bluuebunny/crossref_metadata_2025 huggingface dataset:
Heparan sulfate proteoglycan specificity during axon pathway formation in the Drosophila embryo
Authors: Smart Ashley D. , Course Meredith M. , Rawson Joel , Selleck Scott , Van Vactor David , Johnson Karl G.
Published: April 2011

Axon guidance is influenced by the presence of heparan sulfate (HS) proteoglycans (HSPGs) on the surface of axons and growth cones (Hu, [2001]: Nat Neurosci 4:695–701; Irie et al. [2002]: Development 129:61–70; Inatani et al. [2003]: Science 302:1044–1046; Johnson et al. [2004]: Curr Biol 14:499–504; Steigemann et al. [2004]: Curr Biol 14:225–230). Multiple HSPGs, including Syndecans, Glypicans and Perlecans, carry the same carbohydrate polymer backbones, raising the question of how these molecules display functional specificity during nervous system development. Here we use the Drosophila central nervous system (CNS) as a model to compare the impact of eliminating Syndecan (Sdc) and/or the Glypican Dally‐like (Dlp). We show that Dlp and Sdc share a role in promoting accurate patterns of axon fasciculation in the lateral longitudinal neuropil; however, unlike mutations in sdc, which disrupt the ability of the secreted repellent Slit to prevent inappropriate passage of axons across the midline, mutations in dlp show neither midline defects nor genetic interactions with Slit and its Roundabout (Robo) receptors at the midline. Dlp mutants do show genetic interactions with Slit and Robo in lateral fascicle formation. In addition, simultaneous loss of Dlp and Sdc demonstrates an important role for Dlp in midline repulsion, reminiscent of the functional overlap between Robo receptors. A comparison of HSPG distribution reveals a pattern that leaves midline proximal axons with relatively little Dlp. Finally, the loss of Dlp alters Slit distribution distal but not proximal to the midline, suggesting that distinct yet overlapping pattern of HSPG expression provides a spatial system that regulates axon guidance decisions. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 71: 608–618, 2011
Bergman Cyclization of Fluorinated Benzo‐Fused Enediynes to Naphthalene Derivatives: Syntheses and Structures
Authors: Kane Christopher M. , Meyers Tiffany B. , Yu Xin , Gerken Michael , Etzkorn Markus
Published: April 2011

Fluorinated naphthalene derivatives were prepared by Bergman cyclization of fluorinated benzo‐fused enediynes. This route provides access to the aromatic target compounds in a two‐step procedure from commercially available precursors, via a Sonogashira cross‐coupling and a subsequent, thermally initiated Bergman cyclization. Crystal structures of six fluorinated benzo‐enediynes and three fluorinated naphthalene derivatives display significant diversity in their molecular structures and in the crystal packing arrangements. The rather subtle structural change from di‐ to tetrafluorobenzo‐enediynes, as well as the variation in the terminal acetylene subunit led to different non‐covalent interactions in the solid state that ultimately govern their crystal structures.
N‐Arylcarbonylpseudoprolines as Tunable Chiral Derivatizing Agents for the Determination of the Absolute Configuration of Secondary Alcohols
Authors: Han So‐Yeong , Choi Kihang
Published: April 2011

New chiral derivatizing agents, 3‐arylcarbonyl‐2,2‐dimethyloxazolidine‐4‐carboxylic acids (N‐arylcarbonylpseudoprolines), were prepared through a simple, short‐step synthesis. The absolute configuration of secondary alcohols can be assigned on the basis of the NMR spectroscopic chemical shift difference between diastereomeric pseudoproline esters. Preparation of more efficient agents was achieved simply by using aromatic groups with stronger anisotropic effect.
The xylA promoter of Bacillus megaterium mediates constitutive gene expression in Escherichia coli
Authors: Knobloch Denise , Clemens Andre , Ostermann Kai , Rödel Gerhard
Published: April 2011

In the present study, we demonstrate that the Escherichia coli–Bacillus megaterium shuttle vector pHIS1522 can be used as a versatile expression vector. Recombinant genes under the control of the xylA promoter are constitutively expressed at a high level in E. coli strains, whereas their expression is strongly induced by the addition of xylose in B. megaterium. The utilization of D‐xylose is known to be dependent on the xylAB genes in a number of bacteria. For B. megaterium a XylA‐based expression system was established that allows tightly regulated and highly efficient heterologous gene expression. The open reading frame (ORF) of the fluorescent protein turboRFP was cloned under the control of the xylA promoter of B. megaterium in the shuttle vector pHIS1522. Unexpectedly, tRFP expression was not only observed in B. megaterium, but also in E. coli. Based on fluorescence measurements and Western blot analysis, expression was comparable or slightly higher compared with the commonly used pET vectors. Therefore, pHIS1522 can be used as a versatile expression vector in both, B. megaterium and E. coli.
A causal modelling approach to spatial and temporal confounding in environmental impact studies
Authors: Paul Warren L
Published: April 2011

Deciding whether an anthropogenic disturbance has caused a change in an ecosystem is problematic because of spatial and temporal confounding. The generally accepted approach to this problem has been to use a before‐after control‐impact (BACI) type of design. However, advances in graph theory and causal modelling now provide a formal basis for selecting the covariates that need to be observed in order to control confounding bias, and the solution provided by these advances is simpler than that provided by any of the BACI‐type designs including BACI itself as well as BACIP, Beyond‐BACI and MBACI designs. Based on an explicit description of the nature of spatial and temporal confounding in causal models for two hypothetical environmental impact studies, it is argued that confounding can be controlled by adjusting directly for spatial or temporal location in a before‐after (BA) or control‐impact (CI) study. It is further argued that there is no advantage in combining these designs in a BACI‐type study, either from a causal modelling perspective or from the perspective of the assumptions implicit in BACI‐type designs. Copyright © 2011 John Wiley & Sons, Ltd.
Regression estimator under inverse sampling to estimate arsenic contamination
Authors: Moradi Mohammad , Salehi Mohammad , Brown Jennifer Ann , Karimi Naser
Published: April 2011

The fate of arsenic introduced to the environment as a result of the natural and human activities is an important issue. Surveys of arsenic typically involve sampling from a large area. Measuring arsenic concentrations in samples is expensive, and any improvement in the survey design is welcome. One way to improve efficiency in sampling is to make use of auxiliary information. Surveys of environmental pollution can be classed as surveys of rare populations, where there is a large area with a small polluted subarea. The rare population has many zeroes, or low, values, and contaminated subareas have non‐zero, or high, values. Regression estimators or ratio estimators are undefined for those samples containing only information from the non‐rare (zero‐value) subpopulation (i.e., the non‐contaminated subpopulation) in simple random sampling. In this paper, we introduce the modified regression estimators and their associated variance estimators for sampling designs which are suitable for rare populations, such as general inverse sampling and inverse sampling with unequal selection probabilities. We conducted a simulation study on the real rare population arsenic contamination in Kurdistan. The simulation results showed that the modified regression estimators are more efficient than the previous estimators. Copyright © 2011 John Wiley & Sons, Ltd.
Expression analysis of genes located in the minimally deleted regions of 13q14 and 11q22‐23 in chronic lymphocytic leukemia—unexpected expression pattern of the RHO GTPase activator ARHGAP20
Authors: Herold Tobias , Jurinovic Vindi , Mulaw Medhanie , Seiler Till , Dufour Annika , Schneider Stephanie , Kakadia Purvi M. , Feuring‐Buske Michaela , Braess Jan , Spiekermann Karsten , Mansmann Ulrich , Hiddemann Wolfgang , Buske Christian , Bohlander Stefan K.
Published: April 2011

In chronic lymphocytic leukemia (CLL), 13q14 and 11q22‐23 deletions are found in 2/3 of the cases. 11q22‐23 deletions are associated with poor survival, whereas 13q14 deletions as single abnormality are often found in indolent disease forms. The molecular basis for this difference in prognosis is not known. We examined the 13q14 and 11q22‐23 minimally deleted regions (MDRs) for differentially expressed genes by analyzing 154 microarray CLL gene expression data sets. We were able to generate a detailed gene expression map of the MDRs demonstrating a gene dosage effect. Surprisingly, ARHGAP20 encoding the RHO GTPase activating protein 20, which is located in the 11q22‐23 MDR, showed—counterintuitively—a significantly higher expression in cases with 11q22‐23 deletions compared with cases with no detectable genetic lesion or trisomy 12. Interestingly, cases with 13q14 deletions also had higher ARHGAP20 expression. These expression level changes were confirmed by quantitative PCR in 110 additional CLL samples. The ARHGAP20 gene encodes an evolutionarily conserved protein. In the zebra fish (Danio rerio) genome the syntenic regions of human chromosomal bands 13q14 and 11q22‐23 are juxtaposed. The similar expression profiles of ARHGAP20 in 13q14 and 11q22‐23 deleted CLL cases suggest a molecular connection and an intriguing mechanism of regulation. © 2011 Wiley‐Liss, Inc.
Delays of supraglacial runoff from differently defined microbasin areas on the Peyto Glacier
Authors: Scott Munro D.
Published: April 2011

Microbasin runoff experiments were conducted on ice surfaces of the Peyto Glacier during the 1971 and 2008 ablation seasons, when half‐hourly measurements of net radiation, wind speed, temperature, vapour pressure, and supraglacial runoff were obtained on warm sunny days with daily mean temperatures 6·1–10·1 °C and daily total ablation amounts of 43–95 mm. Net radiation contributed almost 70% of the melt energy in 1971 and nearly 60% in 2008, with the remainder supplied by turbulent transfers of sensible and latent heat. Thus, the two experiments are similar in finding that radiation dominates surface melt energy inputs to microbasin runoff outputs. They differ with respect to area definitions and microbasin shapes: (1) a purposely delineated rhomboidal area, 30 m long × 15 m wide, covering 386 m2 in 1971; (2) a naturally delineated elongated area, approximately 600 m long × 2 m wide, covering an estimated 1200 m2 in 2008. Three 24‐hour periods beginning at 0700 h were obtained for experimental work in 1971, and 8 such periods in 2008. Supraglacial runoff was modelled by passing melt energy water equivalents through a simple storage reservoir and forcing closure with measured runoff by optimising for delay time. Optimal times of 1–2 h were found for 1971, and 7·5–11·5 h for 2008, thus indicating a major difference between the runoff responses of the two microbasins. It is possible that different basin shapes may explain the contrasting delay times, perhaps because different shapes signify different flow connections to meltwater storage in the weathering crust. If the elongated microbasin response is typical of the elemental hydrological response unit of the melting ice surface, distributed glacier runoff models should incorporate it as part of the model structure. Copyright © 2011 John Wiley & Sons, Ltd.
On the usefulness of remote sensing input data for spatially distributed hydrological modelling: case of the Tarim River basin in China
Authors: Liu T. , Willems P. , Feng X. W. , Li Q. , Huang Y. , Bao An. M. , Chen X. , Veroustraete F. , Dong Q. H.
Published: April 2011

The ecological situation of the Tarim River basin in China seriously declined since the early 1950s, mainly due to a strong increase in water abstraction for irrigation purposes. To restore the ecological system and support sustainable development of the Tarim River basin region in China, more hydrological studies are demanded to properly understand the processes of the watershed and efficiently manage the water resources. Such studies are, however, complicated due to the limited data availability, especially in the mountainous headwater regions of the Tarim River basin. This study investigated the usefulness of remote sensing (RS) data to overcome that lack of data in the spatially distributed hydrological modelling of the basin. Complementary to the conventional station‐based (SB) data, the RS products that are directly used in this study include precipitation, evapotranspiration and leaf area index. They are derived from raw image data of the Chinese Fengyun meteorological satellite and from the Moderate Resolution Imaging Spectroradiometer (MODIS). The MODIS land surface temperature was used to calculate the atmospheric temperature lapse rate to describe the temperature dependency on topographical variations. Moreover, MODIS‐based snow cover images were used to obtain model initial conditions and as validation reference for the snow model component. Comparison of model results based on RS input versus conventional SB input exhibited similar results in terms of high and low river runoff extremes, cumulative runoff volumes in both runoff and snow melting seasons and spatial and temporal variability of snow cover. During summer time, when the snow cover shrinks in the permanent glacier region, it was found that the model resolution influences the model results dramatically, hence, showing the importance of detailed (RS based) spatially distributed input data. Copyright © 2011 John Wiley & Sons, Ltd.
Use of stable water isotopes to assess sources and influences of slope groundwater on slope failure
Authors: Peng Tsung‐Ren , Wang Chung‐Ho , Hsu Shih‐Meng , Chen Nai‐Chin , Su Tai‐Wei , Lee Jiin‐Fa
Published: April 2011

This study employs stable oxygen and hydrogen isotopes as natural tracers to assess the headwater of a landslide next to a drainage divide and the importance of the slope's headwater in the study area. The study is undertaken near Wu‐She Township in the mountains of central Taiwan. Because a reservoir is located on the other side of the divide, this study evaluates the relationship between the reservoir water and headwater of the landslide as well. Over a 1‐year period, water samples from September 2008 to September 2009, including local precipitation (LP), Wu‐She Reservoir's water (WSRW), slope groundwater (SGW), upper‐reach stream water (USTW), and down‐reach stream water (DSTW), were analysed for deuterium (δD) and oxygen (δ18O) stable isotopes. Results indicate that WSRW is the predominant component in SGW: approximately 70% of SGW originates from WSRW and 30% from LP based on a two end‐member mass‐balance mixing model for δ18O. The similar two end‐member mixing model is also employed to assess the contributions of USTW and SGW to DSTW. Model results indicate that SGW is the major source of DSTW with a contribution of about 67%. Accordingly, about 47% of DSTW sources from the WSRW. In short, owing to reservoir leakage, WSRW contributes the greater part of both SGW and DSTW. Plentiful WSRW in SGW threatens the stability of the slope in the divide area. To avoid subsequent continuous slope failure, necessary mitigation steps are required. Copyright © 2011 John Wiley & Sons, Ltd.
Increased incidence of aflatoxin B1‐induced liver tumors in hepatitis virus C transgenic mice
Authors: Jeannot Emmanuelle , Boorman Gary A. , Kosyk Oksana , Bradford Blair U. , Shymoniak Svitlana , Tumurbaatar Batbayar , Weinman Steven A. , Melnyk Stepan B. , Tryndyak Volodymyr , Pogribny Igor P. , Rusyn Ivan
Published: April 2011

Viral hepatitis and aflatoxin B1 (AFB1) exposure are common risk factors for hepatocellular carcinoma (HCC). The incidence of HCC in individuals coexposed to hepatitis C (HCV) or B virus and AFB1 is greater than could be explained by the additive effect; yet, the mechanisms are poorly understood because of the lack of an animal model. Our study investigated the outcomes and mechanisms of combined exposure to HCV and AFB1. We hypothesized that HCV transgenic (HCV‐Tg; expressing core, E1, E2 and p7, nucleotides 342–2771) mice will be prone to hepatocarcinogenesis when exposed to AFB1. Neonatal (7 days old) HCV‐Tg or C57BL/6J wild‐type (WT) mice were exposed to AFB1 (6 μg/g bw) or tricaprylin vehicle (15 μl/g bw), and male offspring were followed for up to 12 months. No liver lesions were observed in vehicle‐treated WT or HCV‐Tg mice. Tumors (adenomas or carcinomas) and preneoplastic lesions (hyperplasia or foci) were observed in 22.5% (9 of 40) of AFB1‐treated WT mice. In AFB1‐treated HCV‐Tg mice, the incidence of tumorous or pretumorous lesions was significantly elevated (50%, 18 of 36), with the difference largely due to a 2.5‐fold increase in the incidence of adenomas (30.5 vs. 12.5%). Although oxidative stress and steatohepatitis were observed in both AFB1‐treated groups, molecular changes indicative of the enhanced inflammatory response and altered lipid metabolism were more pronounced in HCV‐Tg mice. In summary, HCV proteins core, E1, E2 and p7 are sufficient to reproduce the cocarcinogenic effect of HCV and AFB1, which is a known clinical phenomenon.
Lipid‐apheresis improves microcirculation of the upper limbs
Authors: Rossenbach Jannik , Mueller Gerhard A. , Lange Katharina , Armstrong Victor W. , Schmitto Jan D. , Hintze Erik , Helfmann Jürgen , Konstantinides Stavros , Koziolek Michael J.
Published: April 2011

Lipid‐apheresis (LA) is thought to improve microcirculation. However, limited data are available on the effects on peripheral microcirculation. We investigated upper limb microcirculation of 22 patients undergoing regular LA on a weekly basis before and after LA. Using standardized semiquantitative scales, we analyzed blood flow, vasomotor function, and erythrocyte aggregation by capillary microscopy. In addition, capillary blood flow in quiescence and under heat and cryo‐stress was evaluated by photoplethysmographic and laser Doppler anemometry. Moreover, levels of vasoactive mediators adrenalin, noradrenalin, endothelin‐1 (ET‐1), atrial natriuretic peptide (ANP), asymmetrical dimethyl‐arginine (ADMA), as well as total protein and fibrinogen were measured. We found a significant increase in blood flow, the number of perfused capillaries and an improvement of erythrocyte aggregation by capillary microscopy. Using laser Doppler anemometry, we were able to show that this increase was predominantly located in the superficial layer capillaries (Δ44.53 ± 135.81%, n.s.) and less so in deeper layer arterioles (Δ2.75 ± 24.84%, n.s.). Vascular response to heat and cryo stress was also improved after LA but failed to reach significance. LA significantly reduced levels of epinephrin (−33 ± 39.2%), ANP (−28.8 ± 20.2%), ADMA (−74.1 ± 23%), and fibrinogen (−45.4 ± 19.7%) when comparing before LA and after LA values. In summary, we found an improvement in the microcirculation of the upper limbs under LA, which may result from a decrease of vasoconstrictors, improvement of vasomotor function, and a decrease in blood viscosity or erythrocyte aggregation. J. Clin. Apheresis, 2011. © 2011 Wiley‐Liss, Inc.
Synthesis and anti‐inflammatory activity of 8H‐1‐thia‐8‐aza‐dibenzo[e,h]azulenes
Authors: Ozimec Landek Ivana , Pešić Dijana , Merćep Mladen , Stanić Barbara , Mesić Milan
Published: April 2011

Synthesis of a novel class of fused heterotetracyclic compounds, 8H‐1‐thia‐8‐aza‐dibenzo[e,h]azulenes (VII), is described. Starting N‐benzoyl‐protected 5H‐dibenzo[b,f]azepine (XI, PG = Bz) was oxidized to 5‐benzoyl‐10,11‐epoxy‐10,11‐dihydro‐5H‐dibenzo[b,f]azepine (2), which subsequently rearranged in Lewis acid‐induced epoxide ring opening to give 5‐benzoyl‐5,11‐dihydro‐10H‐dibenzo[b,f]azepin‐10‐one (3). Vilsmeier reaction of 3 provided β‐chlorovinyl aldehyde 4 that readily cyclized with ethyl 2‐mercaptoacetate to form dibenzazepino[4,5]‐fused thiophene structure 5. Further transformation of substituent at C‐2 position of 5 and N‐deprotection led to final aminoalkoxy derivatives 9. All compounds with tetracyclic skeleton were tested in vitro for their anti‐inflammatory activity. J. Heterocyclic Chem., (2011).
An efficient one‐pot synthesis of dispiropyrrolidine derivatives through 1,3‐dipolar cycloaddition reactions under ultrasound irradiation
Authors: Liu Hai , Zou Yi , Hu Yu , Shi Da‐Qing
Published: April 2011

A series of dispiropyrrolidine derivatives were synthesized via the three‐component 1,3‐dipolar cycloaddition reaction of isatin, sarcosine and 5‐arylidene‐1,3‐thiazolidine‐2,4‐dione or 5‐arylidene‐4‐thioxo‐1,3‐thiazolidine‐2‐one in ethanol under ultrasound irradiation. This protocol has the advantages of mild reaction conditions, higher yields, and shorter reaction time. J. Heterocyclic Chem., (2011).
Knowledge management: An innovative risk management strategy
Authors: Zipperer Lorri , Amori Geri
Published: April 2011

Knowledge management effectively lends itself to the enterprise risk process. The authors introduce the concept of knowledge management as a strategy to drive innovation and support risk management. They align this work with organizational efforts to improve patient safety and quality through the effective sharing of experience and lessons learned. The article closes with suggestions on how to develop a knowledge management initiative at an organization, who should be on the team, and how to sustain this effort and build the culture it requires to drive success.
Value‐driven ERM: Making ERM an engine for simultaneous value creation and value protection
Authors: Celona John , Driver Jeffrey , Hall Edward
Published: April 2011

Enterprise risk management (ERM) began as an effort to integrate the historically disparate silos of risk management in organizations. More recently, as recognition has grown of the need to cover the upside risks in value creation (financial and otherwise), organizations and practitioners have been searching for the means to do this. Existing tools such as heat maps and risk registers are not adequate for this task. Instead, a conceptually new value‐driven framework is needed to realize the promise of enterprise‐wide coverage of all risks, for both value protection and value creation. The methodology of decision analysis provides the means of capturing systemic, correlated, and value‐creation risks on the same basis as value protection risks and has been integrated into the value‐driven approach to ERM described in this article. Stanford Hospital and Clinics Risk Consulting and Strategic Decisions Group have been working to apply this value‐driven ERM at Stanford University Medical Center.
Development of a safety culture: Initial measurements at six hospitals in France
Authors: Occelli Pauline , Quenon Jean‐Luc , Hubert Bruno , Kosciolek Thomas , Hoarau Hélène , Pouchadon Marie‐Laure , Amalberti René , Auroy Yves , Salmi Louis‐Rachid , Sibé Matthieu , Parneix Pierre , Michel Philippe
Published: April 2011

A cross‐sectional and descriptive survey of a safety culture (SC) was conducted in 20 clinical units in France. A self‐administered questionnaire measuring 12 dimensions of safety culture was given to healthcare professionals. The overall response rate was 65%. The poorly developed dimensions of safety culture that were identified were nonpunitive response to error, staffing, management support for patient safety, handoffs, and transitions.
A review of the Office of Inspector General's reports on adverse event identification and reporting
Authors: Howe Christopher L.
Published: April 2011

The Office of Inspector General published a series of four reports from 2008 to 2010 after investigating the frequency and financial impact of “never events” on Medicare recipients. This series investigated healthcare's ability to identify the occurrence of these events and yielded a detailed analysis of data that must, or at least should, be reviewed to fully understand the clinical risks affecting organizations. These reports also shed light on the reality that there remains gross underreporting of adverse events in healthcare and begs several questions about healthcare's current efforts to fully identify and understand risk. This article summarizes the reports and considers their risk management implications, particularly regarding adverse events.
Leading in the chaos of the 21st century
Authors: Tetenbaum Toby , Laurence Hank
Published: April 2011

In the transition from a Newtonian paradigm of control and equilibrium to one of chaos and disequilibrium, organizations have substantially changed their structures (e.g., moving to diverse project‐based teams, advancing knowledge management, and building innovative cultures), but they have only minimally changed their leadership styles and practices. This paper describes a model of leadership proposed by Ron Heifetz that optimizes the characteristics of the 21st century in which the leader's role is to disturb equilibrium, differentiate between technical and adaptive challenges, and engage the followers in solving the organization's problems. This model is contrasted with other leadership models to validate its usefulness in the face of chaos, ambiguity, and rapid change. The commitment of the leader to holding steady in the face of predictably strong resistance and the dangers to the leader in using this model are discussed.
Narrative pedagogy, technology, and curriculum transformation in nursing education
Authors: Grendell Ruth N.
Published: April 2011

More than 100 years ago, John Dewey, a major influence in American education, argued for the need to “stimulate the spirit of inquiry into actual fact” (Dewey, 2002, p. 118). The debate among politicians and educators about the structure, purpose, and goals of education and inquiry continues. Yet the world has changed, largely because of widely accessible and versatile technologies. We are unclear how Dewey's spirit of inquiry will grow, die, or reinvent itself through boundaryless tools of inquiry such as the Internet, but the technology is here and will not disappear while educators debate best methods.

Twenty‐first‐century society demands new ways to learn and understand, and these new ways of learning require new ways of teaching (McPheeters, 2009/2010). For many students, especially the younger generations, technology intertwines with almost all daily activities, including social contact. Many educators lag behind the technological curve and express frustration at the challenge to shift their educational paradigms toward increasingly technological means of communication and interaction, or entertain “virtual realities” as legitimate educational forums.

The purpose of this symposium is to examine the role of technology in transforming higher education.
The goal is to seek best methods of using technology more effectively to educate learners for the 21st century. The shifts in society's focus and the characteristics of learners going into the future are also critical, and part of this discussion.
Spatial and temporal dependence of the cerebral endothelial cells elasticity
Authors: Végh Attila G. , Fazakas Csilla , Nagy Krisztina , Wilhelm Imola , Krizbai István A. , Nagyőszi Péter , Szegletes Zsolt , Váró György
Published: April 2011

The reliable determination of the mechanical properties of a living cell is one of the most important challenges of the atomic force microscopic measurements. In the present study the spatial and temporal dependency of the force measurements on cerebral endothelial cells was investigated. Besides imaging the cells, two different sequences of force measurements were applied:

Acquisition of force curves in short time at several points across the cell surface investigating spatial dependence of the elasticity.

Acquisition of force curves for long time at a previously determined place, over the cell nucleus, which provides the temporal stability/variation of the measured forces/values.

Three different stages of endothelial cell cultures of the hCMEC/D3 cells were used: sub‐confluent living, confluent living, and confluent fixed cells. The Young's modulus was calculated from the force curves using the Hertz model and the results were plotted against time or location correspondingly. The rational of using the three stage of culture was to clarify whether the observed effect belongs to the individual cell, to the ensemble of cells or just to some, not living cell component.

In case of sub‐confluent cells the results revealed a softer nuclear region compared to the periphery, while an attenuated oscillation like fluctuation in time, with a period of about 10–30 min, was observed.

Confluent living cells showed similar tendencies to the sub‐confluent cells, but the changes were larger and the temporal oscillations had longer period. The spatial dependency of the elasticity on confluent cells was confirmed by force–volume measurement too.

In case of fixed cells neither spatial nor temporal differences were observed between the nuclear and peripheral region, however the Young's modulus and the error of the measurement was larger, compared to the sub‐confluent living cells. Copyright © 2011 John Wiley & Sons, Ltd.
Analyses of extreme flooding in Austria over the period 1951–2006
Authors: Villarini Gabriele , Smith James A. , Serinaldi Francesco , Ntelekos Alexandros A. , Schwarz Ulrich
Published: April 2011

Analyses of extreme flooding in Austria is performed using daily discharge time series from 27 stations over the period 1951‐2006. The main research questions revolve around: (1) temporal non‐stationarities in the flood record, (2) upper tail and scaling properties of the flood peak records, and (3) relation between magnitude and frequency of flooding and the North Atlantic Oscillation (NAO). Two datasets are derived from the daily discharge time series: annual maximum daily discharge and peaks‐over‐threshold (POT) data. The validity of the stationarity assumption in the annual maximum discharge record is assessed by investigating the presence of abrupt and slowly varying changes using nonparametric tests. The time series are tested for abrupt changes both in the mean and variance of the flood peak distributions by means of the Pettitt test. The presence of monotonic trends is investigated by means of the Mann‐Kendall and Spearman tests. Violations of the stationarity assumption are associated with abrupt rather than gradual changes. These step changes generally involve river regulation through construction of dams or other major engineering works. It is not possible to make conclusive statements about the presence of an anthropogenic climate change signal in the flood peak record. Similar conclusions are obtained when focussing on the frequency of POT floods. The Generalised Extreme Value distribution is used to study the upper tail and scaling properties of annual maximum daily discharge records. The location and scale parameters exhibit power‐law behaviour as a function of drainage area. The shape parameters indicate that the flood peak distributions for Austria have a heavy tail. Non‐stationary modelling of the annual maximum daily discharge and POT time series is used to explore the relation between flood magnitude and frequency and NAO. The results indicate that NAO is a significant covariate in explaining the magnitude and frequency of occurrence of flooding over a large part of Austria. Copyright © 2011 Royal Meteorological Society
Raman imaging and photodegradation study of phthalocyanine containing microcapsules and coated particles
Authors: Bratashov Daniil N. , Masic Admir , Yashchenok Alexey M. , Bedard Matthieu F. , Inozemtseva Olga A. , Gorin Dmitry A. , Basova Tamara , Sievers Torsten K. , Sukhorukov Gleb B. , Winterhalter Mathias , Möhwald Helmuth , Skirtach Andre G.
Published: April 2011

We present the results of using Raman molecular imaging and atomic force microscopy (AFM) investigation of the composition, stability, and photodegradation of polyelectrolyte multilayer microcapsules and coated microparticles containing copper–phthalocyanine and iron–phthalocyanine. The influence of laser light on degradation of these phthalocyanine dyes embedded in the walls of polyelectrolyte multilayer capsules and shells of microparticles was studied by both AFM and Raman molecular imaging, but only the latter technique gave information on dynamics of photodegradation. Raman peak assignment was performed according to theoretical calculations. The degradation rate of phthalocyanine dyes is estimated from Raman signal measurements and a model is proposed to account for the degradation rate. Practical applications of our approach are outlined. Copyright © 2011 John Wiley & Sons, Ltd.
Quick detection of contaminants leaching from polypropylene centrifuge tubes with surface‐enhanced Raman spectroscopy and ultraviolet absorption spectroscopy
Authors: Xu Zhida , Gartia Manas R. , Choi Charles J. , Jiang Jing , Chen Yi , Cunningham Brian T. , Liu Gang Logan
Published: April 2011

Anomalous surface‐enhanced Raman scattering (SERS) peaks were identified for liquid sample stored in polypropylene (PP) centrifuge tubes for months. We observed unexpected Raman peaks during experiments with thiamine hydrochloride aqueous solutions stored in PP tubes for 2 months. In order to identify the contaminants, we have performed SERS experiments on deionized (DI) water stored in PP centrifuge tubes for 2 months and compared them with those from fresh DI water sample. We have also carried out ultraviolet (UV) absorption spectra for both fresh and contaminated water. We believe that the water is contaminated because of chemicals leaching from the PP tube. From the gas chromatography‐mass spectrometry data, the main contaminants were found to be phthalic acid (PA) and its derivatives. Further SERS and UV absorption experiment for PA correlated well with the anomalous peaks identified earlier. We qualitatively confirmed the identification and quantitatively estimated the concentration of the suspect contaminants as between 1 and 10 µM with both SERS and UV absorption spectroscopy. With UV absorption spectroscopy, we precisely estimated the concentration as 2.1 µM. We have shown that the sample in PP tube can be contaminated by the leaching chemicals upon long‐term storage, and suggest SERS and UV absorption spectroscopy as two quick and simple techniques to detect the contamination. Copyright © 2011 John Wiley & Sons, Ltd.
Influence of phonon confinement, surface stress, and zirconium doping on the Raman vibrational properties of anatase TiO2 nanoparticles
Authors: Lejon Christian , Österlund Lars
Published: April 2011

We present a comprehensive analysis of the Raman spectra of pure and zirconium‐doped anatase TiO2 nanoparticles. To account for the wavenumber shifts of the Eg(ν6) mode as a function of particle size (L) and dopant concentration (x), a modification of the standard phonon confinement model (PCM) is introduced, which takes into account the contribution of surface stress by means of the Laplace–Young equation. Together with X‐ray diffraction (XRD) and transmission electron microscopy data, our analysis shows that the surface stress contribution to the observed blue shift of the Raman wavenumber is of the same magnitude as the spatial phonon confinement effect. Annealing experiments show that Zr‐doped nanoparticles exhibit retarded grain growth and delayed anatase‐to‐rutile phase transition by up to 200 K compared to pure anatase TiO2. XRD shows that Zr doping leads to a unit cell expansion of the anatase structure. Applying the modified PCM to the x‐dependent variations of the Eg(ν6) Raman mode, the mode‐Grüneisen parameter is found to increase abruptly at x > 0.07 with a concomitant mode softening. This coincides with the x range over which the Zr cations are reported to be displaced from their position in the tetrahedral lattice, and where Zr precipitation occurs upon annealing. The results have implications for the interpretation of Raman spectra of ionic metal oxide nanoparticles and how these are modified upon cation doping. Copyright © 2011 John Wiley & Sons, Ltd.
ARBUSCULAR MYCORRHIZAL FUNGI IN REVEGETATED MINED DUNES
Authors: de Souza R. G. , da Silva D. K. A. , de Mello C. M. A. , Goto B. T. , da Silva F. S. B. , Sampaio E. V. S. B. , Maia L. C.
Published: April 2011

This study aimed to thoroughly investigate communities of arbuscular mycorrhizal fungi (AMF) in six coastal, mined, reconstituted and revegetated dune areas in Northeast Brazil. AMF spore density and species richness as well as the numbers of infective AMF propagules and glomalin‐related soil protein (GRSP) were analyzed. Four areas had been restored for 16, 12, 8 and 4 years, and after being mined, reconstituted and re‐vegetated, the fifth was mined and reconstituted but not yet re‐vegetated, and the sixth had a native and undisturbed coastal forest vegetation. The soil samples were sampled in the dry and wet seasons of 2005. The number of infective propagules was significantly higher in the dry than in wet season, except in the un‐vegetated dune area, which had less than 0·2 propagules cm−3 soil. AMF spore density and especially GRSP contents changed little between the seasons. GRSP contents were positively correlated to Al and Fe soil levels and were highest in the restinga forest. In total, 29 AMF species were identified, and glomoid and gigasporoid species predominated in all areas. AMF species richness and viable propagules of AMF were lowest in the un‐vegetated dune area. Remarkably, higher species richness (28) was found in the re‐vegetated areas, compared with the forest area that had only 10 species. The numbers of infective propagules tended to be also lower in the forest than in the re‐vegetated sites. In conclusion, re‐vegetation appears to favour the AMF communities in terms of infective propagule numbers and AMF species richness. Copyright © 2011 John Wiley & Sons, Ltd.
Synergistic effect of diisopropyl phosphite and over‐based calcium sulphonate additives on tribological properties of AISI 52100 steel/Al2O3 ceramics
Authors: Jiang Shuyun , Xie Hongjun
Published: April 2011

The friction‐reducing and anti‐wear effect of the 500SN base oil containing diisopropyl phosphite (T451) and over‐based calcium sulphonate (KT5447) on AISI 52100 steel/Al2O3 ceramic were investigated with a ball‐on‐disc tribometer at a light load of 200 N and a high load of 400 N. The results indicate that the 500SN base oil containing T451 and KT5447 appears to have a synergistic effect on the pair. For the light load of 200 N, the effective composition is 3 wt% T451 + 2–3 wt% KT5447. For the high load of 400 N, the combination of T451 and KT5447 appears to have a synergistic friction‐reducing and anti‐wear effect. The scanning electron microscope images show that ploughed grooves, pitting, spalling and corrosion are the dominant wear modes for both 200 and 400 N. However, no evidence for the formation of the expected sulphur‐containing or phosphorus‐containing chemical compound is found according to X‐ray photoelectron spectroscopy analysis of the worn steel ball surface at both loads. Copyright © 2011 John Wiley & Sons, Ltd.
The effects of a demulsifier on the interface of marine engine oil and water
Authors: Lu Ya , Chen Xiaoxu
Published: April 2011

The water‐shedding property and the interfacial tension of marine engine oils with various additives have been assessed and analysed in this paper. It is concluded that the weak water‐shedding property was mainly due to the molecular structure and the interfacial property of sulphonate detergent, which can adsorb on the oil–water interface intensely to form a strong interfacial film and prevent coalescence of droplets. The impact of a demulsifier to the water‐shedding property and the interfacial tension indicated that demulsifier improved the water‐shedding property of marine engine oil in the manner of being much easy to adsorb onto the interface but formatting a flimsy interfacial film. Copyright © 2011 John Wiley & Sons, Ltd.
A prospective, randomized controlled trial on the efficacy of fractional photothermolysis on scar remodeling
Authors: Lin Jennifer Y. , Warger William C. , Izikson Leonid , Anderson R. Rox , Tannous Zeina
Published: April 2011

Background

Non‐ablative fractional resurfacing (NAFR) has been reported in case studies as an effective treatment for surgical and burn scars [Behroozan et al., J Cosmet Laser Ther 2006; 8(1):35–38; Haedersdal et al., Lasers Surg Med 2009; 41(3):189–195; Waibel and Beer, J Drugs Dermatol 2008; 7(1):59–61; Niwa et al., Dermatol Surg 2009; 35(5):773–777; discussion 777–778; and Tierney et al., Dermatol Surg 2009; 35(8):1172–1180]. We have performed a prospective, randomized controlled study with two different treatment arms to better characterize the response of hypertrophic scars to NAFR.

Study Design

We conducted a prospective, controlled trial on linear, surgical hypertrophic scars 6 months or older in age. Subjects were randomized into two treatment arms of NAFR: (a) high‐density treatment arm (HDTA): 40 mJ and percent coverage of 26% and (b) low‐density treatment arm (LDTA): 40 mJ and percent coverage of 14%. One‐half of the scar was treated every 2 weeks for a total of four treatments, with subsequent follow‐up visits at 1 month and 3 months. Scar improvement was judged as compared to the untreated side by the subjects and two blinded observers using a four‐point scale (0 = no improvement or worsening, 1 = minor improvement, 2 = moderate improvement, and 3 = marked improvement). Volumetric changes were also measured for a select group (n = 4) by measuring scar casts with optical frequency domain imaging. Patient satisfaction was surveyed at the end of the trial. Side effects in both treatment arms were assessed.

Results

Twenty patients were enrolled, of which 17 subjects noted improvement in their scars compared to untreated side. Three subjects in the HDTA rated their scars as having a worsened appearance at the end of the study. After treatment was completed, scars continued to improve in appearance at 3 months compared to 1 month. Subjects in the LDTA rated the treated side with higher scores, than subjects in the HDTA (P = 0.001). Scars <2 years old tended to respond better to NAFR as compared to scars >6 years old. The side effects profile was more severe in the HDTA group. Nevertheless, all subjects were satisfied with the procedure at trial completion.

Conclusions

This study demonstrates the efficacy of NAFR for treating hypertrophic scars. Low‐density treatment is at least as effective as the high‐density treatment and with fewer side effects. The study also suggests that younger scars respond better to NAFR. Thus, early intervention may be key in the treatment of hypertrophic scars. Lasers Surg. Med. 43:265–272, 2011. © 2011 Wiley‐Liss, Inc.
Neuron Cells Uptake of Polymeric Microcapsules and Subsequent Intracellular Release
Authors: Pavlov Anton M. , Sapelkin Andrei V. , Huang Xinyue , P'ng Ken M. Y. , Bushby Andy J. , Sukhorukov Gleb B. , Skirtach André G.
Published: April 2011

Neuron cells uptake of biodegradable and synthetic polymeric microcapsules functionalized with aggregates of gold nanoparticles incorporated into their shells is demonstrated in situ. In addition to traditionally used optical microscopy, electron microscopy is used both for higher‐resolution imaging and for confirming the uptake by focused ion beam cross‐sectioning of specific cells in situ. Subsequently, physical methods of release are compared to chemical methods wherein laser‐induced intracellular release of dextran molecules into the cytosol of hippocampal neuron cells is studied in comparison to biodegradation. Implications of this work for neuroscience, bio‐medicine and single cell studies are discussed.

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Microgels for the Encapsulation and Stimulus‐Responsive Release of Molecules with Distinct Polarities
Authors: Jagadeesan Dinesh , Nasimova Irina , Gourevich Ilya , Starodubtsev Sergey , Kumacheva Eugenia
Published: April 2011

A microfluidic strategy for the encapsulation and stimulus‐responsive release of molecules with distinct polarities from the interior of microgels is reported. The approach relies on (i) the generation of a primary O/W emulsion by the ultrasonication method, (ii) MF emulsification of the primary emulsion, and (iii) photopolymerization of the monomer present in the aqueous phase of the droplets, thereby transforming them into microgels. Non‐polar molecules are dissolved in oil droplets embedded in the microgels. Polar molecules are physically associated with the hydrogel network. Upon heating, the microgels contract and release polar and non‐polar cargo molecules. The approach paves the way for stimuli‐responsive vehicles for multiple drug delivery.

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A new steel with good low‐temperature sulfuric acid dew point corrosion resistance
Authors: Cheng X. Q. , Sun F. L. , Lv S. J. , Li X. G.
Published: April 2011

In this work, new steels (1#, 2#, and 3#) were developed for low‐temperature sulfuric acid dew point corrosion. The mass loss rate, macro‐ and micro‐morphologies and compositions of corrosion products of new steels in 10, 30, and 50% H2SO4 solutions at its corresponding dew points were investigated by immersion test, scanning electron microscopy (SEM) and energy‐dispersive spectrometry (EDS). The results indicated that mass loss rate of all the tested steels first strongly increased and then decreased as H2SO4 concentration increased, which reached maximum at 30%. Corrosion resistance of 2# steel is the best among all specimens due to its fine and homogeneous morphologies of corrosion products. The electrochemical corrosion properties of new steels in 10 and 30% H2SO4 solutions at its corresponding dew points were studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results demonstrated that corrosion resistance of 2# steel is the best among all the experimental samples due to its lowest corrosion current density and highest charge transfer resistance, which is consistent with the results obtained from immersion tests.
Four‐dimensional visualisation and analysis of protein–protein interaction networks
Authors: Goel Apurv , Li Simone S. , Wilkins Marc R.
Published: April 2011

Protein–protein interaction networks are typically built with interactions collated from many experiments. These networks are thus composite and show all interactions that are currently known to occur in a cell. However, these representations are static and ignore the constant changes in protein–protein interactions. Here we present software for the generation and analysis of dynamic, four‐dimensional (4‐D) protein interaction networks. In this, time‐course‐derived abundance data are mapped onto three‐dimensional networks to generate network movies. These networks can be navigated, manipulated and queried in real time. Two types of dynamic networks can be generated: a 4‐D network that maps expression data onto protein nodes and one that employs ‘real‐time rendering’ by which protein nodes and their interactions appear and disappear in association with temporal changes in expression data. We illustrate the utility of this software by the analysis of singlish interface date hub interactions during the yeast cell cycle. In this, we show that proteins MLC1 and YPT52 show strict temporal control of when their interaction partners are expressed. Since these proteins have one and two interaction interfaces, respectively, it suggests that temporal control of gene expression may be used to limit competition at the interaction interfaces of some hub proteins. The software and movies of the 4‐D networks are available at http://www.systemsbiology.org.au/downloads_geomi.html.