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Two-step Procedure (two-step + procedure)
Selected AbstractsChemInform Abstract: Efficient Microwave-Assisted Two-Step Procedure for the Synthesis of 1,3-Disubstituted-imidazo[1,5-a]quinazolin-5-(4H)-ones.CHEMINFORM, Issue 18 2010Flavia Jankowski Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Two-Step Procedure for the Preparation of Mono-Protected Bis-N-heterocyclic Alkyl Ether Systems.CHEMINFORM, Issue 19 2007Jianhua Chao Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Hypervalent Iodine in Synthesis: A Novel Two-Step Procedure for the Synthesis of New Derivatives of 1H-Imidazo[1,2-b]pyrazole by the Cyclocondensation Between 5-Amino-4-cyano-3-phenyl-1H-pyrazole and ,-Tosyloxyacetophenones or ,-Haloacetophenones.CHEMINFORM, Issue 30 2005Ming Li Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of E-Aryl Ethenesulfonamides: A Simple One-Pot, Two-Step Procedure from 1-Hydroxy-1-arylalkanes.CHEMINFORM, Issue 5 2004Andrea Aramini No abstract is available for this article. [source] Two-step procedure for data-based modeling for inferential control applicationsAICHE JOURNAL, Issue 10 2000Raja Amirthalingam A two-step procedure for building an inferential control model, which uses both historical operation data and plant test data, is proposed. Motivation for using the two types of data is given, and a systematic way to combine them in the model-identification step is proposed. Some potential problems associated with the procedure in practice and their solutions are discussed. The efficacy of the procedure is demonstrated in a case study involving a multicomponent distillation column simulated in HYSYS. [source] Bis(salicylaldiminato)titanium Complexes Containing Bulky Imine Substituents: Synthesis, Characterization and Ethene Polymerization StudiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2005Antti Pärssinen Abstract A series of titanium complexes bearing two anionic [N, O,] bidentate salicylaldiminato ligands, namely bis[(N -salicylidene)anilinato]titanium(IV) dichloride (1), bis[(N -salicylidene)-2,6-dimethylanilinato]titanium(IV) dichloride (2), bis[(N -salicylidene)-2,6-di- i - propylanilinato]titanium(IV) dichloride (3), bis[(N -salicylidene)-(1-naphthalenylimino)]titanium(IV) dichloride (4), bis[(N -salicylidene)-2,6-difluoroanilinato]titanium(IV) dichloride (5), and bis[(N -3-fluorosalicylidene)-2,6-difluoroanilinato]titanium(IV) dichloride (6) have been synthesized with good yields by a two-step procedure. The X-ray structure analysis reveals that in complex 2, titanium has a distorted octahedral coordination sphere in which the oxygen atoms and the chloride ligands form the basal plane. Both the chloride and the phenoxy moieties have a cis orientation and the angle between the chloride ligands is 93.05°. The imine nitrogen atoms complete the octahedral coordination of the Ti center by occupying the axial positions. The newly synthesized (2 and 4,6) and already known complexes (1 and 3) were introduced in detailed ethene-polymerization studies. The activities achieved were low to moderate depending on the size and nature of the imino substituents. The polyethenes (PEs) produced had high molar masses, and the modalities of the molecular weight distributions varyied with polymerization temperature. Based on the results of ab initio calculations and on the experimental data obtained, an explanation for uni- and bimodal polymerization behavior and the differences in catalytic activities are given. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] 2H -Pyrrole Derivatives from an Aza-Nazarov Reaction Cascade Involving Indole as the Neutral Leaving GroupEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2008Nugzar Ghavtadze Abstract Trifluoromethyl-substituted N -indolinyl-1-aza-1,4-dien-3-ones 4, which are accessible in good yields from indolinylimino esters 6 in a two-step procedure, undergo a novel type of aza-Nazarov cyclization if treated with strong acids to give the hitherto unknown 3-hydroxy-5H -pyrrole derivatives 8a,p. The solvent-free polyphosphoric acid/acyl anhydride system as the acidic reaction medium is especially efficient and requires only short reaction times. According to quantum chemical calculations the key step in the reaction cascade is the cleavage of the N,N bond of the hydrazone fragment of a protonated N -(indolin-1-yl)-1-aza-1,4-dien-3-one intermediate such as 10. This intermediate releases 3H -indole as an unusual, but very efficient neutral leaving group. Several 1-aza-1,4-dien-3-ones 4 and some 3-hydroxy-5H -pyrrole derivatives 8 were characterized by X-ray diffraction.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Determination of refractory organic matter in marine sediments by chemical oxidation, analytical pyrolysis and solid-state 13C nuclear magnetic resonance spectroscopyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2008J. M. De La Rosa Summary Seeking to quantify the amount of refractory organic matter (ROM), which includes black carbon-like material (BC), in marine sediments, we have applied a two-step procedure that consists of a chemical oxidation with sodium chlorite of the demineralized sediments followed by integration of the aromatic C region in the remaining residues by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. The efficacy for lignin removal was tested by analytical pyrolysis in the presence of tetramethyl ammonium hydroxide (TMAH). Riverine, estuarine and offshore marine sediment samples were collected from the southwest Atlantic coast of Spain, a site of geological and environmental interest. Measured contents of BC-like material ranged between 3.0 and 45.7% of the total organic carbon. Greater relative BC contents were found in riverine sediments close to urban areas, which show an elevated input of anthropogenic organic material. The contents of BC-like material in offshore marine sediments (5.5,6.1%) were similar to those previously reported for these kinds of samples. However, NMR and pyrolysis-GC/MS of the isolated ROM reveals that abundant refractory aliphatic organic material remains in most of the marine samples after chlorite oxidation. We suggest that this pool of aliphatic carbon may play an important role as a stable carbon pool within the global C cycle. [source] Deposition of Functionalized Cr7Ni Molecular Rings on Graphite from the Liquid PhaseADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Alberto Ghirri Abstract Graphite is a clean substrate and its nanostructures hold great potential for applications. Anchoring large molecules on graphite represents a challenge for several reasons that essentially rise from the planar bonds of the packed honeycomb structure of carbon. Here, a systematic investigation by AFM and XPS on different derivatives of molecular Cr7Ni rings deposited on highly oriented pyrolytic graphite (HOPG) is reported. Cr7Ni is emerging as a prototipical example of molecular antiferromagnet on which quantum phenomena and coherence have been demonstrated. For the deposition of Cr7Ni on HOPG, two strategies are adopted: 1) Cr7Ni rings are functionalized with extended alkyl/benzene terminations and 2) a self-assembled monolayer of alkyl chains with sulfonate terminations is deposited and then a cationic Cr7Ni derivative is used. In both cases the electronic bond with the carbon surface is soft, but the two-step procedure is efficient, albeit indirect, in sticking molecular Cr7Ni on HOPG. These strategies can be easily extended to deposit other complex molecular aggregates on graphite from the liquid phase. [source] Moduli stabilization in the heterotic/IIB discretuumFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 4 2006G. Curio We consider supersymmetric compactifications of type IIB and the weakly coupled heterotic string with G resp. H -flux and gaugino condensation in a hidden sector included. We point out that proper inclusion of the non-perturbative effects changes the Hodge structure of the allowed fluxes in type IIB significantly. In the heterotic theory it is known that, in contrast to the potential read off from dimensional reduction, the effective four-dimensional description demands for consistency a non-vanishing H2,1 component if a H3,0 component is already present balancing the condensate. The H2,1 component causes a non-Kählerness of the underlying geometry whose moduli space is, however, not well-understood. We show that the occurrence of H2,1 might actually be avoided by using a KKLT-like two-step procedure for moduli stabilization. Independently of the H2,1 issue one-loop corrections to the gauge couplings were argued to cause a not well-controlled strong coupling transition. This problem can be avoided as well when the effects of world-sheet instantons are included. They will also stabilize the Kähler modulus what was accomplished by H2,1 before. [source] A two-step procedure for constructing confidence intervals of trait loci with application to a rheumatoid arthritis datasetGENETIC EPIDEMIOLOGY, Issue 1 2006Charalampos Papachristou Abstract Preliminary genome screens are usually succeeded by fine mapping analyses focusing on the regions that signal linkage. It is advantageous to reduce the size of the regions where follow-up studies are performed, since this will help better tackle, among other things, the multiplicity adjustment issue associated with them. We describe a two-step approach that uses a confidence set inference procedure as a tool for intermediate mapping (between preliminary genome screening and fine mapping) to further localize disease loci. Apart from the usual Hardy-Weiberg and linkage equilibrium assumptions, the only other assumption of the proposed approach is that each region of interest houses at most one of the disease-contributing loci. Through a simulation study with several two-locus disease models, we demonstrate that our method can isolate the position of trait loci with high accuracy. Application of this two-step procedure to the data from the Arthritis Research Campaign National Repository also led to highly encouraging results. The method not only successfully localized a well-characterized trait contributing locus on chromosome 6, but also placed its position to narrower regions when compared to their LOD support interval counterparts based on the same data. Genet. Epidemiol. 30:18,29, 2006. © 2005 Wiley-Liss, Inc. [source] Factors Affecting Plan Choice and Unmet Need among Supplemental Security Income Eligible Children with DisabilitiesHEALTH SERVICES RESEARCH, Issue 5p1 2005Jean M. Mitchell Objective. To evaluate factors affecting plan choice (partially capitated managed care [MC] option versus the fee-for-service [FFS] system) and unmet needs for health care services among children who qualified for supplemental security income (SSI) because of a disability. Data Sources. We conducted telephone interviews during the summer and fall of 2002 with a random sample of close to 1,088 caregivers of SSI eligible children who resided in the District of Columbia. Research Design. We employed a two-step procedure where we first estimated plan choice and then constructed a selectivity correction to control for the potential selection bias associated with plan choice. We included the selectivity correction, the dummy variable indicating plan choice and other exogenous regressors in the second stage equations predicting unmet need. The dependent variables in the second stage equations include: (1) having an unmet need for any service or equipment; (2) having an unmet need for physician or hospital services; (3) having an unmet need for medical equipment; (4) having an unmet need for prescription drugs; (5) having an unmet need for dental care. Principal Findings. More disabled children (those with birth defects, chronic conditions, and/or more limitations in activities of daily living) were more likely to enroll in FFS. Children of caregivers with some college education were more likely to opt for FFS, whereas children from higher income households were more prone to enroll in the partially capitated MC plan. Children in FFS were 9.9 percentage points more likely than children enrolled in partially capitated MC to experience an unmet need for any type of health care services (p<.01), while FFS children were 4.5 percentage points more likely than partially capitated MC enrollees to incur a medical equipment unmet need (p<.05). FFS children were also more likely than partially capitated MC enrollees to experience unmet needs for prescription drugs and dental care, however these differences were only marginally significant. Conclusions. We speculate that the case management services available under the MC option, low Medicaid FFS reimbursements and provider availability account for some of the differences in unmet need that exist between partially capitated MC and FFS enrollees. [source] Source density-driven independent component analysis approach for fMRI dataHUMAN BRAIN MAPPING, Issue 3 2005Baoming Hong Abstract Independent component analysis (ICA) has become a popular tool for functional magnetic resonance imaging (fMRI) data analysis. Conventional ICA algorithms including Infomax and FAST-ICA algorithms employ the underlying assumption that data can be decomposed into statistically independent sources and implicitly model the probability density functions of the underlying sources as highly kurtotic or symmetric. When source data violate these assumptions (e.g., are asymmetric), however, conventional ICA methods might not work well. As a result, modeling of the underlying sources becomes an important issue for ICA applications. We propose a source density-driven ICA (SD-ICA) method. The SD-ICA algorithm involves a two-step procedure. It uses a conventional ICA algorithm to obtain initial independent source estimates for the first-step and then, using a kernel estimator technique, the source density is calculated. A refitted nonlinear function is used for each source at the second step. We show that the proposed SD-ICA algorithm provides flexible source adaptivity and improves ICA performance. On SD-ICA application to fMRI signals, the physiologic meaningful components (e.g., activated regions) of fMRI signals are governed typically by a small percentage of the whole-brain map on a task-related activation. Extra prior information (using a skewed-weighted distribution transformation) is thus additionally applied to the algorithm for the regions of interest of data (e.g., visual activated regions) to emphasize the importance of the tail part of the distribution. Our experimental results show that the source density-driven ICA method can improve performance further by incorporating some a priori information into ICA analysis of fMRI signals. Hum Brain Mapping, 2005. © 2005 Wiley-Liss, Inc. [source] The generalizability of the Buss,Perry Aggression QuestionnaireINTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue 3 2007József Gerevich Abstract Aggressive and hostile behaviours and anger constitute an important problem across cultures. The Buss,Perry Aggression Questionnaire (AQ), a self-rating scale was published in 1992, and has quickly become the gold-standard for the measurement of aggression. The AQ scale has been validated extensively, but the validation focused on various narrowly selected populations, typically, on samples of college students. Individuals, however, who are at risk of displaying aggressive and hostile behaviours may come from a more general population. Therefore, it is important to investigate the scale's properties in such a population. The objective of this study was to examine the factorial structure and the psychometric properties of the AQ scale in a nationally representative sample of the Hungarian adult population. A representative sample of 1200 subjects was selected by a two-step procedure. The dimensionality and factorial composition of the AQ scale was investigated by exploratory and confirmatory factor analyses. Since spurious associations and increased factorial complexity can occur when the analysis fails to consider the inherently categorical nature of the item level data, this study, in contrast to most previous studies, estimated the correlation matrices subjected to factor analysis using the polychoric correlations. The resulting factors were validated via sociodemographic characteristics and psychopathological scales obtained from the respondents. The results showed that based on the distribution of factor loadings and factor correlations, in the entire nationally representative sample of 1200 adult subjects, from the original factor structure three of the four factors (Physical and Verbal Aggression and Hostility) showed a good replication whereas the fourth factor (Anger) replicated moderately well. Replication further improved when the sample was restricted in age, i.e. the analysis focused on a sample representing the younger age group, comparable to that used in the original Buss,Perry study. Similar to the Buss,Perry study, and other investigations of the AQ scale, younger age and male gender were robustly related to physical aggression. In addition, level of verbal aggression was different between the two genders (with higher severity in males) whereas hostility and anger were essentially the same in both genders. In conclusion, the current study based on a representantive sample of adult population lends support to the use of the AQ scale in the general population. The authors suggest to exclude from the AQ the two inverse items because of the low reliability of these items with regard to their hypothesized constructs. Copyright © 2007 John Wiley & Sons, Ltd. [source] Flight control of a rotary wing UAV using backsteppingINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2010Bilal Ahmed Abstract This paper presents a novel application of backstepping controller for autonomous landing of a rotary wing UAV (RUAV). This application, which holds good for the full flight envelope control, is an extension of a backstepping algorithm for general rigid body velocity control. The nonlinear RUAV model used in this paper includes the flapping and servo dynamics. The backstepping-based controller takes advantage of the ,decoupling' of the translation and rotation dynamics of the rigid body, resulting in a two-step procedure to obtain the RUAV control inputs. The first step is to compute desired thrusts and flapping angles to achieve the commanded position and the second step is to compute control inputs, which achieve the desired thrusts and flapping angles. This paper presents a detailed analysis of the inclusion of a flapping angle correction term in control. The performance of the proposed algorithm is tested using a high-fidelity RUAV simulation model. The RUAV simulation model is based on miniature rotorcraft parameters. The closed-loop response of the rotorcraft indicates that the desired position is achieved after a short transient. The Eagle RUAV control inputs, obtained using high-fidelity simulation results, clearly demonstrate that this algorithm can be implemented on practical RUAVs. Copyright © 2009 John Wiley & Sons, Ltd. [source] One-Pot, Regioselective Synthesis of Substituted Arylglycines for Kinetic Resolution by Penicillin G AcylaseADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2008Peter Grundmann Abstract Amido-alkylation of electron-rich arenes with phenylacetamide and glyoxylic acid offers an inexpensive route to a large variety of N -phenylacetylated arylglycines that are suited for immediate enzymatic resolution by penicillin G acylase. When performed under mild conditions at 5,°C in acetic acid/HCl, this simple one-pot operation resulted in the formation of single regioisomers only (,98%). Subsequent kinetic resolution of the amino acid derivatives by penicillin G acylase at pH,8.0 occurred generally with E values>100 and thus furnished free (S)-configurated arylglycines with high enantiomeric purity. The corresponding enantiopure (R)-substrates, easily separable by a phase-selective extraction process, provided the corresponding (R)-enantiomers upon conventional hydrolysis. This one-pot, two-step procedure for arylglycine synthesis, resolution and work-up requires a minimum of equipment and grants rapid access to both enantiopure (S)- and (R)-antipodes of non-natural ,-amino acids in small- to large-scale quantities. [source] Use of serial pig body weights for genetic evaluation of daily gainJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2010B. Zumbach Summary This study examined the utility of serial weights from FIRE (Feed Intake Recording Equipment, Osborne Industries, Inc., Osborne, KS, USA) stations for an analysis of daily gain. Data included 884 132 body weight records from 3888 purebred Duroc pigs. Pigs entered the feeder station at age 77,149 days and left at age 95,184 days. A substantial number of records were abnormal, showing body weight close to 0 or up to twice the average weight. Plots of body weights for some animals indicated two parallel growth curves. Initial editing used a robust regression, which was a two-step procedure. In the first step, a quadratic growth curve was estimated assuming small or 0 weights for points far away from the curve; the process is iterative. In the second step, weights more than 1.5 SD from the estimated growth curve were treated as outliers. The retained body weight records (607 597) were averaged to create average daily weight (170 443) and then used to calculate daily gains (152 636). Additional editing steps included retaining only animals with ,50 body weight records and SD of the daily gain ,2 kg, followed by removing records outside 3 SD from the mean for given age, across all the animals , the resulting data set included 69 068 records of daily gain from 1921 animals. Daily gain based on daily, weekly and bi-weekly intervals was analysed using repeatability models. Heritability estimates were 0.04, 6 and 9%, respectively. The last two estimates correspond to heritability of 28% for a 12 week interval. For daily gain averaged weekly, the estimate of heritability obtained with a random regression model varied from 0.07 to 0.10. After extensive editing, body weight records from automatic feeding stations are useful for genetic analyses of daily gain from weekly or bi-weekly but not daily intervals. [source] Preparation and characterization of PDLC films formed using a two-step procedureADVANCES IN POLYMER TECHNOLOGY, Issue 1 2007Yu-Che Hsiao Abstract A novel polymer-dispersed liquid crystal composite film was prepared using liquid crystal and dual resins, namely, UV-curable urethane diacrylate and thermo-curable epoxy, with a fixed LC content of 50 wt%. A combination treatment of UV irradiation and heat was performed in sequential steps. At first, the urethane diacrylate resin was cross-linked through UV irradiation and a pre-UV-cured film was formed. Then, the pre-UV-cured film was heat treated for curing the thermo-curable epoxy resin. As the thermal polymerization continued, LC droplets were formed and became embedded within the polymer matrix. PDLC films obtained from the polymer matrix with refractive indices in a range from 1.511 to 1.523 (1.517 ± 0.006) have optimal electro-optical properties. Films with a refractive index higher than 1.523 have high contrast ratio (CR), threshold voltage (Vth), and V90, whereas those with a low refractive index of 1.508 have low CR, Vth, and V90. In this study, we found that PDLC composite films with optimal compositions prepared by dual resins (UV/thermal) have good electro-optical properties. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:14,20, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20087 [source] A Two-Step Estimation of Consumer Adoption of Technology-Based Service InnovationsJOURNAL OF CONSUMER AFFAIRS, Issue 2 2003EUN-JU LEE Firms initially offer new technology-based services to a limited number of customers to reduce risks and maximize their returns on the investments in the new technology. Consequently, consumers' adoption of new technology-based services is restricted by the limited access provided by the businesses. A model of consumer adoption was developed and estimated via a two-step procedure. A significant sample selection bias was found with regard to access when estimating consumer adoption of a relatively new innovation, computer banking, but no such bias was found for a mature innovation, ATMs. [source] Household demand analysis of organic and conventional fluid milk in the United States based on the 2004 Nielsen Homescan panelAGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 3 2010Pedro A. Alviola IV Using the 2004 AC Nielsen panel consisting of over 38,000 households, the authors ascertain the influence of selected demographic variables associated with the purchase of organic fluid milk through the estimation of a probit model. From the use of the Heckman two-step procedure, they also calculate own-price, cross-price, and income elasticities by estimating demand relationships for both organic and conventional milk. They find that demographic factors play a crucial role in the household choice of purchasing organic milk. Furthermore, households are more sensitive to own-price changes in the case of organic milk versus conventional milk. Evidence from estimated cross-price elasticities indicates that organic and conventional milk are substitutes. However, quantities purchased of organic milk are more sensitive to changes in prices of conventional milk than vice versa. Consequently, an asymmetric pattern exists with regard to the substitution patterns of the respective milk types. Moreover, evidence indicates that organic milk is responsive to income changes, but conventional milk is not responsive to income changes. Finally, a 1% increase in the price of organic milk reduces total milk sales by 0.20%, but a 1% increase in the price of conventional milk raises total milk sales by 0.31%. [EconLit citations: C25, D12]. © 2010 Wiley Periodicals, Inc. [source] Demand for milk labels in Germany: organic milk, conventional brands, and retail labelsAGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 2 2008Astrid Jonas German milk brands have come under significant price pressure due to the introduction of retail labels at the lower price end and of organic milk as a premium product. This analysis provides elasticity estimates by milk types and analyzes sociodemographic determinants of demand. A censored system of German household demand for organic and conventional milk, further separated into retail-label and brand milk, is estimated using a two-step procedure on data from the 2000,2003 German GfK ConsumerScan Houshold Survey. Own-price elasticities of conventional milk are around unity, but the demand for organic milk is very price-elastic. Results suggest that the price of organic milk should be considered as an important marketing instrument. [JEL-Code: D12, Q11]. © 2008 Wiley Periodicals, Inc. [source] Synthesis and biological evaluation of 9-thia-5,10-dideazafolic acidJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2002Mark Wall The folate analogue, 9-thia-5,10-dideazafolic acid (3b), was obtained in an efficient two-step procedure in an overall yield of 60%. The previously unknown intermediate dimethyl-thiocarbamic acid S-(2-amino-3,4-dihydo-4-oxo-pyrido[2,3- d]pyrimidin-6-yl) ester (5) was prepared via the condensation of 2,6-diamino-3H -pyrimidin-4-one and S-(2-malonaldehyde)-1,1,3,3-tetramethylthiouronium bromide (4). Compound 5, in a one pot procedure, was deprotected using sodium hydroxide and then coupled to diethyl N -[(4-chloromethyl)benzoyl]-L-glutamate, followed by saponification of the ethyl esters to give the 9-thia-5,10-dideazafolic acid (3b). Compound 3b was a potent inhibitor of human 5-aminoimidazole-4-carboxamide ribonucleotide transformylase (Ki of 8 ± 5 ,M) and showed no inhibition of human glycinamide ribonu-cleotide transformylase at concentrations as high as 50 ,M. Compound 3b was screened by the National Cancer Institute Developmental Therapeutics Program against 60 human tumors and was found to be active against a leukemia RPMI-8226 cell line where the LC50 was 1 ,M. [source] Synthesis and biodistribution in mice of 99mTcN,DBODC,DMSEtJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 3 2009Shuye Yang Abstract Nitrido technetium(V)-mixed ligand complex of 99mTcN,DBODC,DMSEt [DMSEt: Monoethyl ester of (meso) 2,3-dimercaptosuccinic acid, DBODC: bis(2-ethoxyethyl)carbamodithioate] has been prepared in a two-step procedure by first reaction of 99mTcO with succinic dihydrazede in the presence of stannous chloride as a reducing agent and propylenediamine tetraacetic acid as a complexant, followed by the addition of DMSEt and DBODC. The complex was stable over 6,h at room temperature. The partition coefficient indicated that it was a hydrophilic complex. Biodistribution in mice demonstrated that the complex accumulated mainly in liver, lungs and kidneys. Copyright © 2009 John Wiley & Sons, Ltd. [source] N -[3-[4-(2-methoxyphenyl) piperaziny-1-yl]propyl]cyclam: synthesized as a potential 5-HT1A receptor ligand and labelled with 99mTc-nitrido coreJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 10 2008Fenglong Wang Abstract This paper reports the synthesis of new potential 5-HT1A receptor ligand N -[3-[4-(2-methoxyphenyl)piperaziny-1-yl]propyl]cyclam (MPPC) and radiolabelling of it with 99mTc-nitrido core. The novel neutral complex 99mTcN-MPPC combines 1,4,8,11-tetraazacyclotetradecane (cyclam) ligand as chelate moiety for 99mTc-nitrido with a 1-(2-methoxyphenyl)piperazine moiety derived from WAY 100635 via a 3-carbon alkyl chain. This provided a reliable and reproducible method for attaching the technetium to the pharmacophore moiety of WAY 100635. 99mTcN-MPPC was prepared by a two-step procedure and the radiochemical purity was found to be greater than 95%. It was hydrophilic and stable for at least 4,h at room temperature. In vivo stability study in normal rats showed that no degradation of 99mTcN-MPPC was found in deproteinated blood samples at 2,h post-injection. This effective 99mTc-labelling strategy for obtaining neutral 99mTc nitrido complexes would be a useful tool to prepare new SPECT agents to image 5-HT1A receptor with cyclam conjugated ligands. Copyright © 2008 John Wiley & Sons, Ltd. [source] Protein identification via ion-trap collision-induced dissociation and examination of low-mass product ionsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2008Jeremiah J. Bowers Abstract A whole-protein tandem mass spectrometry approach for protein identification based on precursor ion charge state concentration via ion/ion reactions, ion-trap collisional activation, ion/ion proton-transfer reactions involving the product ions, and mass analysis over a narrow m/z range (up to m/z 2000) is described and evaluated. The experiments were carried out with a commercially available electrospray ion-trap instrument that has been modified to allow for ion/ion reactions. Reaction conditions and the approach to searching protein databases were developed with the assumption that the resolving power of the mass analyzer is insufficient to distinguish charge states on the basis of the isotope spacings. Ions derived from several charge states of cytochrome c, myoglobin, ribonuclease A, and ubiquitin were used to evaluate the approach for protein identification and to develop a two-step procedure to database searching to optimize specificity. The approach developed with the model proteins was then applied to whole cell lysate fractions of Saccharomyces cerevisiae. The results are illustrated with examples of assignments made for three a priori unknown proteins, each selected randomly from a lysate fraction. Two of the three proteins were assigned to species present in the database, whereas one did not match well any database entry. The combination of the mass measurement and the product ion masses suggested the possibility for the oxidation of two methionine residues of a protein in the database. The examples show that this limited whole-protein characterization approach can provide insights that might otherwise be lacking with approaches based on complete enzymatic digestion. Copyright © 2007 John Wiley & Sons, Ltd. [source] The [Tc(N)(PNP)]2+ metal fragment labeled cholecystokinin-8 (CCK8) peptide for CCK-2 receptors imaging: in vitro and in vivo studiesJOURNAL OF PEPTIDE SCIENCE, Issue 4 2007Stefania Agostini Abstract The radiolabeling of the natural octapeptide CCK8, derivatized with a cysteine residue (Cys-Gly-CCK8), by using the metal fragment [99mTc(N)(PNP3)]2+ (PNP3 = N,N -bis(dimethoxypropylphosphinoethyl)methoxyethylamine) is reported. The [99mTc(N)(NS-Cys-Gly-CCK8)(PNP3)]+ complex was obtained according to two methods (one-step or two-step procedure) that gave the desired compound in high yield. The complex is stable in aqueous solution and in phosphate buffer. In vitro challenge experiments with an excess of cysteine and glutathione indicate that no transchelation reactions occur, confirming the high thermodynamic stability and kinetic inertness of this compound. Stability studies carried out in human and mouse serum, as well as in mouse liver homogenates, show that the radiolabeled compound remains intact for prolonged incubation at 37 °C. Binding properties give Kd (19.0 ± 4.6 nmol/l) and Bmax (,106 sites/cell) values in A431 cells overexpressing the CCK2-R. In vivo evaluation of the compound shows rapid and specific targeting to CCK2-R, a fourfold higher accumulation compared to nonreceptor expressing tumors. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Two-step procedure for data-based modeling for inferential control applicationsAICHE JOURNAL, Issue 10 2000Raja Amirthalingam A two-step procedure for building an inferential control model, which uses both historical operation data and plant test data, is proposed. Motivation for using the two types of data is given, and a systematic way to combine them in the model-identification step is proposed. Some potential problems associated with the procedure in practice and their solutions are discussed. The efficacy of the procedure is demonstrated in a case study involving a multicomponent distillation column simulated in HYSYS. [source] Highly magnetic latexes from submicrometer oil in water ferrofluid emulsionsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2006Franck Montagne Abstract The synthesis of functionalized submicrometer magnetic latex particles is described as obtained from a preformed magnetic emulsion composed of organic ferrofluid droplets dispersed in water. Composite (polystyrene/,-Fe2O3) particles were prepared according to a two-step procedure including the swelling of ferrofluid droplets with styrene and a crosslinking agent (divinyl benzene) followed by seeded emulsion polymerization with either an oil-soluble [2,2,-azobis(2-isobutyronitrile)] or water-soluble (potassium persulfate) initiator. Depending on the polymerization conditions, various particle morphologies were obtained, ranging from asymmetric structures, for which the polymer phase was separated from the inorganic magnetic phase, to regular core,shell morphologies showing a homogeneous encapsulation of the magnetic pigment by a crosslinked polymeric shell. The magnetic latexes were extensively characterized to determine their colloidal and magnetic properties. The desired core,shell structure was efficiently achieved with a given styrene/divinyl benzene ratio, potassium persulfate as the initiator, and an amphiphilic functional copolymer as the ferrofluid droplet stabilizer. Under these conditions, ferrofluid droplets were successfully turned into superparamagnetic polystyrene latex particles, about 200 nm in size, containing a large amount of iron oxide (60 wt %) and bearing carboxylic surface charges. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2642,2656, 2006 [source] Synthesis of block copolymers by combined ultrasonic irradiation and reverse atom transfer radical polymerization processesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2004Mustafa Degirmenci Abstract A two-step procedure based on ultrasonic irradiation and reverse atom transfer radical polymerization (RATRP) for the synthesis of block copolymers is described. In the first step of the procedure, a stable chlorine-end-capped polymer is formed upon the ultrasonic irradiation of poly(methyl methacrylate) (PMMA) in dry benzene in the presence of a copper chloride/2,2,-bipyridine catalyst. Heating the system to 110 °C initiates the polymerization of the second monomer, styrene, and this results in the formation of the block copolymers. The degradation behavior of PMMA under ultrasonic irradiation has also been studied. The agreement of the experimentally obtained molecular weights and theoretical molecular weights and the unimodal shapes of the gel permeation chromatography curves of the block copolymers indicate the controlled nature of the RATRP process initiated by polymeric radicals formed by sonication. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 534,540, 2004 [source] Dissolution and Enzymatic Degradation Studies Before and After Artificial Ageing of Silk- or Linen-Reinforced Gelatin Laminates, 1MACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2003M. Boyanova Abstract In an attempt to overcome the poor mechanical properties of native, i.e., untreated gelatin, laminates based on gelatin and gelatin/starch blend reinforced with fabrics (linen or silk) were prepared by melt pressing. The mechanical properties of fresh and artificially aged samples were reported previously. In the present series of two consecutive papers we present data concerning the dissolution and biodegradation of these laminates. A two-step procedure for treatment of the laminates was used. The first step is treatment with an aqueous buffer solution, the second with a buffered solution of the enzyme subtilisin. The time-course of the absorbance at 280 nm of the "washing" solutions was followed. A number of kinetic characteristics was determined and discussed with respect to laminate composition and their treatments. In the present Part 1 about the environmental behavior of these new biodegradable materials, the non-enzymatic solubilization in water and buffer solution (i.e., simple dissolution) of fresh and artificially aged samples is described. The dissolution process was followed spectrophotometrically as well as by the weight losses. It was found that gelatin-based silk- or linen-reinforced laminates were subject to dissolution, similarly to the gelatin and gelatin-based materials studied in previous works. In addition, it was established that the thermal treatment of the laminates during their melt pressing leads to postcondensation reactions and crosslinking of the gelatin macromolecules. Similar reactions occur between the matrix and the reinforcing element silk, thus improving their mutual adhesion. Decreased gelatin dissolution ability was observed after the thermal treatment, in the presence of reinforced fabrics and upon "additional" crosslinking with methylenedi(p -phenyl) diisocyanate. The untreated gelatin is the only one that dissolves completely in water. The artificially aged samples tend to dissolve better than the respective fresh samples due to degradation processes during aging. [source] | ||||||||||||||||||||||||||||