bluuebunny/crossref_metadata_2025 huggingface dataset:
OPLA scaffold, collagen I, and horse serum induce a higher degree of myogenic differentiation of adult rat cardiac stem cells
Authors: Di Felice Valentina , Ardizzone Nella Maria , De Luca Angela , Marcianò Vito , Marino Gammazza Antonella , Macaluso Filippo , Manente Lucrezia , Cappello Francesco , De Luca Antonio , Zummo Giovanni
Published: September 2009

In the last few years, a major goal of cardiac research has been to drive stem cell differentiation to replace damaged myocardium. Several research groups have attempted to differentiate potential cardiac stem cells (CSCs) using bi‐ or three‐dimensional systems supplemented with growth factors or molecules acting as differentiating substances. We hypothesize that these systems failed to induce a complete differentiation because they lacked an architectural space. In the present study, we isolated a pool of small proliferating and fibroblast‐like cells from adult rat myocardium. The phenotype of these cells was assessed and the characterized cells were cultured in a collagen I/OPLA scaffold with horse serum to obtain fine myocardial differentiation. C‐KitPOS/Sca‐1POS CSCs fully differentiated in vitro when an environment more similar to the CSC niche was created. These experiments demonstrated an important model for the study of the biology of CSCs and the biochemical pathways that lead to myocardial differentiation. The results pave the way for a new surgical approach. J. Cell. Physiol. 221: 729–739, 2009. © 2009 Wiley‐Liss, Inc.
Molecular mechanisms mediating protective effect of cAMP on lipopolysaccharide (LPS)‐induced human lung microvascular endothelial cells (HLMVEC) hyperpermeability
Authors: Bogatcheva Natalia V. , Zemskova Marina A. , Kovalenkov Yevgeniy , Poirier Christophe , Verin Alexander D.
Published: September 2009

Up to date, the nature of the sepsis‐induced vascular leakage is understood only partially, which limits pharmacological approaches for its management. Here we studied the protective effect of cAMP using endotoxin‐induced hyperpermeability as a model for barrier dysfunction observed in gram‐negative sepsis. We demonstrated that the alleviation of lipopolysaccharide (LPS)‐induced barrier compromise could be achieved by the specific activation of either protein kinase A (PKA) or Epac with cAMP analogs Bnz‐cAMP or O‐Me‐cAMP, respectively. We next studied the involvement of PKA substrates VASP and filamin1 in barrier maintenance and LPS‐induced barrier compromise. Depletion of both VASP and filamin1 with the specific siRNAs significantly exacerbated both the quiescent cells barrier and LPS‐induced barrier dysfunction, suggesting barrier‐protective role of these proteins. VASP depletion was associated with the more severe loss of ZO‐1 peripheral staining in response to LPS, whereas filamin1‐depleted cells reacted to LPS with more robust stress fiber induction and more profound changes in ZO‐1 and VE‐cadherin peripheral organization. Both VASP and filamin1 phosphorylation was significantly increased as a result of PKA activation. We next analyzed the effect of VASP and filamin1 depletion on the PKA‐dependent alleviation of LPS‐induced barrier compromise. We observed that Bnz‐cAMP ability to counteract LPS‐induced hyperpermeability was attenuated only by VASP, but not filamin1 depletion. Our data indicate that while PKA‐dependent VASP phosphorylation contributes to the protective effect of cAMP elicited on LPS‐compromised monolayers, filamin1 phosphorylation is unlikely to play a significant role in this process. J. Cell. Physiol. 221: 750–759, 2009. © 2009 Wiley‐Liss, Inc.
Osteoblast differentiation is functionally associated with decreased AMP kinase activity
Authors: Kasai Takayuki , Bandow Kenjiro , Suzuki Hiraku , Chiba Norika , Kakimoto Kyoko , Ohnishi Tomokazu , Kawamoto Shin‐ichiro , Nagaoka Eiichi , Matsuguchi Tetsuya
Published: September 2009

Osteoblasts, originating from mesenchymal stem cells, play a pivotal role in bone formation and mineralization. Several transcription factors including runt‐related transcription factor 2 (Runx2) have been reported to be essential for osteoblast differentiation, whereas the cytoplasmic signal transduction pathways controlling the differentiation process have not been fully elucidated. AMP‐activated protein kinase (AMPK) is a serine–threonine kinase generally regarded as a key regulator of cellular energy homeostasis, polarity, and division. Recent lines of evidence have indicated that the activity of the catalytic α subunit of AMPK is regulated through its phosphorylation by upstream AMPK kinases (AMPKKs) including LKB1. Here, we explored the role of AMPK in osteoblast differentiation using in vitro culture models. Phosphorylation of AMPKα was significantly decreased during osteoblastic differentiation in both primary osteoblasts and MC3T3‐E1, a mouse osteoblastic cell line. Conversely, the terminal differentiation of primary osteoblasts and MC3T3‐E1 cells, represented by matrix mineralization, was significantly inhibited by glucose restriction and stimulation with metformin, both of which are known activators of AMPK. Matrix mineralization of MC3T3‐E1 cells was also inhibited by the forced expression of a constitutively active form of AMPKα. Metformin significantly inhibited gene expression of Runx2 along with osteoblast differentiation markers including osteocalcin (Ocn), bone sialo protein (Bsp), and osteopontin (Opn). Thus, our present data indicate that differentiation of osteoblasts is functionally associated with decreased AMPK activity. J. Cell. Physiol. 221: 740–749, 2009. © 2009 Wiley‐Liss, Inc.
Immunohistochemical characterization of TH13‐L2 spinal ganglia neurons in sheep (Ovis aries)
Authors: Russo Domenico , Clavenzani Paolo , Mazzoni Maurizio , Chiocchetti Roberto , Di Guardo Giovanni , Lalatta‐Costerbosa Giovanna
Published: September 2009

Spinal ganglia (SG) neurons are commonly classified according to various specific features. The most widespread classification based on morphological and ultrastructural features subdivides SG neurons into light and small dark neurons. Using immunohistochemical, histochemical and lectin methods, it is possible to further subdivide the small dark neurons into two subpopulations: peptidergic and nonpeptidergic neurons. The majority of studies on SG neurons were carried out on mice and rats; there are few or no studies on large mammals. In this study, some of the widely used neuronal markers, neurofilament 200 kDa (NF200), substance P (SP), calcitonin gene‐related peptide (CGRP) and isolectin B4 (IB4), were employed to characterize neuronal nitric oxide synthase (nNOS)‐immunoreactivity (‐IR) in sheep (Ovis aries) SG (Th13‐L2) neurons. The majority of the SG neurons were IB4‐labeled (79 ± 10%), followed by NF200‐ (45 ± 4%), NOS‐ (44 ± 10%), SP‐ (42 ± 5%) and CGRP‐IR (35 ± 7%) neurons. The triple staining experiments showed that a higher percentage (75 ± 16%) of NOS‐IR neurons bound both IB4 and CGRP, or both IB4 and SP (49 ± 6%). The IB4 marker showed an unexpected staining pattern; in fact, IB4‐labeled neurons largely colocalized with NF200, usually considered a marker of light SG neurons, and with CGRP and SP. For this reason, IB4 cannot be employed in sheep to differentiate between light and dark neurons, or between peptidergic and nonpeptidergic neurons. These results suggest the importance of being cautious when comparing data among different species. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Time‐series investigation of fused vesicles in microvessel endothelial cells with atomic force microscopy
Authors: Chen Long , Chu Weiguo , Xu Yonggang , Chen Peipei , Lao Fang , Sun Quanmei , Feng Xizeng , Han Dong
Published: September 2009

Vesicles or caveolae within endothelial cells, fusing together to form vacuolar organelles, are implicated in macromolecular transport and cellular element transmigration across the blood–brain barrier (BBB) during inflammation and ischemia. Vacuolar organelles have been described by transmission electron microscopy and immunofluorescence, but the details of their dynamics have not been well addressed yet. Herein, by using tapping mode atomic force microscopy (AFM), we observed the time‐series changes of fused vesicles within the serum‐free cultured rat cerebral microvessel endothelial cells. The fused vesicles were certainly proved by fluorescent staining of Fm4‐64 combining simultaneous AFM imaging, as well as the field emission scanning electron microscopy technique. And energy dispersive spectrum results additionally implied that there may be specific structure and compositions around the vesicle region. These results indicate that increased vesicles in BBB may contribute to the formation of fused vesicles and a higher probability to construct the trans‐endothelial channel across endothelium layer. Furthermore, the AFM application may open up a new approach to investigate the details of transcellular process by fused vesicles. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Automated compensation of light attenuation in confocal microscopy by exact histogram specification
Authors: Stanciu Stefan G. , Stanciu George A. , Coltuc Dinu
Published: September 2009

Confocal laser scanning microscopy (CLSM) enables us to capture images representing optical sections on the volume of a specimen. The images acquired from different layers have a different contrast: the images obtained from the deeper layers of the specimen will have a lower contrast with respect to the images obtained from the topmost layers. The main reasons responsible for the effects described above are light absorption and scattering by the atoms and molecules contained in the volume through which the light passes. Also light attenuation can be caused by the inclination of the observed surface. In the case of the surfaces that have a steep inclination, the reflected light will have a different direction than the one of the detector. We propose a technique of digital image processing that can be used to compensate the effects of light attenuation based on histogram operations. We process the image series obtained by CLSM by exact histogram specification and equalization. In this case, a strict ordering among pixels must be induced in order to achieve the exact histogram modeling. The processed images will end up having exactly the specified histogram and not a histogram with a shape that just resembles to the specified one, as in the case of classical histogram specification algorithms. Experimental results and theoretical aspects of the induced ordering are discussed, as well as a comparison between several histogram modeling techniques with respect to the processing of image series obtained by confocal microscopy. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
MRT letter: Recovering weak‐textured surfaces using image focus
Authors: Muhammad Mannan Saeed , Choi Tae‐Sun
Published: September 2009

In nature, objects have partially weak texture and their shape reconstruction using focus based passive methods like shape from focus (SFF), is difficult. This article presents a new SFF algorithm which can compute precise depth of dense as well as weak textured objects. Segmentation is applied to discard wrong depth estimate and then later interpolating them from accurate depth values of their neighbors. The performance of the proposed method is tested, using different image sequences of synthetic and real objects, with varying textures. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.
The toxic effect of ketamine on SH‐SY5Y neuroblastoma cell line and human neuron
Authors: Mak Ying T. , Lam Wai P. , Lü Lanhai , Wong Yeuk W. , Yew David T.
Published: September 2009

Ketamine used as an injectable anesthetic in human and animal medicine is also a recreational drug used primarily by young adults often at all night dance parties in nightclubs. The percentage of ketamine users has grown very fast in the last 5 years worldwide. However, this leads to the serious question of the long‐term adverse effects of ketamine on our nervous system, particularly the brain, because ketamine as an NMDA antagonist could cause neurons to commit apoptosis. Our study therefore aimed to find out the chronic effect of ketamine on neuron using prolonged incubation (48 h) of neuronal cells with ketamine in culture. Our results showed that differentiated neuronal cells were prone to the toxicity of ketamine but probably less susceptible than undifferentiated neuronal cells and fibroblasts. This suggested that the ketamine abuse would be harmful to many other organs as well as the brain. Our results also confirmed that the toxicity of ketamine is related to apoptosis via the Bax/Bcl‐2 ratio pathway and caspase‐3 in the differentiated neuronal cells. Therefore, long‐term ketamine treated cell or animal models should be sought to study this multiorgan effects of ketamine. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
Differences between nanoscale structural and electrical properties of AZO:N and AZO used in polymer light‐emitting diodes
Authors: Chen Sy‐Hann , Yu Chang‐Feng
Published: September 2009

Conducting atomic force microscopy and scanning surface potential microscopy were adopted to investigate the nanoscale surface electrical properties of N‐doped aluminum zinc oxide (AZO:N) films that were prepared by pulsed laser deposition (PLD) at various substrate temperatures. Experimental results demonstrated that when the substrate temperature is 150°C and the N2O background pressure is 150 mTorr, the N‐dopant concentration on the surface is optimal. In addition, the root‐mean‐square roughness value of the film surface, the low contact current (<400 nA) conducting region as a percentage of the total area, and the mean work function value are 1.43 nm, 96.9%, and 4.88 eV, respectively, all of which are better than those of the optimal AZO film made by PLD. This result indicates that N‐doped AZO films are better for use as window materials in polymer light‐emitting diodes. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.
The ultrastructure of malpighian tubules and the chemical composition of the cocoon of Aeolothrips intermedius Bagnall (Thysanoptera)
Authors: Conti Barbara , Berti Francesco , Mercati David , Giusti Fabiola , Dallai Romano
Published: September 2009

The secretory activity of the two branched malpighian tubules (MTs) of the second‐instar larva in Aeolothrips intermedius is described. MTs of adult thrips have the typical ultrastructure of excretory epithelium with apical microvilli containing long mitochondria and a rich system of basal membrane infoldings. In the second‐instar larva just before pupation, the ultrastructure of MT epithelial cells is dramatically different, and there are numerous huge Golgi systems in the cytoplasm. These cells are involved in an intense secretory activity to produce an electron‐dense product which is released into the MTs lumen. This secretion is extruded from the hindgut and used by the second‐instar larva to build an elaborate protective cocoon for pupation. Electron‐spray‐ionization mass spectrometry analysis of the cocoon revealed the presence of a β‐N‐acetyl‐glucosamine, the main component of chitin, which is also present in the cocoons of Neuroptera and some Coleoptera. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.
Sensitivity analysis of lossy nonuniform multiconductor transmission lines based on the Lax‐Wendroff technique
Authors: Dou Lei , Dou Jiao
Published: September 2009

This paper applies the Lax‐Wendroff technique, usually used in fluid dynamics, to transmission line sensitivity analysis. A second‐order‐accurate Lax‐Wendroff difference scheme for sensitivity analysis of both uniform and nonuniform transmission lines is derived. Based on this scheme, a new method for analyzing multiconductor transmission line sensitivity, which does not need to be decoupled, is presented by combining with matrix operations. Using numerical experiments, the proposed method is compared with the characteristic method and the fast Fourier transform approach. With the presented method, the sensitivity of a nonlinear circuit including nonuniform multiconductor transmission lines is analyzed and the results are verified by the HSPICE perturbation method. The proposed method can be applied to either linear or nonlinear circuits, which include lossy nonuniform multiconductor transmission lines and is proved to be efficient. Copyright © 2009 John Wiley & Sons, Ltd.
Careers as tournaments: The impact of sex and gendered organizational culture preferences on MBAs' income attainment
Authors: O'Neill Olivia A. , O'Reilly Charles A.
Published: September 2009

Drawing on gender role theory and tournament theory, we examined the effects of sex and organizational culture preferences on the incomes of MBA graduates over an 8‐year period. We found that masculine culture preferences led to higher income 4 years after graduation and, in contrast to previous research, the effect was stronger for women. By 8 years after graduation, however, men's rate of income increase was significantly higher than women's, an effect that was mediated by hours worked per week. These findings clarify some of the conflicting results of previous research on the effects of gender roles on women's careers and suggest that a tournament‐like aspect of careers may account for higher incomes in organizations. Copyright © 2009 John Wiley & Sons, Ltd.
N‐acetylcysteine prevents nitric oxide‐induced chondrocyte apoptosis and cartilage degeneration in an experimental model of osteoarthritis
Authors: Nakagawa Shuji , Arai Yuji , Mazda Osam , Kishida Tsunao , Takahashi Kenji A. , Sakao Kei , Saito Masazumi , Honjo Kuniaki , Imanishi Jiro , Kubo Toshikazu
Published: September 2009

We investigated whether N‐acetylcysteine (NAC), a precursor of glutathione, could protect rabbit articular chondrocytes against nitric oxide (NO)‐induced apoptosis and could prevent cartilage destruction in an experimental model of osteoarthritis (OA) in rats. Isolated chondrocytes were treated with various concentrations of NAC (0–2 mM). Apoptosis was induced by 0.75 mM sodium nitroprusside (SNP) dehydrate, which produces NO. Cell viability was assessed by MTT assay, while apoptosis was evaluated by Hoechst 33342 and TUNEL staining. Intracellular reactive oxygen species (ROS) and glutathione levels were measured, and expression of p53 and caspase‐3 were determined by Western blotting. To determine whether intraarticular injection of NAC prevents cartilage destruction in vivo, cartilage samples of an OA model were subjected to H&E, Safranin O, and TUNEL staining. NAC prevented NO‐induced apoptosis, ROS overproduction, p53 up‐regulation, and caspase‐3 activation. The protective effects of NAC were significantly blocked by buthionine sulfoximine, a glutathione synthetase inhibitor, indicating that the apoptosis‐preventing activity of NAC was mediated by glutathione. Using a rat model of experimentally induced OA, we found that NAC also significantly prevented cartilage destruction and chondrocyte apoptosis in vivo. These results indicate that NAC inhibits NO‐induced apoptosis of chondrocytes through glutathione in vitro, and inhibits chondrocyte apoptosis and articular cartilage degeneration in vivo. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:156–163, 2010
Relative contributions of mechanical degradation, enzymatic degradation, and repair of the extracellular matrix on the response of tendons when subjected to under‐ and over‐ mechanical stimulations in vitro
Authors: Cousineau‐Pelletier Paule , Langelier Eve
Published: September 2009

Tendon response to mechanical loading results in either homeostasis, improvement, or degeneration of tissue condition. In an effort to better understand the development of tendinopathies, this study investigated the mechanical and structural responses of tendons subjected to under‐ and over‐stimulations (1.2% and 1.8% strain respectively, 1 Hz). The objective was to examine three sub‐processes of tendon response: mechanical degradation, enzymatic degradation, and repair of the extracellular matrix. We subjected rat tail tendons to a 10‐day stimulation protocol with four periods of 6 h each day: 30 min of stimulation and 5 h 30 min of rest. To investigate the contribution of the three sub‐processes, we controlled the contribution of the cells through variations in the nutrient and protease inhibitor content in the in vitro solutions. Using nondestructive cyclic tests, we evaluated the daily changes in the peak stress. To assess structural changes, we carried out microscopic analyses at the end of the study period. We observed that the relative contributions of the sub‐processes differed according to the stimulation amplitude. With over‐stimulation of tendons immersed in DMEM, we succeeded in reducing enzymatic degradation and increasing peak stress. In under‐stimulation, the addition of protease inhibitors was required to obtain the same result. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:204–210, 2010
Decrease in particle‐induced osteolysis in ovariectomized mice
Authors: Nich Christophe , Marchadier Arnaud , Sedel Laurent , Petite Hervé , Vidal Catherine , Hamadouche Moussa
Published: September 2009

Postmenopausal osteoporosis is a common disorder that results from increased osteoclastic activity caused by estrogen deficiency. Whether postmenopausal bone remodeling can alter the response to particulate debris is unknown. The purpose of this study was to evaluate the bone response to polyethylene particles in an ovariectomized murine model. Polyethylene particles were implanted onto the calvaria of seven control mice and seven ovariectomized (OVX) mice, as compared with calvaria from sham‐operated and OVX mice. Calvaria were harvested after 14 days. Skulls were analyzed with a high‐resolution micro‐CT and by histomorphometry after staining with Stevenel blue and picrofuschine, and for tartrate‐specific alkaline phosphatase. As assessed by micro‐CT, particle implantation induced a significant decrease in bone thickness in control mice, while bone thickness remained stable in OVX mice. In particle‐implanted animals, the osteoclast number was 2.84 ± 0.3 in control mice and 1.74 ± 0.22 in OVX mice. Mean bone loss was −12% ± 1.9% in control mice and −4.7% ± 1.7% in OVX animals. The reduction of osteolytic response suggests that ovariectomy may have a protective role against particle‐induced bone resorption. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:178–183, 2010
Use of thermo‐Raman spectroscopy and chemometric analysis to identify dehydration steps of hydrated inorganic samples—application to copper sulfate pentahydrate
Authors: Widjaja Effendi , Chong Hui Heng , Tjahjono Martin
Published: September 2009

In situ thermo‐Raman spectroscopy (TRS) measurements were performed in order to investigate solid‐phase transformation of the copper sulfate pentahydrate from room temperature up to 300 °C. Band‐target entropy minimization (BTEM), a blind‐source separation algorithm, was employed in order to identify and reconstruct the pure component spectra of the species involved in the dehydration process. In spite of low signal‐to‐noise ratio and elevated baseline spectral data, BTEM was successfully utilized to identify and reconstruct four pure component spectra of copper sulfate pentahydrate, trihydrate, monohydrate, and anhydrate, which were formed during this thermally induced process. Subsequent mapping of these four pure component spectral estimates back onto the preprocessed spectra yielded the relative concentrations of each individual species. Finally, the transition temperatures of each dehydration step could be unambiguously deduced from the obtained concentration profile. The current study shows that combined thermo‐Raman spectroscopy and chemometric analysis provides an effective tool to determine the dehydration temperatures as well as to identify the structures of each individual species involved in a solid‐phase dehydration process. Copyright © 2009 John Wiley & Sons, Ltd.
Raman and infrared spectra, conformational stability, ab initio calculations and vibrational assignment of dimethylsilylisocyanate
Authors: Guirgis Gamil A. , Zhou Sarah Xiaohua , Durig James R.
Published: September 2009

The Raman (3200‐30 cm−1) and/or infrared spectra (3500 to 400 cm−1) of gaseous, liquid and solid dimethylsilylisocyanate, (CH3)2 Si(H)NCO, have been recorded. The MP2(full) calculations, employing a variety of basis sets with and without diffusion functions, have been used to predict the structural parameters, conformational stability, vibrational fundamental wavenumbers, Raman activities, depolarization values and infrared intensities to support the vibrational assignment. The low wavenumber Raman spectrum of the gas with a significant number of Q‐branches for the SiNC(O) bend is consistent with an essentially linear SiNCO moiety. The ab initio calculations supported this conclusion as all possible orientations of the NCO moiety lead to nearly the same energy. This result is at variance with the conclusion from the electron diffraction study that the heavy atom skeleton was bent with an angle of 152(5)° with one stable cis conformer. It is believed that this reported angle difference from 180° is due to the shrinkage effect. The SiH distance of 1.486 Å has been obtained from the isolated SiH stretching wavenumber. From the adjustment of the ab initio MP2(full)/6‐311+G(d,p) predicted structural parameters, a proposed structure is reported, which is expected to give rotational constants within a few megahertz of the actual ones. These experimental and theoretical results are compared with the corresponding quantities of similar molecules. Copyright © 2009 John Wiley & Sons, Ltd.
Electromagnetic field enhancement in TERS configurations
Authors: Yang Zhilin , Aizpurua Javier , Xu Hongxing
Published: September 2009

We use three‐dimensional finite‐difference time domain (3D‐FDTD) simulations to investigate the field enhancement properties of tip‐enhanced Raman scattering (TERS) in order to find optimal geometric parameters of the metal tip and the metal substrate under certain excitation wavelengths with side illumination. The simulation results show that plasmon coupling effects between the metal tip and the metal substrate play the key role in TERS enhancement, and the enhancement drops dramatically as the distance between the tip and the substrate increases. The spatial resolution of TERS is mainly dependent on the radius of curvature of the tip end. A sharp tip with a small radius can dramatically increase the spatial resolution of TERS. Increasing the tip–substrate distance or changing the metallic substrate into a dielectric substrate lowers the spatial resolution. The TERS enhancement dependence on the incident angle and polarization, the size of tip, as well as the composition of the substrate is also discussed in detail. Copyright © 2009 John Wiley & Sons, Ltd.
A complete Raman mapping of phase transitions in Si under indentation
Authors: Das C. R. , Hsu H. C. , Dhara S. , Bhaduri A. K. , Raj B. , Chen L. C. , Chen K. H. , Albert S. K. , Ray A. , Tzeng Y.
Published: September 2009

Crystalline Si substrates are studied for pressure‐induced phase transformation under indentation at room temperature (RT) using a Berkovich tip. Raman spectroscopy, as a nondestructive tool, is used for the identification of the transformed phases. Raman lines as well as area mapping are used for locating the phases in the indented region. Calculation of pressure contours in the indented region is used for understanding the phase distribution. We report here a comprehensive study of all the phases of Si, reported so far, leading to possible understanding of material properties useful for possible electromechanical applications. As a major finding, distribution of the amorphous phase in the indented region deviates from the conventional wisdom of being in the central region alone. We present phase mapping results for both Si(100) and Si(111) substrates. Copyright © 2009 John Wiley & Sons, Ltd.
Characterisation of FXTAS related isolated intranuclear protein inclusions using laser tweezers Raman spectroscopy
Authors: Moritz Tobias J. , Brunberg James A. , Krol Denise M. , Wachsmann‐Hogiu Sebastian , Lane Stephen M. , Chan James W.
Published: September 2009

We report the analysis of the vibrational modes of intranuclear protein inclusions isolated from the brain of human subjects with the Fragile X‐associated tremor/ataxia syndrome (FXTAS). In this preliminary study, Raman spectra of optically trapped inclusions were measured and analysed to determine protein composition and structure. Our main findings are as follows: (1) The spectra of protein inclusions are characteristic of H2A and H2B histones, which correlate with previous mass spectrometry (MS) studies; (2) Tyrosine is present in its OH form and exposed at the protein surface; (3) Zn and to a lesser extent Cu bound to histidine side chains are detected in the inclusions; (4) The tryptophan side‐chain torsion angle is calculated to be 102°; (5) Several potential spectroscopic markers for the inclusions of FXTAS are identified. These results show the capability of using laser tweezers Raman spectroscopy to identify protein inclusions in a non‐perturbative way and to gain further insight into the pathogenesis and progression of FXTAS in human subjects and in experimental models of this disorder. Copyright © 2009 John Wiley & Sons, Ltd.
Raman spectroscopy of synthetic, geological and biological vaterite: a Raman spectroscopic study
Authors: Wehrmeister U. , Soldati A. L. , Jacob D. E. , Häger T. , Hofmeister W.
Published: September 2009

Raman spectroscopy was used to study vaterite samples of biological, geological and synthetic origin. The Raman band positions and the full width at half‐maximum (FWHM) of the lattice modes and the internal modes of the carbonate ion of all specimens show no significant differences between vaterites of different origin. With increasing Mg concentrations, synthetic vaterite samples show increasing FWHM in the region of the lattice modes and the three ν1 bands, whereas no change in luminescence was detected. In contrast, in situ measurements of vaterite areas in freshwater cultured pearls (FWCPs) by laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) together with the Raman spectra obtained at the same points show that the luminescence intensity in biological samples is affected by the magnesium content. The Raman spectroscopic features of vaterite and parisite‐(Ce) are compared, and their similarities suggest that the structure of vaterite contains at least three crystallographically independent carbonate groups and similar carbonate group layers. A band at 263 cm−1 is observed for the first time in this study, whereas it could be demonstrated that bands previously reported at 130 and 190 cm−1 do not belong to vaterite. Copyright © 2009 John Wiley & Sons, Ltd.
Local field enhancement of an infinite conical metal tip illuminated by a focused beam
Authors: Zhang Weihua , Cui Xudong , Martin Olivier J. F.
Published: September 2009

We present a systematic numerical investigation of conical metal tips which are commonly used in tip‐enhanced Raman spectroscopy (TERS). Different from previous studies, we focus on how the tip length and the illumination condition influence the local field enhancement at the tip apex, and provide a useful reference for real experiments. In particular, we show that the type of illumination has a dramatic influence on the field enhancement: a localized illumination spot—as used in experiments—producing a very different response than a plane wave illumination—as usually used in previous models. Also, the effect of the different geometrical parameters, such as the sharpness of the tip apex and the cone angle, provides guidance to optimize the tip design. Finally, we investigate the influence of the substrate and compare numerical data with results deduced from a simplified model, finding good agreement. This brings new insights into the enhancement mechanism of TERS. Copyright © 2009 John Wiley & Sons, Ltd.
Detection of small amounts of H2O in CO2‐rich fluid inclusions using Raman spectroscopy
Authors: Berkesi Márta , Hidas Károly , Guzmics Tibor , Dubessy Jean , Bodnar Robert J. , Szabó Csaba , Vajna Balázs , Tsunogae Toshiaki
Published: September 2009

Raman spectroscopic analysis at low (−100 °C) or high (100–200 °C) temperature is shown to be effective for detecting small amounts of H2O in CO2‐rich fluid inclusions from the deep lithosphere, which have previously been thought to be water‐free. Copyright © 2009 John Wiley & Sons, Ltd.
Raman spectroscopy of topiramate under high pressure conditions
Authors: Sena Diniz M. , Freire Paulo T. C. , Filho Josué M. , Melo Francisco E. A.
Published: September 2009

Topiramate is a white crystalline solid with powerful anticonvulsant activity and is used to treat epilepsy. Drug manufacturing involves various physical and chemical processes, which may lead to the formation of an unexpected, or undesired, crystalline phase, in a phenomenon known as polymorphism. In this paper, the behavior of topiramate crystal is studied under pressures up to 10.8 GPa using Raman spectroscopy. Under the conditions employed, Raman spectra from topiramate under pressure showed no strong evidence of a phase change, although amorphization may be considered. This may be accounted for by its crystal structure, comprising oppositely running chains of topiramate molecules linked by asymmetric hydrogen bonds, which pose a kinetic barrier against a structural change. It is not yet safe to rule out the existence of topiramate polymorphs, which could possibly be obtained under special crystallization conditions, but not after compression, at least up to 10 GPa. Copyright © 2009 John Wiley & Sons, Ltd.
Adjustment and control of SERS activity of metal substrates by pressure
Authors: Xia Lixin , Jia Yi , Liu Guangye , Yang Zhilin , Chen Xiaowei , Zhang Huili , Sun Mengtao
Published: September 2009

Metal pellets of silver and copper for surface‐enhanced Raman scattering (SERS) spectroscopy were prepared by compression with different pressures. It was found that the SERS activity of the pellet could be controlled by pressure. Enhanced Raman scattering properties of the metal pellets in the presence of adsorbed 4‐mercaptobenzoic acid (4‐MBA) with excitation at 632.8 or 514 nm could be obtained by choosing proper pressure of pellatization. The SERS peak intensity of the band at ∼1584 cm−1 of 4‐MBA adsorbed on the metal pellets varies as a function of applied pressure, and which is about 1.2–32 times greater than when it is adsorbed on silver and copper particles. The calculated results of three‐dimensional finite‐difference time‐domain method (3D‐FDTD) are in good agreement with the experimental data. Moreover, no spurious peaks appear in the SERS spectra of the samples because no other chemicals are involved in the simple preparation process of the metal pellets, which will facilitate its use as an SERS‐active substrate for analytical purposes. In summary, SERS‐active metal pellets can be produced simply and cost effectively by the method reported here, and this method is expected to be utilized in the development of SERS‐based analytical devices. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis of Well‐Defined Telechelic Macrophotoinitiator of Polystyrene by Combination of ATRP and Click Chemistry
Authors: Degirmenci Mustafa , Genli Nasrettin
Published: September 2009

A new well‐defined telechelic macrophotoinitiator of polystyrene was synthesized by combination of ATRP and click chemistry. The ATRP of styrene by means of 2‐oxo‐1,2‐diphenylethyl‐2‐bromopropanoate (PI‐Br) initiator with CuBr/2,2′‐bipyridine yields polystyrene with photoactive benzoin (PI) and bromine (Br) group (PI‐PSt‐Br). Subsequently, PI‐PSt‐Br was converted to PI‐PSt‐N3 by simple nucleophilic substitution reaction. Alkyne functionalized benzoin (PI‐alkyne) was synthesized by using benzoin photoinitiator and propargyl bromide. Then the coupling reaction between PI‐PSt‐N3 and PI‐alkyne was performed by Cu(I) catalysis. The spectroscopic studies revealed that low‐polydispersity polystyrene with desired photoinitiator functionality at both end of the chain, PI‐PSt‐PI, was obtained.

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Determining Initiator Efficiency in Radical Polymerization by Electrospray‐Ionization Mass Spectrometry
Authors: Buback Michael , Frauendorf Holm , Günzler Fabian , Huff Felix , Vana Philipp
Published: September 2009

A method for measuring initiator efficiency in radical polymerization using ESI‐MS is presented. The method is based on the evaluation of relative MS peak intensities of polymer that has been initiated by a mixture of initiators, of which one serves as an internal reference. The method is quickly and easily performed and was found to be reproducible and robust. In polymerization of methyl methacrylate in solution, the efficiency of BTMHP at 80 °C was determined to be fBTMHP = 0.57 ± 0.08, and the efficiency of DBPO at 100 °C was measured to be fDBPO = 0.89 ± 0.08.

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Synthesis and Characterization of Alternating and Random Copolymer Brushes
Authors: Ishizu Koji , Okamoto Nobuyuki , Murakami Takuya , Uchida Satoshi , Nojima Schuichi
Published: September 2009

Alternating free‐radical copolymerization of vinylbenzyl‐ and methacryloyl‐terminated macromonomers in the presence of Lewis acid was applied to the synthesis of prototype copolymer brushes composed of polystyrene/poly(ethylene oxide) (PS/PEO) alternating structure. Random copolymer brushes were also prepared by radical copolymerization of both macromonomers in the absence of Lewis acid. It was found from dilute solution properties that both copolymer brushes composed of short aspect ratio formed an ellipsoid‐like single molecule in solution. To discuss the intramolecular phase separation of PS/PEO brushes in solution, we determined the radius of gyration (Rg) and cross‐sectional radius of gyration (Rg,c) of copolymer brushes by small‐angle X‐ray scattering (SAXS) using Guinier's plots in DMF and styrene. We used styrene as a solvent to cancel each other out with the electron density of PS side chains. We made also clear the effect of branching topology on polymer crystallinity to be examined by comparing the copolymer brushes with corresponding linear PEO or PEO‐block‐PS block copolymer.

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Melt Dispersion and Electrospinning of Non‐Functionalized Multiwalled Carbon Nanotubes in Thermoplastic Polyurethane
Authors: Hunley Matthew T. , Pötschke Petra , Long Timothy E.
Published: September 2009

Nanoscale fibers with embedded, aligned, and percolated non‐functionalized multiwalled carbon nanotubes (MWCNTs) were fabricated through electrospinning dispersions based on melt‐compounded thermoplastic polyurethane/MWCNT nanocomposite, with up to 10 wt.‐% MWCNTs. Transmission electron microscopy indicated that the nanotubes were highly oriented and percolated throughout the fibers, even at high MWCNT concentrations. The coupling of efficient melt compounding with electrospinning eliminated the need for intensive surface functionalization or sonication of the MWCNTs, and the high aspect ratio as well as the electrical and mechanical properties of the nanotubes were retained. This method provides a more efficient technique to generate one‐dimensional nanofibers with aligned MWCNTs.

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Effective reaction rates of a thin catalyst layer
Authors: Lenzinger Michael , Schweizer Ben
Published: September 2009

The catalyst layer in a fuel cell can be described with a system of reaction diffusion eq
uations for the oxygen concentration and the protonic overpotential. The Tafel law gives an exponential expression for the reaction rate, and the Tafel slope is a coefficient in this law. We present a rigorous thin layer analysis for two reaction regimes. In the case of thin catalyst layers and bounded potentials, the original Tafel law enters as an effective boundary condition. Instead, in the case of large protonic overpotentials, we derive an exponential law that contains the doubled Tafel slope. Copyright © 2009 John Wiley & Sons, Ltd.
Experimental protocol for activation‐induced manganese‐enhanced MRI (AIM‐MRI) based on quantitative determination of Mn content in rat brain by fast T1 mapping
Authors: Tambalo S. , Daducci A. , Fiorini S. , Boschi F. , Mariani M. , Marinone M. , Sbarbati A. , Marzola P.
Published: September 2009

In activation‐induced manganese‐enhanced MRI (AIM‐MRI) experiments, differential accumulation of Mn in activated and silent brain areas is generally assessed using T1‐weighted images and quantified by the enhancement of signal intensity (SI), calculated with reference to SI before Mn administration or to SI of brain regions unaffected by the specific stimulus. However, SI enhancement can be unreliable when animals are removed from and reinserted into the magnet. We have developed an experimental protocol based on repeated intraperitoneal (i.p.) injections of Mn, quantitative determination of T1, and coregistration of images to a rat brain atlas that allows absolute quantification of Mn concentration in selected brain areas. Results showed that interanimal variability of postcontrast T1 values was very low (compared to the experimental error in T1 determinations) allowing detection of differential regional Mn uptake in stimulated and unstimulated animals. In addition we have determined in vivo relaxivity of Mn in brain tissue and its frequency dependence. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
An elasto‐plastic three phase model for partially saturated soil for the finite element simulation of compressed air support in tunnelling
Authors: Nagel F. , Meschke G.
Published: September 2009

This paper presents a fully coupled finite element formulation for partially saturated soil as a triphasic porous material, which has been developed for the simulation of shield tunnelling with heading face support using compressed air. While for many numerical simulations in geotechnics use of a two‐phase soil model is sufficient, the simulation of compressed air support demands the use of a three‐phase model with the consideration of air as a separate phase. A multiphase model for soft soils is developed, in which the individual constituents of the soil—the soil skeleton, the fluid and the gaseous phase—and their interactions are considered. The triphasic model is formulated within the framework of the theory of porous media, based upon balance equations and constitutive relations for the soil constituents and their mixture. An elasto‐plastic, cam–clay type model is extended to partially saturated soil conditions by incorporating capillary pressure according to the Barcelona basic model. The hydraulic properties of the soil are described via DARCY's law and the soil–water characteristic curve after VAN GENUCHTEN. Water is modelled as an incompressible and air as a compressible phase. The model is validated by means of selected benchmark problems. The applicability of the model to geotechnical problems is demonstrated by results from the simulation of a compressed air intervention in shield tunnelling. Copyright © 2009 John Wiley & Sons, Ltd.
A new Taylor collocation method for nonlinear Fredholm‐Volterra integro‐differential equations
Authors: Bülbül Berna , Gülsu Mustafa , Sezer Mehmet
Published: September 2009

The aim of this article is to present an efficient numerical procedure for solving nonlinear integro‐differential equations. Our method depends mainly on a Taylor expansion approach. This method transforms the integro‐differential equation and the given conditions into the matrix equation which corresponds to a system of nonlinear algebraic equations with unkown Taylor coefficients. The reliability and efficiency of the proposed scheme are demonstrated by some numerical experiments and performed on the computer program written in Maple10. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010
Sequential quadratic programming and analytic hierarchy process for nonlinear multiobjective optimization of a hydropower network
Authors: Moosavian S. Ali A. , Ghaffari Ali , Salimi Amir
Published: September 2009

In this paper, an optimal annual scheduling for power generation (i.e. rule curves and volume of water releases) in serial or parallel hydropower plants is developed. Multiobjective programming and weighted sum method are used to convert a multiobjective problem to a single objective one. Furthermore, to obtain viable alternatives under existing uncertainty, some random weight vectors in the whole weighting space are generated and for each weight vector an optimal solution is found using sequential quadratic programming (SQP). Then, analytic hierarchy process (AHP) is used to select the best solution according to a given criterion, and determine the most preferred one. Besides, this method does not require choosing a priori preference for the objective function, thus making an ideal tool for handling complicated multiobjective models and easy to use with the aid of computer programs. Combination of multiobjective optimization and multicriteria decision analysis (MCDA) is an integrated methodology that is capable of dealing with complex water management problems. Various scenarios for dry, median, and wet years are assumed based on stochastic flows from external sources (e.g. flooding rivers, unexpected rains, etc.) coming into each reservoir, and turbine power generation is obtained from hill diagrams provided by the manufacturer. The application of this methodology is illustrated in a case study for optimal scheduling of Karoon River Basin, where the decision support system and optimization routines are implemented in MATLAB. The total energy productions for 10 optimized solutions under dry, median, and wet scenarios (generated from forty‐year historical inflow records) are calculated, and specific water consumption for each reservoir is obtained in different months. This can significantly help decision makers to have an optimal and more intelligent management over energy productions in hydropower plants and associated thermal power plants. Copyright © 2009 John Wiley & Sons, Ltd.
Polymeric gels and hydrogels for biomedical and pharmaceutical applications
Authors: Jagur‐Grodzinski Joseph
Published: September 2009

Hydrogels are formed when a three‐dimensional polymeric network is loosely crosslinked. They are swollen by water but not dissolved in it. Hydrogels may display reversible sol–gel transitions, induced by changes in the environmental conditions such as temperature, pH, ionic strength, phase separation, wave length of light, crystallinity, etc. Hydrogel is described as smart or intelligent when sharp transition is induced by small change in such conditions. For the shape‐memory hydrogels, reversible change in shape may also be induced by such stimuli. The preparation and applications of the molecularly imprinted polymeric hydrogels (MIPs) are illustrated by a few examples. The use of shape sensitive hydrogels in microfluidic is mentioned. Application of hydrogels for chronobiology and chronotherapy is outlined. The conversion of hydrogels into aerogels and their respective properties is discussed. Copyright © 2009 John Wiley & Sons, Ltd.