bluuebunny/crossref_metadata_2025 huggingface dataset:
Aggregation and Solvation of Chiral N,P‐Amide Ligands in Coordinating Solvents: A Computational and NMR Spectroscopic Study
Authors: Rönnholm Petra , Nilsson Lill Sten O. , Gräfenstein Jürgen , Norrby Per‐Ola , Pettersson Mariell , Hilmersson Göran
Published: July 2012

The lithium amides of a series of chiral N,P ligands were studied in solution. This ligand class had been shown previously to give good selectivities in asymmetric alkylation of benzaldehyde. These lithium amides were found to aggregate into dimers with surprisingly strong coordination of phosphorus to lithium. The equilibrium between dimeric forms was found to depend strongly on non‐bonded interactions within the solute and between solute and solvent. Only if dispersion and free‐energy contributions were scaled to approximately 20 % of the gas‐phase values was it possible to reproduce the experimentally observed aggregation preferences. NMR spectroscopic shieldings were calculated and found to correlate well with the experimentally observed shifts. Calculated Li,P couplings were shown to be a sensitive measure of the LiP distance.
Distillate‐Range Products from Non‐Oil‐Based Sources by Catalytic Cascade Reactions
Authors: Lacarriere Antoine , Robin Julien , Świerczyński Dariusz , Finiels Annie , Fajula François , Luck Francis , Hulea Vasile
Published: July 2012

An original two‐step process efficiently catalyzed by functionalized mesoporous materials is proposed as a potential route for converting light olefins into long‐chain hydrocarbons in the distillate range. In the first step, ethylene can be selectively transformed into C4–C10 olefins with an even number of carbon atoms, over nickel‐exchanged AlMCM‐41, at 150 °C. When the nickel‐catalyzed oligomerization was assisted by a second acid‐catalyzed step over H‐MCM‐41, olefins with chains longer than 10 carbon atoms were mainly produced with a productivity of 180 g g−1 h−1.
Resource allocation scheme for orthogonal frequency division multiple access networks based on cooperative game theory
Authors: Alavi Seyed Mohamad , Zhou Chi
Published: July 2012

Cooperative game theory can be applied to orthogonal frequency division multiple access (OFDMA) networks for fair resource allocation. In this work, we consider a comprehensive cross‐layer framework including physical and medium access control layer requirements. We apply two cooperative games, nontransferable utility (NTU) game and transferable utility (TU) game, to provide fairness in OFDMA networks. In NTU game, fairness is achieved by defining appropriate objective function, whereas in TU game, fairness is provided by forming the appropriate network structure. For NTU game, we analyze the Nash bargaining solution as a solution of NTU game taking into account channel state information and queue state information. In a TU game, we show that coalition among subcarriers to jointly provide rate requirements leads to better performance in terms of power consumption. The subcarrier's payoff is determined according to the amount of payoff which that subcarrier brings to the coalition by its participation. We show that although NTU and TU games are modeled as rate adaptive and margin adaptive problems, respectively, both solutions provide a fair distribution of resources with minimum fairness index of 0.8. Copyright © 2012 John Wiley & Sons, Ltd.
Two‐dimensional gas chromatography with heart‐cutting for isotope ratio mass spectrometry analysis of steroids in doping control
Authors: Brailsford A. D. , Gavrilović I. , Ansell R. J. , Cowan D. A. , Kicman A. T.
Published: July 2012

The accuracy and precision of gas chromatography combustion isotope ratio mass spectrometry (GC‐C‐IRMS) measurements are highly dependent on analyte purity. Reliable analysis of urinary steroids for doping control therefore requires extensive and time‐consuming sample preparation (i.e. liquid chromatography fraction collection) prior to GC‐C‐IRMS analysis. The use of two‐dimensional GC (GC‐GC) with heart‐cutting (Deans Switch) as a possible approach to reduce the sample purification required for IRMS analysis is described herein. The system uses a low thermal mass oven (LTM) incorporated into an existing GC‐C‐IRMS system. GC‐GC allowed the use of a cyanopropyl/phenyl column in the first dimension to optimize the separation of underivatized steroids, while a phenyl‐methylpolysiloxane column in the second dimension focuses the selectively cut analytes into narrower peaks for more sensitive and reliable MS analysis. In addition, to confirm analyte identity, eluent from the second GC was split, with 20 % entering a scanning MS, and 80 % flowing to the IRMS. As a proof concept, the developed method was then used to analyze a single spot urine (5 ml) from an individual receiving T therapy (2 × 50 mg sachets of Testogel®). The T delta value (−27.8 ‰, [T] = 38 ng/ml) was clearly distinct from 11‐ketoetiocholanolone (−22.5 ‰) (used as an endogenous reference compound (ERC)), indicating T as being of exogenous origin. The simultaneous analysis by the scanning MS yielded a full scan mass spectrum of the same chromatographic peak, thus confirming the peak to be T. Copyright © 2012 John Wiley & Sons, Ltd.
Social Learning Through Environmental Risk Analysis of Biodiversity and GM Maize in South Africa
Authors: Dana Genya V. , Nelson Kristen C.
Published: July 2012

Environmental risk analyses (ERAs) can benefit from participatory methods that enhance social learning, whereby diverse participants share knowledge and perspectives to learn about complex socio‐ecological systems, develop a collective understanding of the risk problem and build support for specific solutions. We used surveys and interviews to investigate social learning among 22 stakeholders during a participatory ERA workshop to evaluate risks of genetically modified maize to South African biodiversity. The ERA process incorporated methodologies designed to enhance social learning, such as open communication, constructive conflict and extended engagement. We observed that social learning occurred as participants understood new information and perspectives, began thinking systemically and transformed their impressions of other participants. In this workshop, they did not develop a shared understanding of the ERA process or priority risks. However, the ERA workshop did engender social learning about other stakeholders, socio‐ecological systems and risk, creating a foundation for longer, iterative engagement needed to build shared understanding of complex problems and solutions related to biodiversity governance. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment
Preparation of Hollow TiO2 Spheres of the Desired Polymorphs by Layer‐by‐Layer Assembly of a Water‐Soluble Titanium Complex and Hydrothermal Treatment (Eur. J. Inorg. Chem. 20/2012)
Authors: Katagiri Kiyofumi , Inami Hitoshi , Koumoto Kunihito , Inumaru Kei , Tomita Koji , Kobayashi Makoto , Kakihana Masato
Published: July 2012

The cover picture shows the formation process of brookite‐type TiO2 hollow spheres through layer‐by‐layer assembly and hydrothermal treatment. The core–shell particles were formed by alternate deposition of the titanium–glycolate complex and positively charged polyelectrolyte on spherical polystyrene spheres utilizing electrostatic interactions. Hollow spheres formed with the polyionic titanium–glycolate complex and the cationic polyelectrolyte were obtained by removal of the polystyrene templates. The hollow shell was successfully crystallized as brookite‐type TiO2 by a hydrothermal treatment at pH = 4. Details are discussed in the article by K. Katagiri et al. on p. 3267 ff.

magnified image
Transition‐Metal‐Catalyzed Cyclization of Alkynals via Oxametallacycle Intermediates (Eur. J. Org. Chem. 20/2012)
Authors: Tanaka Ken , Tajima Yuki
Published: July 2012

The cover picture shows the Japanese famous inverted image of Mt. Fuji (reflected in the water). The scheme shows the general catalytic cycle of the transition‐metal‐catalyzed cyclization of alkynals via oxametallacycle intermediates. This cyclization is a highly efficient method for the stereoselective synthesis of carbocycles and heterocycles. This reaction is catalyzed by Ni, Rh, Ru, and Ti complexes and mediated by organometalloid reagents (X–Y = Si–H, B–C), organometallic reagents (X–Y = Zn–C), dihydrogen (X–Y = H–H), and organic reagents (X–Y = C–H, C–P). Details are presented in the Microreview by K. Tanaka and Y. Tajima on p. 3715 ff.

magnified image
From mass‐wasting to slope stabilization – putting constrains on a tectonically induced transition in slope erosion mode: a case study in the Judea Hills, Israel
Authors: Ryb Uri , Matmon Ari , Porat Naomi , Katz Oded
Published: July 2012

Calcrete‐coated remnants of landslide debris and alluvial deposits are exposed along the presently stable hillslopes of the Soreq drainage, Judea Hills, Israel. These remnants indicate that a transition from landslide‐dominated terrain to dissolution‐controlled hillslope erosion had occurred. This transition possibly occurred due to the significant decrease in tectonic uplift during the late Cenozoic. The study area is characterized by sub‐humid Mediterranean climate. The drainage hillslopes are typically mantled by thick calcrete crusts overlying Upper Cretaceous marine carbonate rocks. Using TT‐OSL dating of aeolian quartz grains incorporated in the calcrete which cements an ancient landslide deposit, we conclude that incision of ~100 m occurred from 1056 ± 262 to 688 ± 86 ka due to ~0·3° westward tilt of the region; such incision invoked high frequency of landslide activity in the drainage. The ages of a younger landslide remnant, alluvial terrace, and alluvial fan, all situated only a few meters above the present level of the active streambed, range between 688 ± 86 ka and 244 ± 25 ka and indicate that since 688 ± 86 the Soreq base level had stabilized and that landslide activity decreased significantly by the middle Pleistocene. Copyright © 2012 John Wiley & Sons, Ltd.
Activated hepatic stellate cells: Negative regulators of hepatocyte proliferation in liver diseases
Authors: Chung Chuhan , Iwakiri Yasuko , Groszmann Roberto J. , Iwakiri Yasuko , Taddei Tamar H.
Published: July 2012

Abstract

Tissue homeostasis requires an effective, limited wound-healing response to injury. In chronic disease, failure to regenerate parenchymal tissue leads to the replacement of lost cellular mass with a fibrotic matrix. The mechanisms that dictate the balance of cell regeneration and fibrogenesis are not well understood. Here we report that fibrogenic hepatic stellate cells (HSCs) in the liver are negative regulators of hepatocyte regeneration. This negative regulatory function requires stimulation of the 5-hydroxytryptamine 2B receptor (5-HT2B) on HSCs by serotonin, which activates expression of transforming growth factor β1 (TGF-β1), a powerful suppressor of hepatocyte proliferation, through signaling by mitogen-activated protein kinase 1 (ERK) and the transcription factor JunD. Selective antagonism of 5-HT2B enhanced hepatocyte growth in models of acute and chronic liver injury. We also observed similar effects in mice lacking 5-HT2B or JunD or upon selective depletion of HSCs in wild-type mice. Antagonism of 5-HT2B attenuated fibrogenesis and improved liver function in disease models in which fibrosis was pre-established and progressive. Pharmacological targeting of 5-HT2B is clinically safe in humans and may be therapeutic in chronic liver disease.
River flux uncertainties predicted by hydrological variability and riverine material behaviour
Authors: Moatar Florentina , Meybeck Michel , Raymond Sébastien , Birgand François , Curie Florence
Published: July 2012

Data on riverine fluxes are essential for calculating element cycles (carbon, nutrients, pollutants) and erosion rates from regional to global scales. At most water‐quality stations throughout the world, riverine fluxes are calculated from continuous flow data (q) and discrete concentration data (C), the latter being the main cause of sometimes large uncertainties. This article offers a comprehensive approach for predicting the magnitude of these uncertainties for water‐quality stations in medium to large basins (drainage basin area > 1000 km²) based on the commonly used discharge‐weighted method. Uncertainty levels – biases and imprecisions – for sampling intervals of 3 to 60 days are correlated first through a nomograph with a flux variability indicator, the quantity of riverine material discharged in 2% of time (M2%). In turn, M2% is estimated from the combination of a hydrological reactivity index, W2% (the cumulative flow volume discharged during the upper 2% of highest daily flow) and the truncated b50sup exponent, quantifying the concentration versus discharge relationship for the upper half of flow values (C = a q b50sup, for q > q50, where q50 is the median flow): M2% = W2% + 27.6b50sup. W2% can be calculated from continuous flow measurements, and the b50sup indicator can be calculated from infrequent sampling, which makes it possible to predict a priori the level of uncertainty at any station, for any type of riverine material either concentrated (b50sup > 0) or diluted (b50sup > 0) with flow. A large data base of daily surveys, 125 station variables of suspended particulate matter (SPM), total dissolved solids (TDS) and dissolved and particulate nutrients, was used to determine uncertainties from simulated discrete surveys and to establish relationships between indicators. Results show, for example, that for the same relatively reactive basin (W2% > 25%), calculated fluxes from monthly sampling would yield uncertainties approaching ±100% for SPM (b50sup > 1.4) fluxes and ±10% for TDS (b50sup = −0.2). The application to the nitrate survey of the river Seine shows significant trends for the 1972–2009 records. Copyright © 2012 John Wiley & Sons, Ltd.
Erosion source discrimination in a rural Australian catchment using compound‐specific isotope analysis (CSIA)
Authors: Hancock Gary J. , Revill Andrew T.
Published: July 2012

Compound‐specific isotope analysis (CSIA) has been used to assess the ability of δ13C signatures of fatty acid compounds to discriminate erosion sources in a rural Australian catchment. The study focussed on a high flow event (10‐year recurrence interval) which occurred in the Logan–Albert catchment in January 2008, and augmented a previous sediment tracing study using fallout radionuclides and major/minor element geochemistry. It is found that surface soil from forest, pasture and cultivated land uses are well discriminated using CSIA. Furthermore, sub‐surface soil sources associated with channel bank erosion and exposed subsoils (gullies and hillslope scalds) occurring specifically in the mid‐western Logan catchment could also be discriminated. Selected fatty acid and bulk carbon δ13C data were used in the IsoSource mixing model to determine erosion sources contributing sediment. The results were compared with results obtained using other sediment tracers. For the lower Logan River, the CSIA tracing results are consistent with fallout radionuclide and element geochemistry tracing, with channel bank erosion being confirmed as the major sediment source. Moreover, CSIA has quantified the significant contribution of exposed subsoils originating on hillslopes and drainage lines from the mid‐western region of the Logan catchment. In the Albert River catchment, about 40% of sediment comes from forest land use, although more than half of this may come from sub‐surface sources. These results have demonstrated that CSIA has the potential to significantly enhance the ability of sediment tracing studies to determine the extent that different land uses and erosion processes are contributing eroded soil to rivers, allowing an assessment of soil erosion and transport model predictions. Copyright © 2012 John Wiley & Sons, Ltd.
Global estimates of cancer prevalence for 27 sites in the adult population in 2008
Authors: Bray Freddie , Ren Jian‐Song , Masuyer Eric , Ferlay Jacques
Published: July 2012

Recent estimates of global cancer incidence and survival were used to update previous figures of limited duration prevalence to the year 2008. The number of patients with cancer diagnosed between 2004 and 2008 who were still alive at the end of 2008 in the adult population is described by world region, country and the human development index. The 5‐year global cancer prevalence is estimated to be 28.8 million in 2008. Close to half of the prevalence burden is in areas of very high human development that comprise only one‐sixth of the world's population. Breast cancer continues to be the most prevalent cancer in the vast majority of countries globally; cervix cancer is the most prevalent cancer in much of Sub‐Saharan Africa and Southern Asia and prostate cancer dominates in North America, Oceania and Northern and Western Europe. Stomach cancer is the most prevalent cancer in Eastern Asia (including China); oral cancer ranks as the most prevalent cancer in Indian men and Kaposi sarcoma has the highest 5‐year prevalence among men in 11 countries in Sub‐Saharan Africa. The methods used to estimate point prevalence appears to give reasonable results at the global level. The figures highlight the need for long‐term care targeted at managing patients with certain very frequently diagnosed cancer forms. To be of greater relevance to cancer planning, the estimation of other time‐based measures of global prevalence is warranted.
SUPERVISING PROFESSIONAL COUNSELORS
Authors: Bandel Murray
Published: July 2012

Practical problems in supervision of counselors stem from personality differences and differences in theoretical viewpoints. A survey of current literature on counselor supervision together with personal experiences as a supervisor of counselors, lead to certain conclusions for handling the situations which may arise.
In vivo bioluminescent imaging of α‐fetoprotein‐producing hepatocellular carcinoma in the diethylnitrosamine‐treated mouse using recombinant adenoviral vector
Authors: Kim Kwang Il , Park Ju Hui , Lee Yong Jin , Lee Tae Sup , Park Jae Jun , Song Inho , Nahm Sang‐Soep , Cheon Gi Jeong , Lim Sang Moo , Chung June‐Key , Kang Joo Hyun
Published: July 2012

Background

The in vivo molecular imaging method is a useful tool for monitoring carcinogenesis in various hepatocellular carcinoma (HCC) models, such as xenografted‐, chemical induced‐ and transgenic mice. The tumor‐specific gene expression strategy, such as transcriptional targeting, is essential for achieving a lower toxicity for normal liver tissue in therapy and the monitoring of tumor progression in diagnosis, respectively. The present study aimed to visualize spontaneously developing α‐fetoprotein (AFP)‐producing HCC through targeted gene expression in tumors using recombinant adenoviral vector.

Methods

The recombinant adenovirus vector, AdAFPfLuc (containing firefly luciferase gene driven by human AFP enhancer/promoter) was prepared. After in vitro infection by adenovirus, gene expression was confirmed using the luciferase assay, semi‐quantitative reverse transcriptase‐polymerase chain reaction and western blotting in AFP‐producing and nonproducing cells. Tumor‐bearing mice were intravenously injected with adenovirus, and bioluminescent images were obtained.

Results

The expression of fLuc was efficiently demonstrated by the luciferase assay in AFP‐producing cells but not in AFP‐nonproducing cells. AFP‐producing HCC targeted gene expression was confirmed at the mRNA and protein levels. After being injected intravenously in HuH‐7 xenografts and HCC‐bearing diethylnitrosamine‐treated mice using adenovirus, functional reporter gene expression was confirmed in tumors by in vivo bioluminescent imaging (BLI).

Conclusions

The recombinant adenovirus vector system can be used to monitor spontaneously developing AFP‐producing HCC and to evaluate targeted gene expression in tumors by in vivo BLI in a small animal model. Copyright © 2012 John Wiley & Sons, Ltd.
Quantification of hepatic macrosteatosis in living, related liver donors using T1‐independent, T2*‐corrected chemical shift MRI
Authors: Joe Eugene , Lee Jeong Min , Kim Kyung Won , Lee Kyung Bun , Kim Soo Jin , Baek Jee Hyun , Shin Cheong Il , Suh Kyung Suk , Yi Nam Joon , Han Joon Koo , Choi Byung Ihn
Published: July 2012

Purpose:

To evaluate the diagnostic implications of the iterative decomposition of water and fat using echo‐asymmetry and the least‐squares estimation (IDEAL) technique to detect hepatic steatosis (HS) in potential liver donors using histopathology as the reference standard.

Materials and Methods:

Forty‐nine potential liver donors (32 male, 17 female; mean age, 31.7 years) were included. All patients were imaged using the in‐ and out‐of‐phase (IOP) gradient‐echo (GRE) and IDEAL techniques on a 1.5 T MR scanner. To estimate the hepatic fat fraction (FF), two reviewers performed regions‐of‐interest measurement in 15 areas of the liver seen on the IOP images and on the IDEAL‐FF images. The magnetic resonance imaging (MRI) and pathology values of macrosteatosis were correlated using the Pearson correlation coefficient. We analyzed the diagnostic performance of IOP imaging and IDEAL for detecting HS.

Results:

The results of the hepatic‐FF estimated on IDEAL were well correlated with the histologic degree of macrosteatosis (γ = 0.902, P < 0.001). IDEAL showed 100% sensitivity and 91% specificity for detecting HS, and IOP imaging showed 87.5% sensitivity and 97% specificity, respectively.

Conclusion:

IDEAL is a useful tool for the preoperative diagnosis of HS in potential living liver donors; it can also help to avoid unnecessary biopsies in these patients. J. Magn. Reson. Imaging 2012;36:1124–1130. © 2012 Wiley Periodicals, Inc.
Reliability of cerebral blood volume maps as a substitute for diffusion‐weighted imaging in acute ischemic stroke
Authors: deIpolyi Amy R. , Wu Ona , Macklin Eric A. , Schaefer Pamela W. , Schwamm Lee H. , Gilberto Gonzalez R. , Copen William A.
Published: July 2012

Purpose:

To assess the reliability of cerebral blood volume (CBV) maps as a substitute for diffusion‐weighted MRI (DWI) in acute ischemic stroke. In acute stroke, DWI is often used to identify irreversibly injured “core” tissue. Some propose using perfusion imaging, specifically CBV maps, in place of DWI. We examined whether CBV maps can reliably subsitute for DWI, and assessed the effect of scan duration on calculated CBV.

Materials and Methods:

We retrospectively identified 58 patients who underwent DWI and MR perfusion imaging within 12 h of stroke onset. CBV in each DWI lesion's center was divided by CBV in the normal‐appearing contralateral hemisphere to yield relative regional CBV (rrCBV). The proportion of lesions with decreased rrCBV was calculated. After using the full scan duration (110 s after contrast injection), rrCBV was recalculated using simulated shorter scans. The effect of scan duration on rrCBV was tested with linear regression.

Results:

Using the full scan duration (110 s), rrCBV was increased in most DWI lesions (62%; 95% confidence interval, 48–74%). rrCBV increased with increasing scan duration (P < 0.001). Even with the shortest duration (39.5 s) rrCBV was increased in 33% of lesions.

Conclusion:

Because DWI lesions may have elevated or decreased CBV, CBV maps cannot reliably substitute for DWI in identifying the infarct core. J. Magn. Reson. Imaging 2012;36:1083–1087. © 2012 Wiley Periodicals, Inc.
Stress‐Induced Melting of Crystals in Natural Rubber: a New Way to Tailor the Transition Temperature of Shape Memory Polymers
Authors: Heuwers Benjamin , Quitmann Dominik , Katzenberg Frank , Tiller Joerg C.
Published: July 2012

Lightly cross‐linked natural rubber (NR, cis‐1,4‐polyisoprene) was found to be an exceptional cold programmable shape memory polymer (SMP) with strain storage of up to 1000%. These networks are stabilized by strain‐induced crystals. Here, we explore the influence of mechanical stress applied perpendicular to the elongation direction of the network on the stability of these crystals. We found that the material recovers its original shape at a critical transverse stress. It could be shown that this is due to a disruption of the strain‐stabilizing crystals, which represents a completely new trigger for SMPs. The variation of transverse stress allows tuning of the trigger temperature Ttrig(σ) in a range of 45 to 0 °C, which is the first example of manipulating the transition of a crystal‐stabilized SMP after programming.
Synthesis of Cyclic Polyamines by Enzymatic Generation of an Amino Aldehyde In Situ
Authors: Cassimjee Karim Engelmark , Marín Sílvia Rodríguez , Berglund Per
Published: July 2012

Multifunctional polycationic polyamines, for example, used in drug and gene delivery, have product range limitations in their synthesis methods. Here, we synthesize a polyamine by forming a self‐assembling amino aldehyde from the corresponding amino alcohol with horse liver alcohol dehydrogenase (HLADH), followed by reduction. Circular polyamines were synthesized from 3‐amino‐propan‐1‐ol as starting material, analogous to cyclic polyamines formed from azetidin. The product had an isolated yield of 89.7% or 15.3 g L−1. The predicted range of possible polyamine products by this method is broad since many amino alcohols are putative substrates for HLADH. The enzyme also had activity for 2‐amino‐propan‐1‐ol and 2‐amino‐2‐phenyl‐ethanol, for which the enantioselectivity was 330 (S) and 32 (R), respectively.
Quantitative rapid steady state T1 magnetic resonance imaging for cerebral blood volume mapping in mice: Lengthened measurement time window with intraperitoneal Gd‐DOTA injection
Authors: Perles‐Barbacaru Adriana T. , Berger François , Lahrech Hana
Published: July 2012

This work demonstrates how the rapid steady state T1 MRI technique for cerebral blood volume fraction (BVf) quantification can be used with intraperitoneal Gd‐DOTA injections in mice at 4.7 T. The peak signal amplitude after intravenous administration (0.7 mmol/kg) and the steady state signal amplitude reached 15 min after intraperitoneal administration (6 mmol/kg) in the same mice lead to equivalent BVf measures in the order of 0.02 in the brain. The resulting time window for BVf quantification is ≈30 min and allows for cerebral BVf mapping with increased spatial resolution or signal‐to‐noise ratio, or for monitoring functional BVf changes. A cerebral BVf increase of up to 25% induced by the vasodilator acetazolamide was observed, validating the vascular origin of the signal. The noninvasive and quantitative rapid steady state T1 technique can be used in serial studies to evaluate new drugs or disease models, such as antiangiogenic therapies in tumors. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Brown Fades: The End of Court‐Ordered School Desegregation and the Resegregation of American Public Schools
Authors: Reardon Sean F. , Grewal Elena Tej , Kalogrides Demetra , Greenberg Erica
Published: July 2012

In this paper, we investigate whether the school desegregation produced by court‐ordered desegregation plans persists when school districts are released from court oversight. Over 200 medium‐sized and large districts were released from desegregation court orders from 1991 to 2009. We find that racial school segregation in these districts increased gradually following release from court order, relative to the trends in segregation in districts remaining under court order. These increases are more pronounced in the South, in elementary grades, and in districts where prerelease school segregation levels were low. These results suggest that court‐ordered desegregation plans are effective in reducing racial school segregation, but that their effects fade over time in the absence of continued court oversight.
Antioxidant and antibacterial effects of natural phenolic compounds on green composite materials
Authors: España J.M. , Fages E. , Moriana R. , Boronat T. , Balart R.
Published: July 2012

The aim of this study is to establish the thermal performance of a biocomposite (Arbofill kokos®), stabilized with different natural phenolic additives, to check the antioxidant capacity of the resulting compounds. Different phenolic compounds (thymol, carvacrol, α‐tocopherol, and tannic acid) were used as biobased additives and the concentrations ranged between 0.5 wt% and 2 wt%. The results obtained were compared with formulations containing a typical industrial petroleum‐based antioxidant agent (octadecyl‐3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl) propionate). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the antioxidant performance of the selected natural additives. The antimicrobial effect of these natural phenolic compounds was also studied by analyzing the growth of bacterial colonies. The comparison between the natural phenolic compounds and the petroleum‐based antioxidant compound showed good antioxidant action for natural phenolic compounds; in all the mixtures of biocomposite and antioxidant agent the oxidation onset temperature (OOT) increased in a remarkable way, but the highest stabilization effect was achieved with α‐tocopherol with provides a % increase on OOT of about 45%. With regard to antibacterial activity of the different natural phenolic compounds, thymol, and carvacrol showed interesting antibacterial properties against Staphylococcus aureus. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Internal geometry variability of two woven composites and related variability of the stiffness
Authors: Olave Mireia , Vanaerschot Andy , Lomov Stepan V. , Vandepitte Dirk
Published: July 2012

In this work, the internal geometry measurements of two woven composites are analyzed: cross section of the yarns, fiber volume fraction, crimp, misalignment of the samples, thickness of the plates, nesting value, and so forth. The chosen textile composites are produced using the same resin reinforcement and same architecture, but have different yarn size (3K and 12K). The dispersion of measured geometrical parameters is introduced in a numerical multiscale modeling approach to evaluate the macroscopic stiffness values. A sensitivity analysis is performed for each geometrical parameter and laminate stiffnesses are derived. These are linked to the experimentally obtained elastic properties by tensile tests. Finally, the unit cell size scale effect for measured geometry variability and experimentally obtained elastic properties are evaluated. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Rheological, thermal, and mechanical properties of phosphorus‐containing wholly aromatic thermotropic liquid crystalline polymer‐filled poly(butylene terephthalate) composites
Authors: Yang Zhi , Cao Bo , Zhu Jiaming , Shen Jiabin , Li Jiang , Guo Shaoyun , Wang Yuzhong
Published: July 2012

Phosphorus‐containing wholly aromatic thermotropic liquid crystalline polymer (TLCP) reinforced poly(butylene terephthalate) (PBT) composites were prepared. Dynamic rheological analysis displayed that the addition of TLCP led to the decrease of the complex viscosity of PBT. While the thermal stability and tensile modulus were found to be increased distinctly, the results of dynamic mechanical analysis, isothermal crystallization, and morphological observation indicated that these changes were related to the rigid chains and in situ fibrillation of TLCP phase, and the interfacial adhesion between PBT and TLCP. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Validity of health plan and birth certificate data for pregnancy research
Authors: Andrade Susan E. , Scott Pamela E. , Davis Robert L. , Li De‐Kun , Getahun Darios , Cheetham T. Craig , Raebel Marsha A. , Toh Sengwee , Dublin Sascha , Pawloski Pamala A. , Hammad Tarek A. , Beaton Sarah J. , Smith David H. , Dashevsky Inna , Haffenreffer Katherine , Cooper William O.
Published: July 2012

Purpose

To evaluate the validity of health plan and birth certificate data for pregnancy research.

Methods

A retrospective study was conducted using administrative and claims data from 11 U.S. health plans and corresponding birth certificate data from state health departments. Diagnoses, drug dispensings, and procedure codes were used to identify infant outcomes (cardiac defects, anencephaly, preterm birth, and neonatal intensive care unit [NICU] admission) and maternal diagnoses (asthma and systemic lupus erythematosus [SLE]) recorded in the health plan data for live born deliveries between January 2001 and December 2007. A random sample of medical charts (n = 802) was abstracted for infants and mothers identified with the specified outcomes. Information on newborn, maternal, and paternal characteristics (gestational age at birth, birth weight, previous pregnancies and live births, race/ethnicity) was also abstracted and compared to birth certificate data. Positive predictive values (PPVs) were calculated with documentation in the medical chart serving as the gold standard.

Results

PPVs were 71% for cardiac defects, 37% for anencephaly, 87% for preterm birth, and 92% for NICU admission. PPVs for algorithms to identify maternal diagnoses of asthma and SLE were ≥ 93%. Our findings indicated considerable agreement (PPVs > 90%) between birth certificate and medical record data for measures related to birth weight, gestational age, prior obstetrical history, and race/ethnicity.

Conclusions

Health plan and birth certificate data can be useful to accurately identify some infant outcomes, maternal diagnoses, and newborn, maternal, and paternal characteristics. Other outcomes and variables may require medical record review for validation. Copyright © 2012 John Wiley & Sons, Ltd.
The nucleofuge in the pyridinolysis of O‐(4‐nitrophenyl) S‐aryl thio and dithiocarbonates
Authors: Castro Enrique A. , Aliaga Margarita E. , Gazitúa Marcela , Santos José G.
Published: July 2012

A kinetic investigation is undertaken on the pyridinolysis of S‐phenyl O‐(4‐nitrophenyl) dithiocarbonate (1), S‐(4‐nitrophenyl) O‐(4‐nitrophenyl) dithiocarbonate (2) and S‐phenyl O‐(4‐nitrophenyl) thiocarbonate (3) in aqueous ethanol. The Brønsted‐type plots (log kN versus pKa) obtained are linear and are explained by a stepwise mechanism with the existence of a tetrahedral intermediate (T±) and its breakdown to products as the rate determining step. The high‐performance liquid chromatography analysis of the products of these reactions and that for the reaction of S‐(4‐chlorophenyl) O‐(4‐nitrophenyl) dithiocarbonate (4) with 4‐oxypyridine shows that 4‐nitrophenoxide is the principal (or the sole) leaving group in these reactions. From the results obtained in the reaction of compound 2, it can be concluded that 4‐nitrophenoxide is a better nucleofuge than 4‐nitrobenzenethiolate from the same tetrahedral intermediate, although the former is three pKa units more basic than the latter. Reasons for this behaviour are given. Copyright © 2012 John Wiley & Sons, Ltd.
Silicon Patterning Using Self‐assembled PS‐b‐PAA Diblock Copolymer Masks for Black Silicon Fabrication via Plasma Etching
Authors: Zhang Xin , Sushkov Andrei B. , Metting Christopher J. , Fackler Sean , Drew H. Dennis , Briber R. M.
Published: July 2012

The poly(styrene‐b‐acrylic acid) diblock copolymer is utilized as a novel self‐assembling mask material suitable for pattern transfer applications. This material system has high dry etch selectivity and can produce a variety of feature types and size scales. Different vertical profiles were produced by altering the etch recipes and diblock copolymer or SiO2 mask processing. This patterning technique is used to fabricate antireflective silicon metamaterials that show broadband antireflection properties in the visible and infrared wavelength range. These materials are potentially useful for solar cell and light sensing applications.

magnified image
Plasma‐Induced Damage and Surface Functionalization of Double‐Walled Carbon Nanotubes Using Atmospheric Pressure RF Discharge
Authors: Nozaki Tomohiro , Yoshida Shinpei , Okazaki Ken
Published: July 2012

Double‐walled carbon nanotubes (DWCNTs) were synthesized using atmospheric pressure plasma‐enhanced chemical vapor deposition. As‐produced DWCNTs were exposed to He/H2 atmospheric pressure RF discharge for 1 min at 100 °C. The top CNT layer was severely damaged, showing a large D‐band peak in the Raman spectrum. However, hydrogen plasma treatment does not create covalent CH bonds. When a H2/O2 mixture was added, plasma damage was suppressed greatly because O2 scavenges active hydrogen. The CH groups were produced via oxygen‐containing reactive species. Active hydrogen creates sp3‐like carbon structures that destroy graphitized CNTs. Oxygen‐containing species such as OH and HOO are useful to break sp2 bonds and to functionalize CNT sidewalls.

magnified image
Rescue of the aggregation prone Itk Pleckstrin Homology domain by two mutations derived from the related kinases, Btk and Tec
Authors: Boyken Scott E. , Fulton D. Bruce , Andreotti Amy H.
Published: July 2012

IL‐2 inducible T‐cell kinase (Itk) is a Tec family non‐receptor tyrosine kinase involved in signaling downstream of the T‐cell receptor. Itk contains an amino‐terminal Pleckstrin Homology (PH) domain that binds phosphatidylinositol (3,4,5)‐trisphosphate, recruiting Itk to the plasma membrane upon T‐cell receptor activation. In addition to phosphoinositide binding, accumulating data suggest that the Itk PH domain likely mediates additional interactions outside of the phosphoinositide ligand binding pocket. The structural basis for additional PH domain functions remains elusive because of the poor recombinant expression and in vitro solution behavior of the Itk PH domain. Here, we determine that the lone α‐helix in the Itk PH domain is responsible for the poor solution properties and that mutation of just two residues in the Itk α‐helix to the corresponding amino acids in Btk or Tec dramatically improves the soluble recombinant expression and solution behavior of the Itk PH domain. We present this double mutant as a valuable tool to characterize the structure and function of the Itk PH domain. It is also interesting to note that the precise sites of mutation identified in this study appear as somatic mutations associated with cancerous tissue. Collectively, the findings suggest that the two helical residues in the Itk PH domain may serve an important and unique structural role in wild‐type Itk that differentiates this tyrosine kinase from its related family members.
Combining different design strategies for rational affinity maturation of the MICA‐NKG2D interface
Authors: Henager Samuel H. , Hale Melissa A. , Maurice Nicholas J. , Dunnington Erin C. , Swanson Carter J. , Peterson Megan J. , Ban Joseph J. , Culpepper David J. , Davies Luke D. , Sanders Lisa K. , McFarland Benjamin J.
Published: July 2012

We redesigned residues on the surface of MICA, a protein that binds the homodimeric immunoreceptor NKG2D, to increase binding affinity with a series of rational, incremental changes. A fixed‐backbone RosettaDesign protocol scored a set of initial mutations, which we tested by surface plasmon resonance for thermodynamics and kinetics of NKG2D binding, both singly and in combination. We combined the best four mutations at the surface with three affinity‐enhancing mutations below the binding interface found with a previous design strategy. After curating design scores with three cross‐validated tests, we found a linear relationship between free energy of binding and design score, and to a lesser extent, enthalpy and design score. Multiple mutants bound with substantial subadditivity, but in at least one case full additivity was observed when combining distant mutations. Altogether, combining the best mutations from the two strategies into a septuple mutant enhanced affinity by 50‐fold, to 50 nM, demonstrating a simple, effective protocol for affinity enhancement.
Air–sea interaction in the Gulf of Guinea at intraseasonal time‐scales: wind bursts and coastal precipitation in boreal spring
Authors: Leduc‐Leballeur Marion , de Coëtlogon Gaëlle , Eymard Laurence
Published: July 2012

The role of air–sea interaction in the boreal spring precipitation of the West African monsoon is explored through the wind variability in the Gulf of Guinea. Linear regressions are performed in May–June during the decade 2000–2009 to investigate the origin and effect of the surface wind strengthening north of the Equator. It appears that the equatorial sea‐surface temperature cooling intensifies a surface‐wind equatorial divergence/coastal convergence circulation, and generates a cross‐equatorial pressure gradient, which both strengthen the southerlies north of the Equator. This increases subsidence above the ocean and convection in the northern Gulf of Guinea. In addition, an abrupt change is observed in the surface wind pattern in the eastern equatorial Atlantic (EEA) between April and July. To investigate the transition mechanisms, a reference date is defined as the date when the surface wind north of the Equator becomes and remains stronger than south of the Equator. Thus the maintenance of strong southerlies north of the Equator is linked to a coincident installation of a deep circulation on the whole troposphere and a northward shift of the low atmospheric local circulation. The resulting sharp seasonal transition coincides each year with a southeasterly wind burst, suggesting that the equatorial SST cooling plays a role in the precipitation along the African coast during boreal spring. Copyright © 2012 Royal Meteorological Society
Carbon isotopic characterization of cider CO2 by isotope ratio mass spectrometry: a tool for quality and authenticity assessment
Authors: Cabañero Ana I. , Rupérez Mercedes
Published: July 2012

RATIONALE

The cider market is an important sector of the food industry in certain regions. Adulteration of cider can happen in several ways: for example, by the addition of sugar, or of exogenous CO2 to certain types of cider. Because such practices are not allowed by either Spanish legislation or the legislation of other countries, it is essential to study possible methods to detect these unauthorized practices. For this purpose a procedure was required to study the stable carbon isotopic composition of CO2 in cider.

METHODS

A liquid sample of cider was transferred to a vial and CO2 from the headspace of the vial was analyzed using a peripheral device interfaced to an isotope ratio mass spectrometer. Separation of the CO2 from water and ethanol was achieved using a gas chromatography column located in the peripheral device.

RESULTS

The values for repeatability and reproducibility obtained indicated the robustness of the method, which is required for routine analysis. Ninety cider samples from various origins were analyzed, most of which showed a 13C content consistent with the declared origin. The δ13C ranged from −24.80‰ to −20.89‰ for ciders with endogenous carbon dioxide (−22.74 ± 0.79‰) and −37.13‰ to −26.00‰ if industrial CO2 was added. Several samples were also suspected of C4 sugar addition prior to the fermentation.

CONCLUSIONS

A fast, accurate and simple method for cider adulteration detection was developed. The addition of exogenous CO2 as well as C4 sugar addition prior to fermentation could be detected. The method showed advantages over existing methods in term of simplicity (no sample preparation and very long‐term stability of the sample), speed (less than 10 min/sample) and precision ((r ≤0.32 and R ≤0.42). Copyright © 2012 John Wiley & Sons, Ltd.
Production and ionization energies of KnF (n = 2–6) clusters by thermal ionization mass spectrometry
Authors: Veljković F. M. , Djustebek J. B. , Veljković M. V. , Veličković S. R. , Perić‐Grujić A. A.
Published: July 2012

RATIONALE

The very small clusters of the type KnF are of particular importance since their first ionization energies (IEs) are lower than those of the alkali metal atoms. Theoretical calculation has demonstrated that this kind of cluster represents a potential 'building block' for cluster‐assembly materials with unique structural, electronic, optical, magnetic, and thermodynamic properties. To date, however, there have been no experimental results on the IEs of KnF (n >2) clusters.

METHOD

KnF (n = 2–6) clusters were produced by the evaporation of a solid potassium fluoride salt using a modified thermal ionization source of modified design, and mass selected by a magnetic sector mass spectrometer where their IEs were determined.

RESULTS

Clusters KnF (n = 3–6) were detected for the first time. The order of the ion intensities was K2F+> > K4F+> > K3F+K6F+ > K5F+. The determined IEs were 3.99 ± 0.20 eV for K2F, 4.16 ± 0.20 eV for K3F, 4.27 ± 0.20 eV for K4F, 4.22 ± 0.20 eV for K5F, and 4.31 ± 0.20 eV for K6F. The IEs of KnF increase slightly with the increase in potassium atom number from 2 to 6. We also observed that the presence of a fluorine atom leads to increasing ionization energy of bare metal potassium clusters.

CONCLUSIONS

The modified thermal ionization source provides an efficient way of obtaining the fluorine‐doped potassium clusters. These results also present experimental proof that KnF (n = 2–6) clusters belong to the group of 'superalkali' species. Copyright © 2012 John Wiley & Sons, Ltd.
Migrating components in a polyurethane laminating adhesive identified using gas chromatography/mass spectrometry
Authors: Athenstädt Behnusch , Fünfrocken Michael , Schmidt Torsten C.
Published: July 2012

RATIONALE

Plastics are increasingly used as packaging materials for pharmaceuticals. However, diffusion of compounds in plastic into drugs may endanger patients' health. Regulatory authorities therefore demand detailed information about leachable compounds in plastics. Here we identify migrating components of a sterilization‐resistant polyurethane (PUR) adhesive used in the primary packaging for an aqueous pharmaceutical. This identification is an essential first step for quantification and toxicological evaluation of the compounds.

METHODS

We used various hyphenated mass spectrometry (MS) methods: gas chromatography (GC/MS) with either electron impact ionization or chemical ionization, and high resolution liquid chromatography (LC/MS) with electrospray ionization.

RESULTS

Of the 13 migrating substances detected, 11 are cyclic esters with characteristic fragmentation schemes apparent from their mass spectra. These esters are formed as by‐products during the reaction of adipic and isophthalic acid with monoethylene glycol and diethyelene glycol. A cyclic ester of isophthalic acid and tetraethylene glycol and a product of the reaction of isophoron diisocyanate with methanol were clearly identified.

CONCLUSIONS

Complementary use of several hyphenated mass spectrometric methods enables successful identification of leachable compounds in the PUR adhesive under study. This opens the way for quantification and evaluation of the potential toxicities of these compounds. Despite the range of compositions of PUR laminates, the approach presented here may be applicable for the qualitative assessment of all PURs. Copyright © 2012 John Wiley & Sons, Ltd.