bluuebunny/crossref_metadata_2025 huggingface dataset:
Alteration of HLA‐F and HLA I antigen expression in the tumor is associated with survival in patients with esophageal squamous cell carcinoma
Authors: Zhang X. , Lin A. , Zhang J.‐G. , Bao W.‐G. , Xu D.‐P. , Ruan Y.‐Y. , Yan W.‐H.
Published: April 2012

Alteration of human leukocyte antigen (HLA) expression, such as decreased HLA I (HLA‐A, ‐B and ‐C) antigens and elevated nonclassical HLA I antigens (HLA‐E, ‐F and ‐G), was reported to have an unfavorable prognosis in various cancers. In our study, HLA‐F expression in 105 primary esophageal squamous cell carcinoma (ESCC) lesions and 62 case‐matched adjacent normal tissues, and HLA I antigens among 68 cases were analyzed by immunohistochemistry. Data revealed that HLA‐F expression was observed in 58.1% (61/105) of the ESCC lesions and in 54.8% (34/62) of the normal esophageal tissues. Among the 62 case‐matched samples, HLA‐F expression (lesion vs. normal tissue) was upregulated, unchanged and downregulated in 13 (21.0%), 6 (9.6%) and 43 (69.4%) cases, respectively. Patients with HLA‐F positive had a worse survival than those with HLA‐F negative (p = 0.040). Patients with upregulated HLA‐F expression (lesion vs. normal tissue) had significantly worse survival than those with HLA‐F unchanged and downregulated (p = 0.010). Furthermore, decreased HLA I expression was observed in 41.2% (28/68) patients and was with worse prognosis in comparison to those with preserved HLA I expression (p = 0.001). Multivariate analysis using Cox's proportional hazards model revealed that upregulated HLA‐F expression (p = 0.026) and downregulated HLA I expression (p = 0.013) could be an independent unfavorable prognostic factor. In conclusion, our study provided the evidence that alteration of HLA I and HLA‐F antigen expression was associated with survival in patients with ESCC.
MicroRNA‐181b targets cAMP responsive element binding protein 1 in gastric adenocarcinomas
Authors: Chen Lin , Yang Qian , Kong Wei‐Qing , Liu Tao , Liu Min , Li Xin , Tang Hua
Published: April 2012

MicroRNAs are a class of small endogenous non‐coding RNAs that function as post‐transcriptional regulators. In our previous study, we found that miR‐181b was significantly downregulated in human gastric adenocarcinoma tissue samples compared to the adjacent normal gastric tissues. In this study, we confirm the down‐regulation of miR‐181b in human gastric cancer cell lines versus the gastric epithelial cells. Overexpression of miR‐181b suppressed the proliferation and colony formation rate of gastric cancer cells. miR‐181b downregulated the expression of cAMP responsive element binding protein 1 (CREB1) by binding its 3′ untranslated region. Overexpression of CREB1 counteracted the suppression of growth in gastric cancer cells caused by ectopic expression of miR‐181b. These results indicate that miR‐181b may function as a tumor suppressor in gastric adenocarcinoma cells through negative regulation of CREB1. © 2012 IUBMB IUBMB Life, 64(7): 628–635, 2012
The osteoinductive potential of printable, cell‐laden hydrogel‐ceramic composites
Authors: Fedorovich Natalja E. , Leeuwenburgh Sander C. , van der Helm Yvonne J. M. , Alblas Jacqueline , Dhert Wouter J. A.
Published: April 2012

Hydrogels used as injectables or in organ printing often lack the appropriate stimuli to direct osteogenic differentiation of embedded multipotent stromal cells (MSCs), resulting in limited bone formation in these matrices. Addition of calcium phosphate (CaP) particles to the printing mixture is hypothesized to overcome this drawback. In this study we have investigated the effect of CaP particles on the osteoinductive potential of cell‐laden hydrogel‐CaP composite matrices. To this end, apatitic nanoparticles have been included in Matrigel constructs where after the viability of embedded progenitor cells was assessedin vitro. In addition, the osteoinductive potential of cell‐laden Matrigel containing apatitic nanoparticles was investigatedin vivoand compared with composites containing osteoinductive biphasic calcium phosphate (BCP) microparticles after subcutaneous implantation in immunodeficient mice. Histological and immunohistochemical analysis of the tissue response as well asin vivobone formation revealed that apatitic nanoparticles were osteoinductive and induced osteoclast activation, but without bone formation. The BCP particles were more effective in inducing elaborate bone formation at the ectopic location. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A: 2412–2420, 2012
The choice of vascular access for therapeutic apheresis
Authors: Kalantari Kambiz
Published: April 2012

Therapeutic apheresis (TA) is performed using either centrifugation‐based or filter‐based systems. The blood flow rate (BFR) used for TA using centrifugation‐based systems is less than 100 mL/min. Because of this low BFR requirement, even peripheral veins can be considered as an option for TA, especially for less‐frequent treatments and those performed for short periods. Other options for vascular access (VA) include central venous catheters (temporary or tunneled), totally implantable ports, and arteriovenous fistulae (AVF) or grafts (AVG). Nontunneled catheters should be considered as the choice of VA for relatively short‐term treatments mainly in the inpatient settings. For long‐term treatments, ports and tunneled catheters should be considered because of lower rates of infections compared to nontunneled catheters. However, studies in hemodialysis (HD) patients have demonstrated significantly higher morbidity and mortality rates associated with the use of tunneled catheters as compared to AVF. Therefore, if TA is being considered for several years, AVG and AVF would be the preferred options of VA. Studies in HD population indicate far better outcomes with the use of AVF as compared to AVG. This article, as presented at the Therapeutic Apheresis Academy in September 2011, is an overview of the available VA options for TA based on indication and duration of treatment. Pros and cons of each option are mentioned briefly. Finally, for those considered for AVF placement for chronic TA, specific recommendations are made for the care of AVF based on our own experience at University of Virginia. J. Clin. Apheresis 2012. © 2012 Wiley Periodicals, Inc.
Impact of a transfusion‐related acute lung injury reduction strategy on apheresis platelet collections
Authors: Williams Dennis , Rao Marepalli , Carey Patricia
Published: April 2012

Background: Most blood centers in the US have implemented transfusion‐related acute lung injury (TRALI) mitigation strategies for apheresis platelet (AP) donations based on theoretical impact of donor loss. The aim of this study is to determine the actual impact of a TRALI mitigation strategy in a US blood center. Study Design and Methods: Daily collection events and resulting products were retrospectively obtained before and after implementation of a TRALI reduction strategy (HLA antibody testing female AP donors four or more pregnancies) for comparison. The retention rate of reassigned donors was determined by reviewing whole blood (WB) and/or apheresis red blood cell (AR) donations post reassignment. Data were obtained to compare donor frequency and split rate from reassigned (historical data) and new AP donors. Results: Mean daily collections (27.7 vs. 30.0) and total products (12,211 vs. 12,957) were significantly higher after implementation, but the number of products/collection event was lower (1.49 vs. 1.40). Mean collections/donor/year (4.0 vs. 1.8) and split rate (36% vs. 27%) were historically higher for reassigned (n = 45) versus new AP donors (n = 1,090). Seventy‐three of 112 donors (65%) testing positive for HLA antibodies returned for WB or AR donations, 31 of 45 (69%) active AP donors returned. Conclusions: Donor loss may not be adequate to estimate impact on AP inventory, as donation characteristics may differ between new donors and those reassigned. We show successful implementation of a TRALI mitigation strategy by increasing collection goals and AP donor recruitment efforts beyond donor loss. Retaining the majority of reassigned donors is feasible. J. Clin. Apheresis 2012. © 2012 Wiley Periodicals, Inc.
The dynamics of the calcium‐induced chain–chain association in the polyuronate systems
Authors: Plazinski Wojciech , Drach Mateusz
Published: April 2012

The calcium‐induced formation of strong, hydrophilic gels is the important feature of polyuronates, connected with most of their practical applications. The insight into the molecular details of gelling process dynamics is hardly feasible for both experimental and theoretical methods. Here, the application of the transition path sampling method for studying this problem is reported; the focus was on the poly(α‐L‐guluronate) systems, treated as the representative for all polyuronate‐containing systems. The results allowed for identifying several distinct local minima of the free energy lying on the transition paths and visited by the system during the process of chain–chain association. These minima usually correspond to the intermediate structures in which the water molecules bridge calcium ion and carboxyl groups. This work emphasizes the importance of water and provides more complete understanding of the calcium binding by the polyuronate chains. © 2012 Wiley Periodicals, Inc.
Benzoxaborole antimalarial agents. Part 3: design and syntheses of (carboxy‐13C‐3,3‐2H2)‐labeled and (3‐14C)‐labeled 7‐(2‐carboxyethyl)‐1,3‐dihydro‐1‐hydroxy‐2,1‐benzoxaboroles
Authors: Zhang Yong‐Kang , Plattner Jacob J. , Easom Eric E. , Liu Liang , Retz Daniel M. , Ge Min , Zhou Hui‐Hong
Published: April 2012

Two new isotopically labeled compounds, (carboxy‐13C‐3,3‐2H2)‐7‐(2‐carboxyethyl)‐1,3‐dihydro‐1‐hydroxy‐2,1‐benzoxaborole (2) and (3‐14C)‐7‐(2‐carboxyethyl)‐1,3‐dihydro‐1‐hydroxy‐2,1‐benzoxaborole (3), were designed and synthesized to support the preclinical development studies of a potential new antimalarial agent, 7‐(2‐carboxyethyl)‐1,3‐dihydro‐1‐hydroxy‐2,1‐benzoxaborole (1). Copyright © 2012 John Wiley & Sons, Ltd.
Comparison of pulsed and pseudocontinuous arterial spin‐labeling for measuring CO2‐induced cerebrovascular reactivity
Authors: Tancredi Felipe B. , Gauthier Claudine J. , Madjar Cécile , Bolar Divya S. , Fisher Joseph A. , Wang Danny J.J. , Hoge Richard D.
Published: April 2012

Purpose:

To compare the performance of pulsed and pseudocontinuous arterial spin‐labeling (PASL and pCASL) methods in measuring CO2‐induced cerebrovascular reactivity (CVR).

Materials and Methods:

Subjects were scanned using both ASL sequences during a controlled hypercapnia procedure and visual stimulation. CVR was computed as the percent CO2‐induced increase in cerebral blood flow (Δ%CBF) per mmHg increase in end‐tidal PCO2. Visually evoked responses were expressed as Δ%CBF. Resting CBF and temporal signal‐to‐noise ratio were also computed. Regionally averaged values for the different quantities were compared in gray matter (GM) and visual cortex (VC) using t‐tests.

Results:

Both PASL and pCASL yielded comparable respective values for resting CBF (56 ± 3 and 56 ± 4 mL/min/100g) and visually evoked responses (75 ± 5% and 81 ± 4%). Values of CVR determined using pCASL (GM 4.4 ± 0.2, VC 8 ± 1 Δ%CBF/mmHg), however, were significantly higher than those measured using PASL (GM 3.0 ± 0.6, VC 5 ± 1 Δ%CBF/mmHg) in both GM and VC. The percentage of GM voxels in which statistically significant hypercapnia responses were detected was also higher for pCASL (27 ± 5% vs. 16 ± 3% for PASL).

Conclusion:

pCASL may be less prone to underestimation of CO2‐induced flow changes due to improved label timing control. J. Magn. Reson. Imaging 2012;36:312–321. © 2012 Wiley Periodicals, Inc.
Copula‐based spatio‐temporal patterns of precipitation extremes in China
Authors: Zhang Qiang , Li Jianfeng , Singh Vijay P. , Xu Chong‐Yu
Published: April 2012

Daily precipitation data from 590 stations in China covering a period of 1960–2005 are analysed using copulas, the modified Mann–Kendall (MK) trend test and linear regression. Changing characteristics of eight precipitation indices are investigated in both time and space. Results indicate that (1) the regions west of 100°E, particularly northwest China, exhibit a wetting tendency as reflected by increasing/decreasing number of consecutive rain/non‐rain days; (2) the drying tendency is observed mainly in the regions covered by the Yellow River basin, the Huaihe River basin, and the Haihe River basin, and relatively moderate changes in precipitation indices are found in northeast China; (3) precipitation extremes are intensifying in the regions east of 100°E, particularly in case of south China, specifically the lower Yangtze River basin, the southeast rivers and the Pearl River basin. The intensification of precipitation extremes in south China is mirrored mainly by the decreasing number of rain days and increasing number of consecutive non‐rain days. Besides an increasing percentage of P90 to the annual total precipitation, (4) the intensification of precipitation extremes has the potential to increase the probability of occurrence of natural hazards, particularly floods and droughts. The spatial distribution of flood‐ and drought‐affected crop areas is in agreement with that of precipitation extremes, showing considerable impacts of precipitation extremes on meteor‐hydrological hazards. An increasing number of consecutive non‐rain days in south China will cause a higher risk of droughts. The regions east of 100°E are heavily populated and are economically developed. Food security, water security, and sustainable socioeconomy in China urgently call for effective water resource management policy. Copyright © 2012 Royal Meteorological Society
An assessment of changes in seasonal and annual extreme rainfall in the UK between 1961 and 2009
Authors: Jones Mari R. , Fowler Hayley J. , Kilsby Christopher G. , Blenkinsop Stephen
Published: April 2012

There is a growing body of evidence supporting the Intergovernmental Panel on Climate Change's contestation that changes to hydrological extremes as a result of anthropogenic climate change are likely. There is also a growing level of concern among water resource managers about the nature of these changes and how we might adapt our behaviour to accommodate them. In particular, extreme multi‐day rainfall events have been a significant contributing factor to the severe flood events of recent years.

Here we provide an updated study of extreme rainfall in the UK, focussing on changes to seasonal and annual maxima over the period 1961‐2009. We employ regional frequency analysis to examine changes in the magnitude of estimated return periods obtained from generalized extreme value distribution curves. Return period estimates are analysed using both the full record and using 10 year intervals to determine the relative importance of natural variability and long‐term changes in extreme rainfall distribution.

The magnitude of changes in estimated return periods are spatially varied, and dominated in northern and western parts of the UK by a periodic forcing such as the North Atlantic Oscillation (NAO), superimposed on normal seasonal fluctuations. In contrast, seasonality has the greatest influence on event magnitude in the south and east. We confirm that previously reported increases in spring and autumn extreme rainfall events have continued. Similarly, longer duration winter events have continued to increase in intensity, with a decrease in return period estimate from a 25‐year to around a 5‐year event over the full 50 years of record in parts of Scotland and Southwest England. In contrast, short‐duration summer rainfall events have continued to decline in intensity, whereas longer duration events appear to be increasing in intensity. These results may have significant implications for flood defence design and planning, as well as to agricultural practices which may be sensitive to extreme rainfall. Copyright © 2012 Royal Meteorological Society
Differentiation of self and its relation to work stress and work satisfaction
Authors: Cavaiola Alan A. , Peters Callandra , Hamdan Nadya , Lavender Neil J.
Published: April 2012

This study examines the relation of differentiation of self in the workplace to work stress and work satisfaction among individuals working in various employment settings. Family theorist Murray Bowen (1976, 1978) defined differentiation as encompassing one's ability to attain a mature balance between autonomy and intimacy within relationships. The purpose of this study was to determine whether better levels of differentiation would translate into better workplace relationships that would reflect in greater job satisfaction and lower perceived stress levels. The Emotional Reactivity, Emotional Cutoff, and Fusion subscales of the Differentiation of Self Inventory (Skowron & Friedlander, 1998) and the Workplace Differentiation Inventory developed by the authors assessed differentiation of self in the workplace. As hypothesized, participants who scored as more highly differentiated on both scales reported greater overall job satisfaction and lower interpersonal stress. Researchers found significant positive correlations between the subscales of the Differentiation of Self Inventory and the Workplace Differentiation Inventory, which suggests that workers tend to respond to interpersonal workplace situations in similar ways as their responses to other relationships. Researchers found significant gender differences, with women reporting more Emotional Reactivity and Fusion than men do. The authors use Bowen's theory of differentiation in discussing these results.
Maximum entropy and time‐domain Kramers–Kronig phase retrieval approaches are functionally equivalent for CARS microspectroscopy
Authors: Cicerone Marcus T. , Aamer Khaled A. , Lee Young Jong , Vartiainen Erik
Published: April 2012

Phase retrieval methods are used to recover Raman spectra from multiplex and broadband coherent anti‐Stokes Raman spectroscopy signals. Two methods are in widespread use, one based on maximum entropy, and one based on a modified time‐domain Kramers–Kronig method. Here we compare these methods with respect to their ability to faithfully and robustly recover Raman spectra from coherent anti‐Stokes Raman spectroscopy spectra simulated to reproduce a range of scenarios expected for experimental data and their efficiency. We find that the time‐domain Kramers–Kronig and maximum entropy approaches perform in functionally equivalent ways, having only minor differences between them. Published 2012. This article is a US Government work and is in the public domain in the USA.
In vitro antioxidant synergism and antagonism between food extracts can lead to similar activities in H2O2‐induced cell death, caspase‐3 and MMP‐2 activities in H9c2 cells
Authors: Wang Sunan , Meckling Kelly A , Marcone Massimo F , Kakuda Yukio , Proulx Amy , Tsao Rong
Published: April 2012

BACKGROUND: The cardio‐health‐promoting activity of some foods may be due to their specific antioxidant content. The antioxidant activity of a mixture of plant extracts has been shown to differ from the activity of the individual extracts. As a result, the activity of the mixture can be described as synergistic, antagonistic or additive. This in vitro study evaluated the relationship between the in vitro antioxidant capacity of mixtures and their bioactivity when cardiomyocytes (H9c2) were challenged with H2O2.

RESULTS: A mixture of raspberry and adzuki bean extracts produced a synergistic response and a mixture of broccoli and soybean extracts produced an antagonistic response in chemical‐based antioxidant assays. When these extracts were tested in cell cultures, individually and in mixtures, the mixture of raspberry and adzuki bean protected the cardiomyocytes from H2O2‐induced cell damage significantly better than the individual extracts. Conversely, the mixture of broccoli and soybean extracts was less effective in protecting H9c2 cells. The synergistic and antagonistic effects of the mixtures in protecting cell damage were brought about by enhanced or reduced ability in attenuating caspase‐3 and matrix metalloproteinase‐2 activities elevated by H2O2.

CONCLUSION: Food mixtures with synergistic antioxidant activity and protective property against reactive oxygen species‐induced cell death can potentially be incorporated into novel functional foods or beverages with optimum health benefit. The antagonistic effect of food mixtures can be a health concern and thus should be avoided. Copyright © 2012 Society of Chemical Industry
Effect of neckband color on survival and recovery rates of Ross's geese
Authors: Caswell Jason H. , Alisauskas Ray T. , Leafloor James O.
Published: April 2012

Colored neckbands are known to reduce survival rates of geese, but the underlying cause for lower survival is unknown. We tested the hypothesis that hunters cause this lower survival rate by actively targeting neckbanded geese. We evaluated this hypothesis by estimating recovery and survival rates of adult Ross's geese (Chen rossii) at both Queen Maud Gulf (QMG) and McConnell River (MCR) Migratory Bird Sanctuaries carrying each of 3 marker combinations: 1) standard legbands (n = 11,321) for basic estimates of recovery and survival rates; 2) standard legbands and colored neckbands (n = 8,587) as the marked sample most detectable and thus most vulnerable to targeting by hunters; and 3) standard legbands and white neckbands (n = 6,501) as the sample exposed to the general risks of carrying neckbands but only minimally detectable by hunters, if at all. Recovery rates (±95% CL) of Ross's geese were lowest for those marked with legbands (0.024 ± 0.004 at MCR and 0.016 ± 0.003 at QMG) and highest for those marked with neckbands, regardless of neckband color (0.042 ± 0.005 at MCR and 0.035 ± 0.005 at QMG). Survival rates (±95% CL) were indistinguishable between geese marked with color and white neckbands (0.54 ± 0.08 at MCR and 0.52 ± 0.08 at QMG), but lower than those marked with standard legbands only (0.72 ± 0.17 at MCR and 0.83 ± 0.23 at QMG). Geese marked with white neckbands were recovered at rates similar to those marked with color neckbands, suggesting that hunter selection of color neckbands did not contribute greatly to lower survival rates in neckbanded geese. Rather, results suggest that neckbanded geese, regardless of neckband visibility, are more vulnerable to hunters than are geese marked only with legbands. © 2012 The Wildlife Society.
Synthesis of End‐capped Regioregular Poly(3‐hexylthiophene)s via Direct Arylation
Authors: Wang Qifeng , Wakioka Masayuki , Ozawa Fumiyuki
Published: April 2012

The synthesis of regioregular head‐to‐tail poly(3‐hexylthiophene)s capped with aryl groups (Ar‐HT‐P3HTs) has been accomplished by palladium‐catalyzed polycondensation of 2‐bromo‐3‐hexylthiophene (1) via direct arylation. A variety of aryl groups are installed at the initiated end in 86%–98% selectivity using aryl bromides and iodides as capping agents. The polymerization proceeds via a two‐stage process. Before monomer 1 is consumed, the competitive formation of end‐capped and non‐capped HT‐P3HTs is operative, where the molecular weight increases linearly with monomer conversion. After 1 is consumed, the resulting polymers are coupled with each other to afford highly end‐capped HT‐P3HTs.
A new defect‐correction method for the stationary Navier–Stokes equations based on local Gauss integration
Authors: Huang Pengzhan , He Yinnian , Feng Xinlong
Published: April 2012

A new defect‐correction method for the stationary Navier–Stokes equations based on local Gauss integration is considered in this paper. In both defect step and correction step, a locally stabilized technique based on the Gaussian quadrature rule is used. Moreover, stability and convergence of the presented method are deduced. Finally, we provide some numerical experiments to show good stability and effectiveness properties of the presented method. Copyright © 2012 John Wiley & Sons, Ltd.
Structure and NMR spectra of cyclophanes with unsaturated bridges (cyclophenes)
Authors: Dodziuk Helena , Demissie Taye Beyene , Ruud Kenneth , Szymański Sławomir , Jaźwiński Jarosław , Hopf Henning
Published: April 2012

The calculated structures of several known and hypothetical cyclophanes with ethylene bridges (cyclophenes) are reported together with experimental and calculated values of their NMR parameters. Of the exchange‐correlation functionals and basis sets used in this work, only the ωB97X‐D/6‐311++G(2d,2p) and ωB97X‐D/cc‐pVQZ yielded values of the Csp3–Csp3 bond length close to the experimental data, although significant differences still remain. As far as the NMR parameters are concerned, except for close‐lying signals, chemical shifts and coupling constants calculated at the ωB97X‐D/cc‐pVQZ level reproduce in most cases the experimental trends. Contrary to the calculations of geometries, an agreement between the values of the NMR parameters obtained at ωB97X‐D/cc‐pVQZ level and the experimental ones is the poorest compared with that of the ωB97X‐D/6‐311++G(2d,2p) one. Taking into account that the results of the different calculations show the same qualitative trends in most cases, we believe that they correctly describe the structure and properties of the hypothetical molecules studied here. Copyright © 2012 John Wiley & Sons, Ltd.
Hydro‐mechanical modeling of cohesive crack propagation in multiphase porous media using the extended finite element method
Authors: Mohammadnejad T. , Khoei A. R.
Published: April 2012

In this paper, a numerical model is developed for the fully coupled hydro‐mechanical analysis of deformable, progressively fracturing porous media interacting with the flow of two immiscible, compressible wetting and non‐wetting pore fluids, in which the coupling between various processes is taken into account. The governing equations involving the coupled solid skeleton deformation and two‐phase fluid flow in partially saturated porous media including cohesive cracks are derived within the framework of the generalized Biot theory. The fluid flow within the crack is simulated using the Darcy law in which the permeability variation with porosity because of the cracking of the solid skeleton is accounted. The cohesive crack model is integrated into the numerical modeling by means of which the nonlinear fracture processes occurring along the fracture process zone are simulated. The solid phase displacement, the wetting phase pressure and the capillary pressure are taken as the primary variables of the three‐phase formulation. The other variables are incorporated into the model via the experimentally determined functions, which specify the relationship between the hydraulic properties of the fracturing porous medium, that is saturation, permeability and capillary pressure. The spatial discretization is implemented by employing the extended finite element method, and the time domain discretization is performed using the generalized Newmark scheme to derive the final system of fully coupled nonlinear equations of the hydro‐mechanical problem. It is illustrated that by allowing for the interaction between various processes, that is the solid skeleton deformation, the wetting and the non‐wetting pore fluid flow and the cohesive crack propagation, the effect of the presence of the geomechanical discontinuity can be completely captured. Copyright © 2012 John Wiley & Sons, Ltd.
A multilaminate constitutive model accounting for anisotropic small strain stiffness
Authors: Schädlich B. , Schweiger H. F.
Published: April 2012

In this paper an extension of existing multilaminate soil models is presented, which can account for inherent and stress‐induced cross‐anisotropic elasticity in the small strain range and its dependency on the load history. In the multilaminate framework, material behaviour is formulated on a number of local planes in each stress point, and the macroscopic response of the material is obtained by integration of the local contributions. Strain‐induced anisotropy, which adds to the stiffness anisotropy inherently present in the material, is therefore intrinsically taken into account. Micro–macro relations between local parameters on plane level and global parameters on macroscopic level are obtained by the spectral decomposition of the global elastic compliance matrix. The model is implemented into a finite‐element code, and model predictions are compared with experimental data of triaxial tests on different soils involving small and large load cycles. The importance of cross‐anisotropic elasticity within the small strain range for predicting ground deformations in geotechnical boundary value problems is discussed at the example of an excavation problem. Copyright © 2012 John Wiley & Sons, Ltd.
Isokinetic relationships for SNAr reactions in different solvents
Authors: Vlasov Vladislav M. , Kornakova Tatyana A.
Published: April 2012

On the basis of the changes of the activation parameters and δ∆S≠ and the statistically significant isokinetic and compensation temperatures, Tiso and Tcomp, for the SNAr reactions of the benzene derivatives with anionic and neutral nucleophiles at their structural variations in different solvents, the general isokinetic relationship versus (Tiso − Tcomp) ⋅ δ∆S≠ was found. The existence of this isokinetic relationship for a series of SNAr reactions suggests the possibility to predict the Tiso value or to interpret it when it is experimentally determined. Copyright © 2012 John Wiley & Sons, Ltd.
Bis‐hydrophilic and functional triblock terpolymers based on polyethers: Synthesis and self‐assembly in solution
Authors: Barthel Markus J. , Babiuch Krzysztof , Rudolph Tobias , Vitz Jürgen , Hoeppener Stephanie , Gottschaldt Michael , Hager Martin D. , Schacher Felix H. , Schubert Ulrich S.
Published: April 2012

A well‐defined triblock terpolymer, poly(ethylene glycol)‐block‐poly(allyl glycidyl ether)‐block‐poly(tert‐butyl glycidyl ether) (PEG‐b‐PAGE‐b‐Pt‐BGE), with a narrow molar mass distribution has been synthesized by sequential living anionic ring‐opening polymerization. Afterward, the PAGE block was modified via thiol‐ene chemistry and different sugar moieties or cysteine as a model compound for peptides could be covalently attached to the polymer backbone. The solution self‐assembly of the obtained bis‐hydrophilic triblock terpolymers in aqueous media has been studied in detail by turbidimetry, dynamic light scattering, and transmission electron microscopy (TEM and cryo‐TEM). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Surface promoted redox cationic polymerization of epoxy monomers catalyzed by silver salts
Authors: Farrell David J. , McArdle Ciaran , Doherty Michael , Kelly John M.
Published: April 2012

The first example of a one‐component room temperature curing redox cationic polymerization for metal surfaces is described. A weak Lewis acid (Ag+) is used as a latent catalyst to likely generate a much stronger one (Fe2+/Fe3+ or Cu2+) at the bond line interface. Such a process has been demonstrated for 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexane carboxylate using [Ag(1,5‐cyclooctadiene)2]SbF6 with the polymerization monitored most conveniently by fourier transform infrared spectroscopy (FTIR). This system, however, demonstrates a relatively low adhesive strength even following curing for 24 h. Higher bond strengths were achieved using mixtures with other cationically polymerizable monomers (vinyl ethers, tetrahydrofuran (THF), oxetanes). Factors considered for optimization of the rates and extent of reaction were the concentrations of a vinyl ether comonomer and [AgLn]X, the nature of the counterion (X), and of the ligand (L). The performance of the Ag(I) system was compared to that of Cu(I) and various organic cations and the activity of the redox cationic polymerizations on a range of metallic (iron, copper, and aluminium) and nonmetallic (glass and various plastics) substrates was studied. A relatively high glass transition temperature was recorded for the optimized model system and the bonding strength at elevated temperature (150–200 °C) following a room temperature cure was found to be attractive compared to selected model anaerobic acrylate compositions. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Main‐chain functionalization of poly(L‐lactide) with pendant unsaturations
Authors: Olsén Peter , Odelius Karin , Albertsson Ann‐Christine
Published: April 2012

Main‐chain‐functionalized poly(L‐lactide) (PLLA) with pendant unsaturations was synthesized through a one‐pot postpolymerization procedure with the PLLA homopolymer as the starting material. The material was functionalized through α‐hydrogen abstraction by a sterically hindered strong base, lithium diisopropylamide, followed by the addition of an acid chloride. Two different acid chlorides were examined, lauroyl chloride as a concept electrophile and oleoyl chloride to provide the pendant unsaturations. The semisolvated system, together with branching reactions from the alpha position of the acid chloride, yielded a high molar amount of the incorporated reactant in the material. The unsaturations were preserved under the chosen conditions and the material exhibited surfactant‐like properties in blends with oleic acid and PLLA. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis and characterization of poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐grafted‐poly(acrylonitrile) via single electron transfer–living radical polymerization process
Authors: Hu Xin , Li Junjie , Li Huayi , Zhang Zhicheng
Published: April 2012

Preparation of functional fluoromaterials through chemical modification of traditional fluoropolymers has been recognized as an economic and convenient strategy to expand the application areas of fluoropolymers. Poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐grafted‐polyacrylonitrile (P(VDF‐co‐CTFE)‐g‐PAN) has been successfully synthesized via single electron transfer–living radical polymerization (SET–LRP) process initiated with macroinitiator P(VDF‐co‐CTFE) in the presence of trace amount of Cu(0)/tris(2(dimethylamino)ethyl)amine (Me6‐TREN) in dimethyl sulfoxide (DMSO) at ambient temperature. The typical side reactions happened on P(VDF‐co‐CTFE) induced by the nitrogen‐containing solvents and high reaction temperature in atom transfer radical polymerization process could be avoided in SET–LRP process by using the mild reaction conditions. Well‐controlled polymerization features were observed under varied reaction conditions including the different reaction temperature, catalyst concentration, as well as monomer amount in feed. An induction period of 0.5–1.0 h in the polymerization procedure was observed at low temperature, which may be attributed to the Cu2O from the surface of the Cu(0) powder. When Cu(0) catalyst is activated, the introduction period is eliminated. The polymerization rates were decelerated by adding excessive Me6‐TREN for the formation of more stable CuCl2/(Me6‐TREN)2. The structure of P(VDF‐co‐CTFE)‐g‐PAN was demonstrated by FTIR, NMR, DSC, and TGA. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Protein dynamics viewed by hydrogen exchange
Authors: Skinner John J. , Lim Woon K. , Bédard Sabrina , Black Ben E. , Englander S. Walter
Published: April 2012

To examine the relationship between protein structural dynamics and measurable hydrogen exchange (HX) data, the detailed exchange behavior of most of the backbone amide hydrogens of Staphylococcal nuclease was compared with that of their neighbors, with their structural environment, and with other information. Results show that H‐bonded hydrogens are protected from exchange, with HX rate effectively zero, even when they are directly adjacent to solvent. The transition to exchange competence requires a dynamic structural excursion that removes H‐bond protection and allows exposure to solvent HX catalyst. The detailed data often make clear the nature of the dynamic excursion required. These range from whole molecule unfolding, through smaller cooperative unfolding reactions of secondary structural elements, and down to local fluctuations that involve as little as a single peptide group or side chain or water molecule. The particular motion that dominates the exchange of any hydrogen is the one that allows the fastest HX rate. The motion and the rate it produces are determined by surrounding structure and not by nearness to solvent or the strength of the protecting H‐bond itself or its acceptor type (main chain, side chain, structurally bound water). Many of these motions occur over time scales that are appropriate for biochemical function.
Structure‐based optimization of designed Armadillo‐repeat proteins
Authors: Madhurantakam Chaithanya , Varadamsetty Gautham , Grütter Markus G. , Plückthun Andreas , Mittl Peer R.E.
Published: April 2012

The armadillo domain is a right‐handed super‐helix of repeating units composed of three α‐helices each. Armadillo repeat proteins (ArmRPs) are frequently involved in protein–protein interactions, and because of their modular recognition of extended peptide regions they can serve as templates for the design of artificial peptide binding scaffolds. On the basis of sequential and structural analyses, different consensus‐designed ArmRPs were synthesized and show high thermodynamic stabilities, compared to naturally occurring ArmRPs. We determined the crystal structures of four full‐consensus ArmRPs with three or four identical internal repeats and two different designs for the N‐ and C‐caps. The crystal structures were refined at resolutions ranging from 1.80 to 2.50 Å for the above mentioned designs. A redesign of our initial caps was required to obtain well diffracting crystals. However, the structures with the redesigned caps caused domain swapping events between the N‐caps. To prevent this domain swap, 9 and 6 point mutations were introduced in the N‐ and C‐caps, respectively. Structural and biophysical analysis showed that this subsequent redesign of the N‐cap prevented domain swapping and improved the thermodynamic stability of the proteins. We systematically investigated the best cap combinations. We conclude that designed ArmRPs with optimized caps are intrinsically stable and well‐expressed monomeric proteins and that the high‐resolution structures provide excellent structural templates for the continuation of the design of sequence‐specific modular peptide recognition units based on armadillo repeats.
The evaluation and implementation of direct analysis in real time quadrupole time‐of‐flight tandem mass spectrometry for characterization and quantification of geniposide in Re Du Ning Injections
Authors: Li Yan‐Jing , Wang Zhen‐Zhong , Bi Yu‐An , Ding Gang , Sheng Long‐Sheng , Qin Jian‐Ping , Xiao Wei , Li Jia‐Chun , Wang Yong‐Xiang , Wang Xue
Published: April 2012

RATIONALE

The Direct Analysis in Real Time (DART) ionization source coupled with a quadrupole time‐of‐flight tandem mass spectrometry (Q‐TOF MS/MS) system has the capability to desorb analytes directly from samples from complex Chinese herbal preparations without sample cleanup or chromatographic separation.

METHODS

In this work, a method based on DART/Q‐TOF MS/MS has been developed for rapid determination of geniposide present in 'Re Du Ning Injections', a Chinese herbal preparation. The method has been evaluated for both qualitative and quantitative analysis of geniposide in Re Du Ning Injections.

RESULTS

Variables including polarity for ion detection, DART gas heater temperature, matrix effect and sample presentation speed were investigated. The quantitative method was validated with respect to linearity, sensitivity, repeatability, precision and accuracy by using both internal and external standards. A comparison of the results obtained using the DART‐based method was made with those obtained using a conventional High‐Performance Liquid Chromatography/Diode‐Array Detector (HPLC/DAD) by analyzing geniposide in four batches of Re Du Ning Injections.

CONCLUSIONS

The DART/Q‐TOF MS/MS‐based method provides a rapid, efficient and powerful method to analyze compounds from complex Traditional Chinese Medicines with limited sample preparation thus reducing time and complexity of quality control for those materials. Copyright © 2012 John Wiley & Sons, Ltd.
Static output feedback control for positive linear continuous‐time systems
Authors: Wang Cuihong , Huang Tianmin
Published: April 2012

This paper studies the problem of designing the static output feedback controller for the positive linear continuous‐time systems. On the basis of a system augmentation approach, a novel characterization on the stable condition of the closed‐loop system is firstly established. Then, a necessary and sufficient condition is given to ensure the existence of the desired static output feedback controller, and an iterative linear matrix inequality algorithm is presented to compute the feedback gain matrix. Finally, a numerical example is provided to illustrate the effectiveness of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.
Graph classes with given 3‐connected components: Asymptotic enumeration and random graphs
Authors: Giménez Omer , Noy Marc , Rué Juanjo
Published: April 2012

Consider a family
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of 3‐connected graphs of moderate growth, and let
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be the class of graphs whose 3‐connected components are graphs in
\documentclass{article}\usepackage{mathrsfs, amsmath, amssymb}\pagestyle{empty}\begin{document}\begin{align*}\mathcal{T}\end{align*}\end{document}. We present a general framework for analyzing such graphs classes based on singularity analysis of generating functions, which generalizes previously studied cases such as planar graphs and series‐parallel graphs. We provide a general result for the asymptotic number of graphs in
\documentclass{article}\usepackage{mathrsfs, amsmath, amssymb}\pagestyle{empty}\begin{document}\begin{align*}\mathcal{G}\end{align*}\end{document}, based on the singularities of the exponential generating function associated to
\documentclass{article}\usepackage{mathrsfs, amsmath, amssymb}\pagestyle{empty}\begin{document}\begin{align*}\mathcal{T}\end{align*}\end{document}. We derive limit laws, which are either normal or Poisson, for several basic parameters, including the number of edges, number of blocks and number of components. For the size of the largest block we find a fundamental dichotomy: classes similar to planar graphs have almost surely a unique block of linear size, while classes similar to series‐parallel graphs have only sublinear blocks. This dichotomy was already observed by Panagiotou and Steger [25], and we provide a finer description. For some classes under study both regimes occur, because of a critical phenomenon as the edge density in the class varies. Finally, we analyze the size of the largest 3‐connected component in random planar graphs. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 42, 438–479, 2013
Immunizing mobile ad hoc networks against collaborative attacks using cooperative immune model
Authors: Gong Tao , Bhargava Bharat
Published: April 2012

In this paper, a security problem of cooperative immunization against collaborative attacks such as blackhole attacks and wormhole attacks, in the mobile ad hoc networks such as the Worldwide Interoperability for Microwave Access (WiMAX) networks, was discussed. Because of the vulnerabilities of the protocol suites, collaborative attacks in the mobile ad hoc networks can cause more damages than individual attacks. In human immune system, nonselfs (i.e., viruses, bacteria and cancers etc.) can attack human body in a collaborative way and cause diseases in the human body. With the inspiration from the human immune system, a tri‐tier cooperative immune model was built to detect and eliminate the collaborative attacks (i.e., nonselfs) in the mobile ad hoc networks. ARM‐based Network Simulator (NS2) tests and probability analysis were utilized in the prototype for immune model to analyze and detect the attacks. Experimental results demonstrate the validation and effectiveness of the model proposed by minimizing the collaborative attacks and immunizing the mobile ad hoc networks. Copyright © 2012 John Wiley & Sons, Ltd.
Security assurance in wireless acoustic sensors via event forecasting and detection
Authors: Zhong Zhen , Zhao Chenglin , Pi Yiming , Wang Lingming
Published: April 2012

In this paper, we study the security assurance in application layer in wireless acoustic sensors via event forecasting and detection. In order to perform event forecasting and detection, we try to answer several challenging questions in acoustic signal research based on wireless acoustic sensors: (i) Are acoustic signals predictable? (ii) How are acoustic signals predicted? (iii) Are there any event‐forecasting applications for the security in wireless acoustic sensors? We study these questions based on Xbow acoustic sensors and demonstrate that real‐world acoustic signals are self‐similar, which means that they are predictable. We propose an acoustic signal prediction scheme using interval type‐2 fuzzy logic system (FLS). We show that a type‐2 fuzzy membership function (MF); that is, a Gaussian MF with uncertain mean is appropriate to model the acoustic signal strength. Two FLSs, a type‐1 FLS, and an interval type‐2 FLS are designed for signal strength forecasting. Furthermore, we propose a double sliding window scheme for event detection based on the forecasted signals. Simulation results show that the interval type‐2 FLS outperforms the type‐1 FLS in signal strength forecasting and the performance of event detection based on the forecasted signal from type‐2 FLS is much better than that based on type‐1 FLS. Copyright © 2012 John Wiley & Sons, Ltd.
A survey of code‐based change impact analysis techniques
Authors: Li Bixin , Sun Xiaobing , Leung Hareton , Zhang Sai
Published: April 2012

Software change impact analysis (CIA) is a technique for identifying the effects of a change, or estimating what needs to be modified to accomplish a change. Since the 1980s, there have been many investigations on CIA, especially for code‐based CIA techniques. However, there have been very few surveys on this topic. This article tries to fill this gap. And 30 papers that provide empirical evaluation on 23 code‐based CIA techniques are identified. Then, data was synthesized against four research questions. The study presents a comparative framework including seven properties, which characterize the CIA techniques, and identifies key applications of CIA techniques in software maintenance. In addition, the need for further research is also presented in the following areas: evaluating existing CIA techniques and proposing new CIA techniques under the proposed framework, developing more mature tools to support CIA, comparing current CIA techniques empirically with unified metrics and common benchmarks, and applying the CIA more extensively and effectively in the software maintenance phase. Copyright © 2012 John Wiley & Sons, Ltd.