bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthetic MMP‐13 degradable ECMs based on poly(N‐isopropylacrylamide‐co‐acrylic acid) semi‐interpenetrating polymer networks. I. Degradation and cell migration
Authors: Kim Soyeon , Chung Eugene H. , Gilbert Michele , Healy Kevin E.
Published: July 2005

Thermoresponsive and injectable semi‐interpenetrating polymer networks (sIPNs) containing a biospecific cell‐adhesive signal and proteolytically degradable domains were developed as a synthetic equivalent of the extracellular matrix (ECM). The sIPNs synthesized define a modular hydrogel ECM where different properties of the matrix can be manipulated independently, thus creating a system where parametric analysis of the effect of hydrogel properties on cell proliferation and differentiation is possible. sIPNs composed of poly(N‐isopropylacrylamide‐co‐acrylic acid) [p(NIPAAm‐co‐AAc)] and RGD‐grafted poly(acrylic acid) linear chains [p(AAc)‐g‐RGD] were synthesized with peptide crosslinkers containing a matrix metalloproteinase‐13 (MMP‐13, collagenase‐3) degradable domain. The lower critical solution temperature (LCST) of peptide‐crosslinked p(NIPAAm‐co‐AAc) sIPNs was not influenced by the addition of either linear p(AAc) or peptide‐modified p(AAc) chains (∼34°C) in PBS. Degradation of peptide‐crosslinked hydrogels and sIPNs was enzyme specific and concentration dependent. Exposure of rat calvarial osteoblast (RCO) culture to the degradation products from the peptide‐crosslinked hydrogels did not significantly affect cell viability. Migration of RCOs into the sIPNs was dependent upon the presence of both a cell‐adhesive RGD peptide (Ac‐CGGNGEPRGDTYRAY‐NH2) and proteolytically‐degradable crosslinks; however, there was greater dependence on the latter. The sIPNs synthesized are versatile materials for assessing cell fate in synthetic ECM constructs in vitro and tissue regeneration in vivo. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Critical interval of somal calcium transient after neurite transection determines B104 cell survival
Authors: Nguyen Michael P. , Bittner George D. , Fishman Harvey M.
Published: July 2005

Nerve cells may survive or die after axonal or dendritic transection. After neurite transection near (<50 μm) the cell body of Fura‐2‐loaded B104 neuroblastoma (rat brain‐derived) cells, the somal calcium concentration (SCC) undergoes a three‐phase transient change: a rapid (0–0.15‐min posttransection [PT]) rise phase, followed by an early (0.15–1.5‐min PT) rapid decay phase, and succeeded by a late (1.5–60‐min PT) slower decay phase that restores SCC to preinjury levels. The SCC in a critical interval (1.5–12.5 min PT) of the third transient phase correlates with cell fate, i.e., most transected cells that exclude dye (restore a barrier) and die have a significantly higher (P < 0.005) SCC in this critical interval than do transected cells that exclude dye and survive at 24‐hr PT. Loading BAPTA (chelation of somal Ca2+) before, but not after, the critical interval increases the percentage of cells that survive compared to that of cells transected without BAPTA loading. Furthermore, most transected cells that die despite successful barrier restoration exhibit characteristics consistent with apoptosis initiated during the critical interval of the SCC, including caspase activation and plasmalemmal phosphatidylserine translocation. These data suggest that decreased cell survival for injuries near the soma is due to Ca2+‐initiated apoptosis during the critical interval of the third phase of the SCC transient. © 2005 Wiley‐Liss, Inc.
Silicon nutrition of tomato and bitter gourd with special emphasis on silicon distribution in root fractions
Authors: Heine Gregor , Tikum George , Horst Walter J.
Published: July 2005

Two plant species, tomato (Lycopersicon esculentum Mill.) and bitter gourd (Momordica charantia), were used for in‐depth studies on the dynamics of silicon (Si) uptake and translocation to the shoots and compartmentation of Si in the roots. The experiments were conducted under controlled environmental conditions in nutrient solutions, which were partly amended with 1 mM Si in the form of silicic acid. At harvest, xylem exudates were collected, and Si concentrations and biomass of roots and shoots were determined. Mass flow of Si was calculated based on the Si concentration of the nutrient solution and transpiration determined in a parallel experiment. Plant roots were subjected to a fractionated Si analysis, allowing attributing Si to different root compartments. Silicon concentrations in the roots compared to the shoots were higher in tomato but lower in bitter gourd. A more ready translocation from the roots to the shoots in bitter gourd was in agreement with Si concentrations in the xylem exudates which were higher than in the external solution. In tomato, the xylem‐sap Si concentration was lower than in the nutrient solution. Calculated Si mass flow to the root exceeded Si uptake in tomato, which was consistent with the measured accumulation of Si in the root water‐free space (WFS). In contrast, Si concentration in the root WFS was lower than in the nutrient solution in bitter gourd, reflecting the calculated Si depletion at the root surface based on the comparison of Si mass flow and Si uptake. Within the roots, more than 80% of the total Si was located in the cell wall and less than 10% in the cytoplasmic fractions in tomato. In bitter gourd, between 60% and 70% of the total root Si was attributed to the cell‐wall fraction whereas the proportion of the cytoplasmic fraction reached more than 30%. Our results clearly confirm that tomato belongs to the Si excluders and bitter gourd to the Si‐accumulator plant species for which high Si concentrations in the cytoplasmic root fraction appear to be characteristic.
Drought and salinity: A comparison of their effects on mineral nutrition of plants
Authors: Hu Yuncai , Schmidhalter Urs
Published: July 2005

The increasing frequency of dry periods in many regions of the world and the problems associated with salinity in irrigated areas frequently result in the consecutive occurrence of drought and salinity on cultivated land. Currently, 50% of all irrigation schemes are affected by salinity. Nutrient disturbances under both drought and salinity reduce plant growth by affecting the availability, transport, and partitioning of nutrients. However, drought and salinity can differentially affect the mineral nutrition of plants. Salinity may cause nutrient deficiencies or imbalances, due to the competition of Na+ and Cl– with nutrients such as K+, Ca2+, and NO$ _3^- $. Drought, on the other hand, can affect nutrient uptake and impair acropetal translocation of some nutrients. Despite contradictory reports on the effects of nutrient supply on plant growth under saline or drought conditions, it is generally accepted that an increased nutrient supply will not improve plant growth when the nutrient is already present in sufficient amounts in the soil and when the drought or salt stress is severe. A better understanding of the role of mineral nutrients in plant resistance to drought and salinity will contribute to an improved fertilizer management in arid and semi‐arid areas and in regions suffering from temporary drought. This paper reviews the current state of knowledge on plant nutrition under drought and salinity conditions. Specific topics include: (1) the effects of drought and salt stress on nutrient availability, uptake, transport, and accumulation in plants, (2) the interactions between nutrient supply and drought‐ or salt‐stress response, and (3) means to increase nutrient availability under drought and salinity by breeding and molecular approaches.
Root and rhizomicrobial respiration: A review of approaches to estimate respiration by autotrophic and heterotrophic organisms in soil
Authors: Kuzyakov Yakov , Larionova Alla A.
Published: July 2005

Partitioning the root‐derived CO2 efflux from soil (frequently termed rhizosphere respiration) into actual root respiration (RR, respiration by autotrophs) and rhizomicrobial respiration (RMR, respiration by heterotrophs) is crucial in determining the carbon (C) and energy balance of plants and soils. It is also essential in quantifying C sources for rhizosphere microorganisms and in estimation of the C contributing to turnover of soil organic matter (SOM), as well as in linking net ecosystem production (NEP) and net ecosystem exchange (NEE). Artificial‐environment studies such as hydroponics or sterile soils yield unrealistic C‐partitioning values and are unsuitable for predicting C flows under natural conditions. To date, several methods have been suggested to separate RR and RMR in nonsterile soils: 1) component integration, 2) substrate‐induced respiration, 3) respiration by excised roots, 4) comparison of root‐derived 14CO2 with rhizomicrobial 14CO2 after continuous labeling, 5) isotope dilution, 6) model‐rhizodeposition technique, 7) modeling of 14CO2 efflux dynamics, 8) exudate elution, and 9) δ13C of CO2 and microbial biomass. This review describes the basic principles and assumptions of these methods and compares the results obtained in the original papers and in studies designed to compare the methods.

The component‐integration method leads to strong disturbance and non‐proportional increase of CO2 efflux from different sources. Four of the methods (5 to 8) are based on the pulse labeling of shoots in a 14CO2 atmosphere and subsequent monitoring of 14CO2 efflux from the soil. The model‐rhizodeposition technique and exudate‐elution procedure strongly overestimate RR and underestimate RMR. Despite alternative assumptions, isotope dilution and modeling of 14CO2‐efflux dynamics yield similar results. In crops and grasses (wheat, ryegrass, barley, buckwheat, maize, meadow fescue, prairie grasses), RR amounts on average to 48±5% and RMR to 52±5% of root‐derived CO2.

The method based on the 13C isotopic signature of CO2 and microbial biomass is the most promising approach, especially when the plants are continuously labeled in 13CO2 or 14CO2 atmosphere. The “difference” methods, i.e., trenching, tree girdling, root‐exclusion techniques, etc., are not suitable for separating the respiration by autotrophic and heterotrophic organisms because the difference methods neglect the importance of microbial respiration of rhizodeposits.
Effect of nitrogen supply on carbon and nitrogen partitioning after flowering in maize
Authors: Paponov Iwan A. , Engels Christof
Published: July 2005

Low nitrogen (N) supply may change assimilate partitioning between plant organs. We measured the effect of N supply on partitioning of recently assimilated 13C and recently absorbed 15N between generative and vegetative plant organs of two maize genotypes (Zea mays L.) 14 d after silking, i.e., during the lag phase of kernel growth. Furthermore, net partitioning of dry matter and N were assessed during grain filling. Plants were grown in a greenhouse in large containers. Our hypothesis was that N deficiency reduces grain set due to low partitioning of carbon (C) and N to the grains during the lag phase and reduces grain yield also because of excessive remobilization of N from the leaves during grain filling. During the lag phase, low N supply increased partitioning of recently assimilated photosynthates towards stem and roots at the expense of partitioning towards reproductive organs. However, despite of diminished sink strength of the reproductive organs for photosynthates, sugar concentrations in the grains of N‐deficient plants were increased, indicating that kernel set and potential kernel weight were not limited by low C supply at the end of the lag phase. In contrast to C, partitioning of recently absorbed N towards the reproductive organs was increased at low N supply at the expense of partitioning towards the roots. This indicates different mechanisms for the regulation of C and N distribution within the plant. During grain filling, biomass partitioning between plant organs was more affected by genotype than by rate of N supply. Nitrogen accumulation in the grains substantially exceeded total N uptake in the plant after flowering. Excess N accumulation in the grains was covered mainly by depletion of stem N at high N supply and by depletion of leaf N at low N supply. However, high concentrations of nonstructural carbohydrates in the stem at maturity indicated that grain yield of N‐deficient plants was not limited by low source strength of N‐depleted leaves.
Proton toxicity interferes with the screening of common bean (Phaseolus vulgaris L.) genotypes for aluminium resistance in nutrient solution
Authors: Rangel Andrés F. , Mobin Mohammad , Rao Idupulapati M. , Horst Walter J.
Published: July 2005

Common bean (Phaseolus vulgaris L.) proved to be very sensitive of low pH (4.3), with large genotypic differences in proton sensitivity. Therefore, proton toxicity did not allow the screening of common bean genotypes for aluminium (Al) resistance using the established protocol for maize (0.5 mM CaCl2, 8 μM H3BO3, pH 4.3). Increasing the pH to 4.5, the Ca2+ concentration to 5 mM, and addition of 0.5 mM KCl fully prevented proton toxicity in 28 tested genotypes and allowed to identify differences in Al resistance using the inhibition of root elongation by 20 μM Al supply for 36 h as parameter of Al injury. As in maize, Al treatment induced callose formation in root apices of common bean. Aluminium‐induced callose formation well reflected the effect of Ca supply on Al sensitivity as revealed by root‐growth inhibition. Aluminum‐induced callose formation in root apices of 28 bean genotypes differing in Al resistance after 36 h Al treatment was positively correlated to Al‐induced inhibition of root elongation and Al contents in the root apices. However, the relationship was less close than previously reported for maize. Also, after 12 h Al treatment, callose formation and Al contents in root apices did not reflect differences in Al resistance between two contrasting genotypes, indicating a different mode of the expression of Al toxicity and regulation of Al resistance in common bean than in maize.
Short‐term and residual availability of nitrogen after long‐term application of organic fertilizers on arable land
Authors: Gutser R. , Ebertseder Th. , Weber A. , Schraml M. , Schmidhalter U.
Published: July 2005

Knowledge on short‐term and long‐term availability of nitrogen (N) after application of organic fertilizers (e.g., farmyard manure, slurry, sewage sludge, composts) provides an important basis to optimize fertilizer use with benefits for the farmer and the environment. Nitrogen from many organic fertilizers often shows little effect on crop growth in the year of application, because of the slow‐release characteristics of organically bound N. Furthermore, N immobilization after application can occur, leading to an enrichment of the soil N pool. However, this process finally increases the long‐term efficiency of organic fertilizers. Short‐term N release from organic fertilizers, measured as mineral‐fertilizer equivalents (MFE), varies greatly from 0% (some composts) to nearly 100% (urine). The most important indicators to be used for predicting the short‐term availability of N are total and NH$ _4^+ $‐N contents, C : N ratio (especially of the decomposable organic fraction), and stability of the organic substances. Processing steps before organic fertilizers are applied in the field particularly can influence N availability. Composting reduces mineral‐N content and increases the stability of the organic matter, whereas anaerobic fermentation increases NH$ _4^+ $‐N content as well as the stability of organic matter, but decreases the C : N ratio remarkably, resulting in a product with a high content of directly available N. Nevertheless, long‐term effects of organic fertilizers rather slowly releasing N have to be considered to enable optimization of fertilizer use. After long‐term application of organic fertilizers, the overall N‐use efficiency is adequate to a MFE in the range of 40%–70%.
Soil water balance and nitrate leaching in winter wheat–summer maize double‐cropping systems with different irrigation and N fertilization in the North China Plain
Authors: Mack Ulrich Dieter , Feger Karl‐Heinz , Gong Yuanshi , Stahr Karl
Published: July 2005

Field experiments over a 3 y period were conducted in a winter wheat‐maize double‐cropping system at the Dongbeiwang Experimental Station, Beijing, China. Three different treatments of irrigation (sprinkler “suboptimal” and “optimized”; conventional flood irrigation) and N fertilization (none, according to Nmin soil tests, conventional) were studied with respect to effects on soil water balance, nitrate leaching, and grain yield. Under sprinkler irrigation, evaporation losses were higher due to a more frequent water application. On the other hand, in this treatment nitrate leaching was smaller as compared to flood irrigation, where abundant seepage fluxes >10 mm d–1 along preferential flow paths occurred. For quantifying nitrate leaching, passive samplers filled with ion‐exchange resins appeared to be better suited than a method which combined measurements of suction‐cup concentrations with model‐based soil water fluxes. As a result of the more balanced percolation regime (compared to that under conventional flood irrigation), there was a tendency of higher salt load of the soil solution in the rooting zone. Given a seepage rate of 50 mm, a winter wheat grain production of 5–6 t ha–1 required a total water addition of about 430 mm. Fertilizer treatments >100 kg N ha–1 did not result in any additional yield increase. An even balance between withdrawing and recharge of groundwater cannot be achieved with “optimized” irrigation, but with a reduction of evapotranspiration losses, adapted cropping systems, and/or by tapping water resources from reservoirs in more distant areas with surpluses.
Soil‐ and plant‐based nitrogen‐fertilizer recommendations in arable farming
Authors: Olfs Hans‐Werner , Blankenau Klaus , Brentrup Frank , Jasper Jörg , Link Axel , Lammel Joachim
Published: July 2005

Under‐ as well as overfertilization with nitrogen (N) will result in economic loss for the farmer due to reduced yields and quality of the products. Also from an ecological perspective, it is important that the grower makes the correct decision on how much and when to apply N for a certain crop to minimize impacts on the environment. To aggravate the situation, N is a substance that is present in many compartments in different forms (nitrate, ammonium, organic N, etc.) in the soil‐plant environment and takes part in various processes (e.g., mineralization, immobilization, leaching, denitrification, etc.). Today, many N‐recommendation systems are mainly based on yield expectation. However, yields are not stable from year to year for a given field. Also the processes that determine the N supply from other sources than fertilizer are not predictable at the start of the growing season. Different methodological approaches are reviewed that have been introduced to improve N‐fertilizer recommendations for arable crops. Many soil‐based methods have been developed to measure soil mineral N (SMN) that is available for plants at a given sampling date. Soil sampling at the start of the growing period and analyzing for the amount of NO$ _3^- $‐N (and NH$ _4^+ $‐N) is a widespread approach in Europe and North America. Based on data from field calibrations, the SMN pool is filled up with fertilizer N to a recommended amount. Depending on pre‐crop, use of organic manure, or soil characteristics, the recommendation might be modified (±10–50 kg N ha–1). Another set of soil methods has been established to estimate the amount of N that is mineralized from soil organic matter, plant residues, and/or organic manure. From the huge range of methods proposed so far, simple mild extraction procedures have gained most interest, but introduction into practical recommendation schemes has been rather limited. Plant‐analytical procedures cover the whole range from quantitative laboratory analysis to semiquantitative “quick” tests carried out in the field. The main idea is that the plant itself is the best indicator for the N supply from any source within the growth period. In‐field methods like the nitrate plant sap/petiole test and chlorophyll measurements with hand‐held devices orviaremote sensing are regarded as most promising, because with these methods an adequate adjustment of the N‐fertilizer application strategy within the season is feasible. Prerequisite is a fertilization strategy that is based on several N applications and not on a one‐go approach.
Field test of superheater corrosion in a CFB waste boiler: Part II – Scale formation characteristics
Authors: Andersson P. , Norell M.
Published: July 2005

This study concerns the scales formed on the steels T22 , Alloy 310, Alloy 28 and the nickel‐based Alloy 65 in a superheater test coil at 460–540°C in a CFB waste boiler. The methods used for the characterisation of the scales included SEM, EDX, Auger spectroscopy and XRD. The deposits on the tubes consisted mainly of alkali chlorides and calcium sulphate. The scales formed consisted of Fe2O3 and Fe3O4 on the T22 steel, NiFe2O3 and Cr2O3 on Alloy 310 and Alloy 28, and Cr2O3 and NiO on Alloy 65. Rapid corrosion on the steel T22 was associated with the growth of an open columnar iron oxide below a thick porous chlorine‐containing scale. Pitting corrosion on Alloy 310 occurred and it may be associated with selective corrosion, first following the grain boundaries then uniformly attacking the metal. The only protective oxide was observed on Alloy 28 that formed an inner chromium oxide separating the chlorides from the metal. Dense thin chromium oxides were observed in the scale on Alloy 28, but no major cracks were found perpendicular to the tube. Alloy 65 suffered from grain boundary attack and was locally attacked under thick porous chromium oxide with nickel chlorides in the advancing front. Molybdenum was enriched at the interface to the metal on both Alloy 28 and Alloy 65.
Investigation of steam oxidation behaviour of TP347H FG. Part 2: Exposure at 91 bar
Authors: Jianmin J. , Montgomery M. , Larsen O. H. , Jensen S. A
Published: July 2005

Tube specimens of TP347FG were exposed in a test superheater loop in a biomass plant in Denmark. The specimens were exposed to surface metal temperatures in the range of 455–568°C, steam pressure of 91 bar and exposure duration of 3500 and 8700 hours. The oxide thickness and morphology was investigated using light optical and scanning electron microscopy. The oxide present on the specimens is a duplex oxide with an inner chromium rich oxide and an outer iron rich oxide. The inner oxide consisted of a primary iron chromium nickel oxide in the original alloy grain and a chromium rich oxide, “healing layer”, at the grain boundaries. This gave the appearance of uneven inner oxide and it was clear that the varying subsurface grain size affected inner oxide thickness, especially after longer exposure times. Longer exposure times from 3500 to 8700 hours resulted in increased pit thickness. Comparison of pit thickness revealed that increase of temperature from 455 to 525°C increases the oxidation rate, however a further increase in temperature did not result in thicker inner oxide presumably due to the formation of a better healing layer at grain boundaries. These results are compared with the previous paper where the pressure and temperature was higher. A thicker inner oxide is observed at the lower temperatures and pressures compared with higher temperatures and pressures. Reasons for this behaviour are discussed.
Electrolytic pickling of duplex stainless steel
Authors: Ipek N. , Holm B. , Pettersson R. , Runnsjö G. , Karlsson M.
Published: July 2005

Pickling of duplex stainless steels has proved to be much more difficult than that of standard austenitic grades. Electrolytic pre‐pickling is shown to be a key process towards facilitating the pickling process for material annealed both in the production‐line and in laboratory experiments. The mechanism for the neutral electrolytic process on duplex 2205 and austenitic 316 steels has been examined and the oxide scale found to become thinner as a function of electrolytic pickling time. Spallation or peeling of the oxide induced by gas evolution did not play a decisive role. A maximum of about 20% of the current supplied to the oxidised steel surface goes to dissolution reactions whereas about 80% of the current was consumed in oxygen gas production. This makes the current utilisation very poor, particularly against the background of reports that in indirect electrolytic pickling only about 30% of the total current, supplied to the process, actually goes into the strip. A parametric study was therefore carried out to determine whether adjustment of process variables could improve the current utilisation.
Stainless steel crevice corrosion testing in natural and synthetic seawater
Authors: Lahodny‐Šarc O. , Kulušić B. , Krstulović Lj. , Sambrailo D. , Ivić J.
Published: July 2005

Susceptibility of stainless steel to crevice corrosion in natural and synthetic seawater was investigated by a new test method, developed by a research group, CrevCorr, of the Marine Working Party of the European Federation of Corrosion. The method was defined on the basis of a Round Robin test performed by twenty laboratories over the world [1, 2]. Among them was our Institute at the Adriatic coast. Geometry of the crevice model, gasket materials, finishing of metal surface and the electrochemical potential increase rate were strictly defined. The monitoring of the free corrosion potential of two austenitic steels and a duplex steel, in the constant flowing conditions, as well as the redox potential, temperature, chloride and oxygen content, have been carried out during six months in the natural seawater from the Adriatic Sea at the location in Dubrovnik, Croatia. Sharp drop of the corrosion potential was used as an indication of the crevice corrosion initiation. After exposure to the seawater eventual crevice damage on a steel specimen was detected by visual and microscopic inspections.

In the synthetic seawater the organic component was simulated by glucose and glucose oxidase [3, 4]. The monitoring of the free corrosion potential and the redox potential was performed at 20, 30 and 40°C during five days, and results compared with those obtained in the natural seawater at same temperatures.
HPLC–SPE–NMR in pharmaceutical development: capabilities and applications
Authors: Sandvoss Martin , Bardsley Ben , Beck Tony L. , Lee‐Smith Emma , North Stephanie E. , Moore Peter J. , Edwards Andrew J. , Smith Richard J.
Published: July 2005

High‐performance liquid chromatography–solid phase extraction–NMR spectroscopy (HPLC–SPE–NMR) has recently become commercially available and has been evaluated with regard to its applicability in a pharmaceutical environment. The addition of an automated SPE unit to an HPLC–NMR system for peak trapping results in an improved NMR signal‐to‐noise ratio (S/N) and also has other practical advantages. The trapping efficiency is shown to depend on compound polarity and is highest for compounds eluting late on reversed‐phase HPLC systems. Multiple peak trapping further increases the S/N, again with the best results for less polar compounds. For polar compounds, multiple peak trapping resulted in no S/N gain as the amount of material retained on the SPE cartridge was equivalent to that from a single injection. When compared with conventional HPLC–NMR, a S/N gain of up to five‐fold could be achieved for some compounds in a single trapping step. A major advantage of the technique is the independence of the chromatographic step from the NMR step, resulting in greater versatility than conventional HPLC–NMR in the HPLC solvents and NMR solvents that can be used. Practical applications from both drug metabolite and drug impurity identification are presented. Copyright © 2005 John Wiley & Sons, Ltd.
Insights into cyclodextrin interactions during sample stacking using capillary isotachophoresis with on‐line microcoil NMR detection
Authors: Almeida Valentino K. , Larive Cynthia K.
Published: July 2005

On‐line capillary isotachophoresis (cITP)–NMR experiments were used to probe the interactions of the pharmaceutical compounds S‐alprenolol, S‐atenolol, R‐propranolol, R‐salbutamol and S‐terbutaline with β‐cyclodextrin (β‐CD) during cITP concentration. In cITP, ionic analytes are concentrated and separated on the basis of their electrophoretic mobility. Because neutral molecules have an electrophoretic mobility of zero, they are normally not concentrated or separated in electrophoretic experiments like cITP. Most of the analytes studied were concentrated by cITP sample stacking by a factor of around 300. For analytes that formed a strong inclusion complex, β‐CD co‐concentrated during cITP sample stacking. However, once the focusing process was complete, a discrete diffusional boundary formed between the cITP‐focused analyte band and the leading and trailing electrolyte, which restricted diffusion into and out of the analyte band. Copyright © 2005 John Wiley & Sons, Ltd.
Determination of regulatory phosphorylation sites in nanogram amounts of a synthetic fragment of ZAP‐70 using microprobe NMR and on‐line coupled capillary HPLC–NMR
Authors: Hentschel Petra , Krucker Manfred , Grynbaum Marc David , Putzbach Karsten , Bischoff Rainer , Albert Klaus
Published: July 2005

The protein kinase ZAP‐70 is involved in T‐cell activation and interacts with tyrosine‐phosphorylated peptide sequences known as immunoreceptor tyrosine activation motifs (ITAMs). We have studied the regulatory phosphorylation sites in the tryptic fragment containing amino acids 485–496 (ALGADDSYYTAR). The four possible peptides with phosphorylation at none, one, or both of the Y‐492 and Y‐493 tyrosines were specifically synthesized and analyzed by 1H/13C–NMR at 600 MHz using a capillary HPLC–NMR microprobe. Unambiguous discrimination of the peptides was possible via effect of chemical shifts of phosphorylation on the aromatic tyrosine protons. With the microprobe and the detection volume of 1.5 µl, it was possible to perform structure elucidation with the very small amounts available for the various peptides. For the syringe injection, 15 µg of the analyte were used (corresponding to ca 2 mg in classical 5‐mm tubes). Capillary HPLC–NMR spectra were recorded in the stopped‐flow mode from less than 400 ng of each peptide, using 1D and 2D techniques (1H,1H–COSY‐90, 1H/13C–HSQC, and 1H/13C–HMBC). Copyright © 2005 John Wiley & Sons, Ltd.
Identification of secondary metabolites from Streptomyces violaceoruber TÜ22 by means of on‐flow LC–NMR and LC–DAD–MS
Authors: Pham L. H. , Vater J. , Rotard W. , Mügge C.
Published: July 2005

For rapid screening of natural products from Actinomycetes, a combination of on‐line couplings LC–NMR, LC–DAD–MS and HPLC–PDA, as well as MALDI–TOF–MS is particularly suitable. Simultaneous use of these coupling techniques provides considerable advantages for the rapid identification of natural compounds in mixtures.

The results of our present investigation on secondary metabolite products of Streptomyces violaceoruber TÜ 22 showed that more than 50% of the identified metabolites are new compounds. The structures of four new polyketides (granaticin C, metenaticin A, B and C) as well as four known ones (granaticin A, granatomycin E, daidzein and genistein) have been elucidated using LC–NMR, LC–MS/MS and –MSn techniques in combination with two‐dimensional NMR spectroscopy. Copyright © 2005 John Wiley & Sons, Ltd.
HPLC–NMR for tissue‐specific analysis of phenylphenalenone‐related compounds in Xiphidium caeruleum (Haemodoraceae)
Authors: Schneider Bernd , Paetz Christian , Hölscher Dirk , Opitz Stefan
Published: July 2005

HPLC–1H NMR has been used to study the tissue‐specific distribution of phenylphenalenones, polyphenolic natural products of Xiphidium caeruleum, a neotropical member of the Haemodoraceae plant family. The present results provide insight into the occurrence of phenylphenalenone‐related compounds in root segments of whole plants and different in vitro culture lines of the same species. Copyright © 2005 John Wiley & Sons, Ltd.
Mouse zygotes with one diploid pronucleus formed as a result of ICSI can develop normally beyond birth
Authors: Krukowska Anna , Tarkowski Andrzej K.
Published: July 2005

A mouse spermatozoon was injected into mouse secondary oocytes (ICSI) in the vicinity of the metaphase spindle. In 22% of oocytes injected successfully, the maternal chromatin (the haploid chromatids formed after the second meiotic division) and paternal chromatin (from the sperm nucleus) were surrounded by a common nuclear envelope to form one diploid bi‐parental pronucleus. However, the use of spermatozoa in which BrdU had been incorporated into DNA during spermatogenesis revealed, that maternal and paternal chromatin occupied two separate compartments within the one pronucleus. In the living state, the diploid pronucleus could be distinguished from a haploid one by its distinctly larger size and by a greater number of “nucleolus‐like bodies”—criteria confirmed karylogically at the 1st cleavage division. Such zygotes with one diploid pronucleus were able to develop in vitro into blastocysts as often as those with two haploid pronuclei [11/29 (38%) vs. 14/35 (40%)]. Seventy nine 2‐cell embryos developing in vitro from zygotes with one diploid pronucleus were transplanted to the oviducts of pseudopregnant recipients: two females had six foetuses when killed on the 17th day, and two females gave birth to nine young, eight of which survived and developed into normal fertile animals. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
Paratesticular metastasis from Wilms tumor associated with a hydrocele
Authors: Aydın G. Burça , Çiftçi Arbay Ö. , Yalçın Bilgehan , Akçören Zuhal , Çağlar Melda , Şenocak Mehmet E. , Büyükpamukçu Münevver
Published: July 2005

Metastatic sites other than the lungs, lymph nodes, and liver are unusual for Wilms tumor (WT). Intra‐scrotal metastasis is very rare. We report a 3‐year‐old boy with stage IIA WT, who experienced paratesticular metastasis 2 months after surgery for an abdominal recurrence. He had right scrotal hydrocele at initial diagnosis. The patient underwent right radical orchiectomy, and pathological examination revealed paratesticular WT metastasis. Intra‐abdominal and peritoneal disseminated metastases followed. We considered that tumor cells spread through the patent processus vaginalis and grew at paratesticular space in hydrocele. One month after the end of 12 months of salvage chemotherapy and abdominal radiotherapy, the patient has no evidence of disease. © 2005 Wiley‐Liss, Inc.
Frequency independent‐dependent conductivity and dielectric properties of some ionomers
Authors: Yakuphanoglu Fahrettin , Erten Hilmi
Published: July 2005

The preparation and physical properties of some ionomers have been investigated. The addition of CH3I significantly improved the conductivity of the ionomers. At room temperature, the highest ionic conductivity value was found to be 4.93 10−8 S cm−1 in the I4 ionomer. The conductivity data do not obey the Arrhenius law and the non‐linearity indicates ionic transport. The alternating current conductivity parameters and dielectric constants of the ionomers were determined. Copyright © 2005 Society of Chemical Industry
An evaluation, comparison, and accurate benchmarking of several publicly available MS/MS search algorithms: Sensitivity and specificity analysis
Authors: Kapp Eugene A. , Schütz Frédéric , Connolly Lisa M. , Chakel John A. , Meza Jose E. , Miller Christine A. , Fenyo David , Eng Jimmy K. , Adkins Joshua N. , Omenn Gilbert S. , Simpson Richard J.
Published: July 2005

MS/MS and associated database search algorithms are essential proteomic tools for identifying peptides. Due to their widespread use, it is now time to perform a systematic analysis of the various algorithms currently in use. Using blood specimens used in the HUPO Plasma Proteome Project, we have evaluated five search algorithms with respect to their sensitivity and specificity, and have also accurately benchmarked them based on specified false‐positive (FP) rates. Spectrum Mill and SEQUEST performed well in terms of sensitivity, but were inferior to MASCOT, X!Tandem, and Sonar in terms of specificity. Overall, MASCOT, a probabilistic search algorithm, correctly identified most peptides based on a specified FP rate. The rescoring algorithm, PeptideProphet, enhanced the overall performance of the SEQUEST algorithm, as well as provided predictable FP error rates. Ideally, score thresholds should be calculated for each peptide spectrum or minimally, derived from a reversed‐sequence search as demonstrated in this study based on a validated data set. The availability of open‐source search algorithms, such as X!Tandem, makes it feasible to further improve the validation process (manual or automatic) on the basis of “consensus scoring”, i.e., the use of multiple (at least two) search algorithms to reduce the number of FPs.∁
Synthesis of well‐defined polymers end‐functionalized with crosslinkable aziridine groups by living anionic polymerization
Authors: Kobayashi Mamoru , Uchino Kentaro , Ishizone Takashi
Published: July 2005

Well‐defined end‐functionalized polystyrene, poly(α‐methylstyrene), and polyisoprene with polymerizable aziridine groups were synthesized by the termination reactions of the anionic living polymers of styrene, α‐methylstyrene, and isoprene with 1‐[2‐(4‐chlorobutoxy)ethyl]aziridine in tetrahydrofuran at −78 °C. The resulting polymers possessed the predicted molecular weights and narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight < 1.1) as well as aziridine terminal moieties. The cationic ring‐opening polymerization of the ω‐monofunctionalized polystyrene having an aziridinyl group with Et3OBF4 gave the polymacromonomer, whereas the α,ω‐difunctional polystyrene underwent crosslinking reactions to afford an insoluble gel. Crosslinking products were similarly obtained by the reaction of the α,ω‐diaziridinyl polystyrene with poly(acrylic acid)‐co‐poly(butyl acrylate). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4126–4135, 2005
Polymerization of 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐D‐mannitol, 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐L‐iditol, and 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐allitol using zinc complexes: The regio‐ and stereoselectivities and asymmetric synthesis of thiosugar polymers
Authors: Satoh Toshifumi , Imai Tomoko , Sugie Norihiko , Hashimoto Hisaho , Kakuchi Toyoji
Published: July 2005

The polymerizations of the diepisulfides 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐D‐mannitol (1a), 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐L‐iditol (1b), and 1,2:5,6‐diepithio‐3,4‐di‐O‐methyl‐allitol (1c) were carried out with ZnEt2/H2O, ZnEt2/alcohol, and ZnEt2/(S or R)‐1,1′‐bi‐2‐naphthol (BN) as the initiator systems. All the polymerizations proceeded without any gel formation and gave white, powdery products. The number‐average molecular weights of the obtained polymers were changed in the range of 5300–33,600. The polymerization of 1a using the ZnEt2/H2O (1/1) catalyst in tetrahydrofuran proceeded through a regio‐ and stereoselective cyclopolymerization mechanism to produce thiosugar polymers mainly consisting of 2,5‐anhydro‐1,5‐dithio‐D‐glucitol as the five‐membered ring units. The polymers obtained from 1b and 1c with ZnEt2/H2O exhibited lower stereoregularities than that from 1a. For the polymers obtained from 1a with the ZnEt2/alcohol systems, the molar fraction of the five‐membered ring units depended on the alcohol used as a ligand. On the other hand, the polymerization of 1c using ZnEt2/(R or S)‐BN asymmetrically proceeded, and optically active polymers consisting of desulfurized acyclic units were obtained. When ZnEt2/(R)‐BN (1/1) was used in toluene, the polymer with [α]D23 = +56.9° was obtained in an 88.6% yield. The resulting polymer had an isotactic‐rich structure consisting of about 90% (R)‐configurational units and about 10% (S)‐units. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4118–4125, 2005
Antimicrobial polymers containing melamine derivatives. II. Biocidal polymers derived from 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine
Authors: Chen Zhaobin , Sun Yuyu
Published: July 2005

Poly(2‐vinyl‐4,6‐diamino‐1,3,5‐triazine) (PVDAT) and a series of poly(styrene‐co‐2‐vinyl‐4,6‐diamino‐1,3,5‐triazine) (PS‐co‐VDAT) copolymers were synthesized via conventional free‐radical polymerizations. The polymer structures were confirmed by Fourier transform infrared, NMR, and elemental analysis. The molecular weights were determined by gel permeation chromatography studies, and the thermal properties were characterized by differential scanning calorimetry and thermogravimetric analysis. After treatment with chlorine bleach, PVDAT and PS‐co‐VDAT provided potent antimicrobial functions against multidrug‐resistant Gram‐negative and Gram‐positive bacteria. The antimicrobial functions were durable for longer than 3 months and rechargeable for more than 50 times. The structure–property relationship of the polymers was further discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4089–4098, 2005
Densely grafting copolymers of ethyl cellulose through atom transfer radical polymerization
Authors: Shen Dawa , Yu Hui , Huang Yong
Published: July 2005

Densely grafting copolymers of ethyl cellulose with polystyrene and poly(methyl methacrylate) were synthesized through atom transfer radical polymerization (ATRP). First, the residual hydroxyl groups on the ethyl cellulose reacted with 2‐bromoisobutyrylbromide to yield 2‐bromoisobutyryloxy groups, known to be an efficient initiator for ATRP. Subsequently, the functional ethyl cellulose was used as a macroinitiator in the ATRP of methyl methacrylate and styrene in toluene in conjunction with CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as a catalyst system. The molecular weight of the graft copolymers increased without any trace of the macroinitiator, and the polydispersity was narrow. The molecular weight of the side chains increased with the monomer conversion. A kinetic study indicated that the polymerization was first‐order. The morphology of the densely grafted copolymer in solution was characterized through laser light scattering. The individual densely grafted copolymer molecules were observed through atomic force microscopy, which confirmed the synthesis of the densely grafted copolymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4099–4108, 2005
Self‐heating and conduction of an acetylene carbon black filled high‐density polyethylene composite at the electric–thermal equilibrium state
Authors: Song Yihu , Zheng Qiang
Published: July 2005

The electric self‐heating and conduction behaviors of a high‐density polyethylene/carbon black composite at the electric–thermal equilibrium state are studied. An equation describing the current density/electric‐field strength (J–E) characteristic is derived on the basis of an equation proposed for the self‐heating temperature as a function of the field strength. The conduction is related to the electronic tunneling and the resistor breakdown due to self‐heating that dominate the nonlinear J–E characteristic below and above a critical field strength corresponding to the J maximum, respectively. The influences of the initial structure of the percolation network and the physical state of the matrix on the conduction are also discussed on the basis of scaling arguments of the self‐heating and the nonlinear J–E characteristic with respect to the initial resistivity at various ambient temperatures from 19 to 120 °C. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2484–2492, 2005
Composition dependence of ordered structures in mixed micellar aqueous solutions of hydrophobically modified poly(ethylene glycol)s
Authors: Iizuka Kenichi , Numasawa Naoko , Hiraoka Kazuyuki , Yamazaki Ritsuko , Nose Takuhei
Published: July 2005

Ordered structures of micellar aqueous solutions of poly(ethylene glycol) (PEG) monododecylether mixtures [octaethylene glycol monododecylether (C12E8) and poly(ethylene glycol) monododecylether (C12E25)] have been investigated as a function of the C12E8/C12E25 composition by means of X‐ray scattering. C12E8 and C12E25 have different chain lengths of corona PEG, that is, 8 and 25 repeating units, respectively. The following results have been obtained. First, in the C12E8‐rich and C12E25‐rich regions, the mixtures take hexagonal and cubic phases, respectively. The hexagonal phase remains over a wider range of compositions and is more stable for the mixing of the other component than the cubic phase. Second, in the C12E8‐rich region of the cylindrical hexagonal packing, the nearest‐neighbor micellar distance increases, whereas the association number density remains constant, with an increasing amount of mixed C12E25 possessing longer corona chains. Third, in contrast to this, the nearest‐neighbor micellar distance of the body‐centered cubic packing exhibits almost no change, whereas the association number increases as C12E8 of shorter corona chains is increasingly incorporated. Fourth, self‐consistent field calculations reasonably reproduce the experimental findings of the second and third observations. We discuss the phase stability and the structural changes with the composition in terms of differences in the PEG corona‐chain length. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2474–2483, 2005
Exhaustive Metropolis Monte Carlo sampling and analysis of polyalanine conformations adopted under the influence of hydrogen bonds
Authors: Podtelezhnikov Alexei A. , Wild David L.
Published: July 2005

We propose a novel Metropolis Monte Carlo procedure for protein modeling and analyze the influence of hydrogen bonding on the distribution of polyalanine conformations. We use an atomistic model of the polyalanine chain with rigid and planar polypeptide bonds, and elastic α carbon valence geometry. We adopt a simplified energy function in which only hard‐sphere repulsion and hydrogen bonding interactions between the atoms are considered. Our Metropolis Monte Carlo procedure utilizes local crankshaft moves and is combined with parallel tempering to exhaustively sample the conformations of 16‐mer polyalanine. We confirm that Flory's isolated‐pair hypothesis (the steric independence between the dihedral angles of individual amino acids) does not hold true in long polypeptide chains. In addition to 310‐ and α‐helices, we identify a kink stabilized by 2 hydrogen bonds with a shared acceptor as a common structural motif. Varying the strength of hydrogen bonds, we induce the helix–coil transition in the model polypeptide chain. We compare the propensities for various hydrogen bonding patterns and determine the degree of cooperativity of hydrogen bond formation in terms of the Hill coefficient. The observed helix–coil transition is also quantified according to Zimm–Bragg theory. Proteins 2005. © 2005 Wiley‐Liss, Inc.