bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of weak $16{2\over3}$ Hz magnetic fields on growth parameters of young sunflower and wheat seedlings
Authors: Fischer G. , Tausz M. , Köck M. , Grill Dieter 
Published: November 2004

AbstractPrevious studies on effects of magnetic fields on plants focussed on the power frequencies (50–60 Hz), but in Austria and Germany electric railways are powered by a frequency of 16⅔ Hz. In the present study, sunflower and wheat seedlings were exposed to 16⅔ Hz sinusoidal 20 μT (rms) vertical magnetic fields. Seeds were germinated in a germination roll and grown for 12 days under continued exposure. Seven series with sunflower and six series with wheat were done over 2 years. Sunflower seedlings exposed to experimental magnetic field showed small, but significant increases in total fresh weights, shoot fresh weights, and root fresh weights, whereas dry weights and germination rates remained unaffected. Experimentally treated wheat exhibited marginally (but significantly) higher root fresh and dry weights, total fresh weights, and higher germination rates. Bioelectromagnetics 25:638–641, 2004. © 2004 Wiley‐Liss, Inc.
Comment: A biological guide for electromagnetic safety: the stress response
Authors: Blank Martin , Goodman Reba 
Published: November 2004

AbstractQuestions of safety of electromagnetic (EM) fields should be based on relevant biological properties, i.e., specific cellular reactions to potentially harmful stimuli. The stress response is a well documented protective reaction of plant and animal cells to a variety of environmental threats, and it is stimulated by both extremely low frequency (ELF) and radio frequency (RF) EM fields. It involves activation of DNA to initiate synthesis of stress proteins. Thermal and non‐thermal stimuli affect different segments of DNA and utilize different biochemical pathways. However, both ELF and RF stimulate the same non‐thermal pathway. Since the same biochemical reactions are stimulated in different frequency ranges with very different specific absorption rates (SARs), SAR level is not a valid basis for safety standards. Studies of EM field interactions with DNA and with model systems provide insight into a plausible mechanism that can be effective in ELF and RF ranges. Bioelectromagnetics 25:642–646, 2004. © 2004 Wiley‐Liss, Inc.
Compensating bends in a 16‐base‐pair DNA oligomer containing a T3A3 segment: A NMR study of global DNA curvature
Authors: McAteer Kathleen , Aceves‐Gaona Alejandro , Michalczyk Ryszard , Buchko Garry W. , Isern Nancy G. , Silks Louis A. “Pete” , Miller John H. , Kennedy Michael A. 
Published: November 2004

AbstractIn‐phase ligated DNA containing TnAn segments fail to exhibit the retarded polyacrylamide gel electrophoresis (PAGE) migration observed for in‐phase ligated AnTn segments, a behavior thought to be correlated with macroscopic DNA curvature. The lack of macroscopic curvature in ligated TnAn segments is thought to be due to cancellation of bending in regions flanking the TpA steps. To address this issue, solution‐state NMR, including residual dipolar coupling (RDC) restraints, was used to determine a high‐resolution structure of [d(CGAGGTTTAAACCTCG)2], a DNA oligomer containing a T3A3 tract. The overall magnitude and direction of bending, including the regions flanking the central TpA step, was measured using a radius of curvature, Rc, analysis. The Rc for the overall molecule indicated a small magnitude of global bending (Rc = 138 ± 23 nm) towards the major groove, whereas the Rc for the two halves (72 ± 33 nm and 69 ± 14 nm) indicated greater localized bending into the minor groove. The direction of bending in the regions flanking the TpA step is in partial opposition (109°), contributing to cancellation of bending. The cancellation of bending did not correlate with a pattern of roll values at the TpA step, or at the 5′ and 3′ junctions, of the T3A3 segment, suggesting a simple junction/roll model is insufficient to predict cancellation of DNA bending in all TnAn junction sequence contexts. Importantly, Rc analysis of structures refined without RDC restraints lacked the precision and accuracy needed to reliably measure bending. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Occurrence of circadian rhythms in hairy root cultures grown under controlled conditions
Authors: Lanoue Arnaud , Shakourzadeh Khalil , Marison Ian , Laberche Jean‐Claude , Christen Philippe , Sangwan‐Norreel Brigitte , Boitel‐Conti Michèle 
Published: November 2004

AbstractHairy roots obtained by transformation via Agrobacterium rhizogenes provide an artificial plant material devoid of aerial parts with high growth on hormone‐free media. Fundamental knowledge of hairy root physiology is essential to develop and control its culture. In contrast to shake‐flask cultures, a bioreactor set‐up combined with on‐line data logging provides an efficient tool to study rapid physiological variations in hairy root cultures. Datura innoxia hairy roots were grown in a bioreactor equipped with on‐line data analyses of pH, dissolved oxygen (pO2), conductivity, oxygen, and carbon dioxide. The experiments were done at a constant temperature and in the absence of light cues. The results obtained showed that the carbon dioxide evolution rate (CER) presented regular oscillations during the culture. Similar oscillations were also observed for the oxygen uptake rate (OUR). These signals were treated mathematically to look for the existence of a rhythm. An autocorrelation function was used to detect any periodic components. The results demonstrate that hairy root respiration exhibited peaks of 1 day. These oscillations, having a period of about 24 h, were also observed in pH and conductivity signals, although not for the pO2 signal. The data acquired in the absence of hairy roots showed that the observed periodic behavior was not an artifact. No effect on rhythms was observed by the imposition of an external “day/night” cycle. The fact that oscillations persisted in the absence of external stimuli, with a free‐running period of 24 h, suggests that a circadian rhythm exists in hairy roots of D. innoxia. © 2004 Wiley Periodicals, Inc.
Fluorescence and CD spectroscopic analysis of the α‐chymotrypsin stabilization by the ionic liquid, 1‐ethyl‐3‐methylimidazolium bis[(trifluoromethyl)sulfonyl]amide
Authors: De Diego Teresa , Lozano Pedro , Gmouh Said , Vaultier Michel , Iborra José L. 
Published: November 2004

AbstractThe stability of α‐chymotrypsin in the ionic liquid, 1‐ethyl‐3‐methyl‐imidizolium bis[(trifluoromethyl)sulfonyl]amide ([emim][NTf2]), was studied at 30 and 50°C and compared with the stability in other liquid media, such as water, 3
M sorbitol, and 1‐propanol. The kinetic analysis of the enzyme stability pointed to the clear denaturative effect of 1‐propanol, while both 3M sorbitol and [emim][NTf2] displayed a strong stabilizing power. For the first time, it is shown that enzyme stabilization by ionic liquids seems to be related to the associated structural changes of the protein that can be observed by differential scanning calorimetry (DSC) and fluorescence and circular dichroism (CD). The [emim][NTf2] enhanced both the melting temperature and heat capacity of the enzyme compared to the other media assayed. The fluorescence spectra clearly showed the ability of [emim][NTf2] to compact the native structural conformation of α‐chymotrypsin, preventing the usual thermal unfolding which occurs in other media. Changes in the secondary structure of this β/β protein, as quantified by the CD spectra, pointed to the great enhancement (up 40% with respect to that in water) of β‐strands in the presence of the ionic liquid, which reflects its stabilization power. © 2004 Wiley Periodicals, Inc.
Hoechst 33258 Selectively Inhibits Group I Intron Self‐Splicing by Affecting RNA Folding
Authors: Disney Matthew D. , Childs Jessica L. , Turner Douglas H. 
Published: November 2004

AbstractFungal pathogens are increasing in prevalence due to an increase in resistant strains and the number of immunocompromised humans. Candida albicans is one of these pathogens, and ∼40 % of strains contain a group I self‐splicing intron, which is a potential RNA drug target, in their large subunit rRNA precursor. Here, we report that Hoechst 33258 and derivatives thereof are selective inhibitors of C. albicans group I intron self‐splicing with an IC50 of 17 μM in 2 mM Mg2+. Chemical probing of the intron in the presence of Hoechst 33258 reveals that the folding of several nucleotides in the P4/P6 region of the intron is affected. A nucleotide near the J4/5 region is protected from chemical modification in the presence of Hoechst 33258 and several nearby are more reactive; this suggests that this region is the molecule's binding site. These results expand the available information on small‐molecule targeting of RNA and suggest that the RNAtargeting scaffold provided by Hoechst may prove valuable in designing compounds that inhibit the functions of RNA.
A Kinetically Stabilized Ferrocenyl Diphosphene: Synthesis, Structure, Properties, and Redox Behavior
Authors: Nagahora Noriyoshi , Sasamori Takahiro , Takeda Nobuhiro , Tokitoh Norihiro 
Published: November 2004

AbstractA new, stable ferrocenyl diphosphene [Tbt‐PP‐Fc] (1) (Tbt=2,4,6‐tris[bis(trimethylsilyl)methyl]phenyl, Fc = ferrocenyl) was synthesized by the dehydrochlorination reaction of the corresponding diphosphane, [Tbt‐P(H)‐P(Cl)‐Fc] (8), with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in good yield. Diphosphene 1 is very stable in the solid state and also in solution. In the 31P NMR spectrum (C6D6), diphosphene 1 showed a low‐fielded AB quartet at δ 501.7 and 479.5 ppm with the coupling constant 1JPP=546 Hz, which is characteristic of an unsymmetrically substituted trans‐diphosphene. The molecular structure of 1 was established by X‐ray crystallographic analysis, which showed a trans‐diphosphene with a C‐P‐P‐C torsion angle of 177.86(17)°. The phosphorusphosphorus bond length of 1 [2.0285(15) Å] which is considerably shorter than the typical PP single‐bond lengths (ca. 2.22–2.24 Å) and within the range of reported PP double‐bond lengths (1.985–2.051 Å) for diaryl diphosphenes, evidenced the PP double‐bond character of 1 in the solid state. In addition, the cyclic voltammograms of 1 showed reversible reduction and oxidation couples at −1.95 and +0.34 V versus SCE, respectively. The electrochemical results for 1 were reasonably supported by the DFT calculations, which suggested that the LUMO and HOMO orbitals should be mainly π* orbital of the diphosphene moiety and d orbitals of the iron(II) atom, respectively.
A Modular Approach to DNA‐Programmed Self‐Assembly of Macromolecular Nanostructures
Authors: Gothelf Kurt V. , Brown Raymond S. 
Published: November 2004

AbstractDNA‐programmed organic reactions are new and powerful tools for assembling chemical compounds into predetermined complex structures and a brief review of their use is given. This approach is particular efficient for the selection and covalent coupling of multiple components. DNA‐templated synthesis is used for polymerization of PNA tetramers and for copying of the connectivity information in DNA. Direct DNA‐programmed multicomponent coupling of custom designed organic modules is described. The macromolecular structures obtained are highly conjugated potentially conducting nanoscaffolds. Some future developments in this area are discussed.
A Practical Synthesis of (+)‐Biotin from L‐Cysteine
Authors: Seki Masahiko , Hatsuda Masanori , Mori Yoshikazu , Yoshida Shin‐ichi , Yamada Shin‐ichi , Shimizu Toshiaki 
Published: November 2004

Abstractα‐Amino aldehyde 4, which is readily derived from L‐cysteine through cyclization and elaboration of the carboxy group, was subjected to the Strecker reaction, which, via sodium bisulfite adduct 16, afforded α‐amino nitrile 5 with high diastereoselectivity (syn/anti=11:1) and in high yield. Amide 6, derived from 5, was converted to thiolactone 8, a key intermediate in the synthesis of (+)‐biotin (1), by a novel S,N‐carbonyl migration and cyclization reaction. The Fukuyama coupling reaction of 8 with the zinc reagent 21, which has an ester group, in the presence of a heterogeneous Pd/C catalyst allowed the efficient installation of the 4‐carboxybutyl chain to provide 9. Compound 9 was hydrogenated and the protecting groups removed to furnish 1 in 10 steps and in 34 % overall yield from L‐cysteine.
Risk factors associated with earlier age of onset in familial pancreatic carcinoma
Authors: James Ted A. , Sheldon David G. , Rajput Ashwani , Kuvshinoff Boris W. , Javle Milind M. , Nava Hector R. , Smith Judy L. , Gibbs John F. 
Published: November 2004

AbstractBACKGROUNDAn estimated 5–10% of all pancreatic adenocarcinomas have a hereditary association. The objective of the current study was to characterize the clinical and pathologic features of familial pancreatic carcinoma and to determine potential differences in demographics, risk factors, and outcomes between familial and sporadic pancreatic carcinoma populations.METHODSA retrospective review was performed to identify patients diagnosed with pancreatic carcinoma who had an associated familial disposition. Demographic analyses and assessment of clinical features and treatment outcomes were performed for the familial subgroup, and the results were compared with observations made in the nonfamilial, or ‘sporadic’, population.RESULTSThirty of 826 patients (3.6%) had familial pancreatic carcinoma. Baseline demographics, resectability, and metastases were similar in both the familial cohort and the sporadic cohort. The mean age of onset was slightly lower in the familial cohort (57.6 years, compared with 61 years in the sporadic cohort). However, the familial population had a significantly greater proportion of patients who were diagnosed at age < 50 years compared with the sporadic population (36.7% vs. 18.3%; P = 0.017). A positive smoking history was more commonly associated with familial pancreatic carcinoma (87% vs. 66%; P = 0.06). The overall median survival durations were 7 months and 6 months for the familial group and the sporadic group, respectively.CONCLUSIONSPatients with familial pancreatic carcinoma present at an earlier age compared with their counterparts who have nonfamilial disease. Smoking may play a significant role in the risk or promotion of pancreatic carcinoma in patients with an inherited predisposition. Cancer 2004. © 2004 American Cancer Society.
Cellular and subcellular distribution of spinophilin, a PP1 regulatory protein that bundles F‐actin in dendritic spines
Authors: Ouimet Charles C. , Katona István , Allen Patrick , Freund Tamás F. , Greengard Paul 
Published: November 2004

AbstractSpinophilin is an actin binding protein that positions protein phosphatase 1 next to its substrates in dendritic spines. It contains a single PDZ domain and has the biochemical characteristics of a cytoskeletal scaffolding protein. Previous studies suggest that spinophilin is present in most spines, but the concentration of spinophilin varies from brain region to region in a manner that does not simply reflect differences in spine density. Here, we show that spinophilin is enriched in the great majority of dendritic spines in cerebral cortex, caudatoputamen, hippocampal formation, and cerebellum, irrespective of regional differences in spinophilin concentration. In addition, spinophilin is present postsynaptic to asymmetrical contacts on interneuronal dendritic shafts. We further show that, in hippocampus and ventral pallidum, spinophilin is occasionally present in dendritic shafts adjacent to γ‐aminobutyric acid‐containing contacts. Thus, the functional role of spinophilin may not be exclusively restricted to excitatory synapses and may be significant at a small fraction of inhibitory contacts. These data also suggest that the concentration of spinophilin per spine is variable and is likely regulated by local physiological factors and/or regional influences. J. Comp. Neurol. 479:374–388, 2004. © 2004 Wiley‐Liss, Inc.
Multiple Aromaticity and Antiaromaticity in Silicon Clusters
Authors: Zhai Hua‐Jin , Kuznetsov Aleksey E. , Boldyrev Alexander I. , Wang Lai‐Sheng 
Published: November 2004

AbstractA series of silicon clusters containing four atoms but with different charge states (Si42+, Si4, Si42−, and NaSi4−) were studied by photoelectron spectroscopy and ab initio calculations. Structure evolution and chemical bonding in this series were interpreted in terms of aromaticity and antiaromaticity, which allowed the prediction of how structures of the four‐atom silicon clusters change upon addition or removal of two electrons. It is shown that Si42+ is square‐planar, analogous to the recently discovered aromatic Al42− cluster. Upon addition of two electrons, neutral Si4 becomes σ‐antiaromatic and exhibits a rhombus distortion. Adding two more electrons to Si4 leads to two energetically close structures of Si42−: either a double antiaromatic parallelogram structure or an aromatic system with a butterfly distortion. Because of the electronic instability of doubly charged Si42−, a stabilizing cation (Na+) was used to produce Si42− in the gas phase in the form of Na+[Si42−], which was characterized experimentally by photoelectron spectroscopy. Multiple antiaromaticity in the parallelogram Na+[Si42−] species is highly unusual.
Spectroscopic Properties of Trapped Electrons on the Surface of MgO Nanoparticles
Authors: Sterrer Martin , Berger Thomas , Stankic Slavica , Diwald Oliver , Knözinger Erich 
Published: November 2004

AbstractTo characterise electron‐trapping sites on the surface of MgO nanoparticles, surface colour centres were generated using UV light in conjunction with selected hydrogen‐based electron sources. Four different colour‐centre species, including the characteristic (e−)(H+) or F${{{+\hfill \atop S\hfill}}}$(H) centre, were identified due to the distinct shape of the respective electron paramagnetic resonance (EPR) signals. The analysis of the EPR saturation behaviour down to microwave powers of 5×10−3 mW reveals an enhanced spin‐relaxation probability of the (e−)(H+) centre compared to all other F${{{+\hfill \atop S\hfill}}}$ centres that do not exhibit significant magnetic interactions with hydroxylic protons. Beside the dipolar magnetic interaction in the (e−)(H+) centre observed by EPR, the electronic interaction between the unpaired electron and the proton of a closely spaced OH group produces a redshift of the OH stretching band by about 70 to 170 cm−1, as observed by infrared spectroscopy. EPR and IR spectroscopic data obtained after the selective address of individual reaction channels for surface colour‐centre formation point to the fact that (e−)(H+) centres are formed by trapping electrons from H atoms. Consequently, the underlying surface defect does not belong to the sites of the MgO surface, which chemisorb hydrogen via a heterolytic splitting process.
Perceptual interactions between fruity and woody notes of wine
Authors: Atanasova Boriana , Thomas‐Danguin Thierry , Langlois Dominique , Nicklaus Sophie , Etievant Patrick 
Published: November 2004

AbstractThe quantitative olfactory interactions in three binary mixtures of wine aroma compounds were studied. For the ﬁrst two mixtures, whisky lactone (woody note) was mixed separately with two esters (fruity note), ethyl butyrate and isoamyl acetate. For the third mixture, guaiacol (woody note) was mixed with ethyl butyrate (fruity note). Perceived odour intensity of 24 stimuli (four supra‐threshold concentration levels of two compounds and the respective 16 mixtures) were evaluated in ﬁve replications, by a trained panel of 13 subjects. The results showed that for the three binary mixtures studied, quantitative perceptual interactions were non‐level independent, non‐symmetrical, and reached the compromise level of hypo‐addition. The experimental data highlighted that generally mixtures with high whisky lactone levels led to the compromise level of mixture intensity perception, whereas mixtures with high fruity note intensity proportions did not. A tendency to hyper‐addition was observed in iso‐intense mixtures only at the lowest intensity level. Copyright © 2004 John Wiley & Sons, Ltd.
Measurements of thermal conductivity and thermal diffusivity of alternative refrigerants in liquid phase with a transient short‐hot‐wire method
Authors: Tomimura Toshio , Maki Syou , Zhang Xing , Fujii Motoo 
Published: November 2004

AbstractA transient short‐hot‐wire method has been proposed to simultaneously measure the thermal conductivity and thermal diffusivity of liquids. The method has been applied to the refrigerant HCFC‐22, alternative refrigerants HFC‐32, HFC‐125, HFC‐134a and refrigerant mixtures HFC‐32/125 [35/65, 50/50 (HFC‐410A), 68/32 wt%], HFC‐32/125/134a [23/25/52 (HFC‐407C) wt%]. From the present study, it is shown that the measured results agree well with the literature values on thermal conductivity and those on thermal diffusivity obtained from NIST's thermophysical property database, REFPROP Ver. 6.0. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(8): 540–552, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20032
Analysis of the parameters of the sintered loop heat pipe
Authors: Zan K.J. , Zan C.J. , Chen Y.M. , Wu S.J. 
Published: November 2004

AbstractThe purpose of this paper is to establish an experimental formula for sintered dendritic nickel powder. For this reason, wick structures with different porosity ranging from 65 to 80% were fabricated by cold pressing sintering process at fixed porosity and their parameters that included porosity, pore radius, and permeability were also measured. According to both the capillary limitation and the present experimental formula of the sintered dendritic nickel powder, the wick structure parameters that would affect the heat transfer capacity of the loop heat pipe (LHP) were analyzed theoretically and then investigated experimentally. The results showed that there exists an optimal combination of wick structure parameters by which the performance of the LHP would achieve optimization. The maximum heat transfer capacity was up to 500 W and the thermal resistance was 0.12°C/W at the allowable working temperature 80°C. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(8): 515–526, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20034
Control of turbulent channel flow over a backward‐facing step by suction or injection
Authors: Sakuraba Kenichiro , Fukazawa Kazuharu , Sano Masatoshi 
Published: November 2004

AbstractExperiments have been performed for turbulent channel flow over a backward‐facing step. The backward‐facing step is controlled by equipping a slit at the bottom corner of the step. Low momentum fluids in the recirculation region are sucked or high momentum fluids are injected from the slit. The width of the slit is changed between 2, 3, and 5 mm, and the flow ratio is varied from 0.00 to 0.15. The wall static pressure and local heat transfer coefficient are measured behind the backward‐facing step. The wall shear stress is measured using a micro flow sensor. In addition, the velocity profiles and turbulent intensities are measured by a split hot film probe. It is found that the heat transfer and pressure drop characteristics are controlled by the flow ratio. When the suction flow ratio is 0.06, the highest performance is obtained. Enhancement of the heat transfer is related to the increase of turbulence intensity. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(8): 490–504, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20036