bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanochitosan crosslinked with polyacrylamide as the chiral stationary phase for open‐tubular capillary electrochromatography
Authors: Chen Jian‐Lian , Hsieh Kai‐Hsin
Published: January 2011

Nanoparticles exhibiting favorable surface‐to‐volume ratios create efficient stationary phases for electrochromatography. New nanomaterials derived from chitosan (CS) were immobilized onto modified capillaries for use as the chiral stationary phase (CSP) in open‐tubular electrochromatography. This immobilization was achieved through the copolymerization of glycidyl methacrylate‐modified nano‐CS with methacrylamide (MAA) and bis‐acrylamide crosslinkers (forming the MAA‐CS capillary) rather than the attachment of nano‐CS to the copolymer of glycidyl methacrylate, MAA, and bis‐acrylamide (forming the MAA+CS capillary). The completed MAA‐CS capillary and its precursors were examined by SEM and ATR‐IR measurements. Before separating chiral samples, the MAA‐CS capillary was characterized by electroosmotic flow measurements at varying pH values, concentrations, and volume percentages of organic modifiers in the running buffers. Tryptophan enantiomers were well separated by the MAA‐CS capillary, whereas no enantioselectivity was observed in the MAA+CS capillary. With the addition of 80% MeOH into the phosphate buffer, the chiral separation of (±)‐catechin was accomplished in a normal‐phase mode. However, the new CSP has its limitations, as only two groups of α‐tocopherol stereoisomers were separated.
Metabolomic profiling of human plasma in pancreatic cancer using pressurized capillary electrochromatography
Authors: Zhang Huiping , Wang Yan , Gu Xue , Zhou Junyi , Yan Chao
Published: January 2011

The application of pressurized capillary electrochromatography (pCEC) coupled with ultra violet (UV) detection has been investigated for the production of global metabolite profiles from human plasma, and its capabilities of classifying pancreatic cancer patients. The pCEC separation of plasma samples was performed on a RP column with gradient elution. The applied voltage, detection wavelength and type of acid modifiers on separation of plasma samples were optimized with pooled quality control (QC) sample. The stability and the repeatability of the methodology were also determined by the repeat analysis of QC sample. The effects of different scaling methods on the results of orthogonal partial least‐squares discrimination analysis (OPLS‐DA) based on pCEC‐UV data set were also investigated. The results of the current study clearly showed the different phenotypes of metabolites of pancreatic cancer patients and healthy controls based on pCEC‐UV plasma profiles. OPLS‐DA data are shown to provide a valuable means of convenient classification. This work indicated that pCEC‐UV method can be used as a cost‐effective and information‐rich, while relatively simple and inexpensive approach for plasma profiling on disease metabolomics studies.
Application of the iPLEXTM Gold SNP genotyping method for the analysis of Amerindian ancient DNA samples: Benefits for ancient population studies
Authors: Mendisco Fanny , Keyser Christine , Hollard Clémence , Seldes Veronica , Nielsen Axel E. , Crubézy Eric , Ludes Bertrand
Published: January 2011

Important developments in the matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) technique have generated new perspectives regarding SNP genotyping, which are particularly promising for ancient population‐based studies. The main aim of the present study was to investigate the application of a MALDI‐TOF MS‐based SNP genotyping technique, called iPLEX® Gold, to analyze Amerindian ancient DNA samples. The first objective was to test the sensitivity of the method, which is recommended for DNA quantities between 10 and 5 ng, for ancient biological samples containing DNA molecules that were degraded and present in minute quantities. The second objective was to detail the advantages of this technique for studies on ancient populations. Two multiplexes were designed, allowing the major Amerindian mitochondrial and Y haplogroups to be determined simultaneously. This analysis has never been described before. Results demonstrated the reliability and accuracy of the method; data were obtained for both mitochondrial and nuclear DNA using picogram (pg) quantities of nucleic acid. This technique has the advantages of both MS and minisequencing techniques; thus, it should be included in the protocols for future ancient DNA studies.
Multi‐objective PSO/GA optimization control strategies for energy efficient PMDC motor drives
Authors: Sharaf Adel M. , El‐Gammal Adel A. A.
Published: January 2011

The paper presents the application of genetic algorithm (GA) and particle swarm optimization (PSO) search and optimization techniques for online tuning of error‐driven self‐adjusting multi‐loop dynamic speed regulators for large industrial permanent magnet DC (PMDC) motor drives. Novel three multi‐loop dynamic error regulator include tan‐sigmoid controller, multi‐zone controller, and incremental self‐regulating controllers are developed by First Author and validate by Second Author. The proposed dynamic multi‐loop control strategies are based on time‐discalced and decoupled regulation loops with assigned loop weightings and dynamic loop delays. The three novel dynamic and efficient control schemes utilize speed, current, dynamic momentum excursion error, and limited current ripple errors as the main inputs to vary the firing delay angleαof the six‐pulse controlled Thyristor rectifier. Multi‐objective GA (MOGA) and multi‐objective PSO (MOPSO) are used for selection of the proposed controller's gains to ensure high performance efficient PMDC motor drives and effective robust dynamic tracking of different speed reference trajectories. The optimization process is based on minimizing the system control total error, the steady state error, settling time, rising time, and maximum overshoot. Copyright © 2011 John Wiley & Sons, Ltd.
Fructose, uricase, and the Back‐to‐Africa hypothesis
Authors: Johnson Richard J. , Andrews Peter
Published: January 2011

In the Middle Miocene (approximately 17 to 12 Ma) at least two radiations of fossil apes from East Africa into Eurasia occurred, and, while controversial, some paleoanthropological studies suggest that one of the Eurasian lineages may have returned to Africa to evolve into humans and the African apes. Here, we present a novel argument supporting this hypothesis. Specifically, the global cooling that occurred in the middle Miocene rendered hominoids living in Europe at risk for starvation as seasonal climate change resulted in less availability of fruits during the winter months. During this time, a mutation in uricase occurred in early hominids that resulted in a rise in serum uric acid. Uric acid has been found to potentiate the effect of fructose to increase fat stores, suggesting that the mutation provided a survival advantage. Such a survival advantage would have been less likely to occur in Africa, where the continued presence of tropical rainforests would have been more likely to provide food throughout the year. Furthermore, Miocene apes in Europe were in protected sites where geographic isolation could have allowed the uricase mutation to be rapidly expressed in the entire population. While speculative, we suggest that the uricase mutation supports an extra‐Africa origin of humans.
Why were the first anthropologists creationists?
Authors: Marks Jonathan
Published: January 2011

Anthropologists in every generation have been tarred as creationists by radical Darwinians. In only the very first generation of scholarly anthropology, however, does the charge really stick; that is, in the founding tradition of liberal German humanistic anthropology from about 1860–1890. This paper explores the ideas that may have motivated their rejection of evolution.
Phenotypic traits of primate hybrids: Recognizing admixture in the fossil record
Authors: Ackermann Rebecca Rogers
Published: January 2011

For many years, the likelihood that hybridization occurred in human evolution has been debated. Tattersall and Schwartz pointed out one of the core problems with resolving this debate, namely “that nobody has any idea what a Neanderthal/modern human hybrid might look like in theory, and few have dared to suggest in practice that any particular known fossil represents such a hybrid.”1:7117 Moreover, while molecular data is proving increasingly useful for characterising hybrid zones, the utility of the phenotype for this purpose is not clear.2 Here I address these issues, discussing both theoretical and empirically‐derived expectations for what hybrid morphology looks like, with an emphasis on the skeleton of hybrid primates, and consideration of the hominin fossil record.
Regulation of hepatic fat and glucose oxidation in rats with lipid-induced hepatic insulin resistance
Authors: Alves Tiago C. , Befroy Douglas E. , Kibbey Richard G. , Kahn Mario , Codella Roberto , Carvalho Rui A. , Falk Petersen Kitt , Shulman Gerald I.
Published: January 2011

Pyruvate dehydrogenase plays a critical role in the regulation of hepatic glucose and fatty acid oxidation; however, surprisingly little is known about its regulationin vivo. In this study we examined the individual effects of insulin and substrate availability on the regulation of pyruvate dehydrogenase flux (VPDH) to tricarboxylic acid flux (VTCA) in livers of awake rats with lipid-induced hepatic insulin resistance. VPDH/VTCA flux was estimated from the [4-13C]glutamate/[3-13C]alanine enrichments in liver extracts and assessed under conditions of fasting and during a hyperinsulinemic-euglycemic clamp, whereas the effects of increased plasma glucose concentration on VPDH/VTCA flux was assessed during a hyperglycemic clamp in conjunction with infusions of somatostatin and insulin to maintain basal concentrations of insulin. The effects of increases in both glucose and insulin on VPDH/VTCA were examined during a hyperinsulinemic-hyperglycemic clamp. The effects of chronic lipid-induced hepatic insulin resistance on this flux were also examined by performing these measurements in rats fed a high-fat diet for 3 weeks. Using this approach we found that fasting VPDH/VTCA was reduced by 95% in rats with hepatic insulin resistance (from 17.2 ± 1.5% to 1.3 ± 0.7%,P< 0.00001). Surprisingly, neither hyperinsulinemiaper seor hyperglycemiaper sewere sufficient to increase VPDH/VTCA flux. Only under conditions of combined hyperglycemia and hyperinsulinemia did VPDH/VTCA flux increase (44.6 ± 3.2%,P< 0.0001 versus basal) in low-fat fed animals but not in rats with chronic lipid-induced hepatic insulin resistance.Conclusion:These studies demonstrate that the combination of both hyperinsulinemia and hyperglycemia are required to increase VPDH/VTCA fluxin vivoand that this flux is severely diminished in rats with chronic lipid-induced hepatic insulin resistance. (HEPATOLOGY 2011.)
Genotype differences in susceptibility and resistance development of hepatitis C virus to protease inhibitors telaprevir (VX-950) and danoprevir (ITMN-191)
Authors: Imhof Ingrid , Simmonds Peter
Published: January 2011

Protease inhibitors (PIs) have proven to be effective adjuncts to interferon/ribavirin treatment of hepatitis C virus (HCV) infections. Little clinical or

in vitro

data exists, however, on their effectiveness for nontype 1 genotypes that predominate in Europe, the Middle East, Africa, and most of Asia. NS3 protease and NS4A genes from genotypes 1-6 were inserted into the JFH clone to generate replication-competent intergenotype chimeras. Susceptibility to PIs was determined by replication and infectivity assays. To study resistance development, chimeras were cultured in subinhibitory concentrations of PIs and mutations phenotypically characterized. Marked differences in susceptibility of different genotypes to danoprevir (ITMN-191) and telaprevir (VX-950) were observed. Genotypes 1, 4, and 6 showed median inhibitory concentration (IC50) values of 2-3 nM, >100-fold lower than genotypes 2/3/5 (250-750 nM). Telaprevir susceptibilities varied over a 4-fold range, with genotypes 1 and 2 being most susceptible and genotypes 4 and 5 most resistant. Culture of genotypes 1-6 in PIs induced numerous mutations in the NS3 protease domain, highly variable between genotypes. Introduction of danoprevir and BILN 2061-induced mutations into the original clones by site-directed mutagenesis (n = 29) all conferred resistant phenotypes, with particularly large increases (1-2 log greater IC50 values) in the initially susceptible genotypes 1/4/6. Most introduced mutations and showed little or no effect on replicative fitness.

Conclusion:

Major differences were found between genotypes in their susceptibility and resistance development to PIs. However, equal sensitivities of genotypes 1, 4, and 6 to danoprevir and a broader efficacy range of telaprevir between genotypes than initially conceptualized provide strong evidence that PIs might be effectively used beyond their genotype 1 target group. (HEPATOLOGY 2011;)
Characterisation of a landslide fissure pattern by integrating seismic azimuth tomography and geotechnical testing
Authors: Grandjean G. , Bitri A. , Krzeminska D. M.
Published: January 2011

In order to characterise the fissure field provoked by the Super‐Sauze mudslide (South French Alps) in the surface material, we conducted a seismic survey and compared the resultingP‐wave tomogram to surface observations and cone penetrometer tests. The first results show that the distribution of theP‐wave velocities correlates well with the fissure parameters, i.e. density, depth, and thickness, estimated from digital photographs and field observations. In addition, one finds good agreement between theP‐wave velocity distribution and the material resistances interpolated from the penetrometer tests, indicating a probable physical relationship. The results of our study demonstrate that seismic azimuth tomography is efficient for characterising fissure systems with the main advantage of the method lying in the integration capacity of wave propagation compared to local mechanical tests. Provided that the correlation betweenP‐wave velocity and fissure characteristics are confirmed at other sites, this technique could be the basis for future and more systematic studies of high‐hazard zones related to landslides. Copyright © 2011 John Wiley & Sons, Ltd.
Slope‐stability‐constrained design of irrigation canals using particle swarm optimization
Authors: REDDY M. JANGA , ADARSH S.
Published: January 2011

This paper presents a practical methodology for optimal design of open channels considering the slope‐stability aspects and other requirements and propounds the solution of particle swarm optimization (PSO) for solving nonlinear optimization problems. The proposed methodology handles site‐specific conditions such as restrictions on allowable top width and water depths. To ensure the stability of canals under field conditions a slope‐stability constraint is incorporated into the channel design. This constraint is handled through an optimization sub‐routine for computing stability of the canals using PSO. The results of the model show that for all the cases considered in the study the PSO‐based solutions are found to perform well and in some cases better than the traditional solutions. The PSO method provides lot of flexibility in its usage for solving complex channel design problems and it can be used to handle various system requirements in a better way. Copyright © 2011 John Wiley & Sons Ltd.
Exposure of larvae to daily thermocycles affects gonad development, sex ratio, and sexual steroids in Solea senegalensis, kaup
Authors: Blanco‐Vives Borja , Vera Luisa María , Ramos Jesús , Bayarri María José , Mañanós Evaristo , Sánchez‐Vázquez Francisco Javier
Published: January 2011

The effect of water temperature during the development of fish larvae on sex differentiation is well known, but not so well known is the impact of the daily thermocycles. Our aim was to investigate the effect of early exposure of Senegal sole larvae to different temperature cycles on gonad development, sex ratio, and sex steroid (11‐ketotestosterone (11‐KT); estradiol (E2); and testosterone, (T)) content in muscle extracts of juveniles. From 1 to 97 days posthatching (DPH) fish larvae and post‐larvae were subjected to three temperature regimes: Thermophase‐Cryophase (TC), Cryophase‐Thermophase (CT), and constant temperature. In fish exposed to TC, sex determination occurred earlier, because 90% of soles were males/females at 110 DPH, whereas 45% of fish under CT were undifferentiated at that time. Fish under TC showed the highest growth rates, followed by fish under constant temperature and by fish under CT, the differences being statistically significant between the TC and CT groups. Regarding sex ratio, juveniles exposed to TC showed a higher proportion of females than fish under CT or constant temperature. Under TC, fish showed the highest concentration of E2, whereas 11‐KT concentration was highest in fish under CT and constant temperature. Fish under constant temperature and CT showed higher T levels than those under TC. These results provide the first insights into the effect of daily thermocycles on sex differentiation in fish, and underline the key role of natural environmental cycles on the control of sex ratios during larval development, which may be applied to the manipulation of sex ratio in aquaculture. J. Exp. Zool. 315:162–169, 2011. © 2011 Wiley‐Liss, Inc.
Detection of low plasma estradiol concentrations in nesting green turtles (Chelonia mydas) by HPLC/Ms‐Ms
Authors: Mahmoud I.Y. , AlKindi A.Y. , Khan T. , Al‐Bahry S.N.
Published: January 2011

In previous studies on nesting green turtles under natural conditions from different geographical regions, 17‐β‐estradiol (E2) was either undetectable or detected at very low levels. RIA and other related techniques were not sensitive enough to measure low E2 values in the green turtles. In this study, a sensitive method was used in detecting low hormone concentrations: high performance liquid chromatography with tandem quadruple mass spectrometry (HPLC‐MS/MS). Using this technique, estradiol for the first time was detected in nesting green turtles during the peak season (June–October) at Ras Al‐Hadd Reserve, Oman. The E2 values recorded from this study were the highest ever recorded from nesting green turtles in any geographical region, but the levels did not vary significantly throughout different phases of nesting. The presence of E2 during nesting presumably plays a role in the physiology and behavior of this species. Ras Al‐Hadd hosts one of the largest nesting populations of green turtles in the world, and an understanding of their nesting patterns may be of value in conservation and management programs for this endangered species. J. Exp. Zool. 315:170–174, 2011. © 2011 Wiley‐Liss, Inc.
Why ontogenetic homology criteria can be misleading: lessons from digit identity transformations
Authors: Young Rebecca L. , Wagner Günter P.
Published: January 2011

As the basis for comparative biology, correctly assigning character homology is critical. Yet, identifying homologous characters in practice is often challenging. Among the major roadblocks is that the mechanistic bases of character homology remain in question. Thus, investigators must rely on several independent lines of evidence (e.g., character anatomy, phylogenetic distribution, or embryological position); however, these distinct sources of evidence often lead to conflicting diagnoses of character homology. What is more, there is no consensus regarding the relative importance of distinct lines of evidence for determining character homology. Here, we review the difficulties that have hindered the search for the mechanistic bases of character identity, and relate these issues to a recently proposed mechanistic hypothesis of character identity—the Character Identity Network Hypothesis. Next, using two well‐studied cases of homology conflict (i.e., avian and skink digit identity), we assess the utility of different lines of evidence in diagnosing homology. We conclude that, when comparing adult structures, because anatomical characters more closely reflect the actions of the developmental genetic mechanisms of character individuation they are more reliable than embryological homology criteria. J. Exp. Zool. (Mol. Dev. Evol.) 316:165–170, 2011. © 2011 Wiley‐Liss, Inc.
Fire and drought as drivers of early Holocene tree line changes in the Peruvian Andes
Authors: Urrego Dunia H. , Niccum Brittany A. , La Drew Christopher F. , Silman Miles R. , Bush Mark B.
Published: January 2011

Three pollen and charcoal records from three lakes lying at 3400 m elevation in southern Peru provided a record of landscape change spanning the last ca.18 000 cal. a BP. The tree line lay close to the site between ca. 16 000 and 12 000 cal. a BP, with Polylepis woodlands growing near the lakes. Progressively drying conditions led to increased fire after 12 000 cal. a BP, coinciding with a decline in Polylepis cover and Andean forest relicts as puna grasslands expanded. A strong decrease in the rate of sediment deposition between ca. 12 000 and ca. 4400 cal. a BP was interpreted to indicate the presence of sedimentary hiatuses. With the return of wet conditions after 4400 cal. a BP, forests did not reassemble around the lakes. Instead, fire‐maintained grasslands dominated the landscape. Humans probably induced the intensified fire activity during the late Holocene and thereby deflected local successions. The modern fragmented landscape, with Polylepsis woodlands existing in fire‐resistant pockets above the general limit of the Andean tree line, resulted from the intensification of human land use practices during the last 4400 cal. a BP. Copyright © 2011 John Wiley & Sons, Ltd.
Cumulative probability functions and their role in evaluating the chronology of geomorphological events during the Holocene
Authors: Chiverrell Richard C. , Thorndycraft Varyl R. , Hoffmann Thomas O.
Published: January 2011

Cumulative probability functions (CPFs) for large numbers of radiocarbon age determinations are increasingly being used by scientists as a methodology to discern environmental histories. While the recent compilation of regional databases of the radiocarbon dating control for fluvial sediment sequences has been beneficial for identifying gaps in knowledge and stimulating new research, there are a number of problems that critically undermine the use of these CPFs as sensitive hydroclimatic proxies. (i) The CPF method is underpinned by the assumption that each radiocarbon measurement is a true age estimate for a point in time, whereas each measured age in fact forms a scatter around the true age of the sample; (ii) calibration of radiocarbon ages is responsible for much of the structure in CPFs and compounds the problem of scatter and smears the chronological control; (iii) the databases incorporate multiple types of environmental changes differing chronological relationships between the 14C measurements and the dated events, with pre‐dating, dating or post‐dating chronological control each displaying variable length temporal lags all mixed together in the same analysis; and (iv) the radiocarbon ages from individual case studies need to be more robustly tested before being incorporated into regional databases. All these factors negate the value of CPFs as sensitive proxies of environmental change, because peaks in probability for individual radiocarbon measurements are likely to be an incorrect estimate for the age of a geomorphological event and this problem is compounded by combining probabilities for multiple unrelated events. In this paper we present a critical analysis of CPFs and their interpretation before suggesting alternative approaches to analysing radiocarbon geochronologies of geomorphic events, which include: (i) Bayesian age modelling of river terrace development; (ii) developing regional databases that test specific geomorphic hypotheses; (iii) Bayesian age modelling of palaeoflood records; and (iv) analysis of sedimentation rates. Copyright © 2011 John Wiley & Sons, Ltd.
Wet aggregate stability as affected by excess carbonate and other soil properties
Authors: Dimoyiannis D.
Published: January 2011

Aggregate stability is a fundamental property influencing soil erodibility and hydraulic characteristics. Knowledge of soil components controlling aggregate stability is very important to soil structure conservation. The objective of this study, which was carried out in surface soils from central Greece, was to relate wet aggregate stability to selected soil properties, with emphasis on excessive free carbonate content. The wet‐sieving technique of air‐dried aggregates was used for structural stability evaluation, according to a test that calculates an instability index. The soils studied were developed on Tertiary marly parent material and ranged in calcium carbonate content from 5 to 641 g kg−1. From the texture analysis before and after removal of carbonates, it was concluded that carbonates mainly contributed to total silt and sand fractions, that is to the mechanical fractions which, as a rule, negatively affect aggregate stability. The results of the correlation analysis showed that aggregate stability was positively affected by aluminosilicate clay content, cation exchange capacity (CEC) and Al‐containing sesquioxides. Clay fraction from carbonates and total sand and silt negatively affected aggregate stability. CEC has been proved a very significant determinant of aggregate stability, which in a hyperbolic form relationship with instability index explained 78·9 per cent of aggregate stability variation. Copyright © 2011 John Wiley & Sons, Ltd.
IMPACT OF DECENTRALIZATION REFORMS IN PAKISTAN ON SERVICE DELIVERY—AN EMPIRICAL STUDY
Authors: Aslam Ghazia , Yilmaz Serdar
Published: January 2011

By bringing decision making closer to people, decentralization is expected to improve governance and service delivery outcomes. Yet, the empirical evidence on the impact of decentralization on macroeconomic performance and public sector size presents a mixed picture. However, the findings of cross‐country studies in the literature are sensitive to the way decentralization is defined, and how its extent and impact are measured. This article avoids the unwanted effects of incomparability and aggregation in cross‐country analysis. We use a unique panel data set from 183 villages in Pakistan to analyze the impact of decentralization reforms implemented in 2001 on the provision of services—street paving, construction of water canals, sanitation sewer lines, and school facilities. Our results show that the magnitude of provision of all services increased significantly following decentralization reforms. We further show that the four services are impacted differently and service delivery improvement is not uniform, but not in ways that conform to the hypotheses of patronage theory. Copyright © 2011 John Wiley & Sons, Ltd.
Determination of 17q gain in patients with neuroblastoma by analysis of circulating DNA
Authors: Combaret Valérie , Bréjon Stéphanie , Iacono Isabelle , Schleiermacher Gudrun , Pierron Gäelle , Ribeiro Agnès , Bergeron Christophe , Marabelle Aurélien , Puisieux Alain
Published: January 2011

Background

Retrospective studies have demonstrated the prognostic impact of genomic profiles in neuroblastoma (NB). Segmental chromosome alterations have been found useful for identifying tumors with a high risk of relapse. As the gain of chromosome arm 17q is the most frequent chromosome alteration reported in NB primary tumors, we evaluated the presence of this 17q gain in the peripheral blood of patients with NB.

Procedure

Using duplex quantitative real‐time PCR, we quantified simultaneously MPO (17q.23.1) and a reference gene, p53, and Survivin (17q25) and p53. MPO and Survivin copy numbers were evaluated as MPO/p53 and Survivin/p53 ratios in 142 serum or plasma samples in which 17q status had been determined by array‐based comparative genomic hybridization (aCGH) or multiplex ligation‐dependent probe amplification (MLPA).

Results

In patients <18 months of age, serum‐based determination of 17q gain in DNA sequences had good specificity (94.4%) and 58.8% sensitivity (P < 0.001). In contrast, for patients over 18 months of age, the approach exhibited moderate specificity (71.4%) and 51.2% sensitivity (P = ns). Similar results were observed in patients with tumors without MYCN amplification.

Conclusion

Our results show that 17q gain determination in circulating DNA is possible and suggest that this non‐invasive test could be useful for very young children when no reliable information on genomic alterations is obtained by aCGH or MPLA analysis of tumor samples This test is complementary to previously developed techniques for detecting circulating MYCN DNA sequences. Pediatr Blood Cancer 2011;56:757–761. © 2011 Wiley‐Liss, Inc.
Analysis of tensile test results for poly(acrylonitrile‐butadiene‐styrene) based on Weibull distribution
Authors: Jar P.‐Y. Ben , Xu Jie
Published: January 2011

Statistical analysis based on two‐parameter Weibull distribution was applied to poly(acrylonitrile‐butadiene‐styrene) to characterize involvement of two damage types in tensile test specimens, which appear as tiny strips and uniform whitening, respectively. Analysis using Weibull distribution suggests that the probability density functions (PDF) for extension at break and total energy consumption (named toughness) give distinctively different characteristics between the two damage types. PDF curve for the tiny strips consists of a sharp peak, whereas that for the uniform whitening a broad hump. Using two‐group mixed Weibull distribution, effect of pre‐existing damage on the fracture process was examined. The PDF curves show that presence of one damage type (e.g., uniform whitening) tends to suppress generation of the other damage type (e.g., tiny strips) even in a test condition that would have favored the latter in virgin specimens. Involvement of the two damage types was quantified using portion for each subpopulation from the Weibull distribution analysis. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Uniform shell patterning using rubber‐assisted hot embossing process. I. Experimental
Authors: Nagarajan Pratapkumar , Yao Donggang
Published: January 2011

In rubber‐assisted hot embossing, a softened thin thermoplastic film is pressurized between a hard mold surface and a rubber pad. The rubber pad, as a soft counter‐tool, deforms conformably to the hard mold surface, allowing feature transfer from the hard surface and formation of shell‐type structures on the polymer film. This two‐article sequence was aimed to understand the basic mechanisms affecting the pattern uniformity and replication in rubber‐assisted hot embossing. In Part I, a series of rubber‐assisted embossing experiments involving parametric studies of the effects of different processing conditions, as well as material selections, on the pattern thickness uniformity and replicated pattern height were conducted. The difference in film thickness uniformity in different experiments was explained using the mechanical and rheological behavior of the polymer film and the rubber counter‐tool under different processing conditions. Based on the experimental results, strategies for determining a feasible process window for achieving uniform shell patterning by rubber‐assisted embossing were proposed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
A surface model‐based simulation for warpage of injection‐molded parts
Authors: Zhou Huamin , Wang Zhiyong , Li Jianhui , Li Dequn
Published: January 2011

The mid‐plane model for warpage simulation of injection‐molded parts requires a mid‐plane mesh whose transformation is considerably time consuming. To overcome this drawback, a surface model‐based warpage simulation is presented, in which the part is represented as a perfect bonding of two half‐thickness plates with their reference surfaces at the outer boundary of the part. The plates over the surface mesh are modeled as flat shell elements, and a new triangular flat shell element is developed which combines an Assumed Natural DEviatoric Strain (ANDES) based membrane component and a Refined Nonconforming Element Method (RNEM) based bending component. The bonding is accomplished by multipoint constraints and a Lagrange multiplier based elimination method is proposed for constraint application. The results show that compared with some popular shell elements, ANSYS, Moldflow and the experiments, the presented model exhibits a high performance in computation accuracy. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Dielectric constant and loss investigations of pristine, iodine‐doped and annealed polyetherimide film
Authors: Quamara Jitendra K , Singh Randhir , Kaushik Balbhadra K
Published: January 2011

Temperature‐ and frequency‐dependent dielectric behaviour has been investigated for pristine, iodine‐doped and annealed polyetherimide (PEI) in the temperature range 303–523 K at various frequencies (120 Hz, 1 kHz, 10 kHz and 100 kHz). In pristine PEI, the rapid decrease in the dielectric constant (ε′) in the temperature range 303–373 K is governed by the Kirkwood model whereas the gradual decrease in ε′ in the temperature range 373–473 K is governed by β‐relaxation (dipolar) and αβ‐relaxation (hybrid) processes. The occurrence of these relaxations is confirmed by the appearance of tan δ loss peaks at ca 403 and 443 K, respectively, in ε″–T curves. The temperature‐independence of ε′ in the temperature range 473–523 K is mainly governed by the α‐relaxation process associated with large segmental groups. The tan δ loss peak appearing at 503 K confirms this relaxation process. In iodine‐doped samples, an overall increase in ε′ is attributed to the formation of charge‐transfer complexes in the polymer structure. The dominance of a new relaxation process due to interaction of iodine with ether linkages neutralizes the 1/T rule in the low‐temperature region. A significant decrease in ε′ in annealed samples below 393 K is due to the suppression of the dipolar relaxation process. The enhancement in ε′ above 393 K is due to the dominance of the α‐relaxation process. The shift in the high‐temperature tan δ loss peak towards higher temperature with increasing frequency shows the distributive nature of relaxation time for this relaxation process. Copyright © 2011 Society of Chemical Industry
Suspension polymerization of aniline hydrochloride in non‐aqueous media
Authors: Konyushenko Elena N , Stejskal Jaroslav , Trchová Miroslava , Prokeš Jan
Published: January 2011

The oxidation of aniline hydrochloride by ammonium peroxydisulfate in non‐aqueous media was studied, when the monomer or oxidant or both were not completely soluble. Polyaniline was formed in acetone, methanol and toluene. Aniline oligomers only were produced in chloroform and n‐butylacetate. No interaction of the monomer and the oxidant was observed in dimethylsulfoxide and N‐methylpyrrolidone. UV‐visible and Fourier transform infrared spectra were recorded in order to study the molecular structure of the final products. Conductivity was measured for conducting protonated forms and corresponding bases. An explanation of aniline hydrochloride oxidation in various organic media is offered. Copyright © 2011 Society of Chemical Industry
Remote substituent effects on homolytic FeC bond energies of p‐G‐C6H4CH2Fe(CO)2(η5‐C5H5) and p‐G‐C6H4(H)(CN)CFe(CO)2(η5‐C5H5) studied by Hartree–Fock and density functional theory methods
Authors: Zeng Qing , Li Zucheng
Published: January 2011

In general, both stoichiometric and catalytic reactions of organometallic complexes involve breaking and forming metal–ligand bonds. Therefore, an evaluation of the thermodynamics of such reactions requires the knowledge of metal–ligand bond energies (BDEs). The homolytic FeC bond dissociation energies [i.e., ΔHhomo(FeC)s] of 12 para‐substituted benzyldicarbonyl(η5‐cyclopentadienyl)iron, p‐G‐C6H4CH2Fp [1,G = NO2, CN, COMe, CO2Me, CF3, Br, Cl, F, H, Me, MeO, NMe2; Fp = (η5‐C5H5)(CO)2Fe] and 12 para‐substituted α‐cyanobenzyldicarbonyl (η5‐cyclopentadienyl)iron, p‐G‐PANFp [2,PAN = C6H4CH(CN)] were studied using Hartree–Fock (HF) and density functional theory (DFT) methods with large basis sets. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of ΔHhomo(FeC)s. The B3LYP method satisfactorily predicts the α and remote substituent effects on ΔHhomo(FeC)s [ΔΔHhomo(FeC)s]. The fair correlations [r = 0.97 (g, 1), 0.99(g, 2)] of ΔΔHhomo(FeC)s of series 1 and 2 with the substituent σ constants imply that the para substituent effects on ΔHhomo(FeC)s originate mainly from polar effects, but those on radical stability originate from both spin delocalization and polar effects. The molecule stabilization effects (MEs) causes that not only the magnitude of ΔΔHhomo(FeC)s(1) varies significantly but also the direction changes from S‐pattern to O‐pattern. ΔΔHhomo(FeC)s(2) were found to conform to the Capto‐dative Principle. The detailed knowledge of the factors that determine the FpC bond strengths would greatly aid in understanding reactivity patterns in many processes. Copyright © 2010 John Wiley & Sons, Ltd.
Efficient synthesis of well‐defined amphiphilic cylindrical brushes polymer with high grafting density: Interfacial “Click” chemistry approach
Authors: Sun Jianping , Hu Jiwen , Liu Guojun , Xiao Dingshu , He Guping , Lu Rufeng
Published: January 2011

Reported here is a novel approach toward efficient preparation of well‐defined cylindrical brushes polymer (CBPs) with both hydrophobic and hydrophilic side chains connected to the linear backbone by interfacial “click” chemistry in two immiscible solvents. The CBPs with high grafting density of more than 95% and molecular polydispersity (Mw/Mn) less than 1.12 can be readily synthesized using present approach. On contrary, the CBPs synthesized from the “click” reaction in a single solvent in homogenous state have low grafting density of less than 55% and molecular polydispersity (Mw/Mn) more than 1.78. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Discordant and chameleon sequences: Their distribution and implications for amyloidogenicity
Authors: Gendoo Deena M.A. , Harrison Paul M.
Published: January 2011

Identification of ambiguous encoding in protein secondary structure is paramount to develop an understanding of key protein segments underlying amyloid diseases. We investigate two types of structurally ambivalent peptides, which were hypothesized in the literature as indicators of amyloidogenic proteins: discordant α‐helices and chameleon sequences. Chameleon sequences are peptides discovered experimentally in different secondary‐structure types. Discordant α‐helices are α‐helical stretches with strong β‐strand propensity or prediction. To assess the distribution of these features in known protein structures, and their potential role in amyloidogenesis, we analyzed the occurrence of discordant α‐helices and chameleon sequences in nonredundant sets of protein domains (n= 4263) and amyloidogenic proteins extracted from the literature (n= 77). Discordant α‐helices were identified if discordance was observed between known secondary structures and secondary‐structure predictions from the GOR‐IV and PSIPRED algorithms. Chameleon sequences were extracted by searching for identical sequence words in α‐helices and β‐strands. We defined frustrated chameleons and very frustrated chameleons based on varying degrees of total β propensity ≥α propensity. To our knowledge, this is the first study to discern statistical relationships between discordance, chameleons, and amyloidogenicity. We observed varying enrichment levels for some categories of discordant and chameleon sequences in amyloidogenic sequences. Chameleon sequences are also significantly enriched in proteins that have discordant helices, indicating a clear link between both phenomena. We identified the first set of discordant‐chameleonic protein segments we predict may be involved in amyloidosis. We present a detailed analysis of discordant and chameleons segments in the family of one of the amyloidogenic proteins, the Prion Protein.
On the computation of non‐perturbative effective potentials in the string theory landscape – IIB/F‐theory perspective –
Authors: Cvetič M. , García‐Etxebarria I. , Halverson J.
Published: January 2011

We discuss a number of issues arising when computing non‐perturbative effects systematically across the string theory landscape. In particular, we cast the study of fairly generic physical properties into the language of computability/number theory and show that this amounts to solving systems of diophantine equations. In analogy to the negative solution to Hilbert's 10th problem, we argue that in such systematic studies there may be no algorithm by which one can determine all physical effects. We take large volume type IIB compactifications as an example, with the physical property of interest being the low‐energy non‐perturbative F‐terms of a generic compactification. A similar analysis is expected to hold for other kinds of string vacua, and we discuss in particular the extension of our ideas to F‐theory. While these results imply that it may not be possible to systematically answer certain physical questions about generic type IIB compactifications, we identify particular Calabi‐Yau manifolds in which the diophantine equations become linear, and thus can be systematically solved. As part of the study of the required systematics of F‐terms, we develop technology for computing ℤ2 equivariant line bundle cohomology on toric varieties, which determines the presence of particular instanton zero modes via the Koszul complex. This is of general interest for realistic IIB model building on complete intersections in toric ambient spaces.
Development and characterisation of transgenic rice expressing two Bacillus thuringiensis genes
Authors: Yang Zhou , Chen Hao , Tang Wei , Hua Hongxia , Lin Yongjun
Published: January 2011

BACKGROUND: Transgenic crops that produce insecticidal toxins from the bacterium Bacillus thuringiensis Berliner (Bt) were first commercialised in 1996. The risk that pests have the potential to evolve resistance to Bt toxins is one of the most serious challenges to this technology. Gene stacking, pyramiding two Bt genes into one variety, is considered to be an effective insect resistance management (IRM) strategy. In this study, insect‐resistant rice expressing two Bt genes was developed by sexual crossing, and then characterised.

RESULTS: Homozygous rice lines of two pyramided Bt genes were obtained in the F3 generation. Quantification of Bt toxin showed that protein concentrations of Cry1Ab, Cry1Ac and Cry2A in the two‐gene lines were comparable with their single‐gene parents, while the expression of cry1C gene decreased after gene stacking. Four two‐gene lines showed higher activity to striped stem borer (Chilo suppressalis Walker) than parental lines in the laboratory bioassay. All pyramided lines and their hybrids exhibited excellent efficacy against stemborers and leaffolders in field evaluation, while most pyramided lines had no significant differences from original variety in yield under spraying of insecticide.

CONCLUSION: These results demonstrate that the two‐gene lines have commercial potential and could serve as a valuable IRM strategy. Copyright © 2011 Society of Chemical Industry
Display female‐specific doublesex RNA interference in early generations of transformed oriental fruit fly, Bactrocera dorsalis (Hendel)
Authors: Chen Shiu‐Ling , Lu Kuang‐Hui , Dai Shu‐Mei , Li Chia‐Hsin , Shieh Chwen‐Jen , Chang Cheng
Published: January 2011

BACKGROUND: The oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most destructive pests in many Asian countries. An effective strategy to reduce fly density in the field is urgently required. Recently, the doublesex of B. dorsalis (Bddsxf) has been cloned, and RNA interference (RNAi) indicates that it can reduce the offspring in vitro. In this study, a piggyBac‐based construct that generates short hairpin RNA (shRNA) against the female‐specific region of Bddsx was introduced into the pest to test the RNAi effects on reproductive functions in vivo.

RESULTS: After embryonic injection and backcross, 21 transgenic lines with germline transformation were identified. Genomic DNA analysis showed that the exogenous transgene including short hairpin Bddsxf and a DsRed marker had integrated into the genomes of 11 transformed lines. Northern blot analysis indicated the presence of Bddsxf short interfering RNA (siRNA) under the control of a U6 promoter in transformed flies. As expected, the specific effects of RNAi led to the delay of egg maturation, and the offspring was significantly reduced. Reverse transcription real‐time PCR further demonstrated that in vivo interference not only specifically inhibited the Bddsxf transcript but also repressed expression of the downstream yolk protein gene (Bdyp1).

CONCLUSION: The results clearly indicate that RNAi is heritable through the expression of specific siRNA in early generations of transformed oriental fruit fly. These results can broaden the understanding of sex‐related developmental mechanisms in the fly, and also offer a possible molecular approach for pest control in the future. Copyright © 2011 Society of Chemical Industry
Lethal and sublethal side‐effect assessment supports a more benign profile of spinetoram compared with spinosad in the bumblebee Bombus terrestris
Authors: Besard Linde , Mommaerts Veerle , Abdu‐Alla Gamal , Smagghe Guy
Published: January 2011

BACKGROUND: This study was undertaken to identify the potential side effects of the novel naturalyte insecticide spinetoram in comparison with spinosad on the bumblebee Bombus terrestris L. The potential lethal effects together with the ecologically relevant sublethal effects on aspects of bumblebee reproduction and foraging behaviour were evaluated. Bumblebee workers were exposed via direct contact with wet and dry residues under laboratory conditions to spinetoram at different concentrations, starting from the maximum field recommended concentration (MFRC) and then different dilutions (1/10, 1/100, 1/1000 and 1/10 000 of the MFRC), and compared with spinosad. In addition, the side effects via oral exposure in supplemented sugar water were assessed.

RESULTS: Direct contact of B. terrestris workers with wet residues of spinosad and spinetoram showed spinetoram to be approximately 52 times less toxic than spinosad, while exposure to dry residues of spinetoram was about 8 times less toxic than exposure to those of spinosad. Oral treatment for 72 h (acute) indicated that spinetoram is about 4 times less toxic to B. terrestris workers compared with spinosad, while exposure for a longer period (i.e. 11 weeks) showed spinetoram to be 24 times less toxic. In addition, oral exposure to the two spinosyns resulted in detrimental sublethal effects on bumblebee reproduction. The no observed effect concentration (NOEC) for spinosad was 1/1000 of the MFRC, and 1/100 of the MFRC for spinetoram. Comparison between the chronic exposure bioassays assessing the sublethal effects on nest reproduction, with and without allowing for foraging behaviour, showed that the respective NOEC values for spinosad and spinetoram were similar over the two bioassays, indicating that there were no adverse effects by either spinosyn on the foraging of B. terrestris workers.

CONCLUSION: Overall, the present results indicate that the use of spinetoram is safer for bumblebees by direct contact and oral exposure than the use of spinosad, and therefore it can be applied safely in combination with B. terrestris. Another important conclusion is that the present data provide strong evidence that neither spinosyn has a negative effect on the foraging behaviour of these beneficial insects. However, before drawing final conclusions, spinetoram and spinosad should also be evaluated in more realistic field‐related situations for the assessment of potentially deleterious effects on foraging behaviour with the use of queenright colonies of B. terrestris. Copyright © 2011 Society of Chemical Industry