bluuebunny/crossref_metadata_2025_split huggingface dataset:
A transient coastal wetland: from estuarine to supratidal conditions in less than 2000 years—Boca do Rio, Algarve, Portugal
Authors: Allen H. D. 
Published: May 2003

AbstractPalaeoecological analysis of a 3 m sediment core from a coastal site in the western Algarve, near Lagos, Portugal, reveals the changing ecological characteristics of the wetland environment during the late Holocene. The dinoflagellate record and sedimentary characteristics show that approximately 2000 years ago the modern Boca do Rio wetlands were an estuary. By about 1200 14C years BP, transition to a lower energy environment was taking place. The pollen record at this time indicates the existence of typical salt marsh vegetation. There is a likely hiatus in the sedimentary record caused by the tsunami associated with the Lisbon earthquake of ad 1755. A barrier lake, impounded by tsunami deposits, existed for approximately 60 years before being breached, followed by a reoccurrence of saline conditions. A comparison of the mineral magnetic signature of the sediments with that of soil samples from the catchment suggests a relatively local provenance for some of the sediments, rather than the highly erodible Carboniferous rocks of the Algarve's Serra uplands. However, it is also suggested that there is a biogenic component to the magnetic mineralogy. Coastal wetlands are among the most vulnerable Mediterranean environments. The history and future of the Boca do Rio wetlands is examined in the context of alluviation history, rising sea levels, both past and future, and catchment land use. Changing patterns of cultivation, irrigation and land abandonment during the last 50 years are likely to have increased water demands within the catchment and therefore decreased river discharge to the wetlands. Consequently, the continued existence of the wetlands in their present form is in doubt, despite being part of a protected natural park. Copyright © 2003 John Wiley & Sons, Ltd.
Erodibility of soils of the upper rainforest zone, southeastern Nigeria
Authors: Igwe C. A. 
Published: May 2003

AbstractThe susceptibility of some soils in the high rainfall zone of Nigeria to soil erosion must be measured regularly for better soil management. A number of techniques have been adopted for the determination of this soil loss parameter. The aim of this study is to determine the soil characteristics that relate significantly to erodibility. Soil samples collected from 0–20 cm depth from 10 different locations in the upper rainforest area were analysed for particle size distribution, water‐stable aggregates, exchangeable cations, organic carbon, soil dispersion and aggregating indices. The soils are mainly Acrisols, Nitosols, Gleysols and Ferralsol in the FAO classification while their textures are sands to sandy‐clay‐loam. They are very unstable in water as reflected in the higher values of WSA >0·50 mm and the mean‐weight diameter that ranged from 0·50 to 2·03 mm. The dispersion ratio for the soils are between 0·26 and 0·69 while clay dispersion ratio also ranged from 0·24 to 0·80. Revised universal soil loss equation (RUSLE) erodibility model values (K) were from 0·03 to 0·06 Mg h MJ−1 mm−1. These parameters can be effectively used in predicting soil erodibility, though their predictability varied in ranking of soil erodibility. In spite of this variability these indices can be used for potential erosion hazard determination by agricultural extension staff to avoid crop failures and other negative influence of soil erosion. The soil parameters are easy to determine and will be a valuable instrument when faster approaches to erosion control measures are required. Copyright © 2003 John Wiley & Sons, Ltd.
Changes in soil fertility and Striga hermonthica prevalence associated with legume and cereal cultivation in the Sudan savannah zone of Ghana
Authors: Abunyewa A. A. , Padi F. K. 
Published: May 2003

AbstractIn the Sudano–Sahelian zones of West Africa, cultivated land is degraded due to reduced fallow periods and Striga hermonthica (Del.) Benth. infestation, and poses a serious threat to sustainable food production. To provide options for addressing these problems, we investigated the possibility of replacing the short fallow periods with food legume cultivation. We tested this in two farming communities within the Sudan savannah zone of Ghana. In the 1997 and 1998 cropping seasons, selected farmers within each community planted soybean [Glycine max. (L.) Merr.] or bambara groundnuts [Vigna subterranea (L.) Verdc.] on continuously cropped, Striga‐infested farmlands, whereas lands that were maintained under two or three years of bush fallowing were planted to millet [Pennisetum glaucum (L.) R. Br.] or sorghum [Sorghum bicolor (L.) Moench]. Analysis of soil sampled from 0–15 cm (plough layer) revealed that contents of major plant nutrients were inadequate to support long‐term crop production. Within each farming community, total nitrogen content at initial sampling showed significant negative correlation with the number of Striga seeds in the plough layer. Under legume cultivation, soil organic carbon content increased and the number of Striga seeds per square metre decreased in both communities from a mean value of 28 183 seeds m−2 to 8185 seeds m−2. Under cereal cultivation Striga seed density increased from 9383 seeds m−2 to 16 696 seeds m−2. The study provides evidence that introduction of food legume cultivation on farmlands with high S. hermonthica infestation as an alternative to bush fallow system could help achieve sustainable crop production in the Sudan savannah zones of sub‐Saharan Africa. Copyright © 2003 John Wiley & Sons, Ltd.
The use of coal fly ash in sodic soil reclamation
Authors: Kumar D. , Singh B. 
Published: May 2003

AbstractAn experiment was conducted for two years in northwest India to explore the feasibility of using coal fly ash for reclamation of waterlogged sodic soils and its resultant effects on plant growth in padi–wheat rotation. The initial pH, electrical conductivity, exchangeable sodium percentage and sodium adsorption ratio of the experimental soil were 9.07, 3.87 dS m−1, 26.0 and 4.77 (me l)−1/2, respectively. The fly ash obtained from electrostatic precipitators of thermal power plant had a pH of 5.89 and electrical conductivity of 0.88 dS m−1. The treatments comprised of fly ash levels of 0.0, 1.5, 3.0, 4.5, 6.0 and 7.5 per cent, used alone as well as in combination with 100, 80, 60, 40, 20 and 10 per cent gypsum requirement of the soil, respectively. There was a slight reduction in soil pH while electrical conductivity of the soil decreased significantly with fly ash as measured after padi and wheat crops. The sodium adsorption ratio of the soil decreased with increasing fly ash levels, while gypsum treatments considerably added to its favourable effects. Fly ash application increased the available elemental status of N, K, Ca, Mg, S, Fe, Mn, B, Mo, Al, Pb, Ni, Co, but decreased Na, P and Zn in the soil. An application of fly ash to the soil also increased the concentrations of above elements except Na, P and Zn in the seeds and straw of padi and wheat crops. The available as well as elemental concentrations in the plants was maximum in the 0 per cent fly ash + 100 per cent gypsum requirement treatment except Na and heavy elements like Ni, Co, Cr. The treatment effects were greater in the fly ash + gypsum requirement combinations as compared to fly ash alone. Saturated hydraulic conductivity and soil water retention generally improved with the addition of fly ash while bulk density decreased. Application of fly ash up to 4.5 per cent level increased the straw and grain yield of padi and wheat crops significantly in both years. The results indicated that for reclaiming sodic soils of the southwest Punjab, gypsum could possibly be substituted up to 40 per cent of the gypsum requirement with 3.0 per cent acidic fly ash. Copyright © 2003 John Wiley & Sons, Ltd.
Sodium removal from a calcareous saline–sodic soil through leaching and plant uptake during phytoremediation
Authors: Qadir M. , Steffens D. , Yan F. , Schubert S. 
Published: May 2003

AbstractSaline–sodic and sodic soils are characterized by the occurrence of sodium (Na+) to levels that can adversely affect several soil properties and growth of most crops. As a potential substitute of cost‐intensive chemical amelioration, phytoremediation of such soils has emerged as an efficient and low‐cost strategy. This plant‐assisted amelioration involves cultivation of certain plant species that can withstand ambient soil salinity and sodicity levels. It relies on enhanced dissolution of native calcite within the root zone to provide adequate Ca2+ for the Na+Ca2+ exchange at the cation exchange sites. There is a lack of information for the Na+ balance in terms of removal from saline–sodic soils through plant uptake and leaching during the phytoremediation process. We carried out a lysimeter experiment on a calcareous saline–sodic soil [pH of saturated soil paste (pHs) = 7.2, electrical conductivity of the saturated paste extract (ECe) = 4.9 dS m−1, sodium adsorption ratio (SAR) = 15.9, CaCO3 = 50 g kg−1]. There were three treatments: (1) control (without application of a chemical amendment or crop cultivation), (2) soil application of gypsum according to the gypsum requirement of the soil and (3) planting of alfalfa (Medicago sativa L.) as a phytoremediation crop. The efficiency of treatments for soluble salt and Na+ removal from the soil was in the order: gypsum ≈ alfalfa > control. In the phytoremediation treatment, the amount of Na+ removed from the soil through leaching was found to be the principal cause of reduction in salinity and sodicity. Copyright © 2003 John Wiley & Sons, Ltd.
Offsetting global CO2 emissions by restoration of degraded soils and intensification of world agriculture and forestry
Authors: Lal R. 
Published: May 2003

AbstractIncrease in atmospheric concentration of CO2 from 285 parts per million by volume (ppmv) in 1850 to 370 ppm in 2000 is attributed to emissions of 270 ± 30 Pg carbon (C) from fossil fuel combustion and 136 ± 55 Pg C by land‐use change. Present levels of anthropogenic emissions involve 6·3  Pg C by fossil fuel emissions and 1·8 Pg C by land‐use change. Out of the historic loss of terrestrial C pool of 136 ± 55 Pg, 78 ± 12 Pg is due to depletion of soil organic carbon (SOC) pool comprising 26 ± 9 Pg due to accelerated soil erosion. A large proportion of the historic SOC lost can be resequestered by enhancing the SOC pool through converting to an appropriate land use and adopting recommended management practices (RMPs). The strategy is to return biomass to the soil in excess of the mineralization capacity through restoration of degraded/desertified soils and intensification of agricultural and forestry lands. Technological options for agricultural intensification include conservation tillage and residue mulching, integrated nutrient management, crop rotations involving cover crops, practices which enhance the efficiency of water, plant nutrients and energy use, improved pasture and tree species, controlled grazing, and judicious use of inptus. The potential of SOC sequestration is estimated at 1–2 Pg C yr−1 for the world, 0·3–0·6 Pg C yr−1 for Asia, 0·2–0·5 Pg C yr−1 for Africa and 0·1–0·3 Pg C yr−1 for North and Central America and South America, 0·1–0·3 Pg C yr−1 for Europe and 0·1–0·2 Pg C yr−1 for Oceania. Soil C sequestration is a win–win strategy; it enhances productivity, improves environment moderation capacity, and mitigates global warming. Copyright © 2003 John Wiley & Sons, Ltd.
Dissolution and Enzymatic Degradation Studies Before and After Artificial Ageing of Silk‐ or Linen‐Reinforced Gelatin Laminates, 2
Authors: Boyanova M. , Stambolieva N. , Apostolov A. A. , Fakirov S. 
Published: May 2003

AbstractBiodegradable laminates based on gelatin and on gelatin/starch blend reinforced with fabrics (silk or linen) were prepared by melt pressing. Due to crosslinking during the thermal treatment and in some cases, to additional crosslinking with methylenedi(p‐phenyl) diisocyanate, the fresh and artificially aged samples demonstrated improved mechanical properties, as reported previously. In Part 1 of this study on the environmental behavior of these new laminated composites, the simple dissolution in a buffer solution or water of fresh and artificially aged samples was considered. During this treatment soluble, i.e., uncrosslinked molecules were removed leaving a product resulting from addition reactions and consequent crosslinking. These processes take place during the melt pressing at 180 °C and cause a decreased solubility of gelatin. The present Part 2 deals with the enzymatic treatment of the same samples. We have implicitly shown that the gelatin moiety of the laminates undergoes proteolysis and that this process depends on the laminate composition. At the end of the treatment the enzymatic buffer solution contains only peptides and virtually no high‐molecular gelatin. The degrees of degradation vs. time dependencies differ for water and enzymatic treatment of the samples, indicating different processes in either treatment. The time‐course curves of the enzymatic treatment of different laminates and the kinetic parameters derived therefrom were analyzed. Thereby the effect of many factors on the accessibility of the gelatin moiety to proteolysis was shown. These factors are: temperature treatment, artificial ageing, the nature of the reinforcing fabrics, the “additional” crosslinking with methylenedi(p‐phenyl) diisocyanate, etc. The gelatin‐linen laminate is the most sensitive to crosslinking. There is a tendency that the crosslinking smears the differences in the time‐course of the absorption behavior curves of the different samples.Degree of degradation, β′, (related to only the gelatin) vs. time, t, for laminates: (a) uncrosslinked gelatin‐linen; (b) crosslinked gelatin‐linen; (c) uncrosslinked gelatin‐silk; (d) crosslinked gelatin‐silk.magnified imageDegree of degradation, β′, (related to only the gelatin) vs. time, t, for laminates: (a) uncrosslinked gelatin‐linen; (b) crosslinked gelatin‐linen; (c) uncrosslinked gelatin‐silk; (d) crosslinked gelatin‐silk.
Reactive Compatibilization of Polyamide 6 with Isocyanate Functionalized Ethylene‐Propylene Copolymer
Authors: Ding Yongtao , Xin Zhirong , Gao Ying , Xu Xiaodong , Yin Jinghua , Costa Giovanna , Falqui Luciano , Valenti Barbara 
Published: May 2003

AbstractReactive compatibilization of ethylene‐propylene copolymer functionalized with allyl (3‐isocyanato‐4‐tolyl) carbamate (TAI) isocyanate (EPM‐g‐TAI) and polyamide 6 (PA6) was investigated in this paper. FTIR analysis revealed the evidence of a chemical reaction between the end groups of PA6 and EPM‐g‐TAI. Thermal, rheological, morphological, and mechanical properties of the resultant system were examined. DSC analysis indicated that the crystallization of PA6 in PA6/EPM‐g‐TAI blends was inhibited, due to the chemical reaction that occurs at the interface of PA6 and EPM‐g‐TAI. Rheological measurement showed that complex viscosity and storage modulus of PA6/EPM‐g‐TAI were both dramatically enhanced compared to those of PA6/EPM at the same blending composition. After examining the morphology of both blending systems, smaller particle size, more homogeneous distribution of domains and improved interfacial adhesion between matrix and domains were observed in the compatibilized system. Mechanical properties such as tensile strength, Young's modulus, flexural strength and modulus, as well as notched and un‐notched impact strength of PA6/EPM‐g‐TAI blends were also found to improve gradually with increasing the content of grafted TAI.Tensile modulus of the blends versus rubber content.magnified imageTensile modulus of the blends versus rubber content.
Reactions of polypeptide ions with electrons in the gas phase
Authors: Zubarev Roman A. 
Published: May 2003

Abstract

I.
Introduction
58

A.  Challenges in the Gas‐Phase Fragmentation of Polypeptides
58

B.  Ion–Electron Interactions
58

C.  Nomenclature
59

II.
Instrumental Realization and Applications
60

III.
Electron‐Capture Dissociation
61

A.  Electron Capture
61

B.  NCα Bond Cleavage
62

C.  SS Bond Reduction
64

D.  Dissociation of Strong Bonds in the Presence of Weak Bonding
65

E.  Frequencies of NCα Bond Cleavage
67

IV.
Electronic Excitation
68

A.  Hot‐Electron‐Capture Dissociation (HECD)
68

B.  Electronic Excitation Dissociation (EED)
69

V.
Vibrational Excitation
70

A.  Vibrational Excitation of Even‐Electron Species
70

B.  Vibrational Excitation of Radical Species
71

VI.
Electron Detachment
72

A.  Ionization
72

B.  Electron‐Detachment Dissociation (EDD)
73

VII.
Conclusions
74

References

74

Reactions of electrons in the energy range below 70 eV with polypeptide cations and anions are reviewed, as well as their applications for the structural analysis of polypeptides. At very low energies (≤ 0.1 eV), the major outcome is electron‐capture dissociation (ECD) of SS and backbone NCα bonds, leading to c′ and z· fragments. ECD is useful in sequencing and characterization of post‐translational modifications (PTMs), because c′, z· fragmentation is abundant and the fragments usually retain labile groups. Electron capture at higher energies (3–13 eV) induces secondary fragmentation in radical z· fragments; this hot ECD (HECD) allows one to distinguish between the isomeric leucine and isoleucine residues. If a hot electron is not captured, then the induced electronic excitation converts internally into vibrational energy, resulting in fragmentation of the C(O)N backbone bond (so‐called EIEIO process). Above 9–10 eV, further ionization of n‐charged cations occurs. If the formed (n + 1)+· cations capture electrons, then the CαC backbone bond is usually broken. For anions that collide with ≈20 eV electrons, the ejection of an electron leads to the creation of a radical positive charge (hole) that recombines internally with a negative charge. Such recombination leads to various backbone bond cleavages. This electron‐detachment dissociation (EDD) is analogous to ECD for negative ions. © 2003 Wiley Periodicals, Inc., Mass Spec Rev 22:57–77, 2003; Published online in Wiley InterScience (www.interscience.wiley.com)
Identification of distinct and common gene expression changes after oxidative stress and gamma and ultraviolet radiation
Authors: Heinloth Alexandra N. , Shackelford Rodney E. , Innes Cynthia L. , Bennett Lee , Li Leping , Amin Rupesh P. , Sieber Stella O. , Flores Kristina G. , Bushel Pierre R. , Paules Richard S. 
Published: May 2003

AbstractThe human genome is exposed to many different kinds of DNA‐damaging agents. While most damage is detected and repaired through complex damage recognition and repair machineries, some damage has the potential to escape these mechanisms. Unrepaired DNA damage can give rise to alterations and mutations in the genome in an individual cell, which can result in malignant transformation, especially when critical genes are deregulated. In this study, we investigated gene expression changes in response to oxidative stress, gamma (γ) radiation, and ultraviolet (UV) radiation and their potential implications in cancer development. Doses were selected for each of the three treatments, based on their ability to cause a similar G1 checkpoint induction and slow down in early S‐phase progression, as reflected by a comparable reduction in cyclin E–associated kinase activity of at least 75% in logarithmically growing human dermal diploid fibroblasts. To investigate gene expression changes, logarithmically growing dermal diploid fibroblasts were exposed to either γ radiation (5 Gy), oxidative stress (75 μM of tert‐butyl hydroperoxide (t‐butyl‐OOH)), or UV radiation (UVC) (7.5 J/m2) and RNA was harvested 6 h after treatment. Gene expression was analyzed using the NIEHS Human ToxChip 2.0 with approximately 1901 cDNA clones representing known genes and expressed sequence tags (ESTs). We were able to identify common and distinct responses in dermal diploid fibroblasts to the three different stimuli used. Within our analysis, gene expression profiles in response to γ radiation and oxidative stress appeared to be more similar than profiles expressed after UV radiation. Interestingly, equivalent cyclin E–associated kinase activity reduction with all the three treatments was associated with greater transcriptional changes after UV radiation than after γ radiation and oxidative stress. While samples treated with UV radiation displayed modulations of their mitogen activated protein kinase (MAPK) pathway, γ radiation had its major influence on cell‐cycle progression in S‐phase and mitosis. In addition, cell cultures from different individuals displayed significant differences in their gene expression responses to DNA damage. Published 2003 Wiley‐Liss, Inc.
Inactivation of helicase‐like transcription factor by promoter hypermethylation in human gastric cancer
Authors: Leung Wai K. , Yu Jun , Bai Alfa H.C. , Chan Michael W.Y. , Chan Ka‐Kui , To Ka‐Fai , Chan Francis K.L. , Ng Enders K.W. , Chung S.C. Sydney , Sung Joseph J.Y. 
Published: May 2003

AbstractHelicase‐like transcription factor (HLTF), a member of the SWI/SNF (mating type switching/sucrose nonfermenting) chromatin‐remodeling complex, is recently found to be inactivated by promoter hypermethylation in human colorectal cancer. However, the role of this putative tumor suppressor gene in other tumors has not been determined. We evaluated the role of HLTF promoter hypermethylation in gastric cancer. Expression of HLTF was examined by reverse‐transcription (RT)–polymerase chain reaction (PCR), and promoter hypermethylation in HLTF was determined by methylation–specific PCR. Bisulfite DNA sequencing was performed to determine the detailed methylation profiles of the promoter region. HLTF expression was lost in two of five gastric cell lines and in 13 (28%) of 46 primary gastric cancers. Accordingly, promoter hypermethylation was detected in the two cell lines and in nine of 13 gastric cancer samples. Of the ten normal gastric specimens and ten paired adjacent nonneoplastic tissues, methylation was detected in only one adjacent nonneoplastic tissue. Bisulfite DNA sequencing of the promoter region of HLTF showed that the CpG island was densely methylated in cell lines and cancer samples; this also appeared to correlate with expression level. Treatment of gastric cell lines that lacked HLTF expression with the demethylating agent 5‐azacytidine (5‐azaDC) restored HLTF expression. These results suggest that HLTF promoter hypermethylation is frequently demonstrated in human gastric cancer, and inactivation of HLTF or the chromatin‐remodeling complex may play a crucial role in gastric carcinogenesis. © 2003 Wiley‐Liss, Inc.