bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen Nonstoichiometry of Various Functional Layered Oxides
Authors: Shimoyama Jun-ichi , Yokota Yuui , Shiraki Masahiro , Sugiura Yuuki , Horii Shigeru , Kishio Kohji
Published: April 2011

The mixed metal oxides having layered crystal structure have been of much interest because of their various new and excellent functions. Precise phase diagrams on the oxygen content have not been clarified for most of these layered oxides, while oxygen nonstoichiometry often plays a crucial role for determining functions of oxide materials. In this paper, we report oxygen nonstoichiometry and related physical properties mainly on the manganese-based and cobalt-based layered oxides. In the La2–2xSr1+2xMn2Oy (x = 0.3, 0.4), dramatic change in magnetization properties with oxygen content were observed in spite of its small oxygen nonstoichiometry. For (Ca2CoO3-δ)0.62CoO2 systems, high valence metal substitution was found to be effective for suppression of oxygen nonstoichiometry, increase of decomposition temperature and thermoelectric properties.
Amorphous “Ti3N4” and Formation of Nanocrystalline TiN
Authors: Hector Andrew L. , Jackson Andrew W. , McMillan Paul F. , Shebanova Olga
Published: April 2011

The existence of Ti3N4 was proposed as the first product of the thermal decomposition of precipitates obtained in ammonolysis reactions of titanium(IV) dialkylamides. The evidence is re-evaluated and further evidence is presented to demonstrate that these materials are probably TiN contaminated with carbon. However, this precursor system is demonstrated to be a good route to finely divided, nanocrystalline TiN powders.
Preparation and characterization of porous TiO2-SiO2 mixed oxide
Authors: Peng Ang Thiam , Ziyi Zhong , Highfield James
Published: April 2011

A study on the comparison of porous TiO2-SiO2 mixed oxides synthesized variously via the “amine directed” method is reported. The amine capping groups were octylamine, dodecylamine, octyldecylamine, aniline, and isobutylamine. The mixed oxide is characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared spectroscopy (IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Brunauer-Emmett-Teller analysis (BET). While XRD, SEM and TEM provide mainly (bulk) structural information on the mixed oxide preparations, BET (N2 physisorption) probes into their surface area and texture. IR evidence suggests that intimate chemical mixing of both oxides has occurred, while BET measurements show that high surface areas are attainable and that the mixed oxide is more thermally stable than pure (control) samples of TiO2.
Electrostatic Spinning, Pyrolysis, and Characterization of Boron Carbide Nanofibers Prepared from Poly(norbornenyldecaborane) - a Polymeric Ceramic Precursor
Authors: Welna Daniel T. , Wei Xiaolan , Bender Jared D. , Krogman Nick R. , Sneddon Larry G. , Allcock Harry R.
Published: April 2011

Electrostatic spinning is a well-developed technique for the fabrication of fibers in the nanoscale domain. Novel boron carbide nanofibers were generated by the electrostatic spinning and ceramic conversion of poly(norbornenyldecaborane) (PND) - a polymeric ceramic precursor. The prepyrolyzed fibers were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The ceramic fibers were characterized by SEM, X-ray diffraction (XRD), 11B magic-angle spinning nuclear magnetic resonance (MAS NMR) and DRIFT spectroscopy. SEM analysis showed retention of the nanostructure in the pre- and postpyrolyzed fibers.
The Effect of Dopant Additions on the Microstructure of Boron Fibers Before and After Reaction to MgB2
Authors: Marzik James V. , Suplinskas Raymond J. , Croft William J. , MoberlyChan Warren J. , DeFouw John D. , Dunand David C.
Published: April 2011

Boron fibers made by a commercial chemical vapor deposition (CVD) process have been used as precursors for the formation of magnesium diboride (MgB2) superconducting wires. Prior to a reaction with magnesium, the addition of dopants such as carbon and titanium to the boron fiber has been shown to enhance the superconducting properties of MgB2. These dopants also influence the kinetics of the reaction with magnesium. In this study, the effect of carbon dopant additions on the microstructure of boron fibers was investigated using powder x-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, bundles of boron fibers were pressure infiltrated with molten magnesium and reacted at elevated temperatures. The microstructure and microchemistry of the fiber-metal interfaces were investigated by TEM and energy dispersive x-ray analysis (EDS).
Substitution effects on the ruthenium, strontium and gadolinium sites in the RuSr2GdCu2O8 compound.
Authors: Chavira E. , Abatal M. , Filippini C. , Tholence J. L. , García-Vázquez V. , Pérez J. C. , Sulpice A. , Noël Henri
Published: April 2011

We present the more relevant results of various cationic substitutions in the RuSr2GdCu2O8 (Ru-1:2:1:2 ) compound. The substitutions were synthesized by solid-state reaction at ambient pressure in the following systems: Ru1−xSr2GdCu2+xO8 (0.0 < x < 1.0), Ru(Sr2-xCax)GdCu2O8 (0 < x < 2.0) and RuSr2(Gd1-xLnx)Cu2O8 (0 < x < 0.9) with Ln = Dy, Ho, Er, Yb and Lu. All of them were isostructural to Ru-1:2:1:2 compound with tetragonal unit cells. The phases have been characterized by X-Ray powder Diffraction (XRD), observing a solid solution (ss ) up to x = 0.4 for Ru ions replaced by Cu ions, x = 0.1 when we substitute Sr atoms by Ca atoms, and x = 0.7 changing Gd ions by Ln ions. As a result of the Scanning Electron Microscopy (SEM), the grain sizes were discovered to be 1 – 10 μm. The Energy Dispersive X-ray spectroscopy (EDX) analysis permitted us to analyze the impurities that we did not detect with XRD. We observed semiconducting, isolated and ferromagnetic behaviors. No superconducting transition could be observed for these ambient preparation conditions.
Structural Stability and Optical Properties of hexagonal and cubic CdSe Nanocrystals synthesized in MgO
Authors: Eijt S.W.H. , Huis van , Mijnarends P.E. , Kooi B.J. , Nanu M.
Published: April 2011

We present a study of CdSe nanocrystals synthesized in MgO by precipitation of Cd and Se supersaturated solid solutions, created in MgO single crystals by ion implantation, in the temperature range between 300 °C and 1100 °C. For high-dose ion implantation, optical absorption spectroscopy revealed the presence of the ∼1.8 eV CdSe semiconductor band-edge. Small sized nanocrystals adopt the rocksalt instead of the wurtzite structure because the former fits better in the MgO matrix and results in lower interface energies. A better understanding of these structural changes and optical properties is obtained from ab-initio total energy calculations on wurtzite, zincblende and rocksalt CdSe using the VASP pseudopotential code. The calculated electronic band structures are compared of zincblende CdSe, a direct band-gap semiconductor, and rocksalt CdSe, which has an indirect optical band-gap.
ZnO nanorods grown by a Pulsed Laser Deposition process
Authors: Park Jae-Hwan , Choi Young-Jin , Ko Won-Jun , Whang In-Sung , Park Jae-Gwan
Published: April 2011

ZnO nanorods were synthesized by a hot-wall type pulsed laser ablation process. At temperatures 500∼800°C, ZnO thin films and wrinkles were synthesized. Above 800°C, vertically aligned ZnO nanorods were grown on the Si and sapphire substrate without any catalysts. The range of diameter was 100∼300nm. When Au catalyst were deposited on the substrate prior to the deposition, the process range of ZnO nanorod become wider and the diameter of ZnO narrower. Especially, ZnO could be grown selectively along the pattern of Au catalyst with the aid of Au-Zn alloy.
Morphology Development Associated With Polymer Blends
Authors: Hashida Tomoko , Hua Ying , Hsu Shaw Ling , Paul Charles W.
Published: April 2011

Morphology development of crystallizable polymer blends has been investigated using optical microscopy, thermal analysis, and vibrational spectroscopy. The blends studied involve crystallizable polyesters of poly(hexamethylene adipate) (PHMA) and poly(hexamethylene sebacate) (PHMS) and non-crystallizable poly(propylene glycol) (PPG). Although these polyesters possess similar chemical structure, they exhibit different phase behavior. Ternary blends including a high glass transition temperature (Tg) component were also studied. Crystallization kinetics in these blends was obtained utilizing Fourier transform infrared spectroscopy. Micro-Raman spectroscopy capable of achieving high spatial resolution (1 μm2) revealed detailed morphological differences in the phase-separated structures. This technique made possible for the first time characterization of the chemical composition of the blends and distribution of crystallites. The role of the third relative immobile component significantly changed both chemical distribution and the degree of crystallinity.
Treatment of 3‐Wall Intrabony Defects in Patients With Chronic Periodontitis With Autologous Platelet‐Rich Fibrin: A Randomized Controlled Clinical Trial
Authors: Sharma Anuj , Pradeep A.R.
Published: April 2011

Background: Platelet‐rich fibrin (PRF) is considered a second‐generation platelet concentrate that is widely used in osseous regeneration. The present study aims to explore the clinical and radiographic effectiveness of autologous PRF in the treatment of intrabony defects in patients with chronic periodontitis.

Methods: Fifty‐six intrabony defects were treated with either autologous PRF with open‐flap debridement or open‐flap debridement alone. Clinical parameters such as the probing depth (PD) and periodontal attachment level (PAL) were recorded at baseline and 9 months postoperatively. The defect fill at baseline and 9 months was calculated on standardized radiographs by using image‐analysis software.

Results: The mean PD reduction was greater in the test group (4.55 ± 1.87 mm) than in the control group (3.21 ± 1.64 mm), whereas the mean PAL gain was also greater in the test group (3.31 ± 1.76) compared to the control group (2.77 ± 1.44 mm). Furthermore, a significantly greater percentage of mean bone fill was found in the test group (48.26% ± 5.72%) compared to the control group (1.80% ± 1.56%).

Conclusions: Within the limits of the present study, there was greater PD reduction, PAL gain, and bone fill at sites treated with PRF with conventional open‐flap debridement compared to conventional open‐flap debridement alone. However, a long‐term, multicentered randomized controlled clinical trial is required to know the clinical and radiographic effects of PRF on bone regeneration.
Legalizing Euthanasia or Assisted Suicide: The Illusion of Safeguards and Controls
Authors: Pereira José
Published: April 2011

Euthanasia or assisted suicide—and sometimes both—have been legalized in a small number of countries and states. In all jurisdictions, laws and safeguards were put in place to prevent abuse and misuse of these practices. Prevention measures have included, among others, explicit consent by the person requesting euthanasia, mandatory reporting of all cases, administration only by physicians (with the exception of Switzerland), and consultation by a second physician. The present paper provides evidence that these laws and safeguards are regularly ignored and transgressed in all the jurisdictions and that transgressions are not prosecuted. For example, about 900 people annually are administered lethal substances without having given explicit consent, and in one jurisdiction, almost 50% of cases of euthanasia are not reported. Increased tolerance of transgressions in societies with such laws represents a social “slippery slope,” as do changes to the laws and criteria that followed legalization. Although the initial intent was to limit euthanasia and assisted suicide to a lastresort option for a very small number of terminally ill people, some jurisdictions now extend the practice to newborns, children, and people with dementia. A terminal illness is no longer a prerequisite. In the Netherlands, euthanasia for anyone over the age of 70 who is “tired of living” is now being considered. Legalizing euthanasia and assisted suicide therefore places many people at risk, affects the values of society over time, and does not provide controls and safeguards.
Fibroblast Proliferation due to Exposure to a Platelet Concentrate: An in vitro Study
Authors: Ahuja Shelly
Published: April 2011

Introduction

The major cellular events in the tissue repair are mitogenesis, migration and metabolism. The proteins responsible for coordination of these events are called “growth factors”. The activated platelets at the wound margins release several growth factors, such as PDGF, TGF-β and EGF, etc., and plasma exudates also provide an important source of TGF-β factors.

Materials and methods

Periodontal ligament fibroblast obtained from third molar impaction surgery, periodontal ligaments were cultured under standard conditions and spread on 96 well tissue culture plates. Platelet concentrate was obtained after centrifugation of 350-400 ml of blood at 1000 and 5000 rpm. 15 μl of platelet concentrate was added to each well. The proliferation rate of test and control group was determined by Redox indicator (Alamar blue® assay). The number of cells were counted by neu bar counting chamber after 24, 48 and 72 hours.

Results

The proliferation activity of cells was considerably higher in the platelet concentrate group (test group) than the control group. The difference was highly significant upto 72 hours after addition of platelet concentrates (Mann-Whitney U test p < 0.001).

Conclusion

A cellular effect of the platelet concentrate is clearly discernible. It was concluded that the use of platelet concentrate is an effective modality of regeneration.
Chronic Odontogenic Sinus Tracts associated with an Impacted Tooth: Report of Two Cases
Authors: Mathur Abhishek , Anup Kumar G , Ashwin DP , Gowda Lagna
Published: April 2011

Odontogenic sinus tracts in the face and neck region are relatively uncommon and may present a diagnostic problem. As specific dental symptoms usually are absent in these cases, patients generally visit physician first for the evaluation and treatment because of the absence of dental symptoms. These cutaneous sinus tracts are most commonly located on the chin, cheek or in the submandibular area and rarely in the nasal region. Diagnostic errors can result in multiple surgical excisions and biopsies, long-term antibiotic therapy and even radiation therapy or electrodessication.1 The primary odontogenic disorder that results in such cutaneous lesions is typically a chronic periapical abscess or an impacted tooth or a root piece. We report two cases of extraoral sinus tracts, which were diagnosed as cutaneous sinus tracts of dental origin only after the failure of initial misdirected therapy.
A Propensity Score Matching Application: Indications and Results of Adding Scleral Buckle to Vitrectomy: The Retina 1 Project: Report 3
Authors: Sanabria María R. , Fernández Itziar , Sala-Puigdollers Anna , Rojas Jimena , Alfaiate Mario , Elizalde Javier , Navea Amparo , Cordoves Luis , Ruiz-Miguel Miguel , Diaz-Llopis Manuel , Coco Rosa M. , De La Rúa Enrique Rodríguez , Pastor José C.
Published: April 2011

Purpose

To identify the indications and differences in outcomes for adding a scleral buckle (SB) to pars plana vitrectomy (PPV) in a prospective series of rhegmatogenous retinal detachment (RD) by using propensity score matching (PSM) to analyze causal effects in observational studies.

Methods

Data were collected from the Retina 1 Project, a prospective, interventional, nonrandomized study of consecutive RDs. Case selection was based upon treatment with PPV or PPV+SB. Surgeons followed personal criteria for the inclusion of SB in the PPV. Propensity score matching corrected for selection biases. Outcomes were assessed by anatomic and visual criteria and the development of proliferative vitreoretinopathy.

Results

Of 523 patients analyzed, 251 had PPV and 272 had PPV+SB. Surgeons used PPV+SB more frequently in younger patients with RD, in those with posterior or unidentified breaks, in phakic eyes, in eyes with the posterior vitreous attached, and for more extended RDs. Overall single surgery anatomic success rate was 86.4%. Based on PSM, there were no difference in reattachment rates of the PPV group, 86.9%, and the PPV+SB group, 85.93%. The incidence of PVR was similar in both groups, with 8.5% in the PPV group and 10.5% in the PPV+SB group.

Conclusions

Data from the Retina 1 Project established the indications for adding SB to PPV in treating primary RD in this series. No anatomic or visual differences between PPV and PPV+SB were found.
Applications of Permanent Maglev Bearing in Heart Pumps and Turbine Machine
Authors: Qian Kun-Xi , Jing Teng , Wang Hao
Published: April 2011

Earnshaw's theorem (1839) stated that no stationary object made of magnets in a fixed configuration can be held in stable equilibrium by any combination of static magnetic or gravitational forces. What will happen by a moving body like a rotating passive magnetic levitator? Nobody has given an answer until now.
The author applied a self-made passive magnetic bearing to radial pump and turbine machine and found that if the rotating speed could be higher than a critical value, 3250 rpm for a pump and 1800 rpm for a turbine, the rotors would be disaffiliated from stators and keep the rotation stable. It seems that the fast rotating levitator has a so-called “Gyroeffect” which makes the passive maglev rotator stable. These results have extended Earnshaw's theorem from static to dynamic equilibrium. In static state or by a speed lower than critical value, the passive maglev rotator cannot keep rotation stable; if the rotating speed is higher than critical speed, the passive magnetic levitator will have Gyroeffect and thereby stabilize its rotation.
Analysis of oxide and vanadate supports for catalytic hydrogen combustion: Kinetic and mechanistic investigations
Authors: Deshpande Parag A. , Polisetti Sneha , Madras Giridhar
Published: March 2011

Combustion synthesized oxide and vanadate compounds (CeO2, Fe2O3, CeVO4, and FeVO4) were tested for catalytic hydrogen combustion. The compounds were characterized by X‐ray diffraction and X‐ray photoelectron spectroscopy. All the four compounds showed good activity and stability for catalytic hydrogen combustion and more than 95% conversion was observed over all the compounds within 500°C. The mechanisms for the reaction over the different classes of compounds (cerium‐based and iron‐based compounds) were proposed on the basis of spectroscopic observations. The main difference in the mechanisms was in the nature of adsorption of H2 over the sites. The elementary processes for the reaction were proposed, corresponding rate expressions were derived, and the rate parameters for the reaction were estimated using nonlinear regression. Langmuir‐Hinshelwood and Eley‐Rideal mechanisms were also tested for the reaction and the proposed mechanism was compared with these mechanisms. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Powder hydrophobicity and flow properties: Effect of feed frame design and operating parameters
Authors: Mendez Rafael , Muzzio Fernando J. , Velazquez Carlos
Published: March 2011

The effect of feed frames, a device used in rotary tablet presses to drive the powders into compression dies, on the properties of the powders entering the dies is systematically described in this article. The work focuses on the effect of blend composition, feed frame parameters (blade speed and residence time), and rotary die disc parameters (die disc speed and die diameter) on powder overlubrication, the flow properties of the blends, and the resulting tablet properties (tablet hardness and dissolution). For lubricated blends, the feed frame had a large impact on powder hydrophobicity and powder flow properties. Hydrophobicity results demonstrated that the shear applied by the feed frame caused overlubrication of the powders, which improved the powder flow properties but affected adversely the tablet hardness and dissolution. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Getting to value in neurological care: A roadmap for academic neurology
Authors: Holloway Robert G. , Ringel Steven P.
Published: March 2011

Academic neurology is undergoing transformational changes. The public investment in biomedical research and clinical care is enormous and there is a growing perception that the return on this huge investment is insufficient. Hospitals, departments, and individual neurologists should expect more scrutiny as information about their quality of care and financial relationships with industry are increasingly reported to the public. There are unprecedented changes occurring in the financing and delivery of health care and research that will have profound impact on the mission and operation of academic departments of neurology. With the passage of the Patient Protection and Affordable Care Act (PPACA) there will be increasing emphasis on research that demonstrates value and includes the patient's perspective. Here we review neurological investigations of our clinical and research enterprises that focus on quality of care and comparative effectiveness, including cost‐effectiveness. By highlighting progress made and the challenges that lie ahead, we hope to create a clinical, educational, and research roadmap for academic departments of neurology to thrive in today's increasingly regulated environment. Ann Neurol 2011;69:909–918
Modeling the tensile behavior of ultra‐high‐molecular‐weight polyethylene with a novel flow rule
Authors: Sweeney J. , Naz S. , Coates P. D.
Published: March 2011

A study of the tensile behavior of ultra‐high‐molecular‐weight polyethylene over a range of strain rates showed that its strain rate sensitivity was a function of the strain. This was related to a flow rule developed for this material in a previous study on compressive behavior. This flow rule is an adaptation of that of Hill, in which the anisotropy coefficients are power‐law functions of the extension ratios. It is used in conjunction with an Eyring process. The observed rate dependence of the tensile behavior conformed with that obtained with the power‐law flow rule and could be used to derive a value of the power‐law coefficient. Independent observations were made of the relationship between the axial and transverse strains in tensile specimens with inhomogeneous strain fields. A constitutive model was developed that incorporates the new flow rule and was implemented in a finite element analysis. When this analysis was used to model the inhomogeneous tensile specimens, it gave predictions of the axial and transverse strain that were consistent with the experiment when the power‐law coefficient was the same value as that derived from the study of the rate dependence. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Modulation of barrier properties of monolayer films from blends of polyethylene with ethylene‐co‐norbornene
Authors: Taglialatela Scafati S. , Boragno L. , Losio S. , Limbo S. , Castellano M. , Sacchi M. C. , Stagnaro P.
Published: March 2011

Flexible monolayer films with modulated diffusional and optical properties were achieved from blends of a LDPE/LLDPE matrix and an ethylene/norbornene copolymer (COC). A significant decrease of O2 and CO2 permeability was observed for cast films with COC content from 5 to 20 wt %. SEM analysis showed that, despite the incompatibility of the blend components, good dispersion and distribution of the COC domains in the PE matrix were achieved; as a consequence, for COC content ranging from 5 to 10 wt % the film transparency results practically unchanged. The UV light transmission decreased on increasing the percentage of COC, which constitutes also a protection against UV radiations. A noticeable improvement was observed in the mechanical properties: adding only 5 wt % of COC, the elastic modulus becomes five times higher than that of the PE matrix. The rheological behavior of the blends keeps practically unchanged with respect to the matrix, allowing to use the typical LDPE processing conditions. Sustainable inexpensive flexible films answering the packaging requirements of specific categories of food were achieved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
A novel method for the preparation of spherical cellulose‐tungsten carbide composite matrix with NMMO as nonderivatizing solvent
Authors: Phottraithip Wimonrat , Lin Dong‐Qiang , Shi Fei , Yao Shan‐Jing
Published: March 2011

N‐methylmorpholine‐N‐oxide (NMMO) was used as the nonderivatizing solvent for dissolving cellulose, and the cellulose‐tungsten carbide composite particles were prepared with water‐in‐oil suspension and cooling regeneration. Some key factors, such as dissolution temperature and time, water content, cellulose concentration, dispersion, and cooling were optimized. The solubility of cellulose in the NMMO solution was greatly dependent on the water content, which should be controlled at the range of 11 to 15 wt %. In addition, the influences of water content of the cellulose/NMMO/water solution on the properties of composite beads were studied, including bead size, wet density, and pore properties. It was found that 13 wt % water content was most appropriate. The expansion and liquid mixing properties of composite beads in an expanded bed were also explored. The results indicated that the cellulose composite beads prepared could be used as the matrix for expanded bed adsorption processes. Compared with the traditional technology with cellulose xanthate viscose, new method based on the NMMO dissolution is more environment‐friendly, reduces the process time and shows a potential application for large scale preparation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Coincorporation of nano‐silica and nano‐calcium carbonate in polypropylene
Authors: Zhang Shilian , Zhu Aiping , Dai Sheng
Published: March 2011

In this study, various polypropylene (PP) nanocomposites were prepared by melt blending method. The effects of different spherical nanofillers, such as 50 nm CaCO3 and 20 nm SiO2, on the linear viscoelastic property, crystallization behavior, morphology and mechanical property of the resulting PP nanocomposites were examined. Rheological study indicated that coincorporation of nano‐SiO2 and nano‐CaCO3 favored the uniform dispersion of nanoparticles in the PP matrix. Differential scanning calorimeter (DSC) and polarizing optical microscopy (POM) studies revealed that the coincorporation of SiO2 and CaCO3 nanoparticles could effectively improve PP crystallizability, which gave rise to a lower supercooling temperature (ΔT), a shorter crystallization half‐life (t1/2) and a smaller spherulite size in comparison with those nanocomposites incorporating only one type of CaCO3 or SiO2 nanoparticles. The mechanical analysis results also showed that addition of two types of nanoparticles into PP matrix gave rise to enhanced performance than the nanocomposites containing CaCO3 or SiO2 individually. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Interfacial interaction of polyvinylidene fluoride/multiwalled carbon nanotubes nanocomposites: A rheological study
Authors: Wen Rui , Ke Kai , Wang Yu , Yang Wei , Xie Bang‐Hu , Yang Ming‐Bo
Published: March 2011

Polyvinylidene fluoride (PVDF)/multiwalled carbon nanotubes (MWCNTs) nanocomposites were prepared by solution blending method, and the melt viscoelastic behavior of the composites was studied. The results showed that the dispersion of MWCNTs in the matrix and the surface characteristic of MWCNTs had a profound influence on the melt rheological behaviors of the nanocomposites. Generally, the dynamic storage modulus (G′) of the nanocomposites with well dispersed MWCNTs was greatly improved. However, PVDF/MWCNTs‐g‐OH nanocomposites exhibit more significant solid‐like behavior than PVDF/MWCNTs nanocomposites at an MWCNTs loading of 2 wt % or higher, even though the dispersion of MWCNTs‐g‐OH is poorer than that of virgin MWCNTs owing to the higher interfacial interactions from van der Waals force and hydrogen bonding. In this case, the influence of the interfacial interactions on the melt rheological properties was stronger than the dispersion state. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Highly electrically conductive and injection moldable polymeric composites
Authors: Wu Tongfei , Pan Yongzheng , Li Lin
Published: March 2011

Highly electrically conductive polypropylene (PP) composites were prepared by melt mixing using tin–lead (Sn‐Pb) alloy as conducting fillers. Two Sn‐Pb alloys, Sn‐Pb (20/80) and Sn‐Pb (40/60), were used for comparison. The effects of Sn‐Pb loading and molding temperature on electrical conductivity and mechanical properties of composites were investigated. It was found that both factors had significant effect on electrical conductivity of the final Sn‐Pb/PP composite. It was interesting to observe that the molding temperature could control the formation of long‐range conducting paths. The mechanism has been explored through the nonequilibrium phase behavior of Sn‐Pb alloy. The influence of Sn‐Pb loading on mechanical properties of Sn‐Pb/PP composites was also investigated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Demonstration of the use of windows of operation to visualize the effects of fouling on the performance of a chromatographic step
Authors: Boushaba Rihab , Baldascini Helen , Gerontas Spyridon , Titchener‐Hooker Nigel J. , Bracewell Daniel G.
Published: March 2011

The high resolution afforded by packed bed chromatography makes it an indispensable operation in the downstream processing of therapeutic molecules. Packed bed performance is however inherently susceptible to changes in feed stream characteristics and fouling processes. The impact of fouling is seldom considered during the early stages of bioprocess development which is concerned with the selection of purification conditions. Instead these are performed with rigorously clarified feeds. Under such conditions, chromatography is effectively treated as an isolated step, independent from its preceding unit operations. In this study, we demonstrate how windows of operation could be used to visualize the impact of changes in the preceding clarification step on the fouling response of a subsequent cation exchange capture step. Laboratory columns (2,5 and 12 cm height) were subjected to varying fouling challenges of Escherichia coli lysate containing different amounts of solids carried over from the previous step. Changes in trans‐column pressure drop and breakthrough of the target protein (Fab′) were monitored. The limits of operability of the resin were determined with respect to the process material's properties. This information was used to extract the parameters for the adsorption kinetics used in the general rate (GR) model to create windows of operation for manufacturing scale operation. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Third in‐stent restenosis in sirolimus eluting stents
Authors: Ozawa Makito , Okamura Atsunori , Date Motoo , Higuchi Yoshiharu , Nagai Hiroyuki , Shibuya Masahiko , Ryusuke Kimura , Inoue Koichi , Koyama Yasushi , Iwakura Katsuomi , Fujii Kenshi
Published: March 2011

Objectives:

We evaluated the predictive factors for recurrent restenosis lesions treated on two previous occasions with sirolimus‐eluting stents (SES).

Background:

Angiography data related to recurrent SES restenosis have not been reported.

Methods:

Binary restenosis was observed in 66 patients with 78 lesions from a total of 1,393 patients with 1,965 lesions who received follow‐up angiography after SES implantation. We enrolled 55 patients with 67 lesions who underwent revascularization using another SES with a second follow‐up coronary angiography. These restenotic lesions were divided into two groups based on the presence or absence of recurrent restenosis: no recurrent restenosis group (n = 56) and recurrent restenosis group (n = 11). The coronary angiography data during first and second SES implantation were compared between the groups.

Results:

Minimal lumen diameter (MLD) was smaller before first and second percutaneous coronary interventions (PCI) with SES implantation in the recurrent restenotic group compared with no recurrent restenosis group (first PCI, 0.28 ± 0.19 mm vs. 0.54 ± 0.42 mm, P = 0.040; second PCI, 0.44 ± 0.36 mm vs. 0.69 ± 0.39 mm, P = 0.036, respectively). Acute stent recoil after second SES implantation was significantly greater in the recurrent restenosis group compared with no recurrent restenosis group (0.08 ± 0.17 mm vs. 0.20 ± 0.22 mm, P = 0.049, respectively). Multivariate analysis showed preprocedural MLD at first PCI and acute stent recoil at second PCI as independent predictors of recurrent restenosis.

Conclusions:

Preprocedural smaller MLD at first PCI and acute stent recoil at second PCI are predictors of recurrent restenosis treated on two previous occasions with SES. © 2011 Wiley Periodicals, Inc
Long‐term clinical outcomes of successful versus unsuccessful revascularization with drug‐eluting stents for true chronic total occlusion
Authors: Lee Seung‐Whan , Lee Jong‐Young , Park Duk‐Woo , Kim Young‐Hak , Yun Sung‐Cheol , Kim Won‐Jang , Suh Jon , Cho Yoon Hang , Lee Nae‐Hee , Kang Soo‐Jin , Lee Cheol Whan , Park Seong‐Wook , Park Seung‐Jung
Published: March 2011

Objectives: The aims of this study were to investigate the long‐term clinical outcomes of patients with successful versus unsuccessful revascularization with drug‐eluting stents (DES) for chronic total occlusion (CTO). Background: The benefits of successful revascularization of CTO remain unclear. Methods: Consecutive patients (n = 333) with “true” CTO, defined as Thrombolysis In Myocardial Infarction (TIMI) flow grade 0 on angiography and duration ≥3 months, were divided into two groups, those with successful (CTO success group, n = 251) and unsuccessful (CTO failure group, n = 82) revascularization with DES for CTO lesions. The primary endpoint was defined as major adverse cardiac events (MACE) the composite of death, Q‐wave myocardial infarction (MI), or target vessel revascularization (TVR). Results: The CTO success group was significantly younger, with a higher involvement of LAD, and lower incidences of renal failure, previous myocardial infarction, and previous coronary intervention than the CTO failure group. After a median follow up of 1,317 days (interquartile range, 1,059–1,590 days), there were no significant between‐group differences in rate of MACE, both after crude analysis (9.4% vs. 11.8%, log‐rank P = 0.16) and after adjustment (HR 1.17; 95% CI 0.47–2.88, P = 0.53). On multivariate analysis, major predictors of MACE were left ventricle ejection fraction (LVEF) <40% (HR 3.14; 95% CI 1.39–7.09, P = 0.005) and multiple CTO (HR 2.38; 95% CI 1.01–5.71, P = 0.049). Conclusions: Long‐term clinical outcomes were similar in the CTO success and failure groups. Multiple CTOs and LVEF <40% in CTO patients were independent predictors of MACE. © 2011 Wiley‐Liss, Inc.
Comparison of novel sensory panel performance evaluation techniques with e‐nose analysis integration
Authors: Sipos László , Kovács Zoltán , Szöllősi Dániel , Kókai Zoltán , Dalmadi István , Fekete András
Published: March 2011

Reliability and validity of sensory data is an important issue in scientific researches. If sensory analysis is performed in an analytical approach, the resulting data will show a similar structure to the chemical analyses. In the present paper the authors have used a complex approach to evaluate the performance of a sensory panel. The tested samples were black tea batches from different plantations of Sri Lanka. Profile analysis was applied to identify the odor profiles of the samples. Sensory profile data was submitted to two novel techniques of panel performance evaluation. GCAP (Gravity Center Area/Perimeter) is based on the profile polygons of the individual assessors. If the area/perimeter ratio of two panelists' profiles is similar and the gravity center is located near to each other, the panelists performed the tests consistently. CRRN (Compare Ranks with Random Numbers) is applicable not only to sensory data but also to other field of chemometrics. The essence of CRRN method is based on the evaluation of an ‘average’ vector, corresponding to the coordinate‐averages of the measured points, and on a produced random vector series of the same dimension as the measured points. Sensory and e‐nose data were evaluated with principal component analysis, cluster analysis and linear discriminant analysis. Partial least square regression and support vector machine regression were used to predict sensory data with electronic nose results. Prediction by support vector machine gave close correlation between the results of electronic nose measurement and odor attributes. Copyright © 2011 John Wiley & Sons, Ltd.
Improved gas holdup in novel bubble column
Authors: Dhanasekaran S. , Karunanithi T.
Published: March 2011

This investigation reports the experimental and theoretical results carried out to evaluate the gas holdup for air–water system in a novel hybrid rotating and reciprocating perforated plate bubble column under countercurrent condition. The response of this hybrid column is found to be similar to that of reciprocating plate column (RPC) showing mixer‐settler, transition, and emulsion regions. The effect of agitation level, superficial gas velocity, superficial liquid velocity, perforation diameter, and plate spacing on gas holdup is studied and found to be significant. The gas holdup is found to be least in the range of agitation level of 1.3–1.5 cm/s. For all the superficial gas and liquid velocities considered in this present investigation, the critical agitation level at minimum gas holdup remains nearly same. The gas holdup in this hybrid column is 1.2–1.7 times higher in mixer‐settler region and 2.1–2.7 times higher in emulsion region than that of RPC. Correlations have been developed and found to concur with the experimental values. It can be used with 95% accuracy. © 2011 Canadian Society for Chemical Engineering
Residence time distribution in spouted bed drying of maltodextrin solutions on a bed of inert particles
Authors: Osorio‐Revilla Guillermo , Gallardo‐Velázquez Tzayhri , Ramírez‐Torres Arturo , Rivera‐Espinoza Yadira
Published: March 2011

Residence time distributions (RTD) for aqueous maltodextrin solutions were determined in two kinds of spouted bed dryers: (1) conventional spouted bed (CSB) 0.305 m diameter with a bed of polypropylene beads and (2) spout‐fluid bed 0.143 m diameter with draft tube submerged in a bed of FEP® pellets (S‐FBDT). RTD, mean residence time tm, and spread of the distribution σ2, were determined at different drying temperatures, spouting velocities, bed depths, spraying pressures, and feed concentrations. Average values of tm and σ2 were 6.5 min and 26.6 min2 for the CSB and 6.9 min and 36 min2 for the S‐FBDT, respectively, for all operating conditions except spraying pressure. RTD curves were well represented by the response of an ideal stirred tank with a superimposed bypass of 15% on average for the CSB and 7% on average for the S‐FBDT dryer for all operating conditions. Increase in spraying pressure produced a reduction of tm and an increase in the bypass fraction of the product in both dryers. © 2011 Canadian Society for Chemical Engineering
Stability of slot‐rectangular spouted beds: Effect of slot configuration
Authors: Chen Z. , Lim C. J. , Grace J. R.
Published: March 2011

Experiments were carried out to determine the flow stability of slot‐rectangular spouted beds of 300 × 100 mm cross‐section with slots of different widths, lengths, and depths. The effects of slot expansion angle and diverging base were also investigated. Dependent variables included the minimum spouting velocity, bed pressure drop and standard deviation of pressure fluctuations. Based on the flow regimes and spout termination mechanisms, instability was found to be mainly due to the interaction of multiple spouts. Criteria were identified relating stable spouting to slot dimensions and particle size. Slots of limited cross‐sectional area can provide sustainable and symmetric spouting with little fluctuation, as long as the slot length‐to‐width ratio and depth are within certain limits, related to those for conventional spouted beds.
Numerical simulation on wave behaviour and flow dynamics of laminar‐wavy falling films: Effect of surface tension and viscosity
Authors: Bo Shoushi , Ma Xuehu , Lan Zhong , Chen Hongxia , Chen Jiabin
Published: March 2011

Numerical simulation has been made on wave behaviour and flow dynamics of falling films of aqueous lithium bromide solution along a vertical wall in the present study. Volume of fluid model is used to track the free surfaces and continuum surface force model is used for dynamic boundary conditions considering the effect of surface tension. A small amplitude forcing perturbation is introduced at the inlet of the flow boundary. Effect of surface tension and viscosity on wave behaviour and flow dynamics has been investigated. The simulation results indicate that wave peak height decreases with increasing surface tension and the number of capillary waves in front of a large wave increases. With the decrease of viscosity wave shape changes from the sinusoidal shape to the solitary one. Furthermore, the flow dynamics underneath the typical waves are analysed, especially the pattern of backflow. © 2011 Canadian Society for Chemical Engineering
Stagnation point flow towards a stretching/shrinking sheet in a micropolar fluid with a convective surface boundary condition
Authors: Yacob Nor Azizah , Ishak Anuar
Published: March 2011

The problem of a steady laminar two‐dimensional stagnation point flow towards a stretching/shrinking sheet in a micropolar fluid with a convective surface boundary condition is studied. The governing partial differential equations are transformed into ordinary differential equations using a similarity transformation, before being solved numerically using the Runge–Kutta–Fehlberg method with shooting technique. The effects of the material parameter and the convective parameter on the fluid flow and heat transfer characteristics are disscussed. It is found that the skin friction coefficient and the heat transfer rate at the surface decrease with increasing values of the material parameter. Moreover, dual solutions are found to exist for the shrinking case, while for the stretching case, the solution is unique. © 2011 Canadian Society for Chemical Engineering
CFD applied to turbulent flows in concentric and eccentric annuli with inner shaft rotation
Authors: Neto J. L. Vieira , Martins A. L. , Neto A. Silveira , Ataíde C. H. , Barrozo M. A. S.
Published: March 2011

Turbulent flows in concentric and eccentric annuli with and without rotating inner cylinder were investigated by numerical simulations. Similar flows occur in drilling operations of oil wells. Several turbulence models with Reynolds Average Navier–Stokes approach were used in the simulations and the respective models predictions were compared with experimental data from the literature. The simulated results of axial and tangential velocities show a good agreement with the experimental data. As compared with another turbulence models, the simulations with the standard Reynolds Stress model presented a slightly better prediction for most of the responses studied.
Characterization of neuropeptide Y2 receptor protein expression in the mouse brain. II. Coexistence with NPY, the Y1 receptor, and other neurotransmitter‐related molecules
Authors: Stanić Davor , Mulder Jan , Watanabe Masahiko , Hökfelt Tomas
Published: March 2011

Neuropeptide Y (NPY) is widely expressed in the brain and its biological effects are mediated through a variety of receptors. We examined, using immunohistochemistry, expression of the Y2 receptor (R) protein in the adult mouse brain and its association with NPY and the Y1R, as well as a range of additional neurotransmitters and signaling‐related molecules, which previously has not been defined. Our main focus was on the hippocampal formation (HiFo), amygdaloid complex, and hypothalamus, considering the known functions of NPY and the wide expression of NPY, Y1R, and Y2R in these regions. Y2R‐like immunoreactivity (‐LI) was distributed in nerve fibers/terminal endings throughout the brain axis, without apparent colocalization with NPY or the Y1R. Occasional coexistence between NPY‐ and Y1R‐LI was found in the HiFo. Following colchicine treatment, Y2R‐LI accumulated in cell bodies that coexpressed γ‐aminobutyric acid (GABA) in a population of cells in the amygdaloid complex and lateral septal nucleus, but not in the HiFo. Instead, Y2R‐positive nerve terminals appeared to surround GABA‐immunoreactive (ir) cells in the HiFo and other neuronal populations, e.g., NPY‐ir cells in HiFo and tyrosine hydroxylase‐ir cells in the hypothalamus. In the HiFo, Y2R‐ir mossy fibers coexpressed GABA, glutamic acid decarboxylase 67 and calbindin, and Y2R‐LI was found in the same fibers that contained the presynaptic metabotropic glutamate receptor 2, but not together with any of the three vesicular glutamate transporters. Our findings provide further support that Y2R is mostly presynaptic, and that Y2Rs thus have a modulatory role in mediating presynaptic neurotransmitter release. J. Comp. Neurol. 519:1219–1257, 2011. © 2011 Wiley‐Liss, Inc.
Multi‐GPU algorithm for k‐nearest neighbor problem
Authors: Kato Kimikazu , Hosino Tikara
Published: March 2011

The recommendation system is a mechanism which automatically recommends items that are likely to be of interest to the user. In the recommendation system, customers' preferences are encoded into vectors, and finding the nearest vectors to each vector is an essential part. This vector‐searching part of the problem is called a k‐nearest neighbor problem. We give an effective algorithm to solve this problem on multiple graphics processor units (GPUs). Our algorithm consists of two parts: the N‐body problem and the partial sort. For an algorithm of the N‐body problem, we applied the idea of a known algorithm, although another trick is needed to overcome the problem of small‐sized shared memory. For the partial sort, we give a novel GPU algorithm which is effective for small k. In our partial sort algorithm, a heap is accessed in parallel by threads with a low cost of synchronization. We show through an experiment that when the size of the problem is large, an implementation of the algorithm on two GPUs runs more than 330 times faster than a single core implementation on a latest CPU. Copyright © 2011 John Wiley & Sons, Ltd.
Rapid inexpensive assay method for verapamil by spectrophotometric sequential injection analysis
Authors: Idris Abubakr M. , Ibrahim Atta E. E. , Abulkibash Abdalla M. , Saleh Tawfik A. , Ibrahim Kamal E. E.
Published: March 2011

Sequential injection analysis (SIA) technique with a miniaturized fibre optic spectrophotometry was exploited to optimize and validate a new method for the assay of verapamil in pharmaceutical formulations. The reduction of acidified permanganate by verapamil was spectrophotometrically detected at 546 nm. The 23 full‐factorial design was adopted for screening the effect of conditions controlling the proposed method, and accordingly for the purpose of optimization. The remarkable advantages of the method are high rapidity (sample frequency was 10.6 samples/h), saving in reagents and sample (total consumed volume was 190 µl) and better safety for the environment (total waste production volume was 2140 µl). Additionally, the method was selective in the presence of excipients usually found in tablet and injection formulations. The average of recovery in synthetic samples as well as dosage forms was 98.8–103.0%. The obtained results were realized by the British Pharmacopoeia method and comparable results were obtained. Copyright © 2011 John Wiley & Sons, Ltd.