bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Aminotetrazolyl Esters from Cyanogen Azide with Amino Esters
Authors: Joo Young‐Hyuk , Cho Soo Gyeong , Goh Eun Mee , Parrish Damon A. , Shreeve Jean'ne M.
Published: December 2012

Several α‐amino esters (and their hydrochloride salts) were treated with cyanogen azide at ambient temperature in a mixture of water and acetonitrile to form chiral 5‐aminotetrazole derivatives in good yields (47–69 %). The cyanogen azide was prepared from cyanogen bromide and sodium azide. Other functionalized α‐amino esters (cysteine, arginine, histidine, and serine) were formed in only trace amounts and were difficult to purify by column chromatography. All 5‐aminotetrazoles (i.e., 1–8) were characterized by IR spectroscopy, 1H, 13C, and 15N NMR spectroscopy, and elemental analysis. The structures of 3–7 were obtained by single‐crystal X‐ray structure analysis.
A stencil adaptive phase‐field lattice Boltzmann method for two dimensional incompressible multiphase flows
Authors: Shao J. Y. , Shu C. , Wu J. , Chew Y. T.
Published: December 2012

This paper presents a stencil adaptive phase‐field lattice Boltzmann method (LBM) for the simulation of two‐dimensional multiphase flows. In the phase‐field model, the interface is viewed as a layer with finite thickness where physical parameters vary steeply and continuously. In the present study, a phase‐field LBM is used. In this model, the Cahn–Hilliard equation can be correctly recovered by LBM without additional terms. The phase‐field LBM can easily resolve topology change and large deformation of an interface. The major challenge faced by the phase‐field model is to approach sharp interface limit within affordable computational loads. A natural solution is to supplement the phase‐field model with the adaptive mesh refinement technique. In fact, much effort has been devoted to alleviate this issue with regards to Navier–Stokes solvers. However, in the realm of LBM, few works can be found in the literature. The present work is the first endeavour to incorporate the stencil adaptive technique into the phase‐field LBM. The proposed method enables high resolution of interface with considerable savings in grid points. In addition, owing to the symmetric structure of two stencils used, the present adaptive phase‐field LBM is freed from complicated spatial and temporal interpolation and modification of the collision term. First, the accuracy, efficiency and convergence of this method are testified through the simulation of a stationary bubble. Furthermore, its ability to probe several types of interfacial dynamics including bubbly flows and contact line problems has also been demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.
On the Catalytic Degradation in Fuel Cell Power Supplies for Long‐Life Mobile Field Sensors
Authors: Thangavelautham J. , Dubowsky S.
Published: December 2012

Important tasks such as environment monitoring require field devices such as sensors that can operate for long durations. Current power supply technologies such as batteries limit many applications. Fuel cells are a promising alternative to batteries because they can have much higher energy densities. However, their lives may be short due to catalyst degradation. Here, a simplified model of proton exchange membrane (PEM) fuel cell catalyst degradation is applied to small fuel cells. The model focuses on the combined effects of catalyst dissolution and migration. The effect of migration on catalyst degradation is found to be substantial and this has not been accounted for in previous models. The model considers the effect of field conditions such as varying power demands, temperature and humidity, and predicts the catalyst life of the fuel cell and its power output. The predicted life is a proposed metric that can quantify the relative importance and effect of field conditions on the catalyst particularly for the design and control of fuel cell power supplies. Experiments are presented that support the model. This model is applied to a study on field sensors and results suggests unless PEM fuel cells are isolated from damaging field conditions, they will have short lives.
Optimization of a High Temperature PEMFC micro‐CHP System by Formulation and Application of a Process Integration Methodology
Authors: Arsalis A. , Nielsen M. P. , Kær S. K.
Published: December 2012

A 1 kWe micro combined heat and power (CHP) system based on high temperature proton exchange membrane fuel cell (PEMFC) technology is modeled and optimized by formulation and application of a process integration methodology. The system can provide heat and electricity for a single‐family household. It consists of a fuel cell stack, a fuel processing subsystem, heat exchangers, and balance‐of‐plant components. The optimization methodology involves system optimization attempting to maximize the net electrical efficiency, and then by use of a mixed integer nonlinear programming (MINLP) problem formulation, the heat exchange network (HEN) annual cost is minimized. The results show the high potential of the proposed model since high efficiencies are accomplished. The net electrical efficiency and total system efficiency, based on lower heating value (LHV), are 35.2% and 91.1%, respectively. The minimized total annual cost of the HEN is $8,147 year–1.
Experimental Study of an SOFC Stack Operated With Autothermally Reformed Diesel Fuel
Authors: Rautanen M. , Halinen M. , Noponen M. , Koskela K. , Vesala H. , Kiviaho J.
Published: December 2012

A 500 W SOFC stack provided by Topsoe Fuel Cells A/S was run with reformed diesel fuel for 1,200 h. Diesel fuel used was Swedish Environmental Class 1 containing <10 ppm of sulfur. The fuel was reformed with an autothermal reformer (ATR). The reformer consisted of a mixing chamber and a reactor chamber containing a noble metal catalyst provided by SüdChemie. The reformer used the diesel fuel without any pre‐treatment such as sulfur adsorbent. The reformer unit was able to achieve high conversion of reactants with only ppm levels of higher hydrocarbons at the reformer outlet. Particulate emissions of the reformer were measured to be 30 μg m–3, a very low value even below daily exposure limits in ambient air set by the European Comission directives. The stack was first run with 3% humidified H2 + N2 fuel to obtain baseline performance and then switched to reformate. Diesel reformate was found not to induce significantly more long‐term degradation on the stack compared to hydrogen case. However, an initial degradation of about 20 mV cell–1 was observed during the first 150 h on diesel fuel reformate. This could be an indication of a poisoning mechanism taking place, but needs further research to be verified.
Thermo‐Mechanical Response of Fuel Cell Electrodes: Constitutive Model and Application in Studying the Structural Response of Polymer Electrolyte Fuel Cell
Authors: Poornesh K. K. , Xiao Y. , Cho C.
Published: December 2012

The characterization of the mechanical properties of fuel cell electrodes through the experimental techniques is a complex task due to the low thickness, constituents' heterogeneous composition, and fragile nature of the film. We present a preliminary investigation on the thermomechanical response of fuel cell catalyst layer (CL) obtained through the numerical experiment. Since the Nafion ionomer is one of the constituents' of the CL, a modified micromechanically motivated viscoplastic model is adopted to characterize the Nafion ionomer in terms of reduced density factor to account for the void content. The catalyst agglomerates are taken as inclusions in the ionomer matrix to form a composite unit which is used to plot the true stress–true strain response. Practicality of this work is tested by implementing the electrode layer as a separate component in the single fuel cell unit cell model. A remarkable difference in the magnitude of stress levels in the membrane is observed under thermal and hydrated conditions with the presence and absence of electrode layer in the simulation domain. The present work will assist in improved understanding of the localized stress distribution in the membrane, which is essential to understand its mechanical endurance.
Effects of olanzapine on 31P MRS metabolic markers in schizophrenia
Authors: Nenadic Igor , Dietzek Maren , Langbein Kerstin , Rzanny Reinhard , Gussew Alexander , Reichenbach Jürgen R. , Sauer Heinrich , Smesny Stefan
Published: December 2012

Antipsychotic drug action might include mechanisms related to normalising phospholipid and high‐energy metabolism. We applied brain metabolic imaging with 31P magnetic resonance spectroscopy (31P MRS) and two‐dimensional chemical shift imaging to assess changes of metabolism of phospholipids and high‐energy phosphates in schizophrenia patients at baseline (four antipsychotic‐naïve and three off antipsychotics) and at follow‐up, after 6 weeks of treatment with olanzapine. Results indicate a significant increase of adenosine‐triphosphate (ATP) in the right inferior temporal cortex and a trend towards ATP decrease in the left cerebellum. This suggests a shift in high‐energy phosphates (rather than phospholipids), possibly related to normalisation of functioning in these areas. Copyright © 2012 John Wiley & Sons, Ltd.
Amyloid beta accumulation in HIV‐1‐infected brain: The role of the blood brain barrier
Authors: András Ibolya E. , Toborek Michal
Published: December 2012

In recent years, we face an increase in the aging of the HIV‐1‐infected population, which is not only due to effective antiretroviral therapy but also to new infections among older people. Even with the use of the antiretroviral therapy, HIV‐associated neurocognitive disorders represent an increasing problem as the HIV‐1‐infected population ages. Increased amyloid beta (Aβ) deposition is characteristic of HIV‐1‐infected brains, and it has been hypothesized that brain vascular dysfunction contributes to this phenomenon, with a critical role suggested for the blood‐brain barrier in brain Aβ homeostasis. This review will describe the mechanisms by which the blood‐brain barrier may contribute to brain Aβ accumulation, and our findings in the context of HIV‐1 infection will be discussed. © 2012 IUBMB Life, 65(1):43–49, 2013
Noninvasive blood glucose monitoring during oral intake of different sugars with optical coherence tomography in human subjects
Authors: Zhang Yuqing , Wei Huajiang , Yang Hongqin , He Yonghong , Wu Guoyong , Xie Shusen , Zhu Zhenguo , He Ruoyu
Published: December 2012

The potential of OCT applied to noninvasive blood glucose monitoring has attracted significant efforts. In this work we investigated the feasibility of OCT in monitoring blood glucose during oral intake of different sugars in humans. Five groups of experiments were performed, in which different sugars were used. The OCT signal slope (OCTSS) changed with variation of blood glucose concentration (BGC). A good correlation between OCTSS and BGC was observed in these experiments. The averaged correlation coefficients R between OCTSS and BGC are 0.900, 0.836, 0.895 and 0.884, corresponding to oral administration of glucose, fructose, sucrose and mixed sugar, respectively. Our studies demonstrated the capability and accuracy of the OCT system in monitoring BGC noninvasively and it could become a powerful tool in daily blood glucose monitoring for patients. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Immunohistochemistry, histopathology and infrared spectral histopathology of colon cancer tissue sections
Authors: Kallenbach‐Thieltges Angela , Großerüschkamp Frederik , Mosig Axel , Diem Max , Tannapfel Andrea , Gerwert Klaus
Published: December 2012

During the past years, many studies have shown that infrared spectral histopathology (SHP) can distinguish different tissue types and disease types independently of morphological criteria. In this manuscript, we report a comparison of immunohistochemical (IHC), histopathological and spectral histopathological results for colon cancer tissue sections. A supervised algorithm, based on the “random forest” methodology, was trained using classical histopathology, and used to automatically identify colon tissue types, and areas of colon adenocarcinoma. The SHP images subsequently were compared to IHC‐based images. This comparison revealed excellent agreement between the methods, and demonstrated that label‐free SHP detects compositional changes in tissue that are the basis of the sensitivity of IHC. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and In VitroAntibacterial Activity of Novel Steroidal (6R)‐Spiro‐1,3,4‐thiadiazoline Derivatives
Authors: Khan Salman A. , Asiri Abdullah M.
Published: December 2012

Novel steroidal (6R)‐spiro‐1,3,4‐thiadiazoline derivatives were synthesized by the cyclization of steroidal thiosemicarbazones with acetic anhydride, screened in vitro against antibacterial activity using disc‐diffusion method and the minimum inhibitory concentration. The results showed that steroidal thiadiazoline derivatives exhibited better antibacterial activity than the steroidal thiosemicarbazone derivatives. Chloro and acetoxy substituents on the 3β‐position of the steroidal thiadiazoline ring increased the antibacterial activity. Among all the compounds, compound 7 and 8 were found better inhibitors of both types of bacteria (Gram‐positive and Gram‐negative) as compared to the respective drug amoxicillin. All the synthesized compounds were well characterized by spectroscopic methods such as IR, 1H‐NMR, 13C‐NMR mass, and elemental analysis and their stereochemistry was also discussed.
Silica‐Supported Perchloric Acid (HClO4–SiO2): An Efficient Catalyst for One‐Pot Synthesis of Functionalized Tetrahydropyrimidine Derivatives
Authors: Khan Abu T. , Khan Md. Musawwer , Das Deb Kumar , Lal Mohan
Published: December 2012

HClO4–SiO2 has been found to be a highly efficient catalyst for the synthesis of substituted tetrahydropyrimidine and bis‐tertahydropyrimidine derivatives in good to excellent yields involving the reaction of dimethyl acetylenedicarboxylate, amines/diamines, and formaldehyde. One‐pot, atom economy, high‐bond forming efficiency, environmentally benign, good yields, and mild reaction conditions are some of the salient features of this multicomponent reaction.
Three‐Component One‐Pot Synthesis of 4‐Aryl‐2,3‐dihydropyrimido[1,2‐a]benzimidazol‐2‐ones Catalyzed by l‐Proline
Authors: Sheibani Hassan , Saidi Kazem , Lakaei Molod
Published: December 2012

An efficient chemoselective synthesis of 4‐aryl‐2,3‐dihydropyrimido[1,2‐a]benzimidazol‐2‐one derivatives from three‐component reactions of 2‐aminobenzimidazole, Meldrum's acid, and aldehydes via [3+3] atom combination is described. The reaction occurs in different conditions such as in DMF as solvent at reflux and in the presence of l‐proline as base catalyst.
Facile Regioselective Synthesis of 5‐Hydroxy‐4,5‐dihydroisoxazoles from Acetylenic Ketones
Authors: Xie Meihua , Li Ming , Liu Changqing , Zhang Jitan , Feng Chengyou
Published: December 2012

5‐Hydroxy‐4,5‐dihydroisoxazoles were synthesized conveniently in good yields by tandem conjugate addition‐cyclization reaction of acetylenic ketones and hydroxylamine hydrochloride salt.
One‐Pot Three‐Component Mild Synthesis of 2‐Aryl‐3‐(9‐alkylcarbazol‐3‐yl)thiazolidin‐4‐ones
Authors: Li Zheng , Zhu Anguo , Yang Jingya
Published: December 2012

A series of novel 2‐aryl‐3‐(9‐alkylcarbazol‐3‐yl)thiazolidin‐4‐ones were synthesized by one‐pot three‐component reactions of 3‐amino‐9‐alkylcarbazoles, aromatic aldehydes, and 2‐mercaptoacetic acid by using dicyclohexylcarbodiimide (DCC) as a cyclizing agent in dry diethyl ether at room temperature. This protocol has advantages of mild condition, short reaction time, high yield, and simple work‐up procedure.
Quinolone Analogues 12: Synthesis and Tautomers of 2‐Substituted 4‐Quinolones and Related Compounds
Authors: Kurasawa Yoshihisa , Yoshida Kiminari , Yamazaki Naoki , Iwamoto Kotoji , Hamamoto Yoshihiko , Kaji Eisuke , Sasaki Kenji , Zamami Yoshito
Published: December 2012

The 4‐quinolone‐2‐carboxylates 4a,b were converted into the 4‐quinolone‐2‐carbohydrazides 5a,b, hydrazones 6,7,10, and related compounds 8,9,11. The 4‐methoxyquinoline‐2‐carboxylate 12 was also transformed into the 4‐methoxyquinoline‐2‐carbohydrazide 13, which was modified to the hydrazone 14 and related compound 15. The antimicrobial activities of compounds 6b and 14 are described together with the 4‐oxo and 4‐hydroxy tautomers of compounds 4‐11 in deuteriodimethyl sulfoxide and deuteriotrifluoroacetic acid.
Synthesis, Characterization, and In Vitro Antibacterial Activities of Macromolecules Derived from Bis‐Chalcone
Authors: Asiri Abdullah M. , Khan Salman A.
Published: December 2012

We investigated the antibacterial activity of some new macromolecules such as bis‐pyrazoline, bis‐pyrazole, bis‐pyrimidines prepared from the reaction of bis‐chalcone with thiosemicarbazide/phenyl hydrazine/guanidine hydrochloride/thiourea. All the macromolecules have been characterized by IR, 1H NMR, 13C NMR, mass and elemental analyses. The antibacterial activity of these compounds was first tested in vitro by the disc diffusion assay against two Gram‐positive and two Gram‐negative bacteria, and then the minimum inhibitory concentration was determined with the reference to standard drug chloramphenicol. The results showed that pyrazoline derivative showed better antibacterial activity on S. typhimurium and E. coli than the reference drug chloramphenicol.
One‐Pot Synthesis of 13‐Acetyl‐9‐methyl‐11‐oxo(or thioxo)‐8‐oxa‐10,12‐diazatricyclo[7.3.1.02,7]trideca‐2,4,6‐trienes under Microwave Irradiation
Authors: Cheng Qingfang , Wang Qifa , Tan Tin , Chen Na , Shuai Mei
Published: December 2012

Oxygen‐bridged monastrol analogs, 13‐acetyl‐9‐methyl‐11‐oxo(or thioxo)‐8‐oxa‐10,12‐diazatricyclo[7.3. 1.02,7]trideca‐2,4,6‐trienes, were synthesized by one‐pot three component condensation reaction of substituted salicylaldehyde, acetylacetone and urea or thiourea with nontoxic, inexpensive, and easily available NaHSO4 as catalyst under microwave irradiation and solvent‐free conditions in short time with good yields. The structures of the products were characterized by IR, 1H NMR, 13C NMR spectra, and elemental analyses.
Creative Activity, Personality, Mental Illness, and Short‐Term Mating Success
Authors: Beaussart Melanie L. , Kaufman Scott Barry , Kaufman James C.
Published: December 2012

It has been argued that creativity evolved, at least in part, through sexual selection to attract mates. Recent research lends support to this view and has also demonstrated a link between certain dimensions of schizotypy, creativity, and short‐term mating. The current study delves deeper into these relationships by focusing on engagement in creative activity and employing an expansive set of personality and mental health measures (Five Factor Model, schizotypy, anxiety, and depression). A general tendency to engage in everyday forms of creative activity was related to number of sexual partners within the past year in males only. Furthermore, schizotypy, anxiety, and Neuroticism were all indirectly related to short‐term mating success, again for males only. The study provides additional support for predictions made by sexual selection theory that men have a higher drive for creative display, and that creativity is linked with higher short‐term mating success. The study also provides support for the contention that certain forms of mental illness may still exist in the gene pool because particular personality traits associated with milder forms of mental illness (i.e., Neuroticism & schizotypy) are also associated directly with creativity and indirectly with short‐term mating success.
High‐resolution stimulated Raman spectroscopy and analysis of the ν1/ν5 (C–H) stretching dyad of C2H4
Authors: Aouididi H. , Rotger M. , Bermejo D. , Martínez R.Z. , Boudon V.
Published: December 2012

The high‐resolution stimulated Raman spectra of the ν1/ν5 C–H stretching bands of C2H4 have been recorded and analyzed by means of the tensorial formalism developed in Dijon for X2Y4 asymmetric‐top molecules. A total of 689 lines (428 for ν5 and 261 for ν1) were assigned and fitted as a dyad including Coriolis coupling constants. We obtained a global root mean square deviation of 4.39 × 10− 3 cm− 1 (4.61 × 10− 3 cm− 1 for ν1, 4.25 × 10− 3 cm− 1 for ν5). The nearby 2ν2 band, extrapolated from ν2, was included in the analysis. However, no interaction parameter involving it could be fitted. The analysis is quite satisfactory, although some parts of ν5 are not very well reproduced, probably indicating some yet unidentified resonances. This region is indeed quite dense, with many interacting dark states that cannot be included at present. Copyright © 2012 John Wiley & Sons, Ltd.
Analysis of volatile oil composition of Citrus aurantiumL. by microwave‐assisted extraction coupled to headspace solid‐phase microextraction with nanoporous based fibers
Authors: Gholivand Mohammad Bagher , Piryaei Marzieh , Abolghasemi Mir Mahdi
Published: December 2012

Nanoporous silica was prepared and functionalized with amino propyl‐triethoxysilane to be used as a highly porous fiber‐coating material for solid‐phase microextraction (SPME). The prepared nanomaterials were immobilized onto a stainless steel wire for fabrication of the SPME fiber. The proposed fiber was evaluated for the extraction of volatile component of Citrus aurantium L. leaves. A homemade microwave‐assisted extraction followed by headspace (HS) solid‐phase apparatus was used for the extraction of volatile components. For optimization of factors affecting the extraction efficiency of the volatile compounds, a simplex optimization method was used. The repeatability for one fiber (n = 4), expressed as RSD, was between 3.1 and 8.6% and the reproducibility for five prepared fibers was between 10.1 and 14.9% for the test compounds. Using microwave‐assisted distillation HS‐SPME followed by GC‐MS, 53 compounds were separated and identified in C. aurantium L., which mainly included limonene (62.0%), linalool (7.47%), trans‐β‐Ocimene (3.47%), and caryophyllene (2.05%). In comparison to a hydrodistillation method, the proposed technique could equally monitor almost all the components of the sample, in an easier way, which was rapid and required a much lower amount of sample.
Quantitation and pharmacokinetics of 1,4‐diamino‐2,3‐dicyano‐1,4‐bis (2‐aminophenylthio) butadiene (U0126) in rat plasma by liquid chromatography‐tandem mass spectrometry
Authors: Bae Soo Hyeon , Hwang Jee Won , Shin Sang Joon , Park Gyu Hwan , Yoon Kee Dong , Bae Soo Kyung
Published: December 2012

A simple, robust, and rapid LC‐MS/MS method was developed for the quantitation of U0126 and validated in rat plasma. Plasma samples (20 μL) were deproteinized using 200 μL ACN containing 30 ng/mL of chlorpropamide, internal standard. Chromatographic separation performed on an Agilent Poroshell 120 EC‐C18 column (4.6 × 50 mm, 2.7 μm particle size) with an isocratic mobile phase consisting of a 70:30 v/v mixture of ACN and 0.1% aqueous formic acid. Each sample was run at 0.6 mL/min for a total run time of 2 min per sample. Detection and quantification were performed using a mass spectrometer in selected reaction‐monitoring mode with positive ESI at m/z 381 → 123.9 for U0126 and m/z 277 → 175 for the internal standard. The standard curve was linear over a concentration range of 20–5000 ng/mL with correlation coefficients greater than 0.9965. Precision, both intra‐ and interday, was less than 10.1% with an accuracy of 90.7–99.4%. No matrix effects were observed. U0126 in rat plasma degraded approximately 41.3% after 3‐h storage at room temperature. To prevent degradation, sample handling should be on an ice bath and all solutions kept at 4°C. This method was successfully applied to a pharmacokinetic study of U0126 at various doses in rats.
Chromatography in characterization of polysaccharides from medicinal plants and fungi
Authors: Hu De‐jun , Cheong Kit‐leong , Zhao Jing , Li Shao‐ping
Published: December 2012

Polysaccharides isolated from medicinal plants and fungi exhibit multiple pharmacological activities. The biological activities of polysaccharides depend on their chemical characteristics. However, characterization of polysaccahrides is a challenge because of their complicated structure and macromolecular mass. In this review, chromatography in characterization of polysaccharides, including physicochemical characterization (purity, molecular mass, and distribution), structural characterization (constituent monosaccharide composition and the ratio, the features of glycosidic linkages), and fingerprint of polysaccharides (acidic and enzymatic hydrolysates), from medicinal plants and fungi were reviewed and discussed according to the publications collected in Web of Science since 2007. The perspective for characterization of polysaccharides has also been described.
Factors Affecting Herbaceous Richness and Biomass Accumulation Patterns of Reclaimed Coal Mines
Authors: Pallavicini Y. , Alday J. G. , Martínez‐Ruiz C.
Published: December 2012

Open‐cast mining reclamation strategies are focused on the identification of the environmental factors at different scales that facilitate the vegetation establishment and development. Here, we characterised the environmental factors at macro‐scale and micro‐scale that influenced the herbaceous richness and biomass accumulation patterns trough a 32‐year chronosequence. Herbaceous richness and biomass were influenced at macro‐scale by successional and soil development gradients whereas at micro‐scale by shrub cover and coarseness gradients. Indeed, certain environmental factors at macro‐scale and micro‐scale contributed simultaneously to determine these gradients. Explicitly, the successional gradient was related to carbon and nitrogen ratio, grazing intensity and Shannon diversity. Across this successional gradient, total herb biomass and Fabaceae biomass were reduced as well as main taxonomical groups richness. Soil development gradient was related to total nitrogen, pH and erosion severity. This gradient only influenced species richness and produced a richness reduction when pH and erosion severity increased. At micro‐scale, the shrub cover gradient was related to organic matter thickness, producing a Poaceae biomass and bryophytes cover increase when shrub cover and organic matter increased. The coarseness gradient was related to the cover of rocks and bare soil, producing a reduction of herb biomass and richness when rocks and bare soil increased. These results emphasise the need to incorporate in the management plans the influence of soil development, successional, shrub cover and coarseness gradients over herbaceous richness and biomass to improve mine reclamation strategies. Copyright © 2013 John Wiley & Sons, Ltd.
Research on the anti‐sticking characteristics of water hydraulic piston friction pairs with hydrostatic bearing
Authors: Huanlong Liu , Guozhi Wang , Jian Ke , Lanying Yu
Published: December 2012

Certain sticking phenomena generally exist in the common clearance sealing piston friction pairs. For oil media, it can be accepted because of its better lubrication, but for water media, it needs to be avoided as far as possible because of its worse lubrication. In this paper, the piston pairs with the hydrostatic bearing are presented to improve its anti‐sticking ability. The anti‐sticking performance is researched by computational fluid dynamics and experiment. The results indicate that the anti‐sticking ability can be improved for the new structure piston pairs. The key reason is that the hydrostatic bearing effect is reasonably applied. Copyright © 2012 John Wiley & Sons, Ltd.
Light‐Triggered Multifunctionality at Surfaces Mediated by Photolabile Protecting Groups
Authors: Cui Jiaxi , Miguel Verónica San , del Campo Aranzazu
Published: December 2012

Photoremovable protecting groups (PRPGs) are applied to organic surfaces, thin polymer films, and hydrogels to achieve light‐based remote control of their (bio)chemical and physical properties. These can be localized (i.e. patterned), tunable by exposure dose, and generated on‐demand. Using PRPGs with independent response to different wavelengths, multifunctional materials with a number of individually addressable functional states can be generated. Light‐triggered polymerization, crosslinking, and degradation processes as well as release of attached molecules can be realized. Light‐responsive surfaces and materials based on PRPGs open interesting possibilities for the next generation of instructive materials for cell culture and tissue regeneration.
Soybean biodiesel methyl esters, free glycerin and acid number quantification by 1H nuclear magnetic resonance spectroscopy
Authors: Coral Natasha , Rodrigues Elizabeth , Rumjanek Victor , Zamian José Roberto , da Rocha Filho Geraldo Narciso , da Costa Carlos Emmerson Ferreira
Published: December 2012

Production of alternative fuels, such as biodiesel, from transesterification of vegetable oil driven by heterogeneous catalysts is a promising alternative to fossil diesel. However, achieving a successful substitution for a new renewable fuel depends on several quality parameters. 1H NMR spectroscopy was used to determine the amount of methyl esters, free glycerin and acid number in the transesterification of soybean oil with methanol in the presence of hydrotalcite‐type catalyst to produce biodiesel. Reaction parameters, such as temperature and time, were used to evaluate soybean oil methyl esters rate conversion. Temperatures of 100 to 180 °C and times of 20 to 240 min were tested on a 1 : 12 molar ratio soybean oil/methanol reaction. At 180 °C/240 min conditions, a rate of 94.5 wt% of methyl esters was obtained, where free glycerin and free fatty acids were not detected. Copyright © 2012 John Wiley & Sons, Ltd.
MRI reporter genes: applications for imaging of cell survival, proliferation, migration and differentiation
Authors: Vandsburger Moriel H , Radoul Marina , Cohen Batya , Neeman Michal
Published: December 2012

Molecular imaging strives to detect molecular events at the level of the whole organism. In some cases, the molecule of interest can be detected either directly or with targeted contrast media. However many genes and proteins and particularly those located in intracellular compartments are not accessible for targeted agents. The transcriptional regulation of these genes can nevertheless be detected, although indirectly, using reporter gene encoding for readily detectable proteins. Such reporter proteins can be expressed in the tissue of interest by genetically introducing the reporter gene in the target cells. Imaging of reporter genes has become a powerful tool in modern biomedical research. Typically, expression of fluorescent and bioluminescent proteins and the reaction product of expressed enzymes and exogenous substrates were examined using in vitro histological methods and in vivo whole body imaging methods. Recent advances in MRI reporter gene methods raised the possibility that MRI could become a powerful tool for concomitant high‐resolution anatomical and functional imaging and for imaging of reporter gene activity. An immediate application of MRI reporter gene methods was by monitoring gene expression patterns in gene therapy and in vivo imaging of the survival, proliferation, migration and differentiation of pluripotent and multipotent cells used in cell‐based regenerative therapies for cancer, myocardial infarction and neural degeneration. In this review, we characterized a variety of MRI reporter gene methods based on their applicability to report cell survival/proliferation, migration and differentiation. In particular, we discussed which methods were best suited for translation to clinical use in regenerative therapies. Copyright © 2012 John Wiley & Sons, Ltd.
Intravascular contrast agent T2* relaxivity in brain tissue
Authors: Patil Vishal , Jensen Jens H. , Johnson Glyn
Published: December 2012

Dynamic susceptibility‐weighted contrast‐enhanced (DSC) MRI perfusion measurements depend on estimating intravascular contrast agent (CA) concentrations (C) from signal intensity changes in ‐weighted images after bolus injection. Generally, linearity is assumed between relaxation and C, but previous studies have shown that compartmentalization of CA and secondary magnetic field perturbations generate deviations from linearity. Physical phantoms using bulk blood have been used to empirically determine the relationship between relaxation rate and C in large vessels. However, the relaxivity of CA in the microvasculature is not easily measured since constructing appropriate phantoms is difficult. Instead, theoretical relaxivity models have been developed. In this study, we empirically tested a non‐linear expression based on static dephasing regime (SDR) and linear approximation. Signal‐time curves in white (WM) and grey matter (GM) were converted to concentration time curves (CTCs) using both expressions. Parameters for both linear and non‐linear formulations were adjusted to give a best agreement between cerebral blood volumes (CBV) calculated from WM and arterial CTCs in a group of normal subjects scanned at 3T. Optimized parameters were used to calculate blood volume in WM and GM in healthy subjects scanned at 3T and in meningioma patients scanned at 1.5T. Results from this study showed that a non‐linear SDR formulation gave an acceptable functional form for tissue relaxivity, giving reliable CBV estimates at different field strengths and echo times. Copyright © 2012 John Wiley & Sons, Ltd.
In vivo measurement of aldehyde dehydrogenase‐2 activity in rat liver ethanol model using dynamic MRSI of hyperpolarized [1‐13C]pyruvate
Authors: Josan Sonal , Xu Tao , Yen Yi‐Fen , Hurd Ralph , Ferreira Julio , Chen Che‐Hong , Mochly‐Rosen Daria , Pfefferbaum Adolf , Mayer Dirk , Spielman Daniel
Published: December 2012

To date, measurements of the activity of aldehyde dehydrogenase‐2 (ALDH2), a critical mitochondrial enzyme for the elimination of certain cytotoxic aldehydes in the body and a promising target for drug development, have been largely limited to in vitro methods. Recent advancements in MRS of hyperpolarized 13C‐labeled substrates have provided a method to detect and image in vivo metabolic pathways with signal‐to‐noise ratio gains greater than 10 000‐fold over conventional MRS techniques. However aldehydes, because of their toxicity and short T1 relaxation times, are generally poor targets for such 13C‐labeled studies. In this work, we show that dynamic MRSI of hyperpolarized [1‐13C]pyruvate and its conversion to [1‐13C]lactate can provide an indirect in vivo measurement of ALDH2 activity via the concentration of NADH (nicotinamide adenine dinucleotide, reduced form), a co‐factor common to both the reduction of pyruvate to lactate and the oxidation of acetaldehyde to acetate. Results from a rat liver ethanol model (n = 9) show that changes in 13C‐lactate labeling following the bolus injection of hyperpolarized pyruvate are highly correlated with changes in ALDH2 activity (R2 = 0.76). Copyright © 2012 John Wiley & Sons, Ltd.
Do pregnant women and their partners make an informed choice about first trimester risk assessment for Down syndrome, and are they satisfied with the choice?
Authors: Bangsgaard Louise , Tabor Ann
Published: December 2012

Objective

All pregnant women in Denmark are offered risk assessment for Down syndrome. The aim of this study was to investigate whether women and partners make an informed choice about first trimester risk assessment, and their satisfaction with the choice.

Methods

A survey using multiple measure of informed choice at 12 weeks and decision regret scale at 30 weeks, among pregnant women and partners, planning to deliver at Copenhagen University Hospital, Rigshospitalet.

Results

Five hundred thirty‐one women (99.6%) out of 534 women chose to have risk assessment. Most women and men had high degree of knowledge (82% and 81%) and positive attitudes regarding risk assessment (97% and 98%), leading to 79% and 80% making an informed choice. Education predicted knowledge for women (odds ratio 3.42; 95% confidence interval 1.63–7.18) and partners (odds ratio 2.97; 95% confidence interval 1.37–6.45), country of origin predicted knowledge, attitude and informed choice among women. Three hundred thirty‐two women (99%) and all partners were satisfied with having chosen risk assessment.

Conclusions

Although 80% of pregnant women and partners make an informed choice about undergoing first trimester risk assessment for Down syndrome, as many as 20% do not. At 30 weeks nearly all women and partners were satisfied to have had a risk assessment performed. © 2012 John Wiley & Sons, Ltd.
Full‐wave optoelectrical modeling of optimized flattened light‐scattering substrate for high efficiency thin‐film silicon solar cells
Authors: Isabella Olindo , Sai Hitoshi , Kondo Michio , Zeman Miro
Published: December 2012

The flattened light‐scattering substrate (FLiSS) is formed by a combination of two materials with a high refractive index mismatch, and it has a flat surface. A specific realization of this concept is a flattened two‐dimensional grating. When applied as a substrate for thin‐film silicon solar cells in the nip configuration, it is capable to reflect light with a high fraction of diffused component. Furthermore, the FLiSS is an ideal substrate for growing high‐quality microcrystalline silicon (µc‐Si:H), used as bottom cell absorber layer in most of multijunction solar cell architectures. FLiSS is a three‐dimensional structure; therefore, a full‐wave analysis of the electromagnetic field is necessary for its optimal implementation. Using finite element method, different shapes, materials, and geometrical parameters were investigated to obtain an optimized FLiSS. The application of the optimized FLiSS in µc‐Si:H single junction nip cell (1‐µm‐thick i‐layer) resulted in a 27.4‐mA/cm2 implied photocurrent density. The absorptance of µc‐Si:H absorber exceeded the theoretical Yablonovitch limit for wavelengths larger than 750 nm. Double and triple junction nip solar cells on optimal FLiSS and with thin absorber layers were simulated. Results were in line with state‐of‐the‐art optical performance typical of solar cells with rough interfaces. After the optical optimization, a study of electrical performance was carried out by simulating current–voltage characteristics of nip solar cells on optimized FLiSS. Potential conversion efficiencies of 11.6%, 14.2%, and 16.0% for single, double, and triple junction solar cells with flat interfaces, respectively, were achieved. Copyright © 2012 John Wiley & Sons, Ltd.
Halogen bonding (X‐bonding): A biological perspective
Authors: Scholfield Matthew R. , Zanden Crystal M. Vander , Carter Megan , Ho P. Shing
Published: December 2012

The concept of the halogen bond (or X‐bond) has become recognized as contributing significantly to the specificity in recognition of a large class of halogenated compounds. The interaction is most easily understood as primarily an electrostatically driven molecular interaction, where an electropositive crown, or σ‐hole, serves as a Lewis acid to attract a variety of electron‐rich Lewis bases, in analogous fashion to a classic hydrogen bonding (H‐bond) interaction. We present here a broad overview of X‐bonds from the perspective of a biologist who may not be familiar with this recently rediscovered class of interactions and, consequently, may be interested in how they can be applied as a highly directional and specific component of the molecular toolbox. This overview includes a discussion for where X‐bonds are found in biomolecular structures, and how their structure–energy relationships are studied experimentally and modeled computationally. In total, our understanding of these basic concepts will allow X‐bonds to be incorporated into strategies for the rational design of new halogenated inhibitors against biomolecular targets or toward molecular engineering of new biological‐based materials.
Regional Economic Performance and Distance Between Parents and Their Employed Children – a Multilevel Analysis
Authors: van den Broek Thijs , Dykstra Pearl A. , Schenk Niels
Published: December 2012

Drawing on the work of Sassen, we assess the association between regional economic performance and the distance between parents and their employed children. Multilevel regression analyses of German Ageing Survey micro data enriched with INKAR (Indicators, Maps, and Graphics for Spatial and Urban Development) district level indicators (N = 5,577) indicate that economic performance of a parent's living district is negatively associated with parent‐employed child distance. The negative association between economic performance of a parent's living district and parent–child distance does not vary by the skill level of the child's job, contrary to expectations based on the polarisation and professionalisation theses. Possible implications of the findings for intergenerational solidarity, most notably the availability of informal care for dependent older parents, are discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Path‐following control for small fixed‐wing unmanned aerial vehicles under wind disturbances
Authors: Liu Cunjia , McAree Owen , Chen Wen‐Hua
Published: December 2012

This paper presents an alternative method of designing a guidance controller for a small unmanned aerial vehicle (UAV) so as to perform path following under wind disturbances. The wind effects acting on UAVs need to be taken into account and eventually eliminated. To solve this problem, we adopted a disturbance observer‐based control approach. The wind information is first estimated by a nonlinear disturbance observer, then it is incorporated into the nominal path following controller to formulate a composite controller that is able to compensate wind influences. The globally asymptotic stability of the composite controller is illustrated through theoretical analysis, whereas its performance is evaluated by various simulations including the one with software‐in‐the‐loop. Initial flight tests using a small fixed‐wing UAV are carried out to demonstrate its actual performance. Copyright © 2012 John Wiley & Sons, Ltd.
A reversible watermark scheme for 2D vector map based on reversible contrast mapping
Authors: Fei Peng , Li Chen , Min Long
Published: December 2012

Reversible watermark is suitable for the hosts with high precision requirement. However, the existed reversible watermark methods are mainly for raster images, and the reversible watermark schemes for vector graphics still have the defects such as low capacity and significant distortion. To counterstrike these situations, a reversible watermark scheme for two‐dimensional vector map based on reversible contrast mapping is proposed. First, the coordinates of the vertices are chosen according to the data precision requirements; then, the data of two‐dimensional vector maps are preprocessed to reduce distortion. After that, the encrypted watermark is embedded into the relative coordinates by using the reversible contrast mapping transform. Experimental results and analysis show that the proposed scheme can achieve higher payload, better reversibility, and invisibility than those of the existed schemes based on difference expansion, discrete cosine transform, and so on. It has great potential in the application of map data authentication and secure communication. Copyright © 2012 John Wiley & Sons, Ltd.
Brief Report: Intravital Imaging of Cancer Stem Cell Plasticity in Mammary Tumors
Authors: Zomer Anoek , Ellenbroek Saskia Inge Johanna , Ritsma Laila , Beerling Evelyne , Vrisekoop Nienke , Van Rheenen Jacco
Published: December 2012

It is widely debated whether all tumor cells in mammary tumors have the same potential to propagate and maintain tumor growth or whether there is a hierarchical organization. Evidence for the latter theory is mainly based on the ability or failure of transplanted tumor cells to produce detectable tumors in mice with compromised immune systems; however, this assay has lately been disputed to accurately reflect cell behavior in unperturbed tumors. Lineage tracing experiments have recently shown the existence of a small population of cells, referred to as cancer stem cells (CSCs), that maintains and provides growth of squamous skin tumors and intestinal adenomas. However, the lineage tracing techniques used in these studies provide static images and lack the ability to study whether stem cell properties can be obtained or lost, a process referred to as stem cell plasticity. Here, by intravital lineage tracing, we report for the first time the existence of CSCs in unperturbed mammary tumors and demonstrate CSC plasticity. Our data indicate that existing CSCs disappear and new CSCs form during mammary tumor growth, illustrating the dynamic nature of these cells.
Transforming Growth Factor β1 Signal is Crucial for Dedifferentiation of Cancer Cells to Cancer Stem Cells in Osteosarcoma
Authors: Zhang Haixia , Wu Haotong , Zheng Junheng , Yu Pei , Xu Lixiao , Jiang Pan , Gao Jin , Wang Hua , Zhang Yan
Published: December 2012

Human osteosarcoma harbors a small subpopulation of cancer stem cells (CSCs) that is believed to be associated with tumor metastasis, radioresistance/chemoresistance, local invasion, and poor clinical outcome. In this study, we found that transforming growth factor β1 (TGF-β1) signaling and a hypoxic environment dramatically induced self-renewal capacity in non-stem osteosarcoma cells, which in turn promoted chemoresistance, tumorigenicity, neovasculogenesis, and metastatic potential. Furthermore, blocking the TGF-β1 signaling pathway resulted in the inhibition of the dedifferentiation and clonogenicity of osteosarcoma cells, and the reduction of CSC self-renewal capacity and hypoxia-mediated dedifferentiation. These findings demonstrate that stem cells and non-stem cells exist in a dynamic equilibrium within the osteosarcoma cell population, and that CSCs may develop de novo from differentiated cancer cells. Hierarchical models of mammalian CSCs, therefore, should be considered to serve as bidirectional interconversion between the stem and non-stem cell components of the tumor.
Proangiogenic and Prosurvival Functions of Glucose in Human Mesenchymal Stem Cells upon Transplantation
Authors: Deschepper Mickael , Manassero Mathieu , Oudina Karim , Paquet Joseph , Monfoulet Laurent-Emmanuel , Bensidhoum Morad , Logeart-Avramoglou Delphine , Petite Herve
Published: December 2012

A major limitation in the development of cellular therapies using human mesenchymal stem cells (hMSCs) is cell survival post-transplantation. In this study, we challenged the current paradigm of hMSC survival, which assigned a pivotal role to oxygen, by testing the hypothesis that exogenous glucose may be key to hMSC survival. We demonstrated that hMSCs could endure sustained near-anoxia conditions only in the presence of glucose. In this in vitro cell model, the protein expressions of Hif-1α and angiogenic factors were upregulated by the presence of glucose. Ectopically implanted tissue constructs supplemented with glucose exhibited four- to fivefold higher viability and were more vascularized compared to those without glucose at day 14. These findings provided the first direct in vitro and in vivo demonstration of the proangiogenic and prosurvival functions of glucose in hMSC upon transplantation and identified glucose as an essential component of the ideal scaffold for transplanting stem cells.