bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of the Tgfβ2 Gene During Chick Embryogenesis
Authors: Yamagishi Toshiyuki , Ando Katsumi , Nakamura Hiroaki , Nakajima Yuji
Published: December 2011

We performed a comprehensive analysis of the expression of transforming growth factor (TGF) β2 during chick embryogenesis from stage 6 to 30 (Hamburger and Hamilton, J Morphol 1951;88:49–92) using in situ hybridization. During cardiogenesis, Tgfβ2 was expressed in the endothelial/mesenchymal cells of the valvulo‐septal endocardial cushion tissue and in the epicardium until the end of embryogenesis. During the formation of major arteries, Tgfβ2 was localized in smooth muscle progenitors but not in the vascular endothelium. During limb development, Tgfβ2 was expressed in the mesenchymal cells in the presumptive limb regions at stage 16, and thereafter it was localized in the skeletal muscle progenitors. In addition, strong Tgfβ2 expression was seen in the mesenchymal cells in the pharyngeal arches. Tgfβ2 mRNA was also detected in other mesoderm‐derived tissues, such as the developing bone and pleura. During ectoderm development, Tgfβ2 was expressed in the floor plate of the neural tube, lens, optic nerve, and otic vesicle. In addition, Tgfβ2 was expressed in the developing gut epithelium. Our results suggest that TGFβ2 plays an important role not only in epithelial‐mesenchymal interactions but also in cell differentiation and migration and cell death during chick embryogenesis. We also found that chick and mouse Tgfβ2 RNA show very similar patterns of expression during embryogenesis. Chick embryos can serve as a useful model to increase our understanding in the roles of TGFβ2 in cell–cell interactions, cell differentiation, and proliferation during organogenesis. Anat Rec, 2012. © 2011 Wiley Periodicals, Inc.
Towards Quantitative Computer‐Aided Studies of Enzymatic Enantioselectivity: The Case of Candida antarctica Lipase A
Authors: Frushicheva Maria P. , Warshel Arieh
Published: December 2011

The prospect for consistent computer‐aided refinement of stereoselective enzymes is explored by simulating the hydrolysis of enantiomers of an α‐substituted ester by wild‐type and mutant Candida antarctica lipase A, using several strategies. In particular, we focused on the use of the empirical valence bond (EVB) method in a quantitative screening for enantioselectivity, and evaluate both kcat and kcat/KM of the R and S stereoisomers. We found that an extensive sampling is essential for obtaining converging results. This requirement points towards possible problems with approaches that use a limited conformational sampling. However, performing the proper sampling appears to give encouraging results and to offer a powerful tool for the computer‐aided design of enantioselective enzymes. We also explore faster strategies for identifying mutations that will help in augmenting directed‐evolution experiments, but these approaches require further refinement.
Major Groove Substituents and Polymerase Recognition of a Class of Predominantly Hydrophobic Unnatural Base Pairs
Authors: Lavergne Thomas , Malyshev Denis A. , Romesberg Floyd E.
Published: December 2011

Expansion of the genetic alphabet with an unnatural base pair is a long‐standing goal of synthetic biology. We have developed a class of unnatural base pairs, formed between d5SICS and analogues of dMMO2 that are efficiently and selectively replicated by the Klenow fragment (Kf) DNA polymerase. In an effort to further characterize and optimize replication, we report the synthesis of five new dMMO2 analogues bearing different substituents designed to be oriented into the developing major groove and an analysis of their insertion opposite d5SICS by Kf and Thermus aquaticus DNA polymerase I (Taq). We also expand the analysis of the previously optimized pair, dNaM–d5SICS, to include replication by Taq. Finally, the efficiency and fidelity of PCR amplification of the base pairs by Taq or Deep Vent polymerases was examined. The resulting structure–activity relationship data suggest that the major determinants of efficient replication are the minimization of desolvation effects and the introduction of favorable hydrophobic packing, and that Taq is more sensitive than Kf to structural changes. In addition, we identify an analogue (dNMO1) that is a better partner for d5SICS than any of the previously identified dMMO2 analogues with the exception of dNaM. We also found that dNaM–d5SICS is replicated by both Kf and Taq with rates approaching those of a natural base pair.
Copper‐Catalyzed One‐Pot Synthesis of Imidazo/Benzoimidazoquinazolinones by Sequential Ullmann‐Type Coupling and Intramolecular CH Amidation
Authors: Xu Hao , Fu Hua
Published: December 2011

A simple, practical, and highly efficient copper‐catalyzed one‐pot synthesis of imidazo/benzoimidazoquinazolinones has been developed. The procedure is based on a sequential copper‐catalyzed Ullmann‐type N‐arylation and aerobic oxidative intramolecular CH amidation. This method should provide a new and useful strategy for construction of N‐heterocycles.
Design of Nanocatalysts for Green Hydrogen Production from Bioethanol
Authors: Bion Nicolas , Duprez Daniel , Epron Florence
Published: December 2011

Bioethanol is an interesting feedstock that may be used for hydrogen production by steam or autothermal reforming. However, the impurities (heavy alcohols, esters, acids, N compounds) contained in the raw feedstock require a costly purification, as they have a dramatic impact on catalyst activity and stability. Thus, a method that can utilize the raw feedstock without severe degradation of the catalyst would be desirable. In this Minireview, the composition of bioethanol from first and second generation biomass, the reactions involved in the catalytic ethanol steam reforming process and the design of catalysts adapted for hydrogen production from a real bioethanol feed are surveyed.
Adaptive frequency compensation for maximum and constant bandwidth feedback amplifiers
Authors: Pennisi Salvatore , Scotti Giuseppe , Trifiletti Alessandro
Published: December 2011

We present an adaptive frequency compensation technique providing maximum bandwidth closed‐loop amplifiers. The approach exploits an auxiliary variable gain amplifier to implement an electrically tunable compensation capacitor proportional to the feedback factor. In this manner, the closed‐loop bandwidth is kept ideally constant irrespective of the closed‐loop gain. The proposed method can be applied to any amplifier adopting dominant‐pole compensation. As an example, we designed a CMOS amplifier providing 66‐dB direct current gain and 310‐MHz gain‐bandwidth product. For closed‐loop gains ranging from 1 to 10, the closed‐loop bandwidth was found never lower than 401 MHz (noinverting configuration) and 229 MHz (inverting configuration). A similar amplifier with equal gain‐bandwidth product, but adopting the traditional fixed compensation approach, would exhibit a closed‐loop bandwidth reduced to 33 MHz (noninverting) and 30 MHz (inverting) when the gain magnitude is set to 10. The enhanced frequency performance is obtained with a 48% increase in current consumption, whereas the other main operational amplifier performance parameters remain almost unchanged compared with the standard solution. Copyright © 2011 John Wiley & Sons, Ltd.
Characterization of the G‐protein‐coupled membrane‐bound estrogen receptor GPR30 in the zebra finch brain reveals a sex difference in gene and protein expression
Authors: Acharya Kalpana D. , Veney Sean L.
Published: December 2011

Estradiol‐induced structural dimorphisms exist in the songbird brain. However, how they arise is not clear since there is a scarce distribution of ERα and lack of ERβ in song control nuclei. This suggests that other receptors are involved. The G‐protein coupled membrane‐bound estrogen receptor, GPR30, is a candidate but has never been investigated in songbirds. In this study, we characterized its gene and protein in the zebra finch brain. Analysis of the putative GPR30 protein sequence revealed a strong similarity to avian and mammalian homologues. Quantitative PCR indicated that the gene was elevated in the telencephalon of both sexes from posthatching day (P) 15 to P45, with a male‐biased sex difference at P21 and P30. In comparison, expression at younger posthatching ages and in adults was significantly less. At P21, GRP30 protein was widespread, nonuniform, and overlapped with song control nuclei. Of particular interest, the number of immunoreactive cells was greatest in HVC and RA, but less in LMAN and Area X. Labeling in HVC was also dimorphic; with more cells present in males than in females. In parallel with the gene, by adulthood, protein expression was reduced across most brain regions. Taken together these data suggest that GPR30 may contribute to differences in song system development by mediating dimorphic responses to estrogens. In addition, the extensive protein distribution indicates that it may also have a role in general brain development in both sexes. © 2011 Wiley Periodicals, Inc. Develop Neurobiol, 2012
Ruthenium Acetate Complexes as Versatile Probes of Metal–Ligand Interactions: Insight into the Ligand Effects of Vinylidene, Carbene, Carbonyl, Nitrosyl and Isocyanide
Authors: Welby Christine E. , Eschemann Thomas O. , Unsworth Christopher A. , Smith Elizabeth J. , Thatcher Robert J. , Whitwood Adrian C. , Lynam Jason M.
Published: December 2011

Reaction of cis‐Ru(κ2‐OAc)2(PPh3)2 with two‐electron donor ligands L results in the formation of complexes trans‐[Ru(κ1‐OAc)(κ2‐OAc)L(PPh3)2] (L = CO, NO+, CNtBu). Vinylidene complexes (L = C=CHR) may be prepared from the corresponding reaction with terminal alkynes HC≡CR, and species containing hydroxyvinylidene ligands (L = C=CHCR1R2{OH}) may be prepared from related reactions with propargyl alcohols HC≡CCR1R2{OH}. Treatment of cis‐Ru(κ2‐OAc)2(PPh3)2 with ω‐alkynols HC≡C(CH2)nOH (n = 2–4) results in the formation of oxacyclocarbene complexes [L = CCH2(CH2)nO]. An analysis of the spectroscopic data and the structural metrics (as determined by X‐ray crystallography) of this series of complexes allows for the relative donor/acceptor properties of the ligand L to be evaluated. This comparison indicates that the vinylidene ligand behaves in a similar fashion to the isocyanide ligand.
Synthesis of Paullone and Kenpaullone Derivatives by Photocyclization of 2‐(2‐Chloro‐1H‐indol‐3‐yl)‐N‐arylacetamides
Authors: Li Zhanshan , Lu Nianhong , Wang Lihong , Zhang Wei
Published: December 2011

An efficient synthesis of paullone and kenpaullone derivatives in moderate to high yields has been achieved through photocyclizations of (2‐chloro‐1H‐indole‐3‐yl)‐N‐arylacetamides in acetone at room temperature. Paullone and kenpaullone have been obtained easily and in high yields by deprotection of the photocyclization products.
Acting prosocially reduces retaliation: Effects of prosocial video games on aggressive behavior
Authors: Greitemeyer Tobias , Agthe Maria , Turner Robin , Gschwendtner Christina
Published: December 2011

Past research has provided abundant evidence that exposure to violent video games increases aggression and aggression‐related variables. In contrast, little is known whether and why video game exposure may also decrease aggressive behavior. In fact, two experiments revealed that playing a prosocial (relative to a neutral) video game reduces aggressive behavior. Mediational analyses showed that differences in both aggressive cognition and aggressive affect underlie the effect of type of video game on aggressive behavior. These findings are in line with assumptions of the General Learning Model and point to the importance of the cognitive and affective routes in predicting how aggressive behavior is affected by exposure to video games. Copyright © 2011 John Wiley & Sons, Ltd.
Reproductive development of yellow perch (Perca flavescens) exposed to oil sands–affected waters
Authors: van den Heuvel Michael R. , Hogan Natacha S. , Roloson Scott D. , Van Der Kraak Glen J.
Published: December 2011

In similar experiments conducted in 1996 and 2009, yellow perch (Perca flavescens) were stocked into two experimental systems: a demonstration lake where oil sands fine tailings were capped with natural water and a lake in a watershed containing bitumen-bearing sodic clays. In both experiments, yellow perch were captured in May from a nearby reservoir and released into the experimental ponds. Perch were recaptured in the experimental systems, the source lake, and two reference lakes in late September and lethally sampled to examine reproductive parameters. In the 1996 experiment, gonad size and steroid hormones were not affected in either pond environment. In the 2009 experiment, male perch in the water-capped tailings pond showed a significant reduction in the testicular development and reductions in circulating testosterone and 11-ketotestosterone, while no reductions were seen in the second experimental pond. No changes were observed in ovarian size or circulating steroid levels in female perch. In the pond containing tailings, the release of water from underlying tailings caused approximately a twofold increase in salinity, alkalinity, and naphthenic acids, and a pH increase from 8.4 to 9.4 over the 13-year period of the study. In the pond influenced by unextracted oil sands materials, total dissolved solids, major ions, and pH did not change substantially. However, naphthenic acids in this system dropped more than twofold post–watershed reclamation. Because the selective reproductive effect observed in male perch in the experimental end-pit lake were accompanied by increases in naphthenic acids, alkalinity, and pH, a specific cause cannot be determined. The present study adds to the evidence, suggesting the presence of endocrine-disrupting substances in oil sands. Environ. Toxicol. Chem. 2012;31:654–662. © 2011 SETAC
Analytical and Chebyshev pseudospectral numerical solutions for a class of axisymmetric horizontal flows dominated by mass or heat sources
Authors: Mohammadian M. , Charron M.
Published: December 2011

A class of axisymmetric horizontal flows dominated by strong heat or mass sources are considered here, which systematically arise in multiscale atmospheric and oceanic flows in various spatiotemporal scales such as hurricane embryos. Various linear and nonlinear analytical solutions are proposed, and several examples are given to illustrate them. On the basis of the proposed exact solutions, stability of the flow under various conditions is examined. The proposed exact solutions serve as benchmarks for validation of numerical models. A Chebyshev pseudospectral model is also developed for these flows. The numerical results are compared with the developed analytical solutions as well as a high‐resolution numerical solution, which showed an excellent performance of the numerical model in terms of numerical diffusion and oscillation. The numerical method is also efficient because expensive calculations such as LU decomposition are only needed once, at the beginning of calculations. The model could be used in studying small‐scale and multiple‐scale phenomena such as hot towers and hurricane embryos, which are the subject of future studies. Copyright © 2011 John Wiley & Sons, Ltd.
The use of cluster analysis in typological research on community college students
Authors: Bahr Peter Riley , Bielby Rob , House Emily
Published: December 2011

This chapter provides an introduction to the family of partitional cluster analytical methods, with specific attention to research on community college students. Key decision points and common approaches in the use of cluster analysis are described.
A new mechanism of oxidation in ultrahigh molecular weight polyethylene caused by squalene absorption
Authors: Oral Ebru , Ghali Bassem W. , Neils Andrew , Muratoglu Orhun K.
Published: December 2011

Although synovial fluid lipids were found to absorb in ultrahigh molecular weight polyethylene (UHMWPE) total joint implants in vivo, their effect on the oxidation of the polymer was not known. Current understanding of the oxidation and oxidative stability of UHMWPE joint implants is focused on the presence or elimination of radiation‐induced free radicals, which are long‐lived and can react with oxygen over the long term. Recently, we found unexplained oxidation in irradiated and melted UHMWPE components that were exposed to bodily fluids then stored on the shelf despite being free of detectable free radicals at the time of implantation. Thus, we hypothesized that lipids absorbed from the synovial fluid in vivo could initiate and accelerate oxidation of UHMWPE even in the absence of detectable residual free radicals. We found that squalene, a precursor in cholesterol synthesis and a synovial fluid lipid with unsaturated bonds, accelerated oxidation in irradiated and melted UHMWPE under in vitro accelerated aging conditions. This result represents a paradigm shift in our understanding of oxidative stability of UHMWPE and prompts further investigation of in vivo oxidation mechanisms as well as the development of relevant in vitro aging models. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Hunting goodwill: Personal goodwill as property in corporate acquisitions
Authors: Bean LuAnn
Published: December 2011

In today's economy, it's more important than ever to examine the tax planning strategies for any corporate acquisition. Poor tax planning for goodwill acquired in an unwise acquisition can lead to a loss in value overnight! And if that happens, a company may have to write it off against earnings. In the worst case, a company might have to write off most, if not all, of its goodwill.

So as more acquisitions of closely held entities occur, it's increasingly important to separate the intangible value of a company into enterprise goodwill versus personal goodwill. But it's a difficult challenge. What techniques or strategies will help?

This article has some answers. The author reveals the importance of the treatment of personal goodwill versus enterprise goodwill—for both the seller and the buyer. And the author also examines factors that should be considered when structuring such an acquisition. © 2012 Wiley Periodicals, Inc.
Duration of venous thromboembolism risk across a continuum in medically ill hospitalized patients
Authors: Amin Alpesh N. , Varker Helen , Princic Nicole , Lin Jay , Thompson Stephen , Johnston Stephen
Published: December 2011

BACKGROUND:

Patients hospitalized for medical illness are at increased risk of venous thromboembolism (VTE), but the duration of risk is not well understood.

OBJECTIVE:

To assess incidence and time course of symptomatic VTE following hospitalization for medical illness in a large, real‐world patient population.

DESIGN:

Data were extracted from the Thomson Reuters MarketScan® Inpatient Drug Link File.

PATIENTS:

Those hospitalized with cancer, heart failure, severe lung disease, or infectious disease from 2005 to 2008.

MEASUREMENTS:

The cumulative VTE risk over 180 days after admission was calculated using Kaplan‐Meier analysis. VTE hazard was calculated on a daily basis and smoothed through LOESS regression.

RESULTS:

The analysis included 11,139 medically ill patients, 46.7% and 8.8% of whom received pharmacological thromboprophylaxis during hospitalization and after discharge, respectively. The mean duration of prophylaxis during hospitalization was 5.0 days. Of the 11,139 patients, 366 (3.3%) experienced a symptomatic VTE event. VTE events were most frequent during days 0‐9 (97 events), followed by days 10‐19 (82 events). The mean length of hospital stay was 5.3 days, and 56.6% of all VTE events occurred after discharge. VTE hazard peaked at day 8, with 1.05 events per 1000 person‐days.

CONCLUSIONS:

The time course of VTE in medical patients shows that risk of symptomatic VTE is highest during the first 19 days after hospital admission, and extends into the period after discharge. Future research is warranted to investigate risks and benefits of reducing the incidence of VTE after discharge, including the role of improving thromboprophylaxis practices in the inpatient setting and extending thromboprophylaxis after hospitalization. Journal of Hospital Medicine 2012;. © 2011 Society of Hospital Medicine
Why surgeons can say “No”: Exploring “Unilateral Withholding”
Authors: Manthous Constantine A. , Ivy Michael
Published: December 2011

OBJECTIVE:

To explore why it is permissible for surgeons to “unilaterally withhold” surgery, whereas it is not commonplace (in the United States) to unilaterally withhold cardiopulmonary resuscitation (CPR) for clinical situations with similar degrees of uncertainty and prognosis.

DATA SOURCES:

The medical literature was sampled using PubMed and Google search engines, employing a variety of search strategies to capture articles relating to medical/surgical decision‐making, risk aversion, acute care surgery, and withholding life‐saving therapies. These topics are used to highlight interprovider variability that affects all practitioners—not just surgeons—and to consider why we deem it permissible for surgeons to withhold surgery, whereas—in the United States, at least—it is not routinely permissible for clinicians to unilaterally withhold mechanical ventilation and CPR for cases with similar prognoses.

CONCLUSIONS:

While there are no published research studies that deal directly with this topic, knowledge, heuristics, experience, variable aversion to risk, and other features inherent in medical‐surgical education likely impact decisions to offer or withhold potentially life‐saving therapies of all kinds. Both surgeons and clinicians, who request surgical consultation for hospitalized patients, should consider these issues and politely pursue second opinions when there is any doubt whether forgoing surgery is in the patient's best interests. Similarly, while unilateral withholding of CPR is not commonly employed in some medical cultures, including the United States, beneficence can be facilitated through robust informed consent. Journal of Hospital Medicine 2012; © 2011 Society of Hospital Medicine
A multi‐sensor study of water vapour from radiosonde, MODIS and AERONET: a case study of Hong Kong
Authors: Liu Zhizhao , Wong Man Sing , Nichol Janet , Chan P. W.
Published: December 2011

Water vapour is one of green house gases (GHG) and a key parameter affecting weather forecasting. Situated on the edge of the South China Sea and in the path of the wet Asian monsoon, Hong Kong experiences more rainstorms than most other cities. An accurate observation of water vapour has a special significance in severe weather prediction for Hong Kong, one of the cities with the highest density of population in the world. In this paper, water vapour observations over the last 6 years from an AErosol RObotic NETwork (AERONET) sunphotometer, 9 years from the MODerate resolution Imaging Spectroradiometer (MODIS) TERRA satellite images and 38 years from radiosonde were analysed and cross‐validated. The operational MODIS water vapour products, namely MOD05 and MOD07, with a spatial resolution of 1 and 5 km, respectively, were compared with both radiosonde and AERONET data. The correlation coefficients between MODIS water vapour products and radiosonde data are r = 0.878 and 0.876 for MOD05 and MOD07 products, and the correlations of those with AERONET data are r = 0.822, r = 0.976, respectively. The results also indicate that radiosonde and AERONET water vapour observations have a good agreement, with a correlation of r = 0.988 and a small mean absolute difference (MAD), and root mean square error (RMS) of 0.197 and 0.289 cm, respectively. Although the satellite data (with a frequency of once per day) represent water vapour coverage of all the territories of Hong Kong, they do not meet short‐term weather prediction demand due to their low temporal resolution. Radiosonde observations with a frequency of twice per day are also temporally inadequate. This study demonstrates that the AERONET sunphotometer can provide accurate and high temporal resolution water vapour data which can be used for short‐term weather prediction and long‐term climate change research. Copyright © 2011 Royal Meteorological Society
Perturbation Theory of Polymer Chains Revisited, 2—Intermolecular Excluded Volume of Random and Self‐Avoiding Walks
Authors: Zifferer Gerhard , Olaj Oskar Friedrich
Published: December 2011

The intermolecular compatibility of 107–108 independent pair configurations of linear chains (chain length 64 ≤ N ≤ 8192) with and without intramolecular interaction on various lattices is checked and the intermolecular excluded volume u evaluated. From the (average) number of possible i‐tuples of overlaps in the pair configurations the parameters Ck of the perturbation theory are calculated. Differences between the various lattice types at finite N vanish completely for N → ∞. While the theoretical values of C1 and C2 were recovered within very narrow limits for chains without intramolecular interaction, markedly higher figures apply to self‐avoiding walks. The excluded volume u itself and higher Ck parameters are called upon to test several classical and renormalized perturbation theories.

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Efficient sampling of early signal arrival for estimation of perfusion and transit time in whole‐brain arterial spin labeling
Authors: Lee Wayne , Janik Rafal , Scouten Amy , Stefanovic Bojana , Sled John G.
Published: December 2011

Arterial spin labeling can be used to measure both cerebral perfusion and arterial transit time. However, accurate estimation of these parameters requires adequate temporal sampling of the arterial spin labeling difference signal. In whole‐brain multislice acquisitions, two factors reduce the accuracy of the parameter estimates: saturation of labeled blood in transit and inadequate sampling of early difference signal in superior slices. Label saturation arises when slices are acquired inferior‐to‐superior such that slice selection in proximal slices spoils the label for a distal slice. Inadequate sampling arises when the time spent acquiring inferior slices is too long to allow early sampling of the difference signal in superior slices. A novel approach to multislice imaging is proposed to address these two issues. In round‐robin arterial spin labeling, slices are acquired in a different order after every pair of control‐label acquisitions. Round‐robin arterial spin labeling enables the acquisitions of all slices across the same range of postlabel delays in a descending superior‐to‐inferior order. This eliminates the temporal sampling problem and greatly reduces label saturation. Arterial transit time estimates obtained for the whole brain with round‐robin arterial spin labeling show better agreement with a single‐slice acquisition than do conventional multislice acquisitions. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Myocardial perfusion acquisition without magnetization preparation or gating
Authors: DiBella Edward V. R. , Chen Liyong , Schabel Matthias C. , Adluru Ganesh , McGann Chris J.
Published: December 2011

Current myocardial perfusion MRI acquisitions are performed with a saturation recovery sequence, in large part to minimize sensitivity to arrhythmia. A new approach is proposed here where the images are acquired ungated at steady state without use of a saturation pulse. The data are acquired continuously and reach steady state after the first few images. A confluence of advances has made this new paradigm of an ungated steady‐state acquisition possible—very rapid undersampled readouts with new reconstruction technologies permit enough measurements that continuous acquisition becomes a feasible approach. Gating can be applied retrospectively from a logged electrocardiogram (ECG) or with self‐gating methods. In this work, simulations and measurements in a concentration phantom are used to demonstrate that similar contrast and signal can be obtained with the standard saturation recovery and the proposed spoiled gradient echo (SPGR) acquisition. Specifically, for a flip angle of 14° and a saturation recovery time of 80 ms, similar signals are acquired over a range of T1s that reflect realistic myocardial tissue concentrations. Preliminary results in one subject are presented to show the potential of this new approach. The method may allow for cine cardiac perfusion and more signal‐to‐noise ratio‐efficient acquisitions. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Null space imaging: Nonlinear magnetic encoding fields designed complementary to receiver coil sensitivities for improved acceleration in parallel imaging
Authors: Tam Leo K. , Stockmann Jason P. , Galiana Gigi , Constable R. Todd
Published: December 2011

To increase image acquisition efficiency, we develop alternative gradient encoding strategies designed to provide spatial encoding complementary to the spatial encoding provided by the multiple receiver coil elements in parallel image acquisitions. Intuitively, complementary encoding is achieved when the magnetic field encoding gradients are designed to encode spatial information where receiver spatial encoding is ambiguous, for example, along sensitivity isocontours. Specifically, the method generates a basis set for the null space of the coil sensitivities with the singular value decomposition and calculates encoding fields from the null space vectors. A set of nonlinear gradients is used as projection imaging readout magnetic fields, replacing the conventional linear readout field and phase encoding. Multiple encoding fields are used as projections to capture the null space information, hence the term null space imaging. The method is compared to conventional Cartesian SENSitivity Encoding as evaluated by mean squared error and robustness to noise. Strategies for developments in the area of nonlinear encoding schemes are discussed. The null space imaging approach yields a parallel imaging method that provides high acceleration factors with a limited number of receiver coil array elements through increased time efficiency in spatial encoding. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
High‐sensitivity Determination of Curcumin in Human Urine Using Gemini Zwitterionic Surfactant as a Probe by Resonance Light Scattering Technique
Authors: Chen Xi , Liang Shengwang , Zhu Li , Liu Jinbin , Zhang Guomin , Chen Zhanguang
Published: December 2011

Introduction

Curcumin is a popular plant medicine that is extracted from turmeric dry rhizomes of Curcuma longa Linn. The study of curcumin is well established and is currently becoming a centre of attention.

Objective

To develop a steady and simple assay for curcumin determination at the nanogram level based on the intense resonance light scattering (RLS) enhancement due to the interaction between curcumin and phosphodiesters quaternary ammonium salt (PQAS).

Methodology

PQAS, a new kind of Gemini zwitterionic surfactant, was used as the probe for the determination of curcumin by the RLS technique. A series of validation experiments was also performed.

Results

A linear relationship was constructed between the ΔIRLS and the concentration of curcumin. The linear regression equation was presented as ΔIRLS = 8.37 + 44.92c (µg/mL) with the regression coefficient r = 0.9987 (n = 12) and the linear range was 0.08–60.0 µg/mL. The detection limit (3σ) was 2.6 ng/mL.

Conclusion

The proposed method can be used to detect the content of curcumin in human urine samples and this new assay using PQAS as a probe was more sensitive and displayed a wider linear range than that reported previously. Copyright © 2011 John Wiley & Sons, Ltd.
Scope of network polysilanes in the synthesis of fluorescent silver and gold nanoparticles/nanoclusters‐modulations of their optical properties in the presence of Hg(II) ions
Authors: Shankar Ravi , Sahoo Usharani
Published: December 2011

The network polysilanes (polysilynes) [RMe2SiCH2CH2Si]n, [R=Ph (1), 2‐Furyl (2)] have been synthesized by room temperature reaction of the corresponding organotrichlorosilane with Na dispersion in tetrahydrofuran (THF) medium. The method allows the formation of high molecular weight polymers [Mw/PDI = 10,504/2.2 (1), 9176/1.5 (2)] in improved yields than those obtained from classical Wurtz coupling reaction (Na, toluene, 110 °C). These polymers act as reducing agents for Ag(I) and Au(III) ions to afford stable metal nanoparticles of 4–8 nm size domains in toluene medium. The corresponding polymer–silver nanocomposites, 1a and 2a, are fluorescent in the green light region (λmax = ∼ 530 nm) due to the formation of silver nanoclusters (AgNCs) along with the nanoparticles (AgNPs). A simple chemical approach has been developed to modulate the plasmonic and emission intensities of the nanocomposite 1a by reacting with varying concentrations (10−12 to 10−7M) of HgI2 in toluene. The method allows enhancement of the fluorescence intensity associated with AgNCs. The results are explained by invoking coupling between the energies of surface plasmon resonance and the nanocluster electronic transition. The polymer–gold nanocomposites, 1b and 2b, are non‐fluorescent and the plasmonic resonance at 530 nm associated with AuNPs is found to be insensitive to Hg(II) ions. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Plasma‐Mediated Nanosilver‐Organosilicon Composite Films Deposited on Stainless Steel: Synthesis, Surface Characterization, and Evaluation of Anti‐Adhesive and Anti‐Microbial Properties on the Model Yeast Saccharomyces cerevisiae
Authors: Saulou Claire , Despax Bernard , Raynaud Patrice , Zanna Sandrine , Seyeux Antoine , Marcus Philippe , Audinot Jean‐Nicolas , Mercier‐Bonin Muriel
Published: December 2011

A series of plasma‐mediated thin films (≈175 nm), containing silver nanoparticles embedded in an organosilicon matrix with controllable properties (silver content, nanoparticle size, matrix composition), were deposited onto stainless steel and chemically and structurally characterized, using a large set of analytical techniques. The process originality relies on a dual strategy, associating silver sputtering, and simultaneous plasma enhanced chemical vapor deposition, in an argon‐hexamethyldisiloxane plasma, using an asymmetrical radiofrequency discharge at 13.56 MHz. X‐ray photoelectron spectroscopy, FTIR spectroscopy, and Raman spectroscopy demonstrated the inclusion of metallic silver nanoparticles within the organosilicon‐like matrix. Silver content was directly related to the plasma process conditions. TOF‐SIMS analysis revealed that the film composition was homogeneous in depth. SEM and TEM observations confirmed the nanoparticle‐based morphology of the coatings, dependent on the silver content. The film anti‐adhesive potentialities were evaluated in vitro toward the model yeast Saccharomyces cerevisiae by performing shear‐flow induced detachment experiments, under well‐controlled hydrodynamic, and physico‐chemical conditions. The maximal effect was achieved for the organosilicon matrix alone. When silver nanoparticles were incorporated, yeast detachment was lower, probably due to the strong affinity of embedded silver for biological components of the cell wall surface. The presence of methyl groups in the matrix network could also promote enhanced hydrophobic yeast/coating interactions. An anti‐microbial action of silver (conjugated effect of nanoparticles and chemisorbed Ag+ ions and complexes released through nanoparticle oxidation) at the immediate vicinity of the coating surface occurred, depending on the silver content. In the conditions under study, a maximal 1.9 log reduction in viable counts was observed, compared to control conditions with bare stainless steel. Based on NanoSIMS50 elemental mapping, various characteristic cell sub‐structures and inclusions were detected, such as cell wall and nucleus. After yeast exposure to nanosilver‐containing films, a quite homogeneous distribution of released silver all over the cell was observed, overlapping with sulfur and phosphorous signals.

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Influence of annealing under reducing ambient on properties of ZnO thin films prepared by mist CVD
Authors: Kawaharamura T. , Orita H. , Shirahata T. , Yoshida A. , Fujita S. , Hirao T.
Published: December 2011

The resistivity of ZnO thin films grown at 300 °C with mist CVD method can be decreased about 3 orders of magnitude, from 6.2 Ωcm as deposited to 2.2×10‐2 Ωcm for the film after post annealing at 350 °C under reducing ambient of 5% H2 in N2 (forming gas: FG) with increasing mobility and without changing carrier density. It is thought that the electrical properties of the ZnO thin films with a large amount of impurities due to the low temperature growth are changed without changing surface morphology, crystal structure and impurity content after annealed in the reducing ambient. This can be explained by the decrease of disorder in the band gap in the grain and lowering of the Schottky barrier height in the grain boundaries due to the H2 interaction with oxygen. The model is supported by the quick decrease of resistivity under FG annealing. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of a monolithic integrated rectenna by using an InGaAs/InAlAs triple‐barrier resonant tunneling diode for zero bias detection of submilimeter‐waves
Authors: Nakamura Masahito , Takahagi Satoshi , Saito Mitsufumi , Suhara Michihiko
Published: December 2011

Zero bias millimeter‐wave detection has been investigated by using backward diodes with InGaAs‐based or Sb‐based interband tunneling and Schottky contact InGaAs‐ based double‐barrier resonant tunneling diodes (DBRTDs). These were intended to be typical cases where the antenna and the detector are individually designed and mutually connected. On the other hand, in this paper we focus on constructing a monolithic type of rectenna (rectifying antenna) for sub‐millimeter wave detection. Our objective is to propose and analyze zero bias detection properties with an InGaAs/InAlAs triple‐barrier resonant tunneling diode (TBRTD) integrated with a bow‐tie type of broadband self‐complementary antenna. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of CuGaO2 films prepared by sol‐gel methods
Authors: Alias Afishah , Sakamoto Masato , Kimura Teppei , Uesugi Katsuhiro
Published: December 2011

Delafossite CuGaO2 films have been fabricated by sol‐gel method. The stable Cu‐Ga‐O solutions were prepared by the mixing of Cu‐O and Ga‐O sol solutions using copper (II) acetate monohydrate and tris‐acetylacetonato gallium (III), respectively. Phase separation in CuGaO2 films is depending on the preparation of sol solutions and post‐bake conditions. P ‐type CuGaO2 films without CuO and Ga2O3 phases were fabricated by post‐baking at 700∼800 °C for 1 h in N2 atmosphere. The sol‐gel‐derived CuGaO2 films show high transparency more than 80% in the visible light range, and the optical energy gap was approximately 3.56 eV. Wide bandgap β ‐Ga2O3 and narrow bandgap CuO oxide films were also successfully fabricated using Cu‐Ga‐O sol solutions. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Entrainment processes in the diurnal cycle of deep convection over land
Authors: Stirling A. J. , Stratton R. A.
Published: December 2011

In this article we show that entrainment during the developing stages of deep convection over land is much higher than convection at equilibrium. A series of idealised cloud‐resolving model simulations are performed for a range of environmental conditions, and these show that the interaction with the environment via the entrainment and detrainment rates gradually decreases as the day progresses, reverting to the values found at equilibrium. The entrainment and detrainment rates are themselves found to depend on the environmental humidity and stability, and are also strongly linked to cloud size, suggesting that the representation of the horizontal growth of clouds in convective parametrizations is important for the representation of the diurnal cycle. We propose a simple new entrainment and detrainment formulation to take account of these findings, and show that this improves the representation of developing convection in a single‐column model, providing a more gradual transition towards deep convection. Copyright © 2011 British Crown copyright, the Met Office. Published by John Wiley & Sons Ltd.
Robotic system for cervical spine surgery
Authors: Kostrzewski S. , Duff J. M. , Baur C. , Olszewski M.
Published: December 2011

Background

In contemporary surgical clinical practice, spinal instability is often treated with mechanical stabilization techniques in order to protect the spinal cord and nerve roots. These techniques involve placing screws in defined regions of the vertebrae, typically the pedicle, where the strongest bone is found. The challenge for the surgeon is the accurate placement of screws for good mechanical purchase and to avoid damage to surrounding vital anatomical structures. This is especially critical in the cervical region, where the target bone mass is smaller and the spinal cord, nerve roots and vertebral arteries are all at risk. A robotic system enabling the surgeon to precisely place implants into the vertebrae should enhance safety and may potentially improve surgical results.

Methods

We describe such a system, which consists of a compact robot positioned using a passive structure, an optical tracking system, a surgical input device and planning and navigational software. The implant trajectory in each vertebra is planned preoperatively, using fine‐cut computerized tomography (CT) scans. During surgery, registration matching between the CT scan and the patient's anatomy is achieved using point to point registration, refined with a surface merge technique. Approximate robot positioning is done passively by the surgeon. Final precise instrument positioning is performed by the robot according to the planned trajectory through the target vertebra. Implants (screws) are then placed through the robot‐guided working channel.

Results

Six cadaver experiments, consisting of placing transarticular (i.e. crossing the joints between the vertebrae) screws in the upper two vertebrae of the human cervical spine, were performed. Implant placement accuracy was comparable with that achieved using freehand image‐guided techniques by an experienced surgeon.

Conclusions

These results confirm the utility and applicability of the system. It is currently in redesign to improve accuracy and to render it compatible with on‐line planning. Copyright © 2011 John Wiley & Sons, Ltd.
Modeling the dynamics of social networks using Bayesian hierarchical blockmodels
Authors: Rodríguez Abel
Published: December 2011

We introduce a new class of dynamic models for networks that extends stochastic blockmodels to settings where the interactions between a group of actors are observed at multiple points in time. Our goal is to identify structural changes in model features such as differential attachment, homophily by attributes, transitivity, and clustering as the network evolves. Our focus is on Bayesian inference, so the models are constructed hierarchically by combining different classes of Bayesian nonparametric priors. The methods are illustrated through a simulation study and two real data sets. © 2011 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 5: 218–234, 2012
The Relationship between Childhood Parental Loss and Metabolic Syndrome in Obese Subjects
Authors: Alciati Alessandra , Gesuele Felice , Casazza Giovanni , Foschi Diego
Published: December 2011

The increasing global trend of obesity is a fundamental contributor to the growing prevalence of metabolic syndrome, a cluster of medical abnormalities including impaired glucose and lipid metabolism, obesity and hypertension. Results from animal and human investigations have shown that early life stress can result in weight gain and metabolic changes.

Our aim is to investigate whether a particular type of an early adverse event, i.e. parental loss during childhood, is associated with the development of metabolic syndrome in severely obese subjects.

One hundred thirty‐five consecutive obese patients who were seeking bariatric surgery were assessed for metabolic syndrome according to the Adult Treatment Panel (ATP) III criteria. Information regarding the experience of parental separation or bereavement before the age of 17 was collected with the use of a semi‐structured interview.

In our population, 31.1% of the subjects met the criteria for metabolic syndrome. No significant differences in demographic factors, health habits or psychiatric diagnosis were found between patients with and without coexisting metabolic syndrome. After adjusting for age and gender, multivariate logistic regression analysis revealed that both childhood loss of a parent and a body mass index (BMI) value greater than 50 were significant predictors of metabolic syndrome.

This study provides preliminary evidence linking childhood parental loss to risk factors for the development of metabolic syndrome. Copyright © 2011 John Wiley & Sons, Ltd.
ISCS method for the performance‐based seismic design of vertically irregular reinforced concrete frame structures
Authors: Men Jinjie , Shi Qingxuan
Published: December 2011

The procedure to obtain the inelastic demand curves for the multi‐degree‐of‐freedom system, composed of inter‐story shear versus inter‐story displacement curve is introduced. The demand curves are established by using mode spectrum method, and the dynamical characteristic of structure under different earthquake hazard levels is taken into account. The relation of structure performance object and displacement ductility is adopted to deduce the relation of structure performance object and inter‐story demand curve. Therefore, the inter‐story demand curves take into account the inelastic behavior of structure under earthquake action adequately. Then, considering the seismic responding characteristic and the capacity curve of the frame structure, a new method named Inter‐Story Capacity Spectrum (ISCS) is put forward for the performance‐based seismic design of vertically irregular frame structures. Examples are presented to demonstrate the applicability and the utility of the proposed method. It is concluded that the new method can control the inter‐story drift, the order and position of hinges of vertically irregular structures under different earthquake hazard levels. Comparing with time‐history analysis method, it leans to safe and is superior to direct displacement‐based design method. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis, Crystal Structure, and Characterization of three New Letrozole Complexes
Authors: Tang Yun‐Zhi , Zhou Man , Huang Jun , Cao Zan , Qi Ting‐Ting , Huang Guang‐Hua , Wen He‐Rui
Published: December 2011

Three new letrozole complexes {[Cu(Le)4Cl2]·(H2O)} (1), {[Ni(Le)4Cl2]·(H2O)}(2) and {[Co(Le)4Cl2]·(H2O)} (3) (Le = letrozole = 1‐[bis(4‐cyanophenyl)methyl]‐1, 2, 4‐triazole) were obtained from self‐assembly of CuCl2, NiCl2·6H2O, and CoCl2·6H2O with medicine letrozole. All compounds were characterized by IR spectroscopy, elemental, single‐crystal as well as powder X‐ray diffraction, and thermogravimetric analyses. The analyses of the structures indicate that all crystals belong to monoclinic system, space group C2/c, for complex 1 with crystal data a = 34.501(18) Å, b = 12.724(7) Å, c = 16.116(9) Å, β = 114.958(7) °, V = 6414(6) Å 3, Z = 4, F(000) = 2660, R1 = 0.0668, wR2 = 0.1574; for complex 2, a = 34.769(6) Å, b = 12.7267(18) Å, c = 16.046(2) Å, β = 115.281(3) °, V = 6420.1(16) Å 3, Z = 4, F(000) = 2656, R1 = 0.0510, wR2 = 0.0896; for complex 3, a = 35.063(8) Å,b = 12.658(3) Å, c = 16.056(4) Å, β = 115.387(3) °, V = 6438(2) Å3, Z = 4, F(000) = 2652, R1 = 0.0528, wR2 = 0.1205. The local arrangements around central metal atoms (CuII, NiII, and CoII) can be best described as distorted octahedra which are constructed by two chlorine atoms and four monodentate nitrogen atoms from different letrozole ligands. XRD results of 1–3 show that all peaks displayed in the measured patterns at room temperature closely match those in the simulated patterns generated from single‐crystal diffraction data, indicating single phases of 1–3 were formed.