bluuebunny/crossref_metadata_2025 huggingface dataset:
G‐CSF rescues tumor growth and neo‐angiogenesis during liver metastasis under host angiopoietin‐2 deficiency
Authors: Im Jae Hong , Tapmeier Thomas , Balathasan Lukxmi , Gal Annamaria , Yameen Sabira , Hill Sally , Smart Sean , Noterdaeme Olivier , Kelly Matthew , Brady Michael , Fu Weili , Kruse Karoline , Bernhard Eric J. , Augustin Hellmut G. , Muschel Ruth J.
Published: June 2012

Suppression of neo‐angiogenesis is a clinically used anti‐tumor strategy with new targets such as angiopoietin‐2 (Ang2) being proposed. However, the functions of Ang2 in vascular remodeling, inflammation and tumor growth are not consistent. We examined effect of depletion of host Ang2 on liver colony formation using Ang2 deficient (Ang2−/−) mice. Surprisingly, the metastatic colonies formed in Ang2−/− mice were larger than those in the wild type. These colonies had greater vascular density with more pericyte coverage than the vessels in liver colonies in the wild type. Liver VEGF concentration in both genotypes was equivalent, and thus, the differences appeared VEGF independent. However, after colony formation, the serum concentration of granulocyte‐colony stimulating factor (G‐CSF) and CXCL1 in Ang2−/− mice was 12 and 6 times greater than after colony formation in wild type. Increase of these two cytokines was associated with two times greater numbers of neutrophils recruited to the liver. Two times more Tie2+/CD11b+/CD31− cells were present in the tumors in Ang2−/− than in the wild type livers. These results suggest that the depletion of host Ang2 induced compensatory VEGF‐independent angiogenic mechanisms and thus enhanced liver metastatic colony growth and colony vascularity. They further indicate organotypic differences in response to tumor metastasis. In contrast, Ang2 deficiency inhibited tumor growth during metastatic colony formation in the lung, consistent with the reports of decreased pulmonary seeding of tumor cells after pharmacological inhibition of Ang2. Further studies are thus required to assess the effects of pharmacological Ang2 blockade for cancer patients particularly in the liver.
Description of an Intensive Dialectical Behavior Therapy Program for Multidiagnostic Clients With Eating Disorders
Authors: Federici Anita , Wisniewski Lucene , Ben‐Porath Denise
Published: June 2012

The authors describe an intensive outpatient dialectical behavior therapy (DBT) program for multidiagnostic clients with eating disorders who had not responded adequately to standard, empirically supported treatments for eating disorders. The program integrates DBT with empirically supported cognitive behavior therapy approaches that are well established for the treatment of eating disorders. Attention is given to inclusion and exclusion criteria, how the program differs from standard treatments for eating disorders, and the application of specific DBT treatment components for multidiagnostic clients with eating disorders.
Nanofiber diameter‐dependent MAPK activity in osteoblasts
Authors: Jaiswal Devina , Brown Justin L.
Published: June 2012

The major challenge for bone tissue engineering lies in the fabrication of scaffolds that can mimic the extracellular matrix and promote osteogenesis. Electrospun fibers are being widely researched for this application due to high porosity, interconnectivity, and mechanical strength of the fibrous scaffolds. Electrospun poly methyl methacrylate (PMMA, 2.416 ± 0.100 μm) fibers were fabricated and etched using a 60% propylene glycol methyl ether acetate (PGMEA)/limonene (vol/vol) solution to obtain fiber diameters ranging from 2.5 to 0.5 μm in a time‐dependent manner. The morphology of the fibrous scaffolds was evaluated using scanning electron microscopy and cellular compatibility with etchant‐treated scaffold was assessed using immunoflurescence. Mitogen‐activated protein kinases (MAPK) activation in response to different fiber diameter was evaluated with western blot as well as quantitative in‐cell western. We report that electrospun micro‐fibers can be etched to 0.552 ± 0.047 μm diameter without producing beads. Osteoblasts adhered to the fibers and a change in fiber diameter played a major role in modulating the activation of extracellular signal‐regulated kinase (ERK) and p38 kinases with 0.882 ± 0.091 μm diameter fibers producing an inverse effect on ERK and p38 phosphorylation. These results indicate that nanofibers produced by wet etching can be effectively utilized to produce diameters that can differentially modulate MAPK activation patterns. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2921–2928, 2012.
Three‐dimensional porous bioscaffolds for bone tissue regeneration: Fabrication via adaptive foam reticulation and freeze casting techniques, characterization, and cell study
Authors: Mallick Kajal K. , Winnett James , van Grunsven William , Lapworth James , Reilly Gwendolen C.
Published: June 2012

Highly interconnected and 3D porous bioactive hydroxyapatite (HAP) and Bioglass scaffolds have been fabricated by an adaptive version of camphene based foam reticulation (ARM) and camphene freeze casting (CFC) methods. Controlled sublimation of camphene during freeze casting at −78°C produced process optimized bioscaffolds with open, uniform, and interconnected porous structures. HAP and Bioglass scaffolds with desired porosity, pore size, and microtopography were successfully fabricated using polyurethane foam templates of appropriate structures. Macropores of 50–1100 μm with microporosity of 1–10 μm, known to facilitate cell adhesion and proliferation, were obtained. Compressive yield strength of 0.8 MPa close to the upper range of cancellous bone was achieved. The mean compressive strength of HAP scaffolds compared favorably with the theoretical model of porosity variation with strength and was higher than reported values. The nature of pore development, morphology, porosity, crystal structure, chemical composition, and thermal behavior were characterized using scanning electron and optical microscopy, X‐ray diffraction, thermal analysis, and mercury porosimetry. These scaffolds are suited for nonstructural graft and were not cytotoxic in vitro when osteoblast‐like MG63 cells were cultured with the HAP constructs. The cells attached indicated by cell metabolic activity by resazurin assay and spread well when cultured on the surface of the materials. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2948–2959, 2012.
Biocompatibility of PDGF‐simvastatin double‐walled PLGA (PDLLA) microspheres for dentoalveolar regeneration: A preliminary study
Authors: Chang Po‐Chun , Chung Min‐Chun , Lei Chenlu , Chong Li Yen , Wang Chi‐Hwa
Published: June 2012

Proper coordination of local signal to harmonize mitogenesis and osteogenic differentiation is one of the prerequisites to optimize dentoalveolar regeneration. In the study, we purpose to fabricate controlled‐release microspheres encapsulating platelet‐derived growth factor (PDGF) and simvastatin by coaxial electrohydrodynamic atomization. The microspheres demonstrated a distinct core and shell structure encapsulating PDGF and simvastatin respectively, and the encapsulation efficiency was 82.45–92.16% in‐core and 51.37–71.34% in‐shell. Sequential release of PDGF and simvastatin was seen in simvastatin‐in‐core and PDGF‐in‐shell (SP) design, and simultaneous release was achieved in PDGF‐in‐core and simvastatin‐in‐shell (PS) design. All microspheres demonstrated acceptable biocompatibility in vivo, with increased proliferation, reduced apoptosis, and reduced inflammation while PDGF or simvastatin was encapsulated. The PS design significantly reduced apoptosis than control, whereby significant and persistent enhanced proliferation was noted in SP group. The thickness of fibrotic capsules surrounding microspheres significantly reduced in both SP and PS group at day 14. The finding demonstrates that synergism of PDGF and simvastatin favored biocompatibility. Further investigations will aim on confirming the regenerative effect of SP and PS microspheres in a more clinically relevant model. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2970–2978, 2012.
Fabrication and characterization of gelatin‐based biocompatible porous composite scaffold for bone tissue engineering
Authors: Khan M. Nuruzzaman , Islam Jahid M. M. , Khan Mubarak A.
Published: June 2012

In this study, composite scaffolds were prepared with polyethylene oxide (PEO)‐linked gelatin and tricalcium phosphate (TCP). Chitosan, a positively charged polysaccharide, was introduced into the scaffolds to improve the properties of the artificial bone matrix. The chemical and thermal properties of composite scaffolds were investigated by Fourier transform infrared spectroscopy, thermogravimetric analyzer, differential thermal analyzer. In vitro cytotoxicity of the composite scaffold was also evaluated and the sample showed no cytotoxic effect. The morphology was studied by SEM and light microscopy. It was observed that the prepared scaffold had an open interconnected porous structure with pore size of 230–354 μm, which is suitable for osteoblast cell proliferation. The mechanical properties were assessed and it was found that the composite had compressive modulus of 1200 MPa with a strength of 5.2 MPa and bending modulus of 250 MPa having strength of 12.3 MPa. The porosity and apparent density were calculated and it was found that the incorporation of TCP can reduce the porosity and water absorption. It was revealed from the study that the composite had a 3D porous microstructure and TCP particles were dispersed evenly among the crosslinked gelatin/chitosan scaffold. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3020–3028, 2012.
Identification of phototransformation products of sildenafil (Viagra) and its N‐demethylated human metabolite under simulated sunlight
Authors: Eichhorn Peter , Pérez Sandra , Aceña Jaume , Gardinali Piero , Abad José Luis , Barceló Damià
Published: June 2012

Recent publications on pharmaceutical monitoring are increasingly covering the field of illicit drugs and lately the forensic evaluation of designing illegal analogs of lifestyle drugs like the phosphodiesterase type 5 (PDE‐5) inhibitors Viagra (sildenafil), Levitra (vardenafil) and Cialis (tadalafil). Recently, the presence of all three erectile dysfunction treatment drugs has been reported in wastewaters at very low concentrations. In the environment, contaminants undergo various physical or chemical processes classified into abiotic (photolysis, hydrolysis) and biotic (biodegradation) reactions. Thus, changes in the chemical structure lead to the formation of new transformation products, which may persist in the environment or be further degraded. This study describes the photolysis of sildenafil (SDF) and its human metabolite N‐demethylsildenafil (DM‐SDF) under simulated solar radiation (Xenon lamp). Following chromatographic separation of the irradiated samples, eight photoproducts in the SDF samples and six photoproducts for DM‐SDF were detected and characterized. The combination of ultra performance liquid chromatography‐electrospray ionization‐quadrupole time‐of‐flight‐mass spectrometry (UPLC‐ESI‐QToF‐MS), liquid chromatography‐atmospheric pressure chemical ionization‐triple quadrupole mass spectrometry (LC‐APCI‐QqQ‐MS) and hydrogen/deuterium‐exchange experiments allowed to propose plausible chemical structures for the photoproducts, taking into account the characteristic fragmentation patterns and the accurate mass measurements. These mass spectral data provided sound evidence for the susceptibility of the piperazine ring toward photodegradation. A gradual breakdown of this heterocyclic structure gave rise to a series of products, which in part were identical for SDF and DM‐SDF. The sulfonic acid, as the formal product of sulfonamide hydrolysis, was identified as key intermediate in the photolysis pathway. In both drug/metabolite molecules, phototransformation processes taking place beyond the sulfonamide group were deemed to be of minor relevance. Copyright © 2012 John Wiley & Sons, Ltd.
Changes in the stress in the femoral head neck junction after osteochondroplasty for hip impingement: A finite element study
Authors: Alonso‐Rasgado Teresa , Jimenez‐Cruz David , Bailey Colin G. , Mandal Parthasarathi , Board Tim
Published: June 2012

The surgical treatment of femoroacetabular impingement (FAI) often involves femoral osteochondroplasty. One risk of this procedure is fracture of the femoral neck. We developed a finite element (FE) model to investigate the relationship between depth of resection and femoral neck stress. CT data were used to obtain the geometry of a typical cam‐type hip, and a 3D FE model was constructed to predict stress in the head–neck after resection surgery. The model accounted for the forces acting on the head and abductor muscular forces. Bone resection was performed virtually to incremental resection depths. The stresses were calculated for five resection depths and for five different activities (i) standing on one leg (static case); (ii) two‐to‐one‐to‐two leg standing; (iii) normal walking; (iv) walking down stairs; and (v) a knee bend. In general, both the average Von Mises stresses and the area of bone that yielded significantly increased at a resection depth of ≥10 mm. The knee bend and walking down stairs demonstrated the highest stresses. The FE model predicts that fracture is likely to occur in the resection area first following removal of a third (10 mm) or more of the diameter of the femoral neck. We suggest that when surgeons perform osteochondroplasty for hip impingement, the depth of resection should be limited to 10 mm. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1999–2006, 2012
Trimethylamine N‐oxide as a media supplement for cartilage tissue engineering
Authors: O'Connell Grace D. , Fong Jason V. , Dunleavy Neil , Joffe Avrum , Ateshian Gerard A. , Hung Clark T.
Published: June 2012

Supplements added to the culture media (e.g., growth factors and dexamethasone) have been successful in improving mechanical and biochemical properties of engineered cartilage towards native values. Trimethylamine N‐oxide (TMAO), a natural osmolyte found in shark cartilage, is thought to induce protein folding, and counteracts the destabilizing effect of the high concentrations of urea stored by sharks. The objective of this study was to investigate the use of TMAO as a media supplement for promoting growth of functional engineered cartilage in culture. In the first study, TMAO was added to the culture media for the first 14 days in culture and concentrations of 0–200 mM were evaluated. In the second study, TMAO was supplemented to the culture media following chondroitinase ABC digestion, which has been previously shown to mediate an increased collagen content in engineered cartilage. A dose‐dependent response was observed with improved mechanical and biochemical properties for engineered constructs cultured with TMAO at concentrations of 5–100 mM. The Young's modulus of digested constructs cultured in TMAO was 2× greater than digested constructs cultured in the control medium and recovered to undigested control levels by day 42. In conclusion, these initial studies with TMAO as a media supplement show promise for improving the compressive mechanical properties, increasing extracellular matrix production, and increasing the recovery time following chABC digestion. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1898–1905, 2012
Depth‐Dependent Indentation Microhardness Studies of Different Polymer Nanocomposites
Authors: Bhandari Netra L. , Lach Ralf , Grellmann Wolfgang , Adhikari Rameshwar
Published: June 2012

Continuous depth sensing indentation microhardness measurements were performed to investigate the effect of filler content and dimensionality on the mechanical behaviour of different polymer nanocomposites. In 1D filler reinforced nanocomposites (such as PP/MWCNT system), both the hardness and the indentation modulus were found to appreciably increase up to a filler weight fraction of 1.6 wt.‐%. Further addition of the filler changed the properties only insignificantly. In the nanocomposites with 2D filler (such as in PA6/LS) both the hardness and the indentation modulus increase notably with the addition of the filler and showed intense plasticity. In the investigated systems and composition range, the 3D filler (such as PP/OS2) showed no reinforcing effect at all. In was concluded that the 1D and 2D nanofillers play much more effective reinforcing role to improve the mechanical properties than the 3D fillers.
Transition Metal Salt Doping on Polypyrrole/MWCNT Composites for Supercapacitor Applications
Authors: Karthikeyan G. , Das C. K.
Published: June 2012

Polypyrrole doped by Zn2+ ions was synthesized as nanocomposites with MWCNT by in‐situ oxidative polymerization and investigated as electrode material for supercapacitors. The uniform coating of polypyrrole on MWCNT was characterized by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). The effect of Zn2+ ions were characterized by Fourier transform infrared (FTIR) spectroscopy. The electrochemical performances were investigated by cyclic voltammetry (CV), constant current charging/discharging cyclic test (CC) and electrochemical impedance spectroscopy (EIS) using a three‐electrode system. The doped polypyrrole composites show higher specific capacitance and better cyclic stability.
Influence of Crystallization Conditions on Relaxation Properties of Polymer Near‐Surface Layers
Authors: Lebedev D. V. , Ivankova E. M. , Nashchekin A. V. , Marikhin V. A. , Myasnikova L. P. , Radovanova E. I.
Published: June 2012

Relaxation properties of polymer near‐surface layers were investigated with the help of thermoluminescent method using Nanoluminograph (PlasmaChem GMbH, Germany). The gel‐ and melt‐crystallized films from PE of different molecular weight were studied. The light sum of thermoluminescence in the temperature range of various relaxation transitions was compared. It is found that it is primarily controlled by the type of morphology forming during crystallization and the arrangement of the structural units on a surface. The glass transition temperature in near‐surface layers appeared to be lower that that in the bulk. Bulk glass transition temperature was determined by radiothermoluminescence, DMA and DSC techniques.
Synthesis and Electrochemical Characterization of Modified Graphene/Polypyrrole Nanocomposites
Authors: Sahoo Sumanta , Nayak G. C. , Das Chapal Kumar
Published: June 2012

Nanocomposites based on both modified/unmodified graphene and polypyrrole, were investigated as electrode materials for supercapacitor application. All the nanocomposites were prepared by in‐situ oxidative polymerization method using ammonium persulfate as oxidant. The amine functionalization of Graphene was confirmed by FTIR and X‐ray Photo Electron Spectroscopy (XPS). Field Emission Scanning Electron Microscopy (FESEM) and High Resolution Transmission Electron Microscopy (HRTEM) analysis were performed to study the morphology of the nanocomposites. The maximum capacitance value was found as 240 F/g for unmodified graphene based composite. Though the capacitance value was found to be lower for modified graphene based composite, the cyclic stability was found to be higher as compared to unmodified graphene/polypyrrole nanocomposite.
Activated Rubber Crumb in Waterborn Surface Coating
Authors: Suma K. K. , Jacob Sinto , Joseph Rani
Published: June 2012

This study investigates the properties of a matt finishing paint formulated using Vinyl acetate (VAc) ‐ Butyl acrylate (BuA) copolymer latex (water based resin system) and activated rubber crumb (matting agent). Vinyl acetate ‐ Butyl acrylate copolymer prepared by semicontinuous emulsion polymerization. The copolymer emulsion mixed with dispersion of rubber crumb to make the surface coating. Presence of rubber crumb may actively resist the attack of chemicals and climate conditions.
Weight variation before and after surgery in Parkinson's disease: A noradrenergic modulation?
Authors: Guimarães Joana , Moura Eduardo , Vieira‐Coelho Maria Augusta , Garrett Carolina
Published: June 2012

Changes in the nutritional profile of patients with Parkinson's disease have been reported before and after deep brain stimulation surgery. The major determinants of the weight variation in Parkinson's disease are not yet understood, and the mechanism seems complex. Based on the influence of the sympathetic nervous system in metabolic syndrome obesity, the intent of the present review is to consider the role of noradrenergic modulation on weight variations in Parkinson's disease. In this review the authors raise the following hypothesis: weight variation in Parkinson's disease before and after deep brain stimulation of the subthalamic nucleus could be influenced by noradrenergic interaction between the locus coeruleus, subthalamic nucleus, and hypothalamic nucleus. © 2012 Movement Disorder Society
Qualitative analysis of the SICR epidemic model with impulsive vaccinations
Authors: Qiao Meihong , Liu Anping , Foryś Urszula
Published: June 2012

Control of epidemic infections is a very urgent issue today. To develop an appropriate strategy for vaccinations and effectively prevent the disease from arising and spreading, we proposed a modified Susceptible‐Infected‐Removed model with impulsive vaccinations. For the model without vaccinations, we proved global stability of one of the steady states depending on the basic reproduction number R0. As typically in the epidemic models, the threshold value of R0 is 1. If R0 is greater than 1, then the positive steady state called endemic equilibrium exists and is globally stable, whereas for smaller values of R0, it does not exist, and the semi‐trivial steady state called disease‐free equilibrium is globally stable. Using impulsive differential equation comparison theorem, we derived sufficient conditions under which the infectious disease described by the considered model disappears ultimately. The analytical results are illustrated by numerical simulations for Hepatitis B virus infection that confirm the theoretical possibility of the infection elimination because of the proper vaccinations policy. Copyright © 2012 John Wiley & Sons, Ltd.
Bayesian multipoint velocity encoding for concurrent flow and turbulence mapping
Authors: Binter Christian , Knobloch Verena , Manka Robert , Sigfridsson Andreas , Kozerke Sebastian
Published: June 2012

An approach to efficiently measure three‐dimensional velocity vector fields and turbulent kinetic energy of blood flow is presented. Multipoint phase‐contrast imaging is used in combination with Bayesian analysis to map both mean and fluctuating velocities over a large dynamic range and for practically relevant signal‐to‐noise ratios. It is demonstrated that the approach permits significant spatiotemporal undersampling to allow for clinically acceptable scan times. Using numerical simulations and in vitro measurements in aortic valve phantoms, it is shown that for given scan time, Bayesian multipoint velocity encoding provides consistently lower errors of velocity and turbulent kinetic energy over a larger dynamic range relative to previous methods. In vitro, significant differences in both peak velocity and turbulent kinetic energy between the aortic CoreValve (150 cm/s, 293 J/m3) and the St. Jude Medical mechanical valve (120 cm/s, 149 J/m3) were found. Comparison of peak turbulent kinetic energy measured in a patient with aortic stenosis (950 J/m3) and in a patient with an implanted aortic CoreValve (540 J/m3) revealed considerable differences relative to the values detected in healthy subjects (149 ± 12 J/m3) indicating the potential of the method to provide a comprehensive hemodynamic assessment of valve performance in vivo. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
The role of technology in gifted students' motivation
Authors: Housand Brian C. , Housand Angela M.
Published: June 2012

Although technology by itself may not be motivating, a relationship seems to exist between the opportunities that technology presents and motivation for gifted students. When technology use aligns with authentic or “real‐world” applications, motivation can be enhanced. This article explores the overlap between factors that have historically been shown to increase motivation and the unique affordances of technology tools to meet the needs of gifted and talented students. Some examples of this overlap include skills related to control and autonomy (e.g., time management, project management, and decision making about choices provided), challenge (e.g., perseverance and patience through hard work, proposing a project and following it through to completion), collaboration and cooperation (e.g., teamwork, people skills, social skills, anger management, and communication with students at other schools), curiosity (e.g., finding resources online, finding the work interesting, and learning new things), and recognition (e.g., the opportunity to communicate beyond the school walls, a “real” product). © 2012 Wiley Periodicals, Inc.
Proteomic characterization of the abdominal ganglion of Aplysia californica—A protein resource for neuroscience
Authors: Birner‐Gruenberger Ruth , Darnhofer Barbara , Chen Wei‐Qiang , Monje Francisco J. , Lubec Gert
Published: June 2012

Aplysia californica (AC) is a widely used model for testing learning and memory. Although ESTs have been generated, proteomics studies on AC proteins are limited. Studies at the protein level, however, are mandatory, not only due to the fact that studies at the nucleic acid level are not allowing conclusions about PTMs. A gel‐based proteomics method was therefore applied to carry out protein profiling in abdominal ganglia from AC. Abdominal ganglia were extirpated, proteins extracted and run on 2DE with subsequent in‐gel digestion with trypsin, chymotrypsin, and partially by subtilisin. Peptides were identified using a nano‐LC‐ESI‐LTQ‐FT‐mass spectrometer. MS/MS data were analyzed by searching the NCBI nonredundant public AC EST database and the NCBI nonredundant public AC protein database. A total of 477 different proteins represented by 363 protein spots were detected and were assigned to different protein pathways as for instance signaling (receptors, protein kinases, and phosphatases), metabolism, protein synthesis, handling and degradation, cytoskeleton and structural, oxido‐redox, heat shock and chaperone, hypothetical, predicted and unnamed proteins. The generation of a protein map of soluble proteins shows the existence of so far hypothetical and predicted proteins and is allowing and challenging further work at the protein level, in particular in the field of neuroscience.
Epigenetic modifications of the neuroproteome
Authors: Brunner Andrea M. , Tweedie‐Cullen Ry Y. , Mansuy Isabelle M.
Published: June 2012

In the central nervous system, epigenetic processes are involved in a multitude of brain functions ranging from the development and differentiation of the nervous system through to higher‐order cognitive processes such as learning and memory. This review summarises the current state of the art for the proteomic analysis of the epigenetic regulation of gene expression, in particular the PTM of histones, in the brain and cellular model systems. It describes the MS technologies that have helped the identification and analysis of histones, histone variants and PTMs in the brain. Strategies for the isolation of histones that allow the qualitative analysis of PTMs and their combinatorial patterns are introduced, methods for the relative and absolute quantification of histone PTMs are described, and future challenges are discussed.
Optical probes of chain packing structure and exciton dynamics in polythiophene films, composites, and nanostructures
Authors: Barnes Michael D. , Baghar Mina
Published: June 2012

This mini‐review on the photophysics of poly‐alkyl thiophenes (e.g., P3HT) and its blends with electron‐acceptor moeties such as fullerenes (e.g., PCBM) and carbon nanotubes focuses on highlights of recent literature on spectroscopic probes of exciton formation, diffusion, charge‐separation, and transport in these materials. The literature in this area is vast: more than 3000 papers have been published in on P3HT (and related materials) and applications to organic solar energy harvesting devices over the last 20 years. Thus, no single review can capture the breadth and depth of this research. Here, we attempt to highlight some of the exciting new research efforts aimed at understanding photophysical processes in organic photovoltaic materials. This mini‐review is organized as follows: First, a summary of the theoretical framework commonly used to describe fundamental physical processes of charge generation in organic (polymeric) semiconductor materials is presented. We then discuss recent exciting results on ultrafast spectroscopic probes of exciton dynamics in these materials. Finally, we present highlights of new research on polymer nanostructures (nanoparticles and nanofibers) and their exciting applications to organic photovoltaics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Titanium oxide nanospheres: preparation, characterization, and wide‐spectral absorption
Authors: Wu Zhan , Zhang Zhi‐Kun , Guo Deng‐Zhu , Xing Ying‐Jie , Zhang Geng‐Min
Published: June 2012

Titanium oxide (TiO2) nanospheres were synthesized by using cathodic‐plasma electrolysis method at low voltage of 70 V. The morphological, componential, and structural characterizations of the nanospheres were carried out in detail by using scanning electron microscope (SEM), transmission electron microscope (TEM), X‐ray photoelectron spectroscopy (XPS), and X‐ray diffraction (XRD). It is found the nanospheres mostly have diameters in the range of 20–200 nm, and are in anatase, rutile, and oxygen‐deficient phases. The nanospheres exhibit excellent optical absorption covering the wavelength range from 240 to 2600 nm. It is also found that the low voltage during plasma electrolysis could result in more anatase phases of TiO2. The mechanisms responsible for the nanosphere formation and the wide spectral absorption were also discussed.
Net spin and polarization components of the spin density for the single determinant in the basis of paired orbitals
Authors: Ruzankin Sergey Ph. , Lyskov Igor , Zilberberg Igor L.
Published: June 2012

A decomposition of the spin density into the net spin density and polarization density for the unrestricted Kohn–Sham (KS) determinant in the basis of Löwdin–Amos–Hall paired orbitals (PO) is derived. In PO basis set, the net spin part of spin density is only determined by the manifold of occupied α‐spin orbitals which do not overlap with occupied β‐spin orbitals. In its turn, the polarization part is associated with the pairs of overlapping α and β orbitals. The decreased overlap in these pairs corresponds to the increased degree of spin polarization. As an example of the developed spin density decomposition, the complex of FeO with nitrobenzene (taken in the state with spin projection of Sz = 2) is considered for the B3LYP solution revealing substantial spin contamination for the KS determinant. The spin density decomposition predicts for this complex appreciable polarization density over the whole complex while the net spin density remains counter intuitive almost intact at FeO center. This result changes presumed mechanism of metal‐to‐ligand transfer of unpaired electrons from paramagnetic center to diamagnetic ligand having a high electron affinity. © 2012 Wiley Periodicals, Inc.
O (3P) + CH3SH reactions: Structures, energetics, and kinetics
Authors: Cardoso Daniely Verônica Viana , de Araújo Ferrão Luiz Fernando , Spada Rene Felipe Keidel , Roberto‐Neto Orlando , Machado Francisco Bolivar Correto
Published: June 2012

The structures, barrier heights, reaction enthalpies, and thermal rate constants of four reaction paths involving hydrogen abstraction and addition processes between O and CH3SH were computed using the Møller–Plesset perturbation theory at the second order level (MP2) and BB1K methods with the aug‐cc‐pV(T+d)Z basis set. A more accurate evaluation of the energetic of these reaction systems are performed by extrapolating the single point CCSD(T) energies to the complete basis set (CBS) limit approach using the BB1K and MP2/aug‐cc‐pV(T+d)Z geometries. The best estimates of the adiabatic barrier heights, determined using the CCSD(T)/CBS//(BB1K or MP2)/aug‐cc‐pV(T+d)Z method, are between 0.5 and 1.0 kcal mol−1 (R1, CH3S + OH), 5.3 and 5.5 kcal mol−1 (R2, CH2SH + OH), 1.3 and 2.3 kcal mol−1 (R3, CH3 + HSO), and 1.6 and 2.9 kcal mol−1 (R4, CH3SO + H). The thermal rate constants calculated using the dual‐level direct dynamics by variational transition state theory with interpolated single‐point energy corrections are in good agreement with experimental results. The calculated branching ratios at 300 K are 0.91:0.01:0.05:0.03 for the reactions paths R1–R4, respectively, which indicate that hydrogen abstraction from the SH group is the main reaction path. © 2012 Wiley Periodicals, Inc.
HAXPES of protected ITO surfaces at the buried P3HT/ITO interface
Authors: Brumbach Michael T. , Woicik Joseph C.
Published: June 2012

The characterization of buried interfaces is difficult and often has to be performed by a post‐processing method where the interface is exposed. Hard energy X‐ray photoelectron spectroscopy offers the ability to tune the X‐ray energy and thereby change the information depth. In this work, an inorganic/organic interface was evaluated, namely the poly(3‐hexylthiophene) (P3HT) interface with indium tin oxide (ITO), with relevance to organic photovoltaic devices. P3HT/ITO buried interfaces were examined using three X‐ray energies where the ITO surface was prepared under different pretreatment conditions. The P3HT film protected the ITO surface from adventitious adsorbents and allowed for sensitivity to the buried ITO surface. Robust peak fitting parameters were obtained to model the O 1 s and In 3d lineshapes. The deconvolution of these lineshapes allowed for the clear identification of a surface layer on the ITO which is oxidized to a greater extent than the underlying bulk ITO. The surface oxide layer, composed of indium oxide and indium hydroxide, is deficient of oxygen vacancies and would therefore be expected to act as an insulating barrier on the ITO surface. Peak fitting conditions allowed for an estimation of the relative thicknesses of this insulating layer. Copyright © 2012 John Wiley & Sons, Ltd.