bluuebunny/crossref_metadata_2025 huggingface dataset:
Portal vein thrombosis following laparoscopic cholecystectomy complicated by dengue viral infection: a case report
Authors: Dan Dilip , King Kevin , Seetahal Shiva , Naraynsingh Vijay , Hariharan Seetharaman
Published: April 2011

Introduction

Portal vein thrombosis is an uncommon post-operative complication following abdominal surgery. Although therapeutic anticoagulation is recommended, this treatment may be questionable when the patient has an associated bleeding diathesis.

Case presentation

We report a case of a 63-year-old woman of Asian Indian ethnicity who developed portal vein thrombosis following an uneventful laparoscopic cholecystectomy for symptomatic gallstones. Her condition was further complicated by dengue viral infection in the post-operative period, with thrombocytopenia immediately preceding the diagnosis of portal vein thrombosis. The etiological connections between dengue viral infection with thrombocytopenia, laparoscopic cholecystectomy, portal vein thrombosis as well as the treatment dilemmas posed in treating a patient with portal vein thrombosis with a bleeding diathesis are discussed.

Conclusion

When portal vein thrombosis occurs in patients with contraindications to anticoagulation, there is a role for initial conservative management without aggressive anticoagulation therapy and such patients must be approached on an individualized basis.
Regulation of chondrocyte gene expression by osteogenic protein-1
Authors: Chubinskaya Susan , Otten Lori , Soeder Stephan , Borgia Jeffrey A , Aigner Thomas , Rueger David C , Loeser Richard F
Published: April 2011

Introduction

The objective of this study was to investigate which genes are regulated by osteogenic protein-1 (OP-1) in human articular chondrocytes using Affimetrix gene array, in order to understand the role of OP-1 in cartilage homeostasis.

Methods

Chondrocytes enzymatically isolated from 12 normal ankle cartilage samples were cultured in high-density monolayers and either transfected with OP-1 antisense oligonucleotide in the presence of lipofectin or treated with recombinant OP-1 (100 ng/ml) for 48 hours followed by RNA isolation. Gene expression profiles were analyzed by HG-U133A gene chips from Affimetrix. A cut-off was chosen at 1.5-fold difference from controls. Selected gene array results were verified by real-time PCR and by in vitro measures of proteoglycan synthesis and signal transduction.

Results

OP-1 controls cartilage homeostasis on multiple levels including regulation of genes responsible for chondrocyte cytoskeleton (cyclin D, Talin1, and Cyclin M1), matrix production, and other anabolic pathways (transforming growth factor-beta (TGF-β)/ bone morphogenetic protein (BMP), insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF), genes responsible for bone formation, and so on) as well as regulation of cytokines, neuromediators, and various catabolic pathways responsible for matrix degradation and cell death. In many of these cases, OP-1 modulated the expression of not only the ligands, but also their receptors, mediators of downstream signaling, kinases responsible for an activation of the pathways, binding proteins responsible for the inhibition of the pathways, and transcription factors that induce transcriptional responses.

Conclusions

Gene array data strongly suggest a critical role of OP-1 in human cartilage homeostasis. OP-1 regulates numerous metabolic pathways that are not only limited to its well-documented anabolic function, but also to its anti-catabolic activity. An understanding of OP-1 function in cartilage will provide strong justification for the application of OP-1 protein as a therapeutic treatment for cartilage regeneration and repair.
Functional status and quality of life 12 months after discharge from a medical ICU in healthy elderly patients: a prospective observational study
Authors: Sacanella Emilio , Pérez-Castejón Joan Manel , Nicolás Josep Maria , Masanés Ferran , Navarro Marga , Castro Pedro , López-Soto Alfonso
Published: April 2011

Introduction

Long-term outcomes of elderly patients after medical ICU care are little known. The aim of the study was to evaluate functional status and quality of life of elderly patients 12 months after discharge from a medical ICU.

Methods

We prospectively studied 112/230 healthy elderly patients (≥65 years surviving at least 12 months after ICU discharge) with full functional autonomy without cognitive impairment prior to ICU entry. The main diagnoses at admission using the Acute Physiology and Chronic Health Evaluation III (APACHE III) classification diagnosis and length of ICU stay and ICU scores (APACHE II, Sepsis-related Organ Failure Assessment (SOFA) and OMEGA) at admission and discharge were collected. Comprehensive geriatric assessment included the presence of the main geriatric syndromes and the application of Lawton, Barthel, and Charlson Indexes and Informant Questionnaire on Cognitive Decline to evaluate functionality, comorbidity and cognitive status, respectively. The EuroQol-5D assessed quality of life. Data were collected at baseline, during ICU and ward stay and 3, 6 and 12 months after hospital discharge. Paired or unpaired T-tests compared differences between groups (continuous variables), whereas the chi-square and Fisher exact tests were used for comparing dichotomous variables. For variables significant (P ≤ 0.1) on univariate analysis, a forward multiple regression analysis was performed.

Results

Only 48.9% of patients (mean age: 73.4 ± 5.5 years) were alive 12 months after discharge showing a significant decrease in functional autonomy (Lawton and Barthel Indexes) and quality of life (EuroQol-5D) compared to baseline status (P < 0.001, all). Multivariate analysis showed a higher Barthel Index and EQ-5D vas at hospital discharge to be associated factors of full functional recovery (P < 0.01, both). Thus, in patients with a Barthel Index ≥ 60 or EQ-5D vas ≥40 at discharge the hazard ratio for full functional recovery was 4.04 (95% CI: 1.58 to 10.33; P = 0.005) and 6.1 (95% CI: 1.9 to 19.9; P < 0.01), respectively. Geriatric syndromes increased after ICU stay and remained significantly increased during follow-up (P < 0.001).

Conclusions

The survival rate of elderly medical patients 12 months after discharge from the ICU is low (49%), although functional status and quality of life remained similar to baseline in most of the survivors. However, there was a two-fold increase in the prevalence of geriatric syndromes.
Long-Term Survival and Late Deaths After Allogeneic Hematopoietic Cell Transplantation
Authors: Wingard John R. , Majhail Navneet S. , Brazauskas Ruta , Wang Zhiwei , Sobocinski Kathleen A. , Jacobsohn David , Sorror Mohamed L. , Horowitz Mary M. , Bolwell Brian , Rizzo J. Douglas , Socié Gérard
Published: April 2011

Purpose

Allogeneic hematopoietic cell transplantation (HCT) is curative but is associated with life-threatening complications. Most deaths occur within the first 2 years after transplantation. In this report, we examine long-term survival in 2-year survivors in the largest cohort ever studied.

Patients and Methods

Records of 10,632 patients worldwide reported to the Center for International Blood and Marrow Transplant Research who were alive and disease free 2 years after receiving a myeloablative allogeneic HCT before 2004 for acute myelogenous or lymphoblastic leukemia, myelodysplastic syndrome, lymphoma, or severe aplastic anemia were reviewed.

Results

Median follow-up was 9 years, and 3,788 patients had been observed for 10 or more years. The probability of being alive 10 years after HCT was 85%. The chief risk factors for late death included older age and chronic graft-versus-host disease (GVHD). For patients who underwent transplantation for malignancy, relapse was the most common cause of death. The greatest risk factor for late relapse was advanced disease at transplantation. Principal risk factors for nonrelapse deaths were older age and GVHD. When compared with age, sex, and nationality-matched general population, late deaths remained higher than expected for each disease, with the possible exception of lymphoma, although the relative risk generally receded over time.

Conclusion

The prospect for long-term survival is excellent for 2-year survivors of allogeneic HCT. However, life expectancy remains lower than expected. Performance of HCT earlier in the course of disease, control of GVHD, enhancement of immune reconstitution, less toxic regimens, and prevention and early treatment of late complications are needed.
Framing Monsters: Multiple and Mixed Genres, Cognitive Category Theory, andGravity's Rainbow
Authors: Sinding Michael
Published: April 2011

This article argues for a cognitive view of genre. Specifically, a cognitive view of categorization helps clarify how texts can participate in multiple genres—by instantiating several different genres more or less equally well and by mixing several genres. I respond to certain recurring assumptions in recent work on genre about the nature of categories and categorization, elaborating on John Frow's incisive critique of misconceptions of genre but correcting his discussion of cognitive poetics. I draw on concept and category research to sketch the three main contemporary approaches to categorization via prototype, exemplar, and knowledge theories. Against this background, I review the many genres that have been attributed to Gravity's Rainbow, then examine three influential generic framings of this text and what the text can tell us about the nature of categories and how people use them. I conclude by discussing the ways this example is particularly revealing about how prototypes, exemplars, and knowledge interact, how experts use categories to understand and experience the very rich and complex realities of their domains of expertise, and how this new understanding of categorization can help clarify Thomas Pynchon's blending of genres.
Renaissance of Organic Synthesis Using Isocyanides
Authors: Tobisu Mamoru , Chatani Naoto
Published: April 2011

New reactions using old functionality, isocyanides, are described. By using isocyanides in place of carbon monoxide, transformations otherwise difficult to achieve, such as GaCl3-catalyzed [4 + 1] cycloaddition and TfOH-catalyzed insertion into a C–O bond of acetals, are realized. In addition, isocyanides are exploited as a key component in transition-metal-catalyzed C–H bond activation and borylation reactions.
Estimation of total length of humerus from its segments
Authors: Singhal Suruchi , Rao Vani
Published: April 2011

The aim of the present study was to calculate the total length of the humerus from its segments using linear, transverse and sagittal measures. One hundred and fifty dry adult unpaired humeri of both sides and of unknown sex from South India were studied. The humeri were divided into eight segments using salient bony points and muscular markings. The length of each segment was compared with the total length. These were subjected to statistical analysis. A high degree of correlation was found between segment length and total length and hence regression equations were calculated to estimate total length of humerus from each segment. The difference in measurements of the right and left sides was insignificant; hence single equations were calculated for all 150 bones. The length of the humerus and finally the stature of the individual could be calculated fairly accurately with an error of less than 2 cm. The results were compared with similar studies on other Indian populations. Calculation of total length from longer segments is comparable with other Indian populations, but if only shorter segments are available, new equations are needed for each population.
Information Technology and the Medication Use Process
Authors: Felkey Bill G. , Fox Brent I.
Published: April 2011

Information technology should enable pharmacists to better perform their job-related responsibilities, whether those tasks are administrative, operational, clinical, or any combination of the three. The reality is that today's health care environment has become so complex that information technology tools are requisite to what pharmacists do. This column addresses several areas within the medication use process where technology supports pharmacists' activities.
Robin Sequence: From Diagnosis to Development of an Effective Management Plan
Authors: Evans Kelly N. , Sie Kathleen C. , Hopper Richard A. , Glass Robin P. , Hing Anne V. , Cunningham Michael L.
Published: April 2011

The triad of micrognathia, glossoptosis, and resultant airway obstruction is known as Robin sequence (RS). Although RS is a well-recognized clinical entity, there is wide variability in the diagnosis and care of children born with RS. Systematic evaluations of treatments and clinical outcomes for children with RS are lacking despite the advances in clinical care over the past 20 years. We explore the pathogenesis, developmental and genetic models, morphology, and syndromes and malformations associated with RS. Current classification systems for RS do not account for the heterogeneity among infants with RS, and they do not allow for prediction of the optimal management course for an individual child. Although upper airway obstruction for some infants with RS can be treated adequately with positioning, other children may require a tracheostomy. Care must be customized for each patient with RS, and health care providers must understand the anatomy and mechanism of airway obstruction to develop an individualized treatment plan to improve breathing and achieve optimal growth and development. In this article we provide a comprehensive overview of evaluation strategies and therapeutic options for children born with RS. We also propose a conceptual treatment protocol to guide the provider who is caring for a child with RS.
Novelties of treatment in advanced renal-cell cancer
Authors: Maráz Anikó
Published: April 2011

Therapeutic options in advanced renal-cell cancer have expanded through better understanding of molecular patho­logy and development of novel targeted therapeutics. Vascular endothelial growth factor, the key ligand of angioge­nesis, has a major role in the progression of vascularized kidney tumors and this is the target molecule of modern medications. The three types of the mechanism of action of current therapies are: monoclonal antibodies blocking directly vascular endothelial growth factor ligand (bevacizumab), tyrosine-kinase inhibitors blocking vascular endothelial growth factor receptors (sorafenib, sunitinib, pazopanib) and inhibitors of the intracellular mTOR-kinase (temsirolimus, everolimus). Based on randomized studies, sunitinib, pazopanib or interferon-α-bevacizumab combination should be the first-line therapy in patients with good/moderate prognosis, while temsirolimus is recommended in those with poor prognosis. Following an ineffective cytokine therapy sorafenib or pazopanib are the se­cond-line treatment. In case of tyrosine-kinase inhibitor inefficacy, current evidence favors everolimus. Patient outcome can further be improved by the involvement of more modern and effective target products. Orv. Hetil., 2011, 152, 655–662.
Highly-ordered Porous Coordination Polymer Nanofilms Grown by Layer-by-Layer Deposition Technique
Authors: Makiura Rie , Kitagawa Hiroshi
Published: April 2011

The facile bottom-up fabrication of a perfect preferentially-oriented MOF nanofilm, NAFS-1 on a solid surface, which is endowed with highly crystalline order both in the out-of-plane and in-plane orientations to the substrate, as determined by synchrotron X-ray surface crystallography, was achieved by the unique combination of a layer-by-layer growth technique coupled with the Langmuir-Blodgett (LB) method.
Synthesis and Characterization of Indium Oxide Doped Hematite xIn2O3·(1-x)α-Fe2O3 Solid Solution
Authors: Sorescu Monica , Xu Tianhong , Diamandescu Lucian
Published: April 2011

Indium oxide-doped hematite xIn2O3·(1-x)α-Fe2O3 (x = 0.1-0.7) solid solution systems were synthesized using mechanochemical activation. The microstructures, magnetic and thermal properties of the system were dependent on In2O3 molar concentration x and ball milling time. XRD results showed that the completion of In3+ substitution of Fe3+ in hematite lattice occurs after 12 h ball milling for x = 0.1. For x = 0.3, 0.5 and 0.7, the substitutions between In3+ and Fe3+ into hematite and In2O3 lattices occur simultaneously. The lattice parameters of hematite and In2O3 vary as a function of ball milling time. The change in these parameters was due to ions substitution between In3+and Fe3+ and the decrease in grain sizes. Mössbauer spectra of the system with x = 0.3 were fitted with three sextets and two quadrupole-split doublets after milling, representing In3+ substitution of Fe3+ in hematite lattice and Fe3+ substitution of In3+ in two different sites of In2O3 lattice. TGA results showed that the hematite decomposition is enhanced due to the smaller hematite grain size. The crystallization of hematite and In2O3 was suppressed with the drops of enthalpy values due to the stronger solid-solid interactions after ball milling. These caused gradual In3+-Fe3+ substitution in hematite/In2O3 lattices.
Thermal and viscoelastic behaviors of nanotube-reinforced polyethylene composite
Authors: Adhikari Ananta Raj , Chipara Mircea , Lozano Karen
Published: April 2011

The effect of processing (shear) time on the mechanical behavior and thermal stability of multiwalled nanotube reinforced polyethylene was investigated. It was observed that the mechanical property (storage modulus, loss modulus) of the composites is process dependant whereas the thermal stability does not. The increase in mechanical behavior is attributed to a stronger interface between the nanotube and the polymer matrix.
Morphological Investigations of Organic/Inorganic Nanocomposites Fabricated to Achieve Controlled Dispersion at High Loadings
Authors: Duncan Andrew J. , Schoch Andrew B. , Gold Christopher S. , Lenhart Joseph L. , Beyer Frederick L.
Published: April 2011

Realization of property enhancements inherent to the presence of nanoparticles continues to be a challenge for the production of bulk nanocomposite materials with commercially available techniques. This study combines twin-screw compounding with surface modification of SiO2 nanoparticles to enable targeted dispersion in a SEBS block copolymer. Production of these composites with high levels of well-dispersed particulates aims to leverage aggregation for production of hierarchical structure. The aggregation state of the particles as well as the level of order in the block copolymer morphology was determined through USAXS and TEM. Particles coated with ligands miscible with the end-blocks of the BCP (minority component) increased dispersion at all loading levels observed up to 10 vol%. Ligands employed to increase miscibility of the nanoparticle with the mid-block (majority component) resulted in large aggregates for all loadings without disturbance of the BCP morphology.
Self-Assembling Functionalized Amino Acids into Unusual Shapes
Authors: Barone Justin R. , Budhavaram Naresh K. , Harvey Katherine J.
Published: April 2011

Multi-component small molecule systems that are amphiphilic or that can hydrogen bond end-to-end or side-to-side have been shown to self-assemble into a variety of shapes including fibers, rods, sheets, plates, spheres, and tubes. Recently, we have identified a simple route to self-assemble the same shapes from one-component systems. The structures form by attaching ethyl vinyl sulfone (EVS) to amino acids in water at room temperature. Choice of amino acid, amount of EVS substitution, and solvent conditions determine the final shape. Functionalized amino acids spontaneously form structures like fibers, spheres, tubes, and donuts when dried from solution. Here we focus on fibers and tubes.
Synthesis of Thermo-Responsive Fluorinated Star-Shaped Polymers by Living Cationic Polymerization
Authors: Irita Tomomi , Imoto Katsuhiko , Nagai Takabumi , Aoshima Sadahito
Published: April 2011

Well-controlled fluorinated star-shaped polymers with oxyethylene units were designed and synthesized by living cationic polymerization. These fluorinated star-shaped polymers were prepared using successive fluorinated initiators to generate fluorinated, end-functionalized and hydrophilic segments with oxyethylene. Poly(vinyl ether)s with oxyethylene units are known to be thermo-responsive polymers that exhibit a lower critical solution temperature (LCST) in aqueous solutions. These novel fluorine-containing star-shaped polymers with oxyethylene were also thermo-responsive, as expected. In addition, the hetero-fluorinated star-shaped polymers with oxyethylene segments and different fluorine compositions were synthesized with various bifunctional initiators by living cationic polymerization having narrow molecular weight distributions (Mw/Mn=1.23−1.29) and contained very little, if any, presence of the linear homopolymer precursor, as evidenced by GPC. The LCST of this polymer depended on the end group fluorine composition and significant changes in cloud points were observed in water, as confirmed by static light scattering (SLS) measurements. As an example, aqueous solutions the star-shaped polymers without fluorine terminal groups showed no cloud point below up to 60 ºC in aqueous solution. After the fluoro-functionality was incorporated into the terminal groups, the cloud point of the aqueous solutions decreased to almost 20 ºC.
Concomitant Channel Cracking and Interfacial Delamination in Polymer/Oxide Nano Hybrid Permeation Barriers in Flexible Electronics
Authors: Jia Zheng , Tucker Matthew B. , Li Teng
Published: April 2011

Polymer/oxide nano hybrid multilayer permeation barriers are emerging as a promising solution to the stringent barrier requirement of flexible electronics. Yet the mechanical failure of the multilayer permeation barriers could be fatal to their barrier performance. We study two co-evolving failure mechanisms of the multilayer permeation barriers under tension, namely, the cracking of the inorganic oxide layer and the delamination along the oxide-organic interface, using computational modeling. An effective driving force for the oxide layer cracking is determined, which decreases as the oxide-organic interfacial adhesion increases.
Structure and Strength of Silica-PDMS Nanocomposites
Authors: Camenzind Adrian , Schweizer Thomas , Sztucki Michael , Pratsinis Sotiris E.
Published: April 2011

Commercially available SiO2 nanoparticles (Aerosil, Degussa) with varying primary particle diameter, specific surface area (SSA), degree of aggregation and structure (fractal dimension) were compounded into PDMS-based nanocomposites. Thin sections of cured nanocomposites were analyzed with TEM and small and ultra-small angle X-ray scattering (U/SAXS) with respect to nanocomposite structure such as: filler primary particle, aggregate (chemically or sinter-bonded particles) and agglomerate (physically-bonded particles). Tensile tests (Young’s modulus) were used to determine the nanocomposite strength which increased with increasing filler volume fraction (up to 12 vol%) consistent with “bound rubber” theory.
Novel Aster-like ZnO Nanowire Clusters for Nanocomposites
Authors: Ladanov Mikhail , Ram Manoj , Kumar Ashok , Matthews Garrett
Published: April 2011

ZnO nanostructures have attracted a great deal of interest because of their biocompatibility and outstanding optical and piezoelectric properties. Their uses are widely varying, including incorporation in sensors, solar cells, and nanogenerators. Biological systems are yet another area of application of ZnO nanowires. Apart from their electrical and optical properties, ZnO nanostructures can be used for the mechanical reinforcement of existing biomimetic scaffolds such as collagen and/or other biodegradable polymers (poly(lactic acid), polyglycolide, poly(alkyene succinate)s or polyhydroxylalkanoates). In this work, we have demonstrated a cheap and comparatively facile hydrothermal growth method for the bulk production of ZnO nanostructures exhibiting an aster-like geometry. The novel nanostructures of ZnO can be used as reinforced material to biopolymers. The aster shape has presented an increased surface area, providing a means for enhancing the stabilization of the gels and\or polymers. With controllable growth of ZnO nanostructures this method allows the geometry which could be tuned for maximal coupling between the two phases of composite and increased mechanical strength.
Characterisation of Organic Semiconductor Growth using Real-time Electron Spectroscopy
Authors: Evans D. Andrew , Roberts Owain R. , Williams Gruffudd T. , Langstaff David. P.
Published: April 2011

An organic molecular beam deposition system coupled to a soft x-ray excitation source has been developed to monitor the growth of organic semiconductor thin films in-situ and in real-time. Rapid collection of photoelectron spectra has been enabled using a multichannel array detector coupled to a hemispherical analyzer. The organic semiconductor tin phthalocyanine (SnPc) exhibits a Stranski-Krastanov growth mode on a polycrystalline gold substrate where the transition thickness between layered and clustered growth has been determined to be comparable to the thickness of a single molecular layer within which the molecules are standing on edge relative to the substrate plane.
A Study on the Electronic Properties of Nitric Oxide Annealed MOS Structures Processed on 4H-SiC
Authors: Chew Kerlit , Tin Chin-Che , Ahyi Claude , Chong Kim Nie , Liang Meng Suan , Chong Sir Cong , Rusli  , Lew Kim Luong
Published: April 2011

Interface state density profiling of the thermal oxide / n-type 4H-SiC interface which underwent post-oxidation nitric-oxide (NO) annealing showed that an interface state density of approximately 1×1011 cm−2eV−1 could be achieved at around 0.2 eV below the conduction band. It decreased exponentially by two orders to 1×109 cm-2eV-1 at around 0.9 eV from the conduction band. The values are comparable or better than other published work. The low interface state density achieved near the conduction band is important towards improved channel carrier mobility in SiC MOSFETs. A positive flat-band voltage shift of the SiC based MOS capacitor was also observed. The shift reduced under UV illumination. It could be attributed to slow acceptor-like (negatively-charged) traps, which may have contributed to the instabilities observed in drain current and threshold voltage suffered by SiC MOSFETs.
The Development of Anodic Aluminum Oxide Based Micro-channel Plate for Large-area Photo-detector
Authors: Lee Seon Woo , Peng Qing , Mane Anil U. , Elam Jeffrey W. , Byrum Karen , Frisch Henry , Wang Hau
Published: April 2011

Anodized Aluminum Oxide (AAO) based micro-channel plates (MCP) are fabricated in order to develop economical large-area photodetectors. Commercially available glass capillary array has a limitation to reach channel diameter below ~10 microns. However, smaller channel diameter is desired for better spatial and fast timing resolution. AAO based MCP is a good candidate to produce channel diameter less than 10 um by taking advantage of the nano-scale intrinsic pores during etching process. In this study, various channel diameters are fabricated with use of lithographic patterning techniques and wet etching; and characterized with optical, atomic force, and scanning electron microscopies. The channel diameter, channel length and related aspect ratio, as well as the open area are varied in order to maximize the MCP photon amplification.
Titanium Dioxide Nanotubes Decorated with Nanoparticles for Dye Sensitized Solar Cells
Authors: Pan Xuan , Zhao Yong , Chen Changhong , Fan Zhaoyang
Published: April 2011

The titanium dioxide (TiO2) nanoparticle (NP) structure has higher surface area and dye loading value to increase photon absorption while the nanotube (NT) can suppress the random walk phenomena to enhance carrier collection. In this work, hydrothermal method was utilized to infiltrate the TiO2 nanotube array by TiO2 nanoparticles with the aim of combining the advantages of both nanostructures to improve dye sensitized solar cells (DSSCs) efficiency. Structure morphology, device performance, and electrochemical properties were investigated. SEM observation confirmed that around 10 nm TiO2 nanoparticles uniformly covered the NT wall. TiO2 NT samples at three different lengths: 8 μm, 13 μm and 20 μm, decorated with different amount of nanoparticles were studied to optimize the structure for light absorption and electron transport to achieve high solar conversion efficiency. Electrochemical impedance spectroscopy (EIS) was also employed to investigate the cells’ parameters: electron lifetime (τ), diffusion length (Ln) et al, to gain insight on the device performance. The incident photon conversion efficiency (IPCE) was also reported.
Noise Mitigation Techniques for Carbon Nanotube-Based Piezoresistive Sensor Systems
Authors: Cullinan Michael A. , Culpepper Martin L.
Published: April 2011

Carbon nanotube (CNT)-based piezoresistive strain sensors have the potential to outperform traditional silicon-based piezoresistors in MEMS devices due to their high strain sensitivity. However, the resolution of CNT-based piezoresistive sensors is currently limited by excessive 1/f or flicker noise. In this paper we will demonstrate several noise mitigation techniques that can be used to decrease noise in the CNT-based sensor system without reducing the sensor’s strain sensitivity. First, the CNTs were placed in a parallel resistor network to increase the total number of charge carriers in the sensor system. By carefully selecting the types of CNTs used in the sensor system and by correctly designing the system it is possible to reduce the noise in the sensor system without reducing sensitivity. The CNTs were also coated with aluminum oxide to help protect the CNTs from environmental variations. Finally, the CNTs were annealed to improve contact resistance and to remove adsorbates from the CNT sidewall. Overall, using these noise mitigation techniques it is possible to reduce the total noise in the sensor system by almost two orders of magnitude and increase the dynamic range of the sensors by 29 dB.
Nanorods of Dy Modified BiFeO3 for Multifunctional Device Applications
Authors: Mandal M. , Duttagupta S. P. , Palkar V. R.
Published: April 2011

We have developed material (Bi0.7Dy0.3FeO3)(BDFO) which exhibits the multiferroic behavior at room temperature with significant coupling in bulk as well as thin films. If these properties could be fashioned in nano rods, implementation in devices could be certainly more prominent and straight forward. We have therefore used vertically aligned arrays of silicon rods (~5 μm in length and ~ 500 nm in diameter) as base material to direct the growth of BDFO in rod form. BDFO is deposited on the surface of Si rods by using pulsed laser deposition technique. These BDFO/Si rods are then separated from the support, dispersed into propanol and transferred onto SiO2/Si substrates for testing. X-ray diffraction (XRD) results indicate presence of phase pure BDFO layer on Si rods. Saturation observed at room temperature in magnetic and ferroelectric hysteresis loops confirm the coexistence of ferromagnetic and ferroelectric properties. Change in ferroelectric polarization measured on single rod in the presence of applied magnetic field suggests the coupling behavior between two order parameters. Moreover, change in magnetic domain pattern of BDFO rods associated with applied electric field further supports the presence of coupling behavior in both ways. The vertical and lateral displacement occurring in BDFO/Si rods with applied electric field helps to confirm their piezoresponce behavior. BDFO/Si nanorods with multifunctional properties could find variety of novel device applications with flexibility and simplicity in operation. It might include single rod power generation by means of applied stress or magnetic field.
Three-Dimensional Patterning of Micro/Nanoparticle Assembly with a Single Droplet of Suspension
Authors: Choi Sun , Pisano Albert P. , Zohdi Tarek I.
Published: April 2011

We develop a novel patterning technique to create 3D patterns of micro, nanoparticle assembly via evaporative self-assembly based on confinement/release of micro/nano particles assembly based on the coffee-ring effect of evaporating suspension. Based on the presented technique, we demonstrate that the patterns of 3D assembly of various sizes of microparticles (Silica), metal oxide nanoparticles (TiO2, ZnO) and metallic nanoparticles (Ag) can be successfully generated by low-concentrated particle suspension (1.25 wt % ~ 5 wt %) without additional sintering steps and we also show the geometries of the patterns can be finely controlled by adjusting the parameters of the process.
A DFT and HRTEM Study on MoS2/Co: Locating Promoters in Catalytic Nanostructures
Authors: Ramos Manuel , Berhault Gilles , Farias Jose Rurik , Elizalde Jose Trinidad , Ferrer Domingo , Torres Brenda , Chianelli R. R.
Published: April 2011

Locating cobalt promoters on catalytically MoS2 structures is a challenging task to achieve; this is due to the size on those MoS2 nanostructures. Previous reports in the literature indicate that specific locations for Co in MoS2 slabs are (1010)-plane creating either a sulfur-Co or Molybdenum-Co termination edge, due to lower energy required for the permutation Mo, S and Co to occur. We present results obtained from Density Functional Theory study done on the interface between MoS2 and Co9S8 crystal structures; the interface show an interesting thiocubane cluster and it is suspected to be the responsible for Mo-S-Co bonding to exist, along with HDS reaction. In order to understand electronic properties on thiocubane Density of States and Mulliken Population Analysis calculations were implemented using Cambridge Serial Total Energy Package (CASTEP). Results indicate a strong electron donation from Co to Mo through intermediate sulfur atom bonded to both metals while an enhanced metallic character is also found.
Nylon 6 reinforced with acrylic polymer nanoparticles. Thermal properties and nano structure
Authors: Huitron-Rattinger Estefania , Alvarado-Tenorio Bonifacio , Romo-Uribe Angel
Published: April 2011

The correlation of thermal properties and nanostructure of nylon 6 (denoted PA6) reinforced with polymer nanoparticles (denoted PNP, size~8 nm) has been investigated. PNPs are highly crosslinked acrylic-based polymers synthesized by the Rohm and Haas Co. PNPs and those grafted with maleic anhydride (denoted PNP-g-MA) were each one dispersed into a commercial PA 6 matrix by melt extrusion, at a concentration of 3 wt%. Thermal analysis showed that the PNPs increased the thermal stability of PA6 and reduced the melting and crystallization temperatures as well as the enthalpy. Small-angle light scattering showed that the PNPs crystallize into a spherulitic morphology, typical of PA6. Isothermal crystallization studies showed that the PNPs act as nucleating agents, accelerating the rate of crystallization. Wide-angle X-ray scattering showed that the composites crystallize in the α-form, and the PNPs reduced the degree of crystallinity, in agreement with thermal analysis results. The smaller degree of crystallinity was also reflected in the long range spacing, it was also reduced by the presence of the PNPs as measured directly by small-angle X-ray scattering.
Formation of Irregular Al Islands by Room-Temperature Deposition on NiAl(110)
Authors: Jing Dapeng , Han Yong , Ünal Bariş , Evans J. W. , Thiel P. A.
Published: April 2011

STM studies reveal that irregular non-equilibrium two-dimensional Al islands form during deposition of Al on NiAl(110) at 300 K. These structures reflect the multiple adsorption sites and diffusion paths available for Al adatoms on the binary alloy surface, as well as the details of inhibited edge diffusion and detachment-attachment kinetics of Al adatoms for numerous distinct step edge configurations. We attempt to capture these features by multi-site lattice-gas modeling incorporating DFT energetics for adatoms both at adsorption sites and transition states. This formulation enables description and elucidation of the observed island growth shapes.
Superconducting Parent Compound Pr2CuO4 Achieved by Special Post-Reduction
Authors: Yamamoto Hideki , Matsumoto Osamu , Yamagami Keitaro , Naito Michio , Krockenberger Yoshiharu
Published: April 2011

It is commonly believed that the parent compounds of high-Tc cupratres are, universally, charge transfer insulators and triggered by Mott physics. In our experiments using metal-organic decomposition (MOD), however, accumulating evidences show that the parent compounds of “electron-doped” superconductors, RE2-xCexCuO4 [RE = rare earth ion] with x = 0, are not Mott insulators but superconductors [1-5]. They have a Tc of 30 K and crystallize in the Nd2CuO4 (T’) structure. Most likely, the sharp contradiction between our results and commonly achieved data originates from the complicated oxygen chemistry in these materials. The as-synthesized specimens contain a fair amount of impurity interstitial oxygen. Throughout the reduction process it is required to remove exclusively impurity oxygen while preserving regular oxygen site occupied in order to obtain superconductivity. With decreasing x the constraints of the reduction process are getting more tight. In this study, we systematically investigated the post-annealing process using MBE-grown T’-Pr2CuO4 films. The MBE films were reduced ex-situ in a tubular furnace following a specially designed 2-step process, as in the case of MOD films. The films were annealed at Ta = 700 - 850°C in a reducing atmosphere (PO2 = 2 x 10−5 − 2 x 10−3 atm) and finally reduced at a lower temperature Tred = 450 – 700°C under vacuum (< 10−4 Torr). The film properties systematically changed with Ta, PO2, and Tred. The optimized Tred varies from 475°C to 650°C mainly depending on Ta, since the microstructure and grain size of the films are determined by Ta. Optimal superconducting properties are Tc of 26 K, while ρ(300 K) = 250 μΩcm, and RRR ~ 10. We believe the combination of thin-film synthesis and specially designed post-reduction process enabled us to obtain nearly intact CuO2 planes. Samples prepared by above-mentioned method unveiled the intrinsic properties of the parent compounds, which are not triggered by Mott physics. This result also agrees with the recent calculation result indicating the parent compounds with T’ structure are not charge transfer insulators [6-8].
Dynamics of hydrogen in Pr2Fe17H4 and Pr2Fe17H5
Authors: Mamontov Eugene , Udovic Terrence J , Rush John J , Isnard Olivier
Published: April 2011

We describe a study of the dynamics of hydrogen in Pr2Fe17H4, where isolated hexagons formed by the interstitial tetrahedral (t) sites of the metal lattice are populated by mobile hydrogen atoms. An activation energy of 0.10 eV has been determined for a localized jump process involving the hopping of these hydrogen atoms among adjacent vertices of each hexagon, slightly lower than that for hydrogen hopping in Pr2Fe17H5, where each hexagon is occupied by two hydrogen atoms.
Charge transfer of n-type GaN photoelectrolysis in HCl solution for H2 gas generation at a counterelectrode
Authors: Fujii Katsushi , Ono Masato , Ito Takashi , Ohkawa Kazuhiro
Published: April 2011

In order to clarify the charge transfer characteristics for H2 generation, photoelectrochemical properties of n-type GaN in HCl solution were investigated. The flatband potential under illumination and the onset voltages of photocurrent located approximately the same position. From the result, we concluded that the positively charged surface by hole capture is the main reason of the extra voltage requirement for H2 generation. The carrier concentration in n-type GaN also affects the photocurrent.
Thermoelectric Study on Polycrystalline La1−xSrxRuO3
Authors: He Jian , Thompson Daniel , Edwards Brad , Tritt Terry M.
Published: April 2011

The otherorhombic distorted perovskite La1−xSrxRuO3 (0.1<x<0.9) polycrystalline samples have been prepared using conventional solid state chemistry reaction. The phase constituent, compositional homogeneity and micro-morphology were checked by X-ray powder diffraction, Energy Disperse X-ray spectroscopy and scanning electron microscopy before characterized by means of the electrical resistivity, thermal conductivity and thermal power measurements. Particularly, the compositional dependence of Seebeck coefficient of present compound was studied in light of the comparison with the strongly correlated system NaxCoO4 and the relevant model proposed by W. Koshibae. Finally, the potential of using La1−xSrxRuO3 as a practical thermoelectric material has been also discussed.
Transient Harman Measurement of the Cross-plane ZT of InGaAs/InGaAlAs Superlattices with Embedded ErAs Nanoparticles
Authors: Singh Rajeev , Bian Zhixi , Zeng Gehong , Zide Joshua , Christofferson James , Chou Hsu-Feng , Gossard Art , Bowers John , Shakouri Ali
Published: April 2011

The transient Harman technique is used to characterize the cross-plane ZT of InGaAs/InGaAlAs superlattice structures with embedded ErAs nanoparticles in the well layers. ErAs nanoparticles have proven to substantially reduce the thermal conductivity while slightly increasing the electrical conductivity of bulk InGaAs. The InGaAs/InGaAlAs superlattice structure was designed to have a barrier height of approximately 200meV. Although ErAs nanoparticles provide free carriers inside the semiconductor matrix, additional doping with Si increased the Fermi energy to just below the barrier height. The bipolar transient Harman technique was used to measure device ZT of samples with different superlattice thicknesses in order to extract the intrinsic cross-plane ZT of the superlattice by eliminating the effects of device Joule heating and parasitics. High-speed packaging is used to reduce signal ringing due to electrical impedance mismatch and achieve a short time resolution of roughly 100ns in transient Seebeck voltage measurement. The measured intrinsic cross-plane ZT of the superlattice structure is 0.13 at room temperature. This value agrees with calculations based on the Boltzmann transport equation and direct measurements of specific film properties. Theoretical calculations predict cross-plane ZT of the superlattice to be greater than 1 at temperatures greater than 700K.
A Band Structure Phase Diagram Calculation of 2D BiSb Films
Authors: Tang Ming Y. , Dresselhaus Mildred S.
Published: April 2011

Ever since the birth of thermoelectrics, it has been well known that semiconductors (materials with a relative small bandgap) give the best thermoelectric performance. From quantum mechanics, it is also well known that low dimension quantum confinement leads to changes in the band alignment of a material. Thus, a semimetallic material can be made semiconducting by using low dimensionality quantum confinement effects. BiSb alloys have been of particular interest for thermoelectric application in the temperature range of 70K to 100K. In bulk form, BiSb alloys can either be semimetal or semiconductor, depending on the alloy composition. Moreover, semimetallic BiSb alloys can be made semiconducting by using the low dimensionality quantum confinement concept. With these two previous concepts in mind, it is valuable to further explore the dependence of the band alignment for different alloy concentrations and different confinement conditions for BiSb alloys.

Following the study of the effect of the Sb concentration and of the wire diameter on the semimetallic or semiconducting phase of BiSb alloy nanowires, we now examine the corresponding effect of the Sb concentration and the film thickness on the properties of BiSb alloy films. A band structure phase diagram is calculated, giving the details on the dependence of the relative band edge position on the film thickness and the Sb concentration. This phase diagram gives a first hand guideline for choosing the film thickness and the Sb concentration to better improve the thermoelectric performance of BiSb alloy films.
Bi2Te3: Structural Modulations in Epitaxially Grown Superlattices and Bulk Materials
Authors: Peranio Nicola , Eibl Oliver , Nurnus Joachim
Published: April 2011

Multiquantum well structures of Bi2Te3 are predicted to show an enhancement of the thermoelectric figure of merit ZT. Electron-conducting Bi2Te3 thin films and superlattices (SL) with a period of 12 nm were epitaxially grown on BaF2 substrates by molecular beam epitaxy. The microstructure was investigated by transmission electron microscopy. The SL could be imaged with strong contrast yielding a period of 12.0±0.5 nm. The SL is slightly bent with an amplitude of 30 nm and a wave length of 400 nm. Threading dislocations were found with a density of 2·109 cm−2. The SL interfaces are strongly bent close to threading dislocations, undisturbed regions have a maximum lateral size of 500 nm. A structural modulation (nns) with a wave length of 10 nm was found in Bi2Te3 thin films, superlattices and bulk materials. The structural modulation is found to be of general character for Bi2Te3 materials and is superimposed to the average structure. It was analysed in detail by stereomicroscopy in bulk material yielding a pure structural modulation with a displacement vector parallel to [5,-5,1] and a wave vector parallel to (1,0,10). The investigations showed the presence of none, one or two (nns). The number of (nns) and thereby the thermoelectric properties might be controlled by the growth parameters. Phonons should be scattered on the sinusoidal strain field of the (nns) yielding (i) a significantly decreased thermal conductivity, (ii) a reduced dimensionality and (iii) anisotropic transport coefficients in the basal plane.
Phase Segregation and Thermoelectric Properties of AgPbmSbTem+2m=2,4,6, and 8
Authors: Sootsman Joseph , Pcionek Robert , Kong Huijun , Uher Ctirad , Kanatzidis Mercouri G
Published: April 2011

The preparation and characterization of the AgPbmSbTem+2 family of compounds with m=2, 4, 6, and 8 is reported. Phase segregation was observed in all of these materials. The lattice thermal conductivity of these samples is low (<1.1 W/m-K). Powder x-ray diffraction, thermal analysis, and electron microscope investigations of these systems show that ideal solid solutions are not formed. The transport properties of these composite materials are presented and suggest that they could have promising thermoelectric properties when optimized.
The Dynamics of the Guests in Filled Germanium Clathrates
Authors: Hermann Raphael P. , Grandjean Fernande , Keppens Veerle , Schweika Werner , Nolas George S. , Mandrus David G. , Sales Brian C. , Christen Hans M. , Bonville Pierre , Long Gary J.
Published: April 2011

In the filled gallium-germanium clathrates, R8Ga16Ge30, where R is Ba, Sr, or Eu, the guests are located in two large cages and are weakly bound to the crystalline clathrate framework. The caged guests exhibit a localized “rattling” vibrational mode that provides an efficient mechanism for reducing the thermal conductivity. Inelastic neutron scattering and nuclear inelastic scattering measurements have yielded the phonon density of states in R8Ga16Ge30; the line width of the localized vibrational modes is found to be an important parameter in determining the lattice thermal conductivity. Neutron diffraction studies on R8Ga16Ge30 have shown that the guests in the larger cage are located off-center, and it was proposed that their jumping about the four off-center locations is responsible for the observed glass-like thermal conductivity at temperatures below 10 K. The detection of such slow guest motion is challenging because the typical time and energy scales involved are ca. 4 ns and 1 µeV, respectively. We have studied the slow europium tunneling dynamics in Eu4Sr4Ga16Ge30 by both Mössbauer and microwave absorption spectroscopy.