bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Pit Floor Material on Compost Quality in Semiarid West Africa
Authors: Bissala YaYa , Payne William
Published: May 2006

Composting improves nutrient recycling in semiarid Africa but requires labor and water inputs. We compared effects of pit floor materials (sand, mud, and straw bricks [banco], and cement) on quality of compost made of pearl millet [Pennisetum glaucum(L.) R. Br.] stalks and cow manure. Mean compost dry mass loss ranged from 25% in sand‐floor pits to 37% in banco‐floor pits. Final C contents were 0.25 g g−1for cement‐floor compost, 0.20 g g−1for sand‐floor compost, and 0.16 g g−1for banco‐floor compost. Final C/N ratios were 25.8 in sand‐floor compost, 20.6 in banco‐floor compost, and 24.9 in cement‐floor compost. Compost water content increased as floor porosity decreased. Dry mass and nutrient content were much greater for plants grown with sand‐floor compost, but none of the compost data taken suggested superior quality. Results suggest increased floor porosity improves compost quality. Additional study is required to improve local compost technology.
Soil Biochemical Properties as Affected by Land Leveling in a Clayey Aquert
Authors: Brye Kristofor R.
Published: May 2006

Land leveling or precision grading is an agricultural practice subsidized by the United States Government for water conservation purposes and is common in the Mississippi River Delta region of the mid‐southern United States. Though undertaken to more uniformly deliver irrigation water, land leveling represents a severe soil disturbance that alters near‐surface soil biogeochemical properties. The objectives of this study were to characterize the short‐term impacts of land leveling on the magnitude, variance, and spatial variability and distributions of soil chemical properties and to evaluate the impact of land leveling on the relationships among soil chemical and biological properties in a Sharkey clay (very‐fine, smectitic, thermic Chromic Epiaquert) used for irrigated soybean [Glycine max (L.) Merr.] and rice (Oryza sativa L.) production in the Mississippi Delta region of northeast Arkansas. Soil pH, EC, and Mehlich‐3 extractable soil K, Ca, Mg, Na, S, Fe, and Cu contents in the top 10 cm increased, while soil OM, total N and C concentrations, C/N ratio, and extractable soil P and Mn contents decreased following land leveling. Variances for soil pH, and extractable soil P, K, Na, S, Mn, Cu and Zn contents increased after leveling. Spatial variability and distributions of soil chemical properties were noticeably altered and many correlations among soil biochemical properties changed significantly after leveling. Increased variations in soil biogeochemical properties as a result of any soil disturbance will make uniform field and crop management more difficult. Precision agricultural technologies may aid in the restoration of uniform productivity and soil fertility to predisturbance levels.
Synthetic Iron Oxides as an Indicator of Reduction in Soils (IRIS)
Authors: Rabenhorst Martin C. , Burch S. N.
Published: May 2006

Various circumstances in wetland delineation or mitigation strategies require the documentation of reducing conditions in soils. An innovative approach for assessing reduction in soils known as Indicator of Reduction in Soils (IRIS) has been recently introduced. IRIS tubes are manufactured by coating polyvinylchloride (PVC) pipe with a paint prepared from an Fe oxide (mainly ferrihydrite) suspension. When the iron oxide is synthesized by adding KOH to a FeCl3 solution, the mineral phase is essentially pure ferrihydrite. Over time, and under particular conditions, the ferrihydrite is transformed to more crystalline forms such as goethite and hematite. The objectives of this study were (i) to assess the mineralogical composition of iron oxide paint synthesized for the manufacture of IRIS tubes and (ii) to assess the significance of mineralogical composition of the Fe oxide paint on desirable qualities for the construction of IRIS tubes. The effects of pH and storage time on the mineralogical alteration of ferrihydrite are examined and compared with performance of the paint by a scale for adhesion and durability. Paint composed of nearly pure ferrihydrite shows poor adhesion and durability. Data suggest that for paint to adhere well to the PVC tubing, the Fe oxide suspension must contain a minimum of 30 to 40% goethite. This desired paint composition can be facilitated during synthesis by titrating the Fe oxide suspension to pH 11 or 12 rather than pH 7.5, which is typically prescribed for the formation of synthetic ferrihydrite.
Transformation of Plant Cuticles in Soil
Authors: Stimler Keren , Xing Baoshan , Chefetz Benny
Published: May 2006

Plant cuticular materials play an important role in sorption of polar and nonpolar pollutants in soils. The objective of this study was to examine the effect of decomposition and transformation of plant cuticles on their sorption behavior with triazine herbicides and polycyclic aromatic hydrocarbons (PAHs). Sorption–desorption behavior was studied during 12 mo of incubation of cuticles isolated from tomato (Lycopersicon esculentum Mill.) fruits and pummelo [Citrus maxima (Burm.) Merr.] leaves in sandy soil. Sorption and desorption experiments and spectroscopic and chemical analyses were performed on the samples after 0, 1, 3, 6, and 12 mo of incubation. The decomposition of the cuticles (46–49% after 12 mo) did not affect the organic‐C‐normalized Freundlich capacity coefficient (KFOC) for the PAHs. In addition, throughout the incubation period, the two PAHs exhibited linear and reversible sorption isotherms with both cuticles. The isotherms of the triazines were significantly affected by the decomposition of the cuticles from pummelo leaves, whereas only minor changes were recorded for the tomato cuticle samples. For the microcosm with cuticles from the pummelo leaves, the KFOC values of the triazines increased with increasing decomposition. Preferential degradation of pectin and cutin probably facilitated the interaction between the triazines and the residual cutan and more condensed cutin moieties. Our data suggest that both cutin and cutan play important roles in the sorption of polar and highly nonpolar and aromatic compounds in soils; however, with decomposition, the more condensed structure of the cutin and mainly the cutan biopolymer govern sorption of the cuticle residues.
Innovation in Higher Education Systems in the Post-Socialist Countries in Central and Eastern Europe, 1999–2005: Possibilities for Exploration through a Complexity Theory Framework
Authors: Romenska Sandra
Published: May 2006

This article discusses the possibilities for applying a collection of theories, known as complexity theory, for the study of institutional innovation in higher education in the post-socialist countries in Eastern and Central Europe for the period 1999–2005. It presents an outline of the theory and suggests for discussion links between the framework of complexity theory and a research project under development, trying to map higher education change.
Comparing Hungary and Russia: Methodological Implications of a Qualitative Research Project
Authors: Laczik Andrea
Published: May 2006

This article addresses methodological challenges during preparation and data collection that the researcher faced while conducting a research project in Hungary and Russia. The article discusses methodological decisions on the basis of the comparative study that had to incorporate not only the researcher's aim but also the agenda of the research participants. It argues that in a qualitative study that explores and describes a new area of research, flexibility, cultural sensitivity and the accommodation of local ideas are essential. First, the article briefly describes the content of the research project and offers a short summary of the contextual understanding of Hungary and Russia. The main part of the article relates to the qualitative research method with its country-specific approach.
Analytical Reflections on Access in English Higher Education: Transnational Lessons across the Pond
Authors: Baber Lorenzo Dubois , Lindsay Beverly
Published: May 2006

Recent policy trends in international higher education suggest that the dichotomy between selective and widening participation is a global issue. The central premise of this article considers the historical and contemporary challenge of promoting higher education opportunities across socio-economic distinctions in England. Three critical questions are considered: (1) How did historical developments of higher education in England during the twentieth century, including American influences after the Second World War, shape the contemporary debate on widening participation? (2) Have the purposes of higher education altered as access shifts from elite to mass? and (3) What critical philosophies influence higher education purposes and developments, and might more balanced viewpoints assist policy makers in crafting decisions? Thus, we can garner a greater comprehension of how educational policies in the twentieth century redefined the role of higher education, contributing to the debate concerning the definition of public good –social contribution for the larger society versus economic return for the individuals. In analyzing this debate, the article also: (1) explicates watershed policies, including major education acts since the 1940s; (2) examines shifting post-secondary roles via Trow's typology of higher education development – elite, mass, and universal; and (3) explores communitarian, neo-liberal, and utilitarian philosophies to illuminate ideas regarding widening access.
ISO 9000 in Education: A Comparison between the United States and England
Authors: Thonhauser Theresa , Passmore David L.
Published: May 2006

Quality schooling has often been a subject of international concern. In an effort to meet government standards for federal funding, improve their performance, and obtain public trust, education institutions of all levels, in many countries are implementing the market-based ISO 9000 quality management system. ISO 9000 is an international quality management system created by the non-governmental organization, International Organization for Standardization (ISO). The literature surrounding ISO 9000 in education indicates that the application of this quality management system to education is debatable, the implementation process is time-consuming and difficult, and that the subject is understudied. While there have been numerous case studies on ISO 9000 in education, this was the first study to use quantitative survey research methods to examine and compare ISO 9000 implementation in education institutions in two different countries, the United States and England. Interestingly, US and English institutions turned out to be very much the same with regard to ISO 9000. For example, US and English education institutions have a similar time to ISO 9000 registration, define their customer, stakeholder, suppliers, and partners in the same manner, and are implementing ISO 9000 for similar reasons.
Methodological Challenges in Complex Comparisons: Bilingual and Intercultural Education Research in Bolivia, Peru, and Chile
Authors: Taylor Solange G.
Published: May 2006

This article examines the methodological issues encountered in carrying out a three-country comparative study of language-in-education policy implementation in Bolivia, Peru, and Chile. The analysis is divided into three sections, each of which addresses one of the primary challenges encountered in undertaking the research. These three primary challenges were the level of analysis, access to interview and documentary data, and accountability to those who assisted the author in her research. The article explores the chosen response to each of these challenges and suggests additional avenues for research and methodological development.
The Interdependency of Vocational and Liberal Aims in Higher Education
Authors: Abowitz Kathleen Knight
Published: May 2006

It is not educators' role to dissuade students from seeing college as a path to a career.

It is our role to help students see the larger purpose in the work they choose.
Assessment Matters Integration, Reflection, Interpretation: Realizing the Goals of a General Education Capstone Course
Authors: Fernandez Nancy Page
Published: May 2006

For the past twenty-three years, students at California State Polytechnic University at Pomona have benefited from a sequential, interdisciplinary general education program that culminates in a capstone course. A departmental culture focused on assessment enabled faculty members to examine this capstone experience and make changes that have substantially improved student learning.
Geochemical characterisation and erosion stability of fine‐grained groyne field sediments of the Middle Elbe River
Authors: Schwartz René
Published: May 2006

Because of the significant reduction of flow velocity relative to the main current there is an accumulation of sediment material in the centre of the groyne fields over time (years to decades) up to a maximum of 1.5 m. Based on the element‐ and compound‐specific depth functions of this fine‐grained material with high organic matter content the sedimentation history of the Elbe River sediments concerning the environmentally relevant nutrients and pollutants can be reconstructed. It could be shown that the fresh sediments are less polluted than the deeper older ones. During the extreme flood of the river Elbe in August 2002 the critical erosion shear stress in the groyne fields was high enough to remobilise a considerable portion of the sediment depot. The hazard to the environment is high due to the fact that a significant part of the remobilised polluted sediments was distributed over the recent floodplain which is normally used as pasture. Thus these groyne field sediments represent a temporary danger for the water quality of the river Elbe. But the hazard of the solids sedimented in the recent floodplain of the river can be viewed as long‐lasting.
The effects of mining in Northern Romania on the heavy metal distribution in sediments of the rivers Szamos and Tisza (Hungary)
Authors: Kraft Claudia , von Tümpling Wolf , Zachmann Dieter W.
Published: May 2006

The breach in the dam of a tailing pond in the processing plant of a gold mine in Baia Mare (NW Romania) in January 2000 lead to an ecological disaster in the rivers Szamos and Tisza. It was mainly caused by the released slurries containing cyanides and heavy metals. The investigation of surface sediment samples and depth profiles of the years 2000 and 2001 documented the pollution of the rivers Szamos and Tisza on Hungarian territory. In the Szamos and large areas of the Tisza floodplains a significant enrichment with the heavy metals Pb, Cd, Cu, and Zn is existent. The identification of the binding forms with sequential extraction showed that Cd and Zn exist in an easily available form. Therefore the remobilization is possible and an environmental hazard in the downstream areas must be considered. The anthropogenically caused portions of heavy metal concentrations decrease considerably with increasing distance to the mining region. The comparison of the concentrations of heavy metals in both years shows that the pollution is not only caused by the accident in January 2000. The increase of concentrations is based on the permanent input of pollutants into the rivers. The pollution is mainly caused by the erosion of exposed tailing dumps and the poor maintenance of the treatment plants.
Spatial distribution and bonding forms of heavy metals in sediments along the middle course of the River Elbe (km 287ċ390)
Authors: van der Veen Andrea , Ahlers Corinna , Zachmann Dieter W. , Friese Kurt
Published: May 2006

Sediments of eight groyne fields along the middle course of the River Elbe (river km 287ċ390) were geochemically studied. The 78 sediment samples were analysed for pH and grain size distribution. The grain size fraction < 2 μm was used for mineralogical and chemical analysis: semiquantitative clay mineral analysis; total element content (Al, Ca, Fe, K, Mn, Cd, Cr, Cu, Ni, Pb, Zn), total inorganic and organic C, and bonding form fractionation with a six‐step sequential chemical extraction. The latter was performed on selected samples (n = 32). The sediments along the Elbe's course are still contaminated with heavy metals far above the local geogenic background level. An enrichment factor of more than 15 was calculated for zinc. Cr and Ni are the elements with the lowest enrichment. The bonding form analysis of selected heavy metals shows a dominance of relatively immobile bonding forms, e. g. the moderately reducible and the residual fraction, which implies a relative low mobility potential. Only Zn poses a higher potential threat to the environment, since it has a higher percentage of the first three extracted phases: adsorbed, carbonate, and easily reducible fraction.
Synthetic, spectral, thermal and antimicrobial studies of bis(N,N‐dialkyldithiocarbamato)arsenic(III) and antimony(III) complexes with diphenyldithiophos‐phate and diphenyldithiophosphinate
Authors: Chauhan H. P. S. , Singh U. P.
Published: May 2006

Bis(N,N‐dialkyldithiocarbamato)arsenic(III)/antimony(III) diphenyldithiophosphate/diphenyldi‐thiophosphinate complexes of the type [R2NCS2]2MS(S)PX2 [where M = As and Sb; NR2 = N(CH3)2, N(C2H5)2 and N(CH2)4; X = OC6H5 and C6H5] have been synthesized and characterized by physico‐chemical, spectral [UV, IR and NMR (1H, 13C and 31P)] and thermal (TG, DTA and DSC) analysis. The TG analysis shows single‐step decomposition of the complex to Sb2S3. These complexes have been screened for antibacterial and antifungal activity using the disc diffusion method. All the complexes have shown good activity as antibacterial and antifungal agents, which increased on increasing the concentration. Chloroamphenicol and terbinafin were used as standards for the comparison. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and structures of cycloalkylidene‐bridged mixed cyclopentadienyl‐indenyl tetracarbonyl diruthenium complexes
Authors: Lin Jin , Luo Shuang , Cheng Bin , Wang Baiquan , Xu Shansheng , Song Haibin
Published: May 2006

A series of cycloalkylidene‐bridged mixed cyclopentadienyl‐indenyl tetracarbonyl diruthenium complexes (η5:η5‐RC5H3CR′2C9H6)Ru2(CO)2(µ‐CO)2 [R = H, R′, R′ = Me2 (1), (CH2)4 (2), (CH2)5 (3), (CH2)6 (4); R = tBu, R′, R′ = Me2 (5), (CH2)4 (6), (CH2)5 (7)] have been synthesized by reactions of the corresponding ligands RC5H4CR′2C9H7 with Ru3(CO)12 in refluxing xylene. The molecular structures of 2, 6 and 7 have been determined by X‐ray diffraction. Copyright © 2006 John Wiley & Sons, Ltd.
Using an intensity‐scale technique to assess the added benefit of high‐resolution model precipitation forecasts
Authors: Mittermaier Marion P.
Published: May 2006

Deterministic precipitation forecasts from the 12‐ and 4‐km versions of the Unified Model (UM) were compared using an intensity‐scale technique. Averaging raw model output is always recommended to minimise grid‐scale errors. The retained detail in averaged 4‐km forecasts produces an improved prediction of larger accumulations. © Crown Copyright 2006. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd.
The interaction between N‐n‐undecyl‐N′‐(sodium p‐aminobenzenesulfonate) thiourea and serum albumin studied using various spectroscopies and the molecular modeling method
Authors: Cui Fengling , Cui Yanrui , Luo Hongxia , Yao Xiaojun , Fan Jing , Lu Yan
Published: May 2006

The preparation and characteristics of N‐n‐undecyl‐N′‐(sodium‐p‐aminobenzenesulfonate) thiourea (UPT), a new water‐soluble reagent with a saturated fatty hydrocarbon group, were described. The interactions of UPT with bovine serum albumin (BSA) and human serum albumin (HSA) were studied using fluorescence spectroscopy in combination with ultraviolet (UV) absorption spectroscopy, circular dichroism (CD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and the molecular modeling method. UPT exhibited a strong ability to quench the intrinsic fluorescence of both BSA and HSA through a static quenching procedure. The binding constants of UPT and BSA or HSA were determined at different temperatures based on the relevant fluorescence data. The binding sites were obtained and the acting force was suggested to be mainly hydrophobic interaction, which was consistent with the result of the molecular modeling study, and there were also a number of hydrogen bonds between UPT and HSA. The results of determination of the proteins in bovine serum or human serum by this method were very close to those obtained by using Coomassie Brilliant Blue G‐250 colorimetry. A practical method was proposed for the determination of UPT in bovine serum or human serum samples with satisfactory results. © 2006 Wiley Periodicals, Inc. Biopolymers 83: 170–181, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Muscarinic Receptors: A Comparative Analysis of Structural Features and Binding Modes through Homology Modelling and Molecular Docking
Authors: Pedretti Alessandro , Vistoli Giulio , Marconi Cristina , Testa Bernard
Published: May 2006

Three‐dimensional models of the five human muscarinic receptors were obtained from their known sequences. Homology modelling based on the crystallographic structure of bovine rhodopsin yielded models compatible with known results from site‐directed mutagenesis studies. The only exceptions were the cytoplasmic loop 3 (CL3) in the five receptors, and the large C‐terminal domain in M1. Here, homology modelling with other closely related proteins allowed to solve these gaps. A detailed comparative discussion of the five models is given. The second part of the work involved docking experiments with the physiological ligand acetylcholine, again yielding results entirely compatible with results from mutagenesis experiments. The study revealed analogies and differences between the five receptors in the residues, and interactions leading to the recognition and binding of acetylcholine.
Inhibition of Histidine Ammonia Lyase by Heteroaryl‐alanines and Acrylates
Authors: Katona Adrian , Toşa Monica Ioana , Paizs Csaba , Rétey János
Published: May 2006

Histidine ammonia lyase (HAL) catalyzes the elimination of ammonia from the substrate to form (E)‐urocanate. The interaction between HAL and acrylic acids or alanines substituted with heteroaryl groups in the β‐position was investigated. These proved to be strong competitive inhibitors when the heteroaryl groups were furanyl, thiophenyl, benzofuranyl, and benzothiophenyl, carrying the alanyl or acrylic side chains either in 2 or 3 positions, with Ki values between 18 and 139 μM. The exception was (furan‐3‐yl)alanine which was found to be inert. Tryptophan and 1‐methyltryptophan, as well as the corresponding acrylates (=prop‐2‐enoates), are strong mixed inhibitors of HAL. Theoretically, L‐histidine can be dissected into 4‐methyl‐1H‐imidazole and glycine. Whereas these two compounds separately are only very weak inhibitors of HAL, equimolar amounts of both show a Ki value of 1.7±0.09 mM which is to be compared with the Km value of 15.6 mM for the normal reaction. We conclude that 5‐methyl‐1H‐imidazole and glycine mimic the substrate and occupy the active site of HAL in a similar orientation.
Nitroimidazoles, Part 2
Authors: Al‐Masoudi Najim A. , Al‐Soud Yaseen A. , Kalogerakis Aris , Pannecouque Christophe , De Clercq Erik
Published: May 2006

A series of 5‐alkylamino and 5‐alkylsulfanyl derivatives of 1‐aryl‐2‐alkyl‐4‐nitro‐1H‐imidazoles 12–21, 31, and 34 were synthesized by a simple method with the aim to develop novel HIV non‐nucleoside reverse transcriptase inhibitors (NNRTIs). All the new compounds were tested against HIV‐1 and HIV‐2 in MT‐4 cells. Compound 21, with an arylsulfanyl group at C(5) of the 4‐nitro‐1H‐imidazole backbone showed an EC50 value of 0.22 μg/ml against HIV‐1 with a therapeutic index of 13. This means that compound 21 was cytotoxic to MT‐4 cells at a CC50 value of 2.57 μg/ml; also compounds 8, 22–25, 28, and 29 were cytotoxic to MT‐4 cells within the 0.4–4 μg/ml concentration range. Compounds 8, and 12–21 were evaluated, as a rule, but found inactive at non‐toxic concentrations against hepatitis C virus, herpes simplex type 1 and 2, cytomegalovirus (CMV), varicella‐zoster virus (VZV), vaccinia virus, and vesicular stomatitis virus, and a number of other viruses. Yet, the therapeutic index of compounds 17 and 21 for CMV and VZV approached the tenfold cut‐off point. Compounds 8 and 21 exhibited some cytostatic activity against leukemia and melanoma cell lines.
Use of Phospholipid Transfer Protein as a Probe to Study the Lipid Dynamics and Alkaline Phosphatase Activity in the Brush Border Membrane of Human Term Placenta
Authors: Sanyal Sankar N. , Goyal Meenakshi , Kanwar Shailender S. , Kaushal Shivani
Published: May 2006

Incubation of placental brush border membrane (BBM) along with sonicated vesicles of exogenous lipids (egg yolk PC) in the presence of phospholipid‐transfer protein (PL‐TP) showed a decrease in the alkaline phosphatase activity due to the change in the membrane micro‐environment, such as fluidity. Effect of substrate concentration was tested by Lineweaver–Burk plot, which showed decreased Vmax and KM. The effect of temperature was probed by the Arrhenius plot, which showed no change in transition temperature, but a decline in the energy of activation both below and above the transition temperature. The protein‐catalyzed transfer of phospholipid from the donor unilamellar vesicles resulted in a substantial increase in the BBM phospholipid and a net decrease in cholesterol/phospholipid molar ratio. The change in membrane fluidity was assessed by translational as well as rotational diffusion of membrane extrinsic fluorescent probes, pyrene and diphenyl‐hexatriene. An increased lateral mobility was recorded by the increased pyrene excimer formation. A decrease in fluorescent polarization of diphenyl‐hexatriene was observed, which led to the decrease in fluorescence anisotropy and order parameter, and therefore, an increase in membrane fluidity (rotational diffusion). Mean anisotropy parameter was also decreased in the presence of PL‐TP. Thus, the placental BBM alkaline phosphatase activity showed a distinct lipid dependence which may have important physiological consequences.
A Fatal Effect of Hornet Venom on Rat‐Brain Cortical Neurons
Authors: Cohen‐Armon Malka , Visochek Leonid , Priel Esther , Ishay Jacob S.
Published: May 2006

In a previous study, it was shown that the hornet venom or, more specifically, its venom sac extract (VSE) possesses deoxyribonuclease activity that exerts an effect both on insects as well as on mammals. We have now examined the effect of hornet VSE on primary culture of rat cortical neurons. Judging on the basis of our results, VSE induces a rapid cell death by a) permeabilizing the cell membrane, b) inducing DNA breaks, and c) cleaving the nuclear protein poly‐ADP‐ribose polymerase (PARP‐1), thereby preventing DNA repair.
Syntheses and Odor Descriptions of Cyclopropanated Compounds, Part 6
Authors: Sakauchi Hiroyuki , Asao Hiroki , Hasaba Tsutomu , Kuwahara Shigefumi , Kiyota Hiromasa
Published: May 2006

Analogs of aliphatic monoterpene dienols (geraniol, nerol, linalool, and lavandulol) and non‐branched alcohols (norleaf alcohol, matsutake alcohol, etc.) bearing a cyclopropane ring were synthesized, and their odor characteristics were examined. Most of the analogs show odor properties different from their parent compounds.
Synthesis of New Phytogrowth‐Inhibitory Substituted Aryl‐p‐Benzoquinones
Authors: de Almeida Barbosa Luiz Cláudio , de Alvarenga Elson Santiago , Demuner Antônio Jacinto , Virtuoso Luciano Sindra , Silva Antônio Alberto
Published: May 2006

Reaction of [(2‐alkyloxy)methyl]‐1,4‐dimethoxybenzene 10 (alkyl=butyl, hexyl, decyl, tridecyl, tetradecyl, hexadecyl, and octadecyl) with ceric ammonium nitrate in order to produce p‐benzoquinones (=cyclohexa‐2,5‐diene‐1,4‐diones) afforded 5‐[(alkyloxy)methyl]‐2‐(4‐formyl‐2,5‐dimethoxyphenyl)benzo‐1,4‐quinones 12a–12g in yields that varied from 46 to 97%, accompanied by 2‐[(alkyloxy)methyl]benzo‐1,4‐quinones 11a–11g in only small quantities (≤5%). These quinones resemble the natural phytotoxic compound sorgoleone, found in Sorghum bicolor. This reaction exemplifies a general procedure for the synthesis of novel aryl‐substituted p‐benzoquinones. The selective effects of compounds 12a–12g, at the concentration of 5.5 ppm, on the growth of Cucumis sativus, Sorghum bicolor, Euphorbia heterophylla, and Ipomoea grandifolia were evaluated. All compounds caused some inhibition upon the aerial parts and root growth of the tested plants. The most active compound, 2‐(4‐formyl‐2,5‐dimethoxyphenyl)‐5‐[(tridecyloxy)methyl]‐benzo‐1,4‐quinone (12d), caused between 3 and 18%, and 12 and 29% inhibition on the roots and aerial parts development of Cucumis sativus and Sorghum bicolor, respectively, and between 77 and 85%, and 34 and 52% inhibition on the roots and aerial parts growth of Euphorbia heterophylla and Ipomoea grandifolia, respectively.
Preliminary Investigation on Mgbede‐20 Oil‐Polluted Site in Niger Delta, Nigeria
Authors: Osuji Leo C. , Idung Iniobong D. , Ojinnaka Chukwunnoye M.
Published: May 2006

Soil physicochemical properties (pH, electrical conductivity (EC), % moisture, total organic carbon (TOC), total organic matter (TOM)), total extractable hydrocarbon content (THC), and micronutrient (Mn, Fe, Cu, Zn) levels of the Mgbede‐20 oil‐impacted site in Niger Delta, Nigeria, were investigated. Both oil‐impacted and their background control soils were found to be acidic especially at surface depth. A slightly higher EC value of 107.4±15.0 μS cm−1 was obtained for the subsurface‐polluted soils. Of the micronutrients investigated, only Fe exceeded its acceptable limit (>100 mg/kg). The observed increase in moisture content resulting from the oil's aggregation of soil particles may lower soil porosity, and increase resistance to penetration and hydrophobicity. Soil pH can be adjusted by aeration to complete the microbially mediated oxidation of the organic acids, followed by the addition of agricultural lime to provide some buffering capacity to the soil.
Lewis Acid Stabilized OPI3: Implications for the Nature of Free OPI3
Authors: Gonsior Marcin , Müller Lutz , Krossing Ingo
Published: May 2006

While reinvestigating the published synthesis of OPI3, it became evident from the experiments that phosphoryl triodide may only be formed as an intermediate and that the end products of the reaction of OPCl3 with LiI are PV oxides, PI3, I2, and LiCl. This is also in agreement with MP2/TZVPP calculations, which assign ΔrH° (ΔrG°) [ΔrG° in CHCl3] for the disproportionation of OPI3 as −7 (−18) [−17 kJ mol−1] (assuming P4O10 as the PV oxide). The first products of this reaction visible in a low‐temperature in situ 31P NMR experiment are P2I4 and PI3, as well as traces of a compound that may be OPCl2I. By contrast, it was possible to prepare and structurally characterize Lewis acid [A] stabilized [A]←OPX3 adducts, where [A] is Al(ORF)3 for X=Br and Al(ORF)2(μ‐F)Al(ORF)3 for X=I (RF=C(CF3)3). These adducts are formed on decomposition of PX4+[Al(ORF)4]−; high yields of Br3PO→Al(ORF)3 (δ(31P)=−65) were obtained, while I3PO→Al(ORF)3 (δ(31P)=−337) and I3PO→Al(ORF)2(μ‐F)Al(ORF)3 (δ(31P)=−332) are only formed as by‐products. The main product of the room‐temperature decomposition of PI4+[Al(ORF)4]− is PI4+[(RFO)3Al(μ‐F)Al(ORF)3]−, which was also characterized by X‐ray crystallography and was independently prepared from Ag+[(RFO)3Al(μ‐F)Al(ORF)3]−, PI3, and I2.
Self‐Assembly of Semifluorinated Dendrons Attached to Electron‐Donor Groups Mediates Their π‐Stacking via a Helical Pyramidal Column
Authors: Percec Virgil , Glodde Martin , Peterca Mihai , Rapp Almut , Schnell Ingo , Spiess Hans W. , Bera Tushar K. , Miura Yoshiko , Balagurusamy Venkatachalapathy S. K. , Aqad Emad , Heiney Paul A.
Published: May 2006

Semifluorinated first‐generation self‐assembling dendrons attached via a flexible spacer to electron‐donor molecules induce π‐stacking of the donors in the center of a supramolecular helical pyramidal column. These helical pyramidal columns self‐organize in various columnar liquid crystal phases that mediate self‐processing of large single crystal liquid crystal domains of columns and self‐repair their intracolumnar structural defects. In addition, all supramolecular columns exhibit a columnar phase at lower temperatures that maintains the helical pyramidal columnar supramolecular structure and displays higher intracolumnar order than that in the liquid crystals phases. The results described here demonstrate the universality of this concept, the power of the fluorous phase or the fluorophobic effect in self‐assembly and the unexpected generality of pyramidal liquid crystals.
Formation of Rack‐ and Grid‐Type Metallosupramolecular Architectures and Generation of Molecular Motion by Reversible Uncoiling of Helical Ligand Strands
Authors: Stadler Adrian‐Mihail , Kyritsakas Nathalie , Graff Roland , Lehn Jean‐Marie
Published: May 2006

The interaction of appropriate metal ions (PbII, ZnII) with helical ligand strands, obtained by hydrazone polycondensation, generates polymetallic supramolecular architectures of rack and grid types, by uncoiling of the ligand. The interconversion between the helical free ligand and the linearly extended ligand in the complexes produces reversible ion‐induced, nanomechanical molecular motions of large amplitude. It has been integrated in an acid–base neutralisation fuelled process, which links the extension/contraction of the ligand strands to alternating changes in pH.
Gold Catalysis: Phenol Synthesis in the Presence of Functional Groups
Authors: Hashmi A. Stephen K. , Weyrauch Jan P. , Kurpejović Elzen , Frost Tanja M. , Miehlich Burkhard , Frey Wolfgang , Bats Jan W.
Published: May 2006

The effect of different substituents, such as bromo, chloromethyl, hydroxymethyl, formyl, acetyl, carboxy, and acylated hydroxymethyl and ammonium groups, on the furan ring of substrates in gold‐catalyzed phenol synthesis has been investigated. The furan ring was also replaced by different heterocycles, such as pyrroles, thiophenes, oxazoles, and a 2,4‐dimethoxyphenyl group; gold catalysis then delivered no phenols, but occasionally other products were obtained. [Ru3(CO)12] also catalyzed the conversion of 1 at a low rate, [Os3(CO)12] failed as a catalyst, and with [Co2(CO)8] the alkyne complex 19 can be obtained, it does not lead to any phenol but reacts with norbornene to give the product of a Pauson–Khand reaction. Efforts to prepare vinylidene complexes of 1 provided the only evidence for these species; in the presence of a phosphane ligand with ruthenium an interesting deoxygenation to 22 was observed. The phenol 2 c was converted to the allyl ether, a building block for para‐Claisen rearrangements, and to the aryl triflate, a building block for cross‐coupling reactions.
Aromaticity of Giant Polycyclic Aromatic Hydrocarbons with Hollow Sites: Super Ring Currents in Super‐Rings
Authors: Hajgató Balázs , Deleuze Michael S. , Ohno Koichi
Published: May 2006

We present a systematic theoretical study based on semi‐empirical, Hartree–Fock (HF), and density functional theory (DFT) models of a series of polycyclic aromatic hydrocarbons (PAHs) that exhibit hollow sites. In this study we focus particularly on the magnetic criteria of aromaticity, namely 1H NMR and nucleus‐independent chemical shifts (NICS), and on their relationships with other electronic properties. The computed shifts and NICS indices indicate that an external magnetic field induces exceptionally strong ring currents in even‐layered PAH doughnuts, in particular in the layer directly adjacent to the central hole of double‐layered compounds. These exceptionally strong ring currents also correlate with particularly small HOMO–LUMO gaps and electronic excitation energies and to abnormally high polarizabilities, indicating in turn that these compounds have a more pronounced metallic character. Comparison is made with further depictions of aromaticity in these systems and in [18]–[66]annulene rings by employing topological, structural, and energetic criteria.
Chiral Phosphane Alkenes (PALs): Simple Synthesis, Applications in Catalysis, and Functional Hemilability
Authors: Piras Elisabetta , Läng Florian , Rüegger Heinz , Stein Daniel , Wörle Michael , Grützmacher Hansjörg
Published: May 2006

A simple synthesis of a chiral phosphane alkene (PAL) involves: 1) palladium‐catalyzed Suzuki coupling of 10‐bromo‐5H‐dibenzo[a,d]cyclohepten‐5‐ol (1) with phenylboronic acid to give quantitatively 10‐phenyl‐5H‐dibenzo[a,d]cyclohepten‐5‐ol (2); 2) reaction of 2 with Ph2PCl under acidic conditions to give a racemic mixture of the phosphane oxide (10‐phenyl‐5H‐dibenzo[a,d]cyclohepten‐5‐yl)diphenylphosphane oxide (PhtroppoPh, 3), which is separated into enantiomers by using high‐pressure liquid chromatography (HPLC) on a chiral column; 3) reduction with trichlorosilane to give the enantiomerically pure phosphanes (R)‐ and (S)‐(10‐phenyl‐5H‐dibenzo[a,d]cyclohepten‐5‐yl)diphenylphosphane (PhtroppPh, 4). This highly rigid, concave‐shaped ligand serves as a bidentate ligand in RhI and IrI complexes. Catalysts prepared from [Rh2(μ2‐Cl)2(C2H4)4] and (S)‐4 have allowed the efficient enantioselective 1,4‐addition of arylboronic acids to α,β‐unsaturated carbonyls (Hayashi–Miyaura reaction) (5–0.1 mol % catalyst, up to 95 % ee). The iridium complex (S,S)‐[Ir(PhtroppPh)2]OTf ((S,S)‐6; OTf=SO3CF3) has been used as a catalyst in the hydrogenation of various nonfunctionalized and functionalized olefins (turnover frequencies (TOFs) of up to 4000 h−1) and moderate enantiomeric excesses have been achieved (up to 67 % ee). [Ir(PhtroppPh)2]OTf reversibly takes up three equivalents of H2. The highly reactive octahedral [Ir(H)2(OTf)(CH2Cl2)(H2‐PhtroppPh)2] could be isolated and contains two hydrogenated monodentate H2‐PhtroppPh phosphanes, one CH2Cl2 molecule, one triflate anion, and two hydrides. Based on this structure and extensive NMR spectroscopic studies, a mechanism for the hydrogenation reactions is proposed.
Stereoelectronic Effects on Type I 1,2‐Dyotropic Rearrangements in Vicinal Dibromides
Authors: Fernández Israel , Sierra Miguel A. , Cossío Fernando P.
Published: May 2006

The effects of different substituents on type I‐dyotropic rearrangements of open‐chain and cyclic 1,2‐dibromo hydrocarbons have been studied by means of DFT calculations. The activation energy (Ea) of this transformation decreases with the π‐donor ability of the substituent attached to the reacting ethylenic system. This is due to donation of electronic density by conjugation or hyperconjugation. This donation leads to longer CC and CBr bond lengths in the corresponding four‐membered transition states (TSs). Linear relationships between the Ea and either the σp Hammett substituent constants and the CC bond length of the TSs were also found. In all cases, the processes have a high value of synchronicity, which is mainly independent on the substituents. A model based on the second‐order perturbational analysis for one ethylene unit with two apical bromine radicals accounts for all the computed results.
Divergent Synthesis of L‐Sugars and L‐Iminosugars from D‐Sugars
Authors: Takahashi Hideyo , Shida Tomomi , Hitomi Yuko , Iwai Yoshinori , Miyama Namisa , Nishiyama Kazusa , Sawada Daisuke , Ikegami Shiro
Published: May 2006

An efficient divergent synthesis of L‐sugars and L‐iminosugars from D‐sugars is described. The important intermediate, δ‐hydroxyalkoxamate, prepared from D‐glucono‐/galactono‐1,5‐lactone, was cyclized under Mitsunobu conditions to give the O‐cyclized oxime compound and the N‐cyclized lactam compound as mixtures. A more detailed investigation revealed that the appropriate protecting groups and solvents controlled the specificity for the O‐/N‐cyclization of the δ‐hydroxyalkoxamate. Suitable protection at the 6‐position of δ‐hydroxyalkoxamate, derived from D‐glucono‐1,5‐lactone, afforded the corresponding O‐alkylation product alone. Thus we succeeded in applying this to the total synthesis of L‐iduronic acid. In contrast, with both TBDMS as the protecting group and RCN as the solvent the efficient conversion of D‐glucono/galactono‐1,5‐lactone into the corresponding L‐iminosugars (L‐idonolactam and L‐altronolactam) was achieved.
Steric Effects in the Uncatalyzed and DMAP‐Catalyzed Acylation of Alcohols—Quantifying the Window of Opportunity in Kinetic Resolution Experiments
Authors: Fischer Christian B. , Xu Shangjie , Zipse Hendrik
Published: May 2006

The kinetics of the reaction of several alcohols (benzyl alcohol, ethanol, 1‐phenylethanol, cyclohexanol, and 1‐methyl‐1‐phenylethanol) with a selection of anhydrides (acetic anyhydride, propionic anhydride, isobutyric anhydride, isovaleric anhydride, and pivalic anhydride) as catalyzed by 4‐(N,N‐dimethylamino)pyridine (DMAP)/triethyl amine have been studied in CH2Cl2 at 20 °C. In all cases the reaction kinetics can be described by rate laws containing a DMAP‐catalyzed term and an uncatalyzed (background) term. The rate constants for the background reaction respond sensitively to changes in the steric demand of the alcohol and the anhydride substrates, making the reaction of cyclohexanol with acetic anhydride 526 times faster than the reaction with pivalic anhydride. Steric effects are even larger for the catalyzed reaction and the reactivity difference between acetic and pivalic anhydride exceeds a factor of 8000 for the reaction of cyclohexanol. There is, however, no linear correlation between the steric effects on the catalyzed and the uncatalyzed part. As a consequence there are substrate combinations with dominating catalytic terms (such as the reaction of benzyl alcohol with isobutyric anhydride), while other substrate combinations (such as the reaction of cyclohexanol with pivalic anhydride) are characterized through a dominating background process. The implications of these findings for the kinetic resolution of alcohols are discussed.
Cover Picture: Effective Manipulation of the Electronic Effects and Its Influence on the Emission of 5‐Substituted Tris(8‐quinolinolate) Aluminum(III) Complexes (Chem. Eur. J. 17/2006)
Authors: Montes Victor A. , Pohl Radek , Shinar Joseph , Anzenbacher Pavel
Published: May 2006

Organic light‐emitting diodes (OLEDs) represent a new technology for a future generation of flat‐panel displays. Over the years, significant efforts have been invested towards developing light emitters for the primary colors red, green, and blue to display the RGB signal. In the Full Paper on page 4523 ff., P. Anzenbacher, Jr., et al. demonstrate how effective modification of one of the most prominent OLED materials, tris(quinolinolate) aluminum(III) (Alq3), results in tuning of its HOMO/LUMO energy levels, which is essential for using Alq3 derivatives as host materials for various dopants and for tuning the color of the light emitted by the devices.
Pericyclic Transition‐State‐Like Aromaticity in the Inorganic Ions Se2I42+ and S2O42‐
Authors: Zhang Qin , Lu Xin , Huang Rong‐Bin , Zheng Lan‐Sun
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Electronic Structures of KNa3In9 and Na2In, Two Metallic Phases with Classical Closed‐Shell Electronic Configurations.
Authors: Li Bin , Corbett John D.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Crystal Structures of the Ln3.33CuPb1.5S7 (Ln: Tb, Dy, Ho, Er and Lu) Compounds.
Authors: Gulay L. D. , Olekseyuk I. D.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Ae2Sb2X4F2 (Ae: Sr, Ba): New Members of the Homologous Series Ae2M1+nX3+nF2 Designed from Rock Salt and Fluorite 2D Building Blocks.
Authors: Kabbour Houria , Cario Laurent
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Structure and Bonding in Yb4MgGe4: Yb2+/Yb3+ Mixed‐Valency and Charge Separation.
Authors: Tobash Paul H. , Bobev Svilen
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Structural Phase Transition and Magnetic Properties of Double Perovskites Ba2CaMO6 (M: W, Re, Os).
Authors: Yamamura Kazuhiro , Wakeshima Makoto , Hinatsu Yukio
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Crystal Structure, Vibrational Properties and Luminescence of NaMg3Al(MoO4)5 Crystal Doped with Cr3+ Ions.
Authors: Hermanowicz K. , Maczka M. , Wolcyrz M. , Tomaszewski P. E. , Pasciak M. , Hanuza J.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Effect of Oxygen Deficiencies and the Substitution of Fluorine on the Electronic States in YBa2Cu3O7‐δ Superconductors
Authors: Larbaoui K. , Tadjer A. , Abbar B. , Aourag H. , Khelifa B. , Mathieu C.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Possible Double Magnetic Phase Transition in Dy5CuPb3.
Authors: Tran V. H. , Gulay L. D.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
The Yb—Ni—B System.
Authors: Veremchuk I. , Chaban N. , Kuzma Y. B.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Comprehensive Thermodynamic Description of the Quasiternary System PbTe—GeTe—SnTe.
Authors: Yashina Lada V. , Leute Volkmar , Shtanov Vladimir I. , Schmidtke Heinrich M. , Neudachina Vera S.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Solubility Investigations in the Na2SO4 + V2O5 + H2O System from 293 K to 323 K.
Authors: Trypuc Mieczyslaw , Chalat Malgorzata , Mazurek Krzysztof
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Thermal Decomposition of ClOOCl.
Authors: Broeske R. , Zabel F.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Structure Determination and Relative Properties of Novel Noncentrosymmetric Borates MM′4(BO3)3 (M: Na, M′: Ca and M: K, M′: Ca, Sr).
Authors: Wu L. , Chen X. L. , Xu Y. P. , Sun Y. P.
Published: May 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.