bluuebunny/crossref_metadata_2025 huggingface dataset:
Odor control using hollow fiber membrane modules
Authors: Tan Xiaoyao , Li K. , Teo W. K.
Published: March 2005

Odor control using hollow fiber membrane modules has been investigated both theoretically and experimentally. First, a mathematical model for the odor gas removal from gas streams in hollow fiber membrane modules was developed, with which the effects of the liquid flow rate and the reactant concentration in solution on the odor removal were studied. As a result, a criterion to determine the optimum liquid flow rate and reactant concentration required for the odor removal was established. Second, experimental studies on the odor removal, that is, H2S removal from N2 streams in PVDF hollow fiber membrane modules were carried out. The results indicate that H2S with low concentrations can be removed from gas streams effectively and economically, and a very high removal rate could be expected. All the experimental data can be estimated satisfactorily with the presented mathematical model. Finally, application of the hollow fiber membrane module fitted in air conditioners for the indoor air purification was explored and a quick graphic method for designing the membrane module was presented. © 2005 American Institute of Chemical Engineers AIChE J, 2005
One‐component polyurethane adhesives for green wood gluing: Structure and temperature‐dependent creep
Authors: Na Bin , Pizzi A. , Delmotte L. , Lu X.
Published: March 2005

Creep and temperature‐dependent creep, characteristic of one‐component polyurethane adhesives for wet and green structural wood gluing are two different parameters. Testing of standards‐approved commercial polyurethane adhesives for this purpose shows that while ambient temperature creep can be avoided or at least greatly limited according to the formulation used, this is not the case for temperature‐dependent creep. The commercial adhesive formulation characteristics that minimize or enhance ambient temperature and temperature‐dependent creep are identified. Basic principles on the structure of simple polyurethane adhesives influencing temperature‐dependent creep are also identified and discussed. The higher the proportion of all hardened network nodes, the lower creep is likely to be at ambient temperature. Instead, due to segment movement and easier disentanglement with increasing temperature, the lower the proportion of covalently linked nodes and the greater the proportion of just physical entanglement nodes, the greater the temperature‐dependent creep will be. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1231–1243, 2005
A Cyclic Hexapeptide Comprising Alternating α‐Aminoxy and α‐Amino Acids is a Selective Chloride Ion Receptor
Authors: Yang Dan , Li Xiang , Sha Yao , Wu Yun‐Dong
Published: March 2005

In nonpolar solvents, the cyclic hexapeptide 2, which comprises alternating D‐α‐amino and D‐α‐aminoxy acids, adopts a C3‐symmetric conformation with alternating eight (NO turns)‐ and seven (γ turns)‐membered‐ring hydrogen bonds. A series of anion‐binding studies has suggested that 2 can function as an effective anion receptor that not only displays a high selectivity for chloride ions, but also the capability to extract chloride ions from aqueous solutions into organic phases.
Capillary electrophoresis‐mass spectrometry in food analysis
Authors: Simó Carolina , Barbas Coral , Cifuentes Alejandro
Published: March 2005

This work provides an updated overview (including works published till June 2004) on the principal applications of capillary electrophoresis‐mass spectrometry (CE‐MS) together with their main advantages and drawbacks in food science. Thus, analysis of amino acids, peptides, proteins, carbohydrates, or polyphenols by CE‐MS in different foods is reviewed. Also, other natural compounds (e.g., alkaloids) and toxins analyzed by CE‐MS in foods are revised. Moreover, exogenous substances with a potential risk for human health (e.g., pesticides, drugs) detected in foods by CE‐MS are included in this work. The usefulness of CE‐MS for food analysis and the information that this coupling can provide in terms of processing, composition, authenticity, quality, or safety of foods is also discussed.
Design, optimisation, and evaluation of a sheath flow interface for automated capillary electrophoresis‐electrospray‐mass spectrometry
Authors: Liu Charles C. , Alary Jean‐Francois , Vollmerhaus Pauline , Kadkhodayan Miryam
Published: March 2005

A sheath‐flow capillary electrophoresis‐mass spectrometry (CE‐MS) system utilizing a fully integrated large‐bore stainless‐steel emitter electrode tapered at the end for micro‐ionspray operation has been developed and evaluated. A separation capillary with an outer diameter of up to 360 µm was inserted into the electrode thus forming a void volume of less than 15 nL between the capillary end and the electrospray ionisation (ESI) tip. The sheath liquid, usually methanol‐water (80:20) with 0.1% formic acid for positive ion mode or methanol for negative ion mode, was delivered at 0.5–1.0 µL/min. Unlike previously reported CE‐MS interfaces, the CE‐MS probe was incorporated directly onto an Applied Biosystems/MDS SCIEX orthogonal‐spray Turbo “V” ion source for ease of use and automatic operation. This integration enables fast and facile coupling and replacement of the separation capillary without interrupting the ion source configuration, and the sheath liquid supply. The reusable electrospray electrode was precisely fabricated and aligned with the length of the nebulizing gas tube for improved reproducibility. Automation was achieved through software control of both CE and tandem MS (MS/MS) for unattended batch sample analysis. The system was evaluated for attomole‐ to low femtomole‐level profiling of model peptides and protein mixtures, bisphosphates, as well as antiviral nucleosidic drugs in cellular extracts.
Mutation analysis of the MYH gene in an Australian series of colorectal polyposis patients with or without germline APC mutations
Authors: Kairupan Carla F. , Meldrum Cliff J. , Crooks Renee , Milward Elizabeth A. , Spigelman Allan D. , Burgess Bronwyn , Groombridge Claire , Kirk Judy , Tucker Kathy , Ward Robyn , Williams Rachel , Scott Rodney J.
Published: March 2005

The MYH gene has recently been shown to be associated with a recessive form of colorectal adenomatous polyposis. Two common mutations in the MYH gene have been identified that lend themselves to rapid screening. We have examined a series of 302 individuals comprising 120 control subjects, 120 patients diagnosed with adenomatous polyposis but without germline mutations in the APC gene and 62 patients diagnosed with familial adenomatous polyposis all harbouring confirmed causative APC germline mutations. The results reveal that MYH accounts for 16 percent of polyposis patients without germline mutations in the APC gene and that it does not appear to be a modifier gene in FAP patients diagnosed with APC germline mutations. © 2005 Wiley‐Liss, Inc.
p53 mutation profile of squamous cell carcinomas of the esophagus in Kashmir (India): A high‐incidence area
Authors: Mir Mohammad Muzaffar , Dar Nazir Ahmad , Gochhait Sailesh , Zargar Showkat Ali , Ahangar Abdul Gani , Bamezai R.N.K.
Published: March 2005

Esophageal squamous cell carcinoma (ESCC) has been reported to show geographical variation in its incidence, even within areas of ethnic homogeneity. Kashmir valley, in north of India, has been described as a high‐risk area for ESCC. Here, we make a preliminary attempt to study mutations in exons 5–8 (the DNA binding domain) of the tumor suppressor gene, p53, in 55 ESCC patients from Kashmir. Polymerase chain reaction followed by direct sequencing analysis revealed the presence of mutations in 36.36% (20/55) tumors, assessed for the extent of allelic instability. The 20 mutations, found in 20 patients, comprised of 17 single‐base substitutions (11 transitions + 6 transversions) and 3 deletions. The 17 single‐base variations represented 12 missense mutations, 2 nonsense mutations and 3 variations located in intron 6, 1 of which resulted in a splicing variant. The patients when compared for the incidence of p53 mutation with various demographic features revealed females to be at increased risk (p = 0.016; OR = 4.13; 95% CI = 1.26–13.46). Comparison of mutation profile with other high‐risk areas reflected both differences and similarities indicating coexposure to a unique set of risk factors. This might be due to the special dietary and cultural practices of Kashmir that needs validation, as does the gender‐based difference in the incidence of p53 mutation observed in this study. © 2005 Wiley‐Liss, Inc.
Localization and regulation of phospholipase D2 by ARF6
Authors: Hiroyama Masami , Exton John H.
Published: March 2005

Phospholipase D (PLD) and ADP‐ribosylation factor 6 (ARF6) have been implicated in vesicular trafficking and rearrangement of the actin cytoskeleton. We have explored the co‐localization of rat PLD1b and rat PLD2 with wild type and mutant forms of ARF6 in HeLa cells and studied their activation by ARF6 and the role of the actin cytoskeleton. GFP‐tagged PLD1 had a similar pattern to multivesicular and late endosomes and the trans‐Golgi apparatus, but not to other organelles. When wild type or dominant negative ARF6 and PLD1 or PLD2 were co‐expressed, they had a similar localization in cytosolic particles and at the cell periphery. In contrast, dominant active ARF6 caused cell shrinkage and had a similar localization with PLD1 and PLD2 in dense structures, containing the trans‐Golgi apparatus and actin. Disruption of the actin cytoskeleton with cytochalasin D did not induce the formation of these structures. To determine, if ARF6 selectively activated PLD1 or PLD2, wild type and mutant forms of the ARF isoform were transfected together with PLD1 or PLD2. Wild type ARF6 did not affect either PLD isozyme, but dominant active ARF6 selectively activated PLD2 and dominant negative ARF6 selectively inhibited PLD2. In contrast, dominant active ARF1 or Rac1 stimulated both PLD isozymes but the ARF1 effect on PLD2 was very small. Cytochalasin D did not affect the activation of PLD by phorbol ester. The localizations of PLD and ARF6 were also analyzed by fractionation after methyl‐β‐cyclodextrin extraction to deplete cholesterol. The results showed that all PLD isoforms and ARF6 mutants existed in the membrane fraction, but only wild type ARF6 was dependent on the presence of cholesterol. These experiments showed that wild type ARF6 had a similar location with PLD isoforms on cell staining, but it did not colocalize with PLD isoforms in fractionation experiments. It is proposed that activated ARF6 translocates to the cholesterol independent microdomain and then activates PLD2 there. It is further concluded that PLD2 is selectively activated by ARF6 in vivo and that disruption of the actin cytoskeleton does not affect this activation. © 2005 Wiley‐Liss, Inc.
Serological protein profiling of neuroblastoma by ProteinChip SELDI‐TOF technology
Authors: He Qing‐Yu , Zhu Rui , Ren Yi , Tam Paul K.H. , Chiu Jen‐Fu
Published: March 2005

Serological proteins of neuroblastoma were profiled and analyzed by ProteinChip‐SELDI‐TOF MS technology with five types of protein chips. By comparing with normal control, a number of protein or polypeptide signals were found significantly and consistently different in their intensities (expression levels) in tumor sera. Interestingly, nine polypeptide peaks in these proteomic features can be simultaneously detected with consistent variations by more than one type of protein chips. None of the expression differences of these nine polypeptides was found in similar comparisons between healthy controls and hepatomas. Preliminary protein identification showed hints for that some of these proteomic alterations may be closely related to the tumorigenesis of neuroblastoma. These results demonstrated the potential of serological biomarker identification for neuroblastoma by ProteinChip‐SELDI technology. © 2005 Wiley‐Liss, Inc.
Symmetries that latin squares inherit from 1‐factorizations
Authors: Wanless Ian M. , Ihrig Edwin C.
Published: March 2005

A 1‐factorization of a graph is a decomposition of the graph into edge disjoint perfect matchings. There is a well‐known method, which we call the 𝕂‐construction, for building a 1‐factorization ofKn,nfrom a 1‐factorization ofKn + 1. The 1‐factorization ofKn,ncan be written as a latin square of ordern. The 𝕂‐construction has been used, among other things, to make perfect 1‐factorizations, subsquare‐free latin squares, and atomic latin squares. This paper studies the relationship between the factorizations involved in the 𝕂‐construction. In particular, we show how symmetries (automorphisms) of the starting factorization are inherited as symmetries by the end product, either as automorphisms of the factorization or as autotopies of the latin square. Suppose that the 𝕂‐construction produces a latin squareLfrom a 1‐factorizationFofKn + 1. We show that the main class ofLdetermines the isomorphism class ofF, although the converse is false. We also prove a number of restrictions on the symmetries (autotopies and paratopies) whichLmay possess, many of which are simple consequences of the fact thatLmust be symmetric (in the usual matrix sense) and idempotent. In some circumstances, these restrictions are tight enough to ensure thatLhas trivial autotopy group. Finally, we give a cubic time algorithm for deciding whether a main class of latin squares contains any square derived from the 𝕂‐construction. The algorithm also detects symmetric squares and totally symmetric squares (latin squares that equal their six conjugates). © 2005 Wiley Periodicals, Inc. J Combin Designs 13: 157–172, 2005.
The use of amino acids to enhance the aerosolisation of spray‐dried powders for pulmonary gene therapy
Authors: Li H.‐Y. , Seville P. C. , Williamson I. J. , Birchall J. C.
Published: March 2005

Background

Pulmonary delivery of gene therapy offers the potential for the treatment of a range of lung conditions, including cystic fibrosis, asthma and lung cancer. Spray‐drying may be used to prepare dry powders for inhalation; however, aerosolisation of such powders is limited, resulting in poor lung deposition and biological functionality. In this study, we examine the use of amino acids (arginine, aspartic acid, threonine, phenylalanine) to enhance the aerosolisation of spray‐dried powders containing model non‐viral gene vectors.

Methods

Lipid/polycation/pDNA (LPD) vectors, in the presence or absence of amino acids, were dispersed in lactose solutions, and spray‐dried to produce appropriately sized dry powders. Scanning electron microscopy and laser diffraction were used to determine particle morphology and diameter, respectively. Gel electrophoresis was used to examine the influence of amino acids on the structural integrity of the LPD complex. In vitro cell (A549) transfection was used to determine the biological functionality of the dry powders, and the in vitro aerosolisation performance was assessed using a multistage liquid impinger (MSLI).

Results

Both gel electrophoresis and in vitro cell transfection indicated that certain amino acids (aspartic acid, threonine) can adversely affect the integrity and biological functionality of the LPD complex. All amino acids significantly increased the aerosolisation of the powder, with the arginine and phenylalanine powders showing optimal deposition in the lower stages of the MSLI.

Conclusions

Amino acids can be used to enhance the aerosolisation of spray‐dried powders for respiratory gene delivery, allowing the development of stable and viable formulations for pulmonary gene therapy. Copyright © 2004 John Wiley & Sons, Ltd.
A non‐contact low‐cost sensor for improved repeatability in co‐evaporated CIGS
Authors: Repins I. L. , Fisher D. , Batchelor W. K. , Woods L. , Beck M. E.
Published: March 2005

A low‐cost, non‐contact sensor that provides endpoint detectionfor each stage in a three‐stage CuInxGa1−xSe2(CIGS( deposition is described. CIGS and precursoremissivity data providing the fundamental basis for the sensor's operation are presented.In situoperation of the sensor is outlined and sensor‐predicted film thickness, maximum Cu ratio during growth, as well as final Cu ratio are compared with those derived by other methods. Characteristics of the sensor relevant to automated and continuous processing are discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Measurement Uncertainty in the Calibration of Low‐flow Ambient Air Samplers
Authors: Wulff Shaun S. , Weitz Mark A.
Published: March 2005

This paper considers the quality of measurement for a new standard used to assess ambient airflow measurements. The quality is quantified through the uncertainty associated in the measurements of this device. While guidelines are available for these analyses, this case study presents a set of additional challenges since the flow rate measurements are based on a linear relationship between two functions where the variables making up these functions are measured with non‐negligible error. In order to estimate the parameters describing this linear relationship, it is necessary to account for the variability associated with these errors. Measurement error modeling approaches can be used to estimate the linear regression parameters and the associated uncertainties. Ordinary least squares procedures are simpler, but must be used with care since the estimates can be biased and the resulting uncertainties can be underestimated. Once estimates for the linear relationship are obtained, measurements from the device are used to calculate a predicted flow rate. Techniques are presented for estimating the uncertainty associated with this predicted flow rate. Copyright © 2005 John Wiley & Sons, Ltd.
Transition Monitoring and Adjustment for Dynamic Systems in a Process Improvement Environment
Authors: Nembhard Harriet Black , Kao Ming Shu
Published: March 2005

In manufacturing applications, we often encounter process transitions due to a changeover in the production or perhaps an unknown perturbation. The main process improvement goal is to shorten the transition time by monitoring the process in order to quickly identify the start and end of the transition period and by actively adjusting the process during the transition. To address these issues, we propose a transition monitoring and adjustment methodology. A polymer process is used to illustrate this methodology. Using simulation, we characterize the impact of the transition adjustment on the effectiveness of monitoring. We show that the adaptive monitoring procedure is robust to small transition adjustments, thus supporting a complimentary application of process monitoring and process adjustment to improve process transitions. Copyright © 2005 John Wiley & Sons, Ltd.
A General Framework for Constructing Control Charts
Authors: Polansky Alan M.
Published: March 2005

A general framework for the construction of control charts is presented. The method is based on using the density of the sample subgroup statistic as a measure of how unusual newly observed subgroups are. This methodology includes, as special cases, many common control chart techniques. The method is also easily applied to multivariate and multimodal situations. A non‐parametric control chart is implemented by estimating the density of the sample subgroup statistic using a kernel estimator of the bootstrap distribution of the observed subgroup statistics. Several examples of the method are presented in the parametric and non‐parametric situations. The potential performance of the non‐parametric version of the method is demonstrated through an empirical study of average run length properties. Copyright © 2005 John Wiley & Sons, Ltd.
Generating random elements of abelian groups
Authors: Lukács András
Published: March 2005

Algorithms based on rapidly mixing Markov chains are discussed to produce nearly uniformly distributed random elements in abelian groups of finite order. Let A be an abelian group generated by set S. Then one can generate ϵ‐nearly uniform random elements of A using 4|S|log(|A|/ϵ) log(|A|) additions and the same number of random bits. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2005
An assessment of seismic design practice of steel structures in the United States since the Northridge earthquake
Authors: Sabol Thomas A.
Published: March 2005

The 1994 Northridge earthquake served as a watershed event in the practice of seismic design of structural steel buildings. Damage to steel moment frame and concentrically braced buildings in this earthquake as well as similar types of damage observed in the 1995 Hyogoken‐Nambu earthquake illustrated the need to address design, construction, and quality shortcomings in design standards, methods of construction, and inspection practices. Research demonstrated that moment frame performance could be improved by shifting the location of the plastic hinge from the face of the column, use of higher notch‐tough welding electrodes, rigorous attention to proper fabrication and erection practices, and improved inspection practices emphasizing visual inspection. Changes to braced frame design provisions have emphasized development of full member strength in the connections, which has led to development of buckling restrained systems to better match tensile and compression brace capacities. This paper assesses the impact of post‐earthquake observations and some of the research initiatives that have changed the way in which structural steel seismic systems are designed. It attempts to identify the trends relative to selection of various steel seismic systems in response to perceived performance issues, limitations imposed by design standards and regulatory agencies, and economic factors. Copyright © 2004 John Wiley & Sons, Ltd.
Wind and bathymetric forcing of the annual sea surface temperature signal in the East (Japan) Sea
Authors: Park Kyung‐Ae , Chung Jong Yul , Kim Kuh , Cornillon Peter C.
Published: March 2005

The relationship between the annual cycle of sea surface temperature (SST) in the East (Japan) Sea and wind forcing and bathymetry is examined using AVHRR‐derived SST fields and satellite‐derived scatterometer wind fields. On the basin scale, SST north of the Subpolar Front (SPF) is characterized by relatively larger amplitude (≥10°C) and variance (≥94%) and earlier phase than water to the south. Furthermore, north of the SPF, earlier SST cooling coincides with regions of high winds. On a much smaller spatial scale, the data show earlier SST cooling over the Siberian seamount is a result of the relatively shallow water over the seamount coupled with the complete erosion of the seasonal thermocline in mid February.
Molecular phylogenetics of babblers (Timaliidae): revaluation of the generaYuhinaandStachyris
Authors: Cibois Alice , Kalyakin Mikhail V. , Lian‐Xian Han , Pasquet Eric
Published: March 2005

The babblers (Timaliidae) form a large songbird family, which achieves its highest diversity in South‐East Asia. As part of an ongoing phylogenetic investigation of this group, we focus here on the systematic position of two Asian genera,YuhinaandStachyris, using cytochromeb, 16S and 12S sequence data. The analysis suggests that the two genera, as defined by morphological characters, are not monophyletic. The white‐bellied yuhinaYuhina zantholeuca, which has been placed among the typical yuhinas by most authors, is not a babbler. The other yuhinas studied, six continental species and a species endemic to Taiwan, form a clade that includes also three species ofStachyrisendemic to the Philippines. The otherStachyrisare not related to this clade, and can be divided into two groups that correspond to morphological and geographical differences among the species.
Variable energetic responses to clutch size manipulations in white‐throated dippers Cinclus cinclus
Authors: Engstrand Susan M. , Ward Sally , Bryant David M.
Published: March 2005

We used the doubly‐labelled water technique to measure daily energy expenditure (DEE) of a free‐living uniparental incubator, the white‐throated dipper Cinclus cinclus, in Scotland. DEE was 205±8 (s.e.m.) kJ d−1 for 17 females incubating their natural clutch sizes, equivalent to 3.2±0.1×basal metabolic rate (BMR). To investigate the influence of clutch size on the energy budget, we measured the DEE of 14 females with clutches increased or reduced by a single egg. Birds with reduced clutch sizes had an energy expenditure with a mean and variance that did not differ from those of birds with unmanipulated clutches. Enlarging the clutch led to an increase in energy expenditure to over 4×BMR for some individuals but not for others, resulting in greater variance in energy expenditure for birds with enlarged clutches. Individual variation in energy expenditure could not be fully explained by environmental conditions, by patterns of behaviour or clutch size.

 Incubating females received a maximum of only 4 kJ d−1 (2% of DEE) from provisioning by the male, and mobilised up to 6 kJ d−1 (3% of DEE) from reserves. Females spent 2.9±0.2 h (n=20) away from the nest each day, so a foraging rate of 95 kJ h−1 was required during incubation recesses to balance DEE. This ‘required foraging rate’ is double previous estimates of the maximum rates of energy acquisition for birds of this size. We suggest that the greater likelihood of a raised energy expenditure associated with larger clutches, combined with the difficulties in maintaining energy supplies, may constitute a constraint on avian clutch size.
Microsatellite typing of sperm trapped in the perivitelline layers of avian eggs: a cautionary note
Authors: Martínez Juan G. , Burke Terry
Published: March 2005

Recently Carter et al. (2000) have shown that it is possible to amplify microsatellite markers from the DNA of spermatozoa trapped in the perivitelline layers of avian eggs. This makes it possible to establish whether sperm reaches the ovum and to identify the males that contribute sperm competing to fertilise an egg. In this article we quantify the genotyping error rate associated with the biased amplification of differently sized alleles. We conclude that multiple marker loci should be used and that those markers where the competing males' alleles differ by more than ten base pairs should be avoided.
A few more hypotheses for the evolution of dioecy in figs (Ficus, Moraceae)
Authors: Harrison Rhett D. , Yamamura Norio
Published: March 2005

In figs (Ficus, Moraceae) there are two breeding systems: monoecy is the ancestral condition but approximately half the 750 odd species are functionally dioecious. Three hypotheses have been proposed for the evolution of dioecy in figs, invoking seasonality (Kjellberg et al. 1987), the reduction of non‐pollinating wasp species (Kerdelhue and Rasplus 1996), and the persistence of pollinator populations within small groups of trees (Kameyama et al. 1999). However, there are two major problems with these ideas. Firstly, dioecy has probably evolved only twice (Weiblen 2000), which severely limits our ability to test between alternative hypotheses. Secondly, it is very simple to suggest ways in which dioecy can evolve from monoecy (Charnov 1982). To illustrate this problem, and enlarge on some recent progress in our understanding of functionally dioecious figs, we are proposing a few more hypotheses.
Experimental small‐scale grassland fragmentation alters aphid population dynamics
Authors: Braschler Brigitte , Lampel Gerolf , Baur Bruno
Published: March 2005

Theory predicts that at higher trophic levels species are especially vulnerable to habitat fragmentation due to small population size and dependence on particular prey species. Using aphids as model organism, we tested the hypothesis that herbivore abundance increases in fragmented habitats as a result of reduced predator and parasitoid densities. In a 3 year‐study, we examined the population dynamics of aphids with respect to host plant abundance and ant nest density in experimentally fragmented calcareous grasslands at two sites in the northern Jura mountains. Fragments of different size (area: 20.25 m2, 2.25 m2 and 0.25 m2) were isolated by a 5 m wide strip of frequently mown vegetation and corresponding control plots were situated in the adjacent undisturbed grassland. Aphid density was higher in fragments than in control plots. This was a combined result of a higher frequency of aphid‐infested plants and larger aphid colonies in fragments than in control plots. Furthermore, a larger proportion of aphid colonies was ant‐attended in fragments than in control plots. Aphid colonies were also more frequently visited by ants in fragments than in control plots in one of the 3 years. Parasitoid pressure on aphids was not influenced by the experimental fragmentation. Neither were aphid species richness and diversity affected by the fragmentation. Our study shows that even small‐scale habitat fragmentation can have profound effects on the abundance of herbivorous insects. The effect on aphid density was consistent over 3 years and two sites with slightly different aphid communities.
The cost of polyphagy: oviposition decision time vs error rate in a butterfly
Authors: Janz Niklas
Published: March 2005

Neural constraints on information processing have emerged as a possible general explanation for why a majority of plant‐feeding insects are relative specialists. According to the hypothesis, acquiring and processing information necessary to make fast and accurate oviposition decisions will carry a cost. As plants constitute a vast but diverse resource, the cost can be expected to increase with increasing host range. The cost can be paid in two currencies: time or accuracy. Both types of costs have been demonstrated, using a variety of taxa including butterflies. However, all studies have measured either one of the two currencies. Hence, there is the possibility that a decrease in one of the currencies can be compensated by an increase in the other, in which case the net outcome may not be a cost at all. Poor oviposition decisions could then be counterbalanced by shorter decision times, which could lead to higher realized fecundity. Using two strains of butterflies (Polygonia c‐album) with different degrees of specificity, I test the hypothesis that the previously reported higher error rates in the more polyphagous butterflies are compensated by shorter decision times at oviposition. Post‐alighting decision times were measured while the females evaluated a preferred plant (Urtica dioica) for oviposition. Contrary to the expectations, the polyphagous butterflies actually had longer decision times than the specialized butterflies, giving no support for the quality vs. quantity hypothesis. Instead, the results suggests that the polyphagous butterflies do pay a real cost for their wide host range and thus gives increased support for the information processing hypothesis as a general explanation for the widespread host specificity among plant‐feeding insects.
Adsorption controls mobilization of colloids and leaching of dissolved phosphorus
Authors: Siemens J. , Ilg K. , Lang F. , Kaupenjohann M.
Published: March 2005

Loss of phosphorus (P) from agriculture contributes to the eutrophication of surface waters. We have assessed the magnitude and controls of P leaching and the risk of colloid‐facilitated transport of P from sandy soils in Münster. Concentrations of soluble reactive P in drainage water and groundwater were monitored from 0.9 to 35 m depth. Total P concentrations, P saturation, and P sorption isotherms of soil samples were determined. Concentrations of dispersible soil P and colloidal P in drainage water and groundwater were investigated. The concentrations of soluble reactive P in drainage water and groundwater were close to background concentrations (< 20 µg P l−1). Median concentrations in excess of 100 µg P l−1 were found down to 5.6 m depth at one of four research sites and in the lower part of the aquifer. Experimentally determined equilibrium concentrations and the degree of P saturation were good predictors of P concentrations of drainage water. Large concentrations of dispersible P were released from soil with large concentrations of oxalate‐extractable P and addition of P induced further dispersion. Colloidal P was transported in a P‐rich subsoil when there was a large flow of water and after nitrate had been flushed from the soil profile and total solute concentrations were small. We conclude that the concentration of soluble reactive P in drainage water is controlled by rapid adsorption in the sandy soils. Subsurface transport of dissolved P contributes substantially to the loss of P from the soils we investigated. Accumulation of P in soils increases the risk of colloid‐facilitated leaching of P.
Surveillance biopsies are superior to functional studies for the diagnosis of acute and chronic renal allograft pathology in children
Authors: Birk Patricia E. , Stannard Karen M. , Konrad Helen B. , Blydt‐Hansen Tom D. , Ogborn Malcolm R. , Cheang Mary S. , Gartner John G. , Gibson Ian W.
Published: March 2005

Abstract:  In this report of our 3‐yr protocol biopsy program, we describe the evolution of acute rejection (AR) and chronic renal allograft nephropathy (CAN) in a cohort of 21 children treated with antibody induction, tacrolimus, mycophenolate mofetil, and prednisone. The aims of this study were to compare the pathogenicity of clinical acute rejection (CAR) and subclinical acute rejection (SAR), and to determine whether functional studies accurately represent acute and chronic renal allograft pathology in pediatric recipients with disproportionately large grafts. Using concurrent biopsies, we evaluated: (i) the utility of changes in the baseline sCr (ΔsCr) to predict both the onset of AR and the response to immunosuppressive therapy; and (ii) the relationship of the calculated creatinine clearance and the presence of pathologic proteinuria to the severity of CAN. We performed 112 biopsies: 11 donor, 73 protocol, 16 acute graft dysfunction and 12 1‐month follow‐up AR therapy. CAR and SAR were similar in incidence, timing and histologic severity. Progression of CAN was associated with the first episode of CAR (p < 0.02) and the cumulative number of episodes of CAR (p < 0.01), SAR (p < 0.05), CAR plus SAR (p < 0.002) and borderline SAR (B‐SAR) (p < 0.006). One‐month post‐treatment ΔsCrs could not distinguish 1‐month follow‐up biopsies with histologically confirmed worsened or unchanged AR from those with improved histology (35.2 ± 74.8% vs. 23.8 ± 24.9%, p = NS). These findings led to the addition of anti‐lymphocyte antibody therapy in five of 10 (50%) cases. Despite 100% 3‐yr actuarial graft survival and excellent function (GFR = 111 ± 36 mL/min/1.73 m2), 18 of 21 (86%) patients had grade I CAN or greater chronic histology at a mean ± sd follow‐up period of 18.2 ± 13.1 months. Thirteen of 21 (62%) patients progressed to grade I CAN at 5.2 ± 3.6 months and five (38%) of these patients progressed to grade II CAN at 17.8 ± 11.3 months. Schwartz GFR did not differ between patients with or without CAN (108 ± 38 mL/min/1.73 m2 vs. 127 ± 8 mL/min/1.73 m2, p = NS). In biopsies with CAN and no associated AR, neither the Banff chronic tubulointerstitial (Banff ci) score nor the Banff chronic grade correlated with the GFR. Proteinuria was not associated with CAN. Clinical AR and SAR are similar histologic lesions with a capacity for CAN progression. In pediatric renal transplant recipients, longitudinal protocol biopsies are superior to functional studies for the diagnosis and post‐therapeutic monitoring of AR and for the surveillance of CAN.
Theoretical and experimental investigation of the second hyperpolarizabilities of methyl orange
Authors: Del Nero J. , de Araujo R. E. , Gomes A. S. L. , de Melo C. P.
Published: March 2005

We describe experimental and theoretical studies of the third-order nonlinear optical coefficients of methyl orange solutions under different pH conditions. A combination of semiempirical and ab initio methods was adopted to investigate the most stable geometrical structures possible for this molecule. The experimental data obtained using the Z-scan technique for the third-order nonlinear optical properties of this compound has allowed the determination of the nonlinear refractive index and nonlinear absorption coefficient under picosecond excitation in the visible (532 nm) spectral region. From those experimental results, the second hyperpolarizability of methyl orange was inferred both for acidic and alkaline solutions. Comparison of these values to the results predicted by semiempirical methods suggests that even at low pH, when the probability of cis-trans isomerization is increased, the trans conformation of the methyl orange molecule should dominate the nonlinear spectra of this compound. The theoretical results were used as an auxiliary tool to identify possible trends on the nonlinear properties changes as a function of the distinct molecular conformations adopted by the methyl orange molecule under different pH conditions.
Laser-induced refractive index gratings formed in Pr3+-doped sodium-magnesium-aluminosilicate glasses
Authors: Hamad Abdulatif Y. , Wicksted James P.
Published: March 2005

We report a systematic study of grating formation in which the Pr2O3 concentration [Pr2O3] in sodium-magnesium-aluminosilicate glasses is varied from 0.5to5mol%. The grating kinetics is reported as functions of the [Pr2O3] and the write-beam irradiance. The maximum persistent change in the index of refraction was 1×10−5. The persistent change in the index of refraction initially decreased linearly as a function of the [Pr2O3] and showed a limiting behavior at the highest [Pr2O3]. No appreciable transient change in the index of refraction, Δntran, was measured. This was attributed to the low probability of the multiphonon relaxation of the P03 level of the Pr3+ ions as determined through fluorescence measurements. The results of this study are consistent with a recently developed small modifier diffusion model.
Fabrication and near-infrared photothermal conversion characteristics of Au nanoshells
Authors: Liu Zhongxin , Song Hongwei , Yu Lixin , Yang Linmei
Published: March 2005

In this letter, gold nanoshells with a size of ∼20nm were prepared by a wet-chemical synthesis method and the surface plasmon absorption band of gold was tuned from visible to near-infrared. The gold nanoshell hydrosol demonstrated excellent photothermal conversion property. The temperature of the hydrosol was increased to as high as 30°C under exposure of an 808nm coherent diode laser with a powder density of 5W∕cm2. This kind of gold nanoshell hydrosol is promising for use in biomedicine through photothermal conversion.
Surfactant-mediated epitaxy of Ge on Si(111): Beyond the surface
Authors: Schmidt Th. , Kröger R. , Clausen T. , Falta J. , Janzen A. , Kammler M. , Kury P. , Zahl P. , Horn-von Hoegen M.
Published: March 2005

For a characterization of interface and “bulk” properties of Ge films grown on Si(111) by Sb surfactant-mediated epitaxy, grazing incidence x-ray diffraction and transmission electron microscopy have been used. The interface roughness, defect structure, and strain state have been investigated in dependence of film thickness and growth temperature. For all growth parameters, atomically smooth interfaces are observed. For thin Ge layers, about 75% of the strain induced by the lattice mismatch is relaxed by misfit dislocations at the Ge∕Si interface. Only a slight increase of the degree of relaxation is found for thicker films. At growth temperatures below about 600°C, the formation of twins is observed, which can be avoided at higher temperatures.
Capacitance-spectroscopy identification of a key defect in N-degraded GalnNAs solar cells
Authors: Kurtz Sarah , Johnston Steve , Branz Howard M.
Published: March 2005

We report a study comparing the device performance and the deep-level transient spectroscopy spectra of Ga1−yInyNxAs1−x diodes. It is found that a transient capacitance signal, which corresponds to a trap 0.18 to 0.25 eV below the conduction-band edge, is observed near 140 K in the nitrogen-containing samples. The existence of this transient correlates with higher dark current [lower open-circuit voltage (Voc)] and the size of the transient increases with x for x⩽0.6%. The abrupt decrease of the Voc with the addition of nitrogen is explained by the hypothesis that a close approach of the electron quasi-Fermi level to the conduction-band edge is arrested by the electron trap. The N-induced trap level reduces Voc as if it were a new conduction-band edge.
Two-dimensional exciton behavior in GaN nanocolumns grown by molecular-beam epitaxy
Authors: Na Jong H. , Taylor Robert A. , Rice James H. , Robinson James W. , Lee Kwan H. , Park Young S. , Park Chang M. , Kang Tae W.
Published: March 2005

We have investigated the behavior of excitons in GaN nanocolumns using time-integrated and time-resolved micro-photoluminescence measurements. In the weak confinement limit, the model of fractional-dimensional space gives an intermediate dimensionality of 2.14 for GaN nanocolumns, with an average diameter of 80nm. Enhanced exciton and donor binding energies are deduced from a fractional-dimensional model and a phenomenological description. Time-integrated photoluminescence spectra as a function of temperature show a curved emission shift. Recombination dynamics are deduced from the temperature dependence of the PL efficiency and decay times.
Hypoxia abolishes transience of the heat-shock response in the methylotrophic yeast Hansenula polymorpha
Authors: Guerra Emanuela , Chye Poh Poh , Berardi Enrico , Piper Peter W.
Published: March 2005

The heat-shock response is conserved amongst practically all organisms. Almost invariably, the massive heat-shock protein (Hsp) synthesis that it induces is subsequently down-regulated, making this a transient, not a sustained, stress response. This study investigated whether the heat-shock response displays any unusual features in the methylotrophic yeast Hansenula polymorpha, since this organism exhibits the highest growth temperature (49–50 °C) identified to date for any yeast and grows at 47 °C without either thermal death or detriment to final biomass yield. Maximal levels of Hsp induction were observed with a temperature upshift of H. polymorpha from 30 °C to 47–49 °C. This heat shock induces a prolonged growth arrest, heat-shock protein synthesis being down-regulated long before growth resumes at such high temperatures. A 30 °C to 49 °C heat shock also induced thermotolerance, although H. polymorpha cells in balanced growth at 49 °C were intrinsically thermotolerant. Unexpectedly, the normal transience of the H. polymorpha heat-shock response was suppressed completely by imposing the additional stress of hypoxia at the time of the 30 °C to 49 °C temperature upshift. Hypoxia abolishing the transience of the heat-shock response appears to operate at the level of Hsp gene transcription, since the heat-induced Hsp70 mRNA was transiently induced in a heat-shocked normoxic culture but displayed sustained induction in a culture deprived of oxygen at the time of temperature upshift.
Novel stationary-phase-upregulated protein of Porphyromonas gingivalis influences production of superoxide dismutase, thiol peroxidase and thioredoxin
Authors: Kikuchi Yuichiro , Ohara Naoya , Sato Keiko , Yoshimura Mamiko , Yukitake Hideharu , Sakai Eiko , Shoji Mikio , Naito Mariko , Nakayama Koji
Published: March 2005

Porphyromonas gingivalis, an obligately anaerobic bacterium, is implicated as a major pathogen in the development and progression of chronic periodontitis. Although expression of several virulence factors of the bacterium has been found to be affected by environmental stress such as entrance into the stationary growth phase and heat, there is relatively little information on the mechanisms that may operate in the bacterium in response to environmental stress. In this study, a novel protein (UstA) was investigated that was initially identified following two-dimensional gel analysis. Expression of UstA was upregulated in stationary phase or by exposure to atmospheric oxygen. N-terminal sequencing and database analysis with theP. gingivalisgenome sequence revealed that the UstA-encoding gene (ustA) was located upstream of a homologue of theuspgene encoding the universal stress protein on the chromosome. TheustAgene appeared to be transcribed in a monocistronic fashion, as revealed by primer extension and Northern blot analysis. To elucidate the role of UstA in the bacterium, chromosomal mutants carrying a disruption of theustAgene were constructed. TheustAmutant grew slower than the wild-type parent strain in rich medium, resulting in a lower yield in stationary phase. Furthermore, in this mutant, expression levels of theP. gingivalishomologues of superoxide dismutase, thiol peroxidase and thioredoxin were markedly higher than those in the wild-type, especially in stationary phase. TheustAmutant was more resistant to diamide, a thiol-specific oxidant, than the wild-type. In addition, theustAmutation suppressed hypersensitivities of theoxyRmutant to diamide, metronidazole and mitomycin C. These results suggest that UstA may play a significant role in oxidative stress responses in the bacterium.
Mutants of Mycobacterium smegmatis unable to grow at acidic pH in the presence of the protonophore carbonyl cyanide m-chlorophenylhydrazone
Authors: Tran Sieu L. , Rao Min , Simmers Cameron , Gebhard Susanne , Olsson Karen , Cook Gregory M.
Published: March 2005

Mycobacterium smegmatis is able to grow and survive at acidic pH, and exhibits intracellular pH homeostasis under these conditions. In this study, the authors have identified low proton permeability of the cytoplasmic membrane, and high cytoplasmic buffering capacity, as determinants of intrinsic acid resistance of M. smegmatis. To identify genes encoding proteins involved in protecting cells from acid stress, a screening method was developed using the electrogenic protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP). CCCP was used to suppress intrinsic acid resistance of M. smegmatis. The screen involved exposing cells to pH 5·0 in the presence of CCCP, and survivors were rescued at various time intervals on solid medium at pH 7·5. Cells capable of responding to intracellular acidification (due to CCCP-induced proton equilibration) will survive longer under these conditions than acid-sensitive cells. From a total pool of 5000 transposon (Tn611) insertion mutants screened, eight acid-sensitive M. smegmatis mutants were isolated. These acid-sensitive mutants were unable to grow at pH 5·0 in the presence of 1–5 μM CCCP, a concentration not lethal to the wild-type strain mc2155. The DNA flanking the site of Tn611 was identified using marker rescue in Escherichia coli, and DNA sequencing to identify the disrupted locus. Acid-sensitive mutants of M. smegmatis were disrupted in genes involved in phosphonate/phosphite assimilation, methionine biosynthesis, the PPE multigene family, xenobiotic-response regulation and lipid biosynthesis. Several of the acid-sensitive mutants were also defective in stationary-phase survival, suggesting that overlapping stress protection systems exist in M. smegmatis.
The structure of secondary cell wall polymers: how Gram-positive bacteria stick their cell walls together
Authors: Schäffer Christina , Messner Paul
Published: March 2005

The cell wall of Gram-positive bacteria has been a subject of detailed chemical study over the past five decades. Outside the cytoplasmic membrane of these organisms the fundamental polymer is peptidoglycan (PG), which is responsible for the maintenance of cell shape and osmotic stability. In addition, typical essential cell wall polymers such as teichoic or teichuronic acids are linked to some of the peptidoglycan chains. In this review these compounds are considered as ‘classical’ cell wall polymers. In the course of recent investigations of bacterial cell surface layers (S-layers) a different class of ‘non-classical’ secondary cell wall polymers (SCWPs) has been identified, which is involved in anchoring of S-layers to the bacterial cell surface. Comparative analyses have shown considerable differences in chemical composition, overall structure and charge behaviour of these SCWPs. This review discusses the progress that has been made in understanding the structural principles of SCWPs, which may have useful applications in S-layer-based ‘supramolecular construction kits' in nanobiotechnology.