bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Photoactive Porous Anatase Films Obtained by Deformation of 3D Mesostructures
Authors: Kimura Tatsuo , Yamauchi Yusuke , Miyamoto Nobuyoshi
Published: March 2011

A transparent film of three‐dimensional (3D) hexagonal (P63/mmc) mesostructured titania was fabricated according to a modified procedure using triblock copolymer Pluronic P123. The precursor solution was diluted with ethanol and spin‐coated to afford a transparent film with a thickness of less than 100 nm. The mesostructure was maintained (deteriorated) at 400 °C, converted to regularly arranged anatase nanopillars with sufficient porosity at 550 °C, and deformed at 700 °C to nanocrystals with intercrystalline mesospaces. The mesostructural variation was related to the degree of shrinkage of the film owing to condensation and crystallization of the titania frameworks. An anatase nanocrystal film having sufficient porosity and high crystallinity was most active in the photodegradation of methylene blue. Such intercrystalline mesospaces can be controlled by regular deformation of 3D mesostructures through anatase nanopillar structures. In addition to adequate crystallinity of the titania frameworks, smooth diffusion of target organic molecules and/or degraded organic compounds was important for effective photodegradation.
Three‐Dimensional Open‐Frameworks Based on LnIIIIons and Open‐/Closed‐Shell PTM Ligands: Synthesis, Structure, Luminescence, and Magnetic Properties
Authors: Datcu Angela , Roques Nans , Jubera Véronique , Imaz Inhar , Maspoch Daniel , Sutter Jean‐Pascal , Rovira Concepció , Veciana Jaume
Published: March 2011

A series of isostructural open‐framework coordination polymers formulated as [Ln(dmf)3(ptmtc)] (Ln=Sm (1), Eu (2), Gd (3), Tb (4), Dy (5); PTMTC=polychlorotriphenylmethyl tricarboxylate) and [Ln(dmf)2H2O(αH‐ptmtc)] (Ln=Sm (1′), Eu (2′), Gd (3′), Tb (4′), Dy (5′)) have been obtained by treating LnIIIions with PTMTC ligands with a radical (PTMTC3−) or a closed‐shell character (αH‐PTMTC3−). X‐ray diffraction analyses reveal that these coordination polymers possess 3D architectures that combine large channels and fairly rare lattice complexTconnectivity. In addition, these compounds show selective framework dynamic sorption properties. For both classes of ligands, the ability to act as an antenna in Ln sensitization processes has been investigated. No luminescence was observed for compounds1–5, and3′because of the PTMTC3−ligand and/or GdIIIion characteristics. Conversely, photoluminescence measurements show that1′,2′,4′, and5′emit dark orange, red, green, and dark cyan metal‐centered luminescence. The magnetic properties of all of these compounds have been investigated. The nature of the {Ln–radical} exchange interaction in these compounds has been assessed by comparing the behavior of the radical‐based coordination polymers1–5with those of the compounds with the diamagnetic ligand set. While antiferromagnetic {Sm–radical} interactions are found in1, ferromagnetic {Ln–radical} interactions propagate in the 3D architectures of3,4, and5(Ln=Gd, Tb, and Dy, respectively). This procedure also provided access to information on the {LnLn} exchange existing in these magnetic systems.
β‐Protic Pyrazole and N‐Heterocyclic Carbene Complexes: Synthesis, Properties, and Metal–Ligand Cooperative Bifunctional Catalysis
Authors: Kuwata Shigeki , Ikariya Takao
Published: March 2011

This Minireview provides an overview of the chemistry of pyrazole and N‐heterocyclic carbene (NHC) complexes bearing an NH group at the β‐position to the metal. The synthesis and structures as well as the Brønsted acidic nature of the β‐NH group are described in detail. These complexes are attractive candidates for novel metal–ligand cooperative bifunctional catalysts, which would benefit highly effective molecular and energy transformations.
Development of a Concise Synthesis of (−)‐Oseltamivir (Tamiflu)
Authors: Trost Barry M. , Zhang Ting
Published: March 2011

We report a full account of our work towards the development of an eight‐step synthesis of anti‐influenza drug (−)‐oseltamivir (Tamiflu) from commercially available starting materials. The final synthetic route proceeds with an overall yield of 30 %. Key transformations include a novel palladium‐catalyzed asymmetric allylic alkylation reaction (Pd‐AAA) as well as a rhodium‐catalyzed chemo‐, regio‐, and stereoselective aziridination reaction.
Lewis Acid/Base Catalyzed [2+2]‐Cycloaddition of Sulfenes and Aldehydes: A Versatile Entry to Chiral Sulfonyl and Sulfinyl Derivatives
Authors: Koch Florian M. , Peters René
Published: March 2011

The first catalytic asymmetric synthesis of β‐sultones is reported. This development has enabled a rapid access to a number of highly enantioenriched biologically interesting sulfonyl and sulfinyl compound classes, which makes use of the inherent ring strain of the four‐membered heterocycles. The products possess either two vicinal stereocenters, such as in β‐hydroxy‐sulfonamides, ‐sulfonates, ‐sulfones, ‐sulfonic acids, ‐sulfinic acids, γ‐sultines, and γ‐sultones or a single stereocenter, such as in α‐branched alkyl or allyl sulfonic acids. This work also represents the first application of sulfene intermediates in asymmetric catalysis. The reactivity of a sulfene normally acting as an electrophile could be reverted by the formation of a nucleophilic zwitterionic sulfene–amine adduct. To achieve a combination of high enantioselectivity and reactivity, cooperative catalytic action of a chiral nucleophilic tertiary amine (the cinchona alkaloid derivative diydroquinine 2,5‐diphenyl‐4,6‐pyrimidinediyl diether ((DHQ)2PYR)) and Bi(OTf)3 or In(OTf)3 was of primary importance.
Modelling asphaltene deposition in turbulent pipeline flows
Authors: Eskin D. , Ratulowski J. , Akbarzadeh K. , Pan S.
Published: March 2011

Asphaltene deposition is one of the important problems of oil production that requires an accurate predictive modelling. We developed an asphaltene deposition model in a pipeline. The model is based on data, which are obtained by experiments performed in a Couette device, where the inner cylinder rotates, and deposition on the outer wall is studied. A detailed theoretical analysis of an applicability of a Couette device for imitation of the asphaltene deposition in a pipe flow is presented. The model developed is based on first principles and consists of the two major modules: (1) a sub‐model describing the particle size distribution evolution in time in a Couette device, and along a pipe; (2) a sub‐model for calculating the particle transport to the wall. A population balance model is employed for modelling the particle size evolution. A concept of the critical particle size is introduced; only particles that are smaller than the critical size can deposit.

The model developed contains only three parameters that are determined experimentally using a Couette device. The model of asphaltene deposition in a Couette device allows accurate describing the deposit mass growth in time. Performance of the deposition model for a pipeline with the coefficients obtained by a laboratory Couette device is also illustrated.

Le dépôt d'asphaltènes est un des problèmes majeurs de l'industrie pétrolière et nécessite des modèles prédictifs fiables. Nous avons développé un modèle de dépôt d'asphaltènes en conduite pétrolière. Le modèle est basé sur des données obtenues expérimentalement par un système Couette avec cylindre intérieur tournant. Le dépôt sur les parois extérieures, fixes, est alors étudié. Une analyse théorique détaillée de l'applicabilité d'un système Couette à l'étude du dépôt d'asphaltènes en écoulement dans une conduite pétrolière est présentée. Le modèle développé est basé sur des principes fondamentaux et consiste en deux principaux modules: (1) un premier module décrivant l'évolution de la distribution de taille des particules avec le temps dans un système Couette et le long d'une conduite, (2) un deuxième module pour le calcul du transport des particules vers la paroi. Un modèle d'équilibre de population (population balance model) est utilisé pour modéliser l'évolution de la taille des particules. Un concept de « taille critique » est alors défini: seules les particules plus petites que cette taille peuvent se déposer. La modélisation contient seulement trois paramètres qui sont déterminés expérimentalement sur un appareil de type Couette. Le modèle permet une description fiable de l'augmentation de la masse de dépôt avec le temps. Les résultats de ce modèle appliqués à une conduite pétrolière avec les paramètres obtenus en laboratoire sur un système Couette sont également démontrés. © 2011 Canadian Society for Chemical Engineering
Machine computations for transient stagewise processes
Authors: Yesberg D. , Johnson A. I.
Published: March 2011

A review of recent work on transient stagewise mass transfer processes is presented, with particular emphasis on numerical and analog solutions for the partial differential difference equations involved. The numerical or analog solutions are relatively simple, whereas the analytical solution even of the linearized equation is quite involved.

An example of gas absorption is considered in which the equations are linearized, and solved numerically as well as by the use of a resistance network analog. These particular methods of solution had not previously been used for this problem, and the present work is compared with previous solutions. The novel feature of the method of solution is the representation of the time derivative by a backward finite difference to produce a set of simultaneous algebraic equations, which may be solved most easily by matrix inversion programmed on a digital computer.
Preparation of aluminum octanoate and aluminum isooctanoate
Authors: Wheat J. A. , MacLeod D. A. , Dunlop R. G. , Sheffer H.
Published: March 2011

Two aluminum soaps have been prepared as hydrocarbon gelling agents. The aluminum soap of 2‐ethylhexanoic acid (Octal) was successfully prepared by a pilot plant continuous process which utilized a flash mixer. Optimum process conditions and the effect of important process variables were determined. There was a seasonal cycle of short gelling times and low gel consistencies in the summer months and high results in the winter. The cause of the cycle is not known.

Aluminum isooctanoate (Isooctal) was prepared continuously and batchwise on both a laboratory and pilot plant scale. The continuously prepared products were not satisfactory. Good Isooctals were prepared batchwise and pilot plant results were the same as those obtained in the laboratory. Gel consistencies showed a seasonal cycle but thickening rates did not.
The upward vertical flow of air‐water mixtures: III. Effect of gas phase density on flow pattern, holdup and pressure drop
Authors: Brown R. A. S. , Sullivan G. A. , Govier G. W.
Published: March 2011

Results of measurements of pressure drop and holdup are reported over a range of air and water rates for the upward vertical flow of air‐water mixtures in a 1.50 inch I.D. tube with average air densities ranging from 0.092 to 0.552 lb./ft.3 Superficial water velocities were between 0.0695 and 7.35 ft./sec.

The data are analyzed by the method first suggested by Govier, Radford and Dunn and later used by Govier and Short. This involves the division of the flow range into four regimes on the basis of the pressure drop curves (to aid correlation of flow pattern and holdup data) and the separation of the unit pressure drop into hydrostatic and irreversible components. A superficial friction factor is calculated from the irreversible component of the unit pressure drop.

The average density of the gas phase has a more or less marked effect on all three regime transitions. The transitions all shift similarly to lower air‐water discharge volume ratios with increasing gas phase density. While the flow patterns were not directly observed in the investigation here reported, the flow pattern transitions would be expected to behave similarly.

Over the range investigated, the gas phase density has little or no effect on the superficial friction factor. The holdup ratio is unaffected by the gas phase density in Regimes I and II but is significantly affected in Regimes III and IV.
Photocatalytic Activity of Combustion Synthesized Nanocrystalline CeAlO3
Authors: Deshpande Parag A. , Aruna S. T. , Madras Giridhar
Published: March 2011

The photocatalytic activity of combustion synthesized nanocrystalline CeAlO3 was determined for the degradation of four anionic and four cationic dyes. The perovskite oxide showed high‐photocatalytic activity and a complete degradation of all the dyes was possible within 2 h. The photocatalytic activity of the compound was comparable with the activity of the commercial Degussa P‐25 TiO2 catalyst. The degradation of dyes was found to follow first order kinetics and the first order degradation rate constants were determined.
Impact of post‐therapy positron emission tomography on prognostic stratification and surveillance after chemoradiotherapy for cervical cancer
Authors: Siva Shankar , Herschtal Alan , Thomas Jessica M. , Bernshaw David M. , Gill Suki , Hicks Rodney J. , Narayan Kailash
Published: March 2011

BACKGROUND:

A study was undertaken to investigate the detection of relapse and survival outcomes in patients with cervical cancer treated with curative intent chemoradiotherapy, and evaluated with a post‐therapy 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) scan.

METHODS:

Between January 2002 and June 2007, 105 consecutive patients were prospectively enrolled into a registry study designed to assess outcomes of chemoradiotherapy. A FDG‐PET scan was performed between 3 and 12 months (median, 4.9 months) post‐treatment at clinician discretion. Tumor response was graded as complete metabolic response, partial metabolic response, or progressive metabolic disease.

RESULTS:

Median follow‐up was 36 months. At post‐therapy FDG‐PET, 73 (70%) patients had complete metabolic response, 10 (9%) had partial metabolic response, and 22 (21%) had progressive metabolic disease. Overall survival at 3 years was 77% in all patients, and 95% for those with complete metabolic response. On multivariate analysis, complete metabolic response (P < .0001) and pretreatment tumor volume (P = .041) were strong predictors for overall survival. The number of involved lymph nodes (P < .005) and International Federation of Gynecology and Obstetrics stage (P = .04) were predictive of relapse‐free survival. In total, 18 patients relapsed at a single site, and 13 underwent salvage, with a 3‐year survival of 67%. Patients with complete metabolic response had a distant failure rate 36‐fold less than those with partial metabolic response (P < .0001). After complete metabolic response, only 1 patient (1.6%) relapsed without symptoms and was detected through physical examination.

CONCLUSIONS:

The presence of a complete metabolic response at post‐therapy FDG‐PET is a powerful predictor for survival after chemoradiation. The very low rate of recurrence in patients with a complete metabolic response justifies a conservative follow‐up approach for these patients, because relapse is usually symptomatic and not detected by routine clinical review. Cancer 2011. © 2011 American Cancer Society.
Prognostic web‐based models for stage II and III colon cancer
Authors: Gill Sharlene , Loprinzi Charles , Kennecke Hagen , Grothey Axel , Nelson Garth , Woods Ryan , Speers Caroline , Alberts Steven R. , Bardia Aditya , O'Connell Michael J. , Sargent Daniel J.
Published: March 2011

BACKGROUND:

Numeracy and Adjuvant! are 2 web‐based calculators that are used widely to estimate the prognosis and potential benefit of adjuvant 5‐fluorouracil (5‐FU)–based therapy for patients with stage II and III colon cancer. In this study, the authors compared the predicted survival estimates from these models with the actual observed estimates in independent datasets that were derived from a population cohort and from clinical trials.

METHODS:

The population cohort was derived from the British Columbia Colorectal Cancer Outcomes Unit database, which identified referred patients with stage II and III colon cancer from 1995 to 1996 and from 1999 to 2003. Patients who were enrolled in North Central Cancer Trials Group (NCCTG) trials NCCTG 94651 and NCCTG 914653 were included in the trials dataset. Patient and disease data were used to predict 5‐year relapse‐free and overall survival using both tools.

RESULTS:

In the population‐based dataset (N = 2033), Adjuvant! offered more reliable predictions of prognosis for patients who underwent surgery alone, but it had reliability similar to that of Numeracy for predicting the prognosis for patients who received adjuvant 5‐FU. Both models tended to overestimate survival for patients with stage II disease who received 5‐FU. In the trials dataset of patients who underwent and received 5‐FU (N = 1729), Numeracy and Adjuvant! demonstrated similar performance and improved correctness.

CONCLUSIONS:

This independent validation analysis demonstrated that both Numeracy and Adjuvant! had similar predictive performance and acceptable reliability for patients with stage III disease. Survival outcomes of patients with stage II colon cancer who received adjuvant 5‐FU were slightly lower than estimated by either model. Cancer 2011;. © 2011 American Cancer Society.
Cytology workload calculation—Has anything really changed?
Authors: Moriarty Ann T.
Published: March 2011

The method of counting slides has changed, but the new counting method does not address evidence‐based data ensuring the safety of the established workload limits.
Color composition features in modern architecture
Authors: Serra Juan , García Ángela , Torres Ana , Llopis Jorge
Published: March 2011

The color composition in modern architecture has been often characterized in a simplistic manner. In fact, this is a complex phenomenon to be studied because of the disparity of proposals and the uniqueness of the architects involved. This research starts with a comparative study of three of the most relevant color composition systems in the first half of the 20th century (Purism and Le Corbusier, Expressionism and Taut, Neoplasticism and Rietveld), and aims to find common characteristics among them, discussing the validity of some widespread ideas about it, such as the prominence of white hues, the use of ”flat colors,” or the conception of color during the ideation phase. We propose and demonstrate three principles that are not categorical about the color composition in modern architecture: it limits the variety of hues; it not only uses white color but also displays color to conform shapes and to transform them; color has ethical connotations and not only aesthetic ones. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011
A theory of unique hues and colour categories in the human colour vision
Authors: Logvinenko* Alexander D.
Published: March 2011

A novel approach to assessing colour appearance is described. It is based on a new technique—partial hue‐matching—which allows for measuring colour in terms of component hues objectively, without resorting to verbal definitions. The new method is believed to have a potential to be as exact as colorimetric techniques. In contrast to classical colour matching, which implies visual equivalence of lights, partial hue‐matching is based on judgements of whether two lights that are different in colour have some hue in common. The major difference between classical colour matching and partial hue‐matching is that the latter is intransitive, whereas the former is generally believed to be transitive (though see Logvinenko, Symposium on 75 years of the CIE Standard Colorimetric Observer, Vienna, Austria, 2006). Formally, partial hue‐matching can be described as a reflexive and symmetric binary relation (i.e., tolerance). The theoretical framework of tolerance spaces is used for developing a theory of partial hue‐matching. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011
Goniochromatic properties of human tooth dentin
Authors: Lee Yong‐Keun , Zhao Guang‐Feng , Yu Bin , Lim Ho‐Nam , Lu Huan
Published: March 2011

This study measured the goniochromatic properties of human tooth dentin through the viewing angle dependent color change measurement, and determined the influence of the microscopic structural nonuniformity of dentin surface on the gonioappearance. Color of 21 polished dentin specimens was measured by a spectroradiometer in wet and dry conditions. Spectral reflectance values were obtained with 0, 20, 45, and 70° aspecular viewing angles to the surface. These values were converted to CIE color coordinates (CIE L*, a*, and b*) relative to the specular set (0°) standard white tile to determine general goniochromatic effect, and to the same aspecular set standard white tiles to determine the influence of nonuniformity on dentin surface caused by dentinal tubules. Color coordinates and chroma were influenced by the viewing angle (P < 0.05). As to the influence of nonuniformity, CIE L* and a* and chroma were influenced by the viewing angle while CIE b* was not (P = 0.05). Goniochromatic effect of human dentin was confirmed instrumentally, and the nonuniformity of dentin increased goniochromatic effect. Based on these results, goniochromatic properties of intact teeth should be studied further, and restorative materials that can simulate these properties should be developed. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2012
A critical role for phagocytosis in resistance to malaria in iron‐deficient mice
Authors: Matsuzaki‐Moriya Chikako , Tu Liping , Ishida Hidekazu , Imai Takashi , Suzue Kazutomo , Hirai Makoto , Tetsutani Kohhei , Hamano Shinjiro , Shimokawa Chikako , Hisaeda Hajime
Published: March 2011

Both iron‐deficient anemia (IDA) and malaria remain a threat to children in developing countries. Children with IDA are resistant to malaria, but the reasons for this are unknown. In this study, we addressed the mechanisms underlying the protection against malaria observed in IDA individuals using a rodent malaria parasite, Plasmodium yoelii (Py). We showed that the intra‐erythrocytic proliferation and amplification of Py parasites were not suppressed in IDA erythrocytes and immune responses specific for Py parasites were not enhanced in IDA mice. We also found that parasitized IDA cells were more susceptible to engulfment by phagocytes in vitro than control cells, resulting in rapid clearance of parasitized cells and that protection of IDA mice from malaria was abrogated by inhibiting phagocytosis. One possible reason for this rapid clearance might be increased exposure of phosphatidylserine at the outer leaflet of parasitized IDA erythrocytes. The results of this study suggest that parasitized IDA erythrocytes are eliminated by phagocytic cells, which sense alterations in the membrane structure of parasitized IDA erythrocytes.
Electrochemiluminescence Aptamer Biosensor for Detection of Thrombin Based on CdS QDs/ACNTs Electrode
Authors: Yang Lizhu , Zhu Jing , Xu Ying , Yun Wen , Zhang Renyi , He Pingang , Fang Yuzhi
Published: March 2011

A label‐free ECL aptamer biosensor based on CdS QDs/ACNTs electrode for the sensitive detection of thrombin was fabricated. CdS QDs and Chitosan (CTS) complex films were coated and filled the tubes of ACNTs by carrying out electrodeposition reaction of CTS‐CdS QDs on ACNTs electrode, the resulting electrode showed high ECL intensity and good biocompatibility. After aptamer was bound to the film via glutaric dialdehyde, the modified electrode could be used as an ECL aptamer sensor for the thrombin detection. The specific reaction between thrombin and aptamer resulted in the decrease in ECL intensity. The change of the ECL intensity was found to be linear with the logarithm of thrombin concentration in the range from 1.0×10−13 M to 1.0×10−9 M. The ECL aptamer sensor had the advantages of speed, high sensitivity, specificity and stability, which could be a promising technique for protein detection.
Electrochemical Determination of L‐Dopa in Mucuna pruriens Seeds, Leaves and Commercial Siddha Product Using Gold Modified Pencil Graphite Electrode
Authors: Kalachar H. C. B. , S. Basavanna  , Viswanatha R. , Naik Y. Arthoba , Raj D. Ananda , Sudha P. N.
Published: March 2011

In the present work a gold modified pencil graphite electrode (GPGE) was used for the determination of L‐dopa present in the aqueous extracts of Mucuna pruriens seeds (MPS), Mucuna pruriens leaves (MPL) and Commercial Siddha Product (CSP). The GPGE shows excellent electrocatalytic activity towards the oxidation of both L‐dopa and ascorbic acid (AA), with the separation of peak potential of 98 mV. The differential pulse voltammetric (DPV) results indicated that the detection limit for L‐dopa was 1.54 µM (S/N=3). This method can be successfully applied for the determination of L‐dopa in real samples.
Determination of Ofloxacin in Pharmaceuticals, Human Urine and Serum Using a Potentiometric Sensor
Authors: Pimenta A. M. , Souto M. R. S. , Catarino R. I. L. , Leal M. F. C. , Lima J. L. F. C.
Published: March 2011

An ofloxacin‐selective electrode was developed for application in pharmaceutical preparations, serum and urine analysis. The electrode is based on tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate as ion exchanger in a poly(vinyl chloride) membrane. The sensor displayed a Nernstian response for ofloxacin over a wide concentration range (3×10−6–1×10−2 mol L−1) with a slope of 55±1 mV per decade of concentration and a practical detection limit of 1×10−6 mol L−1. The electrode was successfully applied to the determination of ofloxacin in samples with no pretreatment steps, adequate accuracy and precision and recoveries within the intervals of 94–107 %.
Possibilities and Outlooks of the Use of Sensors with Mechanically Renewed Solid Electrodes in Electroanalysis
Authors: Aleksandrova T. P. , Skvortsova L. I. , Bek R. Y. , Vais A. A.
Published: March 2011

The described data provide evidence that developed and implemented device of solid electrode regeneration by cutting off a thin surface layer efficiently enhances the reproducibility of the area and properties of the working surface of the electrode. Broad possibilities of the use of the device for the analysis of various objects were demonstrated. The stripping voltammetry with the high‐voltage accumulation (HVA) of the metals is usable only with the developed sensor. HVA accelerates metal cation deposition by 2–3 orders of magnitude.
Effect of random perturbations on adaptive observation techniques
Authors: Hossen M. J. , Navon I. M. , Daescu D. N.
Published: March 2011

An observation sensitivity (OS) method to identify targeted observations is implemented in the context of four‐dimensional variational (4D‐Var) data assimilation. This methodology is compared with the well‐established adjoint sensitivity (AS) method using a nonlinear Burgers equation as a test model. Automatic differentiation software is used to implement the first‐order adjoint model (ADM) to calculate the gradient of the cost function required in the 4D‐Var minimization algorithm and in the AS computations and the second‐order ADM to obtain information on the Hessian matrix of the 4D‐Var cost that is necessary in the OS computations. Numerical results indicate that the observation‐targeting is particularly successful in reducing the forecast error for moderate Reynolds numbers. The potential benefits of the OS targeting approach over the AS are investigated. The effect of random perturbations on the performance of these adaptive observation techniques is also analyzed. Copyright © 2011 John Wiley & Sons, Ltd.
Thermal analysis of CPU with CCC and copper base plate heat sinks using CFD
Authors: Mohan R. , Govindarajan P.
Published: March 2011

This paper describes experimental and theoretical investigations of heat sinks with different base plate material mounted on CPUs. The thermal model of the computer system with heat sinks which is created using Gambit (for preprocessing) and the simulation is carried out using Fluent (for solver execution and post processing). The following parameters are considered: fin thickness, fin height, and number of fins. Primarily in this paper different base plate thickness and base plate materials are optimized for maintaining the cost and thermal performance of a heat sink. In this research work, the thermal model of the computer system with a slot parallel plate fin heat sink design has been selected, and the fluid flow and thermal flow characteristics of heat sinks are studied. The slot parallel plate fin heat sinks have been used with copper base plates and carbon carbon composite (CCC) base plates to enhance the heat dissipation. The results and conclusion obtained in this present work are found to be in good agreement with numerical results. A complete computer chassis with slot parallel plate heat sinks is investigated varying the thickness of base plate, and the performances of the heat sinks are compared. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.20342
Numerical investigation of mixing length on performance of lobed forced mixer nozzles
Authors: Xie Yi , Liu You‐hong
Published: March 2011

Geometric models of a lobed mixer nozzle with variation of mixing length are created and corresponding flow fields are simulated using a steady Reynolds Averaged Navier–Stokes (RANS) equation with realizable k–ϵ turbulence model. The numerical simulation results show that the mixing length of the nozzle has a relatively great influence on the development of streamwise vortices and the effective range for streamwise vortices to intensify mixing is about 0.5D distance from the lobe trailing edge. The change of mixing length has little effect on the thermal mixing efficiency. As for the total pressure recovery coefficient, the shorter the mixing length, the sharper the total pressure recovery coefficient curve. On the nozzle exit section, the thermal mixing efficiency increases at first and then slightly declines, and the total pressure recovery efficiency changes little as the mixing length increases. In addition, the thrust coefficient has some small relationship with the mixing length. The thrust coefficient increases in waves as the mixing length increases and the difference between the maximum and the minimum values is slightly less than 1% when the mixing length increases from 0.4D to D. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library wileyonlinelibrary.com/journal/htj. DOI 10.1002/htj.20343
Vitamin D receptor polymorphisms in patients with cutaneous melanoma
Authors: Orlow Irene , Roy Pampa , Reiner Anne S. , Yoo Sarah , Patel Himali , Paine Susan , Armstrong Bruce K. , Kricker Anne , Marrett Loraine D. , Millikan Robert C. , Thomas Nancy E. , Gruber Stephen B. , Anton‐Culver Hoda , Rosso Stefano , Gallagher Richard P. , Dwyer Terence , Kanetsky Peter A. , Busam Klaus , From Lynn , Begg Colin B. , Berwick Marianne ,   for the GEM Study Group
Published: March 2011

The vitamin D receptor (VDR) gene has been associated with cancer risk, but only a few polymorphisms have been studied in relation to melanoma risk and the results have been inconsistent. We examined 38 VDR gene single nucleotide polymorphisms (SNPs) in a large international multicenter population‐based case‐control study of melanoma. Buccal DNAs were obtained from 1,207 people with incident multiple primary melanoma and 2,469 with incident single primary melanoma. SNPs with known or suspected impact on VDR activity, haplotype tagging SNPs with ≥10% minor allele frequency in Caucasians, and SNPs reported as significant in other association studies were examined. Logistic regression was used to calculate the relative risks conferred by the individual SNP. Eight of 38 SNPs in the promoter, coding, and 3′ gene regions were individually significantly associated with multiple primary melanoma after adjusting for covariates. The estimated increase in risk for individuals who were homozygous for the minor allele ranged from 25 to 33% for six polymorphisms: rs10875712 (odds ratios [OR] 1.28; 95% confidence interval (CI), 1.01–1.62), rs4760674 (OR 1.33; 95% CI, 1.06–1.67), rs7139166 (OR 1.26; 95%CI, 1.02–1.56), rs4516035 (OR 1.25; 95%CI, 1.01–1.55), rs11168287 (OR 1.27; 95%CI, 1.03–1.57) and rs1544410 (OR 1.30; 95%CI, 1.04–1.63); for two polymorphisms, homozygous carriers had a decreased risk: rs7305032 (OR 0.81; 95%CI 0.65–1.02) and rs7965281 (OR, 0.78; 95%CI, 0.62–0.99). We recognize the potential false positive findings because of multiple comparisons; however, the eight significant SNPs in our study outnumbered the two significant tests expected to occur by chance. The VDR may play a role in melanomagenesis.
Impact of intracellular alpha fetoprotein on retinoic acid receptors‐mediated expression of GADD153 in human hepatoma cell lines
Authors: Li Chaoying , Wang Shanshan , Jiang Wei , Li Hui , Liu Zhongmin , Zhang Chao , McNutt Michael A. , Li Gang
Published: March 2011

The aim of our study was to gain a better understanding of the molecular mechanism underlying the previously unrecognized role of cytoplasmic alpha fetoprotein (AFP) in retinoic acid receptors (RAR) mediated expression and biological effects of GADD153. Using microarray analysis, the expression of the GADD153 gene showed the greatest fold change among apoptosis/growth related genes in response to ATRA. AFP was able to interact with RAR in HepG2 cells, which was undetectable in HLE cells owing to absence of AFP. ATRA promoted nuclei entrance of RAR, expression of GADD153 and apoptosis, and these changes were reversed after transfection with the afp gene or addition of AGN193109. The level of GADD153 was gradually elevated as the effect of AFP was counteracted by increasing dose or prolonging treatment time with ATRA in HepG2 cells. Knockdown of AFP in siRNA‐transfected HepG2 cells or over‐expression of AFP in afp gene‐transfected HLE cells was synchronously associated with up‐regulation or down‐regulation, respectively, of GADD153 expression. Both ATRA administration and AFP knockdown were each able to promote greater binding of RAR to its response element with consequent elevation of the proportion of apoptotic cells. Conversely, transfection of HLE cells with pcDNA3.1‐afp resulted in apparent reduction of RAR binding to DNA and change of biological effect. These data taken together demonstrate the involvement of AFP in RAR‐mediated expression and biological effects of GADD153. These findings provide a novel insight into the mechanism underlying the impact of AFP on the RAR signal network.
Do all roads lead to Rome? Routes to metastasis development
Authors: Sleeman Jonathan P. , Nazarenko Irina , Thiele Wilko
Published: March 2011

Metastasis, the life‐threatening aspect of cancer, is a systemic disease process. Considerable progress has been made in recent years regarding how tumor cells circulating in the blood and lymphatic systems interact with and extravasate into secondary sites, and what determines whether these disseminated tumors cells survive, remain dormant or go on to form macrometastases. New insights into the routes that tumor cells take once leaving the primary tumor have emerged. Novel concepts regarding early seeding of metastases coupled to parallel progression, self‐seeding of primary tumors by circulating tumor cells and the induction of premetastatic niches in distant organs by primary tumors have come to the fore. The perceived role of the lymphatic system in determining patterns of metastasis formation in distant organs has been reassessed. Together these new insights have the potential to offer new therapeutic options. In particular, the regulation of tumor cell dormancy emerges as a key event in metastasis formation, and therapeutic control of dormancy holds the promise of rendering cancer a chronic rather than life‐threatening disease.
BRACHYURY confers cancer stem cell characteristics on colorectal cancer cells
Authors: Sarkar Debalina , Shields Brian , Davies Melanie L. , Müller Jürgen , Wakeman Jane A.
Published: March 2011

Cancer stem cells (CSCs) are initiating cells in colorectal cancer (CRC). Colorectal tumours undergo epithelial to mesenchymal transition (EMT)‐like processes at the invasive front, enabling invasion and metastasis, and recent studies have linked this process to the acquisition of stem cell‐like properties. It is of fundamental importance to understand the molecular events leading to the establishment of cancer initiating cells and how these mechanisms relate to cellular transitions during tumourigenesis. We use an in vitro system to recapitulate changes in CRC cells at the invasive front (mesenchymal‐like cells) and central mass (epithelial‐like cells) of tumours. We show that the mesoderm inducer BRACHYURY is expressed in a subpopulation of CRC cells that resemble invasive front mesenchymal‐like cells, where it acts to impose characteristics of CSCs in a fully reversible manner, suggesting reversible formation and modulation of such cells. BRACHYURY, itself regulated by the oncogene β‐catenin, influences NANOG and other ‘stemness’ markers including a panel of markers defining CRC‐CSC whose presence has been linked to poor patient prognosis. Similar regulation of NANOG through BRACHYURY was observed in other cells lines, suggesting this might be a pathway common to cancer cells undergoing mesenchymal transition. We suggest that BRACHYURY may regulate NANOG in mesenchymal‐like CRC cells to impose a ‘plastic‐state’, allowing competence of cells to respond to signals prompting invasion or metastasis.
Optimization of a molecular mechanics force field for type‐II polyoxometalates focussing on electrostatic interactions: A case study
Authors: Courcot Blandine , Bridgeman Adam J.
Published: March 2011

In this study, we have focussed on type‐II polyanions such as [M7O24]6−, and we have developed and validated optimized force fields that include electrostatic and van der Waals interactions. These contributions to the total steric energy are described by the nonbonded term, which encompasses all interactions between atoms that are not transmitted through the bonds. A first validation of a stochastic technique based on genetic algorithms was previously made for the optimization of force fields dedicated to type‐I polyoxometalates. To describe the new nonbonded term added in the functional, a fixed‐charged model was chosen. Therefore, one of the main issues was to analyze that which partial atomic charges could be reliably used to describe these interactions in such inorganic compounds. Based on several computational strategies, molecular mechanics (MM) force field parameters were optimized using different types of atomic charges. Moreover, the influence of the electrostatic and van der Waals buffering constants and 1,4‐interactions scaling factors used in the force field were also tested, either being optimized as well or fixed with respect to the values of CHARMM force field. Results show that some atomic charges are not well adapted to CHARMM parameters and lead to unrealistic MM‐optimized structures or a MM divergence. As a result, a new scaling factor has been optimized for Quantum Theory of Atoms in Molecules charges and charges derived from the electrostatic potential such as ChelpG. The force fields optimized can be mixed with the CHARMM force field, without changing it, to study for the first time hepta‐anions interacting with organic molecules. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Force fields for metallic clusters and nanoparticles
Authors: Legenski Nicole , Zhou Chenggang , Zhang Qingfan , Han Bo , Wu Jinping , Chen Liang , Cheng Hansong , Forrey Robert C.
Published: March 2011

Atomic force fields for simulating copper, silver, and gold clusters and nanoparticles are developed. Potential energy functions are obtained for both monatomic and binary metallic systems using an embedded atom method. Many cluster configurations of varying size and shape are used to constrain the parametrization for each system. Binding energies for these training clusters were computed using density functional theory (DFT) with the Perdew‐Wang exchange‐correlation functional in the generalized gradients approximation. Extensive testing shows that the many‐body potentials are able to reproduce the DFT energies for most of the structures that were included in the training set. The force fields were used to calculate surface energies, buk structures, and thermodynamic properties. The results are in good agreement with the DFT values and consistent with the available experimental data. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Rate constants for hydrogen abstraction reactions by the hydroperoxyl radical from methanol, ethenol, acetaldehyde, toluene, and phenol
Authors: Altarawneh Mohammednoor , Al‐Muhtaseb Ala'A H. , Dlugogorski Bogdan Z. , Kennedy Eric M. , Mackie John C.
Published: March 2011

An important step in the initial oxidation of hydrocarbons at low to intermediate temperatures is the abstraction of H by hydroperoxyl radical (HO2). In this study, we calculate energy profiles for the sequence: reactant + HO2 → [complex of reactants] → transition state → [complex of products] → product + H2O2 for methanol, ethenol (i.e., C2H3OH), acetaldehyde, toluene, and phenol. Rate constants are provided in the simple Arrhenius form. Reasonable agreement was obtained with the limited literature data available for acetaldehyde and toluene. Addition of HO2 to the various distinct sites in phenol is investigated. Direct abstraction of the hydroxyl H was found to dominate over HO2 addition to the ring. The results presented herein should be useful in modeling the lower temperature oxidation of the five compounds considered, especially at low temperature where the HO2 is expected to exist at reactive levels. © 2011 Wiley Periodicals, Inc. J Comput Chem 2011
Accurate macromodeling algorithm for time domain identification of transient port responses
Authors: Deschrijver D. , Dhaene T.
Published: March 2011

Orthonormal vector fitting is a robust method for broadband macromodeling of frequency domain responses. The use of orthonormal rational basis functions makes the conditioning of the system equations less sensitive to the initial pole specification when compared with the classical Vector Fitting procedure. This paper presents a time domain generalization of the technique to compute broadband rational macromodels from transient input–output port responses. The efficacy of the approach is illustrated by two numerical examples. Copyright © 2011 John Wiley & Sons, Ltd.
Phase transitions in Pb8O5(XO4)2 (X = As and V) compounds
Authors: Oliveira E. A. , Silva E. N. , Paschoal A. R. , Dantas S. M. , Guedes I. , Mendes‐Filho J. , Polla G. , Ayala A. P.
Published: March 2011

Raman spectroscopy, polarized microscopy and thermal measurements were used to investigate the sequence of phase transition in the lead oxide salts Pb8O5(XO4)2 (where X = As and V). For Pb8O5(AsO4)2, a second‐order phase transition is observed at 500 K. For Pb8O5(VO4)2, a second‐order and a first‐order structural phase transitions are observed at 425 and 525 K, respectively. The ferroelastic character of Pb8O5(VO4)2 is also discussed. Copyright © 2011 John Wiley & Sons, Ltd.
A highly efficient and versatile microchip capillary electrophoresis method for DNA separation using gold nanoparticle as a tag
Authors: Cao Wei , Chen Lei , Fu Youjian , Tan Zhenyi , Qu Bin
Published: March 2011

A highly efficient and versatile method for DNA separation using Au nanoparticles (Au NPs) as a tag based on microchip capillary electrophoresis (MCE) was developed. The thiol‐modified DNA‐binding Au NPs were utilized as a tag. Target DNA was sandwiched between Au NPs and probe DNA labeled with horseradish peroxidase (HRP). In electrophoresis separation, the difference in electrophoretic mobility between free probe and probe‐target complex was magnified by Au NPs, which enabled the resulting mixture to be separated with high efficiency by microchip capillary electrophoresis. Horseradish peroxidase was used as a catalytic label to achieve sensitive electrochemical DNA detection via fast catalytic reactions. With this protocol, 27‐mer DNA fragments with different sequences were separated with high speed and high resolution. The proposed method was critical to achieve improved DNA separations in hybridization analyses.
Fluorinated FeF3 catalyst interactions in three different oil formulations using design of experiment optimization and chemistry characterization of tribofilms
Authors: Nehme Gabi
Published: March 2011

The influence of fluorinated FeF3 catalyst on the formation and properties of tribofilms was examined using design of experiment (DOE) under extreme boundary lubrication (385 N or maximum Hertzian contact pressure of 2.72 GPa). A closed loop boundary condition test was developed to examine the behaviour of lubricants under boundary conditions. The reduction of phosphorus in engine oil was examined using two different plain oils and one fully formulated oil. Results indicate the formation of a thicker tribofilm in plain fluorinated oil when compared with fluorinated fully formulated oils.

Several chemistry combinations were prepared and tested. Wear and frictional properties were evaluated using DOE, and the interactions of fluorinated FeF3 catalyst with minimum phosphorus were studied and compared with respect to fully formulated and plain zinc dialkyl dithiophosphate oils. Tribofilms with thickness ranging from 150 to 350 nm were developed during wear tests and were analysed for fluorinated plain and fully formulated oils that target reducing phosphorus. Three specific tests with optimised 0.6% FeF3 catalyst concentrations were used with 0.05% phosphorus in plain and fully formulated oil to verify the model optimised conditions with respect to wear and time to full break down. Scanning electron microscopy, hardness of the tribofilms and Auger spectroscopy confirm the presence of fluorine and phosphorus. These tests confirm the optimised prediction of the DOE model. Copyright © 2011 John Wiley & Sons, Ltd.
Addressing the Conformational Flexibility of Serine Racemase by Combining Targeted Molecular Dynamics, Conformational Sampling and Docking Studies
Authors: Bruno Agostino , Amori Laura , Costantino Gabriele
Published: March 2011

Serine racemase (SR) is a PLP‐dependent enzyme catalyzing the racemization of L‐Ser into D‐Ser, which is now recognized as an endogenous co‐agonist at the NMDA receptor complex. As indicated by available X‐ray structures, SR undergoes significant conformational changes during ligand recognition, and it is conceivable that, in addition to the reported X‐ray structures, other intermediate conformational states may have relevance in drug discovery studies. Targeted molecular dynamics (TMD) simulations are an effective tools to follow the conformational transition of a protein under the constrain of reaching a known target states. In this study we use TMD to simulate the transition between the open and closed form of SR in the presence of the endogenous substrate or an orthosteric inhibitor. The trajectories thus obtained are then clustered to collect an ensemble of intermediate conformational states. Docking of a small library of known SR inhibitors or closely related inactive analogs demonstrates that ensemble docking performs better than docking on available crystal structures, thus indicating that inclusion of conformational flexibility into ligand design strategies will be crucial for the development of new classes of SR inhibitors.