bluuebunny/crossref_metadata_2025 huggingface dataset:
Avidity maturation of anti–citrullinated protein antibodies in rheumatoid arthritis
Authors: Suwannalai P. , van de Stadt L. A. , Radner H. , Steiner G. , El‐Gabalawy H. S. , Zijde C. M. Jol‐van der , van Tol M. J. , van Schaardenburg D. , Huizinga T. W. J. , Toes R. E. M. , Trouw L. A.
Published: December 2011

Objective

Anti–citrullinated protein antibodies (ACPAs) are highly specific for rheumatoid arthritis (RA) and are present years before the onset of symptoms. The avidity of autoantibodies can have a strong impact on their effector potency. This study was undertaken to analyze the avidity of ACPAs in serum samples obtained from ACPA‐positive healthy individuals (predisease), patients with early disease, and patients with established RA as well as the avidity maturation over time in samples from healthy subjects who later developed RA.

Methods

We measured ACPA avidity in serum samples from ACPA‐positive healthy individuals, symptomatic individuals, and patients with established RA in 5 collections from The Netherlands, Canada, and Austria. We determined the dynamics of avidity maturation of ACPAs from the predisease stage to established disease in 1 case from the native North American population and in 10 cases from a Dutch blood donor cohort.

Results

The overall ACPA response was characterized by low‐avidity antibodies. Higher‐avidity ACPAs were observed in symptomatic patients only, while low‐avidity ACPAs were observed in both healthy subjects and patients. In longitudinal samples obtained from subjects prior to disease onset, ACPA avidity increased over time until disease onset. No further avidity maturation was observed after disease onset.

Conclusion

Our findings indicate that avidity maturation of the ACPA response takes place prior to disease onset.
Steam Reforming of Bio‐Oil for Hydrogen Production: Effect of Ni‐Co Bimetallic Catalysts
Authors: Zhang Y. , Li W. , Zhang S. , Xu Q. , Yan Y.
Published: December 2011

Various Ni‐Co bimetallic catalysts were prepared by incorporating sol‐gel and wet impregnation methods. A laboratory‐scale fixed‐bed reactor was employed to investigate their effects on hydrogen production from steam reforming of bio‐oil. The catalyst causes the condensation reaction of bio‐oil, which generates coke and inhibits the formation of gas at temperatures of 250 °C and 350 °C. At 450 °C and above the transformation of bio‐oil is initiated and gaseous products are generated. The catalyst also can promote the generation of H2 as well as the transformation of CO and CH4 and plays an active role in steam reforming of bio‐oil or gaseous products from bio‐oil pyrolysis. The developed 3Ni9Co/Ce‐Zr‐O catalyst achieved maximum hydrogen yield and lowest coke formation rate and provided a better stability than a commercial Ni‐based catalyst.
Insights into Protein Sorption and Desorption on Dextran‐Modified Ion‐Exchange Media
Authors: Bowes B. D. , Traylor S. J. , Timmick S. M. , Czymmek K. J. , Lenhoff A. M.
Published: December 2011

A diverse array of experimental techniques was used to compare protein sorption and transport on agarose‐based resins with and without dextran extenders. Van 't Hoff plots indicated similar trends for lysozyme on the resins, with enthalpically dominated sorption. Salt breakthrough curves demonstrated significant exclusion of salt from the dextran, consistent with Donnan equilibrium predictions. Polarization‐sensitive confocal microscopy and fluorescence recovery after photobleaching (FRAP) exhibited little effect of dextran modification on the respective rotational and translation mobilities of adsorbed protein at equilibrium. Finally, confocal microscopy imaging of intraparticle elution behavior showed that slower elution can occur for dextran‐modified resins.
From an Octakis(3‐cyanopropyl)silsesquioxane Building Block to a Highly COOH‐Functionalized Hybrid Organic–Inorganic Material
Authors: Boullanger Arnaud , Gracy Guillaume , Bibent Nicolas , Devautour‐Vinot Sabine , Clément Sébastien , Mehdi Ahmad
Published: December 2011

A new nanostructured and highly COOH‐functionalized hybrid organic–inorganic material has been synthesized by the hydrolysis of oligomeric octahedral silsesquioxane (POSS), which contains eight cyanopropyl groups. The hybrid, elemental building block oligomeric octakis(3‐cyanopropyl)silsesquioxane (CN‐POSS) was synthesized from oligomeric octakis(3‐chloropropyl)silsesquioxane (Cl‐POSS) by an exchange reaction. The formation and nanostructuration of the COOH‐functionalized hybrid material were induced by noncovalent hydrogen bonding between COOH‐POSS units without decomposition of the core. The material has been fully characterized by scanning electron microscopy, FTIR and 1H, 13C, and 29Si solid‐state NMR spectroscopy, X‐ray diffraction, and elemental analysis, which confirm that the POSS core remains intact after each chemical modification step. Thermogravimetric analysis indicates that the organic units are thermally stable up to 200 °C. The activation energy related to the proton conductivity of COOH‐POSS has been evaluated and confirms the presence of strong hydrogen bonds. Finally, the accessibility and adsorption capacity of the COOH groups towards transition metal ions have been demonstrated and underline the potential of these hybrid materials in extraction chemistry.
Regioselective Formation of Silylated Cyclobutenes by the Photochemical [2+2] Cycloaddition of 2(5H)‐Furanones to Trialkylsilylacetylenes
Authors: D'Annibale Andrea , D'Auria Maurizio , Mancini Giovanna , Pace Alessio Daniel , Racioppi Rocco
Published: December 2011

Enantiopure 5‐alkyl‐4‐methyl‐2(5H)‐furanones reacted by [2+2] photochemical cycloaddition with several trialkylsilylacetylenes to afford regioselectively 3‐oxabicyclo[3.2.0]hept‐6‐en‐2‐ones silylated at the vinylic C‐7 atom. The possible reasons for such regioselectivity are discussed. The anti/syn stereoselectivity of the photocycloaddition depends on the nature of the alkyl group on the silicon atom in the starting silylacetylenes.
Nitrogen‐ and Phosphorus‐Containing Lewis Base Catalyzed [4+2] and [3+2] Annulation Reactions of Isatins with But‐3‐yn‐2‐one
Authors: Lian Zhong , Shi Min
Published: December 2011

Nitrogen‐ and phosphorus‐containing Lewis base catalyzed [4+2] and [3+2] annulations of isatins with but‐3‐yn‐2‐one proceeded smoothly to give the corresponding spiro[indoline‐3,2′‐pyran]‐2,4′(3′H)‐diones and spiro[furan‐2,3′‐indoline]‐2′,4(5H)‐diones in good‐to‐excellent yields under mild conditions. The substrate scope has been carefully examined. Moreover, the additive effect of water has also been investigated in detail along with plausible reaction mechanisms based on previous literature and our own investigations.
Incorporating biological information into association studies of sequencing data
Authors: Chen Gary , Wei Peng , DeStefano Anita L.
Published: December 2011

We summarize the methodological contributions from Group 3 of Genetic Analysis Workshop 17 (GAW17). The overarching goal of these methods was the evaluation and enhancement of state‐of‐the‐art approaches in integration of biological knowledge into association studies of rare variants. We found that methods loosely fell into three major categories: (1) hypothesis testing of index scores based on aggregating rare variants at the gene level, (2) variable selection techniques that incorporate biological prior information, and (3) novel approaches that integrate external (i.e., not provided by GAW17) prior information, such as pathway and single‐nucleotide polymorphism (SNP) annotations. Commonalities among the findings from these contributions are that gene‐based analysis of rare variants is advantageous to single‐SNP analysis and that the minor allele frequency threshold to identify rare variants may influence power and thus needs to be carefully considered. A consistent increase in power was also identified by considering only nonsynonymous SNPs in the analyses. Overall, we found that no single method had an appreciable advantage over the other methods. However, methods that carried out sensitivity analyses by comparing biologically informative to noninformative prior probabilities demonstrated that integrating biological knowledge into statistical analyses always, at the least, enabled subtle improvements in the performance of any statistical method applied to these simulated data. Although these statistical improvements reflect the simulation model assumed for GAW17, our hope is that the simulation models provide a reasonable representation of the underlying biology and that these methods can thus be of utility in real data. Genet. Epidemiol. 35:S29–S34, 2011. © 2011 Wiley Periodicals, Inc.
Identification of genetic association of multiple rare variants using collapsing methods
Authors: Sun Yan V. , Sung Yun Ju , Tintle Nathan , Ziegler Andreas
Published: December 2011

Next‐generation sequencing technology allows investigation of both common and rare variants in humans. Exomes are sequenced on the population level or in families to further study the genetics of human diseases. Genetic Analysis Workshop 17 (GAW17) provided exomic data from the 1000 Genomes Project and simulated phenotypes. These data enabled evaluations of existing and newly developed statistical methods for rare variant sequence analysis for which standard statistical methods fail because of the rareness of the alleles. Various alternative approaches have been proposed that overcome the rareness problem by combining multiple rare variants within a gene. These approaches are termed collapsing methods, and our GAW17 group focused on studying the performance of existing and novel collapsing methods using rare variants. All tested methods performed similarly, as measured by type I error and power. Inflated type I error fractions were consistently observed and might be caused by gametic phase disequilibrium between causal and noncausal rare variants in this relatively small sample as well as by population stratification. Incorporating prior knowledge, such as appropriate covariates and information on functionality of SNPs, increased the power of detecting associated genes. Overall, collapsing rare variants can increase the power of identifying disease‐associated genes. However, studying genetic associations of rare variants remains a challenging task that requires further development and improvement in data collection, management, analysis, and computation. Genet. Epidemiol. 35:S101–S106, 2011. © 2011 Wiley Periodicals, Inc.
Effect of linkage disequilibrium on the identification of functional variants
Authors: Thomas Alun , Abel Haley J. , Di Yanming , Faye Laura L. , Jin Jing , Liu Jin , Wu Zheyan , Paterson Andrew D.
Published: December 2011

We summarize the contributions of Group 9 of Genetic Analysis Workshop 17. This group addressed the problems of linkage disequilibrium and other longer range forms of allelic association when evaluating the effects of genotypes on phenotypes. Issues raised by long‐range associations, whether a result of selection, stratification, possible technical errors, or chance, were less expected but proved to be important. Most contributors focused on regression methods of various types to illustrate problematic issues or to develop adaptations for dealing with high‐density genotype assays. Study design was also considered, as was graphical modeling. Although no method emerged as uniformly successful, most succeeded in reducing false‐positive results either by considering clusters of loci within genes or by applying smoothing metrics that required results from adjacent loci to be similar. Two unexpected results that questioned our assumptions of what is required to model linkage disequilibrium were observed. The first was that correlations between loci separated by large genetic distances can greatly inflate single‐locus test statistics, and, whether the result of selection, stratification, possible technical errors, or chance, these correlations seem overabundant. The second unexpected result was that applying principal components analysis to genome‐wide genotype data can apparently control not only for population structure but also for linkage disequilibrium. Genet. Epidemiol. 35:S115–S119, 2011. © 2011 Wiley Periodicals, Inc.
Missense PANK2 mutation without “Eye of the tiger” sign: MR findings in a large group of patients with pantothenate kinase‐associated neurodegeneration (PKAN)
Authors: Delgado Rafael Fermin , Sanchez Pedro Roa , Speckter Herwin , Then Eddy Perez , Jimenez Ramney , Oviedo Jairo , Dellani Paulo R. , Foerster Bernd , Stoeter Peter
Published: December 2011

Purpose:

To present some unusual MR findings in a group of patients from the south‐west of the Dominican Republic suffering from Pantothenate Kinase Associated Neurodegeneration (PKAN).

Materials and Methods:

Twenty patients and one preclinical case homozygous for the PANK2 mutation, 13 heterozygous gene carriers and 14 healthy volunteers were scanned prospectively using a 3 Tesla system.

Results:

All patients showed the typical signal reduction within the globus pallidus and the substantia nigra. A surprising finding was the absence of the bright spot (“tiger's eye”) in the medial part of the pallidum in 6 patients, but not in the preclinical case. Both fractional anisotropy (FA) and mean diffusivity (MD) were increased with high significance in the globus pallidus, whereas a reduction of FA in the anterior parts of the internal capsule was accompanied by an elevation of MD.

Conclusion:

Our findings support the hypothesis that the absence of the “tiger's eye” in PKAN might be secondary, probably caused by an increased accumulation of iron. This could artificially increase FA and MD values and change fiber tracking results. Except for the fronto‐basal tracts, white matter was preserved well. This encouraging finding might support efforts to develop further therapeutic strategies in this devastating dystonia. J. Magn. Reson. Imaging 2012;35:788–794. © 2011 Wiley Periodicals, Inc.
Identification of active compounds from medicinal plant extracts using gas chromatography‐mass spectrometry and multivariate data analysis
Authors: Ching Jianhong , Soh Wei‐Li , Tan Chay‐Hoon , Lee Jun‐Feng , Tan Jiun‐Yu Christina , Yang Jun , Yap Chun‐Wei , Koh Hwee‐Ling
Published: December 2011

Conventional methods of drug discovery from natural products include bioassay‐guided fractionation, which is tedious and has low efficiency. The aim of this work is to develop a platform method to rapidly identify bioactive compounds from crude plant extracts and their partially purified fractions using multivariate data analysis (MVDA). Soxhlet extraction and liquid–liquid fractionation were used to prepare different extracts and fractions from the leaves of a medicinal plant, Ardisia elliptica. The extracts and fractions were analysed chemically using GC‐MS, and their ability to inhibit platelet aggregation was investigated. Two MVDA methods were developed and optimised to analyse the results. In the first method, compounds with the highest contribution scores for biological activity calculated by different models were listed as potential antiplatelet compounds. For the second MVDA method, a correlation of the concentrations of constituents and biological activities in the various extracts and fractions for each compound was done. Compounds with the highest correlation coefficients were identified as potential antiplatelet compounds. One of the predicted components was isolated, purified and confirmed to possess antiplatelet effects. This platform method can be developed and optimised for other plant extracts and biological activities, thus reducing time and cost of drug discovery while improving efficiency.
Er:YAG laser debonding of porcelain veneers
Authors: Morford Cynthia K. , Buu Natalie C.H. , Rechmann Beate M.T. , Finzen Frederick C. , Sharma Arun B. , Rechmann Peter
Published: December 2011

Background and Objectives

The removal of porcelain veneers using Er:YAG lasers has not been previously described in the scientific literature. This study was designed to systematically investigate the efficacy of an Er:YAG laser on veneer debonding, possibly without damage to the underlying tooth, and preservation of the veneer integrity.

Study Design/Materials and Methods

The Fourier Transform Infrared Spectroscopy was used on 10 flat veneer samples (IPS Empress Esthetic, e.max Press HT) to assess which infrared laser wavelengths transmits through a veneer. Additionally, Fourier Transform Infrared (FTIR) spectra for a bonding cement (RelyX) were obtained. Consequently, Er:YAG laser energy transmission (wavelength 2,940 nm, 10 Hz repetition rate, pulse duration 100 µseconds at 133 mJ/pulse) through different veneer thicknesses was measured. Twenty‐four veneers were bonded to freshly extracted and prepared incisors. The energy necessary for debonding was determined and then the veneers were debonded with the laser. Time needed for total debonding was measured and possible damage to the underlying tooth structure was assessed by light microscopy.

Results

While the veneer materials did not show any characteristic water absorption bands in the FTIR, the bonding cement showed a broad H2O/OH absorption band. The veneers transmitted between 11.5% and 43.7% of the incident Er:YAG energy with Emax transmitting twice the energy as EE at comparable thicknesses. Initial signs of cement ablation occurred at 1.8–4.0 J/cm2 with the fiber tip positioned at a distance of 3–6 mm from the veneer surface and 133 mJ output energy. All 24 bonded veneers were completely removed with an average removal time of 113 ± 76 seconds. Underlying tooth structure was not damaged. The debonding mainly occurred at the cement/veneer interface. None of the Emax veneers fractured during debonding, while 36% of the EE did.

Conclusion

Er:YAG laser irradiation effectively debonds porcelain veneers while preserving tooth structure. Maintaining veneer integrity possibly depends on the flexure strength of the veneer porcelain. Lasers Surg. Med. 43:965–974, 2011. © 2011 Wiley Periodicals, Inc.
Ideal current patterns yielding optimal signal‐to‐noise ratio and specific absorption rate in magnetic resonance imaging: Computational methods and physical insights
Authors: Lattanzi Riccardo , Sodickson Daniel K.
Published: December 2011

At high and ultra‐high magnetic field strengths, understanding interactions between tissues and the electromagnetic fields generated by radiofrequency coils becomes crucial for safe and effective coil design as well as for insight into limits of performance. In this work, we present a rigorous electrodynamic modeling framework, using dyadic Green's functions, to derive the electromagnetic field in homogeneous spherical and cylindrical samples resulting from arbitrary surface currents in the presence or absence of a surrounding radiofrequency shield. We show how to calculate ideal current patterns that result in the highest possible signal‐to‐noise ratio (ultimate intrinsic signal‐to‐noise ratio) or the lowest possible radiofrequency power deposition (ultimate intrinsic specific absorption rate) compatible with electrodynamic principles. We identify familiar coil designs within optimal current patterns at low to moderate field strength, thereby establishing and explaining graphically the near‐optimality of traditional surface and volume quadrature designs. We also document the emergence of less familiar patterns, e.g., involving substantial electric‐ as well as magnetic‐dipole contributions, at high field strength. Performance comparisons with particular coil array configurations demonstrate that optimal performance may be approached with finite arrays if ideal current patterns are used as a guide for coil design. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Model selection for DCE‐T1 studies in glioblastoma
Authors: Bagher‐Ebadian Hassan , Jain Rajan , Nejad‐Davarani Siamak P. , Mikkelsen Tom , Lu Mei , Jiang Quan , Scarpace Lisa , Arbab Ali S. , Narang Jayant , Soltanian‐Zadeh Hamid , Paudyal Ramesh , Ewing James. R.
Published: December 2011

Dynamic contrast enhanced T1‐weighted MRI using the contrast agent gadopentetate dimeglumine (Gd‐DTPA) was performed on 10 patients with glioblastoma. Nested models with as many as three parameters were used to estimate plasma volume or plasma volume and forward vascular transfer constant (Ktrans) and the reverse vascular transfer constant (kep). These constituted models 1, 2, and 3, respectively. Model 1 predominated in normal nonleaky brain tissue, showing little or no leakage of contrast agent. Model 3 predominated in regions associated with aggressive portions of the tumor, and model 2 bordered model 3 regions, showing leakage at reduced rates. In the patient sample, vp was about four times that of white matter in the enhancing part of the tumor. Ktrans varied by a factor of 10 between the model 2 (1.9 ↔ 10−3 min−1) and model 3 regions (1.9 ↔ 10−2 min−1). The mean calculated interstitial space (model 3) was 5.5%. In model 3 regions, excellent curve fits were obtained to summarize concentration‐time data (mean R2 = 0.99). We conclude that the three parameters of the standard model are sufficient to fit dynamic contrast enhanced T1 data in glioblastoma under the conditions of the experiment. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Quantification of arterial cerebral blood volume using multiphase‐balanced SSFP‐based ASL
Authors: Yan Lirong , Li Cheng , Kilroy Emily , Wehrli Felix W. , Wang Danny J. J.
Published: December 2011

A new technique is introduced in this study for in vivo measurement of arterial cerebral blood volume by combining arterial spin labeling with a segmented multiphase balanced steady‐state free precession (bSSFP) readout sequence. This technique takes advantage of the phenomenon that the longitudinal magnetization of flowing blood is not or only marginally disturbed (besides T1 relaxation) by the bSSFP ±α pulse train. When the blood water exchanges into tissue, it becomes quickly saturated by the bSSFP pulse train due to 0 velocity and reduced T1, T2 relaxation times. Therefore, labeled blood water behaves like an intravascular contrast agent in multiphase bSSFP scans, and can be used to quantify arterial cerebral blood volume in a similar way as dynamic susceptibility contrast MRI. Both Bloch equation simulation and in vivo experiments were carried out to demonstrate the feasibility for quantifying cerebral blood volume in arteries, arterioles, and capillaries using two variants of the proposed method. Functional MRI of visual cortex stimulation was further performed using multiphase bSSFP‐based arterial spin labeling and compared with vascular‐space occupancy contrast. The proposed multiphase bSSFP‐based arterial spin labeling technique may allow separation of cerebral blood volume of different vascular compartments for functional MRI studies and clinical evaluation of the cerebral vasculature. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Properties of single‐walled carbon nanotube‐based poly(phenylene vinylene) electroluminescent nanocomposites
Authors: AbdulBaki Mansour K. , Tangonan Andrew , Advincula Rigoberto C. , Randall Lee T. , Krishnamoorti Ramanan
Published: December 2011

Devices with varying concentrations of single‐walled carbon nanotubes (SWNTs) dispersed in three derivatives of poly(p‐phenylene vinylene) are prepared, and their electroluminescent properties evaluated. Increasing the concentration of SWNTs improves the electrical conductivity of the nanocomposites. However, an undesired increase in the electroluminescence (EL) turn‐on voltage is observed for the hybrids, possibly due to photoluminescence quenching of excitons by the SWNTs. At relatively low concentrations of SWNTs, there is an increase in the EL lifetime; in contrast, at relatively high concentrations of SWNTs, due to photoluminescence quenching by the nanotubes, significant reduction in brightness and faster degradation of the EL performance of the devices is observed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Clinical Issues—December 2011
Authors: Giarrizzo‐Wilson Sharon , Maxwell‐Downing Denise , Bianco Jessica
Published: December 2011

This Month

Pre‐charting patient care information

Key words: documentation, pre‐charting, corrections, electronic health record.

Using the most current edition of the Perioperative Nursing Data Set (PNDS)

Key words: Perioperative Nursing Data Set, PNDS 3rd edition, PNDS 2nd edition, clinical terminology, versioning.

Data quality and the electronic health record (EHR)

Key words: data quality, electronic health record, retrospective data analysis, front‐end data acquisition.

Assessing and improving the quality of health care data

Key words: data quality assurance, information quality, data quality control, subjective data metrics, objective data metrics.

Electronic documentation and quality patient care

Key words: nursing documentation, information system, designing an electronic documentation system.
Results of the 2011 AORN Salary and Compensation Survey
Authors: Bacon Donald
Published: December 2011

AORN conducted its ninth annual compensation survey for perioperative nurses in June and July 2011. A multiple regression model was used to examine how a number of variables, including job title, education level, certification, experience, and geographic region, affect nurse compensation. Comparisons between the 2011 data and data from previous years are presented. The effects of other forms of compensation, such as on‐call compensation, overtime, bonuses, and shift differentials, on base compensation rates also are examined. Additional analyses explore the effect of the current economic downturn on the perioperative work environment.
Insular volume abnormalities associated with different transition probabilities to psychosis
Authors: Smieskova R. , Fusar-Poli P. , Aston J. , Simon A. , Bendfeldt K. , Lenz C. , Stieglitz R.-D. , McGuire P. , Riecher-Rössler A. , Borgwardt S. J.
Published: December 2011

Background

Although individuals vulnerable to psychosis show brain volumetric abnormalities, structural alterations underlying different probabilities for later transition are unknown. The present study addresses this issue by means of voxel-based morphometry (VBM).

Method

We investigated grey matter volume (GMV) abnormalities by comparing four neuroleptic-free groups: individuals with first episode of psychosis (FEP) and with at-risk mental state (ARMS), with either long-term (ARMS-LT) or short-term ARMS (ARMS-ST), compared to the healthy control (HC) group. Using three-dimensional (3D) magnetic resonance imaging (MRI), we examined 16 FEP, 31 ARMS, clinically followed up for on average 3 months (ARMS-ST, n=18) and 4.5 years (ARMS-LT, n=13), and 19 HC.

Results

The ARMS-ST group showed less GMV in the right and left insula compared to the ARMS-LT (Cohen's d 1.67) and FEP groups (Cohen's d 1.81) respectively. These GMV differences were correlated positively with global functioning in the whole ARMS group. Insular alterations were associated with negative symptomatology in the whole ARMS group, and also with hallucinations in the ARMS-ST and ARMS-LT subgroups. We found a significant effect of previous antipsychotic medication use on GMV abnormalities in the FEP group.

Conclusions

GMV abnormalities in subjects at high clinical risk for psychosis are associated with negative and positive psychotic symptoms, and global functioning. Alterations in the right insula are associated with a higher risk for transition to psychosis, and thus may be related to different transition probabilities.
Integrating rising powers: liberal systemic theory and the mechanism of competition
Authors: SNYDER QUDDUS Z.
Published: December 2011

Why have non-Western powers, such as China, pursued a grand strategy of commercial integration into the liberal system? In developing a general theory of competitive pressure, this article builds upon a growing body of literature that seeks to develop a liberal systemic theory. Powerful network externalities – system-level pressures and incentives – have emerged as a by-product of the highly integrated liberal core. Outsiders have been moved by an interest in accessing these network benefits as well as a fear of falling behind in the struggle for relative power. In a plausibility probe, the article explores China's decision to join the world.
The hitchhiker's guide to E. coli
Authors: Jacobs Howy
Published: December 2011

The threat posed by pathogenic strains of E. coli hit the headlines around the globe last summer. Howy argues that a wider perspective is needed, to combat this and similar dangers to public health. The ‘reputation’ of a much‐valued experimental organism is also at stake.
Intensity and Duration of Obesity‐Related Counseling: Association With 5‐Year BMI Trends Among Obese Primary Care Patients
Authors: Noël Polly H. , Wang Chen‐Pin , Bollinger Mary J. , Pugh Mary J. , Copeland Laurel A. , Tsevat Joel , Nelson Karin M. , Dundon Margaret M. , Hazuda Helen P.
Published: December 2011

We examined 5‐year trends in BMI among obese primary care patients to determine whether obesity‐related education such as nutrition counseling or a weight management program was associated with declines in BMI. Veterans with BMI ≥30 kg/m2 and ≥1 primary care visits in fiscal year 2002 were identified from the Veterans Health Administration's (VHA) national databases. Outpatient visits from fiscal year 2002–2006 for nutrition counseling, exercise, or weight management were grouped into five categories varying in intensity and duration: (i) intense‐and‐sustained, (ii) intense‐only, (iii) irregular, (iv) limited, and (v) no counseling. Generalized estimating equation assessed associations between obesity‐related counseling and BMI trend (annual rate of BMI change fiscal year 2002–2006) among cohort members with complete race/ethnic data (N = 179,881). Multinomial logistic regression compared intensity and duration of counseling among patients whose net BMI increased or decreased by ≥10% vs. remained stable. Compared with patients receiving “intense‐and‐sustained” counseling, the BMI trend of those receiving “intense‐only” or “irregular” counseling was not significantly different, but patients receiving “no counseling” or “limited counseling” had significantly higher rates of decreasing BMI (−0.12 and −0.08 BMI per year; P < 0.01, respectively). This was especially true for veterans in their 50–60s, compared with the oldest veterans who were most likely to lose weight. In contrast, younger veterans (18–35 years) were least likely to lose weight; their BMI tended to increase regardless of counseling intensity and duration. Enhanced efforts are needed to detect and combat increasing weight trajectories among veterans who are already obese, especially among those aged 18–35 who are at greatest risk.
Dissipative particle dynamics at isothermal, isobaric, isoenergetic, and isoenthalpic conditions using Shardlow-like splitting algorithms
Authors: Lísal Martin , Brennan John K. , Avalos Josep Bonet
Published: December 2011

Numerical integration schemes based upon the Shardlow-splitting algorithm (SSA) are presented for dissipative particle dynamics (DPD) approaches at various fixed conditions, including a constant-enthalpy (DPD-H) method that is developed by combining the equations-of-motion for a barostat with the equations-of-motion for the constant-energy (DPD-E) method. The DPD-H variant is developed for both a deterministic (Hoover) and stochastic (Langevin) barostat, where a barostat temperature is defined to satisfy the fluctuation-dissipation theorem for the Langevin barostat. For each variant, the Shardlow-splitting algorithm is formulated for both a velocity-Verlet scheme and an implicit scheme, where the velocity-Verlet scheme consistently performed better. The application of the Shardlow-splitting algorithm is particularly critical for the DPD-E and DPD-H variants, since it allows more temporally practical simulations to be carried out. The equivalence of the DPD variants is verified using both a standard DPD fluid model and a coarse-grain solid model. For both models, the DPD-E and DPD-H variants are further verified by instantaneously heating a slab of particles in the simulation cell, and subsequent monitoring of the evolution of the corresponding thermodynamic variables as the system approaches an equilibrated state while maintaining their respective constant-energy and constant-enthalpy conditions. The original SSA formulated for systems of equal-mass particles has been extended to systems of unequal-mass particles. The Fokker-Planck equation and derivations of the fluctuation-dissipation theorem for each DPD variant are also included for completeness.
Millimeter-wave study of London penetration depth temperature dependence in Ba(Fe0.926Co0.074)2As2 single crystal
Authors: Barannik A. A. , Cherpak N. T. , Ni N. , Tanatar M. A. , Vitusevich S. A. , Skresanov V. N. , Canfield P. C. , Prozorov R. , Glamazdin V. V. , Torokhtii K. I.
Published: December 2011

In-plane surface Ka-band microwave impedance of optimally doped single crystals of the Fe-based superconductor Ba(Fe0.926Co0.074)2As2 (Tc = 22.8 K) was measured. Sensitive sapphire disk quasi-optical resonator with high-Tc cuprate conducting endplates was developed specially for Fe-pnictide superconductors. It allowed finding temperature variation of London penetration depth in a form of power law, namely Δλ(T) ∼ Tn with n = 2.8 from low temperatures up to at least 0.6Tc consisted with radio-frequency measurements. This exponent points towards nodeless state with pairbreaking scattering, which can support one of the extended s-pairing symmetries. The dependence λ(T) at low temperatures is well described by one superconducting small-gap (Δ≅0.75 in kTc units, where k is Boltzmann coefficient) exponential dependence.
Invited Review Article: An odor-sensing system—powerful technique for foodstuff studies
Authors: Dymerski T. M. , Chmiel T. M. , Wardencki W.
Published: December 2011

This work examines gas sensor array technology combined with multivariate data processing methods and demonstrates a promising potential for rapid, non-destructive analysis of food. Main attention is focused on detailed description of sensor used in e-nose instruments, construction, and principle of operation of these systems. Moreover, this paper briefly reviews the progress in the field of artificial olfaction and future trends in electronic nose technology, namely, e-nose based on mass spectrometry. Further discussion concerns a comparison of artificial nose with gas chromatography-olfactometry and the application of e-nose instruments in different areas of food industry.
Structural evolution of implanted vicinal Si(111) during annealing via analysis of the dipole contribution
Authors: Liu Chun-Chu , Liu Chung-Wei , Cheng Jin-Yuan , Huang Yi-Jen , Lo Kuang-Yao
Published: December 2011

The changes in the amplitude and orientation of the dipole at the surface layer of phosphorous (P) implanted vicinal Si(111) show the evolution of its restructuring. The different electronegativities between Si and participated P atoms changed the dipolar configuration of Si surface. The dipolar configuration of implanted vicinal Si(111) would be variant for the different annealing conditions at which silicon recrystallization and P activation occur. Reflective second harmonic generation (RSHG) is a sensitive technique for studying the symmetrical dipole structure on the surface. We offer a model to distinguish dipolar configurations of the top surface from the one of the implanted bulk Si(111) and explain their relative phase variation in the results of RSHG experiment.
Compensator design for improved counterbalancing in high speed atomic force microscopy
Authors: Bozchalooi I. S. , Youcef-Toumi K. , Burns D. J. , Fantner G. E.
Published: December 2011

High speed atomic force microscopy can provide the possibility of many new scientific observations and applications ranging from nano-manufacturing to the study of biological processes. However, the limited imaging speed has been an imperative drawback of the atomic force microscopes. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds, severely undermining the reliability of the acquired images. In this research, we propose a piezo based, feedforward controlled, counter actuation mechanism to compensate for the excited out-of-plane scanner dynamics. For this purpose, the AFM controller output is properly filtered via a linear compensator and then applied to a counter actuating piezo. An effective algorithm for estimating the compensator parameters is developed. The information required for compensator design is extracted from the cantilever deflection signal, hence eliminating the need for any additional sensors. The proposed approach is implemented and experimentally evaluated on the dynamic response of a custom made AFM. It is further assessed by comparing the imaging performance of the AFM with and without the application of the proposed technique and in comparison with the conventional counterbalancing methodology. The experimental results substantiate the effectiveness of the method in significantly improving the imaging performance of AFM at high scan speeds.
Lumping analysis for the prediction of long-time dynamics: From monomolecular reaction systems to inherent structure dynamics of glassy materials
Authors: Lempesis Nikolaos , Tsalikis Dimitrios G. , Boulougouris Georgios C. , Theodorou Doros N.
Published: December 2011

In this work we develop, test, and implement a methodology that is able to perform, in an automated manner, “lumping” of a high-dimensional, discrete dynamical system onto a lower-dimensional space. Our aim is to develop an algorithm which, without any assumption about the nature of the system's slow dynamics, is able to reproduce accurately the long-time dynamics with minimal loss of information. Both the original and the lumped systems conform to master equations, related via the “lumping” analysis introduced by Wei and Kuo [Ind. Eng. Chem. Fundam. 8, 114 (1969)], and have the same limiting equilibrium probability distribution. The proposed method can be used in a variety of processes that can be modeled via a first order kinetic reaction scheme. Lumping affords great savings in the computational cost and reveals the characteristic times governing the slow dynamics of the system. Our goal is to approach the best lumping scheme with respect to three criteria, in order for the lumped system to be able to fully describe the long-time dynamics of the original system. The criteria used are: (a) the lumping error arising from the reduction process; (b) a measure of the magnitude of singular values associated with long-time evolution of the lumped system; and (c) the size of the lumped system. The search for the optimum lumping proceeds via Monte Carlo simulation based on the Wang-Landau scheme, which enables us to overcome entrapment in local minima in the above criteria and therefore increases the probability of encountering the global optimum. The developed algorithm is implemented to reproduce the long-time dynamics of a glassy binary Lennard-Jones mixture based on the idea of “inherent structures,” where the rate constants for transitions between inherent structures have been evaluated via hazard plot analysis of a properly designed ensemble of molecular dynamics trajectories.
Cliff-like conduction band offset and KCN-induced recombination barrier enhancement at the CdS/Cu2ZnSnS4 thin-film solar cell heterojunction
Authors: Bär M. , Schubert B.-A. , Marsen B. , Wilks R. G. , Pookpanratana S. , Blum M. , Krause S. , Unold T. , Yang W. , Weinhardt L. , Heske C. , Schock H.-W.
Published: December 2011

The electronic structure of the CdS/Cu2ZnSnS4 (CZTS) heterojunction was investigated by direct and inverse photoemission. The effects of a KCN etch of the CZTS absorber prior to CdS deposition on the band alignment at the respective interface were studied. We find a “cliff”-like conduction band offset at the CdS/CZTS interface independent of absorber pretreatment and a significant etch-induced enhancement of the energetic barrier for charge carrier recombination across the CdS/CZTS interface.
Adsorption and dissociation of NO on Ir(100): A first-principles study
Authors: He Chao-zheng , Wang Hui , Zhu Peng , Liu Jing-yao
Published: December 2011

Density functional theory (DFT) and periodic slab model have been used to systemically study the adsorption and dissociation of NO and the formation of N2 on the Ir(100) surface. The results show that NO prefers the bridge site with the N-end down and NO bond-axis perpendicular to the Ir surface, and adsorption to the top site is only 0.05 eV less favorable, whereas the hollow adsorption is the least stable. Two dissociation pathways for the adsorbed NO on bridge or top site are located: One is a direct decomposition of NO and the other is diffusion of NO from the initial state to the hollow site followed by dissociation into N and O atoms. The latter pathway is more favorable than the former one due to the lower energy barrier and is the primary pathway for NO dissociation. Based on the DFT results, microkinetic analysis suggests that the recombination of two N adatoms on the di-bridge sites is the predominant pathway for N2 formation, whereas the formation of N2O or NO2 is unlikely to occur during NO reduction. The high selectivity of Ir(100) toward N2 is in good agreement with the experimental observations.
Confined linear molecules inside an aperiodic supramolecular crystal: The sequence of superspace phases in n-hexadecane/urea
Authors: Huard M. , Toudic B. , Rabiller P. , Ecolivet C. , Guérin L. , Bourges P. , Breczewski T. , Hollingsworth Mark D.
Published: December 2011

High-resolution studies of the host-guest inclusion compound n-hexadecane/urea are reported at atmospheric pressure, using both cold neutrons and x-ray diffraction. This intergrowth crystal presents a misfit parameter, defined by the ratio ch/cg (chost/cguest), which is temperature independent and irrational (γ = 0.486 ± 0.002) from 300 to 30 K. Three different structural phases are reported for this aperiodic crystal over this temperature range. The crystallographic superspaces are of rank 4 in phases I and II, whereas phase III is associated with an increase in rank to 5, with a supplementary misfit parameter (δ = 0.058 ± 0.002) that is constant throughout this phase. The superspace group of phase I is hexagonal P6122(00γ) down to Tc1 = 149.5 ± 0.5 K; phase II, which persists down to Tc2 = 127.8 ± 0.5 K is orthorhombic P212121(00γ), and phase III is orthorhombic P212121(00γ)(00δ).
Rotational positioning system adapted to atomic force microscope for measuring anisotropic surface properties
Authors: Liao H.-S. , Juang B.-J. , Chang W.-C. , Lai W.-C. , Huang K.-Y. , Chang C.-S.
Published: December 2011

The diverse atomic configurations induce the anisotropic surface properties. For investigating anisotropic phenomena, we developed a rotational positioning system adapted to atomic force microscope (AFM). This rotational positioning system is applied to revolve the measured sample to defined angular direction, and it composed of an inertial rotational stepper and a visual angular measurement. The inertial rotational stepper with diameter 30 mm and height 7.6 mm can be easily attached to the AFM-system built in any general optical microscope. Based on a clearance less bearing and the inertial driving method, its bidirectional angular resolution reaches 0.005° per step. For realizing a close-loop controlled angular positioning function, the visual measurement method is utilized. Through the feedback control, the angular positioning error is less than 0.01°. For verifying the system performance, we used it to investigate the anisotropic surface properties of graphite. Through a modified cantilever tip, the atomic-scale stick-slip, and the anisotropic friction phenomena can be distinctly detected.
Optofluidic membrane interferometer: An imaging method for measuring microfluidic pressure and flow rate simultaneously on a chip
Authors: Song Wuzhou , Psaltis Demetri
Published: December 2011

We present a novel image-based method to measure the on-chip microfluidic pressure and flow rate simultaneously by using the integrated optofluidic membrane interferometers (OMIs). The device was constructed with two layers of structured polydimethylsiloxane (PDMS) on a glass substrate by multilayer soft lithography. The OMI consists of a flexible air-gap optical cavity which upon illumination by monochromatic light generates interference patterns that depends on the pressure. These interference patterns were captured with a microscope and analyzed by computer based on a pattern recognition algorithm. Compared with the previous techniques for pressure sensing, this method offers several advantages including low cost, simple fabrication, large dynamic range, and high sensitivity. For pressure sensing, we demonstrate a dynamic range of 0-10 psi with an accuracy of ±2% of full scale. Since multiple OMIs can be integrated into a single chip for detecting pressures at multiple locations simultaneously, we also demonstrated a microfluidic flow sensing by measuring the differential pressure along a channel. Thanks to the simple fabrication that is compatible with normal microfluidics, such OMIs can be easily integrated into other microfluidic systems for in situ fluid monitoring.
The influence of charged InAs quantum dots on the conductance of a two-dimensional electron gas: Mobility vs. carrier concentration
Authors: Marquardt B. , Beckel A. , Lorke A. , Wieck A. D. , Reuter D. , Geller M.
Published: December 2011

Using time-resolved transport spectroscopy, we investigate the influence of charge-tunable InAs quantum dots (QDs) on the conductance of a nearby two-dimensional electron gas (2DEG). Loading successively electrons into the self-assembled QDs decreases the carrier concentration and mobility in the 2DEG. We are able to quantify how these transport properties change for each additional charge in the s- or p-shell. It is found that mobility and carrier concentration contribute equally to the overall change in conductance.
Low-temperature graphene growth using epochal catalyst of PdCo alloy
Authors: Kim Eun Sung , Shin Hyeon-Jin , Yoon Seon-Mi , Han Gang Hee , Chae Seung Jin , Bae Jung Jun , Gunes Fethullah , Choi Jae-Young , Lee Young Hee
Published: December 2011

Palladium-Cobalt alloy as a catalyst was introduced to realize low temperature graphene growth on glass substrate by using remote RF plasma-enhanced chemical vapor deposition. Few layer graphene films were easily formed with high transmittance of 88.8% at temperature as low as 400 °C, in good contrast with Ni catalyst in which no graphitic layer was formed at all at the same conditions. High decomposition rate of hydrocarbon gases and formation of nanosize aggregates giving rise to enhancement of carbon incorporation into PdCo alloy and consequently formation of graphene layers at such low temperatures are further discussed with observed Raman spectroscopy and x-ray diffraction.
Electro-optical response of the combination of two twisted nematic liquid crystal cells in series and the applicability of the extended Jones matrix
Authors: Sinha Subhojyoti , Chatterjee Sanat Kumar , Meikap Ajit Kumar
Published: December 2011

A typical electro-optical response is observed by connecting two twisted nematic liquid crystal cells in series and placed back to back such that the director orientation on the back glass substrate of the first cell coincides with the director orientation of the front glass substrate of the second cell and vice versa. The two cells connected in series show cholesteric rotation. It is observed that for a given frequency the output transmittance oscillates having distinct maxima and minima with varying voltage and no flickering of transmittance have been observed at low frequencies. Variation of transmittance with frequency for given voltages is also reported and it has been found that increase of voltage at high frequency does not alter the transmittance appreciably. A discussion on the extended Jones matrix formulation and the scope of its applicability for this case is also given.