bluuebunny/crossref_metadata_2025 huggingface dataset:
Decomposition of leguminous crop residues in a ‘jhum’ cultivation system in Arunachal Pradesh, India
Authors: Arunachalam Kusum , Singh Narendra Deo , Arunachalam Ayyanadar
Published: December 2003

Decomposition of leaves, stems, and roots of two leguminous plants, french bean and pea, was studied in a ‘jhum’ cultivation (shifting agriculture) system in north‐eastern India in litter bag experiments. The dynamics of decomposition varied between the crop residues and species studied. All the three studied types of residues of french bean and the leaves and roots of pea showed polynomial decomposition model with three distinct phases: an initial slow decomposition phase (1), followed by a faster decomposition rate (2) and again by a slow decomposition phase (3). However, the stems of pea plants showed an exponential increase in the decomposition rate during field incubation. Initial N, lignin, and lignin : N ratio were determined in crop residues. In general, roots decomposed slowly as compared to the leaves and stems due to greater lignin content. Soil microbial activity as determined by CO2evolution was significantly correlated with the decomposition rates. Over all, the decay constants reveal that these fast decomposing leguminous crop residues can be properly managed for soil nutrient management in the low input shifting agricultural fields in the hills.
”The principles of rational agriculture” by Albrecht Daniel Thaer (1752–1828). An approach to the sustainability of cropping systems at the beginning of the 19th century
Authors: Feller Christian L. , Thuriès Laurent J.‐M. , Manlay Raphaël J. , Robin Paul , Frossard Emmanuel
Published: December 2003

The identification of quantitative fertility indicators for evaluating the sustainability of cropping and farming systems has become a major issue. This question has been extensively studied by the German agronomist Albrecht Daniel Thaer at the beginning of the 19h century. In this paper Thaer's work is set in its historical background, from the end of the 16th century (Palissy, 1580) to the middle of the 19th century (Liebig, 1840). Then the paper focuses on Thaer's quantitative and complex fertility scale (expressed in “fertility degrees”), which was based on soil properties, on the requirement of nutrients by plants, and on the cropping system (including crop rotation). Thaer expressed soil fertility and economic results as a function of rye production in “scheffel of rye per journal” (ca. 200 kg per hectare). He also proposed a scale to describe the intrinsic fertility of soil. Thaer used this approach to assess the effect of major German cropping systems on soil fertility. He applied it to eight theoretical systems and nine existing systems in a true modeling approach. Thaer completed the fertility evaluation for the nine existing systems with a detailed economical analysis commenting the limits and potentialities of each system. Thaer's approach was used with success during half a century as it combined numerous empirical findings on soils and fertilization with organic substances in a sophisticated model. Unfortunately and despite effective practical applications, the scientific foundations of Thaer's “Humus Theory” proved definitively false as soon as 1840 when Sprengel and Liebig published on mineral nutrition of plants. Thaer's work deserves to be rediscovered since it approaches the modern issue of the sustainability of cropping and farming systems.
Nitrogen biomarkers and their fate in soil
Authors: Amelung Wulf
Published: December 2003

More than 90 % of the nitrogen (N) in soils can be organically bound, but the mechanisms and rates by which it is cycled have eluded researchers. The objective of this research was to contribute to a better understanding of the origin and transformation of soil organic N (SON) by using amino sugars and the enantiomers of amino acids as markers for microbial residues and/or aging processes. Studied samples presented here comprised (1) soil transects across different climates, (2) arable soils with different duration of cropping, and (3) radiocarbon‐dated soil profiles. The results suggested that increased microbial alteration of SON temporarily results in a sequestration of N in microbial residues, which are mineralized at later stages of SON decomposition. Microorganisms increasingly sequestered N within intact cell wall residues as frost periods shortened. At a mean annual temperature above 12–15 °C, these residues were mineralized, probably due to limitations in additional substrates. Breaking the grassland for cropping caused rapid SON losses. Microbial residues were decomposed in preference to total N, this effect being enhanced at higher temperatures. Hence, climate and cultivation interactively affected SON dynamics. Nevertheless, not all SON was available to soil microorganisms. In soil profiles, L‐aspartic acid and L‐lysine slowly converted into their D‐form, for lysine even at a similar rate in soils of different microbial activity. Formation of D‐aspartate with time was, therefore, induced by microorganisms while that of D‐lysine was not. The racemization of the two amino acids indicates that SON not available to microorganisms ages biotically and abiotically. In native soils, the latter is conserved for centuries, despite N deficiency frequently occurring in living terrestrial environments. Climate was not found to affect the fate of old protein constituents in surface soil. When native grassland was broken for cropping, however, old SON constituents had become available to microorganisms and were degraded.
A pilot study of ICG laser therapy of acne vulgaris: Photodynamic and photothermolysis treatment
Authors: Tuchin Valery V. , Genina Elina A. , Bashkatov Alexey N. , Simonenko Georgy V. , Odoevskaya Olga D. , Altshuler Gregory B.
Published: December 2003

Background and Objectives

The near‐infrared (NIR) laser radiation due to its high penetration depth is widely used in phototherapy. In application to skin appendages, a high selectivity of laser treatment is needed to prevent light action on surrounding tissues. Indocyanine green (ICG) dye may provide a high selectivity of treatment due to effective ICG uploading by a target and its narrow band of considerable absorption just at the wavelength of the NIR diode laser. The goal of this study is to demonstrate the efficacy of the NIR diode laser phototherapy in combination with topical application of ICG suggested for soft and thermal treatment of acne vulgaris.

Study Design/Materials and Methods

Twenty‐two volunteers with facile or back‐located acne were enrolled. Skin sites of subjects were stained by ICG and irradiated by NIR laser‐diode light (803 or 809 nm). One mg/ml solution of ICG was applied for 5 or 15 minutes to the cleaned skin site. Untreated, only stained and only light irradiated skin areas served as controls. For soft acne treatment, the low‐intensity (803 nm, 10–50 mW/cm2, 5–10 minutes) or the medium‐intensity (809 nm, 150–190 mW/cm2, 15 minutes) protocols were used. The single and multiple (up to 8–9) treatments were provided. The individual acne lesions were photothermally treated at 18 W/cm2 (803 nm, 0.5 seconds) without skin surface cooling or at 200 W/cm2 (809 nm, 0.5 seconds) with cooling.

Results

The observations during 1–2 months showed that soft acne treatment decreased the number of active elements, reduced erythema and inflammation, and considerably improved the skin state without any side effects. At high power densities (up to 200 W/cm2), ICG stained acne inflammatory elements were destroyed for light exposures of 0.5 seconds.

Conclusions

Based on the concept that hair follicle, especially sebaceous gland, can be intensively and selectively stained by ICG due to dye diffusion through pilosebaceous canal and its fast uptake by living microorganisms, by vital keratinocytes of epithelium of the canal and sebaceous duct, and by rapidly proliferating sebocytes, new technologies of soft and thermal acne lesions treatment that could be used in clinical treatment of acne were proposed. Lasers Surg. Med. 33:296–310, 2003. © 2003 Wiley‐Liss, Inc.
Influence of wavelength on response to laser photothermolysis of blood vessels: Implications for port wine stain laser therapy
Authors: Kimel Sol , Svaasand Lars O. , Hammer‐Wilson Marie J. , Nelson J. Stuart
Published: December 2003

Background and Objective

Treatment of port wine stains (PWS) by photothermolysis can be improved by optimizing laser parameters. We have studied the all‐important role of wavelength (λ) by performing pulsed laser photothermolysis in the vasculature of the chick chorioallantoic membrane (CAM) assay.

Study Design/Materials and Methods

The CAM contains an extensive microvascular network ranging from capillaries with diameter D < 20 μm to blood vessels of D ≈ 120 μm. The CAM assay enables observation and real‐time video documentation of blood flow in pre‐capillary arterioles (A) and post‐capillary venules (V). The ScleroPlus™ laser (Candela Corp., Wayland, MA) has a smooth output over its fixed 1.5 ms pulse duration and allows the operator to vary several treatment parameters such as wavelength, spot size, and energy. Blood vessels in the CAM were irradiated at two clinically relevant wavelengths, λ = 587 or 597 nm, constant spot size (7 mm), and at different exposures (E = 5–12 J/cm2). Threshold exposure (Eth) (at which non‐reversible damage occurred) were 5 J/cm2 at 587 nm and 8 J/cm2 at 597 nm. Mathematical modeling was developed to interpret initial (within 30 seconds) injury of arterioles and venules at both wavelengths as a function of D when varying E.

Results

Vessel injury was graded off‐line from videotapes. For all combinations of λ and E, measurable injury was evident within 30 seconds of irradiation and maximal damage was reached in less than 10 minutes. Vessel damage was found to depend strongly on λ. Damage decreased with increasing vessel size. For all D, damage of arterioles was greater than for corresponding venules.

Conclusions

Selection of the correct wavelength is crucial for successful laser therapy of hypervascular lesions and, ideally, should be based on knowledge of vessel diameters for a specific PWS lesion and of optical penetration depths in blood. As a general statement, smaller blood vessels (D = 10–60 μm) should be treated using shorter wavelengths such as 585 nm. To ensure deposition of sufficient laser energy, irradiation at 585 nm, characterized by lower optical penetration depth in blood, may be preferable for PWS therapy. Lasers Surg. Med. 33:288–295, 2003. © 2003 Wiley‐Liss, Inc.
The interaction of lipopolysaccharides with phenothiazine dyes
Authors: Usacheva Marina N. , Teichert Matthew C. , Biel Merrill A.
Published: December 2003

Background and Objectives

The difference in the photobactericidal efficacy of methylene blue and toluidine blue against gram‐negative bacteria may result from their primary reaction with lipopolysaccharides (LPS) of the outer bacterial membrane. The aim of the present study was to compare the reactivity of these dyes with LPS extracted from different gram‐negative bacteria.

Study Design/Materials and Methods

The interactions of methylene blue and toluidine blue with LPS from Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Klebsiella pneumoniae (K. pneumoniae), and Serratia marcescens (S. marcescens) were studied spectrophotometrically in 0.45% saline. The dyes were used at the concentration of 10 μM. The concentrations of LPS ranged from 5–100 μg/ml.

Results

Methylene blue and toluidine blue enter into a metachromatic reaction with the LPS resulting the in generation of dimers of methylene blue and higher aggregates of toluidine blue. The more significant hypochromic and hypsochromic effects in the reaction of the latter with LPS indicate a greater metachromatic efficacy of toluidine blue than methylene blue. The equilibrium constants of the metachromatic complex between toluidine blue and different LPS were calculated. The spectrophotometric titration of LPS with the dyes was used to estimate the equivalent weight of LPS.

Conclusions

Toluidine blue interacts with LPS more significantly than methylene blue in vitro. This may be one of the main factors determining its greater photobactericidal efficacy against gram‐negative bacteria. Lasers Surg. Med. 33:311–319, 2003. © 2003 Wiley‐Liss, Inc.
Comparison of the photostimulatory effects of visible He‐Ne and infrared Ga‐As lasers on healing impaired diabetic rat wounds
Authors: Kesava Reddy G.
Published: December 2003

Background and Objectives

In this study, the ability of photostimulation to promote healing of impaired wounds was investigated using a Ga‐As laser in rats with experimental diabetes and the results were compared with previously reported findings of the effects of a He‐Ne laser on the repair of healing‐impaired diabetic rat wounds 1.

Study Design/Materials and Methods

Diabetes was induced in male rats by streptozotocin injection following which two full thickness punch wounds of 6‐mm diameter were created in the skin, one on either side of the spine of each animal. The left wound of each animal was treated with infrared radiation at 904 nm produced by a Ga‐As laser at an energy density of 1.0 J/cm2. The right wound of each animal served as the control. The wounds were treated with a laser 5 days a week for 3 weeks. Following animal sacrifice, the strips of skin containing the wound sites were collected and analyzed.

Results

The results from the biomechanical analysis indicated that the Ga‐As laser used in this study significantly increased wound tensile strain and toughness compared to the control wounds. Marginal increases in wound tensile strength (9%) and stress (7%) were observed in the Ga‐As laser‐treated wounds compared to the controls. No significant changes were found in Young's modulus and energy absorption capacity between the control and laser‐treated wounds. Analysis of wound collagen revealed a significant increases in total collagen (14%), salt soluble collagen (31%), acid soluble (14%), and insoluble collagen (50%) with simultaneous decrease in pepsin soluble collagen (19%) in the Ga‐As laser‐treated wounds compared to controls. Comparisons of these results with the earlier findings revealed that the He‐Ne laser appears to be superior to the Ga‐As laser, at the parameters of treatment tested, in promoting the wound healing in diabetic rats.

Conclusions

The differences in stimulatory effects noted between the He‐Ne and Ga‐As lasers suggest that the photochemical response the cells for each laser may depend on the wavelength and coherent properties of the electromagnetic radiation. Lasers Surg. Med. 33:344–351, 2003. © 2003 Wiley‐Liss, Inc.
Evaluation of myocardial perfusion and left ventricular function six months after percutaneous transmyocardial laser revascularization: Comparison of two Ho‐YAG laser systems with the same wavelength, but different energy delivery and navigation systems
Authors: Strehblow Christoph , Gyöngyösi Mariann , Khorsand Aliasghar , Sperker Wolfgang , Gatterer Melanie , Graf Senta , Sochor Heinz , Glogar Dietmar
Published: December 2003

Background and Objectives

Myocardial perfusion and left ventricular function (LVF) were assessed after percutaneous transmyocardial laser revascularization (PTMR) in patients not amenable to conventional revascularization, with a comparison of two laser systems.

Study Design/Materials and Methods

PTMR was performed with an Eclipse laser in 15 patients, and with a Biosense DMR in 10 patients. 201Thallium scintigraphy, coronary angiography, and ventriculography were performed at baseline and at the 7.5±4.3‐month follow‐up. All patients in the Biosense DMR group and 10 in the Eclipse group underwent NOGA mapping before PTMR and after follow‐up.

Results

The event‐free survival rates were comparable, and the angina scores of all patients improved significantly, but more so in the Biosense DMR group than in the Eclipse group (1.2±1.1 vs. 2.3±0.9, P < 0.05). Both, the electrical activity assessed by NOGA mapping and the normalized 201thallium uptake at redistribution improved significantly in the treated segments after Biosense DMR, while the global LVF decreased insignificantly in the Eclipse group.

Conclusions

PTMR resulted in significant improvements in the clinical symptoms, but the electrical activity improved only in the Biosense DMR group, without transforming to a better LVF. Lasers Surg. Med. 33:273–281, 2003. © 2003 Wiley‐Liss, Inc.
Effects of the Ga‐As laser irradiation on myonecrosis caused by Bothrops Moojeni snake venom
Authors: Dourado Doroty M. , Fávero Silvio , Baranauskas Vitor , da Cruz‐Höfling Maria Alice
Published: December 2003

Background and Objectives

Viper snake envenoming induces in the victims systemic coagulopathy, and severe local tissue damage such as edema, hemorrhage, intense pain, and myonecrosis. Serumtherapy and other first‐aid managements are ineffective in neutralizing these local effects. The effects of the gallium‐arsenide (Ga‐As) laser irradiation on mice gastrocnemius injected intramuscularly (i.m.) with Bothrops moojeni snake venom were investigated.

Study Design/Materials and Methods

Macroscopical, histopatological, and myonecrosis quantification through serum creatine kinase (CK) evaluation was done at 3, 12, and 24 hours (two, five, and eight irradiation sessions, 4 J/cm2, 1 minute 32 seconds per period, respectively), were done after the venom or saline injection, and in venom‐unirradiated mice.

Results

In unirradiated gastrocnemius, the venom induced massive hemorrhage, vascular congestion, time‐progressing myonecrosis, edema, abundant inflammatory infiltrate, and high CK serum levels. Ga‐As irradiation significantly decreased the amount of myonecrosis in all the periods tested (P < 0.05).

Conclusions

The laser treatment significantly inhibited the ability of B. moojeni venom to rapidly disrupt the integrity of the plasma membrane. Lasers Surg. Med. 33:352–357, 2003. © 2003 Wiley‐Liss, Inc.
Efficacy of low level laser therapy in myofascial pain syndrome: An algometric and thermographic evaluation
Authors: Hakgüder Aral , Birtane Murat , Gürcan Süleyman , Kokino Siranuş , Nesrin Turan Fatma
Published: December 2003

Background and objectives

The efficacy of low level laser therapy (LLLT) in myofascial pain syndrome (MPS) seems controversial. Our aim was to clarify the effect of LLLT in MPS by using algometry and thermography.

Study Design/Materials and Methods

Sixty‐two patients with MPS having an active trigger point in the neck or upper back region were randomly divided into two equal groups according to therapy applied (group 1: LLLT + stretching exercises, group 2: stretching exercises alone). The outcome measures were pain measured with visual analogue scale (VAS), algometry on the trigger point, algometric difference, thermographic difference, and thermal asymmetry. Comparison was made within and between the groups pre‐ and post‐therapeutically and 3 weeks after therapy.

Results

Mean pain values decreased more significantly in group 1 from baseline to 3 weeks follow up (7.54–3.06) while these values were 7.03–5.19 in group 2 (P < 0.05). Group comparisons revealed significant favorable differences in group 1 patients in terms of all other parameters at the first and the second evaluation post therapeutically (P < 0.05).

Conclusions

LLLT seemed to be beneficial for pain in MPS by using algometry and thermography. Lasers Surg. Med. 33:339–343, 2003. © 2003 Wiley‐Liss, Inc.
EPR‐Messungen in warmgehenden Anlagen
Authors: Schultze S. , Göllner J. , Panitz J.
Published: December 2003

Es wird über Erfahrungen zum Sensibilisierungsverhalten von austenitischen titan‐ und niobstabilisierten Stählen unter Praxisbedingungen bei Betriebstemperaturen zwischen 340 und 600°C berichtet. Auf Sensibilisierung wurden sowohl Rohr‐ und Flanschmaterial als auch Schweißverbindungen einschließlich Wärmeeinflusszonen mit Hilfe des Verfahrens der elektrochemischen potentiodynamischen Reaktivierung (EPR) geprüft. Die Messungen erfolgten während eines Anlagenstillstandes vor Ort an verschiedenen Rohren mit Durchmessern zwischen 150 bis 460 mm mit einer Aufsatzmesszelle.
Beispiel für die Untersuchung eines Korrosionsschadens an Aluminium‐Dach‐ und Fassadenblechen
Authors: Huppatz W.
Published: December 2003

An Aluminiumdach‐ und ‐fassadenblechen aus einem Schmelzwerk wurde die Schädigung untersucht, die durch die Einwirkung von Flugstaub, Reinigungssalzen und Gasen aus dem Betrieb auf die blanke Aluminiumoberfläche ausging. Als Kriterien für die Schädigung wurden die Wanddickenabnahme, die Verringerung der Festigkeitseigenschaften und das Auftreten von Loch‐ und Muldenkorrosion gewertet. Die Schäden waren nach den Resultaten der analytischen Messungen auf Chloride, Sulfate und Fluoride in Zusammenwirken mit der großen Acidität der Ablagerungen in feuchten Zustand zurückzuführen. Qualitätsmängel an den Aluminiumwerkstoffen waren nicht gegeben. Unter den ermittelten Bedingungen waren die Grenzen der Korrosionsbeständigkeit des Aluminiums überschritten. Die Anwendung von Aluminium unter solchen Einflüssen erfordert eine Beschichtung – beispielsweise durch eine PVF2‐Einbrennlackierung oder durch Kaschierung mit einer Tedlar®‐Folie.
Lochkorrosion nichtrostender Stähle und hochlegierte Fe/Ni/Cr/Mo‐Werkstoffe ‐ Entwicklungsstufen und Untersuchungsverfahren
Authors: Riedel G. , Werner H. , Friedrich S.
Published: December 2003

Bezogen auf die Entwicklungsstufen der Lochkorrosion werden Bestimmungsgrößen und Einflussfaktoren dargelegt. Nach der Erläuterung markanter Lochkorrosionspotentiale werden Möglichkeiten zur Detektierung der Entwicklungsstufen der Lochkorrosion aufgezeigt und auf ihre Beeinflussung durch charakteristische Merkmale des Metalls, durch die chemische Zusammensetzung des Mediums und durch physikalische Bedingungen eingegangen. Aufbauend darauf werden Belastungen und Auswertemethoden zur Prüfung der Lochkorrosionsbeständigkeit diskutiert und für technische Fragestellungen wichtige chemische und elektrochemische Prüfverfahren vorgestellt.

Erwähnt wird ein in Entwicklung befindliches Prüfverfahren zur Bestimmung der Lochkorrosionsbeständigkeit von Schweißverbindungen direkt an Apparaten und Anlagen.
Inhibitor efficiency inside small crevices investigated by Electrochemical Noise Analysis
Authors: Schneider M. , Galle K. , Pohl H.
Published: December 2003

The Electrochemical Noise Analysis (ENA) is a novel technique employed to investigate dynamic properties of electrochemical systems. The influence of chromate inhibitors on the corrosion activity of an AA 2024 surface in a chloride containing sodium solution was studied by the measurement of current noise under potential control. The noise analysis clearly shows the efficiency of the chromate inhibitor on the crevice corrosion as well as the sufficiency of the ENA as a useful tool as an inhibitor screening process. The measurement under crevice condition was carried out in‐situ in an artificial crevice.
Lochkorrosionsverhalten von Auftragschweißungen – Schweißlagen‐ und Oberflächeneffekte –
Authors: Heyn A. , Schilling K. , Boese E. , Spieler S. , Altendorf S. , Burkert A. , Schultze S.
Published: December 2003

Zur vergleichenden Einschätzung der Lochkorrosionsbeständigkeit von verschiedenen, mehrlagigen MAGp‐auftraggeschweißten Nickelbasis‐Schweißgütern auf einem Superduplexstahl wurden kritische Lochkorrosionstemperaturen (critical pitting temperature, CPT) nach ASTM G 48 C ermittelt. Es zeigte sich eine unerwartet niedrige Beständigkeit der Auftragschweißungen, als dessen Ursache ein ungünstiger Oberflächenzustand angenommen wurde. Da die CPT‐Bestimmung nach ASTM keine Aussage über den Korrosionsverlauf gestattet und Untersuchungen über einen weiten Temperaturbereich damit sehr aufwendig sind, wurde eine neue Prüfmethode angewandt. Diese ermittelt die CPT mit Hilfe des elektrochemischen Stromrauschens zwischen zwei gleichartigen Proben in der nach ASTM G 48 C geforderten Prüflösung bei kontinuierlicher Temperaturerhöhung. Dadurch war es möglich, den Einfluss des Oberflächenzustandes auf das Lochkorrosionsverhalten der untersuchten Proben schnell nachzuweisen und geeignete Maßnahmen zu ergreifen. Der beim MAGp‐Schweißen entstehende oxidische Oberflächenbelag beeinflusst die Lochkorrosionsbeständigkeit negativ. Nach der mechanischen Beseitigung der Beläge durch Strahlen oder Schleifen weisen die Proben eine wesentlich höhere Lochkorrosionsbeständigkeit auf, und es konnte die Abhängigkeit von der Anzahl der Schweißlagen ermittelt werden.
Ausscheidungshärtbare Nickelbasis‐Superlegierungen für den Verschleißschutz im Hochtemperaturbereich
Authors: Bouaifi B. , Draugelates U.
Published: December 2003

Für Neufertigung und Regenerierung von hochtemperaturbelasteten Bauteilen stehen bereits ausscheidungshärtbare Schweißzusätze auf Nickelbasis zur Verfügung. Ihre besonderen Festigkeitseigenschaften bei Einsatztemperaturen von ca. 800°C beruhen u. a. auf ihrer Aushärtbarkeit durch die γ′‐Phase Ni3(Ti, Al), welche nach mehrstufiger Wärmebehandlung zur Ausscheidung gelangt. Die auftraggeschweißten Bauteile lassen sich jedoch nicht ohne Einbuße der mechanischen Gütewerte des Trägerwerkstoffes wärmebehandeln.

Aus diesem Grunde wurde nach einer Auftragschweißlegierung gesucht, die auch ohne Mehrstufenglühung bzw. mit einer das Substrat nicht schädigenden Wärmebehandlung auskommt. Ziel war, ausscheidungshärtbare Versuchslegierungen zum MSG‐Fülldrahtauftragschweißen mit einer Zusammensetzung zu entwickeln, so dass auch ohne eine substratschädigende Wärmenachbehandlung ähnliche Hochtemperatureigenschaften wie bei Ni‐Basis‐Superlegierungen im ausgehärteten Zustand erreicht werden. Die Legierungen wurden mehrlagig auftraggeschweißt und unterschiedlichen Wärmebehandlungen unterzogen. Als Eigenschaftskontrolle dienten Härteprüfungen. Einflüsse von Schweißparametern sowie dadurch beeinflusste Erstarrungsformen konnten durch metallographische Untersuchungen einander zugeordnet werden. REM‐Untersuchungen an ausgewählten Versuchslegierungen belegten die Ausscheidung der γ′‐Phase und weiterer Hartphasen. Aus den Ergebnissen lassen sich Empfehlungen für das Auftragschweißen von hochtemperaturbeständigen Schichten bezüglich Prozessführung, Legierungszusammensetzung und Wärmenachbehandlung geben.
Initiation and propagation of stainless steel pitting corrosion under heat flux
Authors: Prošek T. , Novák P.
Published: December 2003

An effect of heat flux on initiation and propagation of pitting corrosion of austenitic stainless steel in chloride environment has been studied using electrochemical and exposure methods. The experiments were performed at constant surface temperature of 60°C and heat flux from − 15 to + 74 kW m−2. The presence of heat flux from metal to solution shifted the breakdown potential towards noble values and lowered the pit density, whereas the pit propagation rate increased. Presence of maximum heat flux caused, in comparison with isothermal conditions, increase of the breakdown potential by approx. 100 mV, reduction of pit density by 30% and increase of the average pit depth by 40%. The positive effect of heat flux from metal to solution was given mainly by improving the protective ability of the passive film, as the amount of oxygen available at the metal surface increased. With a smaller significance, the effect of intensified mass transfer, which made accumulation of the chloride ions on the surface more difficult, occurred.
Impedance of Cr18Ni10 stainless steel in sulphate solutions after a low‐temperature plasma nitriding
Authors: Flis J. , Kuczynska M.
Published: December 2003

The 00Cr18Ni10 stainless steel was examined before and after plasma nitriding in a 80%N2/20%H2 gas mixture at 425°C for 30 h, resulting in the formation of a supersaturated solid solution of nitrogen in austenite (S phase) with 12.9 wt.% N at the surface. Electrochemical measurements were made on the as‐nitrided surface and after abrasion to various depths. Polarisation curves and impedance were measured in 0.1 M Na2SO4 acidified to pH 3.0; some measurements were also made at pH 6 and 9. It was found that nitrogen decreased the corrosion resistance of the steel in the acidified solution (pH 3.0), but increased it in the neutral and near‐neutral solutions (pH 6.0 and 9.0). The deleterious effect of nitrogen at pH 3.0 was at potentials of the active state much stronger and more dependent on the nitrogen concentration than in the passive state. It was suggested that the increased anodic reactivity of the nitrided steel in the active state is inherent for the lower thermodynamic stability of the supersaturated solid solution of nitrogen, whereas the increased corrosion resistance in the neutral and near‐neutral sulphate solutions is associated with the effect of nitrogen on anodic films.
Macromolecular metal complexes in nature and laboratory: a survey through the field
Authors: Wöhrle D. , Pomogailo A.D. , Suvorova O. , Tsaryova O. , Dzardimalieva G. , Baziakina N.
Published: December 2003

Based on a very recently published monograph a short overview on macromolecular metal complexes (metal complexes and metals in macromolecules) is given. The understanding of biological system is fundamentally important to construct artificial macromolecular metal complexes. A classification for the various up to now synthesized systems is given, and properties and potential applications are pointed out.
Oxygen‐carrying plasma hemoprotein “albumin‐heme”: nitric oxide binding and physiological responses after administration in vivo
Authors: Tsuchida Eishun , Komatsu Teruyuki
Published: December 2003

Recombinant human serum albumin complexed with tetraphenylporphinatoiron(II) derivative, “albumin‐heme (rHSA‐FeP)”, is a synthetic oxygen (O2)‐carrying plasma hemoprotein, which becomes a new class of red blood cell substitute. The UV‐vis. absorption and ESR spectroscopy revealed that rHSA‐FeP formed six‐coordinate nitrosyl complex after exposure of nitric oxide (NO) gas. Although the NO‐binding affinity of rHSA‐FeP (P1/2NO: 1.7 × 10−6 Torr, pH 7.3, 25°C) is 9‐fold higher compared to that of hemoglobin (Hb), the administration of this artificial hemoprotein solution into anesthetized rat does not induce an acute increase in blood pressure (hypertension), which is often observed in Hb‐based O2‐carriers due to the depletion of NO (endothelial derived relaxing factor).
Molecularly controlled blending of metals and organic metals with polyolefins for the preparation of materials with modulated optical properties
Authors: Pucci Andrea , Elvati Paolo , Ruggeri Giacomo , Liuzzo Vincenzo , Tirelli Nicola , Isola Mauro , Ciardelli Francesco
Published: December 2003

In this paper, after revisiting previous data on terthiophene molecules, several attempts are described to use metal containing species such as nanoclusters and molecular complexes as dispersed chromophores in the same ethylene polymer matrix in order to extend an approach to new classes of molecules and improve some specific optical responses including fluorescence dichroism and behaviour as linear optical polarizers is evaluated. Comparison with typical linear polarizers from the same polymer and terthiophenes of innovative gold clusters is discussed as well as transition metal complexes.
Proton‐conducting polymer membranes for direct methanol fuel cells
Authors: Won Jongok , Kang Yong Soo
Published: December 2003

Three methods to block the methanol transport through proton‐conducting polymer membranes while maintaining the proton conductivity unchanged have been conducted; 1) selective layer formation on the surface of the membrane, 2) prearation of nanoclay composite membrane providing tortuous pathway of methanol, 3) control and fixation of the proton transport channels. The methanol permeability through the membranes decreased significantly at the expense of the small decrease in the proton conductivity. It is thus concluded that both the structure and the fixation of the proton transport channels are crucial in optimizinging proton conducting membranes for direct methanol fuel cells.
Synthesis of azo‐conjugated catecholate complexes and their photo‐ and proton‐responses
Authors: Nagashima Sayoko , Nihei Masayuki , Yamada Teppei , Murata Masaki , Kurihara Masato , Nishihara Hiroshi
Published: December 2003

A new azo‐conjugated catecholate ligand, azocat, and its nickel complexes were synthesized, and their physical and chemical properties were investigated. The complex with one azocat shows no obvious photo‐response, whereas the compound with two azocat's causes a little photoisomerization. Both of these novel azo‐conjugated catecholate complexes show remarkable proton responses.
Effect of supercritical CO2 on bulk hydrogenation of nitrile butadiene rubber catalyzed by RhCl(PPh3)3
Authors: Li Guanghui , Pan Qinmin , Rempel Garry L. , Ng Flora T.T.
Published: December 2003

The effect of supercritical (SC) CO2 on the bulk hydrogenation of NBR entrapped with the catalyst (RhCl(PPh3)3) was investigated under various reaction times, reaction temperatures, hydrogen pressures and loadings of the catalyst and the thicknesses of the polymer films. CO2 helps in improving the transport behaviour of catalyst in polymer matrices, as well as helping to move catalyst into or out of the polymer. A method for the measurement of the dissolution extent or the apparent solubility of the Rh based catalyst in SC‐CO2 was developed. It is found that high temperatures and high SC‐CO2 densities would enhance the apparent solubility. Cosolvents, such as acetone, are also found to increase the apparent solubility. Details on the hydrogenation process are also presented.
Electrochemical reduction of carbon dioxide catalyzed by cofacial dinuclear metalloporphyrin
Authors: Enoki Osamu , Imaoka Takane , Yamamoto Kimihisa
Published: December 2003

Cofacial dinuclear metalloporphyrins exhibited a catalytic activity for the electrochemical reduction of carbon dioxide. The cofacial dinuclear porphyrin was automatically generated by mixing a cationic cobalt porphyrin (CoTMPyP) and an anionic metalloporphyrin (MTPPS) in solution. The redox system of this complex was examined by electrochemical methods. According to the cyclic voltammogram, the catalytic active species was generated at −1.8V vs. Ag/Ag+, which was considered to be a monovalent cobalt porphyrin, Co(I)TMPyP. The catalytic activity of the dinuclear complex was two times greater than that of the mononuclear one because the anionic porphyrin acted as an electron mediator.
Supramolecular catalytic systems based on calixarenes and cyclodextrins
Authors: Karakhanov Edward E. , Maksimov Anton L. , Runova Elena A. , Kardasheva Yulia S. , Terenina Maria F. , Buchneva Tatyana S. , Guchkova Anna Ya.
Published: December 2003

A number of supramolecular metal complex catalitic system based on cyclodextrins and calixarenes have been developed. Particular attention has been given to design of new metal complexes with molecular recognition abilities. Data on application catalytic systems based on receptor molecules capable to formation of inclusion “host‐guest” complexes in hydroformylation and Wacker‐oxidation are given. Influence of different factors on activity, stability, selectivity of metal complex supramolecular catalytic systems is discussed.
Polyfunctional activity of metal complexes containing 2,6‐Di‐tert‐butylphenol in catalytic oxidation
Authors: Milaeva Elena R. , Shpakovsky Dmitry B. , Petrosyan Valery S.
Published: December 2003

The results of the investigations of metal complexes containing 2,6‐di‐tert‐butilphenol in the ligand environment in catalytic homogeneous oxidation of organic compounds are reviewed. The liquid‐phase oxidation of hydrocarbons, olefins, aminophenol and unsaturated fatty acids by molecular oxygen in the presence of phthalocyanines, porphyrins, σ‐aryl and π‐allyl transition metal complexes is described. The change of the reactivity of organometallic and coordination compounds by oxidation of the redox active phenolic group opens up the possibility to use them as polyfunctional catalytic systems showing positive and/or negative catalytic effects.
Oxidation of catecholamines on chitosan‐immobilized Co(II) salen complexes
Authors: Finashina E.D. , Kramareva N.V. , Kustov L.M.
Published: December 2003

L‐Adrenaline and 3,4‐dihydroxyphenylalanine (dopa) oxidation by molecular oxygen in the presence of the Co(II) complex of bis(salicylideneethylene diamine) (CoSalen) immobilized on unmodified chitosan and chitosan modified by 4‐pyridinecarboxaldehyde is studied in aqueous solutions under mild conditions. The catalysts prepared are selective with respect to oxidation of the chosen substrates. Preparation of binary composite egg‐shell systems, with a thin film of low‐loaded CoSalen‐chitosan supported on macroporous SiO2 makes it possible to increase sufficiently the specific surface area and the efficiency of the catalyst.
Recent progress in applications of ligand‐stabilized metal nanoclusters
Authors: Toshima Naoki
Published: December 2003

Due to a nanotechnology boom in science and technology, the metal nanoclusters or nanoparticles stabilized by polymers and organic ligands have achieved much attention recently all over the world. We have studied on the preparation of polymer‐stabilized metal nanoclusters by chemical methods, and applied them mainly to catalyses. Here the recent progresses in our group are presented in the structure control of bimetallic and trimetallic nanoclusters and in the applications of metal nanoclusters not only to the catalyses but also to the sensing responsive to pH and molecular recognition, and to the electro‐optic properties of liquid‐crystalline display rapidly responsive to frequency modulation. Preparation of trimetallic nanoclusters with a triple core/shell structure is especially emphasized to serve as a very active catalyst at a special atomic ratio of three elements.
Metal catalysis to improve compatibility at PO/PET blends interfaces
Authors: Coltelli Maria‐Beatrice , Bianchi Sabrina , Savi Stefania , Liuzzo Vincenzo , Aglietto Mauro
Published: December 2003

Reactive blending of 70/30 by weight PET/polyolefin (PO) mixtures was carried out in a discontinuous mixer using a polyolefin functionalized with dialkyl maleates and potential transesterification catalysts to improve the formation of graft PO‐PET copolymers. The yield of this reaction was evaluated by the analysis of FT‐IR spectra of blends residual fraction after selective extractions of unreacted polyester. The building of a calibration curve and the analysis of the spectra by deconvolution was performed to evaluate the percentage of grafted PET. The results are discussed in terms of influence of the different catalysts and of polyolefin structure on the blends morphology.
The complexes of macromolecules and metal nanoparticles: pseudo‐template synthesis and behavior
Authors: Papisov I.M.
Published: December 2003

Metal sols composed of metal nanoparticles (1 ‐ 10 nm in diameter) protected with polymer molecules may be regarded as dispersions of polymer‐metal complexes formed due to cooperative non‐covalent (e.g., hydrophobic, coulombic) interaction of polymer chains with the surface of metal nanoparticles. The sols are commonly prepared by reducing of metal ions in solutions of appropriate polymers.

The interactions between macromolecules and nanoparticles are reversible. In the case of long polymer chains and minute particles, the equilibrium constant of the reaction exponentially depends on the surface area of the particle. The probability of mutual “recognition” (complex formation) of growing particle and a macromolecule rapidly increases from practically zero to practically unity in narrow interval of the particle's diameters. The recognition is followed with the shadowing of the particles and the stop of their growths. Such kind of processes was termed “pseudo‐template”. In frame of the concept of pseudo‐template processes can be estimated: (1) the conditions at which sol particles of desirable size can be prepared, (2) the influence of temperature, polymer concentration, nanoparticles size, and other conditions on the stability of polymer ‐ particle complex having been prepared, and (3) the conditions at which stable sol does not exist and can not be prepared at all.

The interactions between metal nanoparticles and macromolecules are highly selective regard to the structure of polymer chains. The property can be effectively used for the control the size characteristics of metal nanoparticles (in course of their formation) and the stability of metal sols.

The selectivity provides high conversions in catalytic chemical modification reactions in which a macromolecule is the substrate and a component of the catalyst in the same time. As an example, the hydrolysis of lactame groups in monomer unites of poly(N‐vinyl pyrrolidone) catalyzed with copper sols is discussed.
Combined XPS and AFM study of cluster‐containing polymers based on Rh
Authors: Lyakhovich Alevtina M. , Mikhailova Sophia S. , Pomogailo Svetlana I. , Dzhardimalieva Gulzhian I. , Pomogailo Anatolii D.
Published: December 2003

Rh6‐ monomer and polymer‐immobilized complexes have been characterized using XPS and AFM. Polymer‐immobilized clusters were obtained by the reaction of Rh6(CO)15CH3CN with copolymer of allyldiphenylphosphine and styrene. AFM study shows the change of surface morphology of the above copolymers. XPS data demonstrated the change of charge state of Rh atoms under monosubstitution of the CO‐group for Rh6‐ monomer complexes as well as in copolymer cluster complexe after the catalysis process of hydrogenation.
Magnetic properties of polymer matrix nanocomposites on a basis of metal carboxylates
Authors: Leonowicz Martin K. , Lawecka Marta , Ślawska‐Waniewska A. , Dzhardimalieva Gulzhian I. , Rozenberg Aleksander S. , Pomogailo Anatolii D.
Published: December 2003

Metallopolymer nanocomposites on the bases of cobalt and iron acrylates as well as their cocrystallites have been obtained and characterized. Microstructure of the materials consists of both agglomerated and individual nanocrystallites which are homogeneously distributed in the polymer matrix. Mean crystallite size is 7‐14 nm. All the composite materials exhibit soft magnetic properties at room temperature. The magnetic parameters are controlled by the intrinsic magnetic properties of the constituents and agglomeration of the particles.
Conformational switching between carboxylic acid and carboxylate anion states by NH‐O hydrogen bonding
Authors: Ueyama Norikazu , Takahashi Kazuyuki , Onoda Akira , Okamura Takaaki , Yamamoto Hitoshi
Published: December 2003

Biologically important Ca‐proteins and Ca‐biominerals as metal‐polymer complexes are often regulated by the complexation and demetalation with the biopolymers. Metal‐oxygen bond is supported by NH···O hydrogen bonds between coordinating oxyanion and neighboring amide NH and by the successive hydrogen bonding networks. Carboxylate anion under hydrophobic conditions has a high basicity that leads to a covalent Ca‐O bond character that is significantly affected by the NH···O hydrogen bond. The hydrogen bonds in Asp‐containing tripeptide fragments in Ca‐proteins presumably control coordination/dissociation of metal‐oxygen bonds. Our systematic studies of carboxylate, sulfonate and phosphate Ca(II) complexes demonstrate a relationship between the basicity of oxyanion in carboxylate and hydrogen bonds as cooperating with the oligopeptide conformation in Asp‐containing Ca(II) complexes. Hydrogen bonds between carboxylate oxyanion and amide NH, controlled by a conformational switching of oligopeptide fragments, seem to be one of essential factors for the regulatory formation of Ca‐proteins and nano‐architectures in connection with the interface structure of inorganic and organic phases in biominerals.
Transverse Stark effect of electrons in a semiconducting quantum wire
Authors: Vázquez G. J. , del Castillo‐Mussot M. , Spector Harold N.
Published: December 2003

We investigate the effect of an electric field applied tranversely to the axis of cylindrical symmetry of a cylindrical quantum wire on the ground‐state energy of the electrons in the wire using an infinite confining potential well model. For low electric fields, we find a quadratic shift of the energy levels with the electric field; while for strong fields, the Stark shift of the ground‐state energy increases almost linearly with the electric field. This increase is greater for wide wires, but for narrow wires, the Stark shift of the ground‐state energy does not change much with the electric field. Also, at higher electric fields, the Stark shift of the ground‐state energy increases with increasing wire radius. This will lead to the decrease of the effective bandgap of a semiconducting quantum wire with electric field. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impurity breakdown under transverse runaway of hot electrons
Authors: Metreveli N. K. , Kachlishvili Z. S. , Chumburidze F. G. , Tskipuri L. T.
Published: December 2003

In the transverse electric and magnetic field, in Hall regime the low‐temperature impurity breakdown (IB) under transverse runway (TR) conditions is considered. The effect of the increase in the compensation degree on the IB and TR applied electric field ratio is studied at different values of the magnetic field. It is shown, that with the increase in the magnetic field critical electric fields relevant to IB and TR must tend to each other, while at the fixed magnetic field the IB critical field approaches the TR threshold field with the increase in the compensation degree. The obtained results are at variance with the well‐known fact that the applied breakdown field tends to infinity at C0 → 1, that is to say when the concentration of free charge cariers tends to zero; in asymptotics the applied breakdown and threshold fields merge. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of in‐plane anisotropy on specific heat jump of MgB2
Authors: Udomsamuthirun P. , Rakpanich S. , Yoksan S.
Published: December 2003

An analytical result for the normalized jump of the heat capacity ΔC/CN is derived for in‐plane anisotropic s‐wave superconductors within the framework of the weak‐coupling BCS approach. Our results show that within the anisotropy gap model the value of ΔC/CN must be less than the BCS value and the effect of in‐plane asymmetry will reduce or increase the value of ΔC/CN of in‐plane symmetry depending on its parameters. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Out‐of‐plane transport in Bi2−xPbxSr2Co2Oy single crystals
Authors: Li H. L. , Ruan K. Q. , Wang Q. , Chen Y. , Qian S. , Yu Y. , Huang S. L. , Zheng Z. , Wang C. Y. , Cao L. Z.
Published: December 2003

The transport properties of Bi2−xPbxSr2Co2Oy single crystals with various Pb contents are studied. The in‐plane resistivity ρab always shows metallic behavior from room temperature (290 K) to 80 K with various Pb contents, while the out‐of‐plane resistivity ρc shows rather complex behavior. For Pb‐free samples, ρc shows semiconductive behavior in the measured temperature range. With increasing Pb content, the temperature dependence of ρc shows an evolution from semiconductive through crossover to metallic behavior. According to the formula for ρc proposed previously, the evolution of ρc behavior is fitted well. Using the small polaron theory, the complex behavior of ρc is interpreted. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structure calculationsof magnesium chalcogenides MgS and MgSe
Authors: Rached D. , Benkhettou N. , Soudini B. , Abbar B. , Sekkal N. , Driz M.
Published: December 2003

Theoretical results on the structural and the electronic properties of MgS and MgSe are presented. The calculations were made using the full‐potential linear muffin‐tin orbitals (FP‐LMTO) method augmented by a plane wave (PLW) basis. It was found that the electronic properties in the B1, B3 and B4 structures of these magnesium chalcogenides show good agreement compared to other works. Through these results the power of these calculation methods applied to the magnesium chalcogenides was confirmed. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)