bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystal Structure, Phase Transition, and Thermodynamic Properties of Bis‐dodecylammonium Tetrachlorozincate (C12H25NH3)2ZnCl4(s)
Authors: Kong Yuxia , Di Youying , Yang Weiwei , Lü Yinfeng , Tan Zhicheng
Published: April 2010

The crystal structure and composition of (C12H25NH3)2ZnCl4(s) were characterized by chemical and elemental analysis, X‐ray powder diffraction technique and X‐ray crystallography. The lattice energy of the title compound was calculated to beUPOT=888.82 kJ·mol−1. Low temperature heat capacities of the title compound have been measured by a precision automated adiabatic calorimeter over the temperature range from 80 to 403 K. An obvious solid to solid phase transition occurred in the heat capacity curve, and the peak temperature, molar enthalpy and molar entropy of the phase transition of the compound were determined to beTtrs= (364.02±0.03) K, (trsHm= (77.567±0.341) kJ·mol−1, and (trsSm= (213.77±1.17) J·K−1·mol−1, respectively. Experimental molar heat capacities before and after the phase transition were respectively fitted to two polynomial equations. The smoothed molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at an interval of 5 K.
DFT Investigation of Nuclear 14N Quadrupole Coupling Constants for Four HMX Polymorphs
Authors: Shi Liangwei , Wu Wenming , Qin Guangming , Lü Jian , Chen Minbo , Zhao Gang
Published: April 2010

Density functional theory investigation of 14N nuclear quadrupole coupling constants (NQCC) for HMX polymorphs was performed. During the calculation of NQCC and asymmetry parameter (η) of β‐HMX, single molecule model is found to be worse than cluster model. The calculated results are more sensitive to the proper model than to the basis set. The calculation for β‐HMX using cluster model at B3LYP/6‐311++G(d,p) level gives better agreement with experiment. This approach was subsequently applied to α, γ, and δ‐HMXs. The difference of simulated 14N NQR frequency was found. The NQR spectrum is useful for the study of explosive or propellant on their detection, phase transition, and aging process.
Protein Fractionation of Cowpea (Vigna unguiculata (L.) Walp) Leaf, Flower and Seed by Capillary Electrophoresis and Its Potential for Variety Identification
Authors: Siriamornpun Sirithon , Kaisoon Onanong , Sinsiri Wantana , Sinsiri Naris , Meeso Naret
Published: April 2010

The proteins of different faction of cowpea [Vigna unguiculata (L.) Walp] were fractionated by capillary electrophoresis (CE). The extracting solvent system was one of the most critical factors in the optimization exercise. To improve reproducibility, seed samples needed to be defatted with chloroform/methanol (V:V=2:1) as preferred prior to protein extraction. Proteins were extracted from seeds, leaves and flowers with 50% aqueous 1‐propanol and separated on a 50 (m×20 cm fused silica capillary column using a UV detector at 200 nm. Separation was conducted at constant voltage (10 kV, 40°C), using iminodiacetic acid (pH 2.5) containing 0.05% hydroxypropylmethylcellulose (HPMC) and 20% acetonitile. The results showed that proteins extracted from all fraction of cowpea were successfully separated by CE in less than 20 min. Seed extracts provided the greatest number of eluted protein peaks, followed by flower and leaf, respectively. The seed‐protein extracts provided unique CE patterns for different varieties; hence the seed was the tissue chosen as being most suitable for variety identification. As a result, an optimized procedure was developed to provide rapid identification of cowpea varieties, based on capillary electrophoregram patterns.
Synthesis and Biological Activity of 4‐Hydroxy‐3‐(1,5‐diaryl‐3‐ oxo‐pent‐4‐enyl)chromen‐2‐ones
Authors: Jadhav Mohan R. , Shinde Devanand B.
Published: April 2010

The substituted warfarin acid chalcones have been prepared by condensation of warfarin acid and aromatic/aliphatic aldehyde using aq. NaOH as catalyst. The method is simple, cost‐effective and gives good yield in a short reaction time. All the compounds synthesized have been characterized by IR, NMR and Mass spectra. A new series of 4‐hydroxy‐3‐(3‐oxo‐1,5‐diaryl‐3‐oxo‐pent‐4‐enyl)‐chromen‐2‐ones were synthesized and submitted to biological activity. Result of the biological screening showed the compounds 3b, 3h being the most effective among the various treatments in antimicrobial screening. Compounds 3c, 3d, 3k and 3l showed moderate activity against the microorganisms tested. Compounds 3e, 3h have shown good antifungal activity.
Rapid Separation of Proteins by Capillary HPLC on a Short Polymethacrylate‐based Strong Cation‐exchange Monolithic Column
Authors: Ding Mingyu , Wang Zonghua , Zheng Rui
Published: April 2010

A polymethacrylate‐based strong cation‐exchange capillary monolithic column was prepared by in‐situ copolymerization for the fast separation of proteins. Glycidyl methacrylate (GMA) was used as monomer, ethylenedimethacrylate (EDMA) as cross link agent and the mixture of 1‐propanol, 1,4‐butanediol and water as porogen solvent. The monolith was sulfonated using 1 mol/L Na2SO3 based on a ring opening of epoxides. The influences of the contents of the porogen solvent and GMA and the various concentration ratios of 1‐propanol to 1,4‐butanediol in the polymerization mixture on the morphology, porosity, globule size, stability and column efficiency were investigated. The morphology and pore size distribution of the monolith were characterized by SEM and mercury intrusion porosimetry, respectively. Using only 1.5 cm length of this monolithic capillary column, four kinds of proteins, trypsin, cytochrome C, lysozyme (egg white) and egg albumin, were successfully separated from each other in 5 min at a high flow rate of 110 mm/s.
Removal and Recovery of UO2(??) from Water Samples Using 2,2′‐Diamino‐4,4′‐bithiazole as a New Reagent for Solid Phase Extraction
Authors: Soleimani Majid , Khani Azam
Published: April 2010

A novel sensitive and simple method for rapid and selective extraction, preconcentration and determination of uranyl as its 2,2′‐diamino‐4,4′‐bithiazole (DABTZ) complex by using octadecylsilica columns and spectrophotometry is presented. Extraction efficiency and the influence of flow rates of sample solution and eluent, pH, amount of DABTZ, type and least amount of eluent for elution of uranyl complex from columns, break‐through volume and limit of detection were evaluated. Also the effects of various cationic and anionic interferences on percent recovery of uranyl were studied. Average extraction efficiency of ca. 90% was obtained by elution of the column with minimal amount of solvent in the presence of interferences. The average preconcentration factor, 136 and a detection limit 0.32 ng·mL−1 were obtained. The method was applied to the recovery and determination of uranyl in different water samples.
Allylation of Carbonyl Compounds Mediated by Aluminum/Fluoride Salts in Water
Authors: Yuan Shizhen , Liu Jin , Xu Ling , Zhu Shaofeng
Published: April 2010

A novel mediator (Al/KF) has been developed and employed in the Barbier‐type alkylations of various aldehydes and ketones with alkyl halide in water. The carbonyl compounds could be effectively converted into corresponding homoallylic alcohol in good yields only when allyl bromides or substituted allyl bromides were used as halides. Aromatic aldehydes could afford homoallylic alcohols in high yields, unfortunately, the allylation of aromatic aldehyde substituted by nitro‐ or amino‐group could not proceed smoothly, and the allylation yields of ketones and aliphatic carbonyl compounds were lower under the same condition. The diastereoselectivity and regioseletivity of the reaction have also been studied, the predominant products preferred the erythro‐ or anti‐isomer in dominant γ‐adduct by using Al/KF mediated allylation of benzaldehydes with cinnamyl bromide and ethyl 4‐bromo‐2‐butenoate in water.
Synthesis of Biologically Active [4‐(4‐Bromophenyl)‐2‐thiazolyl]hydrazones and their D‐Galactose Derivatives
Authors: Ramadan El Sayed
Published: April 2010

Benzaldehyde [4‐(4‐bromophenyl)thiazol‐2‐yl]hydrazones 5a–5d were prepared by reacting the thiosemicarbazones 2a–2d with 2,4′‐dibromoacetophenone (1) in absolute ethanol. Acetylation of 5a and 5b with Ac2O/Py at room temperature gave the N‐acetyl derivatives 6a and 6b. 4‐Methyl‐2‐pentanone/cyclopentanone [4‐(4‐bromo‐phenyl)thiazol‐2‐yl]hydrazones (8a) and (8b) were similarly obtained from the reaction of 1 with the thiosemicarbazones 7a and 7b, respectively. Cyclization of D‐galactose thiosemicarbazone (9) and its tautomers 10 and 11 with 1 afforded an equilibrium mixture of the acyclic 2‐thiazolylhydrazone 12, together with its respective cyclic galactosyl derivatives 13 and 14, whose structures were studied by using 1H and 13C NMR spectra. The antimicrobial activity of the synthesized thiazole derivatives was evaluated in vitro by using an agar diffusion technique, and some of these compounds showed potential activity against Candida albicans.
Enantioselective Aldol Reaction of α‐Ketoester and Cyclopentaone Catalyzed by L‐Proline
Authors: Xiang Jiming , Li Baolin
Published: April 2010

A concise and enantioselective synthesis of (S)‐ethyl 2‐cyclopentyl‐2‐hydroxy‐2‐arylacetate, a key intermediate for the muscarinic receptor, is reported. The tertiary stereogenic center was constructed with good stereoselectivity through the L‐proline‐catalyzed direct asymmetric aldol reaction of ethyl arylglyoxylate and cyclopentanone. The carbonyl of the condensation product was reduced using a modified Clemmensen reaction which provided an easier workup and was more environmentally acceptable. The enantioselectivity of the aldol reactions was between 58.3%–93.2%, which means that the stereoselective is efficient in controlling configuration of reaction product.
Cholesterol‐substituted Tetrathiafulvalene (TTF) Compound: Formation of Organogel and Supramolecular Chirality
Authors: Wang Cheng , Sun Fei , Zhang Deqing , Zhang Guanxin , Zhu Daoben
Published: April 2010

A new tetrathiafulvalene (TTF) derivative with two cholesterol units (compound 1) was synthesized and characterized. Gelation of n‐hexane occurred after the hot solution of 1 was subjected to ultrasonic treatment for a few minutes. The resulting organogel was characterized with SEM, XRD and AFM. Besides heating the gel‐sol transition also occurred upon addition of I2 which can oxidize the TTF unit in 1. This result provides a new example of organogels responding to redox reactions. Interestingly, gelation‐induced CD signals were observed and the CD signals can be tuned with the gel‐sol transition which can be effected by heating and chemical reaction with I2.
Coupling Proteins to Amine‐terminated Magnetic Particles Activated with 1,4‐Phenylene Diisothiocyanate
Authors: Tang Yitong , Geng Tingting , Xin Xiaofang , Chen Chao , Cui Yali
Published: April 2010

The homobifunctional crosslinker 1,4‐phenylene diisothiocyanate (PDC) was coupled to amine‐terminated magnetic particles, and human IgG, streptavidin, protein G and protein A were immobilized on the activated magnetic particles. The coupling of PDC to the amine‐terminated magnetic particles was completed in 10 min, and 1 mg of activated magnetic particles was able to immobilize 95 (g of protein G, 120 µg of protein A, 160 µg of streptavidin and 280 µg of IgG. Ultraviolet‐visible spectroscopy, FTIR spectroscopy and electron micrography were used to characterize the functional particles. The results indicated that PDC was successfully coupled to the surface of the amine‐terminated magnetic particles, and the proteins were effectively immobilized on their surface. The activity of protein G immobilized on the activated magnetic particles was confirmed by its ability to purify IgG from plasma.
Dependence of Property of Silver Nanoparticles within Dendrimer‐template on Molar Ratios of Ag+ to PAMAM Dendrimers
Authors: Li Guoping , Luo Yunjun , Lu Wenting , Li Jie , Jin Yujuan , Guo Sufang
Published: April 2010

G5.0‐OH PAMAM dendrimers were used to prepare fluorescent silver clusters with weaker ultraviolet irradiation reduction method, in which the molar ratio of Ag+ to PAMAM dendrimers was the key factor to determine the geometry and properties of silver nanoparticles. The results showed that because of G5.0‐OH PAMAM dendrimers as strong encapsulatores, when the molar ratios of Ag+ to PAMAM dendrimers was smaller than 5, the obtained Agn clusters (n<5) had line structures and "molecular‐like" properties, which were highly fluorescent and quite stable in aqueous solution. Whereas when the molar ratios were between 5 and 8, the obtained Agn clusters were 2D structures and their fluorescence was weaker. When the molar ratio was larger than 8, the structure of silver nanoparticles was 3D and no fluorescence was observed from the obtained silver nanoparticles.
hytic Acid Conversion Coatings of Magnesium
Authors: Liu Jianrui , Guo Yina , Huang Weidong
Published: April 2010

A chrome‐free conversion coating treatment for magnesium by phytic acid solution was developed. The immersion experiments were used for evaluating the effects of the processing parameters (such as conversion temperature and time, concentration and pH value of phytic acid solution) on the corrosion resistance of the phytic acid conversion coating. The morphologies and compositions of the coatings were determined by SEM and EDS respectively. The experimental results indicated that the corrosion resistance of the conversion coating formed in the solution containing 0.5% phytic acid at 25°C and pH=4 for 30 min was higher than that of natural oxide, and the conversion coating formed on the surface of magnesium was of multilayer mainly consisting of Mg, C, O and P. The thicknesses of the conversion coatings were approximately 1.0–15 µm and the conversion coatings presented obvious network‐like cracks. The electrochemical potentiodynamic polarization experiment indicated that the free corrosion potential of the magnesium with phytic acid conversion coating was increased, and its corrosion current and corrosion rate declined in 3.5% NaCl solution. Phytic acid conversion coating could improve the electrochemical property of magnesium and provide effective protection, which can improve the corrosion resistance of magnesium.
Solid‐Phase Extraction of Metoprolol onto (Methacrylic acid‐ ethylene glycol dimethacrylate)‐based Molecularly Imprinted Polymer and Its Spectrophotometric Determination
Authors: Saber Tehrani Mohammad , Vardini Mohammad Taghi , Abroomand Azar Parviz , Husain Syed Waqif
Published: April 2010

A new adsorbent for molecularly imprinted solid phase extraction (MISPE) of metoprolol was synthesized using methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross‐linking agent causing a non‐covalent, bulk, thermal radical‐polymerization. Control polymer (non‐imprinted polymer) was prepared under well defined conditions without the use of metoprolol. The synthesized polymers were characterized by IR spectroscopy, X‐ray diffraction and thermal analysis techniques. This polymer was used for the rapid extraction and preconcentration of metoprolol from real samples prior to spectrophotometric determination. Extraction efficiency and the influence of flow rates of sample and stripping solutions, pH, type of eluent for elution of metoprolol from polymer, break through volume and limit of detection were studied. The detection limit of the proposed method is 0.4 ng·mL−1. The method was applied successfully to the recovery and determination of metoprolol in tablets, human urine and plasma samples.
Silica‐bonded S‐Sulfonic Acid: A Recyclable Catalyst for the Synthesis of Trisubstituted Imidazoles under Solvent‐free Conditions
Authors: Niknam Khodabakhsh , Mohammadizadeh Mohammad R. , Mirzaee Salimeh , Saberi Dariush
Published: April 2010

Trisubstituted imidazoles have been synthesized in high yields in the presence of silica‐bonded S‐sulfonic acid as a catalyst. The reaction was carried out at 130°C under solvent‐free conditions. The reaction work‐up is simple and the catalyst is easily separated from the products by filtration.
The Binding Mode of Side Chain‐ and C3‐Modified Epothilones to Tubulin
Authors: Erdélyi Máté , Navarro‐Vázquez Armando , Pfeiffer Bernhard , Kuzniewski Christian N. , Felser Andrea , Widmer Toni , Gertsch Jürg , Pera Benet , Díaz José Fernando , Altmann Karl‐Heinz , Carlomagno Teresa
Published: April 2010

The tubulin‐binding mode of C3‐ and C15‐modified analogues of epothilone A (Epo A) was determined by NMR spectroscopy and computational methods and compared with the existing structural models of tubulin‐bound natural Epo A. Only minor differences were observed in the conformation of the macrocycle between Epo A and the C3‐modified analogues investigated. In particular, 3‐deoxy‐ (compound 2) and 3‐deoxy‐2,3‐didehydro‐Epo A (3) were found to adopt similar conformations in the tubulin‐binding cleft as Epo A, thus indicating that the 3‐OH group is not essential for epothilones to assume their bioactive conformation. None of the available models of the tubulin–epothilone complex is able to fully recapitulate the differences in tubulin‐polymerizing activity and microtubule‐binding affinity between C20‐modified epothilones 6 (C20‐propyl), 7 (C20‐butyl), and 8 (C20‐hydroxypropyl). Based on the results of transferred NOE experiments in the presence of tubulin, the isomeric C15 quinoline‐based Epo B analogues 4 and 5 show very similar orientations of the side chain, irrespective of the position of the nitrogen atom in the quinoline ring. The quinoline side chain stacks on the imidazole moiety of β‐His227 with equal efficiency in both cases, thus suggesting that the aromatic side chain moiety in epothilones contributes to tubulin binding through strong van der Waals interactions with the protein rather than hydrogen bonding involving the heteroaromatic nitrogen atom. These conclusions are in line with existing tubulin polymerization and microtubule‐binding data for 4, 5, and Epo B.
Prognostic value of mucin 4 expression in colorectal adenocarcinomas
Authors: Shanmugam Chandrakumar , Jhala Nirag C. , Katkoori Venkat R. , Wan Wen , Meleth Sreelatha , Grizzle William E. , Manne Upender
Published: April 2010

BACKGROUND:

Mucin 4 (MUC4) is aberrantly expressed in colorectal adenocarcinomas (CRCs) but its prognostic value is unknown.

METHODS:

Archival tissue specimens collected from 132 CRC patients who underwent surgical resection without presurgery or postsurgery therapy were evaluated for expression of MUC4 by using a mouse monoclonal antibody and horseradish peroxidase. MUC4 expression levels were correlated with clinicopathologic features and patient survival. Survival was estimated by both univariate Kaplan‐Meier and multivariate Cox regression methods.

RESULTS:

In both normal colonic epithelium and CRCs, MUC4 staining was localized primarily in the cytoplasm. The optimal immunostaining cutoff value (≥75% positive cells and an immunostaining score ≥2.0), which was derived by using the bootstrap method, was used to categorize CRCs into groups of high expression (33 of 132 patients; 25%) or low expression (99 of 132 patients; 75%). Patients who had early stage tumors (stages I and II) with high MUC4 expression had a shorter disease‐specific survival (log‐rank;P= .007) than patients who had with low expression. Patients who had advanced‐stage CRCs (stages III and IV) did not demonstrate such a difference (log‐rank;P= .108). Multivariate regression models that were generated separately for patients with early stage and advanced‐stage CRC confirmed that increased expression of MUC4 was an independent indicator of a poor prognosis only for patients who had early stage CRCs (hazard ratio, 3.77; 95% confidence interval, 1.46‐9.73).

CONCLUSIONS:

The current results indicated that increased MUC4 expression is a predictor of poor survival in CRC, specifically for patients who have early stage tumors. Cancer 2010. © 2010 American Cancer Society.
A phase 1‐2 study of imexon plus dacarbazine in patients with unresectable metastatic melanoma
Authors: Weber Jeffrey S. , Samlowski Wolfram E. , Gonzalez Rene , Ribas Antoni , Stephenson Joe , O'Day Steven , Sato Takami , Dorr Robert , Grenier Kathryn , Hersh Evan
Published: April 2010

BACKGROUND:

Imexon (Amplimexon) is an aziridine compound that increases reactive oxygen species, disrupts mitochondrial membranes, and induces apoptosis. Preclinical studies showed activity against melanoma cell lines and models in mice, and synergy with dacarbazine. The authors evaluated standard doses of dacarbazine combined with increasing doses of imexon to determine the maximal tolerated dose (MTD), toxicities, pharmacokinetics, and efficacy.

METHODS:

Sixty‐eight chemotherapy‐naive melanoma patients (1 inoperable stage III and 67 stage IV) were treated with dacarbazine (250 mg/m2) and imexon (570‐1300 mg/m2), both daily for 5 days every 3 weeks.

RESULTS:

There were 18 patients in the phase 1, and 50 in the phase 2 component of the study. The MTD of imexon with dacarbazine was 1000 mg/m2. Dose‐limiting toxicities were pulmonary edema and hepatorenal failure. At the MTD, therapy was well tolerated. The most common toxicities (any grade) were vomiting, diarrhea, anemia, thrombocytopenia, anorexia, fever, and constipation. Among 68 patients, there were 7 treatment‐related serious adverse events. Partial response and stable disease rates were 5.9% and 25% for all subjects and 2% and 30% for the phase 2 patients, respectively. Median progression‐free and overall survival of all patients were 2.0 and 11.7 months and 2 and 7.5 months for the phase 2 patients, respectively. Overall survival of the 31 patients with normal lactate dehydrogenase levels was >22.5 months. Pharmacokinetics of both drugs were similar to previous reports.

CONCLUSIONS:

Imexon plus dacarbazine was well tolerated. The survival data suggest further evaluation in a randomized phase 2 study. Cancer 2010. © 2010 American Cancer Society.
The role of targeted agents in preoperative chemoradiation for rectal cancer
Authors: Wadlow Raymond C. , Ryan David P.
Published: April 2010

In the United States, randomized trials have established preoperative chemoradiation as the standard of care for patients with locally advanced rectal cancer. Pathologic complete response (pCR) rates occur in 10% to 16% of patients and have been shown to be correlated with both disease‐free and overall survival. Therefore, recent efforts incorporating newer cytotoxic and molecularly targeted agents into chemoradiotherapy regimens have reported the pCR rate to be a surrogate marker of clinical outcomes. Substitution of oral fluoropyrimidines, including capecitabine, for infusional 5‐fluorouracil reportedly generated pCR rates of up to 32% in phase 2 studies, but definitive evaluation awaits results from the National Surgical Adjuvant Breast and Bowel Project (NSABP) R‐04 trial. Similarly, regimens incorporating irinotecan generated pCR rates as high as 38%, but to the authors' knowledge have not been evaluated in randomized trials. In contrast, 2 large randomized trials reported that the addition of weekly oxaliplatin to fluoropyrimidine‐based chemoradiation led to an increase in grade 3/4 toxicity but no difference in pCR rates. Early phase trials evaluating the anti‐epidermal growth factor receptor (EGFR) antibody cetuximab in combination with chemoradiation reported modest pCR rates of 5% to 12%, and efforts have focused on identifying biomarkers of response including EGFR copy number, k‐ras mutational status, and both serum and tumor‐specific expression of EGFR ligands. Finally, incorporation of the anti‐vascular endothelial growth factor antibody bevacizumab into chemoradiation appears to be safe and feasible, with initial studies reporting a beneficial effect on vascular normalization and correlations between circulating biomarkers of angiogenesis and pathologic response. Future efforts should include prospective studies of these agents in biomarker‐defined subpopulations, as well as studies of novel agents that target angiogenesis, tumor‐stromal interaction, and the cell signaling pathways implicated in colorectal cancer. Cancer 2010. © 2010 American Cancer Society.
A tetrachromatic model for colorimetric use in mesopic vision
Authors: Polymeropoulos Grigorios , Bisketzis Nikolaos , Topalis Fragkiskos
Published: April 2010

In this article, a tetrachromatic colorimetric model is proposed. Four monochromatic stimuli are used as primaries instead of three to achieve colorimetric matches in mesopic vision. Tetrachromatic colorimetric matches are assumed in such a way so as to hold in both the photopic and the scotopic levels of adaptation. The fourth primary helps to balance the rod contribution in mesopic vision. The proposed model is based on the experimental observations that (a) trichromatic matches can be achieved in any light level and (b) once a tetrachromatic match is made, it holds at all radiances. The main outcome is that (a) only three channels in human vision system are important for color matching at mesopic and photopic levels and (b) additivity can be preserved at all levels once rod input is taken into account. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011
Color emotions for multi‐colored images
Authors: Solli Martin , Lenz Reiner
Published: April 2010

We investigate the emotional response to colors in ordinary multicolored images. In psychophysical experiments, using both category scaling and interval scaling, observers are asked to judge images using three emotion factors: activity, weight, and heat. The color emotion metric was originally developed for single colors, and later extended to include pairs of colors. The same metric was recently used in image retrieval. The results show that people in general perceive color emotions for multi‐colored images in similar ways, and that observer judgments correlate with the recently proposed method used in image retrieval. The intended usage is in retrieval systems publicly available on the Internet, where both the user and the viewing environment is unknown, which requires novel ways of conducting the psychophysical experiments. © 2010 Wiley Periodicals, Inc. Col Res Appl, 36, 210–221, 2011;
Goniocolorimetry: From measurement to representation in the CIELAB color space
Authors: Simonot Lionel , Hébert Mathieu , Dupraz Damien
Published: April 2010

The classical definitions of color are well adapted to diffusing objects, whose color is almost independent of the viewing angle, and to very glossy object observed in the specular direction in respect to the light source. For glossy or iridescent objects, the color is difficult to characterize due to its dependence on the viewing direction. In order to cope with such objects and to represent their angle‐dependent colors in a colorimetric space, we adapt the CIELAB space to “goniocolorimetric” measurements. A crucial point when defining this space is the statement of the viewing solid angle. First, we suggest performing a BRDF measurement at high angular resolution in order to characterize the gloss of the specimen. Then, since for the definition of colors the CIE recommends cones of half‐angle of 2° or 10°, we propose to convert the measured BRDF into a reflectance factor defined in respect to these solid angles. This procedure is eased by a planar multispectral image of the BRDF, where solid angles are specified by the pixel size. At last, the reflectance factors are converted into CIELAB coordinates. By using this procedure, the perfect white diffuser but also the perfect mirror can be represented in this colorimetric space. © 2010 Wiley Periodicals, Inc. Col Res Appl, 36, 169–178, 2011;
SmartGridRPC: The new RPC model for high performance Grid computing
Authors: Brady Thomas , Dongarra Jack , Guidolin Michele , Lastovetsky Alexey , Seymour Keith
Published: April 2010

The paper presents the SmartGridRPC model, an extension of the GridRPC model, which aims to achieve higher performance. The traditional GridRPC provides a programming model and API for mapping individual tasks of an application in a distributed Grid environment, which is based on the client‐server model characterized by the star network topology. SmartGridRPC provides a programming model and API for mapping a group of tasks of an application in a distributed Grid environment, which is based on the fully connected network topology. The SmartGridRPC programming model and API and its performance advantages over the GridRPC model are outlined in this paper. In addition, experimental results using a real‐world application are also presented. Copyright © 2010 John Wiley & Sons, Ltd.
Low‐voltage bulk‐driven input stage with improved transconductance
Authors: Raikos George , Vlassis Spyridon
Published: April 2010

A low‐voltage input stage constructed from bulk‐driven PMOS transistors is proposed in this paper. It is based on a partial positive feedback and offers significant improvement of both input transconductance and noise performance compared with those achieved by the corresponding already published bulk‐driven structures. The proposed input stage offers also extended input common‐mode range under low supply voltage in relevant to a gate‐driven differential pair. A differential amplifier based on the proposed input stage is also designed, which includes an auxiliary amplifier for the output common‐mode voltage stabilization and a latch‐up protection circuitry. Both input stage and amplifier circuits were implemented with 1 V supply voltage using standard 0.35µm CMOS process, and their performance evaluation gave very promising results. Copyright © 2010 John Wiley & Sons, Ltd.
CMOL implementation of spiking neurons and spike‐timing dependent plasticity
Authors: Afifi Ahmad , Ayatollahi Ahmad , Raissi Farshid
Published: April 2010

Successful implementation of spiking neural networks onto CMOS‐Molecular (CMOL) architecture has already been proposed, but the ability of dynamic learning has not yet been addressed. Here, we propose a spiking neural topology with spike‐timing‐dependent learning ability and provide its basic building blocks that are easily mapped onto CMOL architecture. The learning method modifies state of synaptic switches, using spatially and temporally local information which is available at the synapse when state modification is performed.

The performance of the proposed topology is analyzed with regards to pre‐ and post‐synaptic spike timing, and simulation results are provided for a synapse with spike‐timing‐dependent plasticity properties. Furthermore, its performance as spike‐timing correlation learning and synchrony detection in a small feed‐forward network is demonstrated as a case example. Copyright © 2010 John Wiley & Sons, Ltd.
A high‐input‐voltage backlight module driver for multi‐lamp LCD panels
Authors: Lo Yu‐Kang , Pai Kai‐Jun , Wu Kuan‐Hung , Chiu Huang‐Jen
Published: April 2010

A half‐bridge (HB) resonant inverter for driving a backlight module with multiple cold cathode fluorescent lamps (CCFLs) is proposed. Conventionally, a backlight module driving inverter is designed to operate with a low‐input DC voltage. Therefore, a buck converter is required to step down the high‐output DC voltage of a power factor correction (PFC) pre‐regulator. The circuit cost is high and the conversion efficiency is low. In this letter, a high‐input‐voltage HB resonant inverter with only one transformer is used to drive multiple lamps. Analysis and design considerations are discussed in detail. Simulations and experimental results are close to the theoretical prediction. Copyright © 2010 John Wiley & Sons, Ltd.
A low‐power small‐area 10‐bit analog‐to‐digital converter for neural recording applications
Authors: Zarifi Mohammad Hossein , Frounchi Javad , Tinati Mohammad Ali , Farshchi Shahin , Judy Jack W.
Published: April 2010

In vivo neural recording systems require low power and small area, which are the most important parameters in such systems. This paper reports a new architecture for reducing the power dissipation and area, in analog‐to‐digital converters (ADCs). A time‐based approach is used for the subtraction and amplification in conjunction with a current‐mode algorithm and cyclical stage, which the conversion reuses a single stage for three times, to perform analog‐to‐digital conversion. Based on introduced structure, a 10‐bit 100‐kSample/s time‐based cyclical ADC has been designed and simulated in a standard 90‐nm Complementary Metal Oxide Semiconductor (CMOS) process. Design of the system‐level architecture and the circuits was driven by stringent power constraints for small implantable devices. Simulation results show that the ADC achieves a peak signal‐to‐noise and distortion ratio (SNDR) of 59.6 dB, an effective number of bits (ENOB) of 9.6, a total harmonic distortion (THD) of −64dB, and a peak integral nonlinearity (INL) of 0.55, related to the least significant bit (LSB). The ADC active area occupies 280µm × 250µm. The total power dissipation is 5µW per conversion stage and 20µW from an 1.2‐V supply for full‐scale conversion. Copyright © 2010 John Wiley & Sons, Ltd.
A study of superharmonic injection locking in multiband frequency dividers
Authors: Plessas F.
Published: April 2010

A superharmonic voltage‐controlled injection‐locked frequency divider, implemented using a modified Colpitts oscillator operating at 2.5, 5 and 10 GHz and a cross‐coupled LC oscillator operating at 1.25, 2.5 and 5 GHz, is demonstrated. The proposed triple‐band operation is achieved by employing a novel technique that uses pin‐diodes and negative power supply. The discrete dividers, built with low noise hetero‐junction FETs and high‐frequency SiGe BJTs, are described theoretically while their functionality is proven experimentally. Additionally, a short phase noise analysis, which is missing in the literature, is given. Phase noise, frequency range of operation, and locking range measurement results are presented. Finally, post‐layout simulation results of a 5 GHz fully differential injection‐locked frequency divider, implemented in a 0.25µm SiGe process are provided. Copyright © 2010 John Wiley & Sons, Ltd.
CMOS‐controlled inverting CDBA with a new all‐pass filter application
Authors: Metin Bilgin , Pal Kirat , Cicekoglu Oguzhan
Published: April 2010

In this study, new active elements called inverting current differencing buffered amplifier (ICDBA) and current‐controlled ICDBA (C‐ICDBA) are presented. Unlike current differencing buffered amplifier (CDBA), their voltage transfer ratio between the Z and W terminals are equal to minus one. Furthermore, CMOS implementations of the C‐ICDBA and current‐controlled CDBA (C‐CDBA) are shown. Moreover, a novel first‐order all‐pass filter is proposed to show advantages and new circuit producing capability of the ICDBA/C‐ICDBA. Lastly, an electronically tunable band‐pass filter is given as an application example using the presented all‐pass filter. The measured and simulation results are in good agreement with the theoretical ones. Copyright © 2010 John Wiley & Sons, Ltd.
A novel single‐stage AC–DC converter with quasi‐resonant zero‐voltage‐switching for high power factor and high efficient applications
Authors: Kim Myung‐Bok , Park Ki‐Bum , Youn Myung‐Joong
Published: April 2010

A new single‐stage‐isolated ac–dc converter that can guarantee both high efficiency and high power factor is proposed. It is based on a new dc–dc topology that has prominent conversion ratio similar to that of boost topology so that it is adequate to deal with the universal ac input. In addition, since it utilizes the transformer more than others based on the general flyback topology, the size of whole power system can be reduced due to the reduced transformer. Moreover, the voltage stresses on the secondary rectifiers can be clamped to the output voltage by adopting the capacitive output filter and clamp diode, and the turn‐off loss in the main switch can be reduced by utilizing the resonance. Furthermore, since this converter operates at the boundary conduction mode, the line input current can be shaped as the waveform of a line voltage automatically and the quasi‐resonant zero‐voltage switching can be obtained. Consequently, it features higher efficiency, lower voltage stress, and smaller sized transformer than other topologies. A 100 W prototype has been built and tested as the validation of the proposed topology. Copyright © 2010 John Wiley & Sons, Ltd.
Recursive wideband digital integrator and differentiator
Authors: Gupta Maneesha , Jain Madhu , Kumar B.
Published: April 2010

In this paper a novel wideband recursive digital integrator and differentiator is presented. The integrator is obtained by interpolating three digital integration techniques and the new differentiator is obtained by modifying its transfer function appropriately. Both the integrator and the differentiator are of third order and highly accurate, thus suitable for real‐time applications. Copyright © 2010 John Wiley & Sons, Ltd.
A unified set‐theoretic approach to the analysis of PWL resistive circuits and composite N‐ports
Authors: Pastore Stefano , Premoli Amedeo
Published: April 2010

We consider the search for all DC solutions of resistive piecewise‐linear (PWL) circuits and the analysis of the characteristics of resistive PWL compositeN‐ports. These problems are unified from a theoretical and operating point of view by introducing the so‐calledN‐augmented circuit, obtained from theN‐port by closing its ports withNnorators. Set‐theoretic approach is used to describe the properties of theN‐augmented circuits leading to the formulation of a general DC analysis algorithm, based on linear programming techniques. The examples at the end of the paper show some practical and efficient application of the general DC analysis algorithm. Copyright © 2010 John Wiley & Sons, Ltd.
Robust current control for boost PFC converters from a sliding mode viewpoint
Authors: Chu Grace , Tan Siew‐Chong , Tse Chi K. , Wong Siu Chung
Published: April 2010

In this paper, we propose a methodology to derive a pulse‐width modulation (PWM) control for the inner current loop of the boost power factor correction (PFC) converter. The methodology is based on the general sliding mode control theory. It leads to a robust current control that achieves accurate input current tracking under all practical conditions. The design of the control parameters is also presented, which is based on the existence condition and the frequency response analysis. The derived control can be implemented in analog circuitries as an application‐specific controller or as an add‐on feedforward control embedded in standard PFC controller circuits. Copyright © 2010 John Wiley & Sons, Ltd.
Pathological representation of the two‐output CCII and ICCII family and application
Authors: Soliman Ahmed M.
Published: April 2010

The pathological mirror and nullor representation of the two‐output current conveyor family is given. New pathological mirror and nullor representations of the two‐output current conveyor family are given and compared with the corresponding nullator norator resistors' realizations. Simplified representations of the two‐output current conveyors based on using two single‐output current conveyors are given. Two examples are given, the first example demonstrates the importance of the pathological representation in the generation of a family of 16 oscillators from a two‐output current conveyor‐based current mode oscillator. A second example of a current mode low‐pass filter using two single‐output inverting current conveyors is considered. Its simplified modeling using a single balanced output inverting current conveyor is compared with the original current mode filter and the simulation results are given. Copyright © 2010 John Wiley & Sons, Ltd.
Generation and classification of CCII and ICCII based negative impedance converter circuits using NAM expansion
Authors: Soliman Ahmed M.
Published: April 2010

A new simplified generation method of negative impedance converter circuits (NIC) is introduced. The generation method is based on nodal admittance matrix expansion starting from the input admittance of the NIC circuit terminated by a load rather than treating the NIC as a two‐port network element. The four pathological elements, namely nullator, norator, voltage mirror and current mirror, are used in the generation procedure. Two classes of the NIC pathological circuits are defined; each class includes two types. Eight pathological NIC circuits are generated for each class. Two alternative current conveyor and inverting current conveyor‐based realizations for each pathological circuit based on alternative pairing of the pathological elements are defined resulting in a total of 16 NIC circuit for each class and a total of 32 NIC circuits. A new NIC‐based circuits realizing floating negative impedances are also introduced. Copyright © 2010 John Wiley & Sons, Ltd.
An optimal approach to synchronize non‐identical chaotic circuits: An experimental study
Authors: Naseh Majid Reza , Haeri Mohammad
Published: April 2010

The control signal magnitude and energy are among the limiting and therefore important factors to be addressed in the practical applications of a synchronization scheme. In this paper, we present an algorithm to find control parameters in an active sliding mode controller in order to reduce the control effort in synchronizing non‐identical chaotic systems. We also determine uncertainties bound on the systems dynamics for which the calculated control parameters still guarantee the occurrence of the sliding motion of the error states. The proposed controller was practically applied on an experimental setup, consisting of two chaotic circuits, which resembles Chen and Lu systems behavior. Experimental results confirm our theoretical reasoning as well as the effectiveness of the proposed control design technique. Copyright © 2010 John Wiley & Sons, Ltd.
Comparison between models predicting the evolution of the electrical impedance with frequency
Authors: Kluyskens V. , Dehez B.
Published: April 2010

This paper explains and compares different models describing the evolution of the impedance of complex shaped conductors with low and with high frequencies. Indeed, at low frequencies, the evolution of the impedance of conductors with the frequency is negligible whereas at high frequencies, it is quite significant and generally well‐known. Parameterized models, based on the diffusion equation or on phenomenological approaches, are applied on complex shaped conductors, with a variable or not section. The parameters are found by identification with finite elements models. It is shown that simple phenomenological approaches gives accurate models with few parameters. Copyright © 2010 John Wiley & Sons, Ltd.
2D operators on topographic and non‐topographic architectures—implementation, efficiency analysis, and architecture selection methodology
Authors: Zarándy Ákos , Rekeczky Csaba
Published: April 2010

Topographic and non‐topographic image processing architectures and chips, developed within the CNN community recently, are analyzed and compared. It is achieved on a way that the 2D operators are collected to classes according to their implementation methods on the different architectures, and the main implementation parameters of the different operator classes are compared. Based on the results, an efficient architecture selection methodology is formalized. Copyright © 2010 John Wiley & Sons, Ltd.
Prolonged maturation of auditory perception and learning in gerbils
Authors: Sarro Emma C. , Sanes Dan H.
Published: April 2010

In humans, auditory perception reaches maturity over a broad age range, extending through adolescence. Despite this slow maturation, children are considered to be outstanding learners, suggesting that immature perceptual skills might actually be advantageous to improvement on an acoustic task as a result of training (perceptual learning). Previous non‐human studies have not employed an identical task when comparing perceptual performance of young and mature subjects, making it difficult to assess learning. Here, we used an identical procedure on juvenile and adult gerbils to examine the perception of amplitude modulation (AM), a stimulus feature that is an important component of most natural sounds. On average, Adult animals could detect smaller fluctuations in amplitude (i.e., smaller modulation depths) than Juveniles, indicating immature perceptual skills in Juveniles. However, the population variance was much greater for Juveniles, a few animals displaying adult‐like AM detection. To determine whether immature perceptual skills facilitated learning, we compared naïve performance on the AM detection task with the amount of improvement following additional training. The amount of improvement in Adults correlated with naïve performance: those with the poorest naïve performance improved the most. In contrast, the naïve performance of Juveniles did not predict the amount of learning. Those Juveniles with immature AM detection thresholds did not display greater learning than Adults. Furthermore, for several of the Juveniles with adult‐like thresholds, AM detection deteriorated with repeated testing. Thus, immature perceptual skills in young animals were not associated with greater learning. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 636–648, 2010
Cover Picture: Eur. J. Immunol. 5/10
Authors: Chen Yunying , Wermeling Fredrik , Sundqvist Johanna , Jonsson Ann‐Beth , Tryggvason Karl , Pikkarainen Timo , Karlsson Mikael C. I.
Published: April 2010

This issue's cover image is provided by Chen et al., the authors of “A regulatory role for macrophage class A scavenger receptors in TLR4‐mediated LPS responses” (pp. 1451–1460). The image depicts immunofluorescent staining of mouse spleen frozen sections and demonstrates that FITC‐conjugated heat‐killed E. coli are efficiently captured by spleen marginal zone macrophages – a process that is facilitated by MARCO expressed on macrophages.
Analysis of arginine and methylated metabolites in human plasma by field amplified sample injection capillary electrophoresis tandem mass spectrometry
Authors: Desiderio Claudia , Rossetti Diana Valeria , Messana Irene , Giardina Bruno , Castagnola Massimo
Published: April 2010

A CE ion trap tandem MS method was optimised for the analysis of arginine, monomethyl‐ and (symmetric and asymmetric) dimethylarginines in human plasma after a very reduced sample pretreatment step involving a simple protein precipitation with ACN. Several parameters affecting the analytes MS ionization and the capillary electrophoretic separation were carefully studied and optimised. The complete separation of arginine, monomethylarginine and symmetric and asymmetric dimethylarginine was obtained in formic acid BGE in short analysis time with high specificity due to MS2 detection of specific analytes fragments. In order to achieve the detection sensitivity suitable for the analysis of asymmetric and symmetric dimethylarginine in human plasma, the field amplified sample injection was applied. Due to stacking effects, this methodology allowed to operate a consistent on‐line preconcentration of the analytes before running the electrophoresis. The method was validated for linearity, repeatability, recovery and accuracy and applied to the quantitative analysis of arginine, monomethyl‐ and dimethylarginines in human plasma of healthy subjects.