bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the self‐setting property and the in vitro bioactivity of β‐Ca2SiO4
Authors: Gou Zhongru , Chang Jiang , Zhai Wanyin , Wang Junying
Published: March 2005

This study sought to investigate the physical and chemical properties of β‐dicalcium silicate (β‐Ca2SiO4) in order to evaluate its use as an injectable bioactive cement filler. Workable β‐Ca2SiO4 pastes with a liquid‐to‐powder (L/P) ratio of 1.0–1.2 could be injected for 10–30 min (nozzle diameter 2.0 mm) and enabled initial setting times of 60–180 min. The setting process yielded cellular structures with compressive strengths of 4.8–28.8 MPa after 2–28 days. The paste was soaked in simulated body fluid (SBF), and the results demonstrated that it exhibited a moderate degradation and could induce carbonated hydroxyapatite formation. The ionic products of the paste dissolution enhanced a proliferative response of fibroblasts compared with the cells cultured alone, and this cement could also support adhesion and spreading of the mesenchymal stem cells. Finally, with the use of gentamicin as a model drug, it was found that a high dose of drug release from the paste was maintained for 14 days, and there was a sustained release over 4 weeks. This combination of properties indicates that the novel β‐Ca2SiO4 cement might be suitable for potential applications in the biomedical field, preferentially as materials for bone/dental repair and controlled drug‐delivery systems. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater
Exploring the potential energy surface of retinal, a comparison of the performance of different methods
Authors: Blomgren Fredrik , Larsson Sven
Published: March 2005

The ground state structure of retinal has been investigated. We found that DFT and CASSCF produce different results for the bond length alternation in a model system of retinal. Quantum mechanics/molecular mechanics calculations including the closest surrounding amino acids have been performed, using DFT and CASSCF to calculate the structure of retinal in the protein cavity. The planarity of the retinal molecule is affected by the surrounding protein. DFT and CASSCF produce different twist angles. The difference between CASSCF and DFT appears to be related to the positively charged nitrogen of the Schiff base, which leads to different π‐bond orders produced by the two methods. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 738–742, 2005
Site‐select procedure for non‐palpable breast lesions: Feasibility study with a 15‐mm cannula
Authors: Barranger Emmanuel , Marpeau Olivier , Chopier Jocelyne , Antoine Martine , Uzan Serge
Published: March 2005

Background

As screening mammography becomes more commonplace, increasing numbers of non‐palpable breast lesions are being found. The aim of this prospective study was to evaluate the feasibility, utility, and patient‐perceived cosmesis and satisfaction of the Site‐Select procedure in women with non‐palpable breast lesions.

Methods

Thirty‐two consecutive patients underwent the Site‐Select procedure, performed under local anesthesia by the same surgeon. The Site‐Select procedure was included in a protocol for small (<15 mm) breast imaging reporting and data system (BI‐RADS) grade 3 and 4 breast lesions. The pathologic diagnosis, specimen size, length of the procedure, perioperative and postoperative complications, subsequent interventions, patient satisfaction, and esthetic results were documented.

Results

The Site‐Select procedure was successful in all 32 patients (mean age, 56 years; range, 44–79 years). Mammographic lesions corresponded to microcalcifications in 21 patients, microcalcifications with architectural distortion in 4 patients, microcalcifications with nodules in 2 patients, and architectural distortion alone in 5 patients. The Site‐Select procedure was used on an outpatient basis. Carcinomas were diagnosed in five patients (15.6%). No complications occurred during the procedure. The only postoperative complication was a hematoma, which did not require surgical drainage. No missed cancers were detected by follow‐up mammography (mean 8 months later; range, 1–18 months). The esthetic results and patient satisfaction were excellent.

Conclusions

This study demonstrates that the Site‐Select procedure is an effective diagnostic method in selected cases. It has a low complication rate, high patient satisfaction, and excellent esthetic results. J. Surg. Oncol. 2005;90:14–19. © 2005 Wiley‐Liss, Inc.
Vegetation index differencing and linear regression for change detection in a Swedish mountain range using Landsat TM® and ETM+® imagery
Authors: Nordberg M.‐L. , Evertson J.
Published: March 2005

This paper describes the extent to which the normalized difference vegetation index (NDVI) in combination with image regression used on satellite data can indicate vegetation cover decreases caused by increased exploitation of Swedish mountains. The methods outlined in this study give a basis for detection of less sustainable mountain ecosystems by using as an indicator bare patches of humus or soil where none existed previously. Landsat 5 TM® data from 1984 and 1994 and Landsat 7 ETM+® data from the year 2000 were used in the study. The results show that the NDVI significantly separates areas with vegetation cover decrease from areas with no vegetation cover decrease in sensitive, high‐latitude mountain ecosystems, such as mountainous dry heath communities. Copyright © 2005 John Wiley & Sons, Ltd.
Land degradation indicators in Kuwait
Authors: Al‐Awadhi J. M. , Omar S. A. , Misak R. F.
Published: March 2005

In arid regions, such as Kuwait, land degradation is exacerbated by the scarcity of rainfall and intensive wind and water erosion. In Kuwait seven land degradation indicators were recognized and described. These are: soil erosion by wind and/or water; deterioration of vegetation cover; soil crusting and sealing; soil compaction; soil contamination by oil; and soil salinization. Four areas in Kuwait, namely Al Mutlaa, Ras Al‐Sabiyah, Sulaibiyah and Ahmadi‐Al‐Dahr, were studied to assess the extent and magnitude of land degradation. Remote sensing images and the following parameters were investigated in each area: vegetation cover; soil bulk density; infiltration capacity; and top soil resistance. The areas showed significant variations in vegetation cover, and increase in erosion by wind and water and soil compaction. Based on the percentage of vegetation cover and the physical properties of the soil, three classes of land degradation are identified. These classes are: severe; moderate; and slight. Overgrazing was shown as a main cause of land degradation, followed by military operations, quarrying and camping. Copyright © 2005 John Wiley & Sons, Ltd.
Quality assurance of test pieces as a basis for adequate significance of test results
Authors: Badenheim D. , Hoffmann M. J. , Oberacker R.
Published: March 2005

The relevance of the centralised acquisition of test material needed within the SFB and the quality assurance carried out for this material is discussed. Results from quality inspections for components from commercial ceramic materials are reported to demonstrate this relevance. The surface characteristics of these components are compared to surfaces resulting from hard machining operations, carried out under defined conditions in the own laboratory. From the applied mechanical examinations, the crack growth behaviour of Al2O3 evaluated by various methods is compared. Finally, the raw part production and also the hard machining of test series from newly developed sialon ceramics is presented. These materials are considered for sliding applications.
Stereotypical movements and frontotemporal dementia
Authors: Mendez Mario F. , Shapira Jill S. , Miller Bruce L.
Published: March 2005

Stereotypical movements are characteristic of autism or mental retardation but can also occur in patients with dementia, particularly frontotemporal dementia (FTD). In this study, we administered the Abnormal Involuntary Movement Scale (AIMS) to 18 patients with FTD and to 18 patients with the most common form of dementia, Alzheimer's disease (AD). The AIMS scores were gathered at the initial presentation of patients who had not received antipsychotic medications. Compared to the AD patients, the FTD patients had significantly more stereotypical movements, including frequent rubbing behaviors and some self‐injurious acts. All the FTD patients with stereotypical movements had compulsive‐like behaviors, suggesting a similar pathophysiologic cause, and most had a decrease in their stereotypical movements with the administration of sertraline, a serotonin selective reuptake inhibitor. © 2005 Movement Disorder Society
Concanavalin a inhibits pathophysiological effects of anti‐ganglioside GQ1b antibodies at the mouse neuromuscular synapse
Authors: Bullens Roland W. M. , Halstead Susan K. , O'Hanlon Graham M. , Veitch Jean , Molenaar Peter C. , Willison Hugh J. , Plomp Jaap J.
Published: March 2005

Anti‐GQ1b antibodies are present in the Miller Fisher syndrome (MFS), a monophasic neuropathy characterized by ataxia, areflexia, ophthalmoplegia, and sometimes cranial muscle weakness. We have previously shown, at the mouse neuromuscular junction (NMJ) ex vivo, that anti‐GQ1b antibodies, through complement classic pathway activation, block synaptic transmission in a way that resembles the effect of the pore‐forming α‐latrotoxin (αLTx). In order to clarify the mechanism of these αLTx‐like effects, including possible involvement of the alternative and mannose‐binding protein complement pathways, we studied the effects of concanavalin A (ConA), a lectin known to block the action of αLTx, immunoglobulins, and early complement components. With electrophysiological, immunohistological, and bioassay experiments, we showed that the αLTx‐like effects of anti‐GQ1b antibody and complement were inhibited by pre‐ and coincubation with ConA. However, ConA was not able to inhibit evolution of αLTx‐like effects when coincubated upon addition of complement at NMJs that had already bound anti‐GQ1b antibody. Our data suggest that the mannose‐binding protein pathway is not involved in the αLTx‐like effect and that the inhibiting effect of ConA principally arises through interference with presynaptic binding of anti‐GQ1b antibody. In control experiments, ConA prevented the neuroexocytotic effects of αLTx, indicating that αLTx receptors were inhibited under these conditions. We conclude that, although the physiological effects at the NMJ of anti‐GQ1b antibody and αLTx are very similar, the activity of anti‐GQ1b antibody is not mediated through activation of αLTx receptors, but rather is caused by direct presynaptic membrane damage through classic complement pathway activation. Muscle Nerve, 2005
One‐pot synthesis of linear and branched poly(amide aspartimide)s with good solubility in organic solvents
Authors: Wu Chuan‐Shao , Tsai Shr‐Hau , Liu Ying‐Ling
Published: March 2005

Linear and branched poly(amide aspartimide)s were prepared through the reaction of 4,4′‐diaminodiphenylmethane with 4‐maleimidobenzoic acid and 5‐maleimidoisophthalic acid, respectively. The synthesis was performed through a one‐pot operation by means of the Michael addition reaction between amine and maleimide groups and the dehydration condensation reaction between amine and carboxylic acid groups. The obtained polymers exhibited fairly good solubility in aprotic polar solvents at room temperature and in pyridine, tetrahydrofuran, acetone, and chloroform upon heating. High glass‐transition temperatures (≥225 °C) and thermal stability above 360 °C were found for the polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1923–1929, 2005
Atomic force microscopy study on blend morphology and clay dispersion in polyamide‐6/polypropylene/organoclay systems
Authors: Chow W. S. , Ishak Z. A. Mohd , Karger‐Kocsis J.
Published: March 2005

The phase structure and clay dispersion in polyamide‐6(PA6)/polypropylene(PP)/organoclay (70/30/4) systems with and without an additional 5 parts of maleated polypropylene (MAH‐g‐PP) as a compatibilizer were studied with atomic force microscopy (AFM). AFM scans were taken from the polished surface of specimens that were chemically and physically etched with formic acid and argon ion bombardment, respectively. The latter technique proved to be very sensitive to the blend morphology, as PP was far more resistant to ion bombardment than PA6. In the absence of the MAH‐g‐PP compatibilizer, the organoclay is located in the PA6 phase; this finding is in line with transmission electron microscopic results. Further, the PP is coarsely dispersed in PA6 and the adhesion between PA6 and PP is poor. The addition of MAH‐g‐PP resulted in a markedly finer PP dispersion and good interfacial bonding between PA6 and PP. In this blend, the organoclay was likely dispersed in the PA6‐grafted PP phase. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43:1198–1204, 2005
Photonic crystal microcavities for chip‐based cavity QED
Authors: Srinivasan Kartik , Barclay Paul E. , Painter Oskar
Published: March 2005

The suitability of recently demonstrated high quality factor (Q), ultra‐small mode volume (Veff) graded square lattice photonic crystal microcavities for cavity QED experiments is discussed. In addition to the basic importance of the Q and Veff of such cavities, other issues of both practical and fundamental relevance are considered. Included amongst these are the robustness of the cavity's performance to fabrication errors and the ability to efficiently source and collect light from the cavity through conventional fiber optics. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction effects in high‐mobility two‐dimensional electron and hole systems
Authors: Savchenko A. K. , Galaktionov E. A. , Safonov S. S. , Proskuryakov Y. Y. , Li L. , Pepper M. , Simmons M. Y. , Ritchie D. A. , Linfield E. H. , Kvon Z. D.
Published: March 2005

Electron–electron interaction in the presence of impurities is studied in two‐dimensional systems where the parameter kBTτ/ħ changes from 0.1 to 10 (τ is the momentum relaxation time). This corresponds to the intermediate and ballistic regimes of electron interaction. We analyse the interaction correction to the Drude conductivity in terms of recent theories and show that it is strongly dependent on the character of the impurity potential. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface analysis of prosthetic wear debris
Authors: Tokash J. C. , Stojilovic N. , Ramsier R. D. , Kovacik M. W. , Mostardi R. A.
Published: March 2005

Total knee arthroplasty introduces foreign materials into the body that are intended to withstand significant biological and mechanical stresses while maintaining biocompatibility. Unfortunately many arthroplasty patients experience inflammation and pain, presumably due to wear debris that dislodges from the artificial joint over time. The failure mechanisms of prosthetic devices and the chemical make‐up of the associated wear debris are presently unclear. In this study, we use x‐ray photoelectron spectroscopy and Raman microscopy to identify the chemical composition of the wear debris. Knee synovial fluid was aspirated from seven different prosthetics patients and centrifuged, resulting in small deposits of wear debris. Our analysis identifies oxidized titanium in five of the seven sets of samples, indicating femoral component wear and potentially back‐side wear of the tibial base plates of the prosthetics. Furthermore, samples with large percentages of titanium also contain sodium, whereas the others contain chlorine. This may indicate differences in the chemical composition of synovial fluid under different inflammatory conditions. Copyright © 2005 John Wiley & Sons, Ltd.
Characterization of indium‐tin‐oxide films with improved corrosion resistance
Authors: Gaarenstroom Stephen W. , Balogh Michael P. , Militello Maria C. , Waldo Richard A. , Wong Curtis A. , Kelly Nelson A. , Gibson Thomas L. , Kundrat Matthew D.
Published: March 2005

Triple‐junction amorphous silicon solar cells coated with indium‐tin‐oxide (ITO) can be used to produce hydrogen gas from water and sunlight. However, a major limitation in their use is the short lifetime due to corrosion of the ITO coating that forms the anode in photoelectrochemical devices. In this work, we compare corrosion rates for ITO film electrodes grown using different sputter deposition conditions. The corrosion resistance varied by more than a factor of 15, with the longest‐lasting film having a time‐to‐failure of 25 h. The films were characterized exhaustively by techniques including electron microscopy, electron spectroscopy, electron microprobe and x‐ray diffraction to determine composition, thickness and microstructure. The most corrosion‐resistant films had the most well‐formed crystals and showed the most crystal texturing. Copyright © 2005 John Wiley & Sons, Ltd.
Growth, characterization and application of CdS thin films deposited by chemical bath deposition
Authors: Chang Y.‐J. , Munsee C. L. , Herman G. S. , Wager J. F. , Mugdur P. , Lee D.‐H. , Chang C.‐H.
Published: March 2005

The recent advance in soft solution processing of inorganic materials offers an exciting opportunity to develop large‐area manufacturing technologies for inorganic thin‐film transistors (TFTs). In this paper, we report our recent progress in fabricating CdS TFTs using chemical bath deposition (CBD) to deposit CdS channel layers. Device analysis of an enhancement‐mode CdS metal–insulator–semiconductor field effect transistor (MISFET) with a field‐effect mobility of ∼1.5 cm2 V−1 s−1 and a threshold voltage of VT ∼ 14 V is reported here. An on‐to‐off ratio of ∼106 is achieved. This rather large drain current on‐to‐off ratio indicates that this device will function well as a switch. An examination of the CdS film morphology by scanning electron microscopy indicates that the films deposited by CBD and used for our current device fabrication are dominated by a particle sticking growth mechanism. This is supported by a real‐time quartz crystal microbalance growth curve and atomic force microscopy characterizations of the particles formed in the CBD solution. A different bath condition for CBD was tested to obtain a dense CdS layer. A selected‐area electron diffraction pattern indicates that the CdS thin film deposited by CBD has a hexagonal structure with an optical bandgap of 2.4 eV as determined by UV–Vis absorption. Copyright © 2005 John Wiley & Sons, Ltd.
Whole blood endotoxin responsiveness in patients with chronic heart failure: the importance of serum lipoproteins
Authors: Sharma Rakesh , von Haehling Stephan , Rauchhaus Mathias , Bolger Aidan P. , Genth‐Zotz Sabine , Doehner Wolfram , Oliver Brian , Poole‐Wilson Philip A. , Hans‐Dieter Volk , Coats Andrew J.S. , Adcock Ian M. , Anker Stefan D.
Published: March 2005

Background

Endotoxin [lipopolysaccharide (LPS)] may be an important stimulus for cytokine release in patients with chronic heart failure (CHF). We sought to investigate the relationship between whole blood endotoxin responsiveness and serum lipoprotein concentrations. It is not known if low‐dose LPS is sufficient to stimulate immune activation.

Methods and results

Whole blood from 32 CHF patients (mean age 66±2 years, NYHA class 2.7±0.2, five female) and 11 healthy control subjects (mean age 47±4 years, six female) was stimulated with LPS at nine different concentrations (0.001 to 10 ng/mL), and tumor necrosis factor (TNF‐α) release was quantified. Reference standard endotoxin at concentrations of 0, 0.6, 1, and 3 EU/ml was added to whole blood from nine CHF patients (age 64α9.1 years, all NYHA class II, eight male) and incubated for 6 h, the TNF‐α production being measured. Serum lipoproteins were quantified using standard techniques. In CHF patients, there was an inverse relationship between whole blood TNF‐α release and serum cholesterol which was strongest at 0.6 ng/mL of LPS (r=−0.53, p=0.002). A similar although weaker relationship was found for serum HDL. No such correlation was found in healthy subjects or with serum LDL (all r2<0.1). Low concentrations of LPS induced a stepwise increase in TNF‐± release from whole blood to concentrations well above those seen in CHF.

Conclusions

Serum lipoproteins may play an important role in regulating LPS bioactivity in CHF. Very low LPS activity, at levels seen in vivo in CHF, can induce significant TNF‐α production ex vivo.
Postnatal treatment with NAN‐190 but not with 5‐HT1A receptor agonists retards growth of the rat brain
Authors: Djavadian R.L. , Wielkopolska E. , Turlejski K.
Published: March 2005

We investigated the influence of prolonged administration of the 5‐HT1A receptor agonists (8‐OH‐DPAT or buspirone) or its antagonist, NAN‐190 to rat pups on development of their cortical barrel field. Pups were injected daily with the drugs starting from the day of birth till either the 5th postnatal day or the 22–25th postnatal day and were perfused one day later. Square areas of their whisker barrel fields were measured on tangential sections of the cortex stained for cytochrome oxidase. Injections of 8‐OH‐DPAT or buspirone till the 5th postnatal day did not change any of the investigated parameters, while injections of NAN‐190 resulted in 15% reduction of the pups’ body and brain weight and proportional reduction of the square area of their barrel fields. Groups treated till the 22–25th postnatal day showed similar results. Some of these pups were injected with [C14]2‐deoxyglucose to investigate the strength of responses of their cortical barrels to stimulation of corresponding vibrissae. The cortical area labeled with 2‐deoxyglucose after stimulation of vibrissae of the row C was narrower in the NAN‐190 injected rats. This functional deficit was more pronounced than the anatomical one, which resembled the effects of neonatal serotonin depletion (Neuroreport, 1997). Therefore, the results of injecting NAN‐190 to the rat pups point to a deficit of trophic developmental influences of serotonin, adding new arguments for the hypothesis of a trophic role of 5‐HT1A receptors in the brain development.
Das Paradox des Jetzt
Authors: Bischof Norbert
Published: March 2005

Zusammenfassung. Die Frage nach der Willensfreiheit ist Teil des Leib-Seele-Problems. Sie stellt sich insbesondere, wenn wir die psychophysische Relation als isomorphe Parallelität zweier Aspekte derselben Prozeßmannigfaltigkeit begreifen. Hier scheint die Idee einer geschlossenen Naturkausalität der Entscheidungsfreiheit keinen Raum zu lassen. Allerdings ist zu berücksichtigen, dass das Weltbild der nachklassischen Physik nicht mehr uneingeschränkt deterministisch ist. Vor allem aber enthält es bisher eine Erklärungslücke bezüglich der Frage, warum physische Prozesse überhaupt von Bewusstseinserscheinungen begleitet sind. Noch gravierender ist der bisher nicht ausgeräumte Zweifel, ob sich das parallelistische Modell überhaupt konsistent formulieren läßt. Es ist noch nicht entschieden, ob sich die phänomenale Singularität des “Jetzt“ auf die materielle Wirklichkeit umkehrbar eindeutig abbilden läßt, bzw. genereller, ob eine Formulierung des Isomorphieprinzips möglich ist, die eine naive Gleichsetzung physikalischer und phänomenaler Zeit vermeidet.
Interpretation of long‐offset transient electromagnetic data from Mount Merapi, Indonesia, using a three‐dimensional optimization approach
Authors: Commer Michael , Helwig Stefan L. , Hördt Andreas , Tezkan Bülent
Published: March 2005

In the years 1998, 2000, and 2001, long‐offset transient electromagnetic (LOTEM) surveys were carried out at the active volcano Merapi in Central Java. The measurements investigated the conductivity structure of the volcanic edifice. Our area of interest, which is below the summit and the upper flanks, was investigated using horizontal and vertical magnetic field time derivative data from seven transmitter‐receiver setups. Because of topography and a three‐dimensional (3‐D) underground structure, a 3‐D interpretation is used. The method optimizes few parameters of a 3‐D model by a stable least squares joint inversion of the data, providing sufficient resolution capability. Reasonable data fits are achieved with a nonhorizontally layered model featuring a very conductive basement below depths of 1.5 km. While hydrothermal alteration is also considered, we tentatively explain the high conductivities by aqueous solutions with relatively high salt contents. A large magma body or a small superficial reservoir below Merapi's central volcanic complex, as discussed by other authors, cannot be resolved by the LOTEM data.
Adiabatic decompression and melting of mantle rocks: An irreversible thermodynamic analysis
Authors: Ganguly Jibamitra
Published: March 2005

The process of irreversible adiabatic decompression and melting of mantle rocks has been evaluated using the thermodynamic condition of frictionless decompression in a gravitational field. It is found that the melt productivity is significantly greater, thus enhancing the tendency for melt segregation, if a parcel of mantle rock moves upward at nearly constant velocity than that derived for the case of isentropic decompression. The T‐Z trajectory of a solid mantle diapir moving upward at a constant velocity has, in general, a smaller slope than the isentropic trajectory, and assumes a negative slope when its density falls below ∼94% of that of the surrounding mantle. The acceleration of upward movement, and the overall density reduction of the material due to phase change that is the likely cause for the acceleration, have qualitatively opposite effects on the deviations of melt productivity and T‐Z trajectory of mantle diapir from those under isentropic conditions.
Inhibition of P‐glycoprotein and increasing of drug‐sensitivity of a human carcinoma cell line (KB‐A‐1) by an antisense oligodeoxynucleotide–doxorubicin conjugate in vitro
Authors: Ren Yuhong , Wei Dongzhi , Zhan Xiaoyun
Published: March 2005

To improve the antisense activity of AS ODN (antisense oligodeoxynucleotide), a conjugate covalently linked to DOX (doxorubicin) at its 3′‐end was synthesized and its antisense activity in human carcinoma DOX‐resistant cells (KB‐A‐1) was investigated in vitro. The intracellular DOX concentration in KB‐A‐1 cells treated with the conjugate was detected in vitro by HPLC. Results showed that the intracellular DOX concentration was 6.4‐fold higher in KB‐A‐1 cells treated with the conjugate when compared with that in the cells treated with DOX alone. In contrast, a 1.8‐fold increase in the concentration of DOX was observed when the cells were treated with AS ODN. Reverse transcriptase PCR and Western‐blot analysis showed a more significant decrease in the amount of mdr1 (multidrug resistance 1 gene) mRNA and P‐glycoprotein in KB‐A‐1 cells. Chemosensitivity of KB‐A‐1 cells to DOX was also investigated in vitro. When the cells were first exposed to the conjugate (0.5 μM) for 24 h and then exposed to DOX for 24 h, the IC50 value of DOX decreased from 21.5 to 2.2 μM, whereas the IC50 value of DOX decreased only to 16.8 μM when the cells were treated with the mixture of the same concentration of AS ODN. These results suggest that the conjugate is effective in reversing multidrug resistance. Further studies will be conducted to explore the effect of the conjugate on tumours in vivo.
Experimentation, communication and patronage: a perspective on René‐Antoine Ferchault de Réaumur (1683–1757)
Authors: Ratcliff Marc J.
Published: March 2005

Historians of science have neglected the French Academician Réaumur, whose work is emblematic of a modern conception of science that joins together technology, science, and society. Réaumur practised rigorous experimentation on organisms, and uncovered industrial and utilitarian secrets which he communicated to the public. His patronage was essential in boosting the generation of young naturalists of the 1740s who advanced further the experimental approach to the study of nature. For Réaumur, his work was not separate from his mission to disclose and communicate previously restricted knowledge for the benefits of science and society.
Nucleotide specificity of HIV-1 reverse transcriptases with amino acid substitutions affecting Ala-114
Authors: CASES-GONZÁLEZ Clara E. , MENÉNDEZ-ARIAS Luis
Published: March 2005

Ala-114, together with Asp-113, Tyr-115 and Gln-151, form the pocket that accommodates the 3′-OH of the incoming dNTP in the HIV-1 RT (reverse transcriptase). Four mutant RTs having serine, glycine, threonine or valine instead of Ala-114 were obtained by site-directed mutagenesis. While mutants A114S and A114G retained significant DNA polymerase activity, A114T and A114V showed very low catalytic efficiency in nucleotide incorporation assays, due to their high apparent Km values for dNTP. Discrimination between AZTTP (3′-azido-3′-deoxythymidine triphosphate) and dTTP was not significantly affected by mutations A114S and A114G in assays carried out with heteropolymeric template/primers. However, both mutants showed decreased susceptibility to AZTTP when poly(rA)/(dT)16 was used as substrate. Steady-state kinetic analysis of the incorporation of ddNTPs compared with dNTPs showed that substituting glycine for Ala-114 produced a 5–6-fold increase in the RT's ability to discriminate against ddNTPs (including the physiologically relevant metabolites of zalcitabine and didanosine), a result that was confirmed in primer-extension assays. In contrast, A114S and A114V showed wild-type ddNTP/dNTP discrimination efficiencies. Discrimination against ribonucleotides was not affected by mutations at position 114. Misinsertion and mispair extension fidelity assays as well as determinations of G→A mutation frequencies using a lacZ complementation assay showed that, unlike Tyr-115 or Gln-151 mutants, the fidelity of HIV-1 RT was not largely affected by substitutions of Ala-114. The role of the side-chain of Ala-114 in ddNTP/dNTP discrimination appears to be determined by its participation in van der Waals interactions with the ribose moiety of the incoming nucleotide.
The endothelin-1 receptor antagonist bosentan protects against ischaemia/reperfusion-induced endothelial dysfunction in humans
Authors: BÖHM Felix , SETTERGREN Magnus , GONON Adrian T. , PERNOW John
Published: March 2005

Endothelial dysfunction may contribute to the extent of ischaemia/reperfusion injury. ET (endothelin)-1 receptor antagonism protects against myocardial ischaemia/reperfusion injury in animal models. The present study investigated whether oral administration of an ETA/ETB receptor antagonist protects against ischaemia/reperfusion-induced endothelial dysfunction in humans. FBF (forearm blood flow) was measured with venous occlusion plethysmography in 13 healthy male subjects. Forearm ischaemia was induced for 20 min followed by 60 min of reperfusion. Using a cross-over protocol, the subjects were randomized to oral administration of 500 mg of bosentan or placebo 2 h before ischaemia. Endothelium-dependent and -independent vasodilatation were determined by intra-brachial infusion of acetylcholine (1–10 μg/min) and nitroprusside (0.3–3 μg/min) respectively, before and after ischaemia. Compared with pre-ischaemia, the endothelium-dependent increase in FBF was significantly impaired at 15 and 30 min of reperfusion when the subjects received placebo (P<0.01). When the subjects received bosentan, the endothelium-dependent increase in FBF was not affected by ischaemia/reperfusion. Endothelium-independent vasodilatation was not affected during reperfusion compared with pre-ischaemia. The vaso-constrictor response induced by intra-arterial infusion of ET-1 was attenuated significantly by bosentan (P<0.001). The results suggest that the dual ETA/ETB receptor antagonist bosentan attenuates ischaemia/reperfusion-induced endothelial dysfunction in humans in vivo. Bosentan may thus be a feasible therapeutic agent in the treatment of ischaemia/reperfusion injury in humans.
Anomalous deterministic transport
Authors: Artuso Roberto , Cristadoro Giampaolo
Published: March 2005

We present a series of results on deterministic transport in chaotic system, obtained in the framework of periodic orbits theory. The emphasis is on intermittent systems, where deviations from complete chaos may induce anomalies on the asymptotic moments’ growth.
Weak and strong chaos in Fermi–Pasta–Ulam models and beyond
Authors: Pettini Marco , Casetti Lapo , Cerruti-Sola Monica , Franzosi Roberto , Cohen E. G. D.
Published: March 2005

We briefly review some of the most relevant results that our group obtained in the past, while investigating the dynamics of the Fermi–Pasta–Ulam (FPU) models. The first result is the numerical evidence of the existence of two different kinds of transitions in the dynamics of the FPU models: (i) A stochasticity threshold (ST), characterized by a value of the energy per degree of freedom below which the overwhelming majority of the phase space trajectories are regular (vanishing Lyapunov exponents). It tends to vanish as the number N of degrees of freedom is increased. (ii) A strong stochasticity threshold (SST), characterized by a value of the energy per degree of freedom at which a crossover appears between two different power laws of the energy dependence of the largest Lyapunov exponent, which phenomenologically corresponds to the transition between weak and strong chaotic regimes. It is stable with N. The second result is the development of a Riemannian geometric theory to explain the origin of Hamiltonian chaos. Starting this theory has been motivated by the inadequacy of the approach based on homoclinic intersections to explain the origin of chaos in systems of arbitrarily large N, or arbitrarily far from quasi-integrability, or displaying a transition between weak and strong chaos. Finally, the third result stems from the search for the transition between weak and strong chaos in systems other than FPU. Actually, we found that a very sharp SST appears as the dynamical counterpart of a thermodynamic phase transition, which in turn has led, in the light of the Riemannian theory of chaos, to the development of a topological theory of phase transitions.
Inverse variational problem and canonical structure of Burgers equations
Authors: Talukdar B. , Ghosh S. , Das U.
Published: March 2005

It is demonstrated that Burgers equations, which are often believed to describe dissipative systems, are non-Lagrangian. Following Bateman’s analysis of damped harmonic oscillator an action is defined to look for a Lagrangian representation for equations in the Burgers hierarchy. The associated higher-order Lagrangian densities are found to be degenerate such that the Hamiltonian structure could be studied by a repackaging of Ostrogradski formalism and Dirac’s theory of constraints.
The anti-FPU problem
Authors: Dauxois Thierry , Khomeriki Ramaz , Piazza Francesco , Ruffo Stefano
Published: March 2005

We present a detailed analysis of the modulational instability of the zone-boundary mode for one and higher-dimensional Fermi–Pasta–Ulam (FPU) lattices. Following this instability, a process of relaxation to equipartition takes place, which we have called the Anti-FPU problem because the energy is initially fed into the highest frequency part of the spectrum, at variance with the original FPU problem (low frequency excitations of the lattice). This process leads to the formation of chaotic breathers in both one and two dimensions. Finally, the system relaxes to energy equipartition on time scales which increase as the energy density is decreased. We show that breathers formed when cooling the lattice at the edges, starting from a random initial state, bear strong qualitative similarities with chaotic breathers.
Implications of comparative spectral doublets observed for neon-isolated and gaseous tropolone(OH) and tropolone(OD)
Authors: Redington Richard L. , Redington Theresa E.
Published: March 2005

Spectral doublet separations reported for gas phase and neon matrix-isolated samples of tropolone(OH) and tropolone(OD) are found to support recent work suggesting the possibility that tropolone has a slightly nonplanar geometry in the S1(ÃB21)(π*-π) electronic state. Tautomerizations of gaseous tropolones in the S0 and S1 states are governed by equal double-minimum potential energy functions (PEFs), but interactions in the neon matrix environment transform the tautomerization PEFs of the slightly nonplanar S1 tropolones into unequal double-minimum PEFs. The spectral doublets reported for the zero-point S1-S0 transitions imply energy minima for the nonplanar S1 state in a neon matrix are offset by about 7cm−1, and tunneling splittings in the symmetric double minimum PEFs of the gaseous molecules are damped about 2cm−1 by the matrix environment. This means gas phase tunneling splittings smaller than 2cm−1 are fully quenched in the neon matrix, and gas phase tunneling splittings near 20cm−1 are damped by only 10%.
Dynamics of oscillator chains from high frequency initial conditions: Comparison of ϕ4 and FPU-β models
Authors: Lichtenberg Allan J. , Mirnov Vladimir V. , Day Christopher
Published: March 2005

The dynamics of oscillator chains are studied, starting from high frequency initial conditions (h.f.i.c.). In particular, the formation and evolution of chaotic breathers (CB’s) of the Klein–Gordon chain with quartic nonlinearity in the Hamiltonian (the ϕ4 model) are compared to the results of the previously studied Fermi–Pasta–Ulam (FPU-β) chain. We find an important difference for h.f.i.c. is that the quartic nonlinearity, which drives the high frequency phenomena, being a self-force on each individual oscillator in the ϕ4 model is significantly weaker than the quartic term in the FPU-β model, which acts between neighboring oscillators that are nearly out-of-phase. The addition of a self-force breaks the translational invariance and adds a parameter. We compare theoretical results, using the envelope approximation to reduce the discrete coupled equations to a partial differential equation for each chain, indicating that various scalings can be used to predict the relative energies at which the basic phenomena of parametric instability, breather formation and coalescence, and ultimately breather decay to energy equipartition, will occur. Detailed numerical results, comparing the two chains, are presented to verify the scalings.
Dielectric behavior of the system BaSn1−xNbxO3 (x⩽0.10)
Authors: Singh Prabhakar , Kumar Devendra , Parkash Om
Published: March 2005

Compositions with x⩽0.10 have been synthesized in the system BaSn1−xNbxO3 by the solid state ceramic method. All the compositions have been found to be single phase solid solution having cubic structure. Lattice parameter for all the compositions remains almost the same. The optical micrographs show that average grain size is <1μm. Dielectric constant and dielectric loss have been measured as a function of frequency (100Hz–10MHz) and temperature (300–500K). Space charge polarization and orientational polarization contribute to the observed dielectric behavior.
Core-shell photoabsorption and photoelectron spectra of gas-phase pentacene: Experiment and theory
Authors: Alagia Michele , Baldacchini Chiara , Betti Maria Grazia , Bussolotti Fabio , Carravetta Vincenzo , Ekström Ulf , Mariani Carlo , Stranges Stefano
Published: March 2005

The C K-edge photoabsorption and 1s core-level photoemission of pentacene (C22H14) free molecules are experimentally measured, and calculated by self-consistent-field and static-exchange approximation ab initio methods. Six nonequivalent C atoms present in the molecule contribute to the C 1s photoemission spectrum. The complex near-edge structures of the carbon K-edge absorption spectrum present two main groups of discrete transitions between 283 and 288eV photon energy, due to absorption to π* virtual orbitals, and broader structures at higher energy, involving σ* virtual orbitals. The sharp absorption structures to the π* empty orbitals lay well below the thresholds for the C 1s ionizations, caused by strong excitonic and localization effects. We can definitely explain the C K-edge absorption spectrum as due to both final (virtual) and initial (core) orbital effects, mainly involving excitations to the two lowest-unoccupied molecular orbitals of π* symmetry, from the six chemically shifted C 1s core orbitals.
Computation of the pseudorotation matrix to satisfy the Eckart axis conditions
Authors: Dymarsky Anatoly Y. , Kudin Konstantin N.
Published: March 2005

A general solution for satisfying the Eckart axis conditions [C. Eckart, Phys. Rev. 47, 552 (1935)] is presented. The goal is to find such a pseudorotation matrix T that the vector product between the reference molecular conformation R and another transformed conformation r′ is zero [∑amara′×Ra=0;ra′=Tra]. Our solution avoids the limitations of the earlier one [H. M. Pickett and H. L. Strauss, J. Am. Chem. Soc. 92, 7281 (1970)], which fails when one of the involved intermediate matrices is singular. We also discuss how to choose among the always nonunique pseudorotation matrices T the one that represents a true rotation for situations when an alignment of the two conformations is desired.
Dynamics of neuron populations in noisy environments
Authors: Fortuna Luigi , Frasca Mattia , La Rosa Manuela , Spata Alessandro
Published: March 2005

In this paper different topologies of populations of FitzHugh–Nagumo neurons have been introduced in order to investigate the role played by the noise in the network. Each neuron is subjected to an independent source of noise. In these conditions the behavior of the population depends on the connection among the elements. By analyzing several kinds of topology (ranging from regular to random) different behaviors have been observed. Several topologies behave in an optimal way with respect to the range of noise level leading to an improvement in the stimulus response coherence, while others with respect to the maximum values of the performance index. However, the best results in terms of both the suitable noise level and high stimulus response coherence have been obtained when a diversity in neuron characteristic parameters has been introduced and the neurons have been connected in a small-world topology.
Tunable negative refractions in two-dimensional photonic crystals with superconductor constituents
Authors: Feng Liang , Liu Xiao-Ping , Ren Jie , Tang Yue-Feng , Chen Yan-Bin , Chen Yan-Feng , Zhu Yong-Yuan
Published: March 2005

In this paper, a two-dimensional square photonic crystal (PC) with superconductor cylinders is proposed to realize tunable negative refraction. Based on the dependence of the superconductors’ permittivity on temperatures, photonic band structures thus negative refraction could be tuned by temperatures, whereby the refractive angle could be scanned from positive to negative. The feasibility of the PC operating in infrared and visible regions was discussed. The tunability resulted from the lattice, superconductors, operating frequency, and incident angle may lead the PC to great promise in photoelectronics and superconductor electronic applications.
The nature of the hydrogen bond in the LaNiSnH2 and NdNiSnH hydrides
Authors: Spataru T. , Palade P. , Principi G. , Blaha P. , Schwarz K. , Kuncser V. , Lo Russo S. , Dal Toé S. , Yartys V. A.
Published: March 2005

The electronic structure of LaNiSn and NdNiSn compounds and their hydrides has been studied by first principles calculations and variable temperature Sn119 Mössbauer spectroscopy and the nature of the hydrogen-metal bond is discussed. The analysis of the electronic density of states (DOS) in both compounds before and after hydrogenation indicates an hybridization of the Sn, Ni, and H orbitals. The partial Sn-p DOS of LaNiSnH2 gives evidence for a lower symmetry of electron density around tin atoms compared to LaNiSn, according to the larger quadrupole splitting in the corresponding Mössbauer spectrum. Theoretical and experimental Mössbauer parameters agree very well for all samples.
Linear scaling computation of the Fock matrix. VIII. Periodic boundaries for exact exchange at the Γ point
Authors: Tymczak C. J. , Weber Valéry T. , Schwegler Eric , Challacombe Matt
Published: March 2005

A translationally invariant formulation of the Hartree–Fock (HF) Γ-point approximation is presented. This formulation is achieved through introduction of the minimum image convention (MIC) at the level of primitive two-electron integrals, and implemented in a periodic version of the ONX algorithm [E. Schwegler, M. Challacombe, and M. Head-Gordon, J. Chem. Phys. 106, 9708 (1997)] for linear scaling computation of the exchange matrix. Convergence of the HF-MIC Γ-point model to the HF k-space limit is demonstrated for fully periodic magnesium oxide, ice, and diamond. Computation of the diamond lattice constant using the HF-MIC model together with the hybrid PBE0 density functional [C. Adamo, M. Cossi, and V. Barone, THEOCHEM 493, 145 (1999)] yields a0=3.569Å with the 6-21G* basis set and a 3×3×3 supercell. Linear scaling computation of the HF-MIC exchange matrix is demonstrated for diamond and ice in the condensed phase.
Stacking fault nucleation sites in diffused 4H-SiC p-i-n diodes.
Authors: Maximenko S. I. , Sudarshan T. S.
Published: March 2005

The nucleation and development of stacking faults formed during the forward high current stress operation of 4H-SiC silicon carbide p-i-n diodes were investigated using the electron beam induced current mode of scanning electron microscopy and chemical etching in molten KOH. Two initial sources of stacking fault development were found. In addition to preexisting basal plane dislocations, localized defects in the near surface region, attributed to clusters of impurities, were found to serve as nucleation centers for stacking fault development during forward biasing of the diffused p-i-n diodes. Differences were observed in the electrical activity of stacking faults in diodes with the p+ region created by diffusion versus epitaxial growth.
Influence of the alkyl-chains length on the electronic structure and interface properties of 1,4-octasubstituted zinc phthalocyanines on gold
Authors: Dick S. , Peisert H. , Dini D. , Hanack M. , Cook M. J. , Chambrier I. , Chassé T.
Published: March 2005

We compare the interface properties of various 1,4,8,11,15,18,22,25 octa-alkyl-substituted zinc phthalocyanines [(But)8PcZn,(Hep)8PcZn,(Dec)8PcZn] with those of unsubstituted zinc phthalocyanine (PcZn) on gold using x-ray photoemission spectroscopy and valence band ultraviolet photoemission spectroscopy. Although the separation between the aromatic cores in the evaporated thin films depends clearly on the alkyl-chain length, it is found that the nature of the substituents causes only minor changes of electronic properties, such as optical gap and ionization potential. It is shown that the observed small energetic shifts for film thicknesses larger than the molecule size cannot be understood in terms of a band bending like mechanism.
Zinc blende GaAs films grown on wurtzite GaN∕sapphire templates
Authors: Chaldyshev V. V. , Nielsen B. , Mendez E. E. , Musikhin Yu. G. , Bert N. A. , Ma Zh. , Holden Todd
Published: March 2005

1-μm-thick zinc-blende GaAs (111) films were grown by molecular-beam epitaxy on wurtzite GaN∕sapphire (0001) templates. In spite of a ∼20% lattice mismatch, epitaxial growth was realized, so that the GaAs films showed good adhesion and their surface had a larger mirror-like area with an average surface roughness of 10 nm. Transmission electron microscopy revealed a flat and abrupt epitaxial GaAs∕GaN interface with some nanocavities and a large number of dislocations. Reasonably good crystalline quality of the GaAs films was confirmed by Raman characterization. Spectroscopic ellipsometry showed sharp interference fringes and characteristic parameters in the range of 0.75–5.3 eV. Photoluminescence study revealed extended band tails and dominance of non-radiative carrier recombination.