hexagonal dipyramidal morphology when the temperature is increased from 160 to 180 °C. A possible growth mechanism is proposed. The synthesized ϵ‐MnO2 shows both semiconducting and magnetic properties. These materials exhibit ferromagnetic behavior below 25 K and paramagnetic behavior above 25 K. The ϵ‐MnO2 system may have potential applications in areas such as fabrication of nanoscale spintronic materials, catalysis, and sensors.
Enhancement of External Quantum Efficiency of Red Phosphorescent Organic Light‐Emitting Devices with Facially Encumbered and Bulky PtII Porphyrin Complexes
Authors: Ikai M. , Ishikawa F. , Aratani N. , Osuka A. , Kawabata S. , Kajioka T. , Takeuchi H. , Fujikawa H. , Taga Y. 
Published: January 2006

AbstractAn enhancement in the external quantum efficiency (QE) of red phosphorescent organic light‐emitting devices (OLEDs) by using facially encumbered and bulky meso‐aryl substituted PtII porphyrin complexes is demonstrated. The maximum external QEs of phosphorescent OLEDs doped with the facially non‐encumbered PtII porphyrin complex 1 [5,15‐bis[4‐(4,4‐dimethyl‐2,6‐dioxacyclohexyl)phenyl]‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrin platinum(II)], the facially encumbered PtII porphyrin complex 2 [5,15‐bis(2,6‐dimethoxyphenyl)‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrinato platinum(II)], the PtII porphyrin complex 3 that bears bulkier 3,5‐di‐tert‐butylphenyl substituents [5,15‐bis(3,5‐di‐t‐butylphenyl)‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrin platinum(II)], and the “doubly‐decamethylene‐strapped” PtII porphyrin complex 4 were 1, 4.2, 7.3, and 8.2 %, respectively. The trend of increasing QE values in the order of 1 < 2 < 3 < 4 may be related to facial encumbrance and steric bulkiness of meso‐aryl substituted PtII porphyrin complexes. Especially, in the case of the PtII porphyrin 4, it is considered that the “double straps” play an important role in restricting rotational freedom of the meso‐aryl substituents. The triplet excited‐state lifetimes for PtII porphyrins 1–4 in OLEDs at an injection current density of 0.55 mA cm–2 were 80, 103, 140, and 152 μs, respectively. We believe that the trend of increasing triplet lifetime in going from 1 to 4 is correlated with suppressing non‐radiative decay.
Highly Ordered Mesoporous Silicon Carbide Ceramics with Large Surface Areas and High Stability
Authors: Shi Y. F. , Meng Y. , Chen D. H. , Cheng S. J. , Chen P. , Yang H. F. , Wan Y. , Zhao D. Y. 
Published: January 2006

AbstractHighly ordered mesoporous silicon carbide ceramics have been successfully synthesized with yields higher than 75 % via a one‐step nanocasting process using commercial polycarbosilane (PCS) as a precursor and mesoporous silica as hard templates. Mesoporous SiC nanowires in two‐dimensional (2D) hexagonal arrays (p6m) can be easily replicated from a mesoporous silica SBA‐15 template. Small‐angle X‐ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images show that the SiC nanowires have long‐range regularity over large areas because of the interwire pillar connections. A three‐dimensional (3D) bicontinuous cubic mesoporous SiC structure (Ia3d) can be fabricated using mesoporous silica KIT‐6 as the mother template. The structure shows higher thermal stability than the 2D hexagonal mesoporous SiC, mostly because of the 3D network connections. The major constituent of the products is SiC, with 12 % excess carbon and 14 % oxygen measured by elemental analysis. The obtained mesoporous SiC ceramics are amorphous below 1200 °C and are mainly composed of randomly oriented β‐SiC crystallites after treatment at 1400 °C. N2‐sorption isotherms reveal that these ordered mesoporous SiC ceramics have high Brunauer–Emmett–Teller (BET) specific surface areas (up to 720 m2 g–1), large pore volumes (∼ 0.8 cm3 g–1), and narrow pore‐size distributions (mean values of 2.0–3.7 nm), even upon calcination at temperatures as high as 1400 °C. The rough surface and high order of the nanowire arrays result from the strong interconnections of the SiC products and are the main reasons for such high surface areas. XRD, N2‐sorption, and TEM measurements show that the mesoporous SiC ceramics have ultrahigh stability even after re‐treatment at 1400 °C under a N2 atmosphere. Compared with 2D hexagonal SiC nanowire arrays, 3D cubic mesoporous SiC shows superior thermal stability, as well as higher surface areas (590 m2 g–1) and larger pore volumes (∼ 0.71 cm3 g–1).
Self‐Assembled Shape‐Memory Fibers of Triblock Liquid‐Crystal Polymers
Authors: Ahir S. V. , Tajbakhsh A. R. , Terentjev E. M. 
Published: January 2006

AbstractNew thermoplastic liquid‐crystalline elastomers have been synthesized using the telechelic principle of microphase separation in triblock copolymers. The large central block is made of a main‐chain nematic polymer renowned for its large spontaneous elongation along the nematic director. The effective crosslinking is established by small terminal blocks formed of terphenyl moieties, which phase separate into semicrystalline micelles acting as multifunctional junction points of the network. The resulting transient network retains the director alignment and shows a significant shape‐memory effect, characteristic and exceeding that of covalently bonded nematic elastomers. Its plasticity at temperatures above the nematic–isotropic transition allows drawing thin well‐aligned fibers from the melt. The fibers have been characterized and their thermal actuator behavior—reversible contraction of heating and elongation on cooling—has been investigated.
Sporadic onset of erythermalgia: A gain‐of‐function mutation in Nav1.7
Authors: Han Chongyang , Rush Anthony M. , Dib‐Hajj Sulayman D. , Li Song , Xu Zhe , Wang Yun , Tyrrell Lynda , Wang Xiaoliang , Yang Yong , Waxman Stephen G. 
Published: January 2006

Abstract Objective Inherited erythermalgia (erythromelalgia) is an autosomal dominant disorder in which patients experience severe burning pain in the extremities, in response to mild thermal stimuli and exercise. Although mutations in sodium channel Nav1.7 have been shown to underlie erythermalgia in several multigeneration families with the disease that have been investigated to date, the molecular basis of erythermalgia in sporadic cases is enigmatic. We investigated the role of Nav1.7 in a sporadic case of erythermalgia in a Chinese family.MethodsGenomic DNA from patients and their asymptomatic family members were sequenced to identify mutations in Nav1.7. Whole‐cell patch clamp analysis was used to characterize biophysical properties of wild‐type and mutant Nav1.7 channels in mammalian cells.ResultsA single amino acid substitution in the DIIS4‐S5 linker of Nav1.7 was present in two children whose parents were asymptomatic. The asymptomatic father was genetically mosaic for the mutation. This mutation produces a hyperpolarizing shift in channel activation and an increase in amplitude of the response to slow, small depolarizations.InterpretationFounder mutations in Nav1.7, which can confer hyperexcitability on peripheral sensory neurons, can underlie sporadic erythermalgia. Ann Neurol 2006
Manipulation of the small intestine as a cause of the increased inflammatory response after open compared with laparoscopic surgery
Authors: Hiki N , Shimizu N , Yamaguchi H , Imamura K , Kami K , Kubota K , Kaminishi M 
Published: January 2006

Abstract

Background
Laparoscopic surgery of the gastrointestinal tract involves a reduced immune response compared with open surgery. The aim of this study was to assess manual handling of the gut in open procedures as the principal cause of the enhanced immune response.

Methods
Eighteen Landrace pigs underwent gastrectomy by three different methods: conventional open wound with bowel manipulation, laparoscopically assisted gastrectomy, and gastrectomy without manipulation using a combination of open wound and laparoscopic surgical devices. Local inflammatory changes were assessed by ascites formation, intestinal adhesion development and intestinal inflammatory gene expression. Associated systemic inflammatory changes were determined by measuring portal and systemic plasma endotoxin levels, plasma inflammatory cytokine levels, liver inflammatory gene expression and transaminase levels.

Results
Significantly more postoperative intra-abdominal fluid and adhesions were seen in the open group. The expression of inflammatory cytokines was significantly greater in the intestine and liver in the open group. Portal and systemic levels of endotoxin, inflammatory cytokines and transaminases were also higher.

Conclusion
Manual handling of organs during gastrectomy is an important contributor to the molecular and humoral inflammatory response to surgery, supporting the use of minimally invasive techniques in gastrointestinal surgery.
Progressive rise in gut hormone levels after Roux-en-Y gastric bypass suggests gut adaptation and explains altered satiety
Authors: Borg C M , le Roux C W , Ghatei M A , Bloom S R , Patel A G , Aylwin S J B 
Published: January 2006

AbstractBackgroundBariatric surgery is the most effective treatment for achieving long-term weight loss in morbidly obese patients. This study investigated prospective changes in gut hormones and metabolic indices after Roux-en-ϒ gastric bypass (RYGB).MethodsSix patients were seen before, and at 1, 3 and 6 months after operation. Blood was collected after a 12-h fast and at regular intervals after a mixed 420-kcal meal. Hormonal responses were determined, and comparisons between basal levels and areas under the curve were made. Visual analogue scores were used to assess satiety, hunger and nausea.ResultsMean body mass index decreased from 48·3 kg/m2 before surgery to 36·4 kg/m2 6 months after RYGB. This was accompanied by a decrease in fasting leptin (P &lt; 0·001) and insulin (P = 0·021) levels. At 1, 3 and 6 months after operation, progressively increasing peptide YY (P &lt; 0·001), enteroglucagon (P = 0·045) and glucagon-like peptide 1 (P = 0·042) responses were observed. There was no change in fasting ghrelin levels (P = 0·144). Postprandial satiety was significantly increased by 1 month after surgery and this was maintained until the end of the study (P &lt; 0·001).ConclusionRYGB resulted in substantial weight loss with enhanced postprandial satiety, a sustained weight plateau, and proportionate reduction in fasting insulin and leptin levels. Lack of the expected increase in appetite and food intake as components of a counter-regulatory response may be explained by gut adaptation and the consequent graded rise in the levels of gut hormones that promote satiety.