bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlling the formation of indole and skatole in in vitro rumen fermentations using condensed tannin
Authors: Schreurs Nicola M , Tavendale Michael H , Lane Geoffrey A , Barry Tom N , López‐Villalobos Nicolas , McNabb Warren C
Published: February 2007

Indole and skatole are formed in the rumen from the fermentation of tryptophan and have been correlated to the presence of undesirable pastoral flavours in meat from grazing ruminants. A series of four in vitro rumen fermentation experiments was carried out to determine the effectiveness of condensed tannin (CT) for reducing the formation of indole and skatole. Experiment 1 utilised fresh white clover (WC; Trifolium repens) in ratios with the CT‐containing forage Lotus pedunculatus (LP; 97 g CT kg−1 dry matter (DM)). Increasing the ratio of LP to WC decreased the formation of indole and skatole. Experiments 2 and 3 used extracts of CT from LP and grape seed added to incubations of fresh non‐CT‐containing WC or perennial ryegrass (PRG; Lolium perenne). Including the CT extracts in incubations at 40 and 80 g kg−1 DM was more effective at reducing indole and skatole formation than lower concentrations of CT extract (P < 0.05). Including fresh LP in ratios with WC gave a linear decrease in indole and skatole concentration (indicating dilution), while including a CT extract in the incubations gave an exponential decrease in indole and skatole concentration (suggesting binding). Experiment 4 elucidated the mechanisms behind the action of CT by delayed addition of tryptophan and polyethylene glycol (PEG) to incubations of LP. Rumen microbes that were exposed to CT of LP in planta for up to 6 h and then provided with tryptophan were still able to convert tryptophan to indole and skatole. Adding PEG to incubations of LP after 6 h inhibited the activity of plant CT and increased the availability of substrate for indole and skatole formation. These studies have shown that a higher concentration of CT is more efficient for reducing indole and skatole formation and that CT contained within plants acts differently in in vitro rumen fermentations than additions of extracted CT. Under the conditions of these experiments, there was no evidence that CT contained in LP affected the protein present in WC in a mixed fermentation. Copyright © 2007 Society of Chemical Industry
Synthesis and Characterisation of Organogels from ABA Triblock Copolymers
Authors: Monge Sophie , Joly‐Duhamel Christine , Boyer Cyrille , Robin Jean‐Jacques
Published: February 2007

Polystyrene‐block‐poly(2‐ethylhexanyl acrylate)‐block‐polystyrene triblock copolymers with different molar masses were synthesised by atom transfer radical polymerisation which led to the formation of elastic gels in paraffin oil. Copolymers with control over molecular weight and low polydispersity were first obtained with different midblock lengths (10 000, 20 000, 60 000 g · mol−1). In paraffin oil, some triblock copolymers led to a gelation process due to appropriate chain length and concentration. We assumed that polystyrene endblocks aggregated into micelles whereas poly(2‐ethylhexanyl acrylate) midblocks formed loops or bridges between different micelles leading to the formation of a physical network of interconnected polymer chains. Rheological measurements proved that time and slow controlled cooling improved the elastic properties with the creation of new interactions in the network.

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Exposure Reciprocity Law in Photopolymerization of Multi‐Functional Acrylates and Methacrylates
Authors: Feng Li , Suh Byoung I.
Published: February 2007

The applicability of the exposure reciprocity law (ERL) to the photopolymerization of acrylates and methacrylates was investigated. It was found that when the oligomer/monomer mass ratio in the systems studied was equal to or greater than 6:4, the ERL applied quite well. The applicability of the ERL to individual (meth)acrylates was judged by comparing the ratio of the lowest DC under one of the three I‐t combinations to the highest DC under another I‐t combination. The ERL is deemed to apply better to a monomer whose ratio is close to unity. It was found that the viscosity and the number of double bonds are two primary attributes. Photopolymerization of those with more than one double bond and with viscosity higher than 100‐200 mPa · s closely obeys the ERL. This is because the two factors promote the realization of the reaction‐diffusion‐controlled process, which facilitates monomolecular termination of free radicals.

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Aryltriazene Photopolymers for UV‐Laser Applications: Improved Synthesis and Photodecomposition Study
Authors: Nagel Matthias , Hany Roland , Lippert Thomas , Molberg Martin , Nüesch Frank A. , Rentsch Daniel
Published: February 2007

An improved synthesis of photosensitive homopolymers containing aryltriazene chromophores covalently incorporated into the polymer backbone is reported. Such photopolymers proved to have promising properties for novel UV‐laser applications. A homologous series of new aryltriazene polymers with increasingly branched side chains (R = Me, Et, iPr, tBu) was synthesized and characterized. Homogeneous thin films with thicknesses from ≈15 to >150 nm were prepared by spin‐coating. Photodecomposition was studied in solution and on thin films. Polymers with increasingly branched and bulky substituents showed decreasing photodissociation rates. NMR studies suggested an enhanced hindrance of the N(2)–N(3) bond rotation in the aryltriazene moiety with increasing steric demand of the substituents.

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Cover Picture: Macromol. Chem. Phys. 3/2007
Authors: Nagel Matthias , Hany Roland , Lippert Thomas , Molberg Martin , Nüesch Frank A. , Rentsch Daniel
Published: February 2007

Cover: The figure shows a SEM picture of a smooth aryltriazene photopolymer film (thickness 360 nm): part of a typical ablation spot done by 6 pulses of an excimer laser (λ = 308 nm, 90 mJ/cm2), demonstrating the clear cut edges and the absence of debris or carbonization. An improved synthesis for such thin‐film forming photopolymers was reported. Further details can be found in the Full Paper by M. Nagel,* R. Hany, T. Lippert, M. Molberg, F. A. Nüesch, and D. Rentsch on page 277.
Parameters of bladder function in pre‐, peri‐, and postmenopausal continent women without detrusor overactivity
Authors: Pfisterer Mathias H.‐D. , Griffiths Derek J. , Rosenberg Lisa , Schaefer Werner , Resnick Neil M.
Published: February 2007

Aims

To determine normative data for lower urinary tract function in asymptomatic continent women without detrusor overactivity (DO) across the age span.

Methods

Healthy female volunteers aged ≥20 years were recruited from the community. Comprehensive assessment included bladder diary, physical examination, uroflowmetry, and videourodynamics. Continent women without history of frequent urgency and without DO were selected. Data on bladder storage, voiding and urethral sphincter function, urine output and frequency are presented for pre‐, peri‐, and postmenopausal women.

Results

Twenty‐four asymptomatic women (mean age 50.2 years, range 22–80 years) met the inclusion criteria, including 7 pre‐ (29.2 years), 7 peri‐ (48.8 years), and 10 postmenopausal (66.0 years) women. For all subjects, maximum single voided volume in bladder diary was 500 ml and maximum cystometric capacity was 580 ml (median values). Strong desire to void (SDV) was reported at 287, 366, and 425 ml for pre‐, peri‐, and postmenopausal groups, respectively. The maximum flow rate was 25, 32, and 23 ml/sec in uroflowmetry and 23, 24, and 18 ml/sec in pressure‐flow study, respectively. Median post‐void residual volume (PVR) was below 20 ml in all groups. At maximum flow rate subjects voided with detrusor pressures of 29, 26, and 24 cm H2O, respectively. Maximum urethral closure pressure was 94, 74, and 42 cm H2O, respectively.

Conclusions

We provide normative data on bladder function in asymptomatic, continent, pre‐, peri‐, and postmenopausal women without DO. Neurourol. Urodynam. 26:356–361, 2007. © 2007 Wiley‐Liss, Inc.
Effect of traces of inorganic content on thermal stability of poly(methyl methacrylate) nanocomposites
Authors: Wang Haitao , Meng Sheng , Xu Peng , Zhong Wei , Du Qiangguo
Published: February 2007

Silica/titania binary inorganic component was synthesized by a nonhydrolytic sol‐gel method. Fourier transform infrared spectroscopy (FT‐IR) and transmission electron microscopy (TEM) results indicated that titania was stabilized by silica because of the formation of a connecting structure, which would greatly restrain the high aggregation tendency of titania nanoparticles. The thermal stabilities of the PMMA/silica/titania ternary nanocomposites were measured by thermo‐gravimetric analysis (TGA). Although the solvent extraction results confirmed that there were no covalent bond interactions between polymer and inorganic phases, the trace amount of stabilized titania improved the thermal and thermo‐oxidative stabilities of PMMA because titania/silica nanoparticles may have ability to trap the free radicals generated in the degradation of PMMA. POLYM. ENG. SCI., 47:302–307, 2007. © 2007 Society of Plastics Engineers.
Synthesis and characterization of poly(butylene succinate)/epoxy group functionalized organoclay
Authors: Chen Guang‐Xin , Kim Hun‐Sik , Yoon Jin‐San
Published: February 2007

Poly(butylene succinate) (PBS)/clay nanocomposites were prepared by condensation polymerization of 1,4‐butanediol and succinic acid in the presence of an organoclay containing epoxy groups (TFC) and titanium(IV) butoxide as a catalyst. The intercalation and exfoliation of the clay layers in the resulting composite were examined using X‐ray scattering and transmission electron microscopy. The role of the epoxy groups of TFC was investigated for the improvement of the morphology of the composites. The silicate layers in the composite were exfoliated to a greater extent as the epoxy content of TFC was increased from 0.245 to 0.359 mmol g−1, while only intercalated morphology was obtained when no epoxy was present. The improved morphologies were attributed to the enhanced interfacial interactions between PBS and TFC through a chemical reaction of the epoxy groups with the end groups of the PBS. The nonisothermal crystallization process of the composites as well as that of neat PBS is well represented by the Avrami equation as modified by Jeziorny [Jeziorny A, Polymer 19:1142 (1978)]. The crystallization of the composite took place faster as the epoxy content of the clay increased, due to the more effective nucleation of the well‐dispersed TFC layers. Copyright © 2007 Society of Chemical Industry
15N‐Metabolic labeling for comparative plasma membrane proteomics in Arabidopsis cells
Authors: Lanquar Viviane , Kuhn Lauriane , Lelièvre Françoise , Khafif Mehdi , Espagne Christelle , Bruley Christophe , Barbier‐Brygoo Hélène , Garin Jérôme , Thomine Sébastien
Published: February 2007

An important goal for proteomic studies is the global comparison of proteomes from different genotypes, tissues, or physiological conditions. This has so far been mostly achieved by densitometric comparison of spot intensities after protein separation by 2‐DE. However, the physicochemical properties of membrane proteins preclude the use of 2‐DE. Here, we describe the use of in vivo labeling by the stable isotope 15N as an alternative approach for comparative membrane proteomic studies in plant cells. We confirm that 15N‐metabolic labeling of proteins is possible and efficient in Arabidopsis suspension cells. Quantification of 14N versus 15N MS signals reflects the relative abundance of 14N and 15N proteins in the sample analyzed. We describe the use of 15N‐metabolic labeling to perform a partial comparative analysis of Arabidopsis cells following cadmium exposure. By focusing our attention on plasma membrane proteins, we were able to confidently identify proteins showing up to 5‐fold regulation compared to unexposed cells. This study provides a proof of principle that 15N‐metabolic labeling is a useful technique for comparative membrane proteome studies.
Synthesis of raspberry‐like silica/polystyrene/silica multilayer hybrid particles via miniemulsion polymerization
Authors: Qiao Xiaoguang , Chen Min , Zhou Juan , Wu Limin
Published: February 2007

Organic–inorganic hybrid particles have many potential applications, but almost all research has been focused on hybrid particles with one kind of inorganic nanoparticle. This article presents a novel and facile preparation approach for raspberry‐like silica/polystyrene/silica multilayer hybrid particles via miniemulsion polymerization. In this method, larger, surface‐modified silica particles are first dispersed into monomer droplets to form a miniemulsion, and then raspberry‐like silica/polystyrene/silica multilayer hybrid particles are directly obtained when miniemulsion polymerization is performed in the presence of smaller, unmodified silica particles with 4‐vinylpyridine as an auxiliary monomer. Influential parameters such as the amount of 4‐vinylpyridine, the surfactant concentration, and the pH value of the system have been investigated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1028–1037, 2007
Moduli stabilisation and applications in IIB string theory
Authors: Conlon J.P.
Published: February 2007

String compactifications represent the most promising approach towards unifying general relativity with particle physics. However, naive compactifications give rise to massless particles (moduli) which would mediate unobserved long‐range forces, and it is therefore necessary to generate a potential for the moduli. In the introductory chapters I review this problem and recall how in IIB compactifications the dilaton and complex structure moduli can be stabilised by 3‐form fluxes. There exist very many possible discrete flux choices which motivates the use of statistical techniques to analyse this discretuum of choices. Such approaches generate formulae predicting the distribution of vacua and I describe numerical tests of these formulae on the Calabi‐Yau ℙ4[1,1,2,2,6]. Stabilising the Kähler moduli requires nonperturbative superpotential effects. I review the KKLT construction and explain why this must in general be supplemented with perturbative Kähler corrections. I show how the incorporation of such corrections generically leads to non‐supersymmetric minima at exponentially large volumes, giving a detailed account of theα′ expansion and its relation to Kähler corrections. I illustrate this with explicit computations for the Calabi‐Yau ℙ4[1,1,1,6,9]. The next part of the article examines phenomenological applications of this construction. I first describe how the magnitude of the soft supersymmetry parameters may be computed. In the large‐volume models the gravitino mass and soft terms are volume‐suppressed. As we naturally have 𝒱 ⋙1, this gives a dynamical solution of the hierarchy problem. I also demonstrate the existence of a fine structure in the soft terms, with gaugino masses naturally lighter than the gravitino mass by a factor ln (MP/m3/2). A second section gives a detailed analysis of the relationship of moduli stabilisation to the QCD axions relevant to the strong CP problem, proving a no‐go theorem on the compatibility of a QCD axion with supersymmetric moduli stabilisation. I describe how QCD axions can coexist with nonsupersymmetric perturbative stabilisation and how the large‐volume models naturally contain axions with decay constants that are phenomenologically allowed and satisfy the appealing relationship fa2 ∼MP Msusy. A further section describe how a simple and predictive inflationary model can be built in the context of the above large‐volume construction, using the no‐scale Kähler potential to avoid the ϵ problem. I finally conclude, summarising the phenomenological scenario and outlining the prospects for future work.
Surface hydrophobic modification of chitosan thin films by hexamethyldisilazane plasma deposition: effects on water vapour, CO2 and O2 permeabilities
Authors: Assis Odilio B. G. , Hotchkiss Joseph H.
Published: February 2007

This study evaluated the effects of the deposition of a thin hydrophobic silicon coating onto a polysaccharide film's surface. The goal was to improve the water vapour barrier of the hydrophilic film in order to increase the film's usefulness in packaging applications. A cold‐plasma technique was used to create a thin hexamethyldisilazane deposition on a chitosan film surface. The modification was investigated using Fourier transform infrared. The effect on the surface was characterized through contact angle measurements and degree of swelling. A significant reduction in hydrophilicity and water vapour permeability was observed. Gas barrier measurements indicated that there were no substantial differences in O2 and CO2 permeabilities under the conditions used in this investigation. Copyright © 2007 John Wiley & Sons, Ltd.
Daily and seasonal changes in the surface temperature of fallow soil at rothamsted
Authors: Penman H. L. , Keen B. A.
Published: February 2007

A method of obtaining continuous records are discussed.

The relations between surface and sub‐surface temperatures are briefly considered, and then, in more detail, the inter‐dependence of soil surface and air temperatures is examined. At all seasons the soil temperature is in phase with solar radiation whereas the maximum air temperature is delayed; for air maxima below 52° F. the daily range of soil surface temperature is approximately the same as that of the air temperature. Above this threshold the soil surface maximum increases twice as rapidly as the air maximum. Using this value of the air maximum, 5244F., to divide the year into two seasons, it is found that the winter and summer periods so separated are the same as those previously obtained form the criterion:—Seasonal evaporation is equal to or less than that from an open water surface. Interest is primarily centred on the summer season, in which the soil surface temperature exceeds that of the air for a considerable part of the day, and for a rainless summer period of t days an anticipated relation of the form ΣE=at1/n, where n=3, a is a constant and ΣE=the total evaporation, is confirmed from the Rothamsted records.

The effect of the diurnal oscillation of surface temperature on germinating seed is briefly discussed.
Cold winters at kew observatory, 1783–1942
Authors: Drummond A. J.
Published: February 2007

Continuous meteorological observations have been kept in the Richmond district of London for the last hundred and sixty years. During the early half of the period the observations were made first at Syon House, Isleworth, and then at Chiswick, those in the latter half being made at Kew Observatory. The only gap in the records of temperature was one of four years between the first and second series, a period for which other London data are fortunately available. The monthly means, derived from the Syon House and Chiswick registers, were corrected to bring them into line with the corresponding monthly values obtained from the hourly measurements of the traces from the photographic thermograph in the North Wall screen at Kew Observatory. A series of mean monthly winter temperatures, as homogeneous as can reasonably be expected over such a long period, has therefore been constructed. The last three of these wintres, 1939‐40, 1940‐41 and 1941‐42 have been dealt with in considerable detail.
The determination of the location and frequency of thunderstorms by a radio method
Authors: Forrest J. S.
Published: February 2007

A method is described of continuously recording atmospherics in order to obtain warning of the outbreak of thunderstorm and to determine the distance of the storm form the recording site.

The apparatus consists essentially of a radio receiver tuned to approximately 150 kc./s. and connected to a continuous chart output recording meter; a modulated oscillattor is incorporated in order to maintain constant the characteristics of the receiver.

The paper gives the results of three years' experience with this recording technique.

By correlating the output recorder deflections with the known locations of electric power system breakdowns due to lightning, the relation between the recorder output and the storm distance has been determined. For distances up to 600 km. the equivalent field strength of atmospherics at 150 kc./s. has been found to be inversely proportional to the square root of the distance of the source.

Many nearby storms have been recorded, and two or three hours' warning of the outbreak of the storm has always been give.

Some examples are included of the location of thunderstorms by means of records made simultaneously at different sites.

The recording apparatus is also used to provide objective statistical information on the frequency of thunderstorms, and details are given of the diurnal variations in the intensity of atmospherics in the South of England.
Ultra‐Violet and daylight rays in relations to the seasons and the solar cycle
Authors: Ashworth J. R.
Published: February 2007

Accounts are given of apparatus used in the measurement of light radiation together with the results of eleven years ' observations of the intensity of ultra‐violet and daylight rays and their ratio. It is shwon that the variation of the ratio of ultra‐violet to daylight rays are also given and a comparison is made with Dr. Pettit's researches at Mount Wilson.
Modeling system behavior for risk and reliability analysis using KBARM
Authors: Sharma Rajiv Kumar , Kumar Dinesh , Kumar Pradeep
Published: February 2007

With advances in technology and the growing complexity of technological systems, the job of the reliability/system analyst has become more challenging as they have to study, characterize, measure and analyze the behavior of systems with the help of various traditional analytical (mathematical and statistical) techniques, which require knowledge of the precise numerical probabilities and component functional dependencies, information which is difficult to obtain. Even if data are available they are often inaccurate and are thus subject to uncertainty, i.e. historical records can only represent the past behavior and may be unable to predict the future behavior of the equipment. To cope with such situations, the knowledge‐based approximate reasoning methodologies (KBARMs) provide necessary help. Among them, the fuzzy and grey methodologies are the most viable and effective tools for coping with imprecise, uncertain and subjective information in a consistent and logical manner. In this paper, the authors present a methodological and structured approach (which makes use of both qualitative and quantitative techniques) to model, analyze and predict the failurebehavior of two units, namely the forming and press units of a paper machine, using KBARMs. Various system parameters such as repair time, failure rate, mean time between failures, availability and expected number of failures are computed to quantify the system behavior in terms of fuzzy, crisp and defuzzified values. Furthermore, a risk ranking approach based on fuzzy and grey relational analysis is discussed to prioritize various failure causes associated with the components in failure mode and effects analysis (FMEA). Copyright © 2007 John Wiley & Sons, Ltd.
Supercritical fluid extraction and quantification of aflatoxins in Zizyphi Fructus by liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry
Authors: Liau Bing‐Chung , Jong Ting‐Ting , Lee Maw‐Rong , Chang Chieh‐Ming J.
Published: February 2007

An integrated method combining supercritical fluid extraction (SFE) with liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry (LC/APCI‐MS/MS) was developed and successfully applied to quantify aflatoxins (AFs) in Zizyphi Fructus (fruits of Zizyphus jujube), a traditional Chinese medicine. To minimize the potential interferences caused by the complex matrix in Zizyphi Fructus, a SFE pretreatment was performed. In addition, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) spectra were also compared. The results showed that the calibration curves of AFB1, AFB2, AFG1, and AFG2 were all linear over the range of concentration from 1 to 50 ng/g, the squared correlation coefficients (r2) were over 0.995, and the detection limits of the method were between 0.17 and 0.32 ng/g. It showed high recovery and good precision in quantitating AFs in Zizyphi Fructus without further clean‐up. Further, fragmentation pathways of protonated AFs in APCI‐MS/MS were clearly proposed which could predict the existence of AFB or AFG series. To test the empirical validity of the proposed methodology in this paper, eight random samples of Zizyphi Fructus collected from supermarkets and traditional Chinese medicine stores in different geographical areas of Taiwan were analyzed. The results indicated that low levels of AFs were detected in only one of them. Copyright © 2007 John Wiley & Sons, Ltd.
A potential pitfall in 18O‐based N‐linked glycosylation site mapping
Authors: Angel Peggi M. , Lim Jae‐Min , Wells Lance , Bergmann Carl , Orlando Ron
Published: February 2007

A common procedure for identifying N‐linked glycosylation sites involves tryptic digestion of the glycoprotein, followed by the conversion of glycosylated asparagine residues into 18O‐labeled aspartic acids by PNGase F digestion in 18O water. The 3 Da mass tag created by this process is readily observable by liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis, and is often used to identify the sites of N‐linked glycosylation. While using this procedure, we noticed that 60% of the asparagines identified as being glycosylated were not part of the consensus sequence required for N‐linked glycosylation, and thus were not biologically possible. Investigation into the source of this unacceptably high false positive rate demonstrated that even after reversed‐phase cleanup and heat denaturation, the trypsin used for proteolysis was still active and led to the incorporation of 18O into the C‐termini of the peptides during the deglycosylation step. The resulting mass shift accounted for most of the false positive sites, as the database search algorithm confused it with an 18O‐labeled Asp residue near the C‐terminus of a peptide. This problem can be overcome by eliminating trypsin from the solution prior to performing the deglycosylation process, by resuspending the peptides in natural abundance water following deglycosylation, or by allowing 18O incorporation into the C‐terminus as a variable modification during the database search. These methods have been demonstrated on a model protein, and are applicable to the analyses of glycoproteins that are digested with trypsin or another serine protease prior to enzymatic release of the carbohydrate side chains. This study should alert investigators in the field to this potential and unexpected pitfall and provide strategies to overcome this phenomenon. Copyright © 2007 John Wiley & Sons, Ltd.
Use of an integrated MS – multiplexed MS/MS data acquisition strategy for high‐coverage peptide mapping studies
Authors: Chakraborty Asish B. , Berger Scott J. , Gebler John C.
Published: February 2007

Liquid chromatography/mass spectrometry (LC/MS) peptide maps have become a basic tool for characterizing proteins of biological and pharmaceutical interest. The ability to generate reproducible maps with high protein sequence coverage is a central goal of methods development. We have applied a recently developed analytical approach (termed LC/MSE) to LC/MS peptide mapping. Using the LC/MSE approach, the mass detector alternates between a low‐energy scanning mode (MS) for accurate mass peptide precursor identification, and an elevated‐energy mode (MSE) for generation of accurate mass multiplex peptide fragmentation data. In this paper, we evaluate this analytical approach against a tryptic digest of yeast enolase. From the low‐energy data, high peptide map coverage (98% of sequence from peptides >3 amino acids) was reproducibly obtained. The MS signal for essentially equimolar peptides varied over 2 orders of magnitude in intensity, and peptide intensities could be precisely and reproducibly measured. Using the temporal constraint that MSE peptide fragment ions exhibit chromatographic profiles that parallel the precursor ions that generated them, we were able to produce accurate mass time‐resolved MS/MS information for all enolase peptides with sufficient abundance to produce a detectable fragment ion. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of bone minerals by time‐of‐flight secondary ion mass spectrometry: a comparative study using monoatomic and cluster ions sources
Authors: Malmberg Per , Bexell Ulf , Eriksson Cecilia , Nygren Håkan , Richter Katrin
Published: February 2007

Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) is an important tool for the analysis of bone minerals at implant surfaces. Most studies have been performed with monoatomic primary ion sources such as Ga+ with poor secondary molecular ion production efficiency and only elemental distributions and minor fragments of bone minerals have been reported. By using cluster ion sources, such as Au and Bi, identification of larger hydroxyapatite species at m/z 485, 541, 597 and 653, identified as Ca5P3O12, Ca6P3O13, Ca7P3O14 and Ca8P3O15, respectively, became possible. The ions appear to be fragments of the hydroxyapatite unit cell Ca10(PO4)6(OH)2. Each ion in the series is separated by 55.9 m/z units, corresponding to CaO, and this separation might reflect the columnar nature of the unit cell. Copyright © 2007 John Wiley & Sons, Ltd.
Coupled N, C and S stable isotope measurements using a dual‐column gas chromatography system
Authors: Fry Brian
Published: February 2007

Many laboratories routinely analyze plant, animal and soil samples with elemental analyzers coupled to isotope ratio mass spectrometers, obtaining rapid results for nitrogen (%N, δ15N) and carbon (%C, δ13C) from the same sample. The coupled N and C measurements are possible because of a gas chromatography (GC) separation of N2 and CO2 gases produced in elemental analysis. Adding a second GC column allows additional measurement of sulfur (%S, δ34S) from the same sample, so that combined N, C and S information is obtained routinely. Samples are 1–15 mg, and replicates generally differ by less than 0.1‰ for δ15N, δ13C or δ34S. An example application shows that the N, C, and S measurement system allows a three‐dimensional view of element dynamics in estuarine systems that are undergoing pollution inputs from upstream watersheds. Extension of these GC principles should allow coupled H, C, N, and S isotope measurements in future work. Copyright © 2007 John Wiley & Sons, Ltd.
Quantitative analysis of 23‐hydroxybetulinic acid, a novel anticancer substance, in the cellular environment of a human colon adenocarcinoma cell line for cellular pharmacokinetic studies
Authors: Zheng Yuanting , Wang Guangji , Wu Xiaolan , Sun Jianguo , Li Xiaoyu , Gu Yi , Lv Hua , Liang Yan , Yan Bei , Ye Wencai
Published: February 2007

In order to study the cellular distribution and kinetics of a new anticancer substance, 23‐hydroxybetulinic acid, a simple, reproductive and sensitive high‐performance liquid chromatography/mass spectrometric (HPLC/MS) method was developed to quantify its trace concentration in cell suspension and cell culture medium. This method involved a liquid‐liquid extraction with diethyl ether and a subsequent analysis performed on a Shimadzu LCMS 2010A system which contained an electrospray ionization interface. Separation was achieved by HPLC on a Zorbax Extend‐C18 column with gradient elution using a mix of acetonitrile and water containing triethylamine and acetate‐triethylamine as the mobile phase. A total analytical run was achieved within 6.5 min and the calibration curve was linear over a wide concentration range of 1.0–1000.0 nM for both cell suspension and culture medium. Intra‐ and inter‐batch accuracy and precision were acceptable for both matrices. The described assay method was successfully applied to cellular pharmacokinetic studies in a human colon adenocarcinoma cell line (Caco‐2) and its application of measuring the cellular concentrations of 23‐hydroxybetunilic acid could be extended to different cultured cell lines. Copyright © 2007 John Wiley & Sons, Ltd.
The distribution and management of channelized streams in Denmark
Authors: Brookes Andrew
Published: February 2007

The Danish Watercourse Law of 1982 states that major river works and maintenance procedures must be planned and undertaken with regard to water quality and the physical form of the river channel. Fluvial geomorphology is an essential component of alternative procedures of river management which work with nature rather than against it. A survey of Danish stream channels has been produced by collating data obtained from maps, field surveys and engineering documents. This indicates that 97.8 per cent of Danish watercourses have been artificially straightened and that only 2.2 per cent (880 km) have natural morphological characteristics. The density of channel works is 300 times greater than in the U.S.A. and 15 times greater than in England and Wales. It is suggested that since there are only a few naturally sinuous channels in Denmark these should be given special consideration with regard to stream management practices. Measurements undertaken at approximately 300 sites in Denmark indicate five major processes of adjustment within straightened reaches. These adjustments include degradation of the channel bed with associated bank slumping, armouring of the bed, the development of a sinuous thalweg by the deposition of sediment at low gradients, and restoration of meanders. Channel stability is related to specific stream power and the results may be useful in predicting potential adjustments following channel straightening. Deposition in natural reaches below straightened channels often obliterates pool and riffle sequences but several channel adjustments may provide a greater variability of physical habitats than the initial uniform straightened channel; their significance for the biology of the watercourse is best considered before traditional management practices are carried out to control the adjustment.
A method for applied ecological studies of fluvial hydrosystems
Authors: Amoros C. , Roux A. L. , Reygrobellet J. L. , Bravard J. P. , Pautou G.
Published: February 2007

The hydrosystem of the Rhǒne River, France, is considered in 3 dimensions: the upstream‐downstream progression, the transversal dimension (main stream, side‐arms, marshes, flood plain and their interconnections), and the vertical dimension (relationships between epigean and ground waters). Emphasis is placed on the temporal dimension, which considers changes in the river's dynamics, and on the development of its ecosystems over several centuries.

Analyses were performed on different spatial scales; the definitions of functional sectors, functional sets and functional units are based on a combination of geomorphic patterns, fluvial dynamics and ecological processes. Synchronic and diachronic analyses were carried out using functional describers (granulometry and organic content of sediments, floral and faunal communities).

These studies deal mainly with the distrubed hydrosystems of regulated rivers. The changes of the ecological successions are focused on after reference to natural models and the reconstitution of ancient human disturbances. Predictive scenarios are proposed to promote ecological management of the alluvial plains in the event of hydroelectric development.
The influence of kielder water on trichopteran (Caddisfly) populations in the river North Tyne (Northern England)
Authors: Boon P. J.
Published: February 2007

Impounding the North Tyne has reduced the frequency of high peak flows, eliminated periods of extremely low flow and modified the temperature regime downstream from the Kielder dam. This paper compares the results of a recent survey of North Tyne trichopteran populations (Hydropsychidae, Rhyacophilidae, and Polycentropodidae) with those from previously published work in order to assess the impact of river regulation. Benthic samples were collected monthly upstream and downstream from the reservoir. Although nine out of the ten species found previously were also collected in the post‐impoundment survey, species diversity was reduced downstream from the dam. This was mainly the result of disproportionate increases in Hydropsyche siltalai population densities which were up to 9.6 times greater than before; flow regulation and its effect on substrate stability may be largely responsible for this. Rhyacophila dorsalis also increased in abundance downstream probably in response to the altered flow regime. In contrast Hydropsyche pellucidula constituted a smaller proportion in downstream samples with population densities in places only a fifth of pre‐impoundment levels. The differential effect of regulation on these two hydropsychid species may be explained by their different flow velocity preferences. Upstream from the reservoir, standing crops were frequently lower than before possibly due to the disruption of colonization cycles. Growth rates of H. siltalai, H. pellucidula, and R. dorsalis below the dam were accelerated at certain times of the year and retarded at others, apparently correlated with the winter‐warm, summer‐cool discharges from the reservoir. Since this study was completed Kielder Water has now begun generating hydroelectricity, and the flow regime downstream has consequently changed to one of regular, daily fluctuations. It is suggested that any adverse effects of this on the benthic community are likely to be offset by the continued benefit of eliminating flash floods with high peak flows.
Effects of transferring glacier‐fed water to a clear‐water mountain river on the production and food organisms of brown trout (Salmo trutta L.) in Southern Norway
Authors: Hesthagen Trygve , Fjellheim Arne
Published: February 2007

The effects of transferring glacier‐fed water to a clear‐water river on production and food organisms of brown trout (Salmo trutta L.) were investigated in a mountain river, in southern Norway. Production in unregulated fluvial habitat was 271.5 g 100 m−2 yr−1 compared with 103.1 g 100 m−2 yr−1 in a glacier‐fed reach of the river. This difference was due to low fish density and recruitment rate. The growth rate, at least for younger fish (2+ to 4+ age groups), was significantly higher in the regulated reach of the river. The main difference in food composition was the low abundance of crustaceans Eurycercus lamellatus and Gammarus lacustris in the regulated reach. Trichopterans were the main diet component in both sites.
Response of the aquatic macroinvertebrate communities to dam construction on the Thomson river, Southeastern Australia
Authors: Doeg T. J. , Davey G. W. , Blyth J. D.
Published: February 2007

Aquatic macroinvertebrates were sampled above and below the site of the Thomson Dam, Victoria, Australia, over a two‐year period during dam construction. Total number of species and the number of species and individuals per sample were all lower for 33 km below the dam site, compared with sites upstream.

Ordination analysis showed that the major differences between the study sites were related to longitudinal position in the river. The second ordination axis could be related to seasonal changes in the fauna. Variations in the pattern of axis 2 scores at sites downstream of the damsite suggested continuing changes in the community at these sites during the study, possibly due to increases in the density of species favoured by sediment deposition (e.g. Cheumatopsyche sp. 2: Trichoptera, Hydropsychidae).

Classification analysis separated the faunal communities at sites above and below the construction zone. Inverse classifications indicated species with disjunct distributions on either side of the dam site. By comparison with preconstruction data and surrounding undisturbed rivers, species likely to have been disadvantaged by increased sedimentation were identified. These included Atalophlebioides sp. 1 (Ephemeroptera, Leptophlebiidae), Stenoperla australis (Plecoptera, Eustheniidae) and Scirtidae (Coleoptera).
Observed and predicted occurrence of blackflies (diptera: Simuliidae) at fifty reservoir outlets in Britain
Authors: Bass J. A. B. , Armitage P. D.
Published: February 2007

The blackflies present at 50 reservoir outlets throughout mainland Britain were recorded. The observed occurrence of simuliid taxa at sites below upland and lowland reservoirs was compared with the predicted occurrence using predictive equations based on environmental variables.

Below the upland reservoirs five simuliid taxa which were predicted to occur were not recorded. Of these S. reptans gp showed the widest discrepancy between predicted and observed occurrences. Four taxa were recorded at significantly fewer sites than predicted and a further four were present at a small number of sites, not differing greatly from the predicted frequency. A similar pattern was observed at the lowland reservoir outlets but S. noelleri, a species frequently associated with lake outlets, was present at more sites than predicted.

The influence of a reservoir's presence on the simuliid community is discussed in relation to the known requirements of the species occurring and those predicted to occur.
Effects of stream and lake regulation on reproductive success of kokanee in the flathead river system, Montana, U.S.A
Authors: Fraley John , Decker‐Hess Janet
Published: February 2007

Kokanee (Oncorhynchus nerka) provided an important recreational fishery in the Flathead River‐Lake system (Columbia River Basin, U.S.A.‐Canada) until the late 1970s when populations declined dramatically. The declines coincided with peaking river discharge from Hungry Horse Dam during the autumn spawning period and an increase in the duration of lake drawdown caused by the operation of Kerr Dam on the outlet of Flathead Lake. Redds of both river and lakeshore spawners were, therefore, dewatered in winter, causing high freezing and desiccation mortality of eggs during the incubation period. It appeared that growth rates of kokanee were density dependent. Female kokanee from strong year classes (i.e., those produced during years of favourable water levels and flow conditions during the incubation period) were smaller than those from weak year classes when unfavourable conditions for incubation prevailed. A highly significant relationship (r2 = 0.929, p < 0.001) was demonstrated between female kokanee spawner length, river gauge heights, and lake levels during years which produced each year class. The close fit of the relationship was further validated by the strong correlation (r = 0.964) between actual kokanee lengths and predicted lengths. Other factors which could have influenced kokanee year class strength include hatchery plants of kokanee fry, harvest of kokanee by anglers, variations in the carrying capacity of Flathead Lake, and natural fluctuations in egg and fry mortality.
The first five months of the supa reservoir, river Kali, India
Authors: Birasal N. R. , Nadkarni V. B. , Gouder B. Y. M.
Published: February 2007

The Supa Reservoir began to fill in 1984, as part of a hydroelectric power scheme on the Kali River in south‐central India. There were significant increases in electrical conductivity and concentrations of chloride, phosphate, iron and manganese in the impounded water during the filling phase. There were also decreases in pH, turbidity, and dissolved oxygen, accompanied by the evolution of hydrogen sulphide. Nutrients leached from the flooded soil and from decomposition of submerged vegetation contributed to blooms of the cyanobacterium Microcystis aeruginosa. The new reservoir has potential for fisheries based on two major carp species, the mrigal (Cirrhinus mrigala) and the rohu (Labeo rohita).
Changes in the riffle macroinvertebrate fauna of the Tanjil river, Southeastern Australia, during construction of Blue Rock Dam
Authors: Chessman Bruce C. , Robinson David P. , Hortle Kent G.
Published: February 2007

Macroinvertebrates were sampled from riffles upstream and downstream of the Blue Rock Dam construction site and inundation area in late November/early December 1979 (before construction) and 1982 (late in construction). Changes in the downstream fauna were much less than at some other large dam sites in Australia, probably because of improved erosion control. At the downstream sampling stations the total number of taxa collected was similar in both years, but there was a 30‐40 per cent reduction in faunal density; no significant change in density occurred at the upstream station. Multivariate analysis showed that the degree of change in faunal composition between years was similar at upstream and downstream stations. The proportion of fine (<4 mm) inorganic sediment in the streambed increased significantly at downstream stations over the study period, while there was no signficant change upstream. Silt (<250μm) also increased significantly downstream, but never exceeded 1 per cent of inorganic bed material.
River regulation in Spain
Authors: de Jalón Diego García
Published: February 2007

The expansion of river regulation and of related scientific research in Spain since 1982 is reviewed. The number of dams completed each year has decreased and, moreover, the average size of reservoir has continued to decline. It is the creation of many new, relatively small, irrigation reservoirs that is having the greatest impact on the fluvial systems. Recent legislation may promote greater involvement of scientists in the management of these systems not least in the setting of minimum ecological flows.
Food habits of migrating salmonid smolts passing bonneville dam in the Columbia river, 1984
Authors: Muir William D. , Emmett Robert L.
Published: February 2007

The food habits of migrating juvenile steelhead (Salmo gairdneri), sockeye salmon (Oncorhynchus nerka), coho salmon (O. kisutch), and chinook salmon (O. tshawytscha) were identified from April through August 1984 at Bonneville Dam in the Columbia River. During the spring (April‐June), the gammarid amphipods Corophium salmonis and C. spinicorne were the dominant prey for all species. Many insect taxa were also consumed, but in small quantities. Significant diet overlap occurred between all species during the spring due to the importance of Corophium. In summer (July‐August), the importance of Corophium declined in the diet of subyearling chinook salmon and was replaced with Daphnia spp. and adult dipterans (primarily chironomids).
Tributary response to local base level lowering below a dam
Authors: Germanoski Dru , Ritter Dale F.
Published: February 2007

Tributaries located immediately downstream from a dam responded to lowered local base level by incising vertically, widening, and expanding headwardly. The eight tributaries examined, join the Osage River along a 17 km reach directly below the Bagnell Dam in central Missouri. These tributaries flow through unconsolidated alluvium, and respond rapidly to base level lowering.

Local base level lowering below Bagnell Dam is believed to result from a combination of factors, including an increase in channel cross‐sectional area caused by degradation and channel widening, and hydrological desynchronization of the trunk river and the tributaries during periods of high discharge. Of these, degradation appears to be the most important cause of tributary incision. Age dates from cores of trees which project cross‐channel roots indicate that tributary entrenchment has occurred after the closure of Bagnell Dam in 1931.

Root‐armoured knickpoints, subaerially exposed cross‐channel tree roots, broken‐off roots, and ‘within channel’ terraces provided the basis for reconstruction of relative pre‐entrenchment tributary profiles which, when extended to the Osage River confluence, reveals the magnitude of entrenchment at the tributary mouth. The tributaries incised on average, 2·2 m and widened approximately 2·3 m at their mouths. Root armouring protracts the adjustment period of the tributaries and results in stepped longitudinal profiles. Tributary incision is episodic, and the influxes of high sediment discharge are out of phase from tributary to tributary.