bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Trap‐state Distribution and Carrier Transport in Nanotubular and Nanoparticulate TiO2 Electrodes for Dye‐Sensitized Solar Cells
Authors: Mohammadpour Raheleh , Iraji zad Azam , Hagfeldt Anders , Boschloo Gerrit
Published: June 2010

Dye‐sensitized solar cells (DSCs) with nanotubular TiO2 electrodes of varying thicknesses are compared to DSCs based on conventional nanoparticulate electrodes. Despite the higher degree of order in one‐dimensional nanotubular electrodes, electron transport times and diffusion coefficients, determined under short‐circuit conditions, are comparable to those of nanoparticulate electrodes. The quasi‐Fermi level, however, is much lower in the nanotubes, suggesting a lower concentration of conduction band electrons. This provides evidence for a much higher diffusion coefficient for conduction band electrons in nanotubes than in nanoparticulate films. The electron lifetime and the diffusion length are significantly longer in nanotubular TiO2 electrodes than in nanoparticulate films. Nanotubular electrodes have a trap distribution that differs significantly from nanoparticulate electrodes; they possess relatively deeper traps and have a characteristic energy of the exponential distribution that is more than two times that of nanoparticulate electrodes.
Local Disorder in Hydrogen Storage Compounds: The Case of Lithium Amide/Imide
Authors: Ludueña Guillermo A. , Wegner Martin , Bjålie Lars , Sebastiani Daniel
Published: June 2010

Amides and imides of alkali metals are a very promising class of materials for use as a hydrogen‐storage system, as they are able to store and release hydrogen via a chemical route at controllable temperatures and pressures. We critically revise the present picture of the atomic structure of the lightest member (LiNH2/Li2NH) by using a combined computational and experimental approach. Specifically, ab initio path integral molecular dynamics simulations and solid‐state 1H NMR techniques are combined. The results show that the presently assumed local structure might be inconsistent or at least incomplete and needs considerable revision. In particular, the Li atoms turn out to be more mobile and more disordered than suggested by structural data obtained from X‐ray scattering. Also, the configuration of the hydrogen atoms, which is accessible via the NMR experiment and the corresponding first‐principles calculations, is different from the previously assumed data. The computed and experimentally observed 1H NMR parameters are in very good mutual agreement and illustrate the unusual chemical environment of the hydrogen atoms in this system. Incorporating our results on the new lithium data, we show that the effect of nuclear quantum delocalization for the hydrogen atoms is considerably reduced compared to the perfect crystal structure.
Distance estimation to multiple targets using band‐limited noise signal
Authors: Uebo Tetsuji , Nakasako Noboru , Ohmata Norimitsu , Itagaki Hanae
Published: June 2010

In many engineering fields, the distance to target is fundamental and very important information. Acoustical signals, such as audible sound or ultrasound, often play an essential role in measurement of distance. To measure distance, the time delay of the reflected wave measured with reference to the transmitted pulse wave, that is, the time‐of‐flight (TOF), is typically used. However, this method cannot measure short distances because the transmitted wave, which has not attenuated enough at the time of reception of the reflected waves, suppresses the reflected waves for a short distance. Meanwhile, in microwave radar research, a novel method using standing waves has been recently proposed in order to measure the distances to multiple targets, even if short. We apply the fundamental principle of this method to the estimation of short distances for multiple targets using audible sound. In this paper, we focus our attention on audible band‐limited noise. To verify the validity and effectiveness of our method, we perform computer simulations and experiments. It is confirmed that short distances to multiple targets, such as the distances to two targets located 0.1 and 1 m away, can be estimated properly by our method. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(7): 53–60, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10248
Variation of transpiration within a canopy of silver birch: effect of canopy position and daily versus nightly water loss
Authors: Sellin Arne , Lubenets Kristina
Published: June 2010

Sap flux density (FLA) in branches of Betula pendula trees was examined with respect to environmental variables and canopy position. FLA of branches sampled within the basal and top thirds of crowns was analysed with respect to stomatal (gs), canopy (gc) and soil‐to‐leaf hydraulic conductance (KT). The canopy positions differed significantly (P < 0·001) by FLA: the day‐time values in the upper canopy were on average 1·8 times greater than in the lower canopy (59·2 vs 33·2 g m−2 h−1), associated with greater gs, gc and KT observed in the upper canopy. The differences in gc among the canopy positions resulted primarily from a ∼10‐fold greater aerodynamic boundary‐layer conductance (gbl) in the upper canopy (mean gbl was 1695 vs 161 mmol m−2 s−1, respectively) in the day time. The asymptotic nature of gs versus gc relationship observed in the lower canopy suggests that stomata limit transpiration from the shade foliage at higher gbl. The linear relationship (R2 = 0·49–0·58, P < 0·001) between KT and FLA alludes to the role of hydraulic capacity in the control of sap fluxes. The dominant environmental factor affecting FLA in the day time was irradiance, and air relative humidity at night. The strong dependence of FLA on atmospheric evaporative demand in the night time proved that nocturnal branch sap flow indeed represents transpiration, but not tissue water recharge. Nocturnal FLA was about 24·7 and 19·5% of the respective mean day‐time rates for the upper and lower canopy. Owing to short northern nights in summer, nocturnal transpiration constituted only 6–8% of the daily total water loss. The variation in branch‐level sap flow is determined not merely by environmental gradients existing within the forest canopy, but depends largely on trees' internal properties, including stomatal conductance and plant hydraulic properties. Copyright © 2010 John Wiley & Sons, Ltd.
Effect of forest thinning on overland flow generation on hillslopes covered by Japanese cypress
Authors: Xuan Dung Bui , Miyata Shusuke , Gomi Takashi
Published: June 2010

We examined the effect of forest thinning on overland flow generation on hillslopes covered by a Japanese cypress plantation in central Japan. We established hillslope plots in two small catchments for monitoring overland flow generation. Plot 1 was a treatment plot in which 58·3% of stems were removed, whereas plot 2 remained untreated as a control. Overland flow generation was examined using (1) time‐trend analysis that compared overland flow to precipitation 2 years pre‐ and 2 years post‐thinning in plot 1 and (2) a paired‐plot approach that compared the treated hillslope plot to the control hillslope plot. The latter approach was more reliable for identifying treatment effects than time‐trend analysis because it minimizes effects of climate variables such as precipitation. Unlike our initial hypothesis for decreasing overland flow after thinning, paired‐plot analysis indicated that after thinning, mean overland flow increased 7·4% (corresponding to 2·1 mm) in response to individual storms and 4·8% (corresponding to 7·9 mm) based on monthly data. Although the increased overland flow is likely associated with reduced canopy interception, the reduction of canopy interception after the thinning was estimated to be greater than the increases in overland flow. Therefore, some of the increased throughfall was infiltrated into the soil matrix. Such changes in hillslope‐scale runoff in response to thinning alter the distribution of water in the surface and subsurface layers of forested headwater basins. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of cattle grazing during the dormant season on soil surface hydrology and physical quality in a moist‐temperate region
Authors: Stavi Ilan , Lal Rattan , Owens Lloyd B.
Published: June 2010

Livestock grazing in paddocks of temperate regions during the dormant season affects soil surface hydrology and physical quality, thus, impacting its capacity to function. However, very few studies have dealt with these effects in temperate‐moist regions. Thus, the objective of this study was to evaluate the effects of grazing on these variables, with reference to soil hydrological and physical characteristics. Soil properties were measured in a paddock under rotational grazing during the growing season only (GR) and compared with those under grazing during the dormant season and rotational grazing during the growing season (DO). Soil series in both paddocks is Coshocton (fine loamy, mixed, active, mesic Aquultic Hapludalfs). Soil properties were studied for 0–5, 5–10 and 10–15 cm depths. In comparison with GR, DO had a smaller soil water sorptivity (36·2 vs 19·4 mm min−0·5), transmissivity (2·2 vs 0·6 mm min−1), equilibrium infiltration rate (4·8 vs 1·4 mm min−1) and cumulative infiltration in 3 h (865·6 vs 260·0 mm). In addition, GR had larger volumetric field moisture capacity (41·4 vs 39·3%), water stable aggregates (880 vs 830 g kg−1), coarse root (>1 mm) biomass (12·8 vs 7·2 mg cm−3), smaller penetration resistance (0·93 vs 1·42 MPa) and bulk density (1·24 vs 1·44 g cm−3). A small difference between GR and DO was observed in vane shear strength (130·3 vs 124·8 kPa), and no difference was found in aggregate's mean weight diameter. Soil properties differed among depths, and the effect of grazing decreased with increased depth. Copyright © 2010 John Wiley & Sons, Ltd.
Enhancing uplink performance in UTRAN LTE networks by load adaptive power control
Authors: Müllner Robert , Ball Carsten F. , Boussif Malek , Lienhart Johann , Hric Peter , Winkler Hubert , Kremnitzer Kurt , Kronlachner Rudolf
Published: June 2010

Uplink power control in 3GPP UTRAN long term evolution (LTE) networks consists of a closed‐loop scheme around an open‐loop point of operation. The uplink performance of the network is decisively influenced by power control. This paper provides insight into the uplink power control procedure and its interworking with adaptive transmission bandwidth (ATB) as well as adaptive modulation and coding (AMC). A detailed performance evaluation is presented based on system level simulations. In the first step, the performance of pure open‐loop power control (OLPC) was analysed and the impact of parameter settings on resource allocation, utilisation of specific modulation and coding schemes (MCS), re‐transmission rate, and resulting throughput was determined. A two‐dimensional parameter optimisation for full path‐loss (PL) compensation and fractional power control (FPC) was performed to conclude the best strategy for the trade‐off between network capacity and coverage. In the second step, the impact of traffic load on the interaction between the different LTE radio resource management algorithms was analysed. A novel strategy is presented which introduces traffic load dependent decisions for the closed‐loop power control (CLPC) component to optimise the uplink throughput. This solution provides an automatic configuration for LTE networks without further intervention by the operator. Copyright © 2010 John Wiley & Sons, Ltd.
Ethylene Glycol Electrooxidation on Smooth and Nanostructured Pd Electrodes in Alkaline Media
Authors: Bambagioni V. , Bevilacqua M. , Bianchini C. , Filippi J. , Marchionni A. , Vizza F. , Wang L. Q. , Shen P. K.
Published: June 2010

The electrooxidation of ethylene glycol (EG) has been studied either in situ on a smooth Pd electrode by FTIR spectroscopy or on nanostructured Pd‐based catalysts by cyclic voltammetry. The electrooxidation on the Pd electrode is dramatically influenced by the pH. Below pH 12, CO2 is formed and detected in the thin layer by FTIR, while at higher pH values glycolate, carbonate and oxalate are formed almost simultaneously at a potential of ca. 0.4 V versus RHE. Above 0.9 V glycolate is oxidised to oxalate and carbonate. The nanostructured electrocatalysts Pd–(Ni–Zn)/C, Pd–(Ni–Zn–P)/C and Pd/C are much more active than the smooth Pd electrode (up to 3,300 A g(Pd)–1) and give different distributions of the oxidation products. Pd/C is the most selective catalyst yielding glycolate, while mixtures of glycolate (major>60%), oxalate and carbonate are obtained with Pd–(Ni–Zn)/C or Pd–(Ni–Zn–P)/C. Carbonate is produced by oxidation of both glycolate (major contribution) and oxalate, while the major part of oxalate seems to be produced by the direct oxidation of EG.
Diffusion tensor imaging of white matter involvement in essential tremor
Authors: Klein Johannes C. , Lorenz Benedikt , Kang Jun‐Suk , Baudrexel Simon , Seifried Carola , van de Loo Simone , Steinmetz Helmuth , Deichmann Ralph , Hilker Rüdiger
Published: June 2010

This study set out to determine whether there is white matter involvement in essential tremor (ET), the most common movement disorder. We collected diffusion MRI and analysed differences in fractional anisotropy (FA) and mean diffusivity (MD) between ET patients and control subjects as markers of white matter integrity. We used both classical ROI‐based statistics and whole‐brain analysis techniques, including voxel‐wise analysis with SPM5 and tract‐based spatial statistics (TBSS). Using region of interest (ROI) analysis, we found increased MD bilaterally in the inferior cerebellar peduncles (ICP) and reduced FA in the right‐sided ICP of ET patients. Whole‐brain analyses with TBSS detected increased MD distributed in both motor and nonmotor white matter fibers of ET patients predominantly in the left parietal white matter, while there were no significant FA differences in these areas between ET patients and controls. Voxel‐wise analysis with SPM detected significant increase of MD congruent with the highest probability of difference as detected by TBSS. VBM analysis of T1 images did not detect significant differences in either gray or white matter density between our study groups. In summary, we found evidence for changes in white matter MRI properties in ET. The circumscript pathology of the ICP corroborates the pathogenetic concept of the cerebellum and its projections as key structures for tremor generation in ET. Moreover, increased diffusivity in white matter structures of both hemispheres suggests widespread alterations of fiber integrity in motor and nonmotor networks in ET patients. The underlying cause of the DTI changes observed remains to be elucidated. Hum Brain Mapp, 2011. © 2010 Wiley‐Liss, Inc.
Mild and efficient synthesis of aryliodonium ylides of 2,6‐dimethylpyrimidin‐4‐ol
Authors: Kumar Ravi , Nair Reshmi R. , Prakash Om
Published: June 2010

Mild and efficient synthesis of new synthetically useful aryliodonium ylides of 2,6‐dimethyl‐ pyrimidin‐4‐ol (3a–d) using (dichloroiodo)arenes in aqueous medium is reported. Antibacterial activity of these ylides 3a–d against Escherichia coli and Bacillus Licheniformis is also described. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:339–342, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20608
Synthesis of [1,2‐a] benzimidazolo‐1,3,5‐triazin‐2‐thione, [1,2‐a] benzimidazolo‐1,3,5‐thiadiazin‐2‐thione, [1,2‐a] benzimidazolo‐1,3,5‐triazin‐2‐amine, and [1,2‐a] benzimidazol‐2‐yl amidrazone
Authors: Hajri A. , Abderrahim R.
Published: June 2010

N‐benzimidazol‐2‐yl imidate type 1 reacts with thiourea, carbon disulfide, cyanamide, and hydrazide to give, respectively, [1,2‐a] benzimidazolo‐1,3,5‐triazin‐2‐thione 2, [1,2‐a] benzimidazolo‐1,3,5‐thiadiazin‐2‐thione 3, [1,2‐a] benzimidazolo‐1,3,5‐triazin‐2‐amine 4, and [1,2‐a] benzimidazol‐2‐yl amidrazone 5 with good yields. Structures elucidation of all newly synthesized heterocyclic compounds was based on the data of IR, 1H NMR, 13C NMR, elemental analysis, and MS of some products. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:279–283, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20618
Administrative perspectives on international partnerships
Authors: Amey Marilyn J.
Published: June 2010

If international partnerships are to be sustained beyond funding cycles and the initial passions of a faculty champion, they need to become institutionalized into the fabric of the department or institution.
Leveraging partnerships to internationalize the liberal arts college: Campus internationalization and the faculty
Authors: Brewer Elizabeth
Published: June 2010

Liberal arts colleges face particular challenges in using institutional partnerships as a vehicle for internationalization.
Lesions of reuniens and rhomboid thalamic nuclei impair radial maze win‐shift performance
Authors: Hembrook Jacqueline R. , Mair Robert G.
Published: June 2010

The reuniens (Re) and rhomboid (Rh) nuclei are major sources of thalamic input to hippocampus and medial prefrontal cortex. We compared effects of lesions in ReRh and other parts of the midline‐intralaminar complex on tasks affected by lesions in terminal fields innervated by these nuclei, including: visuospatial reaction time (VSRT), a measure of sensory guided responding; serial VSRT, a measure of action sequence learning; and win/shift radial arm maze (RAM) measures of spatial memory. ReRh lesions affected RAM, but not VSRT or serial VSRT performance. The effects of caudal intralaminar lesions were doubly dissociated from ReRh lesions, affecting VSRT, but not RAM or serial VSRT performance. Rostral intralaminar lesions did not produce significant impairments, other than a subgroup with larger lesions that were impaired performing a delayed RAM task. Combined lesions damaging all three sites produced RAM deficits comparable to ReRh lesions and VSRT deficits comparable to caudal intralaminar lesions. Thus there was no indication that deficits produced by lesions in one site were exacerbated significantly by the cumulative effect of damage in other parts of the midline‐intralaminar complex. The effects of ReRh lesions provide evidence that these nuclei affect memory functions of hippocampus and medial prefrontal cortex. The double dissociation observed between the effects of ReRh and caudal intralaminar nuclei provides evidence that different nuclei within the midline‐intralaminar complex affect distinct aspects of cognition consistent with the effects of lesions in the terminal fields they innervate. © 2010 Wiley‐Liss, Inc.
Histomorphology of thrombus organization, neointima formation, and foreign body response in retrieved human aneurysms treated with hydrocoil devices
Authors: Killer Monika , Arthur Adam S. , Barr John D. , Richling Bernd , Cruise Gregory M.
Published: June 2010

Biological processes, such as thrombus organization, endothelialization, and foreign body response, that occur following embolization of intracranial aneurysms are poorly understood. We examined 13 human aneurysms (retrieved at autopsy 1–74 days postembolization) treated with hybrid hydrogel‐platinum coil devices and platinum coils. The specimens were embedded in methyl methacrylate and ground sections were surface stained. Using light microscopy, thrombus organization in the sac, endothelialization of the neck, and foreign body response to the embolic devices were determined. The area percentages of the sac occupied by embolic devices and unorganized thrombus were quantified using image analysis. Thrombus organization increased over time, but was incomplete up to 74 days post‐treatment. Neointima formation had started at 5 days upon dense fibrin depositions and progressed to form a new vessel wall at 74 days. The foreign body response to the hydrogel was characterized by mononuclear macrophages, while platinum coils were surrounded by multinuclear foreign body giant cells. Histometric aneurysm occlusion ranged from 89 to 100% and embolic devices occupied 31–64% of the aneurysm sac. These findings showed that the hydrogel‐based devices occupied a large percentage of the aneurysm sac, provided a framework for thrombus organization to occur, and elicited less severe foreign body response than platinum coils. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.
Tungsten‐rhenium suture needles with improved properties for coronary artery bypass graft surgery
Authors: Cichocki Frank R. , Maurer Robert E. , Bar S. Neil
Published: June 2010

Suture needles are essential instruments for performing blood vessel anastomosis in coronary artery bypass graft (CABG) surgeries. Exceptional needle performance is needed now as never before because of the increasing prevalence of elderly patients with advanced stages of coronary disease and calcified tissue. The various properties that affect the performance of suture needles used in CABG surgery are reviewed and recent progress towards improving needle performance through the use of tungsten‐rhenium alloys and novel lubricous needle coatings is presented. Substantial enhancement of properties beyond those exhibited by commercially available stainless steel suture needles has been made, including an approximate 40% increase in strength, 100% increase in stiffness, and superior multiple pass penetration performance in both synthetic rubber media and human cadaver carotid arteries (p < 0.01). © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010
Electrospun micro/nanofibrous conduits composed of poly(ε‐caprolactone) and small intestine submucosa powder for nerve tissue regeneration
Authors: Hong Soongee , Kim Geunhyung
Published: June 2010

Three‐dimensional biocompatible and biodegradable scaffolds play important roles in tissue engineering. In this study, fibrous mats composed of electrospun poly(ε‐caprolactone) (PCL)/small intestine submucosa (SIS) tubes were fabricated with a high degree of longitudinal alignment as a conduit for peripheral nerves. Fourier transform infrared analyses of electrospun PCL/SIS mats with various amounts of SIS showed that the SIS was well embedded within the PCL matrix. The diameter of the PCL/SIS fibers with the 3 wt % of SIS in the PCL solution decreased 40% relative to that of pure PCL fibers due to increased electrical conductivity and decreased surface tension. PCL/SIS (3 wt %) electrospun mats exhibited various synergistic effects, including stronger mechanical properties (Young's modulus = more than 80%) and enhanced hydrophilicity (water contact angle at 30 min = 54°) relative to pure PCL (water contact angle at 30 min = 142°). Cell attachment and proliferation experiments demonstrated that the interactions between nerve cells (PC‐12) and the PCL/SIS conduits were more favorable than those between PC‐12 cells and a pure PCL conduit. This study contributes to the understanding of the effects of including SIS in electrospun composite mats. The ability to fabricate highly aligned tubes of PCL/SIS with appropriate mechanical properties and cellular interactions shows great potential for the design of nerve regeneration conduits. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.
Contrast‐enhanced sonography‐guided radiofrequency ablation for the local recurrence of previously treated hepatocellular carcinoma undetected by b‐mode sonography
Authors: Miyamoto Noriyuki , Hiramatsu Kazuhide , Tsuchiya Kazuhiko , Sato Yukihiko
Published: June 2010

Background.

The purpose of this study was to assess the usefulness of contrast‐enhanced sonography (CEUS) with Sonazoid to demonstrate local recurrence of hepatocellular carcinoma previously treated with radiofrequency ablation (RFA) and not seen on conventional sonography, prior to repeat RFA.

Methods.

This study included 16 cirrhotic patients with 17 cases of hypervascular locally recurrent hepatocellular carcinoma found by contrast‐enhanced multidetector row CT (MDCT) but not seen on noncontrast sonography. We used Kupffer‐phase imaging and vascular‐phase imaging after re‐injection. The morphologic patterns of local recurrence detected on CEUS were compared with those on MDCT. We performed repeat RFA guided by CEUS using Kupffer‐phase imaging after re‐injection.

Results.

We were able to detect on CEUS the location of all local recurrences with positive enhancement after re‐injection. The morphologic patterns of local recurrence on CEUS were in concordance with those found on MDCT in all lesions. Repeat percutaneous RFA was successfully performed in all lesions.

Conclusions.

The CEUS appearance of local recurrences correlated well with those on MDCT. A wider use of CEUS to guide repeat of percutaneous RFA may be possible with Sonazoid. © 2010 Wiley Periodicals, Inc. J Clin Ultrasound 38:339‐345, 2010
Synthesis and electron microscopic analysis of the self‐assembly of polymer and ferritin core‐shell structures
Authors: Wu Laying , Li Tao , Blom Douglas , Zhao Jibin , Ghoshroy Soumitra , Wang Qian
Published: June 2010

Self‐assembly of poly(4‐vinylpyridine) (P4VP) and ferritin produced a spherical core‐shell structure, which was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In particular, for better understanding, the organization of such core‐shell nanostructures, an optimal protocol for preparation of TEM thin sectioning of ferritin‐P4VP composites, was developed. It entails fixing the ferritin‐P4VP complex with 2.5% glutaraldehyde and infiltrating it with a mixture of acetone/resin while omitting the OsO4 postfixation and ethanol dehydration steps of the conventional protocol. Using this method, a round‐shaped thin section structure with unevenly distributed dark and white components was observed. The dark component from the thin section structure was determined to contain ferritin by energy‐filtered TEM imaging and iron element mapping, whereas the white part was identified as P4VP by its energy dispersive X‐ray spectroscopy (EDS) spectrum. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.
Cryo‐scanning electron microscopy and light microscopy for the study of fungi interactions
Authors: Sempere F. , Santamarina M.P.
Published: June 2010

The application of the cryo‐scanning electron microscopy and light microscopy for the study of the interactions at different environmental conditions between Penicillium oxalicum and Fusarium
verticillioides is described. A dual microculture was developed for the light microscopy analysis of the interaction. The microscope and macroscopic examinations were compared. Analysis of Petri plates revealed that F. verticillioides was a competitor for space and nutrients while P. oxalicum was a mycoparasite under the microscopic observations. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.
Effects of calcium supplements on fracture healing in a rat osteoporotic model
Authors: Shuid Ahmad Nazrun , Mohamad Sharlina , Mohamed Norazlina , Fadzilah Fazalina Mohd , Mokhtar Sabarul Afian , Abdullah Shahrum , Othman Faizah , Suhaimi Farihah , Muhammad Norliza , Soelaiman Ima Nirwana
Published: June 2010

Fracture healing is a complex process, which is further complicated if the bone is osteoporotic. Calcium is one of the important minerals in bone and has been found to prevent osteoporosis but its role in fracture healing of osteoporotic bone is still unclear. We carried out a study on the effects of calcium supplementation on the late phase healing of fractured osteoporotic bone using an ovariectomized rat model. Twenty‐four female Sprague–Dawley rats were divided into three groups: sham‐operated (SO), ovariectomized‐control (OVXC), and ovariectomized + calcium supplements (Ca). The right femurs of all the rats were fractured at mid‐epiphysis and a K‐wire was inserted for internal fixation. After 2 months of treatment, the rats were sacrificed and the femora were dissected out for radiological and biomechanical assessment. As expected, osteoporosis resulted in impaired healing as shown by the poor radiological and biomechanical properties of the OVXC group. CT scans showed significantly lower callus volumes in the SO and Ca groups compared to the OVXC group. Radiological scoring of fracture healing and callus staging of the SO and Ca groups were better than the OVXC group. However, the biomechanical parameters of the Ca group were significantly lower than the SO group and similar to the OVXC group. Therefore, calcium supplements may appear to improve fracture healing of osteoporotic bone but failed to improve strength. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1651–1656, 2010
Modeling solvation on the chemically modified silica surfaces
Authors: Buszewski Bogusław , Bocian Szymon , Nowaczyk Alicja
Published: June 2010

A detailed molecular‐level description of the retention mechanism in RP‐HPLC is a point of great interest to analytical chemists. For this purpose, the solvent adsorption on the octadecyl stationary‐bonded phase was investigated. Preferential adsorption of solvents from the acetonitrile–water mobile phase was modeled on the silica surface with one, two, three and four organic ligands, which represents a series of non‐end‐capped‐bonded phases with different coverage density of bonded ligands. As a result of the computer simulation, the increase of adsorbed acetonitrile around bonded ligands is observed. The number of water molecules near the modeled surface is observed as well. The results are in agreement with experimental measurement of acetonitrile excess adsorption isotherms on the series of in‐house made stationary‐bonded phase.
Synthesis of polyetherols with isocyanuric ring: Kinetics and mechanisms of reactions in the presence of DABCO as catalyst
Authors: Lubczak Jacek
Published: June 2010

To establish the mechanism of reaction of formation of oligoetherols with perhydro‐1,3,5‐triazine ring, the kinetics of reaction of isocyanuric acid and 1,3,5‐tris(2‐hydroxyetyl) isocyanurate with ethylene carbonate resulting in formation of polyetherols in the presence of diazabicyclo[2.2.2]octane as a catalyst has been investigated. The kinetic and mechanistic studies revealed that the initial step of reaction is zero order related to ethylene carbonate and the reaction is inhibited by imide groups of isocyanuric acid. The mechanism of reaction was confirmed by spectroscopic and electrochemical methods. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 550–561, 2010
Speed‐ and topography‐dependent boundary friction characteristics of steel
Authors: Aoki Saiko , Suzuki Akihito , Masuko Masabumi
Published: June 2010

A novel tribometer that undergoes significant changes at ultra‐slow (>5.0 µm s−1) to moderate (<20 cm s−1) sliding speeds was developed in order to study the friction‐speed characteristics of steel lubricated with oil. Three different surface topographies were applied to the specimens, and the friction characteristics with an additive‐free base oil (MO91) and a stearic acid‐formulated oil (StA/MO91) were studied to understand the effects of surface textures on the lubrication performance of an adsorbed molecular layer formed by StA. Friction reduction behaviour of the adsorbed layer observed in the transverse direction was attributed to microscopic hydrodynamic action that maintained the load‐carrying performance of the adsorbed layer. Copyright © 2010 John Wiley & Sons, Ltd.
Biodegradable and Electroactive TEMPO‐Substituted Acrylamide/Lactide Copolymers
Authors: Zhuang Xiuli , Zhang Han , Chikushi Natsuru , Zhao Changwen , Oyaizu Kenichi , Chen Xuesi , Nishide Hiroyuki
Published: June 2010

Copolymers composed of PLA and PTAm were prepared by a macromonomer approach. The PLA bearing vinyl group at chain end was copolymerized with 2,2,6,6‐tetrametylpiperidine‐4‐ylacrylamide. The resulted copolymers were oxidized by a peroxide to give PTAm‐g‐PLA. The structures of the copolymers were confirmed by NMR and FTIR spectroscopy. The comparison of 1H NMR results and SQUID measurements demonstrated that the oxidation of the PTAm fragment proceeded almost to completion. An MTT assay, cell adhesion and spreading evaluation showed that the copolymers exhibited improved cytocompatibility as compared to the PTAm homopolymer due to the introduction of the biocompatible PLA moiety.

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Vinyl‐Type Polymerization of Alkylester‐Substituted Norbornenes Without Endo/Exo Separation
Authors: Müller Kerstin , Jung Youngsuk , Yoon Do Y. , Agarwal Seema , Greiner Andreas
Published: June 2010

The vinyl‐type homo‐ and copolymerization of 9‐norborn‐5‐en‐2yl‐nonane acid ethyl ester and 2‐hexyl‐5‐norbornen was investigated. Both monomers were polymerized using di‐µ‐chlorobis(6‐methoxybicyclo[2.2.1]hept‐2‐ene‐endo‐5σ,2π)palladium(II) and AgSbF6 as catalysts. Poly(2‐hexyl‐5‐norbornene) is soluble in common organic solvents and has a Tg of 252 °C. Poly(9‐norborn‐5‐en‐2yl‐nonane acid ethyl ester) shows swelling in solvents like THF, chlorobenzene or chloroform and has a Tg of 136 °C. The solubility of the copolymers depends on the amount of 9‐norborn‐5‐en‐2yl‐nonane acid ethyl ester. E‐modulus measurements of copolymers with different amounts of ester showed an increase of flexibility when increasing the content of 9‐norborn‐5‐en‐2yl‐nonane acid ethyl ester in the copolymer.

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Electrospinning of Continuous Aligning Yarns with a ‘Funnel’ Target
Authors: Afifi Amalina M. , Nakano Shigeyuki , Yamane Hideki , Kimura Yoshiharu
Published: June 2010

A new electrospinning set‐up is described for continuous aligning of poly(L‐lactide) yarn. It comprises a slowly rotating grounded ‘funnel’ target and a winder placed right up to the funnel. A charged polymer jet is ejected from a nozzle. The electrospun fibers are first accumulated on the mouth plane of the funnel to form a web. The web is then pulled upward and guided to a winder on which twisted fibers are continuously wound as a bundle. Each filament of the bundle is slanted at about 45° relative to the collecting direction, and its average diameter is 6.0 ± 1.9 µm. The drawn fiber shows improved tensile properties as a result of the increased molecular orientation. The morphologies of the twisted fibers before and after drawing are compared.

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Preparation and Subsequent Shaping of Cellulose Acetates Using Ionic Liquids
Authors: Kosan Birgit , Dorn Susann , Meister Frank , Heinze Thomas
Published: June 2010

The acetylation of cellulose in ionic liquids (ILs) and the subsequent dry/wet spinning of these processing solutions were investigated. The homogeneous acetylation in ILs was carried out using different molar ratios of acetic anhydride to the anhydroglucose unit (AGU). The obtained solutions of cellulose acetates were characterised analytically by means of rheological methods. DS and $\overline {DP}$ of the prepared cellulose acetates were determined. Furthermore the processing solutions of the acetylation were shaped by means of a dry/wet spinning process to fibres with varied properties. The resulting fibre properties were discussed in consideration of the DS and in comparison with unsubstituted cellulose fibres.

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Towards Nanowriting on Plastics: Dip‐Pen Nanolithography of Acrylamido‐Functionalized Oligonucleotides on Polystyrene
Authors: Turri Stefano , Torlaj Luca , Levi Marinella
Published: June 2010

Model high density DNA arrays have been realized by direct deposition with Dip‐Pen Nanolithography of acrylamido‐functionalized oligonucleotides (23‐mer) on spin‐coated, flat polystyrene surfaces. A highly specific interaction between the acrylamide end functionality and polystyrene was found. The surface morphology of the model array was studied by atomic force microscopy (AFM). Spots are clearly seen both in topography and demodulation modes. The array withstands the hybridization process with label free, complementary oligonucleotides and the following cleaning procedures. The final AFM characterization showed significant changes especially in demodulation images which may be an indication that molecular recognition between complementary oligos has occurred.

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PNIPAM Copolymers Containing Light‐Responsive Chromophores: A Method Toward Molecular Logic Gates
Authors: Jochum Florian D. , Forst F. Romina , Theato Patrick
Published: June 2010

A series of thermo‐responsive PNIPAM copolymers containing different amounts of fulgimide moieties has been synthesized via a polymer analogous reaction of poly(pentafluorophenyl acrylate). All copolymers were designed to exhibit a lower critical solution temperature (LCST) in water, which was only weakly dependent on the amount of incorporated chromophoric fulgimide groups. The copolymers showed a photocyclization of the fulgimide side groups upon irradiation with UV‐light accompanied with a color change. The closed form of the chromophore had a halftime of 136 min for the visible reisomerization and did not affect the LCST of the polymer. This led to the realization of a logic “NOT A” for the fulgimide containing PNIPAM, while a corresponding azobenzene containing PNIPAM resulted in a different logic “A implies B”.

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Recyclable Spherical Polyelectrolyte Brushes Containing Magnetic Nanoparticles in Core
Authors: Chen Kaimin , Zhu Yan , Li Li , Lu Yan , Guo Xuhong
Published: June 2010

Spherical polyelectrolyte brushes consisting of a magnetite/polystyrene nanocomposite core and a poly(acrylic acid) brush shell were prepared by photo‐emulsion polymerization. They are narrowly dispersed, superparamagnetic and redispersible after aggregating by external magnetic field, as determined by transmission electron microscopy, dynamic light scattering, thermal gravimetric analysis and a vibrating sample magnetometer. Magnetic control is thus introduced into nano‐sized spherical polyelectrolyte brushes to achieve recovery and controllable delivery in applications. This approach opens up the way for cost‐effective applications of spherical polyelectrolyte brushes.

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Describing the Structure of a Randomly Hyperbranched Polymer
Authors: Konkolewicz Dominik , Gray‐Weale Angus , Perrier Sébastien
Published: June 2010

This paper describes random branching theory, a model for the solution structure of hyperbranched polymers. In this model, the hyperbranched polymer is assumed to be composed of units whose structure is simpler than the resulting polymer. These simple units can have any structure of chemical functionality, from monomers to linear chains or spherical particles. This paper outlines how this theory is constructed, describes the underlying assumptions and parameters, and summarizes the most basic form. It is shown how variations in the parameters change the behavior of the model, and described how to fit an experimental data series. This demonstrates how the model can be used to fit other data series, and how it can be used as a test for whether a polymer is randomly hyperbranched.

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Single nucleotide polymorphisms in the hypoxia‐inducible factor‐1 gene and colorectal cancer risk
Authors: Knechtel Gudrun , Szkandera Joanna , Stotz Michael , Hofmann Günter , Langsenlehner Uwe , Krippl Peter , Samonigg Hellmut , Renner Wilfried , Langner Cord , Dehchamani Dadbeh , Gerger Armin
Published: June 2010

With an incidence of about 300 000 new cases colorectal cancer (CRC) is the second leading cause of cancer‐related death in Europe and the United States. Environmental and genetic factors influence CRC risk. Hypoxia‐inducible factor‐1 (HIF‐1), a heterodimeric protein composed of two subunits, HIF‐1 alpha and HIF‐1 beta, plays a critical role in oxygen homeostasis and is involved in angiogenesis and cell proliferation. The gene for the HIF‐1 alpha subunit (HIF1A) carries two common missense mutations—P582S (rs11549465) and A588T (rs11549467)—which both have been related to increased trans‐activation capacity of HIF1A. In our case–control study we investigated the association between these polymorphisms and CRC risk. We investigated 381 patients with histologically confirmed CRC and 2156 control subjects. HIF1A genotypes were determined by exonuclease (TaqMan) assays. For determination of microvessel density (MVD) tumor sections were stained using a mouse monoclonal antibody recognizing the pan‐endothelial marker CD31. In a multivariate logistic regression analysis including age and sex neither the HIF1A 582S allele (Odds ratio: 1.204; 95% confidence interval 0.911–1.592; P = 0.193) nor the 588T allele was significantly associated with CRC (Odds ratio: 0.851; 95% confidence interval 0.444–1.631; P = 0.626). However, in an exploratory analysis, the HIF1A 588T allele was associated with tumor localization (P = 0.016) and tumor size (P = 0.003). MVD was similar in tumors of patients carrying HIF1A 588T allele and patients without this rare allele. We conclude that functional polymorphisms in the HIF1A gene do not modify CRC risk but maybe associated with clinic‐pathological features of the disease. © 2010 Wiley‐Liss, Inc.
Differential expression of nucleostemin, a stem cell marker, and its variants in different types of brain tumors
Authors: Malakootian Mahshid , Mowla Seyed Javad , Saberi Hooshang , Asadi Malek Hossein , Atlasi Yaser , Shafaroudi Afsaneh Malekzadeh
Published: June 2010

Nucleostemin (NS) is implicated in the control of stem and cancer cell proliferation. In the present study, we have examined the expression of NS and its spliced variants in various brain tumors. Total RNA was extracted from 59 brain tumor samples, and the expression of different NS spliced variants was measured by semi‐quantitative RT‐PCR. The subcellular distribution of NS protein in brain tumors was further examined by immunohistochemistry. Furthermore, to decipher the potential involvement of NS in brain tumorogenesis, its expression was knocked‐down by means of RNA interference (RNAi) in two malignant glioma (U‐87MG and A172), one astrocytoma (1321N1) and one medulloblastoma (DAOY) cell lines. The alterations in cell‐cycle progression of the treated cells were then analyzed by flow cytometry. Our data revealed that NS and its variants are widely expressed in different types of brain tumors. Among the NS spliced variants, variant “1” and variant “3” were detected in the majority of tumor samples, whereas variant “2” was only detectable in few samples. Moreover, the intensity of the expression was correlated with the grade of the tumors (P < 0.05). Accordingly, the expression was much higher in glial tumors compared to that of meningiomas. As expected, a nucleolar/nucleoplasmic localization of NS protein was observed in the examined tumor samples. RNAi results revealed a significant reduction of NS expression along with a moderate blockade of the cell cycle in G2/M and S phases of NS‐siRNA treated cells. All in all, our data suggest a potential role for NS in tumorogenesis of brain cancers. © 2010 Wiley‐Liss, Inc.
A simple low‐SAR technique for chemical‐shift selection with high‐field spin‐echo imaging
Authors: Ivanov Dimo , Schäfer Andreas , Streicher Markus N. , Heidemann Robin M. , Trampel Robert , Turner Robert
Published: June 2010

We have discovered a simple and highly robust method for removal of chemical shift artifact in spin‐echo MR images, which simultaneously decreases the radiofrequency power deposition (specific absorption rate). The method is demonstrated in spin‐echo echo‐planar imaging brain images acquired at 7 T, with complete suppression of scalp fat signal. When excitation and refocusing pulses are sufficiently different in duration, and thus also different in the amplitude of their slice‐select gradients, a spatial mismatch is produced between the fat slices excited and refocused, with no overlap. Because no additional radiofrequency pulse is used to suppress fat, the specific absorption rate is significantly reduced compared with conventional approaches. This enables greater volume coverage per unit time, well suited for functional and diffusion studies using spin‐echo echo‐planar imaging. Moreover, the method can be generally applied to any sequence involving slice‐selective excitation and at least one slice‐selective refocusing pulse at high magnetic field strengths. The method is more efficient than gradient reversal methods and more robust against inhomogeneities of the static (polarizing) field (B0). Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Rapid multislice imaging of hyperpolarized 13C pyruvate and bicarbonate in the heart
Authors: Lau Angus Z. , Chen Albert P. , Ghugre Nilesh R. , Ramanan Venkat , Lam Wilfred W. , Connelly Kim A. , Wright Graham A. , Cunningham Charles H.
Published: June 2010

Hyperpolarization of spins via dynamic nuclear polarization (DNP) has been explored as a method to non‐invasively study real‐time metabolic rocesses occurring in vivo using 13C‐labeled substrates. Recently, hyperpolarized 13C pyruvate has been used to characterize in vivo cardiac metabolism in the rat and pig. Conventional 3D spectroscopic imaging methods require in excess of 100 excitations, making it challenging to acquire a full cardiac‐gated, breath‐held, whole‐heart volume. In this article, the development of a rapid multislice cardiac‐gated spiral 13C imaging pulse sequence consisting of a large flip‐angle spectral‐spatial excitation RF pulse combined with a single‐shot spiral k‐space trajectory for rapid imaging of cardiac metabolism is described. This sequence permits whole‐heart coverage (6 slices, 8.8‐mm in‐plane resolution) in any plane, allowing imaging of the metabolites of interest, [1‐ 13C] pyruvate, [1‐ 13C] lactate, and 13C bicarbonate, within a single breathhold. Pyruvate and bicarbonate cardiac volumes were acquired, while lactate images were not acquired due to low lactate levels in the animal model studied. The sequence was demonstrated with phantom experiments and in vivo testing in a pig model. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Fast methods for determining instabilities of elastic–plastic damage models through closed‐form expressions
Authors: Xue Liang , Belytschko Ted
Published: June 2010

Fast methods for determining the onset of instability for elastic–plastic damage models under multiaxial loading conditions are developed. On the basis of the general Hadamard instability criterion, we derive a closed‐form expression to determine the onset of instability, the bifurcation directions and the polarization vector. The results of the present analytical method are compared with solutions using a numerical minimization method. Excellent agreement and significantly faster computations are achieved for the onset of instability and the directions of the instability mode and the polarization vector when using these new methods. Copyright © 2010 John Wiley & Sons, Ltd.
A symmetric weak form of Biot's equations based on redundant variables representing the fluid, using a Helmholtz decomposition of the fluid displacement vector field
Authors: Hörlin N.‐E.
Published: June 2010

A novel symmetric weak formulation of Biot's equations for linear acoustic wave propagation in layered poroelastic media is presented. The primary variables used are the frame displacement, the acoustic pore pressure, the scalar potential and the vector potential obtained from a Helmholtz decomposition of the fluid displacement. Also a symmetric weak form based on the frame displacement, the pore pressure and the fluid displacement is obtained as an intermediate result. hp finite element simulations of a double leaf partition based on this new weak formulation is verified against simulation results from the classical frame displacement, fluid displacement formulation and a frame displacement pore pressure formulation. All three formulations simulated, displays the same rate of convergence with respect to finite element bases polynomial degree. The novel formulation also extends a previously published frame displacement, pore pressure, scalar fluid displacement potential formulation with an implicit irrotational fluid displacement assumption to a full representation of Biot's equations. Copyright © 2010 John Wiley & Sons, Ltd.